Investigating AA5083/(SiC-Gr) hybrid surface composites fabricated by Multi-pass friction stir processing

Friction stir processing (FSP) is well known for its ability to fabricate surface composites with enhanced tribological, mechanical, microstructural, and other properties. Various FSP parameters can influence the final characteristics of the fabricated surface composites. This work aims to study the influence of the number of FSP passes and the direction of tool travel on the microstructural, microhardness, and wear characteristics of the produced surface composite. FSP was conducted on AA5083 to fabricate hybrid surface composites utilising SiC and graphite (Gr) as the reinforcements. Single, double, triple, and four numbers of FSP passes were conducted in the same as well as by altering the tool traverse direction (ATTD). The wear results obtained were correlated with microhardness measurements and microstructure characterisations. The utilisation of a 3-pass FSP with ATTD improved the microhardness and wear rates. It was found that using 3 FSP passes by ATTD enhanced the microhardness by 25.20% and the wear rate by 63.75%. The FSP-treated specimen resulted in a notable reduction of approximately 25.25% in COF compared to the "As-received" specimen. The produced hybrid surface composite showed uniform distribution of reinforcement material throughout the matrix under both 3-pass and 2-pass FSP with ATTD.