Method for improving Mg-Al-Zn magnesium alloy thermoforming and service performance

A magnesium alloy and hot forming technology, which is applied in the field of deformation heat treatment to improve the hot forming and service performance of Mg-Al-Zn series magnesium alloys, and can solve the problems of poor comprehensive mechanical properties, poor hot forming and service performance, and damage of cast magnesium alloys. Solve problems such as alloy strength and ductility, achieve outstanding strengthening effect, promote dynamic recrystallization process, and refine alloy structure

Inactive Publication Date: 2017-09-01
CENT SOUTH UNIV
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  • Abstract
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Problems solved by technology

The age-strengthening precipitates in this alloy are Mg 17 Al 12 Phase, in the ordinary aging process, it is mainly a discontinuous precipitated phase in the form of coarse lamellar, poor thermal stability, rather uneven distribution in the magnesium matrix, weak hindrance to dislocations, poor strengthening effect, and large layers The flaky discontinuous precipitates are easy nucleation points for cracks, which not only damages the strength and ductility of the alloy, but also leads to poor hot forming and service performance, which seriously limits the wider application of Mg-Al-Zn series magnesium alloys
In addition, the magnesium alloys currently used in actual production are mainly cast magnesium alloys, but the comprehensive mechanical properties of cast magnesium alloys are poor, and it is difficult to apply to occasions with high mechanical properties. At this time, it is often necessary to improve their mechanical properties by high temperature deformation. Expand its scope of application

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  • Method for improving Mg-Al-Zn magnesium alloy thermoforming and service performance
  • Method for improving Mg-Al-Zn magnesium alloy thermoforming and service performance
  • Method for improving Mg-Al-Zn magnesium alloy thermoforming and service performance

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Embodiment 1

[0029] The as-cast AZ80 magnesium alloy was solution treated at 450°C for 12h, then bent and deformed at room temperature, then compressed and deformed to introduce twins, the cumulative deformation amount was 0.1 of the true strain, and then aged at 200°C for 2h, the obtained alloy structure is as attached figure 1 shown, from figure 1 It can be seen that the precipitated phases are finely dispersed and evenly distributed in the matrix. The alloy structure of only aging treatment is as attached figure 2 As shown, it can be seen that only the precipitated phase in the aging treatment specimen is in the form of coarse lamellar sheets, and the distribution is uneven. The room temperature tensile mechanical properties of the specimens subjected to deformation heat treatment and aging treatment alone are shown in Table 1. The tensile strength of specimens subjected to deformation heat treatment is 345 MPa, which is 56 MPa higher than that of specimens with only aging treatment; ...

Embodiment 2

[0034] The as-cast AZ61 magnesium alloy was solution treated at 430°C for 10 hours, then pre-compressed and deformed at 300°C, the deformation amount was 0.2 of the true strain, and then aged at 180°C for 2 hours. Figure 5 As shown, it can be seen from the figure that a large number of low-angle grain boundaries appear in the original grains of the alloy after high-temperature pre-deformation, and after subsequent aging treatment, fine precipitates precipitate on the low-angle grain boundaries.

Embodiment 3

[0036] The as-cast AZ91 magnesium alloy was solution treated at 450°C for 12 hours, then pre-stretched at 150°C to introduce twins, and the deformation amount was 0.05 of the true strain, and then aged at 220°C for 30 minutes. Figure 6 As shown, it can be found that the fine dispersed precipitates are uniformly distributed in the AZ91 magnesium alloy matrix. The creep properties of deformation heat treatment specimens and aging treatment specimens at 200°C and 80MPa are shown in the attached Figure 7 As can be seen from the figure, it can be found that the creep deformation and creep rate of the specimens with thermomechanical treatment are much lower than those with only aging treatment, and the steady-state creep rates of specimens with thermomechanical treatment and aging treatment only are 2.7×10 -8 the s -1 , 7.5×10 -8 the s -1 , indicating that the creep resistance of the alloy has been effectively improved after deformation heat treatment.

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Abstract

The invention provides a method for improving Mg-Al-Zn magnesium alloy thermoforming and service performance. The method comprises the steps that Mg-Al-Zn magnesium alloy is subjected to pre-deformation treatment at 25 DEG C to 300 DEG C, twin crystal or low-angle crystal boundaries are introduced, and then aging treatment is conducted. According to the deformation heat treatment method, precipitation of a continuous precipitation phase of the Mg-Al-Zn magnesium alloy can be effectively promoted, and alloy tissue with a uniform, small and dispersively distributed precipitation phase is obtained finally; and alloy strength and plasticity are synchronously improved, and thermoforming performance and service performance of the alloy are improved. The method for improving the Mg-Al-Zn magnesium alloy thermoforming and service performance is reasonable in design, simple in equipment requirement, convenient to operate, low in cost and high in efficiency, distribution of the precipitation phase of the Mg-Al-Zn magnesium alloy is reasonably controlled, the thermoforming performance and service performance of the alloy are improved, and the method has a good industrial application prospect.

Description

technical field [0001] The invention relates to a method for improving hot forming and service performance of Mg-Al-Zn series magnesium alloys, specifically a deformation heat treatment method for introducing twins or low-angle grain boundaries through pre-deformation at different temperatures and post-aging treatment, which belongs to magnesium alloys field of processing technology. Background technique [0002] Mg-Al-Zn series magnesium alloy is a commonly used commercial magnesium alloy, which does not contain rare earth elements and has low cost. The age-strengthening precipitates in this alloy are Mg 17 al 12 Phase, in the ordinary aging process, it is mainly a discontinuous precipitated phase in the form of coarse and large lamellar layers, which has poor thermal stability and is unevenly distributed in the magnesium matrix. The flaky discontinuous precipitates are easy nucleation points for cracks, which not only damages the strength and ductility of the alloy, but...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22F1/06
CPCC22F1/06
Inventor 杨续跃张笃秀肖振宇
Owner CENT SOUTH UNIV
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