Nickel-based alloy and preparation method thereof

Abstract

The invention discloses a preparation method of a nickel-based alloy N04400, the nickel-based alloy N04400 comprises 28.0-34.0 wt% of Cu, less than or equal to 2.5 wt% of Fe, less than or equal to 2.0 wt% of Mn, less than or equal to 0.3 wt% of C, less than or equal to 0.5 wt% of Si, less than or equal to 0.024 wt% of S and the balance of Ni, the hardness of the alloy is HRC20-24 (226-247HB), the grain size of the alloy is grade 7 or finer, Rm is greater than or equal to 760 MPa, Rp0.2 is greater than or equal to 585 MPa, the 4D ductility is greater than or equal to 12%, and non-metallic inclusions are all less than grade 1. The preparation process comprises the following steps: firstly, eliminating the internal stress of the material through annealing to achieve the purpose of softening; the softening is used for realizing drawing (the hard drawing is easy to break or crack); and the final performance of the material is realized by controlling certain drawing deformation.

Description

Technical Field

[0001] The present invention relates to the field of alloy manufacturing, and particularly to a nickel-based alloy and a preparation method thereof. Background Art

[0002] Monel400 (UNS N04400) alloy is a nickel-based corrosion-resistant alloy with strong corrosion resistance, and is used in chemical industry, ocean engineering and high-temperature environments, such as pumps, valves, impeller shafts, fixtures and fasteners of heat exchangers, seawater desalination devices, high-temperature gas treatment equipment, and power and electronic components.

[0003] Due to the high copper content, the Monel400 material is relatively soft, usually with a hardness of 130 HB in the rolled state and only 110 HB in the annealed state.

[0004] Chinese Patent No. 201110340579.2 discloses a processing technology method for a corrosion-resistant copper-zinc-aluminum alloy material, which uses a copper-zinc brass alloy as the matrix, and by adding elements such as zinc, aluminum, nickel, silicon, boron, manganese, rare earth, etc., achieves the purposes of high wear resistance, high corrosion resistance, high temperature resistance and good processing performance, meeting the requirements of materials for the marine development and utilization industry, seawater desalination heat exchange and other special industries; saving energy and reducing production costs. Using a copper-zinc brass alloy as the matrix, nickel, iron, lead, silicon, manganese, aluminum, zinc, boron, at least one of elemental rare earth lanthanum and elemental rare earth cerium or mixed rare earth is added in sequence, and it is completed through batching → melting and casting → sawing → heating → hot rolling → milling → cold rough rolling → annealing → finished product rolling → finished product annealing → shearing → packaging and warehousing. If the product requirement is in the hard state, finished product annealing is not carried out; it can produce corrosion-resistant copper-zinc-aluminum alloy material strip and sheet, and the key lies in melting and casting, heating and hot rolling; the processing technology is less difficult, the method is simple, labor-saving and time-saving; it is convenient to promote.

[0005] The traditional N04400 processing technology uses direct drawing in the hot-rolled state. The main problem is that the material properties in the rolled state are uncontrollable, and the change of temperature during the rolling process leads to large changes in material properties. For different batches of rolling, it is impossible to achieve qualified finished product properties according to the same cold drawing process. For the same drawing deformation amount, the strength and hardness of the drawing results are high and low, and a stable process cannot be obtained. Summary of the Invention

[0006] In order to overcome the deficiency that alloys with a relatively high copper content in the prior art are relatively soft, usually with a hardness of 130 HB in the rolled state and only 110 HB in the annealed state, and cannot meet the requirements of the hardened state, the present invention provides a nickel-based alloy with a relatively high copper content and relatively high hardness and a preparation method thereof. The specific technical solutions are as follows: The first technical solution provided by the present invention is: a nickel-based alloy, whose composition is: Cu: 28.0 - 34.0 wt%, Fe ≤ 2.5 wt%, Mn ≤ 2.0 wt%, C ≤ 0.3 wt%, Si ≤ 0.5 wt%, S ≤ 0.024 wt% and the balance Ni, and the hardness of this alloy is 226 - 257 HB. The hardness of this alloy can be 226 HB or 230 HB or 235 HB or 240 HB or 245 HB or 250 HB or 255 HB or 257 HB or the range or sub-range between any two values.

