Thread: Vintage Carbon steel properties????

Originally Posted by Caledonian

...The ancient Japanese, and those who still use the same tamahagane steelmaking process, most ingeniously solve the problems of a primary steelmaking process almost identical to black Africa's, which was incapable of producing a good sword steel without much further work. The swordsmith laminated excessively soft and excessively brittle steels together to make a bar of layers so thin as to function like a homogeneous steel. ...

As much as we know now about pattern welding and the activity of carbon migration in steel at temperature, in this modern age, this idea is a false one, despite being the basis for much of the myth of damascus steels. By the time the smith gets done with all those laminations (it takes only four welds) the carbon has averaged out, leaving them with an average steel.

... Cold produced by climatic conditions is nowhere near as great as that used in cryogenic treatment today, and I think the analogy is a false one. It is known, though, that steels become more brittle to shock loads in very cold weather. Alexandre Dumas has the aging d'Artagnan break the sword he has carried all his life, by dropping it on the flagstones on a cold morning in the Louvre.

It depends on where you live. The northern US where I'm at can produce -100 F temperatures for a few weeks. Parts of northern Europe and Russia produce similar or greater conditions. That would require a smith that was patient, if the cold was going to produce a desired change in a steel bar. While such a temperature is not the same degree a modern metallurgist might require for a high alloy steel's retained austenite into martensite, it is enough of a temperature to produce some change. There are some modern makers who have used baths of frozen carbon dioxide and alcohol to achieve -120 F in the shop where they could not afford the liquid nitrogen equipment. Those temperatures are not so far off what nature can produce in some places. This temperature would not be metalurgically ideal, but perhaps sufficient to the individual maker's subjective purposes.

I think that because the subject has been discussed in historical literature to be sufficient that the effect had been reported by sword or blade owners. The idea that each legend contains a kernel of truth is difficult to argue against, since none of us can go back in time to disprove it. A good friend of mine, Craig Johnson of Arms and Armor, has summarized the literature that indicates the Persians sought out Frankish steels in preference to steels produced in warmer climates specifically for their winter war benefits.

I have been an ardent debater of the cryo treatment model for carbon steel alloys as not necessary, if the heat treatment was done properly in the first place. In an historical case, if a carbon steel blade was poorly heat treated and contained retained austenite (which the smith would have no concept of), the blade might improve with the application of cold, converting some of the RA to martensite. If left untempered, that martensite would be brittle compared to tempered martensite. It is possible to consider conditions that could contribute to legends like this. There was little "science" available to them, but they were keen observers of what worked. The things that worked would be rapidly adopted. I suspect that a smith, whose techniques were poor, would suffer some Darwinian consequence of his methods.

Originally Posted by Mike Blue

As much as we know now about pattern welding and the activity of carbon migration in steel at temperature, in this modern age, this idea is a false one, despite being the basis for much of the myth of damascus steels. By the time the smith gets done with all those laminations (it takes only four welds) the carbon has averaged out, leaving them with an average steel.




It depends on where you live. The northern US where I'm at can produce -100 F temperatures for a few weeks. Parts of northern Europe and Russia produce similar or greater conditions. That would require a smith that was patient, if the cold was going to produce a desired change in a steel bar. While such a temperature is not the same degree a modern metallurgist might require for a high alloy steel's retained austenite into martensite, it is enough of a temperature to produce some change. There are some modern makers who have used baths of frozen carbon dioxide and alcohol to achieve -120 F in the shop where they could not afford the liquid nitrogen equipment. Those temperatures are not so far off what nature can produce in some places. This temperature would not be metalurgically ideal, but perhaps sufficient to the individual maker's subjective purposes.

I think that because the subject has been discussed in historical literature to be sufficient that the effect had been reported by sword or blade owners. The idea that each legend contains a kernel of truth is diffic ult to argue against, since none of us can go back in time to disprove it. A good friend of mine, Craig Johnson of Arms and Armor, has summarized the literature that indicates the Persians sought out Frankish steels in preference to steels produced in warmer climates specifically for their winter war benefits.

I have been an ardent debater of the cryo treatment model for carbon steel alloys as not necessary, if the heat treatment was done properly in the first place. In an historical case, if a carbon steel blade was poorly heat treated and contained retained austenite (which the smith would have no concept of), the blade might improve with the application of cold, converting some of the RA to martensite. If left untempered, that martensite would be brittle compared to tempered martensite. It is possible to consider conditions that could contribute to legends like this. There was little "science" available to them, but they were keen observers of what worked. The things that worked would be rapidly adopted. I suspect that a smith, whose techniques were poor, would suffer some Darwinian consequence of his methods.

