A c350 maraging alloy wire rod and a method of manufacturing the same

Abstract

The present application relates to the technical field of metal material processing, and particularly relates to a C350 maraging alloy wire rod and a production process thereof. The technical scheme of the present application is as follows: a C350 maraging alloy wire rod is composed of the following elements, and the mass fraction wt% content is as follows: Ni: 18.00-19.00, Co: 11.00-12.50, Mo: 4.50-5.50, Ti: 1.20-1.60, Al: 0.05-0.20, C<=0.03, Si<=0.10, Mn<=0.10, P<=0.010, S<=0.010, B<=0.003, Zr<=0.01, O<=30PPm, N<=100ppm, H<=2ppm, and the balance is Fe. The present application has the following advantages: high purity: double vacuum melting strictly controls impurities, O<=30PPm, N<=100ppm, H<=2ppm, significantly improves cold drawing performance and fatigue life, is suitable for high-frequency moving parts, and the structure is uniform and refined; excellent surface quality: fine treatment and lubricating coating, no oxide skin and no cracks on the surface, Ra<=0.2um, performance matching scene, and stable mass production process parameters are precisely controllable.

Description

Technical Field

[0001] This invention relates to the field of metal material processing technology, and in particular to a 00Ni18Co12Mo5ALTi (C350) martensitic aging alloy wire rod and its production process. Background Technology

[0002] 00Ni18Co12Mo5ALTi martensitic aging alloy is an ultra-high strength alloy with characteristics such as ultra-high strength, high toughness, high hardness, low deformation, and corrosion resistance. It is traditionally used in the aerospace field. In recent years, demand has surged in the 3C and intelligent equipment fields such as AI robot joints and foldable screen hinges for mobile phones. These components need to withstand high-frequency reciprocating motion within an extremely small volume, which places extremely high demands on the dimensional accuracy, surface quality, microstructure uniformity, and fatigue life of the materials.

[0003] The existing technology has the following drawbacks: 1. Poor impurity control, with high levels of O, N, H, S, and P, leads to easy cracking and insufficient fatigue life in cold-drawn wire. 2. Poor process compatibility, narrow high-temperature forging / rolling temperature range, and unreasonable annealing process result in uneven wire rod hardness and poor drawing performance; 3. Rough surface treatment, residual oxide scale, and high surface roughness affect the accuracy of subsequent precision machining and assembly; 4. Not optimized for 3C / AI equipment scenarios, the filament material lacks ultra-fine dimensional stability and high-frequency fatigue resistance. Summary of the Invention

[0004] The purpose of this invention is to provide a 00Ni18Co12Mo5ALTi martensitic aging alloy wire rod and its production process, achieving high purity, high dimensional accuracy, high surface quality, and high fatigue life, and adapting to the needs of high-frequency motion precision components such as AI robot joints and mobile phone folding screen hinges.

[0005] The technical solution of the present invention is as follows: A C350 martensitic aging alloy wire rod, characterized in that it is composed of the following elements, with a mass fraction (wt%) of: Ni: 18.00~19.00, Co: 11.00~12.50, Mo: 4.50~5.50, Ti: 1.20~1.60, Al: 0.05~0.20, C≤0.03, Si≤0.10, Mn≤0.10, P≤0.010, S≤0.010, B≤0.003, Zr≤0.01, O≤30ppm, N≤100ppm, H≤2ppm, balance Fe.

