Microstructure and mechanical properties of cryorolled al 5083 alloy Welded by friction stir welding

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Date
2019-07
Authors
Muhammad Danial Bin Mohd Talha
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This study was aimed to investigate the weld microstructure and mechanical properties of cryorolled Al 5083 alloy using friction stir welding (FSW). The comparison of the weld joint and mechanical properties of as received and cryorolled Al 5083 alloy was made. The as received Al 5083 alloy was cryorolled up to 50% reduction to produce Ultrafine grained (UFG) structure. Microstructural studies revealed severely deformed grains which are elongated along the rolling direction in cryorolling condition. From the XRD pattern, the cryorolled Al 5083 alloy has a smaller crystallite size (15.85 nm) compared with as received (19.05 nm). The effect of variation tilt angle (1.5º, 2º, 3º) at 865 rpm were evaluated by measuring the tensile properties of cryorolled Al 5083 alloy. Based on the tensile strength result, the tilt angle 2º was chosen due to highest strength. Then, various rotational speed (600, 865, 1140, 1500) rpm was investigated on cryrolled Al 508 alloy and 865 rpm shows the highest tensile strength (224.21 MPa). However, tunnel defect was observed at 600 rpm. Then, as received and cryorolled Al 5083 alloy were welded at rotational speed (865, 1140, 1500) rpm. The comparison between as received and cryorolled Al 5083 alloy are made. Both hardness and tensile properties of as received and cryorolled Al 5083 alloy decreases with increasing rotational speed. In general, the hardness and tensile properties of cryorolled Al 5083 alloy are higher compared to as received. The highest hardness (49.1 HV) was obtained at nugget zone for cryorolled Al 5083 alloy at 865 rpm. For tensile test, the peak of yield and tensile strength was achieved by cryorolled sample at 865 rpm which recorded value of 145.61 MPa and 224.21 MPa respectively. The yield and tensile strength of cryorolled sample at 865 rpm improved about 13.36% and 1.14% than as received Al 5083 alloy. The enhancement of tensile strength value is achieved even considered only slight improvement counted as good progress. The fracture surface of the cryorolled sample after tensile test consisting of welldeveloped dimples over the entire surface which indicated fractured in ductile manner.
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