WO2010117074A1 - サブマージアーク溶接用溶融型高塩基性フラックス - Google Patents
サブマージアーク溶接用溶融型高塩基性フラックス Download PDFInfo
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- WO2010117074A1 WO2010117074A1 PCT/JP2010/056491 JP2010056491W WO2010117074A1 WO 2010117074 A1 WO2010117074 A1 WO 2010117074A1 JP 2010056491 W JP2010056491 W JP 2010056491W WO 2010117074 A1 WO2010117074 A1 WO 2010117074A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
- B23K35/3601—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with inorganic compounds as principal constituents
- B23K35/3602—Carbonates, basic oxides or hydroxides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
- B23K35/3601—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with inorganic compounds as principal constituents
- B23K35/3603—Halide salts
- B23K35/3605—Fluorides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
- B23K35/362—Selection of compositions of fluxes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/18—Submerged-arc welding
Definitions
- the present invention relates to a molten flux for submerged arc welding used for pipe making welding of UO steel pipes for pipelines having a base metal tensile strength of 800 MPa to 1200 MPa, which requires strength for transporting petroleum, natural gas, and the like and low temperature toughness.
- a UO steel pipe is manufactured by forming a steel plate into a cylindrical shape using a C press, a U press and an O press, and then joining the butted portions of the plates by welding.
- Submerged arc welding is often used as the welding method used for this joining in consideration of quality and productivity.
- Submerged arc welding is a method of welding by generating an arc in a flux using a flux and a welding wire.
- the submerged arc welded portion in the UO steel pipe is usually a two-layer welding of one layer from the inner surface of the steel pipe and one layer from the outer surface of the steel pipe.
- the weld metal produced by the flux and the welding wire is required to have strength and toughness that are commensurate with the base material. At the same time, a weld metal having a good weld bead shape and no defects is required. In order to control these qualities, the composition of the flux and the components of the welding wire are important, and various technical developments have been made.
- the chemical composition of the base metal of the large-diameter pipe for use in sour-resistant environments and the weld metal is defined. Furthermore, in the weld metal, the ratio of the weld metal component is defined to obtain a seam weld metal for UO steel pipes excellent in low temperature toughness.
- a low oxygen flux is used so that the oxygen content of the weld metal is 0.015% to 0.025%.
- the flux used here is a low oxygen flux disclosed in Patent Document 3.
- SiO 2 is reduced to a low level of 5.4% to reduce oxygen.
- the low-temperature toughness of the weld metal is secured by limiting the components of the welding wire to be used and the basicity of the flux to be used or the chemical component of the base material.
- the flux used here is a CaO—CaF 2 —AiO 2 type flux, and the basicity is set to 0.4 or more in order to make the oxygen content of the weld metal 0.035% or less necessary for ensuring toughness. ing.
- the main composition of the flux used in the examples is SiO 2 : 25% to 29%, MnO: 2% to 5%, TiO 2 : 5% to 7%, Al 2 O 3 : 5%, CaO: 18% to 33%, MgO: 4% to 9%, CaF 2 : 17% to 26%.
- Patent Document 5 The invention described in Patent Document 5 is intended to ensure toughness by prescribing multi-layer welding, particularly for application to welding of thick-walled large-diameter steel pipes, and defining the components of the welding flux. Specifically, in order to control the hardenability of the weld metal and ensure the low temperature toughness of the weld metal, the components of the flux are optimized in the first layer, the second layer, and the third layer and thereafter.
- Patent Document 6 discloses a flux for submerged arc welding applied to a weld metal premised on post-weld heat treatment.
- a flux component is defined.
- Si in the flux the lower limit of Mn in terms of securing deoxidation, the upper limit by the limit in terms of low-temperature toughness ensured, and an appropriate amount of CaF 2, thereby reducing the amount of oxygen in the weld metal.
- JP 58-055597 Japanese Patent Laid-Open No. 03-285770 JP-A-60-191691 JP 05-000375 A Japanese Patent Laid-Open No. 06-1555076 JP 08-257789 A JP 2006-305604 A JP 2007-90399 A
- the flux having the composition disclosed in the example of Patent Document 1 cannot be applied to a high-strength weld metal having a high cold cracking sensitivity.
- a problem of cold cracking occurs after welding.
- top slag in occurs in welding using the flux disclosed in Patent Document 4 and a high strength weld metal.
- the flux having the composition disclosed in the example of Patent Document 5 cannot be applied to a high-strength weld metal having a high cold cracking sensitivity.
- Patent Document 6 The invention described in Patent Document 6 is easy to secure toughness due to the reheating effect by subsequent welding, but cannot be applied to inner and outer surface single layer welding where the reheating effect cannot be expected. Furthermore, the invention described in this document is liable to cause cold cracking after welding and is not suitable for high-strength weld metal.
- Patent Document 7 proposes a fusion flux for submerged arc welding that can be welded sideways with a large current and that can be applied to any orientation of sideways, horizontal fillets, and downwards.
- a fusion flux for submerged arc welding that can be welded sideways with a large current and that can be applied to any orientation of sideways, horizontal fillets, and downwards.
- Patent Document 8 proposes to improve low-temperature toughness in a melt-type flux for submerged arc welding used when manufacturing a high-strength weld metal corresponding to a high-strength steel sheet having a strength of 800 MPa to 1200 MPa.
- application in more severe environments such as UO steel pipes is required.
- the present invention is based on such a background, and even when a high-strength weld metal is created, a low-temperature crack is unlikely to occur after welding, and a sound high-toughness weld metal without top slag in is obtained. It is an object of the present invention to provide a molten flux for high basic submerged arc welding.
- the inventors of the present invention have studied a flux for fusion-type submerged arc welding that can obtain a high-strength weld metal that is less prone to low-temperature cracking after welding and that has no top slag in and has excellent low-temperature toughness as described above. .
- the strength of the weld metal can be improved by using a wire added with an alloy element such as Ni, Cr or Mo as a welding wire used in submerged arc welding.
- an alloy element such as Ni, Cr or Mo
- the oxygen content of the weld metal is important as shown in FIG. 2, when the oxygen content in the weld metal is in the range of about 0.018% to 0.035%, the impact absorption energy at ⁇ 30 ° C. is 100 J or more. Toughness has been found to be obtained.
- the structure changes from an acicular ferrite structure to a bainite structure.
- the amount of oxygen in the weld metal plays an important role in the toughness of the weld metal.
- the structure becomes a martensite structure, and it becomes difficult to ensure toughness only by controlling the amount of oxygen.
