焊接速度对异种不锈钢激光焊接接头组织与性能的影响

Effect of Welding Speed on Microstructure and Properties of Laser Welded Joints of Dissimilar Stainless Steels

以1 mm厚0Cr18Ni9和1Cr17Ni2两种不锈钢激光双面焊接接头为研究对象,对不同焊接速度下接头的宏观形貌、金相组织、显微硬度和抗拉性能进行了分析。结果表明:焊接速度过小会导致焊缝表面出现飞溅和焊瘤等缺陷,提高焊接速度可改善焊缝表面质量,但熔池深度也随之减小。热影响区分为四个形状不规则的区域,以晶粒粗大的柱状晶为主;随着焊接速度增大,焊缝组织晶粒逐渐得到细化,硬度降低,接头试样的伸长率和抗拉强度均先增大后减小。焊接速度大于400 mm/min或低于250 mm/min都无法获得性能优良的焊接接头,当焊接速度为300~350 mm/min时,接头组织均匀致密,抗拉强度超过了0Cr18Ni9母材。

The laser double-sided welded joints of stainless steel of 1 mm thick 0Cr18Ni9 and 1Cr17Ni2 were taken as research objects,and the macroscopic morphology,microstructure,microhardness and tensile properties of the joints under different welding speeds were analyzed.The results show that small welding speed will lead to the weld surface spatter,weld nodules and other defects.Increasing welding speed can improve the surface quality of weld seam,and the depth of molten pool decreases accordingly.The heat affected zone is divided into four irregularly shaped regions,which is mainly composed of columnar crystals with coarse grains.With the increase of welding speed,the grain of weld microstructure is gradually refined and the hardness reduces,and the elongation and tensile strength increase first and then decrease.When the welding speed is more than 400 mm/min or less than 250 mm/min,the welding joints with good performance cannot be obtained.When the welding speed is 300-350 mm/min,the microstructure of the joint is uniform and dense,and the tensile strength exceeds that of 0Cr18Ni9 base metal.