Flux-cored wire for hydrogen-resistant coating of pipeline steel and preparation method of flux-cored wire

Abstract

The invention discloses a flux-cored wire for a hydrogen-resistant coating of pipeline steel, which comprises an outer skin, the outer skin is filled with a flux core, and the flux core comprises the following raw material components in percentage by mass: 3%-5% of chromium, 1%-2% of molybdenum, 2%-3% of vanadium, 2%-4% of titanium, 0.5%-1% of aluminum, 0.4%-0.6% of silicon, 1.5%-3% of manganese and 81.4%-89.6% of iron. The preparation method of the flux-cored wire for the hydrogen-resistant coating of the pipeline steel comprises the following steps that the outer skin is obtained, and raw material powder is weighed according to the mass percent; the raw material powder is heated in an inert gas atmosphere and then subjected to heat preservation; the raw material powder is cooled to the room temperature, the outer skin is rolled into a U-shaped groove shape through a welding wire forming machine, the U-shaped groove is filled with the cooled raw material powder, and an original welding wire is manufactured after closed forming and roller treatment; and reducing the diameter step by step to prepare the flux-cored wire with a set diameter. The flux-cored wire for the hydrogen-resistant coating of the pipeline steel is short in preparation period and high in production efficiency, the performance can be improved by adjusting the components and proportion of the flux core, meanwhile, production of the flux-cored wire is free of pollution, and the cladding efficiency in the welding process is high.

Description

Technical Field

[0001] The invention belongs to the technical field of welding materials, relates to a flux-cored welding wire for a pipeline steel hydrogen-resistant coating, and also relates to a preparation method of the flux-cored welding wire for the pipeline steel hydrogen-resistant coating. Background Art

[0002] In modern industry, pipeline steel is widely used in the fields of petroleum, natural gas, and chemical industry for transporting high-pressure fluids. However, hydrogen often exists in these environments. Especially under high temperature and high pressure conditions, hydrogen has a significant impact on the performance of materials. The mechanical properties of iron-based alloys often decrease significantly due to the influence of hydrogen embrittlement. Hydrogen-induced cracking is the main cause of catastrophic brittle fracture of high-strength structural materials under low stress conditions. Hydrogen embrittlement seriously threatens the safety and reliability of pipeline steel. Hydrogen embrittlement can cause the plasticity of the material to decrease significantly, cracks to expand rapidly, and even cause catastrophic fracture. Therefore, improving the hydrogen resistance of pipeline steel has become an important research topic in industry and academia.

[0003] Traditional anti-hydrogen measures include material selection, alloying, heat treatment and other methods, but these methods often fail to take into account both high strength and high hydrogen resistance. In recent years, surface coating technology has gradually become an important means to improve the hydrogen resistance of materials due to its simplicity, high efficiency and low cost. In particular, martensitic stainless steel is widely used in anti-hydrogen coatings for pipeline steels due to its high strength and good corrosion resistance. The martensitic structure in martensitic stainless steel has high strength and good corrosion resistance. However, conventional coating methods have limitations in adhesion, hydrogen permeability resistance and production efficiency. Therefore, the development of a martensitic stainless steel flux-cored welding wire with excellent hydrogen resistance and easy preparation is of great significance to improving the hydrogen resistance of pipeline steel.

[0004] In summary, the existing technology has the problems of poor hydrogen-resistant coating performance and complicated process. Summary of the invention

[0005] The purpose of the present invention is to provide a flux-cored welding wire for hydrogen-resistant coating of pipeline steel, which solves the problems of poor performance and complicated process of hydrogen-resistant coating in the prior art.

[0006] Another object of the present invention is to provide a method for preparing a flux-cored welding wire for hydrogen-resistant coating of pipeline steel.

[0007] The technical solution adopted by the present invention is a flux-cored welding wire for hydrogen-resistant coating of pipeline steel, comprising an outer skin, the outer skin being filled with a flux core, the flux core being composed of the following raw material components by mass percentage: 3%-5% chromium, 1%-2% molybdenum, 2%-3% vanadium, 2%-4% titanium, 0.5%-1% aluminum, 0.4%-0.6% silicon, 1.5%-3% manganese, and 81.4%-89.6% iron, and the sum of the mass percentages of the above components is 100%.

[0008] The present invention is also characterized in that: The outer shell is made of austenitic stainless steel.

[0009] The filling rate of the drug core in the outer skin is 20%-25%.

