Pure nickel tube plate forging method
Through multi-stage forging methods and optimized annealing conditions, the problem of low strength of pure nickel electroslag ingots is solved, significantly improving the strength and hardness of the forgings, and meeting the needs of high strength and high hardness.
Patent Information
- Application Number
- CN202411608080.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-12
- Publication Date
- 2025-02-18
AI Technical Summary
The strength of pure nickel electroslag ingots is low and it is difficult to significantly improve by conventional methods.
A multi-stage forging method, including sawing, heating, rolling ingot, upsetting and upsetting, combined with spinning and annealing steps, improve the strength and hardness of the forging by increasing the forging deformation and optimizing the annealing conditions. .
The tensile strength, yield strength and hardness of pure nickel pipe sheets have been significantly improved, and the tensile strength ≥380Mpa, yield strength ≥105Mpa and hardness are HRB60~90.
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Figure CN119456898A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of tube sheet forging, in particular to a pure nickel tube sheet forging method. Background Art
[0002] The raw materials for tube sheet forging are usually forged rounds, which have high procurement costs, many raw material production processes, and long production cycles. The use of electroslag ingot forging can reduce the raw material manufacturing cycle and improve production efficiency.
[0003] The electroslag ingot of pure nickel material is a pure austenite structure, and has no trace elements of strengthening phase, so it is difficult to improve the strength. Therefore, it is necessary to design a tube sheet forging method suitable for pure nickel electroslag ingot.
[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention
[0005] In view of the shortcomings of the prior art, the embodiment of the present invention discloses a pure nickel tube sheet forging method to solve the problem of low strength of the pure nickel tube sheet.
[0006] The technical solution adopted by the present invention is as follows:
[0007] The pure nickel tube sheet forging method comprises the following steps: sawing the electrode plate end and the feeding end of the electroslag ingot; heating; forging: rolling the ingot body; performing two upsetting and drawing, followed by a third upsetting and spinning; cooling after forging; annealing; wherein the chemical composition of the electroslag ingot is calculated by weight percentage as follows: Ni: ≥99.0%; Cu≤0.25%; Fe≤0.40%; Mn≤0.35%; C≤0.15%; Si≤0.35%; S≤0.01%. Specifically, in order to meet the standard, C: 0.04-0.15% is used to improve the strength and hardness. The rolling of the ingot body ensures that the surface wrinkles are flattened to avoid folding during the later upsetting.
[0008] A further technical solution is that the upsetting ratio is 1.5 to 2 each time, and the drawing ratio is 1.5 to 2 each time. The upsetting ratio is the ratio of the height of the electroslag ingot before upsetting to the height of the electroslag ingot after upsetting, and the drawing ratio is the ratio of the cross-sectional area before drawing to the cross-sectional area after drawing. The forging deformation is increased by three upsettings and two drawing, and the strain is increased, and the strength is increased.
[0009] A further technical solution is that the heating step includes: the charging temperature of the electroslag ingot is ≤300°C, heating to 700-800°C, the holding time is calculated as 0.35-0.45min / mm, and then heating to 1035-1065°C, the holding time is calculated as 0.85-0.95mim / mm.
[0010] A further technical solution is that after the first upsetting, the electroslag ingot is rounded and returned to the furnace for insulation. The insulation time is calculated as 0.35-0.45 min / mm and the insulation temperature is 1035-1065°C. After subsequent upsetting, the ingot is rounded and the insulation temperature is reduced to 900-950°C.
[0011] A further technical solution is that the post-forging cooling step includes: immediate water cooling, with the water temperature ≤40°C, which is continued until the surface temperature of the electroslag ingot is measured to be ≤100°C 10 minutes after it leaves the quenching tank, to obtain a forging.
[0012] A further technical solution is that the annealing step includes: the forging furnace charging temperature is ≤300°C, the annealing temperature is set at 650-750°C, the insulation time is 2-4h, and air cooling to room temperature.
