CSP流程Ti微合金化高强钢的疲劳性能

Fatigue properties of Ti microalloyed high-strength steel by CSP process

采用升降法对CSP工艺生产的2mm厚Ti微合金化高强钢的疲劳性能进行研究.结果发现:高强钢的抗拉强度为830 MPa;疲劳强度为685 MPa,约为抗拉强度的0.83倍;伸长率为18.8%.绘制了高强钢的S--N曲线,并拟合出疲劳寿命与最大应力的关系.通过扫描电镜对疲劳断裂机理进行了分析.宏观疲劳断口可见明显的裂纹源区、扩展区和瞬断区形貌.疲劳裂纹起始于带钢表面微裂纹;疲劳扩展区存在微观疲劳辉纹、二次裂纹和宏观疲劳贝纹线;瞬断区出现撕裂棱,兼有韧窝存在.

The fatigue properties of 2 mm-thick Ti-microalloyed high-strength steel produced in a CSP line was studied by the up-down method. It is found that the tensile strength of the steel is 830 MPa, the fatigue strength is 685 MPa, about 0. 83 times as large as the tensile strength, and the elongation is 18. 8% . The S-N curve of the steel was drawn out and the relationship between the maximum stress and fatigue life was fitted. The cracking mechanism was analyzed by scanning electron microscopy. The crack source, expansion region, and eventual failure region appears significantly in the microscopic structure. Fatigue cracks initiate from microcracks on the strip surface. Microcosmic fatigue striations, secondary cracks, and macroscopic fatigue bay ridges are observed in the fatigue extension region. The eventual failure region meets the characteristics of tear edge morphology along with dimples.