Ultra-low cycle fatigue properties and fracture mechanism of corroded structural steel

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.

Development of ultra-low cycle fatigue life prediction model for structural steel considering the effects of surface roughness, loading frequency, and loading amplitude

“…Song et al, (2021a) observed a similar reduction effect in the ULCF life of steel bridge piers with the increase in corrosion level. In another study by Song et al, (2021b), it was investigated that corrosion induced surface roughness has a dominant impact on the ULCF life of steel specimens. By increasing the corrosion time from 2 to 10 weeks, the average surface roughness increased by a maximum value of 6.52 μm.…”

“…McKelvey and Fatemi (2012) checked the fatigue life of forged steel and developed life curves as a function of hardness based on their experimental findings. Song et al, (2021aSong et al, ( , 2021b) investigated the ULCF properties and fracture process of corroded steel and found that fatigue life is significantly reduced by the increasing level of surface roughness induced by the corrosion process. Additionally, processing parameters are known to have a strong impact on fatigue life, and variation in surface morphology largely affects the LCF life (Hasunuma et al, 2019).…”