Magnesium alloy plate and preparation process thereof

Abstract

The invention relates to the technical field of catalyst preparation, in particular to a magnesium alloy plate and a preparation process thereof, and the magnesium alloy plate comprises the following components in percentage by weight: 3-5wt% of Gd, 0.3-0.8 wt% of Zr, 0.5-1.5 wt% of Nd and the balance of Mg and inevitable impurities. In addition, the invention provides a magnesium alloy plate and a preparation process thereof, and can provide an effective method for solving the problems that the mechanical property of magnesium alloy is not ideal and the like.

Description

[Technical field]

[0001] The invention belongs to the technical field of alloy heat treatment, and in particular relates to a magnesium alloy plate and a preparation process thereof. [Background technology]

[0002] Bake hardening is an efficient and convenient modification method to improve the hardness and strength of materials through heat treatment. During the pre-deformation annealing process, elements are concentrated on dislocations, which can pin dislocations and hinder dislocation movement, thereby causing annealing strengthening of the alloy. During the pre-deformation annealing process, elements can also be concentrated on stacking faults, thereby causing strengthening of the alloy.

[0003] Magnesium alloy is the lightest metal structural material. Its application in transportation, electronic information, aerospace and other fields can effectively reduce product weight, energy consumption and greenhouse gas emissions. Although magnesium alloy has been widely used in transportation, electronic information, aerospace and other fields, its room temperature strength and plasticity are poor compared with aluminum alloy and steel, which limits its further development and application.

[0004] Therefore, how to improve the mechanical properties of magnesium alloys is a technical problem that needs to be solved in this application. [Summary of the invention]

[0005] In view of the above, it is necessary to provide a magnesium alloy sheet and its preparation process, study the pre-deformation annealing process and optimize the annealing strengthening effect, which is of great significance to improving the mechanical properties of magnesium alloys.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A magnesium alloy plate and a preparation process thereof. The magnesium alloy plate has the following components in weight fractions: Gd: 3-5wt%, Zr: 0.3-0.8wt%, Nd: 0.5-1.5wt%, and the balance is Mg and inevitable impurities.

[0008] In the present invention, further, the magnesium alloy sheet has the following components in weight fractions: Gd: 4wt%, Zr: 0.5wt%, Nd: 1wt%, and the balance is Mg and inevitable impurities.

[0009] The present invention also provides a preparation process of the alloy plate, which comprises the following steps:

[0010] S1 smelting: melting and casting the elements Gd, Zr, Nd and Mg to obtain an ingot;

[0011] S2 homogenization treatment: homogenization treatment is performed on the ingot obtained in S1, and the homogenization treatment temperature is 500-520°C;

[0012] S3 extrusion processing: the ingot treated in S2 is peeled, and then put into an extrusion die, and extruded at an extrusion temperature of 420-470°C and an extrusion speed of 1.0-2.0 mm / s to obtain an extruded sheet;

[0013] S4 pre-deformation: the alloy plate treated in S3 is subjected to pre-stretching deformation treatment, and the stretching deformation amount is 2-8%;

[0014] S5 annealing: anneal the sample after S4 treatment, and then air cool the sample to obtain a magnesium alloy sheet.

[0015] In the present invention, further, in said S2, the homogenization treatment time is 12-16 hours.

[0016] In the present invention, further, in said S3, before the extrusion process, the ingot and the mold are firstly preheated, specifically, maintained at a temperature of 420-470° C. for 0.5-1.5 hours.

[0017] In the present invention, further, in said S4, the direction of the tensile deformation is the ED direction.

[0018] In the present invention, further, in said S5, the temperature of the annealing heat treatment is 160-200° C., and the holding time is 1-3 hours.

