Method for greatly improving yield of titanium alloy cold rolled tube

Abstract

The invention relates to the technical field of titanium alloys, and discloses a method for greatly improving the yield of a titanium alloy cold-rolled pipe, which comprises the following steps: sequentially carrying out first surface treatment, second surface treatment and third surface treatment on a titanium alloy pipe blank to obtain a titanium alloy cold-rolled pipe blank, and carrying out cold rolling on the titanium alloy cold-rolled pipe blank to obtain a titanium alloy cold-rolled pipe, and then the titanium alloy cold-rolled pipe is sequentially subjected to first annealing, acid pickling and chemical milling, and the titanium alloy finished pipe is obtained. According to the method, the titanium alloy pipe blank is subjected to surface treatment before cold rolling, the generation probability of surface defects of the titanium alloy is reduced, and the technical problems of low yield, high cost and low production efficiency of the small-caliber pure titanium and near-alpha titanium alloy seamless pipe are solved by reducing the surface treatment procedure between cold rolling passes.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloys, and in particular to a method for significantly improving the yield rate of titanium alloy cold-rolled tubes. Background Art

[0002] Usually, the manufacture of small-diameter pure titanium and near-α titanium alloy seamless tubes requires the use of hot perforated or extruded tube billets, which are processed by multiple cold rolling processes. Since the smaller the diameter of the titanium tube, the more cold rolling processes are required, and vacuum annealing treatment is also required, resulting in long production processes, low yield, high cost and low production efficiency. At present, the common production method of small-diameter pure titanium and near-α titanium alloys is to process hot extruded billets or perforated billets through 7 to 10 cold rolling processes, and vacuum annealing treatment is also required between passes. After each cold rolling, the outer surface of the titanium tube needs to be ground, and the inner surface of the titanium tube is sandblasted and pickled as a whole to eliminate the cracks on the inner and outer surfaces generated during the cold rolling process. If grinding, sandblasting and pickling cannot eliminate the cracks, the cracked titanium tube needs to be removed. Therefore, the yield from hot extruded billets or perforated billets to finished titanium tubes is only about 50%, which leads to high production costs and low production efficiency for small-diameter pure titanium and near-α titanium alloy seamless tubes.

[0003] CN 112845654 B discloses a method for preparing large-size seamless pipes of titanium and titanium alloys, which adopts electromagnetic casting of hollow tube billets, adopts two-roller or three-roller oblique rolling process to perform 2-3 oblique rolling to open the cast tube billets, and then performs warm rolling-cold rolling-intermediate annealing-cold stretching, or warm rolling-cold stretching, or warm rolling-diameter expansion stretching on the oblique rolled tube billets, and conducts quality inspection after the finished product annealing of the stretched tube. The prior art adopts hot rolling-warm rolling-cold stretching process, which can maximize the use of the plasticity of the alloy, reduce annealing and pickling processes, and reduce metal oxidation and pickling metal loss; through diameter reduction stretching, equal diameter stretching and diameter expansion stretching, it can produce ultra-long, ultra-large, and ultra-thick titanium and titanium alloy pipes with a diameter of Ф80mm-Ф424mm and a wall thickness of 2-30mm. However, the prior art directly prepares tube billets by smelting, which is not suitable for high-precision small-diameter pipes.

[0004] CN 114433654 A discloses a short-process, low-cost method for preparing TC4 seamless pipes, including (1) ingot preparation, (2) bar preparation, (3) tube preparation, (4) tube hot rolling, and (5) heat treatment and straightening of finished pipes; (4) tube hot rolling: the tubes punched out by oblique rolling are subjected to residual hot rolling on a hot rolling mill, and the finished product specifications are φ30 (±0.3) to φ80 (±0.3) × (5-15) (±0.3) mm; (5) heat treatment and straightening of finished pipes: annealing is performed in an electric resistance furnace and residual hot straightening is performed. This prior art performs simple machining on the smelted bar, then performs one-time oblique rolling perforation, and then hot rolling to form a finished product, thereby solving the problem of non-equiaxed structure of TC4 oblique rolled perforated pipes. However, this prior art is not suitable for the preparation of small-diameter pipes, and does not disclose improvement in yield.

[0005] CN 101476141A discloses a titanium alloy copper electroplating process, including a pre-treatment process and having the following technical features: (1) activating the surface of titanium alloy parts by sandblasting + chemical activation; sandblasting the parts with diamond sand at room temperature, and then activating them with a chemical activation solution containing hydrochloric acid and tropine; (2) pre-nickel plating the activated titanium alloy parts in a nickel plating solution; (3) copper plating the titanium alloy parts in a conventional copper plating solution. The prior art adopts sandblasting + chemical activation to improve the activation effect of titanium alloy copper plating. However, the influence of copper electroplating on the subsequent titanium alloy is not disclosed.