[0010] Another technical solution adopted by the present invention is a method for preparing a flux-cored welding wire for a hydrogen-resistant coating of pipeline steel, comprising the following steps: Step 1, obtain the outer skin, and weigh the following raw material powders by mass percentage: chromium 3%-5%, molybdenum 1%-2%, vanadium 2%-3%, titanium 2%-4%, aluminum 0.5%-1%, silicon 0.4%-0.6%, manganese 1.5%-3%, iron 81.4%-89.6%, and the total mass percentage of the above raw material powders is 100%; Step 2: heating the raw material powder in an inert gas atmosphere and then keeping it warm; Step 3: Cool the raw material powder to room temperature, roll the outer skin into a U-shaped groove through a welding wire forming machine, fill the cooled raw material powder into the U-shaped groove, close the shape and make the original welding wire after roller processing; Step 4: The original welding wire is gradually reduced in diameter to produce a flux-cored welding wire of a set diameter for hydrogen-resistant coating of pipeline steel.

[0011] Another technical solution of the present invention is also characterized in that: The raw material powder can pass through an 80-mesh sieve.

[0012] The outer skin is made of 0Cr18Ni9 austenitic stainless steel.

[0013] The heating temperature in step 2 is 150°C-200°C.

[0014] The insulation time in step 2 is 2h-2.5h.

[0015] The inert gas is argon with a purity of not less than 99.999%.

[0016] The beneficial effects of the present invention are as follows: the material of the flux-cored welding wire of the present invention is martensitic stainless steel, which significantly improves the hydrogen resistance of pipeline steel; chromium and molybdenum in the raw material composition of the flux core mainly reduce the risk of hydrogen embrittlement by improving corrosion resistance and increasing hydrogen traps; vanadium and titanium improve the strength and toughness of the material by refining grains and solid solution strengthening; aluminum improves the corrosion resistance and hydrogen resistance of the material by forming a dense oxide film and refining grains; the comprehensive application of these elements makes the hydrogen-resistant material perform well in high strength, high toughness and high corrosion resistance, and can be widely used in key structures and components in high-pressure hydrogen environments; the present invention has a short preparation cycle and high production efficiency, and the performance can be improved by adjusting the flux core composition and proportion, and at the same time, the flux-cored welding wire production is pollution-free and the welding process has high cladding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the microstructure of martensitic stainless steel in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] The invention provides a flux-cored welding wire for a hydrogen-resistant coating of pipeline steel, comprising an outer skin, wherein a flux core is filled in the outer skin, and the flux core is composed of the following raw material components by mass percentage: 3%-5% chromium, 1%-2% molybdenum, 2%-3% vanadium, 2%-4% titanium, 0.5%-1% aluminum, 0.4%-0.6% silicon, 1.5%-3% manganese, and 81.4%-89.6% iron, and the total mass percentage of the above components is 100%.

[0020] The outer skin is made of austenitic stainless steel. The filling rate of the core inside the outer skin is 20%-25%.

[0021] The present invention also provides a method for preparing a flux-cored welding wire for a pipeline steel hydrogen-resistant coating, comprising the following steps: Step 1, obtain the outer skin, and weigh the following raw material powders by mass percentage: chromium 3%-5%, molybdenum 1%-2%, vanadium 2%-3%, titanium 2%-4%, aluminum 0.5%-1%, silicon 0.4%-0.6%, manganese 1.5%-3%, iron 81.4%-89.6%, and the total mass percentage of the above raw material powders is 100%; The raw material powder can pass through the 80 mesh screen. The outer skin is made of 0Cr18Ni9 austenitic stainless steel.

[0022] Step 2: heating the raw material powder in an inert gas atmosphere and then keeping it warm; The heating temperature in step 2 is 150° C.-200° C. The holding time in step 2 is 2 h-2.5 h. The inert gas is argon gas with a purity of not less than 99.999%.

[0023] Step 3: Cool the raw material powder to room temperature, roll the outer skin into a U-shaped groove through a welding wire forming machine, fill the cooled raw material powder into the U-shaped groove, and make the original welding wire after passing through a closed forming roller; Step 4: The original welding wire is gradually reduced in diameter to produce a flux-cored welding wire of a set diameter for hydrogen-resistant coating of pipeline steel.

