Abstract: A microstructure evolution model containing both diffusional phase transformation and non-diffusional phase transformation has been established to describe the ultra-high strength hot stamping process. A series of analytical and empirical models also have been introduced and compared to predict the hardness, strength and elongation of the final hot stamping parts, respectively. The above models were integrated in the commercial finite element analysis codes LS-DYNA, through which a U-cap part for hot stamping process was simulated, and the phase fraction and final mechanical properties were obtained. Experimental measured results show that the simulated values are acceptable and the proposed model is reliable.

Key words: ： ultra high strength steel, hot stamping process, phase transformation models, property prediction