52100 consists of:
From Spyderco's website:
52100 is a high carbon steel used primarily for ball bearings. It has a good amount of carbon (0.98 - 1.10) and very few other alloys. Ball bearing steels usually have to withstand a great deal of force in a very small area. Traditionally, ball bearing steels make good edge steels because an edge also has to withstand much force in a small area. 52100 serves that function well. Oil quenched and drawn to Rc 62, it is a difficult steel to heat treat. A very fine molecular structure permits very sharp edges, even at thin angles. Toughness is good, corrosion resistance isn't. It is not a stainless steel and will have to be cared for.