[0006] Based on this, there is room for improvement in increasing the yield rate of small-diameter pure titanium and near-α titanium alloy seamless tubes. Summary of the invention

[0007] In view of this, the present invention provides a method for significantly improving the yield rate of titanium alloy cold-rolled tubes, which solves the technical problems of low yield rate, high cost and low production efficiency of small-diameter pure titanium and near-α titanium alloy seamless tubes.

[0008] The present invention provides a method for significantly improving the yield rate of titanium alloy cold-rolled tubes, comprising: sequentially performing a first surface treatment, a second surface treatment, and a third surface treatment on a titanium alloy tube blank to obtain a titanium alloy cold-rolled tube blank, cold rolling the titanium alloy cold-rolled tube blank to obtain a titanium alloy cold-rolled tube, and then sequentially performing a first annealing, pickling, and chemical milling on the titanium alloy cold-rolled tube to obtain a titanium alloy finished tube.

[0009] In some embodiments, the first surface treatment is sandblasting, and the first surface treatment of the titanium alloy tube blank includes: using corundum with a pressure of 0.2MPa to 0.5MPa and a particle size of 100 mesh to 150 mesh to sandblast the inner and outer surfaces of the titanium alloy tube blank to obtain a titanium alloy tube blank after sandblasting.

[0010] In some embodiments, the second surface treatment is a chemical activation treatment, and the second surface treatment of the titanium alloy tube blank includes: using an activation solution, at a temperature of 18°C ​​to 25°C, and a chemical activation treatment time of 60s to 180s, to chemically activate the inner and outer surfaces of the titanium alloy tube blank after sandblasting to obtain a titanium alloy tube blank after chemical activation treatment.

[0011] In some embodiments, the composition of the activation solution used in the chemical activation treatment includes hydrochloric acid with ρ=1.19 g / ml, hydrofluoric acid with a volume percentage of 40%, and water, wherein the volume ratio of hydrochloric acid with ρ=1.19 g / ml, hydrofluoric acid with a volume percentage of 40%, and water in the activation solution is 4:3:3.

[0012] In some embodiments, the third surface treatment is copper plating. The third surface treatment of the titanium alloy tube blank includes: using a copper plating solution at a current density of 3A / dm 2 ~12A / dm 2 Under the conditions of 10min to 20min of copper plating time, the inner and outer surfaces of the titanium alloy tube blank after chemical activation treatment are copper plated to obtain a titanium alloy cold-rolled tube blank.

[0013] In some embodiments, the composition of the copper plating solution used in the copper plating treatment includes cuprous cyanide, sodium cyanide, sodium hydroxide, sodium carbonate decahydrate and potassium sodium tartrate, wherein the mass concentration of cuprous cyanide in the copper plating solution is 40 g / L, the mass concentration of sodium cyanide is 60 g / L, the mass concentration of sodium hydroxide is 15 g / L, the mass concentration of sodium carbonate decahydrate is 35 g / L, and the mass concentration of potassium sodium tartrate is 40 g / L.

[0014] In some embodiments, cold rolling a titanium alloy cold-rolled tube blank to obtain a titanium alloy cold-rolled tube includes performing multiple cold rolling passes on the titanium alloy cold-rolled tube blank, and cleaning and annealing the titanium alloy cold-rolled tube blank between two adjacent cold rolling passes to obtain the titanium alloy cold-rolled tube.

[0015] In some embodiments, the cleaning treatment includes removing dirt from the surface of the titanium alloy cold-rolled tube billet to obtain the cleaned titanium alloy cold-rolled tube billet, and the annealing treatment includes annealing the cleaned titanium alloy cold-rolled tube billet to obtain the annealed titanium alloy cold-rolled tube billet.

[0016] In some embodiments, performing a first annealing on the titanium alloy cold-rolled tube includes performing a first annealing on the titanium alloy cold-rolled tube at a first annealing temperature and maintaining the tube for a first holding time to obtain the titanium alloy cold-rolled tube after the first annealing.

[0017] In some embodiments, pickling the titanium alloy cold-rolled pipe includes using acid to remove the copper layer on the inner and outer surfaces of the titanium alloy cold-rolled pipe after the first annealing to obtain the pickled titanium alloy cold-rolled pipe; chemical milling the titanium alloy cold-rolled pipe includes using chemical milling liquid to chemically mill the pickled titanium alloy cold-rolled pipe to obtain a titanium alloy finished pipe.

[0018] Beneficial effects of the present invention: The method of the present invention greatly improves the yield rate of titanium alloy cold-rolled tubes. Before cold rolling, the titanium alloy tube blank is surface treated to reduce the probability of titanium alloy surface defects. By reducing the surface treatment process between cold rolling passes, the production of high-yield titanium alloy finished tubes is achieved, solving the technical problems of low yield rate, high cost and low production efficiency of small-diameter pure titanium and near-α titanium alloy seamless tubes. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in conjunction with specific embodiments.

