The Effect Of Secondary Rolling On Microstructure And Mechanical Properties Of The Twin-roll Casting7050Aluminum Alloy

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 produced 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. The roll after rolling, the slab in second by secondrolling experiments, finally determining the specific rolling technological parametersand the organization structure are analyzed, and through the heat treatment processexperiment at last, making reasonable heat treatment process system. The resultsshow that:Secondary rolling technology is an effective method of improvement of7050aluminum alloy plates. After the five pass rolling, the plate is obviously thinning. Itcan improve many defects with the plate. Along with the increase of the reduction ofrolling process, for different grain by bulky isometric into long strips of grain, grainelongated in the rolling process, grain size have obvious deformation phenomenonand reply recrystallization happens, at the same time, the separation of aluminum andcopper are significantly reduced. Secondary alloy after rolling cross-sectional andlongitudinal and cross section of grain size, most elongated, slits grain, and at grainboundary and internal also have aluminum copper phase precipitation.With higher solution temperatures and longer solution duration, the solubility ofthe alloys become higher, the quantity of bulky second phase in the structuregradually reduce, the size also become smaller. The tensile strength, the yield strength,the elongation and the microhardness of alloy are all showed a trend of rising. It can’tgive full play to the next step aging reinforcement, when solid solution temperature istoo low, the time is too short and solid solution is not fully. The suitable crafts forsolid solution treatment are490℃×60min（ReL=274.5MPa, Rm=486.4MPa, δ=15%）and510℃×100min（ReL=284.7MPa, Rm=526.8MPa, δ=19.5%）.