- the top slag-in occurs as shown below. That is, in order to obtain the strength of the weld metal, the alloy element described above is added to the welding wire used for the submerged arc welding. Change the interfacial tension between the metal and the molten flux. For this reason, it is considered that the slag melted at the time of welding is not easily levitated and separated, and slag-in remains inside the weld metal at the top of the bead, which is the final solidified portion.
- the inventors examined in detail the tendency of the top slag-in generation by arranging the basicity B of the flux calculated by the following formula (1) according to the tensile strength of the weld metal.
- B 6.05N [CaO] + 4.0N [MgO] + 5.1N [CaF 2 ] + 4.8N [MnO] ⁇ 0.2N [Al 2 O 3 ] ⁇ 6.31N [SiO 2 ] (1)
- N [k] represents the mole fraction of component k.
- top slag-in is generated when the SiO 2 content of the flux exceeds 20%.
- the amount of CaF 2 also affects the tendency of the top slag in, and as shown in FIG. 6, it is found that the top slag in is generated when the CaF 2 content in the flux is less than 30% in the high strength weld metal. did.
- the basicity B obtained by the formula (1), the SiO 2 amount of the flux, and the CaF 2 amount is necessary to adjust the basicity B obtained by the formula (1), the SiO 2 amount of the flux, and the CaF 2 amount. Furthermore, the basicity B, the amount of SiO 2 or the amount of CaF 2 in the flux is satisfied within a range in which the top slag in can be avoided, and the oxygen amount in the weld metal is controlled to 0.018% or more and 0.035% or less. There is a need to.
- MnO can increase the oxygen content of the weld metal without adding top slag in by adding an appropriate amount to the flux.
- a basicity B of 1.2 or more and an oxygen amount of 0.018% or more can be stably obtained.
- FIGS. 7, 8 and 9 show the measurement of the loss of mass after the flux was kept for 48 hours in an environment of temperature 25 ° C. and humidity 60% and then dried at 500 ° C. for 24 hours. 7, 8, and 9, the reduced mass is the moisture adsorbed on the flux, and the ratio of the reduced mass to the original mass is taken as the moisture adsorption amount.
- FIG. 7 shows the relationship between the amount of Al 2 O 3 in the flux and the amount of moisture adsorbed.
- FIG. 8 shows the relationship between the amount of SiO 2 in the flux and the amount of moisture adsorbed.
- FIG. 9 shows the relationship between the basicity B of the flux and the amount of moisture adsorbed.
- the basicity B shown in FIG. 9 is a value calculated by the above equation (1).
- the amount of moisture in the flux increases the diffusible hydrogen of the weld metal and makes it easier for cold cracking to occur after welding. Therefore, in the flux used for welding high-strength steel, the amount of Al 2 O 3 in the flux needs to be more than 15%, the amount of SiO 2 should be 10% or more, and the basicity B should be 3.2 or less.
- the gist of the present invention is as follows.
- CaO 5.0% or more, 25.0% or less
- MgO 1.0% or more, 5.0% or less
- Al 2 O 3 more than 15.0%, 30.0% or less
- CaF 2 30.0% or more
- SiO 2 10.0% or more, 20.0% or less
- MnO 0.5% or more and 15.0% or less
- the balance is an inevitable impurity, and obtained by the formula (1)
- N [k] represents the mole fraction of component k.
- melt type high basic flux for submerged arc welding of the present invention it is difficult to generate low temperature cracking after welding, and a high strength weld metal excellent in low temperature toughness without top slag in can be obtained.
- Patent Document 1 is directed to a steel that does not contain Ni, Mo, Cr, or the like, for example, a low-strength steel having a base metal tensile strength of 500 MPa to 600 MPa as shown in the examples. . Therefore, in patent document 1, generation
- the flux having the composition disclosed in the example of Patent Document 1 has a problem that the amount of Al 2 O 3 is small, the flux becomes crystalline, and moisture is adsorbed. Not applicable to metals.
- the weld metal is a low-C, 700 MPa-class strength weld metal with a low content of Mo, Ni, or Cr as shown in the examples, and this is used as it is.
- problems arise when applied to weld metal with higher strength.
- the flux of the invention described in Patent Document 3 used in the invention described in Patent Document 2 there is a problem that the amount of SiO 2 is small and the flux becomes crystalline, resulting in a large amount of moisture adsorption.
- the flux described in Patent Document 3 does not contain Ni, Cr or Mo as described in Table 3 of the Examples of Patent Document 3, for example, the base material tensile strength is 500 MPa to 600 MPa. It is a flux to be applied to low-grade steel of the grade. Therefore, the flux described in Patent Document 3 does not create a high-strength weld metal, and is not premised on application to high-strength steel having a base metal tensile strength of 800 MPa to 1200 MPa.
- Patent Document 4 The scope of application of the invention described in Patent Document 4 is the X65 class as shown in the examples, and is intended for low-strength weld metals having a weld metal strength of, for example, about 600 MPa to 700 MPa. For this reason, in welding using the flux disclosed in Patent Document 4 and a high-strength weld metal, there is a problem that top slag-in occurs because the amount of SiO 2 is large and the amount of CaF 2 is small.
- the invention described in Patent Document 5 targets a low-strength steel pipe, and the flux having the composition disclosed in the examples has a problem that the flux becomes crystalline and moisture is often adsorbed. Therefore, it cannot be applied to a high-strength weld metal that is particularly sensitive to cold cracking.
- the flux disclosed in Patent Document 6 is applied to welding based on post-weld heat treatment, and is based on multilayer welding as disclosed in the examples. For this reason, the invention described in the same document is easy to secure toughness due to the reheating effect by the subsequent welding, and cannot be applied to the inner and outer surface single layer welding which is not expected to have the reheating effect which is assumed in the present invention. Furthermore, the invention described in this document is unsuitable for high-strength weld metals because the amount of SiO 2 is small and the crystallization of the flux proceeds and the amount of moisture adsorption increases. Moreover, the flux described in Patent Document 6 is a bond-type flux, and is a different type of flux having a different manufacturing method from the melt-type flux of the present invention.
- the melt shape flux for submerged arc welding of the present invention is used, so that the bead shape is good and the top slag in is called A weld bead having no defects inside the weld bead can be obtained.
- the oxygen content of the weld metal can be optimized even with a flux composition that does not generate top slag in, and a weld metal with excellent low temperature toughness can be obtained. This makes it possible to easily produce a sound high-strength weld metal.