[0007] Furthermore, the grain size of the alloy is grade 7 or finer, Rm ≥ 760 MPa, Rp0.2 ≥ 585 MPa, the 4D elongation rate is ≥ 12%, and the non-metallic inclusions are all less than grade 1. Wherein Rm is the tensile strength; Rp0.2 is the yield strength.

[0008] The present invention also provides a preparation method of the aforementioned nickel-based alloy, and the detailed steps of this method are as follows: Step 1: Obtain a basic bar through vacuum induction and electroslag remelting processes for the raw materials, and then perform hot rolling on the basic bar to form a round bar. The size of the round bar after hot rolling ≥ (finished product size + 0.5) x 1.24 (mm). According to the performance requirements of the material, the deformation amount is inversely deduced to calculate the hot rolling size; Step 2: Perform solution annealing treatment on the round bar obtained in Step 1. The annealing temperature is controlled at 600 °C - 800 °C, the annealing time is 30 min - 60 min, and then water cooling is carried out; Step 3: Cold draw the bar obtained in Step 2 through a die, and adopt segmented cold drawing: for the first cold draw, control the deformation amount at 20% - 25%, and then perform the second cold draw with a deformation amount of 15% - 20%. The total deformation amount is controlled at 33 - 38%. The total deformation amount = (initial diameter) 2 / (final diameter after cold drawing) 2 .

[0009] Preferably, it further includes Step 4: straighten and polish the bar obtained in Step 3.

[0010] Furthermore, the composition of the raw materials in Step 1 is: Cu: 28.0 - 34.0 wt%, Fe ≤ 2.5 wt%, Mn ≤ 2.0 wt%, C ≤ 0.3 wt%, Si ≤ 0.5 wt%, S ≤ 0.024 wt% and the balance Ni.

[0011] Even further, the grain size of the basic bar in Step 1 is grade 4 or finer; the requirements for non-metallic inclusions are: A, B, C, D are respectively not greater than grade 2, and A + B + C + D ≤ 4.0.

[0012] The principle of the present invention is to first eliminate the internal stress of the material through annealing to achieve the purpose of softening; softening is to enable drawing (hard drawing is prone to breakage or cracks); and the final properties of the material are achieved by controlling a certain amount of drawing deformation. It overcomes the problems in the prior art that the properties of as-rolled materials are uncontrollable, the properties of materials change greatly due to the temperature change during the rolling process, and for different batches of rolling, qualified finished product properties cannot be achieved according to the same cold drawing process. With the same drawing deformation amount, the strength and hardness of the drawing results fluctuate, and a stable process cannot be obtained. Through solution softening and setting a reasonable deformation amount, a stable processing process can ultimately be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the metallographic photograph of the alloy product prepared in Example 1 of the present invention; Figure 2 It is the hardness test result diagram of the alloy product prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS Example 1

[0014] Step 1: Prepare raw materials according to the following requirements: Cu: 28.0 - 34.0 wt%, Fe ≤ 2.5 wt%, Mn ≤ 2.0 wt%, C ≤ 0.3 wt%, Si ≤ 0.5 wt%, S ≤ 0.024 wt% and the balance Ni. The raw materials are successively made into a basic bar through vacuum induction and electroslag remelting processes, and then the basic bar is hot-rolled into a round bar. The diameter of the hot-rolled round bar is 13 mm. Requirements for the grain size grade and non-metallic inclusions of the basic bar: Grain size: Grade 4 or finer; Requirements for non-metallic inclusions: A, B, C, and D are not more than Grade 2 respectively, and A + B + C + D ≤ 4; Step 2: Perform solution annealing treatment on the round bar obtained in Step 1. The annealing temperature is controlled at 750 °C, the annealing time is 30 min, and then water cooling is carried out, and it is charged into the furnace when reaching the temperature; Step 3: Cold draw the bar obtained in Step 2 through a die, adopting segmented cold drawing: For the first cold drawing, the diameter of the bar after the first drawing is 11.5 mm, and then for the second cold drawing, the diameter of the bar after the second drawing is 10.5 mm.

