| Based on production researches on high strength B93 aluminum alloy, the properties and evoloution of microstructures of B93 alloy under various conditions were studied by using tensile testing, optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), differential scanning calorimetry (DSC) and X-ray diffraction, and the technology for heat treatment was optimized. Intensive studies were made on the fatigue property and fracture behaviours of B93 alloy bars, and the crystallographic mechanism of fatigue crack propagation were investigated by using electron back-scattered diffraction (EBSD) techniques. Besides, considering industrial production, the hot working process of this kind of alloy was studied by using thermal simulation techniques and the quenching process was investigated by combining ANSYS finite element modelling and experiments. Technics of hot working and solution, aging treatment obtained from these have already been applied to give directions in factory production. The research have come to the conclusion that:(1) The flow stress constitutive equation of alloy during pyroplastic deformation was established by carrying on thermal simulation researches of B93 alloy bars. Hence unstable flow areas in processing map have been determined and processing temperature and strain rate were optimized. The optimal processing parameter provide support for mass commercial production of alloy bars.(2) Finite element modelling of quenching temperature field of large scale B93 alloy bars contributes to determine the depth of quenching layer and critical cooling rate, and evaluate the quench sensitivity of alloy bars. Thereby the relationship among cooling rate, property and microstructure of large scale B93 alloy bars was established.(3) The S-N curve and equation of p-S-N curve (with a survivability of 99.99%) of B93 alloy bars were obtained from statistical analysis of mass fatigue tests data.(4) Mechanisms of fatigue crack initiation, propagation, and fracture were investigated by using fracture morphology observation and EBSD analysis of fatigue crack, and a new crystallographic model of fatigue crack propagation was given.(5) Stress distribution condition of B93 alloy bars with cracks was analyzed by ANSYS finite element modelling techniques and the stress intensity factor was figured out. Combining the stress intensity factor and K criterion, the motion state of crack could be revealed, which helps evaluate safe reliability of B93 alloy bars.
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