Solid welding wire for gas shielded metal arc welding

Abstract

This invention provides a solid welding wire for gas-shielded metal arc welding (GSAW) that produces less fume during welding and is suitable as a welding material for high-Mn steel. The solid welding wire for GSAW of this invention has the following composition by mass percent: C: 0.2–0.8%, Si: 0.15–0.90%, Mn: 17.0–28.0%, P: less than 0.03%, S: less than 0.03%, Ni: 0.01–10.00%, Cr: 0.4–4.0%, Mo: 0.01–3.50%, B: less than 0.0010%, N: less than 0.12%, with the balance being Fe and unavoidable impurities. It should be noted that, depending on the need, it may contain one or more of V, Ti, and Nb, and one or more of Cu, Al, Ca, and REM.

Description

[0001] This application is a divisional application of Chinese invention patent application No. 201980054255.7 (international application No. PCT / JP2019 / 014537), with the Chinese national phase entry date of February 19, 2021 (international application date of April 1, 2019) and the invention title "Solid Welding Wire for Gas Shielded Metal Arc Welding". Technical Field

[0002] This invention relates to solid welding wire for gas shielded metal arc welding, and particularly to solid welding wire for welding high-Mn steel in extremely low temperature environments. Background Technology

[0003] In recent years, environmental regulations have become increasingly stringent. Liquefied natural gas (LNG), being sulfur-free, is considered a clean fuel that does not produce air pollutants such as sulfur oxides, leading to increased demand. For the transportation or storage of LNG, containers (tanks) must maintain excellent cryogenic impact toughness at temperatures below the liquefaction temperature of LNG, which is -162°C.

[0004] However, based on the necessity of maintaining excellent low-temperature impact toughness, aluminum alloys, 9% Ni steel, and austenitic stainless steel have been used as materials for containers (cans) in the past.

[0005] However, aluminum alloys have low tensile strength, necessitating thicker structural plates and exhibiting poor weldability. Furthermore, 9% Ni steel requires expensive Ni-based welding materials, making it economically disadvantageous. Additionally, austenitic stainless steels are expensive and have low base metal strength.

[0006] Starting from this problem, the application of high-Mn steel, containing approximately 10% to 35% Mn by mass, has recently been studied as a material for containers (tanks) used for transporting or storing LNG. High-Mn steel has the following characteristics: it remains in the austenitic phase even at extremely low temperatures, does not undergo brittle fracture, and has high strength compared to austenitic stainless steels. Therefore, it is desirable to develop welding materials capable of stably welding such high-Mn steel.

[0007] To address such expectations, Patent Document 1, for example, proposes "a high-strength welded joint with excellent low-temperature impact toughness and a flux-cored arc welding wire for use therein." The flux-cored arc welding wire described in Patent Document 1 contains, by weight percent: C: 0.15–0.8%, Si: 0.2–1.2%, Mn: 15–34%, Cr: ≤6%, Mo: 1.5–4%, S: ≤0.02%, P: ≤0.02%, B: ≤0.01%, Ti: 0.09–0.5%, N: 0.001–0.3%, TiO2: 4–15%, total of one or more selected from SiO2, ZrO2, and Al2O3: 0.01–9%, total of one or more selected from K, Na, and Li: 0.5–1.7%, one or more selected from F and Ca: 0.2–1.5%, with the balance being Fe and other unavoidable impurities. When welding with the flux-cored arc welding wire described in Patent Document 1, it is possible to effectively obtain a weld joint with excellent low-temperature toughness of 28 J or more in Charpy impact test at a test temperature of -196°C and high strength of 400 MPa or more at room temperature. In addition, by adjusting the composition of the welding wire to Mo: 1.5% or more, it is possible to ensure a weld joint with excellent resistance to high-temperature cracking.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Publication No. 2017-502842 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, according to the inventor's research, the technology described in Patent Document 1 has the following problem: the amount of fumes generated during welding increases, and the welder is exposed to an environment with a large amount of fumes.

