A method for room temperature power spinning forming based on non-base texture magnesium alloy plate

Abstract

The present application belongs to the technical field of metal plastic working, and particularly relates to a room temperature strong spinning forming method based on a non-basal plane texture magnesium alloy plate. In view of the poor room temperature forming performance of a traditional basal plane texture magnesium alloy and the problem that the room temperature strong spinning forming cannot be realized, the present application directly performs strong spinning under room temperature conditions by taking a non-basal plane texture magnesium alloy plate as an original blank. The single-pass thinning rate is 25% to 45%, and the multi-pass cumulative thinning rate is 50% to 85%. The present application breaks through the traditional technical limitation that magnesium alloy needs to be hot spun, and does not need heating and a protective atmosphere. The product is free of defects such as oxidation and grain coarsening, and the room temperature forming of a magnesium alloy thin-walled rotary body component can be realized in a high-efficiency and low-cost manner.

Description

Technical Field

[0001] This invention belongs to the field of metal plastic processing technology, specifically relating to a room temperature high-strength spinning forming method for magnesium alloy sheets with non-basal surface texture. Background Technology

[0002] Magnesium alloys possess advantages such as low density, high specific strength, and high specific stiffness, making them promising for applications in lightweighting applications in aerospace, rail transportation, automotive manufacturing, and 3C electronics. High-strength spinning, as an advanced continuous localized plastic forming technology, is an ideal process for manufacturing thin-walled rotating parts (such as conical and cylindrical components), improving material utilization and product mechanical properties.

[0003] In the field of high-strength spinning of magnesium alloys, existing research mainly focuses on hot spinning forming processes. When the temperature reaches above 200℃, the plasticity of magnesium alloys increases, and non-basal slip systems are easily activated, enabling spinning with a large amount of deformation. However, hot spinning has obvious drawbacks: (1) it requires heating devices and protective atmospheres, resulting in high equipment investment and complex process control; (2) the heating and cooling processes lead to long production cycles and high energy consumption; (3) at high temperatures, the material surface is prone to oxidation and grain coarsening, thereby reducing the quality and performance of spun products. Therefore, it is necessary to explore room temperature spinning technology that does not require heating to avoid the above problems.

[0004] However, conventional commercial magnesium alloy sheets (such as AZ31) tend to develop a strong basal texture during conventional rolling or extrusion, meaning that the (0001) basal planes of most grains are parallel to the sheet surface. This crystal orientation characteristic results in insufficient slip system activation in magnesium alloys at room temperature, leading to low plasticity and a tendency to crack during force spinning. Therefore, it is generally believed in the art that magnesium alloys cannot be subjected to force spinning with large thinning rates at room temperature. To date, there are no publicly reported cases of obtaining products with a single-pass thinning rate greater than 30% using conventional magnesium alloy sheets through room temperature force spinning. Summary of the Invention

[0005] To address the problem of cracking caused by basal surface texture during room temperature high-pressure spinning of magnesium alloys, this invention proposes a method for achieving room temperature high-pressure spinning using magnesium alloy sheets with non-basal surface texture. This method selects magnesium alloy sheets with non-basal surface texture characteristics as the blank, replacing traditional basal surface textured sheets. The non-basal surface texture is characterized by a lower polar density at the (0001) poles of the basal surface in the normal direction of the sheet than a random distribution, with texture components primarily exhibiting cylindrical, conical, or annular orientations. Compared to basal surface textured magnesium alloys, non-basal surface textured magnesium alloys exhibit higher uniform elongation and work hardening capacity at room temperature, and can withstand complex stress states during high-pressure spinning, thus possessing excellent room temperature spinning forming performance.

[0006] The technical solution of the present invention includes the following steps:

[0007] S1: Billet Preparation

[0008] Magnesium alloy plates with non-basal surface texture were selected, and their thickness was determined based on the target product wall thickness and thinning rate. The texture type was detected by X-ray diffraction (XRD) or electron backscatter diffraction (EBSD) to confirm that the polar density of the basal surface (0001) poles in the normal direction of the plate was lower than the random distribution level (random distribution value is 1).

[0009] S2: Pre-processing of billet

[0010] The sheet metal is cut into circular blanks, and its surface and edges are sanded to remove oxide scale and burrs, thus eliminating stress concentration at the start of spinning. The blank surface is then ultrasonically cleaned with acetone or anhydrous ethanol to remove oil stains, and dried with cold air.

[0011] S3: Room Temperature High-Pressure Spinning

[0012] The circular blank is clamped onto the mandrel of the spinning machine and tightened from the tail. High-intensity spinning is performed at room temperature (10℃~35℃). Spinning parameters are set as follows: spinner feed ratio 0.1~2.0 mm / r, spinner fillet radius 3~10 mm, spinner installation angle 15°~60°, mandrel speed 100~600 r / min, and single-pass thinning rate 25%~45%. The spinning machine is started, and the spinner feeds radially along the mandrel, deforming the blank until a conical or cylindrical part is formed.

[0013] S4: Multi-pass cumulative spinning

[0014] To achieve a greater overall thinning rate, multiple spinning passes can be performed on the same billet, with or without intermediate annealing between passes. The thinning rate per pass is 25% to 45%, and the total cumulative thinning rate is 50% to 85%.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] First, it achieves high-thinning room-temperature spinning of magnesium alloys. This invention uses non-basal textured magnesium alloy sheets as blanks to achieve high-strength room-temperature spinning of magnesium alloys, changing the traditional understanding that "magnesium alloys need to be hot-spun".

