Are CPM ( Powder Steels ) More prone to chipping?

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Steel130 said:
I have heard some talk that powder steels such as CPM154 and S30V ect. are more prone to chipping?
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I think I read the thread you're talking about; the one in the Buck forum with some folks complaining about used and abused knives purchased off of the Bay having chips. Namely the Bass Pro CPM154 and Cabela's S30V 110s.

Over the years people get set in their ways and opinions, and don't wish to change. I don't know how much credence than lends to the position, however.
 
To the original question I will base my answer on experience only and say that No, CPM steel are no more prone than other steels. I however would like to point out that 99% percent of the "chips" in a edge claimed by users are not chips at all but compressions and deformations.
 
Its hard to tell, but I think an example of the evidence that powder steels are less tough than ingot steel was that cpm 154 chipped when M390 rolled. If this example was provided as evidence that powder steel chips easier than ingot steel, the provider should be aware that both are powder steels.

Edited: After rereading the thread, this is not the comparison that was made. That said, M390 rolling on cardboard has nothing to do with it's charpy values. That is a hardness/strength and geometry issue.
 
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Larger carbides are not clumps of small carbides closer together, unless you are talking about the molecular level. It is a larger collection of carbide "molecules" in the same orientation, all connected in their particular arrangement. The carbides in D2 (and other alloys) in the picture above can be removed and tested on their own for their properties, independent of the matrix they were removed from. Carbides can vary in size within the same alloy and it will depend on heat treatment and steel production method (example: ingot vs cpm). Carbides definately vary in size from one alloy to the other, and this depends primarily on composition.

The primary reason for the invention of the CPM process was the control of carbide distribution in ledeburitic steels. The carbides are smaller and more uniformly distributed. Smaller carbides, with the same volume percent, provide greater toughness and greater wear resistance at the same time. Normally these two properties are inversely related. The same steel produced using CPM technology will have greater toughness potential than one produced from ingot steel, as long as the steel has a high enough alloy content to benefit from CPM in the first place. I say potential because people can screw up anything. Many of the steels produced using the CPM process could not be produced any other way. They would not even be steel if producing them using ingot methods was attempted. They'd be specialized cast irons. The benefits of reduced carbide and grain size resulting from CPM processing have spread to other alloys with less carbon, such as CPM 3V. I haven't had a chance to use ledeburitic yet, sorry.
 
Search words: 425MOD Chip.

https://www.google.com/search?q=425m...ient=firefox-a

After several pages, no specific complaints or forum discussions of the problem of 425MOD chipping (although there were a couple references to S30V chipping).

Search words: 440C Chip.

https://www.google.com/search?q=440C...ient=firefox-a

Again, after several pages, no specific complaints or forum discussions on 440C chipping (although, AGAIN, there were a couple comparisons to S30V chipping).

Search words: BG-42 Chip.

https://www.google.com/search?q=bg-4...ient=firefox-a

Same result as above.

Search words: 420HC Chip.

https://www.google.com/search?q=420h...iw=981&bih=478

Same result as above.

Search words: S30V Chip.

https://www.google.com/search?q=s30v...ient=firefox-a

Oh Mama!!! What a difference! More complaints of S30V chipping than you want to count. Hundreds, probably thousands if you took the time to read all the hits......and over a number of years.

Lots of guys saying the same thing......"My S30V knife is chipping......Why? What's wrong?"

The only explanation for all this would be a massive internet conspiracy. Not likely.......more likely the internet reflects the real world experience.

Yet.......here on this forum we have several who defend the powder steels to the bitter end.

"Not only it don't chip.......but it don't hardly get dull, ever!!"

But.......

"It sharpens up real nice and easy."

Contradictory? Not in the magical world of powder steels.

In the magical powder steel world, a steel can be hard enough to hardly never get dull and still sharpen up real nice and easy. Of course......powder steels are made at the Hogwarts School of Witchcraft and Wizardry.

:D

My theory is that a lot of people people bought the hype and the Kool-Aide and it's real, real hard to admit you were wrong.

Anyhow, I'm getting rid of the few S30V knives that I own, before it's too late.

:cool:
 
Uhm...S30V isn't the only powder steel. That single steel can't show the cpm/powder processes are inferior.