[0020] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0021] The method for significantly improving the yield rate of titanium alloy cold-rolled tubes provided by the present invention comprises: sequentially performing a first surface treatment, a second surface treatment, and a third surface treatment on a titanium alloy tube blank to obtain a titanium alloy cold-rolled tube blank, cold-rolling the titanium alloy cold-rolled tube blank to obtain a titanium alloy cold-rolled tube, and then sequentially performing a first annealing, pickling, and chemical milling on the titanium alloy cold-rolled tube to obtain a titanium alloy finished tube.

[0022] Compared with the prior art, the method of the present invention greatly improves the yield rate of titanium alloy cold-rolled tubes. By surface treating the titanium alloy tube blank before cold rolling, the probability of surface defects of the titanium alloy is reduced. By reducing the surface treatment process between cold rolling passes, the production of high-yield titanium alloy finished tubes is achieved, solving the technical problems of low yield rate, high cost and low production efficiency of small-diameter pure titanium and near-α titanium alloy seamless tubes.

[0023] In some embodiments, the titanium alloy tube blank is prepared by conventional methods, for example, the titanium alloy tube blank is prepared by smelting+forging+hot extrusion.

[0024] In some embodiments, the titanium alloy tube may be a pure titanium tube or a near-alpha titanium alloy tube.

[0025] In some embodiments, the size of the titanium alloy tube blank is Φ88*8*1500-2000mm.

[0026] In some embodiments, the first surface treatment is sandblasting, and the first surface treatment of the titanium alloy tube blank includes: using corundum with a pressure of 0.2 MPa to 0.5 MPa and a particle size of 100 mesh to 150 mesh to sandblast the inner and outer surfaces of the titanium alloy tube blank to obtain a titanium alloy tube blank after sandblasting.

[0027] In some embodiments, the second surface treatment is a chemical activation treatment, and the composition of the activation solution used in the chemical activation treatment includes hydrochloric acid with a volume percentage of ρ=1.19 g / ml, hydrofluoric acid with a volume percentage of 40%, and water, wherein the volume percentage of hydrochloric acid with a volume percentage of ρ=1.19 g / ml in the activation solution is 35% to 45%, the volume percentage of hydrofluoric acid with a volume percentage of 40% is 25% to 35%, and the balance is water. The second surface treatment of the titanium alloy tube blank includes: using the activation solution, at a temperature of 18°C ​​to 25°C, and a chemical activation treatment time of 60s to 180s, chemically activating the inner and outer surfaces of the titanium alloy tube blank after sandblasting, to obtain a titanium alloy tube blank after chemical activation treatment.

[0028] In some embodiments, the volume ratio of hydrochloric acid (ρ=1.19 g / ml), hydrofluoric acid (40% by volume), and water in the activation solution is 4:3:3.

[0029] In some embodiments, the third surface treatment is copper plating, and the composition of the copper plating solution used in the copper plating includes cuprous cyanide (CuCN), sodium cyanide (NaCN), sodium hydroxide (NaOH), sodium carbonate decahydrate (Na2CO3·10H2O) and potassium sodium tartrate (KNaC4H4O6·4H2O), wherein the mass concentration of cuprous cyanide in the copper plating solution is 35g / L-45g / L, the mass concentration of sodium cyanide is 55 g / L-65g / L, the mass concentration of sodium hydroxide is 12g / L-18g / L, the mass concentration of sodium carbonate decahydrate is 32g / L-38g / L, and the mass concentration of potassium sodium tartrate is 35g / L-45g / L. The third surface treatment of the titanium alloy tube blank includes: using a copper plating solution at a current density of 3A / dm 2 ~12A / dm 2 (ampere per square decimeter) and copper plating time of 10min to 20min, the inner and outer surfaces of the titanium alloy tube blank after chemical activation treatment are copper plated to obtain a titanium alloy cold-rolled tube blank.

[0030] In some embodiments, the copper plating solution has a cuprous cyanide concentration of 40 g / L, a sodium cyanide concentration of 60 g / L, a sodium hydroxide concentration of 15 g / L, a sodium carbonate decahydrate concentration of 35 g / L, and a potassium sodium tartrate concentration of 40 g / L.

[0031] In some embodiments, cold rolling the titanium alloy cold rolled tube blank to obtain the titanium alloy cold rolled tube includes cold rolling the titanium alloy cold rolled tube blank for multiple passes, wherein the deformation of each cold rolling pass is greater than or equal to 40%, to obtain the titanium alloy cold rolled tube. For example, the titanium alloy cold rolled tube blank is cold rolled for 3 to 6 passes.

[0032] In some embodiments, performing multiple cold rolling passes on the titanium alloy cold rolled tube blank includes performing cleaning treatment and annealing treatment on the titanium alloy cold rolled tube blank between two adjacent cold rolling passes.

