Preparation method of high-alloying rare earth magnesium alloy capable of synchronously regulating and controlling strength and plasticity based on split texture / cylindrical surface composite texture

Abstract

The invention provides a preparation method of a high-alloying rare earth magnesium alloy capable of synchronously regulating and controlling strength and plasticity based on a split texture / cylindrical surface composite texture, and belongs to the technical field of magnesium alloy materials. A high-alloying rare earth magnesium alloy is selected and comprises the following components: 4.0%-10.0% of Y, 2.0%-5.0% of Nd, 0.01%-2.0% of Gd, 0.01%-2.0% of Zr, 0.01%-2.0% of Zn and the balance of magnesium and other inevitable impurity elements. According to the method, by regulating and controlling a hot working path and technological parameters thereof, a long-period stacking ordered phase formed by rare earth elements is used for inducing grain orientation transformation, and a'compression direction split texture ', a'transverse direction split texture' and a cylindrical surface composite texture are formed. According to the four textures, the strength in the specific direction can be improved by activating a conical surface sliding system, or the plasticity is improved by activating a base surface / cylindrical surface sliding system, and synchronous optimization of the strength and the plasticity is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesium alloy materials, and particularly relates to a preparation method of a highly alloyed rare earth magnesium alloy for synchronously regulating strength and plasticity based on split texture / cylindrical texture composite texture. Background Art

[0002] With the continuous development of aerospace technology, the demand for lightweight aerospace equipment is increasing day by day. Magnesium alloys have become the lightest structural materials due to their advantages such as low density, high specific strength and high specific stiffness. Among them, the WE series of magnesium alloys have the characteristics of low density and high specific strength due to the addition of various rare earth elements, and have broad application prospects in the aerospace field. However, the addition of a large number of various rare earth elements also results in poor plasticity of the WE series of magnesium alloys, and the difficulty in synchronously regulating strength and plasticity has become the main reason hindering their wide application.

[0003] An effective measure to synchronously regulate and improve the strength and plasticity of magnesium alloys is to form texture. Due to the hexagonal close-packed crystal structure of magnesium alloys, there are fewer slip systems that can be activated at room temperature. Forming texture can increase the number of slip systems that are easily activated during deformation, synchronously regulate its strength and plasticity, and the purpose of forming texture can be achieved by optimizing alloy composition and improving processing technology. Rare earth elements (such as Y, Gd, Nd) are the most practical and potential alloying elements for optimizing alloy composition. First of all, highly alloyed rare earth magnesium alloys (the types and contents of rare earth elements added are higher than those of the WE series) can improve the strength of magnesium alloys through forms such as grain boundary strengthening and solid solution strengthening because of the addition of a large amount of rare earth elements. Secondly, the rare earth elements enriched in highly alloyed rare earth magnesium alloys are prone to form different types of long-period stacking ordered phases (Long Period Stacking Ordered, LPSO). The evolution and deformation behavior of this second phase are dual-sensitive to the processing path: LPSO will undergo behaviors such as "dissolution" and "mass transfer" under the influence of different processing paths, changing the type and distribution of LPSO, and then regulating the formation of texture by affecting factors such as "grain size" and "aspect ratio"; LPSO is prone to undergo different deformation modes such as "kinking" and "twinning" during the deformation process, and the processing path will affect its main deformation mode, and thus has different induction effects on the formation of different types of texture. In summary, according to different processing paths, highly alloyed rare earth magnesium alloys can form different types of texture.

[0004] Patent CN202411201260.5 discloses a rare earth magnesium alloy and its preparation method. The rare earth magnesium alloy is composed of the following components by mass percentage: Zn: 6.0 - 8.0%, Y: 0.5 - 2.5%, RE: 0.05 - 0.33%, Zr: 0.30 - 0.60%, and the rest is magnesium and inevitable impurities. RE is selected from one or more of Nd, Gd, and Sm. The room temperature tensile strength of the rare earth magnesium alloy is 385 MPa and the elongation is 12.0%. The magnesium alloy obtained by this method has good mechanical properties but has the problem of poor plasticity, and it is difficult to simultaneously improve strength and plasticity.

[0005] Patent CN 202110301920.7 discloses a preparation method of a magnesium alloy sheet with a four-peak non-basal texture feature. Select a Mg-Zn-RE or Mg-Zn-Ca magnesium alloy sheet with a bimodal non-basal texture feature, take the straight line determined by the two points corresponding to the bimodal as the 0° reference line, and perform cold rolling and uniaxial tension respectively under the condition of lower than 150 °C to obtain that the texture poles of the sheet deflect both longitudinally and transversely and are more evenly distributed, presenting a four-peak non-basal texture feature, and the planar anisotropy Δr value is less than 0.15. The magnesium alloy obtained by this method can weaken the basal texture but the non-basal texture strength is low, which makes it difficult to utilize the low anisotropy feature of the non-basal texture and difficult to simultaneously improve the strength and plasticity of the magnesium alloy.

