olydemon

Forge welding failure.... too hot?

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So I've managed to forge weld a few things with ok results (other than totally corrupting my forge floor with flux). The other night I tried to FW a fire poker for the first time and ended up failing miserably. It seemed everything was going pretty well at the beginning. I did hit it on the side and I think it split a little, but it was holding together. I got it bent up and thought I would put another twist in it. This is where it all went bad. I just felt the piece tear rather than twist. I thought I could maybe save it by welding (cheating I know)... but I decided to just break it off since the poker was probably too long anyways, and I figure I can try it again. Inspecting the failed end, I could see a bunch of copper on it. Long story short, a while back I melted some copper by accident and once in a while i get it transferred to my parts, often with cool results so I don't generally worry about it. I was able to rip apart a section of the weld by hand so Obviously it wasn't totally right. You can see in the photo showing the split, there is copper down inside between the layers. That contamination aside (I already have a plan to keep the next one off the floor), I'm more concerned about the torn stock. Is this from overheating? Basically did I burn it up? The only other time I've had my material looking like this was trying to make a Rail Spike hawks twice..  (last 3 photos). On these failures I split the eye then it cracked drifting it out. The failed area looked exactly like the fire poker failure.

 

So it this material crumbling and cracking a result of over heating?

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I'm not 100% sure, but I think the issue is the copper.  I spilled some in my forge a couple of years ago and had difficulty welding up damascus billets until I re-cast the floor of the forge.

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The breakage definitely looks like burning.

Are you using a gas forge, or solid fuel?

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Just now, JHCC said:

The breakage definitely looks like burning.

Are you using a gas forge, or solid fuel?

Propane. Single burner, 1" wool lining with hard fire brick floor. 

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copper from a while ago isnt causing the problem.   I forge copper and bronze often, and I dont have troubles welding, You got it way too hot

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Steve, what do you think would be causing that coppery discoloration?

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There can be an issue with molten copper infiltrating along grain boundaries; while I have forged a lot of copper in the forge; I don't allow it to melt and puddle on the floor. May I commend to your attention Intergranular Attack of Steel by Molten Copper published by the AWS.  Look at the pictures of the cracks in it.

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1 hour ago, JHCC said:

 what do you think would be causing that coppery discoloration?

I agree it looks like copper, but I also assume he was smart enough to removed the visable copper from his fire and not leave it in there for later.

The photo looks like a smelting iron bloom that turned to cast iron, so honestly bad photography was my first guess

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Copper will contaminate your welds every time. It is a well known fact!!!

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Olydemon says, "a while back I melted some copper by accident and once in a while i get it transferred to my parts, often with cool results so I don't generally worry about it."

-edit- OlyDemon the poker looks like you were off to a good start. Possibly do the desired twisting on the handle prior to the forge welding of the poker on the next try. The twisting action, in itself, is one of the most harsh tests of/on a forge welded area. 

Edited by Adun Clebr
added a sentence

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The sulfur in the copper causes red short at the temps we forge weld at and the molten copper infuses itself between the layers and contaminates the weld. The red short explains the crumbling and you can see the copper between the welds. Forging copper is different than melting copper and forging it doesn't leave any residue left over spilling molten copper does. Take a crucible and put it in the forge and melt it and then leave it in the forge and then try to forge weld.

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1 hour ago, Steve Sells said:

I agree it looks like copper, but I also assume he was smart enough to removed the visable copper from his fire and not leave it in there for later.

The photo looks like a smelting iron bloom that turned to cast iron, so honestly bad photography was my first guess

You are correct that there must still be some copper in the forge. Ive tried scraping it out and it hasnt been much of a problem untill recently trying to forge weld. I wonder if the borax caused the copper to pool up in the slurry the borax creates? I always seem to regret using borax for a few weeks after. I only have 1 forge, but am working in a 2 burner one I would like to have setup to FW in.

1 hour ago, ThomasPowers said:

There can be an issue with molten copper infiltrating along grain boundaries; while I have forged a lot of copper in the forge; I don't allow it to melt and puddle on the floor. May I commend to your attention Intergranular Attack of Steel by Molten Copper published by the AWS.  Look at the pictures of the cracks in it.

Thats interesting I will have to give that a read. 

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1 hour ago, BLDSMTH said:

Copper will contaminate your welds every time. It is a well known fact!!!

A well known fact?  

The first recorded use of mokume gane was by Denbei Shoami (1651-1728) who lived and worked in Japan. The husband and wife team of Eugene Michael Pijanowski and Hiroko Sato Pijanowski brought Mokume Gane to the United States in the early 1970s. They learned the technique from ninth generation metalsmith Norio Tamagawa. Today, Mokume Gane jewelry, flatware, hollowware and art objects are created by layering precious and semi-precious metals such as Gold, Platinum, Palladium, Sterling Silver and Copper. The layers are bonded and deformed by rolling, forging, and twisting. 

Did you read Thomas Powers post and reference? 

 

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Metallic copper does not contain sulfur. Propane does not contain sulfur.  Refractories don't, generally, contain sulfur.  Where would the sulfur in the copper come from?

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2 hours ago, ThomasPowers said:

 Intergranular Attack of Steel by Molten Copper published by the AWS.  Look at the pictures of the cracks in it.

