question about Steel!

T

trthleshro

Joined
Jan 6, 2011
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So, i looked around the forums looking for an answer but i couldn't really find one. I'm new to the knife scene and and i was wondering if anyone has any information on 5cr steel? from what i've read the CR is referring to chromium, which is used to prevent corrosion. the only problem is that i haven't found any information on the hardness of 5cr or it's blade retention. so i was wondering if anyone might have any further information on this particular steel. Thanks for any help!
 
Sounds like Chinese alphabet soup steel, most are a low grade stainless and IMO not worth the purchase. It would probably be easy to sharpen but to only hold a edge like a plastic butter knife.

What is the knife in question? Brand/maker?

Welcome to BF :)
 
To be a stainless 12% chromium is the minimum. The first 5% Chrome steel for knives I think about is A2. good knife steel but not a stainless.
 
Actually I've seen articles stating 10.5% is the minimum chromium content for an alloy to be considered stainless. (European definition.) In the U.S., 14% is usually considered the minimum amount of chromium required. FYI, D2 has a chromium content of 11%-13% and is generally not considered to be a "true" stainless steel.

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I'm not sure about that steel specifically, however I know that 3cr steel is used in the spyderco bug and equal to about 420, 8cr13Mov is used in the tenacious and roughly equal to aus-8 and 9cr13Mov was used in a spyderco mule team blade and suppose to be the chinese equivalent to 440C, so I would guess 5cr would be somewhere between 420 and aus-8.
 
trthleshro said:
So, i looked around the forums looking for an answer but i couldn't really find one. I'm new to the knife scene and and i was wondering if anyone has any information on 5cr steel? from what i've read the CR is referring to chromium, which is used to prevent corrosion. the only problem is that i haven't found any information on the hardness of 5cr or it's blade retention. so i was wondering if anyone might have any further information on this particular steel. Thanks for any help!
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5 is 10 x the % Carbon. So you are talking an alloy with roughly 0.5% Carbon. In actuality all compositions are ranges. A typical range for the amount of Carbon in such an alloy might be 0.4% - 0.6%, with 0.5% being the midpoint of the range.

There is no one set hardness for an alloy. The hardness depends on how it is heat treated. So unless you have a specific maker in mind and that maker reveals his specification for hardness you really can't say exactly what the hardness is. As an example, most 420HC blades are heat treated to a final hardness of ~55 HRC, but Buck routinely takes theirs to 58 HRC. The difference in edge retention is noticeable.

Since performance is a combination of composition and hardness, it is hard to give an absolute answer, but I agree with the others that you are looking at something with performance on the order of 420 HC or possibly 440A. Certainly no greater edge retention than those and possibly lower.
 
bld522 said:
Actually I've seen articles stating 10.5% is the minimum chromium content for an alloy to be considered stainless. (European definition.) In the U.S., 14% is usually considered the minimum amount of chromium required. FYI, D2 has a chromium content of 11%-13% and is generally not considered to be a "true" stainless steel.

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The percentage that matters is the free chromium not tied up carbides in the austenite. Depending on time & temperature in heat treat, the corrosion resistance can be altered. The 10.5% definition probably comes from the amount you need dissolved at high heat, which I have also seen pegged at about 11%.
 
Now ain't this funny. I've read that a stainless steel must have 13% chromium to be stainless, and that most D2 is at 12.25 to 12.50%. Strange how many different "answers" there are.:eek: Course mine is the correct answer and ya'll can forget about the others!:thumbup:;):)
 
MTguy said:
Spyderco says 12%...
and iv'e seen non cutlery places say 10 or 11%
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In general most of the steels have most of the elements in certain range. It's rather rare to have something at precise level.
On top of that, D2 is very popular and old steel. Almost every steel maker makes it and everyone is adding their flavors and variations.
If you run the D2 steel query on knife steel chart, for now you will get 8 different compositions for well over 40 names.
D2 is a real champion in that area. So, yes, Cr percentage varies from 11-13. There are D2 variations containing elements that aren't even in D2 spec, e.g. Copper, and some D2 variations are missing Vanadium. Still, makers list them as D2.

