TW200911443A - Solid soldering wire for carbon dioxide gas protection arc welding - Google Patents

Abstract

The invention provides a solid core welding wire used for CO2 gas shielded arc welding which contains: C: 0.020-0.100 wt. %, Si: 0.65-1.10 wt. %, Mn: 1.40-1.74 wt. %, P: 0.005-0.018 wt. %, S: 0.007-0.020 wt. %, Ti: 0.11-0.18 wt. %, B: 0.0015-0.0073 wt. %, C+15*B: 0.0600-0.1990 wt. %, Mo: less than 0.08 wt. %, O: less than 0.0100 wt. %, Cu: less than 0.45 wt. %, allowance is Fe and unavoidable impurity. The solid core welding wire with 540N/mm<2> mechanical property is used as welding metal with excellent slag peeling property, lower slag amount, better intensity and tenacity whatever plate thick in robot constructing, in addition, splash amount is reduced.

Description

200911443 IX. INSTRUCTIONS OF THE INVENTION [Technical Field] The present invention relates to a solid electrode for carbon dioxide gas shielded arc welding, which is used for the purpose of carbon steel gas shielding arc welding of mild steel or 490 to 520 N/mm2 high tensile steel. It is high and can obtain a welded metal with good mechanical properties. [Prior Art] In recent years, the "shielding arc welding method" in which the C 〇 2 is used as a shielding gas in the field of building reinforcement has been used as a main force due to its high efficiency. Most of the manual semi-automatic welding methods have been used so far, but the use of automatic welding of robots has begun to take effect based on saving human resources to reduce costs and utilizing no-night operation at night and holidays to further improve efficiency. On the other hand, 'in terms of welding quality' is mainly to improve the performance of the welded joint in order to improve the shock resistance. In the JASS6 revision of 1997, the revision of the Building Standard Law of 1999, the supply for welding Upper limit management of heat and interlayer temperature. In response to this trend, welding rods for high-heat and high-rise temperatures have been developed for welded electrodes. For 490N/mm2 carbon steel sheets, the maximum heating capacity is 40kJ/cm and the interlayer temperature is 3 5〇°c. For the 5 2 ON/mm2 grade carbon steel plate, it can tolerate a maximum heat supply of 30 kJ/cm and an interlayer temperature of 25 〇. (:, 540N/mm2 grade in 999 = YGW18 obtained JIS. After that, this 5 4 ON/mm2 grade electrode with excellent mechanical properties even at high heating and high-rise temperatures is very fast at 200911443. The speed has been popularized. The 540N/mm2 class electrode has been popularized for the semi-automatic welding which is difficult to manage in heating and interlayer temperature. Recently, the application of 540N/mm2 electrode in robot welding has become more common. The electrode corresponding to the high current and the inter-high temperature for the known carbon dioxide gas welding developed so far has more deoxidizing components such as S i, η η, and T i than the conventional electrode, and is added as needed. Mo, B, Cr, A1, Nb, V, Ni, etc., thereby improving the hardenability of the steel, and improving the toughness, precipitation hardening, and solid solution hardening due to grain refinement, and also improved Strength. This type of welding rod, the larger the groove width, the higher the inter-layer temperature and the greater the plate thickness, the more significant the effect. However, the actual situation of these conventional electrodes is that the design does not take into account the robot loading. situation In the electrode corresponding to the conventional high current and high temperature, there is a disadvantage that the amount of slag generated is too large and the peelability is poor. Since the slag is insulative, the deposited slag hinders arc stability and becomes insufficient for fusion penetration and melting. The direct cause of defects such as slag pollution. In addition, as long as the slag is slightly unnaturally peeled off, the robot will continue to start the arcing even if it is offset from the arcing position, and the arcing error will continue to occur, and the robot will judge the error and stop the operation. Although it exerts its greatest strength in unmannedness, it is unstable due to slag accumulation in a short period of time, and it is necessary to manually remove slag frequently. In order to repair the arcing error, it is necessary to perform slag in the arcing portion. Therefore, in order to solve the problem, it is expected that a fusion welding electrode can be proposed with a maximum heating temperature of 40 kJ/cm 'maximum interlayer temperature of 3 5 0. (: with a condition of 200911443 49ΟΝ/mm2 The mechanical properties required for the grade steel, the amount of slag generated is small, the peelability is also good, the continuous laminate height is high, and the efficiency is high. In response to this expectation, the electrode which can improve the slag removability includes the electrode disclosed in Japanese Patent Laid-Open No. Hei. No. 2006-305605, and No. 2006-150437. It is also disclosed in Japanese Laid-Open Patent Publication No. 2004-122170 and Japanese Patent Application Laid-Open No. Hei No. No. 2006-26643, the slag-removability of the slag is improved. The welding rod has a more pronounced effect on the steel plate with a larger plate thickness. Therefore, in the past, a relatively thin plate thickness of less than 20 mm, which is not too high in heat supply and interlayer temperature, is 490 N/mm 2 used in view of cost. Level = YGW11 is considered to be sufficient to meet the needs, and 540N/mm2 grade = YGW1 is used in the case of thicker plate thickness. Recently, based on: replacement trouble, welding rod cost and 490N/ in the popularity of 540N/mm2 electrode. The reason why the gap of the mm2 grade is reduced, and the tendency of the building structure equipment to increase the strength of the earthquake resistance is high, and the 540N/mm2 grade electrode is used even in the case of a thin steel plate. However, this will cause 3 questions. The first problem is that because the grooved area is small, there is a case where the heating can only be increased to about 2 5 kJ / cm, and since the number of layers is also small, the interlayer temperature has not risen to about 200 °C before welding. It is already done. That is to say, due to the low heating rate and the low interlayer temperature, the cooling rate is too fast. The conventional 540N/mm2 electrode can not maintain the state of the ferrite iron structure and is refined, but is oriented toward the toughened iron structure or hemp. The occurrence of tissue abnormalities in the iron field of the field has caused the toughness to become lower. -7- 200911443 The second problem is that the maturity of the base metal of the backing plate is relatively increased due to the smaller the grooved area, which is susceptible to the composition. Nowadays, in order to use a low-quality steel sheet having a large nitrogen content for a low price, the increase in the nitrogen content in the welded metal causes a decrease in toughness. The third problem is that because the interlayer temperature is not too high, the fusion is completed before the slag starts to peel off, but it is not meaningful that the slag removability is good, and it is more important to reduce the amount of slag. However, in the case of the above-mentioned Japanese Patent Laid-Open No. 2006-88187 and Japanese Patent Application Laid-Open No. 2006-150437, when the strength is too high and the sheet is used for a thin plate, the welded portion