[0006] Patent CN202211588393.3 discloses a hot forging process of a super-high strength rare earth magnesium alloy in a high-temperature single-phase region. The rare earth magnesium alloy is composed of the following components by mass percentage: Gd: 12.8 - 13.4%, Fe: ≤0.05%, Cu: ≤0.05%, Si: ≤0.05%, Ni: ≤0.005%, and the balance is magnesium and inevitable impurities. This type of rare earth magnesium alloy utilizes the characteristics of high solid solubility and strong precipitation hardening of Gd element in magnesium, and combines hot forging processing in a high-temperature single-phase region to improve the forging performance and prepare super-high strength magnesium forgings. However, this processing method of "in the high-temperature single-phase region" requires heat preservation at 520 °C for 24 h (or more), which not only has high energy consumption but also does not fully utilize the advantage that rare earth elements (Gd element) are easy to form LPSO, and can only improve the strength of the rare earth magnesium alloy, and it is difficult to simultaneously improve plasticity.

[0007] Therefore, making full use of the characteristics that high-alloy rare earth magnesium alloys are easy to form LPSO, inducing texture formation through LPSO, and researching and developing a high-alloy rare earth magnesium alloy that synchronously regulates strength and plasticity based on split texture / cylindrical composite texture is of great significance for the application of lightweight materials in the aerospace field. Summary of the Invention

[0008] The object of the present invention is to provide a preparation method of a highly alloyed rare earth magnesium alloy for synchronously regulating strength and plasticity based on a split texture / cylindrical composite texture, so as to solve the technical problem that it is difficult to simultaneously improve the strength and plasticity of existing high rare earth magnesium alloys.

[0009] In order to achieve the above-mentioned invention object, the present invention provides the following technical solutions:

[0010] The present invention provides a preparation method of a highly alloyed rare earth magnesium alloy for synchronously regulating strength and plasticity based on a split texture / cylindrical composite texture, comprising the following steps:

[0011] Just perform hot working and quenching on the highly alloyed rare earth magnesium alloy in sequence;

[0012] The hot working is isothermal single-pass hot working, isothermal multi-pass hot working, high-temperature stepped cooling multi-pass hot working or low-temperature stepped cooling multi-pass hot working.

[0013] Furthermore, the highly alloyed rare earth magnesium alloy comprises the following components in mass percentages:

[0014] Y: 4.0 - 10.0%, Nd: 0.01 - 5.0%, Gd: 0.01 - 5.0%, Zr: 0.01 - 5.0%, Zn: 0.01 - 5.0%, and the balance is magnesium and other inevitable impurity elements.

[0015] Furthermore, the processing methods of the hot working include hot compression, forging, extrusion, rolling or drawing.

[0016] Furthermore, the isothermal single-pass hot working is to heat the highly alloyed rare earth magnesium alloy to 450 - 490°C at a heating rate of 5 - 15°C / s, hold for 200 - 400 s, and then perform one-pass hot working with a deformation rate of 60%.

[0017] Furthermore, the isothermal multi-pass hot working is to heat the highly alloyed rare earth magnesium alloy to 450 - 490°C at a heating rate of 5 - 15°C / s, hold for 200 - 400 s, and then perform three-pass hot working with a deformation rate of 20 - 40% for each pass, and hold for 200 - 400 s after each pass of hot working.

[0018] Furthermore, the multi-pass hot working with stepped cooling at high temperature is to heat the high-alloyed rare earth magnesium alloy to 450-490 °C at a heating rate of 5-15 °C / s, hold for 200-400 s, and then perform the first-pass hot working with a deformation rate of 8-13%; cool down to 410-440 °C at a cooling rate of 5-15 °C / s, hold for 200-400 s, and perform the second-pass hot working with an accumulated deformation rate of 18-25%; cool down to 360-380 °C at a cooling rate of 5-15 °C / s, hold for 200-400 s, and perform the third-pass hot working with an accumulated deformation rate of 30%.

[0019] Furthermore, the multi-pass hot working with stepped cooling at low temperature is to heat the high-alloyed rare earth magnesium alloy to 310-340 °C at a heating rate of 5-15 °C / s, hold for 200-400 s, and then perform the first-pass hot working with a deformation rate of 8-13%; cool down to 260-290 °C at a cooling rate of 5-15 °C / s, hold for 200-400 s, and perform the second-pass hot working with an accumulated deformation rate of 18-25%; cool down to 210-240 °C at a cooling rate of 5-15 °C / s, hold for 200-400 s, and perform the third-pass hot working with an accumulated deformation rate of 30%.

[0020] Furthermore, the quenching is water quenching.

