A processing method for improving the surface quality of titanium alloy wire

Abstract

This invention discloses a processing method for improving the surface quality of titanium alloy wire. The method includes: 1. Obtaining a titanium alloy wire blank using conventional hot working methods; 2. Removing the surface oxide scale and then performing repair and polishing treatment; 3. Cold rolling to obtain the wire; 4. Atmospheric annealing treatment of the wire; 5. Roll milling and stretching or drawing to the finished size; 6. Removing the surface oxide scale and performing surface cleaning; 7. Finished product annealing treatment to obtain the finished titanium alloy wire. This invention, by performing atmospheric annealing treatment before the last rolling pass of the titanium alloy wire processing to form an oxide layer that protects the wire, increases the surface strength, hardness, and surface resistance of the wire, and avoids obvious surface defects such as folds and pits. While ensuring the performance of the titanium alloy wire, it greatly improves its surface quality. This method is simple to operate and is especially suitable for improving the surface quality of finished wires with a diameter not exceeding 1.6 mm. It can be extended to other alloy fine wires.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy preparation technology, and specifically relates to a processing method for improving the surface quality of titanium alloy wire. Background Technology

[0002] Titanium and titanium alloys are widely used in aerospace and nuclear industries due to their excellent comprehensive properties. Titanium and titanium alloy wires are mostly used as welding wires for titanium materials, such as for welding various titanium equipment, repair welding of pipes, turbine disks and blades of aero-jet engines, and casing welding. To ensure reliable welding performance, the wire composition is generally close to that of the base metal, and there are strict requirements for the content of impurity elements. In recent years, the global production of titanium materials has steadily increased, and the demand for titanium wires used as welding materials for titanium alloys is also constantly growing. Since the quality of welding wire directly affects the overall quality and reliability of the welded parts, with the rapid development of advanced welding and rapid repair technologies for titanium alloy materials, design departments have also put forward more stringent quality requirements for titanium alloy welding materials. While ensuring the compositional properties of titanium alloy welding wires, it is necessary to also possess good plasticity, formability, and welding performance. At the same time, higher requirements are placed on the microstructure, strength, and surface quality of titanium alloy wires, requiring the wires to have a uniform microstructure, free of surface and internal defects, while improving the strength and plasticity of the alloy.

[0003] Because finished welding wires have high requirements for surface quality, a smooth surface is required. Welding wires prepared by cold rolling or roller milling have certain surface defects, resulting in low dimensional accuracy and failing to meet the surface quality requirements of finished wires. This is especially true for fine wires, where roller milling or cold rolling processes cannot guarantee dimensional accuracy and surface smoothness, potentially leading to defects such as folds, loops, or pits. Furthermore, their small diameter prevents surface machining, resulting in substandard surface quality and affecting product quality and yield. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a processing method for improving the surface quality of titanium alloy wire. This method involves performing atmospheric annealing before the final rolling pass in the processing of the finished titanium alloy wire to form an oxide layer on the wire surface. This increases the surface strength, hardness, and surface resistance of the wire, protecting the wire surface and preventing obvious surface defects such as folds and pits. While ensuring the wire's performance, this method significantly improves the surface quality of the titanium alloy wire, solving the problem of insufficient surface quality due to wire diameters that cannot be processed by surface machining.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a processing method for improving the surface quality of titanium alloy wire, characterized in that the method includes the following steps:

[0006] Step 1: Obtain titanium alloy wire blanks using conventional hot working methods;

[0007] Step 2: Remove the surface oxide scale from the titanium alloy wire blank obtained in Step 1 and perform repair and polishing treatment.

[0008] Step 3: The titanium alloy wire blank that has been repaired and polished in Step 2 is cold rolled, and vacuum annealing is carried out between rolling strokes to obtain the wire material.

[0009] Step 4: Perform atmospheric annealing on the filaments obtained in Step 3;

[0010] Step 5: Roll-stretch or draw the filament that has undergone atmospheric annealing in Step 4 to the finished size;

[0011] Step 6: Remove the surface oxide scale from the filaments stretched by the roller mill in Step 5 and clean the surface.

[0012] Step 7: Perform a finished product annealing treatment on the wire material that has been surface cleaned in Step 6 to obtain the finished titanium alloy wire material.

