A low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel and its preparation process

Abstract

The present application relates to the field of nickel-based welding wires, and specifically discloses a low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel and its preparation process. The preparation process of low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel includes S1 raw material selection; S2 control the vacuum degree of the vacuum induction melting furnace to reach the preset vacuum degree, add carbon particles, polysilicon, electrolytic nickel, metal chromium, molybdenum bars, niobium bars, aluminum particles, and sponge titanium into the vacuum induction melting furnace according to the ratio, and perform at least three refinings; adjust the atmosphere of the melting chamber to an inert gas protective atmosphere, add NiMg alloy and metal yttrium, stir and let stand, tap the steel, and obtain a vacuum ingot; S3 cut off the riser and peel the vacuum ingot, and then forge, roll, and draw to obtain a low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel. The high-temperature alloy welding wire steel of the present application has the advantages of low iron content, low oxygen content, good corrosion resistance, and excellent welding effect.

Description

Technical Field

[0001] The present application relates to the field of nickel-based welding wires, and more specifically, to a low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel and a preparation process thereof. Background Art

[0002] Nickel-based high-temperature alloy welding wire steel is widely used in petrochemical, marine engineering, nuclear power, aerospace and other industries due to its excellent corrosion resistance. It solves engineering corrosion problems that cannot be solved by general stainless steel and other metal and non-metal materials. It is a very important corrosion-resistant metal material. In order to improve the corrosion resistance of welding wire steel materials, the iron content in the welding material must be strictly controlled; in order to reduce or avoid spattering during welding and the formation of pores in the weld, the gas content in the welding wire steel material must be minimized.

[0003] At present, the traditional smelting preparation process in the industry is vacuum induction melting. The iron content in the produced welding materials is usually above 0.2wt%, and the oxygen content is higher than 0.002wt%. The corrosion resistance of nickel-based high-temperature alloy welding wire steel produced by traditional processes will be affected by the iron content. As the iron content in the steel increases, its corrosion resistance will decrease; and the increase in oxygen content in welding wire steel will increase the probability of defects such as pores in the weld after welding, which will have an adverse effect on the application of welding wire and the final weld quality.

[0004] In response to the above-mentioned related technologies, the present invention provides a new type of nickel-based high-temperature alloy welding wire steel with low iron content and low oxygen content and a preparation method thereof, so that the welding wire steel product has higher cleanliness and better corrosion resistance. Summary of the invention

[0005] In order to reduce the iron content and oxygen content of nickel-based alloy welding wire steel, the present application provides a low-iron and low-oxygen nickel-based high-temperature alloy welding wire steel and a preparation process thereof.

[0006] In the first aspect, the present application provides a low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel, which adopts the following technical solution:

[0007] A low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel comprises the following components in mass percentage:

[0008] C≤0.05%, Cr 20-23%, Mo 8.5-9.5%, Nb 3.2-4.0%, Y 0.08-0.4%, Ti≤0.3%, Si≤0.25%, Al≤0.3%, Mn≤0.1%, Fe≤0.03%, S≤0.004%, P≤0.003%, O≤0.001%, N≤0.003%, H≤0.0003%, and the rest are Ni and unavoidable impurities.

[0009] Preferably, the inclusion size of the low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel is less than 15µm, and the average grain size is grade 10.

[0010] In a second aspect, the present application provides a preparation process of low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel, which adopts the following technical solution:

[0011] A preparation process of low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel comprises the following steps:

[0012] S1 Raw material control:

[0013] Select carbon particles, polysilicon, electrolytic nickel, metal chromium, molybdenum bars, niobium bars, aluminum particles, sponge titanium, NiMg alloy, and metal yttrium as raw materials;

[0014] S2 Vacuum Melting

[0015] The vacuum degree of the vacuum induction melting furnace is controlled to reach a preset vacuum degree, and carbon particles, polysilicon, electrolytic nickel, metal chromium, molybdenum bars, niobium bars, aluminum particles, and sponge titanium are added into the vacuum induction melting furnace according to the proportion, and refining is performed at least three times; the atmosphere of the melting chamber is adjusted to an inert gas protective atmosphere, NiMg alloy and metal yttrium are added, stirred and then allowed to stand, and steel is tapped to obtain a vacuum ingot;

[0016] S3 removes the riser and peels the vacuum cast ingot, and then forges, rolls, and draws it into a low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel.