is reduced in toughness and the amount of slag is not reduced. Therefore, there is no improvement in the work. Further, in Japanese Laid-Open Patent Publication No. 2006-26643, although the slag removability is improved and the amount of slag formation is reduced, mechanical properties are not considered, and excessive strength and consequent low toughness cannot be avoided. In the Japanese Patent Laid-Open No. 2004- 1 22 1 〇, the applicability of the robot is not considered, and the decrease in the amount of slag and the improvement in the peelability are insufficient. Further, when used for a thin plate, the toughness of the welded portion is insufficient. SUMMARY OF THE INVENTION The present invention has been made in view of the related problems, and an object thereof is to provide a solid electrode for carbon dioxide gas shielding arc welding suitable for continuous welding, which has a basic mechanical property of 5 40 N/mm 2 = YGW 18 . In the construction using the robot, regardless of whether the thickness of the sheet is thin or thick, that is, the thickness of the slag is excellent, the slag peeling property and the slag amount can be improved, and the welded metal having good strength and toughness can be obtained, and the melting can be obtained. Splashes are also generated in small quantities. * 8 - 200911443 The solid electrode for carbon dioxide gas shielded arc welding of the present invention has a C: 0.020 to 0.100% by mass, si: 〇.65 uo mass%, Mn: mass. /. Ρ: 〇〇〇5 ～〇·018 mass %, S: 〇·007 ～0.020% by mass, Ti: OB mass%, B 1.0015~ 0.0073 mass. /. , C+15XB: 0.0600 ~ 〇" 99 〇 mass. /. , 0.08 quality. /. Hereinafter, 〇: 〇.〇1〇0% by mass or less, Cu: 〇_45% by mass or less, and the remainder is F e and unavoidable impurities. Here, in the C11 crucible, when the surface of the electrode is plated with C ,, the n 卩 portion of the C U plating is included. In this case, the content of ruthenium is preferably 0.01% by mass or less. Further, in the present invention, it is also possible to contain Nb of 8% by mass or less, V of 〇0.88% by mass or less, A1 of not less than 0.08% by mass, Cr of 0.50% by mass or less, and 0.50% by mass or less. At least one of N i is included. Further preferably, the ratio of 焊.〇 1 to 丨.00^ per l〇kg of the electrode surface is Μ 〇 S 2 . According to the present invention, it is possible to obtain a solid electrode for carbon dioxide gas shielding arc welding suitable for continuous welding, which has sufficient basic mechanical properties as a welding rod of 5 40 N/mm 2 grade, and can be used without any thickness in the construction using a robot. Excellent slag releasability and reduced slag amount are obtained. Further, according to the present invention, it is possible to obtain a welded metal having good strength and toughness, and the amount of occurrence of the spatter is also reduced to the same level as a conventional electrode such as YGW11 or YGW18 used for semi-automatic welding. [Embodiment] The inventors of the present invention repeatedly conducted related research on fusion slag, and explained the influence factors of -9-200911443. The amount of fusion slag generated is most strongly correlated with the strong deoxidation component, i.e., the amount of Μη and the amount of Ti. As the content thereof increases, the amount of slag production increases. The peeling property of the slag, the interface energy between the molten slag/fused metal in the molten state, the strength of the slag itself after solidification, and the unevenness of the surface of the welded metal (that is, the difference in physical height and the frequency of generation of the high and low portions) A strong relationship results in a decrease in the peelability due to an increase in Μη and a decrease in S and P. On the other hand, based on these findings, excessive reduction in slag formation and peeling improvement techniques are likely to cause disadvantages such as deterioration in mechanical properties such as strength and toughness, and occurrence of high-temperature cracks.

Mo is known as an element which can increase the strength of the weld metal. In the JI SZ 3 3 1 2 YGW 1 8 specification, the addition of the upper limit is allowed to be 0.40 mass% or less, but the supply of the sheet is low. Under the conditions of heat and low interlayer temperature, excessive quenching due to the addition of niobium will result in significant low toughness. Therefore, in the robot welding which can completely control the heating and the interlayer temperature, it is preferable that the electrode can be applied to a thick plate having a thickness of about 12 mm to a thick plate having a thickness of about 80 mm. It is not added Μ 〇. As a factor affecting the weldability other than the electrode component, it has been found that if the supply of the electrode is unstable, the formation of the molten pool is broken, and the thickness of the generated slag is not uniform, and the slag releasability is deteriorated. The invention will be described in detail below. First, the composition of the electrode of the present invention will be described with respect to the reason for its component addition and the reason for the composition limitation. "C: 0 · 0 2 0 - 0. 1 0 0% by mass" -10- 200911443 C is used to ensure the strength of the welded metal. It is important to add an element, but when C is less than 0.02% by mass, the strength required for high-heat and high-temperature temperature fusion cannot be ensured. C is preferably 0.05% by mass or more. On the other hand, if c is added in excess of 0.100% by mass, high temperature cracks will easily occur. Further, when c is added in excess of 0.100% by mass, the amount of occurrence of the spatter is increased due to the CO explosion phenomenon in the arc atmosphere, and the arc stability is deteriorated. In addition, the strength is excessive and the toughness is reduced. Therefore, the C content is set to be 0.10% by mass or less. “ S i : 0.0 6 5 〜1 . 1 0 mass % ”

Si is added to ensure strength and prevent stomata defects caused by deoxidation. Further, if Si is added, the slag peeling property is improved although the amount of slag is increased. These effects are obtained by setting the Si content to 0.65 mass% or more. When the Si content is less than 0.65% by mass, the slag removability is deteriorated, and the arc is destabilized. Further, it is preferable that the lower limit Si of the Si content is 0.75% by mass. On the other hand, when the Si content exceeds 1.10% by mass and is excessively added, the amount of slag is excessive, the arc stability is deteriorated, and the toughness of the weld metal is lowered. Therefore, the Si content is set to 1.0% by mass or less. “ Μ η : 1.4 0 〜 1 · 7 4 mass % ” The addition of Μη has the effects of deoxidation, strength enhancement and high toughness. When the Μη content is less than 1.40% by mass, the strength and toughness of the welded metal at the time of high heat welding are insufficient. On the other hand, the general high-heat-welding electrode contains a large amount of Μη, but Μη has a problem of increasing the amount of slag generated and deteriorating the peeling property. In addition, when the welding is performed by a robot or the like, since the welding rod is stabilized in a state in which the protruding length is short, the shielding property is good. -11 - 200911443 Goodly, the oxidation consumption of the deoxidizing element is small even under the condition of high heat welding. The advantages. Therefore, when automatic welding is performed by a robot or the like, the