In the dry friction condition

the sliding friction and wear characteristics were investigated of the grey cast iron and the untreated high-carbon equivalent alloy gray cast iron with high carbon equivalent alloy under different loading and friction time with the semi-metallic material as the sub-metallic material. The results reveal that compared with the untreated ones

the nitrocarburized high carbon equivalent alloy gray cast iron presents high friction coefficient and good stability

and the wear resistance is desirable

especially under the condition of large load and long time. The wear types of untreated high carbon equivalent alloy gray cast iron under low load are characterized by adhesive wear accompanied by slight three-body abrasive wear

and by serious adhesive wear and fatigue spalling wear under high load. The wear mechanism of nitrocarburized high carbon equivalent gray cast iron presents mild oxide three-body abrasive wear under low load and fatigue spalling wear under high load.