[0021] Furthermore, the high-alloyed rare earth magnesium alloy is a plate with a thickness of 12 mm or a cylinder with a diameter of 10 mm and a height of 15 mm.

[0022] Furthermore, the split texture is formed during the processing, and the split texture includes the extrusion direction split texture and the transverse direction split texture; the columnar composite texture includes and columnar composite texture, and columnar composite texture.

[0023] Advantages of the present invention:

[0024] By regulating the hot working path (isothermal single-pass, multi-pass and multi-pass with stepped cooling) and its process parameters (deformation rate, temperature, pass interval), the present invention induces the grain orientation transformation by using the long-period stacking ordered (LPSO) structure formed by rare earth elements, and forms the "extruding direction (ED) split texture", the "transverse direction (TD) split texture", " and columnar composite texture" and " and "Cylindrical composite texture". These four textures can improve the strength in a specific direction by activating the conical slip system or enhance the plasticity by activating the basal / cylindrical slip system, achieving the synchronous optimization of strength and plasticity.

[0025] Comparing the "ED split texture", "TD split texture", " and "cylindrical composite texture" and " and "cylindrical composite texture" obtained in the present invention, it can be seen that the above four textures can synchronously regulate and improve the strength and plasticity of the high-alloyed rare earth magnesium alloy, and the regulating effect of the four textures depends on the position of the texture pole peak. The "ED split texture" and " and "cylindrical composite texture" can improve the strength of the ED and the plasticity of the non-ED, while the "TD split texture" and " and "cylindrical composite texture" can improve the strength of the TD and the plasticity of the non-TD. The present invention solves the problem that it is difficult to synchronously regulate and improve the strength and plasticity of traditional magnesium alloys, and is particularly suitable for aerospace lightweight structural materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of the isothermal single-pass hot compression process;

[0027] Figure 2 is a metallographic diagram of different types of LPSO formed in the high-alloyed rare earth magnesium alloy;

[0028] Figure 3 is a measured SEM image of different types of LPSO formed in the high-alloyed rare earth magnesium alloy;

[0029] Figure 4 is a measured {0001} pole figure of the ED split texture;

[0030] Figure 5 is a schematic diagram of the grain orientation of the ED split texture and a Wulff net calculation diagram of the pole peak distribution position;

[0031] Figure 6 is a schematic diagram of the isothermal multi-pass hot compression process;

[0032] Figure 7 is a measured {0001} pole figure of the TD split texture;

[0033] Figure 8 is a schematic diagram of the grain orientation of the TD split texture and a Wulff net calculation diagram of the pole peak distribution position;

[0034] Figure 9 is a schematic diagram of the high-temperature step-cooling hot compression process;

[0035] Figure 10 For and the measured {0001} pole figure of the cylindrical composite texture;

[0036] Figure 11 is a schematic diagram of the low-temperature step-cooling hot compression process;

[0037] Figure 12 For and the measured {0001} pole figure of the cylindrical composite texture;

[0038] Figure 13 is a statistical chart comparing the mechanical properties of the high-alloyed rare-earth magnesium alloy prepared by the present invention with the WE series of rare-earth magnesium alloys. Specific Embodiments

[0039] The present invention provides a method for preparing a high-alloyed rare-earth magnesium alloy based on synchronous regulation of strength and plasticity by split texture / cylindrical composite texture, comprising the following steps:

[0040] Performing hot working and quenching on the high-alloyed rare-earth magnesium alloy in sequence;

[0041] The hot working is isothermal single-pass hot working, isothermal multi-pass hot working, high-temperature step-cooling multi-pass hot working or low-temperature step-cooling multi-pass hot working.

[0042] In the present invention, the high-alloyed rare-earth magnesium alloy comprises the following components by mass percentage:

[0043] Y: 4.0 - 10.0%, Nd: 0.01 - 5.0%, Gd: 0.01 - 5.0%, Zr: 0.01 - 5.0%, Zn: 0.01 - 5.0%, and the balance is magnesium and other inevitable impurity elements. The rare-earth elements in the high-alloyed rare-earth magnesium alloy of the present invention have multiple functions: the rare-earth elements can refine the grains of the magnesium alloy, making the grains prone to orientation transformation to form texture, and the rare-earth elements are prone to form LPSO, which can not only induce the formation of texture but also increase the grain rotation by taking advantage of the characteristics of easy kinking and twinning of LPSO.

