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Forge weld flux

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I use 1pt. Boric acid to 4pts. Borax. It works fine welding nickle steel billets and plain steel.

Frosty

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Hi. I just learned something interesting about flux when I was trying to weld a piece of cable together. Some time ago, I went to a demo and the demonstrator told me that there is no need to wire brush the steel, since scale improves the fluxing properties of borax. Otherwise, why would the commercial flux manufacturers intentionally add iron oxide to their flux mixtures? At the moment, I just kind of accepted that statement, but it has always nagged me. Later, I learned that silica and scale form a eutectic mixture, which means that the melting point of the mixture is lower than either of the constituents. The eutectic melts at something like 1700 F, which sounds pretty low. Therefore, some iron oxide should help. Anyway, this cable was salvaged from the outdoors, and it was very rusty. Every time I fluxed it with borax and hit it, a whole bunch of black junk would ooze out. After a while, the cable would still be unconsolidated, and black junk would stop oozing out. Then, if I fluxed it again and reheated, more black junk could be squeezed out. Eventually, the 1" original cable solidified into a bar about 1/4" square. It was mostly rust. What a waste of fuel and labor! But it taught something important. At a certain point, enough scale will keep the borax from dissolving it. In other words, at a high enough iron oxide concentration, the melting temperature of the mixture is above the forge welding temperature. Therefore, you have to keep heating and reapplying flux to consolidate the cable. In other words, scale might be helpful for welding up to a point. Above a certain amount, it will just interfere with welding.

This also brings up another point. Many of the comments about adding scale to flux appear to be coming from attempts to reverse engineer a commercial forge welding flux mixture from its MSDS. Although the MSDS says that the slag is iron oxide, everybody knows that steelmaking slag is not just iron oxide. In fact, if there is a lot of iron oxide in the slag, that is wasteful, just like beginners trying to recreate the bloomery process. Slag is a lot more like rock wool, and attempts to reverse engineer slag containing flux might benefit from material more like this.

Anyway, that seems to be what the limited experiments suggest. :)

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I use a mix of 4 pts. borax and 1 pt. boric acid. It works a treat.

Frosty

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I'm new to forge annealing, heat treating, tempering, and forge welding. I'm interested to know what kind of flux to use when forge welding like what I saw on you tube. Good demonstration on a horse shoe, attaching both ends using heat and flux. Annealing is to soften the steel right?, heat treating is when non-magnetic quench in oil, tempering is using a stove @ 400degrees to temper for 2 hours right?. And wah-la grind in between and final the edge and handle and there's a knife finished hopefully all by using a forge and belt grinder etc. Rey

Edited by Rey
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For flux I use plain 20 mule team Borax.

Annealing is a form of Heat Treating; as is hardening and normalizing and tempering!

You have to have the right alloys to harden by heating and quenching; some alloys will get softer when you do that!

What you quench in depends on the alloy. Quenching an air hardening alloy in oil will probably shatter it. Quenching a water hardening steel in oil may not harden it enough.

Tempering depends on the alloy, hardening method and what you want to end up with---400degrees to temper for 2 hours may be too much or too little.

STRONGLY SUGGEST you go ILL a copy of the Complete Bladesmith, Hrisoulas, from the public library and not think that a web page or two written by ??? is a substitute for several hundred pages written by an expert!

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STOP! Read what you just said!

And wah-la grind in between and final the edge and handle and there's a knife finished hopefully all by using a forge and belt grinder etc. Rey

:mad: First: Can you forge a tapper? Then can you make a hook out of it? And not in ten heats ether.If not then how are you going to forge a knife? Wah-la... Stock removel? Cool..You know that when you make your blank you have to cut it out. Wah-la... With what? A grinder belt?

Look as Thomas Powers said. GET SOME BOOKS. Read them then come back and ask the right Qustions. True

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WAH-LA is spelled "viola"

SEARCH BEGINING BLACKSMITH ON THE FORUM....find your local blacksmith group... you WILL hurt yourself if you do not learn some basic use of the tools involved...

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Look at Wayne Goddard's $50 Knife Shop. It will answer all of your questions and help you get started with little investment.

It is on Google Books for free. Some pages are missing though.

It runs for about $20 online.

Good luck.

