Super duplex stainless steel flux-cored wire with high toughness and resistance to hydrogen and preparation method thereof

Abstract

The application discloses a super duplex stainless steel flux-cored wire with high toughness and hydrogen resistance and a preparation method thereof. The super duplex stainless steel flux-cored wire comprises a sheath and a core powder filled in the sheath. The core powder is composed of the following components: Cr, Ni, Mo, TiN, Nb, Mn, Si and iron powder. In the preparation, the raw materials are weighed according to the above percentages, and the raw materials are heated and kept in an inert gas atmosphere to obtain the core powder. Then, the sheath is selected and rolled into a U-shaped groove through a forming machine. The core powder is filled into the U-shaped groove, and the flux-cored wire is formed through a method of gradually reducing the diameter of the closed forming roller. The application solves the problem that the super duplex stainless steel flux-cored wire in the prior art is difficult to have high strength and high hydrogen resistance at the same time, and greatly improves the strength of the joint after welding.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of welding materials, and particularly relates to super duplex stainless steel flux-cored wire with high toughness and hydrogen resistance. BACKGROUND

[0002] In modern industry, super duplex stainless steel has been widely used in the fields of petroleum, natural gas and chemical industry. The existence of hydrogen atoms in a hydrogen environment has higher requirements for the performance of welding materials. Since hydrogen is the element with the smallest relative atomic mass in the periodic table, it is easy to enter the metal material. When the hydrogen content in the metal material reaches a certain concentration, it will cause a series of irreversible hydrogen damage such as hydrogen blistering, hydrogen-induced cracking and hydride. Therefore, hydrogen embrittlement has always been a key problem restricting the use of high-strength steel. When external load exists, hydrogen will be enriched at defects through stress-induced hydrogen diffusion, causing a significant decrease in the plasticity of metal materials, causing hydrogen lagging cracks, thereby leading to failure and cracking of welded joints in industrial production, causing economic losses. Therefore, how to improve the hydrogen resistance of welded joints has become a major pain point in the industry.

[0003] Existing hydrogen resistance measures, such as alloying, introduce impurities to form hydrogen traps to capture hydrogen atoms when producing hydrogen storage materials, thereby achieving hydrogen resistance. However, this requires precise control of the addition amount of refining agents and special production equipment, which affects the performance of the material, resulting in a decrease in the strength, plasticity and other properties of the material. Heat treatment requires a large amount of energy to heat and maintain temperature during production due to its high energy consumption, and heat treatment is difficult to implement in the field, especially for large equipment and welded joints. These traditional hydrogen resistance measures have obvious shortcomings and cannot meet the needs of materials for high performance and high hydrogen resistance. Therefore, it is crucial to develop a welding material that can meet the strength and toughness requirements of welded joints and also meet their hydrogen resistance ability. SUMMARY

[0004] The purpose of the present application is to provide super duplex stainless steel flux-cored wire with high toughness and hydrogen resistance, which solves the problem that super duplex stainless steel flux-cored wire in the prior art cannot simultaneously have high toughness and high hydrogen resistance, and greatly improves the strength of the joint after welding.

[0005] Another purpose of the present application is to provide a preparation method of super duplex stainless steel flux-cored wire with high toughness and hydrogen resistance.

[0006] The first technical solution of the present application is a super duplex stainless steel flux-cored wire with high toughness and hydrogen resistance, which comprises a welding sheath and a core powder filled in the welding sheath, and the core powder is composed of the following components in percentage by mass: Cr: 32.3%~35.8%, Ni: 1%~4%, Mo: 10%~14%, TiN: 0.5%~3%, Nb: 0.1%~1%, Mn: 2%~5%, Si: 0.5%~1.0%, and the rest is iron powder, and the total content of the above components is 100%.

[0007] The first technical solution of the present application is further characterized in that,

[0008] The welding sheath is a 0Cr18Ni9 austenitic stainless steel strip.

[0009] The filling amount of the core powder in the welding sheath is 18%~23%.

[0010] The second technical solution of the present application is a preparation method of a super duplex stainless steel flux-cored wire with high toughness and hydrogen resistance, which specifically comprises the following steps:

[0011] Step 1, the following raw materials are weighed in percentage by mass respectively:

[0012] Cr: 32.3%~35.8%, Ni: 1%~4%, Mo: 10%~14%, TiN: 0.5%~3%, Nb: 0.1%~1%, Mn: 2%~5%, Si: 0.7%~3.2%, and the rest is iron powder, and the total content of the above raw materials is 100%;

[0013] Step 2, the raw material powder is heated and kept in an inert gas atmosphere to remove moisture to obtain the core powder;

[0014] Step 3, the outer skin is selected and placed on the tape placing machine of the wire forming machine, and the outer skin is rolled into a U-shaped groove through the pressure groove of the forming machine;

[0015] Step 4, after the core powder in step 2 is cooled to room temperature, it is filled into the U-shaped groove, and after passing through the closed forming roller, it is finally formed into a flux-cored wire by the method of gradually reducing the diameter.

