A method for forming a TiZrNb high entropy alloy conical part

Abstract

The present invention relates to a method for forming a TiZrNb series high entropy alloy conical part, and belongs to the technical field of alloys. A two-step forming method of stamping preforming and spinning is adopted, wherein the TiZrNb series high entropy alloy blank is first heated, stamped and preformed, then heated and kept warm at a suitable heating current and heating time, and then two passes of spinning are performed at a suitable mandrel speed, feed ratio, and spinning wheel diameter, and finally heat-treated to obtain a conical part product. The conical part obtained by optimizing the process conditions has uniform wall thickness, high surface accuracy, and improved strength and plasticity.

Description

Technical Field

[0001] The invention relates to a TiZrNb series high entropy alloy conical piece forming method, belonging to the technical field of alloys. Background Art

[0002] TiZrNb-based high-entropy alloys composed of highly active and refractory elements are usually prepared by cold crucible smelting technology. Since the superheat of the cold crucible smelted alloy melt is low, its fluidity is poor. The conical products of this alloy are difficult to form by casting. The traditional method of turning the blank has the disadvantages of low processing efficiency and low material utilization.

[0003] Spinning is to fix a flat plate or hollow blank on the die of the spinning machine. When the blank rotates with the spindle of the machine tool, the blank undergoes local plastic deformation under the pressure of the spinning wheel. Spinning can complete the processing of various complex rotating parts and is a special method of sheet metal forming.

[0004] Most of the existing spinning processes are suitable for materials such as copper, aluminum alloy, and magnesium alloy, and have large restrictions on product thickness, and are suitable for processing products with a wall thickness of less than 2mm. For high-strength, low-plasticity, and easily oxidized alloys such as TiZrNb, the existing spinning process often causes problems such as billet breakage, rough and wrinkled product surfaces, and severe oxidation. For TiZrNb-based conical products with a cone angle of less than 90°, a wall thickness of more than 3mm, and a top diameter of less than 20mm, it is difficult to directly form them through spinning due to the large wall thickness and small cone angle. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a method for forming a TiZrNb-based high entropy alloy conical part. The method first performs stamping preforming on the blank, and then performs spinning. By optimizing the process conditions, the conical part has uniform wall thickness, high surface accuracy, and improved strength and plasticity. It is particularly suitable for products with a cone angle of less than 90°, a wall thickness of more than 3mm, and a top diameter of less than or equal to 20mm, overcoming the disadvantage that the spinning process can only process thinner products.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] A method for forming a TiZrNb-based high-entropy alloy conical part, the method steps comprising:

[0008] (1) In an inert gas atmosphere, heat a TiZrNb high entropy alloy slab with a thickness of more than 5 mm and a diameter of more than 40 mm to 600-900°C and place it on a stamping die. Control the pressing speed of the machine tool to 2-6 mm / s, and stamp the slab into a blank with a fracture elongation greater than or equal to 50% at the heating temperature (to ensure the success rate and processing accuracy of subsequent spinning), a taper angle of 110°-120°, a wall thickness of 75%-85% of the slab thickness, and a top diameter of the required size of the tapered product. The top diameter of the tapered product is less than or equal to 20 mm;

[0009] (2) The blank is clamped on the spinning machine and heated by the induction coil. The heating current is 100~150A, the heating temperature is T=600~900℃, and the heating time is (T / 20+10h0)s;

[0010] (3) Maintaining the temperature at (T ± 30) °C, two-pass spinning is performed, the spinning wheel feed rate is 60-450 mm / min, the spinning wheel feed ratio is (1.2-1.8) / h0, h0 is the thickness of the conical part product, and the spinning wheel feed ratio unit is mm / r; the mandrel speed is 50-420 r / min, the spinning wheel radius is 20-50 mm, and the spinning attack angle is the half cone angle of the core mold; the first pass is spun to a cone angle of 95°-100°, and the wall thickness is 67%-75% of the slab thickness; the second pass is spun to a cone angle of less than or equal to 90° and a wall thickness of greater than or equal to 3 mm; after the spinning is completed, cooling is performed to obtain a spun conical part;

[0011] (4) The spun conical part is heated to 800-950°C and kept at this temperature for 1-2 hours. After the holding period, the conical part is cooled to obtain a TiZrNb high entropy alloy conical part.

