52100 Alloy Steel for Knife Blades
AISI 52100 Alloy Steel
52100 is an alloy steel that is commonly used in ball bearings. Incidentally, it is also an excellent knife steel, with possibly the best performance out of many of the tool/carbon steels and reaches hardness of about RC 66, with typical knives usually in the high 50's.
52100 is one of my personal non-stainless favourites, as it does not rust quite as easily as 01, and has a nice fine grain, taking an excellent edge. It can also be differentially hardened, and can really range in quality depending on the heat treatment and forging/grinding process. Many forgers say that 52100 is only really good if it is forged to shape through multiple heating and normalization cycles, while Swamp Rat's SR-101, which is 52100 steel, show that 52100 steel blade can still be very good even if it is made via stock removal.
Swamp Rat SR-101
Jerry Busse called SR-101 steel "52100 with added Kryptonite". It is basically 52100 steel with a proprietary multi-stage tempering protocol with a deep cryogenic treatment. Swamp Rat's preperation of 52100 steel is very good, and personally where my own experience with 52100 lies.
Unlike Busse and INFI, however, Swamp Rat uses steels other than SR-101 in their knives.