Bill Tindall, E.Tn.
The composition is silicon carbide. It will abrade even tungsten carbide. There is no steel it will not abrade, even high vanadium steels. However, it is not recommended for high hardness steel because it is not sufficiently tough when abrading steel of high hardness. It will fracture and act like a finer abrasive than advertised. Aluminum oxide is recommended for this application