[0012] Preferably, in step (1), the chemical formula of the TiZrNb-based high entropy alloy is Ti a Zr b Nb c M x , M is one or more of Hf, W, Ni, Al, Cr, Mo, Fe, Ta and V, 10≤a≤50, 20≤b≤80, 0≤c≤50, 0≤x≤40, a+b+c+x=100.

[0013] Preferably, in step (1), the thickness of the TiZrNb-based high entropy alloy slab is 5-12 mm and the diameter is 40-300 mm.

[0014] Preferably, in step (1), an anti-oxidation coating is applied to the surface of the TiZrNb-based high entropy alloy slab before heating.

[0015] Preferably, in step (1), the heating temperature is 800-900°C.

[0016] Preferably, in step (2), before heating, an anti-oxidation coating and lubricating grease are applied to the inner and outer surfaces of the blank respectively.

[0017] Preferably, in step (2), the heating temperature is 800-900°C.

[0018] Preferably, in step (3), the temperature is maintained at 800-900°C, the roller feed ratio is (1.2-1.8) / h0, the spindle speed is 150-250 r / min, and the roller radius is 30-40 mm.

[0019] Preferably, in step (3), the cone angle of the spin-back cone is 50° to 90°, the wall thickness is 3 to 6 mm, the large end diameter is 50 to 500 mm, and the top end diameter is 5 to 20 mm.

[0020] A TiZrNb series high entropy alloy cone is prepared by the above method.

[0021] Beneficial Effects

[0022] The present invention provides a TiZrNb series high entropy alloy conical part forming method, which adopts a two-step forming method of stamping preforming and spinning. First, the TiZrNb series high entropy alloy blank is heated, stamped and preformed, and then heated and kept warm at a suitable heating current and heating time, and then two passes of spinning are performed at a suitable mandrel speed, feed ratio, and spinning wheel diameter, and finally heat-treated to obtain a conical part product. It can avoid the shortcomings of repeated heating of the blank that easily causes cracking and oxidation, and can improve efficiency and processing accuracy through the spinning process. The pressing rate of the machine tool during stamping preforming is 2~6mm / s to prevent the blank from breaking due to excessive speed. The heating current before spinning is controlled at 100~150A, and the heating time is set to (T / 20+10h0)s. If the heating time is too long and the temperature is too high, the alloy will be severely oxidized, resulting in changes in the material phase structure and a high degree of oxidation, which will lead to problems such as material cracking, excessive loss, and rough surface during spinning. The feed ratio of the rotary wheel is controlled at (1.2~1.8) / h0. A larger feed ratio of the rotary wheel is conducive to the mold attachment of the workpiece, but it is easy to wrinkle; a smaller feed ratio of the rotary wheel may cause local over-rolling or even cracking. The appropriate feed ratio can make the surface roughness of the workpiece good and meet the dimensional accuracy requirements. The spindle speed is 50~420r / min, which matches the feed ratio and the rotary wheel feed rate. When the rotary wheel radius is small, the contact area between the rotary wheel and the blank is small, which is easy to produce a cutting effect, resulting in local thinning of the wall thickness. When the rotary wheel radius is too large, the spun part is prone to bulging in the same direction, resulting in an increase in the wall thickness difference. After heating the spun conical part to 800~950℃ and keeping it warm for 1~2 hours, and cooling it after the end of the insulation, the grains that are elongated and coarsened inside the material due to spinning can be transformed into uniform equiaxed grains, and the texture is eliminated, making its mechanical properties more stable.

[0023] The method of the present invention can improve the forming accuracy, processing efficiency, material utilization rate, etc. of TiZrNb series high entropy alloy conical parts, which is beneficial to expanding the production scale and reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 (a) is the product of Example 1; (b) is the quasi-static tensile curve.

[0025] Figure 2 (a) is the product of Example 2; (b) is the quasi-static tensile curve.

[0026] Figure 3 This is the product blank of Comparative Example 1.

[0027] Figure 4 This is the product of Comparative Example 2. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below in conjunction with specific embodiments.

