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#3800253 - 02/15/10 12:15 PM CPM 154 vs 154CM
michiganroadkill Offline
Campfire Guide

Registered: 12/23/04
Posts: 2534
Loc: western michigan
From Crucibles DATA SHEET
"CPM 154 is CPM-manufactured version of Crucible's standard 154CM. The CPM manufacturing process produces a uniform distribution of the carbides in this grade, giving this CPM 154 easier grinding and polishing, plus better toughness than conventional 154CM, while retaining similar heat treat response and wear properties."
"CPM" is a powdered metal process.
There is no mention of a chemical difference between CPM 154 and 154 CM.

Hitachi makes ATS34 and Crucible makes 154CM. They are near identical in chemical make up.
The biggest difference in ATS 34/154 CM from 440C is that they both have about 3% less chromium and 4% more molybdenum than 440C.
There is no amount of vanadium listed for 154CM, ATS 34 or 440C.

I received my 154CM today.
Tim
_________________________
"The significant problems we face cannot be solved at the same level of thinking we were at when we created them."
Albert Einstein

At Khe Sanh a sign read "For those who fight for it, life has a flavor the protected never knew".

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#3802885 - 02/16/10 06:49 AM Re: CPM 154 vs 154CM [Re: michiganroadkill]
1234567 Offline
Campfire Guide

Registered: 11/26/07
Posts: 4320
Is it CPM 154 CM or 154 CM?

Did you get it in sheets or bars? What size?

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#3803609 - 02/16/10 10:55 AM Re: CPM 154 vs 154CM [Re: 1234567]
K_Salonek Online   content
Campfire Regular

Registered: 05/11/09
Posts: 825
Loc: Base of the Rockies, Colorado
Ditto?

And is it forgeable, if I may ask?
_________________________
Clinging to my God, and my guns!

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#3803826 - 02/16/10 12:19 PM Re: CPM 154 vs 154CM [Re: K_Salonek]
michiganroadkill Offline
Campfire Guide

Registered: 12/23/04
Posts: 2534
Loc: western michigan
It is 154CM.
I got a couple smaller odd size "drop" sheets in .127-.132" thick. It was shirttailed in with another order of 2'x3' sheets.

I am not a forger, but I think that anything is forgeable. Ed Fowler forges 52100 and gets a much tighter grain structure. I guess the question is can you master the heat treat process after you have forged it. I think all forgers do their own heat treat don't they????

The CPM process improves the grain stucture also by using smaller and more uniform size particles--so the mfr says.

Tim
_________________________
"The significant problems we face cannot be solved at the same level of thinking we were at when we created them."
Albert Einstein

At Khe Sanh a sign read "For those who fight for it, life has a flavor the protected never knew".

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#3804102 - 02/16/10 01:56 PM Re: CPM 154 vs 154CM [Re: michiganroadkill]
1234567 Offline
Campfire Guide

Registered: 11/26/07
Posts: 4320
One problem with forging 154 CM is the air hardening when it cools.

I have read some of Wayne Goddards writing and he sends the stainless alloys to Paul Bos for heat treating.

154 CM and others, such as D2, ATS 34, and 440C have a tendency to decarbonize when heated in a standard furnace. That is the reason these steels are heat treated in a vacuum or controled atmosphere furnace.

Heating in a forge would be exposing the steel to the atmosphere, and the contact with the Oxygen in the air could cause it to decarborize, which, in my opinion would cause the steel to be worthless as a cutting tool. I don't know if it could be hardened if it decarborized very much.

But, that might depend on the depth of decarborizing. If the decarborized depth is shallow, then the blade could be ground down after forging, removing the decarborized skin, unless it decarborized all the way through. But then, it would have to be annealed, stress relieved, then heat treated in a controlled atmosphere or vacuum furnace if it only surface decarborized.

That is one reason why forgers prefer steels like 52100, 01, W2, 1095 because they can be heat treated with a torch or in a forge. Apparently steels in this class do not decarbonize when exposed to oxygen when heated.

Some people do make layered stainless steel blades, but I don't know anything about how they prevent the stainless from decarbonizing. It is possible they let it decarbonize anyway, or use something like 303 stainless and layer it with 01, 52100, or one of the other carbon steels to get the layers or carbon and heat treatable steel.

My opinion, and I don't have a way to prove it, is that 154 CM and other stainless steels will slightly decarborize even when heat treated in a controled atmosphere furnace. This would be only a surface decarborization to a shallow depth.

I base this on the fact that most of my blades do not hold an edge very well on their first sharpening. They seem to hold an edge much better when some of the outside is ground or sharpened away.

Even blades that are very sharp initially will show a slight dulling even if they are not used. This could be from the lack of carbon, and formation of rust on the finely sharpened edge.

