Nb 함유 HSLA 강의 저주기 피로실험에서 분위기의 영향 및 소성변형

Abstract

The influence of plastic strain amplitude and gaseous environmental on the low cycle fatigue properties has been studied in a Nb-bearing HSLA steel. The cyclic stress-strain curve (CSSC) shows a plateau nor persistent slip bands (PSB’s) have been observed in the bulk. The cyclic plastic strain energy (∆W) and the accumulated plastic strain energy (W) have been calculated as a function of plastic strain amplitude (∆εp) in the form of K (∆εp/2)N. The computed values of ∆W and W are in good agreement with the experimental data. The vacuum environment enhanced fatigue crack initiation life, fatigue life and W. The environmental effect becomes more severe as the plastic strain amplitude decrease. Tensile properties, cyclic stress response and ∆W are not affected by the gaseous environment.