Bimetallic barrel is made of an ordinary metal material has a certain mechanical strength as the base material, and in the inner bore of the tube Face Further composite layer of special alloy materials protection layer.

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