[0024] In the present invention, raw materials are heated in an inert gas atmosphere and then kept warm so as to remove moisture in the raw materials; the oil stains on the flux-cored welding wire for the pipeline steel anti-hydrogen coating prepared by the present invention are wiped with an alcohol cotton cloth, and then the finally prepared flux-cored welding wire is loaded on a disc and sealed for packaging; when in use, the prepared flux-cored welding wire for the pipeline steel anti-hydrogen coating is loaded into a full-automatic welding robot, and the prepared flux-cored welding wire is coated on a chromium substrate by using a molten extremely inert gas shielded welding method.

[0025] In the present invention, chromium is a key element to improve the corrosion resistance of the material, forming a dense chromium oxide film to effectively prevent the penetration of hydrogen; chromium forms a solid solution in the steel to improve the strength and hardness of the material; chromium can increase the hydrogen traps of the material, reduce the diffusion and aggregation of hydrogen in the material, and thus reduce the risk of hydrogen embrittlement.

[0026] Molybdenum also helps to form a dense oxide film, improving the corrosion resistance of the material; molybdenum forms a solid solution in steel and improves the strength and toughness of the material by refining the grains; molybdenum can effectively inhibit the diffusion of hydrogen, increase hydrogen traps, and reduce hydrogen embrittlement.

[0027] Vanadium refines the material grains and improves the strength and toughness of the material by forming carbides and nitrides; vanadium forms a solid solution in steel to improve the strength of the material; vanadium can increase hydrogen traps and reduce the diffusion and aggregation of hydrogen in the material, thereby reducing the risk of hydrogen embrittlement.

[0028] Titanium can increase hydrogen traps, reduce the diffusion and aggregation of hydrogen in the material, and thus reduce the risk of hydrogen embrittlement; titanium can stabilize carbides, prevent them from decomposing at high temperatures, and maintain the strength and toughness of the material.

[0029] Aluminum forms a dense aluminum oxide film on the surface of the material, improving the corrosion resistance of the material. Aluminum refines the material grains by forming nitrides and oxides, improving the strength and toughness of the material. Aluminum can increase hydrogen traps, reduce the diffusion and aggregation of hydrogen in the material, and thus reduce the risk of hydrogen embrittlement. Aluminum can improve the high-temperature stability of the material and prevent the material from undergoing phase change and grain growth at high temperatures.

[0030] During the welding process, the main functions of manganese and silicon are deoxidation and desulfurization, which reduce the content of oxygen and sulfur in the cladding alloy and prevent defects such as pores from forming in the cladding metal, resulting in a decrease in forming quality.

[0031] The invention has excellent hydrogen resistance and a simple preparation process, is very suitable for the preparation of hydrogen resistance coatings for pipeline steels, significantly improves the hydrogen resistance of pipeline steels, has good development prospects, and provides a new solution to the hydrogen corrosion problem currently faced by hydrogen transmission pipelines.

[0032] Example 1 This embodiment proposes a flux-cored welding wire for hydrogen-resistant coating of pipeline steel, including an outer skin, and a flux core filled in the outer skin, wherein the flux core is composed of the following raw material components by mass percentage: 3% chromium, 1% molybdenum, 2% vanadium, 2% titanium, 0.5% aluminum, 0.4% silicon, 1.5% manganese, and 89.6% iron. The outer skin is made of 0Cr18Ni9 austenitic stainless steel. The filling rate of the flux core in the outer skin is 20%.

[0033] Example 2 This embodiment proposes a flux-cored welding wire for hydrogen-resistant coating of pipeline steel, including an outer skin, and a flux core filled in the outer skin, wherein the flux core is composed of the following raw material components by mass percentage: 5% chromium, 2% molybdenum, 3% vanadium, 4% titanium, 1% aluminum, 0.6% silicon, 3% manganese, and 81.4% iron. The outer skin is made of 0Cr18Ni9 austenitic stainless steel. The filling rate of the flux core in the outer skin is 25%.

[0034] Example 3 This embodiment proposes a flux-cored welding wire for hydrogen-resistant coating of pipeline steel, including an outer skin, and a flux core filled in the outer skin, wherein the flux core is composed of the following raw material components by mass percentage: 4% chromium, 1.5% molybdenum, 2.5% vanadium, 3% titanium, 0.75% aluminum, 0.5% silicon, 2.25% manganese, and 85.5% iron. The outer skin is made of 0Cr18Ni9 austenitic stainless steel. The filling rate of the flux core in the outer skin is 22.5%.

