TWI295603B - Solid wires for gas-shielded arc welding - Google Patents

Description

1295603 (1) EMBODIMENT OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gas-protected type such as an automobile thin steel sheet such as a low-carbon steel sheet and a high-strength steel sheet having a thickness of 〇·6 to 10 mm. Solid wire for arc welding. [Prior Art] The structure of gas-shielded arc welding must have a high quality, and its production must provide more complete labor saving and higher efficiency. In the automotive industry, for example, the fully automated welding industry using welding robots has been introduced, which is welded at a speed of about 1.0 m/min in current commercial production lines: it is necessary to weld at higher speeds with higher efficiency. . The thin steel plate structure is an important technological opportunity to meet global environmental issues. Among them, in order to reduce the weight and improve the fuel efficiency, the automobile industry urgently needs to use the specifications (reduced size) of high-strength steel sheets. However, the obtained welded product does not show the original fatigue strength of the high-strength steel sheet material because the fatigue strength of the welded joint is not as good as that of the base metal material because the load stress on the welded joint increases. Increased, and the system is equal to the conventional low carbon steel. When welding is carried out using a conventional coffin metal material at a local speed of more than 1.3 m / min in order to further improve the welding efficiency, irregular beads such as undercut beads and bulge beads are formed. In addition, due to the variation of the extrusion accuracy of the workpiece, the root opening of the lap joint weld often changes, if it is in the root gap of more than 1 · 9 mm (2) 1295603 high-speed welding Welding defects such as fire through and perforation will occur. Therefore, it is extremely demanded that the solder material can stably produce the bead and generate a wide bead that can bridge the root gap even at the time of high-speed soldering. A conventional solid wire for gas-shielded arc welding having a thickness of 6 mm or less is taught in the Unexamined Patent Application Publication (JP-A) No. 05-3 05476, the solid cored wire It is intended to improve the weldability and weld quality of a 6 mm thick sheet welded at a high speed of 丨.〇m/min or higher, and contains 0·02~0·10% by mass of carbon (C), 0.8. ~ t 1.2% by mass of yttrium (Si), 1.0 to 1.8% by mass of manganese (Μη), 0.020% by mass or less of phosphorus (ρ), 0.020 to o.ioo% by mass of sulfur (S), 0.005% by mass Or lower aluminum (Α1), 0.0070% by mass or less of oxygen (0), and 0.00790 mass% or less of nitrogen (Ν), the balance being iron (Fe) and unavoidable impurities, of which Μη and Si The ratio (Mn/Si) is 1.2 to 1.8. This technique aims to improve bead formation in high speed welding by adding a large amount of sulfur to adjust the surface tension of the molten metal. The use of thin steel sheets as base metal for high-speed welding of conventional solder materials often produces convex beads that do not even cause irregular solder beads. Such convex beads often result in reduced fatigue strength due to stress concentrations at the weld bead of the weld. Therefore, it is necessary to perform welding at a welding speed lower than that of the prior art. Therefore, in order to make high-strength steel sheets more widely used in these structures, it is required to provide a welded structure which can provide high fatigue strength and a welding material which maintains good welding efficiency. It is conventional to improve the fatigue strength of the joint by using a welding material capable of compressing the welded joint. Specifically, the residual stress can be lowered by lowering the martensite to -6 - (3) 1295603 change start temperature (hereinafter referred to as "Markov point (Ms point)") so that the transition can be utilized at a low temperature. . For example, jp-A No. 11-138290 proposes to control the Markov point to 25 〇 ° C to 170 ° C using a predetermined composition having a typical content of c, Cr, Ni, Si, Μ, Mo, and Nb. Welding material. However, the above-mentioned conventional technique has the following disadvantages: · The sulfur (S) added to the solid wire as described in JP-A No. 05-3 05 4 76 is a kind of amount which significantly changes the interface tension. And the fluidity of the molten metal and the elements that can achieve high-speed welding. However, sulfur promotes thermal cracking. This tendency (promoting thermal cracking) is remarkable in a weld metal using a ruthenium-filled metal material which incorporates 0.02% or more of sulfur. In particular, when welding is performed at a high speed of 1 〇 m / min or more on a varying root gap of more than 1.0 mm, hot cracking occurs more frequently. Since the sulfide becomes coarse as the amount of sulfur increases, the sulfur not only causes thermal cracking but also reduces the strength and toughness of the material. According to the Japanese Industrial Standard (JIS) G 48 04, the sulfur-containing high-speed cut-off! 1 steel material, a cut steel [| steel, by containing a large amount of sulfur (SUM 24L, containing 0.26 ~ 0.35 mass% sulfur), With improved machinability. However, in weld metals that require a certain degree of strength, toughness, and other mechanical properties, the sulfur content is typically minimized to 0.03% or less because the presence of sulfur is very detrimental to them. Therefore, the solid wire described in JP-A No. 05-3 05476 exhibits slightly higher hot crack sensitivity and lower strength and toughness than a conventional wire. The solder material described in JP-A No. 1 1 - 1 3 8290 contains a large amount of expensive alloy metal, such as Cr and N1 ' when used as a solid wire, exhibiting (4) 1295603 poor calendering properties, and Very expensive (high cost) welding material. Because the solder material has a high viscosity, the solder material cannot be applied to the high speed solder required for the soldering of the steel sheet. It is also not easy to transfer droplets, which increases the generation of splash (slag). As such, the material is not very suitable for use on actual wires. SUMMARY OF THE INVENTION In the above circumstances, an object of the present invention is to provide a solid wire for gas-shielded arc welding which can stably form a bead even in high-speed welding of 1.0 m/min or more. And in the welding of a steel sheet having a thickness of 〇. 6 to 10 mm, a welded joint having low thermal crack sensitivity and excellent fatigue strength, tensile strength and toughness can be produced. Specifically, a first aspect of the present invention provides a solid wire for gas-shielded arc welding, which comprises 0.03 to 0.15 mass% of carbon (C), 0.50 to 1.50 based on the total mass of the solid wire. Mass % of 矽 (

Si), 1.00 to 3.00% by mass of manganese (Μη), 〇·〇20 to 0.150% by mass of sulfur (s), and selected from: 0_01 to 0.20% by mass of titanium (Ti), 0·01 to 0.20% by mass At least one of 族 (Zr), 0.01 to 0.05% by mass of lanthanum (La), and 〇·〇1 to 〇·〇5 mass% of cerium (Ce); the balance is iron and inevitable An impurity in which phosphorus (P) is contained as an unavoidable impurity in an amount of 〇·〇25 mass% or less, and "A" 确定 determined according to the following Equation 1 is 100 or more; (5) 1295603 (equation 1) 20x [7/]+25x [Zrl+50x [La]^ 50x [Ce] A=~ W] : where [Mn], [Ti], [Zr], [La], [Ce], and [S The content of Μη, Ti, Zr, La, Ce, and S (% by mass) of the wire, respectively. The solid wire of the present invention has a mass of 0·〇2〇~0.150% by mass based on the total mass of the solid wire. The specific sulfur (S) contains heavy 'this causes the molten metal to flow little to the rear end and more to the width direction. The solid wire also has a manganese (Μη) content of 1·〇〇~3.00% by mass, which makes Mn S crystallization, so that the solid core welding The filament has an elevated eutectic temperature and reduced thermal crack sensitivity. In addition, the solid wire contains at least one selected from the group consisting of Ti, Zr, La, and Ce which tend to form sulfides. Leads to the formation of sulfides containing these elements, and has a high melting point, and allows sulfur to be dispersed in the matrix phase, thereby preventing the formation of sulfides at the grain boundaries. In addition, in the solid wire, the ''A is determined according to Equation 1. "値 is set to 100 or more, so that the bead can be stably formed in high-speed welding, and even in the welding of φ high-strength steel sheet, a welded joint having reduced hot crack sensitivity and excellent fatigue strength can be obtained. . The solid wire may have a manganese (Mn) content of 1.50% by mass or more. This can significantly reduce the hot crack sensitivity. The solid wire also has a sulfur (S) content of 0.040% by mass or more. This can form the bead more stably in high-speed welding, and improve the fatigue strength. The second aspect of the invention further provides a solid wire for gas-shielded arc welding, which is based on the total mass of the solid wire. : -9 - (6) 1295603 0.02 to 0.15 mass% of carbon (C), 0.50 to 1.50 mass% of bismuth (

