Effect of Quenching Conditions on Microstructures, Hardness and Magnetic Hysteresis Properties in Die-quenched Steel Plates for Automobile Components

Abstract

　Hardness and magnetic hysteresis loop measurements were performed in a partially die-quenched (DQ) steel plate, and the small steel pieces of spesimen with different cooling rate. The change in microstructre of the specimens were quantitatively characterised by electron backscattering diffraction (EBSD) measurement. A good correlation between hardness and coercivity was confirmed in both series of specimens, which is related to to the formation of martensite. This study demonstrates the plausibility of magnetic nondestructive evaluation of the hardness in DQ products, which improves the quality assurance of automobile components.