JP2017024055A - Flux cored wire for welding stainless steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flux cored wire for welding stainless steel which can provide a welded metal excellent in high-temperature tensile strength and cracking resistance under high temperature environments and has preferable welding workability in a horizontal fillet welding and a vertical upward welding.SOLUTION: There is provided a flux cored wire for welding stainless steel which contains, by mass% based on the total mass of the wire, 0.005 to 0.10% of C, 0.2 to 1.0% of Si, 1.5 to 4.5% of Mn, 8 to 13% of Ni, 16 to 23% of Cr, 0.01 to 1.0% of Mo, 0.55 to 1.0% of Ti, 0.01 to 0.05% of N and 0.05% or less of Nb in the total of the stainless steel sheath and flux, and in flux, contains 5 to 8% of TiOconversion value, 0.1 to 1.5% of SiOconversion value, 0.01 to 0.1% of ZrOconversion value, 0.01 to 0.1% of AlOconversion value, 0.01 to 0.30% of the total of NaO conversion value and KO conversion value, 0.1 to 1.0% of F conversion value and 0.001% or less of Bi.SELECTED DRAWING: None

Description

  INDUSTRIAL APPLICABILITY The present invention is applied to welding of stainless steel, and can obtain a weld metal excellent in high-temperature tensile strength and crack resistance, particularly in a high-temperature environment, and has welding workability in horizontal fillet welding and vertical improvement welding. The present invention relates to a stainless steel welding flux cored wire suitable for high temperature applications.

  In the early 1990s, in the piping of austenitic stainless steel equipment used in the high temperature environment of petroleum refining equipment, cracks occurred one after another in welded joints welded with a flux-cored wire for austenitic stainless steel welding containing Bi. It has been reported. In particular, in the temperature range around 700 ° C., troubles that cause cracks in welded joints have been reported within a short period of less than one year after the start of use, which is a serious problem in practical use. As a cause of this crack, Bi is added in the form of an oxide to a general stainless steel welding flux cored wire in order to improve the slag peelability. It has been reported that welded joints to which Bi is added are concentrated in the austenite grain boundaries and reheat cracking occurs when exposed to a temperature range of 700 ° C. or higher. As a result, it has been conventionally found that weld joints to which Bi is added have a significantly reduced ductility due to a decrease in grain boundary strength in a short time due to reheat cracking.

  As a means to prevent reheat cracking of weld metal welded with a flux-cored wire for stainless steel welding in a high temperature environment, if the Bi content is about 10 ppm, there is no effect on the hot ductility of the weld metal, which is a practical problem. There is no recommendation. For this reason, JIS stipulates Bi ≦ 0.001% by mass of wire, and the American Petroleum Institute (API) also uses Bi ≦ 0.002% by mass for welding pipes used at 550 ° C. or higher. It is recommended to use wires.

  The so-called Bi-free stainless steel welding flux cored wire has a Bi content as close to 0 as possible, and has a high temperature strength and excellent crack resistance. Therefore, it is used in a high temperature environment. Has been applied. However, such a Bi-added stainless steel welding flux-cored wire has a low Bi content, which has an effect of improving the slag releasability. There is a problem that the performance is poor and the demand for higher efficiency in welding construction cannot be satisfied. Therefore, it is desired to develop a flux-free wire for stainless steel welding with no addition of Bi that has welding workability equivalent to that of Bi-containing stainless steel welding flux-cored wire, high strength at high temperatures, and excellent crack resistance. It was.

As described above, various techniques for a stainless steel welding flux-cored wire suitable for high-temperature applications have been studied. For example, Patent Document 1 discloses TiO ₂ , SiO ₂ , ZrO ₂ , metal fluoride, Al ₂ O. _{3. A} flux cored wire for austenitic stainless steel welding containing Bi and Bi compounds is disclosed. However, this flux cored wire for welding stainless steel has a problem that the slag removability is poor because the ZrO ₂ content is large and nitride is generated between the weld metal and the weld slag.

