A steel-cored welding wire and a method of manufacturing and use thereof

Abstract

The application provides a steel-cored welding wire and a preparation method and application thereof, and relates to the technical field of welding materials. The steel-cored welding wire comprises a steel belt and a steel core wrapped in the steel belt. The steel core comprises the following components and the content of each component in percentage of the mass of the steel core: chromium content 16.00-18.00%; nickel content 10.00-14.00%; molybdenum content 2.00-3.00%; carbon content ≤0.030%; manganese content ≤2.00%; silicon content ≤1.00%; phosphorus content ≤0.045%; sulfur content ≤0.030%; nitrogen content 0.7-0.9%, and the balance is iron and inevitable impurities. The steel-cored welding wire can effectively reduce the spatter rate and the generation probability of pores during welding, and can also inhibit the occurrence of hot cracks. The escape of nitrogen is effectively inhibited, the welding process is good, the droplet transition is more uniform during welding, the weld performance is more stable, and the mechanical performance is excellent.

Description

Technical Field

[0001] This invention relates to the field of welding materials technology, specifically to a steel-cored welding wire, its preparation method, and its applications. Background Technology

[0002] High-nitrogen austenitic stainless steel is a new type of steel in which nitrogen (N) replaces the expensive nickel (Ni) element as the main austenitizing element. Nitrogen dissolved in the steel possesses a high stacking fault energy, which not only optimizes the material's microstructure but also significantly improves its mechanical properties. Furthermore, high-nitrogen austenitic stainless steel offers numerous advantages, including lower cost, higher work hardening rate, and excellent corrosion resistance.

[0003] However, during welding, high-nitrogen austenitic stainless steel exhibits the phenomenon of dissolved nitrogen accumulating and escaping, leading to a decline in the performance of the welded joint. Therefore, weldability has become a key factor restricting its widespread application. It is noteworthy that the nitrogen content in the welding wire significantly affects the welding stability of high-nitrogen austenitic stainless steel. As the nitrogen content increases, electrical signal fluctuations become more pronounced and their distribution becomes more dispersed. Furthermore, increased nitrogen content also causes the molten droplet shape to become irregular and its size to increase, resulting in poorer welding wire processability. When the nitrogen content in the welding wire is below 0.40%, the welding process stability is good, but the welding spatter rate increases continuously with increasing nitrogen content. Nitrogen loss caused by nitrogen escape can easily lead to violent explosions of the high-nitrogen austenitic stainless steel droplets, generating a large amount of spatter, which in turn forms porosity in the joint, significantly reducing the mechanical properties of the welded joint. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention provides a steel-cored welding wire and its preparation method to improve the problem of nitrogen element aggregation and escape during welding of high-nitrogen austenitic stainless steel.

[0005] To achieve the above and other related objectives, a first aspect of the present invention provides a steel-cored welding wire, comprising a steel strip and a steel core encased within the steel strip. The steel strip, by mass percentage, comprises the following components and their contents: chromium 16.00%–18.00%, nickel 10.00%–14.00%, molybdenum 2.00%–3.00%, carbon ≤0.030%, manganese ≤2.00%, silicon ≤1.00%, phosphorus ≤0.045%, and sulfur ≤0.030%. The nitrogen content is 0.30% to 0.40%, with the balance being iron and unavoidable impurities; the steel core comprises the following components and their contents by mass percentage: chromium 16.00% to 18.00%; nickel 10.00% to 14.00%; molybdenum 2.00% to 3.00%; carbon ≤0.030%; manganese ≤2.00%; silicon ≤1.00%; phosphorus ≤0.045%; sulfur ≤0.030%; nitrogen 0.7% to 0.9%, with the balance being iron and unavoidable impurities.

[0006] In one embodiment of the present invention, the mass of the steel core is 80% to 85% of the total mass of the steel core welding wire.

[0007] In one embodiment of the present invention, the thickness of the steel strip is 0.2 to 0.4 mm, and the width of the steel strip is 10 to 14 mm.

[0008] In one embodiment of the present invention, the diameter of the steel core is 3.0 to 5.0 mm.

[0009] A second aspect of the present invention provides a method for preparing a steel-cored welding wire, comprising the following steps:

[0010] The steel strip is rolled into a U-shape;

[0011] Place the steel core inside the U-shaped steel strip, and then join the U-shaped steel strip together to form a circle;

[0012] The steel strip filled with the steel core is drawn and reduced in diameter to the required specification to obtain the steel core welding wire.

