Newbie Question - Single Bevel Laminated steel vs Case hardening

N

Nost

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Dec 8, 2020
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Completely new here but after a fair bit of research I havn't been able to find a clear answer.

Generally case hardening wouldn't be used for knives and I completely understand why. Ive come to the forums to see if anyone here has tried this, or is able to provide some guidance.

Where the blade / tool is single beveled (eg a marking knife) would case hardening be an effective way to have both a hard edge as well as making the tool easy to sharpen, similar to what would be achieved by using laminated steel
 
Case hardening is a surface treatment, so you wouldn't be able to sharpen the blade and still have a hard edge.
 
Im not sure i understand you, but maybe it is how i explained it.

I've added a quick image of what im thinking, this would be a cross section of the metal. Red is the case hardening, brown is the soft metal, and blue is the section that has been ground off leaving a sharp hardened edge. Does that make sense?

Screen-Shot-2020-12-09-at-2-31-11-pm.png
 
I suppose that could work, but you have to make sure to keep the cutting edge in the case hardened part. You also have a hard top surface, whereas in a laminate the mild steel up there still has all the toughness of mild steel.
As i understand the metallurgy, the laminate also allows you to use other alloying elements that you can't use in case hardening, with case hardening you're limited to whatever is in the mild steel plus carbon

Edit: how does case hardening affect grain structure? That could have an effect too
 
Ohh, I see what you're asking now. I suppose that might work...but I'll let others who would know better give answers...
 
How hard of a finish does case hardening produce, I imagine it varies steel to steel somewhat.
 
Does case hardening effect the metal to a consistent depth?
Would 1 or 2 sharpenings still be in the hardened metal even if both sides were sharpened? Just curious.
 
I saw a video where a maker put a railroad spike knife in what I'd call a crucible full of carbon. I'm not sure what depth of hardness it reaches.

I'm not sure the benefits for your idea would outweigh the negatives (increased steps to case harden, soft core, different wear rates etc).
 
Since even a medium carbon steel will harden, it seems pointless to use mild steel and case harden it. Do it in anything from 5160 , O-1, 1950, W1/2. All those are cheap and easily procured.
 
Case hardening can be controlled fairly well in terms of thickness. Thicker cases need more time and more time equals more money. There are case hardening compounds for home use, but they would take a lot of experimenting to get good repeatable results I think.

I toyed with this idea a few years ago after being asked to find a way to save a load of parts. They were supposed to be nitrided but weren't. Nitriding was/is more expensive. Carburizing was more affordable, but lead to distortions that the client couldn't tolerate. These were small threaded parts than needed to stay the same in terms of thread dimensions. For knives that wouldn't be a problem.

Sharpening would be an issue. The buyer has to know how and why to sharpen a certain way or the knife will eventually just have a soft edge.

If you have a pile of A36 or 1018 steel that's free, or even better a pile of 8620 steel, and you just want to make knives, there are places that will do carburizing at a reasonable price. It's a batch type operation, so one blade won't be economical. You could try the home compounds and maybe get a system worked out. It's far from impossible or unworkable. You'll have to decide if it's worth the cost.
 
Nost said:
Im not sure i understand you, but maybe it is how i explained it.

I've added a quick image of what im thinking, this would be a cross section of the metal. Red is the case hardening, brown is the soft metal, and blue is the section that has been ground off leaving a sharp hardened edge. Does that make sense?

Screen-Shot-2020-12-09-at-2-31-11-pm.png
Click to expand...
Why not like this ? First cut steel in shape and then case harden .........
t4HjDlu.png
 
That will only work until it gets sharpened. The issue with case hardened blades is they are basically ruined once sharpened.

A piece of 1075, 1080, 1084, 1095, O-1, A-2, W2 can be found everywhere in the world and the cost is less than getting a blade case hardened.
If the OP, Nost, had filled out his profile I am sure someone would have gladly given him what he needs.
 
The problem is, case hardening is generally REALLY thin.
My experience with this is really limited to black powder flintlock rifles, not blades. But when hardening the frizen (the little plate the flint hits) you might end up re-hardening after a couple dozen shots, to a couple hundred depending on how your piece hardens..
It's pretty unpredictable in a home shop, at least in my experience.
 
Stacy E. Apelt - Bladesmith said:
That will only work until it gets sharpened. The issue with case hardened blades is they are basically ruined once sharpened.

A piece of 1075, 1080, 1084, 1095, O-1, A-2, W2 can be found everywhere in the world and the cost is less than getting a blade case hardened.
If the OP, Nost, had filled out his profile I am sure someone would have gladly given him what he needs.
Click to expand...

Why use good steel for a knife when you can make it in the hard way?

Because it is fun:)
 
I disagree, but that is just my opinion.
Personally, I don't consider it fun if you spend a lot of time and effort to get a low quality product from lesser quality materials, when you could have a good product from good materials simpler and cheaper.
 
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