KR101708997B1 - Ni BASED ALLOY FLUX CORED WIRE - Google Patents

Abstract

[PROBLEMS] To provide excellent bead shape, excellent arc stability and slag releasing property, and excellent strength and toughness in electron weldability such as Ni-based alloy and 9% Ni steel and high corrosion resistant austenitic stainless steel. A Ni-based flux-cored wire in which a weld metal having resistance to breakdown, high temperature cracking resistance and corrosion resistance is obtained.
[MEANS FOR SOLVING PROBLEMS] A Ni based alloy flux cored wire filled with a flux in a shell of a Ni-based alloy, comprising a predetermined amount of Ni, Cr, Mo, and Nb per a total weight of the wire, A predetermined amount of an alkali metal compound of Na, K, and Li per a total mass of the wire is contained in the flux in a predetermined amount, TiO ₂ , SiO ₂ , ZrO ₂ , MnO ₂ and Al ₂ O ₃ , And the fluoride is contained in a predetermined amount in terms of fluoride conversion.

Description

Ni based alloy flux cored wire < RTI ID = 0.0 > (Ni < / RTI > BASED ALLOY FLUX CORED WIRE)

The present invention relates to a Ni-based alloy flux cored wire used in welding such as 9% Ni steel, Ni base alloy, and high corrosion resistant austenitic stainless steel.

A welding material composed of a Ni-based alloy is used for welding, for example, a Ni-based alloy or a high corrosion resistant austenitic stainless steel used as a structural member of a chemical plant or a petroleum-related facility. Alternatively, a welding material composed of a Ni-based alloy is used for welding 9% Ni steel used as structural members such as LNG, liquid nitrogen, and storage tanks such as liquid oxygen.

In recent years, gas shielded arc welding using Ni-based flux cored wires, which can be expected to have higher working efficiency, is being widened compared with coated arc welding or TIG welding for special welding materials such as Ni-based alloys.

In the gas shielded arc welding using the Ni-based flux cored wire, since the melting point of the weld metal is low in the Ni-based alloy, the gas tends to be trapped at the interface with the solidified slag, ) Is apt to occur. In addition, improvements are being made to other performances.

Thus, for example, Patent Document 1 discloses a Ni-based alloy flux cored wire improved in fit resistance by adjustment of the amount of addition of TiO ₂ , ZrO ₂ and SiO ₂ and addition of MnO ₂ . Further, with respect to this Ni based alloy flux cored wire, the addition of MnO ₂ has the effect of accelerating the slag out of Si, thereby reducing Si in the weld metal and improving the high temperature crack resistance.

Further, for example, Patent Document 2, TiO _2, SiO _2, by the addition of MnO ₂ to lower the solidification temperature of the slag to the slag-forming agent by the ZrO ₂ to the base, the horizontal fillet, sidewise (橫向) in the weld, in feet A Ni-based alloy flux cored wire having improved properties is disclosed.

Further, for example, Patent Document 3 discloses a Ni-based alloy flux cored wire in which an excellent coagulation-cracking property and a low temperature toughness can be obtained by using a Hastelloy-based weld metal for welding 9% Ni steel. In addition, this Ni-based alloy flux cored wire has excellent welding workability in all positions by optimizing the addition balance of TiO ₂ , SiO ₂ , MnO, ZrO ₂ and alkali metals.

In addition, for example, Patent Document 4 discloses that the amount of addition of TiO ₂ , Al ₂ O ₃ , SiO ₂ , Fe oxide, Mn oxide, alkali metal and fluoride is appropriately adjusted so that bead conformity is good and spatter generation amount is small, There is disclosed a Ni-based alloy flux cored wire excellent in welding workability such as encapsulation property and peelability.

Japanese Patent Application Laid-Open No. 2011-140064 Japanese Patent Application Laid-Open No. 2008-246507 Japanese Patent Application Laid-Open No. 2007-203350 Japanese Unexamined Patent Application Publication No. 6-198488

However, the conventional techniques have the following problems.

In the Ni based alloy flux cored wires described in Patent Documents 1 and 2, the slag solidification temperature is lowered by the addition of MnO ₂ , which is a low melting point oxide. Therefore, in the Ni-based alloy flux cored wires described in Patent Documents 1 and 2, there is a room for improvement in bead shape in the upright posture and the upward posture.

