A thought about knifemaking

Ugaldie

Ugaldie

Joined
Feb 27, 2013
Messages
344
Hello,

I have been learning about knifemaking in this forum for a while I have a question about steel treatment.

In the eternal discussion between stainless vs carbon steel, the disadvantage of carbon steel is (obviously) it's more prone to corrosion. So, has anybody tried chemical surface treatments on those kind of steels?

I potentially see a big advantage in surface treatments like nitriding. You can combine it with a proper heat treatment and you can take advantage of both.

About nitriding:
http://en.wikipedia.org/wiki/Nitriding
 
DLC (diamond like coating) is the best surface treatment but it's expensive (£50 per blade). 76hrc, slipperier than teflon, huge range of colours, incredibly durable. It was developed for Formula 1 engine internals.
 
When you nitride you can control how deep you go into the material. You treat the bevel and the egde. It's a surface treatment, not a coating.

You have also more treatments like carbonitrurating or phosphating.
 
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No knife maker has the money to invest in that kind of equipment. And far too expensive if the only purpose is to prevent a little rust. If you are making a knife that requires high corrosion resistance, why wouldn't you use stainless?
 
The nitriding processes use very high temperatures that may interfere with heat treatment.
Industrial hard chrome is wonderful for blades. Puma used it on many fixed blade knives.
 
So, has anyone here used DLC and how does it work, affect the edge, etc,etc?

I would really like to have a 9260 katana coated and see if it is forever sharp, myself.

Larry
Tinkerer
 
Aaron, those treatments give to the steel more than only corrosion resistance. You can take soft stainless steel and boost its capabilities for example, carbonitriding it. With this treatment you add carbon and nitrogen to the surface, making it harder and more corrosion resistant while the core continues having the initial mechanical properties.

So you can have a hard knife with a tought core.

You don't have to buy those equipment they are common industrial processes, you can send your knifes to somewere to heat treat them.
 
Bill, I agree with you, some treatments use high temperatures and you have to choose to heat treat or to surface treat them.

But I think you could use nitriding process after hardening the steel, instead of tempering it. Plasma nitriding temperatures vary from 260 to 600 Celsius.
 
What seems to be escaping the discussion is that these treatments will only protect and harden the sides. The edge will be exposed steel and the hardness of the edge will be whatever the HT made it. No surface treatment will make the edge last longer.

Would a DLC coated katana cut smoother...maybe ( I really don't know, but it may have a lower coefficient of friction).
Would a DLC coated katana cut better, as far as the edge is concerned, and stay sharp longer - NO.
Would it be worth it - Absolutely Not!
 
I have nickel and/or chrome plated blades and while it does protect the sides you still have to expose the bevel and edge to sharpen so you still have to take care of the blade like it is carbon steel.
 
Wouldn't it be cheaper to just take proper care of your non-stanless blades?
 
It seems we aren't getting the idea, a surface treatment is not a coating.

As the name says you treat all the steel, egde and bevel included. There are treatments that can go 1mm or more into steel.

You can give a treatment to a low carbon tough steel, achieving a high carbon, very hard (high HRC) and more corrosion resistance surface, making all the piece more fatigue resistant and not changing core steel's properties.

Those procceses have been in metalurgical industry for a long time. You don't have to buy the machines, there are factories focused only in surface treatments. You can send them your knifes to surface treat in the same way some knifemakers send their pieces to heat treating factories.

The point is, I think knifemakers could benefit adding those processes to their repertory, maybe combining them with heat treatment.
 
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From your link "The nitrogen then diffuses onto the surface of the material creating a nitride layer.".

"Onto" not into. Even if it is "into" what happens when you sharpen a knife or repair an edge after common incidents? You have to remove material. My reading of this is that the process doesn't change the properties of the steel, it interacts with the steel to create a more durable surface. Is this surface so hard that normal sharpening equipment won't be effective?

The core of my issue is that there are a lot of fantastic knife steels available. Both stainless and non-stainless that are tough, with great edge-holding and corrosion resistant enough for even abusive knife use. With that material available, what is the real benefit to this extra expense? Why would I choose a lesser steel when I can so easily use steel that is properly and appropriately heat treated? In that same vein, I'm not seeing the advantage of a soft tough core with a hard "shell" when you can have high toughness and edge holding with the right properly heat treated steel.
 
