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

Abstract

The present invention discloses a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel. The wire comprises an outer sheath filled with a flux core, wherein the flux core is composed of the following raw material components by mass: 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. The method for preparing the flux-cored welding wire for a hydrogen-resistant coating for pipeline steel comprises the following steps: obtaining the outer sheath and weighing raw material powder by mass; heating the raw material powder in an inert gas atmosphere and then keeping it warm; cooling the raw material powder to room temperature, rolling the outer sheath into a U-shaped groove using a welding wire forming machine, filling the cooled raw material powder into the U-shaped groove, closing the groove to form the groove, and rolling the raw material powder to form the raw welding wire; and gradually reducing the diameter to form a flux-cored welding wire of a set diameter. Flux-cored welding wire used for hydrogen-resistant coating of pipeline steel has a short preparation cycle and high production efficiency. The performance can be improved by adjusting the composition and proportion of the flux core. At the same time, the production of flux-cored welding wire is pollution-free and the welding process has high cladding efficiency.

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 a pipeline steel hydrogen-resistant coating. Background Art

[0002] In modern industry, pipeline steel is widely used in the oil, natural gas, and chemical industries to transport high-pressure fluids. However, hydrogen is often present in these environments, particularly under high-temperature and high-pressure conditions. Hydrogen significantly affects material properties, often leading to a significant decline in the mechanical properties of iron-based alloys due to hydrogen embrittlement. Hydrogen-induced cracking is the primary cause of catastrophic brittle fracture in high-strength structural materials under low-stress conditions. Hydrogen embrittlement poses a serious threat to the safety and reliability of pipeline steel. Hydrogen embrittlement can significantly reduce the material's plasticity, leading to rapid crack propagation and even catastrophic fracture. Therefore, improving the hydrogen resistance of pipeline steel has become a key research topic in both industry and academia.

[0003] Traditional anti-hydrogen measures include material selection, alloying, heat treatment and other methods, but these methods often find it difficult to achieve 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 hydrogen-resistant 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 complex 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 of hydrogen-resistant coating and complicated process 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 sheath filled with a flux core, wherein 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, where the total mass percentage of the above components is 100%.

[0008] The present invention is also characterized in that:

[0009] The outer shell is made of austenitic stainless steel.

[0010] The filling rate of the drug core in the outer skin is 20%-25%.

[0011] Another technical solution adopted by the present invention is a method for preparing a flux-cored welding wire for a hydrogen-resistant coating on pipeline steel, comprising the following steps:

[0012] Step 1: Obtain the outer skin and weigh the following raw material powders 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. The total mass percentage of the above raw material powders is 100%;

[0013] Step 2: heating the raw material powder in an inert gas atmosphere and then keeping it warm;

[0014] 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 process it through a roller to produce the original welding wire;

[0015] Step 4: The original welding wire is reduced in diameter step by step to produce a flux-cored welding wire of a set diameter for hydrogen-resistant coating of pipeline steel.

[0016] Another technical solution of the present invention is also characterized in that:

[0017] The raw material powder can pass through an 80-mesh sieve.

[0018] The outer skin is made of 0Cr18Ni9 austenitic stainless steel.

[0019] The heating temperature in step 2 is 150°C-200°C.

[0020] The holding time in step 2 is 2h-2.5h.

[0021] The inert gas is argon with a purity of not less than 99.999%.

[0022] 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. 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

[0023] Figure 1 Schematic diagram of the microstructure of martensitic stainless steel in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] The present invention provides a flux-cored welding wire for hydrogen-resistant coating of pipeline steel, comprising an outer sheath filled with a flux core, wherein 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, where the total mass percentage of the above components is 100%.

[0026] The outer sheath is made of austenitic stainless steel, and the filling rate of the core inside the outer sheath is 20%-25%.

[0027] The present invention also provides a method for preparing a flux-cored welding wire for a hydrogen-resistant coating on pipeline steel, comprising the following steps:

[0028] Step 1: Obtain the outer skin and weigh the following raw material powders 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. The total mass percentage of the above raw material powders is 100%;

[0029] The raw material powder can pass through an 80-mesh screen. The outer shell is made of 0Cr18Ni9 austenitic stainless steel.

