Thread: RSO # 1

Originally Posted by JDM61

My experience in getting from my Paragon oven to the patented turkey fryer quench tank full of Parks #50 or MacMaster-Carr medium-fast oil is that same as yours. The only hardening "issues' that I have had are incidents of the old "accidental hamon" with thicker W2 blades, but that is not an issue of hand or quenchant speed.

That sounds like a very good set of tools. The accidental hamon is probably due to the lower harden ability of the W2. The section thickness is the limiting factor. There is enough heat retained above the line to prevent hardening and too little below to prevent it. Playing with the cross section a little you can almost specify where the hamon will occur. Fascinating stuff W2.

Yeah, I love that stuff. Some guys have figured out how to get the accidental hamons on purpose and they look wild even at "user grade" hand rubbed finishes like 600 grit. You typically see that done on the big bowies where you know you have enough mass/cross section up by the spine like you said and I have seen some guys use temperatures as low as like 1425 to do that!!! I haven't really figured that out so I have always used that darn messy clay.

Originally Posted by Mike Blue

That sounds like a very good set of tools. The accidental hamon is probably due to the lower harden ability of the W2. The section thickness is the limiting factor. There is enough heat retained above the line to prevent hardening and too little below to prevent it. Playing with the cross section a little you can almost specify where the hamon will occur. Fascinating stuff W2.

Originally Posted by JDM61

....You typically see that done on the big bowies where you know you have enough mass/cross section up by the spine like you said and I have seen some guys use temperatures as low as like 1425 to do that!!! I haven't really figured that out so I have always used that darn messy clay.

Spend some time watching Japanese smiths work sword blades. They seem to work down in carbon content and temperatures we consider too low and they routinely work in steels that require water to quench in charcoal fires.

I've seen fellows like Daryl Meier weld way below normal welding temperatures. I'm getting to the point where I believe anything can happen despite what the books say.

If any of us metal pounders should be called a "national treasure" Mr. Meier should certainly be on the short list of candidates for that title. I have also heard Kevin Cashen say that he welds his O1/L6 damascus at temperatures lower than "recommended." As for the Japanese smiths, I have heard some cynical types say that they succeed in SPITE of their methods. But you can't argue with the results. LOL

Originally Posted by Mike Blue

Spend some time watching Japanese smiths work sword blades. They seem to work down in carbon content and temperatures we consider too low and they routinely work in steels that require water to quench in charcoal fires.

I've seen fellows like Daryl Meier weld way below normal welding temperatures. I'm getting to the point where I believe anything can happen despite what the books say.

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.

Mike, when I said simple, I mean't in its alloy content. By all accounts, it can indeed be a fickled mistress. I don't see O1 as being any "simpler" than 52100 as far as alloying goes. It may arguably be more complex because of the addition of tungsten, vanadium and more manganese compared to 52100, but it is certainly more forgiving. The info that I cited about carbon steel razor blades came from Mr. Landes who said that it is still the primary razor blade material in much of the developing world. I have not bought any Red Devil single edged blades in years, but I recall that those rusted pretty quickly back in the day.
As for O1 being underrated by the knife community, I do not see that. Sure, there are a lot of guys touting every super PM steel that comes down the pike, but O1 and the other "simple" (oops, did it again) steels still have a lot of fans. Guys like you who are set up to truly treat it to its maximum potential are responsible in part for its continued popularity as the tradtional tool users have gotten away from using it because of it's "complex" (translated, marginally unsafe in a commercial environment according to folks like OSHA) oil quench.

Originally Posted by Mike Blue

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.

Originally Posted by JDM61

... tool users have gotten away from using it because of it's "complex" (translated, marginally unsafe in a commercial environment according to folks like OSHA) oil quench.

My quench tank is at least 15 year old canola oil. MacDonald's et.al. had better look out for OSHA because they've been heat treating fries in dangerous oil then. I do have most of a barrel of Parks oil, but I've never used any of it.

LOL.Mickey D's had better watch out as they already have a bullseye on their back for trying to kill innocent American children with their greasy products. I just go by what the machinists tell us on the forums. A lot of them say that their workplaces have been "forced" (or chosen as the case may be) to switch to air hardening steels like A2.

Originally Posted by Mike Blue

My quench tank is at least 15 year old canola oil. MacDonald's et.al. had better look out for OSHA because they've been heat treating fries in dangerous oil then. I do have most of a barrel of Parks oil, but I've never used any of it.

Originally Posted by Mike Blue

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.

I've only used 0-1 so far, but I'm thinking of trying 1095, after finishing the 0-1 razor I'm working on, just to see how I like it. I've heard a couple of people say that they didn't like honing 0-1. I'm OK with it, but I would like to experience working with 1095 at least once.

Thanks to everyone that has contributed to this forum. I've been able to refine a lot of what I have learned about heat treating. You have reinforced my belief that there is more than one right way to heat treat, and "If it works, it works". Thanks again. Consider all the technical posts "liked", whether I pushed the button or not. Now I'm going to back and screen shot all the technical posts, and put them in a folder for future reference. Peace, love and rock and roll.