Abstract: Disclosed is a manufacture and coating method of mechanical products using ferrous alloy in order to improve wear, corrosion, and heat resistances of the mechanical products which are exposed to friction and wear environments with or without lubricating conditions. The mechanical products of the invention include rotation contact parts such as bush and shaft in the inside of caterpillar roller, mechanical seal under high surface pressure, and drawing dice and plug under sliding friction stress. A ferrous alloy composition used for coating in the invention comprises Cr:18.0-42.0 wt %, Mn: 1.0-3.2 wt %, B:3.0-4.5 wt %, Si: 1.0-3.0 wt %, C: less than 0.3 wt %, inevitably incorporated impurities, and Fe for the rest of content. A ferrous alloy composition used for manufacturing bush type product comprises C: less than 4.5%, Si:2.5%, Mn:less than 2%, Cr:0.5-35%, and Fe for the rest of content.