I washed a batch of once fired 284 brass in Dawn to remove
the lube then put them in the oven to dry them at 350 for 45
minutes. They came out with a bluish tint. Did I destroy them?

Most likely they are ok. Here is an extensive article on annealing:

http://www.6mmbr.com/annealing.html

One main point discussed is that the grain structure of the brass is not changed at temperatures less than 482 degrees F.

350 degrees won't warm your brass.

What you are seeing is most likely residue from the soap. Next time rinse them with hot water before dry them.

George

I thank you for your insight. 284 brass isn't easy to come by.
I didn't want to lose it. I guess I thought I was baking brownies
or somthing. More than likely a senior moment!

Nope, should be fine.

I cooked a batch of Norma 3006 cases at 200C overnight once and the cases were tinted blue.

That was ten years ago and those cases are on their 7th reload.

Water boils at 212*, so there is really no need to go higher on the oven temp, might be a bit faster, but not much!

You're O.K. while on the subject of case annealing,I have bought temperature responsive markers available at your welding supply.I've done it by eye for many years but this gets it a bit more precise.

The brass is fine and not annealed. I dry my brass at 325F for a half hour or so.

I put my brass in the dish washer. Comes out clean and no lube and the heat from drying works great.

I temper soften knife at about that, I watch it until it turns a darkish sky blue, its hardening. Seems strange but clean my brass in a viberator cleaner..With loaded rounds I wipe them off with a paper towel after I resize them. I use very little lube and I use Imperial case wax. It wipes right off and is the best..

Thanks for all the responses.