Residual stress analysis considering phase transformation and transformation plasticity for heat-treated large shaft

During heat-treatment when forging a large shaft, stress occurs due to temperature change and phase transformation, and special care should be paid to the heat treatment in order to prevent cracking. Therefore it is important to use the finite element method to estimate the stress and deformation resulting from the heat treatment. However, few previous studies treating large forgings in heat treatment simulations include phase transformation. In this report, the residual stress distribution of the test material after water-cooling and air-cooling was measured based on inherent strains, and heat treatment simulations considering the phase transformation and transformation plasticity were performed. It was found that, especially, the transformation plastic strain plays an important role to simulate the residual stress due to the heat treatment of the large shaft.