[0013] In one embodiment of the present invention, the diameter of the steel-cored welding wire is 1.2 to 1.6 mm.

[0014] A third aspect of the present invention provides an application of a steel-cored welding wire suitable for welding high-nitrogen austenitic stainless steel.

[0015] The steel-cored welding wire of this invention uses a high-nitrogen welding core with a steel strip covering the outside of the core. During welding, due to the skin effect of the current, the steel strip on the surface of the welding wire melts preferentially, followed by the melting of the steel core, with a certain melting time difference between the two. This feature effectively suppresses droplet transfer during welding of high-nitrogen austenitic stainless steel cores, thereby reducing spattering. It also effectively controls nitrogen overflow, resulting in weld metal that meets the composition and performance requirements, making it suitable for welding high-nitrogen austenitic stainless steel. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating the preparation process of the steel-cored welding wire of the present invention in one embodiment. Detailed Implementation

[0018] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of the present invention is for describing specific implementation schemes and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0019] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of the invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to the methods, devices, and materials in the embodiments of the present invention.

[0020] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" used in this specification are only for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as part of the scope of the invention.

[0021] This application provides a steel-cored welding wire, comprising a steel strip and a steel core wrapped within the steel strip. The steel strip, by mass percentage, comprises the following components and their contents: chromium 16.00%–18.00%, nickel 10.00%–14.00%, molybdenum 2.00%–3.00%, carbon ≤0.030%, manganese ≤2.00%, silicon ≤1.00%, phosphorus ≤0.045%, sulfur ≤0.030%, and nitrogen 0.30%–0. 40%, with the balance being iron and unavoidable impurities; the steel core comprises the following components and their contents by weight percentage: chromium 16.00%–18.00%; nickel 10.00%–14.00%; molybdenum 2.00%–3.00%; carbon ≤0.030%; manganese ≤2.00%; silicon ≤1.00%; phosphorus ≤0.045%; sulfur ≤0.030%; nitrogen 0.7%–0.9%, with the balance being iron and unavoidable impurities.

[0022] In one embodiment, the mass of the steel core is 80% to 85% of the total mass of the steel core welding wire, for example, any value among 80%, 83%, or 85%.

[0023] In one embodiment, the thickness of the steel strip is 0.2 to 0.4 mm, for example, the thickness of the steel strip is any value among 0.2 mm, 0.3 mm or 0.4 mm; the width of the steel strip is 10 to 14 mm, for example, any value among 10 mm, 11 mm, 13 mm or 14 mm.

[0024] In one embodiment, the diameter of the steel core is 3.0 to 5.0 mm, for example, the diameter of the steel core can be any value among 3 mm, 4 mm or 5 mm.

[0025] The steel-cored welding wire of this application uses a high-nitrogen austenitic stainless steel core with a nitrogen content of approximately 0.8%. Due to its high nitrogen content, if welding wire is produced solely using the steel core material, improper control can lead to increased porosity in the weld joint and a higher susceptibility to hot cracking. In the welding process of high-nitrogen austenitic stainless steel, when the weld is entirely austenitic, it exhibits very high susceptibility to hot cracking. This invention reduces the susceptibility to welding hot cracking by rationally adjusting the content of other alloying elements in the steel strip to generate a certain amount of high-temperature ferrite in the weld. Therefore, the nitrogen content of the steel strip is kept between 0.3% and 0.4%. By using a steel strip-coated steel core design to produce composite welding wire, the steel strip on the surface of the welding wire melts first during the welding process thanks to the skin effect of the current, followed by the melting of the steel core. The time difference between the two melting processes effectively suppresses droplet transfer during the welding of high-nitrogen austenitic stainless steel cores, thereby reducing spatter. At the same time, it can effectively control the overflow of nitrogen elements, thus obtaining weld metal that meets the composition and performance requirements, satisfying the high nitrogen content requirement of steel plates for welding materials.

[0026] Please see Figure 1 This application also provides a method for preparing a steel-cored welding wire, comprising the following steps:

[0027] S1. Roll the steel strip into a U-shape;

[0028] S2. Place the steel core inside the U-shaped steel strip, and close the U-shaped steel strip to form a circle;

[0029] S3. The steel strip filled with steel core is drawn and reduced in diameter to the required specification to obtain steel core welding wire.

