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3Cr13 Schrade Choppers

Posted by Chum 
3Cr13 Schrade Choppers
March 02, 2013 11:22PM
Here are three new relatively cheap, Chinese, choppers from Schrade. The Bolo Machete has a nice design imho, but it is hard to tell how the two axes would perform just by looking at the pictures. The phrase "Extreme Survival" is pretty funny.

The main point of interest for me is the steel. Cliff mentioned this steel to me recently as a good choice for a "hard use" stainless steel. It is very similar to 420j2, which Cliff mentions in his latest video "Kershaw Junkyard Dog: regrind (some talk about steels and optimal geometry)

Someone correct me if I'm wrong (still trying to make sense of this process,) but 3Cr13 is a martensitic stainless steel, and should be difficult to heat treat poorly, right?

Well, enough butchering of cutlery science from me. Here are the choppers in question...

Schrade Bolo Machete
Specifications
Blade Length: 14" (35.5 cm)
Blade Steel: Titanium Coated 3Cr13 Stainless
Overall Length: 21.3" (54 cm)
Handle Material: Safe-T-Grip
Sheath Material: Nylon with Carry Pouches for a Fire Steel and Sharpening Stone
Weight: 1 lb. 10.8 oz.
Price: $39.95
*** apologies for the gymongous pictures ***






Schrade Extreme Survival Axe 17"
Specifications
Blade Length: 3.4" (8.6 cm)
Blade Steel: Titanium Coated 3Cr13 Stainless
Overall Length: 17.0" (43.2 cm)
Handle Material: Lightly Textured K10
Sheath Material: Nylon
Weight: 1 lb. 15.2 oz.
Price: $41.95



Schrade Extreme Survival Axe 15.6"
Specifications
Blade Length: 3.8" (9.6 cm)
Blade Steel: Titanium Coated 3Cr13 Stainless
Overall Length: 15.6" (39.6 cm)
Handle Material: Thermoplastic Rubber, Black
Sheath Material: Hard Plastic
Weight: 1 lb. 7.1 oz.
Price: $35.95

Re: 3Cr13 Schrade Choppers
March 03, 2013 09:35AM
Quote
Chum
Someone correct me if I'm wrong (still trying to make sense of this process,) but 3Cr13 is a martensitic stainless steel, and should be difficult to heat treat poorly, right?

3Cr13 is a common steel for valve plates, the HT is :

-soak at 1050 C
-oil quench
-temper at 250 C

This will produce 52 HRC with a decent amount of retained austenite. For a knife, in general you would benefit from having a higher martensite %, and reducing the tempering temperature a little bit and so you would add a cold treatment and end up with 54-56 HRC, ideally with 95% martensite. This would produce a very tough blade which was also nice to sharpen, easy to grind in case you hit something hard (could be filed) and still would get a crisp edge easily.

The problem with those knives is that because they are extremely cheap it is unlikely that a lot of effort would be put into hardening them and thus you could see QA/slop problems, the only way to know is to check. I know there were reports of others breaking and if you are snapping that steel something has gone seriously wrong.



Re: 3Cr13 Schrade Choppers
March 03, 2013 10:22AM
I use X46Cr14, which is about the same kind of steel, on many knives, and I never felt it was an inferior steel at all. It may not be as homogeneous as some higher grade steels, but it's pretty tough, easy to sharpen, takes and keeps a good edge. The Hudson Bay Camp Knife Cliff bought from me is made from X50CrMoV15, and upgraded version of X46Cr14, and as far as I can tell, he reviews it at decent at least. Same with the very wide knife I made for Jörg Sprave (I traded it against a custom "slingshoot", as he pronounces).

In my experience, it's a steel very convenient to HT, and I've never messed up a quench (unlike carbon steels, and even 12C27). But factory HT is not the same. A friend working in a professionnal knives factory brought out a "cheese knife" (large and thick knives made to cut round of cheese, french and swiss style), and it broke like glass after just half a dozen batonning hits. Don't remember if I found a cause to it. Could be too high soak temp. or too long soak time, too low or too short tempering, etc... There are so many ways to screw up HT in a large scale process.

But I don't do cryogenic HT on my blades, it's too expensive for knives I sell realtively cheap. But I may soon get some money, and then I could consider buying a liquid nitrogen bottle (or something similar, whatever is the more stable and easier to refill) to do my own cryogenic HT in-house... if possible!
Re: 3Cr13 Schrade Choppers
March 03, 2013 10:23AM
Quote
CliffStamp
3Cr13 is a common steel for valve plates, the HT is :

-soak at 1050 C
-oil quench
-temper at 250 C

This will produce 52 HRC with a decent amount of retained austenite. For a knife, in general you would benefit from having a higher martensite %, and reducing the tempering temperature a little bit and so you would add a cold treatment and end up with 54-56 HRC, ideally with 95% martensite. This would produce a very tough blade which was also nice to sharpen, easy to grind in case you hit something hard (could be filed) and still would get a crisp edge easily.

Thanks Cliff... Could you give the same step by step breakdown of the heat treat for 3Cr13 at 54-56 HRC and 95% martensite, por favor?



Quote
CliffStamp
The problem with those knives is that because they are extremely cheap it is unlikely that a lot of effort would be put into hardening them and thus you could see QA/slop problems, the only way to know is to check. I know there were reports of others breaking and if you are snapping that steel something has gone seriously wrong.

It doesn't sound like getting this steel too 54-56 HRC at 95% martensite would make the heat treat too difficult, and if it isn't you would think some company would do just that and market that steel appropriately. In general people are going to prefer a stainless over a non-stainless steel if they thought it could handle heavy work.



