Study On Microstructure And Properties Of Cu-Ni-Sn Alloy Prepared By Twin-Roll Strip Casting

As a new sort of copper-based elastic alloy,Cu-Ni-Sn alloy has the characteristics of good tensile strength,excellent electrical conductivity and high thermal stability.It is mainly used for all kinds of elastic components in instruments and meters,such as contact springs,switches,connectors,terminals and other components.Due to the serious segregation of Sn element with low melting point,the alloy needs a long time of homogenization treatment and hot rolling process under the traditional production process.The production process is cumbersome and the process parameters are difficult to control,which limits the application of the alloy.After extensive exploration,it was found that increasing the solidification rate can eliminate alloy segregation and other problems,which is also a major direction for the development of the alloy.In this paper,according to the development status and trend of Cu-Ni-Sn alloy,the variation rules of solidification microstructure and properties of alloy at different solidification rates were studied,the process flow was optimized and transformation of process microstructure and properties were analyzed.The optimum process parameters of Cu-9Ni-6Sn alloy under sub-rapid solidification conditions were obtained.It provides feasible experimental data and theoretical analysis for the application of twin-roll strip casting technology in high performance copper alloy.The main research results are as follows:(1)The solidification microstructure and elemental segregation of Cu-9Ni-6Sn alloy produced by twin-roll strip casting,water-cooled copper mold and conventional casting technique were studied and analyzed in detail-It was found that increasing the solidification rate can greatly eliminate the casting defects and weaken Sn element segregation.(2)The Cu-9Ni-6Sn alloy produced by twin-roll strip casting process was solution treated,cold rolled and aging treated,and the microstructure and properties of the alloy under different conditions were analyzed.The optimum process parameters were obtained as follows:solution treatment at 850?-90%rolling reduction-aging treatment at 350? for 3h.Finally,the results show that the tensile strength is 1074MPa,conductivity is 14.46%IACS and Vickers hardness is 368HV.(3)The Cu-9Ni-6Sn alloy produced by twin-roll strip casting process was cold rolled and aging treated,and the microstructure and properties of the alloy under different conditions were analyzed.The optimum process parameters were obtained as follows:90%rolling reduction-aging treatment at 350? for 3h.Finally,the results show that the tensile strength is 1056MPa,conductivity is 14.36%IACS and Vickers hardness is 354HV.(4)By comparing the microstructure and final properties under solution treatment condition with these under non-solution treatment condition,it was found that the Cu-9Ni-6Sn thin strip produced by twin-roll strip casting can save the solution treatment process and further shorten the process flow.