[0044] In the present invention, the raw material system of the high-alloyed rare-earth magnesium alloy is preferably Mg-4.7Y-2.1Nd-1.0Zn-0.6Gd-0.5Zr (wt%), which is prone to form Mg-Y-Zn type LPSO;

[0045] Preferably, the raw material system of the high-alloyed rare-earth magnesium alloy is preferably Mg-4.7Gd-2.1Nd-1.0Zn-0.6Y-0.5Zr (wt%), which is prone to form Mg-Gd-Zn type LPSO;

[0046] Preferably, the raw material system of the high-alloyed rare earth magnesium alloy is preferably Mg-9.4Y-4.2Nd-1.2Gd-1.0Zn-0.5Zr (wt%), which is easy to form the Mg-Gd-Y-Zn type LPSO;

[0047] The above high-alloyed rare earth magnesium alloy is used for hot working under the condition that the deformation rate is 0.1 s -1 .

[0048] In the present invention, the processing methods of the hot working include hot compression, forging, extrusion, rolling or drawing, preferably hot compression or rolling.

[0049] In the present invention, when the hot working is isothermal single-pass hot working, the isothermal single-pass hot working is to heat the high-alloyed rare earth magnesium alloy to 450-490 °C at a heating rate of 5-15 °C / s, hold for 200-400 s, and then perform a single-pass hot working with a deformation rate of 60%;

[0050] Preferably, the high-alloyed rare earth magnesium alloy is heated to 475 °C at a heating rate of 10 °C / s, held for 300 s, and then a single-pass hot working is performed with a deformation rate of 60%.

[0051] In the present invention, the LPSO formed by the high-alloyed rare earth magnesium alloy in the "isothermal single-pass hot working" is mainly the Mg-Y-Zn type LPSO, which further induces the formation of an ED split texture. Since the deflection angle range of the normal direction (i.e., the c-axis) of the ED split texture {0001} is from ND to ED by 60°-85° (60°≤θ≤85°), when the magnesium alloy ED split texture bears the load in the ED direction, the c-axis direction of the grains bears the main load, and it is necessary to activate the cone plane slip system to make the grains slip in the c-axis direction to coordinate the deformation. However, the critical resolved shear stress of the cone plane slip system is relatively high and it is not easy to slip, which improves the flow stress in the ED direction; on the other hand, since the deflection angle range of the normal direction of the ED split texture grains {1010} is from TD to ND by 50°-80° When bearing the load in the ND or TD direction, it is necessary to pass through the basal plane Slip and cylinder surface Slip is used to coordinate deformation, and the critical resolved shear stresses of both are lower than those of the conical slip system, which can improve the plasticity of the magnesium alloy in the ND and TD directions.

[0052] In the present invention, when the hot working is isothermal multi-pass hot working, the isothermal multi-pass hot working is to heat the highly alloyed rare earth magnesium alloy to 450 - 490 °C at a heating rate of 5 - 15 °C / s, hold for 200 - 400 s, and then perform three-pass hot working. The deformation rate of each pass of hot working is 20 - 40%, and after each pass of hot working, it is held for 200 - 400 s;

[0053] Preferably, the highly alloyed rare earth magnesium alloy is heated to 475 °C at a heating rate of 10 °C / s, held for 300 s, and then three-pass hot working is performed. The deformation rate of each pass of hot working is 20 - 30%, and after each pass of hot working, it is held for 300 s.

[0054] In the present invention, the LPSO formed by the "isothermal multi-pass hot working" of the highly alloyed rare earth magnesium alloy is mainly of the Mg-Gd-Zn type LPSO, and then induces the formation of a TD split texture. Since the range of the c-axis deflection angle of the TD split texture grains is from 15° to 50° deflected from TD to ND When bearing TD loads, the load is mainly borne in the direction of the c-axis of the grains. The grains need to coordinate deformation through the conical <c + a> slip, and the critical resolved shear stress of the conical slip system is relatively high and it is not easy to slip, which will increase the flow stress in the TD direction; due to the TD split texture grains The normal deflection angle range is from 50° to 80° (50° ≤ θ ≤ 80°) deflected from ND to TD. When bearing ND or ED direction loads, it mainly relies on the prismatic and basal slip systems to coordinate deformation, and the critical resolved shear stresses of both are lower than those of the conical slip system. Therefore, with the help of the basal Slip and cylinder surface Slip can improve the plasticity in the ND and ED directions.

[0055] In the present invention, when the hot working is high-temperature step-down multi-pass hot working, the high-temperature step-down multi-pass hot working is to heat the highly alloyed rare-earth magnesium alloy to 450 - 490 °C at a heating rate of 5 - 15 °C / s, hold for 200 - 400 s, and then perform the first-pass hot working with a deformation rate of 8 - 13%; cool down to 410 - 440 °C at a cooling rate of 5 - 15 °C / s, hold for 200 - 400 s, and perform the second-pass hot working with an accumulated deformation rate of 18 - 25%; cool down to 360 - 380 °C at a cooling rate of 5 - 15 °C / s, hold for 200 - 400 s, and perform the third-pass hot working with an accumulated deformation rate of 30%.

