tips on forge welding

[thingmaker3]

Never-the-less, the glamour of "Damascus steel" lead, in the 19th century, to the development of scientific metallurgy.

I hope you're not refering to Faraday's work - that was dendritic crucible steel.

[tomhw]

I hope you're not refering to Faraday's work - that was dendritic crucible steel.

Inspiration affects technology, it seems.

I am referring to the romantization of "ancient blades" in the 19th century (Byron, Walter Scott, Richard Burton and so many other Victorians and "Romantics" and later Tolkein) that stirred mechanic's interest and resulted in ""Damascus" shotgun barrels, "Damascus" blades, and a real science of metalography and additional force to steel manufacture.

[Dan P.]

http://damascus.free.fr/f_damas/f_hist/perret.htm

[tomhw]

http://damascus.free...hist/perret.htm

Thank you, Dan. You have shown me a large hole in my education. Explorer says that the site (http://207.221.52.114/p29-dama.txt) does not respond. The site (http://damascus.free...hist/perret.htm) is well done and worth a close look.

[tomhw]

Dan, I was so pleased by the site you published in your post that I did not look at your own site. Now I have looked at it. Your site (http://www.didbrookforge.co.uk) is an excellent site and you do beautiful and commendable work. I see that you know your craft and trade.

[Keith Rider]

I tried a couple of welds recently and failed; perhaps you all can help. My objective was to fold over the end of a 1/2" diameter round bar (mild steel) and weld it to itself. I assumed that two round sections would come together in the middle first and that would allow the slag to squeeze out the sides so that it wouldn't get trapped. Would it be better to square it up first so that the surfaces that are coming together are almost flat?

Maybe that has nothing to do with the failure so I'll give you the details and you can tell me where to go next. The stock was once nickel plated, but almost all the plating is gone and replaced with light rust. I heated it gently until the nickel oxidized to green nickel(II) oxide, brushed off the oxide, then reheated to orange to bend. During the bending there was clearly a continuous layer of scale flaking off, so I don't think that any of the nickel still remained on the surface to mess things up.

I bent the last 3" of the bar around and brushed off the scale just before I closed it up and brought the two parts together. Then I spooned on some borax at a dull red heat until the whole joint was coated. Back into the fire . . . this might be where things went wrong. My forge is plenty deep enough to do a deep fire. I've been using about 4" of coke under the work and 2" of coke above -- if I needed to I could get almost 8" of fire under the work, but that would be a coal gobbling monster. Do I need to get every scrap of green coal out of the forge? When I rake fuel on top of the work I try to sort out the green stuff, but there is certainly a little under-coked stuff that gets mixed in. I figure the fuel on top of the work is "down wind" of the steel and isn't as likely to contaminate the weld.

When I pulled out my work it was to bright to see clearly. (I don't mean the sunlight was too bright, the forge is in the shade.) There were sparks shooting out from the time I pulled it out of the fire until I set it down on the anvil. The first three or four licks with the hammer sent liquid slag spraying out like I expected. Does that sound too hot? Next time I'm going to use tinted glasses so that I can get a good look at the surface to see if it is melting.

Have you ever rubbed two pieces together while they are in the fire? Should you be able to feel when they start to stick when you hit the welding temperature? Seems like it might be an instructive experiment.

I can probably get some pictures of the failed welds this weekend. They looked pretty good -- I dressed the doubled part to a square cross-section with a small visible seam. Cold-bending undid the weld entirely, though. Once the first bit of the seam opened up I was able to drive it down on the corner of the anvil and the whole seam opened up. It didn't weld any part of the seam really; the inside was rough gray scale.

Thanks for reading all this and trying to help

[HWHII]

I think your over thinking this. Keep it simple! You might have better luck by starting with a piece of steel that was not plated. When you look into your fire and it is white hot your there. When you bring your metal out of the fire do not hit real hard because not only the flux will squirt out but molten metal will also, then there is nothing left to bond with. Medium blows to start with the set it home.

[ThomasPowers]

Actually we are doing solid phase welding no no molten metal is involved; but you need a clean surface to bond and the glop is borax and metal oxides that are molten.

