Effect of milling surface topography and texture direction on fatigue behavior of ZK61M magnesium alloy

Material property and surface integrity are key parameters that influence the fatigue properties of metallic material, especially residual stress, microstructure, and surface topography. Multiple surface integrity parameters may change simultaneously during the process of surface formation, which makes it difficult to analyze the evolution rule of the individual parameter. In this paper, the influence of surface topography and texture on tensile fatigue properties of ZK61M magnesium alloy was studied. The ball-end milling method was applied to produce workpiece surfaces with three different morphologies and texture directions but ensuring the consistent residual stress, microstructure, and surface roughness in these three cases. The results showed that the fatigue life (14.5 × 10⁴ cycles) of workpiece with surface texture direction parallel to the fatigue loading direction was even larger than the fatigue life (8.8 × 10⁴ cycles) of the samples after polishing, and the fatigue life (3.2 × 10⁴ cycles) of workpiece was the lowest when the angle of the surface texture was 45 degrees obliqued to the fatigue loading direction, which is about 64% lower than the samples after polishing. The surface texture direction can be controlled independently by this method, which provides a new consideration factor for evaluating the influence of surface topography on fatigue life.