[0016] The second technical solution of the present application is further characterized in that,

[0017] The particle size of each raw material in step 1 is 90 mesh~110 mesh.

[0018] The inert gas in step 2 is argon with a purity of 99.999%.

[0019] The heating temperature in step 2 is 150℃~200℃, and the holding time is 2h~2.5h.

[0020] The outer skin is an austenitic stainless steel strip of 0Cr18Ni9, the width of the outer skin is 6mm-8mm, and the thickness is 0.3mm-0.4mm.

[0021] The filling amount of the core powder filled into the U-shaped groove in step 4 is 18%-23%.

[0022] The present application has the following advantages:

[0023] The preparation method of the high-toughness hydrogen-resistant super duplex stainless steel flux-cored wire has the advantages that the corrosion resistance is improved and the hydrogen trap is increased to reduce the risk of hydrogen embrittlement by adding chromium and molybdenum; the corrosion resistance of the welding wire is improved by adding niobium (Nb) elements, thereby improving the welding performance; the mechanical properties of the weld after welding are improved, the pores in the welding process are inhibited, and the strength of the welded joint is improved by adding Mn elements; the hydrogen-resistant material has excellent performance in high strength, high toughness and high corrosion resistance, and is widely used in key structures and components in high-pressure hydrogen gas environment.

[0024] Meanwhile, the high-toughness hydrogen-resistant super duplex stainless steel flux-cored wire has the advantages of short preparation period, high production efficiency, improved performance by adjusting the composition and proportion of the core, no pollution in the production of the flux-cored wire, and high cladding efficiency in the welding process. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a schematic diagram of the micro tube of the flux-cored wire prepared in the embodiment 6 of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] Embodiment 1

[0028] The high-toughness hydrogen-resistant super duplex stainless steel flux-cored wire comprises a welding skin and a core powder filled in the welding skin, and the core powder is composed of the following components in mass percentage: Cr: 32.3%-35.8%, Ni: 1%-4%, Mo: 10%-14%, TiN: 0.5%-3%, Nb: 0.1%-1%, Mn: 2%-5%, Si: 0.5%-1.0%, and the rest is iron powder, and the total content of the above components is 100%.

[0029] Further, the welding skin is an austenitic stainless steel strip of 0Cr18Ni9.

[0030] Further, the filling amount of the powder in the sheath is 18% to 23%.

[0031] The super duplex stainless steel flux-cored wire with high toughness and hydrogen resistance has short preparation period and high production efficiency, and can improve performance by adjusting the components and proportion of the flux core, and the flux-cored wire production is pollution-free and the cladding efficiency in the welding process is high.

[0032] Specifically, the chromium (Cr) element is an important element for improving the corrosion resistance of the material, and it reacts with oxygen to form a dense chromium oxide film. The oxide film attached to the surface effectively prevents hydrogen penetration. Chromium not only forms a solid solution in steel, which improves the hardness and strength of the material, but also increases the hydrogen traps of the material, so that hydrogen does not diffuse and aggregate in the material, greatly reducing the risk of hydrogen embrittlement.

[0033] The molybdenum (Mo) element also promotes the formation of an oxide film, thereby improving the corrosion resistance of the material. Cobalt not only forms a solid solution in steel, which improves the hardness and strength of the material by refining the grain size, but also increases the hydrogen traps of the material, so that hydrogen does not diffuse and aggregate in the material, greatly reducing the risk of hydrogen embrittlement.

[0034] The main effects of adding Ni element include improving the corrosion resistance, heat crack resistance, strength and toughness of the welded joint. Specifically: improving corrosion resistance: Ni element can significantly improve the corrosion resistance of the welded joint, especially in harsh environments such as chemical corrosion and seawater corrosion, the welded joint has better corrosion resistance. Improve the heat crack resistance: during the welding process, the welded joint is prone to thermal cracks when heated and cooled, and Ni element can effectively inhibit and reduce the occurrence of thermal cracks, thereby improving the heat crack resistance of the welded joint. Improve the strength and toughness: the addition of Ni element can make the welded joint have certain strength and toughness, thereby increasing the service life and stability of the welded joint.

