The static and fatigue properties of 7B04 aluminum alloy structures connected by riveting and refill friction stir spot welding(refill FSSW)were compared and analyzed.Results show that the static compression load of t...The static and fatigue properties of 7B04 aluminum alloy structures connected by riveting and refill friction stir spot welding(refill FSSW)were compared and analyzed.Results show that the static compression load of the typical structure connected by riveting and refill FSSW fluctuated in the range of 117-124 kN,and the shear load was in the range of 89-95 kN.Welds spacing had a small influence on the static load of the structures joined by refill FSSW.However,the fatigue life of riveted structures was lower than that joined by refill FSSW.For the welded structure,the heterogeneous microstructures of the welded joint led to the uneven microhardness,and the hook at the lap interface bent upwards at the same time.These factors made the welded structures during the fatigue test failure along the path of sleeve moving.展开更多
In this paper, several widely applied fracture criteria were first numerically examined and the crack-tip-region Jntegral criterion was confirmed to be more applicable to predict fracture angle in an elastic-plastic m...In this paper, several widely applied fracture criteria were first numerically examined and the crack-tip-region Jntegral criterion was confirmed to be more applicable to predict fracture angle in an elastic-plastic multiphase material. Then, the crack propagation in an idealized an elastic-plastic finite element method. The variation dendritic two-phase AI-7%Si alloy was modeled using of crack growth driving force with crack extension was also demonstrated. It is found that the crack path is significantly influenced by the presence of α-phase near the crack tip, and the crack growth driving force varies drastically from place to place. Lastly, the simulated fracture path in the two-phase model alloy was compared with the experimentally observed fracture path.展开更多
An attempt to investigate the mechanical response to the torsional load, torsional tests of TiA1/steel brazed joints were conducted at room temperature. The TiAl/steel joints used in the torsional loading tests were b...An attempt to investigate the mechanical response to the torsional load, torsional tests of TiA1/steel brazed joints were conducted at room temperature. The TiAl/steel joints used in the torsional loading tests were brazed under the optimum parameters of 1 173 K and 300 s. Torsional strength, fracture path and the behavior of the reaction phases were studied. The results show that the average torsional strength of the joints with the diameters of 13mm, 16 mm and 20 mm is 136 N · m, 270 N · m and 490 N · m, respectively; which is 81.9% , 85.5% and 86. 2% of the TiAl base metal, respectively. Fracture path and crack propagation process analysis shows, when subjected to the torsional load, Ag-based solid solution is deformed and cracks germinate at the interface of Ag-based solid solutioa/AlCu2 Ti particles or Ag-based solid solution/AlCu2 Ti layers, grow up and propagate into the Al-Cu- Ti brittle reaction layers, then propagate into the TiAl base metal, subsequently result in failure.展开更多
文摘The static and fatigue properties of 7B04 aluminum alloy structures connected by riveting and refill friction stir spot welding(refill FSSW)were compared and analyzed.Results show that the static compression load of the typical structure connected by riveting and refill FSSW fluctuated in the range of 117-124 kN,and the shear load was in the range of 89-95 kN.Welds spacing had a small influence on the static load of the structures joined by refill FSSW.However,the fatigue life of riveted structures was lower than that joined by refill FSSW.For the welded structure,the heterogeneous microstructures of the welded joint led to the uneven microhardness,and the hook at the lap interface bent upwards at the same time.These factors made the welded structures during the fatigue test failure along the path of sleeve moving.
文摘In this paper, several widely applied fracture criteria were first numerically examined and the crack-tip-region Jntegral criterion was confirmed to be more applicable to predict fracture angle in an elastic-plastic multiphase material. Then, the crack propagation in an idealized an elastic-plastic finite element method. The variation dendritic two-phase AI-7%Si alloy was modeled using of crack growth driving force with crack extension was also demonstrated. It is found that the crack path is significantly influenced by the presence of α-phase near the crack tip, and the crack growth driving force varies drastically from place to place. Lastly, the simulated fracture path in the two-phase model alloy was compared with the experimentally observed fracture path.
基金This work was supported by the National Natural Science Foundation of China （ No. 50975062）, the Science Foundation of Educational Department of Jiangxi Province （ No. GJJ13064）.
文摘An attempt to investigate the mechanical response to the torsional load, torsional tests of TiA1/steel brazed joints were conducted at room temperature. The TiAl/steel joints used in the torsional loading tests were brazed under the optimum parameters of 1 173 K and 300 s. Torsional strength, fracture path and the behavior of the reaction phases were studied. The results show that the average torsional strength of the joints with the diameters of 13mm, 16 mm and 20 mm is 136 N · m, 270 N · m and 490 N · m, respectively; which is 81.9% , 85.5% and 86. 2% of the TiAl base metal, respectively. Fracture path and crack propagation process analysis shows, when subjected to the torsional load, Ag-based solid solution is deformed and cracks germinate at the interface of Ag-based solid solutioa/AlCu2 Ti particles or Ag-based solid solution/AlCu2 Ti layers, grow up and propagate into the Al-Cu- Ti brittle reaction layers, then propagate into the TiAl base metal, subsequently result in failure.
