10CrNi3MoV钢气体保护焊氢致裂纹的萌生和扩展

Initiation and Propagation of Hydrogen-Induced Crack in MIG Welding 10CrNi3MoV Steel

研究了气体保护焊 (WM96 0 -S焊丝和Ar +2 0 %CO2 气体 )不预热焊接5 90MPa级 10CrNi3MoV钢氢致裂纹萌生和扩展规律。在 - 5℃和相对湿度 80 %的条件下 ,采用小铁研抗裂性试验方法进行抗裂性试验。通过比较单道焊和双道焊的裂纹率及裂纹扩展方式说明 ,MIG焊 (熔化极惰性气体保护电弧焊 )焊缝具有良好的抗裂能力 ;双道焊的抗裂能力显著高于单道焊 ;单道焊时氢致裂纹为沿晶方式扩展 ,双道焊时氢致裂纹为穿晶方式扩展。双道焊时 ,第一道焊缝HAZ(热影响区 )过热区受第二道焊缝焊接热循环作用 ,在根部HAZ粗大晶粒晶界两侧产生的细小晶粒是影响氢致裂纹扩展方式和提高抗裂能力的主要原因。根据裂纹扩展方式的变化 。

This paper deals with the initiation and propagation of hydrogen induced crack while 10CrNi3MoV steel of 590 MPa grade was welded by MIG welding using WM960 S wire and Ar+20%CO 2 mixed gas without preheating.Tekken cracking test was operated under the condition of 5 ℃ and 80% relative humidity.Compared between the single and the multipass welding,the mode and rate of cracking propagation demonstrated that weld metal has good capability to resist crack propagation.Multipass welding with transcrystalline crack possesses better crack resistance than single pass welding with intercrystalline crack.Because of the effect of heat cycle by the second pass in multipass welding fine grains occurred at both sides of coarsed grain boundary in the root of joint,which can change the mode and rate of crack propagation.According to the mode of crack propagation the mechanism of crack initiation and propagation was also discussed.