[0013] A further technical solution is that after the annealing step, the method further comprises the following steps:
[0014] Sampling: Take a sampling ring according to the outer circle of the tube sheet;
[0015] Physical and chemical: Testing the mechanical properties, grain size and hardness of forgings;
[0016] Rough turning: expose all four sides to light, leaving enough margin for later processing to the finished product size;
[0017] Ultrasonic flaw detection: 100% flaw detection in accordance with NB / T 47013.3-2015, meeting level I flaw detection requirements;
[0018] Finished product processing.
[0019] A further technical solution is to obtain forgings with a tensile strength of ≥380Mpa, a yield strength of ≥105Mpa, an elongation of ≥40%, and a hardness of HRB60-90.
[0020] The beneficial effects of the embodiments of the present invention are as follows:
[0021] (I) The pure nickel tube sheet forging method of the present invention comprises the following steps: sawing the electrode plate end and the feeding end of the electroslag ingot; heating; forging: rolling the ingot body; performing two upsetting and drawing, followed by a third upsetting and spinning; cooling after forging; annealing. By using electroslag ingot as the raw material, there are fewer non-metallic inclusions and harmful elements, reducing the phenomenon of component segregation, and having good grain uniformity. At the same time, the content of C element in the raw material is increased, which can increase the strength and hardness of the forging. The tensile strength of the forging is ≥380Mpa, the yield strength is ≥105Mpa, and the hardness is HRB60-90.
[0022] (ii) Furthermore, during forging of the pure nickel tube sheet, two upsetting processes are performed, followed by a third upsetting process followed by spinning, which increases the forging deformation, increases the strain, refines the grains, increases the strength and toughness, and the elongation of the forging is ≥40%.
[0023] (iii) Furthermore, during annealing, the temperature is raised to 650-750°C and kept at this temperature for 2-4 hours to avoid excessive reduction of dislocation density due to excessive temperature and to ensure the strength of the forging. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 The present invention is a flow chart of the pure nickel tube sheet forging method.
[0025] Figure 2 This is a grain map of the pure nickel tube sheet produced according to the first embodiment of the present invention.
[0026] Figure 3 This is a grain map of a pure nickel tube sheet made according to the second embodiment of the present invention.
[0027] Figure 4 This is a grain map of a pure nickel tube sheet made according to the third embodiment of the present invention. DETAILED DESCRIPTION
[0028] The specific implementation of the present invention is described below in conjunction with the accompanying drawings.
[0029] In order to make the purpose, technical scheme and advantages of the present invention clearer, the device proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings adopt a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structure, proportion, size, etc. illustrated by the accompanying drawings of this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effect that the present invention can produce and the purpose that can be achieved, should still fall within the scope of the technical content disclosed by the present invention.
[0030] First embodiment:
[0031] The pure nickel tube sheet forging method comprises the following steps:
[0032] Step S1, sawing the electrode plate end and the feeding end of the electroslag ingot.
[0033] Specifically, pure nickel electroslag ingots are prepared according to the ratio, and the smelting method is vacuum induction melting + electroslag remelting. The chemical composition of the electroslag ingot is calculated by weight percentage: Ni: ≥99.0%; Cu≤0.25%; Fe≤0.40%; Mn≤0.35%; C: 0.04%≤0.15%; Si≤0.35%; S≤0.01%. The electrode plate end and the feeding end of the electroslag ingot are cut off along the dividing line, and the cutting amount of the feeding end is 3% to 5%.
[0034] Step S2, heating.
[0035] Specifically, the heating steps include: the charging temperature of the electroslag ingot is ≤300°C, the temperature is increased to 750°C at a power of ≤100°C / h, the holding time is calculated based on the maximum effective cross-sectional diameter of the electroslag ingot × 0.4min / mm, and then the temperature is increased to 1050°C, and the holding time is calculated based on the maximum effective cross-sectional diameter of the electroslag ingot × 0.9mim / mm.
