The heat treatment is inevitable in the process of brass machining. The heat treatment of brass processing is mainly divided into recrystallization annealing and stress relief annealing.
The necessity of annealing treatment of processed brass: During the processing of brass, such as drawing treatment, extrusion deformation and other machining treatments will make the brass hard, reduce the plasticity of processing, residual stress, etc.
Purpose of heat treatment of brass:
The purpose of recrystallization annealing is to restore recrystallization, eliminate work hardening, reduce hardness, and improve plasticity, so as to facilitate cold forming;
The purpose of stress relief annealing is to eliminate the residual stress generated during cold deformation and machining, prevent self-cracking, and stabilize the size and performance.
Process specifications: Recrystallization annealing can be divided into ordinary recrystallization annealing and bright recrystallization annealing. The difference between them is that bright annealing needs to be protected with hydrogen, ammonia or other inert gas. The cooling method is after the furnace is cooled to below 150 degrees Celsius It came out to cool.
Annealing temperature control: the ordinary recrystallization annealing temperature is generally 500~700 degrees Celsius (the temperature of different materials heat treatment is slightly different but generally within this temperature range); the stress relief annealing generally temperature is 160~400 degrees Celsius (different material heat treatment The temperature is slightly different but generally within this temperature range); the bright recrystallization annealing temperature is generally 450~550 degrees Celsius.
Annealed copper wire
After annealing, a layer of brownish yellow, brownish black or even black oxide scale is formed on the brass surface. This layer of oxide scale will seriously affect the subsequent processing and needs to be cleaned by pickling. Environmentally friendly chromium-free and nitric acid pickling process specification: The potion used is a copper-free chromium-free pickling solution MS0312. This potion is a patented product that has special effects on pickling after heat treatment and is recommended as the current environmental protection process of choice. . The technological process is: chrome-free pickling → water washing → neutralization and anti-discoloration treatment.