[0013] The purpose of this invention is to solve the problems of the prior art mentioned above, and to provide a solid welding wire for gas shielded metal arc welding that produces less smoke and dust during welding, is suitable as a welding material for high Mn steel used in extremely low temperature environments, and can produce weld joints with both high strength and excellent extremely low temperature toughness.

[0014] It should be noted that the "low amount of fume generated during welding" mentioned here refers to the following situation: According to JIS Z3930-2013, the amount of fume generated during gas shielded metal arc welding with a shielding gas composition of 80%Ar+20%CO2 and a welding current of 250A is less than 1200mg / min.

[0015] Furthermore, "high strength" as mentioned here refers to a room temperature yield strength (0.2% endurance) of 400 MPa or higher for the weld metal prepared according to JIS Z 3111. Additionally, "excellent low-temperature toughness" refers to the absorbed energy vE of the Charpy impact test at a test temperature of -196°C for the weld metal prepared according to JIS Z 3111. -196 For cases with a value of 28J or higher.

[0016] Methods for solving problems

[0017] To achieve the above objectives, the inventors first conducted an in-depth study on the factors affecting the amount of fume generated during gas-shielded metal arc welding. The results showed that using solid welding wire instead of flux-cored wire is effective in significantly reducing fume generation. However, for solid welding wire, which requires a larger amount of drawing work compared to flux-cored wire, especially in cases with high Mn content, cracking and wire breakage are prone to occur during drawing. To address this problem, the inventors discovered that drawing can be performed by suppressing the formation of boron nitride and carbides in the steel. Based on these research findings, a new discovery has been made: by adjusting the composition of solid welding wire to the following specific ranges, particularly adjusting C to 0.2–0.8%, Si to 0.15–0.9%, Mn to 17.0–28.0%, Ni to 0.01–10.0%, Cr to 0.4–4.0%, and Mo to 0.01–3.5%, and further reducing B (an impurity) to less than 0.0010% and Ti, Nb, and V (carbide-forming elements) to below 0.04%, defects such as cracks will not occur during wire drawing, the solid welding wire will have excellent manufacturability, and the amount of smoke generated during welding will be low. Furthermore, it is possible to manufacture high-strength wire with a room-temperature yield strength (0.2% endurance) of over 400 MPa and a Charpy impact test absorption energy vE at a test temperature of -196°C. -196 It is a welded joint with high strength above 28J and excellent impact toughness at extremely low temperatures.

[0018] This invention was completed based on the above insights and further research, and the main points of this invention are as follows.

[0019] (1) A solid welding wire for gas-shielded metal electrode arc welding, characterized in that it has the following composition: by mass % containing C: 0.2-0.8%, Si: 0.15-0.90%, Mn: 17.0-28.0%, P: less than 0.03%, S: less than 0.03%, Ni: 0.01-10.00%, Cr: 0.4-4.0%, Mo: 0.01-3.50%, B: less than 0.0010%, N: less than 0.12%, with the balance consisting of Fe and unavoidable impurities.

[0020] (2) The solid welding wire for gas shielded metal arc welding as described in (1) above is characterized in that, based on the above composition, it further contains, by mass%, one or more of the following: V: less than 0.04%, Ti: less than 0.04%, and Nb: less than 0.04%.

[0021] (3) The solid welding wire for gas shielded metal arc welding as described in (1) or (2) above is characterized in that, based on the above composition, it further contains, by mass%, one or more of the following: Cu: less than 1.0%, Al: less than 0.1%, Ca: less than 0.01%, and REM: less than 0.02%.

[0022] Invention Effects

[0023] According to the present invention, a solid welding wire for gas-shielded metal arc welding is provided that has excellent manufacturability, can significantly suppress the amount of smoke generated during gas-shielded metal arc welding, and can be easily manufactured as a welding material for high-Mn steel to produce weld joints with high strength and excellent low-temperature toughness, which has significant industrial benefits. Detailed Implementation

[0024] The solid welding wire of the present invention is a gas-shielded metal arc welding (GSAW) wire suitable for use in gas-shielded metal arc welding of high-Mn steel. The solid welding wire of the present invention enables the welding of high-Mn steel to each other while reducing fume generation, and the weld metal produced according to JIS Z 3111 is a weld metal with high strength of 400 MPa or more at room temperature (0.2% endurance) and excellent low-temperature toughness with a Charpy impact test absorption energy of 28 J or more at a test temperature of -196°C. It is a welding material capable of producing weld joints with high strength and excellent low-temperature toughness.

