Forge weld flux

[ofafeather]

Thanks guys, I like it when someone asks a question I need to know the answer to.

Happy to oblige! ;)

[ofafeather]

I don't remove "excess" flux, some people do.

Generally there is not enough time to rig a hold down and it's time to borrow help if you would need one.

Of course if your flat piece is 12" thick then there probably is enough time! (or to put it otherwise "it depends")

Preheating the tooling seems to help particularly in the winter

Thanks for the input, again. Guess I'll have to wait for the wife to help me forge weld separate pieces (except when I'm working on that 12" thick stock!

One thing worth mentioning about the preheating of tooling: DO NOT heat excessively!! You could possibly ruin the tempering/hardness of an anvil, etc. (basically don't get it too hot to touch).

Good point. Will be careful of that.

[pkrankow]

Thanks for the input, again. Guess I'll have to wait for the wife to help me forge weld separate pieces (except when I'm working on that 12" thick stock!

Called "drop the tongs" because it is what it sounds like. You position, drop the tongs from the hammer hand and use the hammer. Practice on cold till you stop feeling silly, and start feeling silly again. Some say you can press a weld with a stick to set, then back to the fire. I agree, but have a hard time welding due to lack of experience, and not nearly enough forge time.

Phil

[Yance]

ofafeather;

Do yourself a HUGE favor and get a can of either E-Z Weld or Crescent "anti borax" flux.

I had been using borax and getting good results, then tried E-Z Weld when welding thin stock to thick and had GREAT results.

Since both were formulated for use in gas forges, you can weld at a lower heat so you're not on the ragged edge of burning your steel. You can "stick" the workpieces in the fire so be careful about alignment. (don't ask how I know )

[ofafeather]

Called "drop the tongs" because it is what it sounds like. You position, drop the tongs from the hammer hand and use the hammer. Practice on cold till you stop feeling silly, and start feeling silly again. Some say you can press a weld with a stick to set, then back to the fire. I agree, but have a hard time welding due to lack of experience, and not nearly enough forge time.

Phil

Ahhh yes. Seems I had 'heard' that expression on the forum. Now it makes sense.

ofafeather;

Do yourself a HUGE favor and get a can of either E-Z Weld or Crescent "anti borax" flux.

I had been using borax and getting good results, then tried E-Z Weld when welding thin stock to thick and had GREAT results.

Since both were formulated for use in gas forges, you can weld at a lower heat so you're not on the ragged edge of burning your steel. You can "stick" the workpieces in the fire so be careful about alignment. (don't ask how I know )

I'll look into that. Thanks!

Do forge welded items show a seem?

[pkrankow]

Do forge welded items show a seem?

Under certain circumstances, polished and etched, the seam is often plainly visible. Under more common circumstances it depends on the quality of the hammer work, completeness of the weld and lack of a cold shut at the seam.
Phil

[Frank Turley]

Boy Howdy! We could write a book on this subject. I've been forge welding for 47 years.

In an everyday coal forge situation with mild steel, you have two welding heats. One is a sweating heat with no sparks being emitted. The other is when you may notice a few incipient sparks, which may be OK. What you don't want is a HUGE shower of sparks, because then you're oxidizing and burning the metal. It is best to weld at the sweating heat, so named because the surface slag or cinder looks runny. At a sweating heat, you may lose time in terms of a few hammer licks, but there is less chance of burning the metal. The steel is at the incipient burning range when the sparks appear. I've taken a half dozen sweating heats over the same area without adversely affecting the steel.

The sparks, by the way, are the bright ones that burst about a foot or so from the metal. They are actually particles
of metal separating from the parent bar, so there is a weight loss, though minimal. We see the same kind of sparks when oxy welding.

We may need a chemist to deal with the next question. Present day materials scientists call forge welding or fire welding, "solid phase welding," "solid state welding," or "bonding." I don't think that the surface of the scarfs or fagots are molten steel. I don't think that you are going to blow out any molten iron or steel. The metal is in a solid state. It is what the old timers called "pasty" for lack of a better term. When fire welding, you DO want to get rid of the surface molten slag. This molten material is a compound of the flux and scale, now melted together.

Most smiths will either shake the pieces of metal in midair or rap them against the anvil before laying them on the anvil to weld. You can see the surface slop falling, which is good. On small pieces, they are occasionally wire brushed before welding, but most often they are shaken or rapped.

The reason for using RELATIVELY light blows when starting a weld is to prevent "shear." You're trying to keep the material from sliding apart which would occur with a hard blow. The few light licks to start the weld allow for cohesion instead of shear. THEN you can hit harder, once the cohesion takes place.

Regarding seams, which we call "shuts," you can sometimes get rid of them with another welding heat and by using light, rapid blows.

http://www.turleyforge.com Granddaddy of Blacksmith Schools

[Svarttrost]

Thanks Mr. Turley, lots of new useful information there for all of us.

