Physical characteristics of steel shot

　　Chemical Composition:

　　Chemical composition is the most basic index of steel shot and steel sand, which will determine the microstructure of steel shot and steel sand and the effect of heat treatment. Carbon (C) content should be moderate. Silicon (Si) manganese (Mn) can improve the strength of steel shot, hardness, as high as possible (not less than 0.8% is the best). Sulfur (S) phosphorus (P) is a harmful element, easy to brittle steel shot, leading to premature rupture, should be as low as possible (<0.03% is the best).

　　Hardness:

　　If the steel shot or steel sand is too soft, it will slow down the cleaning speed and reduce the work efficiency. During shot peening, the soft steel shot cannot produce suitable residual stress, and the force of low hardness shot cannot be compensated by increasing the impact time. Hardness is too high, will produce unsatisfactory surface topography, increase the probability of projectile breakage, make the consumption too high, and the wear of equipment is large, increase the maintenance cost of equipment, so the appropriate hardness is also very key

　　Microstructure:

　　The microstructure of the steel shot (sand) must be able to resist deformation and reduce energy loss and fatigue life when applied to the working face. Tempered martensite is the most resistant to fatigue. In addition, brittle carbides must be reduced in the microstructure, otherwise it will cause premature fracture of the steel shot (sand) and increase the usage.

　　Physical Defects:

　　The steel shot (sand) must contain as few physical defects as possible that will cause the abrasive to break. Due to the production process used, steel shot (sand) will always have some such physical defects. There must be corresponding process control in production to reduce the proportion of defective particles.

　　Fatigue life:

　　Fatigue life is the ability of steel shot (sand) to resist breakage when applied to the working surface. The abrasive with the longest fatigue life will be the most economical abrasive if it can transfer the appropriate energy to cleaning.