热丝填充激光焊316LN热裂纹产生的成因分析与研究

Study on the Causes of Hot Crack in Laser Welding 316LN with Hot Wire Filler

在热丝填充激光焊接316LN平板试验中,产生了热裂纹。为探讨热裂纹产生的成因,焊后对母材和焊材进行了化学成分分析,借助光学显微镜对母材和焊缝进行了显微组织分析,并研究分析产生热裂纹的力学因素。研究分析表明,冶金因素和力学因素相互作用下产生热裂纹。冶金因素主要包括焊缝为一次结晶为γ的纯奥氏体组织及含有热裂纹促进元素S、P、Si等,力学因素主要是温度梯度大及热膨胀系数大而导致的拉应力过大的缘故。

The thermal crack is caused in the hot wire filled 316LN plate test of laser welding. Chemical analysis hasbeen performed after welding on the base metal and welding material, The microstructure of base metal and weld wasanalyzed using optical microscope, and the mechanical factors of thermal cracking were studied. Results show that thethermal cracking is caused by both metallurgical factors and mechanical factors. The metallurgical factors mainly werethat the weld bead microstructure was pure austenite of primary crystallization of γ phase and there were some hotcrack promoting elements such as S, P, Si and so on. The mechanical factors were mainly the steep temperature gra-dient and the large thermal expansion coefficient induced overloading tensile stress.