[0017] By adopting the above technical scheme, the entire vacuum melting process is in a vacuum state or inert gas protective atmosphere, which effectively isolates the air and controls the gas content of the material at an extremely low level, ensuring the purity of the molten steel and the performance of the steel. Strict control of the raw materials and precise control of the composition of the molten steel can help reduce the iron content. By adding metallic yttrium, the corrosion resistance and high-temperature oxidation resistance can be further enhanced.

[0018] Preferably, the feeding and distributing principles of the vacuum melting step include:

[0019] 10-30% of the raw material weight of electrolytic nickel is spread on the bottom of the crucible of the vacuum induction melting furnace, and then polysilicon and 45-60% of the raw material weight of carbon particles are added, and then the remaining electrolytic nickel, metal chromium and molybdenum bars are added, and the height of the furnace charge is controlled to the crucible slag line position; the melting chamber is kept in a vacuum state, and niobium bars and remaining carbon are added after the molten steel is melted, and the first refining is carried out after all the materials are melted; aluminum particles and sponge titanium are added after the first refining period is completed; after the three refining periods are completed, the atmosphere in the melting chamber is adjusted to an inert gas protective atmosphere before tapping, and NiMg alloy and metal yttrium are added.

[0020] By adopting the above technical solution and strictly controlling the order of adding materials, the composition of molten steel can be made more uniform, thus ensuring the high quality of vacuum casting ingots.

[0021] Preferably, the three refining steps include:

[0022] The first vacuum refining, refining temperature is 1490±20℃, refining time is 30-40min;

[0023] The second vacuum refining, the refining temperature is 1490±20℃, and the refining time is 40-50min;

[0024] The second vacuum refining is carried out at a refining temperature of 1490±20℃ and a refining time of 20-30min.

[0025] By adopting the above technical solution and controlling the refining temperature, it is ensured that the steel has good fluidity during refining so that inclusions and gases inside the molten steel float up and are removed, while ensuring that the refining temperature is not too high to cause the molten steel to corrode the furnace lining.

[0026] Preferably, the vacuum melting step specifically includes:

[0027] After the vacuum degree of the vacuum induction melting furnace is controlled to reach the preset target, power is supplied at 100-200kW and maintained for 1-1.5h; then the power is increased to 300-400kW and maintained for 1-1.5h, and then the power is increased to 500-800kW to enter the material stage, and after the molten steel is melted, niobium bars and remaining carbon are added, and high power is continued to be maintained until all materials are melted, and the molten steel temperature is adjusted to 1490±20℃, electromagnetic stirring is performed for 2-5min, and the whole molten sample is taken for furnace analysis, the molten steel is kept warm, and the first refining stage is entered, and the refining is performed for 30-40min;

[0028] Cut off the power and set the film for 3-10 minutes, add titanium sponge and aluminum particles, stir for 2-5 minutes after melting, take the sample in front of the furnace for furnace analysis, keep the molten steel warm, enter the second refining stage, and refine for 40-50 minutes;

[0029] According to the analysis results of the furnace sample and the target molten steel composition, the molten steel is fine-tuned; the molten steel is kept warm and enters the third refining stage for 20-30 minutes;

[0030] Adjust the atmosphere in the smelting chamber to an inert gas protective atmosphere, add NiMg alloy and metal yttrium and stir for 5-10 minutes; after stirring, turn off the power and let the molten steel stand for 5-10 minutes; take the sample after the furnace as the ingot composition sample;

[0031] Adjust the steel temperature to the tapping temperature of 1510±10℃, maintain the power supply at 300-400kW, and start casting;

[0032] Adjust the vacuum degree of the ingot mold chamber to meet the set target, and demould to obtain a vacuum ingot.

