Magnesium alloy electromagnetic low-temperature semicontinuous casting method

Abstract

The magnesium alloy electromagnetic low-temp. semicontinuous casting method includes the steps of melting magnesium, adding compound fire-resisting elements, adding alloy elements, heat-insulating, standing still and semicontinuous casting under the electromagnetic field. It utilizes the addition of compound fire-resisting elements to implement smelting of magnesium alloy free from coverage or protection so as to shorten technological process and raise melt quality, and utilizes the application of electromagnetic field and optimization of crystallizer structure to implement the low-temp. and high-speed semicontinuous casting of magnesium alloy.

Description

Technical field [0001] The invention belongs to the technical field of magnesium alloy casting. Background technique [0002] The melting and casting process is an important process before the material is formed, and has an important genetic influence on the subsequent process of the material. Semi-continuous casting is an efficient billet-making process for magnesium alloys. Due to the flammability of magnesium alloys, a complex melting process is required; due to the magnesium hcp crystal structure and relatively low thermal conductivity, it is easy to cause coarse dendrites, composition segregation and thermal cracking. How to solve these problems is the key to obtaining high-quality cast ingots and subsequent forming of magnesium alloys. [0003] At present, the smelting method and casting process of magnesium alloy semi-continuous casting process have the following problems: [0004] Problems with the smelting method [0005] 1. SO 2 It has a stimulating effect on ...

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Problems solved by technology

[0005] 1. SO 2 It has a stimulating effect on the operator's respiratory tract; it is highly corrosive; when there is slag, SO 2 Gas instead causes combustion; liquid SO 2 It needs to be heated and vaporized and the temperature and flow rate should be strictly controlled, so there are many procedures and there is a danger of explosion;

[0006] 2. SF 6 The gas is non-toxic and tasteless, and is currently a commonly used protective gas for domestic and foreign enterprises. However, the gas has a greenhouse effect and will be decomposed into toxic gases during protection. Today, with the increasing calls for environmental protection, it is an urgent method to be replaced;

[0007] 3. Flux protection is easy to cause casting slag inclusion, which requires refined operation, which leads to several hours of standing operation, which greatly reduces production efficiency and product quality. Even so, it is difficult to avoid waste products caused by slag inclusion ; The surface of the billet obtained by the above method is seriously oxidized, showing rough, blackened surface, and requires a large amount of milling

[0009] 1. High casting temperature (730-750°C): the tendency of magnesium alloy to oxidize and burn increases; the solidification time is long, because magnesium alloy has low thermal conductivity (at 300°C, the thermal conductivity of pure aluminum

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