CN112030086A - Method for improving fatigue resistance of cast magnesium alloy - Google Patents
Method for improving fatigue resistance of cast magnesium alloy Download PDFInfo
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- CN112030086A CN112030086A CN202010872418.7A CN202010872418A CN112030086A CN 112030086 A CN112030086 A CN 112030086A CN 202010872418 A CN202010872418 A CN 202010872418A CN 112030086 A CN112030086 A CN 112030086A
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/06—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon
Abstract
The invention discloses a method for improving the fatigue resistance of cast magnesium alloy, which comprises the following steps: firstly carrying out high-temperature reciprocating torsion on the magnesium alloy ingot blank subjected to the solution treatment, wherein the temperature of the high-temperature reciprocating torsion is 450-550 ℃, the rotating speed is 10-15 rpm, then carrying out multiple times of medium-temperature reciprocating torsion at 250-450 ℃, wherein in the process of the multiple times of medium-temperature reciprocating torsion, the medium-temperature reciprocating torsion in the next time is lower than the torsion temperature of the medium-temperature reciprocating torsion in the previous time, and finally carrying out low-temperature reciprocating torsion, wherein the temperature of the low-temperature reciprocating torsion is-125 ℃ to room temperature. The method can introduce high-density twin crystals to the edge of the cast magnesium alloy to induce the preferential occurrence of twin generation in the fatigue cycle process, and has the advantages of reasonable process design, simple equipment requirement, convenient operation, high efficiency and remarkable and stable improvement on the fatigue resistance of the cast magnesium alloy.
Description
Technical Field
The invention belongs to the technical field of non-ferrous metal material processing, relates to a method for improving the fatigue resistance of a cast magnesium alloy by using cooling torsion, and particularly relates to a method for improving the fatigue resistance of the cast magnesium alloy by introducing high-density twin crystals through cooling torsion and forcing the preferential de-twinning in the fatigue cycle process.
Background
As a green energy-saving material in the 21 st century, the application of magnesium alloy in the national defense and military industry, aerospace industry and transportation industry is more and more extensive, and particularly, the cast magnesium alloy is gradually applied to secondary bearing structural members. However, the strength of the cast magnesium alloy is low, so that the fatigue resistance of the cast magnesium alloy is poor, and the cast magnesium alloy cannot be safely used on a main bearing structural member for a long time. More seriously, the close-packed hexagonal crystal structure causes that the magnesium alloy is difficult to start non-basal plane slippage at medium and low temperature, and the twinning-de-twinning is taken as a main plastic deformation mechanism in the fatigue cycle process. After the circulation is carried out for a certain number of times, the de-twinning is hindered by accumulated basal plane dislocation, so that the interior of partial crystal grains can not be continuously and completely de-twinned, and the residual twin crystal immediately causes local stress concentration, so that the cast magnesium alloy structural member fails in advance, and casualties and economic loss are caused.
In order to solve the problem of poor fatigue resistance of cast magnesium alloy, most of domestic and foreign research methods adopt a large amount of rare earth elements to form solid solution strengthening or aging strengthening, but the rare earth elements are easy to burn in the casting process, so that the cost is too high, and the improvement of the fatigue resistance is not ideal. Therefore, a new method for efficiently enhancing the fatigue resistance of the cast magnesium alloy is needed to break through the technical bottleneck that the cast magnesium alloy structural member cannot be safely used under alternating load for a long time.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide the method which can introduce high-density twin crystals to the edge of the cast magnesium alloy to induce the preferential occurrence of twin generation in the fatigue cycle process, has reasonable process design, simple equipment requirement, convenient operation and high efficiency, and can obviously and stably improve the fatigue resistance of the cast magnesium alloy.
A method for improving the fatigue resistance of cast magnesium alloy comprises the following steps:
firstly carrying out high-temperature reciprocating torsion on the magnesium alloy ingot blank subjected to the solution treatment, wherein the temperature of the high-temperature reciprocating torsion is 450-550 ℃, the rotating speed is 10-15 rpm, then carrying out multiple times of medium-temperature reciprocating torsion at 250-450 ℃, wherein in the process of the multiple times of medium-temperature reciprocating torsion, the medium-temperature reciprocating torsion in the next time is lower than the torsion temperature of the medium-temperature reciprocating torsion in the previous time, and finally carrying out low-temperature reciprocating torsion, wherein the temperature of the low-temperature reciprocating torsion is-125 ℃ to room temperature.
In the method for improving the fatigue resistance of the cast magnesium alloy, the high-temperature reciprocating twisting is preferably performed for 2-4 passes of reciprocating twisting.
In the method for improving the fatigue resistance of the cast magnesium alloy, preferably, during the high-temperature reciprocating torsion, each clockwise torsion and the subsequent anticlockwise torsion are the reciprocating torsion of one pass, and the clockwise torsion and the anticlockwise torsion in each pass are the same in angle and are both 50-100 degrees.