- Brook

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Thanks for the input, gents and rock-n-time it seems to me that I don't need to be lectured by you and I don't have to come back and ask the right questions. All I wanted to know is what kind of flux is needed to forge weld and I just added my way of making my knives. No one is perfect and every knife maker or steel artist has there own way of doing the art. But, I do appreciate the good words by the other gents. Rey

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Rey; you forget that we are not speaking only to *you* but to *EVERY* new smith that will ever read these postings. Are we not allowed to teach them, who may not be as far along in their smithing, too?

Otherwise it would be simpler to just say "we answered that question 3 years ago go look it up".

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For the record, wah-la is not spelled "viola" -- that's a stringed instrument that looks like a violin. It's "voila." (The French add a diacritical mark, but this is Uhmurrica, dang it.) If you're going to correct others' spelling, be sure you're right. This is why I rarely mess with trying to correct others' spelling and grammar on the Internet. The best-case outcome isn't that great, and the much more likely worst-case is that you end up looking like a tool. No offense. ;)

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Please assume that I am always posting in dialect and so any misspellings are merely aspects of my heritage that I choose to honour!

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Thank you Thomas for your kind words and Matt for the correct spelling, my mistake. Kind words to friends are taken into heart and mind so, I do appreciate it kindly gentlemen. Thanks, Rey in Texas

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Please assume that I am always posting in dialect and so any misspellings are merely aspects of my heritage that I choose to honour!


Excellent. I buy it!

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(That and the fact I'm better with a 3# hammer than with a keyboard---though my wife tells me I hammer the keys when I type and it's the keyboard that pays the bills---integration and test in a research facility)

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Other flux choices, a lesser potentancy: silica sand, often sold as play sand, but some play sand is not silica.

20 mule Borax has been mentioned.

greater potency: boric acid, sold at pharmacies as a soak treatment, and at hardware stores as ant powder, read lables carefully to make sure it is just boric acid.

According to what I have read these three fluxes and proper procedure will let you weld almost any steel.

Do remember, I haven't welded what I want yet, but I have welded some scraps together with what seems like heroic effort. I made a small piece of "fake" cable Damascus out of some insulation ties today, but couldn't weld the handle onto a set of tongs I am making. I ended up burning the jaw off the tongs!

Cleanliness is more important than flux, so scrub off all that scale before fluxing. Procedure and perfect practice are very important too. Practice with cold metal first, then try welding.

All these fluxes stick to metal at around black to dull red heat, long before scale forms, and are considered relatively safe. That said, I also recommend reading MSDS on materials and on commercially prepared fluxes, the effects of fumes in general are unpleasant and in all to many cases can be fatal.

Phil

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clean quartz sand was the flux suggested for welding real wrought iron as it already has a lot of silicates in it and with stands the higher temps to melt the sand better.

Boric Acid is sold as roachpruf anti roach powder much cheaper than at a pharmacy. Have not seen it for ants...

I use a mix of boric acid and borax for my welding most of the time.

High Ni or Cr alloys may need a still more aggressive flux.

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You are right about the boric acid. It's cockroach powder. I was given an expired bottle of pharmacy boric acid soak. Not sure why having a date from 1980 makes it bad though. I haven't used it but there is very little in the container.

I said "almost any steel" because most of us who want to weld those alloys have practiced on common, cheap steels already, and the procedure is not the problem. But I may be overstating that too. The more aggressive fluxes also produce more hazardous fumes.

Phil

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I've used fine, clean play sand (nearly white) as a sort of extender for Dr. Hrisoulas's "steel glue." I cut the flux almost 50/50 with sand, and it doesn't seem to have hurt anything. I haven't tried sand alone, though.

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ok i have found this page to learn about flux and all that i have found on it is people correcting one another! what can i use for flux when forge welding?

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What are you welding? How are you welding it?

For my Bandsaw blade and pallet strapping billets I use 20 mule team borax and roachpruf (boric acid)

For plain drop the tongs welds: borax or borax with filings.

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ok i have found this page to learn about flux and all that i have found on it is people correcting one another! what can i use for flux when forge welding?


You must not have read very carefully. There were several suggestions in the thread before your post: borax (pretty much the standard), boric acid, and clean silica sand. Some other possibilities not yet mentioned include fluorspar (pretty nasty stuff when it burns, though), various forms of ash, crushed green glass (and other colors might work), and ammonium chloride. But I suggest starting with plain old 20 Mule Team borax. It's pretty readily available, inexpensive, effective, and relatively safe compared to some of the others.

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does anyone have a good recipe for welding flux?
i do have 20 muleteam borax just wonderin if there is a good homemade flux or some additives to put in it to make it better

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