Preparation process of nickel-aluminum alloy wire

Abstract

The invention belongs to the field of metal material processing, and particularly relates to a preparation process of a nickel-aluminum alloy wire, which comprises the following steps: S1, smelting and pre-adjusting components; s2, supplementing the intermediate alloy; s3, hot working; s4, drawing and intermediate annealing; s5, locking the surface state; s6, composite boiling washing and closed-loop control; and S7, finish broaching and the like. The problems that in an existing nickel-aluminum alloy wire preparation process, active microelements are not evenly dispersed and prone to burning loss, the yield is reduced easily when the area reduction rate is high, and arcing is unstable due to contact resistance fluctuation caused by defects existing on the alloy surface can be effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of alloy technology, and specifically relates to a preparation process for nickel-aluminum alloy wire. Background Technology

[0002] Existing nickel-aluminum alloy wires used for arc spraying / flame spraying are typically prepared through a process of "vacuum / protected melting - ingot casting - forging hot rolling - multi-pass drawing - multiple annealing - acid and alkali cleaning - precision drawing". This type of process generally faces two key challenges in large-scale production: First, active trace elements (such as RE, Zr, and B) are easily burned off, oxidized, and incorporated into inclusions during the high-temperature holding periods of melting and casting. Furthermore, uneven dispersion due to solidification segregation leads to batch-to-batch fluctuations in microstructure and inclusions. Second, the wire surface is prone to rapid re-oxidation and adsorption of oil / particle contamination after annealing, causing fluctuations in wire feeding contact resistance. This, in turn, leads to problems such as arc ignition failure, increased coating porosity, and increased dispersion in bonding strength, affecting the stability and consistency of the bonding layer as a "reliable interface".

[0003] Furthermore, existing processes often struggle to achieve high cumulative reduction rates (e.g., around 80%), even though high reduction rates help reduce the number of annealing cycles, shorten production cycle time, and improve efficiency. This is because as deformation accumulates, work hardening significantly intensifies, and residual stress and microcrack initiation and propagation become more severe. Simultaneously, inclusions, compositional segregation, and surface defects are amplified under high strain, easily leading to instability phenomena such as wire breakage, die sticking, and tearing. This forces the process to employ more frequent intermediate annealing or reduce the reduction rate per pass, thereby reducing production line efficiency and introducing more process fluctuations.

[0004] To address the aforementioned issues, existing technologies typically employ the following measures: increasing the melting vacuum and protective atmosphere, and extending stirring / homogenization to reduce segregation; using one-time addition or increasing the amount of trace elements to compensate for burn-off; reducing the single-pass surface area reduction rate, increasing the number of intermediate annealing cycles, or increasing the annealing temperature during the drawing stage to "preserve the finished product"; and improving wire feeding and arc initiation stability on the surface treatment side through conventional pickling / solvent degreasing or adding a lubricating layer or inorganic coating.

[0005] However, the above methods still have significant drawbacks: adding or over-compensating trace elements at once can easily form coarse oxide / sulfide inclusions, which become sources of defects such as wire breakage and performance dispersion; frequent annealing and low surface area reduction can reduce the risk of wire breakage, but they will significantly lengthen the process route, reduce efficiency, and may cause grain coarsening and performance fluctuations; conventional cleaning has limited constraints on the randomness of re-oxidation and contamination adsorption after annealing, and if the coating / lubricating layer is heat-resistant or has unstable adhesion, it is easy to decompose, peel off, or leave inclusions at the arc-starting high temperature, further deteriorating the porosity and bonding strength consistency. Therefore, there is an urgent need for a new nickel-aluminum alloy wire preparation process that can balance trace element homogenization and low burn-off, achieve high surface area reduction and high yield, and stabilize the surface electrical contact state. Summary of the Invention

[0006] The purpose of this invention is to address the problems in the existing nickel-aluminum alloy wire preparation process, such as uneven dispersion and easy burn-off of active trace elements, reduced yield at high surface reduction rates, and unstable arc initiation due to contact resistance fluctuations caused by alloy surface defects. This invention provides a novel preparation process for nickel-aluminum alloy wire. This process effectively solves the aforementioned problems through pre-adjustment of composition and Ni-reservation strategy during the melting stage, adding Ni-based master alloy and homogenizing it within a preset superheat window, single intermediate annealing to reset work hardening at a cumulative surface reduction rate of approximately 80%, low-oxygen / low-dew-point closed-loop cooling and time-limited transport to lock the surface state after annealing, and a composite boiling and washing closed-loop control based on the contact resistance fluctuation value ΔR. To achieve the above objective, the technical solution adopted by this invention to solve its technical problems is as follows: This invention provides a process for preparing nickel-aluminum alloy wire, comprising the following steps: S1, Melting and Composition Pre-adjustment: Weigh out the Ni-based furnace charge according to the target composition and melt it with other raw materials except Zr, B, and RE to obtain a melt. The Ni-based charge contains a reserved portion of Ni, which is used to compensate for the introduction of Ni into the intermediate alloy and / or as a cold material to help the melt enter the superheat window. S2, add intermediate alloy: After the melt composition is pre-adjusted, the melt temperature is lowered to the preset superheat window, and Zr, B, and RE are added to the melt in the form of intermediate alloys and stirred to homogenize. Then, the melt is poured to form an ingot. S3, Hot working: The ingot is forged and hot-rolled to obtain wire rod; S4, drawing and intermediate annealing: The wire rod is drawn in multiple passes, and an intermediate annealing is performed when the cumulative reduction rate reaches 70-90%. S5, Surface condition lock: After the intermediate annealing and / or final annealing, the wire is placed in a sealed protective environment and cooled to ≤80°C and then transferred to the composite boiling and washing step. The oxygen content of the protective environment is ≤1.0 vol% and / or the dew point is ≤-30°C, and the time from the end of annealing to entering the composite boiling and washing step is ≤60 min. S6, Composite Washing and Closed-Loop Control: After the surface condition is locked by S5, the wire is subjected to a composite boiling and washing process, and the contact resistance fluctuation value ΔR of the wire under standard conductive nozzle conditions is measured. When ΔR is greater than a preset threshold, at least one boiling and washing parameter is adjusted and the composite boiling and washing process is repeated until ΔR is not greater than the threshold. S7, Fine Pull: The wire is finely drawn to the target diameter to obtain a nickel-aluminum alloy wire.

[0007] Furthermore, the superheat window is 30-80°C above the liquidus line.