[0006] A production process for C350 martensitic aging alloy wire rod includes the following steps: 1) Vacuum induction melting: Raw materials are carefully selected, vacuum degree ≤1×10⁻³Pa, refining temperature 1520~1560℃, holding temperature for 30~40min, casting Φ180~250mm electrode rods, controlling impurity content; 2) Vacuum arc remelting: Electrode rods are vacuum arc remelted, vacuum degree ≤5×10⁻³Pa. 4 Pa, current 2600~4000A, voltage 22~26V, cooling rate 8~12℃ / min, to obtain a high-purity ingot of Φ240~300mm, eliminating segregation and inclusions; 3) High-temperature homogenization annealing, heating the ingot to 1180~1200℃, holding for 8~12h, air cooling to room temperature, to homogenize the structure, eliminate internal stress, and improve hot working plasticity; 4) Staged high-temperature forging, first forging: 1050~1120℃, forging ratio 3~4, forging to 120*120~150*150mm square bar; second forging: 1000~1100℃, forging ratio 2~3, forging to 80*80~90*90mm square bar; final forging temperature ≥850℃ to avoid cold forging cracks and refine grains; 5) High-precision hot-rolled wire rod: heating the bar to 980~1020℃, holding for 40~60min, continuous rolling, final rolling temperature ≥850℃, rolling speed 5~8m / s, rolling to Φ5.5~12mm wire rod, air cooling to room temperature, dimensional tolerance control ±0.30mm; 6) Solution annealing: heating the wire rod to 820~840℃, holding for 60~90min, air cooling, to obtain a uniform martensitic structure, hardness 30~35HRC, meeting the requirements for cold drawing plasticity; 7) Surface finishing: descaling + lubricating coating treatment steps, alkali immersion + pickling: alkali immersion (15~20min) → 10% hydrochloric acid + 0.5% corrosion inhibitor (50-60℃, 15-20 min) → high-pressure water rinsing (20 MPa) → neutralization (5% Na2CO3) → drying (120℃); phosphating + saponification: manganese phosphating (80℃, 10-15 min) → Sodium stearate saponification (60℃, 5~8min) forms a dense lubricating film, reducing drawing friction; 8) Multi-pass cold drawing of wire, using progressive diameter reduction drawing, with a pass compression rate of 15%~20%, a drawing speed of 3~5m / min, and a die material of cemented carbide, finally producing Φ1.0~6.0mm wire with dimensional accuracy ±0.015mm and surface roughness Ra≤0.6μm; 9) Precision inspection and clean winding steps, inspection: surface cracks, metallographic requirements for grain size ≥6 or finer, mechanical properties of strength and toughness, and dimensional accuracy using laser diameter measurement; clean treatment: ultrasonic cleaning to remove anhydrous ethanol for 10 minutes → vacuum drying at 80℃ for 2 hours → winding in a dust-free environment, and packaging for moisture and rust prevention.

[0007] Furthermore, before performing the precision testing and clean winding steps, the filament undergoes an aging strengthening treatment. After straightening, the filament is aged at 490–510°C for 3–6 hours, followed by air cooling, resulting in a hardness of 55–60 HRC and a tensile strength ≥2450 MPa.

[0008] Furthermore, a C350 martensitic aging alloy wire rod is characterized by the following composition: Ni: 18.00, Co: 11.50, Mo: 4.50, Ti: 1.40, Al: 0.08, C: 0.03, Si: 0.05, Mn: 0.10, P: 0.010, S: 0.010, B: 0.002, Zr: 0.01, O: 20 ppm, N: 800 ppm, H: 2 ppm.

[0009] Furthermore, Ni: 18.50, Co: 12.50, Mo: 4.80, Ti: 1.20, Al: 0.15, C≤0.02, Si≤0.10, Mn≤0.05, P≤0.010, S≤0.010, B≤0.001, Zr≤0.01, O: 30PPm, N: 50ppm, H: 1ppm.

[0010] Furthermore, the composition is as follows: Ni: 19.00, Co: 11.80, Mo: 4.70, Ti: 1.350, Al: 0.090, C: 0.02, Si: 0.10, Mn: 0.10, P: 0.010, S: 0.005, B: 0.001, Zr: 0.01, O: 30 ppm, N: 90 ppm, H: 2 ppm.

[0011] Applications of C350 martensitic aging alloy wire rod: for high-frequency motion precision components in AI robot joints and mobile phone folding screen hinges.

[0012] The beneficial effects of this invention are: 1. High purity: Dual vacuum melting strictly controls impurities, O≤30PPm, N≤100ppm, H≤2ppm, significantly improving cold drawing performance and fatigue life, suitable for high-frequency moving parts.

[0013] 2. Uniform and refined microstructure: graded forging + precision rolling + solution annealing, resulting in uniform and fine grains (≥8 grade), no segregation inclusions, excellent dimensional stability, and aging deformation ≤0.01%.