I'd suggest going with the simplest case as well: get some plain hot rolled mild steel (some cold rolled resists welding unless you grind the surface) I would go with sq stock and gently crown it. Remember to flux it when it's barely to glowing temp in a dark room---*before* it starts to scale much. And keep it well covered in the *top* of the fire and not down near the tuyere. Bring up the temp slow and steadily until the surface looks like butter melting in the sun and *tap* it together. Then wirebrush, flux, reheat and work over the weld with more force.

[Don A]

Also, you might be hitting it too hard initially. A weld is best set with light, firm blows. Especially wth the round surfaces, you could be getting a little slippage intead of stickage (appologies for all the technical lingo).

Best thing to do is to take all of the advice you are given, practice 'til it works, and then do it that way from then on.

[Keith Rider]

Butter melting in the sun . . .

I definitely need to have the shades on next time.

[ddwilson]

It will have more surface to weld if it is square. Also, make sure you flux it before the surfaces to be welded are touching that way both surfaces are clean
before they go together.

[Frank Turley]

On a layback weld, hammer from the closed end toward the open end to help squeeze out the dross. You can also, before hitting, quickly tap the piece on the anvil or shake it in midair to get rid of some dross. I've welded many a basket handle out of four sticks of 5/16" round M.S. I've also done it with 1/4" square. On a forge weld, there is this conception that the surfaces are molten and that is what causes cohesion. I don't think so. The scientists call fire-welding "solid phase", "solid state". or bonding. If it's solid, it is not molten. What IS molten is the flux and scale which have melted together. The old timers said that when the welding heat was ready, that the metal was "pastey." (school room paste?).

[Francis Trez Cole]

I think you are a little to hot is should be at the first stage with a very few sparks. I would not work in shades Univex makes a shade called vermillion which is a good way to go to protect your eyes. I personally do 2 or 3 light hits reflux bring back up to heat 2 or 3 harder hits and flux and bring back up to heat hit to shape. You want a good saturating heat all the metal should be the same heat do not be afraid to turn the piece over in the fire to heat all sides . The other problem you may be having is using plated stock. I hot a hold of some stock that sparks at yellow.

[evfreek]

Are you able to test for stickyness with a coat hanger? The feeling is unmistakeable.

Also, forge welds are very weak to prying them down the seam. They seem to be much stronger when the bar is pulled or twisted. This was how a marginally welded pair of tongs behaved. The weld could survive being bent double, but it could be popped apart with a sharp chisel hammered against the seam.

[Keith Rider]

evfreek -- I have an O/A torch and a stick welder and can make welds with either one that will not peel apart. I wouldn't be happy with a weld that could be pryed apart at the seam because I know I can do better than that. If it needed to look forge-welded and I needed it done today I'd do it with the O/A then heat it up in the forge and dress the weld to match the rest of the piece.

I'll try the coat hanger stickyness test tomorrow. Give us some details of your observations for comparison.

[Frank Turley]

I don't claim to be a metallurgist, but I have been forge welding (among other things) for 49 years. A forge weld can be weaker than an oxy or arc weld because of grain growth and slag inclusions along the line of the weld. Then why do it? A forge weld is forgable, whereas a gas or arc weld is not always forgable. There is NO PUDDLE in forge welding. In fusion welding with a puddle, the metal is molten and when it freezes, you get a different crystalline structure (dendritic) than that of the parent material. Because of this different structure, a forged fusion weld may crack or come apart, even though the heat may look "right" to the smith. Another reason for learning forge welding is that when a "branch" is welded onto a "stem" you get a "vanishing point" where the two come together. This gives an organic appearance that is hard to achieve with fusion welding.

I don't mind performing an occasional arc or oxy weld, but I have run into problems with them. One is the heat affected zone. Another is warpage on the project. There is also time consumed in veeing out, lining up, clamping, multiple passes, and cleaning the "gradoo" when finished. Then, if wanting it to look forged, perhaps re-heating and wire brushing.

The photo example shows forge welded leaves and branch to stem. In a three week class, a student will fagot weld two used horseshoes together and bend the result into a horseshoe shape. We call it the "horseshoe sandwich."

When we forge weld, we think about the old cowboy saying, "I don't care how weak it is, as long as it's strong enough!"

