Preparation Of High Quality Al-5Ti-1B Alloy Wire And The Study On Refinement Performance

Grain refinement is an important tool to improve the mechanical properties and the quality of materials. Currently, Al-Ti-B alloy wire used in aluminum industry is the largest grain refiner. However, due to its low purity, poor shape, size, and distributions of the second phase compound particles of TiAl3and TiB2, Al-Ti-B alloy wire is difficult to meet the requirements of production of high quality aluminum plate, strip, foil and profiles. This is the main disparity compared with the foreign products. Along with the development of aluminum processing industry, the more high quality of Al-Ti-B alloy has been required. Furthermore, there is an important significance in the development of aluminum processing industry to development high quality Al-Ti-B alloy of grain refiner.In this paper, to prepare high quality Al-5Ti-1B for goals, according to the industrial generic technology and grand science and technology special project of Guangdong province, the alloy preparation and wire Continues Casting and Extrusion (CASTEX) forming of Al-5Ti-1B were studied. Main work and results are as follows:(1) The effects law of the preparation process conditions on microstructure of Al-5Ti-1B alloy were obtained and the melt preparation process parameters were optimized by analyse of the melt reaction mechanism of Al-5Ti-1B alloy and study experiment of melt preparation. The optimal technological parameters were obtained as follows. The addition amount of villiaumite is more than5%to normal amount of calculation; the adding order of villiaumite is adding part of K2TiF6firstly and then adding K2TiF6and KBF4mixture; the reaction temperature is860-890℃; the reaction time is60-80min; alloying reaction need violent stirring.(2) The uniformity distribution of compounds particles in the alloy was effectively controlled after wire forming; the accumulation and precipitation of compounds particles were eliminated; melt purity of Al-5Ti-1B alloy was improved by electromagnetic stirring to Al-5Ti-1B alloy melt in the tundish. Temperature directly influences the viscous force, increasing electromagnetic stirring temperature make for uniform distribution of compounds particles and aggregate banding disappeared. Under the action of the electromagnetic stirring particles of TiAl3appear sleek round phenomenons. The best electromagnetic stirring temperature is800℃, stirring time is30min.(3) By using the Continues Casting and Extrusion (CASTEX) equipment to casting and extrusion forming, the alloy wires of Al-5Ti-1B which have advantages in good microstructure, smooth surface and no lateral cycle crack were obtained. Shear and rub moves function was strengthen in casting and extrusion process, which can cause spalling of edge and brittle fracture along the crack for TiAl3particles, finally, the compounds particles distribution in microstructure of alloy wire become uniform. The structures of TiAl3particle are massive and all the size is30-75μm. The structures of TiB2particle are small and evenly dispersing around TiAl3particles. The optimal processing parameters of Continues Casting and Extrusion (CASTEX) are as follows. Casting and extrusion temperature is800℃, pouring flow is200-250Kg/h, Volume of cooling water flow is10-15L/min, casting extrusion wheel speed is15r/min.(4) The effects law of microstructure of Al-5Ti-1B alloy, refinement temperature and refinement time on refining effect were obtained by study experiment of Al-5Ti-1B alloy wire on refining effect of pure aluminium. The optimal refinement temperature is690-710℃. The optimal refinement time is0.5-30min. It is further explicated that the optimal microstructure are angulatus massive, the size is30μm, the structures of TiB2particle are small and evenly dispersed, the size is0.5-1.0μm.(5) The composition and microstructure of Al-5Ti-1B alloy wires which are prepared by optimizing technological conditions of preparation, electromagnetic stirring and wire forming meet requirements of the high quality grain refiner. Through application test in industrial field the refinement effects of Al-5Ti-1B alloy wires are the same as imported similar products.