Effects of high-strain-rate deformation on magnetic hysteresis in high-tensile steels

We have studied a relationship between magnetic hysteresis and microstructures on high-tensile AISI 4340 steels after impact loading with a strain rate up to 2100 s−1 We find that coercivity, and minor-loop coefficient which is deduced from a power-law scaling between minor-loop parameters increase with strain rate, show a maximum at around a strain rate of 1400 s−1, followed by a decrease at a higher strain rate, associated with magnetic anisotropy with respect to impact direction. These observations are explained from the viewpoints of heat generation and heterogeneous microstructures characteristic to steels subjected to high strain rate deformation.