Prediction Model for Grain Growth During Austenitization Process of 1800 MPa Ultrahigh Strength Steel

Abstract

This article focuses on the influences of austenitizing temperature and holding time on the grain sizes of 1800 MPa ultrahigh strength steel (UHS-1800). When the austenitizing temperature increases from 900 to 990 °C and the holding time is 5 min, the austenite grain size increases from 12.60 to 20.88 μm. When the austenitizing temperature is 930 °C and the holding time increases from 3 to 9 min, the grain size increases from 13.52 to 17.22 μm. When the austenitizing temperature increases from 900 to 990 °C and the holding time is 5 min, the radiuses of the second-phase particles increase from 15.23 to 25.36 nm. When the austenitizing temperature is 930 °C and the holding time increases from 3 to 9 min, the radius of the second-phase particle increases from 15.72 to 20.50 nm. On this basis, a prediction model for austenite grain growth suitable for UHS-1800 hot stamping process is proposed. The growth model of the austenite grain can accurately predict the grain growth behavior during the hot stamping process, with a maximum error of 5.35% compared to experiments.