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Definitive Test for a Forge Weld?

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I am fairly new to smithing. I have made hooks and some other stuff but I tried my first forge weld today and I would like to know what you think. I have deliberately left the images high res so people could see the details. Essentially I took 3/8ths bar and bent it back on itself then covered the areas to be welded with borax and then heated it to fuming hot under high propane heat and then tapped it together then hammered it hard.

Clearly on the bottom of the loop I have a bit of a cold shut for a bit but above that I THINK it is welded. I dont know how to make sure short of a destructive test. I suppose I could cut through it and see what I can see but I was wondering if anyone could look at my attempt, give me an opinion or suggestions and suggest a manner I could know pretty sure that it is actually welded.

Thanks for looking.

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post-15449-067830900 1288404671_thumb.jp

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I have a possible solution. take a grinder or files to the sides and get polish the weld area then etch. I'm not sure if this would help or not, but i think it might make it esier to see where the weld is and isn't.

please someone correct me if I am wrong. I just might be, heck I probably am.

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Hey Kraythe!

I tried the exact same thing for my first weld! Did you put it back in the forge for a second heat?

One way to tell if the weld is complete is that both pieces of metal are the same colour. If the two parts are different colours as they cool, they're not fused (or at least, not completely). This doesn't tell you as much about the quality of the weld as a destructive test, but it's definitely a good start.

Does anyone know if this method can be used to figure out the *quality* of the weld, and not just if it's complete?

Another way to tell would be to use an ultrasound tester, but those are a bit thin on the ground. :rolleyes:

If you do end up wanting to do destructive testing I'd suggest putting it in a vise and bending it back and forth until it breaks. The way stuff breaks tells you a lot about it! I broke my first weld apart and then cut it into 0.5in wide slices. That piece broke just behind the weld- the grains were gigantic. Then, cutting it up told me 2 things: 1) like you, I hadn't gotten the first little bit welded, so I would have needed to brush, reflux and do a second pass and 2) I needed to clean the metal better before welding!

If you really want to get into the details, you can polish the cutoffs and then etch them in acid (like vinegar) to see lots more detail- the acid etches the grain boundaries much faster than it does the inside. Doing this and then looking under a microscope tells a lot about the grain structure.

Hope this helped!

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Take it to your anvil and hit it cold (only once or twice, and really hit it). If it breaks, it was not welded.

If it was still hot, hit it so you are sorta upsetting in line with the weld, this creates a lot of shear at the weld and it will fail if the weld is poor. This is also part of dressing the welded area.

You are going to get dozens of suggestions. You will ultimately end up making several test welds TO break (or at least attempt to break) so you can be confident about welding.

I am very hit or miss on welding, well, way more miss, I just don't get out to forge enough.


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ok it looks like you have part of it welded good .. there is a section where you cant see a line ant that is probably welded fine ... i would do a better scarf next time so the end welds up nice to get that end to weld good is the hard part ... i find that a propane forge is harder to weld in than a coal or charcoal forge because with a coal forge you can heat well over welding temps (meltdown!) so you can go till it just starts to sparkle then weld . in a propane forge a lot of times it dosent get to that heat ... also propane forges tend to oxadize the steel more (more scale) its not true of all propane forges but most are that way .. for a first weld its fantastic! now go do twenty more and make um perfect!!

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The weld isn't all that good. The leftover seams, we call shuts. In a good forge weld the shuts either don't show at all, or they might show only on the scarf points. The safest welding heat is a bright yellowish white color with no sparks being emitted. You may have a few incipient sparks but NOT a big shower, or you'll begin to oxidize, burn, and ruin the metal.

On a loop weld like yours, it is good to put a simple one sided taper on the free end to act as a "simple scarf." The taper is 1 1/2 to 2 times the stock thickness in length. This scarf allows the metal to "flow" together. If there is no scarf the metal end bites into the parent bar instead of fading into it easily.

You can take a half dozen welding/sweating heats (no sparks) in the same area without damaging the metal. You wire brush and flux before each welding heat. On a weld area like yours, you can hit first on the scarf side, and then quickly on all four sides pepeatedly. The problem with taking many heats, is that you will lose stock in perhaps three ways. One is scale. Two is sparks. Three is hammer reduction. Therefore, the finished weld may be OK, but the stock has lost thickness and width.

One test of a forge weld is to twist it hot. If it opens and goes haywire, then you'll have your answer.

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

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Kraythe, the main thing is that you are trying. No one just starts making "good" welds right off. It takes practice, and you seem interested enough to ask for suggestions. So I think that with practice you will be welding good welds in no time. Get the basics down with the faggot weld before you try welding two seperate pieces together. Then, Practice, Practice, Practice. Good luck. :D

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Does the weld serve its purpose. Is it visually pleasing. Thats very good on your first try.

The only way to test a part that size with out destroying it would be to x-ray two different views of the joint.

Forge welding is kid of like squishing snowballs togather.

Work out a procedure that works for you and practice it

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