F65 low alloy steel and Inconel 625 nickel base alloy surfacing welding process method

Abstract

The invention discloses an F65 low-alloy steel and Inconel 625 nickel-based alloy surfacing process method. The F65 low-alloy steel and Inconel 625 nickel-based alloy surfacing process method comprises the following steps: a, producing and preparing the F65 low-alloy steel; the F65 low-alloy steel is produced 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 TIG surfacing technology is adopted, and surfacing is conducted on the F65 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 F65 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 (-46 DEG C) AKV is greater than or equal to 27 / 20J, the hardness of F65 after welding is 207-237 HBW, the fusion line + 3 mm Fe% is less than or equal to 5%, no macroscopic defect exists, and various requirements of high pressure resistance, high corrosion and the like required by the material of oil and gas drilling and production equipment are met.

Description

Technical Field

[0001] The invention relates to the technical field of F65 low alloy steel welding, and in particular to a surfacing welding process method of F65 low alloy steel and Inconel625 nickel-based alloy. Background Art

[0002] As the exploitation of terrestrial oil and gas resources decreases, the exploration and development of marine oil and gas resources continues to increase, and with the development of technology, oil and gas resources are gradually extending to the deep sea. The number of submarine pipeline applications is huge, and the greater the operating depth, the material is high-standard carbon steel forging ASTM F65. In the submarine pipeline system, F65 serves under harsh working conditions and has higher requirements for material corrosion resistance. Using Inconel 625 nickel-based alloy surfacing to improve its low-temperature toughness, corrosion resistance, acid resistance, high temperature and high pressure resistance is one of the most economical ways, but its heat treatment and surfacing process development are rarely reported. Summary of the invention

[0003] The problem to be solved by the present invention is to provide a surfacing process method of F65 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 F65 low alloy steel and Inconel625 nickel-based alloy, the steps of which are:

[0005] a. Production and preparation process of F65 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 technology (CCM).

[0006] The specific method is:

[0007] 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.

[0008] 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.

[0009] Molten steel vacuum treatment technology (RH): For the material 2 to be processed, in order to further desulfurize and deoxidize, driving gas argon is blown into the molten steel under vacuum conditions to form a density difference, and degassing is carried out by circulating the molten steel up and down, thereby producing the material 3 to be processed.

[0010] Continuous casting technology (CCM): For the material to be processed 3, it is transferred from the smelting furnace to the continuous casting machine, and is gradually cooled and processed into F65 low alloy steel through continuous casting operations.

[0011] 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.

[0012] c. F65 low alloy steel cladding Inconel 625 nickel-based alloy cladding process technology includes: forging process technology, heat treatment process technology and welding process technology. Pulse hot wire TIG cladding is used for welding. The welding wire is heated by an additional hot wire power supply to improve welding efficiency.

[0013] As a preferred solution, the specific chemical composition requirements of the obtained low alloy steel F65 material are as follows: C: 0.08-0.12%; Si: 0.15-0.35%; Mn: 1.00-1.40%; P: ≤ 0.010%; S: ≤ 0.005%; Cr: 0.10-0.25%; Mo: 0.20-0.40%; Ni: 0.70-1.0 %; Ti: ≤ 0.015%; Cu: ≤ 0.30%; V: ≤ 0.03%; Nb: ≤ 0.02%; Pb: ≤ 0.010%; Sn: ≤ 0.010; As: ≤ 0. 010%; N: ≤ 0.012%; Bi: ≤ 0.010%; Sb: ≤ 0.03%; Ca: ≤ 0.005%; B: ≤ 0.0005%; Al: ≤ 0.020%;

[0014] As a preferred solution, the forging ratio of F65 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.

[0015] 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.

[0016] As a preferred solution, F65 material is low alloy steel with more alloy elements and high hardenability. After hot forging, F65 low alloy steel is subjected to reasonable post-forging heat treatment process and performance heat treatment process to obtain fine and uniform structure and good comprehensive performance.

[0017] As a preferred solution, the surface to be welded is finely milled. F65 has poor weldability and needs to maintain a high preheating and interlayer temperature, strictly control the heat input, and obtain a better weld layer. Pulse hot wire TIG welding 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 welding of slender hole surfaces and complex curved surfaces.

[0018] 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: F65 mechanical properties after welding ≥ API 6A 75K, mechanical properties of 625 surfacing layer after welding ≥ API 6A75K, impact toughness (-46℃) AKV≥27 / 20J, F65 hardness after welding 207~237HBW, fusion line +3mm Fe%≤5% macroscopically without any defects. It meets the requirements that the materials of oil and gas drilling equipment need to adapt to various harsh working environments such as high temperature, high pressure, and high hydrogen sulfide content. Specific implementation plan

[0019] Specific embodiments of the present invention are described in detail below.

