Thread: Carbon Teeth and Iron Pits

If my understanding is correct, carbon is used to strengthen and harden iron. That is sort of its role in the steel recipe. So, now let's play make believe.

Pretend we have a piece of high carbon steel. Our particular steel has more carbon than the iron can completely absorb. Will this cause the steel to contain little pockets of left over carbon molecules? In the final razor, will these hard pockets of carbon be more resistant to erosion during honing or shaving? If so, could they possibly stick out of the edge like little saw teeth?

Separately, we have a razor made from high carbon steel whose carbon content is less than the saturation point of iron (.77% carbon by weight? I can't remember). Would there be pockets of pure iron that is softer than the surrounding steel? If so, would this iron be eroded more easily during shaving and stropping, creating tiny pockets or pits along the razor's edge?

Let's suppose that both of these conditions (carbon teeth and iron pits) are plausible. I propose that a razor with iron pits would provide a smoother shave than one with carbon teeth, especially a few weeks after the honing. Can this relate to the history of razors? Perhaps historically they used steel with higher or lower carbon content before metallurgy was well understood. Perhaps this difference is what gives some of the legendary razors (Chronik) their ability to take a super silky edge. Perhaps I have too much time to postulate about razors and steel.

If these ideas have any merit, how could I apply this knowledge to the creation and heat treatment of my own razor? As a complete novice, heat treating is a somewhat daunting. If I don't know exactly what I am doing, should I err on the side of over-soaking or under-soaking my steel? And how would this correlate with carbon teeth or iron pits in the final blade?

Thanks for reading, I look forward to hearing your responses.

Originally Posted by MisterLewisR

If my understanding is correct, carbon is used to strengthen and harden iron. That is sort of its role in the steel recipe. So, now let's play make believe.

Pretend we have a piece of high carbon steel. Our particular steel has more carbon than the iron can completely absorb. Will this cause the steel to contain little pockets of left over carbon molecules? In the final razor, will these hard pockets of carbon be more resistant to erosion during honing or shaving? If so, could they possibly stick out of the edge like little saw teeth?

Separately, we have a razor made from high carbon steel whose carbon content is less than the saturation point of iron (.77% carbon by weight? I can't remember). Would there be pockets of pure iron that is softer than the surrounding steel? If so, would this iron be eroded more easily during shaving and stropping, creating tiny pockets or pits along the razor's edge?

Let's suppose that both of these conditions (carbon teeth and iron pits) are plausible. I propose that a razor with iron pits would provide a smoother shave than one with carbon teeth, especially a few weeks after the honing. Can this relate to the history of razors? Perhaps historically they used steel with higher or lower carbon content before metallurgy was well understood. Perhaps this difference is what gives some of the legendary razors (Chronik) their ability to take a super silky edge. Perhaps I have too much time to postulate about razors and steel.

If these ideas have any merit, how could I apply this knowledge to the creation and heat treatment of my own razor? As a complete novice, heat treating is a somewhat daunting. If I don't know exactly what I am doing, should I err on the side of over-soaking or under-soaking my steel? And how would this correlate with carbon teeth or iron pits in the final blade?

Thanks for reading, I look forward to hearing your responses.

Dont know much about steel but I do know Chroniks are not legendary for their performance but for one mans grandiose claims and the sham that was exposed during a test of several of these razors.

Originally Posted by MisterLewisR

If my understanding is correct, carbon is used to strengthen and harden iron. That is sort of its role in the steel recipe. So, now let's play make believe.

Pretend we have a piece of high carbon steel. Our particular steel has more carbon than the iron can completely absorb. Will this cause the steel to contain little pockets of left over carbon molecules? In the final razor, will these hard pockets of carbon be more resistant to erosion during honing or shaving? If so, could they possibly stick out of the edge like little saw teeth?

Separately, we have a razor made from high carbon steel whose carbon content is less than the saturation point of iron (.77% carbon by weight? I can't remember). Would there be pockets of pure iron that is softer than the surrounding steel? If so, would this iron be eroded more easily during shaving and stropping, creating tiny pockets or pits along the razor's edge?

