The effect of retained austenite on the wear mechanism of bainitic ductile iron under impact load

Abstract

The effect of retained austenite on the impact wear resistance of bainitic ductile iron is studied. Two kinds of bainitic ductile iron with different morphologies of retained austenite were fabricated via continuous cooling process. The impact wear test was carried out on an impact abrasive wear tester under different loads. The results showed that the wear behavior of bainitic ductile iron could be divided into three stages during the impact wear test. There was a close relationship between the wear resistance and microstructure characterization, especially the morphology, distribution and stability of retained austenite. Thin film retained austenite with appropriate stability could improve the wear resistance of ductile iron, while a large number of low stability and bulky retained austenite would reduce the wear resistance under high impact load condition. The wear mass loss of bainitic ductile iron with thin film retained austenite (BDI A) was lower than that of bainitic ductile iron with bulky retained austenite (BDI B). The wear mechanism of BDI A is mainly plough wear and fatigue wear, while that of BDI B is plough wear, fatigue wear and deformation fatigue flake.