Forge welding

[MetalMuncher]

Hello. I'm new here and am just getting to know my way around. I need some help with my forge welding. I just can get it to stick!! Might it be my charcoal? Too much air? Or flux? I'm using borax, I didnt have time to make it anhydrous, so it dances around a bit. Any help or a quick step by step will be a tremendous help. Thanks!!

Michael Brauer

[Rich Hale]

Blueprint ## 0093 may be just what you are looking for. However it is a really good idea to spend time with someone that can walk you through it in person.

[MetalMuncher]

But I live in Brasil and think I'm the only blacksmith here hahaha. I'll check out 93. Thanks!

[Rob Browne]

MM, you may have hit the nail on the head yourself. When I first started trying to weld I had all sorts of problems till one fella told me to "stop blowing the work out of the forge". We often get too carried away with getting up to "welding heat" and make the fire too hot which heats the outside of the work and doesn't get time to soak through the whole piece. We normally do this by really pumping in the air which also moves the oxidising region higher up in the fire so your work may be in this region. Try backing off the air a bit and taking a bit more time to get up to heat. Don't forget to take the piece out of the fire to allow the thin bits to cool and prevent them burning off then put it back in to keep heating slowly.

Cheers

[CurlyGeorge]

MM, also, don't hit with much force. All you need to do is tap the pieces together. If you have slowly brought it to weld temp, and use a lighter hammer, that may also help. I was told to "Put your hammer down. Now, pick up the smallest hammer that you have and don't hit it too hard." It worked for me.

[hill.josh]

ok since no ones given a step by step..
first prepare the scarf and sometimes i grind the piece clean if it has alot of scale but thats not a normal step for me. I stick it in the fire bring it to an orange heat and put on the flux. (i use brazing borax that isn't anyhydrous) not to much though just enough to cover the metal then bring it up to welding temp which for me isn't based on color but when i see sparks dancing on the metal. Then i take it out quickly but don't rest the steel on your anvil until you are goin to hit it otherwise the heat will be sucked out of it.. and tap it lightly with my normal forging hammer. after the welding heat is gone i lightly hammer it reaches dull red because the welding distorts the grain of the steel and the hammering restores it, making it stronger. I was told by a blacksmith of 17 years not to go on to the next step until the first is perfect. I think it applies here too.

[Ironlord Oz]

It depends on the type of weld your trying to do but for a drop the tongs weld I always use 2-3 welding heats. All I do with the 1st heat is get the right temp & tap them together so they have stuck. then I reflux & put it straight back in the fire. It won't take long to get back to a welding heat & this time I work it with medium blows. A 3rd welding heat can be used to "dress" the weld up. This method works well as it makes sure you have a full heat through the steel on the 2nd weld, removes some of the guess work.
Borax as it comes has always worked well for me.
Fire welding is a lot about getting a "feel" for it, if you get it right you can feel it stick. So good luck & practise, practise, practise.:)

[Avadon]

What does brazing borax look like? I went to Lowes and they only had the normal type of flux's for copper brazing.

[maddog]

Brazing borax also sold as brazing flux comes in a small can and is sold mostly in welding shops. Its used for oxy acet brazing. Its borax with some other stuff. It works nicely for forge welding but is a lot more expensive than laundry borax. I havent noticed a significant difference but everyone has his own magic ingredients for forge welding. Mine is to add brake drum turnings to weld which seems to help a lot. You can also braze with 20 Mule Team

Edited September 22, 2008 by maddog

[Avadon]

is this stuff brazing borax? cause i braze copper and brass with it.. will it work for forge welding A36 steel?


Copyrighted photo removed and a link inserted.

[maddog]

Stay Silv is a silver solder. The flux probably is mostly borax. It might work for forge welding - lots of stuff does but I dunno.

There are basically three kinds of soldering brazing processes:

Soft solder: made with lead or tin. Melts at about 600deg. Used for electrical & plumbing work. Can be done with a soldering iron or fuel air torch


Sliver solder: Made of silver. Melts at about 1100deg. Used for jewelry, fine work, AC & vacuum lines and other stuff. Needs fuel air or oxy fuel torch. Sta Silv is designed for AC plumbing. I have some but I dont have the flux so I use 20 Mule Team borax

Brazing: Uses brass brazing rod. Melts at about 1400 deg. Used for joining steel parts and often cast iron which is hard to weld. needs oxy fuel torch.