[0013] This invention first obtains a titanium alloy wire blank through conventional hot working methods, then removes the surface oxide scale and polishes it to obtain a smooth wire blank without defects. This avoids the inheritance, extension, and expansion of defects in the titanium alloy wire blank during subsequent processing, which would affect product quality. Next, this invention uses cold rolling and roller milling to uniformly deform the titanium alloy wire blank, ensuring the uniformity of the obtained wire microstructure and avoiding core voids caused by inconsistent core and surface deformation during conventional hot drawing. At the same time, vacuum annealing is used between rolling strokes to eliminate cold work hardening and avoid excessive oxygen content in the product caused by atmospheric annealing. Subsequently, this invention performs atmospheric annealing before the last rolling stroke to obtain the finished size, which creates an oxide layer on the wire surface, increasing the surface strength and hardness of the wire. This protects the wire surface during the roller milling or drawing stage of the last rolling stroke, preventing surface defects caused by softening of the wire during processing. The oxide scale layer is then removed and the surface is cleaned. The finished titanium alloy wire is obtained after finishing annealing.

[0014] The above-mentioned processing method for improving the surface quality of titanium alloy wire is characterized in that the conventional hot working method in step one includes: obtaining a titanium alloy ingot by vacuum consumable melting according to the nominal composition ratio of the titanium alloy, and then performing forging, rolling and hot gauge rounding on the titanium alloy ingot, wherein the diameter of the titanium alloy wire blank is not greater than 10mm.

[0015] The above-mentioned processing method for improving the surface quality of titanium alloy wire is characterized in that, in step two, the surface oxide scale is removed by surface peeling and polishing, and a smooth titanium alloy wire blank with good surface quality is obtained after repair and polishing.

[0016] The above-mentioned processing method for improving the surface quality of titanium alloy wire is characterized in that, in step three, the deformation amount of a single rolling stroke is not less than 40%, and a vacuum annealing process is used between rolling strokes to eliminate work hardening. The vacuum annealing process is as follows: temperature 700℃~740℃, holding time 40min~60min; the diameter of the wire in step three is not greater than 2.2mm.

[0017] The above-mentioned processing method for improving the surface quality of titanium alloy wire is characterized in that the atmospheric annealing process in step four is as follows: temperature 700℃~750℃, holding time 40min~60min, and air cooling.

[0018] The above-mentioned processing method for improving the surface quality of titanium alloy wire is characterized in that the roller milling or drawing in step five is the last rolling stroke, and the cumulative deformation is not less than 45%. This invention ensures the uniformity of the microstructure and mechanical properties of the titanium alloy wire by controlling the cumulative deformation of the last rolling stroke to be not less than 45%, thus avoiding insufficient deformation that could lead to inadequate performance of the titanium alloy wire.

[0019] The above-mentioned processing method for improving the surface quality of titanium alloy wire is characterized in that, in step six, the surface oxide scale is removed by pickling to obtain wire with no oxygen-rich layer, no defects, and good surface quality. The pickling solution used is prepared by H2O, HNO3, and HF in a volume ratio of 7-12:2-4:1, wherein both HNO3 and HF are industrial acids, with HNO3 having a mass concentration of 65%-68% and HF having a mass concentration of 40%.

[0020] The above-mentioned processing method for improving the surface quality of titanium alloy wire is characterized in that the finished product annealing treatment in step seven is a vacuum dehydrogenation annealing treatment.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. This invention performs atmospheric annealing before the last rolling stroke in the processing of titanium alloy wire to form an oxide layer on the wire surface, increasing the surface strength, hardness, and surface resistance of the wire. This oxide layer then protects the wire surface during the final rolling, stretching, or drawing stage, preventing obvious surface defects such as folds and pits, as well as surface roughness, snagging, and breakage caused by wire peeling. While ensuring wire performance, this invention significantly improves the surface quality of titanium alloy wire, solving the problem that surface quality and dimensional accuracy are difficult to control due to size effects and equipment precision limitations in the processing of titanium alloy fine wire. Furthermore, existing peeling processes also cannot guarantee the smoothness of the finished fine wire surface, failing to meet surface requirements and affecting product quality.

[0023] 2. This invention removes the surface oxide scale of titanium alloy wire blanks by surface peeling and polishing. On the one hand, it ensures the smooth surface of the wire blanks before rolling. On the other hand, peeling and polishing can effectively remove surface defects of the wire blanks, avoid the extension and expansion of defects in subsequent processing, and help improve the surface quality of titanium alloy wires.