[0033] In some embodiments, the cleaning process includes removing dirt from the surface of the titanium alloy cold-rolled tube blank to obtain the cleaned titanium alloy cold-rolled tube blank. For example, the dirt on the surface of the titanium alloy cold-rolled tube blank is wiped off.

[0034] In some embodiments, the annealing treatment includes annealing the titanium alloy cold-rolled tube billet after the cleaning treatment to obtain an annealed titanium alloy cold-rolled tube billet.

[0035] In some embodiments, the annealing treatment conditions are: annealing temperature 500° C. to 830° C., and holding time 1 h to 2 h.

[0036] In some embodiments, performing a first annealing on the titanium alloy cold-rolled tube includes performing a first annealing on the titanium alloy cold-rolled tube at a first annealing temperature and maintaining the tube for a first holding time to obtain the titanium alloy cold-rolled tube after the first annealing.

[0037] In some embodiments, the first annealing temperature is 500° C. to 800° C., and the first holding time is 1 h to 2 h.

[0038] In some embodiments, pickling the titanium alloy cold-rolled tube includes removing the copper layer on the inner and outer surfaces of the titanium alloy cold-rolled tube after the first annealing using an acid solution to obtain the pickled titanium alloy cold-rolled tube.

[0039] In some embodiments, the acid solution includes nitric acid, hydrofluoric acid and water, wherein the volume ratio of nitric acid, hydrofluoric acid and water in the acid solution is 3:1:6.

[0040] In some embodiments, the pickling temperature is 50° C. to 70° C., and the pickling time is 60 min to 90 min.

[0041] In some embodiments, chemical milling of the titanium alloy cold-rolled pipe includes chemical milling of the pickled titanium alloy cold-rolled pipe using a chemical milling liquid to obtain a titanium alloy finished pipe.

[0042] In some embodiments, the chemical milling fluid is a HF-HNO3 type chemical milling fluid. The HF-HNO3 type chemical milling fluid includes hydrofluoric acid (HF) and nitric acid (HNO3). During the chemical milling process, hydrofluoric acid can react chemically with the titanium alloy to dissolve and etch the titanium alloy. Hydrofluoric acid can destroy the oxide film on the surface of the titanium alloy and directly react with the titanium element, so that the atoms on the surface of the material are continuously dissolved into the solution. Nitric acid mainly plays an oxidizing role, which can oxidize the low-valent titanium ions exposed on the surface of the titanium alloy after the hydrofluoric acid dissolves into high-valent titanium ions, making it easier to be further dissolved by hydrofluoric acid. At the same time, nitric acid also helps to control the reaction rate to avoid excessively violent reactions. The HF-HNO3 type chemical milling fluid can be purchased from outside or configured by yourself.

[0043] In some embodiments, the volume ratio of nitric acid, hydrofluoric acid, and water in the HF-HNO3 type chemical milling fluid is 3:1:6.

[0044] In some embodiments, the milling temperature is 60° C. to 70° C., and the milling time is 30 min to 60 min.

[0045] In some embodiments, the size of the titanium alloy finished tube is Φ25*2.1*1000-6000mm.

[0046] Embodiment 1 The method of significantly improving the yield rate of titanium alloy cold-rolled tubes of the present invention is applied in improving the yield rate of Φ25*2.1*6000mm pure titanium finished tubes as follows: Firstly, the inner and outer surfaces of the Φ88*8*1500mm pure titanium tube blank after oblique rolling and punching are sandblasted with diamond steel sand having a pressure of 0.2MPa and a particle size of 120 meshes to obtain the pure titanium tube blank after sandblasting.

[0047] Secondly, an activation solution with a volume ratio of 4:3:3 of hydrochloric acid (ρ=1.19 g / ml), hydrofluoric acid (40% by volume), and water (40% by volume) was used to chemically activate the inner and outer surfaces of the pure titanium tube blank after sandblasting at a temperature of 20°C and a chemical activation treatment time of 120 s to obtain a pure titanium tube blank after chemical activation treatment.

[0048] Secondly, copper plating solution was used at a current density of 10A / dm 2Under the conditions of 15 minutes of copper plating time, the inner and outer surfaces of the pure titanium tube blank after chemical activation treatment were copper plated to obtain a pure titanium cold-rolled tube blank. The copper plating solution contained 40 g / L of cuprous cyanide, 60 g / L of sodium cyanide, 15 g / L of sodium hydroxide, 35 g / L of sodium carbonate decahydrate, and 40 g / L of potassium sodium tartrate.

