Martensitic Transformation and Residual Stress Generation During Thermomechanical Treatment

The influence of thermomechanical deformation on the residual stresses caused by quenching in bar shaped specimens of heat treatable steel SAE 4140 has been investigated using a mechanical method for determining the distribution of residual stresses of the first kind. The results obtained show that the residual stress distribution after quenching is affected by the strengthening and softening of the austenite and the modified transformation behavior in martensite stage. An attempt is made to discuss qualitatively the influence of these changes on the generation of residual stresses as compared to results obtained after conventional hardening.