KR101923806B1 - Stainless steel flux cored wire - Google Patents

Abstract

[PROBLEMS] To provide a stainless steel flux cored wire excellent in tensile strength, toughness at low temperature, fault resistance, and high temperature crack resistance.
[MEANS FOR SOLVING THE PROBLEMS] The steel wire according to the present invention is characterized in that it contains 0.04 mass% or less of C, 0.8 mass% or less of Si, 0.5 to 5.0 mass% of Mn, 3.0 mass% or less of Cu, 13 to 33 mass% of Ni, TiO ₂ : 4.0 to 12.0 mass% per 29 mass% of wire, 2.0 to 6.0 mass% of Mo, 1.0 mass% or less of Nb and 0.08 to 0.25 mass% of N, , SiO _2: 0.05~3.0% by weight, ZrO _2: 0.5~5.0% by weight, Al ₂ O _3: about 2.0% or less, Bi in terms of Bi compound value: 0.01% by mass or less, in terms of alkali metal with respect to the alkali metal compound , And 0.1 to 1.0 mass% of a fluorine-converted value with respect to the fluoride, based on the total weight of the stainless steel flux cored wire.

Description

[0001] STAINLESS STEEL FLUX CORED WIRE [0002]

The present invention relates to a stainless steel flux cored wire which becomes a complete austenitic structure for use in welding stainless steel or 5% Ni steel for low temperature applications.

Stainless steel welding materials are used for welding stainless steel having excellent corrosion resistance and heat resistance and are widely applied in various industrial fields. On the other hand, a Ni-based alloy welding material is often used because a high strength property and impact performance at low temperature are required for a welding material of 5% Ni steel used as a structural member of storage tanks such as LEG.

Since conventional stainless steel welding materials can not satisfy the specifications of strength and impact performance, they are rarely used for welding 5% Ni steel.

For example, Patent Document 1 discloses a Ni-based alloy flux cored wire for low temperature steel welding having excellent mechanical performance.

Also, Patent Document 2 discloses a cryogenic stainless steel coated arc welding electrode for a stainless steel used in a structure for a superconducting coil, which has excellent impact performance at an extremely low temperature.

Japanese Patent Laid-Open No. 2001-334392 Japanese Patent Laid-Open No. 07-124784

However, the Ni-based alloy flux cored wire disclosed in Patent Document 1 has a high content of alloys such as Ni, Cr, and Mo as compared with stainless steels, resulting in high cost. In addition, the stainless steel-coated arc welding electrode disclosed in Patent Document 2 has insufficient strength characteristics at room temperature and is also a coated arc welding electrode, resulting in low welding efficiency.

In view of the above, it is an object of the present invention to provide a stainless steel flux cored wire having low cost and high welding efficiency as compared with a Ni-based alloy in welding austenitic stainless steel and 5% Ni steel for low- And to provide a stainless steel flux cored wire in which a weld metal excellent in strength and impact performance at low temperatures can be obtained.

More specifically, the present invention is a stainless steel flux cored wire used for welding austenitic stainless steel and 5% Ni steel for low-temperature use, and is excellent in tensile strength, toughness at low temperatures, And to provide a stainless steel flux cored wire having excellent properties.

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

That is, when the weld metal becomes a two-phase structure of austenite-ferrite including a ferrite structure, the ferrite phase is brittle at low temperature, and the impact performance is markedly deteriorated. Therefore, in order to attain the low temperature toughness required for the weld metal of 5% Ni steel, the chemical composition of the weld metal is adjusted in the present invention so as to become a complete austenite structure.

In the case of a complete austenite structure, high-temperature cracks tend to occur. It is known that in order to lower the susceptibility to high-temperature cracking, impurities such as P and S that generate low melting point compounds are lowered.

It has been confirmed that Bi added for the purpose of improving the slag releasing property of the slag flux cored wire in general also produces a low melting point oxide and enhances high temperature crack susceptibility, We decided to do with nothing.

The reduction of P and S and the addition of no Bi alone were insufficient for improving the high temperature cracking resistance. Therefore, the present invention also noted the effect of various alloying elements.

It is considered that the alloying element is concentrated in the final solidification zone of the weld metal by the solidification segregation and the melting point of the molten metal is lowered to enhance the high temperature crack susceptibility. In the present invention, microstructure observation or thermodynamic simulation was used to examine the influence of alloying elements.

As a result, it is possible to effectively improve the high-temperature cracking resistance by suppressing the addition amount of Si, which is effective for promoting segregation of alloying elements such as C and Cr and Mo, I found that.

In addition, it is generally known that Mn is an element which forms MnS and improves high-temperature cracking resistance. In the case of a completely austenite structure, 5 to 7% of Mn is added (refer to Japanese Patent Application Laid-Open No. Hei 07-124784) And so on.

However, the excessive addition accelerates the solidification segregation of the Mn itself, resulting in lowering of the melting point of the final solidification region, and in turn, deteriorating the hot cracking resistance. Therefore, in the present invention, it has been found that it is necessary to adjust the Mn content to a suitable range slightly lower.

