A preparation method of a TA16 titanium alloy ribbed special-shaped seamless tube

Abstract

The present invention provides a method for preparing a TA16 titanium alloy ribbed special-shaped seamless tube, comprising the following steps: Step 1: three VAR smeltings to obtain a titanium alloy ingot; Step 2: the titanium alloy ingot is formed into a titanium alloy round rod; Step 3: the titanium alloy round rod is formed into a hollow tube billet; Step 4: the hollow tube billet is cold-rolled in three passes on a two-roll cold rolling mill to produce a titanium alloy seamless tube, and vacuum annealing is performed after each cold rolling pass; the cold rolling process is designed to ensure that the deformation rate ε and K value of each cold rolling pass are greater than those of the previous pass; Step 5: the titanium alloy seamless tube is cold-rolled in a single pass on the two-roll cold rolling mill with a deformation rate ε of 34% to 35% and a K value of 2.9 to 3.0 to produce a titanium alloy ribbed special-shaped seamless tube; Step 6: the titanium alloy ribbed special-shaped seamless tube produced in Step 5 is pickled, vacuum annealed, inspected, and packaged. The product produced by this method has uniform composition, high dimensional accuracy, and good strength-ductility matching; the processing technology is stable, the yield rate is high, and the cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of TA16 titanium alloy seamless tubes, and more specifically, to a method for preparing a TA16 titanium alloy ribbed special-shaped seamless tube. Background Art

[0002] In order to improve the heat transfer efficiency of TA16 titanium alloy heat exchanger tubes, 4 rib lines need to be prepared on the outer surface of the titanium alloy seamless tubes. Since the dimensional tolerances of the rib lines and the tubes are required to be very strict, 4 to 5 dimensional tolerance requirements need to be met simultaneously. At the same time, the mechanical properties, process properties, flaw detection and other indicators of the titanium tubes need to meet the technical requirements. Therefore, the preparation process of TA16 titanium alloy ribbed special-shaped seamless tubes is very complex; the melting and forging processes of TA16 titanium alloy tube blanks, the cold rolling process of TA16 titanium alloy seamless tubes, and the annealing process during cold rolling all affect the dimensions, properties, and defects of the final ribbed special-shaped titanium alloy tube products. However, there is currently no systematic, stable and efficient preparation process technology that covers all processes of TA16 titanium alloy ribbed special-shaped seamless tubes. Summary of the Invention

[0003] In view of the above technical problems, a method for preparing a TA16 titanium alloy ribbed special-shaped seamless tube is provided.

[0004] The technical means adopted by the present invention are as follows:

[0005] A method for preparing a TA16 titanium alloy ribbed special-shaped seamless tube includes the following steps:

[0006] Step 1: Obtain a TA16 titanium alloy ingot through three times of VAR melting;

[0007] Step 2: The TA16 titanium alloy ingot is made into a TA16 titanium alloy round bar through 4 fire times of three upsetting and three drawing free forging, 1 fire time of hot rolling, and 2 fire times of radial forging, and the flaw detection of the TA16 titanium alloy round bar reaches Class AA of the GB / T5193 standard;

[0008] Step 3: The TA16 titanium alloy round bar is machined into a hollow tube blank through drilling, internal boring, and external turning, and the wall thickness tolerance of the hollow tube blank is ≤0.1 mm;

[0009] Step 4: The hollow tube blank is cold rolled into a TA16 titanium alloy seamless tube with an outer diameter of D1 and a wall thickness of S1 through 3 passes on a two-high cold rolling mill, and vacuum annealing is performed after each pass of cold rolling;

[0010] The cold rolling process design ensures that the deformation rate ε and K value of each pass of cold rolling are larger than those of the previous pass;

[0011] When a titanium alloy tube with an outer diameter of Da and a wall thickness of Sa is cold rolled into a titanium alloy tube with an outer diameter of Db and a wall thickness of Sb in one pass, the deformation rate ε calculation formula for this pass of cold rolling is:

