tool steel
To cut, shape, or stamp other metals, you need a steel that is harder than what it works on and keeps that hardness even when the cutting edge gets hot. Tool steels are that class: high-carbon, heavily alloyed steels made to be hardened to extreme hardness and to resist wear, deformation, and softening. They are the metal that makes dies, punches, drills, milling cutters, and injection-mold cavities.
What sets tool steels apart is a big dose of carbide-forming alloys (tungsten, molybdenum, vanadium, chromium) on top of high carbon. These form very hard alloy carbide particles that resist abrasion, and, crucially, they resist tempering: an ordinary hardened carbon steel loses its hardness if it warms past about 200 degrees C, but a high-speed tool steel keeps cutting when the edge glows because its carbides only soften much higher (secondary hardening near 550 degrees C). Grades are grouped by use and quench medium: W (water-hardening), O (oil-hardening), A and D (air-hardening, high chromium), H (hot-work), and the famous M and T (high-speed steels for cutting tools).
Tool steels are expensive and, once hardened, hard to machine, so they are shaped soft (annealed), then heat-treated to final hardness. The trade-off is the classic one: the same high carbon and carbides that make them hard and wear-resistant also make them brittle, so a tool that is run too hard can chip or crack rather than dull gracefully. Choosing a tool steel is a balance of hardness, toughness, wear resistance, and how much the part may distort during hardening.
A high-speed steel drill bit (grade M2) can be hardened to about 64 on the Rockwell C scale and still cut steel with the tip red-hot; a water-hardening W1 chisel is just as hard but softens if it gets warm, so it is for cold work only.
High-speed refers to keeping hardness while cutting fast and hot, not to the tool spinning quickly.
Hard is not the same as tough: a tool run at maximum hardness resists wear best but is most likely to chip. Many tools are deliberately tempered slightly softer to trade a little hardness for the toughness that stops catastrophic cracking.