海上风机螺栓用钢的腐蚀及疲劳行为

Corrosion and Fatigue Behavior of Steel for Offshore Wind Turbine Bolts

通过干湿交替循环盐雾模拟海上风机螺栓所处浪花飞溅区和大气区服役环境,对螺栓用钢42CrMoA进行腐蚀试验。采用扫描电子显微镜(SEM)观察腐蚀产物并用能谱仪(EDS)检测其元素,采用光学轮廓仪表征腐蚀坑形貌,用原位疲劳试验机研究腐蚀后的疲劳裂纹扩展。结果表明:在干湿交替的循环盐雾环境中,42CrMoA钢单位面积腐蚀质量损失与腐蚀时间呈现幂函数规律;42CrMoA钢表面粗糙度与腐蚀时间之间呈线性关系;腐蚀坑促进了疲劳裂纹的萌生和扩展,多个裂纹的扩展与融合加速了试样的断裂,从而降低了疲劳寿命。

Corrosion tests were conducted on bolt steel 42CrMoA in the simulated service environment of offshore wind turbine bolts in the splash zone and atmospheric zone through alternating wet dry cycles of salt spray.The corrosion products were observed by scanning electron microscopy(SEM)and their elements were detected by energy dispersive spectroscopy(EDS).The morphology of corrosion pits was characterized by optical profilometer,and the fatigue crack growth after corrosion was studied by in-situ fatigue testing machine.The results show that in the cyclic salt spray environment with alternating dry and wet conditions,the corrosion mass loss per unit area of 42CrMoA steel and corrosion time exhibited a power function.There was a linear relationship between the surface roughness and corrosion time of 42CrMoA steel.The initiation and propagation of fatigue cracks were promoted by corrosion pits,and the expansion and merging of multiple cracks accelerated the fracture of the specimen,thereby reducing the fatigue life.