Simulation of quenching and induction heat treatment processes with experimental verification

Computational modeling of quenching and induction heat-treatment processes is essential for designing process parameters, a priori, to achieve a desired microstructure, hardness and residual stress distribution in engineering components. Efficient finite element procedures have been developed to simulate the quenching and induction heat-treatment of steels involving non-isothermal phase changes. The finite element procedure first simulates the magnetic field developed when currents flow through an induction coil by solving Maxwell\u27s electromagnetic field equations; at the following step it calculates the temperature distributions in the workpiece due to eddy currents induced by the magnetic field and during quenching of the heated workpiece. The final stage of the simulation involves the determination of the distributions of residual stress, hardness and microstructure in the workpiece developed through the whole process; this involves modeling of the phase transformations occurring in steels. The finite element procedures developed incorporate temperature dependent material properties, changes in magnetic permeability of the workpiece at the Curie temperature, a mixed hardening rule to describe the mechanical behavior of the material, and time-temperature-transformation (TTT) diagram data and evolution equations for describing the phase changes. Quenching experiments have been carried out with 1080 carbon steel cylinders and three commonly used quenchants viz. water and two polymeric-based synthetic fluids. The temperature distribution during quenching and the residual stress and hardness distributions in the quenched steel cylinders were measured. The measurements showed that there was good agreement between the measured and the predicted temperature, residual stress, and hardness distributions. Besides this validation, the finite element procedures for induction heat-treatment have been validated through comparison with analytical solutions. Finally the simulation procedures have been extended to analyze moving induction heat treatment and moving surface heat source/convection boundary problems. The analysis of these problems required the development of efficient remesh procedures