Method for refining microstructure of hot-extruded magnesium alloy

A technology for microstructure and magnesium alloys, applied in the field of extruded magnesium alloys, can solve the problems of dynamic recrystallization and growth, affecting the mechanical properties of extruded alloys, etc.

Active Publication Date: 2017-10-27
CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The hot extrusion deformation method can significantly refine the microstructure of magnesium alloys through dynamic recovery and dynamic recrystallization, but due to the preheating before extrusion, friction heat and deformat

Method used

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  • Method for refining microstructure of hot-extruded magnesium alloy
  • Method for refining microstructure of hot-extruded magnesium alloy
  • Method for refining microstructure of hot-extruded magnesium alloy

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preparation example Construction

[0071] The present invention has no special limitation on the preparation method of the hot-extruded magnesium alloy, which can be prepared by methods well known to those skilled in the art. In the present invention, the preparation method of the hot extruded magnesium alloy is preferably:

[0072] The deformed magnesium alloy is extruded by a magnesium profile extruder to obtain a hot extruded magnesium alloy.

[0073] In the present invention, the composition of the deformed magnesium alloy is consistent with the composition of the above-mentioned hot extruded magnesium alloy, and the composition is:

[0074] 8-9wt% Al;

[0075] 0.4-0.8wt% Zn;

[0076] 0.8-1.4wt% La;

[0077] 0.1-0.3wt% Mn;

[0078] The balance is Mg and unavoidable impurities.

[0079] The present invention has no special limitation on the preparation method of the wrought magnesium alloy, which can be prepared by using the wrought magnesium alloy preparation method well known to those skilled in the a...

Embodiment 1

[0102] Mixing high-purity magnesium, high-purity aluminum, high-purity zinc, magnesium-lanthanum master alloy containing 20% ​​lanthanum and aluminum-manganese master alloy containing 10% manganese;

[0103] Add high-purity magnesium into an iron crucible preheated at 250°C, and add No. 5 flux to cover;

[0104] After the high-purity magnesium is completely melted, the temperature of the melt is raised to 740°C, and high-purity aluminum, high-purity zinc, magnesium-lanthanum master alloy containing 20% ​​lanthanum and 10% manganese are added to the melt in batches. Aluminum-manganese master alloy, keep the melt temperature at 720-780°C during this process;

[0105] After all the additions are completed, stir for 20 minutes, refine with argon gas, and then stand still for 40 minutes to cast a magnesium alloy ingot by semi-continuous casting, which is a deformed magnesium alloy. The volume ratio of the runner and the crystallizer is 100:1. CO 2 and SF 6 Mixed gas as shielding...

Embodiment 2

[0108] Heat the deformed magnesium alloy prepared in Example 1 at 380°C for 2 hours, then heat it at 410°C for 14 hours for solution treatment, quench and cool the magnesium alloy after solution treatment, and turn the cooled magnesium alloy to a length of Ф82mm 120mm.

[0109] Preheat the turned magnesium alloy in a preheating furnace at 250°C for 2.5 hours, and then extrude it into a round bar with a 630-ton magnesium profile extruder at a temperature of 250°C and an extrusion speed of 0.5mm / s. The extrusion ratio is 18:1 to obtain hot extruded magnesium alloy.

[0110] The hot-extruded magnesium alloy obtained at the extrusion outlet is cooled with liquid nitrogen by the above-mentioned cooling device, and the flow rate of the liquid nitrogen is controlled to be 1.2m 3 / h, to obtain a hot extruded magnesium alloy with fine grains.

[0111] Observing the microstructure of the hot-extruded magnesium alloy with fine grains obtained in Example 2 of the present invention, the ...

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Abstract

The invention provides a method for refining a structure of a hot-extruded magnesium alloy. The method comprises the step of applying liquid nitrogen to the hot-extruded magnesium alloy by adopting a cooling device so as to cool the hot-extruded magnesium alloy. The cooling device comprises a bracket (10), a liquid nitrogen storage tank (4), a spray nozzle (7) and a valve (6), wherein the bracket (10) is arranged outside a workpiece (8); the liquid nitrogen storage tank (4) is fixed on the bracket (10) and is used for storing liquid nitrogen; the bracket (10) is of an inverted-U-shaped baffle covering the outside of the workpiece (8), and the top face and two side faces of the inverted-U-shaped baffle have baffle structures; the spray nozzle (7) is arranged at an outlet of the liquid nitrogen storage tank (4) and is used for spraying the liquid nitrogen to the workpiece (8); the valve (6) is arranged between the liquid nitrogen storage tank (4) and the spray nozzle (7); the flow rate of the liquid nitrogen during cooling is 0.6m<3>/h to 1.2m<3>/h. According to the method, by adopting the specific cooling device and controlling the flow rate of the liquid nitrogen, the risks of liquid nitrogen splashing and sectional bar bursting are avoided, and the structure of the hot-extruded magnesium alloy is obviously refined.

Description

technical field [0001] The invention relates to the technical field of extruded magnesium alloys, in particular to a method for refining the microstructure of hot extruded magnesium alloys. Background technique [0002] Magnesium and its alloys have a very small specific gravity (the specific gravity of pure magnesium is 1.74g / cm 3 ), compared to aluminum (2.70g / cm 3 ) and iron (7.80g / cm 3 ) are 35.6% and 77.7% smaller, respectively, and are the lightest among currently available metallic materials. At the same time, magnesium and its alloys also have the advantages of high specific strength, high specific stiffness, good damping performance, good electromagnetic shielding, and good machinability, and have good application prospects in the field of weight reduction of structural materials. [0003] At present, magnesium alloys still have the problem of low mechanical properties, which affects the large-scale application of magnesium alloys. In order to improve the mechan...

Claims

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Application Information

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IPC IPC(8): C22F1/06C22C23/02
Inventor 孟健邱鑫孙伟杨强管凯田政张德平牛晓东刘孝娟
Owner CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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