Also in the Ni based alloy flux cored wire described in Patent Document 3, since the addition amount of MnO is high, the slag solidification temperature is lowered. Therefore, in the Ni-based alloy flux cored wire described in Patent Document 3, there is room for improvement in the bead shape in the nose posture and the upward posture.

In the Ni-based alloy flux cored wire described in Patent Document 4, ZrO ₂ is not contained in the slag component. Therefore, in the Ni-based alloy flux cored wire described in Patent Document 4, there is a room for improvement in bead shape in the nose posture and the upward posture. ZrO ₂ has a high melting point and is effective for improving the shape of the beads in the upward and downward orientations by the addition thereof. Further, in the Ni-based alloy flux cored wire described in Patent Document 4, there is no study on the workability of welding in the orientation and the upward posture.

In addition, in the prior art, the improvement of the weld metal performance such as arc stability, slag releasing property, and bead shape and welding workability and strength, toughness, fault resistance, resistance to hot cracking, . However, it has been desired to improve the welding workability and weld metal performance in addition to the compatibility of the welding workability and the weld metal performance. On the other hand, the fault tolerance is a property in which a blow hole, a pit, and a slag are hardly generated.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a weld bead excellent in arc stability and slag releasability, as well as excellent bead shape in electron weldability such as Ni-based alloy and 9% Ni steel and high corrosion resistant austenitic stainless steel , And a flux cored wire of a Ni-based alloy from which a weld metal having good strength, toughness, fault resistance, high temperature cracking resistance and corrosion resistance can be obtained.

As a result of intensive studies, the present inventors have found the following.

Since the Ni-based alloy has a low melting point, the molten metal is easily sagged in electron welded welding. Therefore, in order to obtain a smooth bead shape in electron welded welding, it is necessary to raise the solidification temperature of the slag to suppress the molten metal from being deposited in the solidified slag. In order to increase the solidification temperature of the slag, it is necessary to increase the addition amount of the oxide having a high melting point in the slag forming agent and to avoid adding an oxide having a melting point as low as possible. Based on this idea, a Ni-based alloy flux cored wire having a slag composition excellent in slag detachment while maintaining a high melting point slag composition was developed.

In order to solve the above problems, the present invention takes the following technical means.

The Ni-based alloy flux cored wire according to the present invention is a Ni-based alloy flux cored wire in which flux is filled in the shell of a Ni-based alloy. The Ni-based alloy flux cored wire is composed of 52 to 65 mass% Ni, TiO ₂ : 4.0 to 12.0 mass%, SiO ₂ : 0.05 to 0.60 mass%, ZrO ₂ : 0.1 to 10 mass%, Mo: 7.0 to 10.0 mass%, and Nb: 3.0 to 5.0 mass% ₂ : 1.0 to 4.0 mass%, MnO ₂ : 0.3 mass% or less and Al ₂ O ₃ : 1.0 mass% or less, and the alkali metal compound of Na, K, In terms of metal, 0.1 to 2.0% by mass in total, and 0.1 to 1.0% by mass in terms of fluoride in terms of fluoride.

According to this structure, Ni-based alloy flux cored wire (hereinafter referred to as flux cored wire or simply wire) is stabilized by stabilizing the austenite structure by adding a predetermined amount of Ni, By adding Cr, Mo and Nb, the strength and corrosion resistance of the weld metal are improved.

Further, by adding a predetermined amount of TiO ₂ , the flux cored wire is formed with slag having uniform and good cohesiveness, and arc stability is improved. In addition, the slag melting point is increased, and the shape of the bead in the electric welding is made flat . Further, by adding a predetermined amount of SiO ₂ , the viscosity of the slag becomes high, and the slag covering becomes uniform, whereby the slag releasability becomes good. Further, by adding a predetermined amount of ZrO ₂ , the slag solidification is accelerated, and a flat bead shape in an inclined posture and an upward posture can be obtained. Further, by regulating the addition amount of MnO ₂ , the lowering of the slag solidification temperature is suppressed, and deterioration of the bead shape of the electron welder is suppressed. Further, by controlling the addition amount of Al ₂ O ₃ , deterioration of slag peeling can be suppressed.