[0056] Preferably, heat the highly alloyed rare-earth magnesium alloy to 475 °C at a heating rate of 10 °C / s, hold for 300 s, and then perform the first-pass hot working with a deformation rate of 10%; cool down to 425 °C at a cooling rate of 10 °C / s, hold for 300 s, and perform the second-pass hot working with an accumulated deformation rate of 20%; cool down to 375 °C at a cooling rate of 10 °C / s, hold for 300 s, and perform the third-pass hot working with an accumulated deformation rate of 30%.

[0057] In the present invention, the LPSO formed by the "high-temperature step-down multi-pass hot working" of the highly alloyed rare-earth magnesium alloy is mainly the high-temperature Mg-Gd-Y-Zn type LPSO, thereby inducing the formation of and columnar composite texture. This columnar texture is composed of columnar texture and columnar texture. From the pole figure, the pole peaks of these two columnar textures are both located at the two poles of the horizontal axis (i.e., the ED compression direction) in the {0001} pole figure, and in and the pole peaks of the pole figure are distributed along the vertical axis (i.e., the TD transverse direction). and When the columnar composite texture is loaded in the ED compression direction, it is the c-axis direction of the grains that bears the load. It is necessary to activate the pyramidal slip system to make the grains slip in the c-axis direction to coordinate the deformation, but the critical resolved shear stress of the pyramidal slip system is relatively high and it is not easy to slip, which increases the flow stress of the highly alloyed rare-earth magnesium alloy in the ED compression direction; on the other hand, and when the columnar composite texture is loaded in the TD transverse direction, it is necessary to pass through the basal plane Slip and cylinder surface Slip is used to coordinate deformation, and the critical resolved shear stresses of both are lower than those of the conical slip system, which improves the plasticity of the high-alloyed rare-earth magnesium alloy in the normal direction and the TD transverse direction.

[0058] In the present invention, when the hot working is low-temperature stepwise cooling multi-pass hot working, the low-temperature stepwise cooling multi-pass hot working is to heat the high-alloyed rare-earth magnesium alloy to 310 - 340 °C at a heating rate of 5 - 15 °C / s, hold for 200 - 400 s, and then perform the first-pass hot working with a deformation rate of 8 - 13%; cool to 260 - 290 °C at a cooling rate of 5 - 15 °C / s, hold for 200 - 400 s, and perform the second-pass hot working with a cumulative deformation rate of 18 - 25%; cool to 210 - 240 °C at a cooling rate of 5 - 15 °C / s, hold for 200 - 400 s, and perform the third-pass hot working with a cumulative deformation rate of 30%.

[0059] Preferably, the high-alloyed rare-earth magnesium alloy is heated to 325 °C at a heating rate of 10 °C / s, held for 300 s, and then the first-pass hot working is performed with a deformation rate of 10%; cooled to 275 °C at a cooling rate of 10 °C / s, held for 300 s, and the second-pass hot working is performed with a cumulative deformation rate of 20%; cooled to 225 °C at a cooling rate of 10 °C / s, held for 300 s, and the third-pass hot working is performed with a cumulative deformation rate of 30%.

[0060] In the present invention, the LPSO formed by the high-alloyed rare-earth magnesium alloy in "low-temperature stepwise cooling multi-pass hot working" is mainly the low-temperature Mg-Gd-Y-Zn type LPSO, which further induces the formation of and cylindrical composite texture. This cylindrical texture is composed of cylindrical texture and cylindrical texture. From the pole figure, the poles of these two cylindrical textures are located at both poles of the vertical axis (i.e., the TD transverse direction) in the {0001} pole figure, and in and the pole peaks of the pole figure are distributed along the horizontal axis (i.e., the ED compression direction). and When the cylindrical composite texture is loaded in the normal direction and the TD transverse direction, it is the c-axis direction of the grains that bears the load, and the conical slip system needs to be activated to make the grains slip in the c-axis direction to coordinate deformation. However, the critical resolved shear stress of the conical slip system is relatively high and it is not easy to slip, which improves the flow stress of the high-alloyed rare-earth magnesium alloy in the normal direction and the TD transverse direction; on the other hand, and When the cylindrical composite texture is loaded in the ED compression direction, it needs to pass through the basal plane Slip and cylinder surface Slip is used to coordinate deformation, and the critical resolved shear stresses of both are lower than those of the conical slip system, which improves the plasticity in the compression direction of the high-alloyed rare-earth magnesium alloy ED.

[0061] In the present invention, during the multi-pass hot working, heat preservation and unloading are carried out after the end of one pass, and reloading is carried out at the start of the next pass; the calculation method of the deformation rate of one pass in the multi-pass hot working is "the reduction amount divided by the height of the specimen before deformation in this pass", and the calculation method of the cumulative deformation amount is "the cumulative reduction amount divided by the height of the undeformed specimen".