[0025] The solid welding wire of the present invention, as a basic component, has the following composition by mass%: C: 0.2-0.8%, Si: 0.15-0.90%, Mn: 17.0-28.0%, P: less than 0.03%, S: less than 0.03%, Ni: 0.01-10.00%, Cr: 0.4-4.0%, Mo: 0.01-3.50%, B: less than 0.0010%, N: less than 0.12%, with the balance being Fe and unavoidable impurities.

[0026] First, the reasons for defining the composition will be explained. It should be noted that "mass%" in the composition will be abbreviated as "%" below.

[0027] C: 0.2-0.8%

[0028] Carbon (C) is an element that increases the strength of weld metal through solid solution strengthening. Additionally, C stabilizes the austenite phase, improving the extremely low temperature impact toughness of the weld metal. To achieve this effect, a content of 0.2% or more is required. However, when the content exceeds 0.8%, carbide precipitation occurs, reducing the extremely low temperature toughness and making high-temperature cracking during welding more likely. Therefore, the C content is limited to the range of 0.2% to 0.8%. It should be noted that 0.4% to 0.6% is preferred.

[0029] Si: 0.15~0.90%

[0030] Si acts as a deoxidizer, improving the yield of Mn, increasing the viscosity of the molten metal, stabilizing the weld shape, and reducing spatter. To achieve these effects, a content of 0.15% or more is required. However, a content exceeding 0.90% reduces the extremely low temperature toughness of the weld metal. Furthermore, Si segregates during solidification, forming a liquid phase at the solidification unit interface, which reduces resistance to high-temperature cracking. Therefore, the Si content is limited to the range of 0.15% to 0.90%. It should be noted that 0.2% to 0.7% is preferred.

[0031] Mn: 17.0~28.0%

[0032] Mn is an inexpensive element that stabilizes the austenite phase, and in this invention, it is required to contain 17.0% or more. When Mn is less than 17.0%, a ferrite phase is formed in the weld metal, significantly reducing toughness at extremely low temperatures. On the other hand, when Mn exceeds 28.0%, excessive Mn segregation occurs during solidification, inducing high-temperature cracking. Therefore, the Mn content is limited to the range of 17.0% to 28.0%. It should be noted that 18.0% to 26.0% is preferred.

[0033] P: below 0.03%

[0034] Phosphorus (P) is an element that causes segregation at grain boundaries and induces high-temperature cracks. In this invention, it is preferable to minimize its content, but it is permissible if it is below 0.03%. Therefore, P is limited to below 0.03%. It should be noted that excessive reduction leads to a significant increase in refining costs. Therefore, P is preferably adjusted to 0.003% or more.

[0035] S: below 0.03%

[0036] Sulfide (S) exists in weld metal as sulfide inclusions, specifically MnS. MnS acts as a fracture initiation point, thus reducing cryogenic toughness. Therefore, S content is limited to 0.03% or less. It should be noted that excessive reduction leads to increased refining costs. Therefore, S content is preferably adjusted to 0.001% or more.

[0037] Ni: 0.01~10.00%

[0038] Ni is an element that strengthens austenite grain boundaries, causing segregation at these boundaries and improving low-temperature impact toughness. To achieve this effect, a content of 0.01% or higher is required. Additionally, Ni has a stabilizing effect on the austenite phase; therefore, further increasing its content stabilizes the austenite phase and improves the low-temperature impact toughness of the weld metal. However, Ni is an expensive element, and a content exceeding 10.00% becomes economically unfavorable. Therefore, the Ni content is limited to 0.01–10.00%.

