In-Situ Determination of Carbide Dissolution in 52100 Bearing Steel

Abstract Carbide dissolution and phase transformation can be tracked insitu with dilatometry, via subtle length changes throughout an entire heat treatment cycle. Through combining theoretical calculations of phase fractions with temperature and experimental dilatometry data, kinetic data can be extracted to determine the time required to dissolve carbides at various heating rates and austenitization temperatures. This study presents a dilatometry test method to produce a diagram that predicts carbide dissolution time for steels, which would be particularly useful for heat treaters when designing optimized austenitization schedules. In particular, the carbide dissolution in 52100 bearing steel is investigated at various isothermal temperatures to plot the fraction of carbides as a function of time. The recorded length changes from dilatometry are converted into the fraction of carbides, as determined through various models and thermodynamic data.