Microstructure and properties of hot stamping boron steel using heated dies under different holding time

Abstract

A range of materials with different properties is obtained by hot stamping under different holding time and a constant mold temperature of 500 °C. In this process, a blank is austenitized and quenched in one step. The microstructure, hardness, phase volume fraction and mechanical properties are investigated in this paper. With the holding time increasing, the test results show that the vickers hardness and the martensite volume fraction is reduced. The hardness of materials were between 280 and 455 HV0.1. Combined with SEM and colour tint etched methods, the proportion of martensite was quantification, which was between 89% and 2%. When the holding time is 3 s, the tensile strength of material arrived 1500Mpa. The tensile strength of the material tends to be stable at 780Mpa when the holding time reaches 20s. The plastic properties of the materials are better with the holding time increasing.