[0030] Step 2: heating the raw material powder in an inert gas atmosphere and then keeping it warm;

[0031] The heating temperature in step 2 is 150° C. to 200° C. The holding time in step 2 is 2 hours to 2.5 hours. The inert gas is argon with a purity of not less than 99.999%.

[0032] 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 pass through a closed forming roller to form the original welding wire;

[0033] Step 4: The original welding wire is reduced in diameter step by step to produce a flux-cored welding wire of a set diameter for hydrogen-resistant coating of pipeline steel.

[0034] In the present invention, raw materials are heated in an inert gas atmosphere and then kept warm to remove moisture from the raw materials; oil stains on the flux-cored welding wire for the pipeline steel hydrogen-resistant coating prepared by the present invention are wiped with an alcohol cotton cloth, and then the final flux-cored welding wire is placed on a reel and sealed for packaging; when in use, the prepared flux-cored welding wire for the pipeline steel hydrogen-resistant coating is loaded into a full-automatic welding robot, and the prepared flux-cored welding wire is coated on a chromium substrate using a metal-inert gas shielded welding method.

[0035] 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, improving the strength and hardness of the material; chromium can increase the hydrogen traps in the material, reduce the diffusion and aggregation of hydrogen in the material, and thus reduce the risk of hydrogen embrittlement.

[0036] 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.

[0037] 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, improving the strength of the material; vanadium can increase hydrogen traps, reduce the diffusion and aggregation of hydrogen in the material, and thus reduce the risk of hydrogen embrittlement.

[0038] 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.

[0039] Aluminum forms a dense aluminum oxide film on the material's surface, improving its corrosion resistance. Aluminum also refines the material's grain size by forming nitrides and oxides, increasing its strength and toughness. Aluminum also increases hydrogen trapping, reducing its diffusion and accumulation within the material, thereby reducing the risk of hydrogen embrittlement. Aluminum also improves the material's high-temperature stability, preventing phase transitions and grain growth at high temperatures.

[0040] During the welding process, the main functions of manganese and silicon are deoxidation and desulfurization, which reduce the oxygen and sulfur content in the surfacing alloy and prevent defects such as pores from forming in the surfacing metal, resulting in a decrease in forming quality.

[0041] The present invention has excellent hydrogen resistance and a simple preparation process, is very suitable for the preparation of hydrogen-resistant 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.

[0042] Example 1

[0043] This embodiment provides a flux-cored welding wire for hydrogen-resistant coatings on pipeline steel. The wire comprises an outer sheath filled with a flux core. The flux core is composed, by mass, of the following raw materials: 3% chromium, 1% molybdenum, 2% vanadium, 2% titanium, 0.5% aluminum, 0.4% silicon, 1.5% manganese, and 89.6% iron. The outer sheath is made of 0Cr18Ni9 austenitic stainless steel. The flux core fill rate within the outer sheath is 20%.

[0044] Example 2

[0045] This embodiment provides a flux-cored welding wire for hydrogen-resistant coatings on pipeline steel. The wire comprises an outer sheath filled with a flux core. The flux core is composed, by mass, of the following raw materials: 5% chromium, 2% molybdenum, 3% vanadium, 4% titanium, 1% aluminum, 0.6% silicon, 3% manganese, and 81.4% iron. The outer sheath is made of 0Cr18Ni9 austenitic stainless steel. The flux core fill rate within the outer sheath is 25%.

[0046] Example 3

[0047] This embodiment provides a flux-cored welding wire for hydrogen-resistant coatings on pipeline steel. The wire comprises an outer sheath filled with a flux core. The flux core is composed, by mass, of the following raw materials: 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 sheath is made of 0Cr18Ni9 austenitic stainless steel. The flux core fill rate within the outer sheath is 22.5%.

[0048] Example 4

[0049] This embodiment provides a method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel, comprising the following steps:

[0050] Step 1: Obtain 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%;

[0051] The raw material powder can pass through an 80-mesh screen. The outer shell is made of 0Cr18Ni9 austenitic stainless steel.

[0052] Step 2: heating the raw material powder in an inert gas atmosphere and then keeping it warm;

[0053] The heating temperature in step 2 is 150° C. The holding time in step 2 is 2 h.