- FIG. 1 It is a schematic diagram of a top slag in. It is a figure which shows the relationship between the oxygen content and toughness of a weld metal. It is a figure which shows the relationship between the basicity B of a flux, the tensile strength of a weld metal, and the generation
- CaO 5.0% or more and 25.0% or less
- CaO affects the weld bead shape of the weld metal. If it is less than 5.0%, the softening and melting temperature becomes high, resulting in poor appearance of the weld bead surface such as the occurrence of fluttering due to the inhibition of the diffusion of the molten gas. On the other hand, if it is excessive, the viscosity is high and the excess is high. In addition, the slag removability is reduced. Therefore, the upper limit was made 25% or less.
- CaO is a component that affects basicity B. If it is less than 5.0%, the basicity B becomes small, and the generation of the top slag in is promoted. If it exceeds 25.0%, the basicity B becomes high, the flux becomes crystalline, and the hydrogen cracking sensitivity becomes high.
- MgO 1.0% or more and 5.0% or less
- MgO affects the viscosity of the molten slag. If it is less than 1.0%, the viscosity of the slag is too low and fluttering defects occur on the surface. On the other hand, if it exceeds 5.0%, the viscosity of the slag becomes high and undercut occurs.
- Al 2 O 3 is one of the important components as a slag forming component, it is added as a constituent component of the flux. However, if it is 15.0% or less, as shown in FIG. 7, the tendency of the crystalline flux becomes strong and it becomes easy to absorb moisture. As a result, the amount of hydrogen in the weld metal increases and the cold cracking susceptibility increases. On the other hand, the addition of Al 2 O 3 has the effect of lowering the basicity B. Therefore, when excessively added, the generation of top slag in is promoted. Al 2 O 3 also affects the bead shape. When added in excess, undercuts and horse-like projections are formed on the top of the weld bead. From these viewpoints, the upper limit was made 30.0% or less.
- CaF 2 is a component that affects the generation tendency of top slag in aside from basicity B.
- the lower limit was made 30.0% or more.
- the upper limit was made 50.0% or less.
- CaF 2 lowers the flux viscosity and softening melting temperature, so that the weld bead is prevented from becoming an excessively convex shape, and the weld bead surface is also smoothed. In order to obtain this effect, it is necessary to add 30.0% or more, preferably more than 35%, more preferably more than 37%.
- SiO 2 10.0% or more and 20.0% or less
- the upper limit was made 20.0% or less.
- the flux becomes crystalline and it becomes easy to absorb moisture. Therefore, the amount of hydrogen in the weld metal is increased, and as a result, the sensitivity to cold cracking of the weld metal is increased. Therefore, the lower limit is made 10.0% or more.
- SiO 2 improves the familiarity with the base material at the toe part, such as improving the contact angle with the base material at the toe part and reducing sticking of slag at the toe part. Furthermore, it has the effect of smoothing the weld bead surface and preventing it from becoming an extremely convex bead, thereby improving the bead shape. In order to obtain this effect, 10.0% or more is necessary.
- FIG. 11 shows the relationship between the basicity B of the flux added with MnO and the amount of oxygen in the weld metal. As shown in this figure, by adding an appropriate amount of MnO, it is possible to stably obtain a basicity B of 1.2 or more shown in FIG. 3 and an oxygen amount of 0.018% or more. In order to obtain this effect, addition of 0.5% or more is necessary.
- the upper limit was made 15.0% or less.
- MnO is added exceeding 15.0%, when the basicity is low, the amount of oxygen in the weld metal becomes excessive and the toughness may be lowered. Therefore, the upper limit was made 15.0% or less.
- N [k] represents the mole fraction of component k. If the relationship between the basicity B and the presence or absence of the top slag-in is arranged, as shown in FIG. 3, the top slag-in is not generated when the basicity B is 1.2 or more. On the other hand, there is no upper limit of basicity B from the viewpoint of the top slag-in, but as shown in FIG. .
- the upper limit of the basicity B is set to 3.2 or less.
- the lower limit is set to 1.2 or more.
- the base material tensile strength is set to 800 MPa to 1200 MPa, preferably more than 980 MPa to 1200 MPa.
- the base material tensile strength is less than 800 MPa, the strength of the UO steel pipe in the field to which the present invention is applied is low, and therefore the problem of the top slag in does not occur.
- the base material tensile strength exceeds 1200 MPa, sufficient toughness may not be ensured.
- the chemical composition of the base material used is, in mass%, C: 0.03% or more, 0.12% or less, Si: 0.5% or less, Mn: 1.2% or more, 2 0.5% or less, Ni: 2.0% or less, Mo: 0.6% or less, Ti: 0.030% or less, Al: 0.07% or less, P: 0.015% or less, S: 0.003 % Or less, Nb: 0.0015% or more, 0.1% or less, and N: 0.008% or less.
- the chemical composition of the welding wire used is, in terms of weld metal strength, toughness or wire manufacturability, in mass%, C: 0.02% or more, 0.15% or less, Si: 0.5% or less. Mn: 1.0% or more, 2.5% or less, Ni: 10.0% or less, Mo: 4.0% or less, Ti: 0.030% or less, O: 0.008% or less, Al: 0 0.05% or less, P: 0.015% or less, S: 0.01% or less, and N: 0.008% or less.
- Total of any one or two of Li 2 O and K 2 O 0.2% or more and 5.0% or less
- the total of any one or two of Li 2 O and K 2 O is preferably 0.2% or more and 5.0% or less, more preferably more than 2% and 5.0% or less.
- MnO increases the arc re-ignition voltage. Therefore, there is a tendency that the weld pool surface is vibrated with a voltage increased when the arc is re-ignited during welding, and as a result, the ripple lines, which are wavy patterns on the weld bead surface, are uneven.
- Li 2 O and K 2 O have the effect of calming this and eliminating irregularities in the ripple line. In order to obtain this effect, 0.2% or more in total of any one or two of Li 2 O and K 2 O is required. On the other hand, if added over 5.0%, the slag peelability is reduced and slag sticking occurs. Therefore, the upper limit was made 5.0% or less.
- B 2 O 3 may be added in an amount of about 0.05% to 2.0%, but this has no influence on the effect of avoiding the top slag in which is the object of the present invention.
- V-shaped groove 12 is a V-shaped groove in cross-sectional view provided between the base materials to be welded in the example and the comparative example, and as shown in FIG.
- the angle formed by the V-shaped groove is 80 °.
