tài liệu Đào tạo công nhân hàn

Chng I: TNH HN CA KIM LOII. CC K HIU V THUT NG HN1. Cc t chc, hip hi:- AWS : American Welding Society (Hip hi hn M). p dng cho hn kt cu thp.- ASME : American Society Mechanical Engineers (Hip hi k s c kh M). p dng cho ch to ni hi v bnh, bn p lc.- ASTM : American Society for Testing and Meterials (Hip hi M v vn kim tra v vt liu). p dng cho vt liu v kim tra.- API : American Petrolium Institute (Vin du m Quc gia M). p dng cho ch to tc cha, bn cha.2. Cc k hiu tiu chun theo quc gia:- KS: Korean Industrial Standard (Tiu chun cng nghip Hn Quc).- JIS: Japanese Industrial Standard (Tiu chun cng nghip Nht Bn).- ANSI: American National Standard Institute (Vin tiu chun quc gia M).- DIN: Deutschs Institute for Normung (Quy phm ca vin quc gia c)3. Thut ng hn:- Hn MAG (metal active gas) l hn h quang kh bo v hot tnh: Thut ng chung cho hn h quang dng in cc dy kim loi nng chy trong kh bo v l kh hot tnh: C02, hn hp Ar v C02... - Hn MIG (metal inert gas) l hn kh tr in cc kim loi: Hn h quang bng in cc dy kim loi nng chy trong mi trng bo v bng kh tr.- Hn TIG (tungsten inert gas): Hn h quang vi in cc vonfram hoc hp kim vonfram trong mi trng bo v bng kh tr.- Flux Cored Arc Welding - (FCAW): Hn h quang dy hn c li thuc.L phng php hn h quang to ra s lin kt ca cc kim loi bng cch t nng chng bng h quang gia kim loi in y nng chy lin tc (in cc nng chy) v vt liu hn c bn. S bo v thu c t thuc hn nm bn trong li ca dy hn hnh ng.Phng php ny khng dng n kh bo v.- Gas Metal Arc Welding - (GMAW): Hn h quang kim loi trong mi trng kh.L phng php hn h quang to ra s lin kt ca cc kim loi bng cch t nng chng bng h quang gia kim loi in y nng chy lin tc (dy hn nng chy) v vt hn.Kh bo v thu c hon ton t ngun cung cp kh hoc kh trn bn ngoi. Mt vi bin i ca phng php ny c gi l MIG, CO2 hoc hn MAG- Gas Tungsten Arc Welding - (GTAW): Hn h quang in cc tungsten trong mi trng kh.L phng php hn h quang to ra s lin kt ca cc kim loi bng cch t nng chng bng h quang gia in cc Tungsten khng nng chy v vt hn. S bo v thu c t kh hoc kh trn. Phng php ny thng c gi l hn TIG.- Shielded Metal Arc Welding - (SMAW): Hn h quang tay (Hn h quang que hn c v bc). L phng php hn h quang to ra s lin kt ca cc kim loi bng cch t nng chng bng h quang gia que hn c thuc bc v vt hn. S bo v thu c t s phn hy ca thuc bc que hn khi chy. Khng s dng lc p v kim loi in y thu c t que hn.- Submerged Arc Welding (SAW): Hn h quang di lp thuc.L phng php hn h quang to ra s lin kt ca cc kim loi bng cch t nng chng cng vi mt h quang hoc nhiu h quang gia mt in cc kim loi trn hoc nhiu in cc v vt hn. H quang v kim loi nng chy c bo v bng lp chn hoc dng bt (thuc hn), l loi vt liu nng chy c ph ln trn vt hn. khng s dng n p lc to mi hn, v mt vi phn t ngun b sung (hn dy li thuc, hoc kim loi dng ht ).- X hn (Slag): T hp ca cc xt kim loi v cc tp cht khc c sinh ra trong qu trnh hn, lin kt vi nhau dng c hc l chnh, c t trng nh hn kim loi vng hn. Tnh cht ca x lng nh hng ng k n cht lng mi hn.- Tc hn (Welding speed): Chiu di ca mt lt hn trn mt n v thi gian.- Kim loi c bn (Base material) : Vt liu ca chi tit kim loi cn hn.- Vng nh hng nhit (Heat - affected zone): Vng kim loi c bn khng b nung chy ti t chc v tnh cht ca kim loi b thay i do hn v ct bng nhit gy ra.- Dy li thuc (Flux cored wire): Dy hn rng trong c in y bi thuc hn.- Kh bo v (Shielding gas): Kh c s dng ngn cn kh t kh quyn xm nhp vo mi hn bo v h quang v kim loi nng chy khi hn.II. TNH HN CA MT S KIM LOI1. Khi nim v tnh hn ca kim loi v hp kim1.1. Khi nimTnh hn ch mc d hn hay kh hn i vi mt loi vt liu no . Tnh hn l tng hp cc tnh cht ca kim loi hay hp kim cho php nhn c lin kt hn tho mn cc yu cu v cht lng cn thit.1.2. Phn loi tnh hnVt liu cn hn c quy c chia thnh bn nhm nh sau:- Vt liu c tnh hn tt: Gm cc loi vt liu cho php hn c bng nhiu phng php hn khc nhau, ch hn c th iu chnh c trong mt phm vi rng, khng cn s dng cc bin php cng ngh phc tp (nh nung nng s b, nhung nng km theo, nhit luyn sau khi hn...) m vn m bo nhn c lin kt hn c cht lng mong mun. Theo cacbon thp v phn ln thp hp kim thp u thuc nhm ny.- Vt liu c tnh hn tho mn: (hay cn gi l c tnh hn trung bnh) vt liu nhm ny ch thch hp vi mt s phng php hn nht nh, cc thng s ca ch hn ch c th dao ng trong phm vi hp. C th phi s dng mt s bin php cng ngh nh nung nng s b, gim tc ngui v x l nhit sau khi hn...Mt s mc thp hp kim thp, thp cacbon v hp kim trung bnh thuc nhm ny.- Vt liu c tnh hn hn ch; Gm nhng loi vt liu cho php nhn c cc lin kt hn vi cht lng mong mun trong cc iu kin kht khe v cng ngh v vt liu hn. Thng phi s dng cc bin php x l nhit, hoc hn trong nhng mi trng bo v c bit (kh tr, chn khng...); ch hn nm trong mt phm vi rt hp. Tuy vy, lin kt hn vn c khuynh hng b nt v d xut hin cc loi khuyt tt khc lm gim cht lng s dng ca kt cu hn.Phn ln cc loi thp cacbon cao, thp hp kim cao thuc nhm nay.f- Vt liu c tnh hn xu: gm cc vt liu rt kh hn. Thng phi hn bng cc cng ngh c bit, phc tp v tn km. T chc kim loi mi hn ti, d b bt nng v nt ngui. C tnh v kh nng lm vic ca lin kt hn thng thp hn so vi vt liu c bn. V d phn ln cc loi gang v mt s hp kim c bit.Vi s pht trin ca khoa hc cng ngh hn, ngy nay tt c vt liu u c tnh hn nht nh, ngha l u c th hn c, d cht lng c th t c rt khc nhau.2. nh gi tnh hn ca kim loi v hp kim nh gi s b tnh hn ca thp theo thnh phn ho hc ca n c th da vo mt s thng s sau y:2.1. Thng s v hm lng cacbon tng ng CEHm lng cacbon tng ng c tnh theo hm lng ca cacbon v cc nguyn t hp kim khc (Mn, Cr, Mo....) c trong thp. V d i vi thp cacbon v thp hp kim thp:Nu CE < CEth th thp c tnh hn (CEth tra trong bng vt liu)Cng c th nh gi gn ng tnh hn ca thp theo thnh phn ho hc bng cch so snh tng hp cc nguyn t hp kim H.K (%) vi hm lng ca cacbon c trong thp C (%) nh bng di y.:H.K (%)(Mn, Si,Cr,Ni...)Tnh hn ca thp theo %C

TtTho mnHn chXu

< ,1< 0,250,25 0,350,35 0,45> 0,45

1,0 3,0< 0,200,20 0,300,30 0,40> 0,4

> 3,0< 0,180,18 0,280,28 0,38> 0,38

- Mangan (Mn): khi hm lng < 1% khng nh hng nhiu n tnh hn ca thp nhng khi hm lng Mn > 1% tnh hn km i v d b nt (tng tnh thm ti).- Silic (Si): khi hm lng < 0,3% khng nh hng nhiu n tnh hn ca thp nhng khi hm lng Si > 0,3% s gy kh khn cho qu trinh hn v to nn cc loi xit kh chy v tng tnh chy long.- Crm (Cr): nh hng xu n tnh hn ca thp v n lm tng s xy ha kim loi v kt hp vi cacbon to thnh cacbit (hp cht ha hc), nng cao cngkim loi vng chuyn tip t mi hn n kim loi c bn. Tuy nhin nu chn c ch hn, vt liu hn v quy trinh cng ngh hn hp l th c th hn ch nh hng xu ca n n tnh hn.- Niken (Ni): c tc dng lm nh ht kim loi v nng cao tnh do ca thp t nh hng n tnh hn ca thp.- Molipden (Mo): gy nhiu kh khn cho qu trinh hn nh lm tng kh nng nt ngm trong mi hn, vng nh hng nhit ln, d b xy ha v chy mnh trong qu trinh hn.- Vonfram (W): lm tng cng v kh nng chu nhit nhng W lm cho tnh hn km i v n thng b xy ha mnh nn cn bo v tht tt trong qu trinh hn.- Vanadi (V) c nh hng tng t nh Vonfram.- Titan (Ti) v Niobi (Nb): ch tn ti trong thp mt lng rt nh ( < 1%) nn khng nh hng nhiu n tnh hn ca thp.- ng (Cu): vi hm lng nh (0,3 0,8%) c tc dng lm tng bn, do, dai va p v tnh chng n mn ca thp nhng t nh hng n tnh hn ca thp.- Lu hunh (S): thng gy hin tng b nng, nt nng cn Phtpho (P) thng gy hin tng gin ngui, nt ngui. l nhng tp cht c hi. Khi hm lng vt qu gii hn cho php, chng c nh hng xu n tnh hn.- Oxy (O2) trong thp thng dng oxit lm gim c tnh v lm xu tnh hn ca thp.- Nit (N2) trong thp to hp cht ha hc (nitrit st) rt cng, dn, lm gim tnh do v gy kh khn cho qu trinh hn.- Hydro (H2) l tp cht c hi, sinh kh trong vng hn, gy nt t vi trong mi hn v gy kh khn cho qu trnh hn.

II. CC PHNG PHP HN KIM LOICu to m hn TIGChc nng ca m hn TIG l dn dng in v kh tr vo vng hn. Cc m hn TIG bng tay v m hn TIG t ng c cu to tng t nhau, m hn TIG bng tay c cn cm vi cc nt iu khin, cn m hn t ng khng c cn, c thit k kp cht vo gi hn.

Cu to:1. Cap: Chui hn TIG chng thot kh bo v v c nh kim hn.2. Collet: Kp kim cu to bng ng, gi in cc khp theo c, khi vn cht chui hn s c nh kp kim, gip gi cht in cc.3. Gas orifice: ng dn kh cho php thot kh ra ngoi.4. Gas nozzle: Chp kh nh hng dng kh ln vng hn phn thnh hai loi ty theo cng hn mt loi cu to bng s cho vic hn TIG cng nh, mt loi cu to bng ng c lm mt bng nc khi thc hin hn TIG vi cng cao dng ln.5. Hoses: Cc ng cht do kt ni vi tay cm sng hn cung cp kh, nc, v cha cp in ni vi m sng hn.Chun b v s dng kim hn TIGChun b kim hn TIGTy tng loi in cc, c im mi hn m chun b in cc khc nhau. Trc khi hn mi u kim in cc c chun b thnh 3 dng: mi cu, mi nhn hoc mi t. Mi cu thng s dng vi loi in cc vonfram nguyn cht ( kin ngh s dng vi dng xoay chiu dng sng hnh Sin hoc xung vung tiu chun. To ra mi cu n gin bng cch thc hin hn vi dng xoay chiu s dng cng ph hp vi ng knh kim hn mi cu s t ng sinh ra trong qu trnh hn. ng knh ca mi cu khng c vt qu 1,5 ln ng knh in cc. Vi dng mi cu h quang thng khng n nh.Vi u mi nhn, hoc t ( s dng vi in cc thun vonfram, ceri, lanthana v thori ) nn c s dng vi dng AC inverter hoc DC. mi in cc vonfram nn s dng a mi chuyn dng ( trnh nhim bn in cc ) c ch to t borazon hoc kim cng. Ch nu mi in cc thori cn phi m bo cc bin php ht bi, qun l bi mi an ton.Cn phi mi in cc trn mi c ht mn v mi theo hng trc. c nh vy gim nh hng ca in cc nn vng hn cng nh to s n nh cho h quang.

