The effectiveness of the effect of copper doping on the wear of eutectoid steels

Abstract

The intensity of wear of graphitized eutectoid steels with a carbon content in the range of 1.1÷1.7%, by weight was investigated. The effectiveness of the effect of copper doping on the wear of eutectoid steels in the cast state has been determined. It was established that under conditions of dry friction by sliding and taking into account the friction parameters in the sealing units the temperature on the worn surface and in the thin near-surface layer should exceed 1100 0С, at such temperatures and copper content more than 12%, by weight, in the binary system Fe-Cu there is a two-phase region +-phase, and  - phase, exists in the state of liquid and acts as a lubricant, the wear mode goes from dry to limiting. Lines of existence of -phases in the liquid state are constructed. The results of studies of the effect of copper on the intensity of wear of steels with different carbon content, under conditions of dry friction by slipping, indicated that regardless of the amount of carbon, doping of alloys with copper significantly reduces their intensity of wear to copper content at the level of 10-12%, by weight, a further increase in copper doping equalizes the effectiveness of the impact and reduces the intensity of wear. Alloying of steels with copper of 12% or more causes the formation of a copper phase film on the friction surface. Under the condition of alloying steel with copper less than 12%, the steel structure contains -phase, as a product of a three-phase eutectoid reaction and as a decomposition product of supersaturated solid iron solution. As the copper content in steel increases, the amount of copper phase in the steel structure and its amount on the contact surface increases, after reaching the copper content in the steel sufficient to form the primary grains of the copper phase, the formation of a stable layer of copper on the contact surface begins, which is the constant boundary layer of copper -phase in the liquid state. Keywords: steel, copper, carbon, alloying, wear resistance, friction.