[0035] The selected TiN has a NaCl type crystal structure, and the dislocation degree with ferrite is very small, which promotes heterogeneous nucleation of ferrite, refines the ferrite grain boundary, and the refinement of ferrite provides a large number of grain boundaries for the formation of GBA, so that austenite is preferentially formed in the form of GBA, and the amount of intragranular austenite is reduced. (Need more supercooling).

[0036] The main effects of adding niobium (Nb) element include improving corrosion resistance and improving welding performance. In 1Cr13 martensitic stainless steel, different contents of niobium iron and vanadium iron (3.2 wt.%, 6 wt.%, 10 wt.%) are added to carry out surfacing test, and the results show that with the increase of niobium iron and vanadium iron content in the flux-cored wire, the number of precipitated phases in the surfacing deposited metal gradually increases, these precipitated phases are Nb and V containing carbonitride, which can effectively inhibit the formation of Cr-rich precipitated phase and increase the effective Cr content in the matrix. A large number of uniformly distributed precipitated phases are beneficial to the corrosion from multiple positions, which promotes the uniform corrosion of the surfacing deposited metal, thereby improving the corrosion resistance of the surfacing deposited metal.

[0037] The main effects of adding manganese (Mn) element include improving the mechanical properties of the weld: manganese element can improve the hardness and strength of the weld, thereby enhancing the mechanical properties of the welded joint. When the manganese content is between 0.6% and 1.8%, the weld metal has high strength and toughness. Improve the toughness of the welded joint: manganese element has a significant effect on the toughness of the weld metal. When the manganese content is between 0.6% and 1.8%, the weld metal has high strength and toughness.

[0038] The main effects of adding silicon (Si) element include deoxidation, prevention of pore formation and optimization of weld microstructure. Silicon is the most commonly used deoxidizing element in welding wire, which can prevent iron from combining with oxygen and reduce FeO in the molten pool. However, when using silicon alone for deoxidation, the generated SiO2 has a high melting point (about 1710℃), and the generated particles are small and difficult to float out of the molten pool, which can easily lead to slag inclusion in the weld metal.

[0039] Example 2

[0040] The application has a preparation method of high-toughness hydrogen-resistant super duplex stainless steel flux-cored wire, which specifically comprises the following steps:

[0041] Step 1, the following raw materials are weighed according to the mass percentage:

[0042] Cr: 32.3%~35.8%, Ni: 1%~4%, Mo: 10%~14%, TiN: 0.5%~3%, Nb: 0.1%~1%, Mn: 2%~5%, Si: 0.7%~3.2%, the rest is iron powder, the total content of the above raw materials is 100%;

[0043] Further, the particle size of each raw material is 90 mesh~110 mesh.

[0044] Step 2, heat and keep the raw material powder in an inert gas atmosphere to remove moisture to obtain a core powder;

[0045] Further, the inert gas in step 2 is argon with a purity of 99.999%.

[0046] Further, the heating temperature in step 2 is 150-200 DEG C, and the holding time is 2-2.5 h.

[0047] Step 3, the outer skin is placed on the tape machine of the welding wire forming machine, and the outer skin is rolled into a U-shaped groove through the pressure groove of the forming machine;

[0048] Further, the outer skin is 0Cr18Ni9 austenitic stainless steel strip, the width of the outer skin is 6-8 mm, and the thickness is 0.3-0.4 mm.

[0049] Step 4, after the core powder in step 2 is cooled to room temperature, it is filled into the U-shaped groove, and finally forms the flux-cored wire through the method of gradually reducing the diameter after the closed forming roller.

[0050] Further, the filling amount of the core powder filled into the U-shaped groove in step 4 is 18-23%.

[0051] The prepared flux-cored wire is wiped with alcohol cotton cloth to remove oil stains on the flux-cored wire, and is sealed and packaged in a tray, the prepared flux-cored wire is loaded into a full-automatic welding robot, and the prepared flux-cored wire is used for surfacing on a 42Cr substrate by using a MIG welding method.

[0052] The preparation method of the super duplex stainless steel flux-cored wire with high toughness and hydrogen resistance provided by the application, through the comprehensive application of various chemical components, the hydrogen-resistant material performs well in high strength, high toughness and high corrosion resistance, and is widely used in key structures and components in high-pressure hydrogen environment.

[0053] Example 3

[0054] Step 1, the following raw materials are weighed according to the mass percentage: Cr: 32.8%, Ni: 2.97%, Mo: 10%, TiN: 1.0%, Nb: 0.1%, Mn: 5%, Si: 0.5%, and the rest is iron powder. The sum of the mass percentages of the above components is 100%.

