Study On Deformation And Heat Treatment Technology Of Silver Copper Hollow Wire

Copper alloy has good conductive and heat conduction performance, but addition different kinds of alloy elements will has larger impact on electrical conductivity and mechanical properties, including silver element is the smallest one influence on performance of copper. This paper studies the silver content of 0.086% Cu-Ag alloy and focuses on the effects of extrusion, drawing deformation and the late heat treatment processes on the properties of its organization. And by studying the effect of technical parameters on microstructure and mechanical properties, we get the optimization process parameters, so that the resulting product has good strength and electric properties. By using the metallographic microscope and scanning electron microscope we observe on the microstructure and fracture morphology, and by using the ZEISS EVO MA 10 SEM with the Oxford EBSD system, we do the research of back scattering electron detection, and analyzing the grain orientation, by using the Metal conductivity measuring instrument, we work on measuring the electrical conductivity of alloy. The main results are as follows:The molding process of hollow Cu-Ag alloy conductor includes casting, extrusion, drawing and intermediate annealing. During the casting, the addition of rare earth alloy elements can refine the casting organization, and can achieve the goal of reducing inclusions. In the process of extrusion, we use the external model which both sides have ear grooves and the internal model which has the cross section for the circular perforation, it improves the stability of the product and yield. The design of different wall thickness structure of Cu-Ag alloy wire can not only help improve the heat dissipation rate, but also can reduce the skin effect.When the Cu-Ag alloy casting billet is processed for extrusion, its microstructure turns out to be isometric and the longitudinal and cross section have the same grain size, the average grain size is 19.7p.m. There are some twin crystals in the crystal grain, and its volume fraction is about 12.8%. At this point, the proportion of large angle grain boundary doesn’t appear to be much different than small one. Compared with the extrusion state, the grains are drawing out to be elliptic globular after wire drawing, the average grain size is 16.69μm,and the number of twin crystals is obviously reduced, turning out to be 0.363%. On this account that the microstructure orientation deviates from the random state, the small angle grain boundaries have the obvious rise, tensile strength and hardness of the Cu-Ag alloy are significantly increased, and the conductivity falls slightly. Upon annealing of the drawing samples, regeneration and recrystallization take place in the alloy, the size of grains is uniform, and the average grain size is 14.75μm. After intermediate annealing, the proportion of large angle grain boundary in alloy increases sharply, the internal alloy appears a large number of annealing twins, which possessed 23.2%. The intermediate annealing also makes the electrical conductivity of alloy increase, strength and hardness fall slightly, and material anisotropy weaken. The hardness of the finished product sample after a final drawing is 129.7 HV, the strength is 400MPa,and the conductivity is 99.5%IACS.Silver-copper alloy after drawing with different heat treatment system study, we concluded that, annealing above the recrystallization temperature of copper silver alloy (370℃ to 570 ℃) and thermal insulation 1.5 h, microstructure have no obvious change, strength and hardness in the range of three fluctuations, conductivity remains the same, we can think that these temperatures of recrystallization annealing have little impact in the performance of silver copper alloy. When the temperature is 370℃ or 570 ℃,holding time were 0.5 h,1.0 h,1.5 h,2.0 h and 2.5 h, respectively, for heating treatment of the same deformation alloys, we found that the strength and hardness of the alloy is the lowest at 1.5 h. That is to say, when the holding time was 1.5 h, work hardening phenomenon of alloy eliminate thoroughly. So, middle annealing by 370 ℃×1.5 h heat treatment process parameters during drawing deformation process, the subsequent low drawing force can be realized in deformation process. In a word, the intermediate heat treatment process can be optimized for 370℃×1.5 h. Compared with the heat treatment process parameters, both reduces the energy consumption and improves the production efficiency.