Chiu cao mi tt nht l t 1.5 n 3 ln ng knh in cc.

Khi hn vi dng hn cng nh vi vt liu cng mng th phi mi in cc cng nhn. in cc nhn cho php hn chnh xc , h quang tp trung gim vng nh hng nhit trnh gy hin tng cong vnh mi hn c bit khi hn trn nhm. Ch khng nn s dng in cc nhn vi dng hn cao, khi s dng vi dng hn cao u mi in cc nhanh chng b mn v lm nhim bn vng hn.Khi hn vi dng hn cao hn nn lm t mi in cc, lm iu ny chng ta cng mi nhn in cc nh trn sau mi t mi in cc n ng knh khong 0.2 n 0.7mm. u in cc t s bo v in cc khi b ph hy vi dng in c mt qu cao.Cc ch khi s dng:* Cn chn dng in thch hp ( kiu v cng ) i vi kch c in cc c s dng. Dng in qu cao s lm h hi u in cc, dng in qu thp s gy ra s n mn, nhit thp v h quang khng n nh.* u in cc phi c mi hp l theo cc hng dn ca nh cung cp trnh qu nhit cho in cc.* in cc phi c s dng v bo qun cn thn trnh nhim bn.* Dng kh bo v phi c duy tr khng ch trong khi hn m cn sau khi ngt h quang cho n khi ngui in cc. khi cc in cc ngui, u in cc s c dng sng bng, nu lm ngui khng chun, u ny c th b oxy ha v c mng mu, nu khng loi b s nh hng n cht lng mi hn. Mi kt ni, c nc v kh, phi c kim tra cn thn.* Phn in cc pha ngoi m hn trong vng kh bo v phi c gi mc ngn nht, ty theo ng dng v thit b, bo m c bo v tt bng kh tr.* Cn trnh s nhim bn in cc. Khi s tip xc gia in cc nng vi kim loi nn hoc que hn, s duy tr kh bo v khng , s gy ra s nhim bn.* Thit b, c bit l u phun kh bo v, phi sch v khng dnh cc vt hn. u phun b bn s nh hng n kh bo v, nh hng n h quang, do gim cht lng mi hn.Phng php hn TIG c th hn khng dng que p, ty thuc vo dng mi ni v kim loi hn. ng thi khi hn trn vt liu mng c th dng kiu mi hn b m v hn khng que . Cng c th p dng cch hn ny cho cc mi hn kiu b g (Edge) hoc cc mi hn gc ngoi.La chn kim hn TIGVonfram l kim loi chnh ch to in cc kim hn TIG. Vonfram c la chn nh cng cng nh kh nng chu c nhit cao do dng in h quang gy ra tc ng ln in cc. Vonfram c nhit nng chy (3.410 C) cao hn tt c cc kim loi khc ( khng phi hp kim ) ch sau cacbon nu tnh tt c cc nguyn t ha hc.Cc in cc khng tiu hao dng trong hn TIG c kch c ng knh cng nh di khc nhau chng cu to t Vonfram nguyn cht, hoc hp kim vonfram vi cc nguyn t t him, hoc oxit ca chng. La chn in cc cho qu trnh hn TIG ph thuc vo vt liu vt hn, dy mi hn, s dng dng in xoay chiu hay mt chiu. Bi vit ny hy vng s gip bn la chn c ng nht loi kim hn ph hp vi mnh.

T tri qua phi: Cerium, 0.9->1.2%ThO2 Thorium, Lanthanum, Pure Vonfram, 1.8->2.2% ThO2 Thorium, Zirconium1. Kim hn thun VonframThnh phn kim hn cha n 99.5% vonfram. Kim hn ny b hao mn nhanh so vi tt c cc loi kim hn hp kim khc tuy nhin n c gi thnh r hn. Kim hn nhanh b mn khi b nung nng, cung cp dng h quang n nh khi s dng dng in xoay chiu c c tnh ng cn bng hoc hnh sin. N c bit tt vi hn vi vt liu nhm v magie. Tuy nhin n khng thng c s dng vi dng hn mt chiu.2. Kim hn Vonfram vi 2% ThoriKim hn vonfram c cha thori oxit cha ti thiu 97.3% vonfram v t 1.7 n 2.2% thori. Chng c s dng ph bin nht trong cc loi kim hn TIG v tui th cng nh tnh d s dng ca n. Thori gip tng kh nng pht x in t ca in cc, do n gip m h quang d dng, cng nh kh nng chu ng dng h quang cao. N cng c kh nng cung cp mi hn sch hn cc in cc khc.Khc vi in cc Vonfram tinh khit, cc in cc c thori ch c s dng vi dng in xoay chiu khi hn vi vt hn nhm mng, hoc cc vt liu c dy di 0.6 inch. Tuy nhin chng c bit ph hp vi vic hn s dng dng mt chiu in cc thun trn cc vt liu thp carbon hoc thp khng g, nickel hoc cc vt hn titan.Trong qu trnh sn xut in cc Thori c phn tn u trn ton b kim hn, iu ny cho php in cc duy tr c u nhn in cc hn, iu ny l l tng cho hn cc vt hn mng. Tuy nhin chng ta cn ch Thori l phng x do , bn phi lun lun tun th theo cc khuyn co ca nh sn xut trong qu trnh s dng.3. Kim hn l hp kim vi CeriKim hn tig c th l hp kim ca Vonfram vi Ceri trong Vonfram chim ti thiu 97.3% v 1.8 n 2.2 % Ceri. in cc ny hot ng tt nht vi cc dng hn mt chiu ti ch hn thp. N cng c th s dng tt vi dng hn mt chiu hoc xoay chiu. Vi c tnh bt u h quang vi c dng in thp. in cc Ceriated tr ln ph bin i vi cc ng dng nh hn ng, tm kim loi mng hoc lm vi cc b phn nh, tinh t. Ging nh in cc thoriated, n c th s dng tt vi thp carbon, thp khng g, thp niken v titan, do n c th l in cc thay th hon ho cho in cc thoriated 2%.in cc Ceriated c cc khc bit khng ng k so vi in cc thoriated. Vic s dng in cc Ceriated vi dng hn cao khng c khuyn khch do nhit u in cc c th ph hng cc u im ca oxit Ceri mang li.4. Kim hn hp kim vi 1.5% LanthanKim hn TiG vi hp kim vonfram vi Lanthan Oxit cha ti thiu 97.8% vonfram v t 1.3% n 1.7% Lanthan oxit hoc Lanthan. in cc ny c kh nng to h quang tt, tc hao mn thp, cha rt nhiu u im ging nh in cc Ceriated. N cng c cc c tnh nh in cc Thoriated m trong mt s trng hp n c th thay th in cc ny m khng phi thay i chng trnh hn.in cc hp kim Lanthanated l l tng nu bn mun ti u kh nng hn ca bn. N c th lm vic tt vi dng AC, cng nh DC in cc thun, tuy nhin in cc c th b nh hng nu dng vi dng hn xoay chiu sng hnh sin. Lathan oxit c phn b u trn in cc kim hn TIG trong qu trnh sn xut, iu ny gip cho vic duy tr u nhn in cc, to u th tt khi hn thp v thp khng r vi dng hn mt chiu hoc dng hn xoay chiu vi sng vung.Khng ging in cc hp kim vi thori cc in cc hp kim lathana tng thch vi hn xoay chiu nh in cc hp kim ceri, n cho php hn h quang vi in p thp. i vi din cc vonfram nguyn cht in cc hp kim lanthana c kh nng chu tng 50% dng in ti.5. in cc vi hp kim zirconi (ZrO2)in cc Vonfram vi Zirconi cha ti thiu 99.1% vonfram v t 0.15% n 0.4% Zirconi. in cc ny cung cp h quang cc k n nh v chng li s nhim bn vonfram. N c th hn vi cc c im bng hoc hn so vi in cc hp kim vi thori khi hn vi dng xoay chiu. Trong mi trng hp th nn s dng in cc ny vi dng in mt chiu.Kt lunin cc kim hn TIG ca vonfram vi cc kim loi hoc oxit t him cung cp cho kim hn in cc cc kh nng lm vic tt vi dng in xoay chiu cng nh mt chiu vi h quang n nh, hao mn kim hn gim i, cng nh gim kch thc kim hn, cng nh chu c dng hn cao hn, nhim bn vonfram thp hn so vi in cc thun vonfram.

K thut gy v kt thc h quang khi hn queVic gy h quang c tin hnh thng qua tip xc u que hn vi vt hn trong thi gian ngn. Do tc dng ca dng ngn mch v in tr tip xc, u que hn c nung nhanh ti nhit cao. Khi nhc u que hn ra khong khng gian gia u que hn v vt hn s b ion ha, to thnh h quang.C hai phng php gy h quang:Phng php qut.Phng php qut l phng php d thc hin vi nhng ngi mi bt u v khi s dng vi my hn xoay chiu. Qut que hn ging nh khi bn nh mt que dim; Nhc in cc ln mt khong cch ko di h quang ln mt on ri quay tr li chiu cao bnh thng h quang hn.

Phng php gPhng php ny mi h quang bng g vung gc que hn vi vt hn sau khi c h quang, ko di h quang trc khi v chiu di h quang bnh thng. Mt khi hnh thnh.

Bt u h quangKhi mi bt u hn nhit vt hn cn thp, nn su nng chy phn ny tng i nng, v vy lc bt u hn, sau khi bt h quang nn ko di h quang hn gia nhit vt hn nng ln, sau mi dn dn h thp v chiu di h quang thch hpDuy tr h quangH quang thng c duy tr chiu di 0.5 n 1.2 ln ng knh que hn, ty theo iu kin hn v loi que hn ( que hn c v bc bazo cn c chiu di h quang nh ).Kt thc h quang hnKhi kt thc h quang iu quan trng l phi in ng quy cch ming hn. y l khu vc cha nhiu tp cht c hi nht do tc kt tinh nhanh ca kim loi , v vy kh nng hnh thnh vt nt ti l rt cao. Cch kt thc h quang ng quy cch l tng dn chiu di chiu di h quang sau khi dng mi chuyn dng khc ca que hn ngt h quang t t.Ch : khi h quang b tt ngu nhin hoc thay que hn, cn gy li h quang ch cha nng chy, cch ming hn khong 1cm, ri cho h quang hn ngc li nung chy phn ming hn ni h quang va tt, sau tip tc hn theo hng cn thit.

1. K thut hn h quang tay mi hn v tr spHn sp l v tr hn thun li, d thao tc nht. Cht lng mi hn khi hn sp cao v iu kin thot kh tt, v cc tp cht d tch ra khi vng hn. Mt khc khi hn sp d quan st v theo di c s hnh thnh mi hn. Hn sp cng l v tr hn ph bin nht trong sn xut, v l v tr c bn nht ngi cng nhn phi thc hin c.Trc khi hn cn chun b vt hn, lm sch v tr hn. Chng ta c th vt mp mt pha hoc hai pha ty thuc v dy ca vt hn. m bo phng b mt gia cc chi tit v m bo khe h gia cc chi tit th vic g phi m bo chc chn.Cc quy nh v hn nh:- Hn nh phi chc chn, cht lng mi hn nh phi nh mi hn chnh.- Khong cch gia cc mi hn nh vo khong 40-50 ln dy vt hn nhng khng c vt qu 300mm.- Chiu di mi hn nh vo khong 3-4 ln dy vt hn v khng c vt qu 30mm.- Cng dng in hn nh phi ln hn cng dng in hn chnh 10-15%.- Sau khi hn nh cn nn sa li vt hn v vt hn c th b bin dng khi hn nh.Chn ng knh que hn v cng dng in hnng knh que hn v cng dng in hn chn theo bng trong s tay hoc c th tnh theo cng thc Mi 1 Amp tng ng vi 0.0254 mm ng knh que hn. Hoc chn dng hn mc thp sau iu chnh tng 5 n 10 Amp ri xem xt kh nng hn cho ph hp.Gc nghing que hn: Que hn nghing u sang hai pha ca cnh hn v nghing vi hng hn mt gc 70-80 nh hnh di:

Chuyn ng que hn:- Hn lin kt gip mi vt hn mng c khe h nn chuyn ng que hn theo ng thng.- Hn mi hn nhiu lp th lp th nht ln dng ng knh que t 3-4mm, vi chuyn ng theo ng thng. T lp th 2 tr nn chuyn ng que hn theo hnh rng ca, bn nguyt...Ch : Mi hn c chiu di khc nhau, c th p dng cc cch hn khc nhau:- Mi hn ngn di 250mm. Hn lin tc mt mch t u n cui theo cng mt hng.- Mi hn trung bnh t 250mm n 1000mm Hn tin hn t gia ra hai u theo kiu ngt bc ( chia ng hn ra thnh nhiu phn nh chiu di 100-350mm sao cho mi ln hn ht mt que hn ).- Mi hn di trn 1000mm Hn c tin hnh t gia ra hai u theo kiu ngt bc v c th dng hai cng nhn hn cng lc.