In the method for improving the fatigue resistance of the cast magnesium alloy, preferably, the medium-temperature reciprocating torsion is performed for 2-6 passes of reciprocating torsion; the torsion rotating speed of the medium-temperature reciprocating torsion is 0.5-5 rpm;
in the process of several times of medium-temperature reciprocating torsion, the medium-temperature reciprocating torsion of the next time is reduced by 10-50 ℃ compared with the torsion temperature of the medium-temperature reciprocating torsion of the previous time.
In the method for improving the fatigue resistance of the cast magnesium alloy, preferably, during the medium-temperature reciprocating torsion, each clockwise torsion and the subsequent anticlockwise torsion are the reciprocating torsion of one pass, and the clockwise torsion and the anticlockwise torsion in each pass are the same in angle and are both 10-100 degrees.
In the method for improving the fatigue resistance of the cast magnesium alloy, preferably, the low-temperature reciprocating twisting is performed for 1 to 3 times of reciprocating twisting, and the twisting speed is 0.05 to 5rpm.
In the method for improving the fatigue resistance of the cast magnesium alloy, preferably, during the low-temperature reciprocating torsion, each clockwise torsion and the subsequent anticlockwise torsion are the reciprocating torsion of one pass, and the clockwise torsion and the anticlockwise torsion in each pass are the same in angle and are both 10-80 degrees.
In the method for improving the fatigue resistance of the cast magnesium alloy, preferably, the high-temperature reciprocating torsion temperature range is 480-550 ℃;
the medium-temperature reciprocating torsion temperature range is 300-450 ℃.
In the method for improving the fatigue resistance of the cast magnesium alloy, the temperature range of the low-temperature reciprocating torsion is preferably-125 to-20 ℃; the torsion rotating speed of the low-temperature reciprocating torsion is 0.05-3 rpm.
In the method for improving the fatigue resistance of the cast magnesium alloy, the cast magnesium alloy is preferably selected from Mg-Al-Sn, Mg-Zn-Zr series and rare earth magnesium alloy.
Compared with the prior art, the invention has the advantages that:
1. the invention does not need to add extra noble metal elements, focuses on the regulation and control of the microstructure, has wide application range and is beneficial to environmental protection; meanwhile, modification elements are not required to be added into common casting state rare earth magnesium alloys, and the Mg-Al-Sn, Mg-Zn-Sn and Mg-Zn-Zr series alloys are mature commercial casting magnesium alloys, so that the production cost is low, the equipment requirement is simple, the operation is convenient, a complex processing process flow is not required, and the fatigue resistance improvement efficiency is high.
2. The fatigue resistance is comprehensively influenced by the metal strength and plasticity, the shear stress applied by the method can avoid a basal plane texture caused by traditional hot forging, hot rolling and hot extrusion while refining the crystal grains of the cast magnesium alloy through cooling and reciprocating torsion at high temperature, medium temperature and low temperature, the synchronous improvement of the magnesium alloy strength and plasticity is realized, and the fatigue resistance of the cast magnesium alloy can be effectively improved; meanwhile, the isothermal torsion can not stably improve the fatigue resistance of the cast magnesium alloy, for example, the torsion is only at the same temperature of high temperature or middle temperature, the coarsening of the crystal grains in the middle part is easily induced, the fatigue resistance is damaged, the cracks are easily generated on the edge part only by the torsion at the middle temperature or the low temperature, and the high-density twin crystals can not be effectively introduced, but the high-temperature torsion rotating speed is high, the torsion temperature at the middle temperature is gradually reduced, the coarsening phenomenon of the refined crystal grains in the next torsion pass is avoided, and the condition that the crystal grains are excessively refined and the high-density twin crystals can not be introduced when the low-temperature torsion; and the high-temperature torsion can also ensure that the cast magnesium alloy does not generate cracks during medium-temperature torsion and low-temperature torsion.
3. The grain size of the cast magnesium alloy is usually more than 200 mu m, the grain size is difficult to be refined to be less than 20 mu m, the twinning-de-twinning phenomenon and the generation of residual twin crystals in the fatigue cycle process cannot be inhibited, the interaction between dislocation and the residual twin crystals is caused, and the fatigue resistance is damaged.
4. The method has remarkable and stable effect on improving the fatigue resistance, can improve the fatigue limit of the cast magnesium alloy to 1.8 times or more before torsion, can effectively break through the technical bottleneck that the current cast magnesium alloy cannot be safely used under alternating load for a long time, and has good application prospect.
Drawings
FIG. 1 is an electron back-scattering diffraction pattern of a Mg-3Zn-6Sn alloy sample in example 1.
FIG. 2 is an electron back-scattered diffraction pattern of a Mg-3Zn-6Sn alloy sample in comparative example 1.