[0030] In step S1, the steel strip comprises the following components and their contents by mass percentage: chromium 16.00%–18.00%, nickel 10.00%–14.00%, molybdenum 2.00%–3.00%, carbon ≤0.030%, manganese ≤2.00%, silicon ≤1.00%, phosphorus ≤0.045%; sulfur ≤0.030%, nitrogen 0.30%–0.40%, with the balance being iron and unavoidable impurities. For example, the thickness of the steel strip is 0.2–0.4 mm, such as any value from 0.2 mm, 0.3 mm, or 0.4 mm; the width of the steel strip is 10–14 mm, such as any value from 10 mm, 11 mm, 13 mm, or 14 mm.

[0031] In step S2, the steel core comprises the following components and their contents by mass percentage: chromium 16.00%–18.00%; nickel 10.00%–14.00%; molybdenum 2.00%–3.00%; carbon ≤0.030%; manganese ≤2.00%; silicon ≤1.00%; phosphorus ≤0.045%; sulfur ≤0.030%; nitrogen 0.7%–0.9%, with the balance being iron and unavoidable impurities.

[0032] In step S3, the diameter of the steel-cored welding wire is 1.2 to 1.6 mm, for example, any value among 1.2 mm, 1.4 mm or 1.6 mm.

[0033] The steel-cored welding wire prepared in this application can effectively reduce spatter and porosity during welding, while also suppressing hot cracking. Nitrogen escape is effectively suppressed, resulting in good welding processability, more uniform droplet transfer during welding, more stable weld properties, and excellent mechanical properties. It is suitable for welding high-nitrogen austenitic stainless steel.

[0034] The technical solution of the present invention will be described in detail below through several specific embodiments. Unless otherwise stated, the raw materials and reagents used in the following embodiments are all commercially available products, or can be prepared by conventional methods in the art, and the instruments used in the embodiments are all commercially available.

[0035] Example 1

[0036] The steel-cored welding wire of this embodiment includes a steel strip and a steel core wrapped within the steel strip. The steel strip, by mass percentage, comprises the following components and their contents: 16.00% chromium, 13.00% nickel, 3.00% molybdenum, 0.030% carbon, 1.8% manganese, 0.80% silicon, 0.045% phosphorus, 0.010% sulfur, and 0.40% nitrogen, with the balance being iron and unavoidable impurities. The steel core, by mass percentage, comprises the following... Composition and content of each component: Chromium 17.00%; Nickel 13.00%; Molybdenum 2.50%; Carbon 0.020%; Manganese 2.00%; Silicon 0.70%; Phosphorus 0.043%; Sulfur 0.020%; Nitrogen 0.8%, with the balance being iron and unavoidable impurities. The steel strip is rolled into a U-shape; a steel core is placed inside the U-shaped steel strip, and the U-shaped steel strip is joined together to form a circle; the steel strip filled with the steel core is drawn and reduced in diameter to the required specification to obtain the steel core welding wire.

[0037] In this embodiment, the diameter of the steel core is 5.0 mm, the width of the steel strip is 14 mm, the thickness of the steel strip is 0.4 mm, the diameter of the steel core welding wire is 1.6 mm, and the mass of the steel core is 85% of the total mass of the steel core welding wire.

[0038] Example 2

[0039] The steel-cored welding wire of this embodiment includes a steel strip and a steel core wrapped within the steel strip. The steel strip, by mass percentage, comprises the following components and their contents: 18.00% chromium, 14.00% nickel, 2.00% molybdenum, 0.020% carbon, 2% manganese, 0.90% silicon, 0.044% phosphorus, 0.010% sulfur, and 0.40% nitrogen, with the balance being iron and unavoidable impurities. The steel core, by mass percentage, comprises the following components: The composition and content of each component are as follows: chromium 16.00%; nickel 12.00%; molybdenum 3.0%; carbon 0.025%; manganese 1.90%; silicon 0.90%; phosphorus 0.040%; sulfur 0.030%; nitrogen 0.85%, with the balance being iron and unavoidable impurities. The steel strip is rolled into a U-shape; a steel core is placed inside the U-shaped steel strip, and the U-shaped steel strip is joined together to form a circle; the steel strip filled with the steel core is drawn and reduced in diameter to the required specification to obtain the steel core welding wire.

[0040] In this embodiment, the diameter of the steel core is 4.0 mm, the width of the steel strip is 12 mm, the thickness of the steel strip is 0.3 mm, the diameter of the steel core welding wire is 1.4 mm, and the mass of the steel core is 83% of the total mass of the steel core welding wire.