[0015] Step 4: Straighten the bar obtained in Step 3 and polish it to a bar diameter of 10 mm. Characterize and test the prepared finished product, Figure 1 It is the metallographic photograph of the product prepared in this example, from Figure 1 it can be seen that the grain size of this alloy is Grade 9; hardness and tensile tests are carried out on the prepared finished product. The test conditions are Wilson VH3100 automatic Vickers / Knoop hardness tester and Instron 5982 tensile testing machine, and the test results are as Figure 2As shown, the measured hardness is 243 HB (HRC 21.1), Rm = 770 MPa, Rp0.2 = 691 MPa, 4D elongation = 17.5%, and non-metallic inclusions are all less than grade 1. Example 2

[0016] Step 1: Prepare raw materials according to the following requirements: Cu: 34 wt%, Fe: 2.5 wt%, Mn: 2.0 wt%, C: 0.3 wt%, Si: 0.5 wt%, S: 0.02 wt%, and the balance Ni. The raw materials are successively processed by vacuum induction and electroslag remelting processes to obtain a basic bar, and then the basic bar is hot-rolled into a round bar. The size of the hot-rolled round bar is 15 mm in diameter. Requirements for the grain size grade and non-metallic inclusions of the basic bar: Grain size: grade 4; Requirements for non-metallic inclusions: A, B, C, and D are respectively not greater than grade 2, and A + B + C + D ≤ 4; Step 2: The round bar obtained in Step 1 is subjected to solution annealing treatment. The annealing temperature is controlled at 700 °C, and the annealing time is 45 min, and then water cooling is carried out, and it is charged into the furnace when reaching the temperature; Step 3: The bar obtained in Step 2 is cold drawn through a die, and segmented cold drawing is adopted: The first cold drawing, the diameter of the bar after the first drawing is 13.5 mm, and then the second cold drawing is carried out, and the diameter of the bar after the second drawing is 12 mm.

[0017] Step 4: The bar obtained in Step 3 is straightened and polished to a diameter of 11.5 mm.

[0018] The obtained finished product is characterized and tested. The grain size of this alloy is grade 9; The hardness of the obtained finished product is tested under the conditions of a Wilson VH3100 automatic Vickers / Knoop hardness tester and an Instron 5982 tensile testing machine. The measured hardness is 238.3 HB (HRC 22.1), Rm = 783 MPa, Rp0.2 = 705 MPa, 4D elongation = 15%, and non-metallic inclusions are all less than grade 1. Example 3

[0019] Step 1: Prepare raw materials according to the following requirements: Cu: 28.0 wt%, Fe: 1.5 wt%, Mn: 1 wt%, C: 0.1 wt%, Si: 0.1 wt%, and the balance Ni. The raw materials are successively processed by vacuum induction and electroslag remelting processes to obtain a basic bar, and then the basic bar is hot-rolled into a round bar. The size of the hot-rolled round bar is 13 mm in diameter. Requirements for the grain size grade and non-metallic inclusions of the basic bar: Grain size: grade 4 or finer; Requirements for non-metallic inclusions: A, B, C, and D are respectively not greater than grade 2, and A + B + C + D = 3; Step 2: Solution annealing treatment is carried out on the round bar obtained in Step 1. The annealing temperature is controlled at 650 °C, the annealing time is 60 min, and then water cooling is carried out. After reaching the temperature, it is charged into the furnace. Step 3: Cold drawing is carried out on the bar obtained in Step 2 through a die, and segmented cold drawing is adopted: the first cold drawing, the diameter of the bar after the first drawing is 11.5 mm, and then the second cold drawing is carried out, and the diameter of the bar after the second drawing is 10.5 mm.