Si), 1.00 to 3.00% by mass of manganese (Μη), 0.020 to 0.150% by mass of sulfur (S), 0.005 to 0.5% by mass of niobium (Nb), and selected from: 0.005 to 0.5% by mass of vanadium (V) , 0·〇1〇~〇·5 mass% of aluminum (A1), 0.005 to 0.5% by mass of chromium (Cr), 0.005 to 0.5% by mass of nickel (Ni), and 0.0010 to 0.0100% by mass of boron (B) At least one of the group consisting of; the balance being iron and unavoidable impurities, wherein the content of phosphorus (P) as an unavoidable impurity is 0.025 mass% or less ► because the content of sulfur and other alloying elements is Adjusted to be appropriate, so the solid wire of the present invention can stably form the bead even in high-speed welding. 'In the welding of high-strength steel sheets, it can have reduced thermal crack sensitivity and excellent fatigue strength, tensile strength. Weld joints for strength and toughness. Further, the present invention provides, in a third aspect, a method of performing gas-shielded arc welding, comprising welding a high-strength steel sheet having a thickness of 〇·6 to 10 mm using the above-described solid-core welding wire for gas-shielded arc welding. step. According to the present invention, the bead can be stably formed even in high-speed welding, and even in the welding of a high-strength steel sheet having a thickness of 0.6 to 10 mm, it is possible to obtain reduced thermal crack sensitivity and excellent fatigue strength and resistance. Tensile joints for strength and toughness. The present invention can form a wide and suitable bead having less weld slag and excellent electrodeposition coating properties. This advantage is particularly remarkable in the case of a steel sheet having a thickness of 0.6 to 10 mm which is welded at a high speed of 1.0 m / min or more. Therefore, a bead having a stable shape can be formed in high-speed welding of a steel sheet, and a welded joint having excellent fatigue strength can be obtained by -10 (7) 1295603. In addition, thermal crack sensitivity can be reduced and proper strength and toughness can be ensured. Other objects, features, and advantages of the present invention will be apparent from the description of the appended claims. [Embodiment] In order to achieve the above object, the inventors have found that the following phenomenon occurs in the welding of a steel sheet having a thickness of 〇·6 to 10 mm: formation of irregular beads, sulfur-induced Thermal cracking and reduction of fatigue strength, strength and toughness of the weld metal. The molten metal on the surface of the molten weld pool of the regular bead is sucked from the high temperature portion toward the distal end to the low temperature portion, and the suction strength is proportional to the surface tension gradient generated by the temperature difference and the length of the molten pool. In high-speed welding of 1. 〇 m/min or higher, the molten pool is elongated in the direction of the weld line, and the flow rate of the molten metal is remarkably high. This is one of the factors that produce irregular beads such as undercut beads and bulge beads. The original range of cure temperature of the weld metal is quite narrow, but even traces of sulfur can also act to broaden the cure temperature range. At this stage, as the matrix phase solidifies, the sulfur is enriched in the residual melt in the dendritic array, and due to the eutectic solidification of the residual melt, the sulfide is crystallized in the final stage of the matrix phase solidification. . The eutectic temperature of Fe-FeS is much lower than the melting point of iron. In the final stage of solidification, the isolation of such a low melting point liquid phase and compound at the grain boundary results in hot cracking. As the sulfur content increases, sulfur not only causes hot cracking, but also thickens vulcanized -11 - (8) 1295603, thereby reducing the elongation and toughness of the material. For example, steel such as sulfur-containing high-speed cutting steel (a type of cutting steel) according to Japanese Industrial Standards (JIS) G 4804 has improved machinability (SUM 24L, containing 0.26 to 0.35 mass% of sulfur) by containing a large amount of sulfur. However, in weld metals that require a certain degree of elongation, toughness, and other mechanical properties, the sulfur content is typically minimized to 0.03% or less because the presence of sulfur is highly damaging to them, as well as the welding of high strength steel. The fatigue limit of the joint may be lower than the fatigue limit of ordinary steel as the base metal. This is mainly due to the local stress concentration of the weld bead. Figure 1 is a diagram of the weld bead of a foot welded joint. In the joint shown in Fig. 1, the base metal (lower sheet) la is welded to the other base metal (upper sheet) 1b in an obliquely downward direction. The inventors have found that the stress concentration significantly changes as the shape of the portion of the base metal la that intersects the surface of the bead 2, that is, the shape of the weld bead, can be increased by making the bead diameter P larger than 0.3 mm. Fatigue strength of the joint. However, in the high-speed welding of high-strength steel sheets, since the beads tend to be convex, the weld bead diameter P becomes small, and the original fatigue strength of the high-strength steel sheet may not be sufficiently exhibited. Sulfur (S) is an element that lowers the surface tension of the molten metal and changes the surface tension gradient due to the temperature difference. Therefore, the inventors have succeeded in making the molten metal flow more toward the distal end and more toward the width direction by adjusting and defining the contents of sulfur and other elements. Thus, they have found a composition that can produce a bead that prevents the undercut and the bulge even in high speed welding. Specifically, by setting the sulfur-12-(9) 1295603 content to 0.020 to 0.150% by mass based on the total mass of the wire, it is possible to cause the molten metal to flow more toward the distal end direction and more to the width direction. Thus, the weld bead diameter P shown in Fig. 1 is 0.3 mm or more, and the fatigue strength of the welded joint in the high-speed welding of the high-strength steel sheet is improved. As mentioned above, the addition of sulfur increases the hot crack sensitivity. Sulfur-induced thermal crack sensitivity can be reduced by increasing the eutectic temperature. This can be achieved by adding a suitable amount of an element having a high affinity for sulfur to form a compound having a high melting point, thereby dispersing sulfur in the matrix phase. Specifically, MnS is crystallized by setting the manganese (Mn) content to 1.00 to 3.00% by mass based on the total mass of the wire, thereby increasing the eutectic temperature. Sulfur can be further dispersed in the matrix phase by adding at least one of a suitable amount of Ti, Zr, La and Ce because these elements act to form sulfides, thereby forming sulfur-containing high melting point compounds. This can substantially prevent the formation of sulfides at the grain boundaries. Further, by adjusting the content of the alloy component, the "A" 値 determined according to the following Equation 2 is 100 or more, and the stable shape of the solder ball can be obtained even in the welding of the high-strength steel sheet, and the thermal crack sensitivity is obtained. Reduced, and welded joints with excellent fatigue strength: Equation 2 ΓΜ?1+20χ [7/1+25 X fZr]+50X [Ζα]+ 50x [Ce] Α= ~Ύ) where [Μη], [ Ti], [Zr], [La], [Ce], and [S] respectively represent the contents of Μη, Ti, Zr, La, Ce, and S (% by mass) of the wire. In view of these findings, the inventors obtained A solid-core welding wire for gas-shielded arc welding according to a first embodiment of the present invention. This solid-core welding wire, 13-(10) 1295603, provides a gas-shielded arc of a high-strength steel sheet having a thickness of 0.6 to 10 mm. In the high-speed welding of welding, it is also possible to produce a welded bead having a stable shape and to form a welded joint having low hot crack sensitivity and excellent fatigue strength. As described above, as the sulfur content increases, the hot crack sensitivity increases. First, by preventing the formation of a low melting point compound F es which mainly produces hot cracks, Low thermal crack sensitivity. According to this technique, by adding an element having affinity for sulfur to raise the eutectic temperature, the sulfide formed is dispersed in the matrix phase, and the formation of the low melting point compound FeS is prevented. The solution is to reduce the thermal cracking sensitivity by adding elements with high hardenability to uniformly disperse the F eS, because the size of the crystal grains formed by the curing is lowered, thereby the grain boundary Based on these, the inventors have found that it is necessary to find the effective content of these elements to reduce the thermal cracking sensitivity. In view of these findings, the inventors have obtained gas-shielded arc welding as a second specific example of the present invention. Solid-core welding wire used. This solid-core welding wire can produce stable-stabilized welding beads even in high-speed welding, and can produce low thermal cracking sensitivity and excellent fatigue resistance in welding of high-strength t steel sheets. , welded joints with tensile strength and toughness. (1) The sulfur content is 0.020~0.150% by mass, which enables the molten metal to flow in the distal direction. (2) The content of Μη is set to 1.00 to 3.00% by mass to crystallize Mn S to increase the eutectic temperature, thereby reducing crack sensitivity. (3) By mixing at least the following One is to increase the hardenability and make the crystal grains finer: 〇·〇〇5~0.50% by mass of 铌(Nb), 0.005~0.5 -14- (11) (11)

