Abstract:

A precipitation-hardened NAK80 steel with low carbon and medium alloy was treated by shot peening. The distribution of micro hardness and residual stress in the shot peening affected layer and surface roughness produced by shot peening with different arc heights were measured. The change in microstructure induced by shot peening was also analyzed. Improvement on surface integrity of NAK80 steel treated by shot peening was discussed qualitatively. The result showed that the requirement of shot-penning arc height for NAK80 steel was different from the general steels,shot peening with a proper arc height could significantly improve surface quality and fatigue life of NAK80 steel, over peening effect would occur when arc height was too high, and decrease the fatigue life. The optimal surface integrity was obtained by shot penning with the arc height value of 0.40 mm·N, and the thickness of shot-peening affected layer was about  150~200 μm.

Key words: metallic material, shot peening, over peening effect, surface integrity