Detailed Description
The invention is further described below with reference to the drawings and specific preferred embodiments of the description, without thereby limiting the scope of protection of the invention.
The invention provides a method for improving the fatigue resistance of cast magnesium alloy, which introduces high-density twin crystals to the edge of the cast magnesium alloy through cooling, reciprocating and twisting to force the preferential de-twinning in the fatigue cycle process, thereby stably and effectively improving the fatigue resistance of the cast magnesium alloy to 1.8 times or more, and comprises the following steps:
firstly carrying out high-temperature reciprocating torsion on the magnesium alloy ingot blank subjected to the solution treatment, wherein the temperature of the high-temperature reciprocating torsion is 450-550 ℃, the rotating speed is 10-15 rpm, then carrying out multiple times of medium-temperature reciprocating torsion at 250-450 ℃, wherein in the process of the multiple times of medium-temperature reciprocating torsion, the medium-temperature reciprocating torsion in the next time is lower than the torsion temperature of the medium-temperature reciprocating torsion in the previous time, and finally carrying out low-temperature reciprocating torsion, wherein the temperature of the low-temperature reciprocating torsion is-125 ℃ to room temperature.
Preferably, the high-temperature reciprocating torsion is performed for 2-4 times of reciprocating torsion, so that the crystal grains on the edge part can be refined quickly, and the refined crystal grains cannot be coarsened again.
Preferably, during the high-temperature reciprocating torsion, each clockwise torsion and the subsequent anticlockwise torsion are the reciprocating torsion of one pass together, the clockwise torsion and the anticlockwise torsion in each pass are the same in angle and are both 50-100 degrees, and therefore the crystal grains on the edge can be refined more quickly, and the crystal grains cannot grow up again after being refined.
Preferably, the medium-temperature reciprocating torsion is performed for 2-6 times of reciprocating torsion, so that the crystal grains at the edge part can be refined to be smaller in size; the twisting speed of the medium-temperature reciprocating twisting is 0.5-5 rpm, and cracks can be effectively prevented from being generated on the edge of the cast magnesium alloy during low-temperature twisting.
Preferably, in the process of multiple times of medium-temperature reciprocating torsion, the temperature of the medium-temperature reciprocating torsion of the next time is reduced by 10-50 ℃ compared with the torsion temperature of the medium-temperature reciprocating torsion of the previous time, so that the crystal grains on the edge can be refined to be smaller in size, and the crystal grains can be better ensured not to grow up again after being refined.
Preferably, during the medium-temperature reciprocating torsion, each clockwise torsion and the subsequent anticlockwise torsion are the reciprocating torsion of one pass, the clockwise torsion and the anticlockwise torsion in each pass are the same and are both 10-100 degrees, and the edge of the cast magnesium alloy can be effectively prevented from generating cracks during the low-temperature torsion.
Preferably, the low-temperature reciprocating torsion is performed for 1-3 passes of reciprocating torsion, the torsion rotating speed is 0.05-5 rpm, twin crystals with higher density can be introduced, and the twin crystals are distributed more uniformly.
Preferably, during the low-temperature reciprocating torsion, each clockwise torsion and the subsequent anticlockwise torsion are the reciprocating torsion of one pass together, the clockwise torsion and the anticlockwise torsion in each pass are the same in angle and are both 10-80 degrees, and twin crystals with higher density can be introduced.
Preferably, the high-temperature reciprocating torsion temperature range is 480-550 ℃, the crystal grains at the edge part can be refined more quickly, and cracks can be prevented from being generated at the edge part of the cast magnesium alloy during medium-temperature torsion and low-temperature torsion;
preferably, the medium-temperature reciprocating torsion temperature range is 300-450 ℃, so that the crystal grains at the edge part can be refined, and the crack of the edge part of the cast magnesium alloy can be effectively prevented from being generated during low-temperature torsion.
Preferably, the temperature range of the low-temperature reciprocating torsion is-125 to-20 ℃, and twin crystals with higher density can be introduced; the twisting rotating speed of the low-temperature reciprocating torsion is 0.05-3 rpm, so that twin crystals with higher density can be introduced, the twin crystal width can be increased, and the twin crystal stripping is facilitated.
The cast magnesium alloy is selected from Mg-Al-Sn, Mg-Zn-Zr series and rare earth magnesium alloy.
The fatigue resistance performance of the present invention refers to the fatigue cycle behavior in the temperature range of room temperature to 200 ℃.
The fatigue resistance of the invention can be tensile-tensile fatigue cycle, compression-compression fatigue cycle or fatigue resistance corresponding to the tensile-compression fatigue cycle, the cyclic loading frequency is 0.01-50 Hz, and the ratio of the absolute minimum stress to the absolute maximum stress is 0-1.
The materials and equipment used in the following examples are commercially available.
