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Method for refining magnesium alloy crystal grains

A technology of grain refinement and magnesium alloy, which is applied in the preparation of magnesium alloy grain refinement through the "preset twinning-low temperature thermal deformation" method, and in the field of magnesium alloy grain refinement, can solve the problem of expensive forming molds and low process Complicated, will introduce problems such as impurities or defects, to achieve the effect of small grain size, simple production equipment, and good toughness

Inactive Publication Date: 2014-07-02
TAIYUAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Grain refining methods include powder metallurgy, rapid solidification, severe plastic deformation (SPD), etc. Although these methods have been proven to be effective, many of them are not suitable for large-scale production due to the limitation of production costs and their own processes. use
For example, powder metallurgy, rapid solidification and other grain refinement methods are complicated and inevitably introduce impurities or defects. In addition, the common severe plastic deformation method is also relatively complicated and has high requirements for forming equipment and expensive forming molds.

Method used

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  • Method for refining magnesium alloy crystal grains
  • Method for refining magnesium alloy crystal grains
  • Method for refining magnesium alloy crystal grains

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Twins were pre-set in AZ31 magnesium alloy slabs by pre-rolling at room temperature with a pre-rolling deformation of 5%, followed by annealing at 200 °C for 6 h. attached figure 1 It is the EBSD diagram of the original magnesium alloy sheet and the pre-rolled and annealed pre-twinned sheet. It can be seen that a large number of twins have formed in the pre-rolled magnesium alloy sheet, and the twinned structure is still intact after low-temperature annealing for 6 hours. It is judged by EBSD that these twins are mainly {10-12} tensile twins, and the twin layers in each grain are almost parallel, and the content of tensile twins is 59%. Then, the original sheet and the pre-twinned sheet were compressed and deformed at 200 °C with a compression deformation of 65% and a strain rate of 10 -3 the s -1 . attached figure 2 It is the EBSD diagram of the original sheet and the pre-twinned sheet subjected to 65% compression deformation at 200°C. It can be seen that after th...

Embodiment 2

[0022] Twins were pre-compressed in AZ31 magnesium alloy slabs at room temperature with a pre-compression deformation of 6%, followed by annealing at 180 °C for 8 h. Then the original sheet and the pre-twinned sheet were rolled and deformed at 200 °C with a compression deformation of 25% and a strain rate of 10 -1 the s -1 . attached image 3 It is the EBSD diagram of the original sheet and the pre-twinned sheet after 25% rolling deformation at 200°C. It can be seen that after hot rolling deformation, the structure of the original sheet is not uniform, and the coarse grains and fine dynamic recrystallization grains alternate distribution, and the dynamic recrystallization induced by the preset twins obviously refines the grain structure of the magnesium alloy, and the structure is uniform and fine. Compared with the original sheet, the grain size of the preset twinned sheet after hot rolling can be refined to 4.1 μm.

Embodiment 3

[0024] AZ31 magnesium alloy slabs were pre-twinned by pre-rolling at room temperature with a pre-rolling deformation of 8%, followed by annealing at 200 °C for 10 h. Then, the original sheet and the pre-twinned sheet were subjected to extrusion deformation at 200 °C, with an extrusion deformation of 80% and a strain rate of 10 -3 the s -1 . After hot extrusion deformation, the structure of the original plate is not uniform, and the coarse grains and fine dynamic recrystallization grains are distributed alternately, while the dynamic recrystallization induced by the preset twins obviously refines the grain structure of the magnesium alloy, and the structure is uniform Small, compared with the original sheet, the grain size of the pre-twinned sheet after hot extrusion can be refined to 2.8 μm.

[0025] The invention pre-deforms twins in the magnesium alloy, then performs low-temperature annealing to eliminate the influence of dislocations and retains the twin structure, and us...

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Abstract

The invention discloses a method for refining magnesium alloy crystal grains, belonging to the technical field of plastic processing of nonferrous metals. According to the method, a magnesium alloy is easily subjected to twin dynamic recrystallization in a low-temperature thermal deformation process by virtue of the processes of twin crystal presetting, low-temperature annealing and low-temperature thermal deformation, and nucleation of new crystal grains is promoted by means of interaction of twin crystals as well as interreaction between the twin crystals and moving dislocation; twin crystal resetting can provide preferred nucleation points, including twin crystal boundaries, boundaries between twin crystals as well as boundaries between twin crystals and crystal boundaries, for dynamic recrystallization in order to accelerate a dynamic recrystallization process and realize refining of crystal grains. The method has the advantages of simple production equipment and low cost, is easy to implement and can be put into mass production.

Description

technical field [0001] The invention relates to a method for refining magnesium alloy grains, in particular to a preparation method for refining magnesium alloy grains through a "preset twinning-low temperature thermal deformation" method. The invention belongs to the technical field of plastic processing of nonferrous metals. Background technique [0002] Magnesium alloy is currently the lightest metal structural material in industrial applications. It has the advantages of high specific strength and specific stiffness, good damping and shock absorption performance, large elastic modulus, good thermal conductivity, easy cutting and easy recycling, so it is widely used In aerospace, automotive, electromechanical and electronic products and other fields. However, magnesium alloy has a close-packed hexagonal crystal structure, and there are few independent slip systems at room temperature, and its plastic deformation is limited to {0001}<11-20> slip on the basal plane a...

Claims

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Application Information

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IPC IPC(8): C22F1/06
Inventor 张华樊建锋许并社董洪标
Owner TAIYUAN UNIV OF TECH
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