Process Design Optimization&Microstructure Control On Properties Of H-section7050Al Alloy Forging

H-section aluminum alloy forgings which are the key load-bearing parts of theaviation aircraft are widely used in aerospace areas and their work conditions areextremely bad. Therefore, these forgings are required to have excellent mechanicalproperties. H-section aluminum alloy forgings are typical aluminum web-rib forgingswhich usually contain under-filling, over-burning, coarse grain, broken fibers and otherflow line defects. Therefore, it is essential to improve the mechanical properties of suchforgings by the study of H-section aluminum forgings process and the forging processon the macroscopic characterization and the microstructure evolution of the forgings.The thesis comprehensively applies the forging process theory and numericalsimulation techniques to design the forging process and optimize numerical simulationof the H-section7050aluminum large forgings. The main research work andachievements include：1.Properties study of7050aluminum alloy. The author made hot compressionexperiment of7050aluminum alloy on Gleeble-1500hot simulator in the constanttemperature and strain. The author also studied the the influence of hot deformationparameters on the flow stress and dynamic recrystallization behavior. After that，basedon the results of hot compression experiment, the author establishes the materialconstitutive model and dynamic recrystallization model of7050aluminum alloy byregression analysis and other mathematical methods.2.Modified process research of7050aluminum alloy forgings based on numericalsimulation technology. Firstly, the author studies the material damage, equivalent straindistribution, dynamic recrystallization volume fraction and average grain size of7050aluminum alloy square blank on the basis of free forging process and finite elementtheory through the DEFORM-3D platform. Secondly, the thesis analyzes the influenceof the equivalent strain and deformation temperature on the dynamic recrystallizationvolume fraction and average grain size of7050aluminum alloy. After that,from theaspect of deformation zone change in the free forging, the author firstly proposed thereason that the multi-forging process could improve the plastic deformation of the blankand refine the grain size. Lastly, the thesis gets that the multi-forging process couldimprove the microstructure property of the7050aluminum alloy blank.3.Die forging process study and process-simulated optimization of H-section aluminum alloy forgings. Firstly, the author simulated the forming process of the H-typecross section of7050aluminum alloy forgings on the DEFORM-2D platform. In theprocess of non-using preform, the thesis researched the primary and secondary order ofprocess parameters affecting on the final forging quality and got the the combination ofoptimized process parameters using orthogonal experiments. In the process of usingpreform, the author firstly proposed the high-rib preform in the final forging andfocused on analysis of metal flow model in the different types of using preform process.Then, the thesis explains the reason of vortex and fiber break happened in the finalforging. Lastly, the author gets the optimized preform and die forging process throughselecting the simulation results.4.Trail production. The research results have been applied to the actual productionsuccessfully, which is essential to control the defects of H-section forgings and improvethe mechanical properties. It also provides a theoretical basis for the similar products.The above research work provides the optimized process for large H-section7050aluminum alloy forgings, it also provides a theoretical basis for actual production.