Magnesium and magnesium alloy casting device and method based on melt speed-controlled drop casting

A magnesium alloy and melt technology, applied in the control of molten metal pouring from ladles, ingot workshops, casting workshops, etc., can solve the problems of small solid phase diffusion coefficient, high equipment conditions, composition segregation, etc., and achieve suppression The degree of dendrite growth, the low degree of contamination introduction, and the effect of improving composition uniformity

Active Publication Date: 2022-03-29
XI AN JIAOTONG UNIV
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  • Application Information

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Problems solved by technology

On the one hand, the existing magnesium and magnesium alloy devices are mainly castings, and the ingots obtained by conventional solidification methods often have serious internal and external structure inhomogeneity and solute segregation, which seriously affects the stability of corrosion performance and mechanical properties. , which also makes it impossible to guarantee the uniformity of metal flow and the dimensional accuracy of processed products during subsequent plastic deformation; and magnesium alloy standard samples, the lack of standard samples and standard physical and chemical properties has seriously delayed its development
In addition, due to the active nature of magnesium and magnesium alloys, it is easy to react with oxygen, nitrogen, and water vapor in the air to form various solid slag inclusions; at the same time, because of its large volume shrinkage during the solidification process, it is easy to cause higher density porosity. Shrinkage cavity, its performance will be significantly deteriorated
[0004] For the uniformity of magnesium and magnesium alloy castings, homogenization annealing treatment (CN1775992A; CN 102586561A; CN 108441731A) is often used at present, that is, the castings are heated to 100°C-200°C lower than the solidus line and kept warm for a long time (the principle of metal solidification , Gao Yimin, Xi’an Jiaotong University Press, 2009), but due to the small solid-phase diffusion coefficient, it can only alleviate or eliminate microscopic dendrite segregation but cannot improve macroscopic segregation, and it often needs to cooperate with subsequent plastic processing methods to further homogenize
Patent applications CN 111057890A and CN 108645685B mentioned that in the solid-liquid coexistence two-phase region or in the solidification process, the diffusion can be accelerated by coupling electromagnetic field, ultrasonic field, electric field and mechanical vibration to achieve homogenization, but the required equipment conditions are relatively high
In addition, the problems of porosity and shrinkage cavity in the casting process of magnesium and magnesium alloys are mostly solved by sequential solidification or setting risers, but these methods will inevitably lead to obvious composition segregation, which is contrary to the requirement of composition uniformity

Method used

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  • Magnesium and magnesium alloy casting device and method based on melt speed-controlled drop casting
  • Magnesium and magnesium alloy casting device and method based on melt speed-controlled drop casting
  • Magnesium and magnesium alloy casting device and method based on melt speed-controlled drop casting

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0046] The raw material of this embodiment is 99.99% dendritic pure magnesium, in combination with the method described in the invention, adopt such as figure 1 Described device specifically comprises the steps:

[0047] Under the situation that no raw material is placed, close the exhaust valve 21, open the intake valve 23, open the vacuum mechanism 9, make the sealed cabin body 2 communicate with the vacuum mechanism 9, and make the pressure in the sealed cavity 2 be at 10Pa, at this time Set the temperature control mechanism 6 so that the temperature of the three stages of temperature control is kept at 200°C for 30 minutes, and then at 600°C for 120 minutes. After the heat preservation is completed, cool to room temperature.

[0048] 400g, 99.99% of loose dendritic pure magnesium is placed in the smelting zone 31, the filter mechanism 5 is set as a graphite plate containing 3 holes and the aperture of each hole is 8mm, at this time, the flow velocity control mechanism 4 is...

Embodiment 2

[0056] The raw material of this example is an extruded AZ31 magnesium alloy, which has more elements with higher concentration than that of Example 1, and the component segregation is serious under the conventional smelting method.

