Analysis and prediction of residual stress in deep cold rolling of Ti-6Al-4V

Abstract

Deep Cold Rolling (DCR) is a mechanical surface treatment method that has been proven to enhance fatigue life of components by inducing deep compressive residual stress (RS), increasing surface hardness and improving surface roughness.This work analyzes the effect of DCR on RS and coupled with the finite element (FE) modelling, deepens the understanding of the mechanics of how DCR imparts the RS into the component, especially at the subsurface region. A three-zone RS profile hypothesis is developed and proven through the use of microstructure and hardness analysis.An analytical model is also developed to predict the RS profile based on the key performance variable inputs. This allows designers and engineers a quick method of developing a starting point for experimentation.The knowledge gained is applied to thin aerofoil-foil like specimens and a technique for achieving a compressive RS zone away from the treated region is proposed.