Research On Hot Forming Property Of Al-2.2Mg-8.3Zn-3.3Cu High Strength Aluminum Alloy

7xxx alunminum alloy has been widely used in various fields of aerospace and industrial production due to its excellent mechanical properties.The jet forming technology based on RS/PM development can obtain the alloy with higher properties and lower segregation degree than the cast 7xxx alunminum alloy,but the cost is too high.By studying the confectionng of liquid forging of as-cast 7xxx aluminum alloy,the performances can be improved to some extent,which provides ideas for practical production.The metal processed by liquid forging process has the advantages of both cast state and forged state.It is an advanced forming process,can eliminate the defects of shrinkage cavity and porosity in the cast state and impose a certain plastic deformation.In this paper,we used hot forging,hot extrusion processing and liquid forging to research the influence of mechanical properties and microstructure evolution by these forming process,and choosed the heat treatment process by orthogonal experiement.According to the designing standard and the equipment we designed the extrusion die,then we designed the precasting liquid forging die according to exhaust and the elimination.According to Deform simulation revised hot forging and hot extrusion processing technology,we started the forming process of free forging,hot extrusion and liquid forging and designed the liquid forging heat treatment experiment table according the national standard.Under the same heat treatment process,the average tensile strength of hot forging increased from 401.78 MPa to 524.29 MPa,which is 30.49% higher than original state.The elongation increased from 0.35% to 1.05%,and the lamellar cleavage fracture changed to mixed fracture by electron microscope observing.After hot extrusion processing and heat treatment,the average tensile strength increased to 582.06 MPa,which is 44.87% higher than the original state,and the average elongation increased to 12.19%.The heat treatment changed the extrusion fracture from typical plastic fracture to intergranular fracture with mixed type.The distribution and size of the second phase were significantly affected by heat treatment by electron microscope and metallographic microscope.According to the orthogonal experiment results,we analysed the influence degree of solid solution heat treatment temperature,solution time,aging temperature,aging time on the mechanical properties and choose the best heat treatment which is 3 hours solution treatment in 465 ?and 16 hours aging treatment by orthogonal experiment and range analysis.Liquid forging can clear the shrinkage defect more than the primitive state organization and make it has most of the tiny equiaxial structure.Different from the un-formuniformly distributed at grain boundaries in original state,the form and size of second phase distribution becomed much and uniformly distributed when used the liquid forging.The tensile strength increased to 546.58 MPa,was increasing about36.09% more than original state,slightly better than hot forging state,and the extension rate also increased to 4.15%.The strengthening effect of liquid forging for this aluminum alloy was between that of hot forging and hot extrusion.