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CN-122007203-A - High-oxygen pure titanium large-specification fine-grain pipe and preparation method thereof

CN122007203ACN 122007203 ACN122007203 ACN 122007203ACN-122007203-A

Abstract

The invention discloses a high-oxygen pure titanium large-size fine-grain pipe and a preparation method thereof, comprising the steps of ingot smelting, namely selecting sponge titanium, pressing the sponge titanium into an electrode, carrying out post treatment after smelting the electrode to obtain a high-oxygen pure titanium ingot, carrying out high-temperature cogging forging, namely heating the high-oxygen pure titanium ingot to a set temperature above a beta phase transition point and carrying out high Wen Huanxiang cogging forging after heat preservation, carrying out low-temperature forging, namely heating the cogged blank below the beta phase transition point and carrying out low-temperature reversing upsetting and drawing steps after heat preservation, carrying out machining to obtain a smooth-surface bar blank, carrying out middle Wen Xiega perforation, namely processing a through hole in the center of the smooth-surface bar blank, carrying out oblique rolling perforation after heating below the beta phase transition point and heat preservation to obtain a pierced billet, carrying out periodic rolling after heating the pierced billet below the beta phase transition point to obtain a pipe blank, and preparing a finished pipe blank, namely carrying out stress relief annealing and machining on the pipe blank in sequence to obtain the high-oxygen pure titanium large-size fine-grain pipe. The method can enable the grain size to reach 7-8 levels.

Inventors

  • YUE XU
  • FANG YUAN
  • MA XU
  • GU ZHONGMING
  • TONG XIAOLE
  • Zhai Xinjiao
  • REN XINLONG
  • Jiao Jijun
  • QIAO ENLI

Assignees

  • 新疆湘润新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20260129

Claims (10)

  1. 1. The preparation method of the high-oxygen pure titanium large-specification fine-grain pipe is characterized by comprising the following steps of: Step 1, ingot casting smelting, namely selecting titanium sponge according to the set weight percentage range of chemical components of 0.26-0.30% of O, less than or equal to 0.4% of Fe, less than or equal to 0.1% of C, less than or equal to 0.05% of N, less than or equal to 0.015% of H and the balance Ti, then pressing the titanium sponge into an electrode, and carrying out post treatment after smelting on the electrode to obtain a high-oxygen pure titanium ingot casting; step 2, high Wen Kaipi forging, namely heating the high-oxygen pure titanium cast ingot obtained in the step 1 to a set temperature above a beta transformation point, and carrying out high Wen Huanxiang cogging forging after heat preservation; Step 3, low-temperature forging, namely heating the blank obtained after the cogging in the step 2 to a set temperature below a beta phase transition point, preserving heat, combining low-temperature reversing upsetting and drawing with drawing, and then machining to obtain a smooth rod blank; step 4, perforating Wen Xiega, namely processing a through hole in the center of the smooth rod blank obtained in the step 3, heating to a set temperature below a beta phase transition point, preserving heat, and then performing oblique rolling perforation to obtain a pierced billet; step 5, low-temperature rolling, namely heating the pierced billet obtained in the step 4 to a set temperature below the beta phase transition point, preserving heat, and then performing periodical rolling to obtain a tube billet; And 6, preparing a finished pipe, namely sequentially carrying out stress relief annealing and machining treatment on the pipe blank obtained in the step 5 to obtain the high-oxygen pure titanium large-specification fine-grain pipe.
  2. 2. The preparation method of claim 1, wherein in the step 1, the granularity of the titanium sponge is 0.83-25.4 mm, the electrode is subjected to 2 times of vacuum consumable arc melting, then a riser and a bottom of the ingot are removed, and the ingot is machined to remove oxide skin on the surface of the ingot, so that the high-oxygen pure titanium ingot with the specification phi 620-720 xL mm is prepared, wherein L is the length.
  3. 3. The preparation method of claim 1, wherein in the step 2, the Gao Yang pure titanium ingot is heated to 50-100 ℃ above the beta transformation point, and is subjected to high Wen Huanxiang cogging forging after heat preservation for 150-180 min, wherein the total deformation is 80% -90%; the high-temperature reversing cogging is forged into a shaft upsetting side drawing and a side upsetting shaft drawing.
  4. 4. The preparation method of the polished rod blank according to claim 1, wherein in the step 3, the blank obtained after the cogging in the step 2 is polished and heated to 100-150 ℃ below a beta phase transition point, and is subjected to low-temperature reversing upsetting and drawing for 2-3 times and drawing for 1 time after heat preservation for 270-300 min, wherein the total deformation of each time of reversing upsetting and drawing is 70% -80%, the total deformation of the drawing is 30% -45%, oxide skin and defects on the surface of the rod blank are removed by machining, and a smooth rod blank with the diameter of phi 500-phi 600 xL mm is prepared; The low Wen Huanxiang upsetting and pulling specific process of 2-3 times comprises the steps of carrying out the side upsetting and shaft pulling after the shaft upsetting and the side pulling in each time of reversing upsetting and pulling process, completing the reversing process once, and then carrying out air cooling and polishing.
  5. 5. The method according to claim 1, wherein in step 4, a through hole is processed at the center of the smooth rod blank, the through hole is heated to 50-100 ℃ below the beta transformation point, the temperature is kept for 360-400 min, a plug is used for oblique rolling perforation to prepare a pierced billet, and the total deformation is 40% -60%.
  6. 6. The method according to claim 1, wherein in step 5, the pierced blank is heated to a temperature of 100-150 ℃ below the beta transformation point, kept for 240-300 min, and subjected to periodical rolling to prepare a tube blank, wherein the total deformation is 40% -60%.
  7. 7. The method according to claim 1, wherein in the step 6, the stress relief annealing is performed by heating the tube blank to 600-640 ℃ and maintaining the temperature for 90-120 min, and then performing residual temperature straightening.
  8. 8. The method according to claim 1, wherein in the step 6, the machining is to perform turning, boring, sawing, facing and polishing on the tube blank after stress relief annealing to obtain the high-oxygen pure titanium large-specification fine-grain tube.
  9. 9. The high-oxygen pure titanium large-specification fine-grain pipe is characterized in that the high-oxygen pure titanium large-specification fine-grain pipe is prepared based on the preparation method of any one of claims 1-8, and the grain size of the high-oxygen pure titanium large-specification fine-grain pipe reaches 7-8 levels.
  10. 10. The high oxygen purity titanium large scale fine grain pipe of claim 9 wherein the large scale fine grain pipe has room temperature tensile strength >580MPa, yield strength >440MPa, elongation after break >20%, reduction of area >40%.

