Effects of Shot-Blasting and Induction Hardening on the Fatigue Strength of Hot-Forged Wheel Bearing Hubs

Abstract

Hot-forged wheel bearing hubs are manufactured using a complicated fabrication process chain to obtain the desired microstructure and mechanical properties in different zones that experience varying local stress states. The different process steps modify the surface roughness and the residual stresses distribution and therefore affect the fatigue behavior of the component. This study focuses on the effects of the shot-blasting and the induction hardening stages on the fatigue failure mechanisms and aims to propose an appropriate fatigue design method. Fatigue tests are performed on industrial components and on conventional material specimens to evaluate the influence of the surface roughness and the residual stresses on the fatigue strength. The relaxation of residual stresses, caused by the heat treatment and the cyclic loading during fatigue testing, is shown to annihilate the positive effect of shot-blasting, and the fatigue strength decreases because of the detrimental surface roughness, created by shot-blasting. Different multiaxial fatigue criteria are tested to take into account the manufacturing process operations.