I don't have much of a physics background, so my assumptions might be somewhat incorrect. But I've recently seen how sanding tools can be used on materials that are powerful, such as stainless steel. From a Google search, it seems standard sanding tools are made out of materials like aluminum oxide, which (aluminum) I've generally understood to be a relatively weaker metal. I was hoping to get some clarification regarding the basic process of how the sandpaper does not deform itself, instead doing more damage to the material it's in contact with.
Pure aluminum metal is relatively soft, but aluminum oxide is harder than any steel. The particles of the oxide that are glued to the paper have extremely sharp edges on them, and when you rub the sandpaper on a piece of steel, those sharp edges scrape off tiny pieces of steel.