balance between the mechanical properties of the weld metal and the amount of slag generated and the slag peelability can be improved by setting the Μη content to be small. If the Μ η content exceeds 4.7 mass%, the amount of slag increases and the peelability decreases. As a result, the arc stability is also deteriorated. Therefore, the Μη content is set to 1.40 to 1_74% by mass. "S: 〇·〇〇7 ~ 0.020% by mass, Ρ: 0.005 to 0.018% by mass »» By the addition of S and yttrium, the surface tension of the molten pool is lowered, and the physical unevenness at the time of solidification is reduced, and the metal is welded. The surface smoothing effect is such that the slag releasability is improved. When S is less than 0.07% by mass and Ρ is less than 0_005% by mass, this effect is not obtained. Therefore, the slag releasability is lowered, and arc stability is caused. Deterioration: S: 0.010% by mass or more, Ρ: 0.007 mass% or more. On the other hand, when S is added in excess of 0.020% by mass and Ρ is more than 0.018% by mass, the surface shape of the welded metal is improved. In addition, the shape of the slag is likely to occur, and the shape of the slag is granulated, which hinders the melting of the arc and locally causes arc instability. Further, if S and bismuth are excessive, the toughness of the weld metal is also lowered. The upper limit of S is set to 0.020% by mass, and the upper limit of Ρ is set to 0 · 0 1 8% by mass. "T i : 0.1 1 〜 0 · 1 8 mass % ”

Ti increases the arc stability in the high current region. When Ti is less than 0 · 1 1 mass%, the arc stability is deteriorated, and the amount of occurrence of spatter is increased. Therefore, Ti needs to be added in an amount of 0.11% by mass or more. On the other hand, when Ti is added in excess of -12-200911443 0.18 mass%, the amount of slag becomes too large, and the peeling property is also deteriorated. It is difficult to melt by arc and the arc stability is deteriorated. In the semi-automatic welding, most of the welding rods having a wire diameter of 1.4 to 1.6 mm are used. Based on the viewpoint of arc stability, it is preferable to add Ti to 0 to 20% by mass or more. However, in the robot welding, a diameter of 1.2 mm is generally used. Since the electrode is not necessary, it is not necessary to add so much Ti, 0.18% by mass or less, and sufficient arc stability can be obtained. From the viewpoint of the reduction in the amount of slag, it is necessary to make the Ti content 〇·18% by mass or less. The upper limit of the preferred T i is 〇 16.6% by mass or less. "B : 0.0 0 1 5 ~ 0 · 0 0 7 3 % by mass, 'B is added in a small amount to make the grain of the weld metal fine, and has an effect of improving the strength and toughness. Although there is also YGW 1 which does not add B. 8 electrode, but in the thinner thin plate, considering the nitrogen component from the high nitrogen pad, in order to improve the toughness, it is necessary to add B to improve the toughness of the weld metal. When B is less than 0.0015 mass%, because The effect of improving the strength and the toughness is not obtained, and the toughness is insufficient. Therefore, the lower limit of B is determined to be 0.0015% by mass. On the other hand, when B is excessively added and more than 0.0073% by mass, high-temperature cracks are likely to occur. The upper limit is 0.0073 mass%, and the B content is more preferably 0.0054 mass% or less, particularly preferably 0.0040 mass% or less. ** C + 1 5 XB : 0.0600 to 0.1990 mass 0 / 〇" According to the contents of C and B, When C + 1 5xB is set as the parameter PCB, Pcb must be 〇_〇600~0.1990% by mass. As described above, the respective contents of C and B must be specified separately, and in the manner of the parameter PCB = C + 1 5 ,, the PCB of the parameter PCB must be limited to the prescribed range. -13- 200911443 In the present invention, generally, it is not necessary to add Mo having a large effect of increasing the strength, or to make it close to the lowest enthalpy, and in order to reduce the amount of slag generated, Μη is also compared with the general YGW 18 Low sputum, in which case there will be insufficient strength. Therefore, when Pcb = C + 15XB is 0.0600 or more, the strength improvement effect by C and B is improved, and sufficient strength can be obtained. On the other hand, both C and B are elements which deteriorate the high temperature crack resistance, and if both elements are high in content, cracks are likely to occur. However, when Pc C + 15xB is 0.1 9 90% by mass or less, there is no problem of high temperature cracking in practical use, so Pcb = C + 15xB is set to 0.1 9 90% by mass or less. In the first drawing, the range of the contents of C and B specified in the present invention is indicated by hatching, and the horizontal axis represents the C content and the vertical axis represents the B content. Among them, Mo is 〇.〇8 mass% or less, and Μη is 1.74 mass% or less. As shown in Fig. 1, when C and strontium are high, high temperature cracks become a problem. Further, if the content of C and bismuth is low, the strength or toughness of the welded metal is lowered. Μ 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 熔 熔In the case of a thin plate, the excessive strength causes a low toughness. In the case of a thick plate and when the robot is welded, since the welding heat supply and the interlayer temperature can be completely grasped and controlled according to the welding procedure, it is not necessary to excessively add Μο ' to make the strength excessive. Therefore, in the present invention, it is preferable not to add Μο. However, it is acceptable to contain Mo in an amount of 0.08% by mass or less as an impurity. If the content of Mo exceeds 0.08 mass%, the toughness will be remarkably lowered. More preferably, the M 0 content is lower than 〇 _ 〇 〖 mass %, 14 - 200911443 "0 : 0 · 0 1 0 0 mass % or less" The fusion slag is an oxide. Therefore, if the amount of ο increases, the amount of slag produced by the reaction also increases. As a result, arc stability and high temperature cracks are also likely to occur due to an increase in inclusions. However, when the content is 0.0100% by mass or less, the above problem is not caused, and therefore it is set to be 0.0100% by mass or less. Also, the effect of 〇 is independent of the state. That is to say, the effect of 0 has nothing to do with the volume and position of the wire, but must be specified by the total amount of zero. "C U : 0.4 5 mass% or less" Excessive addition of C u causes high temperature cracking of the weld metal, and changes the properties of the slag to deteriorate the peelability. The arc stability is degraded. Therefore, the addition of Cu as a wire is actively added, and there is no technical significance. Most of the Cu is in the form of a copper plating component on the surface of the electrode in order to improve the electrical conductivity, rust resistance, linearity and appearance. presence. If the amount of Cu exceeds the amount % ', there is a problem of high temperature cracking and slag peeling property, so the upper limit 量 of the amount is 〇 · 5 5 % by mass. Also, not on the surface of the electrode, Cu means the amount of Cu contained in the wire; plating on the surface of the wire is 'C u means the total amount of copper in the wire and the surface of the wire.' Nb, V, A1 : respectively, 0.08 mass% or less, Cr, not 〇. 50 mass. The addition of a small amount of N b, V, A1, C r, and N i can increase the toughness of the crystal grains by fineness. However, if Nb, V, and A1 are added in excess of 〇·〇8, they are chemically degraded. Distribution surface and other prone to fruit production and division, is the application of 0.45 Cu copper plating copper when Cu 〇Ni: differentiation, and mass % -15- 200911443, Cr, Ni addition force more than 0.50% by mass, then occurs The increase in the amount of slag and the decrease in the peeling property cause the arc to be unstable, and the strength is excessive, and the toughness is also lowered. Therefore, N b, V, and A1 are 0.08 mass% as the upper limit 値' C r, N is 〇. 5 0 The mass % is the upper limit 値. Further, the range of Nb and V is preferably 0.02 mass% as the upper limit 値. For C r and N i , the more preferable range is 0.10 mass%. 