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I Forge Iron

Safe to forge scrap metal


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I am new to forging (only started during quarantine) and I have been using almost exclusively railroad spikes.

I decided to go to the thrift store and look for other scrap metal to try and forge, but after a tent spike turned yellow (and I found out about the dangers of galvanized steel) I do not want to make that mistake again.

Is there a guide to picking usable scrap metal, or a way to identify is a metal is safe to forge?

Thank you all so much for your help.

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Welcome aboard Nerd guy, glad to have you. If you'll put your general location in the header you'll have a much better chance of meeting up with members living within visiting distance.

Galvanized (galvy) is generally easy to spot, it's generally ash grayish and or has a distinct crystal pattern if hot dipped like a pail. There are other potential alloying metals you do NOT want to put in a forge fire. Some alloys contain lead and or cadmium to name the worst. 

Evaluating the working characteristics and properties of salvaged steel is a range of skill sets in themselves. I HIGHLY recommend new folk just buy a 20' stick of hot rolled (mild / A36) steel. I like starting guys on 3/8" square it's thick enough to hold heat so you aren't putting it back in the fire every couple blows but it's small enough to finish a piece without tiring too quickly. 3/8" square is close enough to the same weight per inch as 1/2" round, I consider them the same size. 1/2" square is about as heavy as I start guys on and it's a good size just more work, once you've developed the hammer control and muscles it's not an issue.

Some salvage stock is pretty "predictable" and good stock, coil and leaf spring are VERY useful but are harder to move under the hammer and require better heat control / fire management than low carbon steels. It makes good tools and blades. It's iffy though seeing as a spring broke for a reason, usually stress fractures resulting from millions of compression cycles under a vehicle. This is the case for any used spring so be aware a finished piece may fail in heat treat or use. Coil spring is excellent stock to start learning to work higher carbon steels while making useful tools: punches, drifts, chisels, scribes, pry bars, etc. 

Lots more to come and I'm kind of a talky guy.:ph34r:

Frosty The Lucky.

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Like Frazer said, "In rust we trust". If it is plated, leave it be. Watch out for painted stuff, too. It could be lead. If it is rusty, you're good. But as Frosty mentioned, it may be a higher alloy and just not appropriate for forging. If you can identify where a piece came from/ what it's original use was, there are scrap metal charts that can let you know what it could be. For starting out, buy a stick of a known mild steel- you know what to expect of it. Other than that, junkyard rules apply.


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