So this is an tiny clamp I made to deal with a tiny spot welding job, it survived, and has been used many times hence.
The screw is either a 6 or 8-32 stainless screw, the handle on the screw was a bit of 1/16 308 tig wire.
The frame I *THINK* is some sort of nickle alloy... may even be pure nickle. I plucked the strip the whole thing came from out of the stainless scrap bin, but something about the color of the arc and the way the tacks/welds looked make me think its got a lot of nickle in it...