[0036] Step S3, forging.
[0037] Step S31, rolling the ingot body.
[0038] Step S32, performing two upsetting operations, followed by a third upsetting operation and then spinning.
[0039] Specifically, the upsetting ratio is 1.5 to 2 each time, and the drawing ratio is 1.5 to 2 each time. After the first upsetting, the electroslag ingot is rounded and returned to the furnace for insulation. The insulation time is the maximum effective cross-sectional diameter of the electroslag ingot × 0.4min / mm, and the insulation temperature is 1050°C. After subsequent upsetting, the ingot is rounded and the insulation temperature is reduced to 925°C.
[0040] Step S33, cooling after forging.
[0041] Specifically, the post-forging cooling step includes: immediate water cooling, with the water temperature being ≤40°C, and continuing until the surface temperature of the electroslag ingot is measured to be ≤100°C 10 minutes after it leaves the quenching tank, to obtain a forging.
[0042] Step S4, annealing.
[0043] Specifically, the annealing step includes: the forging charging temperature is ≤300°C, the annealing temperature is set to 700°C, the holding time is 3h, and the forging is cooled to room temperature in air. The heat treatment is carried out in an AMS2750 level 2 or above electric furnace, and a thermocouple is loaded on the surface of the forging to ensure that the forging is heated evenly during the heat treatment process.
[0044] Step S5, sampling: taking a sampling ring according to the outer circle of the tube sheet.
[0045] Step S6, physical and chemical: testing the mechanical properties, grain size and hardness of the forgings.
[0046] Step S7, rough turning: polish all four sides, leaving enough margin for later processing to the finished product size.
[0047] Step S8, ultrasonic flaw detection: 100% flaw detection according to NB / T 47013.3-2015, meeting level I flaw detection requirements.
[0048] Step S9, finished product processing.
[0049] Second embodiment:
[0050] The pure nickel tube sheet forging method comprises the following steps:
[0051] Step S1, sawing the electrode plate end and the feeding end of the electroslag ingot.
[0052] Specifically, a pure nickel electroslag ingot is prepared according to the ratio, and the chemical composition of the electroslag ingot is calculated by weight percentage as follows: Ni: ≥99.0%; Cu≤0.25%; Fe≤0.40%; Mn≤0.35%; C: 0.04%≤0.15%; Si≤0.35%; S≤0.01%. The electrode plate end and the feeding end of the electroslag ingot are cut off along the dividing line, and the cutting amount of the feeding end is 3% to 5%.
[0053] Step S2, heating.
[0054] Specifically, the heating steps include: the charging temperature of the electroslag ingot is ≤300°C, the temperature is increased to 800°C at a power of ≤100°C / h, the holding time is calculated based on the maximum effective cross-sectional diameter of the electroslag ingot × 0.35min / mm, and then the temperature is increased to 1065°C, and the holding time is calculated based on the maximum effective cross-sectional diameter of the electroslag ingot × 0.85mim / mm.
[0055] Step S3, forging.
[0056] Step S31, rolling the ingot body.
[0057] Step S32, performing two upsetting operations, followed by a third upsetting operation and then spinning.
[0058] Specifically, the upsetting ratio is 1.5 to 2 each time, and the drawing ratio is 1.5 to 2 each time. After the first upsetting, the electroslag ingot is rounded and returned to the furnace for insulation. The insulation time is the maximum effective cross-sectional diameter of the electroslag ingot × 0.35min / mm, and the insulation temperature is 1065°C. After subsequent upsetting, the insulation temperature is reduced to 950°C.
[0059] Step S33, cooling after forging.
[0060] Specifically, the post-forging cooling step includes: water cooling, the water temperature is ≤40°C, and the cooling is continued until the surface temperature of the electroslag ingot is ≤100°C 10 minutes after the ingot leaves the quenching tank, thereby obtaining a forging.
[0061] Step S4, annealing.
