Forge welding with a home made forge???

S

stefanj

Joined
Aug 5, 2007
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What do you use to help guage if you are at the correct temp for forge welding???

I have some of my supplies for my forge, I think I'll go driving and look for some other stuff I need to get it up and going. First thing I'm going to be messing with is a couple of railroad spikes I have and then some spring steel.

I really want to know how to ensure I'm at the correct temp or at least ballpark for forging and also forge welding (I saw some cable that I might grab and have a go at).
 
Some may wonder if I have been kidnapped and replaced with a double, but I wouldn't use a pyrometer or try to work off from specific temperatures when learning how to weld. The color and appearence of the steel are formost in determining the weld not the temperture. Solid state welding can be done over a huge range of tempratures as temperature is not the critical mechanism here, contact of the surfaces for metallic bonding is what it is all about. If you are at 2300F and got oxides in the way and insufficient compression it isn't going to happen no matter how close you watch the temp. Yet the steel can be almost cold and if there is tremendous compression and nothing getting in the way of the metal atoms grabbing each other, it is going to stick.

Color is a good indicator of temp, but the overall appearence of the steel is important. I have walked by students pulling welding heat and told them it wasn't goin to stick just by looking a the steel. Regardless of temp the steel should look clean. The froges atmosphere adjustment should elminate oxides and the steel should appear smooth and "waxy". The flux should flow over it like butter and the bubbles on teh flux should be able to move freelly over the suurface. I like to see the bubbles skitter in a zig zag fashion, it will stick every time for me if they are doign that.

A frosty or crusty look is what you don't want, flakes and paste covering the yellow hot billet will bring you frustration. If you got oxide films or crusty's a pyrometer is no more than decoration in helping you weld it, and somedays the steel is ready at 2100F 0r 2200F while somedays it needs to go to 2350F , soem go to 2400 or better but I have never had a reason to go to white hot for any steel operation. If it starts to spark, it may look fine afterwards but inside the steel it will never be the same.
 
Something just ocurred to me about the sparking thing- there is an exception, when impure raw steel as in a bloom is being refined. There will be a period while consolidating a bloom with welding where that thing will shoot plumes of sparks at surprisingly low temperatures without the steel crumbling or all the adverse effects one would suspect. I figure it is like other refining processes such as the Bessemer process where oxygen is attaking the impurites and excess carbon and putting on a spark show. After the bloom is consolidated into a billet that sparking temperature will rise considerabley and then if you spark it you are burnign the steel and things will crumble. It takes some skill to make bloomery steel and this is one of those skills to be developed, learning the good sparking from the bad sparking is kind of tricky but very important. But sparking in good solid steel is always bad. If you see a guy welding 1095 or O1 with it giving off a white hot sparkler show you don't want to use the steel in anything useful, believe me.
 
Thanks Kevin, I may try to consolidate what I got from my thanksgiving smelt this weekend to see if I have anything useful. I remember some fireworks when Michael McCarthy and I were consolidating the bloom iron at Ashokan, but without your advice I probably would have backed off the heat this weekend had I seen fireworks.

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I use the color of the metal and look of the flux when I weld. Buy a few bars of low carbon steel from your local hardware store and learn to weld on them. It sounds like you are new to forging. The best thing you can do is pace yourself, do basic forging for a while before you try forge welding.

Sunshadow I believe Kevin is talking about the forcing of oxygen though a container of molten cast/pig iron (2-4% carbon) to reduce the carbon content and help remove impurities. I don't believe he is talking about the sparking while the initial smelt is taking place. Sparking while smelting might not mean the flow of air is too high but perhaps the pipe angle is too shallow making an oxidizing fire. I could be wrong though. :o
 
I agree with Kevin about judging steel color and appearance of the steel.
Sounds tricky, but it really is not. You'll know what you're looking for in short order. (No offense to the many fine makers using pyrometers intended:o)