[0035] Example 4 This embodiment provides a method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel, comprising the following steps: Step 1: Get the outer skin, and weigh the following raw material powders by mass percentage: 3% chromium, 1% molybdenum, 2% vanadium, 2% titanium, 0.5% aluminum, 0.4% silicon, 1.5% manganese, and 89.6% iron. The total mass percentage of the above raw material powders is 100%; The raw material powder can pass through the 80 mesh screen. The outer skin is made of 0Cr18Ni9 austenitic stainless steel.

[0036] Step 2: heating the raw material powder in an inert gas atmosphere and then keeping it warm; The heating temperature in step 2 is 150° C. The insulation time in step 2 is 2 h.

[0037] Step 3: Cool the raw material powder to room temperature, roll the outer skin into a U-shaped groove through a welding wire forming machine, fill the cooled raw material powder into the U-shaped groove, and make an original welding wire with a diameter of 1.9 mm after passing through a closed forming roller; Step 4: The original welding wire is gradually reduced in diameter to produce a flux-cored welding wire with a set diameter of 1.2 mm for hydrogen-resistant coating of pipeline steel.

[0038] The flux-cored welding wire for the hydrogen-resistant coating of pipeline steel prepared in this embodiment has a stable arc during welding, beautiful shaping, and no defects such as cracks and pores. The obtained hydrogen-resistant coating has a tensile strength of up to 753.8 MPa, an elongation of up to 22.1%, a hydrogen embrittlement sensitivity of 22.72%, and excellent hydrogen resistance.

[0039] Example 5 This embodiment provides a method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel, comprising the following steps: Step 1: Get the outer skin, and weigh the following raw material powders by mass percentage: 3.4% chromium, 1.2% molybdenum, 2.5% vanadium, 2.5% titanium, 0.7% aluminum, 0.5% silicon, 1.8% manganese, and 87.4% iron. The total mass percentage of the above raw material powders is 100%; The raw material powder can pass through the 80 mesh screen. The outer skin is made of 0Cr18Ni9 austenitic stainless steel.

[0040] Step 2: heating the raw material powder in an inert gas atmosphere and then keeping it warm; The heating temperature in step 2 is 200° C. The holding time in step 2 is 2.5 hours. The inert gas is argon gas with a purity of not less than 99.999%.

[0041] Step 3: Cool the raw material powder to room temperature, roll the outer skin into a U-shaped groove through a welding wire forming machine, fill the cooled raw material powder into the U-shaped groove, and make an original welding wire with a diameter of 1.9 mm after passing through a closed forming roller; Step 4: The original welding wire is gradually reduced in diameter to produce a flux-cored welding wire with a set diameter of 1.2 mm for hydrogen-resistant coating of pipeline steel.

[0042] The flux-cored welding wire for the hydrogen-resistant coating of pipeline steel prepared in this embodiment has a stable arc during welding, beautiful shaping, and no defects such as cracks and pores. The obtained hydrogen-resistant coating has a tensile strength of up to 793.1 MPa, an elongation of up to 20.6%, a hydrogen embrittlement sensitivity of 17.72%, and excellent hydrogen resistance.

[0043] Example 6 This embodiment provides a method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel, comprising the following steps: Step 1: Get the outer skin, and weigh the following raw material powders by mass percentage: 4% chromium, 1.5% molybdenum, 3% vanadium, 4% titanium, 0.5% aluminum, 0.6% silicon, 2% manganese, and 84.4% iron. The total mass percentage of the above raw material powders is 100%; The raw material powder can pass through the 80 mesh screen. The outer skin is made of 0Cr18Ni9 austenitic stainless steel.

[0044] Step 2: heating the raw material powder in an inert gas atmosphere and then keeping it warm; The heating temperature in step 2 is 175° C. The holding time in step 2 is 2.25 h. The inert gas is argon gas with a purity of not less than 99.999%.

[0045] Step 3: Cool the raw material powder to room temperature, roll the outer skin into a U-shaped groove through a welding wire forming machine, fill the cooled raw material powder into the U-shaped groove, and make an original welding wire with a diameter of 1.9 mm after passing through a closed forming roller; Step 4: The original welding wire is gradually reduced in diameter to produce a flux-cored welding wire with a set diameter of 1.20 mm for hydrogen-resistant coating of pipeline steel.

[0046] The flux-cored welding wire for the hydrogen-resistant coating of pipeline steel prepared in this embodiment has a stable arc during welding, beautiful shaping, and no defects such as cracks and pores. The obtained hydrogen-resistant coating has a tensile strength of up to 802.9 MPa, an elongation of up to 18.4%, a hydrogen embrittlement sensitivity of 15.92%, and excellent hydrogen resistance.

