Evaluation of SiC nanoparticles-based reinforced casted filler effects on the mechanical performance of Al-2024 GTAW welded joints
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In modern age industries, various ceramic carbide base nanoparticles are widely used in casted fillers due to significant contribution to the improvement of thermal stability, weldability and mechanical characteristics of welded joints. In this research work, Silicon carbide (SiC) based nanoparticle-reinforced casted filler has been manufactured to evaluate its performance on the mechanical and microstructural properties of gas tungsten arc welded (GTAW) Al-2024 joints. The effect of the SiC nanoparticles has been assessed at process variables such as welding current and gas flow rate on the ultimate tensile strength (UTS) and microhardness (MH) of GTAW Al-2024 joints. The Taguchi method has been used to conduct this research work. The results revealed that adding 5% SiC along with the change of weld current from 70 to 80 A and gas flow rate from 9 to 16 L/min resulted in a rise of the UTS from 310 MPa to 410 MPa (an improvement of 24.39%) and the MH from 93 to 129 HV (an improvement of 27.91%) of GTAW Al-2024 joints. The addition of SiC nanoparticles caused a uniform distribution of SiC particles at the melted zone of welded joints that assisted in a significant increment of heat transfer rate, which in turn increased the weld bead penetration and mechanical characteristics of GTAW welded Al-2024 joints. The optical microscopy microstructure analysis depicted that grain size reduces, and grain structure changed from the coarse to fine dendritic with the addition of 5% SiC nanoparticles. A scanning electron microscope (SEM) showed that adding 5% SiC caused a uniform distribution of fine eutectic phases at the grain boundaries and formed a coarse and fine dimple structure. Conversely, large voids and shallow dimples have been observed at the addition of 10% SiC nanoparticles in the casted filler due to the irregular SiC nanoparticle distribution that restricts the diffusion rate at the welded region.
