The effects of the cold expansion degree on the fatigue crack growth rate in rail steel

Abstract

This study investigates the effects of the cold-expansion degree on the fatigue strength of rail steels. Two degrees of cold-expansion, 2% and 4%, and two stress levels were investigated. Results indicate that cold-expansion postpones crack initiation and extends fatigue life, especially with higher degrees of cold-expansion and lower stress levels. Linear superposition principle coupled with the weight function method results in an overestimated fatigue life of cold-expanded specimens, suggesting that reliable predictions can be achieved if both the residual stresses redistribution due to propagating crack and the crack closure effects due to plastic wake generation are considered in the simulations.