52100 is an alloy steel. It like 4140Mod offers little wear resistance although it is exceptionally tough.
Typical applications include: Bearings * Drills (Non-Ferrous) * Forming Tools * Gauges * Mandrels * Taps * Threading Dies * Punches * Dies * Molds
Typical chemistry: Carbon 1.00% * Manganese .35% * Chromium 1.50% * Silicon .25%