Publication: Fabrication and characterization of ultrafine-grained al5083 matrix nanocomposite joint by friction stir welding
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Date
2023-05-01
Authors
Muhamad Nabil Bin Faizul Hilmy
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Abstract
An investigation of friction stir welding (FSW) process parameters was
onducted on ultrafine-grained (UFG) cryorolled AA5083 to determine the best
combination processparameter. Prior to FSW, the as received AA5083 sample was
cryorolled to produce UFG structure, which reduced the thickness by 50%. Welding
parameters for the UFGcryorolled AA5083 includes tool rotational speed (10, 600,
865, 1140, 1500 rpm), welding speed (65, 127, 264, 367, 500 mm/min), and tool tilt
angle (1, 1.5, 2, 2.5, 3°).To assess the quality of the welded joints, a visual inspection
technique, macroscopic and microscopic analysis, Vickers microhardness test, tensile
test, and fracture observation were used. The best combination of FSW process
parameters was obtained at 865 rpm, 264 mm/min, and 2°. The sample welded at the
best parameter combination had a smooth welded surface with no traces of surface
defect, a defect- free welded joint, and the finest grain size within nugget zone (NZ)
with an average size of 27.6 µm. Furthermore, the sample had the highest
microhardness (91.8 HV), and the highest ultimate tensile strength (144.88 MPa).
The surface of the sample had fine dimples with fewer cleavage facet structure,
indicating that the sample fractured in ductile manner. However, the as-received
welded joint had a better quality with higher microhardness (92.2HV) and ultimate
tensile strength (149.2 MPa) than UFG welded joint. To improve the strength of
UFG welded sample, nanoparticles AL2O3 was added as a reinforcement during
FSW. When Al2O3 nanoparticles were added to the UFG sample, the grain was
refined to 17.3 µm in the NZ, resulting in a higher microhardness of 102.5 HV and tensile strength of 163.8 MPa when compared to the Al2O3 reinforced welded joint of
the as received sample. The spring back values of both unreinforced UFG (1.7⁰) an
as-received (2.3°) were lower than reinforced of UFG (2.8°) and as-received (3.7⁰).
At the highest applied load of 50N, Al2O3 nanoparticles reinforced welded joints of
UFG cryorolled and as-received recorded low specific wear rate of 6.66 x 10-5 mm3
N
-1 m-1
and 7.722 x 10-5 mm3 Nm-1
respectively