High-temperature alloy hexagonal bar cold drawing preparation method and product

Abstract

Three times of electric annealing processes are adopted, a new electric annealing process is included, a workpiece is heated through resistance heat, the temperature is monitored through high-temperature infrared temperature measurement, the excellent surface quality and performance requirements of a material are met, the problem of surface over-oxidation in the cold drawing manufacturing process of the high-temperature alloy hexagonal bar is effectively solved, and the cold drawing manufacturing process is simple and convenient. Pits with rough surfaces are prevented; through two times of acid pickling, the surface is uniform and consistent, and the performance is good; and moreover, the efficiency is effectively improved, the process flow is reduced, and the surface size is controlled. The manufacturing method of the hexagonal rod is qualified in performance, excellent in surface quality and excellent in size control.

Description

Technical Field

[0001] The invention belongs to the field of high-temperature alloy manufacturing, and in particular relates to a high-temperature alloy hexagonal bar cold-drawing preparation method and a product. Background Art

[0002] GH2696 is a deformable high-temperature alloy with molybdenum and niobium as the main strengthening elements. It has high yield strength, endurance and creep strength, as well as good high-temperature elasticity, gas corrosion resistance and processing plasticity. It is widely used in foreign countries to make various high-temperature parts of aircraft engines and has long-term reliable use experience. my country uses this alloy to make fasteners, pipe joints, mounting seats, brackets and other parts on a variety of engines.

[0003] The production process of GH2696 hexagonal bar includes hot rolling and cold drawing. The hot rolling process is difficult to control, which may lead to coarse grains and unqualified performance. In addition, during the hot rolling process, due to the fluidity and deformability of the metal at high temperature, the dimensional accuracy and surface quality of the GH2696 hexagonal bar may be difficult to accurately control. The main problem of cold drawing of hexagonal bars is the possible cracking of the material caused by work hardening, and the lack of dimensional control accuracy. Summary of the invention

[0004] The present invention mainly solves a series of problems in the cold-drawing process of high-temperature alloy hexagonal bars, and realizes a method for producing hexagonal bars with qualified performance, excellent surface quality and fine size control. The specific technical scheme of the present invention is as follows: A method for cold drawing a high-temperature alloy hexagonal bar, comprising the following steps: Step 1: hot rolling the base bar into a round bar, the size of the round bar is at least 30% larger than the finished product size; Step 2: Cold drawing to round, the deformation is 10-12%; the bar specification t0 after cold drawing is 0.9-0.96 of the bar diameter; Step 3: Peeling treatment, remove the oxide scale, folds, steps and other defects on the surface of the bar, peeling thickness 0.5-1mm; Step 4: Solution treatment: the rod obtained in step 3 is kept at 1000°C-1100°C for 2 hours, and then solution treated by oil cooling; Step 5: The first hexagonal cold drawing treatment, the deformation is controlled at 5-10%, and the treated bar s1=(1.15-1.2)s, where s refers to the distance across the flats of the initial hexagonal bar, and s1 is the distance across the flats of the bar after the first hexagonal cold drawing treatment; Step 6: The first electrical annealing process is as follows: the bar is heated to 1040°C within 40-60 seconds and then immediately cooled with water; Step 7: The second hexagonal cold drawing treatment, the deformation is controlled at 5-10%, and the specification is s2=(1.05-1.08)s, where s refers to the distance across the flats of the initial hexagonal bar, and s2 refers to the distance across the flats of the bar after the second hexagonal cold drawing treatment; Step 8: The second electrical annealing process is as follows: the rod is heated to 1040°C within 40-60 seconds and then immediately cooled with water; Step 9: The first pickling treatment is to remove the oxide scale of the bar; Step 10: The third hexagonal cold drawing process uses a polycrystalline mold, the mold selection has a negative tolerance of 0-0.02, and the cold drawing strictly controls the size; Step 11: The third electrical annealing process is as follows: the rod is heated to 1040°C within 40-60 seconds and then immediately cooled with water; Step 12: Cut and straighten the head, cut off the drawing head and tail, and use a cantilever straightening machine with a hexagonal pressure wheel to straighten; Step 13: A second pickling treatment is performed to remove all surface impurities and finally complete the product processing.

[0005] Furthermore, the composition of the high-temperature alloy hexagonal rod 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.

[0006] Preferably, the hot rolling process in step 1 is: heating first, then rolling, and finally cooling, the rolling temperature is 1080-1100°C, and the final rolling temperature is ≥900°C.

[0007] The oil cooling in step 4 means that after the solutionizing is completed, the material is immediately immersed in oil for cooling to achieve good material properties.

