[0055] Example 1
[0056] This embodiment provides a new type of nickel-chromium-cobalt-molybdenum superalloy seamless tube for power station, the seamless tube includes the following components by weight: C: 0.062%, Si: 0.012%, Mn: 0.03%, P: 0.005 %, S: 0.002%, Cr: 22.82%, Co: 12.95%, Al: 1.21%, Ti: 0.43%, Mo: 8.78%, Fe: 0.18%, Cu: 0.0089%, B: 0.005%, Pb: 0.001 %, Sb: 0.001%, Bi: 0.001%, Sn: 0.005%, As: 0.005%, the balance is Ni and trace elements, and the sum of the above components is 100%.
[0057] The manufacturing method of the above-mentioned new type of nickel-chromium-cobalt-molybdenum superalloy seamless pipe for power station, the process is as follows figure 1 shown, including the following steps:
[0058] (1) Smelting
[0059] The alloy material of the seamless tube is smelted by vacuum induction, the smelting temperature is 1500℃±10℃, cast into an alloy ingot of Ф360×2800mm, annealed at 1000~1100℃×24h×air-cooling, and then vacuum consumable into an alloy ingot of Ф423mm , and then perform homogenization heat treatment. The heat treatment system is: 1200 ° C ~ 1240 ° C × 72h, and the cooling method is air cooling, which can reduce the degree of segregation of alloying elements;
[0060] (2) Forging
[0061] The alloy ingot obtained in step (1) is opened with a 2000-ton fast forging machine, with a specification of 320mm octagonal billet, and then forged into a Ф250mm forging billet with a 1300-ton diameter forging machine, which can eliminate the as-cast looseness produced by the alloy during the smelting process. and other defects, making the microstructure more compact and better performance;
[0062] (3) Hot extrusion
[0063] The forging billet obtained in step (2) is peeled to remove oxide scale and other defects, then cut to length, and then machined into a hot extrusion billet with a specification of Ф236mm, and then hot extruded at 1150 ° C into a specification of Ф236mm. Ф114×12mm hot extrusion tube, at this temperature, the alloy has the best high temperature thermoplasticity, the structure is more uniform after hot extrusion, and the mechanical properties are good;
[0064] (4) Solution treatment and pickling
[0065] The hot extruded tube obtained in step (3) is subjected to solution heat treatment in a high temperature box furnace, the heat treatment temperature is 1160 ℃ ~ 1200 ℃, the heat preservation is 24 ~ 30min, the cooling method is water cooling, and then straightened to remove head and tail defects And remove the burr, use 5-8% hydrofluoric acid + 10-15% nitric acid mixture for pickling at 50-70 ℃, and then rinse to remove residual acid;
[0066] (5) Pipe end treatment
[0067] The inner and outer surfaces of the alloy tube obtained in step (4) are inspected, ground, and polished, and then 45° chamfering is performed on the outer wall of one end of the alloy tube;
[0068] (6) Cold rolling and heat treatment
[0069] Use the LG110 rolling mill to carry out 2 passes of cold rolling on the alloy tube treated in step (5):
[0070] Roll to Ф89×9mm and Ф76×7mm respectively, control the cold rolling deformation to be 30-45%, the feed rate to be 1-4mm/time, the rolling speed to be 30-50 times/min, and the outer diameter to be controlled at ±0.60mm, ±0.50mm, the wall thickness is controlled at ±0.40mm and ±0.30mm respectively. After each pass of cold rolling and oil removal, solution heat treatment is performed in a high temperature box furnace. ~20min, the cooling method is water cooling, the straightness is controlled to be ≤2.0mm/m after straightening, and then pickling, internal and external surface inspection, grinding, internal and external polishing, and 45° chamfering treatment at one end are carried out to make the alloy tube cold-rolled. It can reduce the stress concentration phenomenon and prevent the head from cracking;
[0071] 2 passes of cold rolling with LG60 mill:
[0072]Rolling to Ф60×5.4mm and Ф38×3.9mm respectively, the cold rolling deformation is 35~55%, the feeding amount is 1~4mm/time, and the rolling speed is 30~50 times/min to obtain better dimensional accuracy. The outer diameter is controlled at ±0.30mm and ±0.25mm respectively, and the wall thickness is controlled at ±0.25mm and ±0.20mm respectively. After each pass of cold rolling and degreasing, solution heat treatment is carried out in a high temperature box furnace. The heat treatment temperature is 1170℃~1200℃, heat preservation for 6~12min, cooling method is water cooling, straightness is controlled to be ≤1.5mm/m after straightening, and then pickling, internal and external surface inspection, grinding, internal and external polishing, and 45° chamfering treatment at one end, In order to reduce the stress concentration phenomenon of the alloy tube during cold rolling and prevent the head from cracking;
[0073] Then use the LG30 rolling mill for 2 passes of cold rolling:
[0074] Rolling to Ф26.8×3.1mm and Ф19×2.65mm respectively, the cold rolling deformation is 40~45%, the feed rate is 1~3mm/time, and the rolling speed is 20~40 times/min to obtain better size Accuracy, the outer diameter is controlled at ±0.18mm, ±0.12mm, and the wall thickness is controlled at ±0.12mm, ±0.10mm, respectively. After each pass of cold rolling and degreasing, solution heat treatment is performed in a pure hydrogen protection bright heat treatment furnace. , the heat treatment temperature is 1170 ℃ ~ 1200 ℃, the heat preservation is 6 ~ 10min, the cooling method is water cooling, the straightness is controlled to be ≤1.2mm/m after straightening, and then the inner and outer surface inspection, grinding, inner and outer polishing, and 45° chamfering treatment at one end , so that the alloy tube can reduce the stress concentration phenomenon during cold rolling and prevent the head from cracking;
[0075] Further, LD30 three-roll finishing rolling was used for 2 passes of cold rolling:
[0076] Roll to Ф16×2.25mm and Ф12.7×1.85mm respectively, the cold rolling deformation is 25~40%, the feed rate is 1~3mm/time, and the rolling speed is 10~30 times/min to obtain better size Accuracy, the outer diameter is controlled at ±0.08mm, ±0.05mm, and the wall thickness is controlled at ±0.08mm, ±0.06mm, respectively. After each pass of cold rolling and degreasing, solution heat treatment is performed in a pure hydrogen protection bright heat treatment furnace. , the heat treatment temperature is 1140 ° C ~ 1170 ° C, the heat preservation is 5 ~ 10 minutes, the cooling method is water jacket cooling, and then straightening, after straightening, control the straightness ≤ 1.0mm/m, and then carry out internal and external surface inspection, grinding, internal and external polishing , the pipe end chamfer;
[0077] (7) Inspection
[0078] Ultrasonic inspection is carried out on each finished tube, and the size of the artificial defect of the ultrasonic inspection standard sample is 0.07mm × 7mm × 0.14mm (depth × length × width);
[0079] Carry out a hydraulic test on each finished pipe, the hydraulic pressure is 69MPa, and the pressure holding time is ≥5s;
[0080] Surface inspection and dimensional inspection are carried out for each finished tube, the surface roughness Ra≤1.0μm, the allowable deviation of outer diameter is ±0.05mm, and the allowable deviation of wall thickness is ±0.10mm;
[0081] (8) Cleaning
[0082] Cleaning of the outer surface: Wipe the outer surface of the alloy tube with a cotton cloth dipped in acetone or alcohol one by one until the outer surface is free of stains caused by oil stains and foreign objects, and finally wipe it with a dry white cotton cloth;
[0083] Cleaning the inner surface: one by one, use white wool felt plugs dipped in acetone or alcohol to blow into the pipe holes with high pressure nitrogen for cleaning, until the surface of the cleaned wool felt plugs is free of stains caused by oil stains and foreign objects, and finally use dry sheep Felt plug or white cotton cloth to dry;
[0084] (9) Identification and packaging
[0085] The outer surface of the superalloy seamless tube is marked one by one by laser coding instead of ink coding;
[0086] After marking, each superalloy seamless pipe is cleaned. After cleaning, both ends are firmly sealed with plastic plugs, and the plastic bags are used for packaging. The superalloy seamless pipe is bundled and placed in a wooden box. The box is strong enough, and should be designed according to the number of packaging steel tubes and the volume of the packaging wooden box, and an appropriate amount of desiccant should be placed in the appropriate position. The desiccant is strictly prohibited from directly contacting the tube, and the packaging materials (sealed bags, plastic bags, plastic plugs, etc.) contain halogens Or the sulfur content should be less than 0.10% (weight percent), and the surface of the alloy tube should be sealed and packaged with a layer of plastic film to prevent the bag from being damaged; after packing, a packing list should be attached to the wooden box to indicate the manufacturer Name or trademark, material grade, specification, smelting furnace number, heat treatment furnace batch number (production batch number), steel pipe number, etc., there should be a mark on the outside of the wooden box, and the hoisting position, balance center mark and transportation should be marked in a prominent position outside the wooden box. Warning signs, such as "handle with care", "keep dry", "this side up", "no forklift truck", etc., should also indicate "the wooden box cannot be opened during shipment", etc.
[0087] The new type of nickel-chromium-cobalt-molybdenum superalloy seamless tube for power station manufactured in this example has both inner and outer surface roughness Ra ≤0.8 μm; the outer diameter is ±0.03 mm, the wall thickness is ±0.04; the grain size is 5.5 grades ; Mechanical properties at room temperature: R m =810MPa, R p0.2 =358MPa, A 50 =58.5%, R m Indicates tensile strength, R p0.2 represents the yield strength, A 50 Indicates elongation after fracture; Micro Vickers hardness at room temperature HV 0.5 =203, 207, 209; high temperature tensile properties: at 100 °C, R m =744MPa, R p0.2 =297MPa, A 50 =50.5%, at 200℃, R m =719MPa, R p0.2 =267MPa, A 50 =48.5%, at 300℃, R m =684MPa, R p0.2 =248MPa, A 50 =42.5%, at 400℃, R m =674MPa, R p0.2 =225MPa, A 50 =44.0%, at 500℃, R m =650MPa, R p0.2 =229MPa, A 50 =42.5%, at 550℃, R m =623MPa, R p0.2 =226MPa, A 50 =43.5%, at 600℃, R m =611MPa, R p0.2 =212MPa, A 50 =45.5%, at 650℃, R m =586MPa, R p0.2 =205MPa, A 50 =41.5%, at 700℃, R m =514MPa, R p0.2 =211MPa, A 50 =36.5%.