[0055] Step 2, the raw material powder weighed in step 1 is heated and held in an inert gas atmosphere to remove moisture to obtain a core powder;

[0056] In step 2, the heating temperature is 150-200 DEG C, and the holding time is 2-2.5 h.

[0057] Step 3, the outer skin is placed on the tape machine of the welding wire forming machine, and the outer skin is rolled into a U-shaped groove through the pressure groove of the forming machine;

[0058] Step 4: After the core powder obtained in Step 2 is cooled to room temperature, the powder is filled into the U-shaped groove at a filling amount of 20%, and after passing through the closed forming roller, a 1.9mm welding wire is prepared, and finally a 1.20mm metal type flux-cored wire is prepared by gradually reducing the diameter.

[0059] The oil stains on the flux-cored wire are wiped with alcohol cotton cloth, and the prepared flux-cored wire is loaded into a full-automatic welding robot. The prepared flux-cored wire is used for coating and surfacing on a 42Cr substrate by MIG welding. The arc is stable during welding, the shape is beautiful, and there are no defects such as cracks and pores. The obtained hydrogen-resistant coating has a tensile strength of 791.8MPa, an elongation of 33.1%, and a hydrogen embrittlement sensitivity of 10.98%. The hydrogen resistance is excellent and meets the use requirements.

[0060] Example 4

[0061] Step 1: The following raw materials are weighed according to the mass percentage: Cr: 35.8%, Ni: 1.97%, Mo: 12.28%, TiN: 0.5%, Nb: 0.5%, Mn: 2%, Si: 0.5%, and the rest is iron powder. The sum of the mass percentages of the above components is 100%.

[0062] Step 2: The raw material powder weighed in Step 1 is heated and kept in an inert gas atmosphere to remove moisture, and a core powder is obtained.

[0063] In Step 2, the heating temperature is 150℃-200℃, and the holding time is 2h-2.5h.

[0064] Step 3: The sheath is placed on the tape machine of the welding wire forming machine, and the sheath is rolled into a U-shaped groove through the pressure groove of the forming machine.

[0065] Step 4: After the core powder obtained in Step 2 is cooled to room temperature, the powder is filled into the U-shaped groove at a filling amount of 23%, and after passing through the closed forming roller, a 1.9mm welding wire is prepared, and finally a 1.20mm metal type flux-cored wire is prepared by gradually reducing the diameter.

[0066] The oil stains on the flux-cored wire are wiped with alcohol cotton cloth, and the prepared flux-cored wire is loaded into a full-automatic welding robot. The prepared flux-cored wire is used for coating and surfacing on a 42Cr substrate by MIG welding. The arc is stable during welding, the shape is beautiful, and there are no defects such as cracks and pores. The obtained hydrogen-resistant coating has a tensile strength of 791.8MPa, an elongation of 33.1%, and a hydrogen embrittlement sensitivity of 10.98%. The hydrogen resistance is excellent and meets the use requirements.

[0067] Example 5

[0068] Step 1, the following raw materials are weighed according to the mass percentage: Cr: 32.3%, Ni: 1%, Mo: 14%, TiN: 3%, Nb: 1%, Mn: 4.2%, Si: 1%, and the rest is iron powder. The sum of the mass percentages of the above components is 100%.

[0069] Step 2, the raw material powder weighed in step 1 is heated and kept in an inert gas atmosphere to remove moisture, obtaining a core powder;

[0070] In step 2, the heating temperature is 150-200℃, and the holding time is 2-2.5h.

[0071] Step 3, the sheath is placed on the tape machine of the welding wire forming machine, and the sheath is rolled into a U-shaped groove through the pressure groove of the forming machine;

[0072] Step 4, the core powder obtained in step 2 is cooled to room temperature after holding, then the powder is filled into the U-shaped groove, the filling amount is 18%, and after passing through the closed forming roller, 1.9mm welding wire is prepared, and finally 1.20mm metal type flux-cored wire is prepared by gradually reducing the diameter.

[0073] The oil stains on the flux-cored wire are wiped with alcohol cotton cloth, the prepared flux-cored wire is loaded into the full-automatic welding robot, and the prepared flux-cored wire is used for coating and surfacing on the 42Cr substrate by MIG welding method. The arc is stable during welding, the shape is beautiful, and there are no defects such as cracks and pores. The tensile strength of the obtained hydrogen-resistant coating can reach 789.9MPa, the elongation can reach 31.4%, the hydrogen embrittlement sensitivity is 8.21%, the hydrogen resistance performance is excellent, and it meets the use requirements.