[0041] Example 3

[0042] The steel-cored welding wire of this embodiment includes a steel strip and a steel core wrapped within the steel strip. The steel strip, by mass percentage, comprises the following components and their contents: 18.00% chromium, 10.00% nickel, 2.50% molybdenum, 0.025% carbon, 1.7% manganese, 1.00% silicon, 0.044% phosphorus; 0.020% sulfur, 0.30% nitrogen, with the balance being iron and unavoidable impurities. The steel core, by mass percentage, comprises the following components: The following components and their contents are as follows: Chromium 18.00%; Nickel 10.00%; Molybdenum 3.0%; Carbon 0.03%; Manganese 1.80%; Silicon 0.90%; Phosphorus 0.045%; Sulfur 0.020%; Nitrogen 0.70%, with the balance being iron and unavoidable impurities. The steel strip is rolled into a U-shape; a steel core is placed inside the U-shaped steel strip, and the U-shaped steel strip is joined together to form a circle; the steel strip filled with the steel core is drawn and reduced in diameter to the required specification to obtain the steel core welding wire.

[0043] In this embodiment, the diameter of the steel core is 3.0 mm, the width of the steel strip is 10 mm, the thickness of the steel strip is 0.2 mm, the diameter of the steel core welding wire is 1.2 mm, and the mass of the steel core is 81% of the total mass of the steel core welding wire.

[0044] Example 4

[0045] The steel-cored welding wire of this embodiment includes a steel strip and a steel core wrapped within the steel strip. The steel strip, by mass percentage, comprises the following components and their contents: 17.50% chromium, 12.00% nickel, 2.00% molybdenum, 0.030% carbon, 1.60% manganese, 0.70% silicon, 0.040% phosphorus; 0.025% sulfur, 0.35% nitrogen, with the balance being iron and unavoidable impurities. The steel core, by mass percentage, comprises the following... The following components and their contents are as follows: Chromium 16.50%; Nickel 14.00%; Molybdenum 2.8%; Carbon 0.025%; Manganese 1.60%; Silicon 0.70%; Phosphorus 0.040%; Sulfur 0.03%; Nitrogen 0.70%, with the balance being iron and unavoidable impurities. The steel strip is rolled into a U-shape; a steel core is placed inside the U-shaped steel strip, and the U-shaped steel strip is joined together to form a circle; the steel strip filled with the steel core is drawn and reduced in diameter to the required specification to obtain the steel core welding wire.

[0046] In this embodiment, the diameter of the steel core is 5.0 mm, the width of the steel strip is 14 mm, the thickness of the steel strip is 0.3 mm, the diameter of the steel core welding wire is 1.2 mm, and the mass of the steel core is 80% of the total mass of the steel core welding wire.

[0047] Example 5

[0048] The steel-cored welding wire of this embodiment includes a steel strip and a steel core wrapped within the steel strip. The steel strip, by mass percentage, comprises the following components and their contents: 17.00% chromium, 12.00% nickel, 2.50% molybdenum, 0.021% carbon, 1.80% manganese, 0.80% silicon, 0.045% phosphorus; 0.030% sulfur, 0.35% nitrogen, with the balance being iron and unavoidable impurities. The steel core, by mass percentage, comprises the following... The following components and their contents are as follows: Chromium 17.00%; Nickel 14.00%; Molybdenum 2.0%; Carbon 0.03%; Manganese 1.50%; Silicon 0.80%; Phosphorus 0.040%; Sulfur 0.015%; Nitrogen 0.90%, with the balance being iron and unavoidable impurities. The steel strip is rolled into a U-shape; a steel core is placed inside the U-shaped steel strip, and the U-shaped steel strip is joined together to form a circle; the steel strip filled with the steel core is drawn and reduced in diameter to the required specification to obtain the steel core welding wire.

[0049] In this embodiment, the diameter of the steel core is 4.0 mm, the width of the steel strip is 12 mm, the thickness of the steel strip is 0.2 mm, the diameter of the steel core welding wire is 1.4 mm, and the mass of the steel core is 80% of the total mass of the steel core welding wire.

