brass will harden on its own over time, annealing allows you to shape and easily cut the brass but later it will return to a more harder state.
There is to my knowledge no known method of hardening brass though I am sure someone will come up with a method.
brass and copper will withstand use better in an annealed state and as it returns to a hard condition it will crack, I have seen evidence of pipes that subject to vibration that have cracked. It is a part of service to remove copper or brass pipes on working machines and anneal them.
Phosphor Bronze can be hardened to a degree by heating and quenching.
In the past copper pipes were used to transfer fuel on IC and CI engines and the vibration would harden the pipes. Failures could mean fuel under high pressure spraying all over.
That is why fuel pipes were made in a loop and not straight!
Nowadays plastic piping is used on low pressure and steel on high pressure.
Brake piping comes to mind and fuel return pipes on diesels.
Clive