Influence of some parameters on the residual stresses from quenching

摘要

The paper concentrates on some important and little discussed effects on the development of residual stresses from quenching: the influence of the martensitic temperature interval and the influence of the shift of the martensite start temperature caused by thermal stresses. The influence of the location of the maximum quenching rate on the residual stress pattern is also discussed. A numerical model of the coupled elasto-plastic problem has been developed, which incorporates the influence of the thermal stresses on the martensite start temperature. It is demonstrated that the length of the martensitic temperature interval may have a significant effect on the residual stress pattern. While large martensitic intervals promote compressive residual stresses at the surface, small martensitic intervals give rise to tensile residual stresses even for small thermal gradients at martensitic temperatures. The shift of the martensite start temperature due to thermal stresses should always be incorporated in calculations because of significant effects on the residual stress pattern. It is also established that during quenching, the thermal stresses always raise the martensite start temperature at the specimen surface, thus promoting non-uniform phase transformation over the cross section of the specimens.