[0012] ε = ((Da - Sa) × Sa - (Db - Sb) × Sb) / ((Da - Sa) × Sa);

[0013] The calculation formula for the K value of this pass of cold rolling is: K = (Sa - Sb) × Da / (Da - Db) × Sa;

[0014] The vacuum annealing process for a titanium alloy tube with an outer diameter of Db and a wall thickness of Sb after cold rolling with a deformation rate of ε is as follows: the heating rate is 2 °C per minute, the vacuum annealing temperature is (600 + 300 × ε) °C, and the holding time is 55 × Sb minutes;

[0015] Step Five: Cold roll the TA16 titanium alloy seamless tube with an outer diameter of D1 and a wall thickness of S1 obtained in Step Four on a two - roll cold - rolling tube mill in one pass with a deformation rate ε of 34% - 35% and a K value of 2.9 - 3.0 to produce a TA16 titanium alloy ribbed special - shaped seamless tube; the total length L of the pass section of the two - roll cold - rolling tube mill consists of a diameter - reducing section, a diameter - reducing and wall - reducing section, and a finishing section. Among them, the length of the diameter - reducing section is 5% of the total length L of the pass section, the length of the diameter - reducing and wall - reducing section is 15% of the total length L of the pass section. Grooves are engraved on the diameter - reducing section, the diameter - reducing and wall - reducing section, and the finishing section. The width and depth of the grooves are 0.2 mm larger than the width and height of the straight ribs on the outer surface of the TA16 titanium alloy ribbed special - shaped seamless tube respectively. The two - roll Pilger cold - rolling tube mill adopts single rotation, single feeding, and the rotation angles of the servo - motor - driven inlet chuck and the servo - motor - driven mandrel are synchronously set to 90°. The feeding amount is the same as the value of the wall thickness S1 of the TA16 titanium alloy seamless tube obtained in Step Four, and it is rolled 40 - 50 times per minute;

[0016] Step Six: Pickle, vacuum anneal, inspect, and package the TA16 titanium alloy ribbed special - shaped seamless tube produced in Step Five.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The triple VAR melting provided by the present invention ensures uniform composition of TA16 titanium alloy; the hot deformation process combination of three-pass three-drawing blanking, hot rolling and radial forging ensures uniform structure and properties of TA16 titanium alloy round bars, and the flaw detection can reach Class AA of GB / T5193 standard; the round bars are machined into hollow billets by drilling, internal boring and external turning, which can completely avoid the defects on the inner and outer surfaces of the billets; the wall thickness difference of the machined billets is extremely small, and the dimensional difference is further reduced after multiple passes of cold rolling. The outer diameter, inner diameter dimensional difference of the TA16 titanium alloy seamless pipe made is ≤0.01 mm, and the wall thickness difference is ≤0.03 mm, thus ensuring the dimensional accuracy of the ribbed special-shaped seamless pipe rolled; the design of the 3-pass cold rolling process makes the deformation amount and K value of each pass of cold rolling larger than the previous pass, ensuring uniform structure and appropriate texture orientation of the TA16 titanium alloy seamless pipe made by cold rolling, so as to ensure that the straight ribs of the ribbed TA16 titanium alloy seamless pipe made by cold rolling can be accurately formed, with high dimensional accuracy and uniform properties of the finished titanium pipe; the annealing temperature is calculated according to the deformation amount, and the annealing holding time is determined according to the wall thickness of the titanium alloy pipe. The designed vacuum annealing process not only ensures full recrystallization but also avoids grain growth; through a series of cold rolling experiments, the deformation rate ε in step five is 34% - 35%, the K value is 2.9 - 3.0, the rolling mill rotates single, feeds single, the rotation angles of the servo motor-driven inlet chuck and the servo motor-driven mandrel are synchronously set to 90°, the feeding amount is S1, and the rolling mill rolls 40 - 50 times per minute. The optimal cold rolling process parameters of a series of straight rib rolling processes are obtained, and combined with the length design of the pass reduction section and the reduction and wall thickness reduction section, as well as the groove size design engraved on the reduction section and the reduction and wall thickness reduction section, it is ensured that the five dimensions of the outer diameter, inner diameter, wall thickness, width of the straight rib, and height of the straight rib of the ribbed finished pipe meet the requirements at the same time. Finally, the finished pipe is obtained through pickling, vacuum annealing, inspection and packaging.