- the flux was stored for 24 hours in an environment of 20 ° C. and 60% humidity, and then dried for 2 hours in a furnace at 150 ° C. before use.
- FIG. 13 is a drawing for explaining the sampling procedure of a test piece
- FIG. 13 (a) is a cross-sectional view of an impact test piece taken from a welded plate as seen from the weld line direction
- FIG. 13B is a plan view showing a tensile test piece taken from a welded plate
- FIG. 13C is a cross section of the tensile test piece taken from a welded plate as seen from the weld line direction.
- the impact test piece was taken from the center of the weld metal in the plate thickness direction, and was processed so that the notch depth direction was the weld line direction.
- the impact test was repeated three times at a test temperature of ⁇ 30 ° C.
- the toughness of the weld metal was evaluated using the average value of the impact test results repeated three times and the minimum value of the three impact test results.
- the round bar type tensile test piece is taken from the center of the weld metal in the plate thickness direction so that the axial direction of the test piece becomes the weld line direction. processed.
- the tensile test was repeated once and performed at room temperature.
- the internal defect of the weld metal bead was investigated by conducting a radiation nondestructive inspection over the entire weld line with a total thickness of 20 mm. Thereafter, the plate thickness was reduced from the back surface opposite to the weld surface to a thickness of 7 mm, and then the radiation nondestructive inspection was performed again to investigate the presence of top slag in.
- the bead shape was evaluated by the shape of the overfill of the bead, the undercut, the unevenness of the bead surface, the presence or absence of a pock mark, the state of the wave called ripple generated on the weld bead surface, and the cross-sectional macro observation.
- the surface condition was judged to include the possibility of being recognized as a defect because it may be recognized as a defect in the radiation transmission test if the unevenness is severe.
- the oxygen concentration in the weld metal was determined in accordance with the oxygen determination method for metal materials described in JIS Z2613.
- Table 5 shows examples and comparative examples of the present invention according to claim 1.
- the other is impurities such as alkali metal oxides, P, and S, which are inevitably mixed from B 2 O 3 , CaCO 3, or raw materials.
- Example 4 and Example 10 B 2 O 3 is added for the purpose of adjusting the B amount of the weld metal to improve the hardenability of the weld metal, but the top slag in of the present invention is generated. It has no effect on the preventive effect.
- CaCO 3 is added for the purpose of preventing an increase in nitrogen in the weld metal, but this has no influence on the effect of preventing the top slag in the present invention. Absent.
- Comparative Examples 1 and 2 components other than MnO and basicity B are within the scope of the present invention, but MnO is less than the scope of the present invention. Therefore, although the basicity B is high and no top slag-in is generated, the oxygen content is small, the toughness of the weld metal is low, and the average value of Charpy absorbed energy exceeds 100 J, but the individual value (minimum value) exceeds 100 J. Below data is obtained. Comparative Examples 1 and 2 show that, by setting the MnO addition range to 0.5% or more, a stable reduction in toughness can be critically prevented by stably obtaining an oxygen amount.
- Comparative Examples 3 and 4 components other than MnO and basicity B are within the scope of the present invention, but MnO is added beyond the scope of the present invention. Therefore, slag in is generated at the bottom. Moreover, in the comparative example 4, oxygen also becomes excess and the toughness (Charpy absorption energy) of a weld metal is less than 100J in each value. Comparative Examples 3 and 4 show that the occurrence of slag in at the bottom can be critically prevented by setting the MnO addition range to 15.0% or less.
- Comparative Example 6 the amount of SiO 2 in the flux is less than the range of the present invention, and the basicity B exceeds the range of the present invention. For this reason, moisture is absorbed during storage, and low temperature cracking occurs after welding despite the fact that the flux is kept dry before use. In order to prevent cold cracking, it was necessary to dry the flux sufficiently at high temperature. Further, since a small SiO 2 in the flux, sticking of slag generated in the toe portion, familiar with the base material is lowered.
- Comparative Example 7 the amount of CaO in the flux is less than the range of the present invention. Therefore, flapping irregularities are generated on the bead surface, and the bead appearance is deteriorated. Further, since a small SiO 2 in the flux, sticking of slag generated in the toe portion, familiar with the base material is lowered. In Comparative Example 8, since the amount of CaF 2 in the flux exceeds the range of the present invention, the arc becomes unstable, and a fluttering pattern called a pock mark is generated on the bead surface.
- Comparative Example 9 As in Comparative Example 8, since the amount of CaF 2 in the flux exceeds the range of the present invention, the arc becomes unstable and a fluttering pattern called a pock mark is generated on the bead surface. Further, since a small SiO 2 in the flux, sticking of slag generated in the toe portion, familiar with the base material is lowered. Furthermore, similarly, since the amount of SiO 2 in the flux is less than the range of the present invention, drying is insufficient under the flux drying conditions in this experiment, and low-temperature cracking occurs after welding.
- the amount of SiO 2 in the flux exceeds the range of the present invention. Therefore, the top slag in is generated.
- the amount of CaF 2 in the flux is less than the range of the present invention. Therefore, the top slag in is generated.
- the weld metal has a martensite structure, a strength of 1250 MPa or more, and low toughness.
- the amount of MgO in the flux exceeds the range of the present invention. Therefore, the viscosity of slag is increased and undercut occurs. Moreover, since the amount of Al 2 O 3 is less than the range of the present invention, the flux becomes crystalline and is easy to absorb moisture. Therefore, drying is insufficient under the flux drying conditions in this experiment, and low temperature cracking occurs after welding. In Comparative Example 15, the amount of MgO in the flux is less than the range of the present invention. Therefore, flapping defects are generated on the surface of the weld bead.
- Comparative Examples 16 to 18 are experimental examples using a base material with low strength.
- the welding material combination also has a low strength of about 740 MPa. Therefore, in Comparative Example 16, SiO 2 exceeds the range of the present invention, but no top slag in is generated. In Comparative Example 17, CaF 2 is less than the range of the present invention, but no top slag in is generated. Further, in Comparative Example 18, the amount of Al 2 O 3 exceeds the range of the present invention, and therefore the extra shape of the bead is a convex bead having a horse's back shape.
- Table 6 shows examples and comparative examples according to claim 2.
- the other flux components in Table 6 are impurities such as alkali metal oxides, P, and S, which are inevitably mixed from B 2 O 3 , CaCO 3, or raw materials as in Table 5.