2. Cc li trong k thut thao tc hn h quang tay:Cng nhn hn nhn bit c u l mi hn p, u l mi hn li v nhn vo mi hn khng th bit c li g hiu chnh my v thao tc.- Mi hn p: cao u t x v khng c hoc t kim loi bn te ra xung quanh. - Mi hn li khi di chuyn que hn qu nhanh: mi hn nhp nh t qung, x kim loi lng bn te nhiu.

- Mi hn li do di chuyn qu chm: ng hn rng, cao. - Mi hn li do h quang qu ngn: ng hn khng ng u, c hin tng dnh que. - Mi hn li do h quang qu cao: ng hn b ngt qung, hnh dng khng u. - Mi hn li do dng hn qu cao: ng hn rng, phng v khng lin tc - Mi hn li do dng qu thp: ng hn cao, khng ngu

3. Cc dng dao ng que hn trong hn h quang tay:

Khi hn h quang tay ( hn que ) mun hnh thnh mi hn ngi th phi a que hn p ng 3 chuyn ng: a dc trc que hn t trn xung di, a dc trc mi hn nhm hn ht chiu di mi hn, a que hn dao ng ngang mi hn nhm m bo chiu rng mi hn.Dng dao ngng dng

Dao ng thngQue hn khng dao ng. B rng mi hn bng 0.5 n 1.5 ln ng knh que hn. Dng hn kim loi mng, hn lp lt trong mi hn nhiu lp, hn p.

Dao ng hnh rng caKhng ch c tnh lu ng ca kim loi nng chy v khng ch rng cn thit cho mi hn, do to hnh mi hn tt. dao ng ny thng dng trong hn bng, hn ng, hn ng, hn trn cc mi hn gip mi v hn gc.

Dao ng tam gicGiao ng ny thch hp khi hn vt cnh v tr hn ngang v hn gc v tr hn bng v hn trn, hn hnh tam gic cn thch hp khi hn ng c vt cnh v hn ng mi hn gc.

Dao ng rnh vungDao ng rnh vung tng cng gia nhit cho c hai bn mp hn. hn mt mt mi hn hnh ch T c vt cnh

Dao ng hnh s 8a que hn hnh s 8, c s dng hn mi hn gc mt lp, bo m gia nhit u c hai mp cnh.

Dao ng na trnC tc dng ch t nng mt cnh mp hn, c s dng khi hn cc chi tit kt cu c chiu dy khc nhau.

Dao ng trnDao ng ny gip kim loi nng chy c nhit cao, m bo cc kh tan trong vng hn c dp thot ra v x hn ni ln. c s dng trong mi hn tng i dy v tr bng

Dao ng trn ca que hn hnh trn c gip tm mi hn c nung nng, thng s dng n khi kt thc mi hn.

K thut bo qun que hn

bo m cht lng mi hn cn quan tm n vic bo qun que hn. phi sy li que hn theo ng hng dn ca nh sn xut trc khi s dng.Bo qun que hn bazo t hidro: y l loi que hn khng cha cc cht hu c v cc thnh phn cha nc. Que bazo thng ng trong cc hp nh bng nha kn hon ton. sau khi b ra m khng dng ht, th trc khi hn cc que ny cn phi sy.Bo qun que hn loi khc: Que hn thng c ng trong trong cc hp cactong hoc cc hp nha nhng khng kn hon ton.Que hn nu c bo qun tt c th gi c kh nng lm vic trong 2 nm.Ch sy mt s loi que hn:

Mt s im cn lu khi sy v bo qun que hn: L sy que hn cng loi thng khng dng chung cho que hn t hydro v que hn khc, do khong nhit sy khc nhau ca chng Nu que hn t hydro thuc nhm bn khc nhau c sy trong cng mt l sy, nn chn nhit sy cao nht c th c. Tuy nhin, thun tin v tit kim, nn dng cc l sy khc nhau cho que hn thuc cc nhm bn khc nhau bo m sy ng v trnh ln ln. Nn trnh sy qu 2 ting ng h nhit trn 350oC hoc qu 1 ting ng h nhit trn 400oC, v fero kim loi trong v bc c th b oxi ha v v bc b gin qu mc. Ngoi ra, nng oxi trong kim loi mi hn tng ln khi lng silic v mangan b gim. Khng nn vt qu gii hn thi gian dnh cho vic sy li que hn v bn v bc c th b gim. V vy m cn c l lu gi que hn trong lc vn chuyn chng qu gii hn thi gian. Khng c gii hn thi gian no cho vic lu gi que hn nhit 150oC Vic ng m l sy thng xuyn ly que hn kh ra dng v a que hn mi vo sy c th lm cho que hn khng c sy ng cch. Do , nn s dng cc l lu gi thng xuyn ly que hn kh ra em dng sau ng li. Trnh sy ngay lp tc cc que hn b m t nhit cao. trnh v v bc, que hn phi c sy kh 100oC trong khong na gi ng h trc khi c a vo l sy. Khng dng l sy que hn vo vic khc. bo m cht lng mi hn, cn khng ch thi gian lu que hn t hydro ngoi khng kh sau khi c sy trong l sy hoc sau khi c ly ra khi l lu gi cho n khi chng c em i hn. C th tham kho cc ch theo bng sau:Thi gian lu que hn baz nhit lu gi sau khi sy, trc khi hnNhm que hn m tng i 90% (tri m) m tng i 50% (tri kh)

E70XX4 h8 h

E80XX2h8 h

E90XX1 h4 h

E0XX/110XX0,5 h2 h

Cc loi phch sy que hn weldcom cung cp: Cc Loi Khuyt Tt Hn v Cch Phng TrnhCc khuyt tt hn do rt nhiu nguyn nhn gy ra. N c lin quan ti cc mt nh: kim loi hn, ch hn v quy trnh cng ngh. S tn ti ca nhng khuyt tt s nh hng trc tip n bn ca u mi hn. Do , ngi th hn phi chn quy phm hn chnh xc v nghim chnh chp hnh cc quy trnh hn.Mi Hn c nhiu loi khuyt tt, sau y l cc khuyt tt thng gp phi v cch phong trnh:1. NtNt l mt trong nhng khuyt tt nghim trng nht ca lin kt hn. trong qu trnh s dng cu kin hn, nu mi hn c vt nt th vt nt s rng dn ra lm cho kt cu b hng.Theo nhit vt nt xut hin m phn ra hai loi:Nt nng: xut hin trong qu trnh kt tinh ca lin kt hn khi nhit kh cao ( trn 1000 C ).Nt ngui: xut hin sau khi kt thc qu trnh hn vi nhit di 1000 C. Nt ngui c th xut hin vi gi hoc thm ch vi ngy sau khi hn.Theo kch thc vt nt c th phn loi thnh:Nt th i: c th gy ph hy kt cu ngay khi lm vic.Nt t vi: Vt nt ny s pht trin rng dn ra to thnh cc vt nt th i.Cch kim tra pht hin vt nt:Cc vt nt th i c th pht hin bng mt thng hoc qua knh lp. Cc vt nt t vi v nm bn trong mi hn ch c th dng cc phng php kim tra nh siu m mi hn, t tnh, chp X quang... pht hin chng.

Mt s phng php hn ch s pht sinh vt nt trong mi hn.Dng Vt NtPhng php kim traNguyn nhnGii php phng trnh

Nt dc1. Bng mt thng2. Dng bt t3. Dng cht ch th mu4. Chp X quang5. Siu m1. S dng vt liu hn cha ng.2. Tn ti ng sut d ln trong lin kt hn.3. Tc ngui cao4. Lin kt hn khng hp l.5. B tr cc mi hn cha hp l1. S dng vt liu hn ph hp.2. Gii phng cc lc kp cht cho lin kt hn khi hn. Tng kh nng in y ca vt liu hn.3. Gia nhit trc cho vt hn, gi nhit cho lin kt hn gim tc ngui.4. S dng lin kt hn hp l, vt mp gim khe h gia cc vt hn ...5. B tr so le cc mi hn.

Nt vng gy v kt thc h quang-nt-1. V tr kt thc h quang b lm, tn ti nhiu tp cht.2. H quang khng c bo v tt.1. S dng thit b hn ph hp, c ch ring cho lc g v kt thc h quang.2. S dng cc bn ni cng ngh v tr bt u v kt thc h quang, cc vt nt ny nm ngoi lin kt hn.

Nt ngan-nt-1.S dng vt liu hn cha ng.2. Tc ngui cao.3. Mi hn qu nh so vi lin kt.1. S dng vt liu hn ph hp.2. Tng dng in v kch thc in cc hn.3. Gia nhit trc khi hn.

2. R khR kh sinh ra do hin tng kh trong kim loi khng kp thot ra ngoi trc khi kim loi ng c.R kh c th sinh ra bn trong hoc b mt mi hn, R kh c th nm phn ranh gii gia kim loi c bn v kim loi p.

S tn ti ca r kh trong mi hn s lm gim tit din lm vic, gim cng chu lc v kn ca lin kt.Nguyn nhn:- Hm lng cacbon trong kim loi c bn hoc trong vt liu hn qu cao.- Vt liu hn b m; b mt chi tit hn b bn, dnh sn, du m, g, hi nc ...- Chiu di ct h quang ln, tc hn qu cao.Bin php phng trnh vi hin tng r kh:- Dng vt liu hn c hm lng cacbon thp.- Lm sch v sy kh vt liu hn trc khi hn.- Gi chiu di ct h quang ngn, gim tc hn.- Nu s dng kh bo v mi hn, phi m bo h thng cp kh sch v hot ng tt, lu lng khlaf ph hp.- Nu hn t ng di lp thuc bo v, thuc hn phi m bo khng b m, cp thuc y trong qu trnh hn.3. Ln x hay ket xLn x ( hoc mt s tp cht khc ) y cng l mt dng khuyt tt ph bin, x hn v tp cht c th tn ti trong mi hn, cng c th nm trn b mt mi hn, c th nm gip ranh gia kim loi mi hn v phn kim loi c bn, hoc gia cc lt hn.

Ln x nh hng ln n bn, dai va p v tnh do ca kim loi, mi hn, gim kh nng lm vic ca kt cu di tc dng ca trng ti ng.Nguyn nhn:- Dng in hn qu nh, khng nhit lng cung cp cho kim loi nng chy v x kh thot ln khi vng hn.- Mp hn cha c lm sch hoc khi hn nh hay hn nhiu lp cha g sch x.- Gc hn cha hp l v tc hn qu ln.- Lm ngui mi hn qu nhanhBin php phng trnh:- Tng dng in hn cho thch hp. Hn bng h quang ngn v tng thi gian dng li ca h quang.- Lm sch vt hn trc khi hn, g sch x mi hn nh cc lp hn.- Thay i gc v phng php a in cc hn cho hp l, gim tc hn.4. Khuyt tt hn khng nguHn khng ngu l loi khuyt tt nghim trng trong lin kt hn. N s gy ra s nt v hng kt cu hn. Hn khng ngu sinh ra gc mi hn, mp hn hoc gia cc lp hn.

Nguyn nhn- Mp hn chun b cha hp l. gc vt qu nh.- Dong in hn qu nh hoc tc hn qu nhanh- Gc in cc hn ( que hn ) v cch a in cc khng hp l.- Chiu di ct h quang khng qu ln.- in cc hn chuyn ng khng ng theo trc mi hn.Bin php phng trnh:- Lm sch lin kt trc khi hn, tng gc vt v khe h hn.- Tng dng in hn v gim tc hn, v.v...5. Lm Chn v Chy LoangLm chnLm chn l phn b lm thnh rnh dc theo ranh gii gia kim loi c bn v kim loi p.Lm chn lm gim tit din lm vic ca lin kt, to s tp trung ng sut cao v c th dn n s hy ca kt cu trong qu trnh s dng.Nguyn nhn:- Dng in hn qu ln- Chiu di, ct h quang ln- Gc que hn v cch a que hn cha hp l- S dng cha ng kch thc in cc hn ( qu ln ).Chy LongChy loang l hin tng kim loi lng chy loang trn b mt ca lin kt hn.,Chy loang l hin tng kim loi lng chy loang trn b mt ca lin kt hn.Chy loang to ra s tp trung ng sut, lm sai lch hnh dng ca lin kt hn.Nguyn Nhn:- Gc nghing que hn khng hp l- Dng in hn que cao- T th hn v cch t vtj hn khng hp l.6. Khuyt tt v hnh dng lin kt hnLoi khuyt tt ny bao gm nhng sai lch v hnh dng mt ngoi ca lin kt ngoi ca lin kt hn, lm n khng tha mn vi cc yu cu k thut v thit k.