[0019] The present invention has the following beneficial effects:

[0020] The present invention proposes a preparation process for a magnesium alloy sheet. On the basis of not increasing the material cost, the extruded Mg-Gd-Zr-1Nd alloy sheet is pre-deformed to introduce defects such as dislocations and stacking faults. The Nd element has a high solid solubility in the Mg-Gd alloy and can react with Mg and Gd to generate a strengthening phase, thereby improving the mechanical properties of the alloy through solid solution strengthening and precipitation strengthening mechanisms. The present invention adds Nd elements to the Mg-Gd alloy to precipitate β′ and β strengthening phases, thereby enhancing the aging strengthening effect and mechanical properties of the alloy. Then, through heat treatment annealing, the Gd and Nd elements can be promoted to segregate in defects, further improving the strength of the extruded alloy sheet. The present application improves the research and application of pre-deformation annealing treatment of magnesium alloys. The magnesium alloy sheet obtained by the preparation process described in the present application has the advantage of greatly improved yield strength and good economy and practicality.

Brief Description of the Drawings

[0021] Figure 1 The engineering stress-strain curves of the extruded Mg-4Gd-0.5Zr-1Nd alloy plate under different conditions according to Example 3 of the present invention;

[0022] Figure 2The engineering stress-strain curves of the extruded Mg-4Gd-0.5Zr-1Nd alloy plate under different pre-stretching values ​​according to Example 3 of the present invention;

[0023] Figure 3 The inverse pole figure, average orientation difference diagram and orientation difference distribution diagram of the extruded Mg-4Gd-0.5Zr-1Nd alloy sheet under 2%, 5% and 8% pre-stretching values ​​according to the embodiment of the present invention;

[0024] Figure 4 This is a transmission analysis diagram of the extruded Mg-4Gd-0.5Zr-1Nd alloy plate after pre-deformation (8%) and annealing (180°C for 2h) according to Example 3 of the present invention. [Specific implementation method]

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0026] Embodiment 1:

[0027] The present embodiment provides a magnesium alloy plate material, wherein the magnesium alloy plate material has the following components in weight fractions: Gd: 3wt%, Zr: 0.3wt%, Nd: 0.5wt%, and the balance is Mg and inevitable impurities.

[0028] This embodiment also provides a preparation process of the magnesium alloy sheet, comprising the following steps:

[0029] S1 smelting: melting and casting the elements Gd, Zr, Nd and Mg to obtain an ingot;

[0030] S2 homogenization treatment: the ingot obtained in S1 is homogenized at a temperature of 500°C for 16 hours;

[0031] S3 extrusion processing: the ingot after S2 treatment is peeled, and then put into the extrusion die, and extruded at an extrusion temperature of 420°C and an extrusion speed of 2.0 mm / s to obtain an extruded sheet; before the extrusion process, the ingot and the die are first preheated, specifically, the temperature is maintained at 420°C for 1.5 hours.

[0032] S4 pre-deformation: the alloy plate treated in S3 is subjected to pre-stretching deformation treatment, the stretching deformation amount is 2%, and the stretching deformation direction is the ED direction;

[0033] S5 annealing: anneal the sample after S4 treatment at a temperature of 160°C and a holding time of 3 hours. After annealing, air cool the sample to obtain a magnesium alloy sheet.

[0034] Embodiment 2:

[0035] The present embodiment provides a magnesium alloy plate material, wherein the magnesium alloy plate material has the following components in weight fractions: Gd: 5wt%, Zr: 0.8wt%, Nd: 1.5wt%, and the balance is Mg and inevitable impurities.

[0036] This embodiment also provides a preparation process of the magnesium alloy sheet, comprising the following steps:

[0037] S1 smelting: melting and casting the elements Gd, Zr, Nd and Mg to obtain an ingot;

[0038] S2 homogenization treatment: the ingot obtained in S1 is homogenized at a temperature of 520°C for 12 hours;

[0039] S3 extrusion processing: the ingot after S2 treatment is peeled, and then put into the extrusion die, and extruded at an extrusion temperature of 470°C and an extrusion speed of 1.0 mm / s to obtain an extruded sheet; before the extrusion process, the ingot and the die are first preheated, specifically, the temperature is maintained at 470°C for 0.5 hours.