Patent Document 2 discloses a flux-cored wire for welding stainless steel for high-temperature applications that includes O, Nb, V, C, N, Cr, TiO ₂ , SiO ₂ , Al ₂ O ₃ and metal fluoride. It is disclosed. However, in this stainless steel welding flux-cored wire, the Nb content in the weld metal is increased, and the slag peelability is deteriorated. Further, since the N content is reduced, stable solid solution strengthening cannot be obtained depending on the crystallization amounts of austenite and ferrite, and the tensile strength of the weld metal is lowered. Furthermore, when applied to austenitic stainless steels such as SUS304N2, there is a problem in that the N content in the weld metal increases due to the influence of dilution, resulting in poor slag removability.

JP 11-192586 A Japanese Patent Laid-Open No. 7-276085

  Therefore, the present invention has been devised in view of the above-described problems, and is applied to welding of stainless steel, and a weld metal having excellent high-temperature tensile strength and crack resistance is obtained particularly in a high-temperature environment. Another object of the present invention is to provide a flux-cored wire for welding stainless steel with good welding workability in horizontal fillet welding and vertical welding.

  In order to solve the above-described problems, the present inventors have made trials on stainless steel welding flux-cored wires having various component compositions and examined them in detail. As a result, by optimizing the components in the flux-cored wire for welding stainless steel (metal component, flux component), the tensile strength, toughness and crack resistance of the weld metal at high temperatures are improved, and horizontal fillet welding is performed. And it discovered that welding workability | operativity became favorable by standing improvement progress welding, and completed this invention.

The gist of the present invention is, in a stainless steel welding flux-cored wire obtained by filling a stainless steel outer shell with flux, mass% with respect to the total mass of the wire, and the total of the stainless steel outer shell and the flux, C: 0.005 to 0.00. 10%, Si: 0.2 to 1.0%, Mn: 1.5 to 4.5%, Ni: 8 to 13%, Cr: 16 to 23%, Mo: 0.01 to 1.0%, Ti: 0.55 to 1.0%, N: 0.01 to 0.05%, Nb: 0.05% or less, and further, Ti oxidation in the flux in mass% with respect to the total mass of the wire. Material: 5 to 8% in total of TiO ₂ conversion value, Si oxide: 0.1 to 1.5% in total of SiO ₂ conversion value, Zr oxide: 0.01 to 0 in total of ZrO ₂ conversion value .1%, Al oxides: 0.01% to 0.1% in total of terms of Al ₂ O ₃ value, Na compound And K compound: Na ₂ O conversion value and 0.01 to 0.30% in total of K ₂ O converted value, fluorine compounds: containing 0.1 to 1.0% in total in terms of F values, Bi: It is 0.001% or less, and the balance is a flux-cored wire for welding stainless steel, characterized by the Fe content of the stainless steel skin, the Fe content in the alloy iron, iron powder, and inevitable impurities.

  According to the flux-cored wire for stainless steel welding to which the present invention is applied, a weld metal excellent in high-temperature tensile strength and crack resistance is obtained, particularly in a high-temperature environment, and horizontal fillet welding and vertical improvement are promoted. It is possible to provide a flux-cored wire for welding stainless steel with good welding workability in welding.

  In order to solve the above-described problems, the present inventors have made trials on stainless steel welding flux-cored wires having various component compositions and examined them in detail. As a result, by optimizing the content of C, Cr, Ni, Mo, Nb, Bi in the flux-cored wire for welding stainless steel, the tensile strength, toughness and crack resistance at high temperatures are improved. I found it.

  In addition, when held at a high temperature for a long time, the σ phase precipitates in the carbide / ferrite phase at the ferrite / austenite grain boundary, the ferrite phase becomes brittle, and the high temperature tensile strength decreases. It has been found that by optimizing the amount of ferrite, the amount of ferrite can be kept low, and carbides and σ phases in the ferrite / austenite grain boundaries can be reduced.

  Further, it was found that by adjusting the amount of C, appropriate carbides can be precipitated in the austenite phase and the tensile strength can be improved. However, since the toughness was reduced accordingly, further investigation was performed. As a result, it has been found that by optimizing the amount of Ti, deoxidation can be promoted to reduce oxides in the weld metal and improve toughness.

