Microstructure, mechanical properties, and electrical conductivity of the solid-state recycled pure copper machining chips

The demand for new methods to reduce CO2 emission by reusing metal scrap has increased recently. This study deals with a new recycling technique utilizing a friction stir consolidation process. In this work, copper was directly recycled from machining chips in the solid-state form without any remelting to reduce environmental pollution and to increase the economic value of the waste material. During the process, copper chips were loaded into the chamber; then, a rotating tool was plunged into the chips at a specified rotational speed and feed rate. Due to the huge amount of heat generated, the softened material was compressed and synthesized to form a consolidated part. Microstructure, mechanical properties, and electrical conductivity of the finished samples were evaluated and compared with as-received material. Also, a numerical model was implemented to predict the evolution of the main field variables, including temperature, density, and strain.