[0024] 3. The present invention uses cold rolling and roller milling to reduce the diameter of the wire blank in the intermediate process, which can ensure the uniformity of the wire structure and avoid uneven microstructure and voids caused by inconsistent deformation of the surface and core due to wire drawing.

[0025] 4. The method of the present invention is simple to operate and effectively solves the problems of pits, sharp edges, folds and ear loops on the surface of titanium alloy wires. It significantly improves the yield reduction caused by surface problems of titanium alloy wires. It is especially suitable for improving the surface quality of wires with a finished diameter of no more than 1.6 mm and can be extended to other alloy wires.

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0027] Figure 1 This is a low-magnification microstructure image of the finished titanium alloy wire prepared in Example 1 of the present invention.

[0028] Figure 2 This is a surface state diagram of the finished titanium alloy wire prepared in Comparative Example 1 of the present invention.

[0029] Figure 3 This is a low-magnification microstructure image of the finished titanium alloy wire prepared in Example 2 of the present invention.

[0030] Figure 4 This is a surface state diagram of the finished titanium alloy wire prepared in Comparative Example 2 of the present invention.

[0031] Figure 5 This is a low-magnification microstructure image of the finished titanium alloy wire prepared in Example 3 of the present invention.

[0032] Figure 6 This is a surface state diagram of the finished titanium alloy wire prepared in Comparative Example 3 of the present invention. Detailed Implementation

[0033] Example 1

[0034] This embodiment includes the following steps:

[0035] Step 1: According to the nominal composition of titanium alloy Ti-2Al-2.5Zr, three vacuum self-consumption melting processes are carried out to obtain titanium alloy ingots. Then, the titanium alloy ingots are forged and rolled to obtain titanium alloy wire blanks with a diameter of 9.5mm. Finally, they are hot-gauge rounded at 850℃ to obtain titanium alloy wire blanks with a diameter of φ9.0mm.

[0036] Step 2: Remove the surface oxide scale from the titanium alloy wire blank obtained in Step 1 by surface peeling and polishing, and perform surface repair and polishing to obtain a smooth titanium alloy wire blank with good surface quality and no defects and a diameter of φ8.5mm.

[0037] Step 3: The smooth titanium alloy wire blank obtained in Step 2 is cold rolled with the following rolling strokes: φ8.5mm→φ6.5mm→φ4.5mm→φ3.2mm→φ2.2mm. The rolling strokes are combined with degreasing, cleaning and vacuum annealing processes. The vacuum annealing process is: temperature 700℃, holding time 60min, to obtain wire with a diameter of φ2.2mm.

[0038] Step 4: The filament obtained in Step 3 is subjected to atmospheric annealing at 700℃ for 60 minutes.

[0039] Step 5: The wire material that has undergone atmospheric annealing in Step 4 is subjected to a final rolling mill stretching process to a diameter of φ1.6mm;

[0040] Step 6: Remove the surface oxide scale from the filaments stretched by the roller mill in Step 5 by pickling. The pickling solution is prepared by mixing H2O, HNO3, and HF in a volume ratio of 7:2:1. Industrial acids are used for both HNO3 and HF. The mass concentration of HNO3 is 65% to 68%, and the mass concentration of HF is 40%. Surface cleaning is then performed to obtain filaments without an oxygen-rich layer, without defects, and with good surface quality.

[0041] Step 7: Perform vacuum dehydrogenation annealing on the wire material after surface cleaning in Step 6, with the following conditions: 630℃ / 1h + 670℃ / 3h + 710℃ / 1h, to obtain finished titanium alloy wire material with good microstructure, properties and surface quality.

[0042] Figure 1 This is a low-magnification microstructure image of the finished titanium alloy wire prepared in this embodiment. Figure 1 It can be seen that the surface of the finished titanium alloy wire is smooth and without defects.

[0043] Comparative Example 1

[0044] The difference between this comparative example and Example 1 is that the atmospheric annealing treatment in step four was not performed.

[0045] Figure 2 This is a surface condition diagram of the finished titanium alloy wire prepared in this comparative example. Figure 2 It can be seen that the surface of the finished titanium alloy wire has pits of varying degrees, indicating that the surface strength of the wire was low during the final rolling process, resulting in pits on the wire surface caused by external defects during the deformation process.