  On the other hand, since the ferrite content decreased and crack resistance tended to deteriorate, it was found that the amount of Mn added was optimized, segregation of the low melting point compound was reduced, and crack resistance could be improved.

As for welding workability in horizontal fillet welding and vertical improvement welding, compared to the conventional flux-cored wire for stainless steel welding containing Bi, the slag peelability deteriorates and the high efficiency of welding work cannot be satisfied. As a result of various investigations, it was found that slag peelability can be improved by optimizing the amount of TiO ₂ and adjusting the thermal expansion coefficient of the weld slag to increase the difference in thermal expansion between the weld metal and the weld slag. . The above effect can be improved by adding appropriate amounts of Al ₂ O ₃ and a fluorine compound. Further, the stability of the arc and the reduction of the sputtering amount can be achieved by adding appropriate amounts of TiO ₂ , ZrO ₂ , Na and K compounds and fluorine compounds, and the bead shape can be Si, SiO ₂ , Al ₂ O ₃ , Na. It has been found that it can be improved by adding appropriate amounts of the compound and the K compound.

Furthermore, it has been found that by optimizing TiO ₂ and Ti, the metal drooping property in standing improvement welding is suppressed and the bead shape is improved.

  The flux-cored wire for stainless steel welding of the present invention can be obtained by the synergistic effect of the individual and coexistence of each component composition of the stainless steel outer shell and the flux, and the reason for addition and limitation of each component composition will be described below. . In addition, content of each component composition shall be shown by the mass% with respect to the total mass of a wire, and when showing the mass%, it shall show only by describing%.

  First, the total of the stainless steel skin and the flux is limited as follows.

[C: 0.005-0.10%]
C is added from stainless steel skin, ferromanganese, ferrosilicon manganese, graphite, and the like, and has the effect of generating Cr carbide and Ti carbide to increase the high temperature tensile strength of the weld metal. If C is less than 0.005%, the formation of Cr carbide and Ti carbide is insufficient, and the tensile strength at high temperature is low. On the other hand, when C exceeds 0.10%, Cr carbide and Ti carbide are coarsened, and the toughness after being kept at a high temperature is lowered. Therefore, the C content is 0.005 to 0.10%.

[Si: 0.2 to 1.0%]
Si is added from stainless steel skin, metallic silicon, ferrosilicon, ferrosilicon manganese, and the like, and has an effect of improving bead shape and slag encapsulation. If Si is less than 0.2%, the amount of slag formed by the deoxidation reaction during welding is small, and the bead shape becomes poor. On the other hand, if Si exceeds 1.0%, the amount of slag becomes excessive, and the slag encapsulation becomes worse. Therefore, the Si content is set to 0.2 to 1.0%.

[Mn: 1.5 to 4.5%]
Mn is added from stainless steel skin, metallic manganese, ferromanganese, ferrosilicon manganese, Mn nitride, and the like, and has the effect of reducing segregation of low melting point compounds and improving crack resistance. If Mn is less than 1.5%, the low melting point compound is segregated at the austenite grain boundary, so that the crack resistance is deteriorated. On the other hand, if Mn exceeds 4.5%, carbides and nitrides are generated and the toughness at normal temperature is lowered. Therefore, the Mn content is 1.5 to 4.5%.

[Ni: 8-13%]
Ni is an element that is added from a stainless steel shell, metallic nickel, ferronickel, or the like and stabilizes the austenite phase, and has the effect of adjusting the ferrite content and improving crack resistance. If Ni is less than 8%, the amount of crystallization of austenite decreases, the amount of ferrite increases, and the toughness at room temperature decreases. On the other hand, when Ni exceeds 13%, the amount of ferrite crystallized decreases, segregation of the low melting point compound is promoted, and the crack resistance deteriorates. Therefore, the Ni content is 8-13%.

[Cr: 16-23%]
Cr is an element that is added from a stainless steel shell, metallic chromium and ferrochromium, Cr nitride, and the like and stabilizes the ferrite phase, and has the effect of increasing the tensile strength of the weld metal. If Cr is less than 16%, the amount of crystallization of ferrite decreases, the amount of austenite increases, and the tensile strength at room temperature decreases. On the other hand, when Cr exceeds 23%, the production of Cr carbide increases, and the tensile strength at high temperature decreases. Therefore, the Cr content is 16-23%.