[0008] The process flow of hexagonal cold drawing in step 5 is as follows: rolling head → surface lubrication → drawing; the drawing rate is 1m~2m / min, and the mold surface should be mirror-smooth and free of any defects before and after drawing; after drawing, check whether the material surface is rough and perform grinding and polishing in time.

[0009] The acid used in the pickling treatment in step 9 is composed of: 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; The acid used in the pickling treatment in step 13 is composed of: 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.

[0010] In step 6, the electrical annealing is a method of heating the workpiece by resistance heat, and the temperature is monitored by high-temperature infrared temperature measurement.

[0011] A product made by the above method has a surface accuracy grade reaching h9 or above.

[0012] This method uses a new process flow, including a new electrical annealing process, to achieve excellent surface quality and performance requirements of the material. This method uses a three-time electrical annealing process to effectively solve the problem of excessive surface oxidation and prevent rough surface pits. After two picklings, the surface is uniform and has good performance. It effectively improves efficiency, reduces process flow, and controls surface size. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a surface photo of the rod initially prepared in Example 1 of the present invention; Figure 2 This is a photo of the surface of the rod after final processing in Example 1 of the present invention. DETAILED DESCRIPTION Example 1

[0014] The GH2696 bar is selected, which contains, 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.

[0015] The initial GH2696 billet was made into a bar with a specification of 35 mm. The surface photo is shown in the figure. Figure 1 As shown, the following steps are performed on it: Cold drawing is performed to round the diameter to 33mm, and then the peeling specification is Ф31mm. Then, the solution is solidified by oil cooling after keeping at 1100℃ for 2h, and then the first hexagonal cold drawing is performed to S1 of 28.5mm, and then the first electrical annealing is performed by water cooling at 1040℃, and then the second hexagonal cold drawing is performed to S2 of 26.5mm, and then the second electrical annealing is performed by water cooling at 1040℃, and then the first pickling is performed to remove the surface oxide layer, and then the third finished hexagonal cold drawing is performed to S3 of 25mm, and then the third electrical annealing is performed by water cooling at 1040℃, and finally the finished product is pickled to a smooth surface. The final product performance is qualified, the final product edge distance is 25 (-0.04~-0.02) mm, and the dimensional accuracy level meets the h9 requirements. The final product photo is as follows Figure 2 shown. Example 2

[0016] The high temperature alloy hexagonal bars are prepared by cold drawing as follows: Step 1: hot rolling the base bar into a round bar, the size of the round bar is at least 30% larger than the finished product size; Step 2: Cold drawing to round, the deformation is 10-12%; the bar specification t0 after cold drawing is 0.9-0.96 of the bar diameter; Step 3: Peeling treatment, remove the oxide scale, folds, steps and other defects on the surface of the bar, peeling thickness 0.5-1mm; Step 4: Solution treatment: the rod obtained in step 3 is kept at 1000°C-1100°C for 2 hours, and then solution treated by oil cooling; Step 5: The first hexagonal cold drawing treatment, the deformation is controlled at 5-10%, and the treated bar s1=(1.15-1.2)s, where s refers to the distance across the flats of the initial hexagonal bar, and s1 is the distance across the flats of the bar after the first hexagonal cold drawing treatment; Step 6: The first electrical annealing process is as follows: the bar is heated to 1040°C within 40-60 seconds and then immediately cooled with water; Step 7: The second hexagonal cold drawing treatment, the deformation is controlled at 5-10%, and the specification is s2=(1.05-1.08)s, where s refers to the distance across the flats of the initial hexagonal bar, and s2 refers to the distance across the flats of the bar after the second hexagonal cold drawing treatment; Step 8: The second electrical annealing process is as follows: the rod is heated to 1040°C within 40-60 seconds and then immediately cooled with water; Step 9: The first pickling treatment is to remove the oxide scale of the bar; Step 10: The third hexagonal cold drawing process uses a polycrystalline mold, the mold selection has a negative tolerance of 0-0.02, and the cold drawing strictly controls the size; Step 11: The third electrical annealing process is as follows: the rod is heated to 1040°C within 40-60 seconds and then immediately cooled with water; Step 12: Cut and straighten the head, cut off the drawing head and tail, and use a cantilever straightening machine with a hexagonal pressure wheel to straighten; Step 13: A second pickling treatment is performed to remove all surface impurities and finally complete the product processing.

[0017] Furthermore, the composition of the high-temperature alloy hexagonal rod 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.

[0018] Preferably, the hot rolling process in step 1 is: heating first, then rolling, and finally cooling, the rolling temperature is 1080-1100°C, and the final rolling temperature is ≥900°C.