[0040] S4 pre-deformation: the alloy plate treated by S3 is subjected to pre-stretching deformation treatment, the stretching deformation amount is 5%, and the stretching deformation direction is the ED direction;

[0041] S5 annealing: anneal the sample after S4 treatment at a temperature of 200°C and a holding time of 1h. After annealing, air cool the sample to obtain a magnesium alloy sheet.

[0042] Embodiment 3:

[0043] The present embodiment provides a magnesium alloy plate material, which has the following components in weight fractions: Gd: 4wt%, Zr: 0.5wt%, Nd: 1wt%, and the balance is Mg and inevitable impurities.

[0044] This embodiment also provides a preparation process of the magnesium alloy sheet, comprising the following steps:

[0045] S1 smelting: melting and casting the elements Gd, Zr, Nd and Mg to obtain an ingot;

[0046] S2 homogenization treatment: the ingot obtained in S1 is homogenized at a temperature of 510°C for 15 hours;

[0047] S3 extrusion processing: the ingot after S2 treatment is peeled, and then put into the extrusion die, and extruded at an extrusion temperature of 450°C and an extrusion speed of 1.5mm / s to obtain an extruded sheet; before the extrusion process, the ingot and the die are first preheated, specifically, the temperature is maintained at 450°C for 1 hour.

[0048] S4 pre-deformation: the alloy plate treated by S3 is subjected to pre-stretching deformation treatment, the stretching deformation amount is 8%, and the stretching deformation direction is the ED direction;

[0049] S5 annealing: anneal the sample after S4 treatment at a temperature of 180°C and a holding time of 2h. After annealing, air cool the sample to obtain a magnesium alloy sheet.

[0050] Performance Testing:

[0051] like Figure 1 As shown, a universal testing machine (CMT6305-300 KN) was used to perform a tensile test on the magnesium alloy obtained in Example 3, and the tensile speed was 1.5 mm / min. The tensile plate specimen was bone-shaped and marked with 12 mm. Pre-deformation only includes pre-stretching, and the pre-stretching amounts are 2%, 5% and 8%, respectively, and the direction is the ED direction. On this basis, the pre-stretched specimens under different conditions were annealed, and the annealing temperature of the pre-deformation annealing process was selected as 180°C, the holding time was 2 hours, and the specimens were air-cooled after annealing. Figure 1 (a) is its strain stress curve. It can be seen from the figure that the yield strength of the extruded Mg-4Gd-0.5Zr-1Nd alloy sheet after direct annealing is slightly lower than that of the original sheet, indicating that softening has occurred.

[0052] After the extruded Mg-4Gd-0.5Zr-1Nd alloy sheet was pre-deformed (5%), its room temperature tensile mechanical properties were tested. Figure 1 The red curve in (b) shows its tensile strain-stress curve. It can be seen that its tensile strain-stress curve continues to extend along the pre-deformed strain-stress curve, and no strengthening phenomenon is observed. After the extruded Mg-4Gd-0.5Zr-1Nd alloy sheet was pre-deformed (5%) and annealed (180℃ for 2h), its room temperature tensile mechanical properties were tested. Figure 1 The blue curve in (b) is its tensile strain stress curve. It can be seen from the figure that the strength of the alloy plate is significantly improved after pre-deformation annealing, and the strengthening increment value is 57.1MPa.

[0053] In addition, it can be seen from the tensile tests with different pre-stretching amounts that Figure 2 The extruded Mg-4Gd-0.5Zr-1Nd alloy sheets were further subjected to pre-deformation annealing treatment as shown in Table 1, and then their room temperature tensile mechanical properties were tested.

[0054] Table 1 Mechanical properties of alloy Mg-4Gd-0.5Zr-1Nd under different pre-stretching amounts

[0055] Pre-stretching amount Yield strength (MPa) Enhanced incremental value (MPa) 2％ 185.0±2.0 51.6±0.3 5％ 210.3±2.5 57.1±0.4 8％ 228.1±2.0 59.9±0.4

[0056] Figure 2 The engineering stress-strain curves of the extruded Mg-4Gd-0.5Zr-1Nd alloy sheet of Example 3 of the present invention at different pre-stretching values ​​are shown. It can be seen that the alloy sheets with 2%, 5% and 8% pre-stretching all show significant strengthening phenomenon, which can be described by "strengthening increment value", that is, the difference between the corresponding flow stress when the sheet is pre-deformed to the set strain value and the yield strength of the alloy sheet after pre-deformation annealing. As the pre-deformation amount increases from 2% to 5% to 8%, the strengthening increment values ​​of the alloy sheet are 51.6MPa, 57.1MPa and 59.9MPa respectively.

