THE THERMO-MECHANICAL AND MICROSTRUCTURAL INVESTIGATIONS OF AA 6061/GNPS WELDED JOINTS DEVELOPED BY CONTINUOUS DRIVE FRICTION WELDING

The paper provides a novel technique for merging graphene nanoplatelets (GNPs) within aluminium matrix (AA 6061) by continuous drive friction welding (CDFW). The welding processes were done at 1400 rpm and 2000 rpm rotational speeds with two different frictional loads 2000 N and 2500 N for 5 sec and 7 sec welding times. The welded joints were subjected to tensile and hardness tests. The heating-cooling cycles through the welding process were monitored. The microstructure investigation was performed using optical and scanning electron microscopes (SEM). The effect of welding conditions on the ultimate tensile strength (UTS) results of AA 6061 and AA 6061/GNPs were completely studied in details. There is no big detectable variation in the mean hardness values due to the GNPs addition. The best welding conditions for achieving the highest mechanical properties were defined. The presence of GNPs in the welded joints results in lower heating at the welded joint at the same welding conditions. Finer grain structure and homogeneous distribution for the GNPs within the welding zone were observed.