Abstract
Hot stamping technology has been widely used in automotive manufacturing to produce ultra-high-strength components that fulfill crashworthiness and lightweight requirements. However, hot-stamped boron martensitic steels are susceptible to hydrogen delayed cracking (HDC), primarily due to diffusible hydrogen introduced during the furnace heating process in the presence of aluminum-silicon (Al-Si) coatings. This study investigates the effectiveness of functional surface coatings to reduce the hydrogen uptake during hot stamping process. An ester-based lubricant was evaluated in comparison with conventional lubricants and non-lubricated conditions. Hydrogen embrittlement test was performed using 4-point bending test and diffusible hydrogen contents analysis was performed by thermal desorption spectroscopy (TDS). Surface analysis was carried out using FT-IR and FE-SEM. The results demonstrated that ester-functionalized lubricants formed hydrogen bonds at elevated temperatures, significantly reducing hydrogen uptake and HDC susceptibility. The findings highlight the importance of surface chemistry and coating design for ensuring delayed fracture resistance in ultra-high-strength hot-stamped components.