[0008] Furthermore, the intermediate alloy is Ni-Zr, Ni-B, or Ni-RE.

[0009] Furthermore, the reduction rate of the drawing single pass is 15-30%.

[0010] Furthermore, the intermediate annealing temperature is 680-820℃, held for 1-4 hours, and then cooled in a vacuum or protective atmosphere.

[0011] Furthermore, an intermediate annealing is performed when the cumulative reduction rate reaches 80%±5%.

[0012] Furthermore, the ΔR threshold is ≤7mΩ.

[0013] Furthermore, The composite boiling and washing process is a two-stage composite boiling and washing process, including the following steps: (1) Alkali boiling for defatting: The annealed wire was placed in an alkaline solution containing 20-80 g / L sodium hydroxide and treated at 50-75℃ for 5-20 minutes. (2) Rinsing: Rinse with running deionized water until the pH reaches 6-8; (3) Compound pickling to remove oxide scale: Place the wire in a compound pickling solution and treat it at 20-40℃ for 20-90 min; The compound pickling solution contains 5-15 wt% sulfuric acid, 1-8 wt% nitric acid, and 0.05-0.10 wt% hydrofluoric acid. (4) Ultrasound enhancement: During the pickling process, superimpose ultrasonic treatment at 20-40 kHz for 3-20 min; (5) Neutralization and drying: After pickling, rinse thoroughly with deionized water until the pH reaches 6-8, and then dry with hot air at 60-120℃. After completing the composite boiling and washing process, the contact resistance fluctuation value ΔR is measured. If ΔR is greater than a preset threshold, at least one boiling and washing parameter is adjusted and the composite boiling and washing process is repeated until ΔR is not greater than the threshold.

[0014] Furthermore, The adjustment of at least one boiling and washing parameter includes extending the alkaline boiling time and / or acid washing time, increasing the rinsing intensity, and increasing the ultrasonic treatment time.

[0015] The present invention has the following beneficial effects: (1) This invention provides a process for preparing nickel-aluminum alloy wire. In stage S1, the melting and composition pre-adjustment of the main alloying elements are completed first. In stage S2, the melt is cooled to a preset superheat window and then key trace elements such as Zr, B, and RE are added and homogenized. This process sequence of "pre-adjustment first, then addition at low superheat" reduces the oxidation, volatilization and burn-off of active trace elements at high temperature and high superheat, and reduces composition drift. On the other hand, it makes the hit rate and stability of the introduction of trace elements higher, thereby improving the repeatability between batches, and taking into account the yield of wire processing while ensuring the required reaction activity of the coating bonding layer.

[0016] (2) This invention provides a process for preparing nickel-aluminum alloy wire, and further adopts a synergistic strategy of "reserving Ni and adding Ni-based master alloys (Ni-Zr, Ni-B, Ni-RE) after the superheat window" to achieve efficient and low-loss introduction of active elements. Specifically, the reserved Ni in S1 is used for: firstly, to compensate for the Ni brought in by the master alloy to ensure the final composition hits; secondly, as a cold material to help the melt quickly enter the superheat window, so that the melt is in a low superheat state when the master alloy is added in S2. This can significantly reduce the oxidation / burn-off and secondary inclusion formation probability of active elements such as Zr, B, and RE, suppress the inclusions such as coarse oxides / sulfides from becoming crack sources, improve the uniformity of microstructure and composition, and thus improve the subsequent drawing stability and yield.

[0017] (3) The present invention provides a process for preparing nickel-aluminum alloy wire. In the “drawing-intermediate annealing” process, the intermediate annealing is set when the cumulative reduction rate reaches 70-90% (preferably 80%±5%), and the single-pass reduction rate is limited to 15-30% and the intermediate annealing temperature is limited, so that the microstructure and stress state under high cumulative deformation can be regenerated in a controllable manner; and production efficiency and batch consistency are taken into account.

[0018] (4) This invention provides a process for preparing nickel-aluminum alloy wire. This invention constructs a quantifiable process control system for arc stabilization through "surface state locking and composite boiling and washing ΔR closed-loop control", which suppresses the fluctuation of wire feeding contact resistance from the source. First, after intermediate annealing and / or final annealing, the wire is placed in a closed environment with low oxygen and / or low dew point for controlled cooling and then transferred to the composite boiling and washing step, which can significantly reduce re-oxidation, moisture absorption and re-adsorption of contaminants after annealing, and maintain the consistency of surface state. Second, the composite boiling and washing adopts alkaline boiling degreasing + compound acid washing to remove oxide scale and superimposed ultrasonic strengthening. While effectively removing oil stains, oxide film and particulate contaminants, the risk of pitting caused by over-acid washing is reduced by parameter control. Third, the contact resistance fluctuation value ΔR is measured under standard conductive tip conditions, and a closed-loop parameter adjustment mechanism is established with ΔR≤7mΩ as the release threshold, which transforms "surface cleanliness / oxide film state / roughness difference" into quantifiable control variables. This can significantly improve the arc initiation success rate, reduce deposition efficiency fluctuations, and ultimately reduce coating porosity, improve appearance uniformity, and stabilize and improve bonding strength and its dispersion. Detailed Implementation

[0019] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0020] The purpose of this invention is to develop a manufacturing process for nickel-aluminum alloy wire to solve the problems of uneven dispersion and easy burn-off of active trace elements (RE / Zr / B) during the existing nickel-aluminum alloy wire manufacturing process, decreased yield under high reduction ratio drawing conditions, and unstable arc ignition due to surface defects / re-oxidation causing contact resistance fluctuations. The approach is as follows: considering that the root causes of the above problems are the burn-off and inclusion of active elements during the high-temperature holding period in the smelting stage, the uneven enrichment of trace elements due to solidification segregation; the accumulation of work hardening and microcrack propagation caused by high cumulative deformation during drawing; and the amplification of randomness in the electrical contact boundary caused by rapid re-oxidation and contamination adsorption on the hot surface after annealing. To address this, this process involves pre-adjusting the composition during the smelting stage and reserving Ni to compensate for the introduction of Ni into the intermediate alloy and to act as a cold material for fine-tuning, allowing the melt to enter the superheat window. Ni-based intermediate alloys are added in batches within a window of 30-80°C above the liquidus, followed by stirring and homogenization / slag removal to reduce burn-off and segregation, and refine inclusions. A single intermediate annealing is performed to reset work hardening, restore plasticity, and compress defect sources when the cumulative surface area reduction reaches approximately 80%. Subsequently, the surface state after annealing is locked under low-oxygen / low-dew-point closed-loop cooling and time-limited transport conditions to suppress re-oxidation. Finally, a composite boiling and washing closed-loop correction is implemented using the contact resistance fluctuation value ΔR as a criterion, ultimately obtaining a nickel-aluminum alloy wire with high yield, stable electrical contact, and reliable arc initiation. Examples of this invention are as follows: This invention provides a process for preparing nickel-aluminum alloy wire, comprising the following steps: S1, Melting and Composition Pre-adjustment: Weigh out the Ni-based furnace charge and other raw materials except Zr, B, and RE according to the target composition, and add them together to a vacuum induction furnace for melting: evacuate to ≤5×10⁻ 3 After Pa, high-purity Ar is reintroduced to 0.02-0.06 MPa as a protective atmosphere. The temperature is then raised to 1500-1550℃ and held for 5-15 minutes, while electromagnetic stirring is performed for 2-8 minutes to promote compositional homogeneity. After melting, a compositional pre-adjustment is performed to obtain a stable melt. The Ni-based charge contains a reserved portion of Ni, which is used to compensate for the introduction of Ni into the intermediate alloy and / or as a cold material to assist the melt in entering the superheat window.