[0029] Example 1: TiZrNbAl 11 Alloy spinning cone parts

[0030] The product of this spinning is a conical part with a cone angle of 60°, a top diameter of 12mm and a wall thickness of 3mm.

[0031] The blank with a diameter of 130mm and a thickness of 6mm is evenly coated with anti-oxidation coating, heated to 800℃, the machine tool pressing rate is set to 3mm / s, and the blank is punched into a blank with a cone angle of 110° and a top diameter of 12mm. The wall thickness of the blank is measured to be 5mm, the wall thickness deviation is less than 0.3mm, and the quasi-static elongation at 800℃ is 71%, which meets the requirements of subsequent spinning processing.

[0032] The stamped blank is clamped onto the spinning machine, and anti-oxidation coating and grease are applied on both sides of the blank in turn. The induction coil current is adjusted to 150A. After heating for 100s to reach the spinning temperature of 800℃, the mandrel speed is set to 150r / min, the spinning wheel feed ratio is selected to be 0.4mm / r, the spinning wheel radius is 30mm, and the feed program is started. After the first spinning pass, the cone angle is 90°, and the wall thickness is 71% of the blank thickness. The product is obtained after the second spinning pass. The deviation between the wall thickness and the theoretical value is measured to be 0.12mm.

[0033] In an inert gas atmosphere, the spun conical piece was heated to 800° C. and kept at that temperature for 1 hour. After the heat preservation, it was cooled to obtain the final product.

[0034] Figure 1(a) is the product obtained by spinning using this process, and (b) is the quasi-static tensile curve sampled along the generatrix direction of the product. It can be seen that the strength of the material after spinning is 1000MPa and the elongation at break is 8%, which are both improved compared to the strength of 900MPa and the elongation at break of 5% before spinning.

[0035] Example 2: NbZrTiTa 12 Alloy spinning cone parts

[0036] The product spun this time is a conical part with a cone angle of 75°, a top diameter of 15mm and a wall thickness of 5mm.

[0037] The blank with a diameter of 160mm and a thickness of 8mm is evenly coated with anti-oxidation coating, heated to 900℃, the machine tool pressing rate is set to 3mm / s, and the blank is punched into a blank with a cone angle of 120° and a top diameter of 15mm. The wall thickness of the blank is measured to be 6.9mm, the wall thickness deviation is less than 0.45mm, and the quasi-static elongation at 900℃ is 63%, which meets the requirements of subsequent spinning processing.

[0038] The stamped blank is clamped to the spinning machine, and anti-oxidation coating and grease are evenly applied. The induction coil current is adjusted to 150A, and it is heated for 125s to reach the spinning temperature of 900℃. The mandrel speed is set to 200r / min, the spinning wheel feed ratio is selected to be 0.5mm / r, the spinning wheel radius is 25mm, and the feed program is started. After the first spinning pass, the cone angle is 100°, and the wall thickness is 77% of the blank thickness. After the second spinning pass, the product is obtained, and the deviation of the wall thickness from the theoretical value is about 0.15mm.

[0039] In an inert gas atmosphere, the spun conical piece is heated to 850° C. and then kept at this temperature for 1.5 hours. After the end of the heat preservation, the piece is cooled to obtain a final product.

[0040] Figure 2 (a) is the product obtained by spinning using this process, and (b) is the quasi-static tensile curve sampled along the generatrix direction of the product. It can be seen that the strength of the material after spinning is 800MPa and the elongation at break is 18%, which are both improved compared to the strength of 700MPa and the elongation at break of 15% before spinning.

[0041] Comparative Example 1: NbZrTiAl 11 Alloy spinning cone parts

[0042] The difference from Example 1 is that the feed ratio of the rotary wheel is 2 mm / r, and the other processing conditions remain unchanged. Figure 3 The product blank obtained after the first spinning pass using the process parameters has a relatively rough surface. This is because the spinning wheel feeds too fast and the material is not fully deformed, resulting in local wrinkling. The measurement shows that the wall thickness deviation of the blank is greater than 0.6mm, which cannot meet the requirements of subsequent processing.

[0043] Comparative Example 2: NbZrTiTa 12 Alloy spinning cone parts

[0044] The difference from Example 2 is that stamping preforming is not used, and the processing is directly carried out through the spinning process, and the other processing conditions remain unchanged. Figure 4 For the products obtained using this spinning process, it can be seen that the blank is completely broken. This is because the fracture elongation of the material cannot meet the requirements of direct spinning. During spinning, the stress of the material is concentrated at the corners, causing it to break.

