Study On Weldability Of High Strength And High Conductivity Copper Alloy

High-strength and high-conductivity Cu-Cr-Zr alloy is the new functional structure material in recent years, it has the characters of high strength, good plasticity and excellent conductivity, and it has a wide range of application in the industrial field. In this paper, ANSYS software was firstly adopted to simulate and analysis the flat butt TIG welding dynamic temperature field of a typical Cu-Cr-Zr alloy.The double-ellipsoid is chosen as heat source models,and used command to apply load of moving heat source .The transition grid of meshes are used,also the impact of phase change latent is considered adequately.Besides,the varying thermal and mechanical properties with temperature varying are taken into account in simulate the temperature field under different welding parameters.According to the numerical simulation results of Cu-Cr-Zr alloy welding temperature field,worked out the corresponding welding parameters.Welding process test was carried out for Cu-Cr-Zr alloy by TIG welding. The optical microscope,scanning electron microscopy(SEM) with energy dispersive spectrometer(EDS) and hardness, tensile Strength, conductivity test and other modern test measurements were applied to research the influence of TIG welding on microstructures,mechanical properties and electrical properties of welded joints of Cu-Cr-Zr alloy. And the influence and variation of different postheat treatment on the microstructures , mechanical properties and electrical properties ,identified the best postheat treatment process parameter.The results shown that:the tension strength of Cu-Cr-Zr alloy welding joint decreased from 400MPa to 224.74MPa.The hardness of welding joints declined seriously, this indicated welding joints was softened,and considered that overageing is the main reason of softened.The specific conductance of Cu-Cr-Zr alloy welding joint decreased from 80%IACS to 68.09%IACS,and analysis the reason of specific conductance decreased.The heat treatment test at different temperatures solution 1h and different temperatures aging 1～4h were carried out on the welded joints. The results indicated that the best postweld heat treatment of Cu-Cr-Zr alloy welded joint was solution at 950℃for 1h and aging at 450℃for 3h.The hardness of weld zone and heat-affected zone of Cu-Cr-Zr alloy welding joint was increased greatly,the tension strength increased to 324.23 MPa,the specific conductance increased to 78.42%IACS,close to the level of base metal .By observing microstructure of welded joints discoveryed the welding joint could get small and uniform crystalline grain,high-density twin crystal,quantity and small precipitated phase.Fracture analysis showed that the welded joint welded breaked in the weld zone,break mode was ductile rupture,the welded joints breaked in the fusion area under heat treatment condition,break mode was ductile rupture and transcrystalline fracture.The energy spectrum analysis show that welded joint Cu matrix not has Cr particles precipitated.After heat treatment, Cu-Cr-Zr alloy fracture dimples have much small Cr particles dispersed precipitates in the form of precipitation distribution in the matrix,certified the Cu-Cr-Zr alloy was strengthened by precipitation of Cr particles and high-density twins together to achieve.