[0057] Under the situation that no raw material is placed, close the exhaust valve 21, open the intake valve 23, open the vacuum mechanism 9, make the sealed cabin body 2 communicate with the vacuum mechanism 9, and make the pressure in the sealed cavity be at 10Pa, set the control at this time The temperature mechanism 6 keeps the three-stage temperature control at 200°C for 30 minutes, then at 600°C for 120 minutes, and cools to room temperature after the heat preservation is completed.

[0058] Place 400g of extruded AZ31 in the smelting zone 31, set the filter mechanism 5 as a graphite plate with 3 holes and the diameter of each hole is 8mm, at this time close the flow rate control mechanism 4, that is, the lifting of the inverted cone inside t...

Embodiment 3

[0065] The raw materials of this example are pure magnesium and pure zinc. Compared with Examples 1 and 2, this example is mainly used to explore the feasibility of preparing a homogeneous alloy.

[0066] Under the situation that no raw material is placed, close the exhaust valve 21, open the intake valve 23, open the vacuum mechanism 9, make the sealed cabin body 2 communicate with the vacuum mechanism 9, and make the pressure in the sealed cavity be at 10Pa, set the control at this time. The temperature mechanism 6 keeps the three-stage temperature control at 200°C for 30 minutes, then at 600°C for 120 minutes, and cools to room temperature after the heat preservation is completed;

[0067] The purity is 99.99%, and the quality is 150g of dendritic pure magnesium and 10g of granular pure zinc placed in the smelting zone 31, and the filter mechanism 5 is set as a graphite plate containing 3 holes and the aperture of each hole is 8mm. Close the flow rate control mechanism 4, t...

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PUM

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Abstract

The invention discloses a magnesium and magnesium alloy casting device and method based on melt speed-controlled drop casting. The casting device comprises an electric furnace body, a sealed cabin and a multi-section temperature control assembly are arranged in the electric furnace body, a flange end cover and an exhaust valve are arranged on the upper portion of the sealed cabin, and a bottom air inlet valve is communicated with an argon supply mechanism and a vacuum mechanism; a top pouring type integrated crucible is arranged in the sealed cabin body, a flow rate adjusting mechanism and a filtering mechanism are nested between a smelting area and an ingot casting area of the top pouring type integrated crucible, and a thermocouple is arranged at the bottom of the outer wall of the top pouring type integrated crucible; the casting method comprises the following steps: placing magnesium and magnesium alloy raw materials in a smelting area; vacuumizing to enable the whole cavity to be filled with argon; the temperature of the multi-section temperature control assembly is set, and magnesium and magnesium alloy raw materials are melted in the full argon protection atmosphere; meanwhile, the flow velocity adjusting mechanism is adjusted to control the flow velocity of the melt; the liquid drops drop into an ingot casting area in a continuous and clean liquid drop form; the device and the process are simple, the effect is excellent, and the formed casting product has high homogeneity, high compactness and high cleanliness at the same time.

Description

technical field [0001] The invention relates to the technical field of preparation of magnesium and magnesium alloys, in particular to a melting and casting device and method for magnesium and magnesium alloys based on melt velocity controlled drop casting. Background technique [0002] Magnesium and magnesium alloys have broad application prospects in the fields of lightweight rail transit, biomedicine, aerospace, and national defense because of their low density, high specific strength and specific stiffness, and easy recycling. [0003] In recent years, seeking high-uniformity, high-density, high-clean magnesium and magnesium alloy preparation methods has become one of the main development trends in the field of magnesium and magnesium alloys. On the one hand, the existing magnesium and magnesium alloy devices are mainly castings, and the ingots obtained by conventional solidification methods often have serious internal and external structure inhomogeneity and solute segr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22D7/00B22D37/00B22D27/04B22D9/00B22D7/12C22B9/00
CPCB22D7/005B22D37/00B22D27/04B22D9/003B22D7/12C22B9/006
Inventor 单智伟郑芮杨博毛路遥李伟超
Owner XI AN JIAOTONG UNIV
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