Example 1
The invention discloses a method for improving the fatigue resistance of a cast magnesium alloy, which comprises the following steps:
in the embodiment, the raw material is casting Mg-3Zn-6Sn (mass percent) to be a bar ingot blank, after solution treatment, the sample is subjected to 3 passes of reciprocating torsion at 520 ℃, the torsion rotation speed is 15rpm, each clockwise torsion and the subsequent anticlockwise torsion are both one pass, and the clockwise and anticlockwise torsion angles in each pass are both 70 degrees; performing 3 passes of reciprocating torsion at the temperature of 420-340 ℃, wherein the torsion temperature of the next pass is reduced by 40 ℃ compared with the torsion temperature of the previous pass, the torsion speed is 2rpm, each clockwise torsion and the subsequent anticlockwise torsion are both one pass, and the clockwise and anticlockwise torsion angles in each pass are both 50 degrees; and carrying out 1-pass reciprocating twisting at-80 ℃, wherein the twisting speed is 0.2rpm, each clockwise twisting and the subsequent anticlockwise twisting are jointly one pass, the clockwise twisting angle and the anticlockwise twisting angle in each pass are both 20 degrees, and the sample is marked as No. 1.
Comparative example 1
In comparison, the sample has the same raw material, casting and solution treatment as example 1, and is temperature-reduced and twisted under the same conditions, and the sample is different from example 1 only in that after the temperature-reduced and twisted, annealing is further performed at 300 ℃ for 2 hours, and the sample is marked as sample No. 2.
Comparative example 2
This sample had the same raw material, casting and solution treatment as example 1, but was not subjected to torsional deformation and was designated as sample No. 3.
FIG. 1 shows an electron backscatter diffraction texture map of a sample after temperature reduction and torsion, wherein high-density twin crystals have been successfully introduced; in contrast, fig. 2 shows an electron back scattering diffraction structure diagram after the sample is cooled, twisted and annealed, and twin crystals are completely disappeared. Subsequently, three samples were subjected to a fatigue resistance test at 150 ℃ in a tensile-tensile manner at a cyclic loading frequency of 0.5Hz and a ratio of the absolute minimum stress to the absolute maximum stress of 0.1. The test results are shown in table 1.
TABLE 1
| Sample (I) | Tensile yield strength | Tensile-tensile fatigue limit |
| Example 1 (sample No. 1) | 103MPa | 81MPa |
| COMPARATIVE EXAMPLE 1 (sample No. 2) | 84MPa | 37MPa |
| COMPARATIVE EXAMPLE 2 (sample No. 3) | 89MPa | 40MPa |
As can be seen from Table 1, the tensile yield strength of the sample No. 1 after temperature reduction and torsion is obviously improved, and the tensile-tensile fatigue limit at room temperature is also improved to 81MPa, which is 2.2 times and 2.0 times of the fatigue limit of the sample No. 2 after temperature reduction and torsion plus annealing and the fatigue limit of the sample No. 3 without treatment. It can be seen that the temperature-reducing torsion obviously improves the fatigue resistance of the as-cast Mg-3Zn-6Sn alloy, and the annealing after the temperature-reducing torsion can eliminate high-density twin crystals and damage the fatigue resistance.
Example 2
The invention discloses a method for improving the fatigue resistance of a cast magnesium alloy, which comprises the following steps:
in the embodiment, the raw material is Mg-9Gd-4Y alloy (mass percent) in a casting state, a bar ingot is cast, after solution treatment, the sample is subjected to reciprocating torsion for 4 passes at 500 ℃, the torsion rotation speed is 15rpm, each clockwise torsion and the subsequent anticlockwise torsion are both one pass, and the clockwise and anticlockwise torsion angles in each pass are both 80 degrees; 4 passes of reciprocating torsion are carried out at the temperature of 360-270 ℃, the torsion temperature of the next pass is reduced by 30 ℃ compared with the torsion temperature of the previous pass, the torsion speed is 3rpm, and the clockwise and anticlockwise torsion angles in each pass are 40 degrees; 2 passes of reciprocating torsion are carried out at the temperature of minus 20 ℃, the torsion speed is 0.5rpm, the clockwise and anticlockwise torsion angles in each pass are both 20 degrees, and the sample is marked as No. 4.
Example 3
The present embodiment is different from embodiment 2 only in that the high temperature reciprocating torsion is different, and the conditions of the high temperature reciprocating torsion of the present embodiment are: the sample is twisted back and forth at 460 ℃ for 4 passes at 15rpm, each clockwise twist and the subsequent counterclockwise twist are combined into one pass, the clockwise and counterclockwise twist angle in each pass is 80 degrees, and the sample is marked as No. 5.
