Influencing factors of sand quality

　　answer

　　1. Hardness (GP-HRC42-50, GL-HRC56-60, GH-HRC63-66)

　　The hardness of the steel grit should be moderate. If the steel grit is too soft, it will slow down the cleaning speed and reduce the work efficiency. During sand blasting, too soft steel grit cannot produce suitable residual stress, and the force of low hardness sand cannot be compensated by increasing the impact time. If the hardness is too high, it will produce unsatisfactory surface morphology, increase the chance of breaking the sand, make the consumption too high, and cause greater wear and tear on the equipment, increasing the maintenance cost of the equipment, so the appropriate hardness is very important.

　　2. Chemical composition

　　The chemical composition will affect the hardness of the steel shot, etc. Carbon (C) content should be moderate. Silicon (Si) and manganese (Mn) can increase the strength and hardness of steel grit, so they should be as high as possible. Sulfur (S) and phosphorus (P) are harmful elements, which can easily cause brittleness of steel grit and lead to premature fracture, and should be kept as low as possible.

　　3. Microstructure

　　The microstructure of steel grit can resist deformation, and when it acts on the working surface, it can reduce energy loss and increase fatigue life. Tempered martensite is more resistant to fatigue. In addition, it is necessary to reduce brittle carbides in the microstructure, otherwise it will cause premature rupture of steel grit and increase consumption.

　　4. Fatigue life

　　Fatigue life is the ability of steel grit to resist breakage when it acts on a working surface, and an abrasive with a longer fatigue life will be an economical abrasive if it can transfer the proper amount of energy to cleaning.

　　5. Physical defects

　　Due to the production process used, there will always be certain physical defects in steel grit. There must be corresponding procedures to control in production to reduce the proportion of defective particles.