[0021] The amount of reserved Ni is mainly used for compensation, and secondarily for cold material temperature control; the amount of compensation added is 1-10% of the final Ni added; the total amount of cold material added does not exceed 1-3% of the melt mass.

[0022] S2, add intermediate alloy: After the melt composition is pre-adjusted, it is allowed to cool naturally under conditions of stopped heating / reduced power, with a small amount of reserved Ni used for fine-tuning the temperature to enter the preset superheat window. Subsequently, within the superheat window, intermediate alloys are added in 2-5 batches and stirred continuously for 2-10 minutes to ensure complete dissolution and homogenization. After that, it is allowed to stand for 1-3 minutes to remove slag / float inclusions, and finally, it is poured under a protective atmosphere to form an ingot. The pouring temperature is 30-70°C above the liquidus. The pouring process is kept stable. After the ingot is removed from the furnace, risers are removed and the surface is cleaned.

[0023] The superheat window is 30-80°C above the liquidus line.

[0024] The intermediate alloys are Ni-Zr, Ni-B, and Ni-RE.

[0025] The amount of intermediate alloy added can be determined by back-calculating the target element's mass fraction and the mass fraction of that element in the intermediate alloy; the mass of Ni introduced along with the intermediate alloy is included in the final Ni matrix content. The Ni mass reserved in stage S1 can be determined as "target Ni mass - Ni mass introduced by each intermediate alloy" to reduce the final composition deviation. When the reserved Ni is added as cold material, it can be added in 1-5 batches, with the amount added in each batch ≤ 0.3-0.8% of the melt mass, to avoid local overcooling leading to solidified shells or inclusions.

[0026] S3, Hot working: The ingot is heated to 1000-1120℃ and held for 0.5-2 hours before being forged into a billet. The forging ratio is 2.0-3.5, the final forging temperature is 980-1030℃, and the total forging ratio is 4.0-6.5. After forging, it is held at 850-950℃ for 0.5-2 hours. Subsequently, the forged billet is reheated to the hot rolling starting temperature and hot rolled at 980-1060℃ and 850-930℃ to obtain a wire rod with a uniform structure. The preferred wire rod diameter is Φ5.5-10.0mm. The wire rod is then straightened, surface cleaned, or lightly peeled to reduce surface defect sources.

[0027] S4, drawing and intermediate annealing: Intermediate wire rods are obtained by multi-pass drawing of the wire rod. A multi-pass continuous drawing machine is used, with a preferred linear speed of 0.5-3.0 m / s. The lubrication system can use a paraffin-based carrier combined with a solid lubricating phase (graphite / molybdenum disulfide) to maintain clean and stable lubrication supply. During the drawing process, an intermediate annealing is performed when the cumulative area reduction reaches 70-90% to release work hardening, promote recrystallization, and homogenize the microstructure. After intermediate annealing, drawing can continue to an intermediate specification close to the target wire diameter, providing a stable substrate state for subsequent surface treatment and precision drawing.

[0028] The single-pass drawing reduction rate is 15-30%.

[0029] Intermediate annealing is performed when the cumulative area reduction reaches 80% ± 5%. When the cumulative area reduction is close to 80%, the material has sufficient deformation energy storage. Intermediate annealing can more effectively trigger recrystallization and microstructure homogenization, and significantly release residual stress, thereby suppressing brittleness and wire breakage caused by accumulated work hardening. At the same time, under the above annealing window, plasticity can be restored to avoid excessive grain coarsening, improving the continuous stability and yield of subsequent fine drawing. Due to the improved wire microstructure homogenization and the compression of surface defect sources, the wire feeding friction and contact state are more consistent, and the fluctuations in the spraying arc initiation and deposition process are reduced. This can indirectly lead to the improvement of porosity and bonding strength dispersion, while taking into account production efficiency and batch consistency.

[0030] The intermediate annealing temperature is 680-820℃, held for 1-4 hours, and then cooled in a vacuum or protective atmosphere.

[0031] S5, Surface condition lock: After the intermediate and / or final annealing, the wire is placed in a sealed protective environment for controlled cooling to ≤80°C, and then transferred to the composite washing step within ≤60 minutes after annealing. The controlled cooling is carried out in a slow cooling chamber, and the controlled cooling time is included within the aforementioned ≤60 minutes; the protective environment meets the requirements of oxygen content ≤1.0 vol% and / or dew point ≤-30°C, and the protection method adopts a slow cooling chamber for annealing furnace discharge with an inert atmosphere of Ar, and the wire is immediately sealed and transferred after discharge from the furnace.

[0032] This surface state locking step is used to suppress rapid re-oxidation and contaminant adsorption on the hot surface after annealing, reduce the randomness of subsequent contact resistance fluctuations of the conductive nozzle, and make the composite boiling and washing process more controllable and consistent.

[0033] S6, Composite Washing and Closed-Loop Control: After the surface condition is locked by S5, the wire is subjected to a composite boiling wash, and the contact resistance fluctuation value ΔR of the wire under standard conductive nozzle conditions is measured. When ΔR is greater than a preset threshold, at least one boiling wash parameter is adjusted and the composite boiling wash is repeated until ΔR is not greater than the threshold.

[0034] The ΔR threshold is ≤7mΩ.