[0019] For the above reasons, the present invention can be widely promoted in the fields such as ribbed special-shaped seamless pipes of TA16 titanium alloy. Brief Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a cross-sectional view of a ribbed special-shaped seamless pipe of TA16 titanium alloy in the specific embodiment of the present invention. Specific Embodiments

[0022] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] The described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way restricts the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts belong to the scope of protection of the present invention.

[0024] A preparation method of a TA16 titanium alloy ribbed profiled seamless tube includes the following steps:

[0025] Step 1: Obtain a TA16 titanium alloy ingot through three times of VAR melting;

[0026] Step 2: The TA16 titanium alloy ingot is made into a TA16 titanium alloy round bar through 4 fire passes of three upsetting and three drawing free forging, 1 fire pass of hot rolling, and 2 fire passes of radial forging, and the TA16 titanium alloy round bar is detected by flaw detection to reach Class AA of the GB / T5193 standard;

[0027] Step 3: The TA16 titanium alloy round bar is machined by drilling, internal boring, and external turning to make a hollow tube blank, and the wall thickness difference of the hollow tube blank ≤ 0.1 mm;

[0028] Step 4: The hollow tube blank is cold-rolled through 3 passes on a two-high cold rolling mill to make a TA16 titanium alloy seamless tube with an outer diameter of D1 and a wall thickness of S1, and vacuum annealing is performed after each pass of cold rolling;

[0029] The cold rolling process design ensures that the deformation rate ε and K value of each pass of cold rolling are larger than those of the previous pass;

[0030] When a titanium alloy tube with an outer diameter of Da and a wall thickness of Sa is cold-rolled in one pass to a titanium alloy tube with an outer diameter of Db and a wall thickness of Sb, the calculation formula for the deformation rate ε of this pass of cold rolling is:

[0031] ε = ((Da - Sa) × Sa - (Db - Sb) × Sb) / ((Da - Sa) × Sa);

[0032] The calculation formula for the K value of this pass of cold rolling is: K = (Sa - Sb) × Da / (Da - Db) × Sa;

[0033] The vacuum annealing process for a titanium alloy tube with an outer diameter of Db and a wall thickness of Sb after cold rolling with a deformation rate of ε is: the heating rate is 2 °C / minute, the vacuum annealing temperature is (600 + 300 × ε) °C, and the holding time is 55 × Sb minutes;

[0034] Step 5: Cold roll the TA16 titanium alloy seamless tube with an outer diameter of D1 and a wall thickness of S1 obtained in Step 4 on a two-high cold rolling mill to form a TA16 titanium alloy profiled seamless tube with ribs in one pass with a deformation rate ε of 34% - 35% and a K value of 2.9 - 3.0; the total length of the working section of the pass of the two-high cold rolling mill is L, which consists of a reducing section, a reducing and wall-thinning section, and a finishing section. The length of the reducing section is 5% of the total length L of the working section of the pass, and the length of the reducing and wall-thinning section is 15% of the total length L of the working section of the pass. The reducing section, the reducing and wall-thinning section, and the finishing section are engraved with grooves, and the width and depth of the grooves are 0.2 mm larger than the width and height of the straight ribs on the outer surface of the TA16 titanium alloy profiled seamless tube with ribs respectively. The two-high Pilger cold rolling mill adopts single rotation and single feeding, and the rotation angles of the servo motor-driven inlet (blank) chuck and the servo motor-driven mandrel are synchronously set to 90°. The feeding amount is the same as the wall thickness S1 value of the TA16 titanium alloy seamless tube obtained in Step 4, and it is rolled 40 - 50 times per minute;

[0035] Step 6: Pickle, vacuum anneal, inspect, and package the TA16 titanium alloy profiled seamless tube with ribs made in Step 5. The cross-section of the TA16 titanium alloy profiled seamless tube with ribs is as Figure 1 shown.