- the flux having the components in the range of claim 2 of the present invention has good toughness (Charpy absorbed energy) at -30 ° C, and no top slag in is generated. . Furthermore, since appropriate amounts of Li 2 O and K 2 O are added, the bead surface ripple lines are uniform and have a beautiful bead surface.
- B 2 O 3 is added for the purpose of adjusting the B amount of the weld metal to improve the hardenability of the weld metal. It has no effect on the preventive effect.
- CaCO 3 is added for the purpose of preventing an increase in nitrogen in the weld metal, but this does not affect the effect of preventing the occurrence of top slag in the present invention.
- Example 1 Using three-electrode submerged arc welding, wires having different compositions and strength levels shown in Table 2 were combined under the welding conditions shown in Table 1, and a plate thickness of 20 mm and a length of 1500 mm having the chemical composition and tensile strength shown in Table 3 were used. In the base material, a groove having a cross-sectional shape shown in FIG. 1-No. Welding was performed using 14 fluxes.
- the weld metal thus obtained was measured for toughness (Charpy absorbed energy), tensile strength and oxygen content at ⁇ 30 ° C. in the same manner as described above, and the weld metal had a tensile strength of 800 MPa or more and 1200 MPa or less.
- the relationship between oxygen content and toughness in the weld metal in some cases was investigated. The result is shown in FIG. As shown in FIG. 2, when the oxygen content of the weld metal is in the range of 0.018% or more and 0.035% or less, good toughness with an impact absorption energy at ⁇ 30 ° C. of 100 J or more can be obtained. found.
- Example 2 Using three-electrode submerged arc welding, wires having different compositions and strength levels shown in Table 2 were combined under the welding conditions shown in Table 1, and a plate thickness of 20 mm and a length of 1500 mm having the chemical composition and tensile strength shown in Table 3 were used. In the base material, the groove having the cross-sectional shape shown in FIG. 15-No. Welding was performed using 24 fluxes.
- the tensile strength of the weld metal thus obtained was measured in the same manner as the evaluation method described above, and the relationship between the tensile strength of the weld metal, the basicity B of the flux, and the top slag in was examined. The result is shown in FIG. As shown in FIG. 3, in the weld metal having a tensile strength of 800 MPa or more, it was found that the basicity B was 1.2 or more and no top slag in was generated.
- Example 3 Using 3 electrode submerged arc welding, wires having different compositions and strength levels shown in Table 2 under the welding conditions shown in Table 1, combined with a chemical composition and tensile strength shown in Table 3, a thickness of 20 mm and a length. A groove having the cross-sectional shape shown in FIG. 25-No. Welding was performed using 79 fluxes.
- the oxygen content of the weld metal thus obtained was measured in the same manner as the evaluation method described above, and the relationship between the oxygen content of the weld metal and the basicity B of the flux was examined. The result is shown in FIG. As shown in FIG. 4, it has been found that the oxygen content of the weld metal and the basicity B of the flux have a correlation.
- Example 4 Using 3 electrode submerged arc welding, wires having different compositions and strength levels shown in Table 2 under the welding conditions shown in Table 1, combined with a chemical composition and tensile strength shown in Table 3, a thickness of 20 mm and a length. A groove having a cross-sectional shape shown in FIG. 80-No. Welding was performed using 89 flux.
- FIG. 5 is a graph showing the relationship between the amount of SiO 2 in the flux, the tensile strength of the weld metal, and the tendency to generate top slag in.
- the top slag-in occurs when the amount of SiO 2 in the flux exceeds 20%.
- Example 5 Using 3 electrode submerged arc welding, wires having different compositions and strength levels shown in Table 2 under the welding conditions shown in Table 1, combined with a chemical composition and tensile strength shown in Table 3, a thickness of 20 mm and a length. A groove having the cross-sectional shape shown in FIG. 90 ⁇ No. Welding was performed using 97 flux.
- FIG. 6 is a graph showing the relationship between the amount of CaF 2 in the flux, the tensile strength of the weld metal, and the tendency to generate top slag in.
- the top slag-in is generated when the amount of CaF 2 in the flux is less than 30%.
- FIG. 7 is a graph showing the relationship between the amount of Al 2 O 3 in the flux and the amount of moisture adsorption
- FIG. 8 is a graph showing the relationship between the amount of SiO 2 in the flux and the amount of moisture adsorption. As shown in FIG. 7, the amount of adsorbed water increases rapidly when the amount of Al 2 O 3 in the flux is 15% or less.
- FIG. 8 is a graph showing the relationship between the amount of SiO 2 flux and the amount of moisture adsorbed. As shown in FIG. 8, the amount of adsorbed water increases rapidly when the amount of SiO 2 in the flux is less than 10%.
- FIG. 9 is a graph showing the relationship between the basicity B of the flux and the amount of moisture adsorbed. As shown in FIG. 9, even when the basicity B exceeds 3.2, the amount of adsorbed water increases rapidly.
- Example 9 Using 3 electrode submerged arc welding, wires having different compositions and strength levels shown in Table 2 under the welding conditions shown in Table 1, combined with a chemical composition and tensile strength shown in Table 3, a thickness of 20 mm and a length. A groove having the cross-sectional shape shown in FIG. 121 ⁇ No. Welding was performed using 139 flux.
- the oxygen content of the weld metal thus obtained was measured in the same manner as the evaluation method described above, and the relationship between the oxygen content of the weld metal and the basicity B of the flux was examined. The result is shown in FIG. As shown in FIG. 11, by adding 0.5% or more of MnO, a weld metal having a basicity B of 1.2 or more and an oxygen amount of 0.018% or more can be obtained stably.
- the top slag in addition to the good bead shape by using the molten flux for submerged arc welding of the present invention.
- a weld bead having no defects inside the weld bead can be obtained.
- the oxygen content of the weld metal can be optimized even with a flux composition that does not generate top slag in the component system of the present invention, and it is easy to obtain a weld metal having excellent low temperature toughness, contributing to the industry. However, it is very big.