That said, it's pretty well known that the first batch, and maybe some subsequent batches, of S30V had some issues. The cleanliness/impurity level wasn't where it should have been. S30V is tricky to heat treat. S30V also has a very high carbon content. It's not like you can use a 1.45% plain carbon steel and not have some chipping issues.

Knives chip for a huge variety of reasons. However, when someone buys a knife made using a "new" technology, and then it chips or otherwise fails to perform up to expectations, that new tech will get all the blame, whether it deserves it or not. The fact remains that when steels of the same composition, such as CPM D2 and ingot D2, are compared, the CPM steel will be superior in almost every trait, except price. There is much more to a knife than steel choice.

I will agree that S30V was pushed and hyped to an enormous degree. I also don't think it's good enough for me to spend money on for a knife. However, I have used S60V, and found it to be great in every respect for a knife steel. Sadly, it was discontinued.
 
me2 said:
Uhm...S30V isn't the only powder steel. That single steel can't show the cpm/powder processes are inferior.

That said, it's pretty well known that the first batch, and maybe some subsequent batches, of S30V had some issues. The cleanliness/impurity level wasn't where it should have been. S30V is tricky to heat treat. S30V also has a very high carbon content. It's not like you can use a 1.45% plain carbon steel and not have some chipping issues.

Knives chip for a huge variety of reasons. However, when someone buys a knife made using a "new" technology, and then it chips or otherwise fails to perform up to expectations, that new tech will get all the blame, whether it deserves it or not. The fact remains that when steels of the same composition, such as CPM D2 and ingot D2, are compared, the CPM steel will be superior in almost every trait, except price. There is much more to a knife than steel choice.

I will agree that S30V was pushed and hyped to an enormous degree. I also don't think it's good enough for me to spend money on for a knife. However, I have used S60V, and found it to be great in every respect for a knife steel. Sadly, it was discontinued.
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Yes.
YES,
Try M390.
 
mete said:
Typical steels are made in a furnace ,many tons worth. The steel is then poured into a series of ingot molds to form ingots of steel which are on the order of 20" diameter and 10' or so long.Solidification of the ingot causes various problems of segregation of elements and a carbon and alloy rich center.
I have no idea what "free carbon " is.
The blademaker's HT makes a big difference in properties !
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My understanding of the meaning of "free carbon" is the amount of carbon in the alloy that is free to combine with the iron to form cementite (iron carbide) after some of the carbon is taken up with the other carbide formers such as chromium and vanadium. ZDP-189 has 3.0% carbon, but the 20.0% chromium ties up a lot of that carbon in chromium carbides so that less of it is "free" to form iron carbide.
 
me2 said:
Its hard to tell, but I think an example of the evidence that powder steels are less tough than ingot steel was that cpm 154 chipped when M390 rolled. If this example was provided as evidence that powder steel chips easier than ingot steel, the provider should be aware that both are powder steels.

Edited: After rereading the thread, this is not the comparison that was made. That said, M390 rolling on cardboard has nothing to do with it's charpy values. That is a hardness/strength and geometry issue.
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Actually I was comparing the 154CM in my Emerson CQC-7 with the CPM-154 in my Galyean Pro Turbulence. But I can see how one would confuse the two given the backwards naming process:D.

For M390, I don't have a clue as to what the Charpy values are, nor whether or not those values have any impact on my real world use. Hardness was Rc 62, edge thickness was typical Phil Wilson thickness, so a roughly 1" wide blade with a full flat zero edge grind with a microbevel for an edge(that is to say, stupid thin), and the microbevel would be about 15-20 degrees per side(hard to say for sure). Quite an impressive outcome given the hard blade, the thin edge, and the fact that I was cutting inch-thick cardboard used to hold watermelons into a pallet.
 
Bill1170 said:
My understanding of the meaning of "free carbon" is the amount of carbon in the alloy that is free to combine with the iron to form cementite (iron carbide) after some of the carbon is taken up with the other carbide formers such as chromium and vanadium. ZDP-189 has 3.0% carbon, but the 20.0% chromium ties up a lot of that carbon in chromium carbides so that less of it is "free" to form iron carbide.
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Have a look at the iron-iron carbide phase diagram to see where cementite is formed. You'll get cementite even on slow cooling to pearlite as long as the steel is hypereutectoid. Carbon isn't a real strong carbide former; metals like manganese, chromium, molybdenum, tungsten, vanadium, niobium, titanium are all stronger. Cementite also isn't very hard/wear resistant in comparison.
 