The temps are approx - I dont recall exactly. These are all very similar processes in that the metal being joined is not melted but held together by a layer of metal which melts at a lower temp than the base metal. They all require a flux to wash the oxides off the surface of the joint.

Strictly speaking only the brass process is called "brazing" the others being called soldering. Seems a bit arbitrary to me since the only difference is the metal being used and the temp but there it is.

Brazing flux is mostly borax with a couple of other cleaining agents added

You can find this stuff in welding supply stores , automotive parts stores and some hardware stores. It sells for about $16/lb. IMO it works a little nicer than ordinairy laundry borax which costs $1/lb for forge welding . I have brazed and silver soldered with 20 mule team borax which you can find on the laundry aisles of many supermarkets.

Edited September 22, 2008 by maddog

[MetalMuncher]

Thanks for all the tips guys, BIG help. I should be able to get a weld now.

[Woody]

When using commercially prepared flux get a MSDS and READ IT! Many of these products contain fluorite which when heated in the forge gives off Hydrogen Fluoride Gas which is extremely toxic, those are big words for DEADLY if you breathe enough of it. When a forge weld fails to make, it is usually not flux that is the problem. Most forge welds fail for one of the following reasons reasons, either it wasn't hot enough or you hit it to hard or the metal wasn't clean. Try bringing it to welding heat and squeezing it together in a vise.

[Avadon]

Thank you maddog and woody. I'm going to try Airgas and see if they have what is in the picture above. Airgas is really the only thing "welding" on capecod, so if they don't have it or can't order it then i'll have to fish it down from the internet somewhere. I'll definitely check out the MSDS. Most of the welding products I use I know are full of carcinogens, but since i've been welding forever I think they have actually mummified my body lol

[Rich Hale]

Twenty mule team borax is a good flux and is found in the laundry soap part of grocery stores

[evfreek]

I am starting to wonder why fluorite is so dangerous. There must be a good reason. I heard that 6011 welding rods contain a small amount of potassium fluoride to help stabilize the arc. They smell terrible, and it made sense that the irritating nature of their smoke was partially due to the fluoride. Well, a quick web search shows that this is not quite right. In fact 7018's, which smell much better when they are burning, contain about 15-30% fluorite based on the MSDS's. This encouraged me to search around a little more. Apparently, the main irritating constituent of 7018 smoke is an alkali calcium fluoride fume. There is some risk to the lungs, but the main culprits, with lower TLV's, are haxavalent chromium, nickel and manganese. In fact, many welding fume analyses do not contain fluoride percentages, instead being restricted to metal fractions. According to many studies, the fluorite fume is not all that harmful, although it has an OSHA and ACGIH TLV of 2.5 mg/m3. Hydrogen fluoride is much nastier, and I know more people who have been laid low by this chemical. It is toxic at about 3 ppm. Oddly enough, the two numbers above are nearly identical. Maybe the fluorite is just as dangerous, but since it was "baked off" with calcium carbonate, its impact is in a less dangerous alkali form. So, why is forge flux fluorite so much more dangerous????!?!???! One reason is the alkalinity of the welding fume. Another may be the quantity, but forge fluxes tend to carry a much lower percentage of fluorite than welding rod flux. Forges are hot, but SMAW arcs are much hotter (even though they're smaller). Fluorite is stable up to pretty high temperatures, and does not decompose into hydrogen fluoride, unless there is hydrogen or water present. It can, according to one source, out-gas fluorine, according to ceramicists. A lot of people inhale a lot of welding fume, especially those doing unprotected confined space work, and the main risk appears to be siderosis due to magnetite deposition in lung tissues, as well as the aforementioned metallic carcinogenicity risk.

Whew, that was kind of long winded. Briefly, why is fluorite so dangerous in forge welding flux when it is much less so in stick welding flux for basic electrodes? :confused:

[maddog]

Im inclined to agree. One 6011 is widely used by prof welders and amateurs. One doesnt hear of poisonings or injuries. I bought 1lb of flourspar from a pottery supply house to add to my forge welding borax. The bag didnt come with any special warnings. I can smell it when I use it but have not suffered any ill effects. Nor is it a toxin that accumulates in the body allowing sub toxic doses to build up to dangerous levels.

I think its a bit of hyperbole that gets passed around and repeated. There are common chemicals that are lethal in high enough concentrations but harmless at low levels. Hard boiled eggs sewage, cabbage and human flatulence all contain hydrogen sulphide, which is more lethal than cyanide yet we survive those. Cyanide too occurs naturally in almonds and mangos