Tailored properties of a novelly-designed press-hardened 22MnMoB steel

Abstract

A novel 22MnMoB hot stamping steel was designed. The continuous cooling transformation (CCT) measurement of the 22MnMoB steel showed that the ferrite-bainite microstructure could be obtained at cooling rates lower than 25 °C/s, and the complete martensite structure required the cooling rate higher than 30 °C/s. The experiments with non-uniform die temperatures were carried out to obtain tailored properties. The results showed that strength of 1411 MPa and elongation of 6% could be obtained in the hard zone, and strength of 916 MPa and elongation of 9% could be obtained in the soft zone, which can be realized by controlling the die temperature at 400 °C. The transition zone was found smooth and could be beneficial to reduce the stress concentration and therefore improve the performance of components.