[Mo: 0.01 to 1.0%]
Mo is added from a stainless steel shell, metallic molybdenum, ferromolybdenum, or the like, and is dissolved in the austenite phase, and has an effect of improving the tensile strength. If Mo is less than 0.01%, the effect of solid solution strengthening cannot be obtained, and the tensile strength at room temperature decreases. On the other hand, when Mo exceeds 1.0%, an extremely hard and brittle σ phase is precipitated from the ferrite, and the toughness after being kept at a high temperature is lowered. Therefore, the Mo content is set to 0.01 to 1.0%.

[Ti: 0.55-1.0%]
Ti is added from stainless steel skin, metallic titanium, ferrotitanium, etc., promotes deoxidation, reduces oxides in the weld metal, improves toughness and improves welding workability in vertical welding. Has the effect of When Ti is less than 0.55%, deoxidation is insufficient and toughness at room temperature is lowered. Further, in vertical improvement welding, metal dripping occurs and the bead shape becomes defective. On the other hand, if Ti exceeds 1.0%, droplets grow coarsely during welding and large spatters are generated. Therefore, the Ti content is set to 0.55 to 1.0%.

[N: 0.01 to 0.05%]
N is added from a stainless steel shell, chromium nitride, manganese nitride, or the like, and has the effect of improving the tensile strength by being dissolved in austenite. If N is less than 0.01%, the effect cannot be obtained, and the tensile strength at room temperature decreases. On the other hand, if N exceeds 0.05%, N that cannot be completely dissolved in the molten pool is generated at the time of welding, and droplet transfer is not performed smoothly, and the amount of spatter generated increases. Therefore, the N content is set to 0.01 to 0.05%.

[Nb: 0.05% or less]
Nb is a component contained in the stainless steel skin and unavoidably contained in the wire. If the Nb content is increased, a compound is generated between the weld metal and the slag to deteriorate the slag removability. Therefore, a smaller content is desirable, and 0.05% or less is acceptable. The Nb content is preferably 0.02% or less.

  Next, the component composition contained in the flux in mass% with respect to the total mass of the wire is limited as follows.

[Ti oxide: 5 to 8% in total of TiO ₂ conversion values]
TiO ₂ is added from rutile, titanium oxide, sodium titanate, titanium slag, illuminite or the like. These improve the slag peelability by adjusting the thermal expansion coefficient of the weld slag and increasing the difference in thermal expansion between the weld metal and the weld slag, and also have the effect of improving the welding workability in the vertical improvement welding. Have. When the total of the TiO ₂ conversion values of the Ti oxide is less than 5%, the difference in thermal expansion between the weld metal and the weld slag decreases, and the slag peelability becomes poor. Further, in vertical improvement welding, metal dripping occurs and the bead shape becomes defective. On the other hand, if the total TiO ₂ conversion value of the Ti oxide exceeds 8%, the slag completely encapsulates the droplets and hinders the migration of the droplets, so that the arc becomes stable. Therefore, the total of TiO ₂ converted values of Ti oxide is 5 to 8%.

[Si oxide: 0.1 to 1.5% in total in terms of SiO ₂ ]
SiO ₂ is added from silica sand, zircon sand, etc., and acts as a slag forming agent, and has the effect of adjusting the viscosity of the slag to improve the slag encapsulation. When the total SiO ₂ conversion value of the Si oxide is less than 0.1%, the viscosity of the slag is lowered and the slag encapsulation is deteriorated. On the other hand, when the total of SiO ₂ conversion values of Si oxides exceeds 1.5%, the amount of slag increases, the balance between the weld metal and the amount of slag deteriorates, and the bead shape becomes poor. Therefore, the total of SiO ₂ conversion values of Si oxide is 0.1 to 1.5%.

