Differential velocity cyclic extrusion forming method for high performance rare earth magnesium alloy billet

Abstract

The invention discloses a differential velocity cyclic extrusion forming method for a high performance rare earth magnesium alloy billet, and relates to a billet making die for differential velocity cyclic extrusion of a high performance rare earth magnesium alloy. The billet making die comprises an upper die assembly, a "T"-shaped punch, a split concave die and a lower die assembly. The split concave die comprises an upper concave die and a lower concave die. The upper concave die is provided with an upper rectangular die cavity and an upper half polygons expansion die cavity. The lower concave die is provided with a lower cuboid die cavity and a lower half polygons expansion die cavity, the upper concave die and the lower concave die combine to form a polygons expansion die cavity, and differential velocity angles are arranged on both sides of the lower half polygons expansion die cavity, and the height of the differential velocity angle on both sides is different. A billet is extruded through multiple passes after upsetting, a metal flow state is changed by changing the structure of a concave die cavity, the shear deformation is introduced to realize the strain growth, the number of deformation is reduced, the strain effect is improved, the production efficiency is improved, the grain structure is refined, the second phase structure is optimized, and finally the magnesium alloy billet with remarkable mechanical properties is obtained.

Description

technical field [0001] The invention belongs to the technical field of metal plastic processing technology and forming, in particular to a high-performance rare-earth magnesium alloy billet differential-speed circular expansion extrusion forming method. Background technique [0002] Magnesium alloy is the lightest structural material, which has the characteristics of high specific strength, high specific stiffness, corrosion resistance, electromagnetic shielding, and creep resistance. At present, magnesium alloy has been well applied in general structural parts: such as AZ91D Application of magnesium alloy sheet on automobile panels, application of AZ80 magnesium alloy on automobile hub. With the development of lightweight equipment, magnesium alloy has gradually become the best substitute for aluminum alloy materials for important structural parts of aerospace. Magnesium alloys have a close-packed hexagonal crystal structure, and it is difficult to start the deformation-sl...

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Problems solved by technology

[0005] The purpose of the present invention is to introduce large plastic deformation to the high-strength heat-resistant Mg-Gd-Y-Zn-Zr alloy to refine the grains of the magnesium alloy, adjust the distribution of the second phase, and introduce the shear deformation force to the traditional one by changing the cavity structure. In the process of cyclic expansion and extrusion, it realizes the differential flow during the metal flow process, enhances the comprehensive mechanical properties of the metal, and at the same time solves the problems of small cumulative strain and cumbersome deformation passes in the traditional cyclic expansion and extrusion

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