In addition, in the flux cored wire, by adding a predetermined amount of an alkali metal compound of Na, K, and Li, arc stability is improved, and by adding a predetermined amount of fluoride, pore defects due to moisture are reduced.

The Ni based alloy flux cored wire according to the present invention contains a Ca compound, a Ba compound and a Bi compound as a slag forming agent, and each of these compounds contains 0.5 mass% or less, 0.5% by mass or less in terms of Ba and 0.01% or less by mass in terms of Bi.

According to such a constitution, the flux cored wire restricts the addition amount of the Ca compound and the Ba compound so that the lowering of the slag melting point is suppressed, and deterioration of the welding workability of the electric wire is suppressed. As a result, slag detachment is more favorable, and a flat bead shape is easier to obtain from an electron beam. Further, by regulating the addition amount of the Bi compound, deterioration of the high-temperature cracking resistance of the weld metal is suppressed.

The Ni-based alloy flux cored wire according to the present invention contains an oxide and a carbonate as a slag forming agent, and an oxide of Ti, Zr, Si, Ca, Mn, Ba and an oxide of Ti, Zr, Si, (TiO ₂ + ZrO ₂ ) / (SiO ₂ + CaO + MnO ₂ + BaO): 5 to 50, in terms of oxide, with respect to the carbonate of Ca, Mn and Ba.

According to this constitution, the flux cored wire defines (TiO ₂ + ZrO ₂ ) / (SiO ₂ + CaO + MnO ₂ + BaO) so that the welding workability in electronic taxation and the adaptation of slag are compatible. As a result, a bead shape that is more flat in electron sheath is obtained, and the slag peeling property is also better.

The Ni-based alloy flux cored wire of the present invention can obtain a weld metal having excellent bead shape in electron weldability such as Ni-based alloy, 9% Ni steel and high corrosion resistant austenitic stainless steel, And slag peeling are excellent. Further, the Ni-based alloy flux cored wire of the present invention can obtain a weld metal having good strength, toughness, fault resistance, high temperature crack resistance and corrosion resistance.

Hereinafter, embodiments of the present invention will be described in detail.

The flux cored wire of the present invention is a Ni-based alloy flux cored wire in which flux is filled in the shell of a Ni-based alloy. The flux cored wire contains a predetermined amount of Ni, Cr, Mo, and Nb per total mass of the flux cored wire. The flux cored wire contains TiO ₂ , SiO ₂ , ZrO ₂ , MnO ₂ , Al ₂ O ₃ And a predetermined amount of an alkali metal compound of Na, K, and Li in terms of alkali metal and a predetermined amount of fluoride in terms of fluorine in a total amount of the wire in the flux.

Hereinafter, the reason for limiting the components of the flux cored wire will be described.

≪ Ni: 52 to 65 mass%

Ni is added to stabilize the austenite structure. If the Ni content is less than 52 mass%, the content of the other elements is relatively increased, the structure becomes unstable, and the toughness deteriorates. On the other hand, when the Ni content exceeds 65 mass%, the amount of addition of Cr, Mo, Nb, and the like is relatively low, and corrosion resistance and strength are deteriorated. Therefore, the Ni content of the flux cored wire is set to 52 to 65 mass% per mass of the wire. The Ni content is preferably 55 mass% or more, and more preferably 58 mass% or more, from the viewpoint of making the structure more stable. From the viewpoint of further improving the corrosion resistance and strength, it is preferably 62 mass% or less, and more preferably 61 mass% or less.

≪ Cr: 18 to 23 mass%

Cr has an effect of improving the strength and corrosion resistance of the weld metal. If the Cr content is less than 18 mass%, corrosion resistance is deteriorated. On the other hand, if the Cr content exceeds 23 mass%, the toughness of the weld metal deteriorates. Therefore, the Cr content in the flux cored wire is set to 18 to 23 mass% per mass of the wire. The Cr content is preferably at least 19 mass%, and more preferably at least 20 mass%, from the viewpoint of further improving the corrosion resistance. From the standpoint of further improving the toughness, it is preferably not more than 22 mass%, more preferably not more than 21.5 mass%.

