Here is my take,
Any carbon bearing ferros metal when heated then quickly quenched hardens. If heated then allowed to cool slowly it anneals. Non-ferros metals such as aluminum, brass, copper, etc are just the opposite. When heated then quickly quenched it is annealed. Many yrs ago while working in the aircraft industry we heated aluminum extrusions in an electric oven to a given temp for a set time. Then Immediately plunged them into a blast freezer for annealing. When held at that temp they remained soft. Parts were transported to machinists packed in dry ice. After machining, parts were returned to the oven and then allowed to cool slowly to reharden.
I use a cheapy propane torch standing on its base and a 3# coffee can half full of water. Holding cases by base turn in flame until they turn from brass color to "straw" color in the neck/shoulder area then drop them into coffee can. The more (overbore) the case the more often they need annealing. This process prevents split necks and often more than doubles case life due to removing the work hardening caused by firing and resizing.