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Abstract
Description
サブマージアーク溶接とは、フラックスと溶接ワイヤを用いてフラックス中でアークを発生させて溶接する方法である。UO鋼管でのサブマージアーク溶接部は、通常鋼管の内面から1層、鋼管の外面から1層の合計2層溶接である。フラックスおよび溶接ワイヤにより作製される溶接金属には、母材に見合った強度と靭性が要求される。また、同時に良好な溶接ビード形状や欠陥の無い溶接金属が要求される。
これらの品質の制御には、フラックスの組成や溶接ワイヤの成分が重要であり、従来から、色々と技術開発が行われてきた。
特許文献2に記載の発明で使用されている特許文献3に記載の発明のフラックスでは、溶接後に低温割れの問題が発生する。
特許文献4で開示されているフラックスを用い、かつ、高強度の溶接金属とする溶接では、頂部スラグインが発生するという問題がある。
特許文献5の実施例で開示されている組成のフラックスでは、低温割れ感受性の高い高強度溶接金属には適用できない。
引張強度800MPa以上1200MPa以下の溶接金属では、組織がアシキュラーフェライト組織からベイナイト組織となる。これらの組織では、溶接金属中の酸素量が溶接金属の靭性に重要な働きをしている。一方、1200MPa超の溶接金属では、組織がマルテンサイト組織となり、酸素量の制御のみでは靭性の確保が困難となる。
B=6.05N[CaO]+4.0N[MgO]+5.1N[CaF2]+4.8N[MnO]−0.2N[Al2O3]−6.31N[SiO2]・・・(1)
ここで、N[k]は成分kのモル分率を表す。
これは、フラックス中のAl2O3が15%以下か、あるいはSiO2が10%未満か、あるいは塩基度Bが3.2超になると、フラックスの表面が結晶質になり水分を吸着しやすくなるためである。高強度鋼の溶接においてはフラックス中の水分量は、溶接金属の拡散性水素を増加させて溶接後に低温割れを発生し易くする。そのため、高強度鋼の溶接に使用するフラックスにおいては、フラックス中のAl2O3量は15%超、SiO2量は10%以上、また塩基度Bは3.2以下とする必要がある。
(1)母材引張強度が800MPa~1200MPaのパイプライン用UO鋼管をシーム溶接する際に使用されるサブマージアーク溶接用溶融型高塩基性フラックスにおいて、質量%で、CaO:5.0%以上、25.0%以下、MgO:1.0%以上、5.0%以下、Al2O3:15.0%超、30.0%以下、CaF2:30.0%以上、50.0%以下、SiO2:10.0%以上、20.0%以下、MnO:0.5%以上、15.0%以下を含有し、残部が不可避的不純物であり、且つ、式(1)で得られる塩基度Bが、1.2以上、3.2以下であることを特徴とする、サブマージアーク溶接用溶融型高塩基性フラックス。
B=6.05N[CaO]+4.0N[MgO]+5.1N[CaF2]+4.8N[MnO]−0.2N[Al2O3]−6.31N[SiO2]・・・(1)
ここで、N[k]は成分kのモル分率を表す。
[CaO:5.0%以上、25.0%以下]
CaOは溶接金属の溶接ビード形状に影響をおよぼす。5.0%未満では、軟化溶融温度が高くなり溶融ガスの放散の阻害によるあばたの発生等の溶接ビード表面の外観不良につながる。一方、過剰では粘度が高く余盛りが高くなる。またスラグの剥離性も低下する。そのため上限を25%以下とした。
また、CaOは、塩基度Bに影響を与える成分である。5.0%未満では塩基度Bが小さくなり、頂部スラグインの発生を助長する。25.0%超では塩基度Bが高くなり、フラックスが結晶質となり水素割れ感受性を高くする。
MgOは溶融スラグの粘性に影響を与える。1.0%未満ではスラグの粘性が低すぎて表面にあばた状の欠陥が発生する。一方、5.0%超ではスラグの粘性が高くなり、アンダーカットが発生する。
Al2O3はスラグの形成成分として重要な成分の一つであるため、フラックスの構成成分として添加する。しかし、15.0%以下では、図7に示した様にフラックスの結晶質の傾向が強くなり、吸湿し易くなる。その結果、溶接金属中の水素量が増加し低温割れ感受性が高くなる。一方、Al2O3の添加は、塩基度Bを低くする作用があるため、過剰に添加すると頂部スラグインの発生を助長する。また、Al2O3は、ビード形状に対して影響を与える。過剰に添加するとアンダーカットや馬の背状の突起が溶接ビード頂部に生成する。これらの観点から、上限を30.0%以下とした。
CaF2は、塩基度Bとは別に頂部スラグインの発生傾向に影響をあたえる成分である。CaF2が30.0%未満では頂部スラグインが発生するため、下限を30.0%以上とした。一方、過剰に添加するとアークが不安定となり、ビード表面にポックマークと呼ばれるあばた状の模様が発生する。そのため、上限を50.0%以下とした。また、CaF2は、フラックスの粘度や軟化溶融温度を下げるため、溶接ビードが過剰な凸形状になるのを防止し、また溶接ビード表面も滑らかにする。この効果を得るためには30.0%以上、好ましくは35%を超えて、さらに好ましくは37%を超えて添加する必要がある。
SiO2を20.0%超まで過剰に添加すると、頂部スラグインが発生するようになる。そのため、上限を20.0%以下とした。一方、図8に示した様に、10.0%未満ではフラックスが結晶質となり吸湿し易くなる。そのため、溶接金属中の水素量を高くし、その結果溶接金属の低温割れ感受性を高くする。そのため、下限を10.0%以上とした。
同時に、SiO2は止端部の母材との接触角を良好にしたり、止端部でのスラグのこびり付きを低減したりするなど止端部における母材とのなじみを良好にする。さらに溶接ビード表面を滑らかにして且つ極端な凸ビードになることを防ぎビード形状を良好にする効果がある。この効果を得るため10.0%以上は必要である。
MnOは、適量フラックスに添加することにより、頂部スラグインの発生を招かずに、溶接金属の酸素量を増加させることができる。図11は、MnOを添加したフラックスの塩基度Bと溶接金属中の酸素量の関係を示す。この図が示す様に、MnOを適量添加することにより、塩基度Bは図3が示す1.2以上でかつ、酸素量が0.018%以上を安定して得ることができる。この効果を得るためには0.5%以上の添加が必要である。しかし、15.0%超添加すると、図10に示す様な溶接ビードの底部の溶融線近傍あるいは溶融線上に底部スラグインSLが発生しやすくなる。そのため上限を15.0%以下とした。また、MnOを15.0%を越えて添加すると、塩基度が低い場合は溶接金属中の酸素量が過剰となり靭性が低下する可能性がある。そのため、上限を15.0%以下とした。
B=6.05N[CaO]+4.0N[MgO]+5.1N[CaF2]+4.8N[MnO]−0.2N[Al2O3]−6.31N[SiO2]・・・(1)
ここで、N[k]は、成分kのモル分率を表す。