[0019] The oil cooling in step 4 means that after the solutionizing is completed, the material is immediately immersed in oil for cooling to achieve good material properties.

[0020] The process flow of hexagonal cold drawing in step 5 is as follows: rolling head → surface lubrication → drawing; the drawing rate is 1m~2m / min, and the mold surface should be mirror-smooth and free of any defects before and after drawing; after drawing, check whether the material surface is rough and perform grinding and polishing in time.

[0021] The acid used in the pickling treatment in step 9 is composed of: 2.5 parts of hydrofluoric acid, 12 parts of nitric acid, 2 parts of citric acid, 1.5 parts of sulfuric acid and 1 part of a surfactant; The acid used in the pickling treatment in step 13 is composed of: 3.5 parts of hydrofluoric acid, 10 parts of nitric acid, 2 parts of citric acid, 1.5 parts of sulfuric acid and 1 part of a surfactant.

[0022] In step 6, the electrical annealing is a method of heating the workpiece by resistance heat, and the temperature is monitored by high-temperature infrared temperature measurement.

Claims

1. A method for 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, wherein the size of the round bar is at least 30% larger than the size of the finished product; Step 2: Cold drawing to round, the deformation is 10-12%; the bar specification t0 after cold drawing is 0.9-0.96 of the base bar diameter; Step 3: Peel the bar obtained in step 2 to a thickness of 0.5-1 mm; Step 4: Solution treatment: the rod obtained in step 3 is kept at 1000°C-1100°C for 2 hours, and then solution treated by oil cooling; Step 5: The first hexagonal cold drawing treatment, the deformation is controlled at 5-10%, and the treated bar s1=(1.15-1.2)s, where s refers to the distance across the flats of the initial hexagonal bar, and s1 is the distance across the flats of the bar after the first hexagonal cold drawing treatment; Step 6: The first electrical annealing process is as follows: the bar is heated to 1040°C within 40-60 seconds and then immediately cooled with water; Step 7: The second hexagonal cold drawing treatment, the deformation is controlled at 5-10%, and the specification is s2=(1.05-1.08)s, where s refers to the distance across the flats of the initial hexagonal bar, and s2 refers to the distance across the flats of the bar after the second hexagonal cold drawing treatment; Step 8: The second electrical annealing process is as follows: the rod is heated to 1040°C within 40-60 seconds and then immediately cooled with water; Step 9: The first pickling treatment is to remove the oxide scale of the bar; Step 10: The third hexagonal cold drawing process uses a polycrystalline mold, the mold selection has a negative tolerance of 0-0.02, and the cold drawing strictly controls the size; Step 11: The third electrical annealing process is as follows: the rod is heated to 1040°C within 40-60 seconds and then immediately cooled with water; Step 12: Cut and straighten the head, cut off the drawing head and tail, and use a cantilever straightening machine with a hexagonal pressure wheel to straighten; Step 13: A second pickling treatment is performed to remove all surface impurities and finally complete the product processing.

2. The method for cold drawing a high-temperature alloy hexagonal bar according to claim 1, characterized in that: The compositions of the high-temperature alloy hexagonal bar are 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.

3. The method for cold drawing a high-temperature alloy hexagonal bar according to claim 1, characterized in that: The hot rolling process in step 1 is: heating first, then rolling, and finally cooling, the rolling temperature is 1080-1100°C, and the final rolling temperature is ≥900°C.

4. The method for cold drawing a high-temperature alloy hexagonal bar according to claim 1, characterized in that: The oil cooling in step 4 means that after the solutionizing is completed, the material is immediately immersed in oil for cooling to achieve good material properties.

5. The method for cold drawing a high-temperature alloy hexagonal bar according to claim 1, characterized in that: The process flow of hexagonal cold drawing in step 5 is as follows: first rolling the head, then surface lubrication, and finally drawing; the drawing rate is 1-2m / min, and the mold surface should be mirror-smooth and free of any defects before and after drawing; after drawing, check whether the material surface is rough and perform grinding and polishing in time.

6. The method for cold drawing a high-temperature alloy hexagonal bar according to claim 1, characterized in that: The acid used in the pickling treatment in step 9 is composed of: 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 for cold drawing a high-temperature alloy hexagonal bar according to claim 1, characterized in that: The acid used in the pickling treatment in step 13 is composed of: 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.

8. The method for cold drawing a high-temperature alloy hexagonal bar according to claim 1, characterized in that: The electrical 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 obtained by the method of claim 1, characterized in that: Its surface accuracy grade reaches h9 and above.

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