[0035] The determination of contact resistance fluctuation value ΔR was performed using a contact resistance tester. The wire was trimmed to Φ2.0mm and clamped in a copper conductive nozzle. The inner diameter of the nozzle was +0.03-0.08mm of the finished wire diameter, and its length was 20mm. The clamping pressure was 30N. A constant test current of 10A was applied, and the wire feeding speed was 3m / min. The real-time contact resistance curve was collected within a 10s sampling window. ΔR was defined as the difference between the maximum and minimum resistance values ​​within this window. Each sample was tested at least 5 times, and the average value was taken. The test environment was 25±2℃ and the relative humidity was ≤60%.

[0036] The composite boiling and washing process is a two-stage composite boiling and washing process, including the following steps: (1) Alkali boiling degreasing: The annealed wire is placed in an alkaline boiling solution containing 20-80 g / L sodium hydroxide and treated at 50-75℃ for 5-20 min to remove drawing lubricant residue and organic contamination; (2) Rinse: Rinse with running deionized water until the pH is 6-8; (3) Compound pickling to remove oxide scale: Place the wire in the compound pickling solution and treat at 20-40℃ for 20-90 min; The compound pickling solution contains 5-15 wt% sulfuric acid, 1-8 wt% nitric acid and 0.05-0.10 wt% hydrofluoric acid, and is used to remove annealed oxide scale and form a cleaner and more uniform metal surface. (4) Ultrasonic enhancement: During the pickling process, superimpose 20-40kHz ultrasound for 3-20 minutes to improve the uniformity of film removal and reduce local residual film; (5) Neutralization and drying: After pickling, rinse thoroughly with deionized water until the pH is 6-8, and dry with hot air at 60-120℃; After completing the composite boiling and washing process, the contact resistance fluctuation value ΔR is measured. If ΔR is greater than a preset threshold, at least one boiling and washing parameter is adjusted and the composite boiling and washing process is repeated until ΔR is not greater than the threshold.

[0037] The adjustment of at least one boiling and washing parameter includes extending the alkaline boiling time and / or acid washing time, increasing the rinsing intensity, and increasing the ultrasonic treatment time.

[0038] When ΔR exceeds the threshold, the composite boiling and washing process should preferably be performed by adjusting parameters in the following order: "strengthening rinsing - increasing ultrasonication - extending acid / alkali boiling time". Each adjustment should preferably be 10-30% of the original parameters or an increase of 2-5 minutes in ultrasonic time. To balance the adequacy of film removal with the risk of over-corrosion, the composite boiling and washing process should preferably not be repeated more than 3 times. If the results are still unsatisfactory, the batch of wires can be identified as having an abnormal defect source and should be reworked or scrapped.

[0039] S7, Fine Pull: The wire that has passed the composite washing and cleaning process is then precision drawn to the target diameter to obtain nickel-aluminum based alloy wire. Precision drawing can be performed using a single crystal die or a high crystal die, with a final pass area reduction rate preferably of 5-15%, while maintaining a clean and stable lubrication system. The target diameter of the finished wire can be Φ1.6-2.0mm. After precision drawing, straightening, winding, and finished product inspection are carried out.

[0040] Finished product inspection includes at least appearance defects (scratches, pits, dents) and ΔR re-inspection or random sampling under standard conductive tip conditions to ensure subsequent arc initiation success rate, porosity, and bonding strength dispersion.

[0041] The present invention discloses a process for preparing a nickel-aluminum alloy wire. The raw material formulation for the nickel-aluminum alloy wire, by mass percentage, comprises: Al 3.0-5.8%, Ti 0.8-1.0%, RE 0.05-0.20%, Fe 0.15-0.35%, Mn 0.15-0.25%, Si 0.02-0.5%, Zr 0.02-0.08%, B 0.003-0.015%, with the balance being Ni and unavoidable impurities. The total impurity content is ≤0.1%, and S≤0.01% and P≤0.01%. Furthermore, the formulation used in the following embodiments comprises, by mass percentage: Al 4.4%, Ti 0.9%, RE 0.12%, Fe 0.25%, Mn 0.20%, Si 0.2%, Zr 0.05%, B 0.01%, with the balance being Ni and unavoidable impurities.

[0042] To further understand the present invention, the preparation process of the nickel-aluminum alloy wire provided by the present invention will be described in detail below with reference to specific embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0043] Example 1 A process for preparing a nickel-aluminum alloy wire includes the following steps: S1, Melting and Composition Pre-adjustment: Weigh out the Ni-based furnace charge and other raw materials except Zr, B, and RE according to the target composition, and add them together to a vacuum induction furnace for melting: evacuate to 4×10⁻ 3 After Pa, high-purity Ar is reintroduced to 0.04 MPa as a protective atmosphere, and the temperature is raised to 1530℃ and held for 10 min, while electromagnetic stirring is performed for 6 min to promote compositional homogeneity. After melting, a compositional pre-adjustment is performed to obtain a stable melt. The Ni-based furnace charge contains a reserved portion of Ni; the amount of the reserved Ni is mainly used for compensation, and secondarily for cold material temperature control; the compensation amount is 5% of the final Ni added; the total amount of cold material added is 2% of the melt mass.

[0044] S2, add intermediate alloy: After the melt composition is pre-adjusted, it is naturally cooled and supplemented with a reserved Ni fine-tuning temperature to enter the preset superheat window. Then, the intermediate alloy is added in four batches within the superheat window and stirred continuously for 6 minutes to ensure it is fully dissolved and homogenized. After that, it is allowed to stand for 3 minutes to remove slag / float inclusions. Finally, it is poured under a protective atmosphere to form an ingot. The pouring temperature is 50°C above the liquidus. The pouring process is kept stable. After the ingot is removed from the furnace, the risers are removed and the surface is cleaned.

[0045] The superheat window is 55°C above the liquidus line.

[0046] The intermediate alloys are Ni-Zr, Ni-B, and Ni-RE.

[0047] S3, Hot working: The ingot was heated to 1060℃ and held for 1 hour before being forged into a billet with a forging ratio of 3.0, a final forging temperature of 1010℃, and a total forging ratio of 5.5. After forging, it was held at 900℃ for 1 hour. Subsequently, the billet was reheated to the hot rolling starting temperature and hot rolled at 1020℃ and a final rolling temperature of 900℃ to obtain a wire rod with a uniform structure. The wire rod had a diameter of Φ8.0mm and was straightened, surface cleaned, or lightly peeled to reduce surface defect sources.

