Method for cold drawing of high-temperature alloy hexagonal bar and product

Abstract

The application adopts a three-time electric annealing process, comprises a new electric annealing process, heats the workpiece through resistance heat, and monitors the temperature through high-temperature infrared temperature measurement, realizes excellent surface quality and performance requirements of the material, effectively solves the problem of excessive oxidation of the surface of the high-temperature alloy hexagonal bar in the cold drawing process, prevents the surface roughness pit, realizes the surface quality of the hexagonal bar with qualified performance, excellent surface quality and excellent size control.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature alloy manufacturing, specifically relating to a method for cold drawing high-temperature alloy hexagonal bars and the resulting product. Background Technology

[0002] GH2696 is a wrought superalloy with molybdenum and niobium as the main strengthening elements. It possesses high yield strength, creep strength, and endurance and creep resistance, as well as good high-temperature elastic properties, resistance to combustion gas corrosion, and machinability. It is widely used abroad in the manufacture of various high-temperature components for aero-engines, with a long history of reliable use. In my country, this alloy is used to manufacture fasteners, pipe fittings, mounting brackets, and other parts for various engines.

[0003] The manufacturing process of GH2696 hexagonal bars includes hot rolling and cold drawing. Hot rolling is difficult to control and can lead to coarse grains and substandard performance. Furthermore, due to the fluidity and deformability of the metal at high temperatures during hot rolling, the dimensional accuracy and surface quality of GH2696 hexagonal bars may be difficult to precisely control. The main problems with cold drawing hexagonal bars are material cracking due to work hardening and insufficient dimensional control precision. Summary of the Invention

[0004] This invention primarily addresses a series of problems in the cold-drawing process of high-temperature alloy hexagonal bars, achieving a method for manufacturing hexagonal bars with satisfactory performance, excellent surface quality, and precise dimensional control. The specific technical solution of this invention is as follows:

[0005] A method for cold drawing high-temperature alloy hexagonal bars includes the following steps:

[0006] Step 1: Hot-roll the base bar into round bars, with the round bar dimensions being at least 30% larger than the finished product dimensions;

[0007] Step 2: Cold drawing and rounding, with a deformation of 10-12%; the specification t0 of the cold-drawn bar is 0.9-0.96 of the bar diameter;

[0008] Step 3: Peeling treatment, remove the oxide scale, folds, steps and other defects from the surface of the bar, peeling off 0.5-1mm thick;

[0009] Step 4: Solution treatment. After holding the bar obtained in Step 3 at 1000℃-1100℃ for 2 hours, solution treatment is performed using oil cooling.

[0010] Step 5: First hexagonal cold drawing treatment, deformation amount controlled at 5-10%, the treated bar s1=(1.15-1.2)s, where s refers to the distance between opposite sides of the initial hexagonal bar, and s1 is the distance between opposite sides of the bar after the first hexagonal cold drawing treatment;

[0011] Step 6: First electric annealing treatment. The electric annealing process is as follows: heat the bar to 1040℃ within 40-60 seconds, and then immediately water cool it.

[0012] Step 7: Second hexagonal cold drawing treatment, deformation controlled at 5-10%, specification s2=(1.05-1.08)s, where s refers to the distance between opposite sides of the initial hexagonal bar, and s2 is the distance between opposite sides of the bar after the second hexagonal cold drawing treatment;

[0013] Step 8: Second electric annealing treatment. The electric annealing process is as follows: heat the bar to 1040℃ within 40-60 seconds, and then immediately water cool it.

[0014] Step 9: First pickling treatment to remove the oxide scale from the bars;

[0015] Step 10: The third hexagonal cold drawing process is carried out using a polycrystalline die. The die is selected with a negative tolerance of 0-0.02. The dimensions are strictly controlled during cold drawing.

[0016] Step 11: Third electric annealing treatment. The electric annealing process is as follows: heat the bar to 1040℃ within 40-60 seconds and then immediately water cool it.

[0017] Step 12: Head cutting and straightening. Cut off the head and tail of the pull-out part and straighten it using a cantilever straightening machine with hexagonal pressure rollers.

[0018] Step 13: Second pickling treatment to remove all impurities from the surface, finally completing the product processing.

