Are CPM ( Powder Steels ) More prone to chipping?

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here's an old drawing by kovacsgy (posted 7 yrs ago) that shows how lateral and longitudinal toughness might matter to a blade. Of course, if the steel is cross-rolled, forged down, folded, EDM'd from large stock, and other such things happen, your toughness values would change with the direction. I like steels that have an advertised increase toughness in the same level of wear resistance over others, like picking 3V over D2. Or even for small increases, which may or may not fall within the range of results for charpy testing. Saying 'don't compare charpy results for different steels' was pretty common for a while, but that is exactly what the mills do, especially in their discussion of PM offerings. A lot of their bar graphs feature impact toughness right next to grindability and wear resistance (oh yeah, those are different, and vary between different steels, despite opposing beliefs)
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I have one blade in 420HC and I am not really that impressed. Its a kershaw so the heat treat should be right. But compared to S30V or even just 14c28n it has hardly and edge holding ability.
Back to the discussion on toughness and strength. From what I could gather an edge rolling is not due to insufficient toughness but rather strength. For example if you were cutting a piece of cardboard and your edge rolls this is because the force applied laterally to the blades edge exceeded the blades strength? And if you were to make the same cut but your edged chipped this would probably be due to hitting an impurity in the cardboard ( I gather cardboard has alot of junk floating in there ) and the impact chipped the blade, this being were toughness, resistance to deformation when hitting an object harder than the blade, comes into play?
 
sodak said:
CPM 10V and 3V easily live up to the hype, IMO. This is based on my personal experience, not what other people say. I did have Ankerson confirm my CPM 10V results, and he agreed with me, although the difference for him might be less, as he has more exotic steels than I do to compare it to.
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CPM 10V is an excellent steel all the way around and at high hardness it's very strong.
 
BG42EDGE said:
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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Only in the hundred acre woods.
[video=youtube;IZvF0Z2w_-c]http://www.youtube.com/watch?v=IZvF0Z2w_-c[/video]
 
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Noctis3880 said:
...confusion with the fact that 420HC having little to no carbides naturally makes it tougher.
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420 HC may not be the highest carbide steel in the drawer, but it certainly does contain carbides; a small amount of V carbides, with the majority being Cr carbides.

Noctis3880 said:
I feel the comparison would be more fair if you were to compare the ingot steel to a direct PM counterpart.
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These are the only comparisons I pay any attention to.

hardheart said:
Saying 'don't compare charpy results for different steels' was pretty common for a while, but that is exactly what the mills do, especially in their discussion of PM offerings.
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I'd like to see independent Charpy tests conducted on finished knives. Data collected in this manner would actually count for something.
 
Steel130 said:
And if you were to make the same cut but your edged chipped this would probably be due to hitting an impurity in the cardboard ( I gather cardboard has alot of junk floating in there ) and the impact chipped the blade, this being were toughness, resistance to deformation when hitting an object harder than the blade, comes into play?
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I wouldn't call that impact toughness related either. That's more a ductility issue, and again, strength, and geometry. Impact is at the speed of being hit with a hammer, say if you were chopping into the cardboard. I don't think just cutting it is fast enough to be impact. You can certainly cut cardboard and hit an inclusion, and push on through it. If the edge isn't hard enough (strong enough), then the inclusion can deform the edge and break the deformation off. This will look like a chip, but it's not impact related.
 
Buck_110 said:
420 HC may not be the highest carbide steel in the drawer, but it certainly does contain carbides; a small amount of V carbides, with the majority being Cr carbides.
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not really. it's going to depend on austenization temperature, but if done at the higher end, it will have no primary carbides and the carbon will be dissolved in austenite and the chromium free for corrosion resistance.
 
Buck_110 said:
420 HC may not be the highest carbide steel in the drawer, but it certainly does contain carbides; a small amount of V carbides, with the majority being Cr carbides.
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It has .30% Vanadium, not enough to make any difference at all edge retention wise, it's there for grain refinement.

Any usable carbides are coming from the Chromium and with the low Carbon content not a lot of that is going into forming carbides.
 
Noctis3880 said:
420HC can go up to Rc 58 at best. S30V can be from Rc 57-62.
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I know. Many people say that's why S30V has a chipping problem.

I also don't understand your confusion with the fact that 420HC having little to no carbides naturally makes it tougher.
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I quite understand that and I have no confusion about it. Again, that's why there are few reports of 420HC chipping as compared to the huge number of reports of S30V chipping.

Where there's that much smoke--there must be quite a fire.

S60V will chip more than S30V, S90V will chip more than S60V, and S125V will chip more than S90V. More carbides = more chipping.
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That sounds logical......and logic is appreciated.

I feel the comparison would be more fair if you were to compare the ingot steel to a direct PM counterpart. Apples and oranges and all that.
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We have been comparing types of steel, not types of fruit.