[Zr oxide: 0.01 to 0.1% in total in terms of ZrO ₂ ]
ZrO ₂ is added from zircon sand, zirconium oxide, or the like, and has the effect of adjusting the viscosity of the slag and reducing the amount of spatter generated during droplet transfer. When the total of the ZrO ₂ conversion values of the Zr oxide is less than 0.01%, the viscosity of the slag becomes low, and small particles are sputtered during droplet transfer. On the other hand, if the total of ZrO ₂ conversion values of the Zr oxide exceeds 0.1%, the viscosity of the slag increases, the droplets grow large, the droplet transfer is not smoothly performed, and the arc becomes unstable. . Therefore, the total of ZrO ₂ converted values of the Zr oxide is set to 0.01 to 0.1%.

[Al oxide: 0.01 to 0.1% in total of converted value of Al ₂ O ₃ ]
Al ₂ O ₃ is added from alumina, potassium feldspar, feldspar, etc., and has the effect of adjusting the melting point of the slag and improving the bead shape. If the total Al ₂ O ₃ conversion value of the Al oxide is less than 0.01%, the melting point of the slag is lowered, so that the solidification of the weld metal and the slag becomes uneven and the bead shape becomes poor. On the other hand, if the total Al ₂ O ₃ conversion value of the Al oxide exceeds 0.1%, the melting point of the slag increases, and the slag remains in the bead portion where the cooling rate is fast, resulting in poor slag peelability. The total Al ₂ O ₃ conversion value of the Al oxide is 0.01 to 0.1%.

[Na compound and K compound: 0.01 to 0.30% in total of Na ₂ O converted value and K ₂ O converted value]
Na compound and K compound are added from Na ₂ O and K ₂ O of water glass, fluorides such as sodium fluoride and potassium silicofluoride, etc., and have the effect of stabilizing the arc and reducing the amount of spatter generated. If the total of Na ₂ O converted value and K ₂ O converted value of Na compound and K compound is less than 0.01%, the arc becomes unstable, the droplet transfer becomes short-circuit transfer, and the amount of spatter generated increases. On the other hand, when the total of Na ₂ O converted value and K ₂ O converted value of Na compound and K compound exceeds 0.30%, solidification of slag is accelerated and the bead shape is deteriorated. Therefore, the total of Na ₂ O converted value and K ₂ O converted value of Na compound and K compound is 0.01 to 0.30%.

[Fluorine compounds: 0.1 to 1.0% in total in terms of F]
The fluorine compound is added from sodium fluoride, potassium silicofluoride, potassium zircon fluoride, cryolite, aluminum fluoride, lithium fluoride, fluorite, and the like, and has an effect of improving arc stability. If the total F converted value of the fluorine compound is less than 0.1%, the above-mentioned effect is insufficient and the arc becomes unstable. On the other hand, when the total F converted value of the fluorine compound exceeds 1.0%, the melting point of the slag is lowered, the solidification of the slag is faster than the weld metal, and the bead shape is not uniform. Therefore, the total F converted value of the fluorine compound is 0.1 to 1.0%.

[Bi: 0.001% or less]
Bi tends to concentrate at austenite grain boundaries and deteriorates crack resistance when the weld is kept at a high temperature for a long time, so Bi in the flux is made 0.001% or less.

  The balance is Fe and inevitable impurities. The Fe content is the Fe content from the stainless steel outer shell, flux iron powder, iron alloy (ferroalloys such as ferrosilicon, ferromanganese, and ferrosilicon manganese) powder. Inevitable impurities refer to impurities inevitably mixed such as P, S, Bi, etc., and preferably 0%, but it is difficult to make 0% because there is a problem that production costs increase.

  From the viewpoint of crack resistance, P is preferably 0.040% or less, and S is preferably 0.020% or less.

  As mentioned above, although the reason for limitation of the component composition of the flux-cored wire for stainless steel welding of the present invention was described, when referring to the method for producing the flux-cored wire for stainless steel welding, for example, the stainless steel sheath is formed from a strip steel into a tubular shape. In this case, the filled flux that has been blended, mixed, stirred, and dried is filled into a U-shaped groove, then formed into a round shape, and drawn to a predetermined wire diameter. At this time, the formed outer seam can be welded to form a seamless type stainless steel welding flux-cored wire. When the stainless steel skin is a pipe, the pipe can be vibrated, filled with flux, and drawn to a predetermined wire diameter. In any of the manufacturing methods, the wire diameter can be manufactured up to 0.8 to 3.6 mm.