Comparative example 3
For comparison, the sample has the same raw materials, casting and solution treatment as those of the sample in example 2, the sample is subjected to 4 passes of reciprocating torsion at 500 ℃, the torsion rotation speed is 15rpm, the torsion angles are all 80 degrees, and quenching is not performed between each pass; carrying out isothermal reciprocating torsion of 4 passes at 360 ℃, wherein the torsion rotation speed is 3rpm, the clockwise and anticlockwise torsion angles in each pass are both 40 degrees, and after each pass is twisted, water quenching and reheating to 360 ℃; 2 passes of reciprocating torsion are carried out at the temperature of minus 20 ℃, the torsion speed is 0.5rpm, the clockwise and anticlockwise torsion angles in each pass are both 20 degrees, and the sample is marked as No. 6.
Comparative example 4
This sample had the same raw material, casting and solution treatment as example 2, but was not subjected to torsional deformation and was designated as sample No. 7.
Subsequently, four samples were subjected to a fatigue resistance test at room temperature in which the loading manner was tension-compression, the cyclic loading frequency was 0.01Hz, and the ratio of the absolute minimum stress to the absolute maximum stress was-1. The test results are shown in table 2.
TABLE 2
| Sample (I) | Tensile yield strength | Compressive yield strength | Tensile-compressive fatigue limit |
| Example 2 (sample No. 4) | 149MPa | 187MPa | 128MPa |
| Example 3 (sample No. 5) | 138MPa | 189MPa | 123MPa |
| COMPARATIVE EXAMPLE 3 (sample No. 6) | 97MPa | 122MPa | 62MPa |
| COMPARATIVE EXAMPLE 4 (sample No. 7) | 101MPa | 114MPa | 67MPa |
As can be seen from Table 2, the tensile yield strength and the compressive yield strength of the No. 4 sample and the No. 5 sample (temperature-lowering torsion at a medium temperature of 360 ℃ to 270 ℃) are both obviously improved, meanwhile, the No. 4 sample has better fatigue resistance, the tensile-compressive fatigue limit at room temperature is improved to 128MPa, and the tensile-compressive fatigue limit is 2.1 times and 1.9 times of the fatigue limit of the No. 6 sample (isothermal torsion at a medium temperature of 360 ℃) and the No. 7 sample (no torsion). As can be seen, the temperature reduction and torsion obviously improve the fatigue resistance of the cast Mg-9Gd-4Y alloy.
Example 4
The invention discloses a method for improving the fatigue resistance of a cast magnesium alloy, which comprises the following steps:
in the embodiment, the raw material is casting Mg-4Al-8Sn alloy (mass percent) to be cast into a bar ingot blank, after solution treatment, the sample is subjected to 3 passes of reciprocating torsion at 450 ℃, the torsion rotation speed is 10rpm, each clockwise torsion and the subsequent anticlockwise torsion are both one pass, the clockwise and anticlockwise torsion angles in each pass are both 60 degrees, and no quenching is performed between each pass; 4-pass reciprocating torsion is carried out at 380-320 ℃, the torsion rotation speed is 2rpm, the clockwise and anticlockwise torsion angles in each pass are both 30 degrees, water quenching is carried out after each pass torsion, the heating is carried out again to the torsion temperature of the next pass, and the torsion temperature of the next pass is reduced by 20 ℃ compared with the torsion temperature of the previous pass; the sample was twisted back and forth at room temperature for 1 pass at a twist rate of 3rpm, with both clockwise and counterclockwise twist angles of 10 ° for each pass, and labeled sample No. 8.
Example 5
The present sample differs from example 4 only in the medium-temperature reciprocal torsion conditions, which are: and 4 passes of reciprocating torsion are carried out at the temperature of 280-260 ℃, the torsion temperature of the next pass is reduced by 5 ℃ compared with that of the previous pass, the torsion speed is 2rpm, the clockwise and anticlockwise torsion angles in each pass are both 30 degrees, and the sample is marked as sample No. 9.
Comparative example 5
For comparison, this sample has the same raw material, casting and solution treatment as example 4, but is not torsionally deformed and is labeled sample No. 10.
The three samples were subjected to a fatigue resistance test at room temperature in a tensile-compressive loading manner at a cyclic loading frequency of 10Hz and a ratio of the absolute minimum stress to the absolute maximum stress of-1. The test results are shown in table 3.
TABLE 3
| Sample (I) | Tensile yield strength | Compressive yield strength | Tensile-compressive fatigue limit |
| Example 4 (sample No. 8) | 137MPa | 153MPa | 105MPa |
| Example 5 (sample No. 9) | 132MPa | 147MPa | 83MPa |
| COMPARATIVE EXAMPLE 5 (sample No. 10) | 82MPa | 134MPa | 40MPa |
As can be seen from Table 3, the tensile yield strength and the compressive yield strength of the No. 8 sample and the No. 9 sample after temperature reduction and torsion are both obviously improved, meanwhile, the No. 8 sample obtains better fatigue resistance improvement, and the tensile-compressive fatigue limit at room temperature is improved to 105MPa which is 2.6 times of the fatigue limit of the No. 10 sample without temperature reduction and torsion. As can be seen, the temperature reduction torsion obviously improves the fatigue resistance of the casting state Mg-4Al-8Sn alloy.