1295603% by mass of vanadium (V), 0.010 to 0.5% by mass of aluminum (Al) 〇·5·5% by mass of chromium (Cr), 0.005 to 0.5% by mass of nickel, and 0.001 to 0.010% by mass of boron (B) . A suitable amount of the compound is mixed to make the structure formed by the curing finer, thereby increasing the grain boundary. The liquid phase segregation of FeS is prevented and dispersed, thus reducing crack sensitivity. The formation of FeS on the grain boundaries and in the dendrite array results in cracking. These elements are also used to reduce the hot crack sensitivity, which makes the grains finer, thereby improving the toughness and reducing the stress concentration in the liquid phase solidification of FeS caused by expansion during welding. (4) The other elements listed in (3) prevent the formation of welds, which promote the formation of suitable beads with less weld slag. Therefore, combining these elements can reduce the hot crack sensitivity and ensure proper strength without compromising the advantages of these elements. The reason why the composition of the wire of the present invention is specified will be explained below. First, the composition of a solid wire for gas protection as a first specific example of the present invention will be described. Carbon content: 0.03 to 0.15 mass% Carbon (C) is an element required to ensure the strength of the weld metal and to effectively deoxidize. However, if the carbon content is 0.03 mass% based on the total mass of the wire, the weld metal has insufficient strength. As a result, the carbon content exceeds 0.15 mass%, and the weld metal has a reduced increase in thermal crack sensitivity. Therefore, the basis weight of the total mass of the welding wire is set to 〇.〇3 to 0.15 mass%.矽 content: 0.50~1.50% by mass 0.005 Ni): Some of the surface 'heat': the meeting will be this: and the 〇 〇 丨 丨 丨 丨 丨 丨 弧 弧 弧 弧 弧 弧 弧 弧 弧 弧 弧 弧 弧 弧 弧 弧 弧 弧 弧 弧 弧-15- (12) 1295603 矽(Si) is an element that promotes deoxidation and improves the strength of steel to improve the consistency of the bead. However, based on the amount of welding, if the niobium content is less than 0.50% by mass, there are no advantages. On the contrary, if the niobium content exceeds 1.50 mass%, the ductility and the toughness of the weld metal are impaired. Therefore, based on the amount of weld, the content of niobium is set at 0.50 to 1.50. The content of manganese is 1.00~3.00% by mass. Manganese (Μη) is effective as a niobium to promote the mechanical properties of deoxidation and modification. Elements. It also acts to cause the MnS to have a high eutectic temperature, thereby reducing the hot crack sensitivity. However, on the basis of mass, if the manganese content is less than 1.00% by mass, the heat is increased. Conversely, if the manganese content of the weld metal is excessively more than 3 % by mass, the toughness is reduced. Therefore, the manganese content is set to 1.00 to 3.00% by mass based on the total mass of the wire. Preferably, it is 1 - 50% by mass or more. Sulfur content: 0.020 to 0.150% by mass Sulfur (S) acts to lower the surface tension of the molten metal. When a suitable amount is used, the effect is to improve the consistency between the bead and the base at the weld bead and to improve the fatigue strength of the welded joint. However, based on the total mass, if the sulfur content is less than 0.020% by mass, these advantages are obtained. Conversely, if the sulfur content exceeds 0.150, thermal cracking will occur even if the content of other elements is adjusted. Based on the total mass of the filament, the sulfur content is set to 0.020 to 0.150, preferably set at 0.040% by mass or more, more preferably set at 0, and the total mass of the filament is obtained to obtain the total mass% of the filament of the droplet. . The total crack sensitivity of the incoming gold and the wire is set based on the amount of weld % when the amount of wire added to the base metal is not sufficient. .0 6 0 Quality -16- (13) 1295603 % or higher. , from 0.01 to 0.20% by mass of titanium (Ti), 0.01 to 0.20% by mass of bismuth (Zr), 0.01 to 0.05% by mass of lanthanum (La), and 0.01 to 〇. 0 5 % by mass of ruthenium ( C e ) at least one of the group consisting of titanium (Ti), lanthanum (Z 〇, lanthanum (La), and cerium (Ce)) are elements that readily bind sulfur and thus form high fused sulfides. At least one of the sulfur may be dispersed in the matrix phase. However, even when two or more of these elements are added to the solid wire, based on the total mass of the wire, if the content of each element Less than 〇·〇1% by mass, these advantages are not obtained. Conversely, if the titanium content or the pin content exceeds 0.20% by mass, the droplets become coarse, the droplet transfer is disturbed, and the weld slag is excessively formed, thereby impairing the weldability. Therefore, based on the total mass of the wire, if added, the content of Ti and/or Zr is set to 〇.〇1 to 〇.20% by mass. If the content of cerium or lanthanum exceeds 0.05% by mass, the sulphide becomes coarse. , steel production is reduced, which increases costs. Therefore, if added, Based on the total mass of the wire, the content of La and/or C e is set at 〇. 〇1 to 0.05% by mass. Phosphorus content: 0.025% by mass or less Phosphorus (P) is inevitable for contaminated steel Impurity; it is an element that increases the sensitivity of hot cracking, and preferably lowers its content. However, based on the total mass of the wire, the phosphorus content is negligible at 0.025 mass% or less. Therefore, the total mass of the wire is Based on the control, the p content is controlled to 0.025 mass% or less. "A": 100 or more -17- (14) 1295603 According to the present invention, the "A" It is 100 or more. In Equation 3, [Mn], [Ti], [Zr], [La], [Ce], and [S] represent the Μη, Ti, Zr, La, Ce, and S of the wire, respectively. Content (% by mass). If "A" 値 is less than 100, the thermal crack sensitivity increases. Conversely, based on the total mass of the wire, by adjusting the contents of Μη, Ti, Zr, La, Ce, and S, "A "値 is 100 or more, crystallizes MnS' to increase the eutectic temperature, and prevents low melt in the final stage of curing. And the compound is isolated at the grain boundary. In addition, a high-melting sulfide containing at least one of Ti, Zr, La, and Ce can be formed. Therefore, the thermal crack sensitivity can be remarkably reduced. The following equation is defined according to the results of the crack resistance test. The coefficients of 3, which may be significantly affected by the tendency of each element to form a sulfide. Equation 3 λ _ [M;?]