[0054] Step 3: Cool the raw material powder to room temperature, roll the outer skin into a U-shaped groove through a wire forming machine, fill the cooled raw material powder into the U-shaped groove, and pass through a closed forming roller to form an original welding wire with a diameter of 1.9 mm;

[0055] Step 4: The original welding wire is reduced in diameter step by step to produce a flux-cored welding wire with a set diameter of 1.2 mm for hydrogen-resistant coating of pipeline steel.

[0056] 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.

[0057] Example 5

[0058] This embodiment provides a method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel, comprising the following steps:

[0059] Step 1: Obtain 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%;

[0060] The raw material powder can pass through an 80-mesh screen. The outer shell is made of 0Cr18Ni9 austenitic stainless steel.

[0061] Step 2: heating the raw material powder in an inert gas atmosphere and then keeping it warm;

[0062] The heating temperature in step 2 is 200° C. The holding time in step 2 is 2.5 hours. The inert gas is argon with a purity of not less than 99.999%.

[0063] Step 3: Cool the raw material powder to room temperature, roll the outer skin into a U-shaped groove through a wire forming machine, fill the cooled raw material powder into the U-shaped groove, and pass through a closed forming roller to form an original welding wire with a diameter of 1.9 mm;

[0064] Step 4: The original welding wire is reduced in diameter step by step to produce a flux-cored welding wire with a set diameter of 1.2 mm for hydrogen-resistant coating of pipeline steel.

[0065] 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.

[0066] Example 6

[0067] This embodiment provides a method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel, comprising the following steps:

[0068] Step 1: Obtain 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%;

[0069] The raw material powder can pass through an 80-mesh screen. The outer shell is made of 0Cr18Ni9 austenitic stainless steel.

[0070] Step 2: heating the raw material powder in an inert gas atmosphere and then keeping it warm;

[0071] The heating temperature in step 2 is 175° C. The holding time in step 2 is 2.25 hours. The inert gas is argon with a purity of not less than 99.999%.

[0072] Step 3: Cool the raw material powder to room temperature, roll the outer skin into a U-shaped groove through a wire forming machine, fill the cooled raw material powder into the U-shaped groove, and pass through a closed forming roller to form an original welding wire with a diameter of 1.9 mm;

[0073] 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.

[0074] 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.

[0075] Example 7

[0076] This embodiment provides a method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel, comprising the following steps:

[0077] Step 1: Obtain 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%;

[0078] The raw material powder can pass through an 80-mesh screen. The outer shell is made of 0Cr18Ni9 austenitic stainless steel.

[0079] Step 2: heating the raw material powder in an inert gas atmosphere and then keeping it warm;

[0080] The heating temperature in step 2 is 160° C. The holding time in step 2 is 2.5 hours. The inert gas is argon with a purity of not less than 99.999%.

[0081] 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 pass through a closed forming roller to form a raw welding wire with a diameter of 1.9 mm;

[0082] Step 4: The original welding wire is reduced in diameter step by step to produce a flux-cored welding wire with a set diameter of 1.2 mm for hydrogen-resistant coating of pipeline steel.

[0083] 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.

[0084] 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 in the figure, 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, making the hydrogen atoms evenly distributed in the structure, thereby reducing the sensitivity to hydrogen embrittlement.

Claims

1. Flux-cored welding wire for hydrogen-resistant coating of pipeline steel, characterized in that: The outer skin is filled with a core, wherein the 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%; The outer skin is made of austenitic stainless steel; The filling rate of the drug core in the outer skin is 20%-25%.

2. The method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel according to claim 1, wherein: The following steps are involved: Step 1: Obtain the outer skin and weigh the following raw material powders 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. 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 process it through a roller to produce the original welding wire; Step 4: The original welding wire is reduced in diameter step by step to produce a flux-cored welding wire of a set diameter for hydrogen-resistant coating of pipeline steel.

3. The method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel according to claim 2, characterized in that: The raw material powder can pass through an 80-mesh sieve.

4. The method for preparing a flux-cored welding wire for a hydrogen-resistant coating for pipeline steel according to claim 2, characterized in that: The outer skin is made of 0Cr18Ni9 austenitic stainless steel.

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

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

7. The method for preparing a flux-cored welding wire for hydrogen-resistant coating of pipeline steel according to claim 2, characterized in that: The inert gas is argon with a purity of not less than 99.999%.

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