Example 6
The invention discloses a method for improving the fatigue resistance of a cast magnesium alloy, which comprises the following steps:
in the embodiment, the raw material is casting Mg-4Nd-3Y alloy (mass percentage), a bar ingot is cast, after solution treatment, the sample is subjected to 3 passes of reciprocating torsion at 480 ℃, the torsion rotation speed is 10rpm, each clockwise torsion and the subsequent anticlockwise torsion are both one pass, the clockwise and anticlockwise torsion angles in each pass are both 80 degrees, and no quenching is performed between each pass; performing 6 passes of reciprocating torsion at 300-250 ℃, wherein the torsion rotation speed is 1rpm, the clockwise and anticlockwise torsion angles in each pass are both 50 degrees, after each pass of torsion, water quenching is performed, and the next pass of torsion is reheated to the torsion temperature of the next pass, and the torsion temperature of the next pass is reduced by 10 ℃ compared with the torsion temperature of the previous pass; the reciprocal twisting was performed in 2 passes at room temperature, at a rotation speed of 0.5rpm, with both clockwise and counterclockwise twisting angles of 20 ° per pass, and labeled sample No. 11.
Comparative example 6
The sample is different from the sample in example 6 in that the sample is not subjected to high-temperature and medium-temperature torsion under different torsion conditions, the sample is subjected to isothermal torsion for 2 passes at room temperature, the torsion rotation speed is 0.5rpm, the clockwise torsion angle and the anticlockwise torsion angle in each pass are both 20 degrees, and the sample is marked as sample No. 12.
Comparative example 7
This sample had the same raw material, casting and solution treatment as example 6, but was not subjected to torsional deformation and was designated as sample No. 13.
The three samples were subjected to a fatigue resistance test at room temperature in a tensile-tensile manner with a cyclic loading frequency of 10Hz and a ratio of the absolute minimum stress to the absolute maximum stress of 0. The test results are shown in table 4.
TABLE 4
| Sample (I) | Tensile yield strength | Tensile-tensile fatigue limit |
| Example 6 (sample No. 11) | 97MPa | 75MPa |
| COMPARATIVE EXAMPLE 6 (sample No. 12) | 66MPa | 41MPa |
| COMPARATIVE EXAMPLE 7 (sample No. 13) | 69MPa | 41MPa |
As can be seen from Table 4, the tensile yield strength of the No. 11 sample after temperature reduction and torsion is significantly improved, and the tensile-tensile fatigue limit at room temperature is also improved to 75MPa, which is 1.8 times of the fatigue limit of the No. 12 sample subjected to isothermal torsion and the No. 13 sample not subjected to torsion. Therefore, the temperature reduction reciprocating torsion obviously improves the fatigue resistance of the casting state Mg-4Nd-3Y alloy.
Example 7
The invention discloses a method for improving the fatigue resistance of a cast magnesium alloy, which comprises the following steps:
in the embodiment, the raw material is Mg-6Zn-0.8Zr alloy (mass percent) in a casting state, a bar ingot blank is cast, after solution treatment, the sample is subjected to reciprocating torsion for 2 passes at 450 ℃, the torsion speed is 12rpm, each clockwise torsion and the subsequent anticlockwise torsion are both one pass, the clockwise and anticlockwise torsion angles in each pass are both 50 degrees, and no quenching is performed between each pass; 2-pass reciprocating torsion is carried out at the temperature of 300-250 ℃, the torsion rotation speed is 0.5rpm, the clockwise and anticlockwise torsion angles in each pass are 10 degrees, water quenching is carried out after each pass torsion, the heating is carried out again to the torsion temperature of the next pass, and the torsion temperature of the next pass is reduced by 50 ℃ compared with the torsion temperature of the previous pass; the sample was twisted back and forth at-125 ℃ for 1 pass at a twist rate of 0.05rpm, with both clockwise and counterclockwise twist angles of 10 ° per pass, and labeled sample No. 14.
Example 8
The sample differs from example 7 only in that the low temperature twist conditions are different, the sample is twisted back and forth at room temperature for 1 pass, the twist speed is 5rpm, the clockwise and counterclockwise twist angles in each pass are both 10 °, and the sample is marked as sample No. 15.
Comparative example 8
The sample has the same raw materials, casting and solution treatment as example 7, the sample is subjected to 5 passes of isothermal torsion at 250 ℃, the torsion rotation speed is 0.5rpm, the clockwise and anticlockwise torsion angles in each pass are 10 degrees, the sample is water-quenched and reheated to 250 ℃ after each pass of torsion, and the sample is marked as sample No. 16.
