welding 1.1(Welding):1 1 (fusion welding) 2 (pressure welding) 3 (brazing, soldering)

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1.21.2.1:welded jointbase metalheat affect zonebond lineareaweld123

1.2.2.1.welding arc(cathodearc columnanode103104mm 36% 2400K 43% 2600K 21% 6000~8000KAe UAe

molten pool1231core wire2welding wire3coating1)23)4)

Advance metal materialHigh Strength low alloy steelpipeline steel)ULCB Ultra- low carbon bainitic)Ultra-fine grain steel acicular ferrite steel

base metalweld metal bond zoneheat affect zone1aproeutectoid ferritePF770~680grain boundary ferriteGBFbferrite side plateFSP 700~550

dintergrain FerriteIGF650~450 efine grain ferriteFGF500650fbainiteB 500gmartensiteM 300

23(heat affect zoneHAZ(weld thermal cycle) VTmt 1)11002)850~1100 3)700~850 )HAZ1LBZlocal brittle zone

2UCGHAZUnaltered coarse grain HAZ3IRCGHAZIntercritically reheated CGHAZ4SRCGHAZ (Subcritically reheated CGHAZ HAZ80~200m (Oxide Metallurgy) CRcontrolled rolling controlled coolingHAZ

1)narrow gap welding 2~5mm0.5mmHAZ1mm10mm2) laser beam welding20mm electron beam welding250mm plasma arc welding20mm3) 4)

Under water welding 12)3)4)5)

1212345Welding in space

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