残余应力对Super304H焊缝金属再热裂纹敏感性的影响

Effect of Residual Stress on Reheat Cracking Susceptibility of Super304H Austenitic Stainless Steel Weld Metal

采用预压缩CT试样的方法研究了残余应力对Super304H奥氏体不锈钢焊缝金属再热裂纹敏感性的影响。通过ABAQUS模拟结合EBSD表征分析了不同残余应力下的焊缝金属的塑性应变分布和位错密度分布,并从残余应力诱导焊缝金属晶内析出相的方面解释了残余应力对焊缝金属再热裂纹敏感性的影响。结果表明:高预压缩载荷的CT试样具有更高的残余应力,更容易产生再热裂纹。随着残余应力的增加,焊缝金属拉伸试样的抗拉强度逐渐降低。焊缝金属CT试样靠近U型口的高残余应力区域具有更高的位错密度和更高比例的亚晶,促进了晶内小颗粒相的析出,使得晶内硬化更为严重,再热裂纹更容易产生。

The effect of residual stress on the reheat cracking susceptibility of Super304H austenitic stainless steel weld metal by the pre-compressed CT specimen method was studied.The plastic strain and dislocation density distribution of weld metal under different residual stresses were analyzed by ABAQUS simulation combined with EBSD characterization.The effect of residual stress on the reheat cracking susceptibility was explained from the aspect of stress-induced precipitation.The results show that CT specimens with high pre-compression force have higher residual stress and are more likely to generate cracks.With increasing the residual stress,the tensile strength of the specimen is decreased gradually.The high residual stress region of the CT specimen closed to the U-shaped notch has higher dislocation density and subgrain,promoting the precipitation of the small intragranular phase,which makes the intragranular hardening more serious and the easy occurrence of reheat cracks.