Whatever it is, I did a little test with ER70 (S6) and looks good, no cracks or porosity. So I'll proceed and be on the watch for old cracks. Thanks everyone for the input! Sounds plausible. The beam was said to have been around for a while. But does shitty old mild steel develop orange skin like in...

Search - http://www.scrapmetaljunkie.com spark test - and they have some clear pictures of several spark tests on various metals plus other info. From the look of their pictures compared to yours the closest would be tool steel! Would that be possible in an I beam? If so could it be for a special p...

Sounds plausible. The beam was said to have been around for a while. But does shitty old mild steel develop orange skin like in my first picture?

Coldman wrote:Look in the crack, it's old meaning you didn't do it. What you have is an old very rusty abused and @&itty piece of mild steel.


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Ok, couldn't wait. I tried tigging the corner to see if that hardened it. Well, not sure what happened, but I seemed to be able to hand-file it down pretty easily. Made me optimistic... ...however: I called out the other corner with a 500g hammer. Below you see what happened. That crack means that's...

I'll try the hammer and the Tig-Corner test on the weekend, thanks for the input.

Here's a side by side comparison of the spark test btw. On top the I-beam, below a piece of mild steel.

Hi, I recently acquired a couple of steel I-beams. They're old and rusty. I want to use them to build the underframe for a larger desk. The plan requires me to cut two sides of each beam and build a bracket-like shape by welding it, angled, to a smaller sections the beam on each side. It didn't occu...