Forge Welding

[primtechsmith]

What is the best advice you can give someone who is attempting to forge weld? What about the Fire, air flow, flux, etc....

Peyton

[bridgtonblacksmith]

First of all, you will need to have a clean fire. Make sure that there is no clinker in your fire pot and that the tuyere is clear to allow air to flow up through the fire.


The first suggestion that I would have is to try forge welding a single piece, NOT a "drop the tongs" type of weld. It is much easier to focus on the technique of welding without having the awkward problems of aligning the pieces before they cool too much. Simply take a scrap piece of bar stock, cut HALFWAY through and fold the end back over itself (kind of like a tight "V"), and try with that. You also want to make sure that you heat both sides thoroughly, wire brush all slag away, apply plently of flux, and get the piece up to a good white heat (just about where it starts to sparkle and burn). Once there, remove from the fire and quickly get it to the anvil and tap the 2 halves together. It doesn't take a lot of force. Forge welding DOES NOT have to be pounded together, you just have to make the surfaces come in contact. As a matter of reference, I saw a demo where a smith showed us that you can forge weld a bar using a wooden mallet. Not a lot of force. If it doesn't stick the first time, put it back in the fire, heat, wire brush, and try again.

Also, ALWAYS think safety. Wear the correct protective gear, and be aware that forge welding typically involves flying sparks/slag.

Hope this helps,

[Ian]

I agree with the above post, a clean fire helps a lot. Here in England a lot of older Smiths don't actually use any flux, just a very clean fire. A new fire is still burning off a lot of the impurities from the coal, and you can use this time to pile up coal around the fire to coke up a little for when you start to forge weld. A simple billet is what I started with but a folded over weld, like you'd find on the end of a fire poker is a good place to start. If you have access to a welder you can make a billet of several pieces stacked on top on each other and tack weld a bead on each end to hold then together and to put them onto a handle so your not faffing around with tong juggling. Make sure the metal is clean before you stack it. Make sure that you heat the metal evenly (turning it in the fire so each side is in the blast) and allow it to 'soak' for long enough that the metal is at the right heat all the way through. Everyone has their own ideas of the right time to try to weld, but if the metal is sparking then its burning, your looking for the point when the steel has a sheen to it like melted butter does on toast. Others will say as soon as you see the first spark, it's all relative. Time and experience are the best teachers here. I'd also recommend reading ANYTHING written by Dr Jim Hrisoulas as well. He's an acknowledged master of pattern welding and posts on this forum under the moniker of JPH. He doesn't tack weld his billets together but wraps them with wire to keep them together, I'm not that clever yet
Someone told me the only way to get really good at forge welding is to try and do at least one everytime you light up the forge. Good advice.
Let us know how you get on.

p.s. A safety note: The fire and metal will potentially get VERY bright so staring into/at it for any length of time is not recommended. There are tinted glasses on the market, but I don't know the in's and out's of them.

[ThomasPowers]

1: don't try to weld car spring to itself as a starter project

2: this is when safety glasses and a face shield and a leather apron, long sleeves and gloves are mandatory! When the flux flies it's unpleasent to have your skin be the landing spot.

3: Deep Fire and bring up the heat slowly---you don't want an oxidizing fire! This also helps get the center to welding heat as well as the outside.

4: Don't slam the pieces with the hammer you want more of a firm tap to set the weld---some folks demo this by welding a billet using a hammer handle to set the weld.

5: have everything to hand *before* the piece comes out of the fire and don't set the piece on the anvil but hold it slightly over it and let the hammer push it onto the anvil---helps keep the piece hot

And as my original instructor used to yell at me---"DON'T LOOK AT IT! HIT IT!"

Thomas

[HWooldridge]

I have to confess that I have had more frustration and failure at forge welding than anything else I have attempted in blacksmithing. Some people say heat treating is hard but it's a cake walk from my perspective compared to making a good looking forge weld. Over the years, I have arrived at some things that work for me. A few mirror previous comments, while others may just be my take on it.

The absence of clinker is important because it restricts air flow. I typically make a fresh fire and get all of the upsetting out of the way early - by that time, the fire is about right to weld. I bring the blast up pretty quickly at first, so I have a yellow-white fire to my eyes. When the piece(s) are red, I remove and flux. I know some people flux in the fire but that does not work for me and I use EZ Weld or any commercial equivalent - I don't like plain borax. I put the pieces back in and cover with coke to the point I can see the tips. In addition, (depending on stock size) I leave about 3-5 inches in the fire so the rest of the stock is plenty hot and doesn't suck heat from the weld area.

I leave the blast pretty high until the pieces start to blend with the fire's color and then throttle way back. Depending on stock size, I let the pieces soak for some seconds with almost no blast. The fire does not cool immediately so the pieces tend to continue heating. At this point, I usually see a few small sparks coming out of the top of the fire so it's time to remove and go to hammering. The weld typically goes "spat!" and sticks. If it does, I attempt to finish the joint - if not, I let the pieces cool completely and then grind away the resulting scale to bare metal. I have rarely been able to make something stick on subsequent tries without cleaning but by not beating the H@#$ out of it, I can usually save the upset. If it sticks but gets cold, I take another welding heat and finish the joint - because I have had a couple welds break from forging at too low a temp.