+20x [7z]-h25x [Zr]-f 50x [La]-f 50x [Ce In addition to phosphorus (P), the unavoidable impurities contained in the solid wire of the present invention include, for example, Cu, Al, Ni, Cr, Mo, and B. The reason why the composition of the welding wire for gas-shielded arc welding as the second specific example of the present invention is defined will be explained below. Carbon content: 0.02 to 0.15 mass% Carbon (C) is an element required to secure the strength of the weld metal, and is effective as a deoxidizing element. If the carbon content is less than 0.02% by mass, the strength of the welded metal is insufficient. On the contrary, if the carbon content exceeds 0.15% by mass, the toughness of the weld metal is lowered and the hot crack sensitivity is increased. The addition of excessive amounts of carbon impairs the releasability of the droplets and produces a large amount of sputtering, which results in weldability and a large amount of weld slag which are damaged by -18-(15) 1295603. Therefore, the carbon content is set to 0.02 to 0.15 mass% here. Sand content: 0.50 to 1.50% by mass 矽(Si) is also an element which promotes deoxidation, improves steel strength and improves weld bead consistency. If the niobium content is less than 0.50% by mass, these advantages are insufficient, the bead has poor consistency, and the shape of the weld bead is damaged, often resulting in stress concentration and fatigue strength reduction. The cerium content is preferably 0.60% or more. Conversely, if the niobium content exceeds 1.50 mass%, the molten pool has an excessively high viscosity (flow resistance), which often results in a humping bead in high speed welding. Excess sand damages droplets for releasability and produces a large amount of sputtering. This results in poor weldability and a large amount of weld slag. The niobium content is more preferably 1.20% by mass or less. Manganese content: 1.00 to 3.00% by mass Manganese (Mn) is an element such as cerium (Si) which is used as a deoxidizing element and acts to improve the mechanical properties of the weld metal. Due to the crystallization of MnS, it acts to increase the eutectic temperature, thereby reducing the thermal crack sensitivity. If the manganese content is less than 〇〇% by mass, the hot crack sensitivity increases and the weld metal has insufficient strength. Conversely, if the manganese content exceeds 3.00% by mass, the molten pool has an excessively high viscosity (flow resistance), which often causes bulging beads and a large amount of weld slag in high-speed welding. Therefore, the manganese content is set to 1.00 to 3.00% by mass. More preferably in the range of 1.00 to 2.00% by mass 〇 Phosphorus content: 0.025% by mass or less Phosphorus (P) is an element which increases the sensitivity to thermal cracking. Since the high-melting phosphorus compound cannot be formed even by the addition of the -19-(16) 1295603 alloying element, it is preferred to minimize the phosphorus content. However, the phosphorus content of 〇·〇25% by mass is negligible. Sulfur content ··0.020~0.150% by mass Sulfur (S) acts to lower the surface tension of the molten metal. When a suitable amount is added, it acts to improve the consistency between the bead and the base metal at the weld bead. Improve the fatigue strength of welded joints. However, without the addition of the following specific elements, a large amount of sulfur thickens the sulfide formed in the grains and at the grain boundaries, thereby reducing the strength and toughness of the weld metal. The above advantages can be obtained by adding sulfur in an amount of 0.020% by mass or more. On the contrary, if the sulfur content exceeds 0.150% by mass, even if the content of other elements is adjusted, thermal cracking will occur, and the strength and toughness are remarkably lowered. Therefore, the sulfur content is set to be 0.020 to 0.150% by mass. More preferably, it is set at 0.040 to 0.150% by mass, and further preferably set at 〇.050 to 0.150% by mass. Antimony content: 0.005 to 0.50% by mass Niobium (Nb) has an affinity for sulfur and is liable to form a sulfide. A suitable amount of ruthenium acts to prevent the formation of F e S which causes thermal cracking. In addition, since niobium is an element which improves hardenability to make crystal grains finer, it acts to lower thermal crack sensitivity and ensure proper strength and toughness. However, if the _N content is less than 0.05% by mass, these advantages are not obtained, and the hot crack sensitivity is increased. The silver content is more preferably 0.02% by mass or more. Conversely, if the silver content exceeds 50% by mass, these advantages are no longer increased, and segregation occurs at the grain boundaries and in the dendrite array upon curing, which in turn increases the thermal cracking sensitivity. Excessive enthalpy increases the production cost of the solid wire, increases the viscosity (flow resistance) of the -20-(17) 1295603 molten pool, produces bulge beads, and increases sputtering in high speed welding. "A group consisting of: 0.005 to 0.5% by mass of vanadium (V), 0.010 to 0.5% by mass of aluminum (A1), 0.005 to 0.5% by mass of chromium (Cr), and 0.005 to 0.5% by mass of nickel (Ni) At least one of them" vanadium (V), aluminum (A1), chromium (Cr), and nickel (Ni) increase the hardenability and effect to make the weld metal formed by welding finer, ensuring proper strength and toughness. An element that reduces the sensitivity of hot cracks. In order to exhibit these advantages, the content of each of V, Cr and Ni must be 0.005 mass% or more, and the A1 content must be 0.010 mass% or more. More preferably, the content of each of V, Cr and Ni must be 〇.〇2% by mass or more, and the A1 content must be 0.03% by mass or more. Conversely, a content of more than 0.5% by mass of each of these elements increases the production cost of the solid wire, increases the viscosity (flow resistance) of the molten pool, and produces a bulge bead and an increase in the amount of sputtering in high-speed welding. Boron content: 〇·〇〇1 to 0.010% by mass Boron (B) is an element which increases the hardenability and acts to make the weld metal formed by welding finer, ensures proper strength and toughness, and reduces hot crack sensitivity. In order to demonstrate these advantages, the boron content must be 〇 〇 〇 1% by mass. On the contrary, the upper limit of the boron content is set to 〇 〇 1 〇 by mass or less because the thermal crack sensitivity is increased if the boron content exceeds 0.010% by mass. Therefore, the boron content is set to 0.001 to 0.010% by mass. Welding method of the present invention - 21 - (18) 1295603 The gas-shielding method and welding conditions of a steel sheet having a solid core thickness of 0.6 to 10 mm according to the first and second specific examples of the present invention are as follows. The gas here may be any welding method such as CO2 welding (MAG) welding or metal inert gas (MIG) welding (TIG) welding. For example, output power or current and welding speed MAG pulse welding, MIG pulse welding or TIG pulse can be set depending on the processor type and shape. Depending on the portion of the weld, the target welded joint can be, for example, a butt joint or a lap joint. The present invention can be applied to any joint. In the welding of thin steel plates, it is preferred to use high-speed weldability and arc stability and to reduce smoke generation, but not limited to 3 5 0 A~600 A peak current, 3 current, one The peak (from the beginning of the pulse rise, the end of the constant drop) is 0.8 to 5.0 milliseconds. Welding is carried out in the present invention. Steel sheet with a thickness of 0.6 to 10 mm If the thickness of the steel sheet is less than 〇6 mm, it is difficult to carry out the rule because the sheet penetrates and burns. Conversely, if the thickness exceeds 1 〇 mm, it is used by the wire for W arc welding. It is more effective to weld the welding conditions such as the preferred V-protected arc welding square, the metal active gas splicing and the tungsten inert gas enthalpy, and the thick melon of the workpiece. Any suitable joint (pulse welding machine) The pulse condition can be 0-8~1008 base-set peak to pulse under these conditions can be the arc force to make the thin steel reverse polarity arc welding to thermal expansion and heat recovery -22- (19) 1295603 contraction The increase, so that excessively large stress is applied to the weld metal and the molten weld pool is cooled more rapidly, so the risk of hot cracking increases. In addition, the molten weld pool formed in the welding using the welding wire of the present invention has a low viscosity ( Flow resistance), when T-shaped horizontal fillet welding is performed in a single corner of a large solder fillet length, the upper solder fillet is drooped. Therefore, the thickness of the welded steel sheet is preferably 0.6 to 10 mm. In terms of the strength of the welded steel sheet The present invention can be applied to a wide range of thin steel sheets, from regular low carbon steel sheets to high strength thin steel sheets; the upper limit of the strength of the steel sheets is not particularly limited. Test Example 1 Referring to the following examples, The advantages of the present invention are exemplified in more detail in the comparative examples outside the scope of the present invention. First, the test example 1 relating to the solid wire of the first specific example of the present invention will be described. In Test Example 1, the composition having the following Table 1 was used. Solid-core welding wire for gas-shielded arc welding. Evaluating the formation of weld beads for high-speed welding, mechanical properties of weld metal, weld bead diameter P, hot crack sensitivity and weldability. The composition of the solid wire in Table 1. The balance is iron and inevitable impurities. -23· (20)1295603

