Microstructural, texture, and crystallographic analysis of SiC particle incorporation in double-sided friction stir welding of dissimilar aluminium alloys

This paper investigates the impact of incorporating SiC nanoparticles into the welded interface joint of dissimilar aluminium alloys 2024 and 7075. Double-sided friction stir welding (DS-FSW) was performed to investigate the impact of added nanoparticles on the joint's mechanical properties and crack growth rate . Microstructural analysis of the fractured surface was conducted to assess the influence of nanoparticles on crack propagation , while field emission scanning electron microscopy (FESEM) was utilized to examine the grain size distribution across different weld zones. On analyzing the DS-FSW joint with SiC-reinforced particles using electron backscattered diffraction (EBSD), predominant shear texture components such as B/B̅ and C are observed. Additionally, there are deformed textures like Rotating cube (H) {001} <110> and F {111} <112>, along with recrystallization texture elements such as Goss {110} <001>, P {011} <112>, and Cube {001} <101>. Mechanical properties, determined through hardness and tensile tests , were compared between nanocomposite weldments and base metal to assess the improvement in mechanical properties following the inclusion of SiC particles. Crack growth tests were performed using compact test (CT) specimens at a maximum load of 5 kN and a stress ratio of R = 0.1. The addition of SiC nanoparticles to the joint area led to a significant decrease in grain size and an increase in hardness within the stir zone, compared to the base metal and samples without the powder. The tests revealed an approximately 62 % increase in tensile strength and a notable increase in microhardness of the weld zone of the aluminium alloy metal matrix composite (AAMMCs). • The average grain size in SZ is 3.64 µm for SiC-reinforced DS-FSW joints and 8.77 µm for unreinforced. • Significant shear texture components B/B̅ and C, along with recrystallized texture were observed in the SiC-reinforced MMCs. • Fabricated AAMMCs exhibit higher tensile and yield strength than unreinforced DS-FSW joints. • The weld joint with SiC demonstrated greater fatigue crack resistance than those without SiC in DS-FSW joints. • The critical stress intensity factor range (∆Kcr) was higher (30.58 MPa√m) for SiC-containing samples.