塩基度Bと頂部スラグインの発生の有無との関係を整理すると、図3が示す様に、塩基度Bが1.2以上で頂部スラグインは発生しなくなる。一方、頂部スラグインの観点からは塩基度Bの上限は無いが、図9が示す様に、塩基度Bが3.2超ではフラックスが結晶質の傾向を強く示すようになり、吸湿し易くなる。その結果、溶接金属中の水素量が増加し低温割れ感受性が高くなる。このような観点から、塩基度Bの上限を3.2以下とした。
また、塩基度Bが1.2未満では、MnO添加との相乗効果で酸素が過剰となり、溶接金属の靭性が低下する可能性が出てくるため、その下限を1.2以上とした。
本発明において、母材引張強度は800MPa~1200MPaとされ、980MPa超~1200MPaであることが好ましい。
母材引張強度が800MPa未満の場合、本発明を適用する分野のUO鋼管としては強度が低く、そのため頂部スラグインの問題は発生しない。また、母材引張強度が1200MPaを超えると、十分な靭性を確保できない場合がある。
用いる母材の化学組成は、強度と靭性の観点から、質量%で、C:0.03%以上、0.12%以下、Si:0.5%以下、Mn:1.2%以上、2.5%以下、Ni:2.0%以下、Mo:0.6%以下、Ti:0.030%以下、Al:0.07%以下、P:0.015%以下、S:0.003%以下、Nb:0.0015%以上、0.1%以下、N:0.008%以下であることが望ましい。
Li2OおよびK2Oの何れか1種または2種の合計は、0.2%以上、5.0%以下であることが好ましく、2%超~5.0%以下であることがより好ましい。
MnOは、アークの再点弧電圧を高くする。そのため、溶接中にアークが再点弧する際に高められた電圧で、溶融池表面を振動させ、その結果溶接ビード表面の波目模様であるリップルラインを不揃いにする傾向がある。これは、機械的特性上問題では無く欠陥とは認識されないが、外観上好ましくなく、且つ溶接後に表面被覆する場合等には、作業性を低下させる要因となる。これに対し、Li2OおよびK2Oは、これを静めて、リップルラインの不揃いをなくす効果がある。この効果を得るためには、Li2OおよびK2Oの何れか1種または2種の合計で0.2%以上必要となる。一方、5.0%超添加すると、スラグの剥離性が低下してスラグのこびりつきが発生する。そのため上限を5.0%以下とした。
実施例および比較例では、3電極のサブマージアーク溶接を用いて、表1に示す溶接条件で、表2に示す組成および強度レベルの異なるワイヤを組み合わせ、表3に示す化学組成および引張強度を持つ板厚20mm、長さ1500mmの母材に、図12に示す断面形状の開先を加工し、表5または表6に示す成分のフラックスを用いて溶接を行った。実施例および比較例に用いたワイヤの組み合わせを表4に示す。
なお、図12に示す開先は、実施例および比較例において溶接を行う母材間に設けられた断面視V字型の溝であり、図12に示すように、溝の深さが9mm、V字溝のなす角度が80°のものである。また、実施例および比較例においてフラックスは、20℃、60%の湿度の環境で24時間保管後、使用する前に150℃の炉内で2時間乾燥して使用した。
衝撃試験片は図13(a)に示す様に溶接金属の板厚方向中央部から採取し、ノッチ深さ方向は溶接線方向になるように加工した。衝撃試験は、−30℃の試験温度で3回繰り返し試験を行った。溶接金属の靭性の評価は、3回繰り返した衝撃試験結果の平均値と、3回の衝撃試験結果の最小値を用いて行った。
また、丸棒型引張試験片は、図13(b)および図13(c)に示す様に溶接金属の板厚方向中央部から採取し、試験片の軸方向が溶接線方向になるように加工した。引張試験は繰り返し1回で、室温で行った。
表面の状況は、凹凸が激しいと放射線透過試験に写り欠陥として認識される可能性もあるため、欠陥と認識される可能性があるかも含めて判断した。
また、実施例8および実施例13では、溶接金属中の窒素の増加を防ぐ目的で、CaCO3を添加しているが、本発明の頂部スラグインの発生を防止する効果には何ら影響を与えていない。
比較例1および比較例2は、MnO以外の成分や塩基度Bは本発明の範囲に入っているが、MnOが本発明の範囲未満である。そのため、塩基度Bが高く頂部スラグインは発生していないが、酸素量が少なく溶接金属の靭性が低くシャルピー吸収エネルギーの平均値は100Jを越えているが、個々の値(最低値)では100Jを下回るデータが得られている。比較例1および2により、MnOの添加範囲を0.5%以上とすることにより、酸素量を安定して得ることにより靭性の低下を臨界的に防止できることが示されている。
比較例8は、フラックスのCaF2量が本発明の範囲を超えているため、アークが不安定となり、ビード表面にポックマークと呼ばれるあばた状の模様が発生している。
比較例13は、フラックス中のCaF2量が本発明の範囲未満である。そのため、頂部スラグインが発生している。また、溶接金属は、組織がマルテンサイト組織となり、強度が1250MPa以上で、靭性が低い。
比較例15は、フラックス中のMgO量が本発明の範囲未満である。そのため、溶接ビード表面にあばた状の欠陥が発生している。
また、実施例20および実施例26では、溶接金属のB量を調整して溶接金属の焼き入れ性を向上させる目的でB2O3を添加しているが、本発明の頂部スラグインの発生を防止する効果には何ら影響を与えていない。
また、実施例21では、溶接金属中の窒素の増加を防ぐ目的で、CaCO3を添加しているが、本発明の頂部スラグインの発生を防止する効果には何ら影響を与えていない。
比較例19から比較例21までは、Li2OおよびK2Oの添加量が本発明の範囲未満のため、ビード表面のリップルラインが荒れている。
比較例22、比較例23は、Li2OまたはK2Oの添加量が本発明の範囲を越えている。そのため、スラグがビード表面にこびり付きスラグの剥離性が低下している。
比較例24、比較例25は、Li2OとK2Oの両方を添加した場合の合計の添加量が本発明の範囲を越えている。そのため、スラグがビード表面にこびり付きスラグの剥離性が低下している。
3電極のサブマージアーク溶接を用いて、表1に示す溶接条件で、表2に示す組成および強度レベルの異なるワイヤを組み合わせ、表3に示す化学組成および引張強度を持つ板厚20mm、長さ1500mmの母材に、図12に示す断面形状の開先を加工し、表7に示す成分のNo.1~No.14のフラックスを用いて溶接を行った。
図2に示すように、溶接金属の酸素量が0.018%以上0.035%以下の範囲である場合、−30℃での衝撃吸収エネルギーが100J以上となる良好な靭性が得られることが判明した。
3電極のサブマージアーク溶接を用いて、表1に示す溶接条件で、表2に示す組成および強度レベルの異なるワイヤを組み合わせ、表3に示す化学組成および引張強度を持つ板厚20mm、長さ1500mmの母材に、図12に示す断面形状の開先を加工し、表8に示す成分のNo.15~No.24のフラックスを用いて溶接を行った。
図3に示すように、引張強度800MPa以上の溶接金属においては、塩基度Bが1.2以上で頂部スラグインは発生していないことが判明した。