[0014] 3. Excellent surface quality: fine treatment and lubricating coating, no oxide scale or cracks on the surface, Ra≤0.2μm, meeting the requirements of 3C precision assembly.

[0015] 4. Performance matching scenarios: Wire strength ≥2450MPa, hardness 55~60HRC, fatigue strength ≥800MPa, suitable for AI robot joints (high frequency rotation) and mobile phone folding screen hinges (100,000 folds).

[0016] 5. Stable mass production: The process parameters are precise and controllable, and it can stably produce Φ0.1~6.0mm wire with a dimensional accuracy of ±0.015mm and a yield rate of ≥99.5%, replacing imports and reducing costs. Detailed Implementation

[0017] Wire rod production process 1. Vacuum induction melting + vacuum arc remelting (double vacuum purification) Vacuum induction melting: Selected raw materials (high-purity iron, high-purity Ni / Co / Mo / Ti / Al), vacuum degree ≤1×10⁻³Pa, refining temperature 1520~1560℃, holding temperature for 30~40min, casting Φ180~250mm electrode rod, and controlling impurity content.

[0018] Vacuum arc remelting: Vacuum arc remelting of electrode rods, vacuum degree ≤5×10⁻ 4 Pa, current 2600~4000A, voltage 22~26V, cooling rate 8~12℃ / min, to obtain high-purity ingots with diameter 240~300mm, eliminating segregation and inclusions.

[0019] 2. High-temperature homogenization annealing The ingot is heated to 1180~1200℃, held for 8~12 hours, and then air-cooled to room temperature to homogenize the microstructure, eliminate internal stress, and improve hot working plasticity.

[0020] 3. Staged high-temperature forging Forging: 1050~1120℃, forging ratio 3~4, forging to 120*120~150*150mm square bar; Second forging: 1000~1100℃, forging ratio 2~3, forging to 80*80~90*90mm square bar; The final forging temperature should be ≥850℃ to avoid cold forging cracks and refine the grain size.

[0021] 4. High-precision hot-rolled wire rod The bar stock is heated to 980~1020℃, held for 40~60min, and continuously rolled. The final rolling temperature is ≥850℃, the rolling speed is 5~8m / s, and the stock is rolled into Φ5.5~12mm wire rod. It is then air-cooled to room temperature, and the dimensional tolerance is controlled at ±0.30mm.

[0022] 5. Solution annealing (soft state preparation) The wire rod is heated to 820-840℃, held for 60-90 minutes, and then air-cooled to obtain a uniform martensitic structure with a hardness of 30-35 HRC, which meets the requirements for cold drawing plasticity.

[0023] 6. Surface finishing (removal of oxide scale + lubricating coating) Alkali immersion + acid pickling: Alkali immersion (15-20 min) → 10% hydrochloric acid + 0.5% corrosion inhibitor (50-60℃, 15-20 min) → high-pressure water rinsing (20 MPa) → neutralization (5% Na2CO3) → drying (120℃); Phosphating + Saponification: Manganese phosphating (80℃, 10-15 min) → Sodium stearate saponification (60℃, 5-8 min) to form a dense lubricating film and reduce drawing friction.

[0024] 7. Multi-pass cold drawing for wire production The process employs a progressive diameter reduction drawing method with a pass compression rate of 15%–20%, a drawing speed of 3–5 m / min, and a die material of cemented carbide. The final product is a wire with a diameter of Φ1.0–6.0 mm, a dimensional accuracy of ±0.015 mm, and a surface roughness Ra≤0.6 μm.