[0048] S4, drawing and intermediate annealing: Intermediate wire rod is obtained by multi-pass drawing of the wire rod. The drawing process uses a multi-pass continuous drawing machine at a linear speed of 2.0 m / s. The lubrication system employs a paraffin-based carrier combined with a solid lubricating phase (graphite / molybdenum disulfide) to maintain cleanliness and a stable supply of lubricant. During the drawing process, an intermediate annealing is performed when the cumulative area reduction reaches 80%. After intermediate annealing, drawing can continue to an intermediate specification close to the target wire diameter, providing a stable substrate condition for subsequent surface treatment and precision drawing.

[0049] The single-pass reduction rate of the drawing is 25%.

[0050] The intermediate annealing temperature is 750°C, held for 2.5 hours, and then cooled in a vacuum or protective atmosphere.

[0051] S5, Surface condition lock: After the intermediate and / or final annealing, the wire is placed in a sealed protective environment and cooled to ≤80°C, and then transferred to the composite washing step within ≤60 minutes after annealing. The protective environment meets the requirements of oxygen content ≤1.0 vol% and dew point ≤-30°C. The protection method adopts a slow cooling chamber at the discharge of the annealing furnace with an inert atmosphere of Ar, and the wire is immediately sealed and transferred after exiting the furnace.

[0052] S6, Composite Washing and Closed-Loop Control: After the surface condition is locked by S5, the wire is subjected to a composite boiling wash, and the contact resistance fluctuation value ΔR of the wire under standard conductive nozzle conditions is measured. When ΔR is greater than a preset threshold, at least one boiling wash parameter is adjusted and the composite boiling wash is repeated until ΔR is not greater than the threshold.

[0053] The ΔR threshold is ≤7mΩ.

[0054] The composite boiling and washing process is a two-stage composite boiling and washing process, including the following steps: (1) Alkali boiling degreasing: The annealed wire was placed in an alkaline boiling solution containing 50 g / L sodium hydroxide and treated at 65°C for 10 min; (2) Rinse: Rinse with running deionized water until pH 7; (3) Compound pickling to remove oxide scale: Place the wire in the compound pickling solution and treat at 30°C for 60 min; The compound pickling solution contains 10 wt% sulfuric acid, 4 wt% nitric acid, and 0.07 wt% hydrofluoric acid. (4) Ultrasonic enhancement: Superimpose 30kHz ultrasound for 10 minutes during the pickling process; (5) Neutralization and drying: After acid washing, rinse thoroughly with deionized water until the pH is 7, and dry with hot air at 90℃; After completing the composite boiling and washing process, the contact resistance fluctuation value ΔR is measured. If ΔR is greater than a preset threshold, at least one boiling and washing parameter is adjusted and the composite boiling and washing process is repeated until ΔR is not greater than the threshold.

[0055] S7, Fine Pull: The wire that has passed the composite washing and cleaning process is then precision drawn to the target diameter to obtain nickel-aluminum based alloy wire. Precision drawing can be performed using a single crystal die, with a final pass area reduction of 10%, while maintaining a clean and stable lubrication system. The target diameter of the finished wire can be Φ2.0mm. After precision drawing, straightening, winding, and finished product inspection are carried out.

[0056] Example 2 A process for preparing a nickel-aluminum alloy wire includes the following steps: S1, Melting and Composition Pre-adjustment: Weigh out the Ni-based furnace charge and other raw materials except Zr, B, and RE according to the target composition, and add them together to a vacuum induction furnace for melting: evacuate to 5×10⁻ 3 After Pa, high-purity Ar is recharged to 0.02 MPa as a protective atmosphere, and the temperature is raised to 1500℃ and held for 15 min, while electromagnetic stirring is performed for 8 min to promote compositional homogeneity. After melting, a compositional pre-adjustment is performed to obtain a stable melt. The Ni-based furnace charge contains a reserved portion of Ni; the amount of the reserved Ni is mainly used for compensation, and secondarily for cold material temperature control; the compensation amount is 2% of the final Ni added; the total amount of cold material added is 1% of the melt mass.

[0057] S2, add intermediate alloy: After the melt composition is pre-adjusted, it is naturally cooled and supplemented with a reserved Ni fine-tuning temperature to enter the preset superheat window. Then, the intermediate alloy is added in two batches within the superheat window and stirred continuously for 2 minutes to ensure it is fully dissolved and homogenized. After that, it is allowed to stand for 3 minutes to remove slag / float inclusions. Finally, it is poured under a protective atmosphere to form an ingot. The pouring temperature is 30°C above the liquidus. The pouring process is kept stable. After the ingot is removed from the furnace, the risers are removed and the surface is cleaned.

[0058] The superheat window is 30°C above the liquidus line.

[0059] The intermediate alloys are Ni-Zr, Ni-B, and Ni-RE.

[0060] S3, Hot working: The ingot was heated to 1000℃ and held for 2 hours before being forged into a billet with a forging ratio of 3.5, a final forging temperature of 980℃, and a total forging ratio of 6.5. After forging, it was held at 850℃ for 2 hours. Subsequently, the billet was reheated to the hot rolling starting temperature and hot rolled at 1060℃ and a final rolling temperature of 930℃ to obtain a wire rod with a uniform microstructure. The wire rod had a diameter of Φ10.0mm and was straightened, surface cleaned, or lightly peeled to reduce surface defect sources.

[0061] S4, drawing and intermediate annealing: Intermediate wire rods are obtained by multi-pass drawing. The drawing process uses a multi-pass continuous drawing machine at a linear speed of 2.0 m / s. The lubrication system employs a paraffin-based carrier combined with a solid lubricating phase (graphite / molybdenum disulfide) to maintain cleanliness and a stable supply of lubricant. During the drawing process, an intermediate annealing is performed when the cumulative area reduction reaches 85%. After intermediate annealing, drawing can continue to an intermediate specification close to the target wire diameter, providing a stable substrate condition for subsequent surface treatment and precision drawing.

[0062] The single-pass drawing reduction rate is 30%.

[0063] The intermediate annealing temperature is 820°C, held for 1 hour, and then cooled in a vacuum or protective atmosphere.

[0064] S5, Surface condition lock: After the intermediate and / or final annealing, the wire is placed in a sealed protective environment and cooled to ≤80°C, and then transferred to the composite washing step within ≤60 minutes after annealing. The protective environment meets the requirements of oxygen content ≤1.0 vol% and dew point ≤-30°C. The protection method adopts a slow cooling chamber at the discharge of the annealing furnace with an inert atmosphere of Ar, and the wire is immediately sealed and transferred after exiting the furnace.