[0033] By adopting the above technical solution, furnace samples are taken multiple times during the vacuum melting process to conduct component analysis, and the composition of the molten steel is adjusted in time to achieve the purpose of accurately controlling the composition of the molten steel.

[0034] Preferably, after the first refining period, the weight of titanium sponge and aluminum particles to be added is calculated based on the analysis results of the full melt sample, the element internal control indicators, the actual weight of the molten steel and the theoretical furnace charge, and the titanium sponge and aluminum particles are added after the power is turned off and the film is formed.

[0035] Preferably, after the second refining period, the weight of the material that needs to be fine-tuned is calculated based on the analysis results of the furnace sample, the element internal control indicators, the actual weight of the molten steel and the theoretical furnace charge, added to the crucible, stirred for 2-5 minutes, and then the third refining is carried out.

[0036] Preferably, the casting speed is 350-450 kg / min.

[0037] Preferably, the equipment conditions of the vacuum induction melting furnace are: the gas leakage rate of the melting chamber is less than 1.3Pa / min, and the ultimate vacuum value of the melting chamber is lower than 2Pa. The equipment needs to have an inert gas argon atmosphere protection function and a three-phase electromagnetic stirring function.

[0038] In summary, this application has the following beneficial effects:

[0039] 1. The high-temperature alloy welding wire steel of the present application has low oxygen content (oxygen ≤ 10PPm), low iron content (iron ≤ 0.03%), excellent corrosion resistance and good welding effect; and by adding rare earth element Y, it has excellent high-temperature corrosion resistance and is suitable for petrochemical industry, nuclear power industry, etc.

[0040] 2. The preparation process of the present application can control the iron content of the high-temperature alloy welding wire steel to below 0.03wt%, the oxygen content to below 0.001wt%, and the size of inclusions in the steel to below 15µm; by adopting the vacuum induction melting process designed by the present invention, the steel product not only has good tensile strength and excellent plasticity, but also has higher cleanliness and better corrosion resistance. At the same time, the probability of defects such as pores appearing in the weld during welding is lower, thereby improving the high-temperature corrosion resistance of the weld after welding.

[0041] 3. This application adopts a vacuum melting process, and the raw materials are added to the crucible of the vacuum induction melting furnace in an orderly manner according to the principle of feeding and distributing materials, and high-quality vacuum ingot materials are cast; the entire melting process is in a vacuum state or in an inert gas protection atmosphere, which effectively isolates the air and controls the gas content of the material at an extremely low level, thereby ensuring the purity of the molten steel and the performance of the steel;

[0042] 4. This application has precisely controlled the composition of the molten steel by strictly controlling the raw materials, taking furnace samples for component analysis and fine-tuning the composition of the molten steel many times, so that the vacuum ingot has an extremely low iron content; three-phase electromagnetic stirring is used many times during the vacuum smelting process to make the steel composition uniform, effectively avoiding the element segregation problem in the preparation process just now. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a vacuum melting process flow chart of an embodiment of the present application;

[0044] Figure 2 This is a metallographic photograph of the welding wire in the embodiment of the present application. DETAILED DESCRIPTION

[0045] To further help understand the technical solution of the present invention, the technical solution of the present invention is described in more detail below by providing several specific implementation examples. All of these described embodiments are only partial embodiments of the present invention, not all of them.

[0046] The following specific embodiments may be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments; and the reaction devices, monomer compounds, etc. involved in the following embodiments are all commercially available.

[0047] The following specific embodiments may be combined with each other, and the same or similar concepts or processes therein may not be described in detail in some embodiments.

[0048] The following examples are further explanations of the present invention, but the present invention is not limited thereto. Unless otherwise specified in the examples, the percentages are all by mass.

