Using the chemistry, RE: sword steel

More recent research into martensite morphologies have revealed that they are probably the result of the temperature at which they are formed, however this is inextricably tied to the alloy content. Most alloying will lower Ms and carbon is one of those, so the more carbon you have, the lower will be Ms and this will make the martensite more plate like in nature. So this gives the possibility of raising Ms by not putting as much carbon in solution, but allowances would also have to be made for other alloying elements, things like moly have a very profound effect on Ms. But much of this is a mute point to most bladesmiths since the controls necessarry to put precise predetermined ammounts into solution, and no more, is not exactly realistic with a forge All the same if you add this to the hazard of retained austenite, it you get all the more reason not to overheat your steel before the quench.
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I'm sorry, but I have a hard time believing that one. Maybe it would be more appropriate to say that I have a hard time wrapping my head around it, and I have a hard time accepting as fact a concept I don't yet understand. Either way, it makes it less plausible to me. Here's my problem:

It is my understanding (probably wrong) that if you were to do a simple water quench on 1095 (from full soloution) you would end up with a great deal of high stress plate martensite, wheras on the other hand, say, 1050, while barely sufficiently hardenable, would make all lath martensite which is much tougher.

Now, certainly, I am willing to concede that the carbon will depress the Ms point in the 1095 to a noticeable degree, however, I was under the impression that the martensite transformation is a continuous process, thus there would be a huge amount of overlap on a temperature chart where both steels would be forming martensite. The overlap should be greater than 300 degrees in duration.

Assuming my unserstanding of the cooling / transformation process is correct, then the premise that martensite morphology is temperature dependant would mean that the only place where the 1095 would form plate martensite would be in the window where it was forming martensite and 1050 wasn't. Being that 1050 started making martensite first, let's be simple and assume it also has a higher Mf than 1095, so all of the plate martensite 1095 would make would be formed at low (near ambient) temperatures.

Or, if not that, then it would mean that all of the lath martensite that the 1050 would form could only be formed in the relatively small window on a temperature chart where it was forming martensite, but the 1095 was not. This would mean that the 1050 would have completely finished its transformation, and reached Mf before 1095 had even cooled to the Ms point!


Since neither of these situations seem even remotely logical to me, I have a really hard time understanding how the morphlogy could be dependant on the tempreature at which the marketansite were formed.

I could, on the other hand believe that it could be influenced by an interplay of, say, alloying AND formation temperature.

I could be convinced that as the martensite transformation continues, it will tend to follow the morphology most present in the emerging martensite. This would make the Ms point quite critical as opposed to the carbon content where martensite morphology were concerned.

However, without a more thorough / clear explanation as to why it would be temperature dependant, I just have a hard time swallowing that.
 
To put it into common terms:
Dwarfs control the temperature curves of steel.
Elves determine when the Ms and Mf will happen.
Gnomes are responsible for alloying and carbides.
Trolls are responsible for most warpage and bad quenching.

When they all agree you get a perfect HT and a high quality blade.
Since they seldom agree, you usually have a trade off.
When they are really fighting, you get "PING".

There, that should clear it up.
Stacy
 
bladsmth said:
To put it into common terms:
Dwarfs control the temperature curves of steel.
Elves determine when the Ms and Mf will happen.
Gnomes are responsible for alloying and carbides.
Trolls are responsible for most warpage and bad quenching.

When they all agree you get a perfect HT and a high quality blade.
Since they seldom agree, you usually have a trade off.
When they are really fighting, you get "PING".

There, that should clear it up.
Stacy
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:thumbup: :D That does explain everything.
 
Dammit, I been blaming the gremlins for warpage the whole time, and it turns out they're innocent!

I'm gonna have to apologize to those gremlins.
 
So, if I do my hardening in the sunlight, will that keep the trolls from doing their nasty jobs on my blades? :)
 
Dan Zawacki said:
I'm sorry, but I have a hard time believing that one...
...It is my understanding (probably wrong) that if you were to do a simple water quench on 1095 (from full soloution) you would end up with a great deal of high stress plate martensite, wheras on the other hand, say, 1050, while barely sufficiently hardenable, would make all lath martensite which is much tougher...
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Well Dan, if you flip to page 36 of your "Atlas of isothermal transformation diagrams" From U.S. Steel (second edition) you will find the curve for 1095 that shows Ms to be at approximately 420F. and then if you look on page 39 you will see that 1050 will reach M90% at round 475F. Overlap??? One could take thier clue perhaps from bainite which roughly shares some characteristics with martensite (but is nowhere near as beatiful and refined;) ) a small bit of which is some shear based transformation, and has two distinct morphologies based solely upon temperature.