[0047] Example 7 This embodiment provides a method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel, comprising the following steps: Step 1: Get the outer skin, and weigh the following raw material powders by mass percentage: 5% chromium, 2% molybdenum, 2.7% vanadium, 3% titanium, 1% aluminum, 0.6% silicon, 1.6% manganese, and 84.1% iron. The total mass percentage of the above raw material powders is 100%; The raw material powder can pass through the 80 mesh screen. The outer skin is made of 0Cr18Ni9 austenitic stainless steel.

[0048] Step 2: heating the raw material powder in an inert gas atmosphere and then keeping it warm; The heating temperature in step 2 is 160° C. The holding time in step 2 is 2.5 hours. The inert gas is argon gas with a purity of not less than 99.999%.

[0049] Step 3: Cool the raw material powder to room temperature, roll the outer skin into a U-shaped groove through a welding wire forming machine, fill the cooled raw material powder into the U-shaped groove, and make an original welding wire with a diameter of 1.9 mm after passing through a closed forming roller; Step 4: The original welding wire is gradually reduced in diameter to produce a flux-cored welding wire with a set diameter of 1.2 mm for hydrogen-resistant coating of pipeline steel.

[0050] The flux-cored welding wire for the hydrogen-resistant coating of pipeline steel prepared in this embodiment has a stable arc during welding, beautiful shaping, and no defects such as cracks and pores. The obtained hydrogen-resistant coating has a tensile strength of up to 785.2 MPa, an elongation of up to 24.5%, a hydrogen embrittlement sensitivity of 14.03%, and excellent hydrogen resistance.

[0051] The microstructure of the martensitic stainless steel in the flux-cored welding wire for the hydrogen-resistant coating of pipeline steel obtained in this embodiment is as follows: Figure 1 As shown, the microstructure is austenite (A) + ferrite (δ-F) + martensite (M). It is obvious from the figure that the fine martensite structure can provide higher strength for the material, while the low content of ferrite and uniform austenite structure improve the toughness of the material. The martensite + ferrite + austenite structure can form a benign hydrogen trap to capture hydrogen atoms, so that hydrogen atoms are evenly distributed in the structure, thereby reducing the sensitivity to hydrogen embrittlement.

Claims

1. A flux-cored welding wire for hydrogen-resistant coating of pipeline steel, characterized in that: It includes an outer skin, and the outer skin is filled with a core, which is composed of the following raw material components by mass percentage: chromium 3%-5%, molybdenum 1%-2%, vanadium 2%-3%, titanium 2%-4%, aluminum 0.5%-1%, silicon 0.4%-0.6%, manganese 1.5%-3%, iron 81.4%-89.6%, and the total mass percentage of the above components is 100%.

2. The flux-cored welding wire for hydrogen-resistant coating of pipeline steel according to claim 1, characterized in that: The outer skin is made of austenitic stainless steel.

3. The flux-cored welding wire for hydrogen-resistant coating of pipeline steel according to claim 1, characterized in that: The filling rate of the drug core in the outer skin is 20%-25%.

4. A method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel, characterized in that: The following steps are involved: Step 1, obtain the outer skin, and weigh the following raw material powders by mass percentage: chromium 3%-5%, molybdenum 1%-2%, vanadium 2%-3%, titanium 2%-4%, aluminum 0.5%-1%, silicon 0.4%-0.6%, manganese 1.5%-3%, iron 81.4%-89.6%, and the total mass percentage of the above raw material powders is 100%; Step 2, heating the raw material powder in an inert gas atmosphere and then keeping it warm; Step 3: Cool the raw material powder to room temperature, roll the outer skin into a U-shaped groove through a welding wire forming machine, fill the cooled raw material powder into the U-shaped groove, close the shape and make the original welding wire after roller processing; Step 4: The original welding wire is gradually reduced in diameter to produce a flux-cored welding wire of a set diameter for hydrogen-resistant coating of pipeline steel.

5. The method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel according to claim 4, characterized in that: The raw material powder can pass through an 80-mesh sieve.

6. The method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel according to claim 4, characterized in that: The material of the outer skin is 0Cr18Ni9 austenitic stainless steel.

7. The method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel according to claim 4, characterized in that: The heating temperature in the step 2 is 150°C-200°C.

8. The method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel according to claim 4, characterized in that: The insulation time in step 2 is 2h-2.5h.

9. The method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel according to claim 4, characterized in that: The inert gas is argon with a purity of not less than 99.999%.

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