≪ Mo: 7.0 to 10.0 mass%

Mo has the effect of improving the strength and corrosion resistance of the weld metal in the same manner as Cr. If the Mo content is less than 7.0 mass%, the corrosion resistance is deteriorated. On the other hand, if the Mo content exceeds 10.0 mass%, the toughness of the weld metal deteriorates. Therefore, the Mo content in the flux cored wire is set to 7.0 to 10.0 mass% per mass of the wire. The Mo content is preferably 7.5% by mass or more, and more preferably 8.0% by mass or more, from the viewpoint of further improving the corrosion resistance. From the viewpoint of further improving toughness, it is preferably 9.0 mass% or less, more preferably 8.8 mass% or less.

<Nb: 3.0 to 5.0 mass%>

Nb is a solid solution strengthening element and has an effect of improving the strength of the weld metal. If the Nb content is less than 3.0 mass%, the strength is deteriorated. On the other hand, if the Nb content exceeds 5.0 mass%, the toughness of the weld metal deteriorates. Therefore, the Nb content in the flux cored wire is set to 3.0 to 5.0 mass% per mass of the wire. The Nb content is preferably at least 3.15% by mass, and more preferably at least 3.3% by mass from the viewpoint of further improving the strength. From the viewpoint of further improving the toughness, it is preferably 4.5 mass% or less, more preferably 4.2 mass% or less.

<TiO ₂ : 4.0 to 12.0 mass% in the flux>

TiO ₂ is a main component of the slag forming agent, and it has an effect of improving the arc stability by forming slag having uniform and good foaming property. The addition of TiO ₂ also has the effect of increasing the slag melting point and flattening the shape of the bead in the electron welder. If the TiO ₂ content is less than 4.0 mass%, the above effect can not be obtained. On the other hand, if the content of TiO ₂ exceeds 12.0% by mass, the flux hardly melts and the flux column melts and becomes a cause of inclusion of slag. Therefore, the content of TiO _{2 in the} flux is set to 4.0 to 12.0 mass% per mass of the wire. The TiO ₂ content is preferably 5.0% by mass or more, and more preferably 5.5% by mass or more, from the viewpoint of further improving the above effects. Further, it is preferably not more than 10.0 mass%, more preferably not more than 9.0 mass% from the viewpoint of facilitating the melting of the flux.

<SiO ₂ : 0.05 to 0.60 mass% in the flux>

SiO ₂ enhances the viscosity of the slag and uniformizes the slag coverage, thereby improving the slag peeling property. If the SiO ₂ content is less than 0.05 mass%, the above effect can not be obtained. On the other hand, if the SiO ₂ content exceeds 0.60 mass%, SiO ₂ is reduced by a strong deoxidizing element such as Ti, and therefore Si is increased in the weld metal, resulting in deterioration of the toughness of the weld metal. Further, the melting point of the slag is lowered, and the shape of the bead in the electron welder is deteriorated. Therefore, the content of SiO _{2 in the} flux is set to 0.05 to 0.60 mass% per mass of the wire. The SiO ₂ content is preferably 0.20 mass% or more, and more preferably 0.30 mass% or more, from the viewpoint of further improving the above effect. From the viewpoint of further improving the toughness and from the viewpoint of improving the bead shape, it is preferably 0.55 mass% or less, more preferably 0.50 mass% or less.

<ZrO ₂ : 1.0 to 4.0 mass% in the flux>

ZrO ₂ has the effect of accelerating the solidification of the slag and obtaining a flat bead shape in the inclined posture and the upward posture. If the ZrO ₂ content is less than 1.0% by mass, the above effect can not be sufficiently obtained. On the other hand, if the content of ZrO ₂ exceeds 4.0 mass%, deterioration of the slag foaming property is caused and the slag peeling property is significantly deteriorated. Therefore, the content of ZrO _{2 in the} flux is set to 1.0 to 4.0 mass% per mass of the wire. The ZrO ₂ content is preferably 1.5% by mass or more, and more preferably 1.8% by mass or more, from the viewpoint of further improving the above effects. From the viewpoint of further improving the slag releasability, it is preferably 3.0 mass% or less, more preferably 2.8 mass% or less.