Now I know that we should be citing C-T diagrams, but I do not have a copy of an Atlas of C-T diagrams, and I am assuming Dan may not have his readily at hand;).
 
Wow, 90% at 475?? damn, that's hot.

I guess that makes the second premise the correct one, only without the whole tiny window thing, as the overlap I thought would be huge is practically nonexistant! Yikes!
 
butcher_block said:
i just puilled some thing from all this

cpm3v is .8 carbon and has 2.75 V in it so is that why the temps are over 2000 for most heat treating

it was my thought that having a "cpm2v" beign something on the order of 1.0 carbon and 2.0 V with the same other as 3v would make for a great steel (fine grain higher wear and higher hardness) as i could then harden it up to 64-65 and temper down a hair like i can with cpm10v. as fine as 1v sounds it to me jsut seems like its too soft being .55 carbon and 1.0 V
mind you im looking for a good high carbon kitchen knife steel (air quench)and love 3v but think i should be able to get it harder
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The closest thing to what you're asking for is Vanadis 4, though it has higher wear resistance than 3V, not less, but it's only available in round bar and thick sheet, and only through Europe. 3V has around 5% vanadium carbide by volume, and Vanadis 4 has around 8-9% vanadium carbide.

So since that is out of the question that leaves CPM-M4. CPM-M4 has even higher wear resistance than Vanadis 4, but is still rather tough and has high edge stability with very high potential for hardness and fine carbides. The carbide size and volume are smaller than 10V, and it is not as difficult to sharpen. Still hard to finish though. CPM-M4 has 4% vanadium carbide and 8% molybdenum and tungsten carbide, 10V has 17.5% vanadium carbide. CPm-M4 has small carbides because the molybdenum/tungsten carbides are very small, and don't form with the vanadium. 10V has so much vanadium carbide that they are larger than the carbides in Vanadis 4 and 3V, and with the high volume it has a low edge stability and is difficult to sharpen.

Hope this helps.
 
Perhaps I should just take a hint and read some of the wonderful metallurgical texts shared here, but would anyone hazard a reply on my earlier question in the interests of instant gratification?

the possum said:
Would 1080 be noticeably more resistant to rolling and plastic deformation than 1055 if both were tempered to the same hardness?
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thanks larrin the search continues for a air hardening super fine high carbon kitchen steel
i will have to try out M4 now tho
 
It isn't necessary to go above 2000F with 3V or most any other steel most of us work with. 1975F is fine. Temper at 950F. Just remember that air hardening usually isn't, especially with some CPM's like 3V and S30V.
 
Butch, have you tried pushing the hardness on 3V up to 63 Rc? You might try using the maximum austenitization temperature (2050F) along with a 950F temper like Jerry just recommended. I believe the 950F temper is peak hardness, though it could be a little higher than that (like 975F). Vanadis 4 and CPM-M4 can both get super hard (65 Rc and higher), you're already using 3V and you like it you might as well see what you can get out of it.
 
Perhaps I should just take a hint and read some of the wonderful metallurgical texts shared here, but would anyone hazard a reply on my earlier question in the interests of instant gratification?

Quote:
Originally Posted by the possum View Post
Would 1080 be noticeably more resistant to rolling and plastic deformation than 1055 if both were tempered to the same hardness?
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It was my understanding that hardness is defined as resistance to deformation. It would therefore follow that if they were treated to the same hardness, then any two steels would be exactly equal in resistance to rolling and plastic deformation. If edge rolling is a problem, I would suggest either the heat treat isn't optimal, or edge geometry isn't optimal.

On the other hand, toughness at a given level of hardness can vary from one alloy to another, or even to a pretty significant degree within one alloy with different treatments, all arriving at the same hardness.

If two different alloys were treated to a relatively high hardness, then it is possible that the tougher one could experience a plastic failure when the more brittle one would experience a more brittle failure.
 
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