Preparation method of high-strength and high-plasticity titanium alloy

Abstract

The invention discloses a preparation method of a high-strength and high-plasticity titanium alloy, which comprises the following steps: weighing spherical TC4 powder and irregular TiH2 powder according to the ratio of (11: 1)-(7: 1); tC4 powder, TiH2 powder and a binder are mixed together; putting the mixed feed into a granulator for extrusion granulation to obtain a granular injection feed; putting the granular injection feed into an injection stock bin, and injecting into a mold to obtain a TC4 green body; the TC4 green body is subjected to degreasing treatment; and the TC4 degreased blank is sintered and cooled along with a furnace, and a TC4 sintered part is obtained. According to the method, a certain proportion of irregular TiH2 powder is doped in spherical TC4 powder, the titanium alloy is manufactured through the metal injection molding technology, and by means of the fact that the TiH2 powder is prone to generating the phase change process from TiH2 to alpha + H2 under the high-temperature condition, the Ti-Ti bond of H in the titanium alloy is weakened, the atomic diffusion rate is increased, TC4 crystal grains are broken, full-dense sintering is promoted, and the titanium alloy is obtained. And therefore, the density of the titanium alloy material is improved, and a titanium alloy product obtains high strength and high plasticity and toughness.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy manufacturing, and particularly relates to a preparation method of a high-strength and high-plasticity titanium alloy. Background Art

[0002] As a high-quality light metal structural material and functional material, titanium alloy has the characteristics of low density, high specific strength, good biocompatibility, oxidation resistance, corrosion resistance, wide use temperature range, non-magnetic, non-toxic, etc., and has always occupied an important position in the manufacturing fields of military products such as aviation, aerospace, navigation, and ordnance. The traditional preparation methods of titanium alloy are casting, ingot hot working, and powder metallurgy. However, the surface quality of cast titanium alloy is poor and the grains are uneven, the dimensional accuracy of cast and hot-worked titanium alloy is poor, and the density of powder metallurgy titanium alloy is low and the surface is rough. At the same time, due to the high activity of titanium alloy, it is easy to react with interstitial elements such as C, O, N, etc. during the preparation process to form brittle phases such as TiC, TiO2, TiN, etc., resulting in the reduction of the plastic toughness of titanium alloy and the inability to achieve the balance of high strength and high plastic toughness at the same time. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: to provide a preparation method of a high-strength and high-plasticity titanium alloy.

[0004] To solve the above technical problem, the technical solution adopted by the present invention is: a preparation method of a high-strength and high-plasticity titanium alloy, comprising the following steps: Step 1, weigh spherical TC4 powder and irregular TiH2 powder, and the ratio of TC4 to TiH2 powder is 11:1 to 7:1; Step 2, put the TC4 powder, TiH2 powder and binder into an atmosphere internal mixer according to a certain loading amount and mix them together; Step 3, put the mixed feed into a granulator to extrude and granulate to obtain granular injection feed; Step 4, put the granular injection feed into an injection material bin and inject it into a mold to obtain a TC4 green body; Step 5, perform debinding treatment on the TC4 green body to obtain a TC4 debound blank; Step 6, sinter the TC4 debound blank, and then perform furnace cooling to obtain a TC4 sintered part.

[0005] The beneficial effects of the present invention are as follows: In the preparation method of the high-strength and high-plasticity titanium alloy provided by the present invention, a certain proportion of irregular TiH2 powder is doped into spherical TC4 powder, and the titanium alloy is manufactured by metal injection molding technology. By utilizing the phase change process of TiH2→α+H2 that easily occurs in TiH2 powder under high-temperature conditions, H weakens the Ti-Ti bond in the titanium alloy, increases the atomic diffusion rate, breaks the TC4 grains, reduces the grain size, improves the microstructure, promotes full-density sintering, and further increases the density of the titanium alloy material, enabling the titanium alloy product to obtain high strength and high plastic toughness. Brief Description of the Drawings

[0006] Figure 1 It is the metallographic diagram of the TC4 tensile bar in the first embodiment of the present invention; Figure 2 It is the metallographic diagram of the TC4 tensile bar in the second embodiment of the present invention; Figure 3 It is the metallographic diagram of the TC4 tensile bar in Comparative Example 1; Figure 4 It is the metallographic diagram of the TC4 tensile bar in Comparative Example 2. Detailed Embodiment

[0007] To illustrate the technical content, achieved objectives and effects of the present invention in detail, the following is described in conjunction with the embodiments and accompanied by the drawings.