Let's suppose that both of these conditions (carbon teeth and iron pits) are plausible. I propose that a razor with iron pits would provide a smoother shave than one with carbon teeth, especially a few weeks after the honing. Can this relate to the history of razors? Perhaps historically they used steel with higher or lower carbon content before metallurgy was well understood. Perhaps this difference is what gives some of the legendary razors (Chronik) their ability to take a super silky edge. Perhaps I have too much time to postulate about razors and steel.

If these ideas have any merit, how could I apply this knowledge to the creation and heat treatment of my own razor? As a complete novice, heat treating is a somewhat daunting. If I don't know exactly what I am doing, should I err on the side of over-soaking or under-soaking my steel? And how would this correlate with carbon teeth or iron pits in the final blade?

Thanks for reading, I look forward to hearing your responses.

Legendary razors (Chronik included) invokes much poetry and
literary license. If you do not have experience with one
how can you find out if you have conquered the hill.

There has been a lot of work on carbon steel.
There are some standard practices to harden and temper steel
so do some homework. You should not "err" and over/under soak
your steel. You can try various temp time curves but keep as exact
a set of notes as you can. But as a novice you need
to start with the tried and true base line. What used to be
trade secret is common knowledge in the industry and on
the internet.

The key is that carbon and steel do more than mix. There are
chemical reactions that involve phase changes at specific temperatures.
The trick is to capture the right mix of phases and hold them
in a quenched product.

Consider that diamond and graphite are both pure carbon.
Diamond is the equilibrium phase at super high temperatures
and pressures. The only reason we see natural diamond
is that the hot rock escaped from the hot pressure chamber
and erupted to the surface and near surface.

Back to steel this diagram link holds half of the information you need.

Iron-Iron Carbide Phase Diagram Example

The other half is how fast the transitions take place at various
temperatures so you can capture in a room temperature chunk
a precise mix of phases and properties. These are the soak time
and temperature heating and cooling curve bits that are so hard
to get consistently right.

also any other alloys in the steel can make carbides with the "leftover" carbon

about the best simple steel you can get your hands on so far as ease of HT and balance of carbon is 1084

once you get into the W2, O1 or 52100 (higher alloy simpleish steels) HT gets a bit more tricky

Thank you all for the responses.
But I think I asked the question wrong. Let me try again.

A piece of 1095 that is heat treated and quenched to room temperature will have an estimated 13% retained austenite. So our steel is now composed of two different phases of steel: austenite and martensite. Do these phases have different properties of hardness and wear resistance? If so, would it cause the edge of our razor to erode (through shaving, honing, or stropping) enevenly, creating tiny saw teeth? And, would those saw teeth, though microscopic, cause the shave to feel rougher as they become more pronounced from erosion?

I have heard that some of the homemade razors from our members have been in the low 50's on the Rockwell scale and still made very good shavers. So it got me thinking that maybe I should make a razor out of 1080 instead of 1095, because the retained austenite of 1080 quenched to room temperature is approximately 9%, compared to the 13% of 1095. So the 1080 would be a "purer" steel, with smaller "imperfections" of retained austenite. The trade-off would be sacrificing hardness to gain smoothness. I'm not sure the difference would be much, and I know that 1095 can be made into a very nice razor. This is more of a hypothetical curiosity that I couldn't answer by myself, and I simply cannot stand for unanswered questions. I also wonder if the same concept of "imperfections" in the steel affecting the quality of shave would apply to the various carbides that Butch mentioned.

I am entirely open to the idea that the amount of retained austenite is completely irrelevant to the quality of the shave. Maybe austenite and martensite are nearly identical in hardness and wear resistance. Maybe the amount of austenite is just too small in either case to make a difference. Those are the questions I want answered, moreso than instructions on how to heat treat.

