Frank - if you posted this and you other question as separate questions instead of tacking it on to the end of a discussion on Staple Frets, you might get a better answer. Use the Search function here and search on "Dulcimer Plans". All fretwire is shaped like a mushroom, or a domed T.
The coating on wire feed welding is copper, which acts as a lubricant for the wire when drawn through the feed mechanism in the mig welder. It's not as hard as brass, and won't last long before it wears off and shows the steel inside.It really won't affect anything but the appearance when it wears off. The bigger problem is the diameter. Unless you have some really large mig wire, it's probably way too small for fret staples. I would suggest coat hanger wire. It's soft enough to bend, cheap, and easily obtained. It may not be as hard as fret wire, but should do the job.If it wears enough to be a problem, you can replace them with more coat hanger.
Ooh, I meant CopperPhosphorousrods, not Prosperous Rods, Gotta watch that spell check.
You can achieve arudimentarymeasure of the effect of yourtemperingeffort by taking a piece of the pre-tempered part and laying it beside the tempered part. Take a small ball bearing and hold it with a needle nose on the part, strike it with a hammer, perform the same maneuver on the other part with the same amount of hammer force and with a good glass ormicroscopelook for the size of the indent made by the ball. If you really wanted to experiment, you mightalsotry quenching in oil. If you are using steal, depending on the alloy, oil or water is used. I have no idea of the effects oftemperingwith oil or water on things like Brazing rods, I only suggest this because sometimes deviations in the journey can be fun. Of course that is why it often takes me three or four times as long is it should to get things done. . I get distracted easy....
You may be able to re-temper the rod after you've made the frets, as mentioned above.
To test this take a length of wire and heat one end in a gas flame until two or three inches are red hot, then immediately quench it in water.
See if there is now a difference in how easy it is to bend either end.
Randy, without seeing it I would guess it to be at least as hard as standard fret wire ?
When I made my TMB's I formed the frets from pieces cut from large (3") bent wire paper clips, they seem to be holding up OK, but have a couple of lengths of 1/16" welding rod I am thinking of using on the next build?
If it's the stuff I'm thinking of it's usually annealed so it bends easilly, used to tie rebar together in mass concrete work, that sort of thing.
Maybe do your cutting and bending, then re-anneal them by quenching, this will harden them up. Have a word with a metal worker.