Effect of Austenitization Temperature on the Precipitation of Carbides in Quenched Low Carbon Boron Steel

Abstract

The objective of this study was to study the effect of austenitization temperature on the formation of carbide/borocarbide, the microstructure and the mechanical properties of low carbon boron steel after quenching and its effects on the tensile properties of the steel. Three austenitization temperatures were used: 870, 1050, and 1200 °C. The steel microstructures were analyzed by light, scanning and transmission electron microscopy techniques. Microstructural analyses showed that the highest percentage of martensite was obtained at the austenitizing temperature of 1050 °C. The lower content of martensite at the austenitization temperature of 870 °C was caused by the low percentage of boron in solution or by the largest non-equilibrium segregation of boron to the grain boundaries at 1200 °C. A lower content of borocarbide (Fe23(C,B)6) was identified for the austenitization of 1050 °C, which caused an enhanced effect of boron on the reducing of the formation of carbide/borocarbide on the grain boundaries. © 2013 Springer Science+Business Media New York and ASM International.