Surfacing process method for 8630 low alloy steel and Inconel 625 nickel base alloy

Abstract

The invention discloses an 8630 low alloy steel and Inconel 625 nickel-based alloy surfacing process method. The 8630 low alloy steel and Inconel 625 nickel-based alloy surfacing process method comprises the following steps: a, producing and preparing the 8630 low alloy steel; 8630 low alloy steel is prepared through an electric furnace smelting technology, a ladle refining furnace refining technology, a vacuum refining technology and a continuous casting technology; b, selecting a reasonable welding material, namely an Inconel 625 nickel-based alloy; and c, a pulse hot wire TIG surfacing technology is adopted, 8630 low alloy steel is used as a surfacing matrix, and surfacing is conducted on the 8630 low alloy steel and the Inconel 625 nickel base alloy. The post-welding technical indexes of the novel welding material are as follows: the 8630 mechanical property is greater than or equal to API 6A 75K, the post-welding 625 surfacing layer mechanical property 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 post-welding 8630 hardness 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 hydrogen sulfide 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 8630 low alloy steel welding, and in particular to a surfacing welding process method for 8630 low alloy steel and Inconel625 nickel-based alloy. Background Art

[0002] The high-pressure wellhead assembly is a key component of the underwater wellhead system that supports the submarine casing string group. It needs to be welded by high-pressure wellheads, reducers, pipe connectors and other parts. Each part is usually made of American material standard AISI 8630 quenched and tempered steel. 8630 material forgings have high hardness, yield strength, tensile strength, good low-temperature impact toughness, elongation, and cross-sectional shrinkage. At the same time, it has good heat treatment performance and is widely used in the oil and gas drilling industry. For oil and gas equipment serving under harsh working conditions, there are higher requirements for material corrosion resistance. Inconel 625 nickel-based alloy is the first choice of mainstream oil and gas equipment manufacturers at home and abroad. It is particularly suitable for use in acidic conditions and has excellent resistance to high hydrogen sulfide and seawater corrosion. The cladding parts used in oil and gas products have high requirements on the surface and internal quality of the cladding layer. The quality of the weld layer must be guaranteed while taking into account efficiency. 8630 low-alloy steel has poor weldability. Developing and optimizing cladding technology is an effective way to improve welding quality. Summary of the invention

[0003] The problem to be solved by the present invention is to provide a surfacing process method of 8630 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: 8630 low alloy steel and Inconel 625 nickel-based alloy surfacing process, the steps of which are: a. The production and preparation process of 8630 low alloy steel: mainly includes electric furnace smelting technology (EF), ladle refining furnace refining technology (LF), vacuum refining technology (VD), and continuous casting technology (CC). The specific method is:

[0005] Electric furnace smelting technology (EF): a series of process flows including furnace filling, charging, melting, oxidation and reduction are used to produce the material to be processed1.

[0006] 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.

[0007] Vacuum refining technology (VD): For the material 2 to be processed, in order to further degas, deoxidize, desulfurize and stir, reduce the hydrogen and nitrogen content in the steel, and make the composition and temperature uniform so as to produce the material 3 to be processed.

[0008] Continuous casting technology (CC): For the material to be processed 3, the molten steel is converted into a steel billet to obtain the final required 8630 low alloy steel material.

[0009] Appropriate forging technology and heat treatment technology are used to ensure the mechanical properties of its base material 8630.

[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 an austenitic structure, excellent corrosion resistance and oxidation resistance, and is widely used in acid-resistant and high-temperature oxidation environments.

[0011] c. 8630 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 to heat the welding wire through an additional hot wire power supply to improve welding efficiency.

[0012] As a preferred solution, the specific chemical composition requirements of the obtained 8630 low alloy steel material are as follows: C: 0.25%-0.33%; Si: 0.15%-0.35%; Mn: 0.70-1.10%; P: ≤0.025%; S: ≤0.025%; Cr: 0.85-1.00%; Ni: 0.35%-0.45%; Ni: 0.75%-0.90; Cu: ≤0.25; V: ≤0.06%; Ti: ≤0.06%; Al: ≤0.035%;

[0013] As a preferred solution, the forging ratio 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, 8630 material is low alloy steel with more alloy elements and high hardenability. It is necessary to design appropriate forging process technology and heat treatment process technology according to different mechanical performance requirements to ensure its 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: mechanical properties of 8630 after welding ≥ API 6A 75; mechanical properties of 625 surfacing layer after welding ≥ API 6A 75K; impact toughness (-60℃) AKV≥27 / 20J; hardness of 8630 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. DETAILED DESCRIPTION

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

[0019] A surfacing process for 8630 low alloy steel and Inconel 625 nickel-based alloy, comprising the following steps:

[0020] a. Production and preparation process of 8630 low alloy steel: mainly includes electric furnace smelting technology (EF), ladle refining furnace refining technology (LF), vacuum refining technology (VD), and continuous casting technology (CC). The specific methods are:

[0021] Electric furnace smelting technology (EF): a series of process flows including furnace filling, charging, melting, oxidation and reduction are used to produce the material to be processed1.