[0057] Figure 3 The EBSD observation results of the pre-deformed annealing of the extruded Mg-4Gd-0.5Zr-1Nd alloy sheet after 2%, 5% and 8% pre-deformation. It can be seen that there are a small number of twins in the alloy after pre-deformation, but its main deformation mode is dislocation slip. The number of twins is small. It can be seen from the orientation difference distribution diagram that with the increase of the pre-deformation amount, the dislocation density of the alloy increases accordingly. With the increase of the pre-deformation amount, the number of dislocations and stacking faults gradually increases, the number of locations where elements can be segregated in the alloy during the annealing process increases, and the element pinning, stabilizing dislocations and stacking faults are significantly enhanced, resulting in an increase in the strengthening increment value of the Mg-4Gd-0.5Zr-1Nd alloy sheet.

[0058] Figure 4 This is the transmission analysis diagram of the extruded Mg-4Gd-0.5Zr-1Nd alloy plate after 8% pre-deformation annealing. From the morphology and diffraction spots, it can be seen that there are stacking faults in the alloy. From the energy spectrum scanning diagram, it can be seen that Gd and Nd elements co-segregate on the stacking fault, and the segregation amount of Gd is about 4at.%, and the segregation amount of Nd is about 2.5at.%. This shows that Gd and Nd elements are prone to co-segregation, thereby pinning the stacking fault and enhancing the performance of the alloy.

[0059] In summary, the present application improves the research and application of pre-deformation annealing treatment of magnesium alloys. The magnesium alloy sheet obtained by the preparation process described in the present application has the advantage of greatly improved yield strength and has good economy and practicality.

[0060] The above-mentioned embodiments merely express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it should not be understood as limiting the scope of the present invention.

Claims

1. A magnesium alloy sheet, characterized in that: The magnesium alloy sheet has the following components in weight fractions: Gd: 3-5wt%, Zr: 0.3-0.8wt%, Nd: 0.5-1.5wt%, and the balance is Mg.

2. The magnesium alloy sheet according to claim 1, characterized in that: The magnesium alloy sheet has the following components in weight fractions: Gd: 4wt%, Zr: 0.5wt%, Nd: 1wt%, and the balance is Mg.

3. A process for preparing a magnesium alloy sheet according to claim 1 or 2, characterized in that: The process comprises the following steps: S1 smelting: melting and casting the elements Gd, Zr, Nd and Mg to obtain an ingot; S2 homogenization treatment: homogenization treatment is performed on the ingot obtained in S1, and the homogenization treatment temperature is 500-520°C; S3 extrusion processing: the ingot treated in S2 is peeled, and then put into an extrusion die, and extruded at an extrusion temperature of 420-470°C and an extrusion speed of 1.0-2.0 mm / s to obtain an extruded sheet; S4 pre-deformation: the alloy plate treated in S3 is subjected to pre-stretching deformation treatment, and the stretching deformation amount is 2-8%; S5 annealing: anneal the sample after S4 treatment, and then air cool the sample to obtain a magnesium alloy sheet.

4. The method according to claim 1, characterized in that: In S2, the homogenization treatment time is 12-16 hours.

5. The method according to claim 1, characterized in that In S3, before the extrusion process, the ingot and the mold are first preheated, specifically, at a temperature of 420-470° C. for 0.5-1.5 hours.

6. The method according to claim 1, characterized in that In the above S4, the direction of the tensile deformation is the ED direction.

7. The method according to claim 1, characterized in that In S5, the annealing heat treatment is performed at a temperature of 160-200° C. and a holding time of 1-3 hours.

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