<MnO _2: 0.3% or less by mass in the flux>

MnO ₂ lowers the slag solidification temperature and deteriorates the bead shape of the electron weld. Therefore, the content of MnO _{2 in the} flux is 0.3 mass% or less per mass of the wire. The MnO ₂ content is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, from the viewpoint of further suppressing the deterioration of the bead shape. On the other hand, the lower limit is not specifically defined, but MnO ₂ is preferably not contained. However, since MnO ₂ is inevitably incorporated, substantially 0.001 mass% is the lower limit value.

<Al ₂ O _3: more than 1.0% by weight of the fluxes>

Al ₂ O ₃ causes deterioration of slag releasability. Therefore, the content of Al ₂ O _{3 in the} flux is set to 1.0 mass% or less per mass of the wire. The Al ₂ O ₃ content is preferably 0.8 mass% or less, more preferably 0.6 mass% or less, from the viewpoint of further suppressing deterioration of slag releasability. On the other hand, the lower limit is not specifically defined, but it is preferable that Al ₂ O ₃ is not contained. However, since Al ₂ O ₃ is inevitably incorporated, substantially 0.001 mass% is the lower limit value.

<Sum of alkali metal conversion values of alkali metal compounds of Na, K and Li: 0.1 to 2.0 mass% in the flux>

Alkali metals such as Na, K, and Li have an effect of improving arc stability. These can be added as fluorides or complex oxides, and the total amount of Na, K, and Li in terms of alkali metals is set to 0.1 to 2.0 mass%. If the total of Na, K and Li is less than 0.1% by mass, the arc stability is deteriorated. On the other hand, if it exceeds 2.0 mass%, the melting point of the slag is lowered and the bead shape in the electron welder is deteriorated. Therefore, the total of Na, K and Li in the flux is set to 0.1 to 2.0 mass% per mass of the wire. The total of Na, K and Li is preferably not less than 0.3% by mass, more preferably not less than 0.5% by mass, from the viewpoint of further improving the arc stability. From the viewpoint of better bead shape, it is preferably 1.5% by mass or less, more preferably 1.2% by mass or less.

&Lt; Fluorine conversion value of fluoride: 0.1 to 1.0 mass% in flux >

Fluorine has an effect of reducing water-borne pore defects. When the fluoride conversion value of the fluoride is less than 0.1% by mass, the effect of reducing the pore defects can not be obtained. On the other hand, if the fluoride conversion value of the fluoride exceeds 1.0% by mass, the arc stability is deteriorated. Further, the shape of the beads in the electron welder deteriorates. Therefore, the fluoride conversion value of the fluoride in the flux is set to 0.1 to 1.0% by mass based on the total mass of the wire. The fluoride conversion value of the fluoride is preferably not less than 0.3% by mass, more preferably not less than 0.4% by mass, from the viewpoint of further improving the effect of reducing pore defects. Further, it is preferably 0.9 mass% or less, more preferably 0.8 mass% or less, from the viewpoint of better arc stability and bead shape.

On the other hand, the alkali metal compound also includes an alkali metal fluoride, and the term &quot; fluoride &quot; also includes an alkali metal fluoride. That is, the term &quot; fluoride &quot; herein includes fluorides other than NaF, KF and LiF.

In addition, the remainder of the flux is Mn, W, Fe and inevitable impurities.

<Remnant: Inevitable impurities>

The balance of the components as a whole of the flux cored wire is an inevitable impurity. Examples of the inevitable impurities include C, Si, P, S, Cu, V, N and the like.

The flux cored wire contains a Ca compound, a Ba compound and a Bi compound as a slag forming agent, and the flux cored wire contains a predetermined amount of these compounds per Ca mass conversion value, Ba conversion value, and Bi conversion value desirable.

&Lt; Ca conversion value relative to Ca compound: 0.5 mass% or less >

Ca lowers the melting point of the slag and deteriorates the workability of welding of the electron beam. By reducing Ca, slag peeling is better and a bead shape that is more flat than that of an electron beam is easily obtained. Therefore, the content of the Ca compound is preferably 0.5% by mass or less in terms of Ca, based on the total mass of the wire. The content of the Ca compound is preferably not more than 0.1% by mass in terms of Ca, more preferably not more than 0.05% by mass in terms of Ca, from the viewpoint of further improving the workability of welding and further improving the bead shape to be. On the other hand, the lower limit is not specifically defined, but it is preferable that the Ca compound is not contained. However, since Ca is inevitably incorporated, the lower limit value is substantially 0.001 mass% in terms of Ca conversion.

