Bimetallic barrel is a common metal material has a certain mechanical strength as the base material, and in the inner bore of the tube Face additional layer of special alloy composite material of the protective layer.

This layer must have a certain thickness and hardness of the alloy protective layer based on the use of different working conditions, or the role of a wear-resistant or corrosion-resistant effect, or with both abrasion and corrosion effects. This protective layer uniformly attached to the base material, and an interlock between the base metal on the microstructure and will not fall off, forming a solid overall - bimetallic barrels.