[0049] Secondly, the pure titanium cold-rolled tube billet is cold-rolled for three times, and the pure titanium cold-rolled tube billet is cleaned and annealed between two adjacent cold-rolling times. The deformation of the three cold-rolling times is 45%, 53%, and 71%, respectively, to obtain a pure titanium cold-rolled tube with a final size of Φ25*2.1*6000mm. That is, between the first cold-rolling and the second cold-rolling, the pure titanium cold-rolled tube billet after the first cold-rolling is subjected to the first cleaning treatment and the second annealing treatment, and between the second cold-rolling and the third cold-rolling, the pure titanium cold-rolled tube billet after the second cold-rolling is subjected to the second cleaning treatment and the third annealing treatment. The first cleaning treatment is to wipe the dirt on the surface of the pure titanium cold-rolled tube billet after the first cold-rolling to obtain the pure titanium cold-rolled tube billet after the first cleaning treatment, and the second annealing treatment is to perform the second vacuum annealing treatment on the pure titanium cold-rolled tube billet after the first cleaning treatment to obtain the pure titanium cold-rolled tube billet after the second annealing treatment, and the pure titanium cold-rolled tube billet after the second annealing treatment is subjected to the second cold-rolling. The annealing temperature of the second annealing treatment is 600°C, and the holding time is 2h. The second cleaning treatment is to wipe the dirt on the surface of the pure titanium cold-rolled tube billet after the second cold rolling, and obtain the pure titanium cold-rolled tube billet after the second cleaning treatment. The third annealing treatment is to perform a third vacuum annealing treatment on the pure titanium cold-rolled tube billet after the second cleaning treatment to obtain the pure titanium cold-rolled tube billet after the third annealing treatment. The pure titanium cold-rolled tube billet after the third annealing treatment is subjected to a third cold rolling. The annealing temperature of the third annealing treatment is 600°C, and the holding time is 2h.

[0050] Secondly, the pure titanium cold-rolled pipe of Φ25*2.1*6000mm is subjected to a first annealing to obtain the pure titanium cold-rolled pipe after the first annealing, the first annealing temperature is 550° C., and the first insulation time is 2h.

[0051] Secondly, the copper layer on the inner and outer surfaces of the pure titanium cold-rolled tube after the first annealing is removed by acid solution, and the copper layer generated during the copper plating process is removed to obtain the pure titanium cold-rolled tube after pickling. The volume ratio of nitric acid, hydrofluoric acid and water in the acid solution is 3:1:6, the pickling temperature is 55°C, and the pickling time is 90 minutes.

[0052] Finally, the pure titanium cold-rolled pipe after pickling was chemically milled using HF-HNO3 chemical milling liquid to optimize the surface quality of the pure titanium cold-rolled pipe after pickling, and obtain a Φ25*2.1*6000mm pure titanium finished pipe. The volume ratio of nitric acid, hydrofluoric acid and water in the HF-HNO3 chemical milling liquid is 3:1:6, the milling temperature is 65℃, and the milling time is 45min.

[0053] Embodiment 2 The method of significantly improving the yield rate of titanium alloy cold-rolled tubes of the present invention is applied in improving the yield rate of Φ25*2.1*6000mmTA18 titanium alloy finished tubes as follows: Firstly, the inner and outer surfaces of the Φ88*8*1500mm TA18 titanium alloy tube blank after oblique rolling and punching were sandblasted with diamond grit having a pressure of 0.3 MPa and a particle size of 150 meshes to obtain the sandblasted TA18 titanium alloy tube blank.

[0054] Secondly, an activation solution with a volume ratio of 4:3:3 of hydrochloric acid (ρ=1.19 g / ml), hydrofluoric acid (40% by volume), and water (40% by volume) was used to chemically activate the inner and outer surfaces of the TA18 titanium alloy tube blank after sandblasting at a temperature of 20°C and a chemical activation treatment time of 120 s to obtain a TA18 titanium alloy tube blank after chemical activation treatment.

[0055] Secondly, copper plating solution was used at a current density of 8A / dm 2 Under the conditions of 20 minutes of copper plating time, the inner and outer surfaces of the TA18 titanium alloy tube blank after chemical activation treatment were copper plated to obtain a TA18 titanium alloy cold-rolled tube blank. The copper plating solution contained 40 g / L of cuprous cyanide, 60 g / L of sodium cyanide, 15 g / L of sodium hydroxide, 35 g / L of sodium carbonate decahydrate, and 40 g / L of potassium sodium tartrate.