[0019] Furthermore, the composition of the high-temperature alloy hexagonal bar is as follows: by mass fraction, carbon: ≤0.1%, chromium: 10-12.5%, nickel: 21-25%, molybdenum: 1.0-1.6%, aluminum: ≤0.08%, titanium: 2.6-3.2%, silicon: ≤0.6%, manganese: ≤0.6%, phosphorus: ≤0.02%, sulfur: ≤0.01%, boron: ≤0.02%, and the balance iron.

[0020] Preferably, the hot rolling process in step 1 is as follows: first heating, then rolling, and finally cooling down, with a rolling temperature of 1080-1100℃ and a final rolling temperature of ≥900℃.

[0021] In step 4, oil cooling refers to immersing the material in oil immediately after solution treatment to achieve good material properties.

[0022] The process flow of hexagonal cold drawing in step 5 is as follows: rolling head → surface lubrication → drawing; drawing speed 1m~2m / min, check the surface of the die before and after drawing to ensure it is mirror smooth and free of any defects; check the surface of the material after drawing for roughness and perform grinding and polishing treatment in time.

[0023] The acid used in the pickling process in step 9 consists of 2.5-3.5 parts hydrofluoric acid, 10-12 parts nitric acid, 2 parts citric acid, 1.5 parts sulfuric acid, and 1 part surfactant.

[0024] The acid used in the pickling process in step 13 consists of 2.5-3.5 parts hydrofluoric acid, 10-12 parts nitric acid, 2 parts citric acid, 1.5 parts sulfuric acid, and 1 part surfactant.

[0025] In step 6, electrical annealing is a method of heating the workpiece by resistance heating, and the temperature is monitored by high-temperature infrared thermometry.

[0026] A product prepared by the aforementioned method has a surface finish grade of h9 or higher.

[0027] This method employs a novel process flow, including a new electro-annealing process, to achieve excellent surface quality and performance requirements for the material. The method utilizes a three-stage electro-annealing process, effectively solving the problem of excessive surface oxidation and preventing rough surface pits. Two pickling processes result in a uniform and consistent surface with good performance. This method effectively improves efficiency, reduces process steps, and controls surface dimensions. Attached Figure Description

[0028] Figure 1 This is a photograph of the surface of the bar material initially obtained in Example 1 of the present invention;

[0029] Figure 2 This is a photograph of the surface of the bar after final processing in Embodiment 1 of the present invention. Detailed Implementation Example 1

[0030] GH2696 bars are selected with the following composition by mass fraction: carbon: ≤0.1%, chromium: 10-12.5%, nickel: 21-25%, molybdenum: 1.0-1.6%, aluminum: ≤0.08%, titanium: 2.6-3.2%, silicon: ≤0.6%, manganese: ≤0.6%, phosphorus: ≤0.02%, sulfur: ≤0.01%, boron: ≤0.02%, and the balance iron.

[0031] The initial GH2696 billet was processed into bars with a diameter of Ф35mm. A surface photograph of the bar is shown below. Figure 1 As shown, the following steps are performed on it:

[0032] The product is cold-drawn to a diameter of 33mm, then peeled to a diameter of Ф31mm. It is then solution-treated by oil cooling after holding at 1100℃ for 2 hours. Next, it undergoes a first hexagonal cold drawing to S1 of 28.5mm, followed by a first electrical annealing at 1040℃. A second hexagonal cold drawing is then performed to S2 of 26.5mm, followed by a second electrical annealing at 1040℃. A first pickling process removes the surface oxide layer. A third hexagonal cold drawing is then performed to S3 of 25mm, followed by a third electrical annealing at 1040℃. Finally, the finished product is pickled to a smooth surface. The final product meets performance requirements, with a side distance of 25 (-0.04~-0.02)mm and a dimensional accuracy grade of h9. The final product photo is shown below. Figure 2 As shown. Example 2

[0033] High-temperature alloy hexagonal bars are prepared by cold drawing using the following steps:

[0034] Step 1: Hot-roll the base bar into round bars, with the round bar dimensions being at least 30% larger than the finished product dimensions;

[0035] Step 2: Cold drawing and rounding, with a deformation of 10-12%; the specification t0 of the cold-drawn bar is 0.9-0.96 of the bar diameter;

[0036] Step 3: Peeling treatment, remove the oxide scale, folds, steps and other defects from the surface of the bar, peeling off 0.5-1mm thick;

[0037] Step 4: Solution treatment. After holding the bar obtained in Step 3 at 1000℃-1100℃ for 2 hours, solution treatment is performed using oil cooling.

