F22 low alloy steel and Inconel 625 nickel base alloy surfacing welding process method

Abstract

The invention discloses an F22 low-alloy steel and Inconel 625 nickel-based alloy surfacing process method. The F22 low-alloy steel and Inconel 625 nickel-based alloy surfacing process method comprises the following steps: a, producing and preparing F22 low-alloy steel; the F22 low-alloy steel is prepared through an electric arc furnace smelting technology, a ladle refining furnace refining technology, a molten steel vacuum degassing refining technology and a continuous casting technology; b, selecting a reasonable welding material, namely an Inconel 625 nickel-based alloy; and c, the pulse hot wire surfacing technology is adopted, and surfacing is conducted on the F22 low alloy steel serving as a surfacing matrix and the Inconel 625 nickel base alloy. The technical indexes of the novel welding material after welding are as follows: the mechanical property of F22 is greater than or equal to API 6A 75K, the mechanical property of a 625 surfacing layer after welding is greater than or equal to API 6A 75K, the impact toughness (-60 DEG C) AKV is greater than or equal to 27 / 20J, the hardness of F22 after welding is 207-237 HBW, the fusion line + 3 mm Fe% is less than or equal to 5%, and no macroscopic defect exists. And various requirements of materials of oil and gas drilling and production equipment on use in seawater high-pressure and sulfide-containing oil and gas environments and the like are met.

Description

Technical Field

[0001] The invention relates to the technical field of F22 low alloy steel welding, and in particular to a surfacing welding process method of F22 low alloy steel and Inconel625 nickel-based alloy. Background Art

[0002] At present, the traditional underwater Christmas tree products in the world are basically produced by underwater equipment suppliers such as AkerSolutions, FMC, Cameron, and GE. The Christmas trees in domestic oil and gas fields are also mainly from these three suppliers. Underwater Christmas trees are basically imported, which seriously affects the safety of oil and gas use in my country. F22 steel is a low-carbon, low-alloy Cr-Mo steel in the US ASTM standard. It is the preferred steel type to replace 4130 steel to produce deep-sea Christmas tree valve bodies. It has a low carbon content and high Cr and Mo content. It is easy to undergo peritectic reaction during continuous casting and form defects inside. Inconel 625 nickel-based alloy has good corrosion resistance. Overlaying Inconel 625 nickel-based alloy on the equipment body is currently recognized by the world's land or deep-sea oil production equipment manufacturers as the most economical and mature method. With the help of a certain heat source, the corrosion-resistant alloy material is clad on the F22 surface to improve the acid resistance and high pressure resistance of F22, which is of great significance to the localization of underwater Christmas trees. Summary of the invention

[0003] The problem to be solved by the present invention is to provide a surfacing process method of F22 low alloy steel and Inconel 625 nickel-based alloy for deep-sea oil production equipment which is corrosion-resistant, pressure-resistant and impact-resistant and has high surfacing quality and high efficiency.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a surfacing process method of F22 low alloy steel and Inconel625 nickel-based alloy, the steps of which are:

[0005] a. Production and preparation process of F22 low alloy steel: mainly includes electric arc furnace smelting technology (EAF), ladle refining furnace refining technology (LF), molten steel vacuum degassing refining technology (RH), and continuous casting process technology (CCM). The specific methods are:

[0006] Electric Arc Furnace (EAF) smelting technology: produces the material to be processed through a series of process steps including furnace filling, charging, melting, oxidation and reduction1.

[0007] Ladle refining furnace refining technology (LF): Deoxidation and desulfurization catalytic materials are added to the material to be processed 1, and heating is performed to produce a chemical reaction to achieve desulfurization and deoxidation to produce the material to be processed 2.

[0008] Vacuum degassing and refining technology of molten steel (RH): For the material to be processed 2, a density difference is generated in the vacuum tank, so that the molten steel circulates up and down in the ladle and the vacuum tank, and the gas originally dissolved in the molten steel is discharged as much as possible to prevent secondary oxidation, thereby producing the material to be processed 3.

[0009] Continuous Casting Process (CCM): For the material to be processed 3, it is poured into the tundish, and then the molten steel is distributed to each crystallizer through the nozzle. The casting in the crystallizer is pulled out, cooled, electromagnetically stirred, and cut into slabs of a certain length, so as to finally obtain the required low alloy steel F22 material.

[0010] b. Welding material Inconel 625 nickel-based alloy is a solid solution strengthened nickel-based deformable high-temperature alloy with molybdenum and niobium as the main strengthening elements. It has excellent corrosion resistance and oxidation resistance, good tensile and fatigue properties from low temperature to 980℃, and is resistant to stress corrosion in salt spray atmosphere.