Nguyn nhn:- Gp lp v chun b mp hn cha hp l- Ch hn khng n nh- Vt liu hn khng m bo cht lng- Trnh cng nhn qu thp, v.v...Ngoi cc loi khuyt tt trn cn c cc loi khuyt tt khc nh qu nhit v bn te.Qu Nhit: Khuyt tt ny xut hin do vic chn ch hn khng hp l lm cho kim loi p v cng nh hng nhit c cu to ht rt th, c tnh ca lin kt hn b gim.Bn te: Khuyt tt ny l hin tng bn te kim loi ln vt liu hn, do vt liu hn khng m bo cht lng, thiu kh bo v hoc s dng khng ng loi kh. Gy mt thm m lin kt hn, tn cng sc lm sch v.v...Ni chung cc loi khuyt tt hn sau khi pht hin c nu qu trnh cho php th phi:- c b phn kim loi c khuyt tt;- Hn sa cha v kim tra li;- Ring i vi vt nt cn phi khoan chn 2 u vt nt hn ch s pht trin ca vt nt, loi b trit v hn sa cha li.- Khc phc khuyt tt qu nhit bng phng php nhit luyn khi phc li kch thc ht ca kim loi mi hn v vng nh hng nhit.

II. Cc loi vt liu ng ng p dng trong Nh my m Ph M:1. Piping classPhn nhmLu cht cng ngh K hiuCp chu pVt liuGhi ch

B14CAmmonia LiquidNHL150 RFK.C.S. (PWHT); A333Gr.6Am lng

B18ACooling Tower Water Return (aboveground)CTR150 FFFIBER GLASSNc sng lm mt

Cooling Tower Water Supply (aboveground)CTS150 FFFIBER GLASSNc sng lm mt

River Water (aboveground)WR150 FFFIBER GLASSNc sng lm mt

B18Z150 FFC.S. CEMENT LINEDCc ng ng cacbon bc xi mng bn ngoi

B18GCooling Tower Water Return (underground)CTR150 FFFIBER GLASSNc sng lm mt

Cooling Tower Water Supply (underground)CTS150 FFFIBER GLASSNc sng lm mt

River Water (underground)WR150 FFFIBER GLASSNc sng lm mt

B20GFire Water (underground)WF150 RFC.S.Nc cu ha

B24BAmmonia FlareNHV150 RFC.S.Am hi ra uc

Atmospheric Vent from Tank (Urea)TU150 RFC.S.ng x kh trong bn cha ra mi trng

Blowdown WaterWBD150 RFC.S.1.5 mm

Boiler Feed WaterWBF150 RFC.S.1.5 mm

Carbon DioxideCD150 RFC.S.1.5 mm

Fire Water (aboveground)WF150 RFC.S.1.5 mm

Fresh Cooling Water Return (aboveground)FCR150 RFC.S.1.5 mm

Fresh Cooling Water Supply (aboveground)FCS150 RFC.S.1.5 mm

Fuel Gas (LP)FUG150 RFC.S.1.5 mm

Hydrocarbon FlareHCV150 RFC.S.1.5 mm

HydrogenH2150 RFC.S.1.5 mm

L.P. Washing Condensate (Urea)LW150 RFC.S.1.5 mm

B24BLow Press. Sat.d Steam (Urea)LSS150 RFC.S.1.5 mm

Low Pressure SteamLS150 RFC.S.1.5 mm

Lubrication OilLO150 RFC.S.1.5 mm

MDEA SolutionMD150 RFC.S.1.5 mm

Medium/Low Press. Sat.d Steam (Urea)MLS150 RFC.S.1.5 mm

Natural GasNG150 RFC.S.1.5 mm

NitrogenN2150 RFC.S.1.5 mm

Process AirAPR150 RFC.S.1.5 mm

Process GasGP150 RFC.S.1.5 mm

Service WaterWS150 RFC.S.1.5 mm

Urea Process (Urea)UP150 RFC.S.1.5 mm

Waste GasGW150 RFC.S.1.5 mm

Waste WaterWW150 RFC.S.1.5 mm

Water CondensateWC150 RFC.S.1.5 mm

Water Process CondensateWCP150 RFC.S.1.5 mm

B24CMDEA SolutionMD150 RFC.S. (PWHT)1.5 mm

B24ECompressed/Plant AirAC150 RFC.S.3.0 mm

Oily WaterWO150 RFC.S.3.0 mm

Waste WaterWW150 RFC.S.3.0 mm

B24GOily Water Sewer (Underground)OS150 RFC.S.3.0 mm

B24UFresh Cooling Water Return (underground)FCR150 RFC.S.1.5 mm

Fresh Cooling Water Supply (underground)FCS150 RFC.S.1.5 mm

B40ZCarbon DioxideCD150 RFAISI-304L0 mm

B50AChemicals Treatment WaterWT150 RFAISI-3040 mm

Demineralized WaterWD150 RFAISI-3040 mm

Fuel Gas (LP)FUG150 RFAISI-3040 mm

Lubrication OilLO150 RFAISI-3040 mm

MDEA SolutionMD150 RFAISI-3040 mm

Process AirAPR150 RFAISI-3040 mm

Waste WaterWW150 RFAISI-3040 mm

Water Process CondensateWCP150 RFAISI-3040 mm

D14BAmmonia GasNHG300 RFK.C.S.1.5 mm

Blow Down Vent (Urea)BD300 RFK.C.S.1.5 mm

D14CAmmonia LiquidNHL300 RFK.C.S. (PWHT)1.5 mm

D24BAmmonia GasNHG300 RFC.S.1.5 mm

Ammonia Water SolutionNHW300 RFC.S.1.5 mm

Carbon DioxideCD300 RFC.S.1.5 mm

Fuel Gas (HP)FUG300 RFC.S.1.5 mm

HydrogenH2300 RFC.S.1.5 mm

Low Pressure SteamLS300 RFC.S.1.5 mm

M.P. Condensate, 22 Barg (Urea)MC300 RFC.S.1.5 mm

M.P. Washing Condensate (Urea)HW300 RFC.S.1.5 mm


Medium Press. Sat.d Steam (Urea)MSS300 RFC.S.1.5 mm

Medium Pressure Steam (Urea)MS300 RFC.S.1.5 mm




Synthesis GasSG300 RFC.S.1.5 mm


D24CAmmonia LiquidNHL300 RFC.S. (PWHT)1.5 mm

MDEA SolutionMD300 RFC.S. (PWHT)1.5 mm

D24EProcess GasGP300 RFC.S.3.0 mm

D34CLow Pressure SteamLS300 RF1.25-CHROME (PWHT)1.5 mm

Process GasGP300 RF1.25-CHROME (PWHT)1.5 mm

D50AMDEA SolutionMD300 RFAISI-3040 mm

Process AirAPR300 RFAISI-3040 mm

Process GasGP300 RFAISI-3040 mm


F24BBlowdown WaterWBD600 RFC.S.1.5 mm

Boiler Feed WaterWBF600 RFC.S.1.5 mm

High Pressure SteamHS600 RFC.S.1.5 mm





F24BSteam ProcessSP600 RFC.S.1.5 mm


F24EProcess GasGP600 RFC.S.3.0 mm

F34BNatural GasNG600 RF1.25-CHROME1.5 mm

F34CProcess GasGP600 RF1.25-CHROME (PWHT)1.5 mm

F50AChemicals Treatment WaterWT600 RFAISI-3040 mm

MDEA SolutionMD600 RFAISI-3040 mm

Process GasGP600 RFAISI-3040 mm


F64AProcess AirAPR600 RTJAISI-321H0 mm

G24BAmmonia Water SolutionNHW900 RTJC.S.1.5 mm

Synthesis GasSG900 RTJC.S.1.5 mm

G36BNatural GasNG900RTJ2.25-CHROME1.5 mm

H24BAmmonia Water SolutionNHW1500 RTJC.S.1.5 mm

Blowdown WaterWBD1500 RTJC.S.1.5 mm

Boiler Feed WaterWBF1500 RTJC.S.1.5 mm

Process GasGP1500 RTJC.S.1.5 mm

Synthesis GasSG1500 RTJC.S.1.5 mm

Very High Pressure SteamKS1500 RTJC.S.1.5 mm

Water Process CondensateWCP1500 RTJC.S.1.5 mm

H24CAmmonia LiquidNHL1500 RTJC.S. (PWHT)1.5 mm

H24EProcess GasGP1500 RTJC.S.3.0 mm

H24JBoiler Feed WaterWBF1500 RTJC.S.1.5 mm

Very High Pressure SteamKS1500 RTJC.S.1.5 mm

H34QSynthesis GasSG1500 RTJ1.25-CHROME (PWHT)1.5 mm

H36QProcess GasGP1500 RTJ2.25-CHROME (PWHT)1.5 mm

Synthesis GasSG1500 RTJ2.25-CHROME (PWHT)1.5 mm

H50AChemicals Treatment WaterWT1500 RTJAISI-3040 mm

H66ASynthesis GasSG1500 RTJAISI-347H0 mm

J36BVery High Pressure SteamKS2500 RTJ2.25-CHROME1.5 mm

J52MHigh Pressure Washing CondensateKW

Caustic SodaCA

Carbonate Closed Drain (Urea)CDR

B40AUrea Closed Drain (Urea)CU150 RFAISI-304

Acid Water (Urea)CY

Low Pressure CondensateLC

Steam TracingDM

Sulphuric Acid 98%SA

PHN LOI VT LIU THP THEO ASTM:Vt liu ngPh kin ngMt bchVanBulng& ai c

Thp cc bon (Carbon Steel)A106 Gr AA234 Gr WPAA105A216 Gr WCBA193 Gr B7A194 Gr 2H

A106 Gr BA234 Gr WPBA105A216 Gr WCB

A106 Gr CA234 Gr WPCA105A216 Gr WCB

Thp hp kim nhit cao (Carbon Steel Alloy, High-Temp)A335 Gr P1A234 Gr WP1A182 Gr F1A217 Gr WC1A193 Gr B7A194 Gr 2H

A335 Gr P11A234 Gr WP11A182 Gr F11A217 Gr WC6



A335 Gr P5A234 Gr WP5A182 Gr F5A217 Gr C5

A335 Gr P9A234 Gr WP9A182 Gr F9A217 Gr C12

Thp hp kim nhit thp (Carbon SteelAlloy Low-Temp)A333 GR 6A420 Gr WPL6A350 Gr LF2A352 Gr LCBA320 Gr L7A194 Gr 7

A333 Gr 3A420 Gr WPL3A350 Gr LF3A352 Gr LC3

Thp khng r (Austenitic StainlessSteel)A312 Gr TP304A403 Gr WP304A182 Gr F304A182 Gr F304A193 Gr B8A194 Gr 8

A312 Gr TP316A403 Gr WP316A182 Gr F316A182 Gr F316



Thnh phn ha hc ca tng loi thp:Thp A106Grade AGrade BGrade C

Carbon, max. %0.25 (1)0.30 (2)0.35 (2)

Manganese %0.27-0.930.29-1.060.29-1.06

Phosphorus, max. %0.0350.0350.035

Sulfur, max. %0.0350.0350.035

Silicon, min. %0.100.100.10

Chrome, max. % 0.400.400.40

Copper, max. % 0.400.400.40

Molybdenum, max. % 0.150.150.15

Nickel, max. %0.400.400.40

Vanadium, max. %0.080.080.08

StandardASTM A333

GradeGrade 1Grade 3Grade 4Grade 6Grade 7Grade 8Grade 9Grade 10Grade 11

Chemical Composition C0.300.190.120.300.190.130.200.200.10

Si0.180.37 0.180.37 0.100.130.32 0.130.32 0.100.35 0.35

Mn0.401.06 0.310.640.501.05 0.291.06 0.900.900.401.06 1.151.50 0.6

P0.0250.0250.0250.0250.0250.0250.0250.030.025

S0.0250.0250.0250.0250.0250.0250.0250.0150.025

Cr0.441.01 0.150.50

Ni3.183.820.470.98 2.032.57 8.409.60 1.602.24 0.2535.037.0

Cu0.400.75 0.751.25 0.015

Mo0.500.50

V0.12

Al0.040.30 0.06

ng: A106 = Thp cc bon dng cho nhit cao. A335 = This specification covers seamless ferritic alloy-steel pipe for high-temperature service. A333 = This specification covers wall seamless and welded carbon and alloy steel pipe intended for use at low temperatures. A312 = Standard specification for seamless, straight-seam welded, and cold worked welded austenitic stainless steel pipe intended for high-temperature and general corrosive service.Fittings A234 = This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction. A420 = Standard specification for piping fittings of wrought carbon steel and alloy steel for low-temperature service. A403 = Standard specification for wrought austenitic stainless steel piping fittings.Flanges A105 = This specification covers standards for forged carbon steel piping components, that is, flanges, fittings, Valves, and similar parts, for use in pressure systems at ambient and higher-temperature service conditions. A182 = This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and Valves and parts for high-temperature service. A350 = This specification covers several grades of carbon and low alloy steel forged or ring-rolled flanges, forged fittings and Valves for low-temperature service.Valves A216 = This specification covers carbon steel castings for Valves, flanges, fittings, or other pressure-containing parts for high-temperature service and of quality suitable for assembly with other castings or wrought-steel parts by fusion welding. A217 = This specification covers steel castings, martensitic stainless steel and alloys steel castings for Valves, flanges, fittings, and other pressure-containing parts intended primarily for high-temperature and corrosive service. A352 = This specification covers steel castings for Valves, flanges, fittings, and other pressure-containing parts intended primarily for low-temperature service. A182 = This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and Valves and parts for high-temperature service.Bolds & Nuts A193 = This specification covers alloy and stainless steel bolting material for pressure vessels, Valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications. A320 = Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for Low-Temperature Service. A194 = Standard specification for nuts in many different material types.