[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 refining technology (VD): For the material 2 to be processed, in order to further degas, deoxidize, desulfurize and stir, reduce the hydrogen and nitrogen content in the steel, and make the composition and temperature uniform so as to produce the material 3 to be processed.

[0024] Continuous casting technology (CC): For the material to be processed 3, the molten steel is converted into a steel billet to obtain the final required 8630 low alloy steel material.

[0025] The specific chemical composition requirements of the obtained 8630 low alloy steel material are as follows: C: 0.25%-0.33%; Si: 0.15%-0.35%; Mn: 0.70-1.10%; P: ≤0.025%;

[0026] S: ≤0.025%; Cr: 0.85-1.00%; Ni: 0.35%-0.45%; Ni: 0.75%-0.90; Cu: ≤ 0.25; V: ≤ 0.06%; Ti: ≤ 0.06%; Al: ≤ 0.035%;

[0027] 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 an austenitic structure, excellent corrosion resistance and oxidation resistance, and is widely used in acid-resistant and high-temperature oxidation environments. Due to poor thermal conductivity, welding heat is not easy to diffuse, and overheating and coarseness are prone to occur. Some S and P impurities will segregate in the weld. In addition, the material has poor fluidity and wettability, making it difficult to weld through.

[0028] c. Pulse hot wire TIG surfacing. 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. The pulse hot wire TIG surfacing developed by Fronius of Austria is adopted. The parameters of pulse hot wire TIG welding are stable, 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 penetration testing.

[0029] The technical indicators of the products produced by this method are as follows:

[0030] Index items Index value 8630 low alloy steel after welding ≥API 6A 75K Mechanical properties of 625 cladding layer after welding ≥API 6A 75K Impact toughness (-60℃) AKV ≥27 / 20J 8630 hardness after welding 207~237HBW Fusion line + 3mm Fe% ≤5％ Macro No defects

[0031] 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 8630 low alloy steel and Inconel 625 nickel-based alloy, comprising the following steps: a. Production and preparation process of 8630 low alloy steel: mainly includes electric furnace smelting technology (EF), ladle refining furnace refining technology (LF), vacuum refining technology (VD), and continuous casting technology (CC). The specific methods are: Electric furnace smelting technology (EF): a series of process flows including furnace filling, charging, melting, oxidation and reduction are used to produce the material to be processed1. 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 refining technology (VD): For the material 2 to be processed, in order to further degas, deoxidize, desulfurize and stir, reduce the hydrogen and nitrogen content in the steel, and make the composition and temperature uniform so as to produce the material 3 to be processed. Continuous casting technology (CC): For the material to be processed 3, the molten steel is converted into a steel billet to obtain the final required 8630 low alloy steel material. b. The welding material is Inconel 625 nickel-based alloy. c. 8630 low alloy steel cladding Inconel 625 nickel-based alloy cladding process technology includes: Forging technology, heat treatment technology and welding technology. Pulse hot wire TIG surfacing is used to heat the welding wire through an additional hot wire power supply to improve welding efficiency.

2. The production process of 8630 low alloy steel according to claim 1, characterized in that In step a, the specific chemical composition requirements of the obtained 8630 low alloy steel material are as follows: C: 0.25%-0.33%; Si: 0.15%-0.35%; Mn: 0.70-1.10%; P: ≤0.025%; S: ≤0.025%; Cr: 0.85-1.00%; Ni: 0.35%-0.45%; Ni: 0.75%-0.90; Cu: ≤0.25; V: ≤0.06%; Ti: ≤0.06%; Al: ≤0.035%.

3. The 8630 low alloy steel and Inconel 625 nickel-based alloy surfacing process according to claim 1 is characterized in that In step c, the forging ratio of 8630 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 8630 low alloy steel and Inconel 625 nickel-based alloy surfacing process according to claim 1, characterized in that In step c, the 8630 material is a low alloy steel with more alloy elements and high hardenability, and it is necessary to adopt appropriate forging process technology and heat treatment process technology to ensure the performance of its base material.

5. The 8630 low alloy steel and Inconel 625 nickel-based alloy surfacing process 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.