carbide tools are highly effective at machining various types of steel such as Carbon Steels (~HB225), Alloy Steels (HB225~325), Pre-hardened Steels (up to HRC45), Hardened Steels (HRC40~48), and Cast Iron. General Usage: Applicable with copper, copper alloys, cast iron, steels, carbon steels, alloy steels, pre-hardened steels, hardened steels, and stainless steel materials. Best use for materials HRC less than 50. We use the highest quality tungsten carbide powders and adjust the ratio of tungsten carbide and cobalt to meet the ideal hardness. It is stable and has excellent wear-resistance of the material. It significantly enhances the tool's lifespan and keeps the end mill sharp. It also helps keep the surface quality of your work-piece at the best level possible.