The heat treat on INFI is not a secret or a mystery. Jerry has posted about the process several times in answering questions on the forum. And, yes, it's about a good heat treat as you can get, and as you know, heat treat makes a bigger difference than type of steel. Not just a good heat treat, but how the heat treat is matched to the steel. Busse just does a great job with it. The specs of INFI steel are also not a secret, and I see someone has already posted them in this thread. INFI is cool because although it is not a stainless steel it does not rust easily, and because it has a crazy ability to be both hard (58-60 Rc) and soft (edge tends to roll not chip, when abused, making sharpening easier). They heat treat INFI to a whopping 950 degrees, and employ a 3-day multi-cycle dry cryogenic treatment. The cryogenics improves the steel, and Busse does it the right way. Below is Jerry expounding on their heat treat method:
"Busse has been doing cryo since the early 1980's. Back then it was a very primitive process involving an old cooler, dry ice and about a gallon of acetone. Process: pack the blades in dry ice, pour the acetone over the ice to speed the evaporation process, and hit somewhere around the -190 degree mark. Do a normalizing temper (approx. 350 - 450) and voila! Prehistoric Cryo!
In the late eighties we began the employment of a deep cryo treatment (-300/320 degrees) which was done in a dry, controlled, atmosphere. This process allows us to take our blades down to temp. over the course of 10 hours hold them at temp. (-300 degrees) for approx 50 hours, and then bring them back up to room temp. over the course of the next 10 hours at which point they receive 3 more, individualized, oven tempers. This is the same process that we employ to this day.
Some makers are out there just plunging their blades into liquid nitrogen which can shock the steel so dramatically that microscopic cracks and fissures can form that could cause massive blade failure in the field under heavy and/or light use. That is why it is crucial that the blades be cooled slowly and brought back to room temperature slowly and then normalized with a few oven tempers for stress relief.
Of course there are also some makers that I know of who claim to employ cryogenics because they stick their knives in the freezer over night. Scary! Alway ask the maker to give as much detail of his cryo process as possible.
Knowledge is power! Arm yourself!
Yours in Nuclear Cryogenics,
Jerry Busse"