Formation of wear-resistant copper-bearing layers on the surfaces of steel substrates by non-vacuum electron beam acladding using powder mixtures

Abstract

By using the method of non-vacuum electron beam cladding, copper-bearing surface layers have been obtained on mild steel substrates. These layers possessed enhanced wear resistance under sliding friction compared to the substrate material. Metallographic and TEM investigations revealed that copper in cladding layers was in the form of nanoscale inclusions distributed in the ferrite matrix as well as in the form of large precipitates in the interdendritic space. The latter is an undesirable effect that significantly reduces the reliability of the material. Technological experiments aimed at dilution of the cladding material with aluminium or carbon in order to reduce the amount of copper precipitate in the interdendritic space and, consequently, to improve the quality of the cladding layers have established that the latter approach is the most efficient. The addition of aluminium, which increases the solubility of copper in the iron, contributes to the formation of the embrittling intermetallic phase (AlFe) in the ferrite matrix. When applying cladding using a mixture containing copper, iron, and carbon, the structure of hypoeutectic cast iron with nanoscale precipitates of copper in ferrite and cement forms in the surface layer. The wear resistance of such layers is one order of magnitude higher than that of the base material.