3電極のサブマージアーク溶接を用いて、表1に示す溶接条件で、表2に示す組成および強度レベルの異なるワイヤを組み合わせて、表3に示す化学組成および引張強度を持つ板厚20mm、長さ1500mmの母材に、図12に示す断面形状の開先を加工し、表9に示す成分のNo.25~No.79のフラックスを用いて溶接を行った。
図4に示すように、溶接金属の酸素量とフラックスの塩基度Bとは、相関があることが判明した。
3電極のサブマージアーク溶接を用いて、表1に示す溶接条件で、表2に示す組成および強度レベルの異なるワイヤを組み合わせて、表3に示す化学組成および引張強度を持つ板厚20mm、長さ1500mmの母材に、図12に示す断面形状の開先を加工し、表10に示す成分のNo.80~No.89のフラックスを用いて溶接を行った。
図5は、フラックスのSiO2量と溶接金属の引張強度と頂部スラグインの発生傾向の関係を示すグラフである。
図5に示すように、溶接金属の引張強度が800MPa以上では、フラックスのSiO2量が20%超で頂部スラグインが発生する様になる。
3電極のサブマージアーク溶接を用いて、表1に示す溶接条件で、表2に示す組成および強度レベルの異なるワイヤを組み合わせて、表3に示す化学組成および引張強度を持つ板厚20mm、長さ1500mmの母材に、図12に示す断面形状の開先を加工し、表11に示す成分のNo.90~No.97のフラックスを用いて溶接を行った。
図6は、フラックスのCaF2量と溶接金属の引張強度と頂部スラグインの発生傾向の関係を示すグラフである。
図6に示すように、フラックス中のCaF2量が30%未満で頂部スラグインが発生する様になる。
表12に示す成分のNo.98~No.105のフラックスの水分吸着量を上述した方法により調べた。その結果を図7に示す。
図7に示すように、フラックス中のAl2O3量が15%以下で吸着水分量が急激に増加している。
表13に示す成分のNo.106~No.112のフラックスの水分吸着量を上述した方法により調べた。その結果を図8に示す。
表14に示す成分のNo.113~No.120のフラックスの水分吸着量を上述した方法により調べた。その結果を図9に示す。
3電極のサブマージアーク溶接を用いて、表1に示す溶接条件で、表2に示す組成および強度レベルの異なるワイヤを組み合わせて、表3に示す化学組成および引張強度を持つ板厚20mm、長さ1500mmの母材に、図12に示す断面形状の開先を加工し、表15に示す濃度でMnOを含有するNo.121~No.139のフラックスを用いて溶接を行った。
図11に示すように、MnOを0.5%以上添加することにより、塩基度Bが1.2以上でかつ、酸素量が0.018%以上の溶接金属を安定して得ることができる。
SL:底部スラグイン
Claims (2)
- 母材引張強度が800MPa~1200MPaのパイプライン用UO鋼管をシーム溶接する際に使用されるサブマージアーク溶接用溶融型高塩基性フラックスにおいて、
質量%で、
CaO:5.0%以上、25.0%以下、
MgO:1.0%以上、5.0%以下、
Al2O3:15.0%超、30.0%以下、
CaF2:30.0%以上、50.0%以下、
SiO2:10.0%以上、20.0%以下、
MnO:0.5%以上、15.0%以下
を含有し、残部が不可避的不純物であり、且つ、式(1)で得られる塩基度Bが、1.2以上、3.2以下であることを特徴とする、サブマージアーク溶接用溶融型高塩基性フラックス。
B=6.05N[CaO]+4.0N[MgO]+5.1N[CaF2]+4.8N[MnO]−0.2N[Al2O3]−6.31N[SiO2]・・・(1)
ここで、N[k]は成分kのモル分率を表す。 - さらに、質量%で、Li2OおよびK2Oのいずれか1種または2種を、合計で、0.2%以上、5.0%以下含有することを特徴とする、請求項1に記載のサブマージアーク溶接用溶融型高塩基性フラックス。
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US13/258,522 US20120043304A1 (en) | 2009-04-10 | 2010-04-06 | Melt type high basicity flux for submerged arc welding use |
BRPI1010518-2A BRPI1010518B1 (pt) | 2009-04-10 | 2010-04-06 | "high basic flow of the cast type for use in welding submerse arc" |
JP2011508402A JP4903912B2 (ja) | 2009-04-10 | 2010-04-06 | サブマージアーク溶接用溶融型高塩基性フラックス |
EP10761773.0A EP2418043B1 (en) | 2009-04-10 | 2010-04-06 | Melt type high basicity flux for submerged arc welding use |
CN201080016063.6A CN102387890B (zh) | 2009-04-10 | 2010-04-06 | 埋弧焊用熔炼型高碱性焊剂 |
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JP2013091082A (ja) * | 2011-10-26 | 2013-05-16 | Nippon Steel & Sumikin Welding Co Ltd | 低温用鋼のサブマージアーク溶接方法 |
WO2014109402A1 (ja) * | 2013-01-11 | 2014-07-17 | 株式会社神戸製鋼所 | 耐水素脆化感受性に優れた溶接金属及びサブマージアーク溶接用ソリッドワイヤ |
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US20120043304A1 (en) | 2012-02-23 |
BRPI1010518A2 (pt) | 2016-03-15 |
CN102387890B (zh) | 2016-02-03 |
EP2418043A1 (en) | 2012-02-15 |
EP2418043B1 (en) | 2018-03-28 |
BRPI1010518B1 (pt) | 2017-12-26 |
EP2418043A4 (en) | 2016-07-27 |
JP4903912B2 (ja) | 2012-03-28 |
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JPWO2010117074A1 (ja) | 2012-10-18 |
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