[0074] Example 6

[0075] Step 1, the following raw materials are weighed according to the mass percentage: Cr: 33.8%, Ni: 4%, Mo: 12.28%, TiN: 1.0%, Nb: 0.5%, Mn: 2.2%, Si: 1.0%, and the rest is iron powder. The sum of the mass percentages of the above components is 100%.

[0076] Step 2, the raw material powder weighed in step 1 is heated and kept in an inert gas atmosphere to remove moisture, obtaining a core powder;

[0077] In step 2, the heating temperature is 150-200℃, and the holding time is 2-2.5h.

[0078] Step 3, the sheath is placed on the tape machine of the welding wire forming machine, and the sheath is rolled into a U-shaped groove through the pressure groove of the forming machine;

[0079] Step 4: The core powder obtained in step 2 is kept warm and cooled down to room temperature in the furnace, then the powder is filled into a U-shaped groove with a filling amount of 19%, and after the closed forming roller, a 1.9mm welding wire is prepared, and finally a 1.20mm metal type flux-cored wire is prepared by gradually reducing the diameter.

[0080] The oil stains on the flux-cored wire are wiped with alcohol cotton cloth, and the prepared flux-cored wire is loaded into a full-automatic welding robot, and the prepared flux-cored wire is used for coating and surfacing on a 42Cr substrate by using MIG welding method. The arc is stable during welding, the shaping is beautiful, and there are no defects such as cracks and pores. The obtained hydrogen-resistant coating has a tensile strength of 843.5MPa, an elongation of 37.5%, and a hydrogen embrittlement sensitivity of 6.03%, and has excellent hydrogen resistance.

[0081] As shown in Figure 1 , the microstructure of the weld after welding in the embodiment is austenite + ferrite. It can be seen from the figure that the austenite structure provides high strength for the material, and the low content of ferrite and uniform austenite structure also provide good toughness for the material. By adding TiN, Nb and other elements, nucleation points are provided, the columnar grains in traditional surfacing of duplex stainless steel are changed, and the corrosion resistance and hydrogen resistance of duplex stainless steel are enhanced.

[0082] Finally, it should be noted that in this document, the terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or equipment including the element.

[0083] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same or similar parts between various embodiments can be referred to each other.

[0084] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Therefore, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A super duplex stainless steel flux-cored wire having high toughness against hydrogen, comprising a sheath and a core powder filled in the sheath, characterized in that, The drug core powder consists of the following components in percentage by mass: Cr: 32.3%~35.8%, Ni: 1%~4%, Mo: 10%~14%, TiN: 0.5%~3%, Nb: 0.1%~1%, Mn: 2%~5%, Si: 0.5%~1.0%, and the rest is iron powder, and the total of the above components is 100%. The welding skin is a 0Cr18Ni9 austenitic stainless steel strip; The filling amount of the drug core powder in the welding skin is 18%~23%.

2. A preparation method of super duplex stainless steel drug core welding wire with high toughness and hydrogen resistance, specifically comprising the following steps: Step 1: the following raw materials are weighed in percentage by mass respectively: Cr: 32.3%~35.8%, Ni: 1%~4%, Mo: 10%~14%, TiN: 0.5%~3%, Nb: 0.1%~1%, Mn: 2%~5%, Si: 0.7%~3.2%, and the rest is iron powder, and the total of the above raw materials is 100%; Step 2: the raw material powder is heated and kept in an inert gas atmosphere to remove moisture to obtain a drug core powder; Step 3: the outer skin is selected and placed on the strip placing machine of the welding wire forming machine, and the outer skin is rolled into a U-shaped groove through the pressing groove of the forming machine; Step 4: after the drug core powder in step 2 is cooled to room temperature, it is filled into the U-shaped groove, and after passing through the closed forming roller, it is finally formed into a drug core welding wire through the method of gradually reducing the diameter; The outer skin is a 0Cr18Ni9 austenitic stainless steel strip, and the width of the outer skin is 6mm~8mm and the thickness is 0.3mm~0.4mm; The filling amount of the drug core powder filled into the U-shaped groove in step 4 is 18%~23%.

3. The method of manufacturing high toughness hydrogen resistant super duplex stainless steel flux cored wire as claimed in claim 2, wherein, The particle size of each raw material in step 1 is 90 mesh~110 mesh.

4. The method for preparing a super duplex stainless steel flux-cored welding wire with high toughness and hydrogen resistance according to claim 2, wherein: The inert gas in step 2 is argon with a purity of 99.999%.

5. The method of manufacturing super duplex stainless steel flux cored wire with high toughness against hydrogen of claim 2, characterized in that, The heating temperature in step 2 is 150℃~200℃, and the holding time is 2h~2.5h.

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