Straightening of distorted components ater heat treatment is oten a necessary operation. he straightening operation leads to local plastic deformation, which is afecting the residual stress state, the hardness, and ultimately the fatigue strength of the component. he present study evaluates the inluence of a straightening operation on fatigue strength and on the residual stress state of induction hardened shats of steel EN 42CrMo4. A simpliied FEM model was formulated. he model showed that the residual stress state was asymmetric along the circumference of a straightened shat. Fatigue testing was performed in a three point bending and showed that the fatigue strength was reduced by up to some 20 % by heavy straightening. A fracture mechanics model for fatigue crack growth and arrest was developed. he model could be used to predict the fatigue strength of a straightened shat provided that the residual stress state was known.