| dc.description.abstract | The aim of this study was to investigate the tensile and fatigue properties of as- extruded aluminum alloy, 7005.
Regrading to tensile properties, specimens were tested at higher strain rate (1.85x10-2 s-1) and lower strain rate (1.85x10-4 s-1) and showed the effects on the UTS, YS and elongation. As the experimental results indicated, the strain hardening effect under higher strain rate was more obvious and both the UTS and YS were higher. The polygonization of dynamic recovery under lower strain rate deformation resulted in subgrains stretched by tensile stress. So the elongation was higher, too.
In the part of fatigue property, the relationship between fractography and microstructure of specimens under two levels of repeated stress(240 MPa、180 MPa) was analyzed. As the experimental results indicated, the existent inclusion particles near specimen surface had a great influence on fatigue life. During the plastic deformation process, if dynamic recovery and polygonization occurred in the specimens, the grains were softened and the fatigue crack was transgranular fracture. Then the fatigue striations showed. If dynamic recrystallization occurred, the microstructure showed fine grains and the fatigue crack was intergranular fracture. The rough fracture surface was observed. Finally the statistical analysis of reliability, Weibull distribution function, was utilized to predict the fracture probability and fatigue life. | en_US |