[0011] c. The surfacing technology of F22 low alloy steel and Inconel 625 nickel-based alloy includes forging technology, heat treatment technology and welding technology. Pulse hot wire TIG surfacing is adopted. The welding wire is heated by an additional hot wire power supply, which improves the welding efficiency.

[0012] As a preferred solution, the specific chemical composition requirements of the obtained low alloy steel F22 material are as follows: C: ≤0.10-0.15%; Si: ≤0.15-0.50%; Mn: ≤0.30-0.60%; P: ≤0.015%; S: ≤0.010%; Cr: 2.00-2.50%; Mo ≤0.87-1.13%; Ni: ≤0.50%; Nb: ≤0.01%; V: ≤0.03%; Ti: ≤0.03%; Al: ≤0.05%;

[0013] As a preferred solution, the forging ratio of F22 low alloy steel must be guaranteed to be ≥4:1. This ensures a compact structure after forging, breaks up coarse austenite grains, disperses inclusions, eliminates banded structures, and reduces anisotropy.

[0014] As a preferred solution, when approaching the final forging temperature, a light-beating and fast-forging process is used to make the grains finer, laying the foundation for improving the mechanical properties.

[0015] As a preferred solution, F22 material is low alloy steel with more alloy elements and high hardenability. The heat treatment process is: when F22 is lower than 350°C, the temperature is raised to 913-970°C at a heating rate lower than 200°C / hour, kept warm for more than 4.5 hours, and quenched below 204°C. After the workpiece is cooled to below 350°C, high temperature tempering is performed and kept warm for more than 9 hours to obtain a fine and uniform structure and better comprehensive performance.

[0016] As a preferred solution, pulse hot wire TIG cladding is performed by a pulse hot wire TIG welder produced by Fronius, Austria. The welding speed, wire feeding speed, pulse parameters, arc length, hot wire current and other parameters are adjusted to determine the welding process, and the preheating, interlayer temperature and welding line energy are strictly controlled.

[0017] The beneficial effects of the present invention are: pulse hot wire TIG surfacing is adopted, the surface of the surfacing layer is flat and continuous, and no visible defects are found after penetration testing. The indicators of the material obtained by the surfacing process are: F22 mechanical properties after welding ≥ API 6A 75K; mechanical properties of 625 surfacing layer after welding ≥ API 6A75K; impact toughness (-60℃) AKV≥27 / 20J; F22 hardness after welding: 207~237HBW; fusion line +3mm Fe%≤5%; no macroscopic defects. It meets the requirements that the materials of oil and gas drilling and production equipment such as land wellheads and Christmas trees, underwater wellheads and Christmas trees, and blowout preventers need to adapt to various harsh working environments such as high temperature, high pressure, and high hydrogen sulfide content. Specific implementation plan

[0018] Specific embodiments of the present invention are described in detail below.

[0019] A method for surfacing welding of F22 low alloy steel and Inconel 625 nickel-based alloy, comprising the following steps:

[0020] a. Production and preparation process of F22 low alloy steel: mainly including electric arc furnace smelting technology (EAF), ladle refining furnace refining technology (LF), molten steel vacuum degassing refining technology (RH), continuous casting process technology (CCM). The specific methods are as follows:

[0021] Electric Arc Furnace (EAF) smelting technology: produces the material to be processed through a series of process steps including furnace filling, charging, melting, oxidation and reduction1.

[0022] Ladle refining furnace refining technology (LF): Deoxidation and desulfurization catalytic materials are added to the material to be processed 1, and heating is performed to produce a chemical reaction to achieve desulfurization and deoxidation to produce the material to be processed 2.

[0023] Vacuum degassing and refining technology of molten steel (RH): For the material to be processed 2, a density difference is generated in the vacuum tank, so that the molten steel circulates up and down in the ladle and the vacuum tank, and the gas originally dissolved in the molten steel is discharged as much as possible to prevent secondary oxidation, thereby producing the material to be processed 3.

[0024] Continuous Casting Process (CCM): For the material to be processed 3, it is poured into the tundish, and then the molten steel is distributed to each crystallizer through the nozzle. The casting in the crystallizer is pulled out, cooled, electromagnetically stirred, and cut into slabs of a certain length, so as to finally obtain the required low alloy steel F22 material.

[0025] The specific chemical composition requirements of the obtained low alloy steel F22 material are as follows:

[0026] C: ≤0.10-0.15%; Si: ≤0.15-0.50%%; Mn: ≤0.30-0.60%; P: ≤0.015%;

[0027] S: ≤ 0.010%; Cr: 2.00-2.50%; Mo ≤ 0.87-1.13%; Ni: ≤ 0.50%; Nb: ≤ 0.01%; V: ≤ 0.03%; Ti: ≤ 0.03%; Al: ≤ 0.05%;

[0028] The heat treatment process is: when F22 is lower than 350℃, use a heating rate lower than 200℃ / hour to increase to 913~970℃, keep warm for more than 4.5 hours, and quench below 204℃. After cooling to below 350℃, high temperature tempering is performed and kept warm for more than 9 hours to obtain a fine and uniform structure and better comprehensive performance.