[0039] Cr: 0.4–4.0%

[0040] Cr acts as an element that stabilizes the austenite phase at extremely low temperatures, thus improving the low-temperature impact toughness of the weld metal. In addition, Cr also increases the strength of the weld metal. Furthermore, Cr effectively raises the liquidus line of the molten metal and inhibits the formation of high-temperature cracks. Moreover, Cr effectively improves the corrosion resistance of the weld metal. To achieve these effects, a content of 0.4% or more is required. When the Cr content is less than 0.4%, the above effects cannot be guaranteed. On the other hand, when the content exceeds 4.0%, Cr carbides are formed, leading to a decrease in low-temperature toughness. Furthermore, the formation of carbides reduces the machinability of the welding wire during drawing. Therefore, the Cr content is limited to the range of 0.4% to 4.0%. It should be noted that 0.8% to 3.0% is preferred.

[0041] Mo: 0.01%~3.50%

[0042] Mo is an element that strengthens austenite grain boundaries. It segregates at these grain boundaries, increasing the strength of the weld metal. This effect becomes significant when the content is above 0.01%. It should be noted that when the content exceeds 0.01%, it also increases the strength of the weld metal through solid solution strengthening. On the other hand, when the content exceeds 3.50%, it precipitates as carbides, reducing hot workability. Furthermore, it induces cracks during wire drawing, reducing the manufacturability of the weld wire. Therefore, the Mo content is limited to the range of 0.01% to 3.50%.

[0043] B: Less than 0.0010%

[0044] Boron (B), as an impurity mixed into steel, segregates at the austenite grain boundaries. When B content exceeds 0.0010%, boron nitride forms at the austenite grain boundaries, reducing grain boundary strength. This reduction in grain boundary strength causes the austenite grain boundaries to become fracture initiation points during wire drawing, resulting in wire breakage and reduced wire drawing processability and manufacturability. The formation of boron nitride can be suppressed by limiting B content to less than 0.0010%, therefore, B is limited to less than 0.0010%. It should be noted that 0.0009% or less is preferred, and 0.0008% or less is more preferred. It should be noted that excessive reduction leads to increased refining costs. Therefore, B content is preferably adjusted to 0.0001% or more.

[0045] N: below 0.12%

[0046] Nitrogen (N) is an unavoidable inclusion element, and like carbon (C), it effectively contributes to increasing the strength of weld metal and stabilizing the austenite phase, thus steadily improving low-temperature toughness. This effect becomes significant when the content is 0.003% or higher, therefore, a content of 0.003% or higher is preferred. However, when the content exceeds 0.12%, nitrides form, reducing low-temperature toughness. Therefore, the content of N is limited to 0.12% or less.

[0047] In the solid welding wire of the present invention, the above-mentioned components are the basic components. In the present invention, based on the above-mentioned basic components, one or more of the following can be selected as optional components: V: less than 0.04%, Ti: less than 0.04%, and Nb: less than 0.04%, and / or one or more of the following can be selected as optional components: Cu: less than 1.0%, Al: less than 0.1%, Ca: less than 0.01%, and REM: less than 0.02%.

[0048] Selected from one or more of V: ​​less than 0.04%, Ti: less than 0.04%, and Nb: less than 0.04%.

[0049] V, Ti, and Nb are all elements that promote the formation of carbides and help improve the strength of weld metal. One or more of them can be selected as needed.

[0050] V: Below 0.04%

[0051] V is a carbide-forming element that causes the precipitation of fine carbides, which helps to improve the strength of the weld metal. To achieve this effect, a content of 0.001% or more is preferred. However, when the content exceeds 0.04%, the carbides become coarse, becoming the initiation point for cracks during the drawing process of solid welding wire, reducing the wire's workability and manufacturability. Therefore, when present, the V content is limited to 0.04% or less.

