Comparison of the tribological behavior of columnar-grained polycrystalline copper with vertical/horizontal orientation sliding against AISI 1045 steel

► The friction coefficient and wear rate of HO pin in sliding against AISI 1045 steel disk are lower than that of the VO pin. ► A tribo-oxidation layer presents on worn surface of HO pin and a mixed layer in composition presents on worn surface of VO pin. ► Tribo-oxidation has a beneficial effect on reducing friction and wear for HO pin sliding against AISI 1045 steel disk.