GTAW *TIG) welding limitations

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skillgannon

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Apr 27, 2009
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I am a welder and a AWS certified welding inspector. I am setting up my shop and have plans of working on blades as well many other projects. I have a Esab caddy Tig 2200 that will allow me to program a pulse down to 400 times a second. This offers me a lot of control and very low heat inputs. I had hoped to use this for 3 things.

(1) Adding tool steel such as CPM M4 (others may be a much better fit) to cutting edges of tools such as axes.

(2) Adding overlay of stainless or high nickel alloy. This could eliminate the need for a forge weld, create an interesting etch pattern or add performance or corrosion resistance.

(3) Allow the addition of mixed alloy "Mokume" type alloys to be added to a blade or tool post heat treat.

I would assume most of these techniques would require the use of high nickel alloy filler metal. I have a good working knowledge of metal working but would definitely not call my self even a good armchair metallurgist. Are there reasons why addition based techniques cannot be used effectively in a basic shop setting?

Also does anyone else use welding in any stages of knife making other the welding on guards?
 
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The HAZ might cause structural problems when you go to heat treat. Like grain boundaries. I'm just guessing but let's see what the more metallurgically minded people say. Good to see another CWI on here.
 
None of those tasks are done by TIG welding on knives. It may sound feasible to a welder, but sounds fairly impossible to a metallurgist or damascus maker. Forge welding is the only really feasible method of laminating steel for knife use. Mokume is a eutectic welding process, and a TIG would be terrible.

Welding is used to tack together and seal up billets for forge welding. It is used to weld a re-bar handle on a damascus billet. It is used to add tangs to damascus blades. It is used in forming some guards and other fancy hardware. It is used a lot in making elaborate sword guards and hardware. It is used to make metal sheaths for knives and swords.
 
I am assuming that this is because of a cast grain structure?

I am sorry if these are some very obvious questions. I am doing a bit of self teaching at all of your expense.:)

If this is the case could the piece be refined by forging?
 
Some people like Bill Burke will TIG weld bolsters to kitchen blades. The reason you forge weld is because that is how the process works. It doesn't really have anything to do with cast vs sintered/PM grain structure. To TIG weld like that, you would have to get the entire surface area of every layer of steel to completely weld to the entire surface area of every piece is was touching.
 
I guess I should clarify that in no way am I talking about welding anything into thin blades.

My first concept piece is an axe head with a premium steel welded into the blade. I would then weld overlay with a pattern of nickel alloy such as some types of INCO and Hastelloy (Sometimes it is possible to find decent quantities of leftovers from jobs. Unless a company has a permanent shop in the area they often dump these because of lost documentation.) and if it didn't look to busy maybe use some sort of Mokume for the poll. I would then grind/machine and etch the surface. If forging were needed or possible it could definitely be done.

Really the only non aesthetic thing would be adding tool steel for an edge. I think with proper welding procedures that should not be a problem though maybe not with super alloys. When it comes to this would anyone have recommendations for both a steel that could be used and a filler metal to join them?

I guess I have also thought about doing some sort of overlay welding on difficult to forge weld steels to make billets that could be forged. It could be interesting at least.
 
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At a minimum, you risk making that welded transition between the bit and body of the axe really ugly when you etch it,
skillgannon said:
I guess I should clarify that in no way am I talking about welding anything into thin blades.

My first concept piece is an axe head with a premium steel welded into the blade. I would then weld overlay with a pattern of nickel alloy such as some types of INCO and Hastelloy (Sometimes it is possible to find decent quantities of leftovers from jobs. Unless a company has a permanent shop in the area they often dump these because of lost documentation.) and if it didn't look to busy maybe use some sort of Mokume for the poll. I would then grind/machine and etch the surface. If forging were needed or possible it could definitely be done.

Really the only non aesthetic thing would be adding tool steel for an edge. I think with proper welding procedures that should not be a problem though maybe not with super alloys.

I guess I have also thought about doing some sort of overlay welding on difficult to forge weld steels to make billets that could be forged. It could be interesting at least.
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Depending on the welding characteristics of the tool steel bit, I think 1.) may work.

I dont see why 2) would not work with some trial and error and not welding too close to the edge. However forge welding would probably be easier/ less time intensive.

I dont have any real experience with mokume, so I dont have any input on 3)
 
Kevin Powers said:
The HAZ might cause structural problems when you go to heat treat. Like grain boundaries. I'm just guessing but let's see what the more metallurgically minded people say. Good to see another CWI on here.
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There are a few of us on here.

I don't want to discourage anyone from trying something, but from my experience, welding hardenable steels is pretty tricky. What would the carbon equivalence look like for something like M4?!?!?!?! Is it done, yes. Have I seen anyone do it? No. You may want to dig into laser welding. That is one way the edges of bi-metal saw blades are attached. Not that you would be doing it, but it could provide some insight into how to start trying with TIG.
 
This is sort of like making your own Dymondwood. You start with a 6" piece of 1X4" maple, and laminate a 1X4X6" piece of walnut on it. Then you sand the second piece to .030". Repeat 50 times with alternating layers and then sand the original board to .030". Then you have it stabilized. You now have a 50 layer block of unknown quality handle material. OR ... you can buy a block of Dymondwood for $10.

Of your ideas, the only one that would have any possibility of working would be welding two pieces of metal together to make an axe billet. You would still have to deal with the HT on an axe head with an M4 bit and a mild steel body.
 
I could see surfacing a steel billet with stainless giving off a San Mai appearance but that would be a lot of surfacing welds to get thickness you'd want. You would likely have a bunch of cracking. Shoot I might try it for an craps and giggles after the holidays. I'm guessing the distortion from surfacing, inconsistent metal deposition and penetration will leave me with an unusable knife blade, but who knows until it's tried right?
 
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