A Study On Microstructure And Texture Of Aluminum Alloys During Rolling And Recrystallization Annealing

Aluminum alloy has low density,high strength to weight ratios,excellent ductility and good formability,therefore,this structural material is widely used in electronics,space technology,chemical industry,building industry,and transportation industry.Aluminum alloy is now the second largest used metal material,next only to steel.The specific orientation or crystallographic texture of aluminum alloy sheets formed during thermomechanical and recrystallization process play an important role in the mechanical property of the sheets.In order to better understand the texture evolution during plastic deformation and recrystallization,many researchers have focused on the investigation of the macro/micro deformation and recrystallization behavior in polycrystalline.In this present work,an attempt has been made to study the microstructure and texture of DC 1050 aluminum alloy,CC 2037 aluminum alloy and DC 5182 aluminum alloy during cold rolling and recrystallization annealing.Microstructural evolutions and orientation rotation behavior taking place during cold rolling at room temperature are studied in polycrystalline 1050 aluminum alloy.Variations in grain boundary characteristics,such as misorientation and grain boundary distribution,during in situ plane compression are analyzed statistically using EBSD equipment system.Orientation rotation behavior in individual grains is traced during the whole deformation process.As the rolling reduction increased,the average misorientation angle of the grains increased,while the corresponding misorientation distribution widens.The spread level of the grains is related to the initial orientation,the rotation path is rather long when the initial orientation is far away from the β-fiber components.Whereas the rotation path is rather short and the spread level of the grains is small when the initial orientation is in the vicinity of the β-fiber components.The deformation of the grains is inhomogeneous in the early stage of plastic deformation,the local strain is obvious by grain boundaries and in triple junctions;the results in this work also indicate a way by which the RD r-cube orientation transforms into the S orientation,ND r-cube orientation transforms into the copper orientation and brass orientation,and meanwhile the ND r-cube orientation transforms into the Goss orientation and R orientation to the S and C orientations during cold rolling.The texture evolution of continuous cast(CC)AA 2037 aluminum alloy during cold rolling was investigated by X-ray diffraction as a function of the precipitation state.The deformation microstructure is typical,the rolling texture consists of β fiber rolling texture;after solution treated at 500°C for 2 hours,the recrystallization texture strong cube texture.The electrical resistivity decreased while the amount of the precipitates increased during the aging process;the hardness of CC 2037 aluminum alloy reached the peak value at the aging time of 24 days.The evolution of rolling texture was quantitatively analysed by mathematical formulas,and it is indicated that the rate of disappearance of the cube + r-cube component decreased during aging,and that the said rate of the remainder component slightly decreased with increasing aging time.At large strains the ?? and ? precipitates enhance significantly the rate of disappearance of the remainder component.In summarise,the evolution rate of theβ fiber rolling texture barely changed during aging.The state of precipitation has a significantly effect on the distribution of orientation intensities along the β fiber.With increasing aging time,more initial cube-oriented grains are rotated to the C orientation rather than the B orientation,which leads to a more rapid increase in the intensity of the C orientation with increasing rolling reduction.The investigation on the effect of precipitation state on recrystallization behaviour of continuous cast(CC)AA 2037 aluminum alloy showed that the size of recrystallization grains slightly changed during aging,and the delay of recryastallization can be attributed to the precipitates.While for the SHT CC 2037 hot band with and without pre-deformation,the recrystallization texture was consisted of cube and R components,the major decrease through ageing was for the cube component,but increased the R component.Meanwhile,it is observed that the cube and R components were reduced with the increasing of the annealing temperature,and it is more obvious at higer temperatures.However,the intensity of the recrystallization texture was very low,and the recrystallization texture was consisted of 22.5° ND r-cube and R components for the alloy without SHT.After aging for 50 days,the recrystallization texture was consisted of cube component and R component.The investigation on the effect of initial grain size on cold rolling process of 5182 aluminum alloy showed that the fine-grained alloy recrystallized more rapidly than the coarse-grained alloy since initial grain boundaries were favored nucleation sites which led to more homogeneous recrystallized microstructure than in the coarse-grained alloy.Shear bands and transition bands were more readily formed in the coarse-grained alloy than in the fine-grained alloy,and inhomogeneous distribution of nuclei led not only to a slow decrease of the YS and UTS with increasing annealing temperature,but also to a marked inhomogeneity of recrystallized grains.The rolling texture of the fine-grained alloy consisted of the ? fiber,Goss and remaining cube components,while the coarse-grained alloy exhibited a much stronger ? fiber rolling texture.The strong S and C components in the rolling texture of the coarse-grained alloy could be attributed to the formation of shear bands.The recrystallization texture of the fine-grained alloy was characterized by the R component and the cube orientation with some scattering about the rolling direction(RD)towards the Goss orientation,while the recrystallization texture of the coarse-grained alloy exhibited the 22.5° normal direction(ND)rotated cube orientation and the R′ component deviated from the R component.The formation of 22.5° ND rotated cube and R′ textures could be attributed to the inhomogeneous deformed microstructure and unique rolling texture.