The Effect of Grain and Carbine Refinement on the Isothermal Transformation Characteristics of AISI 52100 Steel

摘要

A study of the microstructure and mechanical properties of isothermally-transformed AISI 52100 bearing steel was conducted. Standard spheroidized annealed and thermomechanically grain-refined materials were compared. Heat treatment consisted of austenitization at 850 C, followed by isothermal transformation at 350 C, 275 C or 250 C. Hardness, retained austenite, and optical and transmission electron microscopy data were obtained as a function of isothermal transformation time. Tensile test results also were obtained on selected conditions. It was found that isothermal holding above M sub s resulted in comparable hardness values for both materials. Retained austenite remained low for all cases but did tend to increase as the M sub s was approached. Microstructural analysis revealed that the fine-grain structure of the refined material was retained throughout the transformations while little or no difference in the carbide structure was noted. Tensile results show that the refined and transformed material exhibits greater strength and ductility. (Author)