[0045] In summary, the invention includes but is not limited to the above embodiments. Any equivalent substitution or partial improvement made under the spirit and principle of the invention shall be deemed to be within the protection scope of the invention.

Claims

1. A method for forming a TiZrNb high entropy alloy conical part, characterized in that: The method steps include: (1) In an inert gas atmosphere, a TiZrNb high entropy alloy slab with a thickness of more than 5 mm and a diameter of more than 40 mm is heated to 600-900°C and then placed on a stamping die. The pressing speed of the machine tool is controlled to be 2-6 mm / s, and the slab is stamped and preformed into a blank with a fracture elongation greater than or equal to 50% at the heating temperature, a cone angle of 110°-120°, a wall thickness of 75%-85% of the slab thickness, and a top diameter of the required size of the tapered product. The top diameter of the tapered product is less than or equal to 20 mm; (2) The blank is clamped on the spinning machine and heated by the induction coil. The heating current is 100~150A, the heating temperature is T=600~900℃, and the heating time is (T / 20+10h0)s; (3) Maintaining the temperature at (T ± 30) °C, two-pass spinning is performed, the spinning wheel feed rate is 60-450 mm / min, the spinning wheel feed ratio is (1.2-1.8) / h0, h0 is the thickness of the conical part product, and the spinning wheel feed ratio unit is mm / r; the mandrel speed is 50-420 r / min, the spinning wheel radius is 20-50 mm, and the spinning attack angle is the half cone angle of the core mold; the first pass is spun to a cone angle of 95°-100°, and the wall thickness is 67%-75% of the slab thickness; the second pass is spun to a cone angle of less than or equal to 90° and a wall thickness of greater than or equal to 3 mm; after the spinning is completed, cooling is performed to obtain a spun conical part; (4) The spun conical part is heated to 800-950°C and kept at this temperature for 1-2 hours. After the holding period, the conical part is cooled to obtain a TiZrNb high entropy alloy conical part.

2. A method for forming a TiZrNb high entropy alloy conical part according to claim 1, characterized in that: In step (1), the chemical formula of the TiZrNb high entropy alloy is Ti a Zr b Nb c M x , M is one or more of Hf, W, Ni, Al, Cr, Mo, Fe, Ta and V, 10≤a≤50, 20≤b≤80, 0≤c≤50, 0≤x≤40, a+b+c+x=100.

3. A method for forming a TiZrNb high entropy alloy conical part according to claim 1, characterized in that: In step (1), the thickness of the TiZrNb high entropy alloy slab is 5-12 mm and the diameter is 40-300 mm.

4. A method for forming a TiZrNb high entropy alloy conical part according to claim 1, characterized in that: In step (1), an anti-oxidation coating is applied to the surface of the TiZrNb high entropy alloy slab before heating.

5. A method for forming a TiZrNb high entropy alloy conical part according to claim 1, characterized in that: In step (1), the heating temperature is 800-900°C.

6. A method for forming a TiZrNb high entropy alloy conical part according to claim 1, characterized in that: In step (2), before heating, anti-oxidation coating and lubricating grease are applied to the inner and outer surfaces of the blank respectively.

7. A method for forming a TiZrNb high entropy alloy conical part according to claim 1, characterized in that: In step (2), the heating temperature is 800-900°C.

8. A method for forming a TiZrNb high entropy alloy conical part according to claim 1, characterized in that: In step (3), the temperature is maintained at 800-900°C, the feed ratio of the rotary wheel is (1.2-1.8) / h0, the spindle speed is 150-250 r / min, and the rotary wheel radius is 30-40 mm.

9. A method for forming a TiZrNb high entropy alloy conical part according to claim 1, characterized in that: In step (3), the cone angle of the spin-back cone is 50°~90°, the wall thickness is 3~6 mm, the large end diameter is 50~500 mm, and the top end diameter is 5~20 mm.

10. A TiZrNb high entropy alloy cone, characterized in that: It is prepared by the method according to any one of claims 1 to 9.

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