[0062] The present invention utilizes the characteristic that the high-alloyed rare-earth magnesium alloy is prone to form different types of LPSO along different processing paths, and obtains different types of textures by the induction effect of LPSO on texture formation and the turning of grains to different orientations during hot working.

[0063] In the present invention, by carrying out different processing paths on the high-alloyed rare-earth magnesium alloy and regulating the hot working passes, deformation temperature and deformation rate, it is possible to cause the high-alloyed rare-earth magnesium alloy to form split textures in different directions, thereby realizing the synchronous regulation of the strength and plasticity of the high-alloyed rare-earth magnesium alloy.

[0064] In the present invention, the quenching is preferably water quenching.

[0065] In the present invention, the high-alloyed rare-earth magnesium alloy is a sheet with a thickness of 12 mm or a cylinder with a diameter of 10 mm and a height of 15 mm.

[0066] In the present invention, the split texture is formed during the processing, and the split texture includes a compression direction split texture and a transverse direction split texture; the columnar composite texture includes and columnar composite texture, and columnar composite texture.

[0067] In the present invention, from the {0001} pole figure, as a result of the change in grain orientation during the processing, the pole peaks of the "split texture" split at large angles towards both ends of the horizontal axis or the vertical axis of the pole figure. At this time, a large number of grains maintain a specific and obvious regular orientation angle, and the law can be seen from the measured pole peak positions using a Wulff net. For the ED split texture, the deflection angle range of the c-axis of the grains along the normal direction (Normal Direction, ND) towards ED is 60° to 85° (60° ≤ θ ≤ 85°), the deflection angle range of the normal direction along the TD of the specimen towards ND is 50° to 80° the deflection angle range of the c-axis of the TD split texture grains along TD towards the ND of the specimen is 15° to 50° The deflection angle range of the normal direction along the ND direction to the TD direction of the sample is 50° to 80° (50° ≤ θ ≤ 80°).

[0068] In the present invention, " and the cylindrical composite texture" is composed of " the cylindrical texture" and " the cylindrical texture". It can be seen from the {0001} pole figure that the characteristics of " the cylindrical texture" and " the cylindrical texture" exist simultaneously. " and the cylindrical composite texture" is composed of " <0001>the cylindrical texture" and " the cylindrical texture". It can be seen from the {0001} pole figure that the characteristics of " the cylindrical texture" and " the cylindrical texture" exist simultaneously.

[0069] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0070] Example 1

[0071] The present invention provides a preparation method for an ED split texture high-alloyed rare earth magnesium alloy.

[0072] Select a Mg-4.7Y-2.1Nd-1.0Zn-0.6Gd-0.5Zr sheet with a thickness of 12 mm for single-pass hot canned rolling, and the canning material is aluminum alloy. Heat it to 475 °C at a heating rate of 10 °C / s, keep it warm for 300 s and then roll it. The reduction is 7.2 mm, the remaining amount is 4.8 mm, and the deformation rate is 60%. After rolling, water quenching is carried out. The longitudinal section after deformation is the ND surface. It is detected that Mg-Y-Zn type LPSO is formed on the ND surface. See the metallographic pictures Figure 2 As shown, the SEM detection results are shown in Figure 3 As shown, it can be seen from the figure that the LPSO morphology is short and thick and the grain size is relatively large. The {0001} pole figure is obtained by EBSD detecting the ND plane, as shown in Figure 4As shown, due to the induction of the Mg-Y-Zn type LPSO, an ED split texture can be observed from the pole figure. The angular distribution of the ED split texture pole peaks was measured using a Wulff net, see Figure 5 As shown, let θ represent the radius, and the center of the circle is θ = 0°; represents the latitude, and the upper and lower poles are The deflection angle of the grain c-axis along the ND direction to the ED direction is 70° - 85°, The deflection angle in the normal direction is the deflection angle along the ND direction to the ED direction of 60° - 70°.

[0073] Example 2

[0074] As Figure 6 shown, the present invention provides a preparation method for a high-alloyed rare earth magnesium alloy with a TD split texture obtained by isothermal multi-pass rolling.