[0065] S6, Composite Washing and Closed-Loop Control: After the surface condition is locked by S5, the wire is subjected to a composite boiling wash, and the contact resistance fluctuation value ΔR of the wire under standard conductive nozzle conditions is measured. When ΔR is greater than a preset threshold, at least one boiling wash parameter is adjusted and the composite boiling wash is repeated until ΔR is not greater than the threshold.

[0066] The ΔR threshold is ≤7mΩ.

[0067] The composite boiling and washing process is a two-stage composite boiling and washing process, including the following steps: (1) Alkali boiling degreasing: The annealed wire was placed in an alkaline boiling solution containing 20 g / L sodium hydroxide and treated at 75°C for 5 min; (2) Rinse: Rinse with running deionized water until pH 7; (3) Compound pickling to remove oxide scale: Place the wire in the compound pickling solution and treat at 40℃ for 20 min; The compound pickling solution contains 5 wt% sulfuric acid, 8 wt% nitric acid, and 0.05 wt% hydrofluoric acid. (4) Ultrasonic enhancement: 40kHz ultrasound is superimposed on the pickling process for 3 minutes; (5) Neutralization and drying: After acid washing, rinse thoroughly with deionized water until the pH is 7, and dry with hot air at 60℃; After completing the composite boiling and washing process, the contact resistance fluctuation value ΔR is measured. If ΔR is greater than a preset threshold, at least one boiling and washing parameter is adjusted and the composite boiling and washing process is repeated until ΔR is not greater than the threshold.

[0068] S7, Fine Pull: The wire that has passed the composite washing and cleaning process is then precision drawn to the target diameter to obtain nickel-aluminum based alloy wire. Precision drawing can be performed using a single crystal die, with a final pass area reduction of 10%, while maintaining a clean and stable lubrication system. The target diameter of the finished wire can be Φ2.0mm. After precision drawing, straightening, winding, and finished product inspection are carried out.

[0069] Example 3 A process for preparing a nickel-aluminum alloy wire includes the following steps: S1, Melting and Composition Pre-adjustment: Weigh out the Ni-based furnace charge and other raw materials except Zr, B, and RE according to the target composition, and add them together to a vacuum induction furnace for melting: evacuate to 5×10⁻ 3 After Pa, high-purity Ar is reintroduced to 0.06 MPa as a protective atmosphere, and the temperature is raised to 1550℃ and held for 5 minutes, while electromagnetic stirring is performed for 2 minutes to promote compositional homogeneity. After melting, a compositional pre-adjustment is performed to obtain a stable melt. The Ni-based furnace charge contains a reserved portion of Ni; the amount of the reserved Ni is mainly used for compensation, and secondarily for cold material temperature control; the compensation amount is 10% of the final Ni added; the total amount of cold material added is 3% of the melt mass.

[0070] S2, add intermediate alloy: After the melt composition is pre-adjusted, it is naturally cooled and supplemented with a reserved Ni fine-tuning temperature to enter the preset superheat window. Then, within the superheat window, the intermediate alloy is added in 5 batches and stirred continuously for 10 minutes to fully dissolve and homogenize it. After that, it is allowed to stand for 3 minutes to remove slag / float inclusions. Finally, it is poured under a protective atmosphere to form an ingot. The pouring temperature is 70°C above the liquidus. The pouring process is kept stable. After the ingot is removed from the furnace, the risers are removed and the surface is cleaned.

[0071] The superheat window is 80°C above the liquidus line.

[0072] The intermediate alloys are Ni-Zr, Ni-B, and Ni-RE.

[0073] S3, Hot working: The ingot was heated to 1120℃ and held for 0.5 hours before being forged into a billet with a forging ratio of 2.0, a final forging temperature of 1030℃, and a total forging ratio of 4.0. After forging, it was held at 950℃ for 0.5 hours. Subsequently, the forged billet was reheated to the hot rolling starting temperature and hot rolled at 980℃ and 850℃ to obtain a wire rod with a uniform microstructure. The wire rod had a diameter of Φ5.5mm and was straightened, surface cleaned, or lightly peeled to reduce surface defect sources.

[0074] S4, drawing and intermediate annealing: Intermediate wire rods are obtained by multi-pass drawing. The drawing process uses a multi-pass continuous drawing machine at a linear speed of 2.0 m / s. The lubrication system employs a paraffin-based carrier combined with a solid lubricating phase (graphite / molybdenum disulfide) to maintain cleanliness and a stable supply of lubricant. During the drawing process, an intermediate annealing is performed when the cumulative area reduction reaches 75%. After intermediate annealing, drawing can continue to an intermediate specification close to the target wire diameter, providing a stable substrate condition for subsequent surface treatment and precision drawing.

[0075] The single-pass drawing reduction rate is 15%.

[0076] The intermediate annealing temperature is 680℃, held for 4 hours, and then cooled in a vacuum or protective atmosphere.

[0077] S5, Surface condition lock: After the intermediate and / or final annealing, the wire is placed in a sealed protective environment and cooled to ≤80°C, and then transferred to the composite washing step within ≤60 minutes after annealing. The protective environment meets the requirements of oxygen content ≤1.0 vol% and dew point ≤-30°C. The protection method adopts a slow cooling chamber at the discharge of the annealing furnace with an inert atmosphere of Ar, and the wire is immediately sealed and transferred after exiting the furnace.

[0078] S6, Composite Washing and Closed-Loop Control: After the surface condition is locked by S5, the wire is subjected to a composite boiling wash, and the contact resistance fluctuation value ΔR of the wire under standard conductive nozzle conditions is measured. When ΔR is greater than a preset threshold, at least one boiling wash parameter is adjusted and the composite boiling wash is repeated until ΔR is not greater than the threshold.

[0079] The ΔR threshold is ≤7mΩ.

[0080] The composite boiling and washing process is a two-stage composite boiling and washing process, including the following steps: (1) Alkali boiling degreasing: The annealed wire was placed in an alkaline boiling solution containing 80 g / L sodium hydroxide and treated at 50°C for 20 min; (2) Rinse: Rinse with running deionized water until pH 8; (3) Compound pickling to remove oxide scale: Place the wire in the compound pickling solution and treat at 20°C for 90 min; The compound pickling solution contains 15 wt% sulfuric acid, 1 wt% nitric acid, and 0.10 wt% hydrofluoric acid. (4) Ultrasonic enhancement: 20kHz ultrasound is superimposed on the pickling process for 20min; (5) Neutralization and drying: After acid washing, rinse thoroughly with deionized water until the pH is 6, and dry with hot air at 120℃; After completing the composite boiling and washing process, the contact resistance fluctuation value ΔR is measured. If ΔR is greater than a preset threshold, at least one boiling and washing parameter is adjusted and the composite boiling and washing process is repeated until ΔR is not greater than the threshold.

