CPM440c?

harrymole,
You make alot of sense and don't be surprised if a particle metallurgy version of D2 makes its way to the market. The CPM process has its limitations and surprisingly enough it is limited in the direction of lower alloyed steels and tool steels. To the best of my knowledge there never has been a CPM S7 produced and this will never happen. ESR S7 has been made but not CPM S7.

We discussed CPM 154 for years and decided to introduce it because the custom knifemakers wanted a more user friendly, premium quality, stainless knife blade steel. One that was easier to grind and easier to finish than CPMS30V. We try to listen to our customers and that is why we introduced CPM154. This grade is for the custom knife makers and if the production companies want to use it - great.

Two things we learned about CPM154 - it will achieve a higher hardness than conventional 154CM when using the very same heat treat procedure and it is tougher than conventional 154CM - approx 2X the toughness.

We can do extensive testing and publish the data but until the steel is used, tested, and endorsed by custom knife makers, production knife companies and end users - all the data we provide doesn't have much merit.

Thanks for listening.

T.Scott Devanna
 
tsdevanna said:
To the best of my knowledge there never has been a CPM S7 produced and this will never happen.
Click to expand...

I just checked the data sheets, yes it doesn't state CPM S7, it just states Crucible S7 is a double refined high purity version of S7, not a CPM product.

We discussed CPM 154 for years and decided to introduce it because the custom knifemakers wanted a more user friendly, premium quality, stainless knife blade steel.
Click to expand...

As Blop noted, there are already powdered versions of 154CM produced, custom makers have been using it for some time, so why didn't the guys asking for CPM154CM just use that?

Two things we learned about CPM154 - it will achieve a higher hardness than conventional 154CM when using the very same heat treat procedure and it is tougher than conventional 154CM - approx 2X the toughness.
Click to expand...

154CM from your own data sheets can be tempered to 65 HRC with oil+cold. How hard does CPM-154CM get under the same heat treatment? Or do you just get better hardness without accelerated quenches/cold.

Using exactly what measure of toughness is there a 100% improvment, how does it compare across the rest of them, Charpy, Izod, torsional, c/v notch, area under stress/strain curve and ductility ?

-Cliff
 
Thanks tsdevanna for your comments on this subject. I thought the article in Blade was very interesting and us knife nuts are always interested in the latest and greatest steel. I think by using the CPM process on 154CM we can learn alot about steel and its' properties. My only goal is to give the reader an idea, a thought on how we can as a community make the steel we have better before we move on. Who is to say that our next great steel isn't new but only improved. Example: ( I love examples ) SwampRat knives. They took 52100 ball bearing steel heat treated it and tempered it to its fullest extent and created SR101. So why not take the next step, we already have the steel lets improve it, try to get what we want out of it. Create, rebuild and manipulate until it is what we want. One more thought has anyone try to combine certain aspects or even differant steels to get a hybrid? Thanks.
 
I am familiar with Roman's work, the basic principles were discussed on rec.knives over ten years ago, and it was known there before then. However it is only the critical point of failure on very low angles at very high edge polishes. If you take D2 and W1 down to very acute edges then W1 at 66 HRC compares very well to D2 at 58/62 HRC. However once the edge thickens to the point that the D2 is well enough supported it doesn't suffer failure due to carbide tear out and thus the edge retention is high. This is how Dozier and Boye can be well respected for very high cutting ability and edge retention evne though they use alloys with very coarse grain structure, in particular Boye uses steels which still have the primary as-cast carbide aggregates. However this doesn't have to mean he gets low edge retention for reasons I noted earlier.

-Cliff
 
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