Microstructural effects on the mechanical properties of carburized low-alloy steels

Abstract

This study examined the effects of composition and initial microstructure on the physical, metallurgical, and mechanical properties of carburized SAE 8620 and PS-18 steels. Testing was performed on 8620 and PS-18 steels in the as-received and normalized conditions. Hardenability testing was conducted prior to additional heat treatments. Size and shape distortion, residual stress, retained austenite, and effective case depth measurements were obtained for specimens subjected to a carburizing heat treatment. Specimens subjected to a core thermal cycle heat treatment were tested to determine the tensile and Charpy impact properties of the core material of carburized components. Despite differences between the as-received and normalized materials prior to carburizing, testing revealed that normalizing did not have a significant effect on the properties of the carburized or core thermal cycle heat treated materials. PS-18 had a higher hardenability, effective case depth, and ultimate tensile strength and a lowerCharpy impact toughness than 8620