〇 “M〇S2 on the surface of the electrode: 0.01~l.OOg per 10kg electrode” The supply of the electrode also has a great influence on the slag stripping property. By making the electrode supply stable, the molten pool will be The formation is stable, the thickness of the generated slag is uniform, and the heat shrinkage stress can uniformly act to make the whole The peeling is easy. The Mo S2 on the surface of the electrode strip reduces the welding of the power supply point between the power supply head and the electrode, and improves the supply of the electrode. In the past, a method of generating peroxidation at the grain boundary along the surface of the electrode to improve the supply of the electrode exists. The method of increasing the amount of slag by increasing the amount of slag. On the other hand, the method of improving the supply property of the electrode by applying M 〇 S2 is suitable as the present invention because there is no concern such as an increase in the amount of slag. A method for improving the supply of the welding rod of the welding rod. The effect is effective when the surface of the electrode is attached to the MoS2 at a ratio of 0.01 g or more per 1 kg of the welding rod. On the other hand, if the surface of the electrode is more than 1.0 g per 10 kg of the electrode. When MoS2 is attached, Mo S2 starts to accumulate in the electrode supply system such as a conduit liner, and the plug is blocked by Mo S2, which causes a poor supply of the electrode, which affects the properties of the slag and reduces the peelability. Therefore, the adhesion amount of Mo S2 to the surface of the electrode is limited to 1.00 g/10 kg of the electrode. -16- 200911443 [Examples] Next 'with the comparative example The characteristics of the embodiment of the present invention will be described in more detail and the effects of the present invention will be described. A welding test using a diaphragm having a slotted shape as shown in Fig. 2(a) and a round steel tube is used. The body 'welding conditions shown in Table 1 are welded using a commercially available robotic welding system for steel bars. As shown in the second (b) and (c), the horizontally disposed steel pipe 2' is vertically disposed at the front end thereof. 1. A V-groove is formed on the end surface of the steel pipe 2 on the separator 1 side, and the annular gasket 3 is placed under the groove of the welded portion between the separator 1 and the steel pipe 2. The slot is welded by the torch 4. Table 2 shows the combination of the shapes of the separator 1, the steel pipe 2, and the backing plate 3 (Condition 1 and Condition 2). Table 3 shows the composition of these separators 1, the steel pipe 2, and the backing plate 3. The separator 1 and the steel pipe 2 are manufactured by a blast furnace manufacturer. On the other hand, the backing plate 3 is manufactured by a commercially available electric furnace manufacturer, and has a high nitrogen content and poor weldability. Further, in Tables 2 and 3, the reference numerals of SN490C and the like indicate the materials specified by IS. Then, the peeling property of the slag after the completion of the welding was calculated by the digital image processing (Process 1). In addition, the amount of slag was measured (Process 2). Further, as an index of the strength and toughness of the welded metal, a tensile test and a Charpy impact test (Process 3) were carried out. In addition, the arc stability (Process 4) and the amount of spatter generated (Process 5) in the welding were also recorded. In addition, the occurrence of high temperature cracks was investigated by ultrasonic flaw detection test (Process 6). Table 4-1 to Table 4-4 show the composition of the electrode of the embodiment of the present invention and the electrode of the comparative example. Further, Tables 5-1 and 5-2 show the results of the fusion test of the examples and the comparative examples. In addition, in the chemical composition of Table 4, the content is expressed by the upper limit, indicating that the general lower limit of analysis is 値 from -17 to 200911443, and is considered to be not contained in the industry. Further, the remaining portion of the electrode component in Table 4 is F e . Next, the method of evaluating the peelability of the melt (Process 1) will be described. The evaluation of the peelability and the amount of slag was measured only under the condition that the thickness of the steel pipe was thin. Further, the welded electrode which performed well under Condition 1 was confirmed to be equally good under Condition 2. At the point where the welding start point is welded to the final layer, 'photographed at a position returning from the welding rod to 90°, 1 〇 〇 m m before and after, and a total of 200 mm. Fig. 3 is a photograph showing the appearance of the welded joint, and Fig. 3(a) shows a portion where the melting is naturally peeled off, and Fig. 3(b) shows a portion where the slag adheres. Then 'according to the photo of the appearance of the solder ball, the total image of each pixel (pixel) is calculated by the image analysis software, the number of pixels of the portion of [(a)] / { the number of pixels of the portion of [[a)] + [ The number of pixels in the portion (b)]}χι〇〇 obtained the slag peeling rate (% by mass). Then, the slag peeling rate was 15% by mass or more, and it was judged to be good. Next, regarding the amount of slag of the treatment 2, all the slag (including natural peeling) was recovered after the photograph of the appearance of the weld joint, and the weight was measured. The amount of the slag is preferably 1 2 g or less. In addition, the tensile test of the welded metal of the treatment 3 and the Charpy impact test are respectively in the condition! 2, 'A2 of JIS Z31 1 1 (parallel diameter 6 mm) and a standard test piece (a square cross section with a side length of 10 mm) were taken. Fig. 4 shows the position at which the tensile test piece was taken from the weld metal, and Fig. 5 shows the position at which the Charpy impact test piece was taken from the welded metal. Further, the tensile test was carried out at room temperature (20 °C), the Charpy impact test was carried out under ye, and the average enthalpy of each of the three test results was evaluated as 値. Then, the tensile strength was 490 N/mm2 or more, and the Charpy impact test was an average of 7 〇j or more. -18- 200911443 The arc stability of the treatment 4 is evaluated in the welding. In particular, it is judged to be good when the slag does not hinder the occurrence of the destruction arc. Also, it was judged to be unacceptable when an arc is broken due to poor supply of the electrode. The amount of spatter generated in the treatment 6 is such that after the welding at the condition 1 is completed, the spatter attached to the shield nozzle is recovered, and the weight is measured to be 6 g or less.