P.S. It's the amount of free chromium that makes steel stain resistant. Just general % doesn't tell the whole picture. Which is why ZDP-189 with 20% Cr is a lot less stain resistant than bunch of low carbon steels with 14% Cr.
 
Gator97 said:
In general most of the steels have most of the elements in certain range. It's rather rare to have something at precise level.
On top of that, D2 is very popular and old steel. Almost every steel maker makes it and everyone is adding their flavors and variations.
If you run the D2 steel query on knife steel chart, for now you will get 8 different compositions for well over 40 names.
D2 is a real champion in that area. So, yes, Cr percentage varies from 11-13. There are D2 variations containing elements that aren't even in D2 spec, e.g. Copper, and some D2 variations are missing Vanadium. Still, makers list them as D2.

P.S. It's the amount of free chromium that makes steel stain resistant. Just general % doesn't tell the whole picture. Which is why ZDP-189 with 20% Cr is a lot less stain resistant than bunch of low carbon steels with 14% Cr.
Click to expand...

I had no idea there was that many variants of D2, I've seen a few before but iv'e never heard any of the others.

I knew that it was free chromium that determined stain resistance but is there anyway of actually measuring the amount of free Cr in a steel?
 
MTguy said:
Not that I know of. You can do some rough calculations, but nothing precise. Basically, the problem is that different types of carbides form based on HT. There's Cr3C2, there's Cr23C26, Cr7C3, and that's just Chromium carbide. Carbon also forms carbides with other alloying elements, Vanadium, Tungsten, Moly, etc. All have several carbide types. And from what I read/understood depending on annealing/tempering temps formation of carbides changes, also cooling speed and temperature makes difference. In short, way too many variables to account for something.
I was trying to make free Cr calculator for the steel chart, but after few months of research, gave up, too imprecise.
Of course, if someone knows easy method I'll be very happy to hear about it.

Meanwhile, looking at steel composition in molar % or atomic count mode instead of just mass% can give you more realistic picture.
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Wow!! thanks for the responses guys! the knife is a hand me down from my pa and i was thinking of using it for an EDC, primarily for sentimental reasons, however, i've decided to put it away and go for a BK14 or the izula II. Thanks for all the great information. Admittedly some of it is way over my head, so i was wondering if you guys might know of any other links or resources to help me learn more about the different types of steel used in most manufactured knives and the process used in making the blades?
 
trthleshro said:
Wow!! thanks for the responses guys! the knife is a hand me down from my pa and i was thinking of using it for an EDC, primarily for sentimental reasons, however, i've decided to put it away and go for a BK14 or the izula II. Thanks for all the great information. Admittedly some of it is way over my head, so i was wondering if you guys might know of any other links or resources to help me learn more about the different types of steel used in most manufactured knives and the process used in making the blades?
Click to expand...

http://www.bladeforums.com/forums/showthread.php?t=368828 is a good one
 
The Piggyback knife that comes with the Kabar JAB Potbelly and Baconmaker is 5cr13 steel. I am not impressed with the steel in this knife. It will take a hair popping edge, but it won't hold an edge at all. I've got one of the old Outdoor Edge Wedge knives in 420J2 and it will hold an edge much better than the 5cr13.

The Piggyback will throw a decent spark from a ferro rod though. It's good for that with all of its little sharp edges.
 
Gator97 said:
Not that I know of. You can do some rough calculations, but nothing precise. Basically, the problem is that different types of carbides form based on HT. There's Cr3C2, there's Cr23C26, Cr7C3, and that's just Chromium carbide. Carbon also forms carbides with other alloying elements, Vanadium, Tungsten, Moly, etc. All have several carbide types. And from what I read/understood depending on annealing/tempering temps formation of carbides changes, also cooling speed and temperature makes difference. In short, way too many variables to account for something.
I was trying to make free Cr calculator for the steel chart, but after few months of research, gave up, too imprecise.
Of course, if someone knows easy method I'll be very happy to hear about it.

Meanwhile, looking at steel composition in molar % or atomic count mode instead of just mass% can give you more realistic picture.
Click to expand...
have you looked into thermo-calc http://www.calphad.com/thermo_calc.html
 
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