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利用激光表面预处理技术清除船用高强钢907A表面油漆等污物,以期改善焊接接头性能;对预处理后的母材进行激光焊接,分析激光表面预处理对接头组织性能的影响。结果表明:激光表面预处理后,试板表面油漆被去除,并产生一些微小的凹陷,深度小于150μm,预处理区宽度变化范围是3437.61~7150.21μm;较合理的激光表面预处理参数是激光功率为3.5 k W,离焦量为450 mm,速度为1.8 m/min。激光焊接后,焊缝试样横截面由未预处理试样的“抛物线形”变为有预处理试样的“双曲线形”。焊缝区组织为粗大的板条马氏体和少量残余奥氏体,热影响区组织为粗细不同的马氏体组织、细小马氏体与铁素体的混合组织等;焊缝与热影响区的显微硬度均高于母材,热影响区内出现回火软化。
Laser surface pretreatment technology was used to remove the surface paint of marine high strength steel 907A so as to improve the performance of welded joint. Laser welding was performed on the pretreated base metal to analyze the influence of laser surface pretreatment on the microstructure and properties of joint. The results show that after laser surface pretreatment, the paint on the surface of the test board is removed and some small depressions are formed, the depth is less than 150μm and the width of pretreatment area is 3437.61 ~ 7150.21μm. The more reasonable laser surface pretreatment parameters are laser power 3.5 kw, defocus amount 450 mm, speed 1.8 m / min. After laser welding, the cross section of the weld specimen changed from the “parabolic shape” of the non-pretreated specimen to the “hyperbolic shape” of the preconditioned specimen. The weld zone is composed of coarse lath martensite and a small amount of retained austenite, the heat affected zone is composed of martensite with different thickness, mixed martensite with ferrite, etc .; The microhardness of the zone is higher than that of the base metal, tempering softening appears in the heat affected zone.