[ofafeather]

Thanks Mr. Turley, lots of new useful information there for all of us.

My thanks, too, Frank! Great post.

[brianbrazealblacksmith]

On 7/16/2010 at 9:16 AM, Frank Turley said:

Boy Howdy! We could write a book on this subject. I've been forge welding for 47 years.
 

Great explanation Mr. Turley. I was only 3 years old when you started forge welding. I just wanted to emphasize the "shear" you spoke of. That is one of the most important things when forge welding. You need to hit the material into itself and keep your blows square to the material so it doesn't "shear" or slide out of square when you are using only a hand hammer and anvil.

[John B]

A properly formed scarf helps to stop the shear/slide of the pieces when you place them prior to the first light blows

[SoCal Dave]

Great post Frank. I haven't see your posts lately and it's good to have your advise and knowledge. As usual, you add that experience of 50+ years of blacksmithing to our discussions which is so needed and enjoyed by me. Stay healthy OLD wise one.

[eric sprado]

When I served my shoeing apprenticeship near Fort Riley Kansas in the sixties our first handmade shoe was made of Baling wire!!! You twisted lots of wire together in the vice and started welding. After the shoe was made you left strands of wire hanging off one heel to show what you had done. In that spot we used white sand from the Kaw River for flux. I have used Twenty Mule Team Borax or Anhydrous Borax(whatever that means) for flux ever since I left home. Works for me.Frank's description of the process, as usual, was right on the money. All I need to do now is put the word arteeest in my head and try to use my ****** horseshoeing skills for something pretty!! Goodluck with your welding. Nobody said anything about RELAXING. Relaxing mind and body are essential to forge welding!!

[ofafeather]

ofafeather;

Do yourself a HUGE favor and get a can of either E-Z Weld or Crescent "anti borax" flux.

I had been using borax and getting good results, then tried E-Z Weld when welding thin stock to thick and had GREAT results.

Since both were formulated for use in gas forges, you can weld at a lower heat so you're not on the ragged edge of burning your steel. You can "stick" the workpieces in the fire so be careful about alignment. (don't ask how I know )

Yance, is there a difference between Crescent and E-Z Weld?

[Don A]

ofafeather,

This is some great advice that has been offered so far.

The only thing I can add is to practice on some scrap so you don't have to deal with the frustration of trying to learn on a project you've already spent some time on and are afraid of messing it up.

I would also recommend doing a few faggot welds, just to get the feel for what you're doing.

Get a piece of square stock about 3/8" to 1/2", and leave it long enough that you won't need tongs.

On the first heat, come back an inch or two from the tip and hot-cut it half way through. While you still have heat, wire brush it real good, then fold it over, tap it closed, and flux it. You might want to bring it up to red heat and brush & flux it one more time... some do, some don't.

Now, go in for your welding heat (see Mr. Turleys commentary above). Be patient and relax. This, I think, is one of our biggest problems with forge welding. We turn it into this nerve-racking procedure and we tend to rush and fumble. Just relax and let it come up slow. Don't push too much air, but don't let it lay in the fire indefinitely. And as Frank said, don't just study the color... study the appearance. When you see that surface begin to look like butter melting on a piece of cornbread, you know your getting close.

Relax as you go to the anvil. Stay calm and those misplaced shearing blows won't be so frequent. I can't offer any more about setting and finishing the weld than has been said above, but work those practice pieces until you can consistantly make 'em stick, then work on making that line disappear, as well as the end of the scarf (I still need a lotta work in that department).

Join two pieces, and when they're cool, put 'em in your vise and try to tear them apart. Take advantage of your practice on the scrap. Know what you're doing so that when you start on that piece you have already invested an hour in, you'll have the confidence to finish it to your satisfaction.

Good luck,

Don

[ofafeather]

On 8/4/2010 at 12:43 PM, Don A said:

ofafeather,

This is some great advice that has been offered so far

 

Don, good suggestion. I was about to go out to the smithy and do just that. I was going to try your way and also try a ring/loop weld with the same material, scarfing the tip and making a loop at the end of the stock. Anyone doing this with a gas forge? I know some won't get up to welding heat, though I am assured that the one I have (Chili Forge Tabasco Model) will do just fine.

 

[pete46]

Is it possible, on the 1st.,weld'n blow to just use the vise instead?
(to avoid shear )

[ofafeather]

Okay. Trying a faggot weld a la John B's suggestion using 3/8 square stock. How long does it usually take to get up to welding heat? I am wearing #2 green glasses for this and can see the flux running like heck but have yet to see the surface get "slippery". I've pulled it out a couple times thinking that might be it but know go. Also, looks like it might be losing some mass and there is some slag that I can't brush off even with the heavy brush. Am I on the right track or doing something wrong? Using Borax for flux. It seems to melt on contact with the hot metal.