[0081] S7, Fine Pull: The wire that has passed the composite washing and cleaning process is then precision drawn to the target diameter to obtain nickel-aluminum based alloy wire. Precision drawing can be performed using a single crystal die, with a final pass area reduction of 10%, while maintaining a clean and stable lubrication system. The target diameter of the finished wire can be Φ2.0mm. After precision drawing, straightening, winding, and finished product inspection are carried out.

[0082] Example 4 Everything else is the same as in Example 1, except that: A process for preparing nickel-aluminum alloy wire, wherein an intermediate annealing is performed when the cumulative reduction in surface area reaches 70%.

[0083] Example 5 Everything else is the same as in Example 1, except that: A process for preparing nickel-aluminum alloy wire, wherein an intermediate annealing is performed when the cumulative reduction in surface area reaches 90%.

[0084] The following comparative examples are all compared with Example 1: Comparative Example 1 The rest is the same as in Example 1, except that: a preparation process for a nickel-aluminum alloy wire, wherein in S1, Zr / B / RE is added to a vacuum induction furnace in pure element form and melted at once.

[0085] Comparative Example 2 The rest is the same as in Example 1, except that: in a process for preparing a nickel-aluminum alloy wire, the amount of reserved Ni is 0% of the final amount of Ni added; that is, no Ni is reserved.

[0086] Implement Comparative Example 3 The process is the same as in Example 1, except that: a nickel-aluminum alloy wire preparation process is used, wherein an intermediate annealing is performed when the cumulative reduction rate reaches 50%.

[0087] Comparative Example 4 The process is the same as in Example 1, except that: a nickel-aluminum alloy wire preparation process is used, wherein an intermediate annealing is performed when the cumulative surface reduction rate reaches 95%.

[0088] Comparative Example 5 The process is the same as in Example 1, except that in the preparation process of the nickel-aluminum alloy wire, step S6 involves only one composite boiling and washing, without closed-loop monitoring of the contact resistance fluctuation value ΔR. The next step is performed after the boiling and washing is completed.

[0089] Comparative Example 6 The process is the same as in Example 1, except that the preparation process of a nickel-aluminum alloy wire does not include step S5.

[0090] The alloy wires in the above embodiments and comparative examples were used to prepare the metal substrate bonding layer by arc spraying. The specific steps are as follows: Preprocessing: The substrate was a Q235 carbon steel test plate (100mm×100mm×8mm); after degreasing and oil removal with acetone, and roughening by sandblasting with 60-mesh white corundum (sandblasting pressure 0.5MPa, sandblasting angle 45°, sandblasting distance 150mm), the surface roughness Ra of the substrate was 10-15μm. After drying, it was immediately sprayed.

[0091] Arc spraying application: The equipment is a dual-wire electric arc spray gun (air atomization). Parameters: current 220A; voltage 30V; atomizing gas: compressed air 0.60MPa; spraying distance 160mm; gun speed 0.5m / s; overlap rate 30-50%; target coating thickness: 200-300μm.

[0092] Post-processing: Let it cool naturally to room temperature.

[0093] The physical properties of the nickel-aluminum alloy wires prepared in the embodiments and comparative examples of the present invention were measured respectively, and the results are shown in Table 1.

[0094] Table 1 Physical test performance of each embodiment As can be observed from Examples 1-5, the preparation process of the nickel-aluminum alloy wire of the present invention exhibits stable advantages in core indicators: high yield (93.6-96.7%), low contact resistance fluctuation ΔR (3-6mΩ), high arc initiation success rate (96-99%), low coating porosity (1.2-1.6%), and high bonding strength with small dispersion (56-61MPa / 5-7%). This indicates that the combined process of "batch replenishment of intermediate alloy within the superheat window, reserved Ni compensation / cold material micro-temperature control, intermediate annealing window control, surface state locking, and ΔR closed-loop composite boiling and washing" can simultaneously improve the processing yield and coating consistency, especially significantly reducing wire feeding electrical contact fluctuation and improving arc initiation reliability.

[0095] As can be seen from Examples 1 and 4-5, annealing with a cumulative reduction in surface area of ​​70% (Example 4) results in insufficient deformation energy storage, inadequate recrystallization, and insufficient microstructure homogenization, leading to larger ΔR and dispersion. Annealing with a cumulative reduction in surface area of ​​90% (Example 5) results in excessive accumulation of work hardening and surface damage, leading to a decrease in yield, an increase in ΔR, and consequently, an increase in porosity and a decrease in bond strength. Setting the intermediate annealing at 80% ± 5% is more conducive to achieving a balance between "sufficient recrystallization - avoiding coarsening - compressing defect sources - stabilizing subsequent fine drawing".

[0096] As can be seen from Comparative Examples 1-6, key process characteristics have a direct impact on performance: The one-time addition of pure elements (Comparative Example 1) easily leads to the burn-off of reactive elements, significantly increases the risk of inclusions / segregation and coarse compounds, resulting in a sharp decrease in yield, an increase in ΔR, and a significant deterioration in arc initiation, porosity, bonding strength, and dispersion; The lack of pre-reserved Ni (Comparative Example 2) makes it impossible to meterly compensate for the introduction of Ni into the intermediate alloy, and also lacks a "soft temperature control" method for fine-tuning the cold material into the superheat window. Composition and temperature deviations are more easily amplified, resulting in decreased yield, higher ΔR, increased porosity, and increased dispersion; with a cumulative area reduction of 50... % annealing (Comparative Example 3) results in insufficient microstructure homogenization and ineffective compression of surface / near-surface defects, leading to a high ΔR, worsening of arc initiation, porosity, and dispersion, and a low yield. 95% cumulative surface area reduction annealing (Comparative Example 4) results in excessive hardening and damage accumulation, with annealing lagging in "stopping" defects, further reducing the yield, increasing porosity, and worsening bonding strength and dispersion. Without ΔR closure (Comparative Example 5), it is impossible to correct residual film / contamination fluctuations, resulting in a significant increase in ΔR and leading to arc initiation failure, increased porosity, and amplified dispersion. Without surface state locking (Comparative Example 6), the randomness of re-oxidation after annealing increases, and the controllability of subsequent cleaning decreases.

