SM490A

1 1 1 2 2* 3

1 2 3

(Flux Cored Arc WeldingFCAW)

CO2 AWS A5.20 E70T-1 JIS G3106 SM490A

SM490A

1.

Inert-Gases Shield Metal Arc

Welding

(Flux-Cored Arc

Welding, FCAW)

(weld metal)(heat affected

zone)

(reheated zone)

(primary fusion zone)

SM490A

9

mm

2.

2.1

SM490A

(Niobium)

SM490A []

JIS [] JIS G3106 SM490A 16mm

JIS G3106

(%) C Mn P S Si Al Nb

SM490 0.12 1.06 0.02 0.006 0.01 0.032 0.023

Yield

Strength (MPa)

Tensile Strength (MPa)

Elongation (%)

JIS G3106 SM490A 325 490-610 17

Test Result SM490A 457 537 17.3

JIS

2.2 FCAW

(FCAW)

(over-matching)

SM490A TM-70C [3]

1.2mm AWS A5.20

E70T-1

(wt%) Fe C Mn P S Si

E70T-1 Bal. 0.05 1.47 0.017 0.01 0.55

Yield strength (MPa)

Tensile strength (MPa)

Elongation (%)

E70T-1 549 598 26

2.3

(1)

SASBSC

SVIQ *= (1)

(QI V S)

2.4

2.4.1

SiC #240#400#600#800#1000#1500#2000

0.05m

5%Nital (5%HNO3+ 98%

) OM

Welding parameters No.

Welding layer

Current(A)

Voltage (V)

Speed (mm/s)

Heat input(KJ/mm)

Total heat input

(KJ/mm)

Root 175 25.5 2.33 1.915 Second layer 170 27.5 2.33 2.006

SA

Surface 170 29.5 2.33 2.152

6.073

Root 165 24.5 2 2.021 Second layer 160 26.5 2 2.12

SB

Surface 160 28.5 2 2.28

6.421

Root 185 27.5 2.5 2.035 Second layer 180 29.5 2.5 2.124

SC

Surface 180 31.5 2.5 2.268

6.427

SEM

2.4.2 TEM

3mm 10mm

200m 70m

twin-jet (jet polish)

5%(HClO3) + 20% + 75%

-15~-10 JEOL JEM 100CXII

100KV

2.5

2.5.1 (tensile test)

AWS D1.1[4]

ASTM E8 20mm/min

2.5.2 (Charpy-notch impact test)

SEM

AWS D1.1[4]

10mm x 7.5mm x 55mm

2mm ASTM E23

2.5.3

SEM

2.5.4

AWS D1.1[4]

40mm x 9mm x 150mm 3-11

ASTM E190-92

()

ASTM E190-92

2.5.5

5%nital

HAZ

200g 0.5mm

0.25mm

2.6 -

(potentiodynamic polarization curve test)

(cyclic polarization curve test)

3.5wt%NaCl ()

3.

3.1

SM490A

[5](Nb)

[6] 1200

(Coarse grain

zone) (Fine grain zone) (Partially

transformed zone)(Tempered zone)

(Reaustenization)

SM490A

SM490A

( 1200

)

[7]

TEM

100nm

SM490A

50m

(grain

boundary ferrite)(Widmanstatten ferrite)

(acicular ferrite) (inclusion)

(Micro-phase)...

TEM

5

1~101

micro-phase micro-phase

3.2

3.2.1

[8] SM490A

SM490A

(MPa) EL

SM490 537 17.3%

SA 606 26.47%

SB 600 25.68%

SC 599 23.78%

3.2.2

(weldability)

[4]

(Hv)

SM490A

Microphases Microphases

[6]

SM490A

NbNb

(Ar3)

Micro-phase

SA

SA

Gowrisankar[9]

Dorschu Stout[10]

Weld Maximum Minimum SM490A170

180

190

200

210

220

230

240

250

HV 0

.2

Distance (mm)

SA SB SC

Weld Maximum Minimum SM490A

170

175

180

185

190

195

200

205

210

HV 0

.2

Distance (mm)

SA SB SC

Weld Maximum Minimum SM490A

180

190

200

210

220

230

HV 0

.2

Distance (mm)