[0046] Example 2

[0047] This embodiment includes the following steps:

[0048] Step 1: According to the nominal composition of titanium alloy Ti-2Al-1.5V, three vacuum self-consumption melting processes are carried out to obtain titanium alloy ingots. Then, the titanium alloy ingots are forged and rolled to obtain titanium alloy wire blanks with a diameter of 10.0 mm. The blanks are then hot-gauge rounded at 850℃ to obtain titanium alloy wire blanks with a diameter of φ8.7 mm.

[0049] Step 2: Remove the surface oxide scale from the titanium alloy wire blank obtained in Step 1 by surface peeling and polishing, and perform surface repair and polishing to obtain a smooth titanium alloy wire blank with good surface quality and no defects and a diameter of φ8.0mm.

[0050] Step 3: The smooth titanium alloy wire blank obtained in Step 2 is cold rolled with the following rolling strokes: φ8.0mm→φ5.9mm→φ4.2mm→φ3.1mm→φ2.25mm→φ1.65mm. The rolling strokes are combined with degreasing, cleaning and vacuum annealing processes. The vacuum annealing process is: temperature 740℃, holding time 40min, to obtain wire with a diameter of φ1.65mm.

[0051] Step 4: The filament obtained in Step 3 is subjected to atmospheric annealing at 750℃ for 40 minutes.

[0052] Step 5: Perform a final rolling mill stretching process on the wire material that has undergone atmospheric annealing in Step 4 to a diameter of φ1.2mm.

[0053] Step 6: Remove the surface oxide scale from the filaments stretched by the roller mill in Step 5 by pickling. The pickling solution is prepared by mixing H2O, HNO3, and HF in a volume ratio of 8:4:1. Industrial acids are used for both HNO3 and HF. The mass concentration of HNO3 is 65% to 68%, and the mass concentration of HF is 40%. Surface cleaning is then performed to obtain filaments without an oxygen-rich layer, without defects, and with good surface quality.

[0054] Step 7: Perform vacuum dehydrogenation annealing on the wire material after surface cleaning in Step 6, with the following conditions: 630℃ / 1h + 670℃ / 3h + 710℃ / 1h, to obtain finished titanium alloy wire material with good microstructure, properties and surface quality.

[0055] Figure 3 This is a low-magnification microstructure image of the finished titanium alloy wire prepared in this embodiment. Figure 3 It can be seen that the surface of the finished titanium alloy wire is smooth and without defects.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 2 is that the atmospheric annealing treatment in step four was not performed.

[0058] Figure 4 This is a surface condition diagram of the finished titanium alloy wire prepared in this comparative example. Figure 4 It can be seen that the surface of the finished titanium alloy wire has a relatively thick and deep fold.

[0059] Example 3

[0060] This embodiment includes the following steps:

[0061] Step 1: According to the nominal composition of titanium alloy Ti-2Al-2.5Zr, three vacuum self-consumption melting processes are carried out to obtain titanium alloy ingots. Then, the titanium alloy ingots are forged and rolled to obtain titanium alloy wire blanks with a diameter of φ9mm. The blanks are then hot-gauge rounded at 850℃ to obtain titanium alloy wire blanks with a diameter of φ8.2mm.

[0062] Step 2: Remove the surface oxide scale from the titanium alloy wire blank obtained in Step 1 by surface peeling and polishing, and perform surface repair and polishing to obtain a smooth titanium alloy wire blank with good surface quality and no defects and a diameter of φ7.8mm.

[0063] Step 3: The smooth titanium alloy wire blank obtained in Step 2 is cold rolled with the following rolling strokes: φ7.8mm→φ5.4mm→φ3.3mm→φ2.05mm→φ1.6mm. The rolling strokes are combined with degreasing, cleaning and vacuum annealing processes. The vacuum annealing process is: temperature 740℃, holding time 40min, to obtain wire with a diameter of φ1.6mm.

[0064] Step 4: The filament obtained in Step 3 is subjected to atmospheric annealing at 750℃ for 60 minutes.

[0065] Step 5: The wire material that has undergone atmospheric annealing in Step 4 is drawn to a diameter of φ1.0mm in the next rolling pass;

[0066] Step 6: Remove the surface oxide scale from the filaments stretched by the roller mill in Step 5 by pickling. The pickling solution is prepared by mixing H2O, HNO3, and HF in a volume ratio of 12:3:1. Industrial acids are used for both HNO3 and HF. The mass concentration of HNO3 is 65% to 68%, and the mass concentration of HF is 40%. Surface cleaning is then performed to obtain filaments without an oxygen-rich layer, without defects, and with good surface quality.

