When dealing with Ferrous and Non Ferrous metals, A person has to understand their properties.
Ferrous Metal contains Iron, By adding carbon when heated to red and quenched it makes the object hard, Then the temper must be drawn or heat soaked (Heat Treating) to make it tough and hard.
To soften Ferrous Metal, Heat it to red hot and then cool it very slow. In machine shops they usually have a lime box to bury red hot steel in over night or over the week end to soften the steel so it can be machined.
Non Ferrous Metal, Brass and copper being the most common react exactly opposite.
Heat red hot and quench softens it. Heat red and cool slow hardens it.
As Loaders of ammunition, When annealing brass we need to find the happy medium of Hard enough to hold bullets firmly in the neck of the case, But soft enough the case necks will not split and allowing wild cat cartridges be formed without damage to the case.
