Correlation of Almen arc height with residual stresses in shot peening process

The deformations of shot peened Almen strips constrained on Almen blocks with increasing shot peening time, and their subsequent changes after the fixing screws are removed, are experimentally investigated and modelled. Deflection of the constrained Almen strips appears, principally in the transverse direction, as soon as the first passes of peening are applied. The curvatures and the residual stress change with increasing peening time. Removing the screws results in a significant deflection and a great relaxation of residual stress in the longitudinal direction only. A model is proposed to calculate the deformation and the residual stresses in the constrained and free strips. A new problem arises in the evaluation and interpretation of the Almen intensity scale. MST/3113. © 1995 The Institute of Materials.