Study On Preparation Of High-performance And Heat-resistant Al-Sc-Zr Wire By Continuous Rheo-extrusion And Cold-drawing

In this paper, Al-Sc-Zr alloy was studied and heat-resistant aluminium alloy conductor was prepared by continuous rheo-extrusion process, and then heat treatment and cold drawing was done. By studied on the effect of parameters of continuous rheo-extrusion process, heat treatment system and cold-drawing process on microstructure and properties of Al-0.12Sc-0.04Zr(wt.%) conductor, the following results are obtained.(1) 09.5mm Al-0.12Sc-0.04Zr(wt.%) conductors were prepared successfully by continuously rheologic extrusion machine (DZJ350), and the optimal process of Al-0.12Sc-0.04Zr(wt.%) conductor processing was obtained:the pouring temperature is about 730?; the gap between roller and boot is about 1-1.5 mm; the speed of roller is 0.275m/s; cooling water flow is 1.67×10-4m3/s. Under this condition, the tensile strength of Al-0.12Sc-0.04Zr(wt.%) conductor is 62MPa and the conductivity is 56.7%IACS.(2) Effect of solution treatment on metallurgical structure and properties of Al-0.12Sc-0.04Zr(wt.%) conductor was obtained. The average diameter of the grain size increases with the solution treatment time going and it is influenced by grain growth. Tensile strength affected by solution treatment is very small, and mainly affected by solution strengthening, recrystallization and stress relief; conductivity is imporved at the beginning, and then keeps a good level, it's influenced by the synthetic action of decomposition of primary phase Al3(Sc,Zr), the solution of Sc and Zr, the Static recrystallization and stress relieved.(3) Effect of aging on metallurgical structure and properties of Al-0.12Sc-0.04Zr(wt.%) conductor was obtained. Lots of secondary Als(Sc,Zr) precipitates are separated out. These precipitates with micro-twins (faults) structure are only lOnm, and grow with aging. The relationship between precipitates and Al-based is coherent, and the mismatch is only about 2%. With the 320? aging, tensile strength and conductivity of wire increases rapidly and keeps in a high level for a long time. Continuous rheologic extrusion Al-0.12Sc-0.04Zr(wt.%) wires were used as raw materials and the best heat treatment regime is:water quenching after 630?×1.5h solution treatment, then water quenching after 320?×1.5h aging. The tensile strength, elongation and conductivity of Al-0.12Sc-0.04Zr(wt.%) wire after heat treatmment is 169MPa,25.2% and 65.7%IACS. The heat test tensile residual rate of 230?×1h and 400?×1h is 100% and 99.38%.(4) Effect of cold drawing on metallurgical structure and properties of Al-0.12Sc-0.04Zr(wt.%) conductor was obtained. With the decrease of area reduction, equiaxed grain is elongated in the drawing direction until the formation of fibrous texture. Subgrains are formed by dislocation tangle. With the increase of deformation, tensile strength raises, elongation, conductivity and heat-resistance decrease.(5) 3mm,4.5mm,5mm,6mm,7mm,8mm heat-resistant aluminum wires which meet the AT1, AT3 and AT4 standard of "The Standard of Heat-resistant Aluminum Alloy wire for overhead conductor by EC" were prepared. Its tensile strength, conductivity and elongation is higher than the standard 13.8%?39.5%,0.5%?11.7%, and 1.7?5.65 times.