Another thing I began doing to make the joints look better on butt welds is to feather the scarf tip to a point - rather than a chisel edge. I used to upset and draw the tip to run straight across the stock for the full width but noticed I would often get a nick or cold shut mark, which would sometimes peel if I was twisting through the weld area. I began experimenting and eventually just starting drawing a point. For me, this does not burn as easily and also blends better to the opposite piece. Using this technique, I can sometimes finish a weld in one heat and make the weld line disappear - although it can be a benefit to let it show (that way, you can show the client that it was really forge welded). The "point scarf" also works well on faggot welds when you are making a closed loop. I sometimes do a public demo that involves welding 1/4 square in a loop and then cutting apart to make a fork. This method leaves a nice transition at the union without causing a cold shut.

I do not make knives so do not pattern weld - all of my work is typically sticking bits of steel together to make ornamental stuff. I'm sure the pattern welding folks have different techniques.

[Glenn]

If you have ever gas welded, you use heat to make a puddle from one metal, a puddle from the other metal, and blend or mix the puddles to form the weld. Welding rod is used to fill and make the metal surface level when it cools.

Forge welding is much the same, you heat and liquify the surface of the metal and then blend or mix the liquids. As suggested above, bumping the metals to mix the liquid is all that is needed. Giving it a good whack will result in a spectactular spray of sparks, the liquid being squirted across the shop and leaving no liquid to mix together and form a weld.

To mix dirt, scale, and other junk and impurities in the liquid metal will make the weld weaker, or not to weld at all. You have to start with the cleanest metals you can in order to have the best welds you can. To see just how good the weld is, you have to destroy it, bend it till failure, cut it in half. and look at the weld line, and the entrie weld section.

To make good welds, make a LOT of welds, destroy a lot of welds, and make a lot more welds. But keep the first forge weld that "took" so you can see where it all started and you can show others that is not magic, but working till you get it right.

[HWooldridge]

Glenn,

Interesting you bring up the gas welding because it reminded me of something I do occasionally. Once in a while, I have a little production job that requires welding 1/4" square together into a cross pattern. I take the two pieces, tack with a TIG, then hold with tongs and heat lightly with an O/A torch (usually a cutting head set on neutral flame). When it's red, I flux with gas welding flux, heat to bright yellow white and smack it together with the hammer. This does not make a classic forge weld but the pieces do stick quite well and won't pull apart.

[GobblerForge]

I can only tell you what I was tought. Start with making chain links. It's a good basic project and the ones that work, you can use for tong reign clamps. Start with six to eight inches of 1/4 to 3/8 round. Heat and bend into a U and scarf the ends on the edge of the anvil. Bend the scarfs over each other and get the welding area shaped together. Now heat to a bright orange and brush the weld area continuously as it cools until the scale stops forming. Bright red. Now the steel is clean and ready for flux. For most steels and wrought iron, 20 mule team borax will work fine for flux. Before the steel cools any more, sprinkle flux liberaly over the whole weld area. The flux melts and coats the steel but does not burn off until a temp. above your goal. This helps keep oxygen from touching the steel and forming scale that can't be welded through. Return to the fire and slowly heat until the wet glassy sheen can be seen. I like to heat my links on end with the weld down so the heat is blown through the scarf, heating both halves evenly. At weld temp. your work time is limited to only a few hammer strokes so work quickly. Bring to the anvil and strike. The flux and debris should be squished ot sealing the weld. I like to do a little shaping then do a second weld to be sure.
To test your weld, clamp the link in the vice at the bottom cold. Put a bar through the link and twist 90 degrees. If the weld was poor it will open up.
I have a friend that works at Timken Research. He tested one of my links from 3/8 round mild. It streach tested to over 7000 lbs. until it tore open.
Gobbler

[Ellen]

I can't add anything to what has been said about forge welding in coal fires.

But, I do all of my forge welds in my propane forge. Things that work for me: make sure your forge gets hot enough. This often requires 2" of kaowool and a good coat of ITC. Burners must be properly adjusted, a slightly reducing flame works best for me. If you are welding two separate pieces together, tie them together with some wire to hold them in alignment. Cleanliness is most important. 20 Mule Team is a fine flux, but I often use Sure Weld or EZ Weld. Wire brush, flux, heat, wire brush, flux, and heat to welding heat. Watch the flux amount, it will eat your kaowool. A ceramic kiln shelf for a floor helps a lot.

Leave the work in the gas forge till it is the same color as the interior of the forge. That is as hot as it is going to get. Remove quickly and lightly tap to "set" the weld, tap quickly to finish the weld. Speed is highly important as is a minimum of force. When working the welded area later in your project keep it good and hot, close to a welding heat.

Make lots of welds. It's just like arc welding. Your welds look and hold terrible till you burn a few pounds of rod.

[Ian]

Hi folks,
there's been a lot of discussion on forge welding and I posted that my first ever was just a simple billet, so here are two pictures of it for folks to look at. Nothing earth shattering, but it's just to show that if even complete novices like myself can do it then there's hope for anyone!

enjoy

[Rantalin]

Thats a great looking weld Ian, and I like the paper towel background.

[Ian]

LOL, first thing I could grab that wouldn't bounce the flash back at the camera ;)

[Rantalin]

Thats actually a really good idea. I have white counter tops, and it bounces the flash back like a mirror.