Impact of Surface Roughness on the Yield Drop of Hot‐Rolled AZX311 Mg Alloy

Surface roughness control is crucial for optimizing the mechanical performance of magnesium alloys in various industrial applications. This study investigates the influence of surface roughness on the mechanical behavior of hot‐rolled AZX311 Mg alloy. Uniform scratches are made on the gauge length perpendicular to the loading direction by mechanical grinding using P‐2400 grit‐size sandpaper on one set of samples, while another set retains a polished surface. Uniaxial tensile tests reveal a significant decrease in yield strength for the rough‐surfaced samples compared to the polished samples. Surface profilometry confirms higher R_a values for the rough‐surfaced samples, indicating a noticeably rougher surface compared to the smoother polished samples. The rough surface exhibits V‐notch irregularities, acting as stress concentrators during mechanical loading, in contrast to the smoother profile of the polished samples. This behavior is corroborated by Vickers hardness testing, which shows the highest hardness values near the scratched surfaces indicating localized deformation and strain‐hardening effects.