I have a process that I am trying to determine here. I have a roll of 17-4PH wire that I am clipping off and putting through a multi-step cold punch/die process.

I then need to dump these parts, bullet casings in this case, onto a ingoing continuous furnace to heat treat them.

I need to achieve an Rc of about 45, so it looks like I need to put them through H900 process of 900*F for 1 hour. I then would need to air cool them.

The thing is, how cool does it need to get? I need to wash the parts after heating so I would need to know how long to wait before washing as to prevent any change in material characteristics by washing them too soon and quenching.