Effect of microstructure and punching method on residual stress formation of punched thick-plate advanced high-strength steels

Advanced high-strength steels (AHSSs) represent a promising advancement in materials for the automotive industry due to their exceptional combination of strength, ductility, and formability, offering a compelling alternative to conventional high-strength low-alloy (HSLA) steels. AHSSs, with a higher strength-to-weight ratio than that of HSLA, allow for the design of thinner gauges, resulting in substantial weight reduction and consequent fuel savings. However, applying AHSSs in the thick-plate configuration for heavy-duty trucks remains a challenging endeavor. This challenge stems from the sheet shearing processes required to manufacture chassis components, such as hole punching and trimming.
These processes more adversely affect the fatigue properties of AHSSs compared to conventional HSLA steels due to introducing a rougher surface inside the punch, as well as a more pronounced shear-affected zone, and particularly higher residual stress accumulation around the punched area. Consequently, heavy-duty trucks still predominantly rely on conventional HSLA steels, and the full potential of AHSSs remains unrealized in these applications. To address this limitation and optimize the integration of AHSS steels in heavy-duty trucks, a comprehensive understanding of punching effect on fatigue behavior is essential. This study aims to particularly focus on quantifying the residual stress resulting from punching in AHSSs with different microstructures and hole geometries.