Effect Of Solution Temperature On Microstructure And Properties Of 2519A Aluminum Alloy Thick Plate Along The Thickness

2519A aluminum alloy has been widely used in tank armor,due to the characteristics of low density,high strength,excellent weldability and corrosion resistance.However,the uneven distribution of structure and performance in the thickness direction hinders the application of the alloy in the field of new generation tank armor.In this paper,2519 A aluminum alloy thick plate is taken as the research object,with the aim of improving the uniformity of the alloy thick plate,metallurgical microscope,scanning electron microscope and transmission electron microscope microstructure observation method and mechanical property test and other test methods are used.The variation of the thickness microstructure and properties of the alloy thick plate with the solution temperature along different thickness layers is analyzed,and the root cause of the difference in the alloy thickness and rolling properties with the solution temperature is proved..The following conclusions are drawn:(1)The microstructure and properties of different layers are not uniformly distributed.The aspect ratio of the grains of the alloy surface and intermediate layers is reduced from12.77 to 9.05.The area fraction of the coarse second phase increased from 2.10% to 6.30%from the surface layer to the middle layer.The average particle size of the thick alloy plate toward the middle chromatography and the size of the grain boundary precipitation-free zone are larger than the surface layer.(2)The fracture mechanism of alloys with different tensile directions is analyzed.Then The fracture model of the alloy in the thickness direction and the rolling direction was established,and the fracture model of the high-strength aluminum alloy with grain boundaries,grain structure and the second phase was established.The elongation of the alloy in the thickness direction is much lower than that in the rolling direction,and the difference is as high as 10.3%.Grain boundaries,uneven structure distribution and coarse second phase are the main reasons for the difference in ductility between the thick-stretched and rolled-stretched alloys.Due to the low hardness of the thick middle layer of the alloy,the deformation tends to concentrate in the middle.(3)The relatively better solution treatment process is 530?/2h.The thickness of the alloy thick plate changes from elongated fibrous to equiaxed with the increase of solution temperature.The difference in grain size of different layers along the thickness gradually decreases,and the structure tends to be uniform.Compared with the solution process at510?/2h,the yield strength and tensile strength of the alloy plate in the thickness direction of this solution treatment process are improved by 13.3% and 15.9%.The thickness of the alloy thick plate changes from elongated fibrous to equiaxed with the increase of solution temperature.The difference in grain size of different layers along the thickness gradually decreases,and the structure tends to be uniform.At the same time,the difference in the unevenness of the alloy thickness to the different layers of the structure is reduced at this solution temperature,and the soluble particles in the intermediate layer are fully dissolved,which increases the alloy thickness elongation,but the increase is not obviously.The residual phase of the middle layer with a large volume fraction is the fundamental reason for restricting the thicknesswise ductility of the thick alloy plate.