Steel strengthening shot will cause plastic deformation of the sprayed surface of the parts, which will change the surface roughness of the parts. Surface roughness is a kind of microscopic geometric shape error, also known as microscopic irregularity. Surface roughness, like surface waviness and shape error, belongs to geometric shape error of parts. Surface roughness has an important influence on the performance of machine parts.
 

The effect of steel shot peening on the parts surface and its roughness is usually in the range of Ra0.6 ~ 20mm. When the process parameters are not changed, the higher the raw surface roughness of the material, the greater the Ra value after shot peening. Production practice has proved that, the surface roughness before spraying is below 6.3mm, shot peening can improve or maintain the original surface roughness, if the original surface roughness is above 6.3mm, the surface roughness after shot peening will be reduced.