ITER用316LN激光焊接接头显微组织和力学性能研究

Microstructure and Mechanical Properties of 316LN Laser Welded Joint for ITER

以21 mm厚的316LN奥氏体不锈钢板为研究对象,采用双面对称施焊的方式进行激光焊接,并对激光焊接接头的显微组织和力学性能进行了分析。结果表明,采用锁底式打底焊接时,焊缝中的主要缺陷是焊接气孔。减小钝边厚度,采用单面打底焊后,气孔问题得到解决。焊缝区显微组织为单相奥氏体,不同位置的显微组织呈现不同的结晶形态,焊缝中心处的等轴晶粒能有效抑制焊接裂纹的产生。激光焊焊接接头拉伸试样均断裂于母材处,弯曲样件表面未见任何微裂纹,焊接接头展现了良好的抗低温冲击性能。

Taking 21 mm thick 316 LN austenitic stainless steel plate as the research object, the laser welding tests were carried out with double-side symmetry welding, and the microstructure and mechanical properties of the laser welded joints were studied. The results show that when bottom locking welding is used, the main defects of the welding seam are porosity,which are solved by decreasing the root thickness and using the single side bottom welding. The microstructure of the weld zone is single austenite, and the microstructures in different locations show different crystalline forms. The equiaxed grain at the weld center can effectively suppress the production of welding cracks. The tensile specimens of laser welded joints all fracture in base metal, and there is no visible crack on the surface of the bending specimens, which shows that the welded joints has good low temperature impact resistance.