[0008] A preparation method of a high-strength and high-plasticity titanium alloy includes the following steps: Step 1, weigh spherical TC4 powder and irregular TiH2 powder, and the ratio of TC4 to TiH2 powder is 11:1 to 7:1; Step 2, put the TC4 powder, TiH2 powder and binder into an atmospheric kneader according to a certain loading amount and knead them together; Step 3, put the kneaded feed into a granulator to extrude and granulate, obtaining granular injection feed; Step 4, put the granular injection feed into an injection material bin and inject it into a mold to obtain a TC4 green body; Step 5, perform degreasing treatment on the TC4 green body to obtain a TC4 degreased blank; Step 6, sinter the TC4 degreased blank, and then perform furnace cooling to obtain a TC4 sintered part.

[0009] As can be seen from the above description, the beneficial effects of the present invention are as follows: In the spherical TC4 powder, a certain proportion of irregular TiH2 powder is doped, and the titanium alloy is manufactured by metal injection molding technology. Utilizing the phase change process of TiH2→α+H2 that easily occurs in TiH2 powder under high-temperature conditions, H weakens the Ti-Ti bond in the titanium alloy, increases the atomic diffusion rate, breaks the TC4 grains, reduces the grain size, improves the microstructure, promotes full-density sintering, and further enhances the density of the titanium alloy material, enabling the titanium alloy product to obtain high strength and high plastic toughness.

[0010] Further, the mass of the TC4 powder is 8 kg - 12 kg, and the mass of the TiH2 powder is 0.8 kg - 1.5 kg.

[0011] Further, in the weight percentages of the components of the TC4 powder, Al is 6 wt% - 6.5 wt%, V is 3.75 wt% - 4.25 wt%, Fe ≤ 0.3 wt%, C ≤ 0.08 wt%, O ≤ 0.18 wt%, and Ti is the balance.

[0012] Further, the particle size of the TC4 powder is less than or equal to 25 μm, and the particle size of the TiH2 powder is less than or equal to 25 μm.

[0013] Further, in step two, the kneading time is 2 h - 3 h, and the kneading temperature is 160°C - 200°C.

[0014] Further, in step three, the granulation temperature is 175°C - 185°C, the extrusion speed is 10 Hz - 20 Hz, the feeding speed is 5 Hz - 10 Hz, the cutting speed is 5 Hz - 10 Hz, the particle diameter is 3 mm, and the particle diameter length is 2 mm - 4 mm.

[0015] Further, in step four, the injection mold is a tensile bar mold, the injection mold temperature is 80°C - 120°C, the feeding heating temperature is 160°C - 200°C, the injection pressure is 100 MPa - 140 MPa, and the holding pressure time is 5 s - 15 s.

[0016] Further, in step five, the debinding method adopts oxalic acid catalytic debinding.

[0017] Further, in step five, the debinding temperature is 110°C - 140°C, and the debinding time is 8 h - 14 h.

[0018] Further, in step six, the heating rate during sintering is 5°C / min - 15°C / min, the sintering temperature is 1030°C - 1080°C, and the holding time is 5 h - 10 h.

[0019] Example one of the present invention is as follows: A preparation method of a high-strength and high-plasticity titanium alloy, comprising the following steps: Step 1, raw material preparation: Weigh a certain mass of spherical TC4 powder prepared by commercially available gas atomization method and irregular TiH2 powder. The ratio of TC4 to TiH2 powder is 9:1, where the mass of TC4 powder is 9 kg and the mass of TiH2 powder is 1 kg. In the weight percentage of each component of the TC4 powder, Al is 6.27 wt%, V is 3.9 wt%, Fe ≤ 0.1 wt%, C ≤ 0.021 wt%, O ≤ 0.178 wt%, and Ti is the balance. The particle size of the TC4 powder is less than or equal to 25 μm, and the particle size of the TiH2 powder is less than or equal to 25 μm.

[0020] Step 2, kneading: Put the TC4 powder, TiH2 powder and the corresponding plastic-based binder into an atmosphere internal mixer according to a certain loading amount for kneading. The kneading time is 3 h and the temperature is 180 °C.