&Lt; Ba conversion value relative to Ba compound: 0.5 mass% or less >

Ba lowers the melting point of the slag and deteriorates the workability of welding of the electron beam. By reducing Ba, slag peeling is better and a bead shape that is more flat than the electron beam is easily obtained. Therefore, the content of the Ba compound is preferably 0.5% by mass or less in terms of Ba, based on the total mass of the wire. The content of the Ba compound is preferably not more than 0.1% by mass in terms of Ba, more preferably not more than 0.05% by mass in terms of Ba, from the viewpoint of further improving the workability of welding and further improving the bead shape to be. On the other hand, the lower limit is not specifically defined, but it is preferable that Ba compound is not contained. However, since Ba is inevitably incorporated, the lower limit value is substantially 0.001 mass% in terms of Ba.

&Lt; Bi conversion value relative to Bi compound: 0.01 mass% or less >

Bi is segregated in the final solidification region as a low melting point oxide in the weld metal, deteriorating the high temperature cracking resistance of the weld metal. Therefore, it is preferable that the content of the Bi compound is 0.01 mass% or less in Bi conversion value per mass of the wire. The content of the Bi compound is more preferably 0.001 mass% or less in terms of Bi, and more preferably 0.0005 mass% or less in terms of Bi, from the viewpoint of further improving the high temperature cracking resistance. On the other hand, the lower limit is not specifically defined, but it is preferable that the Bi compound is not contained. However, since Bi is inevitably incorporated, 0.0001 mass% in terms of Bi substantially becomes the lower limit value.

The flux cored wire contains oxides and carbonates as slag forming agents, and the oxides of Ti, Zr, Si, Ca, Mn, and Ba and the carbonates of Ti, Zr, Si, Ca, (TiO ₂ + ZrO ₂ ) / (SiO ₂ + CaO + MnO ₂ + BaO) in terms of oxide is preferably within a predetermined range.

(TiO ₂ + ZrO ₂ ) / (SiO ₂ + CaO + MnO ₂ + BaO) in terms of oxides for oxides and carbonates of Ti, Zr, Si, Ca,

By adjusting the balance of Ti, Zr, Si, Ca, Mn, and Ba to be added as a slag forming agent, it is possible to achieve compatibility between welding workability and slag adaptability in the electronic industry. As a result, a bead shape that is more flat in electron sheath is obtained, and the slag peeling property is also better. (TiO ₂ + ZrO ₂ ) / (SiO ₂ + CaO + MnO ₂ + BaO) is 5 or more in terms of oxides of oxides and carbonates of Ti, Zr, Si, Ca, Mn and Ba, And the workability of welding in the electronic industry is improved. On the other hand, when (TiO ₂ + ZrO ₂ ) / (SiO ₂ + CaO + MnO ₂ + BaO) is 50 or less, the compliance of the slag is easily improved and the practical level can be more easily maintained with respect to the slag peeling property. (TiO ₂ + ZrO ₂ ) / (SiO ₂ + CaO + MnO ₂ + BaO) in terms of oxides of oxides and carbonates of Ti, Zr, Si, Ca, Mn and Ba is 5 to 50 desirable. (TiO ₂ + ZrO ₂ ) / (SiO ₂ + CaO + MnO ₂ + BaO) is more preferably 10 or more, and more preferably 12 or more, from the viewpoint of further improving the welding workability. From the viewpoint of further improving the compliance of the slag and making it easier to maintain the slag releasability more preferably 40 or less, more preferably 30 or less.

On the other _{hand, TiO 2, SiO 2, ZrO} 2, MnO 2 herein are not to be contained in addition to _{TiO 2, SiO 2, ZrO 2} , MnO 2 in the above-described flux. This equation is derived experimentally.

The above-described flux cored wire of the present invention can be suitably used for gas shielded arc welding using an Ar + CO ₂ mixed gas for welding low temperature steel such as 9% Ni steel or various high Ni alloys.

