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为提高普通碳钢表面耐蚀性,利用5 kW横流CO2激光加工设备在45钢表面激光熔覆制备304不锈钢涂层。采用光学显微镜、XRD和SEM等手段对所制备涂层的显微组织及相组成进行分析,并分别利用化学侵蚀实验和阳极极化曲线对涂层的耐腐蚀性能进行测试。结果表明:熔覆层由铁素体和奥氏体双相组成,自界面处到顶端逐渐由单一粗大的柱状晶向尺寸约为5~8μm的致密细小的等轴晶过渡;在15%FeCl3溶液中静置24 h后,基材被腐蚀而熔覆层无明显变化;熔覆层的自腐蚀电位比基材高290 mV,仅比商用304不锈钢低70 mV,而3者之中熔覆层的自腐蚀电流密度最低。
In order to improve the surface corrosion resistance of ordinary carbon steel, 304 stainless steel coating was prepared by laser cladding on the surface of 45 steel with a 5 kW cross-flow CO2 laser processing equipment. The microstructure and phase composition of the prepared coating were analyzed by optical microscope, XRD and SEM. The corrosion resistance of the coating was tested by chemical erosion and anodic polarization respectively. The results show that the cladding consists of two phases of ferrite and austenite and transitions from a single coarse columnar crystal to a dense fine equiaxed crystal with a size of about 5 ~ 8μm from the interface to the top. In 15% FeCl3 After standing for 24 h in the solution, the substrate was eroded without any significant change in the cladding layer. The self-corrosion potential of the cladding layer was 290 mV higher than that of the substrate, which was only 70 mV lower than that of commercial 304 stainless steel. Layer self-corrosion current density is the lowest.