High-purity high-homogenization casting method of magnesium alloy and magnesium-lithium alloy

Abstract

The invention discloses a high-purity high-homogenization casting method of magnesium alloy and magnesium-lithium alloy. The method comprises the following steps: (1) putting fully preheated magnesiumingots into a smelting crucible, and protecting the melt by adopting vacuum and inert gas; (2) performing electrifying to melt the magnesium ingots, adding alloying raw materials, keeping argon gas introduction in the feeding process, and adjusting the argon gas pressure to 1*10<5>Pa; (3) pushing the melt to carry out underflow type transfer injection by utilizing potential energy difference andgas pressure difference; and (4) carrying out homogenization solidification and waste heat homogenization on the melt. The invention realizes high-efficiency and continuous casting production of magnesium-lithium alloy ingot blanks and the casting. The reinjection process becomes simple and efficient by undercurrent reinjection. Through capturing of the valley bottom of a U-shaped solid-liquid interface in real time, the solid phase region at the lower part of the valley bottom of the solid-liquid interface starts to be homogenized at a constant temperature when the temperature of a core partis close to the solidus temperature, so that solidification shrinkage is reduced, and the cracking risk of a large ingot is greatly reduced.

Description

technical field [0001] The invention belongs to the field of melting and casting of magnesium alloys, especially magnesium-lithium alloys, and specifically relates to a method for melting and casting magnesium alloys, especially magnesium-lithium alloys, with high purity and high homogenization of ingots or castings. Background technique [0002] Magnesium alloy is the lightest metal structural material, and magnesium metal is a non-ferrous alloy variety with resource advantages in China. The development of magnesium alloy industry is for the independent controllability, upgrading, energy saving and emission reduction of national defense and military industry, transportation, new energy vehicles and electronic 3C is of great significance. Density of magnesium-lithium alloy (1.35~1.65g / cm 3 ) is lower than the usual magnesium alloy (1.74 ~ 1.91g / cm 3 ), the weight reduction effect is more significant. In particular, the crystal structure of the magnesium-lithium alloy with ...

AI Technical Summary

Problems solved by technology

Conventional magnesium alloy smelting systems are difficult to obtain high-purity and high-homogenization ingots or castings, and cannot meet the demand for high-quality magnesium alloys and magnesium-lithium alloys in high-end fields such as aerospace and biomedicine, mainly because the existing technologies still exist as follows: Disadvantages: (1) The use of flux for melt protection and refining will introduce flux slag, which seriously deteriorates the corrosion resistance and mechanical properties of the material; (2) The usual refining and filtering methods cannot filter out the oxidized slag to the greatest extent and flux slag, the filter is not easy to replace; (3) The usual pouring method is the melting furnace tilting pouring and the infusion pump transfer, which cannot form a stable static liquid level in the mold, and there are problems of turbulence and air entrainment, which is also not conducive to Realize automatic production; (4) Ingots obtained by conventional solidification methods often have serious internal and external structure inhomogeneity and solute area segregation, which affects the uniformity of mechanical properties and also seriously affects the uniformity of metal flow during subsequent plastic deformation Therefore, the dimensional accuracy of plastic processed products cannot be guaranteed; (5) when the cross-sectional size of the billet increases, the internal stress caused by solidification shrinkage increases, which may easily cause the billet to crack; (6) the usual vacuum melting will Placed in the same vacuum chamber, it is necessary to repeatedly vacuumize and fill inert gas treatment (washing treatment) during continuous production, which is not conducive to the realization of continuous production and the production of large-sized ingots. At the same time, due to the large volume of the furnace chamber, the vacuum The vacuum efficiency is low, and the vacuuming time of each furnace usually accounts for 50% of the total casting time, which seriously affects the production efficiency; (7) The usual homogenization process is to reheat the turned cold ingot below the solidus line, Causes energy consumption. For ingots with large cross-sectional dimensions, energy consumption is huge

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