Steel abrasives are available in high carbon and low carbon content, although their cleaning performance is comparable, there are some differences in their characteristics, compared to high carbon steel, the low carbon steel abrasives, which are normally supplied at cast shot, offer up to 20% longer durability because of their tendency not to crack and their relative softness, also, they cause less wear on blasting equipment.
However, high carbon steel are still the most commonly used, they are supplied in both shot and grit particle shapes. The particles are heat treated to produce either a martensitic or a bainitic structure for a good combination of hardness and durability. Martensite is a very hard brittle particle produced when hot steel is suddenly chilled by cold water. Abrasives with bainitic structure are similar to low carbon marensite; they are formed by not allowing the steel to cool below 380º until they are solid. Because of their sharp, angular structure, grit particles are particular effective for surface cleaning. Grit comes in various harnesses, and the harder the grit the better its cleaning ability. However, grit eventually becomes rounded in form, and it generally has a shorter life than shot particularly the harder it is.
Steel shot abrasives are pre-dominantly used in impact wheel-type blasting equipment. They clean by hammering action. The profile they produce is much rounder then that achieved by similar shot of iron abrasives.
The important point to remember is to choose an abrasive of the lowest hardness needed to achieve the profile and speed of cleaning required. Manufacturers data sheets should be consulted for information about selecting the appropriate abrasives for a particular purpose. The harder the abrasive, the shorter life because of its tendency to fracture more quickly. It means higher abrasive costs and increase wear on machine parts