| Copper alloy is one of the most widely used metal materials, its main application field is electrical and electronic industry, which accounts for over 50% of copper consumption. It’s used as the basic materials in the production and manufacture of cables, switches, circuit boards and electrical products. At the same time, in the production of mechanical and vehicle are mainly used for production of industrial valves and fittings, instrumentation, bearing, high temperature resistant mold, heat exchangers. However, using the traditional method of casting copper alloy is prone to forming casting defects such as shrinkage cavity, segregation and porosity with poor organization uniformity, which seriously affected the use performance and service life of copper alloy. At the same time, due to the high melting point of copper alloy, there exists fatal problem of short service life mould in the process of extrusion casting.Semi-solid processing technology with the advantages of short process flow, stable filling process, low energy consumption, long service life of mould, is considered to be the most promising materials processing and forming methods in the 21st century. The organization of parts fabricated by this method is dense, with good mechanical performance easy to machining, near-net shape reducing amount of machining in the mechanical processing. The key problem of the method is the semi-solid slurry preparation.Processing the copper alloy by the semi-solid forming technology can lower the temperature of mould and significantly improve the service life of mould, and improve its service life and application scope by improve the organization uniformity of the copper alloy. This paper used rotating-rod induced nucleation to fabricate semi-solid slurry of CuSn10 alloy, and obtained parts from extrusion forming on semi-solid slurry. The main research content is as follows:Rotating-rod induced nucleation was used to fabricate CuSn10 alloy semi-solid slurry and analyze the effect of rod diameter, rod rotating speed on the semi-solid slurry microstructure. Results show that rotating-rod induced nucleation had obvious promotion nucleation function in CuSnlO alloy melt solidification, refined the α-Cu phase, eliminated the dendritic structure, and significantly improved the uniformity of organization. However, semi-solid slurry micro structure obtained is different with different experimental parameters. Compared with slurry fabricated by (?)45mm stainless rotating rod in same rotating speed, grain refinement and balling effect of in billet microstructure is better obtained from (?)75mm stainless rotating rod, organization distribution is more uniform. Comparison of slurry fabricated at different speed from (?)75mm stainless rotating rod shows that with the increasing of rod rotating speed, rotating-rod induced promote nucleation effect strengthen at first and weaken afterwards, not simply strengthen gradually. When pouring temperature is 1080℃ (low superheat state), with the rotating speed of 500 r/min, grain refinement in billet microstructure is best, and average grain diameter is 42.3 μm, at the same time liquid rate in organization is as high as 23.2%.Extrusion forming process on alloy semi-solid slurry was used to analyze influence on the microstructure and tensile strength of parts under different pressure and forming speed. Results shows that, at the same forming speed, with the increasing of pressure, tensile strength of parts increases. Under the same pressure, with the increasing of forming speed, tensile strength of parts increases. Compared with the liquid extrusion forming, the tensile strength of semi-solid extrusion forming improved from 183.1MPa to 232.4MPa, up by 26%, elongation rate from 2.97% increase to 12.1%, increased 4.1 times. According to tensile fracture morphology analysis, with increasing of pressure and forming speed, parts has denser organization tensile failure mode of parts is disintegrate fracture. |
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