Study On Microstructure, Properties And Stress Relaxation Behavior Of Cu-Zn-Al-Ni-Co Alloy

The reason why the use of the phosphor bronze is limited is because it has some disadvantages,such as high cost,difficult to heat processing,easy segregation and so on.For the elastic materials,such as tin phosphor bronze,stress relaxation is the main form of failure in the process of use.Therefore,it is significant to study the subsitution of phosphor bronze and its stress relaxation behavior.This paper aims to add three different ratios of Nickel and Cobalt on the basis of Cu-22.7Zn-3.4Al alloy.Cu-22.7Zn-3.4Al-0.1Ni-0.5Co,Cu-22.7Zn-3.4Al-0.3Ni-0.3Co and Cu-22.7Zn-3.4Al-0.5Ni-0.1Co were prepared.The total amount of Nickel and Cobalt is 0.6%,and the ratio of Nickel and Cobalt is 0.2,1 and 5,respectively.The influence of different Nickel and Cobalt on the microstructure and mechanical properties of the alloy was also discussed.By analysising the microstructure and mechanical properties of he three alloys in diffrent states,such as in casting,hot rolling,hot rolling annealing,hot rolling annealing,rough rolling,rough rolling annealing,intermediate rolling,intermediate rolling annealing and finish rolling,we know when the ratio of Nickel and Cobalt is 1,the comprehensive performance of the alloy is the best,which means Cu-22.7Zn-3.4Al-0.3Ni-0.3Co alloy is better than the other two alloy.The tensile strength of the stress annealed strip up to 835 MPa,vickers hardness was 252,extension rate was 5.7%,elastic modulus was 125 GPa,conductive rate reached 18.7% IACS.The tensile strength,hardness and conductivity of the alloy exceed the phosphor bronze(tensile strength:700~800MPa,vickers hardness:170~210,conductive rate:13%IACS,elastic modulus:124GPa),which can partially replace the phosphor bronze.In this paper,the static strain gauge was used to measure the surface strain of the equivalent stress specimen The stress relaxation behavior and effect of temperature,initial stress and the ratio of Nickel and Cobalt were studied by analysising the stress relaxation curve.The results show that the alloy has good relaxation stability after 220?×1h stress annealing and the stress relaxation rate increases with the increase of the temperature,the initial stress and the ratio of Nickel and Cobalt Under the conditions of 80?,399.9MPa,the dynamic equation of the stress relaxation of Cu-24.7Zn-3.4Al-0.3Ni-0.3Co alloy is:?*=[1.3×10-9×(t+1.7)+1.21×10-6]-0.44.