<Manufacturing method of flux cored wire>

The flux cored wire can be produced by a method in which a flux is spread in the longitudinal direction of the strip steel and is then wrapped and formed into a circular cross section to draw wire or a method of filling a steel pipe of a large diameter with a flux There is a fresh way. However, since either method does not affect the present invention, either method may be used. There is also a seam, and there is no seam, but it can be either.

Example

Hereinafter, examples falling within the scope of the present invention will be described in comparison with comparative examples deviating from the scope of the present invention.

First, flux cored wires having the chemical compositions of the wires shown in Table 2 below were prepared using the shells of the chemical components shown in Table 1 below. The chemical composition of the wire is% by mass with respect to the total mass of the wire. The wire diameter of the flux cored wire was 1.2 mm, and the flux rate was 17 to 27 mass%.

In the table, numbers that do not satisfy the scope of the present invention are indicated by underlining numerical values. Further, &quot; Na + K + Li &quot; is the sum of alkali metal conversion values of alkali metal compounds of Na, K and Li, and F, Ca, Ba and Bi are conversion values of these compounds, respectively. Further, the formula is "(TiO ₂ + ZrO ₂ ) / (SiO ₂ + CaO + MnO ₂ + BaO)".

Using these flux cored wires, the shape of the beads in the arc stability, the slag releasing property, and the upward and upward welding position was evaluated as welding workability. Further, tensile strength, toughness, fault resistance, resistance to hot cracking, and corrosion resistance were evaluated as the weld metal performance.

Welding workability was evaluated by fillet welding of the bending direction. More specifically, welding workability was evaluated by performing welding at a welding current (150 to 180 A) and an arc voltage (24 to 27 V) using 80% Ar-20% CO ₂ as a shielding gas.

The tensile strength and toughness of the weld metal were evaluated in accordance with AWS B4.0.

The fault tolerance of the weld metal was evaluated by performing the RT test of AWS A5.11.

The high temperature cracking resistance of the weld metal was evaluated by performing a FISCO crack test and examining the presence or absence of cracks by performing a penetration test on the surface of the bead immediately after welding.

The corrosion resistance of the weld metal was evaluated using the ASTM G48 C method.

The evaluation criteria are as follows.

<Arc Stability>

With respect to the arc stability, it was confirmed that spraying was carried out, the volume was small, the spatter was small (very good) (⊚), the volume transfer was close to the spray transfer and the spatter was relatively small, (X) that a large volume and a large amount of spatter were generated.

&Lt; Slag peeling property &

As for the slag releasability, it was determined that the slag was naturally peeled off very well (O), the peeled off by hitting with a hammer was good (?), And the slag was peeled off the bead surface and was not peeled off.

&Lt; Bead shape in the bending direction welding position >

For the bead shape in the bidirectional up and down welding posture, the bead shape satisfying the acceptance criteria of the fillet of AWS A5.34, the bead shape of the flat shape being extremely good (O), the bead shape satisfying the acceptance criteria of the fillet of AWS A5.34 (∘), and it was determined that a convex bead did not satisfy the criteria of AWS A5.34 and that it was defective (×).

<Tensile Strength>

The tensile strength was determined to be good (O) when 690 MPa or more was obtained and poor (X) when it was less than 690 MPa.

<Humanity>

The toughness was evaluated by a Charpy impact test at -196 캜. Good (?) Indicates that the absorbed energy is 50 J or more, and poor (x) indicates that the absorbed energy is less than 50 J.

<Fault tolerance>

The fault tolerance was evaluated as satisfactory (○) satisfying the acceptance criteria of the RT test of AWS A5.11, and bad (×) not satisfying the acceptance criteria of the RT test of AWS A5.11.

<High temperature cracking resistance>

The high-temperature cracking resistance was evaluated by FISCO crack test. The test was conducted at a welding current of 200 A and a welding speed of 40 cpm to determine that no crack occurred (?) And the crack occurred (poor).

<Corrosion resistance>

With respect to the corrosion resistance, in the ASTM G48 C method, it was judged to be good (O) when CPT 50 deg.