Comparative example 9
This sample had the same raw material, casting and solution treatment as example 7, but was not twisted and was marked as sample No. 17.
The four samples are subjected to a fatigue resistance test in a compression-compression loading mode at 200 ℃, the cyclic loading frequency is 50Hz, and the ratio of the absolute minimum stress to the absolute maximum stress is 0. The test results are shown in table 5.
TABLE 5
| Sample (I) | Compressive yield strength | Compression-compression fatigue limit |
| Example 7 (sample No. 14) | 127MPa | 96MPa |
| Example 8 (sample No. 15) | 121MPa | 94MPa |
| COMPARATIVE EXAMPLE 8 (sample No. 16) | 93MPa | 50MPa |
| COMPARATIVE EXAMPLE 9 (sample No. 17) | 98MPa | 52MPa |
As can be seen from Table 5, the compressive yield strength of the sample No. 14 and the sample No. 15 after temperature reduction and torsion are obviously improved, meanwhile, the fatigue resistance of the sample No. 14 is improved better, and the compression-compression fatigue limit at 150 ℃ is improved to 96MPa, which is 1.9 times and 1.8 times of the fatigue limit of the sample No. 16 and the sample No. 17 which are isothermally twisted and are not twisted respectively. Therefore, the temperature reduction reciprocating torsion obviously improves the fatigue resistance of the casting state Mg-6Zn-0.8Zr alloy.
Example 9
The invention discloses a method for improving the fatigue resistance of a cast magnesium alloy, which comprises the following steps:
in the embodiment, the raw material is casting Mg-3Al-1.2Sn alloy (mass percent) and is cast into a bar ingot blank, after solution treatment, the sample is subjected to reciprocating torsion for 4 passes at 550 ℃, the torsion speed is 15rpm, each clockwise torsion and the subsequent anticlockwise torsion are both one pass, the clockwise and anticlockwise torsion angles in each pass are both 100 degrees, and no quenching is performed between each pass; performing 6 passes of reciprocating torsion at 450-300 ℃, wherein the torsion rotation speed is 5rpm, the clockwise and anticlockwise torsion angles in each pass are both 100 degrees, after each pass of torsion, water quenching is performed, and the next pass of torsion is reheated to the torsion temperature of the next pass, and the torsion temperature of the next pass is reduced by 30 ℃ compared with the torsion temperature of the previous pass; the reciprocal twisting was performed in 3 passes at room temperature, at a twisting speed of 5rpm, with clockwise and counterclockwise twisting angles of 80 ° in each pass, and labeled sample No. 18.
Comparative example 10
In comparison, this sample, which had the same raw materials, casting and solution treatment as example 9, was subjected to isothermal back-and-forth twisting at 400 ℃ for 6 passes only, at a 5rpm twist rate, at 100 ° clockwise and counterclockwise twist angles for each pass, and was water quenched and reheated to 400 ℃ after each pass of twisting, and labeled sample No. 19.
Comparative example 11
This sample had the same raw material, casting and solution treatment as example 9, but was not twisted and was marked as sample No. 20.
The three samples were subjected to a fatigue resistance test at 100 ℃ in a tensile-compressive loading manner at a cyclic loading frequency of 1Hz and a ratio of the absolute minimum stress to the absolute maximum stress of-1. The test results are shown in table 6.
TABLE 6
| Sample (I) | Tensile yield strength | Compressive yield strength | Tensile-compressive fatigue limit |
| Example 9 (sample No. 18) | 113MPa | 126MPa | 85MPa |
| COMPARATIVE EXAMPLE 10 (sample No. 19) | 78MPa | 94MPa | 43MPa |
| COMPARATIVE EXAMPLE 11 (sample No. 20) | 83MPa | 86MPa | 45MPa |
As can be seen from Table 6, the tensile yield strength and compressive yield strength of the 18 th sample after temperature reduction and torsion are both significantly improved, and the fatigue limit at 100 ℃ is also improved to 85MPa, which is 2.0 times of the fatigue limit of the 19 th sample subjected to isothermal torsion and the fatigue limit of the 20 th sample not subjected to torsion. Therefore, the temperature reduction reciprocating torsion obviously improves the fatigue resistance of the casting state Mg-3Al-1.2Sn alloy.
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make many possible variations and modifications to the disclosed embodiments, or equivalent modifications, without departing from the spirit and scope of the invention, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention.