A. Hn kim loi1.1 KHI NIM CHUNG1.1.1 Khi nimHn kim loi l mt phng php ni lin cc chi tit li vi nhau thnh mt khi khng th tho ri c bng cch: Nung kim loi vng hn n nhit nng chy sau khi ng dc ta c mi lin kt vng chc gi l hn nng chy; Hoc c th nung chng n nhit cao nh hn nhit nng chy ca kim loi (i vi kim loi do th c th khng nung) ri dng lc ln p chng dnh chc vo nhau gi l hn p lc; C th dng kim loi trung gian nng chy ri nh s ho tan, khuyt tn kim loi hn vo vt hn m to nn mi ghp gi l hn vy. Hin nay cn c th dng keo dn cc chi tit li vi nhau to nn cc mi ni ghp; Ngoi ra ta cn c th dung keo kim loi dn chung dnh chc vo nhau gi ldn kim loi.1.1.2 NG DNG :Hn kim loi dng mt vai tr rt quuan trng trong qu trnh gia cng, chto v sa cha phc hi cc chi tit my.Hn khng ch th dng ni ghp cckim loi li vi nhau m cn ng dng ni cc phi kim loi hoc hn hp kimloi vi phi kim loi. Hn c mt trong cc ngnh cng nghip, trong ngnh y t haytrong cc ngnh phc hi sa cha cc sn phm ngh thut,...1.1.3 c im ca hn kim loia. Tit kim kim loi So vi tn ri v, hn kim loi c th tit kim t 10 - 15 % kim loi (do phninh tn, phn khoa l) v cha k n bn kt cu b gim do khoan l. So vi c : Tit kim khong 50 % kim loi do mi hn khi hn khng cn hthng u hi, u ngt, bn cnh chiu dy vt c ln hn vt hn,...-Tit kim kim loi qu him : V d khi ch to dao tin ta ch cn mua vt liuphn ct gt l thp dng c cn phn cn ta s dng thp thng CT38 S c gthnh r m vn tho mn cc yu cu k thut.b. bn mi hn cao, mi hn kn, chu c p lcc. Thit b n gin, gi thnh hd. Nhc im T chc kim loi vng mi hn khng ng nht, tn ti ng sutv bin dng sau khi hn.2 QA TRNH LUYN KIM KHI HN NNG CHY2.1 QU TRNH LUYN KIM KHI HN NNG CHYKhi hn nng chy nhit vng hn trung bnh l 1700 - 1800 oC. trngthi nhit cao kim loi lng chu s tc ng mnh ca mi trng xung quanhv cc nguyn t c trong thnh phn que hn v thuc bc que hn; Kim loi mihn trng thi lng v mt phn bi bay hi. Trong vng mi hn xy ra nhiu qutrnh nh xy ho, kh xy, hon nguyn v hp kim ho mi hn, qu trnh tox v tinh luyn ,... Cc qu trnh phn no tng t nh nhng qu trnh luynkim nn ngi ta gi qu trnh ny l qu trnh luyn kim khi hn nhng xy ratrong mt th tch nh v thi gian ngn.a. nh hng ca xyxy c trong cc mi trng xung quanh nh khng kh, hi nc, Co2,H2O, v trong cc it kim loi, trong lp x khi hn,...xy c tc dng mnh vi cc nguyn t : Fe, Mn, Si, C, ... kt qu s lm thay i thnh phn v tnh cht ca kim loi mi hn.V d :Fe + O ----> FeOFe + O2 ----> 2FeOMt phn cc xit st nh trn s i vo x, mt phn s trn ln vi kim loimi hn do khng thot ra ngoi kp. Mi hn c ln x s lm cho c tnh gimmnh.Trong mi trng xung quanh cng cn c nhiu cht kh c nh hng n cht lng mi hn nh hydro., Nit, lu hunh, pht pho,...Hydro: c trong hi nc, trong cc loi kh bo v hoc do b phn hu cc cht trong qu trnh hn s ho tan vo mi hn v gy nn r kh. i vi thp v hp kim nhm, hydro l nguyn nhn ch yu gy nn r kh.Lu hunh l cht gy nn nt nng cho mi hnPht pho gy nn nt ngui cho mi hnTrong vng mi hn xy ra qu trnh kh xy. C th tm tt theo cc dng phn ng sau:[FeO] + (Si) --> [Fe] + (SiO2)[ ] - Thnh phn cc cht i vo kim loi;( ) - Thnh phn cc cht i vo trong x;[FeO] + (Mn) --> [Fe} + (MnO2)[FeO] + (SiO2 --> (FeO.SiO2)FeS + Mn -- > MnS + FeFeS + MnO --> MnS + FeOFe3P + FeO ---> (P2O5) + 9 FeCaO + P2O5 --> Ca3P2O8 2.2 VNG HN V C IM CA N.Khi hn, di tc dng ca ngun nhit, vng kim loi nng chy to nnmt vng hn. Kim loi y l hn hp cc nguyn t ca kim loi c bn v kimloi vt liu hn. Vng hn c chia ra 2 vng chnh: vng u v vng ui vnghn.Qu trnh kt tinh ca mi hn- Mi hn kt tinh trong iu kin phn u vng hn lun b nung nng bi ngunnhit hn cn vng ui th c ngui dn.- Kim loi vng hn lun chuyn ng;- Th tch vng hn nh khong 0,2-0,4 cm3.- Thi gian kim loi mi hn tn ti trng thi lng nh,;- Tc lm ngui ln- Vng tm mi hn c nhit cao d lm cho kim loi b qu nhit.2.3. T CHC KIM LOI MI HN V VNG CN MI HNSau khi ng c, kim loi mi hn s c thnh phn khc so vi kim loi cbn. Di tc dng ca nhit t chc kim loi mi hn cng c chia thnhnhiu vng khc nhau.T chc kim loi mi hn ph thuc phng php hn, kim loi vt hn, vch hn. T chc kim loi vng mi hn v gn mi hn c chia ra 7 vngkhc nhau : Vng mi hn, vng vin chy, vng nh hng nhit gm c cc vng: vng qu nhit, vng thng ho, vng kt tinh li khng hon ton vng kt tinhli, vng dn xanh.Vng mi hn (1) :C thnh phn kim loi hn hp giua vt hn, thuc hn v que hn. Tchc c dng ko di v tm mi hn (theo hng kt tinh)Vng gn vin chy ct chc ht nh mn do tc tn nhit nhanh; vung trung tm c ln nhiu tp chtdo kt tinh sau cng.Vng vin chy (2) :Vng ny kim loi nng chy khng hon ton. Thnh phn kim loi mihn c ln cc nguyn t ca que hn v thuc hn. Do c s tc dng qua li giapha long v pha c nn trong mi hn c th ln cc tp cht. Ht tinh th vngny nh, c c tnh tt. Vng ny tn ti 2 pha lng c chhiu rng vng ny nhkhong 0,1- 0,3 mm rt kh phn bit chng nn gi chung l vng vin chy.Vng nh hng nhit :L vng c nhit thp hn nhit nng chy nhng c t chc v tnhcht thay i di tc dng ca nhit . Chiu rng vng ny ph thuc chiu dyvt hn, ngun nhit, ch hn, phng php hn,... (xem bng 1.1)

Khi nim v vng hn v mi hn10.2.1.1 Vng hnVng hn c th chia lm hai phn:- phn u A: Ch yu xy ra cc qu trnh nng chy ca kim loi c bn v kim loi b sung;- phn ui B: din ra qu trnh kt tinh v hnh thnh mi hn.Khi hn nng chy, di tc dng ca ngun nhit hn, mt phn kim loi c bn ti v tr trn mp hn b nng chy kt hp vi kim loi b sung t vt liu hn (que hn, dy hn, thuc hn...) to ra mt khu vc kim loi lng thng gi l vng hn.Trong vng hn, kim loi lng lun trng thi ng kim loi lng phn u b y li v pha ui mt cch tun hon di tc dng ca p sut dng kh ln b mt kim loi vng hn. V vy, b mt mi hn sau khi hnh thnh khng phng v c dng sng hnh vy c xp chng. Hnh 10.3

Hnh 10.3 Vng hn 10.2.1.2 Mi hnKhi ngun nhit chuyn ng dc theo mp hn, vng hn chuyn ng theo li phn kim loi lng c kt tinh to thnh lin kt kim loi pha sau n, gi l mi hn.Theo hnh dng mt ct ngang, ngi ta phn bit cc mi hn nng chy thnh hai loi: mi hn gip mi, mi hn ch T v mi hn gc (hnh 10.4)Cc mi hn nng chy c th gm mt lp hay nhiu lp, lin tc hay gin on, mt pha hay hai pha.

Hnh 10.4 Mt ct ngang mi hn

Qu trnh luyn kim khi hn nng chyTrong vng hn, nhng giai on nht nh c th xy ra cc qu trnh l ho sau yS tng tc gia kim loi lng v x hnCng vi s nng chy ca kim loi c bn v vt liu hn b sung (que hn, thuc hn...), thng to ra mt pha lng gi l x hn.Trong x hn c cha cc oxit mang tnh axit (SiO2), TiO2, P2O5) hoc baz (CaO, MnO. FeO, BaO...). X to ra lp v mng trn vng hn, c tc dng bo v kim loi lng khi tc dng xu ca mi trng khng kh.

Tc ng bo v ca mi trng kh v xMi trng khng kh xung quanh h quang v vng hn gm nhiu loi kh, trong oxy v nit c nh hng rt xu n cht lng mi hn. Oxy (O2) xm nhp vo vng hn s to nn cc oxit (FeO, CuO, Al2O3...) nm quanh tinh gii ht hoc ho tan dng hn hp c hc.Nit (N2) to thnh cc nitrit lm gim mnh do v tng kh nng gin ngui ca kim loi mi hn.Thuc bc que hn, li thuc ca dy hn, bt v thuc hn khi chy s to ra mi trng x v kh bo v. Khi hn bng in cc trn (v d in cc volfram, dy hn c....), cn ch ng a cc loi kh nh argon (Ar), heli (He), cacbonic (CO2)... vo vng hn y khng kh ra khi vng hn.Qu trnh oxy ho - kh v hp kim kho kim loi mi hn+ S oxy ho: c th do mi trng kh xung quanh kim loi nng chy c cha nhiu hi nc, kh m (cc yu t ny i vo vng hn thng qua que hn, thuc hn, kh chy....), c th do x hn (cha nhiu FeO, CaCO3...) hoc cng c th do s tn ti ca nhng lp g cha khng kh m trn b mt hn. h thp hm lng ca O2 trong kim loi p, ngi ta phi tin hnh cc bin php kh oxy khi hn nng chy. Thng dng nht l bin php kh oxy bng x hn v kh oxy bng cc cht kh mnh- Kh oxy bng x hn:

- Kh oxy bng cht kh: S dng cc nguyn t hp kim c i lc mnh vi oxit nh Al, Ti, Mn, Si... kh oxy+ Hp kim ho kim loi mi hn: Nhm b li cc nguyn t hp kim ca vt liu c bn mt do qu trnh chy hay bc hi; hoc l hp kim ho kim loi mi hn bng cc nguyn t hp kim khc khng c trong thnh phn ca kim loi c bnThng thng, cc nguyn t hp kim nh Cr, Mo, W, V, Ti.... c a vo mi hn thng qua dy hn, thuc bc que hn v thuc hn, trong vic hp kim ho mi hn bng dy hn c hiu qu cao nht.Qu trnh ho tan kh - r kh trong mi hnKhi hn lun xy ra s ho tan cc loi kh vo mi hn, khng nhng to thnh cc oxit, nitrit,... c hi, m cn lm xut hin cc r kh. l s xut hin cc l trng v bt kh, l kt qu ca s thot kh khng trit khi kim loi lng vng hn, vt liu hn (dy hn, que hn, thuc hn...) b m, b mt chi tit cha c lm sch trc khi hn, mc kh oxy cha trit ...R kh c th xut hin trong kim loi mi hn cng nh ngay trn b mt mi hn, gy nn hin tng tp trung ng sut, lm tng cng, gin v gim tnh do ca kim loi vng hn.S kt tinh v hnh thnh kim loi mi hn- Khi phn u ca vng hn ang din ra s nung nng th phn ui li xy ra qu trnh kt tinh, kim loi lng trong vng hn di chuyn mnh t phn u sang phn ui ca vng hn. Trong qu trnh kt tinh, cc tp cht x v bt kh b y v ni ln trn. Nu b kt li v mt l do no th chng s thnh cc khuyt tt trong mi hn.T chc kim loi ca mi hnNhit ca ngun nhit hn lm kim loi que hn v mt phn kim loi vng hn b nng chy to thnh vng hn chy lng ng thi tc dng ln vng xung quanh n lm thay i t chc do lm thay i c tnh ca n. Vng hn ny c gi l vng nh hng nhit.1) Vng vng hnVng hn c th tch rt nh c bao bc bng kim loi c bn trng thi rn xung quanh nn ngui nhanh. Cc ht tinh th thng c dng hnh kim v dng nhnh cy phc tp, pht trin theo phng thng gc vi cc mt ng nhit. Cng vo pha tm mi hn, ht tinh th cng ln v c xu th chuyn t dng hnh nhnh cy sang dng hnh cu, v tm vng hn ngui chm nht (hnh 10.5 ) Trong vng hn cn ln c tp cht v bt kh. Hnh 10.5 T chc kim loi vng hn2) Vng nh hng nhit gm cc vng: Hnh 10.6- Vng qu nhit : L vng gip ranh gia vng hn v kim loi c bn, c nhit xp x nhit nng chy, thng xy ra qu trnh kt tinh li. Do hin tng qu nhit, nn ht tinh th c kch thc ln, dai v chm v do thp d nt nng v nt ngui. y l vng yu nht ca lin kt hn.- Vng thng ho : Khu vc kim loi b nung nng t nhit 900 - 11000C. T chc gm nhng ht ferit nh v peclit, c c tnh tng hp tng i cao.- Vng kt tinh li khng hon ton : y nhit khong 720 - 900OC. Kim loi c s kt tinh li tng phn, lm xut hin cc tinh th mi. T chc gm cc ht ferit th v ostenit nh, c tnh ca vng ny km hn.- Vng kt tinh li (cn gi l vng ho gi): Nhit khong 500 - 700oC, xy ra qu trnh kt tinh li, pht sinh v pht trin cc tinh th mi.

Hnh 10.6 Vng nh hng nhit- Vng gin xanh: nhit khong 100 - 5000C, khng c s thay i r rt v t chc kim loi, nhng do nh hng ca nhit hn nn thng tn ti mt trng thi ng sut d, do v dai v p gim, bn tng.Nh vy, s thay i t chc ca vng nh hng nhit u lm gim c tnh tng hp ca lin kt hn. C gng hn ch kch thc ca vng nh hng nhit, vng nh hng nhit cng nh khi:- Cng sut ca h quang hoc ngn la kh cng nh;- Tng vn c hn (gi nguyn cng sut nhit);- Vt liu c bn ca nhit dung cng cao v gin nhit cng thp.

Hng dn hn nhm bng thit b hn MIGCc hng dn sau y da trn kinh nghim v thc tin c c kt t vic la chn thit b hn, chun b vt liu c bn, p dng k thut thch hp, v kim tra trc quan kt cu hn m bo mi hn cht lng cao vi quy trnh hn MIG v TIG khi hn hp kim nhm. Ngay c vi ngi c kinh nghim hn thp vn c th gp kh khn khi hn hp kim nhm. Tnh dn nhit cao v im nng chy thp ca hp kim nhm c th dn ti hin tng chy thu (burnthrough) vt liu nu th hn khng thc hin ng quy trnh. Trong quy trnh hn MIG, vic cp dy hn nhm cng c nhng kh khn nht nh v dy nhm mm hn dy hn thp, c n hi thp d dn ti ri dy cun dy hn. khc phc nhng vn ny, th hn phi tun th nhng hng dn sau y:Chun b vt hn: hn nhm, th hn phi lm sch b mt vt hn cn thn. nh sch lp oxit nhm b mt v cc cht bn c th t du, m. Oxit nhm trn b mt ca vt hn nng chy ti nhit 3,700 F trong khi vt liu nhm ca chi tit hn c nhit nng chy di 1,200 F . V vy, lm sch lp oxit trn b mt vt hn s hn ch s thu su ca kim loi in vo vt hn. lm sch lp oxit nhm, s dng bn chi bng thp khng g nh sch hoc dng dung mi v cc phng php n mn. Khi dng bn chi, nn chi theo mt hng. Nn chi nh v u khng lm cho b mt th rp x x qu c th tng thm nguy c ngm oxit trn b mt vt hn. Ngoi ra, lm sch b mt vt hn bng nhm khng c dng bn chi s dng cho vic lm sch vt hn bng thp hoc thp khng g. Khi dng cc gii php lm sch bng ha hc phi m bo lm sch dung mi n mn trn b mt chi tit trc khi hn. gim thiu nguy c hydrocarbon t du m hoc dung mi t nguyn cng ct xm nhp vo mi hn, phi lm sch chng bng cht ty. Kim tra chc chn rng cht ty khng cha thnh phn hydrocarbon.Gia nhit: :Gia nhit vt hn trnh nt mi hn. Nhit nung nng vt hn khng vt qu 230F. Nn dng nhit k ch ng duy tr nhit trnh qu nhit. Th hn cng cn nung nng trc chi tit hn dy khi hn vi chi tit mng. Dng k thut y m hn: Vi nhm, hn vi thao tc y m hn thay v ko m tc dng lm sch tt hn, gim thiu nhim bn mi hn v tng kh nng bo v ca kh.Tc di chuyn:Hn nhm cn c thc hin "nng v nhanh". Khng nh thp, tnh dn nhit cao ca nhm i hi phi t in p hn, dng hn ln hn, v tc di chuyn m hn cng ln hn. Nu tc di chuyn m chm, c th dn ti chy thu mi hn, c bit l khi hn chi tit mng.Kh bo v:kh Argon, vi tc dng lm sch v c tnh thm nhp tt, l loi kh c chn s dng ph bin nht cho hn nhm. Hn cc hp kim nhm 5XXX-series, hn hp kh bo v kt hp argon vi heli - ti a 75% heli - s gim thiu s hnh thnh oxit magi.Dy hn: La chn dy hn c nhit nng chy tng t vt liu c bn . Th hn cng hn ch khong nng chy ca kim loi th cng d hn. hn chi tit mng, s dng dy 0.8mm kt hp vi quy trnh hn xung ti tc thp - 100 n 300 inch/pht - l ti u.Hnh thnh mi hn dng li: Khi hn nhm, nt mi hn thng hay xy ra. Nt do mc dn n nhit cao ca nhm v s co ngt xy ra khi ngui mi hn. Nguy c nt l rt ln vi mi hn lm v b mt ca mi hn co ngt v rch khi ngui. Do , th hn nn thao tc hn hnh thnh mi hn dng li. Bi v khi mi hn ngui dn, dng li ca mi hn s cn bng lc co ngt.La chn ngun hn:Khi chn thit b hn cho ng dng hn nhm trong kh bo v, iu u tin l la chn phng php dch chuyn h quang phun hoc xung. My hn c ch dng hn khng i (cc) v in p hn khng i (cv) c dng cho hn h quang phun. Vi chi tit nhm dy, i hi dng hn mc hn 350A, ch cc cho kt qu tt nht.Hn xung thng c thc hin vi my hn inverter. Cc my hn i mi tch hp quy trnh hn xung da trn ng knh v loi dy hn. Khi hn MIG xung, cc git nh kim loi t dy hn dch chuyn ti vt hn trong mi chu k xung ca dng hn. Quy trnh hn xung to dch chuyn git kim loi mt cch ch ng, t bn te v tc hn nhanh hn so vi hn dch chuyn phun. S dng quy trnh hn MIG dng xung khi hn nhm cng iu khin s tch nhit vt hn tt hn, gim thiu s lch v tr hn v cho php th hn c th hn chi tit mng ti dng hn v tc cp dy nh.

B cp dy:Phng php c a dng cp dy hn nhm mm vi khong cch xa l phng php y-ko, s dng bung cp dy kn bo v dy khi tc ng mi trng. M t cp dy nhiu tc vi mmen xon khng i trong bung cp dy gip cho vic y v dn dy qua sng hn vi lc y v tc khng i. Mt c mmen xon cao trong sng hn ko dy v duy tr tc cp dy v chiu di h quang thch hp. Trong mt s trng hp, th hn s dng cng mt b cp dy cho dy hn thp v dy hn nhm. Khi , nn s dng liner dn dy bng plastic hoc teflon gip cho vic cp dy nhm c thun li.i vi ng dn dy, s dng ng dn dy u vo bng plastic hn ch ri dy trc con ln dn dy ch ng. Khi hn, cp m hn cng thng cng tt gim thiu lc cn cp dy. Kim tra v cn chnh thng hng gia con ln y dy v ng dn dy hn ch s co xc dy hn nhm.S dng con ln y dy dng ring cho dy nhm. Cn chnh lc p thch hp ln con ln dy c cp trn tru v n nh. Lc p qua ln s lm cho dy hn bin dng v lm cn tr s y dy; lc p qu nh th dy c cp khng nnh. C hai trng hp c th dn ti h quang hn khng n nh v lm r mi hn.Sng hn:S dng ng liner dng ring cho dy hn nhm. ngn chn s co xc dy, c gng lp gi c hai u ca liner st vi ng phun kh trong m hn. Thay th liner thng xuyn s lm gim cc kh nng gy tc do c xt dy to nn bt xit nhm trong ng. S dng u bp hn cho dy nhm (contact tip) vi ng knh ln hn khong 0,4 mm so vi u bp hn dy thp do dy nhm c h s dn n nhit cao. Thng thng, khi hn vi dng hn ln hn 200A nn s dng m hn lm mt bng nc trnh tch ly nhit v gim thiu cc kh khn xy ra i vi vic cp dy.K thut hn gangK thut hn gang l mt k thut cc k kh v phc tp, nhng khng phi l khng th hn. Thng thng phng php hn ch dng sa cha, ch khng dng kt ni cc chi tit vi nhau. Nh sa cha khun c hay sa li cc sn phm sau khi c hoc sau gia cng bi v tnh dn ca hu ht cc loai gang. Gang c hm lng carbon t 2-4% v cng gp 10 ln thp.- Cc kh khn khi hn gang:Th nht, Kh nng bin dng do ca gang rt thp. Trong biu th ko ca gang th gn nh khng c vng bin dng chy r rt.Th hai, Gang rt nhy cm vi nhit, nn rt d thay i v t chc trong qu trnh hn v qu trnh ngui sau khi hn. Do tc ngui ca gang ln nn mi hn v vng kim loi lin k d hnh thnh t chc ti, ti chc gang trng c cng, gin cao ( ln ti 800HB) d gy nt mi hn.Th 3: Cc sn phm gang rt a dang v mt thnh phn ha hc, t chc. Nn khi hn kh c th xc nh chnh xc ch hn v ch gia cng nhit.Th t: th lng gang c tnh chy long cao. Gang kh hn t th khc hn sp.Khi hn gang, cn phi tun th nhng vn sau:- Loi quy trnh hn p dng:Quy trnh ngui: Hn tng on ngn t 2-3 cm sau ngui cho n khi chm vo c mi hn ri mi hn tip. Trnh t hn nn p dng theo kiu phn on nghch hoc hn i xng.Quy trnh nng: Nung nng vt ln nhit chuyn bin pha 600-650 0C v ng thi lin tc gi nhit trong qu trnh hn. Sau khi hn cn lm ngui chm vt hn (120 0C/s) trong l hoc bng cch bc v cch nhit(kh thc hin vi nhng kt cu ln)Mo b sung cho quy trnh hn nng l nung gang cn hn n kh thy c mu c chua chn l c (mo dng g thng kh gt ln ch va nung thy c tn than bay l ok).- Vt liu hn:La chn vt liu hn gang ng: Thng thng vt liu hn gang cn c do rt cao, nn thnh phn Nikel trong l rt cao, ln n 90%!Nn chn que hn v ch hn hp l, loi que hn thng dng l que hn ng, que hn innox. Hn tt nht l s dng que hn hp kim niken ng.v dng ngn la cc bon ho b p lng cc bon trong gang b chy.i vi b mt gang b nt chng ta vn c th tin hnh hn c bng que hn c bit.Loi que hn: Eutectic 240 (Que hn ni v p cho cc loi gang)Ngun hn: AC/DC+Thnh phn: Ni Fe Mn C bn ko:55 000 psi (380 MPa)- Mt s k thut, kinh nghim khi hn gang:Do gang cng v dn, nn ng sut d trong gang kh ln, cc vt nt s tip tc pht trin trong qu trnh s dng v c bit l trong qu trnh hn. V th, trnh vt nt tip tc x, ngi ta thng khoan chn 2 u vt nt trc khi hn. Bc tip theo l dng trnh t hn t ch bt u nhnh nt cho ti ch chng gp nhau. Sau cng, tin hnh hn cc v tr l khoan.Vi nhng chi tit ln, ta c th sang phanh ( tc l to ra rnh ch V ging kiu hn thp) sau y gia cng cc l ren c th l l ren 6, 8, 10 l ty v c gng cng nhiu cng tt nn xp theo dy. n y ta bt cc bu lng vo v ct i( nh tha ra 5 ti 10 mm cht na ta s hn ln n) .Nh c thm cc u tha bulong nh ln v n vo chi tit qu trnh hn s thun li hn rt nhiu v kt cu tt hn (do lc ny ta s hn ln c gang v thp m thp th s d hn).Khi hn gang phi c thc hin trong mi trng cch ly vi gi nu khng qu trnh nung v hn s xy ra hin tng tch, nt thm.Vi nhng chi tit c cng vng cao nhng c th tin hnh nung nng cc b( phn gch cho) thay v nung nng ton b. Mc ch ca nung nng s b l to iu kin cho kim loi mi hn v vng kim loi lin k c tc nung v lm ngui ng u, trnh hin tng nt do ng sut nhit.