[0021] Step 3, granulation: Put the feed obtained after kneading into a granulator for extrusion granulation. The granulation temperature is 180 °C, the extrusion speed is 15 Hz, the feeding speed is 8 Hz, the cutting speed is 8 Hz, the particle diameter is 3 mm, and the particle diameter length is 3 mm to obtain granular injection feed.

[0022] Step 4, injection molding: Put the granular injection feed obtained in Step 3 into the injection material bin and inject it into the mold. The injection mold is a tensile bar mold. The temperature of the injection mold is 110 °C, the feeding heating temperature is 180 °C, the injection pressure is 120 MPa, and the holding pressure time is 10 s to obtain a TC4 green body.

[0023] Step 5, debinding: Perform debinding treatment on the TC4 green body obtained in Step 4. The debinding method uses oxalic acid catalytic debinding. The debinding temperature is 120 °C and the debinding time is 12 h to obtain a TC4 debound blank.

[0024] Step 6, sintering: Sinter the TC4 debound blank. The heating rate is 10 °C / min, the sintering temperature is 1060 °C, and the holding time is 7 h. Then, perform furnace cooling to obtain a TC4 sintered part.

[0025] Perform mechanical property testing on the sintered TC4 tensile bar. The results are as follows: tensile strength 1100 MPa, yield strength 1065 MPa, elongation 17%, hardness 360 HV, density 4.4 g / cm3, average grain size 20 μm, C content 0.113 wt%, O content 0.23 wt%. Figure 1 This is the metallographic diagram of the TC4 tensile bar in Example 1.

[0026] Example 2 of the present invention is as follows: A method for preparing a high-strength and high-plasticity titanium alloy, comprising the following steps: Step 1, raw material preparation: Weigh a certain mass of commercially available spherical TC4 powder and irregular TiH2 powder. The ratio of TC4 to TiH2 powder is 10:1, where the mass of TC4 powder is 10 kg and the mass of TiH2 powder is 1 kg. In the weight percentages of the components of the TC4 powder, Al is 6.27 wt%, V is 3.9 wt%, Fe ≤ 0.1 wt%, C ≤ 0.021 wt%, O ≤ 0.178 wt%, and Ti is the balance. The particle size of the TC4 powder is less than or equal to 25 μm, and the particle size of the TiH2 powder is less than or equal to 25 μm.

[0027] Step 2, kneading: Put the TC4 powder, TiH2 powder, and the corresponding plastic-based binder into an atmospheric kneader for kneading according to a certain loading amount. The kneading time is 3 h and the temperature is 180 °C.

[0028] Step 3, granulation: Put the feed obtained after kneading into a granulator for extrusion granulation. The granulation temperature is 180 °C, the extrusion speed is 15 Hz, the feeding speed is 8 Hz, the cutting speed is 8 Hz, the particle diameter is 3 mm, and the particle diameter length is 3 mm to obtain granular injection feed.

[0029] Step 4, injection molding: Put the granular injection feed obtained in Step 3 into the injection material bin and inject it into the mold. The injection mold is a tensile bar mold. The injection mold temperature is 110 °C, the feed heating temperature is 180 °C, the injection pressure is 120 MPa, and the holding pressure time is 10 s to obtain a TC4 green body.

[0030] Step 5, debinding: Perform debinding treatment on the TC4 green body obtained in Step 4. The debinding method uses oxalic acid catalytic debinding. The debinding temperature is 120 °C and the debinding time is 12 h to obtain a TC4 debound blank.

[0031] Step 6, sintering: Sinter the TC4 debound blank. The heating rate is 10 °C / min, the sintering temperature is 1050 °C, and the holding time is 8 h. Then, perform furnace cooling to obtain a TC4 sintered part.

[0032] Perform mechanical property testing on the sintered TC4 tensile bar. The results are as follows: tensile strength 1080 MPa, yield strength 1032 MPa, elongation 18%, hardness 353 HV, density 4.39 g / cm3, average grain size 21 μm, C content 0.12 wt%, O content 0.25 wt%. Figure 2 This is the metallographic diagram of the TC4 tensile bar in Example 2.