[0075] Mg-4.7Gd-2.1Nd-1.0Zn-0.6Y-0.5Zr plates with a thickness of 12 mm were selected for multi-pass encapsulated rolling, and the encapsulating material was aluminum alloy. It was heated to 475 °C at a heating rate of 10 °C / s, and held for 300 s for the first pass rolling, with a reduction of 2.4 mm, a remaining amount of 9.6 mm, a deformation rate of 20%, and an accumulated deformation rate of 20%. After compression, it was unloaded, and after holding for 300 s, the second pass rolling was carried out, with a reduction of 2.4 mm, a remaining amount of 7.2 mm, a deformation rate of 25%, and an accumulated deformation rate of 40%. After compression, it was unloaded, and after holding for 300 s, the third pass rolling was carried out, with a reduction of 2.4 mm, a remaining amount of 4.8 mm, a deformation rate of 33%, and an accumulated deformation rate of 60%. After rolling, it was water quenched. Taking the deformed longitudinal section as the ND plane, it was detected that Mg-Gd-Zn type LPSO was formed on the ND plane. See the metallographic pictures Figure 2 As shown, see the SEM detection results Figure 3 As shown, it can be seen from the figure that compared with the Mg-Y-Zn type LPSO, the morphology of this type of LPSO is refined and grows, and the grain size is reduced. The {0001} pole figure was obtained by EBSD detecting the ND plane. See Figure 7 As shown, since the Mg-Gd-Zn type LPSO has an inducing effect on the formation of the TD split texture, it can be seen from the pole figure that the TD split texture is formed. The angular distribution of the pole peaks was measured using a Wulff net. See Figure 8 As shown, let θ represent the radius, and the center of the circle is θ = 0°; represents the latitude, and the upper and lower poles are The deflection angle of the grain c-axis along the TD direction to the ND direction is 20° - 40°, and the grain The deflection angle of the normal direction along the TD direction to the ND direction is 50° - 70°.

[0076] Example 3

[0077] As Figure 9 shown, the present invention provides a preparation method of a " and cylindrical surface composite texture" high-alloyed rare earth magnesium alloy.

[0078] Select a cylindrical specimen of Mg-9.4Y-4.2Nd-1.2Gd-1.0Zn-0.5Zr with a diameter of 10 mm and a height of 15 mm, and perform "high-temperature stepped cooling multi-pass hot compression" with the height direction as the compression direction. Heat it to 475 °C at a heating rate of 10 °C / s, keep it warm for 300 s and then perform the first pass of hot compression. The reduction is 1.5 mm, the remaining amount is 13.5 mm, and the cumulative deformation rate is 10%. After the compression is completed, unload. Cool it to 425 °C at a cooling rate of 10 °C / s, keep it warm for 300 s and then perform the second pass of hot compression. The reduction is 1.5 mm, the remaining amount is 12 mm, and the cumulative deformation rate is 20%. After the compression is completed, unload. Cool it to 375 °C at a cooling rate of 10 °C / s, keep it warm for 300 s and then perform the third pass of hot compression. The reduction is 1.5 mm, the remaining amount is 10.5 mm, and the cumulative deformation rate is 30%. After the compression is completed, water quench. The longitudinal section of the third pass of hot compression is the ND plane. It is found that Mg-Gd-Y-Zn type LPSO is formed by detecting the ND plane. See the metallographic picture in Figure 2 shown, and the SEM detection result is shown in Figure 3 shown. It can be seen from the figure that at this time, the morphology of LPSO has both "short and thick" and "long and thin" morphologies, and the area ratio of LPSO is significantly larger than that of "Example 1" and "Example 2". The {0001} pole figure is obtained by EBSD detecting the ND plane. See Figure 10 shown. Since the Mg-Gd-Y-Zn type LPSO has an inducing effect on the formation of and cylindrical surface composite texture at high temperature, it can be observed from the pole figure that and cylindrical surface composite texture is formed.

[0079] Example 4

[0080] As Figure 11 shown, the present invention provides a preparation method of a " and cylindrical surface composite texture" high-alloyed rare earth magnesium alloy.

[0081] Select a cylindrical Mg-9.4Y-4.2Nd-1.2Gd-1.0Zn-0.5Zr specimen with a diameter of 10 mm and a height of 15 mm, and perform "low-temperature stepped cooling multi-pass hot compression" with the high direction as the compression direction. Heat it up to 325 °C at a heating rate of 10 °C / s, hold for 300 s, and then perform the first pass of hot compression with a reduction of 1.5 mm, a remaining amount of 13.5 mm, and a cumulative deformation rate of 10%. Unload after compression is completed. Cool it down to 275 °C at a cooling rate of 10 °C / s, hold for 300 s, and then perform the second pass of hot compression with a reduction of 1.5 mm, a remaining amount of 12 mm, and a cumulative deformation rate of 20%. Unload after compression is completed. Cool it down to 225 °C at a cooling rate of 10 °C / s, hold for 300 s, and then perform the third pass of hot compression with a reduction of 1.5 mm, a remaining amount of 10.5 mm, and a cumulative deformation rate of 30%. Quench in water after compression is completed. The longitudinal section after deformation is the ND plane. By detecting the ND plane with SEM, it is found that Mg-Gd-Y-Zn type LPSO is formed. See the metallographic picture in Figure 2 as shown, and the SEM detection results are shown in Figure 3 as shown. It can be seen from the figure that the LPSO morphology has both "short and thick" and "slender" types, but the "slender" LPSO is significantly more. Compared with other embodiments, the area ratio of LPSO is larger and the grain size is smaller at this time. The {0001} pole figure is obtained by detecting the ND plane with EBSD. See Figure 12 as shown. Since the Mg-Gd-Y-Zn type LPSO has an inducing effect on the formation of and the columnar composite texture, it can be observed from the pole figure that and the columnar composite texture is formed.