[0017] Secondly, the single-pass thinning rate is relatively large, resulting in high forming efficiency. The single-pass thinning rate of this invention is 25%~45%, which is higher than that of traditional room temperature spinning of magnesium alloys (usually not exceeding 20%). This can reduce the number of spinning passes, shorten the process flow, and improve production efficiency.

[0018] Third, it avoids the shortcomings of hot spinning. Room temperature spinning does not require heating, which avoids surface oxidation, grain coarsening, and dimensional errors caused by thermal expansion due to high temperatures. The resulting products have good surface quality, dense structure, and high mechanical properties.

[0019] Fourth, it reduces energy consumption and manufacturing costs. No heating devices or protective atmospheres are required, resulting in lower equipment investment, reduced energy consumption, safe and environmentally friendly operation, and overall economic efficiency. Attached Figure Description

[0020] Figure 1 The macroscopic morphology of AZ31 magnesium alloy plates with annular non-basal texture and basal texture after room temperature shear-spinning spinnability test in embodiments of the present invention is shown. Detailed Implementation

[0021] The following description, with reference to the accompanying drawings and preferred embodiments, illustrates the implementation of the present invention. Those skilled in the art can understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified and changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0022] Example 1: Room temperature shear spinning of AZ31 magnesium alloy sheet with annular non-basal texture, including:

[0023] AZ31 magnesium alloy sheet with a thickness of 1.1 mm was selected. Electron backscatter diffraction (EBSD) analysis confirmed that its texture type was a ring-shaped non-basal plane texture, with an average original grain size of 30 μm. The sheet was machined into circular blanks with a diameter of 78 mm using wire cutting. To eliminate stress concentration at the start of spinning, the surface and edges of the blank were sanded to remove oxide scale and burrs. The blank thickness after sanding was approximately 1.0 mm. The blank was ultrasonically cleaned in anhydrous ethanol for 10 minutes to remove oil and then dried with cold air for later use.

[0024] A room-temperature shear spinning test was conducted on a CNC spinning machine using a self-made ellipsoidal mandrel. A circular blank was clamped onto the mandrel, with axial clamping force applied from the tail end. Spinning was performed at room temperature (25±5℃) without auxiliary heating. The spinning process parameters were: spinneret feed ratio 0.3 mm / r, mandrel rotation speed 600 r / min, spinneret fillet radius 4 mm, and spinneret installation angle 45°. During shear spinning, the spinneret feeds radially along the mandrel, causing deformation of the blank.

[0025] The experimental results show that the AZ31 magnesium alloy sheet with a circular non-basal surface texture achieves a limiting thinning rate of 41% in a single-pass shear spinning process at room temperature, as shown in the attached figure. Figure 1As shown in (a). For comparison, AZ31 magnesium alloy sheets with similar initial thickness, diameter, and grain size but exhibiting a typical basal texture were tested under the same spinning parameters. The ultimate thinning rate of the basal textured AZ31 sheet was 13%, as shown in the attached figure. Figure 1 As shown in (b), the limiting thinning rate of the annular non-base textured sheet is increased by approximately 215% (an absolute increase of 28 percentage points) compared to the base textured sheet. This method eliminates the need for auxiliary heating, improves the efficiency of high-strength spinning of magnesium alloys, and provides a technical approach for room temperature forming of thin-walled rotating magnesium alloy parts.

Claims

1. A room-temperature high-strength spinning forming method for magnesium alloy sheets with non-basal surface texture, characterized in that... Includes the following steps: S1: Select magnesium alloy sheet with non-basal surface texture as billet; S2: The magnesium alloy sheet is processed into a circular blank, and then surface-treated and cleaned. S3: The blank is clamped on the spinning machine at room temperature of 10℃~35℃, and the spinning parameters are controlled to perform single-pass or multi-pass high-intensity spinning to obtain the spun product with the required shape and wall thickness.

2. The method according to claim 1, characterized in that... In step S1, X-ray diffraction (XRD) or electron backscatter diffraction (EBSD) is used to detect and confirm the texture type of the magnesium alloy sheet.

3. The method according to claim 1, characterized in that... The non-basal surface texture is characterized by a lower polar density at the basal surface (0001) poles than the random distribution level in the normal direction of the plate, and the texture components are mainly distributed in cylindrical, conical, or annular orientations.

4. The method according to claim 1, characterized in that... The surface treatment in step S2 involves sanding the surface and edges of the blank with sandpaper to remove oxide scale and burrs, thereby eliminating stress concentration at the start of spinning; the surface cleaning involves ultrasonic cleaning with acetone or anhydrous ethanol followed by cold air drying.

5. The method according to claim 1, characterized in that... The thinning rate of the single-pass high-intensity spinning described in step S3 is 25%~45%.

6. The method according to claim 1, characterized in that... The multi-pass high-strength spinning is a multi-pass cumulative spinning process, with a thinning rate of 25% to 45% per pass and a total cumulative thinning rate of 50% to 85%. Intermediate annealing may or may not be performed between each pass.

7. The method according to claim 1, characterized in that... The spinning parameters are: spinneret feed ratio 0.1~2.0 mm / r, spinneret fillet radius 3~10 mm, spinneret mounting angle 15°~60°, and mandrel rotation speed 100~600 r / min.

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