On a bit of a tangent... would it be feasible and/or beneficial for a knife maker using martensitic stainless steel to do Magnetic Particle Inspection (MPI) on their knives before they send them to a customer? I don't see mass produced knives going through that process, but a custom maker could include that in their price... if it wasn't too expensive.
Re: 3Cr13 Schrade Choppers
March 03, 2013 10:32AM
I remember you talking about the stainless steels you have been using Mad, and I agree with you. If the steel can take the abuse why not use it as oppose to a non-stainless?

My Ontario SP50 is made out of 5160 and is 53-55 HRC. It keeps an edge just fine. The edge is barely effected by chopping into hardwoods. I think the perception is that knives HAVE to be 57 HRC or higher, and stainless steel just isn't tough enough enough to handle heavy wood processing.
me2
Re: 3Cr13 Schrade Choppers
March 03, 2013 10:36AM
I've done my share of mag particle. I just wonder what you'd be looking for by using it. It gets dirt simple to fairly complicated, depending on application. The most basic equipment is reasonable, a couple to a few hundred dollars.
Re: 3Cr13 Schrade Choppers
March 03, 2013 10:47AM
Quote
me2
I just wonder what you'd be looking for by using it.

That's the question I have. I don't know much about it, but it would be interesting to find out if it could benefit a knifemaker.
me2
Re: 3Cr13 Schrade Choppers
March 03, 2013 10:55AM
There is some use, but it limited. Magp is a method to detect surface and shallow subsurface flaws, 1/16" to maybe 1/8" deep. Do a google search and you'll see some really good pictures of cracks. Another method might be die penetrant. Its even cheaper but more limited. I think busse used mag for their s7 after some of the splits in the scrap yard line. Bob Engnath used die penetrant to test his clay hardened blades for cracks.
Re: 3Cr13 Schrade Choppers
March 03, 2013 04:08PM
Quote
Chum

Thanks Cliff... Could you give the same step by step breakdown of the heat treat for 3Cr13 at 54-56 HRC and 95% martensite, por favor?


-550°C, equalize
-900°C, equalize
-soak at 1050 C
-oil/plate quench
-cold treatment
-temper at 180 C
-water quench
-cold treatment
-temper at 180 C

The exact temperature/times would need to be altered depending on the exact furnace tolerances. The only difference this is from the standard valve treatment is :

-addition of two preheat's to minimize soak time (prevent grain growth)
-cold treatment/tempering cycles

However this is a very expensive cycle and isn't going to be practical for a inexpensive knife so a more sensible approach would be :

-soak at 1035 C
-oil/plate quench
-temper at 180 C

The lower soak temperature is used to put less carbon in solution and prevent grain growth as you will need more time at temperature. The less alloy in solution will reduce retained austenite. This will likely reduce the hardness by 2-4 points over the previous cycle but is a fraction of the cost and will also produce a very high martensite percentage, likely between 10-15% retained austenite,
Re: 3Cr13 Schrade Choppers
March 03, 2013 05:14PM
Do you know what kind of cost difference there would be between thoe two heat treatments?
Re: 3Cr13 Schrade Choppers
March 03, 2013 05:17PM
It would depend on who is doing it, what they have available, what they usually harden, how many you wanted hardened, etc. . Your best bet if you were actually going to do it small scale, like 1-2 knives would be to find a maker close to you and drop by their shop.
Re: 3Cr13 Schrade Choppers
March 04, 2013 05:14AM
Frankly, I see only one way to properly do the two pre-heat steps, and it is a three zone belt furnace. Anything involving taking the blade from one furnace to another immediatly nullifies the interest of the whole process, as knife blades are so thin they cool extremely rapidly. Only factories producing high performance components have interest in having such an expensive device being made. I don't see how a knifemaker not working for the Qataris could justify it. But if there is a company heat-treating pieces with a similar HT cycle, it's absolutely nothing for them to add your blade (if it fits in dimensions) to a bunch.
Re: 3Cr13 Schrade Choppers
March 04, 2013 11:19AM
To give some background, this extensive HT comes from Landes, his perspective is that once you move into the realm of charging high prices for your knives then you should be doing high priced work in all areas. Do not for example put a $150 blade finish on a knife which has a $25 heat treatment (unless it is an art knife).

If you look at the cost of knives now it is trivial to find even introductory makers (working 1-3 years) charging $250 for a small knife and $500 for a large fixed blade or folder. The same makers will be open about the fact it doesn't take close to half a day for them to make the knife so you have :

-base materials
-abrasives + power
-one days labor

These also are on very simply and easy to grind steels, AEB-L, O1, etc. . There is no way you would wear out a belt on a knife on those steels, so the abrasive costs are very low. Thus put more money into the HT, use this to refine the geometry and increase performance. There is a cost though, Roman's knives are not cheap, but then again just look at what else people pay for and the actual raw cost.

Note as well if you sink more money into materials you can avoid HT costs, for example the extremely high alloy steels have a much simpler HT which is similar to :

-soak very hot
-quench
-temper very high

There is no cold treatment, you can not easily over soak them (the grain is pinned by all the carbides), and the multiple high tempers (which are very inexpensive) will transform martensite to a very high percentage.

This used to be the way people would HT ATS-34 for example, the downside is that you lose :

-corrosion resistance
-impact toughness
-ease of sharpening and very high sharpness edge retention

However if you have customers who do not care that much about them and just want a knife which stays fairly dull for a long time then that is the ideal way because it will maximize wear resistance. A lot of nice hunters were made and appreciate like that for example, but it is one of the reasons why a lot of stainless steel gets a reputation for being difficult to sharpen.
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