Thread: RSO # 1

Martensite, the desirable hardened form of steel, can be a mixture of ferrite and cementite. The amount of cementite depends on how much excess carbon is available and how rapid the cooling to martensitic forms. Retained austenite is always a risk above eutectic carbon contents, even under optimum heat treatment regimens and conditions.

I don't know that cementite adds any desirable properties. When above the austentizing temperature all the cementite dissolves. Controlling it's formation is a function of time and temperature, as we have been discussing.

I disagree that 52100 is a component of modern razors to the percentage you've stated. If this is about vintage razors, for the vast majority, they are all high carbon steels. 1.2% carbon and nearly nothing else besides iron. 52100 did not exist then. For modern razors, I agree that stain resistant steels dominate the very thin strip style razors and are likely a relative mixture very similar to AEB-L or the 12C27 variety or nearly so depending on whether they are made in Europe or Japan. The metal engineers have invested a lot more time working stain resistant materials. 52100 was a bearing steel not a cutting tool steel before it found it's way into the knife world. I would like to see more source material about the amount of 52100 in razor blades. I don't believe it.

Frankly JDM, all the smiths I know would not refer to 52100 as a simple steel. It is a fickle mistress in most hands and requires the complete attention of the smith working it. It has a narrow range of temperatures for forging, has a relatively low coarsening temperature and takes most of 24 hours to thermal cycle back to fine grain if the smith overshoots the temperatures inadvertently. I do not recommend it as a beginner's material.

There is no question it is a good steel for cutting edges. For 15 years or so it was the best testing hardened steel by the CATRAL group in the UK. The only steel that could outperform it was wootz in the unhardened state. John Verhoeven and Al Pendray were the primary researchers in those two steels at the time. It was very popular for a while until people tried to work it and found it difficult. The stories it has earned that hype this steel, are not complete stories by a wide margin. Perhaps more marketing has been applied to it than most know about. I should call my friends (most of them already mentioned) and ask them if they think 52100 is simple. Nah, I don't have to. That question was answered to my satisfaction long ago.

There all sorts of new alloys, all build on the foundation laid by 52100 for performance characteristics, that will outperform 52100 routinely, namely SxxV or any variation of. Most of that data has been readily developed at companies like Spyderco. They do their own testing on the new alloys for cutting performance. I don't necessarily want to leave out any others but only speak of systems I know well.

Given the original post: my recommendation is to begin with O-1 and stick with it. Learn it, until you know it inside and out. It's general composition is so near the old mixture called silver steel (indeed, O1 drill rod is still called silver steel in Europe) that it overlaps some traditional ground. It does not require special tools or complicated processes. It's cheap. It's hard to see any value in racing off after all the other materials when something old fashioned and highly under-rated by the knife community can perform in a razor in all the desirable characteristics from shaving to honing.