某大型电站锅炉屏式过热器TP347HFG/12Cr1MoVG异种钢钨极气体保护全氩弧焊接接头服役1.5×10⁴ h后频繁发生开裂泄漏。利用宏观观察、金相检验、扫描电镜分析及力学性能测试等方法对该过热器TP347HFG/12Cr1MoVG异种钢接头进行开裂原因分析。结果表明:异种钢接头焊接工艺不当,导致了12Cr1MoVG侧熔合线镍基填充金属与母材未有效熔合,使TP347HFG/12Cr1MoVG异种钢接头发生早期开裂失效。

The TIG welded joint of TP347HFG/12Cr1MoVG dissimilar steel for platen superheater of a large utility boiler frequently cracked and leaked after serving for 1.5×10⁴ h. The cracking cause of the welded joint between TP347HFG/12Cr1MoVG dissimilar steel was analyzed by means of macroscopic observation, metallographic examination, SEM analysis and mechanical property test. The results show that the early cracking failure of TP347HFG/12Cr1MoVG dissimilar steel joint was mainly caused by the improper welding process, which led to the ineffective fusion of Ni based filler metal and base metal in the fusion zone of 12Cr1MoVG side.