Research on Smelting and Casting Technology of High-Quality 7050 Aluminum Alloy Large-Sized Slab for Aerospace Applications
7050 aluminum alloy is widely used in aerospace structural parts because of its low density,high strength and excellent thermal processing performance.However,the problems of hot tearing,difficult forming,severe microporosities and oxidation inclusions within slabs have been existed in the semi-continuous direct-chill casting(DC)process of large-sized 7050 aluminum alloy slabs.In this study,the metallurgical quality control technology of alloy melt in the DC casting process of large-sized slabs was investigated,and the influence of melt refining process and grain refinement technologies on the quality of large-sized slabs were systematically explored,and the casting process of large-sized slab was also confirmed.The results show that,applying the optimized processes,the hydrogen and inclusion contents of the melt can be strictly controlled,and the grain sizes can be controlled at 1-1.5 grades when the grain refinement process with Al-Ti-C refiner was used for the alloy.High-quality melt alleviated the solidification shrinkage strain of the alloy,which solved the hot tearing behaviors of the cast slab ingots in a large proportion.Finally,a set of melting and casting process suitable for large-sized 7050 alloy slab ingot had been established.
7050 aluminum alloysemi-continuous direct-chill(DC)castingmelting and castinghot tearingmicrostructure
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