超声冲击对SMA490BW耐候钢焊接接头腐蚀疲劳的影响

Effect of Ultrasonic Impact on Corrosion Fatigue Performance of Welded Joint of SMA490BW Steel

采用USP-300超声表面加工装置对SMA490BW耐候钢表面进行超声冲击处理。研究超声冲击前后试件的显微组织、显微硬度和残余应力,比较超声冲击前后SMA490BW耐候钢焊接接头的腐蚀速率和腐蚀疲劳寿命。通过光学显微镜观察超声冲击后SMA490BW耐候钢的显微组织,采用测试仪器测试焊接接头的表面硬度和残余应力,分析超声冲击提高SMA490BW耐候钢抗腐蚀性及其疲劳寿命的机理。结果表明,超声冲击处理能使材料表层晶粒细化形成致密的塑性变形层,提高显微硬度,并在材料表面引入有效的残余压应力,降低腐蚀速率,减小失重量。同时,超声冲击处理后裂纹扩展路径变得更加复杂,裂纹扩展速率降低,焊接接头腐蚀疲劳寿命得到提高。

The surface of SMA490BW weathering steel was subjected to ultrasonic impact treatment by USP-300 ultrasonic surface processing device.The microstructure,microhardness and residual stress of the specimens before and after ultrasonic impact were studied,and the corrosion rate and corrosion fatigue life of the welded joints of the SMA490BW weathering steel before and after ultrasonic impact were compared.The microstructure of the SMA490BW weathering steel after ultrasonic impact was observed by optical microscope,and the surface hardness and residual stress of welded joint were measured by testing instrument.The mechanism of improving corrosion resistance and fatigue life of SMA490BW weathering steel by ultrasonic impact was analyzed.The test results show that ultrasonic impact treatment can refine the surface grain to form a dense plastic deformation layer,improve the microhardness,introduce effective residual compressive stress on the surface of the material,reduce the corrosion rate and the weight loss.At the same time,after ultrasonic impact treatment,the crack propagation path becomes more complicated,the crack propagation rate decreases,and the corrosion fatigue life of welded joints increases.