Description

High-oxygen pure titanium large-specification fine-grain pipe and preparation method thereof Technical Field The invention belongs to the technical field of titanium alloy pipes, and particularly relates to a high-oxygen pure titanium large-specification fine-grain pipe and a preparation method thereof, which are particularly suitable for application in the fields of petrochemical industry, ocean engineering equipment, ship manufacturing and the like. Background Titanium is an ideal material with an advanced lightweight structure by virtue of low density, high specific strength, excellent corrosion resistance and fatigue resistance, and has been widely applied to the fields of petrochemical industry, ocean engineering equipment, shipbuilding and the like. The pure titanium pipe, in particular to a large-caliber seamless pipe, has a wide application prospect because of the excellent structural efficiency and the good working condition adaptability, and is highly matched with the development of the fields of petrochemical industry, ocean engineering, ship manufacturing and the like. At present, most of the preparation of pure titanium seamless pipes still takes medium-small specification pipes with the outer diameter phi below 400mm as the main materials. The patent CN101708511B discloses a production method for preparing a pure titanium seamless pipe with the outer diameter phi of 10-89 mm, and the outer diameter of the pure titanium seamless pipe prepared by the patent CN104889163B, CN107234145B is not more than 114mm. With the development of the related field, the demand for the pure titanium large-size seamless pipe with the external diameter phi of more than 400mm is gradually growing. However, at present, researches on pure titanium large-size seamless pipes with the outer diameter phi of more than 400mm mainly comprise the forming technology of the pipes, and the tissue control technology of the pipes is less. The complexity of the application environment also puts higher demands on the comprehensive mechanical properties of the pure titanium seamless pipe. The large-size pure titanium seamless pipe prepared by the existing preparation method is coarse in crystal grains and low in strength, so that the comprehensive mechanical property of the pure titanium seamless pipe is low, for example, the large-size pure titanium seamless pipe is usually obtained by rolling after a blank is manufactured by a bevel rolling perforation method, but the heating system is usually selected to be higher than or slightly lower than the beta phase transition point temperature by the existing processing method of rolling after the bevel rolling perforation method. For example, patent CN111167862a uses heating temperatures of 900 ℃ (above the beta transus) and 850 ℃ (about 30-50 ℃ below the beta transus) to perforate and thermally expand the pure titanium rod blank. The higher heating temperature and deformation temperature rise effect are extremely easy to lead to grain growth, and the comprehensive mechanical property of the pure titanium seamless pipe is seriously reduced. For example, patent CN110170543A adopts a perforation temperature of 890-990 ℃, and the prepared pure titanium seamless pipe has an elongation of more than or equal to 45%, but the crystal grains of the pipe are coarse, the average size is more than or equal to 80 mu m, the strength is lower, the tensile strength is more than or equal to 320MPa, and the yield strength is more than or equal to 235MPa. In addition, the existing preparation method has higher production cost. Therefore, development of a method for preparing a large-size pure titanium seamless pipe with uniform and fine structure, strength and plasticity is needed to ensure the reliability and stability of the seamless pipe in a service environment. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a high-oxygen pure titanium large-specification fine-grain pipe and a preparation method thereof. The invention improves the comprehensive mechanical property of pure titanium pipe through two ways of gap solid solution strengthening and fine crystal strengthening, thus improving the O element content in cast ingot by expanding the selection range of sponge titanium in the component design process, utilizing the O element to be solid solution in HCP cells of pure titanium to influence the nucleation of dislocation inside pure titanium, adding O element can form O-Ti bond inside pure titanium, the formed O-Ti bond is higher than the bond energy of Ti-Ti bond of pure titanium, the lattice resistance of dislocation slip is improved when dislocation moves, and secondly, the shearing of tensile twin crystal is blocked by the improvement of pure titanium bond (O-Ti bond), thus effectively improving the strength of large-size pure titanium seamless pipe under the combined actions of influencing dislocation nucleation, improving the bond energy inside titani