Prediction and analysis of residual stress and deflections of Almen strip by burnishing

Burnishing is a surface treatment process widely used to improve fatigue and corrosion resistance of metal components by introducing a compressive residual stress layer. However, the measurement of residual stress by X-ray diffraction is expensive, time consuming, and tedious. Hole drilling method is quick and simple, but it is destructive and provides limited resolution in depth direction. This work presents a quick method to determine the nature and magnitude of residual stress by using Almen strips. Inspired by the application of Almen strips in shot peening, the deflection of the burnished Almen strips under different burnishing conditions were measured. In addition, a finite element simulation model has been developed to predict residual stresses and deflection which were compared with the experimental results. Contact conditions with different combinations of sliding and rolling were investigated in the simulations to understand the contact nature in a burnishing process. It was found that the deflection of Almen strip reflects the magnitude and penetration depth into subsurface of the induced residual stress. The contact condition during burnishing is either pure sliding or a mixed mode of sliding and rolling, but not pure rolling.