Search

This study investigates the mechanical characteristics of friction stir processed dissimilar joints between AA5083 and AA6082 alloys reinforced with coal particles. Employing friction stir welding (FSW), the mean grain size measured 19.7 μm, but using the FSP technique with coal reinforcement (FSP + Coal) significantly refined the grain size to 8.75 μm. In flexural testing, FSW face samples exhibited failure at 12.7% strain and 535 MPa stress, while FSP + Coal face specimens showed diminished performance at 3% strain and 222 MPa stress. Similar trends were observed in root specimens. For FSW joints, the ultimate tensile strength (UTS) peaked at 145.90 MPa, with the lowest recorded UTS at 93.43 MPa. FSP + Coal joints reached a maximum UTS at 142 MPa and minimum UTS at 104.06 MPa. Fractures in both FSWed and FSPed samples occurred on the AA5083 side. In terms of hardness, FSW joints exhibited 80.33 HV, while FSP + Coal joints displayed a higher hardness of 83.66 HV at the nugget zone. Fracture surface morphology analysis revealed a prominent ductile failure mechanism for both FSWed and FSP + Coal joints. This study provides insight into the enhanced mechanical properties achieved through FSP + Coal processing, offering valuable implications for dissimilar alloy joints in various applications. [ABSTRACT FROM AUTHOR]

Aluminum alloys have been successfully used in the railroad and automotive industries because of their potential to significantly reduce component weights, and their good mechanical and anti-corrosion properties. Problems with joining aluminum alloys are characterized by low weldability, which influences the need for studies focused on unconventional methods. The environmentally friendly and low-cost friction-stir-welding method enables the material to be joined without melting. In the following study, dissimilar butt joints were produced from AA5083 and AA6060 alloys. A constant tool traverse speed of 100 mm/min and a tool tilt angle of 2º were used, combined with tool rotational speeds of 800, 1000 and 1200 RPM. It was revealed that as the tool speed increases, the hardness in the weld nugget zone increases, due to higher heat input and more effective recrystallization. The highest hardness of the weld nugget zone was observed for the weld that was produced with the highest tool rotational speed, and was equal to 1.07 GPa, compared to the hardness of both parent materials of 0.75 and 1.15 GPa for AA5083 and AA6060, respectively. Increasing the heat input also decreased the hardness of the heat-affected zone, where recrystallization was not observed. The lowest density of dislocations with the highest mobility was observed in the heat-affected zone on the AA6060 side, which also contributed to the reduction in strength in this zone. The produced welds exhibited corrosion resistance between both parent materials, with the lowest corrosion current density being 6.935 ± 0.199 µA·cm−2 for the weld that was produced at a tool speed of 1200 RPM. [ABSTRACT FROM AUTHOR]

The friction stir welding method is increasingly attracting interest in the railway sector due to its environmental friendliness, low cost, and ease of producing high-quality joints. Using aluminum alloys reduces the weight of structures, increasing their payload and reducing fuel consumption and running costs. The following paper presents studies on the microstructure, strength, and corrosion resistance of AA6082 aluminum alloy sheets joined via friction stir welding. The sheets were joined by employing two different traverse speeds (200 and 250 mm/min), two different rotational speeds (1000 and 1250 rpm), and two different tool tilt angles (0° and 2°). It was observed that the use of the inclined tool provides finer microstructure in the nugget zone, higher value of microhardness, and better corrosion resistance, compared to the tilt angle equal to 0°. By increasing the value of revolutionary pitch, finer grains are observed in the nugget zone and the measured hardness is higher. It was also observed that the change in process parameters strongly influences the radius of the nugget zone and the potentiodynamic properties of the friction stir-welded material. The joints produced with the tool tilt angle equal to 2°, the tool traverse speed of 200 mm/min, and its rotational speed of 1250 rpm revealed the highest hardness in the nugget zone (about 92% of the base material). Moreover, the finest grain size in the nugget with the average value of 9.8 ± 1.5 µm was found. The lowest corrosion current density equal to 16.029 µA cm−2 was noted for the sample with the highest strength, which also provides its good corrosion resistance. [ABSTRACT FROM AUTHOR]