[ThomasPowers]

They used to forge weld up the main drive shafts for naval vessels from *lots* of pieces of real wrought iron; so it seems a good weld can be done.

One thing that helps strengthen a weld is forging it while *hot*.

If you want to know the fiddly details "Solid Phase Welding" Tylecote covers them.

[Rich Hale]

Lets not overlook the plating he speaks of,,i douibt it is a nickel plate but if it is oh well...It is most likely galvanized and there is a lot of information on this sight about the haards of heating it up or the by product it gives off if it is ground off. Just do not heat galvanied metals is the best thing to remember,,if you are not sure it is or not,,just pass it up and get metla that there is no question that is not plated with anything.

[Keith Rider]

Nickel plate and zinc plate are easy to tell apart. Zinc comes right off in an acid bath and makes a white oxide when it is heated in air. Nickel is acid resistant and makes a green oxide. These used to be old ring-stands from a chemistry lab, which is why they nickel plated them. The acid vapor would take the galvinizing right off but it takes about 20 years to go through the nickel. This stock was nickel plated about 40 years ago and used in a lab with very bad ventilation and worse humiditiy control, so there isn't very much nickel left.

I've gotten some good tips here so I'll give it another try this weekend.

[Frosty]

Hold off trying to weld rounds, you have to have really good hammer control to drive the pieces center to center or they'll want to slip sideways and shear any weldment. Square or flats are much easier to forge weld till you have the process down.

My most successful method is to match the halves of the join then clean them, preferably sand or file them shiny, lightly flux, cold and drive/wire/tack weld/etc. them into contact. Then I bring them to welding heat slowly in a reducing fire, a gas forge with a little pinkish dragon's breath or high in a coal forge out of the air blast, higher still in a charcoal forge. In any case the principle is the same, oxygen is bad, burn it all before it gets to your project. Once the piece is to heat, watery or sweating heat is a good visible cue, the steel will look like the surface is wet or sweaty with shades of yellow flickering across/through it. If it's soaked long enough this temp is to the center it's good to go. If you're welding thin stock hold it slightly off the anvil so the anvil doesn't draw the heat and give it a solid but gentle dead blow. If the hammer bounces you've given it too much pepper, All you want to do is drive the two halves close enough together they start exchanging electrons and that's it, forge/diffusion welded.

Then clean the joint, reflux, reheat and refine the weld, do this at welding heat at least the first couple times.

Of course that's just the way I do it. <grin>

Frosty The Lucky.

[ThomasPowers]

Never pull the piece out of the fire if you don't have your hammer in your hand. raise it while turning to the anvil and start your downward stroke so piece, anvil and hammer all come together at once.

Now the better you get, the "looser" you can be doing welds; but if you start having issues---going back to first principles generally helps!

[Keith Rider]

I got a couple of welds to stick yesterday, but couldn't get past the tack weld stage. Frustrating because I assumed that I was home free once everthing was tacked. Some of my proto-welds were pretty strong, but they all came apart after enough beating. The weld surfaces were a smooth, uniform gray color with little round shiny spots where the tack welds were holding.
My best luck was with pieces that I heated up while I was rubbing them together. When they got sticky I reached into the fire and squeezed them together with tongs to get the tack weld. Two welding heats later the welds looked good from the outside, but failed the cold bend test.
Same results with some rebar that I tried. The only difference is that rebar leaves a distinctive mark when you fumble the tongs and drop a piece then try to pick it up barehanded.

[Big__Joe]

Hello guys,

 

I'm a student from the Nation School of Blacksmithing (Hereford, England), I'm doing a project on firewelding, where i explore all the different types of fire welding and see if i can find any tips on tricks/ shortcuts on my route. Any advice or tips and tricks you have pick up on your way would be gratefully taken on board.

 

Thanks, Joe.

 

[Rich Hale]

Joe in this forum there has been alot of threads over along time about this...Rather than just havin to type them here,,You can look throught this foruim..go back a long way and look at them..That will give you ideas from many folks.

[Dan P.]

Hi Joe,
Fire welding is bound to the laws of physics.
Know the physics, know how to fire weld.
A simple balance of iron, oxygen and carbon.
It's really as simple as that.
If you need elaboration, ask any of the tutors up there at Hereford.