[0056] Secondly, the TA18 titanium alloy cold-rolled tube billet is cold-rolled for three times, and the TA18 titanium alloy cold-rolled tube billet is cleaned and annealed between two adjacent cold-rolling times. The deformation amounts of the three cold-rolling times are 43%, 51%, and 68%, respectively, to obtain a TA18 titanium alloy cold-rolled tube with a final size of Φ25*2.1*6000mm. That is, between the first cold-rolling and the second cold-rolling, the TA18 titanium alloy cold-rolled tube billet after the first cold-rolling is cleaned for the first time and annealed for the second time, and between the second cold-rolling and the third cold-rolling, the TA18 titanium alloy cold-rolled tube billet after the second cold-rolling is cleaned for the second time and annealed for the third time. The first cleaning treatment is to wipe the dirt on the surface of the TA18 titanium alloy cold-rolled tube billet after the first cold rolling, and obtain the TA18 titanium alloy cold-rolled tube billet after the first cleaning treatment. The second annealing treatment is to perform a second vacuum annealing treatment on the TA18 titanium alloy cold-rolled tube billet after the first cleaning treatment to obtain the TA18 titanium alloy cold-rolled tube billet after the second annealing treatment, and the TA18 titanium alloy cold-rolled tube billet after the second annealing treatment is subjected to a second cold rolling. The annealing temperature of the second annealing treatment is 700°C, and the holding time is 2h. The second cleaning treatment is to wipe the dirt on the surface of the TA18 titanium alloy cold-rolled tube billet after the second cold rolling, and obtain the TA18 titanium alloy cold-rolled tube billet after the second cleaning treatment. The third annealing treatment is to perform a third vacuum annealing treatment on the TA18 titanium alloy cold-rolled tube billet after the second cleaning treatment to obtain the TA18 titanium alloy cold-rolled tube billet after the third annealing treatment, and the TA18 titanium alloy cold-rolled tube billet after the third annealing treatment is subjected to a third cold rolling. The annealing temperature of the third annealing treatment is 700° C., and the holding time is 2 h.

[0057] Secondly, the TA18 titanium alloy cold-rolled tube with a size of Φ25*2.1*6000mm is subjected to a first annealing to obtain the TA18 titanium alloy cold-rolled tube after the first annealing, the first annealing temperature is 600° C., and the first insulation time is 2h.

[0058] Secondly, the copper layer on the inner and outer surfaces of the TA18 titanium alloy cold-rolled tube after the first annealing is removed by acid solution, and the copper layer generated during the copper plating process is removed to obtain the TA18 titanium alloy cold-rolled tube after pickling. The volume ratio of nitric acid, hydrofluoric acid and water in the acid solution is 3:1:6, the pickling temperature is 50°C, and the pickling time is 80 minutes.

[0059] Finally, HF-HNO3 chemical milling liquid was used to chemically mill the TA18 titanium alloy cold-rolled pipe after pickling, and the surface quality of the TA18 titanium alloy cold-rolled pipe after pickling was optimized to obtain Φ25*2.1*6000mmTA18 titanium alloy finished pipe. The volume ratio of nitric acid, hydrofluoric acid and water in the HF-HNO3 chemical milling liquid was 3:1:6, the milling temperature was 60℃, and the milling time was 40min.

[0060] Comparative Example 1 The Φ88*8*1500mm pure titanium tube blank after oblique rolling and punching was subjected to vacuum annealing treatment at a temperature of 600°C and a holding time of 2h to obtain a pure titanium tube blank after vacuum annealing treatment.

[0061] The pure titanium tube blank after vacuum annealing is cold rolled for three times, and the pure titanium tube blank is annealed and surface pickled between two adjacent cold rolling passes to obtain a pure titanium cold rolled tube with a final size of Φ25*2.1*6000mm. That is, between the first cold rolling and the second cold rolling, the pure titanium tube blank after the first cold rolling is subjected to the second annealing treatment and the first surface pickling treatment, and between the second cold rolling and the third cold rolling, the pure titanium tube blank after the second cold rolling is subjected to the third annealing treatment and the second surface pickling treatment. The second annealing treatment is to perform a second vacuum annealing treatment on the pure titanium tube billet after the first cold rolling, the annealing temperature of the second annealing treatment is 600°C, the holding time is 2h, and the pure titanium tube billet after the second annealing treatment is obtained. The first surface pickling treatment is to pickle the pure titanium tube billet after the second annealing treatment, wherein the volume ratio of nitric acid, hydrofluoric acid and water in the acid solution used for pickling is 3:1:6, the pickling temperature is 65°C, and the pickling time is 50min, to obtain the pure titanium tube billet after the first surface pickling treatment, and the pure titanium tube billet after the first surface pickling treatment is subjected to a second cold rolling. The third annealing treatment is to perform a third vacuum annealing treatment on the pure titanium tube billet after the second cold rolling. The annealing temperature of the third annealing treatment is 600°C and the holding time is 2h to obtain the pure titanium tube billet after the third annealing treatment. The second surface pickling treatment is to pickle the pure titanium tube billet after the third annealing treatment, wherein the volume ratio of nitric acid, hydrofluoric acid and water in the acid solution used for pickling is 3:1:6, the pickling temperature is 65°C, and the pickling time is 50min to obtain the pure titanium tube billet after the second surface pickling treatment. The pure titanium tube billet after the second surface pickling treatment is subjected to a third cold rolling.

[0062] The Φ25*2.1*6000mm pure titanium cold-rolled pipe is subjected to a first annealing to obtain a pure titanium cold-rolled pipe after the first annealing. The first annealing temperature is 550° C. and the first insulation time is 2 h.