[0020] Step 4: The bar obtained in Step 3 is straightened and polished until the diameter of the bar is 10 mm. The prepared finished product is characterized and tested. The grain size of this alloy is grade 9; hardness and tensile tests are carried out on the prepared finished product. The test conditions are Wilson VH3100 automatic Vickers / Knoop hardness tester and Instron 5982 tensile testing machine. After testing, the hardness is 239 HB (HRC22.5), Rm = 786 MPa, Rp0.2 = 705 MPa, 4D elongation = 14%, and non-metallic inclusions are all less than grade 1. Example 4

[0021] Step 1: Prepare raw materials according to the following requirements: Cu: 30.0 wt%, Fe: 2 wt%, Mn: 1.5 wt%, C: 0.1 wt%, Si: 0.1 wt% and the balance Ni. The raw materials are successively made into a basic bar through vacuum induction and electroslag remelting processes, and then the basic bar is hot-rolled into a round bar. The size of the hot-rolled round bar is 13 mm in diameter. Requirements for the grain size grade and non-metallic inclusions of the basic bar: Grain size: grade 4 or finer; Requirements for non-metallic inclusions: A, B, C, and D are not more than grade 2 respectively, and A + B + C + D = 3. Step 2: Solution annealing treatment is carried out on the round bar obtained in Step 1. The annealing temperature is controlled at 650 °C, the annealing time is 60 min, and then water cooling is carried out. After reaching the temperature, it is charged into the furnace. Step 3: Cold drawing is carried out on the bar obtained in Step 2 through a die, and segmented cold drawing is adopted: the first cold drawing, the diameter of the bar after the first drawing is 11.5 mm, and then the second cold drawing is carried out, and the diameter of the bar after the second drawing is 10.5 mm.

[0022] Step 4: The bar obtained in Step 3 is straightened and polished until the diameter of the bar is 10 mm. The prepared finished product is characterized and tested. The grain size of this alloy is grade 9; hardness and tensile tests are carried out on the prepared finished product. The test conditions are Wilson VH3100 automatic Vickers / Knoop hardness tester and Instron 5982 tensile testing machine. After testing, the hardness is 238 HB (HRC22.5), Rm = 780 MPa, Rp0.2 = 704 MPa, 4D elongation = 14.6%, and non-metallic inclusions are all less than grade 1.

[0023] Comparative Example 1 Step 1: Prepare raw materials as follows: Cu: 28.0 - 34.0 wt%, Fe ≤ 2.5 wt%, Mn ≤ 2.0 wt%, C ≤ 0.3 wt%, Si ≤ 0.5 wt%, S ≤ 0.024 wt% and the balance Ni. The raw materials are successively processed by vacuum induction and electroslag remelting processes to obtain a basic bar, and then the basic bar is hot-rolled into a round bar. The size of the hot-rolled round bar is 13 mm in diameter. Requirements for the grain size grade and non-metallic inclusions of the basic bar: Grain size: Grade 4 or finer; Requirements for non-metallic inclusions: A, B, C, and D are not more than Grade 2 respectively, and A + B + C + D ≤ 4.0; Step 2: Perform solution annealing treatment on the round bar obtained in Step 1. The annealing temperature is controlled at 900 °C, and the annealing time is 30 min. Then water cooling is carried out, and it is charged into the furnace when reaching the temperature; Step 3: Cold draw the bar obtained in Step 2 through a die, adopting segmented cold drawing: The first cold drawing, the diameter of the bar after the first drawing is 11.5 mm, and then the second cold drawing is carried out, and the diameter of the bar after the second drawing is 10.5 mm.

[0024] Characterize and test the obtained finished product. The grain size of this alloy is Grade 4; Perform hardness and tensile tests on the obtained finished product. The test conditions are Wilson VH3100 automatic Vickers / Knoop hardness tester and Instron 5982 tensile testing machine. After testing, the hardness is HRC19, Rm = 656 MPa, Rp0.2 = 538 MPa, and the 4D elongation = 27.5%.