[0038] Step 5: First hexagonal cold drawing treatment, deformation amount controlled at 5-10%, the treated bar s1=(1.15-1.2)s, where s refers to the distance between opposite sides of the initial hexagonal bar, and s1 is the distance between opposite sides of the bar after the first hexagonal cold drawing treatment;

[0039] Step 6: First electric annealing treatment. The electric annealing process is as follows: heat the bar to 1040℃ within 40-60 seconds, and then immediately water cool it.

[0040] Step 7: Second hexagonal cold drawing treatment, deformation controlled at 5-10%, specification s2=(1.05-1.08)s, where s refers to the distance between opposite sides of the initial hexagonal bar, and s2 is the distance between opposite sides of the bar after the second hexagonal cold drawing treatment;

[0041] Step 8: Second electric annealing treatment. The electric annealing process is as follows: heat the bar to 1040℃ within 40-60 seconds, and then immediately water cool it.

[0042] Step 9: First pickling treatment to remove the oxide scale from the bars;

[0043] Step 10: The third hexagonal cold drawing process is carried out using a polycrystalline die. The die is selected with a negative tolerance of 0-0.02. The dimensions are strictly controlled during cold drawing.

[0044] Step 11: Third electric annealing treatment. The electric annealing process is as follows: heat the bar to 1040℃ within 40-60 seconds and then immediately water cool it.

[0045] Step 12: Head cutting and straightening. Cut off the head and tail of the pull-out part and straighten it using a cantilever straightening machine with hexagonal pressure rollers.

[0046] Step 13: Second pickling treatment to remove all impurities from the surface, finally completing the product processing.

[0047] Furthermore, the composition of the high-temperature alloy hexagonal bar is as follows: by mass fraction, carbon: ≤0.1%, chromium: 10-12.5%, nickel: 21-25%, molybdenum: 1.0-1.6%, aluminum: ≤0.08%, titanium: 2.6-3.2%, silicon: ≤0.6%, manganese: ≤0.6%, phosphorus: ≤0.02%, sulfur: ≤0.01%, boron: ≤0.02%, and the balance iron.

[0048] Preferably, the hot rolling process in step 1 is as follows: first heating, then rolling, and finally cooling down, with a rolling temperature of 1080-1100℃ and a final rolling temperature of ≥900℃.

[0049] In step 4, oil cooling refers to immersing the material in oil immediately after solution treatment to achieve good material properties.

[0050] The process flow of hexagonal cold drawing in step 5 is as follows: rolling head → surface lubrication → drawing; drawing speed 1m~2m / min, check the surface of the die before and after drawing to ensure it is mirror smooth and free of any defects; check the surface of the material after drawing for roughness and perform grinding and polishing treatment in time.

[0051] The acid used in the pickling process in step 9 consists of 2.5 parts hydrofluoric acid, 12 parts nitric acid, 2 parts citric acid, 1.5 parts sulfuric acid, and 1 part surfactant.

[0052] The acid used in the pickling process in step 13 consists of 3.5 parts hydrofluoric acid, 10 parts nitric acid, 2 parts citric acid, 1.5 parts sulfuric acid, and 1 part surfactant.

[0053] In step 6, electrical annealing is a method of heating the workpiece by resistance heating, and the temperature is monitored by high-temperature infrared thermometry.

