Surface Temperature and Heat Transfer Coefficient Determination during Quenching for Martensite Fraction Prediction using a Parabolic Heat Transfer Model

A simplified method is used in this paper to predict the transient temperature distributions in a cylinder during quenching. The model is based on the assumption that the radial temperature distributions follow a parabolic-type behavior. In order to validate the model, AISI 304 stainless steel round samples (ø8 mm) were instrumented with thermocouples for temperature data logging during quenching. The samples were heated to 900°C followed by quenching in water-base salt solutions. Based on the results of the model, in conjunction with the transformation diagrams of the alloy, it was possible to predict the martensite fraction formation in the radial direction. A practical example of the use of the predicted transient temperature distributions and martensite fraction at various radial depths is presented in this paper for a partially decarburized AISI 5160 steel.