A suggestion here:
"Annealing is often confused with Tempering. Both can be considered forms of Heat Treatment, but, with the risk of oversimplifying matters – Tempering takes the metal to a lower temperature and tends to harden metals, Annealing is a shorter, hotter process and softens them.1
We don’t want to harden the metal any more than it already is. So, we are talking about high temperatures for brief periods of time. Under-anneal and no real benefit will occur, over-anneal, and you risk over softening your brass. Something you don’t really want when it’s meant to be directing and controlling and explosion.
Brass Annealing Temperature
Online, the suggested temperature your brass needs to get varies a bit, ranging from 600 to 800 degrees Fahrenheit (that’s 315 to 420 Celsius for us in metric land). The average recommendation seems to sit in the 700 F range though (370 C)."
One one of the online forums, the consensus seems to suggest heating to 650 degrees Fahrenheit for 8s to 15 minutes. I believe the wide range of heating time is due to the various size of the samples.
The stress relieving temperature is normally between 550 and 650°C for steel parts. Soaking time is about one to two hours. After the soaking time the components should be cooled down slowly in the furnace or in air. A slow cooling speed is important to avoid tensions caused by temperature differences in the material, this is especially important when stress relieving larger components.
The temperature for stress relieving copper parts is, depending on the alloy, 150-275°C and for brass components 250-500°C.