Experimental investigation on effects of varying volume fractions of SiC nanoparticle reinforcement on microstructure an
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Experimental investigation on effects of varying volume fractions of SiC nanoparticle reinforcement on microstructure and mechanical properties in friction-stirweldeddissimilarjointsofAA2024-T351andAA7075-T651 Karinanjanapura Shivamurthy Anil Kumar1,a) Hemantha Kumar1
, Siddlingalli Mahadevappa Murigendrappa1,
1
Department of Mechanical Engineering, National Institute of Technology Karnataka, Surathkal 575025, India Address all correspondence to this author. e-mail: [email protected]
a)
Received: 12 June 2018; accepted: 5 November 2018
Effects of varying volume fractions of SiC nanoparticle (SiCNP) reinforcement on microstructure and mechanical properties of dissimilar AA2024-T351 and AA7075-T651 joints by friction stir welding (FSW) have been investigated experimentally. A rectangular section edge groove was prepared at the adjoining surfaces of the two plates with the butt configuration before FSW. Initially, four fractional volumes with 0, 5, 8, and 13% of SiCNP are reinforced into the grooves of width, 0, 0.2, 0.3, and 0.5 mm and the FSW was performed with the first and second pass to obtain metal matrix nanocomposite (MMNC) at the weld nugget zone (WNZ). The characterization of microstructure specimens was investigated using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction technique (XRD). The FSW joint specimen produced with 5 vol% fraction of SiCNP for second pass processing observes a defect-free, homogeneous distribution of SiCNP with a mean grain size of about 2–3 lm at the WNZ and weld joints higher in tensile strength, 411 MPa, yield strength, 252 MPa, and percentage elongation, 14.3. The result shows that varying volume fractions (5, 8, 13%) of the SiCNP after the FSW second pass led to significant grain refinement at the WNZ and higher mechanical properties compared with FSW specimens prepared without SiCNP. Higher hardness of 150 Hv was observed in the WNZ for specimen produced with 13 vol% fraction SiCNP.
Introduction Friction stir welding (FSW) is a most promising method of welding technology developed by a solid-state metal joining process and plays a crucial role in overcoming the shortcomings and the defects that are observed in the conventional fusion welding of high-strength aluminum alloys such as solidification cracks, slags, and porosity that are responsible for deterioration of weld joint properties [1, 2]. Aluminum and its alloys being light in weight and having low cost, high-level plasticity, malleability, and electrical or thermal conductivity are very widely and primarily used candidates for the structural parts
in
aircraft,
automotive,
and
marine
industries.
Aluminum-based metal matrix nanocomposite (MMNC) fabricated with nanosized particles reinforcement has shown improvement in mechanical and tribological characteristics
ª Materials Research Society 2019
compared with aluminum alloys without reinforcement [3, 4, 5]. In comparison with the unreinforced aluminum alloys, the bulk aluminum MMNC prepared by using SiCNP by ultrasonic
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