Thread: Exotic steels for strait razor making

Mike: About Nitrobe 77, it's reportedly hard to get and only in 2mm thick barstock. That seems to be too thin for a typical straight, maybe a frameback though. The nitrogen replaces the carbon and significantly improves rust proofing. For comparison, stainless steels will rust. One of the folks who tested this stuff ground the blade from hardened stock because heating it to heat treat it will drive off the nitrogen and lessen the desirable qualities of the nitrogen saturation. The heat treatment routine requires a cold quench/cycle four times. Hard to get, complex heat treatment, excess care grinding all equal expensive.

Joed: plain carbon (low alloy) steels that are correctly heat treated do not generally require nor improve from cryo treatments. In high alloy steels that contain aggressive carbide formers like chromium et al, there is retained austenite. Cryo treatment converts retained austenite to untempered martensite, so an additional tempering cycle is needed when this is done. Some steels will have retained austenite upwards of 25% despite cryo treatment and those would include most of the exotic alloys previously discussed in this thread.

Austenite is relatively softer than martensite. For most applications it is detrimental in the steel. In some steels retained austenite can convert over time to untempered martensite at room temperature. This is the basis for some legends about blades getting harder over time. This is probably best explained by increased brittleness from the untempered martensite formed from the RA because when this phenomena was noticed there were no really scientific methods of hardness testing and that metallurgy has improved the ability to microhardness testing and differentiate the martensite and the retained austenite.

The CPM, powder metallurgy metals are a big improvement because of the more even distribution of all the alloying components, but it's not the carbon equation. As soon as the steel is heated above austenitizing temperature, the carbon will go into solution and diffuse evenly throughout the bar no matter the particle size originally. If temperature controls are closely exercised CPM steels will have a much finer crystalline grain size than a cast steel type could get even with repetitive grain refinement cycles but then if you're like me and enjoy the appearance of dendritic carbides those are lost.

As always, there is a balance between features and performance. Some of those can approach each other around a mean value while others have to be balanced at both ends of a spectrum of effects.

Rsq: there is a phrase, the better is the enemy of the good. I don't believe you will find a perfect steel. In three to five years, your perfect steel will be ordinary and out of fashion and not cool any longer.

Even so, I admire all your enthusiasm and would not discourage you in your exploration. I remember when I was like that. Now I'm old and in the way. Happy too.

Thanks for your perspective on CPM and Cryo treatments Mike. I too am getting old and in the way most times. Here is some interesting reading from Crucible, a respectable metal company: http://www.crucible.com/eselector/ge...eralpart3.html

As for cryo treating, I posted some links a while ago. I'll search for it some other day.

I like Crucible, Sandvik, Bohler-Uddeholm as companies and makers of fine products, both traditional and CPM. Damasteel is another CPM product. Don't get me wrong, cryo treatments have their place in the heat treatment cycle, for certain materials, but even when used they are often not applied in the best fashion. Since I mostly always am working with a low alloy steel and can precisely control what I'm doing to them, I don't have a need for all the extra equipment and the price to gain only a small fraction of performance that may not be significant.

Cryo cycles refine the grain, which is important for razors. As to which materials merit them and which don't, I'm not sure. I've only recently begun learning about metallurgy.

Does anyone know where to find cts xhp in thicker bars? I can only seem to find it in .15" or less. I would like to find it in ~.25" thickness

I also ordered some elmax, which is VERY similar to m390, with just a slight amount less V, so I'll be able to compare the two

I do not have near the depth of knowledge or experience that Mike has with steels. But I did my fair share of experimenting with a limited number of high alloy steels. Most of it in the wood working plane genre. I thought when it first came out CPM10V would be the be all and end all. In the end I am where Mike is. A simple carbon steel blade made from quality steel and properly handled can't be beat.

But neither will I discourage anyone from eating up tons of belts and searching (and paying) for the best steel and heat treat.

For this is something you must taste for yourself.

There is everything to be said for that approach. it's traditional, well understood, and produces consistent results. For me, though, it just lacks that shiny-new-toy allure, the cutting-edge coolness factor (I know, it's a pun)

Originally Posted by Rsq

There is everything to be said for that approach. it's traditional, well understood, and produces consistent results. For me, though, it just lacks that shiny-new-toy allure, the cutting-edge coolness factor (I know, it's a pun)

Don't get me wrong
Cool is not a bad thing or without merit. Right now I am scouting the Texas country side for good magnetite (found some actually) and refining my charcoal making system in preparation for trying to smelt steel in something resembling a Tatara. Why, because it will produce the best steel known to man? Nope-Because it think it is cool. And what I think is important

I just did some reading about k390
Needless to say, I must make something with it. I ordered enough for a large tanto and a santoku. I'm wondering if it will take an edge worthy of a straight razor. At 9% vanadium, this is a very big question, but I have also heard great things about bohler's 3rd gen pm steels fine grain, so I was wondering if anyone hadps any experience with it?

I know...it is ridiculously hard to machine...but from what I understand, it's worth it.