| The light gauge foil has series of characteristics, such as light, well cladding, poisonless and tasteless, anti-ultraviolet etc, and it has been widely used in packaging field. Its main problem is high pin-porosity. However, the pin-porosity of light gauge foil is significantly influenced by the size of the second phases and grains, solid solution quantity of alloying elements in foil stock. The production of1235light foil stock by cast-rolling is a promising manufacturing method with the advantages of short technological process, less investment in equipment, high production efficiency and low energy consumption in production etc. But it also has some disadvantages, such as there are many coarse second phases in the central layer of the foil stock and high solid solubility of Fe and Si, which increase pin-porosity of light gauge foil. However, anneal promotes the coarse second phases to disintegrate and solid solubility of elements to precipitate.In this paper, optical microscope, scanning electron microscopy, mechanical properties and other analysis and test means were used to systematically investigate the influence of annealing on the size of the second phase and grains of1235alloys light gauge foil stock, in order to reduse the quantity of the coarse second phases, decrease the content of alloying elements, and control the size of grains, thereby improve the quality of1235light gauge foil stock by cast-rolling.The results show that the grains morphology in the surface layer of7.0mm cast-rolled aluminum stock are slender lamellae, while coarse column in the center layer.The second phases in the surface layer are fine and their morphology are spherical,while most of second phase in the center layer are skeletal a(AlFeSi) phases and stripy βp(AlFeSi) phases.The matrix contains many skeletal a(AlFeSi) phases and stripy βp(AlFeSi) phases when annealing temperature is below530℃of cold rolled sheet with38.6%deformation. When annealing temperature is530℃, the skeletal α(AlFeSi) phases disintegrate into spherical particles while most stripy βp(AlFeSi) phases convert into small rod-shaped compounds, and the size of residual βp(AlFeSi) phases shortened to8～10μm. When annealing temperature is560℃, the matrix appears acicular FeA13phases, and the grains grow abnormally, that is disadvantageous for reducing pin-porosity of light gauge foil.The skeletal a(AlFeSi) phases has been disintegrated completely while there are some residual strip βp(AlFeSi) phases in the matrix when annealing at530℃with heat preservation for6hours of cold rolled sheet with38.6%deformation. When heat preservation time is10hours, most of the strip βp(AlFeSi) phases convert into small rod-shaped compounds, and the size of residual βp(AlFeSi) phases shortened to8～10μm. When prolong heat preservation time, the decomposition trend of strip βp(AlFeSi) phases is indistinctive. Therefore the best homogenization annealing process of cold rolled sheet with38.6%deformation is that annealed at530℃for10hours.When cooling in water after annealing at530℃for10hours of cold rolled sheet with38.6%deformation, the second phases whose size between1～5μm occupy64.2%, this percent is60.1%when cooling in stove, and68.3%when cooling in air.4.3mm aluminum sheet without homogenization annealing is cold rolled to0.45mm, the matrix contains many coarse second phases, and the tensile strength of the sheet is194.2MPa, while the elongation is4.0%. However, the aluminum sheet after homogenization annealing of530℃for10hours is cold rolled to0.45mm, the tensile strength of the sheet is192.9MPa, while the elongation is4.7%. Compared with the sheet without homogenization annealing, the tensile strength of the sheet after homogenization annealing has not changed distinctly, while the elongation improves17.5%.4.3mm aluminum sheet after homogenization annealing of530℃for10hours were cold rolled with59.3%and89.5%deformation, then intermediate annealed. The results show that the second phases precipitate more and grains grow slowly as annealing temperature rising when the sheet of89.5%deformation anneal between320～360℃. And when intermediate annealing temperature is360℃, the second phases precipitate most and there size between1～5μm occupy87%, the average size of grains is47.6μm. As annealing temperature rising continuedly, the second phases whose size greater than5μm increase, and the grains grow obviously. As the sheet with89.5%deformation intermediate anneal at360℃with heat preservation time between4～8hours, the second phases precipitate gradually. When heat preservation time is8hours, the second phases precipitate most, and prolong heat preservation time, the second phases don’t precipitate anymore, and the second phases whose size greater than5μm increase. Therefore the best intermediate annealing process of cold rolled sheet with89.5%deformation is that annealed at530℃for10hours.When the sheet with59.3%deformation intermediate anneals at360℃for8hours, the second phases whose size between1～5μm occupy67.1%, this proportion is lower than sheet with89.5%. Therefore it should appropriately increase the deformation of aluminum sheet before intermediate annealing.When the light gauge foil stock with46.7%deformation and H14state anneals at200℃, the matrix precipitate many granular second phases whose size are less than1μm. When annealing temperature raises to220℃, the precipitation is maximum, the second phases whose size between1～5μm occupy78.6%. And when annealing temperature is higher than220℃, the precipitation don’t increase anymore, and the second phases grow. When the light gauge foil stock anneals at200℃for10hours, the second phases begin to precipitate. When the heat preservation time is12hours, the precipitation is maximum, while the precipitation don’t increase anymore when the heat preservation time is longer than12hours. |
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