Study On Hot Deformation Behavior And Annealing Process Of Complex Tin-nickel Brass

As a functional material,copper-based elastic alloys are widely used in electrical and electronic,instrumentation,machinery,chemical and other fields due to their high strength,high elasticity and excellent electrical conductivity.The Cu-Zn-Sn-Ni alloy studied in this paper is a new high-performance elastic copper alloy.The complex tin-nickel brass formed by adding a small amount of elements such as Sn and Ni on the basis of ordinary brass has the characteristics of good performance,low cost,green environmental protection,simple processing technology,etc.,and can partially replace tin phosphor bronze and beryllium bronze in the applications of electronic components.In this paper,the hot deformation behavior,cold rolled hardening and annealing heat treatment process of Cu-Zn-Sn-Ni alloy were studied.Through the analysis of the microstructure and properties of the material after hot compression deformation,cold deformation and heat treatment,the reasonable preparation process parameters of Cu-Zn-Sn-Ni alloy were determined,which provided a theoretical basis for actual production process.The main results are as follows:1.According to the flow stress-strain curve of hot compression deformation,the thermal deformation behavior of Cu-Zn-Sn-Ni was studied.The results show that Cu-Zn-Sn-Ni is a kind of positive strain rate sensitive material,and the higher the deformation temperature,the lower the flow stress;the higher the strain rate,the higher the flow stress.The constitutive equation of Cu-Zn-Sn-Ni alloy is calculated by Arrhenuis equation.Based on the theory of dynamic material model(DMM)and the theory of Prasad processing map,the thermal processing diagram of Cu-Zn-Sn-Ni at 660-900? and 0.01s-1-10s-1 was established.Combined with the dynamic instability diagram and the power dissipation rate diagram,when the true strain is 0.6,the suitable processing region is mainly 800-900?,and the deformation rate is 0.01-0.1s-1.2.The Cu-Zn-Sn-Ni alloy was cold-rolled at different processing rates(0-83.3%),and the work hardening curve of the alloy was obtained.The recrystallization temperature of the alloy was determined,and the tensile strength,elongation,hardness and electrical conductivity of samples with different processing rates after annealing were tested and observed.The results show that the alloy has obvious work hardening effect after cold working deformation.When the processing rate is 80%at normal temperature,the tensile strength can reach 590MPa,the Vickers hardness can reach 186,the elongation is 5.6%,and the electrical conductivity can reach 28.2%IACS.The strength and hardness of the alloy increase with the increase of the deformation amount,and tend to be stable.The elongation,conductivity and deformation amount are oppositely changed.3.The tensile strength of Cu-Zn-Sn-Ni alloy with the processing rate was obtained by fitting the tensile curves of different deformation alloys.According to the fitting curve and the actual curve,the temperature at which the alloy begins to recrystallize under different deformation amounts is determined,increasing with the degree of deformation,the recrystallization temperature of the alloy is lower,the 80%deformation of the Cu-Zn-Sn-Ni alloy begins to recrystallize at temperature of 400-450?.The appropriate recrystallization annealing temperature and time for the 80%processing alloy is 500?,1 h.