Analysis of Temperature and Microstructure in the Quenching of Steel Cylinders

A finite-element procedure has been developed for temperature and microstructural analyses of quenching problems involving nonisothermal phase transformations. The finite-element analysis incorporates temperature-dependent material properties, time-temperature-transformation (TTT) diagrams to describe the microstructural evolution in steels, and the latent heat released during a phase change. The procedure is applied to calculate temperature, microstructure, and hardness distributions in 1080 steel cylinders quenched in water and in two polymeric quenchants. The calculated values for the three quantities are found to be in good agreement with corresponding measurements made in quenched 1080 steel cylinders. The effect of latent heat released during a phase change on the temperature and microstructural evolution is studied computationally. It is found that, when the latent heat is not included in the calculations, the resulting volume fractions of pearlite and martensite present in the quenched steel are nearly one order of magnitude different from the corresponding values calculated by including the latent heat in the formulation. Finally, the quenching of a large-diameter 1080 steel cylinder in water is analyzed to show the nonlinear effect of cylinder diameter on the temperatures and microstructures.