[ThomasPowers]

Depends on the forge and how you are running it.

If the flux gets "crunchy" it's too oxidized to do it's job.

One tip: I like to build up a big welding fire and then stop all air and stick the piece in to do it's "warming up"; then take it out and wirebrush and flux and back in the fire in just a couple of seconds and then start adding air to get to welding temp.

[John B]

Okay. Trying a faggot weld a la John B's suggestion using 3/8 square stock. How long does it usually take to get up to welding heat? I am wearing #2 green glasses for this and can see the flux running like heck but have yet to see the surface get "slippery". I've pulled it out a couple times thinking that might be it but know go. Also, looks like it might be losing some mass and there is some slag that I can't brush off even with the heavy brush. Am I on the right track or doing something wrong? Using Borax for flux. It seems to melt on contact with the hot metal.

Can't take credit for Don A's suggestion, however no scarf is necessary for the practice faggot weld as it closes into itself, just start from the doubled over end and be gentle with it 'til you get it stuck, if you are in a solid fuel fire, you should not need flux.

[ofafeather]

Oops! Sorry Don and John. Need to give credit where it's due. Thanks for the ideas, gentlemen.

Here's where I stand. I use a propane forge and made a few attempts using 1/2" square mild steel and borax. I heated the stock and put a notch in it with the hardy ~ 1/2 way through, wire brush and bent it over. I put flux on it with partially liquifies upon contact. I tried a few different ways of heating, bringing it to red, wire brush and flux then heat or just bringing it up to temp in one heat. I can't tell if I'm getting it hot enough or not. It's at bright yellow or white, hard to tell and definitely hard to look at with naked eyes. The flux clearly bubbles, runs and looks like sweat. Don't know if that means the metal is getting to that liquid/solid state or not. I made a few attempts at the same weld on one side. Finally the piece fell of where it was notched so I drew that end out a bit to use as a handle and started on the other end. Same process. Made a couple of attempts but no luck. Any suggestions?

As far as oxidizing or reducing in a propane forge, I do have a choke plate and can somewhat control the air intake. I usually run 3/4 to 7/8 open on the choke. Also, could I be using too much flux? I have a mess of slag on the bottom plate of the forge. Glad I planned ahead and only use this one for welding. Also, whats the difference in fluxes made for forge welding with gas forges? Do they really help?

[Don A]

One thing comes to mind...

Are you using hot-rolled steel (A-36)?

If so, you will notice that it comes from the supplier coated with dark gray or black mill scale.

Try hitting it with the grinder/sander/file/rasp until you have bare steel in the weld area.

I know it seems like that stuff should scale up and brush away on the first heat, but it can prove to be troublesome.

And I use coal, so I'm completely in the dark when it comes to a gasser.

Stay with it,

Don

[ofafeather]

Don, Good point. Will try that. I have a couple of other plans in mind, too. I don't think this would make a good empirical study on problem solving because I don't really have the patience to try every variable one at a time. Here's the gist, though.

Close the choke a bit to allow less air therefore less oxydizing fire

Preheat the forge to a higher temp, heat the stock with a lower blast for even heating and again less O2

Use less flux - made a mess and really eats into the bottom plate. Very glad to have that extra plate to protect the forge

Maybe try with no flux - not sure if this can be done in a gas forge but I should be able to see the change in the metal surface better

Prep the surface of the weld area

I'll see if any of that makes a difference. Also considering getting a flux like Z-weld made for gas forges.

[pkrankow]

There was a series of pictures linked from another thread looking at the dragon's breath to help determine the reducing/oxidizing nature of the forge.
http://www.spaco.org/Blacksmithing/PipeForge/PipeForgeAndPropane.htm
its near the bottom of the page, and the dragon's breath should look the same whether blown or atmospheric.
Phil

[ofafeather]

There was a series of pictures linked from another thread looking at the dragon's breath to help determine the reducing/oxidizing nature of the forge.
http://www.spaco.org/Blacksmithing/PipeForge/PipeForgeAndPropane.htm
its near the bottom of the page, and the dragon's breath should look the same whether blown or atmospheric.
Phil

Phil,

Thanks for the link. I remember coming across that last year when I was researching forges. It is pretty interesting. The forge I have is atmospheric (Venturi) so I can only control air flow with the choke plate. I think someone with more experience with this than me could probably give us more specifics but I'm guessing that closing the choke a bit, especially at higher PSI will help. Typically I would say that the dragon's breath on my forge looks like the center picture but I will look more closely today when I go out. In my first experiments with welding yesterday I was amazed at how much material disappeared. Is that a sure sign of oxydizing? I wonder. I've just been reading a fascinating post on fluxes on the MAF. http://www.metalartistforum.com/forum/showthread.php?tid=5907 Don't know if there is a policy on linking to other forums and I apologize if there is.