Development of steel castings to be heat treated by carbo-austempering

Abstract

Carbo-austempering is a heat treatment in which the surface of a steel is carburized and then quenched and held at a temperature above the martensite start temperature (Ms) to form a bainitic structure in the carburized layer. In this research, two low-carbon steels susceptible to carburizing were designed, named A1 and A2. Optimal conditions for homogenization, austenization, and austempering were established. The steels were characterized using optical emission spectrometry, optical microscopy, scanning electron microscopy, X-ray diffraction, and Vickers microhardness test. The results demonstrate the influence of chemical composition on controlling microstructures after isothermal transformation, ensuring an optimal balance between heat treatment and mechanical properties.