[0049] Example

[0050] This embodiment discloses a low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel, and its preparation process is as follows:

[0051] (1) Raw material control:

[0052] The following raw materials were selected for preparation: carbon particles (C 99.6%), polycrystalline silicon (S 99.9%), electrolytic nickel (Ni 99.97%), metallic chromium (JCr99A, Cr 99.5%), molybdenum bars (Mo-1, Mo 99.93%), niobium bars (Nb-1, Nb 99.92%), aluminum particles (Al99.7%), sponge titanium (MHTi-100, Ti 99.7%), NiMg alloy (Mg 18%), and metallic yttrium (3N-Y, Y 99.92%).

[0053] (2) Melting equipment selection: Use a 4.5t vacuum induction melting furnace; the vacuum induction melting furnace has a melting chamber leakage rate of 1.2Pa / min; the ultimate vacuum value of the melting chamber is 1.5Pa; the melting equipment has an inert gas argon atmosphere protection function and a three-phase electromagnetic stirring function.

[0054] (3) Principles of adding materials and fabrics

[0055] Place 20% of the formula weight of electrolytic nickel on the bottom of the crucible of the vacuum induction melting furnace, add polysilicon and 50% of the raw material weight of carbon particles, then add the remaining electrolytic nickel, metal chromium and molybdenum bars, and control the height of the furnace charge to the crucible slag line; keep the melting chamber in a vacuum state, add niobium bars and remaining carbon after the molten steel is melted, and carry out the first refining after all the materials are melted; add aluminum particles and sponge titanium after the first refining period; after the three refinings are completed, adjust the atmosphere in the melting chamber to an inert gas protective atmosphere before tapping, and add NiMg alloy and metal yttrium in an argon atmosphere.

[0056] (4) Vacuum melting

[0057] Melting process flow Figure 1 shown.

[0058] Place 20% of the formula weight of electrolytic nickel on the bottom of the crucible of the vacuum induction furnace, then add 50% of the formula weight of carbon particles and all polysilicon, then add the remaining electrolytic nickel, all the metal chromium, and all the molybdenum bars, and control the height of the furnace charge to the crucible slag line; if there is any remaining return material, it can be added to the crucible through a barrel under vacuum during the melting period;

[0059] The smelting chamber is evacuated, and when the vacuum reaches 10Pa, 100kW of power is supplied and maintained for 1.5 hours; the power is increased to 300kW and maintained for 1 hour; the power is increased to 600kW and the material is quenched; when the molten steel is completely melted, niobium bars and residual carbon are added, and high power is maintained until all the materials are completely melted; the temperature of the molten steel is adjusted to 1490℃, electromagnetic stirring is performed for 2 minutes, and the whole molten sample is taken for furnace analysis; the molten steel is kept warm and enters the first refining period, and the refining time is 30 minutes;

[0060] According to the analysis results of the full melt sample, the element internal control index, the actual weight of the molten steel and the theoretical furnace input amount, the weight of the titanium sponge and aluminum particles to be added is calculated; the power is turned off for 5 minutes, the titanium sponge and aluminum particles are added, and they are stirred for 2 minutes after melting; the sample in front of the furnace is taken for furnace analysis; the molten steel is kept warm and enters the second refining period, and the refining time is 40 minutes;

[0061] According to the analysis results of the pre-furnace sample, check whether the composition of the molten steel needs to be fine-tuned. If fine-tuning is required, calculate the weight of the material that needs to be fine-tuned based on the analysis results of the pre-furnace sample, the element internal control index, the actual molten steel weight and the theoretical furnace input amount, add it into the crucible and stir for 2 minutes; keep the molten steel warm and enter the third refining period, which lasts for 20 minutes;

[0062] The melting chamber was filled with argon to 28000Pa, NiMg alloy and metal yttrium were added, and stirred for 8 minutes; after the stirring was completed, the power was turned off, and the molten steel was allowed to stand for 10 minutes; the sample after the furnace was taken as the ingot composition sample;

[0063] Adjust the steel temperature to the steel-out temperature of 1510℃, maintain the power supply at 350kW, and carry out casting (mold specification Ø360*2800mm, excluding riser height). The casting speed is controlled at 350kg / min, and the power is turned off after casting. Extract the argon in the ingot mold chamber, and stop evacuating when the vacuum value reaches 100Pa. Maintain the pressure until the next day, then break and open the mold chamber, and finally demold it to obtain a vacuum ingot.