S30V is a type of steel that is plagued by huge numbers of reports of chipping--and I have indeed searched the internet for such reports on many types of steel--and S30V is the champion chipper by FAR.

That's the comparison and it is quite fair.
 
Ankerson said:
It has .30% Vanadium, not enough to make any difference at all edge retention wise, it's there for grain refinement.
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No doubt, but it's highly doubtful that zero V carbides will form.

Ankerson said:
Any usable carbides are coming from the Chromium and with the low Carbon content not a lot of that is going into forming carbides.
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I agree. A lot of the Cr will be free, hence the reason I stated 420 HC isn't the highest carbide steel out there.
 
BG42EDGE said:
I know. Many people say that's why S30V has a chipping problem.



I quite understand that and I have no confusion about it. Again, that's why there are few reports of 420HC chipping as compared to the huge number of reports of S30V chipping.

Where there's that much smoke--there must be quite a fire.



That sounds logical......and logic is appreciated.



We have been comparing types of steel, not types of fruit.

S30V is a type of steel that is plagued by huge numbers of reports of chipping--and I have indeed searched the internet for such reports on many types of steel--and S30V is the champion chipper by FAR.

That's the comparison and it is quite fair.
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S30V is a bastard to get the HT and tempering correct, but if it's done correctly the chipping issues do go away and it's very stable.

The S30V of today isn't the same S30V that was developed back when it was first introduced, they changed the alloy content slightly so it won't take the high hardness that that 1st run would. So what happened was the HT formulas had to be changed to deal with the issues, some did that better than others, faster than others.

Spyderco, Buck, Strider and Chris Reeve (Lately) handle S30V much better than most others do, there are also some custom makers that really know how to HT and temper S30V extremely well, Phil Wilson being at the top of that list.
 
Buck_110 said:
No doubt, but it's highly doubtful that zero V carbides will form.



I agree. A lot of the Cr will be free, hence the reason I stated 420 HC isn't the highest carbide steel out there.
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There are no Vanadium carbides being formed in 420HC, and maybe 1% or 2% at the very most Chromium carbides and that is stretching it....

420HC is a low alloy steel, very stainless due to the Chromium content.
 
Ankerson said:
S30V is a bastard to get the HT and tempering correct, but if it's done correctly the chipping issues do go away and it's very stable.

The S30V of today isn't the same S30V that was developed back when it was first introduced, they changed the alloy content slightly so it won't take the high hardness that that 1st run would. So what happened was the HT formulas had to be changed to deal with the issues, some did that better than others, faster than others.

Spyderco, Buck, Strider and Chris Reeve (Lately) handle S30V much better than most others do, there are also some custom makers that really know how to HT and temper S30V extremely well, Phil Wilson being at the top of that list.
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And I can believe that to a certain extent. However......I find that my dollars, without exception, go to other steels.

Why should I gamble on a difficult and problematic steel with such a poor history of good performance when there are other steels of excellent reputation?

In fact, why should anybody take that gamble?
 
Gator97 said:
Dude, what's up with you and 420HC anyway, it is as usual softer than CPM S30V and doesn't have carbide content S30V does. Chipping is not the only way edges dull, rolling is much more of a culprit.
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Would you be more comfortable if the comparison was with ATS-34? Or BG-42? Or D2? Or INFI?

Because the result is still the same. Huge numbers of reports on S30V chipping.......not on the others.

Refer my earlier post with links.
 
BG42EDGE said:
And I can believe that to a certain extent. However......I find that my dollars, without exception, go to other steels.

Why should I gamble on a difficult and problematic steel with such a poor history of good performance when there are other steels of excellent reputation?

In fact, why should anybody take that gamble?
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I EDC S30V more than any other steel and I have had zero chipping issues and I also use it at work a lot and hard.
 
Ankerson said:
There are no Vanadium carbides being formed in 420HC...
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That's an impossible statement to make with 100% certainty. How can you be sure no V is bonding with the C? Granted, there may not be enough to notice a difference, but that doesn't automatically equate to no vanadium carbides being formed.

Ankerson said:
...and maybe 1% or 2% at the very most Chromium carbides and that is stretching it....
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What is the basis for the percentage of Cr carbides formed?
 
Buck_110 said:
That's an impossible statement to make with 100% certainty. How can you be sure no V is bonding with the C? Granted, there may not be enough to notice a difference, but that doesn't automatically equate to no vanadium carbides being formed.



What is the basis for the percentage of Cr carbides formed?
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With .30% Vanadium and the low percentage of Carbon there is no way that any Vanadium at all is being formed into carbides, there just isn't enough carbon nor Vanadium in the steel.

Carbon .46%

Chromium 13.00%

Silicon .40%

Vanadium .30%

Manganese .40%


Sorry, but the carbide formers just ain't there other than Chromium and at 13% and with that low Carbon content..... Well it's just not happening sorry.

420HC is a good steel, it's a nice inexpensive steel that is good for general uses and that's pretty much it and Buck has done a good job with it.
 
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