Welding machine type welding rod welding machine welding power supply, polar DC machine, reverse polarity shielding gas C〇2 flow rate 25 liters / min welding rod diameter 1 · 2 mm φ heating maximum 40kJ / cm interlayer temperature maximum 3 5 0 ° C posture downward welding rod protruding Length 2 2 〜2 5 mm Slag removal condition 1: Unconditional 2: There is a power supply head attached to the splatter removal, cleaning condition 1: Unconditional 2: Yes -19- 200911443 [Table 2] Partition steel pipe backing condition 1 (thin plate SN490C plate thickness 25mm&gt;&lt;450mm square STKN490B plate thickness 1 6 mm χ outer diameter 3 5 0 mm SN490A plate thickness 9mm χ outer diameter 3 3 4 mm condition 2 (thick plate) SN490C plate thickness 75mmx800mm square STKN490B plate thickness 6 0 Mmx outer diameter 70 0 0 mm SN490A plate thickness 9 mm χ outer diameter 6 4 0 mm [Table 3] Application / steel composition (% by mass) / residual Fe and 7 F avoidable impurities C Si Μ Ρ s N Plate / SN490C 0.15 0.3 5 1.45 0.0 10 0.003 0.0029 Steel pipe / STKN490B 0.09 0.12 1.02 0.0 10 0.003 0.0035 Plate / SN490A 0.11 0.13 0.46 0.017 0.022 0.0125 -20- 200911443 [Table 4 -1] Composition (% by mass) Plated No. C Si Ti Μη Mo s 0 P Cu Copper 1 0.060 0.90 0.15 1.65 &lt;0.005 0.011 0.0040 0.011 0.20 There are 2 0.090 0.90 0.15 1.60 &lt;0.005 0.013 0.0025 0.012 0.23 There are 3 0.040 0.95 0.16 1.55 0.02 0.008 0.0030 0.010 0.27 There are 4 0.040 0.75 0.17 1.74 &lt; 0.005 0.015 0.0035 0.009 0.25 There are 5 0.090 1.00 0.12 1.45 &lt;0.005 0.010 0.0072 0.015 0.17 There are 6 0.020 1.10 0.16 1.52 &lt;0.005 0.013 0.0010 0.007 0.30 There is real 7 0.100 0.85 0.15 1.50 0.007 0.018 0.0025 0.015 0.21 有施8 0.050 0.65 0.18 1.49 &lt;0.005 0.010 0.0043 0.008 0.10 Example 9 0.050 0.90 0.11 1.73 0.010 0.007 0.0078 0.005 0.21 There are 10 0.070 0.90 0.15 1.65 0.080 0.012 0.0020 0.010 0.20 There are 11 0.060 0.75 0.14 1.58 0.030 0.020 0.0060 0.010 0.28 There are 12 0.065 0.70 0.15 1.62 &lt;0.005 0.015 0.0066 0.012 0.44 There are 13 0.060 0.90 0.17 1.70 &lt;0.005 0.011 0.0030 0.011 0.20 There are 14 0.030 0.80 0.13 1.65 0.010 0.009 0.0098 0.008 0.15 There are 15 0.060 0.90 0.15 1.65 &lt;0.005 0.011 0.0040 0.011 &lt;0.001 te j \ w 16 0.050 0.77 0.16 1.41 &lt;0.005 0.0 13 0.0077 0.012 &lt;0.001 Μ j\w 17 0.090 0.90 0.17 1.57 &lt;0.005 0.010 0.0085 0.007 &lt;0.001 4πτ III 1 y * \\ 18 0.060 0.80 0.15 1.57 0.050 0.018 0.0020 0.018 &lt;0.001 sister j \\\ -21 - 200911443 [Table 4-2] Composition (% by mass) / M〇S2 is the content per 10 kg of electrode (g) No. B C+15B Nb V A1 Cr Ni MoS2 1 0.0030 0.1050 &lt; 0.005 &lt; 0.005 &lt; 0.005 0,010 &lt;0.005 &lt;0.01 2 0.0020 0.1200 &lt;0.005 &lt;0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.20 3 0.0054 0.1210 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.01 4 0.0045 0.1075 &lt;0.005 &lt; 0.005 &lt; 0.005 0.010 &lt; 0.005 &lt; 0.01 5 0.0018 0.1170 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.01 6 0.0027 0.0605 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.060 &lt;0.005 0.18 7 0.0066 0.1990 &lt;0.005 &lt;0.005 &lt;0.005 0.020 &lt;0.005 0.54 Application 8 0.0073 0.1595 0.080 &lt;0.005 &lt;0.005 0.020 &lt;0.005 &lt;0.01 Example 9 0.0030 0.0950 &lt;0.005 &lt;0.005 &lt;0.005 0.500 &lt;0.005 &lt;0.01 10 0.0054 0.1510 0.002 0.080 0 .011 &lt;0.005 0.100 0.29 11 0.0025 0.0975 0.050 0.003 0.003 0.200 0.050 &lt;0.01 12 0.0020 0.0950 &lt;0.005 0.050 &lt;0.005 &lt;0.005 0.020 0.77 13 0.0015 0.0825 0.009 &lt;0.005 0.080 0.030 0.500 0.98 14 0.0026 0.0690 &lt;0.005 &lt;0.005 &lt; 0.005 &lt; 0.005 0.010 &lt; 0.01 15 0.0030 0.1050 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.010 &lt; 0.005 &lt; 0.01 16 0.0020 0.0800 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.03 17 0.0035 0.1425 0.052 &lt;0.005 &lt;0.005 0.030 &lt;0.005 &lt;0.01 18 0.0038 0.1170 &lt;0.005 0.010 0.050 &lt;0.005 0.05 &lt;0.01 -22- 200911443 [Table 4-3] Composition (% by mass) Plating No. C Si Ti Μη Mo S o P Cu Copper 19 0.010 0.75 0.13 1.55 &lt;0.005 0.015 0.0055 0.006 0.25 There are 20 0.110 0.92 0.15 1.60 &lt;0.005 0.008 0.0026 0.010 0.19 There are 21 0.050 0.61 0.16 1.74 &lt;0.005 0.009 0.0010 0.015 0.25 There are 22 0.090 1.12 0.15 1.54 &lt;0.005 0.016 0.0034 0.011 0.28 There are 23 0.100 0.80 0.10 1.45 &lt;0.005 0.014 0.0060 0.008 0.15 There are 24 0.060 0.85 0.19 1.4 9 &lt;0.005 0.007 0.0095 0.007 0.01 There are 25 0.090 0.74 0.12 1.38 &lt;0.005 0.015 0.0015 0.016 0.18 There are 26 0.080 1.00 0.15 1.76 &lt;0.005 0.018 0.0045 0.010 0.20 There are 27 0.070 0.98 0.16 1.52 0.09 0.013 0.0010 0.012 0.21 There are 28 0.060 0.70 0.14 1.50 0.25 0.016 0.0070 0.009 0.20 There are 29 0.080 0.81 0.12 1.66 &lt;0.005 0.006 0.0029 0.007 0.22 There are 30 0.030 0.90 0.18 1.70 &lt;0.005 0.021 0.0015 0.016 0.23 There is a ratio of 31 0.020 0.86 0.11 1.44 &lt;0.005 0.012 0.0110 0.013 0.38 There are 32 0.050 0.83 0.15 1.65 &lt;0.005 0.008 0.0025 0.004 0.20 There are cases 33 0.070 0.94 0.16 1.60 &lt;0.005 0.009 0.0041 0.020 0.25 There are 34 0.050 0.77 0.18 1.74 0.005 0.010 0.0028 0.009 0.48 There are 35 0.060 0.88 0.16 1.70 &lt;0.005 0.009 0.0023 0.015 0.21 There are 36 0.030 0.69 0.17 1.52 &lt;0.005 0.012 0.0037 0.011 0.20 There are 37 0.025 0.80 0.14 1.66 &lt;0.005 0.010 0.0050 0.008 0.26 There are 38 0.095 0.90 0.13 1.70 &lt;0.005 0.015 0.0023 0.008 0.19 There are 39 0.040 0.70 0.12 1.41 &lt;0.005 0.015 0.0078 0.012 0.19 There are 40 0.080 0.72 0.15 1.70 0.060 0.018 0.0030 0.010 0.01 Μ 41 0.070 0.88 0.18 1.65 &lt;0.005 0.013 0.0058 0.006 0.05 Μ &gt; \ w 42 0.070 0.86 0.16 1.61 0.010 0.014 0.0015 0.013 0.17 There are 43 0.080 0.77 0.12 1.55 &lt;0.005 0.009 0.0022 0.010 0.20 There are 44 0.060 0.89 0.13 1.68 &lt;0.005 0.012 0.0019 0.010 0.18 There are 45 0.065 0.90 0.23 1.95 &lt;0.005 0.004 0.0150 0.012 0.25 There are 46 0.080 0.55 0.17 1.70 0.15 0.015 0.0025 0.025 &lt;0.001 Μ j \ \\ 47 0.050 0.95 0.20 1.80 &lt;;0.005 0.008 0.0035 0.012 0.25 There are 48 0.040 1.00 0.22 2.00 0.50 0.007 0.0035 0.012 0.20 Yes -23- 200911443 [Table 4-4]

No. Component composition (% by mass) / 1 ^ 〇 82 is the content per 10 kg of electrode (g) B C + 15 B Nb V A1 Cr Ni MoS2 19 0.0040 0.0700 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.05 20 0.0030 0.1550 &lt;0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.01 21 0.0022 0.0830 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.15 22 0.0050 0.1650 &lt; 0.005 &lt; 0.005 &lt;0.005 &lt; 0.005 &lt; 0.005 0.25 23 0.0020 0.1300 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.35 24 0.0035 0.1125 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.010 0.45 25 0.0035 0.1425 &lt;;0.005&lt;0.005&lt;0.005 0.050 &lt; 0.005 0.50 26 0.0044 0.1460 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.78 27 0.0018 0.0970 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.90 28 0.0048 0.1320 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.020 0.04 29 0.0025 0.1175 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.010 0.10 30 0.0030 0.0750 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt;0.005 &lt;0.01 to 31 0.0040 0.0800 &lt;0 .005 &lt;0.005 &lt;0.005 &lt;0.005 &lt;0.005 &lt;0.01 compared to 32 0.0026 0.0890 &lt;0.005 &lt;0.005 &lt;0.005 &lt;0.005 &lt;0.005 &lt;0.01 Example 33 0.0015 0.0925 &lt;0.005 &lt;0.005 &lt;; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.01 34 0.0070 0.1550 0.080 &lt; 0.005 0.080 &lt; 0.005 &lt; 0.005 &lt; 0.01 35 0.0013 0.0795 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.01 36 0.0075 0.1425 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.88 37 0.0022 0.0580 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.65 38 0.0070 0.2000 &lt; 0.005 0.050 &lt; 0.005 &lt; 0.005 0.150 0.15 39 0.0030 0.0850 0.100 &lt;0.005 &lt;0.005 &lt;0.005 &lt;0.005 0.26 40 0.0041 0.1415 0.010 0.100 &lt;0.005 &lt;0.005 &lt;0.005 0.15 41 0.0019 0.0985 &lt;0.005 &lt;0.005 0.100 0.150 &lt;0.005 0.11 42 0.0039 0.1285 &lt;0.005 &lt;0.005 &lt;0.005 0.600 &lt;0.005 &lt;0.01 43 0.0017 0.1055 0.070 0.050 0.100 0.020 0.600 0.05 44 0.0066 0.1590 &lt;0.005 0.006 &lt;0.005 &lt;0.005 &lt;0.005 1.11 45 &lt;0.0001 0.0650 &lt;0.005 &lt;0.005 &lt;0.005 0.150 0.010 &lt;0.01 46 0.0060 0.1700 &lt; 0.005 &lt; 0.005 0.01 0.010 0.010 &lt; 0.01 47 0.0050 0.1250 &lt; 0.005 &lt; 0.005 &lt; 0.005 0.020 0.010 &lt; 0.01 48 0.0100 0.1900 0.010 0.010 0.010 0.050 0.020 0.12 -24- 200911443 [Table 5-1]

No. Peeling rate mass % Slag amount (g) Tensile strength MPa Condition 1 Absorption energy J Condition 1 Tensile strength MPa Condition 2 Absorption energy J Condition 2 Arc stability Spillage amount (g) Crack 1 22〇8.4〇5650 132〇532〇166〇〇4.00 No 2 24〇7.2〇570〇135〇530〇167〇◎ 3.7〇无3 25〇6.0〇542〇142〇516〇175〇〇4.2〇无4 15〇11.8〇576〇 80〇548〇94〇〇4.6〇Μ 5 28〇5.4〇556〇85〇520〇98〇〇4.3〇Μ 6 29〇9.0〇525〇74〇496〇82〇◎ 3.5〇无实7 22〇8.3〇 600〇80〇575〇1000 ◎ 5.8〇无施8 16〇11.2〇551〇152〇536〇1770 〇3.3〇Μ Example 9 17〇6.0〇594〇153〇568〇1800 〇5.8〇No 10 20〇9.0〇 594〇91〇569〇1060 ◎ 3.7〇无11 18〇7.5〇586〇77〇565〇900 〇3.9〇无12 16〇11.00 551〇120〇522〇145〇◎ 3.5〇无13 18〇10.50 582〇71 〇555〇99〇◎ 5.00 No 14 21〇11.4〇532〇73〇5010 1〇4〇〇4.8〇无15 22 8.4〇566〇134〇532〇1500 〇4.4〇无16 32〇5.2〇531〇73〇494〇93〇◎ 5.1〇Μ Π 23〇8.00 549〇1190 525〇136〇〇4.6〇11* 18 29〇9.9 〇563〇74〇546〇1〇1〇〇5.5〇-25- 200911443 [Table 5-2]

