Seized bolts

Trying to understand what I did wrong here or what happened. I've had this happen two times now - Removed OEM bolts from aluminum parts, put the bolts back in and had to later take them out. When I did they were seized. Photo attached.

How much did you torque the bolts? Perhaps that application needs anti-seize in the future...

One bolt required about 16 lbs and the other about 60 lbs. The photo is the larger of the two. Is this called galling?

I did wire wheel brush the fasteners clean since they had been removed for a while and needed to be cleaned up. In doing so I believe I may have removed the surface coating from them - zinc coated I guess. The application for these bolts is just car parts. So bolts are steel they thread into aluminum.

If seizing has been an issue, like David mentioned, an anti-seize lubricant is designed to make this far less likely to occur.

There are some situations where typical anti-seize isn't up to the heat requirement though there are some higher temp options.

In some cases you want more of a locking agent, but without seizing, in which case Loctite does a bit of both.

Like most things, the proper tool for each job can vary.

That doesn't look galled -- to me, it looks like you pulled the threads out from too much torque. Any chance the bolt was bottoming out in the hole (or something non-compressible got into the hole)? That can also strip threads if you can see the fastener hasn't pulled up tight and keep twisting - but that would likely be way more than 65 lb-ft of torque.

The small one could have pulled the threads then from the impact ratchet, not gun but the large one (photo) was drawn down with an impact gun but not to torque. I did that with a torque wrench. Somewhere in all this I did something wrong. Probably back to hand ratchets from now on to be sure.