ABSTRACT

Ultra-low cycle fatigue (ULCF) tests of corroded steel specimens were conducted to illustrate the effects of corrosion on the ULCF properties and fracture mechanism of structural steel. Fatigue crack initiation and propagation process and fracture morphology were observed respectively. The results indicate that the ULCF fracture life of corroded specimens decreases more with increasing surface roughness. The crack-initiation life of corroded specimens is less than half of the fracture life. With corrosion degree increases, the area of the ULCF crack propagation zone expands observably, where it gets harder to find dimples, indicating a transition from ductile to brittle fracture mode.

摘要

对腐蚀钢试样进行了超低周疲劳 (ULCF) 试验，以说明腐蚀对结构钢的 ULCF 性能和断裂机制的影响。分别观察疲劳裂纹的萌生和扩展过程及断裂形貌。结果表明，随着表面粗糙度的增加，腐蚀试样的ULCF断裂寿命下降得更多。腐蚀试样的裂纹起始寿命小于断裂寿命的一半。随着腐蚀程度的增加, ULCF 裂纹扩展区的面积明显扩大, 更难找到凹痕, 表明从韧性断裂模式过渡到脆性断裂模式。