No. Peeling rate mass % Slag halo (g) Tensile strength MPa Condition 1 Absorption energy J Condition 1 Tensile strength MPa Condition 2 Absorption energy J Condition 2 Arc stability Spillage amount (g) Crack 19 19〇9.50 5100 980 475x 122〇◎ 4.9〇Μ 20 22〇8.2〇608〇60x 5850 75〇X 6.5x There are 21 13x 7.5〇505〇86〇482x 1020 X 5.1〇ΤΓΓΓ •Μ 22 29〇12.2x 6010 54x 5740 63x X 5.3〇 1 j' 23 300 5.10 590〇77〇5550 910 X 6.4x and J \\\ 24 13x 13.3x 562〇110O 5370 138〇X 3.9〇| j' 25 25〇6.2〇504〇61x 480x 66x 〇5.6〇M 26 llx 12.6x 5780 1000 559〇119〇X 3.80 M /1 \\ than 27 18〇9.4〇602〇65x 5720 79〇◎ 4.3〇/nr τΐ 11. Compared with 28 16〇10.20 6360 42x 5980 71〇◎ 4.5〇 No case 29 12x 1〇.7〇542〇1150 5260 1300 X 3.6〇No 30 20〇9.1〇550〇58x 530〇60x X 5.0〇31 17〇12.5x 538〇66x 506〇73〇X 3.5〇32 12x 10.00 545〇126〇5150 145〇X 4.4〇Μ 33 18〇9.70 5530 63x 5240 59x X 5.2〇34 14x n.OO 580〇 800 551〇1〇1〇X 5.4〇35 22〇8.5〇503〇55x 484x 750〇4.1〇无36 21〇8.9〇558〇1420 530〇150〇◎ 4.0〇37 22〇9.6〇495〇85〇 480x 116〇◎ 4.6〇38 20〇9.1〇591〇82〇560〇1〇7〇◎ 5.8〇39 13x 13.2x 613〇56x 582〇80〇X 5.4〇and 40 13x 14.4x 624〇42x 598〇79 〇X 5.6〇无41 12x 14.9x 618〇62x 580〇85〇X 5.5〇无42 13x 13.7x 616〇60x 579〇80〇X 5.1〇Μ / 1 43 12x 12.2x 622〇69x 584〇96〇X 5.4 〇无44 14x 8.5〇557〇1030 525〇126〇X 9.8x no 45 5x 21.2x 645〇32x 591〇83〇X 3.8〇46 llx 9.2〇608〇55x 578〇59x X 4.3〇47 8x 18.4x 6470 40x 5870 88〇X 4.5〇无48 3x 23.3x 675〇20x 618〇80〇X 4.1〇有-26- 200911443 As shown in Table 5-1, the embodiment ο ο · 1~1 8 is an example of the present invention, Since the content of each component is within the range specified by the present invention, the slag removability, the amount of slag, the strength of the weld metal, the toughness, and the stability of the arc are stabilized. , Low melting spatter resistance, crack resistance and resistance was good welding can be obtained having excellent workability, excellent in weld metal mechanical properties. As shown in Table 5-2, No. 19 to 47 depart from the scope of the present invention. In Comparative Example No. 19, C was too small, and the strength of the welded metal was insufficient when the thick plate was welded. In Comparative Example No. 20, the C amount was excessive, and the weld metal was cracked at a high temperature. When the thin plate was welded, the toughness was lowered due to the excessive strength, and there were many spatters, and the arc stability was poor, and the shielding gas nozzle was easily clogged, so that the continuous weldability was deteriorated. . In Comparative Example No. 2, Si was too small, and the strength of the welded metal was insufficient when the thick plate was welded, and the slag peeling property was also poor, and the arc was unstable due to the slag hindrance, and the continuous weldability was deteriorated. In Comparative Example No. 22, the amount of Si was excessive, and the toughness of the weld metal was insufficient, and the excessive amount of slag was hindered, and the arc was unstable, and the continuous weldability was deteriorated. In Comparative Example No. 2, the amount of Ti was too small, and the amount of occurrence of the spatter was large, the arc stability was poor, and the shielding gas nozzle was easily clogged. Therefore, the continuous weldability was deteriorated. In Comparative Example No. 24, the amount of Ti was excessive, and the amount of slag was large, and the peeling property was also inferior. Excessive amount of slag is an obstacle and causes arc instability, and continuous weldability is deteriorated. In Comparative Example No. 25, the amount of Μη was too small. The tensile strength of the welded metal at the time of welding the thick plate and the toughness at any thickness were low. Comparative Example Ν 〇 . 2 6 Μ η η excess, the amount of slag is large, and the peelability is also poor. Excessive amount of slag is an obstacle and the arc is unstable, and the continuous weldability is deteriorated. Comparative Examples No. 27 and 28 have excessive Mo, and the toughness is deteriorated due to excessive strength when the thin plate is welded. Comparative Example 〇 2 · 2 9 S is too small 'The peeling property of melting is poor' Melt -27- 200911443 The slag becomes an obstacle and the arc is unstable, and the continuous weldability is deteriorated. Comparative Example No. 30 had excessive S, low toughness, and high temperature cracking. Although the slag removability is good, the deposits are granulated, and the thickness is increased to impair the stability of the arc. As a result, the continuous weldability is deteriorated. In Comparative Example No. 3 1 , the amount of slag increased. The stability of the arc is impaired, and the continuous weldability is deteriorated. Excessive inclusions in the weld metal occur and high temperature cracks occur. Comparative Example No. 3 2 When P is too small, the slag has poor peelability, and the slag is inhibited from causing arc instability, and the continuous weldability is deteriorated. In Comparative Example No. 3 3, P was excessive, the toughness was low, and high temperature cracks also occurred. Although the slag removability is good, the deposits are granulated and the thickness is increased to impair the stability of the arc. As a result, the continuous weldability is deteriorated. In Comparative Example No. 34, Cu was excessive, high-temperature cracks occurred, and slag removability was also poor, and slag was inhibited from causing arc instability and continuous weldability