[Kevin R. Cashen]

Hey Michael, I hear what you are saying, I have joked before that I am scared of working with 52100 because it appears to have some sort of toxic elements in it that burn out when you heat it and gets into smith’s brains. It seems that every time I hear some convoluted fantastic ritual involved in heat treating a steel, I will stop the person and say “don’t’ tell me …52100?”, and the answer will be “yes, how did you know?”

Normally the reason is because people are coming at 52100 like it is a simple carbon steel that can be done with just any equipment and any temperatures. But 52100 is not a beginner’s steel that will tolerate much deviation in what it needs to respond to heat treatment. The more folks mess around with deviating from what it needs, the more hoops they start having to jump through to bring it back on track, and new whacky 52100 heat treatment is born.

Yes 1475°F is the trick, folks will heat threat this steel with a 6,000°F torch flame or an unmeasured forge fire and then the fun begins. Above 1475°F you will lose hardness to retained austenite by putting too much of that 1% carbon into solution, industry says 1550°F.
but this steel was designed and intended for bearings, not knife blades, so industry gives you the correct methods to make a bearing not a knife, the bearing process deals with retained austenite in different ways.

If you have forged and normalized the steel, 1475°F and a quench into a medium speed oil, (1.4% Chrome means this is not 10XX series or W2 that needs a fast quench) should get you to 65HRC with no problem, I have gotten 67.5-68HRC at times using this method. If you find your HRC locked down around 63, you may need to free up some heavily spheroidized carbon by backing off your annealing cycles a bit and going for hotter normalizing before some follow up refinement cycles.