[0025] 8. Enhanced timeliness (on demand) After straightening, the wire undergoes aging treatment: 490~510℃, heat treatment for 3~6 hours, air cooling, hardness 55~60HRC, tensile strength ≥2450MPa. 9. Precision testing + clean tray operation Inspection: (surface cracks), metallography (grain size ≥ grade 6 or finer), mechanical properties (strength / toughness), dimensional accuracy (laser diameter measurement); Cleaning process: Ultrasonic cleaning (anhydrous ethanol, 10 min) → Vacuum drying (80℃, 2 h) → Dust-free environment winding on trays, packaging for moisture and rust prevention. Composition of 00Ni18Co12Mo5ALTi (C350) martensitic aging alloy (mass fraction, wt%) Ni: 18.00~19.00, Co: 11.00~12.50, Mo: 4.50~5.50, Ti: 1.20~1.60, Al: 0.05~0.20, C≤0.03, Si≤0.10, Mn≤0.10, P≤0.010, S≤0.010, B≤0.003, Zr≤0.01, O≤30ppm, N≤100ppm, H≤2ppm, balance Fe.

[0026] Example 1 (Φ2.0mm Wire for Folding Screen Hinge) 1. Composition: Ni 19.0%, Co 12.0%, Mo 5.0%, Ti 1.4%, Al 0.09%, impurities C≤0.02%, O≤0.0020%; 2. Double vacuum melting: Vacuum induction heating at 1540℃ for 35 minutes → vacuum arc remelting to obtain a Φ280mm ingot; 3. Homogenization: Hold at 1200℃ for 10 hours; 4. Staged forging: First forging at 1080℃ → 120*120mm, second forging at 980℃ → 85*85mm, final forging at 880℃; 5. Hot rolling: Hold at 1000℃ for 50 min → Φ6.5mm wire rod, final rolling at 880℃; 6. Solution annealing: Hold at 830℃ for 75 minutes, hardness 32HRC; 7. Surface treatment: shot blasting for 22 min → pickling for 18 min → phosphating for 12 min → saponification for 6 min; 8. Cold drawing: 5 passes to Φ2.0mm, dimensional tolerance ±0.01mm, Ra0.15μm; 9. Aging: After holding at 500℃ for 4 hours, the hardness is 58HRC and the tensile strength is 2580MPa; 10. Inspection: Eddy current testing showed no cracks, grain size grade 8.5, and no breakage after 100,000 folds.

[0027] Example 2 (Φ3.0mm AI robot joint wire) 1. Composition: Ni 18.8%, Co 11.8%, Mo 4.9%, Ti 1.35%, Al 0.10%, impurities S≤0.005%, N≤0.010%; O≤0.003%; H≤0.0002%.

[0028] 2. Double vacuum melting: Vacuum induction heating at 1530℃ for 38 minutes → vacuum arc remelting to obtain a Φ260mm ingot; 3. Homogenization: Hold at 1190℃ for 11 hours; 4. Staged forging: First forging at 1060℃ → Φ130mm, second forging at 960℃ → Φ65mm, final forging at 860℃; 5. Hot rolling: Hold at 990℃ for 45 min → Φ8.0mm wire rod, final rolling at 870℃; 6. Solution annealing: Hold at 825℃ for 80 minutes, hardness 33 HRC; 7. Surface treatment: Alkali soaking for 15-20 min → pickling for 16 min → phosphating for 14 min → saponification for 7 min; 8. Cold drawing: 6 passes to Φ3.0mm, dimensional tolerance ±0.015mm; 9. Aging: After holding at 495℃ for 5 hours, the hardness is 57HRC and the tensile strength is 2460MPa; 10. Testing: High-frequency fatigue strength 820MPa, joints showed no wear after 5000 hours of continuous operation.

[0029] The 00Ni18Co12Mo5ALTi(C350) martensitic aging alloy wire rod prepared by this invention can be directly used for: 1. Foldable screen hinge for mobile phones: Φ0.5~3.0mm wire is used to make the hinge shaft and connecting rod, meeting the requirements of 100,000 folding cycles and thinness; 2. AI robot joints: Φ2.0~6.0mm wire is used to make elbow and wrist joint shafts, which can withstand high-frequency rotation and high load, and have a long fatigue life; 3. Others: Precision springs, miniature bearings, high-strength fasteners, and other high-frequency moving parts for 3C and intelligent equipment.

