.7050 Alloy During Hot Compression Deformation Behavior And Microstructure Evolution

In order to optimize the forming process for 7050 Al alloy component, the rheological properties and inhomogeneous deformation of alloy at high temperature have been extensively investigated with experiment and numerical simulation techniques. The microstructure evolution of 7050 Al alloy was studied by optical microscope(OM) and transmission electron microscope(TEM). The main contents are as follows:The thermo-compression experiments were conducted under different temperatures and strain rates to study the influences of processing parameters on the flow stress of 7050 Al alloy. The model for steady flow stress was proposed.The commercial software ,DEFORM-3D ,was adopted to simulate the hot compression test. The simulation result indicates that the distribution of effective stress, effective strain and temperature are uneven .The degree of homogeneity increases with increase temperatures and decrease strain rates.Results of the metallurgical analysis show that the microstructure of samples after compression is uneven too. The marginal grains are big and complete, but the inner grains are lengthened and staved. So it is best to choose the inner grains of deformed samples to observe and study the influences of hot deformation parameters on the microstructure of 7050 Al alloy. The grain size of large deformation region increases with increase of temperatures and decrease of strain rates.The results of TEM analysis shows that the sub-grains formed during the hot compression of 7050 Al alloy. The mean sub-grain size increases with the decrease of Z parameter, and there is a good linear relationship between the reciprocal of the sub-grain size and the natural logarithm of Z value. When temperature is 250℃, only the dynamical recovery(DRV) occurs and typical sub-grains appear. Dynamic recrystallization occurs when the temperature is higher than 350℃and recrystallized grains sizes increases with increase of temperatures and decrease of strain rates. The deformation parameters also play a very important role in the evolution of the configuration of precipitates and dislocation. The size and quantity of precipitates decrease with the increase of temperatures and decrease of strain rates.