双面焊316L不锈钢焊缝裂纹失效研究

Weld Crack Failure Analysis of 316L Austenite Stainless Steel by Double-sided Welding

采用金相显微镜(OM)、扫描电镜(SEM)和能谱分析等方法,观察了双面焊不锈钢焊缝显微组织及裂纹分布特征,分析了双面焊接对焊缝显微组织、应力状态和元素分布特征的影响。结果表明裂纹区域显微组织无异常,先焊面焊缝边缘产生裂纹的原因主要是由于后焊面焊接时对其产生了拉应力,同时由于再加热作用导致先焊面焊缝C、Cr、Mo等元素迁移,在晶界处形成贫铬现象,降低了焊缝的抗裂纹扩展能力,进而在先焊面焊缝边缘形成了裂纹。

To investigate effect of double-sided on weld microstructure, weld stress state and chemical element distribution, Microstructure and cracks of double-sided Welding of 316L austenite stainless steel were observed by OM, SEM and EDS. The results showed that the microstructure of weld joint was normal. The reason causing cracking of weld joint earlier was tensile stress, which produced by the later welding. Meanwhile, another important reason was element migration （C, Cr, Mo, etc） caused by reheating in weld joint earlier. The chromium depletion in grain boundary impaired the property of resistance to propagation of cracks, and the cracks were formed at weld joint.