油气工程用Inconel 718合金激光焊接头的氢脆行为

采用激光焊接工艺,对油气工程用4 mm厚经1030 ℃×2 h固溶+780 ℃×8 h时效和1030 ℃×2 h固溶+780 ℃×16 h时效两种热处理后的Inconel 718合金进行激光焊接,结合微观组织分析、拉伸性能分析和断口形貌分析,对合金母材及激光焊接头在原位充氢条件下的氢脆行为进行了研究。结果表明:长时间时效导致δ相大量析出,使合金母材的氢脆敏感性指数从正常时效态的0.27提高到过时效态的0.48。激光焊接头整体的氢脆敏感性没有受焊前热处理的影响,分别为0.39和0.38;由于焊缝内Laves相的析出,导致激光焊接头的氢脆敏感性高于正常时效态的母材。

Hydrogen embrittlement behavior of oilfield-grade Inconel 718 alloy laser welded joint

The oilfield-grade Inconel 718 alloy, which was respectively heat treated by 1030 ℃×2 h solution treatment+780 ℃×8 h aging and 1030 ℃×2 h solution treatment+780 ℃×16 h aging, was welded by laser beam welding process. The hydrogen embrittlement behaviors of the base metal and welded joint of the alloy were studied during in situ hydrogen charging by analyses of microstructure, tensile properties and fracture morphologies. The results show that longer time aging induces large amount of δ phase, resulting in the hydrogen embrittlement susceptibility index of the base metal increasing from 0.27 to 0.48. The hydrogen embrittlement susceptibility of the welded joint is not affected by the heat treatment before welding, which is 0.39 and 0.38, respectively. However, the precipitation of Laves phase in welded zone induces that the hydrogen embrittlement susceptibility of the welded joints is higher than that of base metal aged for 8 h.