Further, in the present invention, it has been found that addition of interstitial solid solution strengthening elements such as C and N is effective for improving the tensile strength of the weld metal to become a complete austenite structure. In order to obtain a high tensile strength at room temperature, It was decided to add a large amount of phosphorus. On the other hand, since C is an element that enhances the susceptibility to high-temperature cracking, it is designed to positively add N in the present invention.

However, it is known that, when the amount of N added is increased, bubbles are generated which are caused by supersaturated N when the weld metal solidifies, thereby increasing the risk of occurrence of blowholes and pits. Thus, in the present invention, it has been succeeded in reducing the risk of occurrence of pore defects by optimizing the slag composition of TiO ₂ , ZrO ₂ , SiO ₂ and Al ₂ O ₃ in the flux.

The inventors of the present invention obtained the above finding and, in view of the above problems, the present inventors have found that by adjusting the chemical composition of the weld metal, the low temperature toughness required of the weld metal can be attained and the addition amount of alloying elements such as C, Si, Mn, Cr, By setting the specific range, it has succeeded in improving the good high-temperature cracking resistance. Furthermore, by controlling the slag composition in the N and fluxes to a specific range, it has been succeeded to suppress the risk of occurrence of pore defects (fault tolerance) while realizing a high tensile strength at room temperature, thereby completing the present invention.

That is, the present invention relates to the following.

[1] A stainless steel flux cored wire filled with a flux on the outer surface of a stainless steel,

Per total mass of wire,

C: 0.04 mass% or less,

Si: 0.8 mass% or less,

Mn: 0.5 to 5.0 mass%

Cu: 3.0 mass% or less,

Ni: 13 to 33 mass%

Cr: 15 to 29 mass%

Mo: 2.0 to 6.0 mass%

Nb: 1.0 mass% or less, and

N: 0.08 to 0.25 mass%

In addition, in the flux,

TiO ₂ : 4.0 to 12.0 mass%

0.05 to 3.0% by mass of SiO ₂ ,

ZrO _2: 0.5~5.0 mass%

2.0% by mass or less of Al ₂ O ₃ ,

Bi conversion of Bi: 0.01 mass% or less,

0.1 to 2.0% by mass of the total of the alkali metal compounds composed of Na, K and Li in terms of alkali metals, and

And a fluorine conversion value of 0.1 to 1.0 mass% with respect to the fluoride.

[2] The stainless steel flux cored wire according to [1], wherein the content of each component contained in the wire satisfies the following relational expression.

A / B? 1.4

A = Ni + 30 x (C + N) + 0.5 x Mn + 12.4

B = Cr + Mo + 1.5 x Si + 0.5 x Nb

According to the stainless steel flux cored wire according to the present invention, in all-position welding such as cryogenic stainless steel, 5% Ni steel and high corrosion resistant austenitic stainless steel, excellent tensile strength, low temperature It is possible to obtain a weld metal having toughness, fault tolerance and high temperature cracking resistance.

Furthermore, by specifying the amounts of oxides of Ti, Si, Zr and Al in the oxide and carbonate added as the slag forming agent, a flat bead shape can be obtained from the electron beam, and the slag peeling property is also improved.

Hereinafter, embodiments for carrying out the present invention will be described in detail. On the other hand, the present invention is not limited to the embodiments described below.

The flux cored wire according to the present invention is a stainless steel flux cored wire filled with a flux on the outer surface of a stainless steel. The flux cored wire according to the present invention is a stainless steel flux cored wire in which Cu, Si, Mn, Cu, Ni, Cr, Mo, And further contains, in the flux, a predetermined amount of an alkali metal compound consisting of TiO ₂ , SiO ₂ , ZrO ₂ , Al ₂ O ₃ , Bi compound, Na, K and Li, and fluoride .

Hereinafter, content of each component of the flux cored wire according to the present invention will be described for the total mass of the wire.

<C: 0.04 mass% or less>

C is an element that improves the tensile strength of the weld metal, but is segregated in the final solidified portion of the weld metal, thereby lowering the melting point of the melt and deteriorating the hot cracking resistance. Therefore, the addition amount per total weight of the wire is suppressed to 0.04 mass% or less. When the C content exceeds 0.04 mass%, the susceptibility to high-temperature cracking increases. Further, it is preferably 0.03 mass% or less. Further, C is not required to be contained, but it is preferable that the content of C is 0.01% by mass or more for securing strength.

<Si: 0.8 mass% or less>

Si is also segregated in the final solidified portion of the weld metal to lower the melting point of the melt and deteriorate the hot crack resistance, so that the addition amount is suppressed to 0.8 mass% or less. When the Si content exceeds 0.8 mass%, solidification segregation is promoted, and high-temperature cracking susceptibility is enhanced. Further, it is preferably 0.6 mass% or less. In addition, Si is not required to be contained, but it is preferable that the Si content is 0.2% by mass or more for the purpose of securing the strength of the weld metal, securing low-temperature toughness, suppressing blowholes and the like.