[0030] During vacuum smelting, 1. All materials must meet the quality requirements for vacuum smelting. ≤25% of the returned material should be used. After baking at 400℃ for more than 6 hours according to regulations, the surface should be polished before use. 2. The amount of other elements introduced into the current furnace must be strictly controlled to ensure the composition is not affected. Vacuum smelting should be performed according to the high-temperature smelting process. The vacuum degree during melting should be less than 2 Pa. Refining should involve adding 0.05% Ni-Mg, 0.05% rare earth, and 0.05% Ni-Ca. Smaller materials should be added after refining during the power-off film formation for deoxidation, and the composition should be controlled. The vacuum degree during refining should be ≤2 Pa. At least two high-temperature instantaneous refining processes and one low-temperature long-term refining process should be used. The steel temperature should be raised to 1540℃ for 1-2 minutes, then lowered to 1400℃ (in the initial film formation state). The refining time should be ≥50 minutes. The refining temperature should be 1500℃. Strict control of material purity and uniform melting is required. The tapping temperature should be adjusted to 1580℃. The electrode rod should be cast, and the electrode markings should be air-cooled before the next process and the surface polished.

[0031] Vacuum consumable ingot operation: 1. Clean the shrinkage cavities at both ends of the electrode, and grind and clean surface defects. Use the same steel grade base pad and the same steel ingot ignition rod. Use Hualin new vacuum electroslag furnace with full gas protection for electroslag or vacuum consumable ingot operation. Add trace elements according to the Al and Ti content. 2. Follow the vacuum consumable ingot operation process specifications. 3. Sufficiently compensate for shrinkage in the later stage of consumable ingot operation. 4. After cooling for 30 minutes, demold the steel ingot and air cool it. 5. Machining the surface of the vacuum consumable ingot to remove defects.

[0032] During the forging process: 1. The forging heating temperature is 1100-1120℃, and the holding time should be ≥4h; 2. The initial forging temperature is ≥1100℃; the final forging temperature is ≥850℃; 3. Ultrasonic testing is performed on the forging billet; 4. The entire surface of the square bar is ground or polished, and the surface penetration test shows no cracks or defects. After passing the inspection, the bar is then hot-rolled into wire rod.

[0033] As a preferred composition, Ni: 18.00, Co: 11.50, Mo: 4.50, Ti: 1.40, Al: 0.08, C: 0.03, Si: 0.05, Mn: 0.10, P: 0.010, S: 0.010, B: 0.002, Zr: 0.01, O: 20 ppm, N: 800 ppm, H: 2 ppm.

[0034] As a preferred composition, Ni: 18.50, Co: 12.50, Mo: 4.80, Ti: 1.20, Al: 0.15, C≤0.02, Si≤0.10, Mn≤0.05, P≤0.010, S≤0.010, B≤0.001, Zr≤0.01, O: 30ppm, N: 50ppm, H: 1ppm.

[0035] As a preferred composition, the composition is as follows: Ni: 19.00, Co: 11.80, Mo: 4.70, Ti: 1.350, Al: 0.090, C: 0.02, Si: 0.10, Mn: 0.10, P: 0.010, S: 0.005, B: 0.001, Zr: 0.01, O: 30 ppm, N: 90 ppm, H: 2 ppm.

[0036] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements or substitutions without departing from the principles of the present invention, and these improvements or substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A C350 martensitic aging alloy wire rod, characterized in that: Composed of the following elements, with a mass fraction (wt%) of: Ni: 18.00~19.00, Co: 11.00~12.50, Mo: 4.50~5.50, Ti: 1.20~1.60, Al: 0.05~0.20, C≤0.03, Si≤0.10, Mn≤0.10, P≤0.010, S≤0.010, B≤0.003, Zr≤0.01, O≤30ppm, N≤100ppm, H≤2ppm, balance Fe.