Awesome stuff Mr. Powers, thanks for posting this. I learned from that study.

Back to the breaking issue; I may be looking at the pictures wrong, but I see 1) an obvious break, and 2) a separated forge weld on the poker tip (and the visual copperish hue).

The break- this part had to be sparkling/burning, right? This was covered above that it looks like it got too hot. It may have survived as a linear shaft until the twist got it.

The separated forge weld- just practice some more. Like I said, it looks like a good start on the poker. Personally, I ended up cutting a dozen pieces of 10"-12" long, 1/8" thick, 1" wide mild steel stock as forge welding test "coupons". I paired them up & practiced forge welding them together. I am not a professional forge welder, but this practice made my fourth (or fifth) poker actually be a user. 

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While I'm not sure about the cracking (looks to me that either copper or too high of heat could be the culprit), the weld almost certainly failed from the copper. Although, as it has been pointed out, it is not correct to say that that copper will always make a weld fail, it will certainly make it very difficult to weld a mild steel once infiltrated. It is important to note that while there do exist some steel allows that contain copper and can be forge welded, they likely do not have nearly as much copper, and must be very clean and welded in a near zero oxygen environment. I'd be willing to say that if you lost enough copper in your forge to do this, it's probably time to give it a proper clean :)

 

Best of luck, 

-NelsonR

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7 hours ago, BLDSMTH said:

The sulfur in the copper causes red short at the temps we forge weld at and the molten copper infuses itself between the layers and contaminates the weld. The red short explains the crumbling and you can see the copper between the welds. Forging copper is different than melting copper and forging it doesn't leave any residue left over spilling molten copper does. Take a crucible and put it in the forge and melt it and then leave it in the forge and then try to forge weld.

So does this mean, even If I kept the piece off the floor, the fumes inside the forge would still contaminate my piece?

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I saw a forge welding demo where an onlooker threw a penny in the forge to mess with the demonstrator, the demonstrator was peaved but continued his demo and on first try successfully forge welded a bunch of electrician's pliers, wire strippers together to make a knife for a retired electrician. I know this because the demo was in my brick forge at a hammer-in I hosted. The demonstrator who did the forge welding said it's not the penny that causes problems, it's the fire management for forge welding that counts for a successful weld. I saw, so therefore I believe.

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I bet the piece being welded was not in contact with molten copper which is what seems to be the problem causer.

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6 hours ago, Adun Clebr said:

Awesome stuff Mr. Powers, thanks for posting this. I learned from that study.

Back to the breaking issue; I may be looking at the pictures wrong, but I see 1) an obvious break, and 2) a separated forge weld on the poker tip (and the visual copperish hue).

The break- this part had to be sparkling/burning, right? This was covered above that it looks like it got too hot. It may have survived as a linear shaft until the twist got it.

The separated forge weld- just practice some more. Like I said, it looks like a good start on the poker. Personally, I ended up cutting a dozen pieces of 10"-12" long, 1/8" thick, 1" wide mild steel stock as forge welding test "coupons". I paired them up & practiced forge welding them together. I am not a professional forge welder, but this practice made my fourth (or fifth) poker actually be a user. 

The part was not sparkling at all. It was a bright yellow.

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Which is way too hot for some alloys.  I forget do we know for sure what this piece was made from?

I've cottage cheesed H-13 before thinking that as a high temp alloy it might work better in the yellow....

Also what was the ambient light like in the forge?

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40 minutes ago, ThomasPowers said:

I bet the piece being welded was not in contact with molten copper which is what seems to be the problem causer.

I don't follow.  you said it was NOT in contact. Did you mean to say that it was in contact? It so, you are probably right. As stated before I've never had an issue with what bits of copper are left in the forge from accidentally letting a piece melt once.

6 minutes ago, ThomasPowers said:

Which is way too hot for some alloys.  I forget do we know for sure what this piece was made from?

I've cottage cheesed H-13 before thinking that as a high temp alloy it might work better in the yellow....

Also what was the ambient light like in the forge?

Thanks for the time to reply, and hopefully help me learn.

It was just plain mild steel from a local steel supplier, not home improvement store.. I would guess A36 if I remember correct.

Ambient light? Pretty bright I would say. I often have issues when its too dark seeing other things. Most all of these photos are pretty true to my shop lighting.

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10 hours ago, jeremy k said:

I saw a forge welding demo where an onlooker threw a penny in the forge to mess with the demonstrator, the demonstrator was peaved but continued his demo and on first try successfully forge welded a bunch of electrician's pliers, wire strippers together to make a knife for a retired electrician. I know this because the demo was in my brick forge at a hammer-in I hosted. The demonstrator who did the forge welding said it's not the penny that causes problems, it's the fire management for forge welding that counts for a successful weld. I saw, so therefore I believe.

I wonder if it depends on what year of penny is thrown in.  IIRC, pennies were 95% copper until 1984 when they changed to 2% copper.

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I was referring to the examples where people have successfully welded with copper present in the forge.  I would bet those examples did not have contact with molten copper.

If the ambient light is bright then the piece is a lot hotter than it would look under lower light conditions.  I have this clearly shown when I'm teaching outside and the sun is setting; when it's dusk the metal looks a lot hotter than when it's full sun; but you can sure tell the difference under the hammer!

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