[0064] (5) Machining control

[0065] The pouring riser of the vacuum cast ingot is cut off to ensure that there is no secondary shrinkage cavity on the ingot body; the ingot is peeled on a lathe with a peeling thickness of 5~10mm to remove the slag inclusions and heavy skin on the surface of the ingot.

[0066] (6) Hot working process

[0067] The vacuum cast ingot after the riser is cut off and the skin is peeled is forged, rolled, and finally drawn into a finished wire with a specification of Ø1.2mm to obtain a low-iron, low-oxygen nickel-based high-temperature alloy welding wire steel.

[0068] (7) Analysis and testing

[0069] 7.1 The composition of the vacuum cast ingot in step (5) was analyzed. The results are shown in Table 1.

[0070] Table 1 Composition analysis of vacuum cast ingot (unit: wt%)

[0071]

[0072] 7.2 Analysis of inclusions in vacuum casting

[0073] Using Explorer 4 inclusion counting instrument, the vacuum casting sample obtained in step (5) was magnified 400 times for observation, and the observation area size was 43.68 mm 2 The inclusion observation results are shown in Table 2.

[0074] Table 2 Vacuum ingot inclusion analysis

[0075]

[0076] It can be seen from Table 2 that the vacuum ingot produced by the preparation process disclosed in the present invention has high purity, a small number of inclusions in the ingot, and a small size of the inclusions, less than 15 μm.

[0077] 7.3 Metallographic analysis of welding wire

[0078] According to GB / T6394 "Method for determination of average grain size of metals", the welding wire obtained in step (6) was sampled and tested. The average grain size was grade 10. The metallographic photograph is as follows: Figure 2 shown.

[0079] 7.4 Analysis of mechanical properties of welding wire

[0080] According to the method of GB / T230.1-2018 "Standard for Determination of Mechanical Properties of Metallic Materials", the welding wire prepared in step (6) was sampled and tested for tensile properties. The tensile test results are shown in Table 3 below.

[0081] Table 3 Wire tensile test results

[0082]

[0083] In summary, the vacuum melting process designed by the present invention can not only effectively isolate the air, strictly control the composition ratio, avoid element segregation in the steel preparation process, ensure the purity of the molten steel, and make the steel material have low oxygen content and low iron content, but also obtain steel wire with fine grains and small inclusion size, so that the steel has excellent corrosion resistance and welding effect, and has good tensile strength and excellent plasticity, which can meet various application requirements.

[0084] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A preparation process of a low-iron, low-oxygen nickel-based high-temperature alloy welding wire, characterized in that: The following components are included in mass percentage: C≤0.05%, Cr 20-23%, Mo 8.5-9.5%, Nb 3.2-4.0%, Y 0.08-0.4%, Ti≤0.3%, Si≤0.25%, Al≤0.3%, Mn≤0.1%, Fe≤0.03%, S≤0.004%, P≤0.003%, O≤0.001%, N≤0.003%, H≤0.0003%, the rest are Ni and unavoidable impurities; The inclusion size of the welding wire is less than 15µm and the average grain size is grade 10; The preparation process is: S1 Raw material control: Select carbon particles, polysilicon, electrolytic nickel, metal chromium, molybdenum bars, niobium bars, aluminum particles, sponge titanium, NiMg alloy, and metal yttrium as raw materials; S2 Vacuum Melting: Place 10-30% of the raw material weight of electrolytic nickel flat on the bottom of the crucible of the vacuum induction melting furnace, then add polysilicon and 45-60% of the raw material weight of carbon particles, then add the remaining electrolytic nickel, metal chromium, and molybdenum bars, and control the height of the furnace charge to the crucible slag line position; Keep the smelting chamber in a vacuum state, add niobium bars and residual carbon after the molten steel is completely melted, and perform the first refining after all the materials are completely melted; add aluminum particles and sponge titanium after the first refining period; perform the second and third refining, and after refining, adjust the atmosphere of the smelting chamber to an inert gas protective atmosphere before tapping, add NiMg alloy and metal yttrium, stir and then stand, tap the steel, and obtain a vacuum ingot; S3 removes the riser and peels the vacuum cast ingot, and then forges, rolls, and draws the ingot to obtain welding wire; The temperatures for the first refining, the second refining and the third refining are all 1490±20°C, and the durations are 30-40min, 40-50min and 20-30min respectively.

