Microstructural and Mechanical Characterization of the Dissimilar AA7075 and AA2024 Aluminum Alloys Reinforced with Different Carbide Particles Welded by Friction Stir Welding

Abstract

In the present study, AA7075 and AA2024 aluminum alloys were reinforced with ZrC, and the particles of WC were joined using the friction stir welding (FSW) method. The microstructural and mechanical properties of the welds were investigated using SEM, EDS, and tensile tests. The FSW process resulted in high-quality welds with fine grain structure; the stirred zone has 666% smaller grain size than AA7075 and AA2024 aluminum alloys. The tensile test showed strong and ductile welds. The fracture test showed ductile and less brittle composite joints of AA2024 and AA7075 alloys reinforced with WC and ZrC. The processing parameters in the FSW process significantly affect tensile strength (UTS); therefore, the improvement of UTS with tool speed is much greater than with welding speed. Increasing the tool speed from 400 to 560 rpm increased UTS by 7.1%, and from 560 to 700 rpm by 5.4%. The tensile test results showed that the welds exhibited considerable strength and ductility. Fracture analysis showed that the composite joints made of different AA2024 and AA7075 alloys and reinforced with WC and ZrC were ductile and less brittle. This study showed that FSW can efficiently fuse different aluminum alloys reinforced with ceramic particles.

Keywords

• FSW
• mechanical properties
• dissimilar alloy
• composites
• microstructure
• zirconium carbide