Table 1 No. Composition (Quality® ί) AC Si Μη S Ti Zr La Ce P Example 1 0.035 0.72 2.12 0.065 0.07 0.03 0.03 0.03 0.010 111.8 2 0.138 0.84 2.32 0.052 0.06 0.12 - - 0.015 125.4 3 0.061 0.53 1.72 0.082 0.10 0.15 - 0.03 0.014 109.4 4 0.085 1.44 2.08 0.071 0.07 0.18 - - 0.005 112.4 5 0.088 1.05 1.09 0.048 - 0.16 嶋- 0.009 106.0 6 0.075 0.88 1.55 0.062 0.07 0.14 - - 0.003 104.0 7 0.045 1.21 2.88 0.117 0.11 0.17 0.01 0.05 0.006 105.4 8 0.067 0.89 1.66 0.022 - 0.05 - - 0.021 132.3 9 0.051 0.78 2.51 0.139 0.15 0.19 0.04 0.04 0.018 102.6 10 0.071 0.95 1.92 0.064 0.01 0.16 0.01 - 0.005 103.4 11 0.094 1.14 2.24 0.094 0.17 0.18 - - 0.007 107.9 12 0.081 1.08 2.42 0.042 0.09 - - - 0.012 100.5 13 0.112 1.31 1.91 0.036 0.08 0.01 - - 0.019 104.4 14 0.050 0.69 2.65 0.102 0.05 0.18 0.03 0.03 0.12 109.3 15 0.126 1.08 1.95 0.055 0.10 0.05 0.01 雠0.013 103.6 16 0.086 0.81 2.75 0.121 0.16 0.19 0.04 - 0.008 105.0 17 0.072 0.81 2.13 0.037 - - 0.04 - 0.005 111.6 18 0.048 0.94 1.77 0.062 0.09 0.16 - 0.01 0.022 130.2 19 0.077 1.25 2.58 0.084 0.13 0.06 - 0.05 0.016 109.3 20 0.086 0.69 1.85 0.035 - - - 0.04 0.007 110.0 Comparative Example 21 0.024 0.78 1.88 0.039 0.05 0.05 0.01 0.01 0.0113 131.5 22 0.155 0.91 1.94 0.054 0.02 0.05 0.01 0.01 0.012 85.0 23 0.054 0.45 1.77 0.042 - 0.12 - 0.01 0.007 125.5 24 0.084 1.54 2.24 0.061 0.03 0.07 0.01 0.03 0.014 108.0 25 0.069 1.04 0.96 0.026 0.07 - - - 0.006 90.8 26 0.078 1.23 3.03 0.119 0.17 0.18 0.01 0.02 0.009 104.5 27 0.121 1.11 2.56 0.054 0.05 0.12 0.01 - 0.027 130.7 28 0.080 1.05 1.32 0.017 0.02 0.02 - - 0.019 130.6 29 0.075 0.67 2.79 0.153 0.17 0.18 0.03 0.03 0.005 89.5 30 0.085 0.55 1.89 0.069 0.006 0.17 - - 0.003 90.7 31 0.047 0.81 1.63 0.073 0.22 0.04 - 0.02 0.007 110.0 32 0.062 1.23 2.34 0.093 0.12 0.005 0.01 0.01 0.015 63.1 33 0.077 1.39 2.47 0.122 0.07 0.22 0.04 0.03 0.023 105.5 34 0.067 0.71 2.05 0.066 0.09 0.03 0.005 0.01 0.018 81.1 35 0.081 1.09 2.66 0.103 0.11 0.05 0.01 0.005 0.007 66.6 36 0.067 0.95 1.69 0.062 - - - - - 0.004 27.3 37 0.082 0.88 1.08 0.023 - - - - 0.007 47.0 38 0.052 1.01 1.73 0.094 - - - - 0.005 18.4 39 0.081 1.12 1.64 0.010 - - - - 0.008 164.0 40 0.075 0.89 1.41 0.005 - - - - 0.005 282.0 - 24-(21)1295603 Table 2 Composition (% by mass) C Si Μη Ρ S Balance 0.04 0.02 1.35 0.013 0.003 Fe and unavoidable impurities Next, the method for evaluating performance will be described. The mechanical properties of the weld metal are determined according to the tensile test method for butt welded joints specified in Japanese Industrial Standards (JIS) Z 3121 and the impact test method for welded joints specified in JIS Z 3 2 2 8 Sex. In these tests, it has a tensile strength of 560 N/mm2 or higher and an absorption energy of 1 〇〇 or higher in a Charpy impact test at a test temperature of _2 °C. The sample is rated as "good" and has a tensile strength of less than 560 N/mm2 or a sample having an absorbed energy of less than 100 J in the Charpy impact test at a test temperature of -20 °C. "Failed". Bead formation of high-speed welding is as follows. The bead formation of high-speed welding is evaluated as follows. The lap joint sample having the composition of Table 2 and a high-strength steel sheet of 2.3 mm thickness is opened at 1. 〇mm. MAG pulse welding was performed using a welding current of 200 to 300 A and a welding speed of 1.3 to 1.5 m/min using a gas mixture of 80% by volume of Ar and 20% by volume of CO 2 as the shielding gas. No undercut was shown. , bulging bead, burn through and penetration, and the sample that can overlap the gap in all welds is evaluated as "good" with, for example, undercut, bulge beads, -25- (22) 1295603 burn through or penetrate Samples with defects were evaluated as "failed". Solderability The weldability was evaluated by observing the arc stability and the rule of droplet transfer using a high speed camera and measuring the number of discrete sputtering. In this procedure, a gas mixture of 80% by volume of Ar and 20% by volume of CO 2 was used as a shielding gas, and a pulseless MAG welding was performed at a welding current of 200 to 30 〇 A. A sample with a stable arc, a highly regular droplet transfer, and a small amount of sputtering is evaluated as "good", and at least one of the samples with poor arc stability, droplet transfer regularity, and sputter count is evaluated. The quantity is “failed.” The hot crack sensitivity of the weld metal is evaluated by the results of the fish bone crack test and the crater crack test to evaluate the hot crack sensitivity of the weld metal. First, the method of performing the fish bone fracture test is described. Fig. 2A is a cross-sectional view showing the position of the sampled test piece, and Fig. 2B is a plan view showing how to prepare a test piece for the fishbone crack resistance test. Referring to Fig. 2A, the two layers have a thickness of 20 mm and contain SM490A low carbon steel. As the high-strength steel sheet of the base metal 11, a gasket metal 13 containing SM490A low carbon steel was used, butt welding was performed at an oblique angle of 45°. The obtained welded joint was mechanically cut into a thickness of 5 mm to obtain The test piece 14 of the fish bone fracture test has a width of 175 mm, a length of 250 mm, and a thickness of 5 mm. As shown in Fig. 2B, two of the long sides of the test piece 14 The end of the rule - 26- (23) 1295603 The slits are formed into slits 15. The slits 15 have a varying length, increasing from the short side to the other side, so that the thermal deformation (thermal stress) applied to the molten metal continues with the length of the slit. Specifically, the slit 15 has a short side of a small length, the thermal deformation is large, and the other short side of the slit 15 having a large length is small in thermal deformation. The test piece 14 is placed at a width of 750 mm. TIG welding was carried out on a copper plate 16 having a length of 500 mm and a thickness of 25 mm, under the conditions of Table 3 below, in which the test plate was moved. In this procedure, by applying a plate end having a shorter length in the slit The static arc is about 5 seconds, thereby sufficiently melting the end of the plate and thermally deforming the end of the plate, and causing a solidification crack (hot crack) generated by shrinkage/solidification deformation during cooling at the end of the plate. The end of the crack is welded to the slit at the other end of the slit having a longer length. The heat crack resistance is evaluated based on how far the crack is extended from the end of the sheet of the test piece 14 (how long). Corresponding to thermal deformation, ie thermal crack sensitivity Specifically, a color inspection is performed after soldering, the length of the crack formed in the bead 12 is measured, and the ratio of the crack length to the length of the test piece (crack ratio) is determined. The sample having a crack ratio of 5% or less is evaluated as "Good", samples with a crack ratio greater than 5% were rated as "failed". Table 3 Welding method TIG on-board bead-on-plate shielding gas 100% Ar, 20 l / min welding current 200 A welding speed 3 0 cm / min -27- (24) 1295603 using SM490A low carbon In the crater crack test of metal, a gas mixture of 80 vol% Ar and 20 vol% C02 was used as a shielding gas at a depth of 5 mm and a slope of 90 at a welding current of 200 to 300 Å. On the beveled V-shaped groove, three welding beads of about 7 mm in length were intermittently formed under the same conditions by pulseless MAG welding. The total length of cracks on the surface of each weld was measured. The ratio of the crack length to the length or diameter of the weld is measured, and the average enthalpy of the ratio of the three welds is used as an index. Samples with an average crack ratio of 15 % or less were rated as "good", and samples with an average crack ratio of more than 15 % were rated as "failed". Weld bead diameter p For convenience, the weld bead diameter was determined. p is used as an index of the fatigue strength of the welded joint, because as the weld edge diameter p increases, the stress concentration is slowed and the fatigue strength is improved. Specifically, a gas mixture of 80% by volume Ar and 20% by volume C〇2 is used as Protective gas, at an average welding current of 200 to 300 A and a welding speed of 1.3 to 1.5 m/min, according to the automatic foot welding 'make the overlap of the high-strength steel sheet having the composition of Table 2 and a thickness of 2 · 9 mm Perform MAG pulse welding. Then measure the weld bead diameter P as shown in Figure 1. Samples with a weld bead diameter of 0.3 mm or greater are rated as "good", and samples with a weld bead diameter of less than 0 · 3 mm are rated as "Unqualified." The results of the above evaluations are shown in Table 4 below. -28- (25) 1295603 Table 4 Example Comparative Example No. Mechanical Properties of Welded Metals High-Speed Welding Beads Forming Weldability Process Fishbone Crack Test Arc Pit Crack Test Weld Edge Defects (Round P Crack Ratio (%) Evaluation Crack ratio (%) Evaluation of weld bead diameter (mm) Evaluation 1 Good Good Good 0 Good 0 Good 0.58 Good 2 Good Good Good 0 Good 0 Good 0.51 Good 3 Good Good Good 2.3 Good 0 Good 0.74 Good 4 Good Good Good 0 Good 0 Good 0.70 Good 5 Good Good Good 0 Good 3.5 Good 0.43 Good 6 Good Good Good 3.1 Good 4.8 Good 0.55 Good 7 Good Good Good 2.7 Good 2.1 Good 0.84 