Investigation of thermal behavior and mechanical properties in hot stamping of aluminized 30MnB5 with an integrated process window design

Hot stamping technology has emerged as an essential process for manufacturing lightweight and ultra-high-strength automotive components, particularly with the increasing adoption of electric vehicles. Among advanced materials, aluminized 30MnB5 steel, with tensile strengths exceeding 1.8 GPa, provides a compelling combination of crash safety enhancement and weight reduction. However, its mechanical properties are highly sensitive to processing conditions, necessitating systematic optimization. This study introduces an integrated Process Window (PW) that incorporates heating, transfer, and cooling stages to ensure efficient and reliable manufacturing. Experimental results identified 870 °C as the optimal heating temperature for 30MnB5 steel. At this temperature, the steel achieved a tensile strength exceeding 1.8 GPa, a yield strength of approximately 1.2 GPa, and an elongation of 6.8 %. Additionally, the interdiffusion layer thickness in the Al-Si coating was reduced to approximately 3.8 μm, the prior austenite grain size was refined to 9.6 μm, and hydrogen absorption was suppressed by about 45 % compared to higher heating temperatures. These conditions collectively enhance weldability and ensure consistent mechanical performance. The sheet thickness was shown to significantly influence thermal behavior, impacting heating times, ambient exposure, and die-cooling. The derived temperature-time relationship functions enable tailored process adjustments to achieve consistent strength and formability across varying sheet thicknesses. Unlike conventional PW, which primarily addresses heating conditions, the proposed integrated PW encompasses the entire hot stamping process. It aims to reduce inefficiencies and improve process stability. By quantitatively linking process parameters to microstructural evolution and mechanical properties, this study establishes a robust framework for the production of lightweight, ultra-high-strength automotive components. The findings also contribute to advancing sustainable manufacturing practices by optimizing energy consumption and process efficiency.