The Study On Forming Behavior And Heat Treatment Process Of Cast-rolling7050Aluminum Alloy Sheet

7050aluminum alloy is an hardening alloy with a series of advantages such aslow density, high specific strength and toughness, good formability and processingproperty, lower cost,etc. And it has been widely used in aero field, transportation andother high stress structure parts requiring lightweight, high strength and goodcorrosion resistance.Wrought aluminum alloy sheets produce by traditional ingot casting-hot rollingmethod have higher price and low yield due to complex producing process and highenergy consumption. Strip casting is a promising route to directly produce aluminumalloy sheet by twin roll casting method. In recent years, the research and applicationof aluminum alloys have been attractive all over the world.In this paper,7050aluminum alloy was studied by lots of experiments onvertical twin-roll casting machine. The reasonable cast-rolling parameters weredetermined, and the7050aluminum alloy sheet of4mm×200mm was produced byvertical twin-roll casting machine. First, the defect of the7050aluminum alloy sheetand precaution were analysed, and microstructures and mechanical properties of thecast-rolling7050aluminum alloy were investigated by means of optical microscope(OM), scanning electron microscopy (SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), Vickers hardness test and tensile mechanicalproperties test.The results show that the ideal products of4mm thick cast-rolling sheet could beobtained by using conditions of casting speed12r/min and roller diameter300mm andcasting temperature943K. Microstructures of cast-rolling7050alloy sheet areinhomogeneous on the crossing section. From the edge to the center, grain sizedecreases gradually and microstructures become more homogeneous, showing atransition from dendrite to equiaxed grains. Microstructures in the edge or near thesurface have a lot of second phase particles while the center is few. Alloying elementshave a certain phenomenon of segregation. Vickers hardness of cast-rolling alloy is95.3HV and fracture mechanism is ductile fracture.Effects of solution and aging treatments on microstructures and properties ofcast-rolling7050alloy were analyzed. The results show that the second phaseadequately dissolves and strength increases when the alloy is solution treated at highertemperature for longer time. The second phase fully dissolve and strength reach thepeak at480℃and60min. When the solid solution temperature or the solid solutiontime further increase，the overheated structure appears in the alloy, the strengtheningeffect of dispersive phases decreases, and the strengthness gradually decreases. Theexcellent solution treatment system of cast-rolling7050aluminum alloy is480℃×1h,while hardness is185.5HV, tensile strength is422MPa, yield strength is361MPa.