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#3804723 - 02/16/10 04:53 PM Re: CPM 154 vs 154CM [Re: michiganroadkill]
K_Salonek Online   content
Campfire Regular

Registered: 05/11/09
Posts: 825
Loc: Base of the Rockies, Colorado
Originally Posted By: michiganroadkill
It is 154CM.
I got a couple smaller odd size "drop" sheets in .127-.132" thick. It was shirttailed in with another order of 2'x3' sheets.

I am not a forger, but I think that anything is forgeable. Ed Fowler forges 52100 and gets a much tighter grain structure. I guess the question is can you master the heat treat process after you have forged it. I think all forgers do their own heat treat don't they????

The CPM process improves the grain stucture also by using smaller and more uniform size particles--so the mfr says.

Tim


Thanks Tim!

Yes, I get my 52100 from the same place Ed Fowler dose, mechanical reduced about 99% from 6 1/2 " virgin 53100 bars stock.

About the only thing different is our methods of reduction and final TH. Using a different quanchant Ed's is Texico Type 'A' , I use pure mineral oil. Ed gets his to cut, with over 35 years working on the process, with 3 differential quenches in 160F type 'A' for full hardness. Years less experience, I ,may be running a slight over-kill with one @ 145F , one at 155F and a final @ 160F , seems to work better for me, with the same 24-hours apart spent in a freezer. Just like Ed, I draw the temper 3 times at 2-hours each once up to temperature. Ed hardens slightly less into the blade, about 1/3, I go higher, about 1/2 way, and need to temper at a slightly higher temperature.

I believe they test very close to the same, hoping to get this on video, you can whittle steel off a horseshoe and still shave arm-hair when everything turns out right.

We may have the same reasons to strive for that small grain structure, as it seems to sure take a sharper edge with less effort!

It would be fantastic to see your work with your new steel!
_________________________
Clinging to my God, and my guns!

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#3804826 - 02/16/10 05:19 PM Re: CPM 154 vs 154CM [Re: 1234567]
K_Salonek Online   content
Campfire Regular

Registered: 05/11/09
Posts: 825
Loc: Base of the Rockies, Colorado
Originally Posted By: 1234567
One problem with forging 154 CM is the air hardening when it cools.

I have read some of Wayne Goddards writing and he sends the stainless alloys to Paul Bos for heat treating.

154 CM and others, such as D2, ATS 34, and 440C have a tendency to decarbonize when heated in a standard furnace. That is the reason these steels are heat treated in a vacuum or controled atmosphere furnace.

Heating in a forge would be exposing the steel to the atmosphere, and the contact with the Oxygen in the air could cause it to decarborize, which, in my opinion would cause the steel to be worthless as a cutting tool. I don't know if it could be hardened if it decarborized very much.

But, that might depend on the depth of decarborizing. If the decarborized depth is shallow, then the blade could be ground down after forging, removing the decarborized skin, unless it decarborized all the way through. But then, it would have to be annealed, stress relieved, then heat treated in a controlled atmosphere or vacuum furnace if it only surface decarborized.

That is one reason why forgers prefer steels like 52100, 01, W2, 1095 because they can be heat treated with a torch or in a forge. Apparently steels in this class do not decarbonize when exposed to oxygen when heated.

Some people do make layered stainless steel blades, but I don't know anything about how they prevent the stainless from decarbonizing. It is possible they let it decarbonize anyway, or use something like 303 stainless and layer it with 01, 52100, or one of the other carbon steels to get the layers or carbon and heat treatable steel.

My opinion, and I don't have a way to prove it, is that 154 CM and other stainless steels will slightly decarborize even when heat treated in a controled atmosphere furnace. This would be only a surface decarborization to a shallow depth.

I base this on the fact that most of my blades do not hold an edge very well on their first sharpening. They seem to hold an edge much better when some of the outside is ground or sharpened away.

Even blades that are very sharp initially will show a slight dulling even if they are not used. This could be from the lack of carbon, and formation of rust on the finely sharpened edge.


Thanks 1234567!

That would be a problem forging CPM 154 if it air hardened readily, especially if there were a hold time needed to bring it back down (soft). That memory would set up forging stress-cracks quickly. The extra time at temp would grow the grain and defeat the purpose of the powdered steel.

Air-hardening would keep it from being cold-forged, hot-forging will de-carb the steel. Gotcha!

52100 will decarbonize also, but working it in that just none-magnetic 'critical' range (cold-forging) dose not seem to decarbonize much, or grow grain size and dose not harden between forgings.

It still will not cut well till it has had a few sharpening, a trick for that is to just forge it 'big' profile it thick, and belt it down after HT . Takes a couple more belts, but since it's such a deep-hardening steel, never an issue it seems. Just can't grind with gloves, you want to know what temperature your grinding at, any color and it's scrap.

Thanks!
_________________________
Clinging to my God, and my guns!

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