  The flux can be granulated by adding a fixing agent (potassium silicate and sodium silicate water glass) so that the supply and filling can be performed smoothly.

  Hereinafter, the present invention will be described in detail by way of examples.

  Using the stainless steel skin of the chemical composition shown in Table 1, a stainless steel welding flux cored wire having the composition shown in Table 2 was prepared. In the production of this wire, a stainless steel outer shell was filled with a flux, the end faces were welded to make a seamless shape, and then the diameter was reduced to produce a stainless steel welding flux-cored wire. The wire diameter was 1.2 mm and the flux filling rate was 19 to 24%.

  We investigated the welding workability, weld metal performance, and crack resistance of these prototyped wires.

  Welding workability evaluation is performed by using horizontal SUS304L steel plate of the components shown in Table 3 and horizontal fillet welding and stand-up improvement fillet welding under the welding conditions shown in Table 4. Arc stability, spatter generation amount, slag encapsulation , Slag peelability, presence or absence of metal sag (only in case of fillet welding progressed), and bead shape were investigated.

  In the weld metal test, two-layer buttering was performed on an SM490A steel plate with a plate thickness of 20 mm and a bevel angle of 10 °, and a multi-layered pile was formed under a gap of 16 mm according to JIS Z 3323 under the welding conditions shown in Table 4. Welding was performed. Tensile test pieces and impact test pieces were collected from the weld metal part and tested at room temperature and at a high temperature of 650 ° C.

  In the normal temperature test, a tensile test at room temperature and an impact test at a test temperature of −20 ° C. were performed, and a tensile strength of 520 MPa or more and an absorbed energy of 3 average values were determined to be 60 J or more.

  In the high temperature test, a tensile test was performed immediately after heating the tensile test piece to 650 ° C., and the tensile strength was 300 MPa or more. In the impact test, the impact test piece was held at 650 ° C. × 2 h, air-cooled to room temperature, and the absorbed energy was 3 J or more at a test temperature of −20 ° C., which was 30 J or more.

  Evaluation of cracking resistance was performed by using a SUS304L steel plate having a thickness of 20 mm having the components shown in Table 3 and performing multi-layer welding under the welding conditions shown in Table 4 at a bevel angle of 10 ° and a gap of 16 mm. A side bend test piece was collected in accordance with JIS Z 3122 and a side bend test was performed. The survey results are summarized in Table 5.

  The wire symbols W1 to W8 in Tables 2 and 4 are examples of the present invention, and the wire symbols W9 to W19 are comparative examples.

The wire symbols W1 to W8, which are examples of the present invention, are the sum of C, Si, Mn, Ni, Cr, Mo, Ti, N and the TiO ₂ equivalent value of the flux, the SiO ₂ equivalent value of the stainless steel sheath and the flux. , Total of ZrO ₂ converted value, total of Al ₂ O ₃ converted value, total of Na ₂ O converted value and K ₂ O converted value, total of F converted value, Bi is appropriate, so normal temperature test and high temperature The tensile strength and absorbed energy of the weld metal in the test were good, and the crack resistance was also good. In addition, the arc stability in horizontal fillet welding and vertical improvement welding was good, the amount of spatter was small, and the bead shape, slag encapsulation, and slag peelability were good.

  Since the wire symbol W9 in the comparative example has a small amount of C, the tensile strength of the weld metal in the high temperature test was low. Moreover, since there is much Si, the slag encapsulation was poor in horizontal fillet welding and vertical improvement welding.

Since the wire symbol W10 has a large amount of C, the absorbed energy of the weld metal in the high temperature test was low. Further, since the ZrO ₂ conversion value is small, the amount of spatter generated was large in horizontal fillet welding and vertical improvement welding. Furthermore, since the Al ₂ O ₃ conversion value was small, the bead shape was poor.