Jonathan, I'll be the first to admit that I don't know squat about the chemistry of steel. I barely passed chemistry in college. But I make razors. I use 1095 steel, heat them in a coffee can on a propane burner , and temper them in peanut oil in a $20 deep frier. Then I cryo them with a pound of dry ice in the freezer over night.
Almost all (I can't claim 100% at anything) of my razors are really good shavers. They take a wicked edge, do the hanging hair thing, and maintain that edge as well as any commercial razor that I own. I hesitate to compare my razors with others because we enter a very subjective area. That is why we have boker,W&B,Henkels and other fans. Every brand and type of razor has it's supporters and detracters.
The only was to own the perfect razor is to make 1000 of them and keep the best 1.

So to answer your question, Yes, I think you are over thinking this. Make some razors and have some fun.

Bob

Originally Posted by MisterLewisR

....A piece of 1095 that is heat treated and quenched to room temperature will have an estimated 13% retained austenite. So our steel is now composed of two different phases of steel: austenite and martensite.

If the heat treatment regimen is correct, especially quench temperature and the tempering cycle or cycles, retained austenite in LOW alloy steels like 1095 is inconsequential to performance as an edged tool. Where did you come up with 13% anyway? What is the reference?

I have heard that some of the homemade razors from our members have been in the low 50's on the Rockwell scale and still made very good shavers. So it got me thinking that maybe I should make a razor out of 1080 instead of 1095, because the retained austenite of 1080 quenched to room temperature is approximately 9%, compared to the 13% of 1095. So the 1080 would be a "purer" steel, with smaller "imperfections" of retained austenite. The trade-off would be sacrificing hardness to gain smoothness. I'm not sure the difference would be much, and I know that 1095 can be made into a very nice razor. This is more of a hypothetical curiosity that I couldn't answer by myself, and I simply cannot stand for unanswered questions. I also wonder if the same concept of "imperfections" in the steel affecting the quality of shave would apply to the various carbides that Butch mentioned.

This is true as it happened in my shop. 9% retained austenite in a 10xx steel is more likely to be blamed on a bad heat treatment IMO rather than the alloy. If you drift into the HIGH alloy steels, i.e. those with more than trace quanties of chromium, manganese or, cobalt, tungsten, moly and nickel and the other minor alloying elements that hint toward stain resistance or other tool characteristics, then you have a problem of having to live with retained austenite no matter how you heat treat the blade. You can reduce the RA with subzero treatments but you still will not rid yourself of it all in this class of steels.

1080 is not purer than 1095 because of carbon or any phase change. It is pure based on smelting conditions, not the heat treatment.

Bob pretty much answered in a far more practical way. If it ain't fun, stop doing it.

I haven't had a chance to try out my first home made razor, but I had no problems doing the heat treat, I don't know how much RA there is, or what the hardness is, but a file skated across it before my first temper, and it is looking workable.
Hopefully it will shave as well.
I used O-1 and I know it isn't perfect.
I'm having fun and if they feel right, I'm not worried about the chemistry.

I've honed a lot of razors, and high 50's is ideal, but not necessary. I can hone a razor in the 60's but if I'm not careful, it will feel toothy.
I can also get a razor's edge on something in the high 40's and it will feel very smooth for the first half pass... It's all about balance.
Get your razor into the 50's and up, and learn to hone what you make. You'll have a great shaver.

Thanks for replying, everybody. I know it isn't necessarily a practical subject, just the musings of my curious mind. You should see me when I get into a dictionary frenzy.

...the retained austenite of 1080 quenched to room temperature is approximately 9%, compared to the 13% of 1095.

Those numbers are from Metallurgy of Steel for Bladesmiths & Others who Heat Treat and Forge Steel (2005) by Verhoeven (I haven't finished yet, but I intend to). It's a somewhat inconsistent figure, and the 9% I gave is actually more like 7-11%, and the 13% is more like 9-15%. Unless I am mistaken, these levels are normal for steel that is heat treated to room temp. You would have to be in the ballpark of -200C (not a well established figure, either) before all of the austenite had transformed to martensite. I'm assuming this is the aim of Bob's cold treatment?

If it ain't fun, stop doing it.

You'd have to kill me first. But really, theorizing is part of my fun. And I always appreciate your educated and scientific answers, Mike Blue.

Bob and Mike Ratliff, thanks also for the encouragement and practical advice. I have followed threads by both of you and have been inspired.