[0050] Comparative Example 1

[0051] In this comparative example, the welding wire is a solid welding wire of uniform material. The chemical composition of the welding wire, by mass percentage, is as follows: chromium 17.50%, nickel 12.00%, molybdenum 2.00%, carbon 0.030%, manganese 1.60%, silicon 0.70%, phosphorus 0.040%, sulfur 0.025%, nitrogen 0.8%, with the balance being iron and unavoidable impurities. The diameter of the welding wire in this comparative example is 1.2 mm.

[0052] Comparative Example 2

[0053] In this comparative example, the welding wire is a solid welding wire of uniform material. The chemical composition of the welding wire, by mass percentage, is as follows: chromium 17.00%, nickel 12.00%, molybdenum 2.50%, carbon 0.021%, manganese 1.80%, silicon 0.80%, phosphorus 0.045%, sulfur 0.030%, nitrogen 0.65%, with the balance being iron and unavoidable impurities. The diameter of the welding wire in this comparative example is 1.4 mm.

[0054] Comparative Example 3

[0055] In this comparative example, the welding wire is a solid welding wire of uniform material. The chemical composition of the welding wire, by mass percentage, is as follows: chromium 16.00%, nickel 13.00%, molybdenum 3.00%, carbon 0.030%, manganese 1.8%, silicon 0.80%, phosphorus 0.045%, sulfur 0.010%, nitrogen 0.70%, with the balance being iron and unavoidable impurities. The diameter of the welding wire in this comparative example is 1.6 mm.

[0056] Welding tests were conducted on the welding wires prepared in Examples 1 to 5 and Comparative Examples 1 to 3. The chemical composition of the deposited metal was tested according to the standard GB / T29713-2013 Stainless Steel Welding Wire and Strip, and the mechanical properties of the welded joints were also tested. The welding process performance and nitrogen content of the deposited metal are shown in Table 1, and the mechanical properties of the welded joints are shown in Table 2.

[0057] Table 1: Welding process performance and nitrogen content of weld metal prepared in Examples 1 to 5 and Comparative Examples 1 to 3

[0058]

[0059] Table 2: Mechanical properties of welded joints when welded using welding wires prepared in Examples 1 to 5 and Comparative Examples 1 to 3

[0060]

[0061] As can be seen from Table 1, the steel-cored welding wire of this application has good arc stability, little spatter, beautiful forming, and stable nitrogen content.

[0062] The steel-cored welding wire of this invention uses a high-nitrogen welding core with a steel strip covering the outside of the core. During welding, due to the skin effect of the current, the steel strip on the surface of the welding wire melts preferentially, followed by the core, with a certain melting time difference between the two. This feature effectively suppresses droplet transfer during welding of high-nitrogen austenitic stainless steel cores, thereby reducing spattering. Simultaneously, it effectively controls nitrogen overflow, resulting in weld metal that meets composition and performance requirements, making it suitable for welding high-nitrogen austenitic stainless steel. Therefore, this invention effectively overcomes some practical problems in the prior art, thus possessing high utilization value and practical significance.

[0063] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A steel-cored welding wire, characterized in that, The steel-cored welding wire comprises a steel strip and a steel core encased within the steel strip. The steel strip, by mass percentage, is composed of the following components, with the following content: chromium 16.00%~18.00%, nickel 10.00%~14.00%, molybdenum 2.00%~3.00%, carbon ≤0.030%, manganese ≤2.00%, silicon ≤1.00%, phosphorus ≤0.045%; sulfur ≤0.030%, nitrogen 0.30%~0.40%, with the balance being iron and unavoidable impurities. The steel core, by mass percentage... According to the specifications, the steel core is composed of the following components, with the following content: chromium 16.00%~18.00%; nickel 10.00%~14.00%; molybdenum 2.00%~3.00%; carbon ≤0.030%; manganese ≤2.00%; silicon ≤1.00%; phosphorus ≤0.045%; sulfur ≤0.030%; nitrogen 0.7%~0.9%, with the balance being iron and unavoidable impurities; the mass of the steel core is 80%~85% of the total mass of the steel core welding wire; the steel core welding wire is suitable for welding high-nitrogen austenitic stainless steel.

2. A method for preparing the steel-cored welding wire according to claim 1, characterized in that, Includes the following steps: The steel strip is rolled into a U-shape; Place the steel core inside the U-shaped steel strip, and then join the U-shaped steel strip together to form a circle; The steel strip filled with the steel core is drawn and reduced in diameter to the required specification to obtain the steel core welding wire.

3. The preparation method according to claim 2, characterized in that, The diameter of the steel-cored welding wire is 1.2~1.6mm.

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