[0052] Ti: below 0.04%

[0053] Furthermore, Ti is a carbide-forming element, causing the precipitation of fine carbides, which helps improve the strength of the weld metal. Additionally, Ti causes carbides to precipitate at the solidification unit interfaces of the weld metal, helping to suppress the initiation of high-temperature cracks. To achieve this effect, a content of 0.001% or more is preferred. However, when the Ti content exceeds 0.04%, the carbides become coarse, becoming the initiation point for cracks during the drawing process of solid welding wire, reducing wire drawing processability and manufacturability. Therefore, when present, the Ti content is limited to 0.04% or less.

[0054] Nb: below 0.04%

[0055] Furthermore, nitrogen (Nb) is a carbide-forming element, which helps to increase the strength of weld metal by causing carbide precipitation. Additionally, Nb causes carbides to precipitate at the solidification unit interfaces of the weld metal, helping to suppress the initiation of high-temperature cracks. To achieve this effect, a content of 0.001% or more is preferred. However, when Nb exceeds 0.04%, the carbides become coarse, becoming the initiation point for cracks during the drawing process of solid welding wire, reducing wire drawing processability and manufacturability. Therefore, when present, the Nb content is limited to 0.04% or less.

[0056] Selected from one or more of the following: Cu: less than 1.0%, Al: less than 0.1%, Ca: less than 0.01%, and REM: less than 0.02%.

[0057] Cu is an element that helps stabilize austenite, Al is an element that improves weldability, and Ca and REM are elements that help improve machinability. You can choose to include one or more of these elements as needed.

[0058] Cu: below 1.0%

[0059] Cu is an element that stabilizes the austenite phase, even at extremely low temperatures, thereby improving the low-temperature impact toughness of weld metals. To achieve this effect, a content of 0.01% or more is preferred. However, when the content exceeds 1.0% and is present in large quantities, thermal ductility decreases, and the manufacturability of the welding wire deteriorates. Therefore, when present, the Cu content is limited to 1.0% or less.

[0060] Al: below 0.1%

[0061] Al acts as a deoxidizer, playing a crucial role in increasing the viscosity of the molten metal, stabilizing the weld shape, and reducing spatter. Furthermore, Al raises the liquidus temperature of the molten metal, helping to suppress high-temperature cracking in the weld metal. This effect becomes significant when the content is 0.005% or higher, therefore, a content of 0.005% or higher is preferred. However, when the content exceeds 0.1%, the viscosity of the molten metal becomes excessively high, which increases spatter, weld non-propagation, and poor fusion defects. Therefore, when present, the Al content is limited to 0.1% or less. It should be noted that 0.005% to 0.06% is preferred.

[0062] Ca: below 0.01%

[0063] In molten metal, Ca combines with S to form high-melting-point sulfides, CaS. CaS has a higher melting point than MnS, thus maintaining a spherical shape during the hot working of solid welding wires instead of stretching along the rolling direction, which improves the machinability of the wires. This effect becomes significant when the Ca content is above 0.001%. On the other hand, when the Ca content exceeds 0.01%, arc disturbance occurs during welding, making stable welding difficult. Therefore, in cases where Ca is present, the content is limited to 0.01% or less.

[0064] REM: below 0.02%

[0065] REM is a powerful deoxidizer, existing in weld metal as REM oxides. REM oxides serve as nucleation sites during solidification, thereby refining the grain size and contributing to increased weld metal strength. This effect becomes significant at concentrations above 0.001%. However, concentrations exceeding 0.02% decrease arc stability. Therefore, when present, REM content is limited to below 0.02%.

[0066] The balance other than the above components consists of Fe and unavoidable impurities.

[0067] Next, the manufacturing method of the solid welding wire of the present invention will be described.

[0068] In the manufacture of the solid welding wire of the present invention, molten steel having the above-described composition is used and the annealing temperature is set to 900–1200°C. Other than this, there is no particular limitation on the manufacturing method, and commonly used methods for manufacturing solid welding wires can be applied. Specifically, it is preferable to sequentially perform a casting process in which molten steel having the above-described composition is melted in a commonly used melting furnace such as an electric furnace or a vacuum melting furnace and cast in a mold of a specified shape; a heating process in which the obtained steel ingot is heated to a specified temperature; a hot rolling process in which the heated steel ingot is hot-rolled to form a steel raw material (bar) of a specified shape; and a cold rolling process in which the obtained steel raw material (bar) is cold-rolled (cold-drawn) more than twice and annealed as needed to form a welding wire of the desired size.