[0063] HF-HNO3 type chemical milling liquid is used to chemically mill the inner and outer surfaces of the pure titanium cold-rolled pipe after the first annealing, wherein the volume ratio of nitric acid, hydrofluoric acid and water in the HF-HNO3 type chemical milling liquid is 3:1:6, the milling temperature is 65°C, the milling time is 50min, and a Φ25*2.1*6000mm pure titanium finished pipe is obtained.

[0064] Comparative Example 2 The Φ88*8*1500mmTA18 titanium alloy tube blank after oblique rolling and punching was subjected to vacuum annealing treatment at an annealing temperature of 700°C and a holding time of 2h to obtain a TA18 titanium alloy tube blank after vacuum annealing treatment.

[0065] The TA18 titanium alloy tube blank after vacuum annealing is cold rolled for three times, and the TA18 titanium alloy tube blank is annealed and surface pickled between two adjacent cold rolling passes to obtain a TA18 titanium alloy cold rolled tube with a final size of Φ25*2.1*6000mm. That is, between the first cold rolling and the second cold rolling, the TA18 titanium alloy tube blank after the first cold rolling is subjected to the second annealing treatment and the first surface pickling treatment, and between the second cold rolling and the third cold rolling, the TA18 titanium alloy tube blank after the second cold rolling is subjected to the third annealing treatment and the second surface pickling treatment. The second annealing treatment is to perform a second vacuum annealing treatment on the TA18 titanium alloy tube billet after the first cold rolling, the annealing temperature of the second annealing treatment is 700°C, and the holding time is 2h, to obtain the TA18 titanium alloy tube billet after the second annealing treatment, the first surface pickling treatment is to pickle the TA18 titanium alloy tube billet after the second annealing treatment, wherein the volume ratio of nitric acid, hydrofluoric acid and water in the acid solution used for pickling is 3:1:6, the pickling temperature is 60°C, and the pickling time is 40min, to obtain the TA18 titanium alloy tube billet after the first surface pickling treatment, and the TA18 titanium alloy tube billet after the first surface pickling treatment is subjected to a second cold rolling. The third annealing treatment is to perform a third vacuum annealing treatment on the TA18 titanium alloy tube billet after the second cold rolling. The annealing temperature of the third annealing treatment is 700°C and the holding time is 2h to obtain the TA18 titanium alloy tube billet after the third annealing treatment. The second surface pickling treatment is to pickle the TA18 titanium alloy tube billet after the third annealing treatment, wherein the volume ratio of nitric acid, hydrofluoric acid and water in the acid solution used for pickling is 3:1:6, the pickling temperature is 60°C, and the pickling time is 40min to obtain the TA18 titanium alloy tube billet after the second surface pickling treatment. The TA18 titanium alloy tube billet after the second surface pickling treatment is subjected to a third cold rolling.

[0066] The Φ25*2.1*6000mm TA18 titanium alloy cold-rolled tube is subjected to a first annealing to obtain the TA18 titanium alloy cold-rolled tube after the first annealing. The first annealing temperature is 600° C. and the first insulation time is 2 h.

[0067] The inner and outer surfaces of the TA18 titanium alloy cold-rolled tube after the first annealing were chemically milled using HF-HNO3 type chemical milling liquid, wherein the volume ratio of nitric acid, hydrofluoric acid and water in the HF-HNO3 type chemical milling liquid was 3:1:6, the milling temperature was 60°C, the milling time was 40 min, and a Φ25*2.1*6000mm TA18 titanium alloy finished tube was obtained.

[0068] The yield rates of Example 1 and Example 2 and Comparative Example 1 and Comparative Example 2 are shown in Table 1.

[0069] Table 1 Yield rate

[0070] It can be seen from Table 1 that when the same tube billet is rolled to the same finished product specification, the cold rolling yield rate of the finished tube can be effectively improved by using the method of the present invention. This is under the three-pass cold rolling process. If the number of cold rolling passes is increased, the cold rolling yield rate of the finished tube will be further increased. The method of the present invention has a significant effect on improving the yield rate of cold-rolled tubes.

[0071] The method of the present invention for greatly improving the yield rate of cold-rolled titanium alloy tubes adopts a surface copper plating method to avoid direct contact between the surface of the titanium alloy tube blank and the mold during the cold rolling process, which can not only reduce the probability of surface defects and improve the surface quality of the titanium alloy, but also reduce the surface treatment procedures (such as grinding, sandblasting, pickling, etc.) between cold rolling passes, thereby reducing manufacturing costs and improving the yield rate of tubes. The method of the present invention is highly operable and has good promotion prospects. The method of the present invention is combined with surface copper plating to reduce the intermediate treatment procedures during the cold rolling process of titanium alloy tubes, improve the yield rate of tubes, and at the same time do not reduce the mechanical properties of the tubes. The surface copper plating process is simple, highly operable, and cost-controllable. The method of the present invention can be used for cold rolling of pure titanium and near-α titanium alloy tubes, and has promotion significance.

