Method for preparing magnesium alloy plate strip with grain size in symmetric gradient distribution along plate thickness direction

Abstract

The invention relates to a method for preparing a magnesium alloy plate strip with a grain size in symmetric gradient distribution along a plate thickness direction. In the method, the magnesium alloy plate strip is subjected to bidirectional continuous bending deformation and then recrystallization annealing; during deformation, a surface layer is subjected to large twinning deformation, and shear stress applied to the surface layer makes a base surface texture deflected and weakens the original texture; during annealing, the surface layer with large deformation is subjected to static recrystallization so as to refine grains and randomize the texture; and when the deformation is less than or equal to 0.03, the grains on the surface layer are quickly recrystallized and grown to be coarsened due to a low recrystallization nucleation rate. By the method, two gradient materials with refined or coarsened grains on the surface layer can be prepared. The process is reasonable in design and easy to operate, required equipment is realized by modifying and upgrading the conventional straightener, the gradient structure along the plate thickness direction is obtained by coordinating repeated bending with recrystallization annealing, the texture of the magnesium alloy plate strip is weakened, the strength and the ductility of the magnesium alloy plate strip are improved, and the subsequent processability of a magnesium alloy plate is improved.

Description

technical field [0001] The invention discloses a preparation method of a magnesium alloy strip whose grain size is distributed symmetrically and gradiently along the thickness direction, and belongs to the technical field of magnesium alloy processing. Background technique [0002] As the metal structure material with the lowest density, magnesium alloy has the advantages of high specific strength, high specific modulus, and electromagnetic shielding. It has important application value and broad application prospects in the fields of automobile, electronics, aerospace, and national defense. However, magnesium alloy ingots will form a strong plate texture after being rolled and extruded into sheets or strips. For magnesium alloys with hexagonal close-packed structure, this texture is difficult to reduce and eliminate through annealing process and conventional deformation process, which can lead to various deformation defects and severely limit the secondary forming ability, t...

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Problems solved by technology

[0004] The purpose of the present invention is to overcome the problem of poor ductility of the existing magnesium and magnesium alloy strips due to their strong texture, and to provide a kind of reasonable process design, simple operation, through the bidirectional repeated bending deformation of magnesium and magnesium alloy strips to accumulate twinning Coordinated deformation and static recrystallization to prepare magnesium alloy strips with a symmetrical gradient distribution of grain size and texture along the thickness direction, to achieve the purpose of improving the texture and properties of magnesium and magnesium alloy strips

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