Powdered Metallurgy steels resists flex breakage. True or false?

marcinek said:
All metal resists flex breakage.
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Until it yields and/or breaks.

I think the theory of PM steels is that they are finer-grained, and this might help a tiny bit with increasing ultimate strength, but I haven't read anything that said this.
 
marcinek said:
By the way...where did you see this and on what knife?
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it's one of survive! knives advertising.

"CPM-20CV is a very high quality martensitic stainless steel, with outstanding corrosion resistance and excellent edge holding. CPM-20CV does lack the impact toughness of CPM-3V but being made with the CPM process, this steel is still very resistant to lateral stress (flex) breakage. Consider CPM-20CV for a very low maintenance, all weather cutting tool. "

bdmicarta made a point.
 
knife chop said:
it's one of survive! knives advertising.

"CPM-20CV is a very high quality martensitic stainless steel, with outstanding corrosion resistance and excellent edge holding. CPM-20CV does lack the impact toughness of CPM-3V but being made with the CPM process, this steel is still very resistant to lateral stress (flex) breakage. Consider CPM-20CV for a very low maintenance, all weather cutting tool. "

bdmicarta made a point.
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Survive KNives advertising shows an S30V knife breaking? You lost me.

And yes, bimicarta did make a point. The same one I did. That, yes, Powdered Metallurgy steels resist flex breakage. Until they break.

So the answer to your question is "true."

Of course jello and peanut brittle resist flex breakage until they break too.
 
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knife chop said:
Is it just marketing? because i've seen an S30V break from flexing.
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Ah yeah blades will break once the flex goes beyond a certain point.....

A lot will depend on the tempering and blade geometry on how far that will be....
 
Ankerson said:
Ah yeah blades will break once the flex goes beyond a certain point.....

A lot will depend on the tempering and blade geometry on how far that will be....
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Will an S7 or CPM 3V with a 10 inch blade with a hardness of 58-60 rc flex the same as a 1055 with a hardness between the high 40's and low 50's. given all had the same length and edge geometry.
 
knife chop said:
Will an S7 or CPM 3V with a 10 inch blade with a hardness of 58-60 rc flex the same as a 1055 with a hardness between the high 40's and low 50's. given all had the same length and edge geometry.
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1055 is a spring steel..... So if that high 40's to low 50's is a spring temper then nope....
 
I think most of the PM steels would have to be bent to an angle where they would be permanently deformed before they would snap.

I base this, of course, on zero experience or research.
So really I just completely wasted your time. It's my little bit of schadenfreude for the day.
 
knife chop said:
Will an S7 or CPM 3V with a 10 inch blade with a hardness of 58-60 rc flex the same as a 1055 with a hardness between the high 40's and low 50's. given all had the same length and edge geometry.
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They will flex exactly the same, to the point where one steel will fail. Because there are multiple possible reasons to fail, I will not say which will fail first in real world.
 
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knife chop said:
Will an S7 or CPM 3V with a 10 inch blade with a hardness of 58-60 rc flex the same as a 1055 with a hardness between the high 40's and low 50's. given all had the same length and edge geometry.
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At the difference in hardness who cares the low hardness 1055 wouldn't hold much of an edge at that rc, while the s7 or cpm 3v will. Are you wanting a pry bar or a knife?
 
knife chop said:
Will an S7 or CPM 3V with a 10 inch blade with a hardness of 58-60 rc flex the same as a 1055 with a hardness between the high 40's and low 50's. given all had the same length and edge geometry.
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We need to first define flex. Flexing is when the blade takes no permanent bend, and returns to true when pushed sideways, ie prying. The S7 and 3V at that hardness will not bend much before breaking. All three will flex the same to the point the 1055 bends, which it will before the other 2. S7 and 3V will flex further than the 1055 (in this example), but once pushed too far, they will not bend much before breaking. The S7 should have a slight edge on the 3v in flexing, but there is so much dependent on how the hardness was reached that it's not easy to make a prediction.
 
I know that 8cr will bend a few times near the tip a little and not break.
Unlike PS that will just snap from what I have seen but at a much higher pressure. Not my own , that is for sure.
 
A good knife will break before it bends, so what are they saying? A broken knife is still usable, a bent one is not.
 
me2 said:
We need to first define flex. Flexing is when the blade takes no permanent bend, and returns to true when pushed sideways, ie prying. The S7 and 3V at that hardness will not bend much before breaking. All three will flex the same to the point the 1055 bends, which it will before the other 2. S7 and 3V will flex further than the 1055 (in this example), but once pushed too far, they will not bend much before breaking. The S7 should have a slight edge on the 3v in flexing, but there is so much dependent on how the hardness was reached that it's not easy to make a prediction.
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And we might add that harder steel, which in most cases is less ductile, is more prone to break on stress risers and inperfections.
 
Yes, but we don't know anything about that, so for the sake of simplicity, I left that part out. I actually thing it would be much more interesting to test all 3 at the same hardness (58 or so), as was said above, the 1055 isn't going to hold much of an edge at 50ish. The Cold Steel Recon Tanto is in that range, so the low hardness might be valid in that case. Come to think of it, I have some CS machetes in that range too and they hold an edge fine. Either way, it would be interesting. At the same hardness, I wouldn't expect S7 to be much better in edge holding than 1055, but my CS machetes will still shave my arm after an afternoon of brush chopping and small tree bucking.
 
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