Hn l phng php ni hai hay nhiu chi tit kim loi thnh mt m khng th tho ri c bng cch nung nng chng ti vng tip xc n trng thi nng chy hay do, sau khng dng p lc hoc dng p lc p chi tit hn dnh cht vi nhau. Khi hn nng chy, kim loi b nng chy, sau kt tinh hon ton to thnh mi hn. Khi hn p lc, kim loi c nung n trng thi do, sau c p to nn mi lin kt kim loi v tng kh nng thm thu, khch tn ca cc phn t vt cht gia hai mt chi tit cn hn lm cho cc chi tit lin kt cht vi nhau to thnh mi hn.

Arc Strikes: Vt gy h quang.

S thiu thn trng mang tnh cht khng lin tc c kt qu t h quang, gm c mt vi vng kim loi b nng chy, kim loi vng nh hng nhit, hoc thay i trong b mt nghing ca mt vi i tng kim loi. Vt gy h quang c th l l do ca in cc hn h quang, cc c thc kim tra t tnh, hoc cp hn b c sn.Blowhole: R hnh ng. L mt thut ng khng tiu chun thay th cho Porosity.Concavity: B mt lm. L khong cch ln nht t b mt ca mi hn gc lm vung gc vi ng ni cc chn mi hn.Cracks: Nt. Loi khe nt c tnh khng lin tc biu th c im bng u sc nhn v c t l rt ln gia chiu di v chiu rng khe h chim ch.Crater: H. Ch tht xung thnh h ti im kt thc ca mi hn.Crater Cracks (star crack): Nt hnh sao. Vt nt trong h, thng im kt thc ca mi hn.Incomplete Fusion: S nu chy khng hon ton. Mt mi hn c tnh khng lin tc trong s nu chy khng xy ra gia kim loi mi hn v nu chy b mt hoc phn tip gip cc ng hn.Lack of Fusion: Thiu chy L mt thut ng khng tiu chun th cho incomplete fusion.Longitudinal Crack: Nt theo chiu dc Mt mi nt cng vi phn ln trc ca n c nh hng gn nh song song vi trc ca mi hn.Overlap: Chng lp. S nh ra ca kim loi mi hn vt xa hn chn ca mi hn hoc gc mi hn.Porosity: Trng thi r, xp. L loi l hng c tnh khng lin tc c to nn bi kh cn nm li trong kim loi mi hn sau khi qu trnh ng c kt thc.Root Crack: Nt gc mi hn. Vt nt trong mi hn hoc vng nh nhit xy ra t gc ca mi hn.Slag inclusion: Ngm x L vt liu c phi kim loi nm li trong kim loi mi hn hoc gia kim loi mi hn v vt liu c bn.Spatter: Bn to. Cc ht nh kim loi b bn ra trong khi hn nng chy, cc ht khng hnh thnh t b phn ca mi hn.Toe Crack: Nt chn. Vt nt trong mi hn hoc trong vng nh hng nhit xy ra t chn ca mi hn.Transverse Crack: Nt theo chiu ngang. Mt mi nt cng vi phn ln trc ca n c nh hng gn nh vung gc vi trc ca mi hn.Undercut: Chy cnh (chy chn). Mt rnh b nu chy vo trong kim loi c bn gn st chn mi hn hoc gc mi hn v tri li khng c lp y bng kim loi mi hn.Underbead Crack: Nt di ng hn Mt vt nt trong vng nh hng nhit thng thng khng m rng ln b mt ca kim loi c bn.Underfill: Lm b mt Ch lm trn b mt mi hn hoc b mt gc c m rng xung thp hn lin k b mt ca kim loi c bn.Cc Phng Php Kim Tra Khuyt Tt Mi HnMc ch ca phng php kim tra cht lng lin kt hn l kim tra cc tnh cht c hc, ho hc, kim loi hc v xc nh cc khuyt tt. Ngoi ra vic kim tra cht lng mi hn cn c dng phn loi cc quy trnh hn v trnh tay ngh th hn.Cc phng php kim tra c chia thnh hai phng php chnh :1. KIM TRA BNG PHNG PHP PH HU1.1 KIM TRA C TNH CA MI HNMc ch ca vic kim tra ny l so snh c tnh ca lin kt hn vi c tnh ca kim loi c bn. Qua nh gi trnh tay ngh ca ngi th hn mt cch chnh xc hn. Cn c vo yu cu k thut, kh nng thit b kim tra, quy trnh hn c p dng m dng mt hoc nhiu cc phng php kim tra sau: Kim tra th ko Kim tra th un Kim tra dai va p th ko, th un hoc cc phng php th dai va p cc mu c ct ra t phn kim loi p ca lin kt hn v c gia cng c kh t c hnh dng v kch thc theo cc tiu chun c p dngCc mu th kim tra vi tc dng ca ti trng tnh hoc ti trng ng.1.2 KIM TRA CU TRC CA LIN KT HNGm c hai dng l: Kim tra th v kim tra t viKIM TRA TH - c tin hnh trc tip vi cc mu th kim loi hoc cc mt gy ca chng. Cc mu th c ct ra t lin kt hn, mi bng v ty sch bng dung dch axit nitric 25% ri dng knh lp hoc mt thng pht hin khuyt tt ca lin kt hn, c th khoan ly mu ngay trn kim loi p nghin cu. Mi khoan ly mu c ng knh rng hn chiu rng ca mi hn 3mm ly c phn kim loi c bn v kim loi mi hn.KIM TRA CU TRC T VI - c tin hnh di loi knh lp c phng i ln (100-500 ln), nh vy c th xc nh c d dng v chnh xc cht lng kim loi ca lin kt hn.2. KIM TRA BNG PHNG PHP KHNG PH HU2.1 KIM TRA BNG MT THNGKim tra trc khi hn Kim tra bn v, cc tiu chun t ra cho lin kt hn Kim tra chng ch vt liu c s dng c v ph hp vi yu cu khng. Kim tra gia cng g lp, khe h v mp vt c ng vi thit k khng. Kim tra sch ca lin kt hnKim tra trong khi hn Kim tra cc thng s ca quy trnh hn. Loi vt liu hn tiu hao. Nhit nung nng trc khi hn (nu c yu cu). V tr hn v cht lng b mt vt hn. Trnh t hn. X l cc mi hn nh v v sinh gia cc lp hn. Kch thc lin kt hn. Nhit v thi gian s l nhit sau khi hn.Kim tra sau khi hn Lm sch b mt lin kt hn (b mt mi hn v vng kim loi c bn) Quan st k bng mt thng hoc bng knh lp Kim tra kch thc ca mi hn so vi bn v thit k.

2.2 KIM TRA BNG DUNG DCH CH TH MUy l phng php s dng cc dung dch thm thu vo cc vt nt, r kh nh ca lin kt hn m khng th quan st c bng mt thng, sau dng cc cht hin th mu pht hin ra v tr m dungdch thm thu cn nm li cc vt nt cng nh r kh.Cn lu l : Phng php ny ch pht hin c cc khuyt tt m ra trn b mt vt liu cn kim tra. Thng thng s dng 3 loi dung dch v c tin hnh theo cc bc sau: Dng dung dch lm sch ty sch b mt mi hn. Phun dung dch thm thu ln b mt mi hn. Sau khi thi gian dung dch thm thu vo cc vt nt, r kh, th lau sch b mt mi hn. Dng dung dch hin th mu phun ln vng mi hn va thc hin cc bc trn pht hin khuyt tt.Phng php ny c tnh u vit l n gin, d thc hin, pht hin c c cc khuyt tt nh khng quan st c bng mt thng mt cch nhanh chng, tuy nhin n khng pht hin c nhng khuyt tt nm bn trong ca lin kt hn v chiu su ca khuyt tt.

2.3 KIM TRA BNG T TNHDng bt st t rc trong trng ca nam chm t nhin hay in t th n s phn b theo quy lut ca cc ng sc t. Quy lut ny trc tin ph thuc vo s ng nht ca cu trc st t, nu nh trn ng i cc ng sc t gp phi cc vt nt, khe h th quy lut phn b ca cc ng sc t thay i so vi nhng khu vc khc do c s khc nhau v thm t. Khi gp cc khuyt tt cc ng sc t tn ra bao xung quanh ly cc khuyt tt .Da vo nguyn l ngi ta tin hnh kim tra bng cch rc bt st ln b mt mi hn, sau t kt cu hn vo trong mt t trng ri nhn vo s phn b cc ng sc t c th pht hin v phn bit c khuyt tt. Phng php ny ch p dng i vi cc vt liu t tinh, n cho php pht hin cc khuyt tt nt b mt c kch thc rt nh, cc khuyt tt pha di b mt lin kt hn nh:Nt vng nh hng nhitHn khng nguNt pha di b mtR kh, ln x.

2.4 KIM TRA BNG TIA PHNG X (RNGHEN V GAMMA)Tia X v tia Gamma l sng in t c bc sng rt ngn, tn s dao ng v nng lng rt cao c th i xuyn qua khi kim loi dy. Mt phn bc x tia X v tia gamma b hp th, mt phn s i qua mu kim \tra, lng hp th v lng i qua c xc nh theo chiu dy ca mu. Khi c khuyt tt bn trong, chiu dy hp thc bc x s gim, iu ny to phn khc bit trong phn hp th, c ghi li trn phim dng hnh nh bng gi l nh bc x. Gii on phim s cho php pht hin cc khuyt tt bn trong vt hn mt cch chnh xc.Phng php ny cho php pht hin c tt c cc loi khuyt tt tr cc vt nt vi nh.

2.5 KIM TRA BNG SIU MSng siu m l dng sng m thanh dao ng n hi trong mi trng vt cht nht nh, khi truyn qua bin gii gia cc mi trng vt cht khc nhau sng siu m s b khc x hay phn tr li. Da vo c tnh , ngi ta ch to c cc loi my d siu m pht hin cc khuyt tt nm su trong lng kim loi.Phng php ny cho php pht hin cc vt nt, hn khng ngu, r kh, kt x,v c nhng thay i rt nh vng nh hng nhit ca lin kt hn. Quan st trn mn nh ca my bng nhng xung hin th, c th cho php bit c chnh xc v tr ca cc khuyt tt.

