| In practical engineering applications,2xxx(Al-Cu-Mg)aluminum alloy is widely used because of its low density,high strength,excellent molding and heat resistance and other characteristics,especially in aerospace,transportation,military equipment and other fields.At present,with the rapid development of aerospace,transportation and other fields,higher requirements have been put forward for the comprehensive properties of2xxx series aluminum alloys.The research on how to improve the strength of Al-Cu-Mg alloy while maintaining good plasticity has become a hot topic.Based on the 2024 aluminum alloy rod as the research object,through hardness test,tensile test and inter-crystalline corrosion test method,focuses on the aging before the pre-deformation of alloy microstructure,mechanical properties and the effect of intergranular corrosion performance,this experiment mainly adopts the way of prestressing is:cyclic strain,the pre-tension and single-compression deformation.The results are as follows:(1)The influence of cyclic strain on microstructure and properties of 2024 aluminum alloy was studied.The experiment was controlled by constant total strain amplitude and treated by cyclic strain of different cycles.After cyclic strain treatment,the tensile strength and yield strength of the alloy are significantly increased,but the susceptibility to intergranular corrosion is increased.With the increase of the number of cycles,the tensile strength of the sample increases first and then decreases,the yield strength gradually increases,the elongation continues to decrease,and the plasticity of the alloy becomes worse.The composite mechanical properties of N_f=500 with cyclic cycles are the best,and the tensile strength,yield strength and elongation are up to 616 MPa,423 MPa and28.2%.The alloy has high strength and good ductility,which is related to the dislocation cells generated in the matrix during deformation.After aging treatment at 150?and 190?,the degree of intergranular corrosion of cyclic strain samples increases.The yield strength,tensile strength and elongation all decreased in different degrees,which was related to the recovery of dislocation in the aging process.(2)The effect of pre-stretching on the microstructure and properties of 2024 aluminum alloy was studied.The pre-stretching rates were 0%,1%,4%and 7%,respectively.After pre-tensile treatment,the strength and hardness of the alloy increase,showing the phenomenon of deformation strengthening.The yield strength,tensile strength and elongation of the alloy increase first and then decrease with the increase of pre-tensile strength,and the intergranular corrosion depth increases gradually,and the corrosion degree increases.The tensile strength,yield strength and elongation of the sample with a pre-tensile ratio of 1%are 568 MPa,384MPa and 27.2%,respectively.The alloy has high strength and high elongation.After aging at 190?/20 h,the tensile strength and elongation of the pre-tensile samples decreased,while the yield strength increased.After aging at 150?/24 h,the yield strength and tensile strength of the samples decreased first and then increased with the increase of pre-tensile ratio,while the elongation increased.After aging treatment,the susceptibility of the pretension samples to intergranular corrosion decreases and the corrosion degree decreases.Deformation strengthening and aging strengthening are superimposed,and the strengthening effect is related to deformation degree,aging temperature and aging time.(3)The effect of single tension-compression deformation on the microstructure and properties of 2024 aluminum alloy was studied,and the deformation amounts were 0%,1%,4%and 7%,respectively.The results show that the strength and hardness of the alloy are increased and the plasticity has little change after pre-deformation.When the deformation degree increases,the tensile strength and yield strength of the alloy first increase and then decrease,the elongation is similar,the intergranular corrosion depth increases gradually,and the corrosion degree increases.The tensile strength and yield strength of the sample with 1%pre-deformation are 581 MPa and 404 MPa,respectively,and the elongation is27.9%.After aging at 190?/16 h,the yield strength,tensile strength and elongation of the samples all decreased.After aging at 150?/24 h,the tensile strength of the deformed samples increases.With the increase of deformation,the yield strength decreases first and then increases.The tensile strength,yield strength and elongation of the sample with pre-deformation of 7%are 583 MPa,455 MPa and 29.2%,respectively.After aging treatment under different regimes,the susceptibility of the deformed samples to intergranular corrosion decreases and the corrosion degree decreases. |
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