Microstructure, mechanical and wear properties of friction stir processed Cu-1.0%Cr alloys

Friction stir processing (FSP) is a solid-state material processing technique to enhance the surface properties of metallic materials. In this study, Cu-1.0%Cr alloy is friction stir processed with an intention to improve its surface hardness and wear resistance. A single-pass FSP was performed by varying the tool traverse speed from 50 to 200 mm/min in steps of 50 mm/min and the tool rotational speed was kept constant at 600 rpm. Samples for microstructure, mechanical, electrical conductivity, and wear studies were extracted from the stir zone. The grain size of the stir zone was reduced to 4?m from its initial 40 ?m after processing with a traverse speed of 200 mm/min. An increase in hardness was observed in the stir zone processed with higher traverse speed (200 mm/ min) from 71 HV to 95 HV. The minimum wear rate and decrease in coefficient of friction (CoF) were observed in the specimen processed with 200 mm/min. The electrical conductivity of the base alloy was 84.4 % IACS, whereas for the processed at 50 mm/min alloy it was 82.1 % IACS. Results showed that FSP is an effective way to increase the wear resistance of the surfaces without much deteriorating the electrical conductivity.