Analysis of Surface and Subsurface Layers after Shot Peening of Various Aluminium Alloys

In the paper two aluminium alloys, i.e. 6082 and 7075, which were cold hardened by shot peening under different conditions, are treated. Surface hardening was carried out with S170 steel shot of the same diameter, particle hardness being 56 HRC. Other conditions were the operating pressure, mass flow, which provide different Almen intensities. The hardened layer was described by surface integrity. Macroscopic and microscopic analyses consisted in analyses of hardened profiles of hardness, and residual stresses in the thin surface layer. Research results indicated that there were significant differences among the characteristics chosen to describe surface integrity and that they had an important influence on the final condition of the surface layer. With too severe settings of the peening parameters, the surface properties got worse because of damages, which resulted in crack initiation and growth of the existing cracks.