利用5 kW碟片激光器对1.1 mm厚的先进高强钢进行对接填丝焊,采用正交试验设计激光工艺参数,并借助万能力学试验机、显微硬度仪、光学显微镜和扫描电镜对焊接接头的拉伸强度、显微硬度、表面与截面组织进行分析,研究激光工艺参数对焊接接头力学性能及组织的影响。结果表明,在试验参数范围内,激光功率与焊接速度是影响接头性能最重要的参数。在合理的工艺参数下,即线能量大于阈值时,可以获得均匀、连续以及表面光滑的焊缝形貌,抗拉强度为母材的90%以上。接头均存在熔合区硬化和外侧热影响区软化现象,熔合区组织主要由板条马氏体和先共析铁素体组成,热影响区组织因回火马氏体的大量出现而发生软化,从而影响接头拉伸性能。

A 5 kW disk laser is used for the butt filler wire welding of 1.1 mm thick advanced high strength steels. The laser process parameters are designed by the orthogonal test, and the tensile strength, microhardness, surface and cross section of these welded joints are analyzed by the universal mechanical test machine, microhardness tester, optical microscope and scanning electron microscope. In addition, the effects of laser process parameters on the mechanical properties and microstructures of the welded joints are studied. The results show that laser power and welding speed are the most important parameters influencing the performances of joints in the range of test parameters. Under the reasonable process parameters, that is, when the line energy is greater than the threshold value, the weld appearance with a uniform, continuous and smooth surface can be obtained, and the tensile strength is more than 90% of that of the base material. There exist for all the joints the phenomena of fusion zone hardening and lateral heat-affected zone softening. The microstructure of the fusion zone is mainly composed of lath martensite and proeutectoid ferrite. The microstructure of the heat affected zone is softened due to the emergence of large quantities of tempering martensite, which affects the tensile properties of joints.