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A Method for Improving High Temperature Creep Resistance of Magnesium Alloys Using Bending Grain Boundaries

A creep-resistant, magnesium alloy technology is applied to improve the performance of magnesium alloys in the subsequent creep process and the field of high-temperature creep resistance. problems, to achieve the effect of improving creep resistance, good application prospects, and improved creep resistance

Inactive Publication Date: 2020-06-19
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, blindly pursuing the addition of rare and precious elements will increase the density of the alloy, increase the cost, and even some elements are poisonous to the environment, making it difficult to recycle, which is not in line with the concept of economic and environmental protection
On the other hand, the introduction of a single precipitated phase structure as a means to improve creep performance has certain limitations, because under certain temperature and stress conditions, these precipitated phases may be broken and become the starting point of crack initiation due to the difference in properties from the matrix. , but reduces the creep properties of the alloy

Method used

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  • A Method for Improving High Temperature Creep Resistance of Magnesium Alloys Using Bending Grain Boundaries
  • A Method for Improving High Temperature Creep Resistance of Magnesium Alloys Using Bending Grain Boundaries
  • A Method for Improving High Temperature Creep Resistance of Magnesium Alloys Using Bending Grain Boundaries

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Experimental program
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Effect test

Embodiment 1

[0027] In this embodiment, the raw material is Mg-3Al-1Zn-0.2Mn magnesium alloy hot extrusion rod. Its average grain size is about 50 μm. The sample is pre-compressed at 400°C, and the compression rate is 0.003s -1 , the true strains are 0.2, 0.3 and 0.5, and the corresponding fine grain ratios are 0.2, 0.4 and 0.8.

[0028] The specimen structure after pressing is as figure 1 shown, where figure 1 (a) is the undeformed sample structure, figure 1 (b) is the sample structure with a true strain of 0.3, figure 1 (c) is the sample structure with a true strain of 0.5. It can be seen from the figure that several fine dynamic recrystallization grains appear at the original grain boundaries, and these dynamic recrystallizations cause the grain boundaries of the original coarse grains to bend to varying degrees. As the degree of deformation increases, the proportion of fine grains increases. , the bending degree of the original grain boundary also increases gradually.

[0029] T...

Embodiment 2

[0031] In this embodiment, the raw material is Mg-4Y rolled plate. Its average grain size is about 80 μm. For one group of samples at 450°C, 0.003s -1 Under pre-compression treatment, the true strain is 0.3. In order to obtain a higher proportion of fine-grained structure, the other two groups of samples were subjected to variable-speed three-step compression treatment at 450°C, and the compression rate of the first step was 0.003s -1 , followed by an intermediate annealing at 400°C for 10min, and then 0.03s -1 Carry out the second step of compression, followed by intermediate annealing at 400°C for 30min, and finally with 0.3s -1 The rate of the third compression step, the total true strain is 1.2 and 1.6, respectively, the three corresponding fine grain ratios are 0.3, 0.5 and 0.7.

[0032] The deformed tissue is as image 3 as shown, image 3 (a) is the undeformed sample structure, image 3 (b) is the sample structure with a true strain of 0.3, image 3 (c) is the s...

Embodiment 3

[0035] The raw material used in this embodiment is cast Mg-9Gd-3Y-0.5Zr. Its average grain size is about 200 μm. For one group of samples at 520°C, 0.003s -1 Under pre-compression treatment, the true strain is 0.3. In order to obtain a higher proportion of fine-grained structure, the other two groups of samples were subjected to variable-speed two-step compression treatment at 520°C, and the compression rate of the first step was 0.003s -1 , followed by intermediate annealing at 520°C for 20min, and finally with 0.3s -1 The second-step compression is carried out at a rate of 1. The total true strains are 1.2 and 1.6, respectively, and the corresponding fine grain ratios of the three are 0.2, 0.5 and 0.8.

[0036] The deformed tissue is as Figure 5 as shown, Figure 5 (a) is the undeformed sample structure, Figure 5 (b) is the sample structure with a true strain of 0.3, Figure 5 (c) is the sample structure with a true strain of 1.2. The microstructure after one-step ...

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Abstract

The invention relates to a method for improving a high-temperature creep resistance performance of magnesium alloy by using curved grain boundaries. The method comprises the steps that as-cast or deformed magnesium alloy materials is subjected to pre-compression deformation in a temperature range of 400-550 DEG C, and the true strain is 0.2-1.2 to obtain the curved grain boundaries with differentdensities, and the corresponding fine grain ratio is 0.2-0.6. Tensile creep performance tests are carried out on undeformed samples, samples with fine grain ratio of 0.2 - 0.6 and samples with fine grain ratio of greater than or equal to 0.6 in the temperature range of 150-350 DEG C separately. Compared with undeformed samples and the samples with high fine grain ratio, creep strain and steady-state creep rate of the curved grain boundary samples with fine grain ratio of 0.2-0.6 under the same conditions are significantly reduced, and creep resistance performance is significantly improved. Theinvention provides a method for stably improving high-temperature creep resistance performance of magnesium alloy with reasonable design, simple equipment requirements, low cost, high efficiency andwide application range.

Description

technical field [0001] The invention relates to a method for improving the high-temperature creep resistance of magnesium alloys by using curved grain boundaries, and specifically relates to a method for improving the creep resistance of magnesium alloys in the subsequent creep process by using dynamic recrystallization generated by pre-deformation to distort the grain boundaries. performance. It belongs to the technical field of failure and protection of non-ferrous metal materials Background technique [0002] With the development of the economic level and the improvement of people's awareness of environmental protection, the requirements for lightweight industrial design in modern society are becoming more and more urgent. Due to its excellent specific gravity and comprehensive performance, magnesium alloy is very suitable for today's industrial design concept of lightweight and environmental protection, and has broad application prospects in aviation, aerospace, transpo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22F1/06
CPCC22F1/06
Inventor 杨续跃杨溢肖振宇霍庆欢
Owner CENT SOUTH UNIV
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