2. The preparation process of the low-iron, low-oxygen nickel-based high-temperature alloy welding wire according to claim 1, characterized in that: The vacuum melting step specifically comprises: After the vacuum degree of the vacuum induction melting furnace is controlled to reach the preset target, power is supplied at 100-200kW and maintained for 1-1.5h; then the power is increased to 300-400kW and maintained for 1-1.5h, and then the power is increased to 500-800kW to enter the material stage, and after the molten steel is melted, niobium bars and remaining carbon are added, and high power is continued to be maintained until all materials are melted, and the temperature of the molten steel is adjusted to 1490±20℃, electromagnetic stirring is performed for 2-5min, and the whole molten sample is taken for furnace analysis, the molten steel is kept warm, and the first refining stage is entered for refining; Cut off the power supply and set the film for 3-10 minutes, add titanium sponge and aluminum particles, stir for 2-5 minutes after melting, take the sample in front of the furnace for furnace analysis, keep the molten steel warm, and enter the second refining stage for refining; According to the analysis results of the furnace sample and the target molten steel composition, the molten steel is fine-tuned; the molten steel is kept warm and enters the third refining stage for refining; Adjust the atmosphere in the smelting chamber to an inert gas protective atmosphere, add NiMg alloy and metal yttrium and stir for 5-10 minutes; after stirring, turn off the power and let the molten steel stand for 5-10 minutes; take the sample after the furnace as the ingot composition sample; Adjust the steel temperature to the tapping temperature of 1510±10℃, maintain the power supply at 300-400kW, and start casting; Adjust the vacuum degree of the ingot mold chamber to meet the set target, and demould to obtain a vacuum ingot.

3. The preparation process of the low-iron, low-oxygen nickel-based high-temperature alloy welding wire according to claim 1, characterized in that: After the first refining period, the weight of titanium sponge and aluminum particles to be added is calculated based on the analysis results of the full melt sample, the internal control indicators of the elements, the actual weight of the molten steel and the theoretical furnace charge, and the titanium sponge and aluminum particles are added after the power is turned off and the film is formed.

4. The preparation process of the low-iron, low-oxygen nickel-based high-temperature alloy welding wire according to claim 1, characterized in that: After the second refining period, the weight of the material that needs to be fine-tuned is calculated based on the analysis results of the furnace sample, the internal control indicators of the elements, the actual weight of the molten steel and the theoretical furnace input amount, added to the crucible, stirred for 2-5 minutes, and then the third refining is carried out.

5. The preparation process of the low-iron, low-oxygen nickel-based high-temperature alloy welding wire according to claim 2, characterized in that: The casting speed is 350-450kg / min.

6. The preparation process of the low-iron, low-oxygen nickel-based high-temperature alloy welding wire according to claim 1, characterized in that: The equipment conditions of the vacuum induction melting furnace are: the leakage rate of the melting chamber is less than 1.3Pa / min, and the ultimate vacuum value of the melting chamber is lower than 2Pa. The equipment must have an inert gas argon atmosphere protection function and a three-phase electromagnetic stirring function.

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