Hot forming limit curves for numerical press hardening simulation of AISI 420C

Abstract

A possible alternative to the established press hardening steel 22MnB5 are hot formed martensitic chromium steels. Both strength and ductility of the martensitic chromium steels can reach very high values with appropriate heat treatments. Therefore, car body parts with high crash safety can be produced by hot forming martensitic chromium steels. To identify the formability of a sheet metal, forming limit curves are state of the art. Conventional forming limit curves are recorded at room temperature and do not adequately describe the forming capacity for hot sheet metal forming as it strongly depends on temperature. Therefore, in this paper, an experimental-numerical method for determining quasi-isothermal FLC at high forming temperatures is applied to the martensitic chromium steel AISI 420C (X46Cr13) for forming temperatures between 750-1,050 °C according to its process route. The results show an increase of the formability with rising forming temperature with the highest at 1,050 °C.