Microstructure, Hardness, and Tensile Properties of Vacuum Carburizing Gear Steel

We investigated the effects of austenitizing temperature on microstructure, hardness, and tensile properties case-carburized steel after vacuum carburization at 930 °C then re-austenitization 820–900 followed by oil quenching tempering. The results show that fractures occurred early with increase in temperature, although all carburized specimens showed a similar case hardness 800 HV0.2 depth 1.2 mm. highest fracture stress 1919 MPa was obtained for experimental when 840 due to its fine microstructure relatively high percentage retained austenite transformed into martensite during tests. also found stress–strain behavior could be described area-weighted curves core combination. strain hardening exponent about 0.4 did not vary temperature. concluded optimum around steel.