[0069] The present invention will be further described below based on embodiments.

[0070] Example

[0071] The molten steel with the composition shown in Table 1 was melted in a vacuum melting furnace and cast to produce 1000 kg steel ingots. The resulting steel ingots were heated to 1200°C and then hot-rolled and subsequently cold-rolled to produce 1.2 mm Φ solid welding wire for gas-shielded metal arc welding. It should be noted that during the manufacturing of the welding wire, the manufacturability of each solid welding wire was evaluated by measuring the rolling load (drawing load), observing cracks, and observing the wire cross-section. Cases where the rolling load (drawing load) was too high to allow for rolling (drawing), cases where cracks were observed, and cases where subsequent processes could not be performed due to cracks were evaluated as "×". All other cases were evaluated as "○".

[0072] In addition, a flux-cored welding wire with the composition of metal powder and flux adjusted to the manner shown in Table 2 was prepared as a comparative example. It should be noted that, as the outer sheath, a thin steel plate (0.5 mm thick) with a composition of 0.1% C, 0.2% Si, 0.5% Mn, and the balance Fe (by mass%) was used. The adjusted metal powder and flux were encapsulated in the aforementioned outer sheath and drawn to a diameter of 1.2 mm. It should be noted that the composition shown in Table 2 is the total value of the outer sheath, metal powder, and flux.

[0073] First, using the solid or flux-cored welding wires obtained as shown in Tables 1 and 2 as welding materials, gas-shielded metal arc welding was performed in a welding fume collection device according to JIS Z 3390. The generated fumes were collected using a filter material (made of glass fiber), and the fume generation rate (mg / min) was measured. The welding conditions were set as follows: current: 250A, voltage: 34V, welding speed: 30cm / min, shielding gas: 80%Ar + 20%CO2 (flow rate: 20L / min).

[0074] In addition, according to JIS Z 3111, a high-Mn steel plate (thickness: 12mm) for ultra-low temperature applications was prepared as a test plate and butt-welded to form a 45° V-groove. The resulting solid welding wire was used as the welding material for gas-shielded metal arc welding, and deposited metal was obtained within this groove. It should be noted that the steel plate used as the test plate is a high-Mn steel plate for ultra-low temperature applications with a composition of 0.5% C, 0.4% Si, 25% Mn, 3% Cr, and the balance Fe (by mass%).

[0075] For welding, use the solid welding wire (1.2 mm in diameter) or flux-cored welding wire (1.2 mm in diameter) with the compositions shown in Tables 1 and 2, without preheating, and perform the welding in a downward orientation under the following conditions: current: 180–330 A (DCEP), voltage: 24–33 V, welding speed: 30 cm / min, interpass temperature: 100–150 °C, and shielding gas: 80% Ar + 20% CO2.

[0076] After welding, the weld metal is observed using an optical microscope to determine the presence or absence of weld cracks. Weld cracks are high-temperature cracks; if crack formation is observed, it is evaluated as a reduction in high-temperature crack resistance and is marked "×". If no crack formation is observed, it is evaluated as excellent high-temperature crack resistance and is marked "○".

[0077] The weld appearance is judged by visual inspection. If undercut, weld beads, or pits are observed, the weld appearance is considered poor and rated as "×". If no such defects are observed, the weld appearance is considered good and rated as "○".

[0078] According to JIS Z 3111, tensile test pieces (parallel portion diameter 6mmΦ) and Charpy impact test pieces (V-notch) of the deposited metal are cut from the obtained deposited metal, and tensile tests and impact tests are carried out.

[0079] Tensile tests were performed on three specimens at room temperature, and the average value (0.2% endurance) was taken as the tensile property of the weld metal using the solid welding wire. Additionally, Charpy impact tests were performed on three specimens, and the absorbed energy vE at the test temperature of -196°C was determined. -196 The average value of this value is taken as the cryogenic impact toughness of the weld metal using the solid welding wire.