Good 8 Good Good Good 0 Good 0 Good 0.36 Good 9 Good Good Good 4.3 Good 7.1 Good 0.90 Good 10 Good Good Good 3.5 Good 7.4 Good 0.53 Good 11 Good Good Good 2.8 Good 0 Good 0.76 Good 12 Good Good Good 3.8 Good 6.4 Good 0.39 Good 13 Good Good Good 0 Good 5.1 Good 0.41 Good 14 Good Good good 0 Good 0 Good 0.79 Good 15 Good Good Good 3.2 Good 6.5 Good 0.53 Good 16 Good Good Good 2.9 Good 0 Good 0.79 Good 17 Good Good Good 0 Good 0 Good 0.40 Good 18 Good Good Good 0 Good 0 Good 0.60 Good 19 Good Good good 0 Good 2.3 Good 0.77 Good 20 Good Good Good 0 Good 0 Good 0.38 Good 21 Unsatisfactory Good Good 0 Good 0 Good 0.37 Good 22 Unsatisfactory Good 8.8 Unsatisfactory 8.3 Good 0.53 Good 23 Unqualified Good 0 Good 0 Good 0.23 Failed 24 Failed Good Failed 0 Good 5.1 Good 0.56 Good 25 Failed Good Good 4.5 Good 16.3 Unsatisfactory 0.33 Good 26 Failed Good Good 3.9 Good 6.1 Good 0.82 Good 27 Good Good 7.1 Unsatisfactory 8.4 Good 0.50 Good 28 Good failure Good 0 Good 0 Good 0.24 Unsatisfactory 29 Good Good 8.9 Unsatisfactory 13.4 Good 0.81 Good 30 Good Good 6.4 Unqualified 15.5 Unqualified 0.70 Good 31 Good Good Fail 0 Good 4.1 Good 0.78 Good 32 Good Good Good 11.4 Unsatisfactory 25.8 Unsatisfactory 0.81 Good 33 Good Good Failed 3.2 Good 0 Good 0.89 Good 34 Good Good Good 7.0 Unsatisfactory 12.3 Good 0.72 Good 35 Good Good Good 13.4 Unsatisfactory 28.4 Unsatisfactory 0.83 Good 36 Good Good 21.3 Unsatisfactory 43.2 Unsatisfactory 0.58 Good 37 Good Good Good 6.1 Unsatisfied 15.3 Unsatisfactory 0.33 Good 38 Good Good Good 19.3 Unsatisfactory 41.2 Unsatisfactory 0.74 Good 39 Good Good Failure 0 good 0 good 0.21 unsatisfactory 40 good failure good 0 good 0 good 0.18 fail 29- (26) 1295603 Table 4 shows that the solid wire according to the embodiments 1 to 2 of the present invention is excellent in some evaluations result. Conversely, the solid wire of Comparative Examples 21 to 40 outside the scope of the present invention is at least one of high-speed welding bead formation, weld metal mechanical properties, weld bead diameter p, hot crack sensitivity, and workability. The person is bad. Specifically, since the solid wire of Comparative Example 21 has a carbon content smaller than the range defined by the present invention, it exhibits insufficient weld metal strength. Since the carbon content of the solid wire of Comparative Example 22 exceeded the range defined by the present invention, it exhibited an insufficient toughness of the weld metal. In addition, since the solid wire has an "A" 小于 smaller than the range defined by the present invention, it has an increased hot grain sensitivity. Since the solid wire of Comparative Example 23 has a bismuth content smaller than that defined by the present invention, the weld metal exhibits insufficient strength. The cored wire also exhibits poor bead formation and a weld bead diameter P in high speed welding. In contrast, the solid wire of Comparative Example 24 had a niobium content exceeding the range defined by the invention, thereby exhibiting insufficient weld gold B toughness, coarse droplets, and increased sputtering. The solid core welding of Comparative Example 25 had a manganese content smaller than the range defined by the present invention and "A" 小于 which was smaller than the range bound by the present invention, thereby exhibiting insufficient weld metal strength and added hot crack sensitivity. In contrast, the solid wire of Comparative Example 26 had a manganese content exceeding the range defined by the present invention, thereby exhibiting insufficient toughness of the joined metal. The solid wire of Comparative Example 2 7 had a phosphorus content exceeding the range defined by the present invention, thereby exhibiting an increased hot crack sensitivity. Although the welding of the comparative example has a lower thermal cracking sensitivity than the existing solid-wired wire of -30-28 (27) 1295603, which is less than the prior art, it has less than the present invention. The range of sulfur content is defined to exhibit poor bead formation and small weld bead diameter p in high speed welding. On the contrary, even if the content of other elements in the solid wire of Comparative Example 29 is within the scope of the present invention, it has a sulfur content exceeding the range defined by the present invention and an "A" 小于 smaller than the range defined by the present invention, Thereby exhibiting high thermal crack sensitivity. Each of the solid wires of Comparative Examples 30, 32, 34, and 35 had an "A" 小于 less than the range defined by the present invention, thereby exhibiting high thermal crack sensitivity. b The solid wire of Comparative Example 3 1 exceeded The titanium content of the range defined by the present invention, thereby exhibiting coarse droplets, increased sputtering, and increased slag. Similarly, the solid wire of Comparative Example 33 has a zirconium content exceeding the range defined by the present invention, thereby Shows coarse droplets, increased sputtering, and increased weld slag. Comparative Example 3 6, 3, and 3 8 solid wire does not contain any of Ti, Zr, La, and Ce, each having less than The "A" of the range defined by the present invention exhibits high thermal crack sensitivity. The solid wire of Comparative Examples 3 and 40 does not contain Ti, Zr, La and Ce, and has a range exceeding the range defined by the present invention B. The sulfur content, thereby exhibiting high thermal cracking sensitivity. Test Example 2 Next, Test Example 2 relating to the second specific example of the present invention will be exemplified. In this test example, a wire welded steel sheet having the composition shown in Table 5 below was used. Measure the formation of high-speed welded beads, The mechanical properties of the weld metal, the weld bead diameter P, the coatability, the hot crack sensitivity and the weldability. The balance of the solid wire of Table 5 is iron and unavoidable impurities. -31 · (28)1295603 Table 5

No. Chemical composition of the wire (% by mass) C Si Μ Ρ Ρ S Cr Ni Nb V A1 B Example 1 0.022 0.93 1.22 0.006 0.057 0.062 - - - - - 2 0.138 0.84 2.32 0.015 0.052 - - - - - 0.0089 3 0.021 0.53 1.02 0.014 0.082 - - - 0.251 - - 4 0.085 1.44 2.08 0.005 0.071 - - - - 0.155 - 5 0.035 1.05 1.09 0.009 0.048 0.155 - - - - - 6 0.035 0.88 1.55 0.003 0.062 - - 0.032 - - - 7 0.025 1.21 2.88 0.006 0.117 - 0.153 - - - - 8 0.067 0.89 1.32 0.021 0.022 - - - 0.005 - - 9 0.051 0.78 1.33 0.018 0.139 - - - - 0.065 - 10 0.071 0.95 1.25 0.005 0.064 - 0.030 - - - - 11 0.094 1.14 2.24 0.007 0.055 - - 0.470 - - - 12 0.081 1.08 2.42 0.012 0.068 - - - - - 0.0030 13 0.112 1.31 1.91 0.019 0.036 0.005 - - 0.151 - - 14 0.031 0.69 2.65 0.012 0.102 - 0.006 0.160 - - - 15 0.126 1.08 1.58 0.013 0.055 0.035 - - - 0.010 - 16 0.086 0.81 1.68 0.008 0.121 - 0.230 - 0.030 - 0.0098 17 0.086 0.81 1.32 0.005 0.037 0.050 - - - 0.033 0.0070 18 0.025 0.94 1.55 0.022 0.062 0.250 - 0.240 - - - 19 0.030 1.25 2.00 0.016 0 .084 - 0.260 0.035 - 0.260 - 20 0.053 0.65 1.10 0.015 0.020 0.460 - - 0.489 - - 21 0.022 1.49 2.02 0.015 0.034 - - 0.060 - - 0.0010 22 0.024 1.02 1.43 0.014 0.045 - 0.052 - 0.055 - - 23 0.052 1.45 1.53 0.024 0.065 - - 0.006 - 0.478 - 24 0.088 1.20 2.00 0.010 0.055 0.032 0.488 - - - - 25 0.086 0.69 1.85 0.007 0.035 0.250 0.036 0.033 0.032 0.033 0.0012 Comparative Example 26 0.031 0.73 2.53 0.010 0.052 - - - - - - 27 0.048 1.02 1.52 0.010 0.101 - - - - - - 28 0.031 1.23 1.02 0.010 0.130 - - - - - - 29 0.020 0.85 1.35 0.019 0.040 - - - - 0.003 - 30 0.080 1.20 1.60 0.013 0.070 - 瞧- - 0.007 - 31 0.160 1.00 1.25 0.012 0.030 - - 0.320 0.200 - 0.0040 32 0.052 1.23 3.50 0.011 0.120 - - 0.020 - 0.053 - 33 0.083 2.00 1.53 0.010 0.085 - 0.410 - 0.085 - - 34 0.025 0.98 1.02 0.032 0.120 0.420 0.430 0.020 A - 0.0012 35 0.050 1.23 1.52 0.010 0.019 0.230 - - 0.350 - - 36 0.032 1.01 1.82 0.020 0.005 - - - - 0.023 0.0010 37 0.053 1.20 1.53 0.010 0.065 0.650 - - - - - 38 0.023 2.32 1.23 0.01 2 0.120 0.850 0.620 - 0.007 - - 39 0.102 1.00 1.56 0.010 0.070 0.050 - - - 0.850 - 40 0.050 1.03 1.65 0.011 0.052 1.020 0.020 0.023 0.630 - 0.0005 41 0.102 0.82 2.11 0.015 0.082 - - 0.820 - - 0.0050 42 0.056 0.98 1.58 0.015 0.052 0.301 - - - - 0.0200 43 0.085 1.20 2.01 0.010 0.065 - 0.230 0.420 0.602 - 0.0120 44 0.068 1.80 0.89 0.015 0.065 0.050 - - 0.006 0.010 - 45 0.030 1.32 1.50 0.010 0.160 - - - - - - 46 0.010 1.12 0.93 0.012 0.055 - 0.030 0.025 0.012 0.320 - 47 0.190 0.42 2.62 0.010 0.110 0.030 - - - - 0.0030 48 0.065 0.45 2.02 0.030 0.032 0.120 - 0.045 - 0.325 - 49 0.201 1.20 3.10 0.022 0.042 - 0.420 0.062 0.420 0.012 - 50 0.014 1.32 1.11 0.032 0.098 - 0.330 - 0.250 - 0.0021 -32- (29) 1295603 Table 6 C Si Μη Ρ S Balance 0.04 0.02 1.35 0.013 0.003 Iron and unavoidable impurities Next, the method for evaluating the performance is described. The mechanical properties of the weld metal are in accordance with the tensile test method for butt welded joints specified in Japanese Industrial Standards j I s Z 3 1 2 1 and the impact test method for welded joints specified in JI SZ 3 1 2 8 Determine