[0072] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for significantly improving the yield rate of titanium alloy cold-rolled tubes, characterized in that: include: The titanium alloy tube blank is subjected to a first surface treatment, a second surface treatment and a third surface treatment in sequence to obtain a titanium alloy cold-rolled tube blank, the titanium alloy cold-rolled tube blank is cold-rolled to obtain a titanium alloy cold-rolled tube, and then the titanium alloy cold-rolled tube is subjected to a first annealing, pickling and chemical milling in sequence to obtain a titanium alloy finished tube.

2. The method for significantly improving the yield rate of titanium alloy cold-rolled tube according to claim 1 is characterized in that: The first surface treatment is sandblasting, and the first surface treatment of the titanium alloy tube blank includes: using corundum with a pressure of 0.2MPa to 0.5MPa and a particle size of 100 to 150 meshes to sandblast the inner and outer surfaces of the titanium alloy tube blank to obtain a titanium alloy tube blank after sandblasting.

3. The method for significantly improving the yield rate of titanium alloy cold-rolled tube according to claim 2 is characterized in that: The second surface treatment is a chemical activation treatment, and the second surface treatment of the titanium alloy tube blank includes: using an activation solution, at a temperature of 18°C ​​to 25°C, and a chemical activation treatment time of 60s to 180s, to chemically activate the inner and outer surfaces of the titanium alloy tube blank after sandblasting to obtain a titanium alloy tube blank after chemical activation treatment.

4. The method for significantly improving the yield rate of titanium alloy cold-rolled tube according to claim 3 is characterized in that: The activation solution used in the chemical activation treatment comprises hydrochloric acid with ρ=1.19 g / ml, hydrofluoric acid with a volume percentage of 40%, and water, wherein the volume ratio of hydrochloric acid with ρ=1.19 g / ml, hydrofluoric acid with a volume percentage of 40%, and water in the activation solution is 4:3:

3.

5. The method for significantly improving the yield rate of titanium alloy cold-rolled tube according to claim 3 is characterized in that: The third surface treatment is copper plating. The third surface treatment of the titanium alloy tube blank includes: using a copper plating solution at a current density of 3A / dm 2 ~12A / dm 2 Under the conditions of 10 min to 20 min of copper plating time, the inner and outer surfaces of the titanium alloy tube blank after the chemical activation treatment are copper plated to obtain the titanium alloy cold-rolled tube blank.

6. The method for significantly improving the yield rate of titanium alloy cold-rolled tube according to claim 5, characterized in that: The copper plating solution used in the copper plating treatment comprises cuprous cyanide, sodium cyanide, sodium hydroxide, sodium carbonate decahydrate and potassium sodium tartrate, wherein the mass concentration of cuprous cyanide in the copper plating solution is 40 g / L, the mass concentration of sodium cyanide is 60 g / L, the mass concentration of sodium hydroxide is 15 g / L, the mass concentration of sodium carbonate decahydrate is 35 g / L, and the mass concentration of potassium sodium tartrate is 40 g / L.

7. The method for significantly improving the yield rate of titanium alloy cold-rolled tube according to claim 1 is characterized in that: Cold rolling a titanium alloy cold-rolled tube blank to obtain a titanium alloy cold-rolled tube material includes performing multiple cold rolling passes on the titanium alloy cold-rolled tube blank, and cleaning and annealing the titanium alloy cold-rolled tube blank between two adjacent cold rolling passes to obtain the titanium alloy cold-rolled tube material.

8. The method for significantly improving the yield rate of titanium alloy cold-rolled tube according to claim 7, characterized in that: The cleaning treatment includes removing dirt from the surface of the titanium alloy cold-rolled tube billet to obtain the cleaned titanium alloy cold-rolled tube billet, and the annealing treatment includes annealing the cleaned titanium alloy cold-rolled tube billet to obtain the annealed titanium alloy cold-rolled tube billet.

9. The method for significantly improving the yield rate of titanium alloy cold-rolled tube according to claim 1, characterized in that: The first annealing of the titanium alloy cold-rolled tube includes performing the first annealing of the titanium alloy cold-rolled tube at a first annealing temperature and keeping the tube warm for a first holding time to obtain the titanium alloy cold-rolled tube after the first annealing.

10. The method for significantly improving the yield rate of titanium alloy cold-rolled tube according to claim 9, characterized in that: The pickling of the titanium alloy cold-rolled pipe includes using acid to remove the copper layer on the inner and outer surfaces of the titanium alloy cold-rolled pipe after the first annealing to obtain the pickled titanium alloy cold-rolled pipe; the chemical milling of the titanium alloy cold-rolled pipe includes using chemical milling liquid to chemically mill the pickled titanium alloy cold-rolled pipe to obtain the titanium alloy finished pipe.

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