[0067] Step 7: Perform vacuum dehydrogenation annealing on the wire material after surface cleaning in Step 6, with the following conditions: 630℃ / 1h + 670℃ / 3h + 710℃ / 1h, to obtain finished titanium alloy wire material with good microstructure, properties and surface quality.

[0068] Figure 5 This is a low-magnification microstructure image of the finished titanium alloy wire prepared in this embodiment. Figure 5 It can be seen that the surface of the finished titanium alloy wire is smooth and without defects.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 3 is that the atmospheric annealing treatment in step four was not performed.

[0071] Figure 6 This is a surface condition diagram of the finished titanium alloy wire prepared in this comparative example. Figure 6 It can be seen that the surface of the finished titanium alloy wire still has certain surface defects, and the surface is uneven, mainly due to processing defects caused by insufficient surface strength.

[0072] comprehensive Figures 1-6 It is understood that by performing atmospheric annealing treatment before the last rolling stroke in the processing of titanium alloy wire, the present invention avoids obvious surface defects such as folds and pits in the wire, as well as surface roughness, earing and easy breakage caused by wire peeling. Under the premise of ensuring wire performance, the surface quality of titanium alloy wire is greatly improved.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A processing method for improving the surface quality of a titanium alloy wire, characterized by, The method comprises the following steps: Step one, obtaining a titanium alloy wire blank according to a conventional hot working method; Step two, removing the surface oxide skin of the titanium alloy wire blank obtained in step one and performing a scratch polishing treatment; Step three, cold rolling the titanium alloy wire blank after the scratch polishing treatment in step two, and cooperating with a vacuum annealing process between rolling processes to obtain a wire; Step four, performing an air annealing treatment on the wire obtained in step three; the system of the air annealing treatment is: temperature 700-750 DEG C, holding time 40-60 min, air cooling; Step five, performing roll grinding stretching or drawing to the finished product size on the wire after the air annealing treatment in step four; Step six, removing the surface oxide skin of the wire after the roll grinding stretching or drawing in step five and performing surface cleaning; Step seven, performing a finished product annealing treatment on the wire after the surface cleaning in step six to obtain a finished product titanium alloy wire.

2. The method of claim 1, wherein the titanium alloy wire is a titanium alloy wire having a diameter of 0.1 mm or less. The conventional hot working method in step one comprises: obtaining a titanium alloy ingot by vacuum self-consumption smelting according to the nominal composition ratio of the titanium alloy, and then performing open forging rolling and hot sizing on the titanium alloy ingot; the diameter of the titanium alloy wire blank is not greater than 10 mm.

3. The method of claim 1, wherein the titanium alloy wire is a titanium alloy wire having a diameter of 0.1 mm or less. In step two, the surface oxide skin is removed by surface skinning and polishing, and a smooth titanium alloy wire blank with good surface quality is obtained after the scratch polishing treatment.

4. The method of claim 1, wherein the titanium alloy wire is a titanium alloy wire having a diameter of 0.1 mm or less. In step three, the single rolling process deformation of the cold rolling is not less than 40%, and the vacuum annealing process is cooperated between rolling processes to eliminate cold work hardening; the system of the vacuum annealing is: temperature 700-740 DEG C, holding time 40-60 min; the diameter of the wire in step three is not greater than 2.2 mm.

5. The method of claim 1, wherein the titanium alloy wire is a titanium alloy wire having a diameter of 0.1 mm or less. In step five, the roll grinding stretching or drawing is the last rolling process, and the cumulative deformation is not less than 45%.

6. The method of claim 1, wherein the titanium alloy wire is a titanium alloy wire having a diameter of 0.1 mm or less. In step six, the surface oxide skin is removed by pickling to obtain a wire without an oxygen-rich layer, defects and good surface quality, and the pickling solution used for pickling is prepared by H2O, HNO3 and HF according to a volume ratio of 7-12:2-4:1, wherein the HNO3 and HF acids are industrial acids, the mass concentration of HNO3 is 65%-68%, and the mass concentration of HF is 40%.

7. The method of claim 1, wherein the titanium alloy wire is a titanium alloy wire having a diameter of 0.1 mm or less. In step seven, the finished product annealing treatment is a vacuum hydrogen removal annealing treatment.

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