I am not sure what Busse's proprietary heat treatment is for INFI. As a matter of fact, that term is almost redundant in that INFI is a custom "blend" made exclusively for Busse. As for "proprietary" heat treatments for 52100, typically they start out by austenizing at around 1475F instead of the 1500F+ you would use if you were making big bearings where large primary carbides for serious abrasions resistance at lower hardness levels were the goal. No telling who figured that out first because Busse does it with their SR101 labeled steel, but Bob Kramer by all accounts, "nailed' the HT for 52100 a number of years ago. But the trick of austenizing below the "saturation point" for increased toughness and the ability to take a super fine and very stable edge is pretty much common knowledge now. That is why it is a go to steel for custom kitchen knives. If you think that kitchen knives are left too hard to be tough, watch the video from the CBS Sunday Morning show from a few years back where Mr, Kramer does the BAs performance test with one of his chef's knives with no damage to the blade. He says that his damascus blades are not that tough and they obvious contain steel that has nickel which is one of the most common alloying elements used to increase toughness.