Now for Heat treat ovens/salt pots, by all means go for the digital controllers, pyrometers -- whatever it takes.:thumbup:
 
I was talking about when consolidating the bloom after the smelt. I remember little spark fountains at almost welding heat when we were consolidating the bar at Ashokan while it was still a little squishy, I assume it was little slag pockets or something like that, once the bar didn't feel squishy under the hammer they went away

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sunshadow said:
I was talking about when consolidating the bloom after the smelt. I remember little spark fountains at almost welding heat when we were consolidating the bar at Ashokan while it was still a little squishy, I assume it was little slag pockets or something like that, once the bar didn't feel squishy under the hammer they went away

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I was referring back to the OP's question about forge welding. :)
 
Get a piece of iron wire, the black plumbers wire or an old coat hanger. When you think your billet is hot enough stick the wire into the forge, bring it up to the same color and touch it to the billet. If it sticks your there if not bring it up a bit more. There should be a soak time also so once it sticks you may want to let it sit for another 5 minutes or so.

Chuck
 
sunshadow said:
I was talking about when consolidating the bloom after the smelt. I remember little spark fountains at almost welding heat when we were consolidating the bar at Ashokan while it was still a little squishy, I assume it was little slag pockets or something like that, once the bar didn't feel squishy under the hammer they went away

-Page
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Sorry I read your original post incorrectly. :o

stefanj what fuel will you be using for your forge?
 
Kevin R. Cashen said:
Some may wonder if I have been kidnapped and replaced with a double,
Click to expand...

Yes, and one of them would be me ;)

I've been living by many of the tips you've given us here over the years. Such as using known materials, engineered quenchants and................ known, precise temperatures ;) :D I think I understand your reasoning in this case though. Thanks :thumbup:
 
David Wesner said:
Yes, and one of them would be me ;)

I've been living by many of the tips you've given us here over the years. Such as using known materials, engineered quenchants and................ known, precise temperatures ;) :D I think I understand your reasoning in this case though. Thanks :thumbup:
Click to expand...

I am quite obsessive when it comes to that critical factor in an operation, in heat treating temperature is everything so I want to know what it is and be in control of it within 1 degree if I can. In solid state welding temperture is only a conveninece to make the job easier the critical factor is how close you can get iron atoms to each other. Solid state welding can be done at room temperature if the surfaces are prepared incredibly well or the compression is sufficient to intiate the bond. These critical factors here are not possible for the average shop at room temperature so we throw heat into the mix to make the atoms grabbier and thus possible for us to do it with a tap from hammer. If there is a range of over several hundred degrees that I can weld at I will focus my attention elsewhere as that is well within my feeble eyes ability to control.

You would recognize my style quite well in how I prepare the steel for welding and how I design my forge. All of my steel is carefully ground clean on all mating surfaces before staking up. I get the flux on as soon as it can get gooey and stick, and before heavy oxides can get started. I am very picky about my forge designs as I want to be able to control the atmosphere as rigidly as I could with an oxy-acetylene torch, oxidizing, carburizing or neutral and any degree between each, and it must heat evenly. I prefer certain weights and types of power hammers for welding as well as specific dies. Between each fold I grind both surfaces clean and get the flux on it immediately.

A pyrometer in the welding forge could be good for keeping track of trends and how various materials react to your processes, as long as you kept good notes. It could also be good for a new welder to keep track of the maximum temp you want to go with a particular steel. But I feel that the new welder could be mislead by watching exact temperature instead of the really critical area of surface conditions. Once you are over a certain temperature the forges atmosphere is much more critical than its heat.

On the bloomery thing, I did indeed mean the process of consolidation by forging after the bloom had been removed from the smelter. If you get sparks while smelting, your atmosphere is really messed up in the furnace and you are deconstructing iron, not making it. I do however really like it when I tap the slag deeply and there is a little glob of goo on the end of the rod that immediately turns into a sparkler show when it comes in contact with the outside air; there is only one thing that does that and it ain't pure silica;)
 
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