冷焊修复层在H_2S环境下的开裂行为研究

Cracking Behavior of Cold-welding Layer on A350 LF2 Steel in H_2S Environment

研究了不同工艺条件下A350 LF2钢冷焊修复层的组织特征以及在NACE标准实验条件下的硫化物应力开裂(SSC)和氢致开裂(HIC)特征。结果表明,低的热输入量、短持续时间和高占空比条件下容易产生未熔合焊接缺陷,Ar气输入量较大则容易产生焊接气泡。H_2S腐蚀实验结果表明,冷焊修复层对SSC不敏感,但是却极易在焊接缺陷处产生HIC裂纹,裂纹在未熔合区以及焊缝气泡的边缘萌生,并沿着焊接熔合线在焊缝一侧扩展。适当的冷焊修复工艺参数能消除焊接缺陷,有利于提高焊缝的抗HIC开裂性能。

The microstructures of the cold-weld layers on A350 LF2 steel prepared with different pro- cess parameters was characterized and then their sulfide stress cracking （SSC）- and hydrogen induced cracking （HIC）-behavior was assessed corresponding to NACE standard experimental conditions. Re- sults show that the welding process with low heat input, short duration and high duty cycle can lead to in- complete fusion, while high influx of Ar is easy to generate bubbles. The cold-weld layer is not sensitive to SSC, however it is easy to produce HIC cracks at welding defects. The cracks initiate in the non-fusion zone and the edge of weld bubbles, and then propagate along welding line. Appropriate parameters can eliminate welding defects, thereby, the prepared cold weld layer may possess good resistance to HIC.