Are CPM ( Powder Steels ) More prone to chipping?

[hardheart]

at least you have abandoned any attempt to appear like you understand anything being discussed

 

[Steel130]

at least you have abandoned any attempt to appear like you understand anything being discussed

HH how Long have you been studying the metallurgy side of steel? I would like to get as good as ou and others here some day.

 

[Longtrang]

at least you have abandoned any attempt to appear like you understand anything being discussed

You referring to me? I understand perfectly. After reading every post here and deferring to my own personal experience with the steel, I have concluded that s30v is difficult to treat properly but if done correctly it makes for a decent knife steel. Not the best, certainly not the worst but decent.

 

[hardheart]

Heh, aim a lot higher, like mete. He's a retired metallurgist. I just bought a bunch of books, downloaded more as pdfs, saved a lot of threads from mastersmiths, metallurgists, & the like, got a ton of research papers, stuff like that. Made a few forges and played around a bit before Katrina wiped most of it out. Several years of scratching the surface, really.

 

[hardheart]

You referring to me?

nah, the guy posting about fairy dust and magic shoes

 

[me2]

I dont fully understand how a blade can be stronger but not as tough. Seems like the two would coincide. Powder steels all also seem to aim for a more homogeneous structure or more uniform and without as many voids in the piece of steel right?

One of the problems is the use of different definitions for the same words. Strength and toughness have specific meanings for engineers, metallurgists, etc. They have generic and variable meanings when used in the knife industry. This leads to a great deal of confusion. With relation to toughness and knives, the specific meaning is usually taken to be impact toughness. This is the ability of a material to absorb energy under sudden loading (impact). This applies mainly to large chopping knives, which benefit from this property. A pocket knife or modern one hand folder hitting a knot in wood while whittling is not a situation where impact toughness is important. The load is not sudden enough, nor the target material hard enough, to get into impact toughness, unless the heat treatment was just a complete mess, like leaving the steel as quenched with no tempering. Likewise, the example of edge rolling during cardboard cutting is not related to impact toughness.

In its generic use, tough steel can be anything from high strength to difficult to grind. You can see where this would lead to a great deal of confusion for beginners and old timers alike. Generally speaking, impact toughness and strength are inversely related over a broad range of materials. Speaking specifically about knife steels, there are exceptions all over the place to this general rule. That's why people fool around with different heat treatments so much. They attempting to find as much of each as they can. For certain steels, decreasing the hardness (and strength) will decrease the toughness as well, in certain ranges.

 

[BG42EDGE]

You referring to me? I understand perfectly. After reading every post here and deferring to my own personal experience with the steel, I have concluded that s30v is difficult to treat properly but if done correctly it makes for a decent knife steel. Not the best, certainly not the worst but decent.

I thought he might be referring to me.

But I totally agree with you, so we're in the same camp.

The only thing I would add is that--when I put out a bunch of hard-earned dollars for S30V--how do I know that THAT PARTICULAR knife got the required perfect heat-treat to make it a decent knife????

And why should I gamble on it???

That's the salient issue that bothers a lot of people.

Bottom line is this: they could eliminate that issue by offering better steels, but they don't.

And what is there to stop them except us refusing to cooperate?

 

[sodak]

So it seems that powder steels performance can also be seen in being able to hold a thinner edge longer than other steels, not blanketing all steels, but as a goal. S30Vs toughness allows it to hold a stronger edge at say 30* inclusive versus a 440c edge at 30* inclusive.

I dont fully understand how a blade can be stronger but not as tough. Seems like the two would coincide. Powder steels all also seem to aim for a more homogeneous structure or more uniform and without as many voids in the piece of steel right?

You're on the right track, I think. I can't speak to CPM S30V, but if you harden CPM 10V above 62, you can indeed *drastically* thin the edge, and you can also do it with M2 HSS at 65 or 66 HRC as well. Strength is directly correlated to hardness (someone correct me if that's wrong), but I'm pretty sure of that statement. So IF you can get a steel to 66 or 67, it's going to be stronger than the same steel at 57. M2 HSS, CPM 10V, ZDP 189 all come to mind. They can be very strong if hardened to those levels, and the bevels thinned out drastically to take advantage of this. All this combined will give you unbelieveable cutting performance. And they sharpen faster than a Ginsu knife! I should also say that at those hardnesses, burring while sharpening is rare/trivial. These actually sharpen easier (for me) than more common steels at softer levels due to lack of large burr formation.

The only thing I would add is that--when I put out a bunch of hard-earned dollars for S30V--how do I know that THAT PARTICULAR knife got the required perfect heat-treat to make it a decent knife????

And why should I gamble on it???

That's the salient issue that bothers a lot of people.

You hit the nail on the head for me too. I think that they probably have the heat treat down pat by now, but I've had enough stinkers that I won't trust it anymore. I will say, I've NEVER had a bad knife in CPM 3V (from 3 different makers), I don't know if the heat treat is easier, or if there are only a few people that do it, and have excellent quality control. I guess that I should add - this is a concern for any knife and steel, how do you know the heat treat is spot on? You don't, at least until you test it.

In the end, you have to go by the reputation of the maker and/or heat treater.

 

[Handwrecker]

at least you have abandoned any attempt to appear like you understand anything being discussed

Everybody was thinking it. It's a shame BG42EDGE has to be rude and derail many threads of this nature. I've chipped my 420HC and not my S30V, but that doesn't cause me to champion a negative argument.

