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超薄不锈钢在航天、医疗器械、日用品中的应用日趋广泛,对其激光焊接质量也提出了更加苛刻的要求。由于材料很薄,易于汽化穿孔,要想得到连续、无烧穿的焊缝,关键是对参数的精确控制。采用光纤激光实现了0.2mm厚1Cr18Ni9Ti不锈钢片的对接及搭接焊。研究了激光功率、焊接速度、离焦量、脉冲频率、占空比等工艺参数对焊缝表面成形的影响规律,并对焊缝显微组织及接头力学性能进行了考察。结果表明,在连续焊模式下,即使采用非常小的热输入,也无法避免焊缝起始及收尾处出现的烧穿;脉冲焊模式下,热输入一定时,采用低的脉冲频率、占空比及焊接速度相比高的脉冲频率、占空比及焊接速度可以有效减少单脉冲能量,从而避免焊缝在起始及收尾处的烧穿。在优化的工艺参数下可得到表面成形良好、无烧穿的对接及搭接焊缝。焊缝中心区由柱状晶与等轴晶组成,几乎不存在热影响区,对接接头抗拉强度可高于母材,搭接接头经拉剪测试断于母材。
Ultra-thin stainless steel in aerospace, medical equipment, daily necessities in the increasingly widespread application of its laser welding quality also made more stringent requirements. Because the material is very thin, easy to vaporize perforation, in order to get continuous, no burn through the weld, the key is the precise control of the parameters. Using fiber laser to achieve 0.2mm thick 1Cr18Ni9Ti stainless steel butt and lap welding. The effects of laser power, welding speed, defocusing amount, pulse frequency and duty cycle on the forming of weld surface were studied. The microstructure of the weld and the mechanical properties of the joint were investigated. The results show that in the continuous welding mode, even if using a very small heat input, can not be avoided at the beginning and end of the weld burn through; pulse welding mode, the heat input is a certain, the use of low pulse frequency, the duty cycle The pulse frequency, duty cycle and welding speed, which are higher than the welding speed, can effectively reduce the single-pulse energy, so as to avoid the burn-through of the weld at the beginning and the end. Under the optimized process parameters, the surface is formed well, without burn-through butt and lap weld. The weld center area consists of columnar crystals and equiaxed grains with almost no heat affected zone. The tensile strength of the butt joint can be higher than that of the base metal. The lap joint is cut off from the base metal by the tensile shear test.