[0097] In summary, this invention revolves around a complete process route design of "controlled melt composition / inclusions - microstructure homogenization window - post-annealing oxidation suppression - ΔR-quantified closed-loop correction", achieving a synergistic improvement in yield, arc stability, and coating density / low dispersion.

[0098] The testing method is as follows: (1) Yield: Under the same original wire rod specifications, the same target wire diameter, and the same drawing-annealing-surface treatment process route, the proportion of finished wire length that can be continuously completed to the target wire diameter and meet the electrical contact stability requirements for subsequent spraying to the total length of wire rod input. The calculation formula is: Yield (%) = Qualified finished wire (L) / Total wire rod input (L) × 100%. Among them, the determination of qualified finished wire must simultaneously meet the following conditions: i) Geometry and appearance: The wire diameter meets the target wire diameter tolerance requirements, and the surface is free of defects that affect the stability of wire feeding and electrical contact (including: continuous scratches, cracks, pits / dents, peeling to expose the base material, and residual oxide scale). ii) Continuous production without interruption: No abnormalities occurred during the drawing process to the target wire diameter that would render the wire section unusable (including: wire breakage, severe die sticking / scratching, bundle tearing). If wire breakage occurs, only the length of wire that is rejoined and meets the requirements after the breakage point will be counted.

[0099] (3) Arc spraying arc ignition success rate: Under the above standard spraying parameters, the arc is continuously ignited 100 times, and the number of successful arc ignitions / total number of arc ignitions × 100% is recorded. The criteria for successful arc ignition are: a continuous arc is formed within 1.0s after triggering for ≥3s and there is no continuous arc break.

[0100] (4) Improvement of coating porosity: The cross-section of the coating was observed using a metallographic microscope (magnification 500x). Ten fields of view were randomly selected, and the proportion of pore area was statistically analyzed using image analysis method. The average value was then taken.

[0101] (5) Coating bonding strength and dispersion: The tensile bonding strength of thermal spray coatings was determined by the pull-out method according to GB / T 8642-2023 "Determination of tensile bonding strength of thermal spray coating".

[0102] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A process for preparing nickel-aluminum alloy wire, characterized in that: Includes the following steps: S1, Melting and Composition Pre-adjustment: Weigh out the Ni-based furnace charge according to the target composition and melt it with other raw materials except Zr, B, and RE to obtain a melt. The Ni-based charge contains a reserved portion of Ni, which is used to compensate for the introduction of Ni into the intermediate alloy and / or as a cold material to help the melt enter the superheat window. S2, add intermediate alloy: After the melt composition is pre-adjusted, the melt temperature is lowered to the preset superheat window, and Zr, B, and RE are added to the melt in the form of intermediate alloys and stirred to homogenize. Then, the melt is poured to form an ingot. S3, Hot working: The ingot is forged and hot-rolled to obtain wire rod; S4, drawing and intermediate annealing: The wire rod is drawn in multiple passes, and an intermediate annealing is performed when the cumulative reduction rate reaches 70-90%. S5, Surface condition lock: After the intermediate annealing and / or final annealing, the wire is placed in a sealed protective environment and cooled to ≤80°C and then transferred to the composite boiling and washing step. The oxygen content of the protective environment is ≤1.0 vol% and / or the dew point is ≤-30°C, and the time from the end of annealing to entering the composite boiling and washing step is ≤60 min. S6, Composite Washing and Closed-Loop Control: After the surface condition is locked by S5, the wire is subjected to a composite boiling and washing process, and the contact resistance fluctuation value ΔR of the wire under standard conductive nozzle conditions is measured. When ΔR is greater than a preset threshold, at least one boiling and washing parameter is adjusted and the composite boiling and washing process is repeated until ΔR is not greater than the threshold. S7, Fine Pull: The wire is finely drawn to the target diameter to obtain a nickel-aluminum alloy wire.

2. The preparation process of a nickel-aluminum alloy wire according to claim 1, characterized in that: The superheat window is 30-80°C above the liquidus line.

3. The preparation process of a nickel-aluminum alloy wire according to claim 1, characterized in that: The intermediate alloys are Ni-Zr, Ni-B, and Ni-RE.

4. The preparation process of a nickel-aluminum alloy wire according to claim 1, characterized in that: The single-pass drawing reduction rate is 15-30%.

5. The preparation process of a nickel-aluminum alloy wire according to claim 1, characterized in that: The intermediate annealing temperature is 680-820℃, held for 1-4 hours, and then cooled in a vacuum or protective atmosphere.

6. The preparation process of a nickel-aluminum alloy wire according to claim 1, characterized in that: When the cumulative reduction rate reaches 80%±5%, an intermediate annealing is performed.

7. The preparation process of a nickel-aluminum alloy wire according to claim 1, characterized in that: The ΔR threshold is ≤7mΩ.

8. The preparation process of a nickel-aluminum alloy wire according to claim 1, characterized in that: The composite boiling and washing process is a two-stage composite boiling and washing process, including the following steps: (1) Alkali boiling for defatting: The annealed wire was placed in an alkaline solution containing 20-80 g / L sodium hydroxide and treated at 50-75℃ for 5-20 min. (2) Rinsing: Rinse with flowing deionized water until the pH reaches 6-8; (3) Compound pickling to remove oxide scale: Place the wire in a compound pickling solution and treat it at 20-40℃ for 20-90 min; The compound pickling solution contains 5-15 wt% sulfuric acid, 1-8 wt% nitric acid, and 0.05-0.10 wt% hydrofluoric acid. (4) Ultrasound enhancement: During the pickling process, superimpose ultrasonic treatment at 20-40 kHz for 3-20 min; (5) Neutralization and drying: After pickling, rinse thoroughly with deionized water until the pH reaches 6-8, and then dry with hot air at 60-120℃. After completing the composite boiling and washing process, the contact resistance fluctuation value ΔR is measured. If ΔR is greater than a preset threshold, at least one boiling and washing parameter is adjusted and the composite boiling and washing process is repeated until ΔR is not greater than the threshold.

9. The preparation process of a nickel-aluminum alloy wire according to claim 1, characterized in that: The adjustment of at least one boiling and washing parameter includes extending the alkaline boiling time and / or acid washing time, increasing the rinsing intensity, and increasing the ultrasonic treatment time.

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