| Aluminum and its alloys are widely applied to air field because of their good characteristic which include low density, strong corrosion resistance, good fracture toughness and high fatigue strength. Defects appear easily in the metal components which work in harsh environment like high temperature, high pressure and high speed. The defects lead to fatigue failure that caused a great loss of life and property. So, determining the fatigue life of components that work in fatigue load has an important scientific guiding significance for the aeronautic aluminum alloys design and manufacturing.The fatigue life of 1933 aluminum alloys, from which S-N curves can be deserved, was tested with GPS 100 high-frequency fatigue machine in room temperature. In this test, sine loading and stress ratio that was 0.1 were adopted. Fatigue fracture morphology, initiation and propagation behavior of fatigue crack, fatigue fracture characteristics under different stresses, microstructure morphology and precipitate of 1933 aluminum alloys were studied by analysis methods of OM, XRD, SEM, EDS and TEM. The results of the study show that:(1) The fatigue limit of 1933 aluminum alloys (L direction, Kt=3, R=0.1) is 107MPa.(2) Fatigue Fracture Characteristics such as fatigue striation, fatigue step, secondary crack and toughening nest can be observed obviously in the fatigue fracture of 1933 aluminum alloys.(3) Higher amount of fatigue sources, bigger fatigue striation spacing and more fatigue steps which are much shorter and flatter can be observed in the samples under higher stress.(4) η phase strengthening is the main strengthening mechanism of 1933 aluminum alloys of T73 condition, grain boundary precipitate is η phase which is coarse and discrete, precipitate free zone can be observed obviously. |
PDF Full Text Request