[0029] b. Welding material Inconel 625 nickel-based alloy is a solid solution strengthened nickel-based deformable high-temperature alloy with molybdenum and niobium as the main strengthening elements. It has excellent corrosion resistance and oxidation resistance, good tensile and fatigue properties from low temperature to 980℃, and is resistant to stress corrosion in salt spray atmosphere.

[0030] c. Pulse hot wire TIG surfacing. The substrate used is F22 low alloy steel. Pulse hot wire TIG surfacing has the advantages of low base material dilution rate, small heat affected zone, dense weld structure, small residual stress and deformation, stable arc, and few welding defects. In particular, the welding gun has a simple structure and good accessibility, which is suitable for surfacing of slender hole surfaces and complex curved surfaces. Pulse hot wire TIG welding has stable parameters, and the welding wire is heated by an additional hot wire power supply, which improves welding efficiency. The surface of the surfacing layer is flat and continuous, and no visible defects are found after penetration testing.

[0031] The technical indicators of the products produced by this method are as follows:

[0032]

[0033]

[0034] The above-mentioned embodiments are only illustrative of the principles and effects of the invention, as well as some embodiments of its application, and are not intended to limit the invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the invention, and all of these belong to the protection scope of the invention.

Claims

1. A surfacing process for F22 low alloy steel and Inconel 625 nickel-based alloy, comprising the following steps: a. Production and preparation process of F22 low alloy steel: Electric arc furnace smelting technology (EAF), ladle refining furnace refining technology (LF), molten steel vacuum degassing refining technology (RH), continuous casting process technology (CCM). The specific methods are: Electric Arc Furnace (EAF) smelting technology: produces the material to be processed through a series of process steps including furnace filling, charging, melting, oxidation and reduction1. Ladle refining furnace refining technology (LF): Deoxidation and desulfurization catalytic materials are added to the material to be processed 1, and heating is performed to produce a chemical reaction to achieve desulfurization and deoxidation to produce the material to be processed 2. Vacuum degassing and refining technology of molten steel (RH): For the material to be processed 2, a density difference is generated in the vacuum tank, so that the molten steel circulates up and down in the ladle and the vacuum tank, and the gas originally dissolved in the molten steel is discharged as much as possible to prevent secondary oxidation, thereby producing the material to be processed 3. Continuous Casting Process (CCM): The material 3 to be processed is poured into the tundish, and the molten steel is distributed to each crystallizer through the nozzle. The casting in the crystallizer is pulled out, cooled, and electromagnetically stirred, and then cut into billets of a certain length, thereby finally obtaining the required low alloy steel F22 material. b. The welding material is Inconel 625 nickel-based alloy. c. F22 low alloy steel surfacing Inconel 625 nickel-based alloy surfacing technology includes: Forging technology, heat treatment technology and welding technology. Pulse hot wire TIG surfacing is used. The welding wire is heated by an additional hot wire power supply to improve welding efficiency.

2. The production process of F22 low alloy steel according to claim 1, characterized in that In step a, the specific chemical composition of the obtained F22 low alloy steel material is required as a finished product: C: ≤0.10-0.15%; Si: ≤0.15-0.50%; Mn: ≤0.30-0.60%; P: ≤0.015%; S: ≤0.010%; Cr: 2.00-2.50%; Mo ≤0.87-1.13%; Ni: ≤0.50%; Nb: ≤0.01%; V: ≤0.03%; Ti: ≤0.03%; Al: ≤0.05%.

3. The surfacing process of F22 low alloy steel and Inconel 625 nickel-based alloy according to claim 1, characterized in that In step c, the forging ratio of F22 low alloy steel must be guaranteed to be ≥4:

1. When approaching the final forging temperature, the forging process of light beating and fast forging can make the grains finer, laying the foundation for improving the mechanical properties.

4. The surfacing process of F22 low alloy steel and Inconel 625 nickel-based alloy according to claim 1, characterized in that In step c, the heat treatment process is: when F22 is lower than 350°C, the temperature is raised to 913-970°C at a heating rate lower than 200°C / hour, kept at this temperature for more than 4.5 hours, and quenched at a temperature lower than 204°C. The workpiece cooled to below 350°C is subjected to high temperature tempering and kept at this temperature for more than 9 hours to obtain a fine and uniform structure and better comprehensive properties.

5. The surfacing process of F22 low alloy steel and Inconel 625 nickel-based alloy according to claim 1, characterized in that In step c, adjust the welding speed, wire feeding speed, pulse parameters, arc length, hot wire current and other parameters, determine the welding process, and strictly control the preheating, interlayer temperature and welding line energy.

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