Since the wire W symbol 11 has a small amount of Si, the bead shape was poor in horizontal fillet welding and vertical improvement welding. Moreover, since there was little Mn, the wrinkle of 5.0 mm generate | occur | produced in the side bending test piece. Further, since TiO ₂ converted value is large, the arc state was unstable in horizontal fillet welding and vertical upward proceeds welding.

Since the wire symbol W12 has a large amount of Mn, the absorbed energy of the weld metal in the normal temperature test was low. Moreover, since N is small, the tensile strength of the weld metal in the normal temperature test was low. Further, since the total of Na ₂ O converted value and K ₂ O converted value is small, the arc state is unstable and the amount of spatter is large in horizontal fillet welding and vertical improvement welding.

Since the wire symbol W13 has a small amount of Ni, the absorbed energy of the weld metal in the normal temperature test was low. Further, since the SiO ₂ converted value is small, the slag encapsulated was poor in horizontal fillet welding and vertical upward proceeds welding. Furthermore, since there were many F conversion values, the bead shape was unsatisfactory.

Since the wire symbol W14 has a large amount of Ni, 4.0 mm wrinkles occurred on the side bend specimen. Moreover, since there was little Cr, the tensile strength of the weld metal in the normal temperature test was low. Further, since the SiO ₂ converted value is large, the bead shape was poor in horizontal fillet welding and vertical upward proceeds welding.

Since the wire symbol W15 has a large amount of Cr, the tensile strength of the weld metal in the high temperature test was low. Moreover, since there was much Ti, there was much spatter generation amount by horizontal fillet welding and vertical improvement welding. Further, since the terms of ZrO ₂ value is large, the arc state was unstable.

Since the wire symbol W16 has a small amount of Mo, the tensile strength of the deposited metal in the normal temperature test was low. Further, since the F-converted value is small, the arc was unstable in horizontal fillet welding and vertical improvement welding. Further, since the TiO ₂ conversion value is small, the slag peelability is poor, and metal dripping occurs particularly in the vertical improvement welding, and the bead shape is poor.

Since the wire symbol W17 has a large amount of Mo, the absorbed energy of the weld metal in the high temperature test was low. Moreover, since there are many values converted to Al ₂ O ₃ , the slag peelability was poor in horizontal fillet welding and vertical improvement welding.

  Since the wire symbol W18 has a small amount of Ti, the absorbed energy in the normal temperature test was low. Further, in the vertical improvement welding, metal dripping occurred and the bead shape was poor. Moreover, since there is much Nb, slag peelability was inferior in horizontal fillet welding and vertical improvement welding.

Since the wire symbol W19 has a large amount of N, a large amount of spatter was generated in horizontal fillet welding and vertical improvement welding. Further, since the terms of Na ₂ O values and K sum is often the ₂ O converted value, the bead shape was poor. Furthermore, since there was much Bi, a wrinkle of 4.5 mm was generated on the side bending test piece.

Claims (1)

In the flux-cored wire for stainless steel welding formed by filling the stainless steel outer shell with flux,
It is the mass% with respect to the total mass of the wire.
C: 0.005-0.10%,
Si: 0.2 to 1.0%
Mn: 1.5 to 4.5%,
Ni: 8-13%,
Cr: 16-23%
Mo: 0.01 to 1.0%,
Ti: 0.55-1.0%,
N: 0.01 to 0.05% is contained,
Nb: 0.05% or less,
Furthermore, in mass% with respect to the total mass of the wire,
Ti oxide: 5 to 8% in total of TiO ₂ conversion value,
Si oxide: 0.1 to 1.5% in total of SiO ₂ conversion value,
Zr oxide: 0.01 to 0.1% in total in terms of ZrO ₂ ,
Al oxide: 0.01 to 0.1% in total of Al ₂ O ₃ conversion value,
Na compound and K compound: 0.01 to 0.30% in total of Na ₂ O converted value and K ₂ O converted value,
Fluorine compound: Contains 0.1 to 1.0% in total in terms of F,
Bi: 0.001% or less,
The balance is the Fe content of the stainless steel sheath, the Fe content in the alloy iron, iron powder, and inevitable impurities, and a stainless steel welding flux cored wire.