Influence of plastic prestraining on the fatigue crack propagation rate of S355MC and S460MC structural steels

摘要

Cold forming induces significant plastic deformation at corner locations of structural steel members, resulting in both material strain hardening and the development of residual stresses, which influence the fatigue resistance of the steel members. Reliable fatigue assessment at such critical locations requires knowledge of the influence of pre-existing plastic deformation on material behavior. The effect of plastic prestraining on the fatigue crack growth resistance of S355MC and S460MC structural steels has been evaluated experimentally. A comparative study, including fatigue crack growth and fracture resistance tests for both reference (non-prestrained) and prestrained materials, has been performed. The experimental results, which are correlated to examined microstructural features and fracture characteristics of the materials revealed that fatigue crack growth rates of the prestrained material are higher than the reference material in the low Δ_κ region. Also, the S460MC steel exhibits higher crack growth rates compared to S355MC steel within the examined Δ_κ range.