[0036] Example 1

[0037] Produce a TA16 titanium alloy seamless tube with ribs having a width of 0.5 mm and a height of 1 mm and a production specification of Φ14×1 mm.

[0038] The production process flow adopted is: triple vacuum consumable to form a Φ490 round TA16 titanium alloy ingot → 4-fire three-upsetting and three-drawing free forging on a hydraulic press to form a Φ180 round bar → 1-fire hot rolling to form a Φ100 round bar → 2-fire rotary swaging to form a Φ42 black round bar → machining by drilling, internal boring, and external turning to form a Φ37×4 hollow tube blank with a wall thickness tolerance of 0.09 mm → cold rolling on a two-high cold rolling mill to form a Φ30×3.5 titanium tube (ε is 30%, K value is 0.66) → vacuum annealing at 690 °C (600 + 300×0.3), holding for 192.5 minutes (55×3.5) → cold rolling on a two-high cold rolling mill to form a Φ23×2.5 titanium tube (ε is 45%, K value is 1.22) → vacuum annealing at 735 °C (600 + 300×0.45), holding for 137.5 minutes (55×2.5) → cold rolling on a two-high cold rolling mill to form a Φ15.5×1.4 titanium tube (ε is 61%, K value is 1.35) → vacuum annealing at 783 °C (600 + 300×0.61), holding for 77 minutes (55×1.4) → cold rolling on a two-high cold rolling mill to form a Φ14×1 ribbed titanium tube (ε is 34%, K value is 2.95, the feeding amount of the rolling mill is 1.4 mm, and the rolling speed is 45 times per minute) → pickling, vacuum annealing, straightening, inspection, and packaging.

[0039] Among them, the total length L of the working section of the pass of the two-high cold rolling tube mill that cold-rolls from the Φ15.5×1.4 specification to the Φ14×1 specification is 600 mm. Among them, the length of the diameter reduction section of the pass is 30 mm, and the length of the diameter and wall thickness reduction section of the pass is 90 mm. Grooves with a width of 0.7 mm and a depth of 1.2 mm are engraved on the diameter reduction section and the diameter and wall thickness reduction section of the pass, and the straight ribs rolled out are 0.5 - 0.505 mm wide and 1.0 - 1.01 mm high.

[0040] For the seamless TA16 titanium alloy tube with the Φ14×1 mm specification prepared in this embodiment, the range difference of the outer diameter and inner diameter dimensions is 0.009 mm, and the range difference of the wall thickness is 0.027 mm.

[0041] Example 2

[0042] Produce seamless TA16 titanium alloy tubes with ribs that are 0.5 mm wide and 1 mm high and have a specification of Φ16×1.1 mm.