was deteriorated. In Comparative Example No. 35, B was insufficient, and the strength at the time of welding the thick plate and the toughness at the time of welding the thin plate were insufficient. In Comparative Example No. 36, B was excessive and high temperature cracking occurred. Comparative Example No. 3 7 Although the C and B respectively satisfy the predetermined ranges, the PCB = (C + 15xB) is insufficient. The strength at the time of fusion of the thick plates is insufficient. Comparative Example N 〇. 3 8 Although C and B respectively satisfy the prescribed range ', but 卩^ = (€+15\:8) is excessive, high temperature cracks occur. Comparative Example &gt;^〇.39~ N 〇 · 4 3 minutes S!J N b, V, A1, C r, N i excess The slag amount increasing force []' peeling property is lowered. The slag becomes a hindrance to cause arc instability, and the continuous weldability is deteriorated. When the thin plate is welded, the strength is excessive and the toughness is also lowered. In Comparative Example N 0.4 4, the amount of adhesion of MoS2 was excessive, and the supply of the conduit or the like was caused by the accumulation of MoS2 and clogging. The supply of the electrode was extremely unstable. As a result, the arc stability is impaired, and the slag distribution is not uniformized to cause an adverse effect, and the peeling property is lowered. The amount of spatter is also increased. -28- 200911443 Ν ο · 4 5 Its T i, Μ η, 0 excess, S too little. The increase in the amount of slag and the decrease in the peeling property are remarkable, and the slag becomes a hindrance to cause arc instability, and the continuous weldability is deteriorated. When the thin plate is welded, the excessive strength due to excessive Μη causes the toughness to also decrease. In Comparative Example No. 46, Si was too small, and Mo was excessive. Since Si is insufficient, the slag removability is poor, and the slag becomes an obstacle to cause arc instability, and continuous weldability is deteriorated. Because of the excess of P, high temperature cracks occur. In addition, since the excess of Μ is excessive, the strength of the thin plate is excessively welded, so the toughness of the thin plate and the thick plate are low. In the comparative example Νο.47, Ti and Μη are excessive. The increase in the amount of slag and the decrease in the peeling property are remarkable, and the slag becomes an obstacle to cause the arc to be unstable, and the continuous weldability is deteriorated. When the thin plate is welded, the excessive strength due to excessive Μη causes the toughness to also decrease. In Comparative Example No. 48, Ti, Mn, Mo, and yttrium were excessive. The increase in the amount of slag and the decrease in the peeling property are remarkable, and the slag becomes an obstacle to cause arc instability and deterioration of continuous weldability. When the thin plate is welded, the toughness is also lowered due to excessive strength due to excessive Mn, Mo, and B. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a graph showing the range of C and Β of the electrode in the present invention. Figs. 2(a) to 2(c) are diagrams showing the shape of the welded test body and the shape of the groove. The figure is a photograph of the appearance of the welded joint, (a) shows a portion where the slag is naturally peeled off, and (b) shows a portion where the slag is attached. Fig. 4 is a view showing the position at which the welded metal tensile test piece is taken. Fig. 5 is a view showing the position at which the welded metal Charpy impact test piece is taken. -29- 200911443 [Main component symbol description 1 : Partition 2 : Steel pipe 3 : Backing plate 4 : Welding torch

Claims (1)

200911443 X. Patent application scope 1. A solid electrode for carbon dioxide gas shielded arc welding 'system 0 has θ 0/ , Μη c: 0.020 ～ 0.100 mass. /〇, Si: 0.65 to 1·1% by mass, : 1.40 to 1.74% by mass, Ρ: 0·005 to 0.018% by mass, S: 〇. Ί 5 to 0.020% by mass, Ti: 0.11 to 0.18% by mass, Β: 0·001 0.0073 Quality. /. , c+15xB: 0.0600 to 0.1990% by mass, · n 4 5皙%%0_08% by mass, 〇: 0.0100% by mass or less, Cu · 〇_45 Å or less, and the remainder is F e and unavoidable impurities. _ 2 · As described in the scope of application of the patent scope, the carbon dioxide gas shield is a solid electrode for arc welding, wherein the content of Mo is 0.01 mass ° ° ° 〇 3. As described in the scope of claim H 1 carbon dioxide gas cover Cr and 〇·5 of A1 〇 〇 % 以下 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 0 quality. The following N1 13 kg constitutes one to more than one of the group. 4. For the solid electrode for carbon dioxide gas shielding arc welding according to any one of the items 1 to 3 of the patent application, wherein M〇S2 ° exists in the ratio of H 0.0 1 to Lg per 10 kg of electrode on the surface of the electrode - 31 -