Noctis3880 said:
Actually I was comparing the 154CM in my Emerson CQC-7 with the CPM-154 in my Galyean Pro Turbulence. But I can see how one would confuse the two given the backwards naming process:D.

For M390, I don't have a clue as to what the Charpy values are, nor whether or not those values have any impact on my real world use. Hardness was Rc 62, edge thickness was typical Phil Wilson thickness, so a roughly 1" wide blade with a full flat zero edge grind with a microbevel for an edge(that is to say, stupid thin), and the microbevel would be about 15-20 degrees per side(hard to say for sure). Quite an impressive outcome given the hard blade, the thin edge, and the fact that I was cutting inch-thick cardboard used to hold watermelons into a pallet.
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Its not a knock against the knife or steel. At that geometry and hardness, its possible that no steel would have made that cut without rolling, but it didn't chip. At any thicker geometry, you likely couldnt have made the cut at all. I know I've made cuts with a Schrade peanut that my BM TSEK just could not make. I was not phisically able to push the knife hard enough to make the cut.
 
Ankerson said:
Yeah the metals used in the Aerospace industry are much more advanced than the typical knife blade steel.

Then the treatment of those alloys in the manufacturing process and treatment process is much more advanced than for the typical knife blade, railroad rail, steel I-Beam ect.

That would be a whole different topic completely.


People trying to do a cross relationship between the steel applications really isn't realistic.
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Yes it's like comparing an anvil to a blade.
 
 
The Mastiff said:
Powder steels seem easier to sharpen ( say a DMT diafold, for instance) than their ingot steel counterparts of similar composition and hardness. Is it my imagination or is it a real thing? I don't recall ever seeing the claim made by a steel company or knife manufacturer.

154cm vs CPM 154 both @ or around rc 59-60

and....

D2 vs. CPM D2 Both @ or around RC 62

These are the ones I have the most experience with and are closest in hardness figures claimed ( not tested by me) by manufacturers.
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mete said:
Powder steels ARE easier to sharpen.
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If this is the case, then powder steels are less wear resistant than their ingot steel counterparts; no?
Powder steels no doubt have even carbide dispersion, so why are they easier to sharpen?
What else can it be due to except the fact that they are compressed in non-molten form?
 
 
Buck_110 said:
If this is the case, then powder steels are less wear resistant than their ingot steel counterparts; no?
Powder steels no doubt have even carbide dispersion, so why are they easier to sharpen?
What else can it be due to except the fact that they are compressed in non-molten form?
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1. No
2. Because they have even carbide dispersion
3. Because it isn't about wear resistance, since the alloy composition and hardness are the same. It is about how much effort it takes to get the edge sharp. With a higher quality microstructure, it is easier to form the edge. If the edge is not chipping, rolling, or burring while you are sharpening, then the edge forms faster and more cleanly.

Knife steels are compressed in non-molten form. Forged down rounds, pattern welds, laminates, mosaics, etc. The steel is not remelted to make a blade. The sheets that stock removal blades are made from were not poured directly into 0.125" plates. Photomicrographs have already been linked, there are no voids at micron levels.
 
Buck_110 said:
If this is the case, then powder steels are less wear resistant than their ingot steel counterparts; no?
Powder steels no doubt have even carbide dispersion, so why are they easier to sharpen?
What else can it be due to except the fact that they are compressed in non-molten form?
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Well, I've heard that story, too!!!

Never gets dull but easy to sharpen!

Doesn't make sense at all, does it? Ah, but it CAN make sense when we cross over into the supernatural.

What other explanation can there be except that powder steels are made at the Hogwarts School of Witchcraft and Wizardry?

Surpassing even the Vorpal blades, these powders are tossed in the air by elves and magically reform as perfect sheets of supernatural steel from which blanks can be stamped out like Christmas cookies (and great profits can be made).

Never gets dull and sharpens up real easy.

The masses will believe anything if you say it often enough and loud enough.
 
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