Wear resistance of hypereutectoid steel, alloy with copper and aluminum

Structure, mechanical properties and wear resistance of hypereutectoid steels with 0.09... 8.97 wt. %. Cu is investigated. Addition of 3 wt. % Cu to the steel is accompanied by an increase in microhardness of pearlite from 380 to 430 HV. At the same time Brinell hardness increases from 340 to 390 HB. A further increase in the concentration of copper has no significant effect on the microhardness of pearlite and the Brinell hardness of the steel. Increasing copper content is the reason for the growth of lamellar pearlite microhardness. Three types of copper-based particles are detected. The first type particles have a size of about 20 nm and are arranged at ferrite intervals of pearlite. The particles of the second type have a size of similar to 1 mu m and are arranged at a former grain boundaries of gamma-Fe. The particles of the third type have a circular shape and size of similar to 25 mu m. Wear resistance of hypereutectoid steel, containing 8.97 wt. % copper, is 3.5 times higher compared to bronze and similar to 23 % in comparison with antifriction cast iron when tested according to the scheme of sliding friction. Mainly, this is due to nanoparticles precipitated in pearlite the copper-based epsilon-phase. Relative wear resistance of hypereutectoid steel with addition of copper is almost 3 times higher than the durability of bronze in the friction conditions of fixed abrasive particles. The increase in wear resistance in sliding friction conditions, associated with a high content of copper, is due to increases in the volume fraction of cupric nanoparticles.