[0043] The production process flow adopted is as follows: triple vacuum consumable electrode melting to produce a Φ490 circular TA16 titanium alloy ingot → four-pass free forging on a hydraulic press to form a Φ180 round bar → one-pass hot rolling to form a Φ100 round bar → two-pass rotary swaging to form a Φ42 black round bar → machining by drilling, internal boring, and external turning to produce a Φ37×4 hollow tube blank with a wall thickness range difference of 0.09 mm → cold rolling on a two-high cold rolling tube mill to produce a Φ30×3.5 titanium tube (ε is 30%, K value is 0.66) → vacuum annealing at 690 °C (600 + 300×0.3) for 192.5 minutes (55×3.5) → cold rolling on a two-high cold rolling tube mill to produce a Φ23×2.5 titanium tube (ε is 45%, K value is 1.22) → vacuum annealing at 735 °C (600 + 300×0.45) for 137.5 minutes (55×2.5) → cold rolling on a two-high cold rolling tube mill to produce a Φ17.7×1.54 titanium tube (ε is 51%, K value is 1.67) → vacuum annealing at 753 °C (600 + 300×0.51) for 84.7 minutes (55×1.54) → cold rolling on a two-high cold rolling tube mill to produce a Φ16×1.1 ribbed titanium tube (ε is 34%, K value is 2.97, the mill feed is 1.54 mm, and the rolling speed is 46 times per minute) → pickling, vacuum annealing, straightening, inspection, and packaging.

[0044] Among them, the total length L of the working section of the pass of the two-high cold rolling tube mill that cold-rolls from the Φ17.7×1.54 specification to the Φ16×1.1 specification is 600 mm. Among them, the length of the diameter reduction section of the pass is 30 mm, and the length of the diameter and wall thickness reduction section of the pass is 90 mm. Grooves with a width of 0.7 mm and a depth of 1.2 mm are engraved on the diameter reduction section and the diameter and wall thickness reduction section of the pass, and the straight ribs rolled out are 0.5 - 0.51 mm wide and 1.01 - 1.02 mm high.

[0045] The difference between the maximum and minimum values of the outer diameter and inner diameter of the Φ16×1.1mm TA16 titanium alloy seamless tube produced in this embodiment is 0.008mm, and the wall thickness difference is 0.029mm.

[0046] Example 3

[0047] Produce a Φ18×1.2mm TA16 titanium alloy seamless tube with ribs that are 0.8mm wide and 1.5mm high.

[0048] The production process flow adopted is as follows: three times of vacuum consumable electrode melting to produce a Φ490 circular TA16 titanium alloy ingot → four-pass free forging on a hydraulic press to form a Φ180 round bar → one-pass hot rolling to form a Φ100 round bar → two-pass radial forging to form a Φ45 black skin round bar → drilling, internal boring, and external turning by machining to produce a Φ40×4 hollow tube blank with a wall thickness difference of 0.09mm → cold rolling on a two-high cold rolling mill to produce a Φ32×3.5 titanium tube (ε is 31%, K value is 0.63) → vacuum annealing at 693°C (600 + 300×0.31) for 192.5 minutes (55×3.5) → cold rolling on a two-high cold rolling mill to produce a Φ25×2.5 titanium tube (ε is 44%, K value is 1.31) → vacuum annealing at 732°C (600 + 300×0.44) for 137.5 minutes (55×2.5) → cold rolling on a two-high cold rolling mill to produce a Φ19.9×1.68 titanium tube (ε is 46%, K value is 1.61) → vacuum annealing at 738°C (600 + 300×0.46) for 92.4 minutes (55×1.68) → cold rolling on a two-high cold rolling mill to produce a Φ18×1.2 ribbed titanium tube (ε is 34%, K value is 2.99, the mill feed is 1.68mm, and the rolling speed is 44 times per minute) → pickling, vacuum annealing, straightening, inspection, and packaging.

[0049] Among them, the total length L of the working section of the pass of the two-high cold rolling mill for cold rolling from the Φ19.9×1.68 specification to the Φ18×1.2 specification is 600mm, of which the length of the diameter reduction section of the pass is 30mm, and the length of the diameter reduction and wall thickness reduction section of the pass is 90mm. Grooves with a width of 1.0mm and a depth of 1.7mm are engraved on the diameter reduction section and the diameter reduction and wall thickness reduction section of the pass, and the straight ribs rolled out are 0.80 - 0.81mm wide and 1.50 - 1.51mm high.