Claims

1. A method of cold drawing a high temperature alloy hexagonal bar, characterized in that, The method comprises the following steps: step 1, hot rolling the base bar into a round bar, the size of the round bar being at least 30% larger than the size of the finished product; Step 2, cold drawing and rounding, the deformation being 10-12%, the size of the bar after cold drawing t0 being 0.9-0.96 times the diameter of the base bar; Step 3, peeling the bar obtained in step 2, the peeling thickness being 0.5-1 mm; Step 4, solid solution treatment, the bar obtained in step 3 being heated at 1000-1100 ℃ for 2 h, and then being cooled by oil cooling; Step 5, first hexagonal cold drawing, the deformation being controlled to be 5-10%, the size of the bar after the first hexagonal cold drawing s1 being (1.15-1.2) s, wherein s refers to the opposite side distance of the initial hexagonal bar, and s1 refers to the opposite side distance of the bar after the first hexagonal cold drawing; Step 6, first electric annealing treatment, the electric annealing process being that the bar is heated to 1040 ℃ within 40-60 s, and then being immediately water-cooled; Step 7, second hexagonal cold drawing, the deformation being controlled to be 5-10%, the size of the bar after the second hexagonal cold drawing s2 being (1.05-1.08) s, wherein s refers to the opposite side distance of the initial hexagonal bar, and s2 refers to the opposite side distance of the bar after the second hexagonal cold drawing; Step 8, second electric annealing treatment, the electric annealing process being that the bar is heated to 1040 ℃ within 40-60 s, and then being immediately water-cooled; Step 9, first pickling treatment, so as to remove the oxide skin of the bar; Step 10, third hexagonal cold drawing, a polycrystal die is adopted, the die is selected to have a negative tolerance of 0-0.02, and the size is strictly controlled during cold drawing; Step 11, third electric annealing treatment, the electric annealing process being that the bar is heated to 1040 ℃ within 40-60 s, and then being immediately water-cooled; Step 12, head cutting and straightening, the drawing head and tail are cut off, and a cantilever straightening machine is adopted to straighten the bar by using a hexagonal pressing wheel; Step 13, second pickling treatment, so as to remove all impurities on the surface, and finally the product is processed and manufactured.

2. The method of cold drawing a high temperature alloy hexagonal bar according to claim 1, wherein The high-temperature alloy hexagonal bar comprises the following components in mass fraction: carbon: ≤0.1%, chromium: 10-12.5%, nickel: 21-25%, molybdenum: 1.0-1.6%, aluminum: ≤0.08%, titanium: 2.6-3.2%, silicon: ≤0.6%, manganese: ≤0.6%, phosphorus: ≤0.02%, sulfur: ≤0.01%, boron: ≤0.02%, and the balance of iron.

3. The method of cold drawing a high temperature alloy hexagonal bar according to claim 1, wherein The hot rolling process of the hot rolling in step 1 is: heating first, rolling second, and cooling last, the rolling temperature being 1080-1100 ℃, and the final rolling temperature being ≥900 ℃.

4. The method of cold drawing a high temperature alloy hexagonal bar according to claim 1, wherein The oil cooling in step 4 refers to that the bar is immediately immersed in oil for cooling after the solid solution ends, so as to achieve good material performance.

5. The method of cold drawing high temperature alloy hexagonal bar according to claim 1, wherein The process flow of the hexagonal cold drawing in step 5 is: rolling the head first, then surface lubrication, and finally drawing; the drawing speed is 1-2 m / min; the surface of the die should be mirror-smooth before and after drawing, and should not have any defects; whether the surface of the material is rough after drawing is checked, and timely polishing treatment is carried out.

6. The method of cold drawing a high temperature alloy hexagonal bar according to claim 1, wherein The acid used in the pickling treatment in step 9 comprises the following components: 2.5-3.5 parts of hydrofluoric acid, 10-12 parts of nitric acid, 2 parts of citric acid, 1.5 parts of sulfuric acid, and 1 part of a surfactant.

7. The method of cold drawing a high temperature alloy hexagonal bar according to claim 1, wherein The acid used in the pickling process in step 13 has the following composition: 2.5-3.5 parts of hydrofluoric acid, 10-12 parts of nitric acid, 2 parts of citric acid, 1.5 parts of sulfuric acid and 1 part of surfactant.

8. The method of cold drawing a high temperature alloy hexagonal bar according to claim 1, wherein The electric annealing in step 6 is a method of heating the workpiece by resistance heat, and the temperature is monitored by high-temperature infrared temperature measurement.

9. A product produced by the method of claim 1, wherein The surface precision grade reaches h9 and above.

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