Fretting fatigue behavior and damage mechanism of cast Al-Si-Cu-T6 alloy under two surface roughness conditions

Abstract

This paper experimentally evaluates the fretting fatigue properties of cast Al-Si-Cu-T6 alloys against nodular cast irons with two surface roughnesses. A softening phenomenon contrary to the cyclic response behavior of plain cyclic loading is pointed out and discovered to be affected by persistent damage and cumulative plastic deformation. Two considerably different roughness conditions produce two entirely distinct damage mechanisms, and a schematic diagram is drawn to illustrate the discrepancy. The initiation and propagation of cracks are not only affected by fretting wear damage but also significantly depend on the microstructure, especially the α-Fe and (β + ω) phases play key roles. The realization of this research comprehensively reveals the fretting damage mechanism of Al-Si cast alloys under two characteristic contact surface states, which serves the fretting failure analysis of aluminum castings in the automotive industry.