On a positive note, thank you mete for explaining the differences between the two kinds of impact strength. This thread has brought up many interesting aspects of steel that I wasn't aware of. Also, since S30V is a 1st gen powder steel, does that mean that 2nd and 3rd gen steels will benefit in similar ways, only to greater effect?

Keep the discussion flowing. :thumbup:

 

[BG42EDGE]

In the end, you have to go by the reputation of the maker and/or heat treater.

Well, true.......you kinda have to go with maker's reputation with most everything, but while that may make for fewer doubts.......the doubts are strong enough that I'll still stick with steels other than S30V powder if I'm laying a bunch of money on the line.

 

[BG42EDGE]

Handwrecker said:

It's a shame BG42EDGE has to be rude and derail many threads of this nature. I've chipped my 420HC and not my S30V, but that doesn't cause me to champion a negative argument.

As I showed earlier on this thread......the internet is awash with reports of S30V chipping and very, very few reports of 420HC chipping.

So your one report must be viewed in that perspective.

And you are confusing a little irony used to make a point with rudeness. A sense of humor is a wonderful thing.

 

[knarfeng]

Handwrecker said:



As I showed earlier on this thread......the internet is awash with reports of S30V chipping and very, very few reports of 420HC chipping.

So your one report must be viewed in that perspective.

And you are confusing a little irony used to make a point with rudeness. A sense of humor is a wonderful thing.

420HC has no carbides to speak of, and it is the size and distribution of carbides which make PM alloys superior in toughness to non-PM, carbide containing, alloys.

Your "humor" is wearing a bit thin on a lot of us. Either present a technical argument or don't post.

 

[loug]

brings to mind carbide tip tools used when i worked as a machinist. these inserts were so hard they would cut forever at higher speeds and didn't need cutting fluids to keep them cool. if you happened to bump it with a wrench or on the piece being cut they would chip or shatter like glass. same production method, powdered metals. probably the same with knives made from powdered metals. strong if used correctly. if accidentally dropped or abused they will chip very easily

 

[knarfeng]

probably the same with knives made from powdered metals. strong if used correctly. if accidentally dropped or abused they will chip very easily

You haven't read the entire thread, have you.

 

[Noctis3880]

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.

Actually I've made the cut plenty of times with a considerably thicker Spyderco Para2 in CTS-20CP(that chipped it a little), I just need to use more force to do so. Since then I've figured out that the trick to cutting that thick cardboard would be to make one light cut outside to trace the line, then cut again along the line, but deeper. Basically cut layers at a time rather than all at once. No more issues since then:thumbup:.

 

[BG42EDGE]

420HC has no carbides to speak of, and it is the size and distribution of carbides which make PM alloys superior in toughness to non-PM, carbide containing, alloys.

Uh-huh.......very impressive, very technical.......so that's why the internet is awash with reports of S30V chipping and very, very few reports of 420HC chipping?

Humor wearing a little thin? Because the internet is awash with reports of S30V chipping?

 

[Noctis3880]

Handwrecker said:



As I showed earlier on this thread......the internet is awash with reports of S30V chipping and very, very few reports of 420HC chipping.

So your one report must be viewed in that perspective.

And you are confusing a little irony used to make a point with rudeness. A sense of humor is a wonderful thing.

420HC can go up to Rc 58 at best. S30V can be from Rc 57-62. I also don't understand your confusion with the fact that 420HC having little to no carbides naturally makes it tougher. S60V will chip more than S30V, S90V will chip more than S60V, and S125V will chip more than S90V.

More carbides = more chipping. This is why they don't make knife blades out of pure tungsten carbide.

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. Now given that S30V can't even exist in ingot form, I don't feel it's relevant to this discussion unless you're willing to include CPM-3V in your comparisons. Now perhaps you can comb the internet for comparisons of D2 and CPM-D2 or M4 and CPM-M4, preferably from the same maker with the same heat treatment.

 

[knarfeng]

All right laddy. Back on ignore you go BG.

 

[Gator97]

My powder steel knife is so hard and holds an edge so well it practically never gets dull...... but it sharpens up real easy when it does get dull.

Yes, absolutely, I have a few dozen knives that fit the description. Once I feel they are dull, I can bring back very sharp edge using diamond or CrO loaded strops(0.25-0.50micron), several times, then gradually progress to 3mic, 5 mic etc, until the edge needs more serious bevel work, when I take out sharpening stones.
There is zero magic, thin, hard edges are very easy to maintain, and yes when subjected to significant loads they tend to chip, not roll.

Uh-huh.......very impressive, very technical.......so that's why the internet is awash with reports of S30V chipping and very, very few reports of 420HC chipping?

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.

 

[flatface77]

From my hard-won thread-lurking expertise I gathered that S30V's early chipping tendencies were generally blamed on folks not having the heat-treat dialed in early on. Given the seeming toughness of most other PM steels, this would seem to make sense. The early hype on the PM steels (when the first Militarys in CPM440V came out) centered around the ability to cram a ton more alloys into the mix with the process, resulting in increased wear resistance. It's only recently, after refinements in the process, that I've heard anything about increased toughness. My M390 at 60rc is far from brittle & I'm hearing a lot of noise about Elmax being extremely tough for a stainless, despite it's high alloy & carbide content.