[0033] Comparative Example 1: The titanium alloy preparation method includes the following steps: Step 1, raw material preparation: Weigh a certain mass of spherical TC4 powder prepared by commercially available gas atomization method and irregular TiH2 powder. The ratio of TC4 to TiH2 powder is 2:1, where the mass of TC4 powder is 10 kg and the mass of TiH2 powder is 5 kg. In the weight percentages of the components of the TC4 powder, Al is 6.27 wt%, V is 3.9 wt%, Fe ≤ 0.1 wt%, C ≤ 0.021 wt%, O ≤ 0.178 wt%, and Ti is the balance. The particle size of the TC4 powder is less than or equal to 25 μm, and the particle size of the TiH2 powder is less than or equal to 25 μm.

[0034] Step 2, kneading: Put the TC4 powder, TiH2 powder and the corresponding plastic-based binder into an atmosphere kneader according to a certain loading amount for kneading. The kneading time is 3 h and the temperature is 180 °C.

[0035] Step 3, granulation: Put the feed obtained after kneading into a granulator for extrusion granulation. The granulation temperature is 180 °C, the extrusion speed is 15 Hz, the feeding speed is 8 Hz, the cutting speed is 8 Hz, the particle size is 3 mm, and the particle size length is 3 mm to obtain granular injection feedstock.

[0036] Step 4, injection molding: Put the granular injection feedstock obtained in Step 3 into the injection material bin and inject it into the mold. The injection mold is a tensile bar mold. The injection mold temperature is 110 °C, the feedstock heating temperature is 180 °C, the injection pressure is 120 MPa, and the holding pressure time is 10 s to obtain a TC4 green body.

[0037] Step 5, debinding: Carry out debinding treatment on the TC4 green body obtained in Step 4. The debinding method uses oxalic acid catalytic debinding. The debinding temperature is 120 °C and the debinding time is 12 h to obtain a TC4 debound blank.

[0038] Step 6, sintering: Sinter the TC4 debound blank. The heating rate is 10 °C / min, the sintering temperature is 1050 °C, and the holding time is 8 h. Then, it is cooled in the furnace to obtain a TC4 sintered part.

[0039] Perform mechanical property tests on the sintered TC4 tensile bar. The results are as follows: tensile strength 1148 MPa, yield strength 1102 MPa, elongation 5%, hardness 406 HV, density 4.35 g / cm3, average grain size 24 μm, C content 0.34 wt%, O content 0.42 wt%. Figure 3 It is the metallographic diagram of the TC4 tensile bar of Comparative Example 1.

[0040] Comparative Example 2: The titanium alloy preparation method includes the following steps: Step 1, Raw material preparation: Weigh a certain mass of spherical TC4 powder prepared by commercially available gas atomization method and irregular TiH2 powder. The ratio of TC4 to TiH2 powder is 2:1, where the mass of TC4 powder is 10 kg and the mass of TiH2 powder is 5 kg. In the weight percentages of the components of the TC4 powder, Al is 6.27 wt%, V is 3.9 wt%, Fe ≤ 0.1 wt%, C ≤ 0.021 wt%, O ≤ 0.178 wt%, and Ti is the balance. The particle size of the TC4 powder is less than or equal to 25 μm, and the particle size of the TiH2 powder is less than or equal to 25 μm.

[0041] Step 2, Kneading: Put the TC4 powder, TiH2 powder, and the corresponding plastic-based binder into an atmosphere kneader according to a certain loading amount for kneading. The kneading time is 3 h and the temperature is 180 °C.

[0042] Step 3, Granulation: Put the feed obtained after kneading into a granulator for extrusion granulation. The granulation temperature is 180 °C, the extrusion speed is 15 Hz, the feeding speed is 8 Hz, the cutting speed is 8 Hz, the particle size is 3 mm, and the particle size length is 3 mm to obtain granular injection feedstock.

[0043] Step 4, Injection molding: Put the granular injection feedstock obtained in Step 3 into the injection material bin and inject it into the mold. The injection mold is a tensile bar mold. The injection mold temperature is 110 °C, the feedstock heating temperature is 180 °C, the injection pressure is 120 MPa, and the holding pressure time is 10 s to obtain a green TC4 body.

[0044] Step 5, Debinding: Perform debinding treatment on the green TC4 body obtained in Step 4. The debinding method uses oxalic acid catalytic debinding. The debinding temperature is 120 °C and the debinding time is 12 h to obtain a debound TC4 body.

[0045] Step 6, Sintering: Sinter the debound TC4 body. The heating rate is 10 °C / min, the sintering temperature is 1100 °C, and the holding time is 4 h. Then, perform furnace cooling to obtain a sintered TC4 part.

