采用焊接热模拟通过改变冷却时间（t8/5），研究了金属芯焊丝E120C-K4多道焊熔敷金属模拟粗晶区（CGHAZ）显微组织对冲击韧性的影响规律. 结果表明，当t8/5为6 ~ 12 s时，CGHAZ显微组织由蜕化上贝氏体、粒状贝氏体和针状铁素体组成，奥氏体晶粒内部形成复相分割结构，冲击韧性最好. 而当t8/5为30 ~ 120 s时CGHAZ显微组织主要由粒状贝氏体和针状铁素体组成，冲击韧性下降. t8/5为120 s时，冲击韧性最差，–40 ℃冲击吸收能量仅为24 J. t8/5为6 ~ 12 s时韧性改善的关键是形成复相分割微观结构；晶粒细小；单位距离上大角度晶界数量多.
苏小虎
,
栗卓新
,
李红
,
JinKim Hee
,
孟波
. 高强钢金属芯焊丝E120C-K4熔敷金属粗晶区显微组织对冲击韧性的影响[J]. 焊接学报, 2019
, 40(10)
: 48
-53
.
DOI: 10.12073/j.hjxb.2019400262
The effect of microstructure as a function of welding cooling time (t8/5) from 800℃ to 500℃ on the impact toughness of coarse grained heat affected zone (CGHAZ) of deposited metal of metal cored wire E120C-K4 was investigated by welding thermal simulation. The results showed that the microstructure of CGHAZ was mainly composed of degenerate upper bainite (DUB) granular bainite (GB) and Acicular ferrite(AF) at t8/5 from 6 s to 12 s, forming the interlace multiphase microstructure, then the optimal impact toughness was obtained. The microstructure of CGHAZ formed with granular bainite (GB) and Acicular ferrite(AF) and the impact toughness decreased when t8/5 from 30 s to 120 s. The absorbed energy of CGHAZ was only 24 J at −40℃ at t8/5 of 120 s, the worst impact toughness. The key of improving impact toughness at t8/5 from 6 s to 12 s was:① forming the interlace multiphase microstructure; ② refining grains; ③ more high-angle grain boundaries per unit distance.
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