Claims (10)
1. A method for improving the fatigue resistance of cast magnesium alloy is characterized by comprising the following steps:
firstly carrying out high-temperature reciprocating torsion on the magnesium alloy ingot blank subjected to the solution treatment, wherein the temperature of the high-temperature reciprocating torsion is 450-550 ℃, the rotating speed is 10-15 rpm, then carrying out multiple times of medium-temperature reciprocating torsion at 250-450 ℃, wherein in the process of the multiple times of medium-temperature reciprocating torsion, the medium-temperature reciprocating torsion in the next time is lower than the torsion temperature of the medium-temperature reciprocating torsion in the previous time, and finally carrying out low-temperature reciprocating torsion, wherein the temperature of the low-temperature reciprocating torsion is-125 ℃ to room temperature.
2. The method for improving the fatigue resistance of the cast magnesium alloy as claimed in claim 1, wherein the high temperature reciprocating twisting is performed for 2-4 passes of reciprocating twisting.
3. The method for improving the fatigue resistance of the cast magnesium alloy as claimed in claim 2, wherein each clockwise twist and the subsequent counterclockwise twist are the same as the reciprocating twist of one pass at the time of the high-temperature reciprocating twist, and the clockwise twist and the counterclockwise twist in each pass are both at an angle of 50-100 °.
4. The method for improving the fatigue resistance of the cast magnesium alloy as claimed in any one of claims 1 to 3, wherein the medium-temperature reciprocating torsion is performed for 2 to 6 times of reciprocating torsion; the torsion rotating speed of the medium-temperature reciprocating torsion is 0.5-5 rpm;
in the process of several times of medium-temperature reciprocating torsion, the medium-temperature reciprocating torsion of the next time is reduced by 10-50 ℃ compared with the torsion temperature of the medium-temperature reciprocating torsion of the previous time.
5. The method for improving the fatigue resistance of the cast magnesium alloy as claimed in claim 4, wherein at the medium-temperature reciprocating torsion, each clockwise torsion and the subsequent anticlockwise torsion are the reciprocating torsion of one pass, and the clockwise torsion and the anticlockwise torsion in each pass are the same in angle and are both 10-100 degrees.
6. The method for improving the fatigue resistance of the cast magnesium alloy as claimed in any one of claims 1 to 3, wherein the low-temperature reciprocating torsion is performed for 1 to 3 passes; the torsion rotation speed is 0.05-5 rpm.
7. The method for improving the fatigue resistance of the cast magnesium alloy as claimed in claim 6, wherein each clockwise twist and the subsequent counterclockwise twist are the same reciprocating twist of one pass at the time of the low-temperature reciprocating twist, and the clockwise twist and the counterclockwise twist in each pass have the same angle of 10-80 °.
8. The method for improving the fatigue resistance of the cast magnesium alloy as claimed in claim 1, wherein the high temperature reciprocating torsion temperature is in the range of 480 to 550 ℃;
the medium-temperature reciprocating torsion temperature range is 300-450 ℃.
9. The method for improving the fatigue resistance of the cast magnesium alloy as claimed in claim 1, wherein the temperature range of the low-temperature reciprocating torsion is-125 to-20 ℃; the torsion rotating speed of the low-temperature reciprocating torsion is 0.05-3 rpm.
10. The method for improving fatigue resistance of cast magnesium alloy as claimed in claim 1, wherein said cast magnesium alloy is selected from the group consisting of Mg-Al-Sn, Mg-Zn-Zr series and rare earth magnesium alloys.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011084791A (en) * | 2009-10-16 | 2011-04-28 | National Institute Of Advanced Industrial Science & Technology | High-strength high-ductility magnesium alloy extruded material, and method for producing the same |
| CN103540881A (en) * | 2013-11-08 | 2014-01-29 | 中南大学 | Processing method for improving drawing and pressing asymmetry of magnesium alloy |
| CN104498848A (en) * | 2015-01-21 | 2015-04-08 | 西南大学 | Processing method of magnesium alloy bar material |
| CN110512129A (en) * | 2019-08-30 | 2019-11-29 | 中南大学 | A kind of forging torsion integrated technique preparing superelevation severe deformation magnesium alloy rod |
-
2020
- 2020-08-26 CN CN202010872418.7A patent/CN112030086B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011084791A (en) * | 2009-10-16 | 2011-04-28 | National Institute Of Advanced Industrial Science & Technology | High-strength high-ductility magnesium alloy extruded material, and method for producing the same |
| CN103540881A (en) * | 2013-11-08 | 2014-01-29 | 中南大学 | Processing method for improving drawing and pressing asymmetry of magnesium alloy |
| CN104498848A (en) * | 2015-01-21 | 2015-04-08 | 西南大学 | Processing method of magnesium alloy bar material |
| CN110512129A (en) * | 2019-08-30 | 2019-11-29 | 中南大学 | A kind of forging torsion integrated technique preparing superelevation severe deformation magnesium alloy rod |
Non-Patent Citations (1)
| Title |
|---|
| QINGHUAN HUO: "Enhanced fatigue properties of cast AZ80 Mg alloy processed by cyclic", 《MATERIALS SCIENCE & ENGINEERING A》 * |
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