What is the blackening treatment of firearms?

It is to blacken the material in an alkali solution of about 150 degrees to form an acid-resistant oxidation layer.

Reference: General gun parts are forged or machined parts with great internal stress. However, the firearms themselves require higher materials, such as barrel, needle and lock bolt. It should be not only strong enough, but also resistant to vulcanization and corrosion.

Therefore, the parts of firearms should be annealed after processing, that is, the materials should be heated to a suitable temperature, and then slowly cooled to release its internal stress.

After annealing, the parts need to be quenched, tempered or heat treated according to the use requirements. Common methods are:

1. surface nitriding or carburizing: it can increase the surface hardness of the material while maintaining the elasticity of the core.

2. Work hardening: Turning a layer on the surface can make a part of it just produce stress hardening and achieve the effect of nitriding or carburizing.

3. Quenching: After heating to the grain boundary melting temperature for a period of time, the material can be cooled rapidly by oil cooling or water cooling, which can obviously improve the strength of the material, but it is easy to cause deformation.

4. Blue baking: blackening the material at the alkali liquor temperature of about 150 degrees to form an acid-resistant oxidation layer.

After one or more of the above processes, the life of gun parts can be significantly improved. Because all the above processes are to change the crystal structure of materials by means of heating or reheating and cooling, they are called heat treatment!