SA SB SC

3.2.3

AWS1.1 4.8.3.3

1. 1/8inch(3mm)

2. 1/32inch(1mm) 1/8inch(3mm)

3/8inch(9.5mm)

3. (Corner crack)1/4inch(6mm)

1/8inch(3mm)

SA SB SC

SA SB SC

3.2.4

Charpy V-notch

25C

~

notch

n*(n

)

EDX

inclusion

[11]

DA

inclusion

inclusion

inclusion [10][11]

SM490

Nb

Nb

SM490A

[12] EDX (

) MnS

(I)

SM490A 12.512 0.250791

HAZ-SA 8.08 0.75896

HAZ-SB 8.44 0.680468

HAZ-SC 8.69 0.470208

W-SA 17.21 0.586228

W-SB 17.00 1.220092

W-SC 19.44 0.666107

SA SB

SC

EDX

3.3

3.3.1

(corrosion potential)

Tafel (Tafel extrapolation)

(corrosion current)

Tafel 50mV

Tafel

50mV

(linear polarization

method)

10mV

SA

SBSC 2

order 3 order

3.5wt%NaCl

1E-7 1E-6 1E-5 1E-4 1E-3 0.01-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

Pot

entia

l (V

)

Log I (A/cm2)

SM490A

1E-10 1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0.01-1.2

-1.0

-0.8

-0.6

-0.4

Pot

entia

l (V

)

Log I (A/cm2)

SA SB SC

mV

(A/cm2)

(ohm*cm2)

BM-SM490 -699 5.578*10-5 6.082*102

WM-SA -665 5.31 x 10-6 5.876*103

WM-SB -669 3.38 x 10-8 1.156*106

WM-SC -652 2.69 x 10-8 1.408*106

SM490A

SA SB

SC

3.3.2

SM490A 3.5wt%NaCl

SM490A

(Positive Pitting hysteresis loop)

SM490A

(negative pitting

hysteresis loop)

1E-7 1E-6 1E-5 1E-4 1E-3 0.01

-1.0

-0.5

0.0

0.5

1.0

1.5

Pote

ntia

l (V

)

Log I (A/cm2)

SM490A

1E-7 1E-6 1E-5 1E-4 1E-3-1.5

-1.0

-0.5

0.0

0.5

1.0

Pot

entia

l (V

)

Log I (A/cm2)

SA

1E-7 1E-6 1E-5 1E-4 1E-3-1.5

-1.0

-0.5

0.0

0.5

1.0

Pot

entia

l (V

)

Log I (A/cm2)

SB

1E-8 1E-7 1E-6 1E-5 1E-4 1E-3-1.5

-1.0

-0.5

0.0

0.5

1.0

Pote

ntia

l (V

)

Log I (A/cm2)

SC

BM-SM4

90A

SA SB SC

mV -684 -737 -671 -660

(A/cm2) 3.312*10-5 3.79*10-6 5.733*10-6 3.88*10-7

(mV) 148 320 271 204

(mV) -632 242 - -

4.

inclusion micorphase

SM490A

SM490A

SM490A

[1] JIS G3106-2004 Rolled Steels for Welded

Structure(2004)

[2] (2008)

[3] -490/FCAW-G (2008)

[4] ANSI/AWS D1.1/D1.1M:2002 Structural Welding Code

- Steel (2002)

[5]

P11(1990)

[6] Najma Shams, Jounal of Materials, 1985, p.21.

[7] M.N.Waton, P.L.Harrison and R.A. Farrar, Welding and

Metal Fabrication, 1981, p.101.

[8] -(1995).

[9] I. Gowrisankar, A. K. Bhaduri, V. Seetharaman, D. D. N.

Verma, D. R. G. Achar, Effect of Number of Passes on

the Structure and Properties of Submerged Arc Welds of

AISI Type of 316L, Welding JOURNAL, Vol66, 1987,

p.147-p.154.

[10] Gladman, Effect of Second-phase Particle on the

Mechanical Properties of Steel, Iron and Steel

Interstitute, 1971.

[11] J.F.Knott, Fundamentals of Fracture Mechanics,

Butterworth, 1973.

[12] T.J. Baker and J.A. Charles, Deformation of MnS

inclusions in steel, J. Iron Steel Inst. 210 (1972),

p.680p.690.