Computational modeling of quenching and carburizing heat treatment processes is essential for designing process parameters to achieve a desired microstructure, hardness, and residual stress and deformation distribution in engineering components. Efficient finite element procedures have been developed to simulate the quenching and carburizing of steels involving non-isothermal phase transformations. The finite element procedure first simulates the diffusion of carbon atoms into a carbon steel by solving the diffusion equation. It then calculates the temperatures distributions and microstructure evolution in the piece when it is quenched from high temperatures. The final stage of the simulation is to determine the deformations and stresses developed during the process. The finite element procedures developed incorporate temperature dependent material properties, a mixed hardening rule to model the mechanical behavior of the material, time-temperature-transformation (TTT) diagram data and evolution equations to describe the phase transformations, and diffusion equations to model the diffusion of carbon into the workpiece. Several example problems simulating the heat treatment of steel cylinders and aluminum bars are used to validate the model and applications are made to problems of interest, such as the effect of cylinder size on quenching.
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