Analysis of high strength characteristics of aluminized quenchable boron steel (22MnB5) using groove pattern on the hot stamping die surface

The increasing demand for lightweight vehicles, while ensuring collision safety, has led to the growing utilization of high-strength steel sheets. Accordingly, the hot stamping process, which involves heating the material and shaping it in a die while simultaneously cooling it, has gained significant attention. However, the inclusion of heating and cooling processes in the hot stamping engineering presents competitive disadvantages in terms of cost. As a result, numerous studies are being carried out to overcome these challenges and improve productivity. In particular, the sidewall areas of the vehicle body parts, which thin out during the stamping process, can experience a reduced cooling rate compared to other areas. To counteract the potential risk of a relative decrease in strength in these areas, extending the pressurization time of the press becomes necessary. In this study, by introducing groove patterns on the surface of the die used in the hot stamping forming and cooling processes, it was investigated how to enhance the cooling rate of the sidewall of the vehicle part without necessitating additional press dwell time. Using this approach, it was possible to achieve a strength of over 1.6 GPa and a dimensional accuracy of -0.06 mm within a short in-die quenching time of 6 s.