2.6 PHNG PHP KIM TRA KN CA LIN KT HNKim tra kn bng p lc khTrc lc kim tra cn bt kn, sau bm kh vo (khng kh hoc kh tr) n mt p sut nht nh no , sau bi nc x phng ln mt ngoi mi hn v quan st (100 gam x phng trn mt lt nc).Nhng ch b r r s c pht hin theo cc v tr m bong bng x phng ni ln.Kim tra bng p lc nc kim tra ngi ta bm nc vo kt cu cn kim tra, to mt p sut d cao hn p sut lm vic 1,5 n 2 ln v gi p sut trong vng 5 - 6 pht. Giai on tip theo l h p xung n p sut lm vic ri dng ba g nh vng xung quanh mi hn (rng 15 - 20mm)v quan st xem nc c r r ra khng. i vi nhng kt cu h nh bn cha, thng,ch cn th bng cch bm nc vo v gi trong vng 2 - 24 gi v quan st xem nc c b r r ra khng.Kim tra bng phng php to chn khngCh p dng trong iu kin khng tin hnh c bng cc phng php th kn trn (v d nh: y bn, b)Trc tin bi nc x phng ln mi hn cn kim tra. t bung chn khng trc tip ln vng mi hn cn kim tra, ti cc vin xung quanh bung chn khng c rong cao su to kn cn thit vi vt liu kim tra, chn khng c to ra nh c bm chn khng t pha ngoi. Do c s chnh lch ln v p sut, khng kh s chui vo bung chn khng qua cc khuyt tt, np y c thit k trong sut qua ta c th quan st v tr cc khuyt tt theo cc bong bng x phng.Thut Ng Cc Khuyt Tt Hn

Arc Strikes: Vt gy h quang. S thiu thn trng mang tnh cht khng lin tc c kt qu t h quang, gm c mt vi vng kim loi b nng chy, kim loi vng nh hng nhit, hoc thay i trong b mt nghing ca mt vi i tng kim loi. Vt gy h quang c th l l do ca in cc hn h quang, cc c thc kim tra t tnh, hoc cp hn b c sn.Blowhole: R hnh ng. L mt thut ng khng tiu chun thay th cho Porosity.Concavity: B mt lm. L khong cch ln nht t b mt ca mi hn gc lm vung gc vi ng ni cc chn mi hn.Cracks: Nt. Loi khe nt c tnh khng lin tc biu th c im bng u sc nhn v c t l rt ln gia chiu di v chiu rng khe h chim ch.Crater: H. Ch tht xung thnh h ti im kt thc ca mi hn.Crater Cracks (star crack): Nt hnh sao. Vt nt trong h, thng im kt thc ca mi hn.Incomplete Fusion: S nu chy khng hon ton. Mt mi hn c tnh khng lin tc trong s nu chy khng xy ra gia kim loi mi hn v nu chy b mt hoc phn tip gip cc ng hn.Lack of Fusion: Thiu chy L mt thut ng khng tiu chun th cho incomplete fusion.Longitudinal Crack: Nt theo chiu dc Mt mi nt cng vi phn ln trc ca n c nh hng gn nh song song vi trc ca mi hn.Overlap: Chng lp. S nh ra ca kim loi mi hn vt xa hn chn ca mi hn hoc gc mi hn.Porosity: Trng thi r, xp. L loi l hng c tnh khng lin tc c to nn bi kh cn nm li trong kim loi mi hn sau khi qu trnh ng c kt thc.Root Crack: Nt gc mi hn. Vt nt trong mi hn hoc vng nh nhit xy ra t gc ca mi hn.Slag inclusion: Ngm x L vt liu c phi kim loi nm li trong kim loi mi hn hoc gia kim loi mi hn v vt liu c bn.Spatter: Bn to. Cc ht nh kim loi b bn ra trong khi hn nng chy, cc ht khng hnh thnh t b phn ca mi hn.Toe Crack: Nt chn. Vt nt trong mi hn hoc trong vng nh hng nhit xy ra t chn ca mi hn.Transverse Crack: Nt theo chiu ngang. Mt mi nt cng vi phn ln trc ca n c nh hng gn nh vung gc vi trc ca mi hn.Undercut: Chy cnh (chy chn). Mt rnh b nu chy vo trong kim loi c bn gn st chn mi hn hoc gc mi hn v tri li khng c lp y bng kim loi mi hn.Underbead Crack: Nt di ng hn Mt vt nt trong vng nh hng nhit thng thng khng m rng ln b mt ca kim loi c bn.Underfill: Lm b mt Ch lm trn b mt mi hn hoc b mt gc c m rng xung thp hn lin k b mt ca kim loi c bn.nh Nghia Tng Phn Mi Hn Rnh v Mi Hn Gc

GROOVE ANGLE (A):Gc m mp hn.L ton b gc ca rnh gia cc phn c ghp mi to rnh hn BEVEL ANGLE (A):Gc vt ca mp hn.L gc c to gia vic s l mp ca mt chi tit v mt phng vung gc vi b mt ca chi tit . PLATE THICKNESS (T):Chiu dy vt liuChiu dy ca vt liu c hn. ROOT FACE (RF): ty mp hn (Mp cn). L mt rnh lin k ti chn ca mi ghp. ROOT OPENING (RO):Khe h h.L s tch ra gia cc chi tit c ghp mi cnh chn ca mi ghp. GROOVE FACE:B mt rnh. Bao gm b mt ca chi tit trong rnh. SIZE OF WELD (S):Kch thc mi hn. ngu ca mi ni (chiu su ca gc xin cng vi ngu chn theo l thuyt ). Kch thc ca mi hn rnh v rnh c hiu lc chnh l mt LEG OF A FILLET WELD:Cnh ca mi hn gc.L khong cch t gc ca mi lin kt ti chn ca mi hn gc. ACTUAL THROAT OF A FILLET WELD: Khong cch thct ca mt mi hn gc. L khong cch ngn nht t gc ca mi hn gc ti b mt ca n. FACE OF WELD:B mt ca mi hn. L b mt phi ra ca mi hn trn mt phng t bt k mi hn no hon thin. SIZE OF WELD (S):Kch thc ca mi hn. di chn ca mi hn gc. ROOT OF A WELD:Gc ca mi hn. Bt k cc im mt sau ca mi hn phn cch vi b mt kim loi c bn. DEPTH OF FUSION:Chiu su ngu chy. L khong cch ngu chy m rng vo trong kim loi c bn hoc xuyn qua t b mt kim loi nu chy trong thi gian hn. TOE OF A WELD:Chn ca mi hn. L s ni lin gia b mt ca mi hn v kim loi c bn

Hn QueKhi Nim:Hn Que hay cn gi l hn h quang que hn c v bc (SMAW) l phng php hn h quang s dng nhit ca h quang gia que hn c v bc v b hn. Phng php thng dng cng vi s bo v t vic phn hu ca v bc que hn khi b t chy trong qu trnh hn, trong phng php ny khng s dng p lc, v kim loi in y thu c t que hn.

u im v lnh vc s dng:Phng php hn que hay h quang SMAW l mt trong nhng phng php hn c a chung nht.Hn que th hn vi nhiu loi kim loi trong tt c cc v tr hn t chiu dy nh nht cho ti nhng chiu dy ln nht.V bc que hn t cung cp mi trng hn cho qu trnh hn.t b nh hng gi hn so vi cc qui trnh hn vi kh bo v.S u t v thit b tng i r tin, n gin v c tnh c ng cao.Phng php ny c s dng trong ch to v trong cng vic khai thc cho xy dng v bo dng.

Cc gii hn ca phng php hn Que:Gii hn ch yu ca phng php hn h quang que hn c v bc l gin on (khng lin tc).Nng xut hn thp do phi dng li thay que hn.Hao ph nguyn vt liu hn.Phi lm sch x ra khi ng hn sau qu trnh hn.V bc ca que hn cung cp:1) Kh t s phn hu ca thnh phn no trong thuc bc bo v h quang khi khng kh.2) Cht kh oxi y kh v lm thanh khit kim loi mi hn kt lng.3) X t s chy ca v bc lm nhim v bo v kim loi mi hn kt lng trnh khi s oxi h ca khng kh.4) Yu t ion ho to nn h quang n nh nht v c tc dng cng vi dng in xoay chiu.5) Cc nguyn t hp kim cung cp c bit, c tnh cho kt lng ca kim loi mi hn.6) Bt st ci thin nng sut ca que hn.Hn TIG, Hn Argon, Hn WIGHn TIG ( Tungsten Inert gas) cn c tn gi khc l hn h quang bng in cc khng nng chy (tungsten) trong mi trng kh bo v - GTAW ( Gas Tungsten Arc Welding ) thng c gi vi tn hn Argon hoc WIG ( Wonfram Inert Gas). Hn TIG thng c s dng khi c yu cu mi hn c cht lng cao.u im C th hn c kim loi mng hoc dy do thng s hn c phm vi iu chnh rng ( t vi ampe n vi trm ampe). Hn c hu ht cc kim loi v hp kim vi cht lng cao. Mi hn sch p, khng ln x v vng te. Kim sot c ngu v hnh dng vng hn d dng.- C th s dng hoc khng s dng que p to ln mi hn.Nhc im Nng sut thp. i hi th c tay ngh cao hn so vi hn MIG v hn que. Gi thnh tng i cao do nng sut thp, thit b v nguyn liu t tin.Kh Bo V- Argon hoc Heli- Argon+Heli- Argon+Hydro hoc Argon+Oxy.Video v hn TIG vi ngun AC:- Hin nay c 03 loi cng ngh ch to my hn TIG l: Diote, Thyristor v inverter. Tuy nhin, hin ti, ch c 02 loi my hn TIG c s dng ph bin l my hn TIG s dng cng ngh thyristor v my hn TIG s dng cng ngh Inverter. My hn TIG cng ngh inverter c u im ni tri so vi my hn TIG cng ngh Thyristor l gn nh hn nhiu ln, d dng iu chnh cc thng s ca dng hn c c mi hn c cht lng tt nht v hnh thc p nht.

5 k thut c bn khi hn h quang tayi vi nhiu ngi mi lm quen vi hn h quang tay hoc khng thng xuyn hn h quang tay th c mt mi hn p v m bo cht lng l mt iu khng d. Sau y l 5 iu c bn bn cn quan tm khi thc hin hn h quang tay m bo cht lng mi hn: Thit lp dng in, iu chnh di h quang, iu chnh gc nghing que hn, thao tc que hn v iu chnh tc hn.Chun b:Hn que l k thut hn khng i hi cao v lm sch v tr hn, tuy nhin khng v th m b qua bc ny. Cn loi b bi bn bng c hay s dng dng c lm sch b mt chuyn dng. Khu vc kp km mt cng phi c lm sch m bo tip xc tt, iu ny s gip n nh h quang.T th hn phi m bo trng r vng hn. Ngi th phi chn hng nhn tt nht, trnh b tay hn che mt, v trnh vng khi hn c hi.5 k thut khi hn h quang tay: Thit lp dng in, iu chnh di h quang, iu chnh gc que hn, thao tc que hn v iu chnh tc hn. p ng cc quy tc. Cng nhn hn cn luyn tp thng xuyn, t c th ci thin cht lng sn phm cng nh nng sut.1. Thit lp dng inTy theo loi in cc s dng m thit b s dng cn thit lp dng mt chiu thun, mt chiu nghch hay dng xoay chiu. Cn phi m bo bn thit b c thit lp ng trc khi hn. ln ca dng hn ph thuc vo ng knh que hn v loi in cc hn m bn s dng. Nh sn xut que hn thng cung cp thng tin v dng ph hp vi que hn trn bao b. Dng hn c th iu chnh theo cch tnh sau vi mi 1 Amp tng ng vi 0.0254 mm ng knh que hn. Bn c th dng hn mc thp sau iu chnh tng 5 n 10 Amp ri xem xt kh nng hn cho ph hp. Hin tng khi hn vi dng hn qu thp:

Hin tng khi hn vi dng hn qu cao:

2. iu chnh di h quang di h quang ph thuc vo tng loi que hn, tng v tr hn. C bn di h quang hn khng nn vt qu ng knh que hn. Khi di h quang qu ngn c th gy h quang khng n nh, c th lm tt h quang, vng hn ng cng nhanh hn v to vy hn cao. H quang qu di s gy ra hin tng bn te, tc kt ta chm v r kh.H quang qu ngn

H quang qu diCh i vi nhng ngi mi vo ngh hn thng h quang qu di, v h mun quan st h quang v vng hn, tuy nhin nn thay i v tr hn c th nhn c h quang v vng hn tt hn, khng nn ko di h quang. Mt cht luyn tp bn s c th m bo c c mi hn thp t bn te.3. Chnh gc que hni vi hn bn mt, gc que hn nn t 5 n 15 theo hng chuyn ng, i vi hn h quang v tr ng nn gc que hn t 0-15 ngc chiu vi hng di chuyn que hn.

4. Thao tc que hn Chuyn ng dc theo trc mi hn duy tr v iu chnh di h quang. Chuyn ng ngang duy tr rng ca ng hn. C nhiu loi chuyn ng: ngang, lin tc v chuyn ng ngt qung ty thuc vo dy ca vt hn .Vi vt hn mng khng cn c chuyn ng ngang que hn v rng ca h quang y rnh hn. Vi hn ng nn ch hn t di ln vi cc tm dy v hn t trn xung vi cc tm mng v ch n ra rnh hn.

5. iu chnh tc hn: Tc hn nn m bo sao cho h quang hn chim 1/3 di ca vng hn. Hn qu chm s to vy hn li v hn khng ngu. H quang b mt nhit khng th nng chy vt hn.

Tc hn qu nhanh gim ngu ca mi hn, vy hn khng u khng lp y vng hn.

tài liệu Đào tạo công nhân hàn

Documents