Investigation of hot stamping transition zones at tailored carburization at elevated temperatures

Hot stamping is an established process for producing safety-critical components in the automotive industry while maintaining lightweighting concepts. The high strength achievable due to hardening and the geometrical complexity based on hot-forming are two major advantages of the process. A combination of locally ductile and high-strength zones can further improve crashworthiness. One approach to attain this is the tailored carburization process, which involves a local enhancement of the carbon content to strengthen the respective areas. Preliminary investigations have shown a possible reduction in process time by applying a diffusion annealing process route at elevated temperatures of up to 1050 °C. The resulting accelerated carbon diffusion effects similar material properties with tensile strengths of up to 1500 MPa, but only requires one-third of the dwell time. One effect that has not been investigated yet is the impact of the elevated carburizing temperatures on the expansion of the transition zones. Therefore, within this work the carburization parameters are varied and the resulting transition zone is characterized. Besides the laboratory samples, transitions at hot stamped components are also investigated.