Preparation method of fine grain magnesium alloy

Abstract

The invention relates to a preparation method of a fine grain magnesium alloy. In the method, the preheating temperature of a mould is 350+ / -5 DEG C; a magnesium alloy blank is subjected to at least five passes of extrusion and deformation; the preheating temperature of the magnesium alloy blank is 250+ / -5 DEG C-380+ / -5 DEG C; the extrusion rate is 2mm / s-15mm / s, and the extrusion direction each time is different; and the preheating temperature of the magnesium alloy blank changes from high to low, and the extrusion rate is varied from large to small. According to the preparation method provided by the invention, a multi-pass multi-direction temperature-variable extrusion technology is adopted, i.e., the temperature and extrusion rate of the magnesium alloy blank are gradually reduced along with the increase of extrusion pass, and forces are applied in the different directions of magnesium alloy so as to carry out extrusion and deformation, thereby improving the deformation nonuniformity of a magnesium alloy structure in the conventional isothermal extrusion deformation and preventing full growth and grain mixing of dynamically recrystallized grains due to high temperature in the extrusion process. Thus, the grains of the magnesium alloy obtained by using the multi-pass multi-direction temperature-variable extrusion deformation are obviously fined, and the size of the grain is uniform.

Description

technical field [0001] The invention relates to metal materials, in particular to magnesium alloy materials, and in particular to a preparation method of fine-grained magnesium alloys. Background technique [0002] Magnesium alloy has the characteristics of light specific gravity, high specific strength, good impact resistance and earthquake resistance, excellent electromagnetic shielding performance and cutting processing performance. It is known as a clean material that can be recycled in the 21st century and does not pollute the environment. It is expected to be used in aerospace, aerospace, Weapons and equipment, automobiles, rail trains, 3C products and other fields have been increasingly widely used. [0003] Magnesium alloy has a close-packed hexagonal crystal structure, so its plastic formability is poor and it is difficult to perform plastic processing. Its application range is limited to a certain extent, so that magnesium alloy cannot reach the popular level of al...

AI Technical Summary

Problems solved by technology

[0005] Conventional plastic processing methods for magnesium alloys are mainly isothermal extrusion, rolling, stamping, etc., which is to heat the magnesium alloy billet to 300 ° C ~ 450 ° C, put it in a mold for extrusion or rolling, but because of the core of the billet The temperature is obviously higher than the surface temperature of the billet, and there is friction between the billet and the mold / roller, which is easy to cause significant uneven plastic deformation, and the effect of grain refinement is not obvious; if the billet and mold temperatures are low, it is easy to cause Magnesium Alloy Extrusion or Rolling Cracking

At present, the new process methods of magnesium alloy grain refinement at home and abroad mainly include: rapid solidification powder sheath extrusion or hot rolling, mechanical alloying powder sheath extrusion or hot rolling, equal channel angle extrusion (ECAE) and other methods. , these methods can refine the grains of magnesium alloys to the submicron level, but the process and mold structure are complicated, difficult to control, and relatively high in cost, which cannot meet the needs of mass production for engineering applications

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