[0025] Comparative Example 2 Step 1: Prepare raw materials as follows: Cu: 28.0 - 34.0 wt%, Fe ≤ 2.5 wt%, Mn ≤ 2.0 wt%, C ≤ 0.3 wt%, Si ≤ 0.5 wt%, S ≤ 0.024 wt% and the balance Ni. The raw materials are successively processed by vacuum induction and electroslag remelting processes to obtain a basic bar, and then the basic bar is hot-rolled into a round bar. The size of the hot-rolled round bar is 13 mm in diameter. Requirements for the grain size grade and non-metallic inclusions of the basic bar: Grain size: Grade 4 or finer; Requirements for non-metallic inclusions: A, B, C, and D are not more than Grade 2 respectively, and A + B + C + D ≤ 4.0; Step 2: Perform solution annealing treatment on the round bar obtained in Step 1. The annealing temperature is controlled at 720 °C, and the annealing time is 30 min. Then water cooling is carried out, and it is charged into the furnace when reaching the temperature; Step 3: Cold draw the bar obtained in Step 2 through a die, using segmented cold drawing: the first cold draw, the diameter of the bar after the first draw is 11 mm, then the second cold draw is carried out, the diameter of the bar after the second draw is 10 mm, and then the third cold draw is carried out, the diameter of the bar after the third draw is 9.5 mm, and the total deformation amount reaches 46.5%.

[0026] Characterize and test the obtained finished product. The grain size of this alloy is Grade 8; hardness and tensile tests are carried out on the obtained finished product. The test conditions are Wilson VH3100 automatic Vickers / Knoop hardness tester and Instron 5982 tensile testing machine. After testing, the hardness is HRC24.5, Rm = 827 MPa, Rp0.2 = 755 MPa, and the 4D elongation rate = 10.5%. As is known in the art, the larger the grain size number of the alloy, the finer it is. In this comparative example, although the grain size of the obtained alloy is relatively fine because the annealing temperature is relatively low, its hardness is too high, cracks will occur, and it cannot meet the use requirements. Moreover, its 4D elongation rate also cannot meet the use requirements, so it is unqualified.

Claims

1. A nickel-based alloy, characterized in that: Its composition is: Cu: 28.0-34.0wt%, Fe≤2.5wt%, Mn≤2.0wt%, C≤0.3wt%, Si≤0.5wt%, S≤0.024wt% and the balance Ni. The hardness of the alloy is 226-247HB.

2. The nickel-based alloy according to claim 1, characterized in that The alloy has a grain size of 7 or finer, Rm≥760MPa, Rp0.2≥585MPa, 4D elongation of ≥12%, and non-metallic inclusions of less than 1 level.

3. The method for preparing a nickel-based alloy according to claim 1 or 2, characterized in that: The following steps are involved: Step 1: The raw materials are subjected to vacuum induction and electroslag remelting processes to obtain basic bars, and then the basic bars are hot-rolled into round bars, with the hot-rolled size ≥ (finished product size + 0.5) x 1.24 (mm); Step 2: subjecting the round rod obtained in step 1 to solution annealing treatment, with the annealing temperature controlled at 600°C to 800°C and the annealing time being 30min to 60min, followed by water cooling; Step 3: The rod obtained in step 2 is cold drawn through a die, using segmented cold drawing: the first cold drawing controls the deformation at 20%-25%, and then the second cold drawing is performed with a deformation of 15%-20%, and the total deformation is controlled at 33-38%.

4. The method for preparing a nickel-based alloy according to claim 3, characterized in that: The method further comprises step 4: straightening and polishing the rod obtained in step 3.

5. The method for preparing a nickel-based alloy according to claim 3, characterized in that: The composition of the raw material in step 1 is: Cu: 28.0-34.0wt%, Fe≤2.5wt%, Mn≤2.0wt%, C≤0.3wt%, Si≤0.5wt%, S≤0.024wt% and the balance Ni.

6. The method for preparing a nickel-based alloy according to claim 3, characterized in that: The grain size of the base rod in step 1 is grade 7 or finer; the non-metallic inclusion requirements are: A, B, C, and D are not greater than grade 2 respectively, and A+B+C+D≤4.

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