[0062] Specifically, the annealing step includes: the forging charging temperature is ≤300°C, the annealing temperature is set to 750°C, the holding time is 2h, and the forging is cooled to room temperature by air. The heat treatment is carried out in an AMS2750 level 2 or above electric furnace, and a thermocouple is loaded on the surface of the forging to ensure that the forging is heated evenly during the heat treatment process.
[0063] Step S5, sampling: sampling a sample ring according to the outer circle of the tube sheet.
[0064] Step S6, physical and chemical: testing the mechanical properties, grain size and hardness of the forgings.
[0065] Step S7, rough turning: polish all four sides, leaving enough margin for later processing to the finished product size.
[0066] Step S8, ultrasonic flaw detection: 100% flaw detection according to NB / T 47013.3-2015, meeting level I flaw detection requirements.
[0067] Step S9, finished product processing.
[0068] Third embodiment:
[0069] The pure nickel tube sheet forging method comprises the following steps:
[0070] Step S1, sawing the electrode plate end and the feeding end of the electroslag ingot.
[0071] Specifically, a pure nickel electroslag ingot is prepared according to the ratio, and the chemical composition of the electroslag ingot is calculated by weight percentage as follows: Ni: ≥99.0%; Cu≤0.25%; Fe≤0.40%; Mn≤0.35%; C: 0.04%≤0.15%; Si≤0.35%; S≤0.01%. The electrode plate end and the feeding end of the electroslag ingot are cut off along the dividing line, and the cutting amount of the feeding end is 3% to 5%.
[0072] Step S2, heating.
[0073] Specifically, the heating steps include: the charging temperature of the electroslag ingot is ≤300°C, the temperature is increased to 700°C at a power of ≤100°C / h, the holding time is calculated based on the maximum effective cross-sectional diameter of the electroslag ingot × 0.45min / mm, and then the temperature is increased to 1035°C, and the holding time is calculated based on the maximum effective cross-sectional diameter of the electroslag ingot × 0.95mim / mm.
[0074] Step S3, forging.
[0075] Step S31, rolling the ingot body.
[0076] Step S32, performing two upsetting operations, followed by a third upsetting operation and then spinning.
[0077] Specifically, the upsetting ratio is 1.5 to 2 each time, and the drawing ratio is 1.5 to 2 each time. After the first upsetting, the electroslag ingot is rounded and returned to the furnace for insulation. The insulation time is the maximum effective cross-sectional diameter of the electroslag ingot × 0.45min / mm, and the insulation temperature is 1035°C. After subsequent upsetting, the insulation temperature is reduced to 900°C.
[0078] Step S33, cooling after forging.
[0079] Specifically, the post-forging cooling step includes: water cooling, the water temperature is ≤40°C, and the cooling is continued until the surface temperature of the electroslag ingot is ≤100°C 10 minutes after the ingot leaves the quenching tank, thereby obtaining a forging.
[0080] Step S4, annealing.
[0081] Specifically, the annealing step includes: the forging charging temperature is ≤300°C, the annealing temperature is set to 650°C, the holding time is 4 hours, and the forging is cooled to room temperature in air. The heat treatment is carried out in an AMS2750 level 2 or above electric furnace, and a thermocouple is loaded on the surface of the forging to ensure that the forging is heated evenly during the heat treatment process.
[0082] Step S5, sampling: taking a sampling ring according to the outer circle of the tube sheet.
[0083] Step S6, physical and chemical: testing the mechanical properties, grain size and hardness of the forgings.
[0084] Step S7, rough turning: polish all four sides, leaving enough margin for later processing to the finished product size.
[0085] Step S8, ultrasonic flaw detection: 100% flaw detection according to NB / T 47013.3-2015, meeting level I flaw detection requirements.
[0086] Step S9, finished product processing.
[0087] Test example
[0088] For the forgings obtained in the first embodiment, the second embodiment and the third embodiment, a sample ring of 25 mm*25 mm was taken from the outer circumference of the forging, and samples were selected from random positions of the sample ring for testing. The test results are shown in Table 1.