the mechanical properties of the weld metal. In these tests, samples with a tensile strength of 560 Ν/mm2 or higher and an absorption energy of 1 〇〇j or higher in the Charpy impact test at a test temperature of -20 °C were rated as "good". Samples having a tensile strength of less than 560 N/mm2 or an absorption energy of less than 100 J in the Charpy impact test at a test temperature of -20 °C were rated as "failed". Bead formation of high-speed welding The bead formation property of high-speed welding is evaluated as follows. A sample lap joint having a composition of Table 6 and a high-strength steel sheet having a thickness of 2·9 mm was used on a 1.0 mm weld edge opening at a welding current of 250 A and a welding speed of 1·5 m/min. A gas mixture of vol% Ar and 20 vol% C02 was used as a shielding gas for MAG pulse welding. Samples that did not exhibit defects such as undercut, burr beads, burn through and penetration, and could overlap the gap throughout the weld were rated as "good", and samples with defects were rated as "failed "-33- (30) 1295603 Welding processability The weldability is evaluated by observing the regularity of arc stability and droplet transfer using a high-speed camera and measuring the number of discrete sputterings. In this procedure, a gas mixture of 80 vol% Ar and 20 vol% C 〇 2 was used as a shielding gas, and a pulseless MAG welding was performed at a welding current of 250 A and a welding speed of 1.0 m/min. Samples with high droplet transfer regularity and small shots were rated as 'good', and samples with at least one of arc stability, droplet transfer regularity, and sputter count were rated as "failed". Coating property In the electrodeposition coating step after soldering, the coating property is evaluated according to the risk of delamination of the coating due to peeling of the solder. According to the soldering bead surface after soldering The risk is determined by the area of the weld slag. In this procedure, a gas mixture of 80% by volume Ar and 20% by volume C02 is used as the shielding gas, the welding current at 250 A and the welding speed at 1 · 〇m/min. The sample was subjected to pulseless MAG welding. The sample having a ratio of weld slag area to bead surface area of less than 1% was rated as "good", and the sample having a ratio of 10% or more was rated as "failed". Fishbone crack resistance test The hot crack sensitivity of the weld metal is evaluated based on the fish bone fracture test and the results of the crater crack test described below. -34- (31) 1295603 The position of the test piece sample is shown in Figure 2A. Referring to Fig. 2A, a low carbon steel SM490A having a thickness of 20 mm as a base metal 11 was used, and a butt welding was performed at an oblique angle of 45 by using a gasket metal 13 containing a low carbon steel SM490A. The resulting welded joint was mechanically cut to a thickness of 5 mm to obtain a test piece 14 for a fish bone crack test having a width of 175 mm, a length of 250 mm, and a thickness of 5 mm. Next, as shown in Fig. 2B, slits 15 are formed at regular intervals on both ends of the long sides of the test piece 14. The slit 15 has a varying length, increasing from the short side to the other side, so that the thermal deformation (thermal stress) applied to the molten metal continuously changes with the length of the slit. Specifically, in the slit 15 having a short side of a small length, the thermal deformation is large, and the slit 15 has the other short side of a large length, and the thermal deformation is small. The test piece 14 was placed on a copper plate 16 having a width of 75 mm, a length of 500 mm, and a thickness of 25 mm, and TIG welding was performed under the conditions of Table 7 below, in which the test plate was moved. In this procedure, a static arc is applied for about 5 seconds at the end of the plate having a shorter length in the slit, thereby sufficiently melting the end of the plate and thermally deforming the end of the plate, causing shrinkage during cooling at the end of the plate. / Curing crack (hot crack) caused by solidification deformation. Next, the welding is performed in accordance with the welding direction 17 from the end of the plate where the crack occurs to the other end of the slit having a longer length. The heat crack resistance was evaluated based on how far (how long) the crack was extended from the end of the test piece 14 . The length of the crack corresponds to thermal deformation, that is, thermal crack sensitivity. Specifically, a color inspection was performed after the welding, the length of the crack formed in the bead 12 was measured, and the ratio (crack ratio) of the crack length to the length of the test piece was determined. Samples with a crack ratio of 5% or less were rated as "good", and samples with a crack ratio of more than 5% were rated as "failed" by -35- (32) 1295603. Table 7 Soldering method Solder bead shielding gas on TIG plate 100% Ar, 20 liters/min welding current 200 A welding speed 30 cm/min crater crack test using SM490A steel sheet, on a V-shaped groove with a depth of 5 mm and a slope of 90. Bevel, under the same conditions MAG welding, intermittently forming three welding beads of about 70 mm length. Determine the total length of cracks on the surface of each joint. Determine the ratio of crack length to the length or diameter of the weld, and use three welds. The average enthalpy of the ratio was used as an index. Samples with an average crack ratio of 15% or less were rated as "good", while samples with an average crack ratio of more than 15% were rated as "failed".

Weld bead diameter P For the sake of convenience, the weld bead diameter P is measured as an index of the fatigue strength of the welded joint, since the stress concentration is reduced as the weld bead diameter P increases, and the fatigue strength is improved. Specifically, a gas mixture of 80% by volume of Ar and 20% by volume of C 02 is used as a shielding gas, and at a welding current of 250° A and a welding speed of 1.5 m/min, according to the horizontal foot welding, for the table 6 MAG pulse welding was performed by lap joints (1 ap -36- (33) 1295603 joint) of high-strength steel sheets with a thickness of 2 · 9 mm. Then, the weld bead diameter P as shown in Fig. 1 was measured. Samples with a weld edge diameter P of 0.3 mm or greater were rated as "good, and samples with a weld bead diameter P less than 〇. 3 m m were rated as "failed." The results of the above evaluation are shown in Table 8 below.

-37- (34)1295603 Table 8

No. Welding machine mechanical properties High-speed welding Bead formation Welding processability Coating fish bone crack test Arc pit crack test Weld bead diameter P Crack ratio (%) Evaluation crack ratio (%) Evaluation of weld bead diameter (mm) Evaluation 1 Good Good Good Good 0 Good 0 Good 0.53 Good 2 Good Good Good Good 3.5 Good 4.1 Good 0.41 Good 3 Good Good Good Good 0 Good 0 Good 0.36 Good 4 Good Good Good Good 1.5 Good 0 Good 0.63 Good 5 Good Good Good Good 0 Good 2.2 Good 0.41 Good 6 Good Good Good Good 0 Good 0 Good 0.59 Good 7 Good Good Good 3.4 Good 8.5 Good 0.78 Good 8 Good Good Good Good 0 Good 0 Good 0.31 Good 9 Good Good Good Good 3.5 Good 6.1 Good 0.82 Good 10 Good Good Good Good 0 Good 0 Good 0.53 Good 11 Good Good Good Good 0 Good 0 Good 0.59 Good Real 12 Good Good Good Good 0 Good 0 Good 0.45 Good Good 13 Good Good Good 2.5 Good 5.2 Good 0.33 Good Example 14 Good Good Good Good 0 Good 2.3 Good 0.63 Good 15 Good Good Good Good 3.9 Good 5.5 Good 0.41 Good 16 Good Good Good Good 2.2 Good 4.5 Good 0.88 Good 17 Good Good Good Good 1.2 Good 0 Good 0.33 Good 18 Good Good Good Good 0 Good 5.6 Good 0.54 Good 19 Good Good Good Good 0 Good 0 Good 0.59 Good 20 Good Good Good Good 0 Good 0 Good 0.31 Good 21 Good Good Good Good 0 Good 0 Good 0.35 Good 22 Good Good Good good 0 Good 0 Good 0.38 Good 23 Good Good Good Good 2.5 Good 8.9 Good 0.51 Good 24 Good Good Good Good 0 Good 0 Good 0.49 Good 25 Good Good Good Good 0 Good 0 Good 0.31 Good 26 Good Good Good Good 10.3 Unsatisfactory 14.3 Good 0.43 Good 27 Unqualified Good Good Good 15.2 Unsatisfactory 20.3 Unsatisfactory 0.56 Good 28 Unqualified Good good 20.1 Unsatisfactory 35.5 Unsatisfactory 0.85 Good 29 Good good Good good 9.3 Unsatisfactory 14.3 Good 0.40 Good 30 Unqualified Good Good Good 14.2 Unsatisfied 15.5 Unsatisfactory 0.55 Good 31 Unqualified Good Unqualified Unqualified 6.7 Unqualified 16.0 Unqualified 0.33 Good 32 Unqualified Unqualified Good Unqualified 4.3 Good 14.2 Good 0.84 Good 33 Unqualified Unqualified Unqualified Unsatisfactory 4.0 Good 10.2 Good 0.69 Good 34 Good Good Good 8.9 Unsatisfactory 20.5 Unsatisfactory 0.53 Good 35 Good Failure Good Good 0.0 Good 0.0 Good 0.18 Unsatisfied 36 Good failure Good good 0.0 Good 0.0 Good 0.23 Unsatisfactory ratio 37 Good failure Not acceptable Good 0.0 Good 0.0 Good 0.59 Good 38 Good failure Not acceptable Good 3.5 Good 10.9 Good 0.82 Good example 39 Good unqualified unqualified good 0.0 Good 0.0 Good 0.68 Good 40 Good