The Research Of Large-diameter Aluminum Alloy With Series Of High Performance And Alteration Mechanism Of Residual Stress During Quenching

With microstructure design as the core,phase diagram - microstructure design - processing technology - properties is supposed as the main route for materials design.And the phase diagrams,corresponding phase transformation and phase of the Al-Zn-Mg-Cu alloy are calculated and characterized.All of these help the design of high strength,high modulus and high ductility aluminum alloys,and as an example the lager section jet spray aluminum alloy (Al-10.0Zn -3Mg-1.6Cu-0.8Ni-0.8Zr,Fe＜0.1 wt%,Si＜0.05wt%)is designed in the present paper.The optimum grain and particle size theory is proposed for design of high performance aluminum alloys.The matching of grain of matrix, precipitate and the solution extent is the core of high performance aluminum alloy.Based on the phase diagram,a homogeneous and fully recrystallized fine grain and the optimum matching of solution and precipitation sequence are obtained by long time three-stage solution treatment.The strength, ductility and modulus of the investigated alloy are improved together.An empirical equation for solution and aging treatment of the investigate alloy is proposed.A complete processing technology,especially the four-stage solution treatment and three-stage aging treatment,for the investigated alloy is developed in the present paper.The average ultimate strength of the investigated alloy by this series of processing technology is 770MPa;average yield strength is 730MPa,average elongation rate is 9%and average modulus is 75.5Gpa inφ150×260mm workpice.The mechanical properties are better than those of the alloy 7085,which is developed by US in 2002.The equations for description of the relationship between equipments play a critical role for computer control of jet spray equipments,which can improve the quality of ingots substantially.Five critical equations are proposed in the present paper,which made the foundation for computer control of jet spray equipments.A series of topological models are proposed for analysis of residual stress of aluminum workpieces,which completely discard the classical two-layer structure model by Japanese researchers in the 70s for investigation of residual stress.The thermal stress,plastic deformation and residual stress of quenched workpieces are systemically and thoroughly investigated with this series of topological model.The comer effect,quenching dynamic film effect, micro- and macro-plastic deformation mechanism due to quenching,driving force for plastic deformation,stress evolution pattem,the formation and distribution mechanism of residual stress and so on are revealed with the topological model.A completely novel system for investigation of residual stress is established.