[0050] The difference between the maximum and minimum values of the outer diameter and inner diameter of the Φ18×1.2mm TA16 titanium alloy seamless tube produced in this embodiment is 0.009mm, and the wall thickness difference is 0.029mm.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a TA16 titanium alloy ribbed special-shaped seamless tube, characterized in that, It includes the following steps: Step 1: Obtain a TA16 titanium alloy ingot through three times of VAR melting; Step 2: Process the TA16 titanium alloy ingot into a TA16 titanium alloy round bar, and perform flaw detection on the TA16 titanium alloy round bar to reach Class AA of the GB / T5193 standard; Step 3: Process the TA16 titanium alloy round bar into a hollow tube blank, and the wall thickness tolerance of the hollow tube blank ≤ 0.1 mm; Step 4: Cold-roll the hollow tube blank on a two-high cold-rolling mill through 3 passes to form a TA16 titanium alloy seamless tube with an outer diameter of D1 and a wall thickness of S1, and perform vacuum annealing after each cold-rolling pass; The cold-rolling process design ensures that the deformation rate ε and K value of each cold-rolling pass are larger than those of the previous pass; When a titanium alloy tube with an outer diameter of Da and a wall thickness of Sa is cold-rolled in one pass into a titanium alloy tube with an outer diameter of Db and a wall thickness of Sb, the formula for calculating the deformation rate ε of this cold-rolling pass is: ε = ((Da - Sa)×Sa - (Db - Sb)×Sb) / ((Da - Sa)×Sa); The formula for calculating the K value of this cold-rolling pass is: K = (Sa - Sb)×Da / ((Da - Db)×Sa); The vacuum annealing process for the titanium alloy tube with an outer diameter of Db and a wall thickness of Sb after cold-rolling with a deformation rate of ε is: the heating rate is 2 °C / minute, the vacuum annealing temperature is (600 + 300×ε) °C, and the holding time is 55×Sb minutes; Step 5: Cold-roll the TA16 titanium alloy seamless tube with an outer diameter of D1 and a wall thickness of S1 obtained in Step 4 on a two-high cold-rolling mill in one pass with a deformation rate ε of 34% - 35% and a K value of 2.9 - 3.0 to form a TA16 titanium alloy ribbed profiled seamless tube. The total length L of the working section of the pass of the two-high cold-rolling mill consists of a diameter-reducing section, a diameter-reducing and wall-thinning section, and a finishing section. Among them, the length of the diameter-reducing section is 5% of the total length L of the working section of the pass, the length of the diameter-reducing and wall-thinning section is 15% of the total length L of the working section of the pass. The diameter-reducing section, the diameter-reducing and wall-thinning section, and the finishing section are engraved with grooves, and the width and depth of the grooves are 0.2 mm larger than the width and height of the straight ribs on the outer surface of the TA16 titanium alloy ribbed profiled seamless tube respectively. The two-high cold-rolling mill adopts single rotation, single feeding, and the rotation angles of the servo-motor-driven inlet chuck and the servo-motor-driven mandrel are synchronously set to 90°. The feeding amount is the same as the value of the wall thickness S1 of the TA16 titanium alloy seamless tube obtained in Step 4, and it is rolled 40 - 50 times per minute; Step 6: Pickle, perform vacuum annealing, inspect, and package the TA16 titanium alloy ribbed profiled seamless tube made in Step 5.

2. The preparation method of a TA16 titanium alloy ribbed special-shaped seamless tube according to claim 1, wherein In Step 2, the TA16 titanium alloy ingot is processed into a TA16 titanium alloy round bar through 4 fire times of three-upsetting and three-drawing free forging, 1 fire time of hot rolling, and 2 fire times of rotary forging.

3. The preparation method of a TA16 titanium alloy ribbed special-shaped seamless tube according to claim 1, characterized in that, In Step 3, the TA16 titanium alloy round bar is processed into a hollow tube blank through drilling, internal boring, and external turning machining.

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