The Effect of the Chamber-Filling Ratio in Vibratory Shot Peening on Selected Surface Layer Properties of 30HGSA.

This study investigated the influence of the filling ratio of the working chamber and ball diameter in vibratory shot peening (VSP) on select properties of the surface layer. The tested material was 30HGSA steel, which is effectively used in the aviation industry. The following were analyzed: the surface roughness parameters, the shape of the Abbott-Firestone curve, the bearing area ratio Smr, the microhardness distribution, the microhardness on the surface, and the residual stress σ on the surface. A change in the ratio of peaks and valleys in the maximum height of the profile was observed. After VSP, the valleys were dominant over the peaks. The most favorable values of the analyzed roughness parameters (Sz, Sp, and Sv) were obtained for d = 9.4 mm and k = 33%. The bearing area ratio Smr was approximately 50 times higher than before VSP (the most favorable for d = 9.4 mm and k = 33%). The largest thickness of the strengthened layer of 200 μm and the greatest increase in the microhardness equal to ΔHV 0.05 = 109 were obtained after VSP was conducted using the ball diameter d = 14.3 mm k = 33%. Regardless of the VSP conditions, the absolute value of compressive stresses increased; the highest σ stresses were obtained for d = 3.0 mm and k = 33%, and they were 88% higher than before the treatment. It was concluded that the recommended chamber-filling ratio for beneficial properties is k = 33%.