[0089] Table 1
[0090]
[0091] The test method is as follows:
[0092] Tensile strength, yield strength, elongation: The test standard adopts E8 "Test method for tensile test of metallic materials"; the equipment adopts microcomputer-controlled electronic universal testing machine E45.305 and electronic extensometer Y50 / 10-N.
[0093] Hardness HRB: The test standard adopts ASTM E18 "Rockwell hardness test method for metallic materials", and the equipment used is Rockwell hardness tester AT350 DR-TM.
[0094] Grain size: The test standard adopts ASTM E112 "Test method for determination of average grain size", and the equipment used is Zeiss metallographic microscope AXio vertA1.
[0095] Non-metallic inclusions: The test standard adopts ASTM E45 "Evaluation method for inclusion content in steel", and the equipment uses Zeiss metallographic microscope AXio vertA1.
[0096] Intergranular corrosion: Using the ASTM A262-E method, observe the curved outer surface through a 10X microscope to see if there are cracks caused by intergranular corrosion.
[0097] It can be seen that the pure nickel tube sheet produced by the pure nickel tube sheet forging method of the present invention has good mechanical properties and has high strength, hardness and toughness.
[0098] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0099] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.
Claims
1. A pure nickel tube sheet forging method, characterized in that: The following steps are involved: Sawing the electrode plate end and feeding end of electroslag ingot; heating; forging: rolling spindle body; Two upsetting passes were performed, followed by a third upsetting pass and then spinning; Cooling after forging; annealing; The chemical composition of the electroslag ingot is calculated by weight as follows: Ni: ≥99.0%; Cu≤0.25%; Fe≤0.40%; Mn≤0.35%; C≤0.15%; Si≤0.35%; S≤0.01％。 2. The pure nickel tube sheet forging method according to claim 1, characterized in that: The upsetting ratio is 1.5 to 2 each time, and the drawing ratio is 1.5 to 2 each time.
3. The pure nickel tube sheet forging method according to claim 1, characterized in that: The heating step includes: the charging temperature of the electroslag ingot is ≤300°C, heating to 700-800°C, the holding time is calculated as 0.35-0.45min / mm, and then heating to 1035-1065°C, the holding time is calculated as 0.85-0.95mim / mm.
4. The pure nickel tube sheet forging method according to claim 3, characterized in that: After the first upsetting, the electroslag ingot is rounded and returned to the furnace for insulation. The insulation time is calculated as 0.35-0.45 min / mm and the insulation temperature is 1035-1065°C. After subsequent upsetting and rounding, the insulation temperature is reduced to 900-950°C.
5. The pure nickel tube sheet forging method according to claim 1, characterized in that: The post-forging cooling step comprises: Immediately water cool with the water temperature ≤40℃ and continue until the surface temperature of the electroslag ingot is ≤100℃ 10 minutes after it leaves the quenching tank to obtain the forging.
6. The pure nickel tube sheet forging method according to claim 1, characterized in that: The annealing step comprises: the forging furnace charging temperature is ≤300°C, the annealing temperature is set to 650-750°C, the heat preservation time is 2-4h, and air cooling to room temperature.
7. The pure nickel tube sheet forging method according to claim 1, characterized in that: After the annealing step, the step further includes: Sampling: Take a sampling ring according to the outer circle of the tube sheet; Physical and chemical: testing the mechanical properties, grain size and hardness of forgings; Rough turning: expose all four sides to light, leaving enough margin for later processing to the finished product size; Ultrasonic flaw detection: 100% flaw detection in accordance with NB / T 47013.3-2015, meeting level I flaw detection requirements; Finished product processing.
8. The pure nickel tube sheet forging method according to claim 1, characterized in that: The obtained forging has a tensile strength of ≥380Mpa, a yield strength of ≥105Mpa, an elongation of ≥40%, and a hardness of HRB60-90.