There is anything wrong in experimenting new working procedures. Think about what others thought about the first man who experimented adding cryogenic treatment to the traditional steel heat treatment.
 
While I think the idea is not without its merit (or possibilities), I think that for MOST knifemakers, and perhaps even more so the customers to whom this extra cost will be passed down, the cost to benefit ratio is just too high on the cost side, with very little benefit to show for it, when all things are considered.

One way I look at it is as follows: There are many stain resistant steels now available that are close enough to having properties of carbon's edge refinement AND sharpenability, and would be much cheaper to machine and properly heat treat (including any necessary upgrades to equipment) vs. getting equipped for surface treating a low, mid, or high carbon steel blade to that point that you might expect anywhere close to comparable results.
Even contracting either the surface treating or the heat treating, I'd hazard to guess that heat treating (even with an initially more expensive steel) would come out cheaper. Especially if you're talking something as expesive as DLC treatment.

For those who might be "purist" on the carbon steel side of things, I think you're still going to be hard pressed to find a great deal of benefit for surface treatments. It may require less maintenance, or be more easily maintained, but does that convenience justify the price increase? It definitely has a coolness and uniqueness factor, but keeping your blades clean and dry and oiled cost next to nothing, and should be part of your routine regardless, including for stainLESS knives.

As for the idea of being able to use a lower carbon (i.e., cheaper) steel and impart a little more strength, durabilty to it, I think you're fighting a losing battle, which would be much more effieciently fought by just using a higher grade of steel in the first place.

Now, I will give one example that we use here at work with promotes the benefit of surface treatment:
We've recently started using a coating (looks like some kind of nitride coating to me? Gold in color? I don't know...) for our radiusing tool bits in our large lathe. These tool bits are about 4" long and use to grind large radii into the ends of very large backup rolls. Before the coating, IIRC, we were getting about 2 or 3 rolls per bit, and the bit was getting red hot.
Now it stays cool and we get about 10 or 12 rolls per bit, on a good day.
Now, it does cost a few hundred bucks per coated bit, but we are saving money vs. breaking the cheaper ones more often, and they're also being used on very expensive rolls that are used to make millions of dollars worth of steel. So in THAT instance, the cost is easily justified.
 
First at all thank you for those instructive answers

I come from the industrial world and I thought those processes would help knifemaking in the same way they helped in its days in general industry. I agree with you the cost benefit of using those treatments is very small when we are speaking on general knife use.

I'm used to all kind of tool manteinance, including knives. I work in a plant near the sea and we have corrosive environment here due to our idustrial process. Here all the machines and tools have to be stainless or surface treated and you have to do their manteinance very periodically. Unless you do it well they corrode, also some kind of "stainless steel". I was shoked when I started working here and I saw surface corrosion in my 12c27 knife.

I have started this threat with my experience in mind. I know not all the people has my needs.

A, and sorry for my English. It's my third language and I haven't used it for a while.
 
Why not just make an all-stainless san mai type blade, soft stainless sides and a fine grained stainless core? There are many kitchen knives made that way now. I think that if you use a nice carbon tool steel for a blade, then carbo-nitride it or whatever other treatment may be suitable, you'll find that the treatment has changed the cutting and sharpening characteristics completely from what you wanted in a carbon edge, anyway.

I don't know that there is any alloy or steel treatment that offers an answer to high corrosion resistance and fine-edge stability at knife hardnesses. Stainlesses always seem to to either edge-roll or chip to some degree, especially when ground thin. I would think nitriding would significantly embrittle your edge.

With carbon chef knives, a forced patina can do wonders for easy maintenance. Also, I find that pattern weld with a pretty deep etch is easy to maintain compared to say, straight 01.

I think you'll find that the world of steels and heat treating in custom knives is one of those areas where the necessary compromises between various aspects of blade performance have already been highly explored and pretty sharply defined. Not to say there's nothing new possible, but every few years we see a new material touted as "the ultimate" in knife performance across the board. There is always an Achilles' heel. For instance, SM-100 is hot right now but I've seen hard questions with few answers about it's low Young's Modulus, and difficulty to work with...

Hell, maybe take a look at INFI...
 
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