[0046] Perform mechanical property testing on the sintered TC4 tensile bar. The results are as follows: Tensile strength is 1137 MPa, yield strength is 1082 MPa, elongation is 4%, hardness is 412 HV, density is 4.34 g / cm3, average grain size is 28 μm, C content is 0.24 wt%, and O content is 0.36 wt%. Figure 4 The metallographic diagram of the TC4 tensile bar for Comparative Example 2.

[0047] In summary, the preparation method of the high-strength and high-plasticity titanium alloy provided by the present invention doped a certain proportion of irregular TiH2 powder in spherical TC4 powder and manufactured the titanium alloy by metal injection molding technology. By utilizing the phase change process of TiH2→α+H2 that easily occurs in TiH2 powder under high-temperature conditions, H weakens the Ti-Ti bond in the titanium alloy, increases the atomic diffusion rate, breaks the TC4 grains, reduces the grain size, improves the microstructure, promotes full-density sintering, and further increases the density of the titanium alloy material, enabling the titanium alloy product to obtain high strength and high plastic toughness.

[0048] The above are only the embodiments of the present invention, and thus do not limit the patent scope of the present invention. Any equivalent transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in the relevant technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A method for preparing a high-strength and high-plasticity titanium alloy, characterized in that, It includes the following steps: Step 1: Weigh spherical TC4 powder and irregular TiH2 powder, and the ratio of TC4 to TiH2 powder is 11:1 to 7:1; Step 2: Put the TC4 powder, TiH2 powder and binder into an atmosphere internal mixer according to a certain loading amount and mix them together; Step 3: Put the mixed feed into a granulator to extrude and granulate to obtain granular injection feed; Step 4: Put the granular injection feed into an injection material bin and inject it into a mold to obtain a green TC4 blank; Step 5: Carry out debinding treatment on the green TC4 blank to obtain a debound TC4 blank; Step 6: Sinter the debound TC4 blank, and then carry out furnace cooling to obtain a sintered TC4 part.

2. The preparation method of a high-strength and high-plasticity titanium alloy according to claim 1, characterized in that: The mass of the TC4 powder is 8 kg - 12 kg, and the mass of the TiH2 powder is 0.8 kg - 1.5 kg.

3. The preparation method of a high-strength and high-plasticity titanium alloy according to claim 1, characterized in that: In the weight percentages of the components of the TC4 powder, Al is 6 wt% - 6.5 wt%, V is 3.75 wt% - 4.25 wt%, Fe ≤ 0.3 wt%, C ≤ 0.08 wt%, O ≤ 0.18 wt%, and Ti is the balance.

4. The preparation method of a high-strength and high-plasticity titanium alloy according to claim 1, wherein: The particle size of the TC4 powder is less than or equal to 25 μm, and the particle size of the TiH2 powder is less than or equal to 25 μm.

5. The preparation method of a high-strength and high-plasticity titanium alloy according to claim 1, characterized in that: In Step 2, the mixing time is 2 h - 3 h, and the mixing temperature is 160°C - 200°C.

6. The preparation method of a high-strength and high-plasticity titanium alloy according to claim 1, characterized in that: In Step 3, the granulation temperature is 175°C - 185°C, the extrusion speed is 10 Hz - 20 Hz, the feeding speed is 5 Hz - 10 Hz, the cutting speed is 5 Hz - 10 Hz, the particle size is 3 mm, and the particle size length is 2 mm - 4 mm.

7. The preparation method of a high-strength and high-plasticity titanium alloy according to claim 1, characterized in that: In Step 4, the injection mold is a tensile bar mold, the injection mold temperature is 80°C - 120°C, the feed heating temperature is 160°C - 200°C, the injection pressure is 100 MPa - 140 MPa, and the holding pressure time is 5 s - 15 s.

8. The preparation method of a high-strength and high-plasticity titanium alloy according to claim 1, characterized in that: In Step 5, the debinding method uses oxalic acid catalytic debinding.

9. The preparation method of a high-strength and high-plasticity titanium alloy according to claim 8, characterized in that: In Step 5, the debinding temperature is 110°C - 140°C, and the debinding time is 8 h - 14 h.

10. The preparation method of a high-strength and high-plasticity titanium alloy according to claim 1, wherein: In Step 6, the heating rate during sintering is 5°C / min - 15°C / min, the sintering temperature is 1030°C - 1080°C, and the holding time is 5 h - 10 h.

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