For many years we had a Goodyear owned tire plant here (Kelly-Springfield) and of course, that supported quite a bit of mold work. If I'm not mistaken, 7075 is one material commonly used for molds, and this includes tire molds. I knew a couple of guys who worked at a support shop for that tire plant, and they were always welding up some worn or damaged feature. Whether or not it was 7075 or not for sure I don't know, but it seems that unless it was a structural component for aircraft, a common application for 7075, I don't see the suspected problem of micro-cracking after the weld to me a problem. so I wouldn't be at all surprised. If it's important, I might be able to track down one of those guys and ask. That tire plant is long gone now, and it hurt Tyler's economy when it left. I think it went to.....wait for it.....Mexico if memory serves. Not China though.