[0082] As can be seen from the above embodiments, the present invention provides a preparation method of a high-alloyed rare earth magnesium alloy for synchronously regulating strength and plasticity based on split texture / cylindrical composite texture. The present invention detects the mechanical properties of four textures. See Figure 13 as shown. By comparing with the mechanical properties of common WE series rare earth magnesium alloys, it can be known that the obtained "TD split texture" and " and cylindrical composite texture" high-alloyed rare earth magnesium alloys reduce the yield strength in the ED direction to improve plasticity, increase the yield strength in the TD direction, and the elongation at break increases overall. The obtained "ED split texture" and " and cylindrical composite texture" high-alloyed rare earth magnesium alloys reduce the yield strength in the TD direction to improve plasticity, increase the yield strength in the ED direction, and the elongation at break also increases overall. This shows that the method of the present invention can effectively synchronously regulate the strength and plasticity of the high-alloyed rare earth magnesium alloy and significantly improve both properties.

[0083] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a high-alloyed rare earth magnesium alloy based on split texture / cylindrical composite texture to simultaneously control strength and plasticity, characterized in that: The following steps are involved: The high alloyed rare earth magnesium alloy can be hot worked and quenched in sequence; The thermal processing is isothermal single-pass thermal processing, isothermal multi-pass thermal processing, high-temperature step-cooling multi-pass thermal processing or low-temperature step-cooling multi-pass thermal processing.

2. The preparation method according to claim 1, characterized in that: The high-alloyed rare earth magnesium alloy comprises the following components in percentage by mass: Y: 4.0-10.0%, Nd: 0.01-5.0%, Gd: 0.01-5.0%, Zr: 0.01-5.0%, Zn: 0.01-5.0%, and the balance is magnesium and other inevitable impurity elements.

3. The preparation method according to claim 2, characterized in that: The hot working method includes hot compression, forging, extrusion, rolling or drawing.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The isothermal single-pass hot working is to heat the high-alloyed rare earth magnesium alloy to 450-490° C. at a heating rate of 5-15° C. / s, keep the temperature for 200-400s, and then perform a hot working with a deformation rate of 60%.

5. The preparation method according to any one of claims 1 to 3, characterized in that: The isothermal multi-pass hot working is to heat the high-alloyed rare earth magnesium alloy to 450-490°C at a heating rate of 5-15°C / s, keep it warm for 200-400s, and then perform three hot working passes, with a deformation rate of 20-40% in each hot working pass, and keep it warm for 200-400s after each hot working pass.

6. The preparation method according to any one of claims 1 to 3, characterized in that: The high-temperature step cooling multi-pass hot processing is to heat the high-alloyed rare earth magnesium alloy to 450-490°C at a heating rate of 5-15°C / s, keep it warm for 200-400s, and then perform the first hot processing with a deformation rate of 8-13%; cool it to 410-440°C at a cooling rate of 5-15°C / s, keep it warm for 200-400s, and perform the second hot processing with a cumulative deformation rate of 18-25%; cool it to 360-380°C at a cooling rate of 5-15°C / s, keep it warm for 200-400s, and perform the third hot processing with a cumulative deformation rate of 30%.

7. The preparation method according to any one of claims 1 to 3, characterized in that: The low-temperature step cooling multi-pass hot processing is to heat the high-alloyed rare earth magnesium alloy to 310-340°C at a heating rate of 5-15°C / s, keep it warm for 200-400s, and then perform the first hot processing with a deformation rate of 8-13%; cool it to 260-290°C at a cooling rate of 5-15°C / s, keep it warm for 200-400s, and perform the second hot processing with a cumulative deformation rate of 18-25%; cool it to 210-240°C at a cooling rate of 5-15°C / s, keep it warm for 200-400s, and perform the third hot processing with a cumulative deformation rate of 30%.

8. The preparation method according to claim 1, characterized in that: The quenching is water quenching.

9. The preparation method according to claim 1 or 2, characterized in that: The high-alloyed rare earth magnesium alloy is a plate with a thickness of 12 mm or a cylinder with a diameter of 10 mm and a height of 15 mm.

10. The preparation method according to claim 9, characterized in that: The split texture is formed during the processing, and the split texture includes a compression direction split texture and a transverse direction split texture; the cylindrical composite texture includes and Cylindrical composite texture, and Cylindrical composite texture.

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