Numerical and Experimental Investigation on Tube Hot Gas Forming Process for UHSS

Ultra-high strength steels (UHSS) have been regarded as one of the most attractive alternatives for lightweight parts in automotive industry. In this study, the tube hot gas forming process is introduced to implement high temperatures forming for UHSS tubular components. In the proposed process, the tube blank is first heated up to 900 degrees C for several minutes to achieve homogeneous austenitization and then quickly transferred to a press for forming. Nitrogen gas replaces? water in traditional hydro-forming process as media to apply internal pressure in a heated tube. To enhance the energy absorption capability of the components, a one-step quenching and partitioning (Q&P) process is conducted by the die cooling during deforming simultaneously to increase the elongation and ductility of the material. Moreover, a numerical investigation on a tube component fabricated from 22MnB5 steel is performed. The temperature distribution and microstructure evolutions are studied, which demonstrates the forming quantity advantages of tube gas forming process.