In the comprehensive evaluation, the welding workability was all?, The welding metal performance was all?, That at least one of the welding workability was?, The welding metal performance was all?, The welding workability and welding Among the metal performances, those with x marks were evaluated as x.

The results are shown in Table 3.

As shown in Table 3, in the case of No. 4 that satisfies the range of the present invention. 1 to 16 were good in welding workability and weld metal performance.

On the other hand, in the case of No. &quot; No. &quot; 17 to 35 gave the following results.

No. 17 had a low Mo content, the corrosion resistance of the weld metal deteriorated. No. 18 had a low content of Na + K + Li, and thus the arc stability deteriorated. No. 19 had a low Nb content, the tensile strength of the weld metal deteriorated greatly. No. 20 had a high TiO ₂ content, so that the flux hardly melted and the fault resistance was deteriorated.

No. 21 had a low Cr content, so that the corrosion resistance of the weld metal deteriorated. No. 22 had a high content of Na + K + Li, the slag melting point was lowered, and the bead shape in the upward and upward welding posture deteriorated. No. 23 had a high Ni content, it was impossible to appropriately add Cr and Mo, and the tensile strength and corrosion resistance of the weld metal deteriorated. No. 24 had a low F content, so that blowholes due to moisture were liable to be generated, and the defect resistance was deteriorated.

No. 25 had a high Mo content, the toughness of the weld metal deteriorated. No. 26 had a high Cr content, so that the toughness of the weld metal deteriorated. No. 27 had a low content of SiO ₂ , the slag peeling property deteriorated. No. 28 had a high Nb content, so that the toughness of the weld metal deteriorated. No. 29 had a high content of ZrO ₂ , the slag releasability deteriorated. No. 30 had a high content of SiO ₂ , the slag melting point was lowered, and the bead shape in the upward and upward welding posture deteriorated. In addition, the amount of Si in the weld metal increased and the toughness deteriorated.

No. 31 had a low Ni content, and toughness deteriorated. In addition, since the Al ₂ O ₃ content was high, the slag peeling property deteriorated. No. 32 had a low TiO ₂ content, the bead shape in the upward and upward welding posture deteriorated. No. 33 had a low content of ZrO ₂ , the bead shape in the upward and upward welding posture deteriorated. No. 34 had a high F content, so that the arc stability and the shape of the beads in the upward and backward welding posture deteriorated. No. 35 had a high content of MnO ₂ , the bead shape in the orientation upward welding position deteriorated.

While the present invention has been described in detail with reference to the embodiment, it is to be understood that the scope of the present invention is not limited to the above-described embodiments but is broadly construed based on the description of the claims. It is needless to say that the content of the present invention can be widely modified or changed on the basis of the above description.

Claims (3)

A Ni-based flux cored wire filled with a flux in an outer surface of a Ni-based alloy,
Per total mass of wire,
Ni: 52 to 65 mass%
18 to 23 mass% of Cr,
Mo: 7.0 to 10.0 mass%
Nb: 3.0 to 5.0 mass%
&Lt; / RTI &gt;
In the flux,
TiO ₂ : 4.0 to 12.0 mass%
0.05 to 0.60% by mass of SiO ₂ ,
ZrO _2: 1.0~4.0 mass%
MnO _2: 0.3% by mass or less,
Al ₂ O ₃ : not more than 1.0% by mass
Lt; / RTI &gt;
In the flux,
A total of 0.1 to 2.0 mass% of alkali metal compounds of Na, K and Li in terms of alkali metal, and 0.1 to 1.0 mass% of fluoride in terms of fluorine,
Wherein the oxides and carbonate of the Ti, Zr, Si, Ca, Mn, Ba and the carbonate of Ti, Zr, Si, Ca, Mn and Ba contained in the oxides and the carbonates as the slag forming agent, Wherein the Ni-based alloy flux cored wire is (TiO ₂ + ZrO ₂ ) / (SiO ₂ + CaO + MnO ₂ + BaO): 5 to 50. The method according to claim 1,
A Ca compound, a Ba compound, and a Bi compound as a slag forming agent, and these compounds each contain 0.5 mass% or less in terms of Ca, 0.5 mass% or less in Ba and 0.5 mass% or less in terms of Bi, 0.01% or less by mass of the Ni-based alloy flux cored wire. delete