[0080] The results are shown in Table 3.

[0081]

[0082] [Table 3]

[0083] It can be said that the examples of this invention are all welding wires with excellent manufacturability, and the amount of fume generated during gas shielded metal electrode arc welding with a welding current of 250A according to JIS Z 3930-2013 is less than 1200mg / min, and the amount of fume generated is low.

[0084] Furthermore, it can be said that all examples of the present invention can achieve welding without the generation of welding cracks (high-temperature cracks), excellent resistance to high-temperature cracking, and a yield strength (0.2% endurance) of over 400 MPa at room temperature, and the absorbed energy vE of the Charpy impact test at a test temperature of -196°C. -196 Welding materials (solid welding wire) for welding metals with a J of 28J or higher, which combine high strength and excellent low-temperature toughness.

[0085] On the other hand, in comparative examples outside the scope of this invention, the following conditions may be met: high dust generation exceeding 1200 mg / min; poor manufacturability of the welding wire; reduced high-temperature crack resistance due to welding cracks (high-temperature cracks); weld defects; 0.2% strength at room temperature less than 400 MPa; or low absorbed energy vE. -196 Less than 28J, it is impossible to obtain the desired weld metal with low smoke generation, high strength and excellent low-temperature toughness.

[0086] Welding wires No. 14 and No. 15 (comparative examples) have low C and Cr content, which is outside the scope of this invention. Therefore, the 0.2% strength of the deposited metal is less than 400 MPa, and the desired high strength cannot be ensured. Furthermore, welding wires No. 16, No. 17, No. 18, and No. 19 (comparative examples) have high Mn or Ti, B, Cr, and Nb content, which is outside the scope of this invention. Therefore, the wire drawing processability is reduced, and it cannot be drawn to the desired wire diameter. Additionally, welding wire No. 20 (comparative example) has low Mn content, which is outside the scope of this invention. Therefore, the stability of the austenite phase is low, and thus the absorbed energy vE is low. -196 At J less than 28J, the extremely low temperature toughness decreases. Furthermore, No. 21 (comparative example) has a low Ni content, which is outside the scope of this invention; therefore, the absorbed energy vE is low. -196At a temperature below 28 J, the extremely low temperature toughness decreases. Furthermore, welding wires No. 22, No. 23, and No. 24 (comparative examples) have high Si, P, and C content, which is outside the scope of this invention, thus causing welding cracks and reducing high-temperature cracking resistance. Additionally, welding wire No. 25 (comparative example) has low Si content, which is outside the scope of this invention, and welding wire No. 26 (comparative example) has high Al content, which is also outside the scope of this invention, thus failing to obtain a good weld shape and producing pits or weld beads. Furthermore, welding wires No. 27, No. 28, No. 29, and No. 30, which are comparative examples, are flux-cored welding wires, therefore generating more than 1200 mg / min of fume.

Claims

1. A solid welding wire for gas-shielded metal electrode arc welding, characterized in that, It has the following composition by mass%: C: 0.2-0.8%, Si: 0.15-0.90%, Mn: 17.0-28.0%, P: less than 0.03%, S: less than 0.03%, Ni: 0.01-10.00%, Cr: 0.4-4.0%, Mo: 0.01-3.50%, B: less than 0.0010%, N: 0.003-0.12%, V: 0.001-0.04%, with the balance consisting of Fe and unavoidable impurities.

2. The solid welding wire for gas-shielded metal arc welding according to claim 1, characterized in that, Based on the aforementioned composition, it also contains, by mass%, one or both selected from Ti: less than 0.04% and Nb: less than 0.04%.

3. The solid welding wire for gas-shielded metal arc welding according to claim 1 or 2, characterized in that, Based on the aforementioned composition, it further contains, by mass%, one or more of the following: Cu: less than 1.0%, Al: less than 0.1%, Ca: less than 0.01%, and REM: less than 0.02%.

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