2. The production process of C350 martensitic aging alloy wire rod according to claim 1 includes the following steps: 1) Vacuum induction melting: Raw materials are carefully selected, vacuum degree ≤1×10⁻³Pa, refining temperature 1520~1560℃, holding time 30~40min, casting Φ180~250mm electrode rods, controlling impurity content; 2) Vacuum arc remelting: Electrode rods are vacuum arc remelted, vacuum degree ≤5×10⁻³Pa. 4 Pa, current 2600~4000A, voltage 22~26V, cooling rate 8~12℃ / min, to obtain a high-purity ingot of Φ240~300mm, eliminating segregation and inclusions; 3) High-temperature homogenization annealing, heating the ingot to 1180~1200℃, holding for 8~12h, air cooling to room temperature, to homogenize the structure, eliminate internal stress, and improve hot working plasticity; 4) Staged high-temperature forging, first forging: 1050~1120℃, forging ratio 3~4, forging to 120*120~150*150mm square bar; second forging: 1000~1100℃, forging ratio 2~3, forging to 80*80~90*90mm square bar; final forging temperature ≥850℃ to avoid cold forging cracks and refine grains; 5) High-precision hot-rolled wire rod: heating the bar to 980~1020℃, holding for 40~60min, continuous rolling, final rolling temperature ≥850℃, rolling speed 5~8m / s, rolling to Φ5.5~12mm wire rod, air cooling to room temperature, dimensional tolerance control ±0.30mm; 6) Solution annealing: heating the wire rod to 820~840℃, holding for 60~90min, air cooling, to obtain a uniform martensitic structure, hardness 30~35HRC, meeting the requirements for cold drawing plasticity; 7) Surface finishing: descaling + lubricating coating treatment steps, alkali immersion + pickling: alkali immersion (15~20min) → 10% hydrochloric acid + 0.5% corrosion inhibitor (50-60℃, 15-20 min) → high-pressure water rinsing (20 MPa) → neutralization (5% Na2CO3) → drying (120℃); phosphating + saponification: manganese phosphating (80℃, 10-15 min) → Sodium stearate saponification (60℃, 5~8min) forms a dense lubricating film, reducing drawing friction; 8) Multi-pass cold drawing of wire, using progressive diameter reduction drawing, with a pass compression rate of 15%~20%, a drawing speed of 3~5m / min, and a die material of cemented carbide, finally producing Φ1.0~6.0mm wire with dimensional accuracy ±0.015mm and surface roughness Ra≤0.6μm; 9) Precision inspection and clean winding steps, inspection: surface cracks, metallographic requirements for grain size ≥6 or finer, mechanical properties of strength and toughness, and dimensional accuracy using laser diameter measurement; clean treatment: ultrasonic cleaning to remove anhydrous ethanol for 10 minutes → vacuum drying at 80℃ for 2 hours → winding in a dust-free environment, and packaging for moisture and rust prevention.

3. The production process of C350 martensitic aging alloy wire rod according to claim 2, characterized in that: Before the precision testing and clean winding steps, the wire undergoes an aging strengthening treatment. After straightening, the wire is aged at 490-510℃ for 3-6 hours, followed by air cooling. The hardness is 55-60 HRC, and the tensile strength is ≥2450 MPa.

4. The C350 martensitic aging alloy wire rod according to claim 1, characterized in that: Ni: 18.00, Co: 11.50, Mo: 4.50, Ti: 1.40, Al: 0.08, C: 0.03, Si: 0.05, Mn: 0.10, P: 0.010, S: 0.010, B: 0.002, Zr: 0.01, O: 20PPm, N: 800ppm, H: 2ppm.

5. The C350 martensitic aging alloy wire rod according to claim 2, characterized in that: Ni: 18.50, Co: 12.50, Mo: 4.80, Ti: 1.20, Al: 0.15, C≤0.02, Si≤0.10, Mn≤0.05, P≤0.010, S≤0.010, B≤0.001, Zr≤0.01, O: 30PPm, N: 50ppm, H: 1ppm.

6. The C350 martensitic aging alloy wire rod according to claim 2, characterized in that: Ni: 19.00, Co: 11.80, Mo: 4.70, Ti: 1.350, Al: 0.090, C: 0.02, Si: 0.10, Mn: 0.10, P: 0.010, S: 0.005, B: 0.001, Zr: 0.01, O: 30PPm, N: 90ppm, H: 2ppm.

7. An application of a C350 martensitic aging alloy wire rod, characterized in that: The C350 martensitic aging alloy wire rod according to claim 1 is used for high-frequency motion precision components such as AI robot joints and mobile phone folding screen hinges.