I don't believe there is any contradiction between your first paragraph and my saying that finely laminated steels function like a homogeneous one. Wikipedia says that the record low temperatures for the United States is -80 °F, in Prospect Creek Alaska in 1971. Nowhere outside of Antarctica has been recorded as sinking below -80 °F. You may have meant 100 degrees below freezing, which is -68°F, but even that is rare, and I doubt if any straight razors have been left outdoors in it.

The ancient and modern worlds are full of over-optimistic beliefs about technology. The Japanese believed certain swords, and the product of some makers, could have a malignant and treacherous disposition, and there are records of Viking swords which would sing to themselves when action was imminent. They are not necessarily true. I think -120 °F, more even than true cryogenic temperatures, come under the heading of those which you believe, correctly I think, not to do a bit of good. They have their place, for relieving stresses in objects of complex shape. Rifle barrels, for example, may be less likely to bend as they heat up, and send their bullets off in the wrong direction. But it is rare for the problems of any razor to derive from internal stresses.

Steel becoming fairly (not extremely) brittle at temperatures within the normal human idea of uncomfortably cold weather, but well over -68°F, is relatively well-known. But I think the effect would last only as long as that temperature did.

Originally Posted by Caledonian

I don't believe there is any contradiction between your first paragraph and my saying that finely laminated steels function like a homogeneous one.

At it's heart, the purpose of the process of folding and welding, no matter the cultural traditions, is to render a raw steel bloom into a clean workable billet of material without sand, charcoal, slags and spaces. Much like kneading bread to mix the materials thoroughly. I have no argument with that concept.

..You may have meant 100 degrees below freezing, which is -68°F, but even that is rare, and I doubt if any straight razors have been left outdoors in it.

I don't know of anyone who has set out to formally test the effects of cold on razors either. Or swords. There may be, unknown as yet, metallurgical labs that have done some kind of work in this area. See below.

The ancient and modern worlds are full of over-optimistic beliefs about technology. ... I think -120 °F, more even than true cryogenic temperatures, come under the heading of those which you believe, correctly I think, not to do a bit of good. They have their place, for relieving stresses in objects of complex shape. Rifle barrels, for example, may be less likely to bend as they heat up, and send their bullets off in the wrong direction. ...

Don't leave out the concept of windchill, or for the sandbox and elsewhere the heat index. Relative temperature effects are not simply the reading from an isolated thermometer.

My use of the phrase ardent debater is perhaps misleading, as I do not recommend cold treatments except under correct conditions. My understanding of cryo treatments is that it is beneficial for high alloy steels like the 4140 material used in rifle barrels, or what we'd all consider stainless types of steel. Cold treatment, for a plain low alloy steel (e.g. most vintage razors), properly heat treated, like 10xx steels does not show enough benefit to be a valuable addition to the process. There are numerous conflicts of interest in the present research processes in this field. The main one is that the people who advocate for the use of cryo treatments are often in the business of selling the equipment and supplies.

I agree that beliefs often exist in spite of facts.

Relative temperature is indeed a matter of what the thermometer says, and wind chill can't reduce the temperature of a metal below the ambient temperature.

The value of cryogenic treatment (if it has any) lies mainly in the removal of stresses (if it removes them) which were caused by cold-working. The majority of modern rifle barrels are no longer rifled by cutting or scraping processes. Instead the rifling is made by various processes which impress the internal rifling into a smooth bore. This undoubtedly induces stresses, and heat would remove them, but would also remove the heat-treatment which may be of some slight value in a rifle barrel or many other objects, but is everything to a razor. However the barrel has internal stresses, and can change from Alaskan to finger-burning temperatures in use, so that some users think the rather speculative process of cryogenic treatment is worth trying. It is unlikely that either applies to the razor.

I deal with so many human beings and relative temperatures I missed the obvious about metals exposed to cold. Metals don't feel the temperature, they would only cool quicker in the wind.

Cryogenic treatment of steel (there are a lot of other metals reported to benefit from cold treatment) converts retained austenite from the heat treatment process into martensite. RA is a larger crystalline structure than martensite. Stresses internal to the metal can be caused by the increase in size, reducing that reduces internal tension. The RA is unstable and that contributes to the potential for fracture sites within the metal. Treated retained austenite becomes untempered martensite, another brittle structure. Correction of that requires an additional tempering cycle to change all the martensite present to tempered martensite. The metallurgical rationale for using cold temperatures has a greater effect on the crystalline stresses induced by the heat treatment process than machining stressors.

The idea that an old blade could have been heat treated and contained retained austenite that would convert into untempered martensite, putting the blade at greater risk from fracture, either from aging or the cold of winter is plausible and could contribute to the legends that initiated this thread. We just don't know enough about the old blades or their processes to know for certain.