Nano-porous layer on steel surface as lubricant carrier.

: In cold forging of steels, metal soap on zinc-phosphate coating is excellent lubrication system. However, the system is not only less productive, but produces hazardous wastes. In this study, an alternative lubrication system using surface porous layer is proposed. Surface oxide on low carbon steel turns into porous layer by chemical reduction using hydrogen. It is found that liquid lubricant decreases the friction coefficient in compression greatly. The porous surface enhances the decrease, especially in the cases of heavy deformation.