[0020] A method for surfacing welding of F65 low alloy steel and Inconel 625 nickel-based alloy, comprising the following steps:

[0021] a. Production and preparation process of F65 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 technology (CCM).

[0022] The specific method is:

[0023] 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.

[0024] 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.

[0025] Molten steel vacuum treatment technology (RH): For the material 2 to be processed, in order to further desulfurize and deoxidize, driving gas argon is blown into the molten steel under vacuum conditions to form a density difference, and degassing is carried out by circulating the molten steel up and down, thereby producing the material 3 to be processed.

[0026] Continuous casting technology (CCM): For the material to be processed 3, it is transferred from the smelting furnace to the continuous casting machine, and is gradually cooled and processed into F65 low alloy steel through continuous casting operations.

[0027] The specific chemical composition of the obtained low alloy steel F65 material is as follows: C: 0.08-0.12%; Si: 0.15-0.35%; Mn: 1.00-1.40%; P: ≤0.010%; S: ≤0.005%; Cr: 0.10-0.25%; Mo: 0.20-0.40%; Ni: 0.70-1.0%; Ti: ≤0.015%; Cu: ≤0.30%; V: ≤0.03%; Nb: ≤0.02%; Pb: ≤0.010%; Sn: ≤0.010; As: ≤0.010%;

[0028] N: ≤ 0.012%; Bi: ≤ 0.010%; Sb: ≤ 0.03%; Ca: ≤ 0.005%; B: ≤ 0.0005%;

[0029] Al: ≤0.020%;

[0030] 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.

[0031] c. Pulse hot wire TIG surfacing. The substrate used is F65 low alloy steel, and the surface to be surfacing is finely milled. F65 has poor weldability, so it is necessary to maintain a high preheating and interlayer temperature, strictly control the heat input, and obtain a good surfacing layer. Pulse hot wire TIG welding has stable parameters, and the welding wire is heated by an additional hot wire power supply, which improves the welding efficiency. The surface of the surfacing layer is flat and continuous, and no visible defects are found after penetrant testing.

[0032] The technical indicators of the products produced by this method are as follows:

[0033] Index items Index value Mechanical properties of F65 after welding ≥API 6A 75K Mechanical properties of 625 cladding layer after welding ≥API 6A 75K Impact toughness (-46℃) AKV ≥27 / 20J F65 hardness after welding 207~237HBW Fusion line + 3mm Fe% ≤5％ Macro No defects

[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 F65 low alloy steel and Inconel 625 nickel-based alloy, comprising the following steps: a. Production and preparation process of F65 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 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. Molten steel vacuum treatment technology (RH): For the material 2 to be processed, in order to further desulfurize and deoxidize, driving gas argon is blown into the molten steel under vacuum conditions to form a density difference, and degassing is carried out by circulating the molten steel up and down, thereby producing the material 3 to be processed. Continuous casting technology (CCM): For the material to be processed 3, it is transferred from the smelting furnace to the continuous casting machine, and is gradually cooled and processed into F65 low alloy steel through continuous casting operations. b. The welding material is Inconel 625 nickel-based alloy. c. F65 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 F65 low alloy steel according to claim 1, characterized in that In step a: the specific chemical composition of the obtained low alloy steel F65 material is required to be C: 0.08-0.12%; Si: 0.15-0.35%; Mn: 1.00-1.40%; P: ≤0.010%; S: ≤0.005%; Cr: 0.10-0.25%; Mo: 0.20-0.40%; Ni: 0.70-1.0%; Ti: ≤0.015%; Cu: ≤0.30%; V: ≤0.03%; Nb: ≤0.02%; Pb: ≤0.010%; Sn: ≤0.010; As: ≤0.010%; N: ≤ 0.012%; Bi: ≤ 0.010%; Sb: ≤ 0.03%; Ca: ≤ 0.005%; B: ≤ 0.0005%; Al: ≤ 0.020%; 3. The surfacing process of F65 low alloy steel and Inconel 625 nickel-based alloy according to claim 1 is characterized in that In step c, the forging ratio of low alloy steel F65 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 F65 low alloy steel and Inconel 625 nickel-based alloy according to claim 1, characterized in that In step c, F65 material is low alloy steel with more alloy elements and high hardenability. After hot forging, F65 low alloy steel is subjected to reasonable post-forging heat treatment process and performance heat treatment process to obtain fine and uniform structure and good comprehensive performance.

5. The surfacing process of F65 low alloy steel and Inconel 625 nickel-based alloy according to claim 1, characterized in that In step c, the weldability of F65 is poor, and it is necessary to maintain a high preheating and interpass temperature and strictly control the heat input to obtain a better surfacing layer.