unqualified Unqualified Good 0.0 Good 0.0 Good 0.45 Good 41 Good unqualified Good 3.2 Good 17.5 Unsatisfactory 0.68 Good 42 Good Good Good Good 6.3 Unsatisfied 15.3 Unsatisfactory 0.35 Good 43 Good Failure Unqualified Good 4.5 Unqualified 18.0 Unsatisfactory 0.38 Good 44 Unqualified Good Unqualified Unqualified 5.5 Unqualified 20.3 Unqualified 0.43 Good 45 Failed Good Good Good 21.1 Unsatisfactory 35.5 Unsatisfactory 0.84 Good 46 Failed Good Good Failed Good 4.3 Unqualified 5.5 Good 0.35 Good 47 Unqualified Unqualified Unqualified Unqualified 20.2 Unqualified 43.3 Unqualified 0.23 Unqualified 48 No Qualified unqualified good good 5.5 unqualified 10.3 good 0.21 unqualified 49 unqualified unqualified unqualified unqualified 6.3 unqualified 15.5 unqualified 0.35 good 50 unqualified good good 5.6 unqualified 16.3 unqualified 0.69 good -38- (35) 1295603 These results show that the solid wire of Examples 1 to 25 has a composition within the scope defined by the present invention and is excellent in all evaluations. In contrast, the solid wire of Comparative Examples 26 to 50 has a composition outside the range defined by the present invention, and the bead formation at high speed welding, the mechanical properties of the weld metal, the bead diameter P, the thermal crack sensitivity, and the coating At least one of the cloth properties and the weldability is poor. Specifically, Table 8 shows that the solid wire of Examples 1 to 25 having the composition of the range defined by the present invention is excellent in all evaluations. In contrast, the solid wire of Comparative Examples 26 to 50 has a composition outside the range defined by the present invention, and the bead formation at high speed welding, the mechanical properties of the weld metal, the bead diameter p, the coatability, and the hot crack At least one of sensitivity and weld processability is undesirable. The solid wire of Comparative Examples 26 to 30 does not contain any one of Cr, Ni, Nb, V, A1 and B, or contains any one of these elements but the content thereof is smaller than the range defined by the present invention, thereby The weld metal exhibits increased hot crack sensitivity and insufficient strength and toughness. The solid wire of Comparative Example 3 1 had an excessively high carbon content, thereby exhibiting insufficient weld metal toughness and increased hot crack sensitivity. It also exhibits coarse droplets, increased sputtering, and a large amount of weld slag which causes poor coatability. The solid wire of Comparative Example 3 2 had an excessively high manganese content, thereby exhibiting insufficient toughness of the weld metal, generation of bulge weld beads in high-speed welding, and failure to form normal weld beads. It also causes a large amount of weld slag and exhibits poor coating properties. The solid wire of Comparative Example 3 3 had an excessively high niobium content, thereby exhibiting insufficient toughness of the weld metal, coarse droplets, and increased sputtering. It also caused a large amount of weld slag, which exhibited poor coating properties from -39-(36) 1295603. The solid wire of Comparative Example 4 4 had an excessively high phosphorus content and exhibited high thermal crack sensitivity. Comparative Example 3 The solid wire of 5 and 3 6 has an excessively low sulfur content. Despite exhibiting low thermal cracking sensitivity, it exhibits poor bead formation and small bead diameter in high speed welding. Comparative Example 3 The solid wire of 7 to 40 contained an excessive content of at least one of Cr, Ni, V and A1, and thus was expensive and produced a bulge bead in high-speed welding. It also shows coarse droplets and a large amount of sputtering. The solid wire of Comparative Example 4 1 has an excessively high niobium content' thus exhibiting high hot crack sensitivity, being expensive, and producing a bulge bead in high speed welding. It also shows coarse droplets and causes a lot of sputtering. The solid wire of Comparative Example 42 had an excessively high boron content, thereby exhibiting high thermal crack sensitivity. The solid wire of Comparative Example 43 had an excessively high boron and vanadium content, thereby exhibiting high hot crack sensitivity, being expensive, and producing a drum bead in high speed welding. It also shows coarse droplets and causes a lot of sputtering. The solid wire of Comparative Example 44 had an excessively high niobium content and an excessively low manganese content, thereby indicating insufficient weld metal strength, coarse droplets, and increased sputtering. It also causes bulging beads and a large amount of slag in high-speed welding, and exhibits poor coatability and high thermal crack sensitivity. The solid wire of Comparative Example 45 had an excessively high sulfur content, so that the weld metal exhibited insufficient strength and toughness and high hot crack sensitivity. The solid wire of Comparative Example 46 had an excessively low carbon and manganese content, so that the weld metal exhibited insufficient strength and high thermal crack sensitivity. The solid wire of Comparative Example 47 had an excessively high carbon content and an excessively low niobium content, so that the weld metal had insufficient toughness and increased hot crack sensitivity. It also exhibits poor bead consistency, small welds -40-(37) 1295603 side diameter, resulting in coarse droplets, increased sputtering and large amounts of weld slag, and exhibits poor coating properties. The solid wire of Comparative Example 4 8 had an excessively low yttrium content and an excessively high phosphorus content, so that the weld metal showed insufficient strength, poor bead uniformity, small weld bead diameter, and high hot crack sensitivity. The solid wire of Comparative Example 49 had an excessively high carbon and manganese content, so that the weld metal exhibited excessive strength and poor toughness. It also causes bulging of the bead in high-speed welding, so that normal bead cannot be formed, and droplets of coarse I, increased sputtering, large amount of weld slag, poor coatability, and high thermal crack sensitivity are exhibited. A solid steel wire of a proportion of 50 has an excessively low carbon content and an excessively high phosphorus content, thereby exhibiting insufficient weld metal strength and high hot crack sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing a welded edge of a welded joint of a foot; and Fig. 2A is a sectional view showing a sampling position of the test piece, and Fig. 2B is a test piece showing how to prepare a fish bone crack resistance test. Floor plan. [Symbol description of main components] la: base metal (lower sheet), lb: base metal (upper sheet) 2: solder beads, 1 1 : base metal, 12: solder beads 13 : gasket metal, 14 : test Sheet, i 5 ··slit 1 6 : copper plate, 1 7 : welding direction • 41 -

Claims (1)

1295603 (1) X. Patent application scope 1. A solid wire for gas-shielded arc welding, comprising: 〇.〇3 to 0.15 mass% of carbon (C) based on the total mass of the wire; 〇·50 to 1.50% by mass of bismuth (Si); 1·〇〇 to 3.00% by mass of manganese (Μη); 0.020 to 0.150% by mass of sulfur (S); and selected from: 0.01 to 0.20% by mass of titanium (Ti), 〇.〇1 to 〇2 〇瘫· 0.5% by mass of chromium (Zr), 0.01 to 〇·〇5 mass% of lanthanum (La), and 0.01 to 0.05% by mass of lanthanum (Ce) At least one of the populations of the group f is iron and unavoidable impurities, wherein the content of phosphorus (P) as an unavoidable impurity is 〇.25 mass% or less, and wherein it is determined according to the following equation "A"値 is 100 or more; [M]]+20x [37]+25x [Zr]+50x [La]+50x [Ce] • 乂= W] where [Mn], [Ti], [ Zr], [La], [Ce], and [S] represent the contents of Μη, Ti, Zr, La, Ce, and S (% by mass) of the wire, respectively. 2. The solid wire for gas-shielded arc welding according to the first application of the patent scope, which has a manganese (Mn) content of 1.5% by mass or more. 3. A solid wire for gas-shielded arc welding according to claim 1 of the patent application, which has a sulfur (S) content of 0.040% by mass or more. 4. A solid wire for gas-shielded arc welding, comprising: -42- (2) 1295603 0.02 to 0.15 mass% of carbon (C); 0.50 to 1.50 mass% based on the total mass of the wire矽 (Si); 1.00 to 3.00% by mass of manganese (Μη); 0.020 to 0.150% by mass of sulfur (S); 0.005 to 0.5% by mass of bismuth (Nb); and selected from: 0.005 to 0.5% by mass of vanadium (V), 0.010 to 0.5% by mass of aluminum (A1), 0.005 to 0.5% by mass of chromium (Cr), 0.005 to 0.5% by mass of nickel (Ni), and 0.0010 to 0.0100% by mass of boron ( B) at least one of the group consisting of; the balance being iron and unavoidable impurities, wherein the content of phosphorus (P) as an unavoidable impurity is 0.025 mass% or less. 5. A method of gas-shielded arc welding comprising the steps of welding a low carbon steel or a high-strength steel sheet having a thickness of 0.6 to 10 mm using a solid wire of the first application of the patent scope. -43-