&Lt; Mn: 0.5 to 5.0 mass%

Mn is added because it has the effect of suppressing the blowhole (BH) due to the oxygen-based gas due to the deoxidation effect and also has the effect of stabilizing the austenite structure. If the Mn content is less than 0.5% by mass, a sufficient deoxidation effect can not be obtained. On the other hand, when the Mn content exceeds 5.0 mass%, solidification segregation of Mn into the final solidification region of the weld metal is promoted, and the melting point of the melt is lowered, and high-temperature cracks are likely to occur. Therefore, the Mn content in the flux cored wire is set to 0.5 to 5.0 mass% per mass of the wire. Further, it is preferably not less than 1.0% by mass, and preferably not more than 4.0% by mass.

<Cu: 3.0 mass% or less>

When the content of Cu exceeds 3.0 mass%, Cu deteriorates the high-temperature cracking resistance. Therefore, the content of Cu is 3.0 mass% or less per total mass of the wire. Preferably not more than 2.5% by mass. The lower limit is not specifically defined, and Cu may be added to stabilize the austenite structure.

&Lt; Ni: 13 to 33 mass%

Ni is added to stabilize the austenite structure. If the Ni content is less than 13 mass%, the austenite structure becomes unstable. On the other hand, if the Ni content exceeds 33 mass%, the solubility of C or N lowers and BH tends to be generated. Therefore, the Ni content in the flux cored wire is set to 13 to 33 mass% for the entire wire mass. The Ni content is preferably at least 14 mass%. Further, it is preferably 30 mass% or less.

&Lt; Cr: 15 to 29 mass%

Cr has an effect of improving the strength of the weld metal and stabilizing the austenite phase. If the Cr content is less than 15 mass%, sufficient strength can not be obtained. On the other hand, when the Cr content exceeds 29 mass%, the toughness of the weld metal is deteriorated, and the solidification segregation of Cr is promoted and the high-temperature cracking resistance is deteriorated. Therefore, the Cr content in the flux cored wire is set to 15 to 29 mass% per mass of the wire. The Cr content is preferably at least 17 mass%. Further, it is preferably 27 mass% or less.

&Lt; Mo: 2.0 to 6.0 mass%

Mo, like Cr, has the effect of improving the strength of the weld metal. If the Mo content is less than 2.0% by mass, sufficient strength can not be obtained. On the other hand, if the Mo content exceeds 6.0% by mass, the toughness of the weld metal deteriorates, and solidification of Mo is promoted and the high-temperature cracking resistance is deteriorated. Therefore, the Mo content in the flux cored wire is set to 2.0 to 6.0 mass% per mass of the wire. The Mo content is preferably 2.5 mass% or more. Further, it is preferably 5.0 mass% or less.

<Nb: 1.0 mass% or less>

Nb may be added because it has an effect of improving the strength of the weld metal, but if it exceeds 1.0% by mass, the high-temperature cracking resistance is deteriorated. Therefore, the Nb content in the flux cored wire is set to 1.0 mass% or less. And preferably 0.8 mass% or less. There is no specific lower limit.

&Lt; N: 0.08 to 0.25 mass%

N is a solid solution strengthening element and has an effect of improving the strength of the weld metal. If the N content is less than 0.08 mass%, sufficient strength can not be obtained. On the other hand, when the N content exceeds 0.25 mass%, BH tends to occur. Therefore, the N content in the flux cored wire is set to 0.08 to 0.25 mass% per total wire mass. The N content is preferably 0.10 mass% or more. Further, it is preferably 0.20 mass% or less.

It is preferable that the content of each component contained in the wire satisfies the following relational expression in order to obtain a complete austenite structure.

A / B? 1.4

A = Ni + 30 x (C + N) + 0.5 x Mn + 12.4

B = Cr + Mo + 1.5 x Si + 0.5 x Nb

Here, the expression denoted by A means the equivalent amount of Ni, and the expression denoted by B means the equivalent amount of Cr. That is, when the value represented by A / B is 1.4 or more, a complete austenite structure is preferable. Further, A / B is more preferably 1.5 or more, and more preferably 1.6 or more.

The content of each component in the flux in the stainless steel flux cored wire according to the present invention per weight of the wire will be described below.

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

TiO ₂ is a main component of the slag forming agent, and has an effect of improving the arc stability by forming a slag which is uniform and encapsulated. 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 occurrence 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 mass% or more. Further, it is preferably 10.0 mass% or less.

<SiO ₂ : 0.05 to 3.0 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, when the SiO ₂ content exceeds 3.0% by mass, the solidification temperature of the slag is lowered, and the weld metal is liable to sag in the electron beam. Therefore, the content of SiO _{2 in the} flux is set to 0.05 to 3.0 mass% per mass of the wire. The SiO ₂ content is preferably 0.2 mass% or more. Further, it is preferably 2.0 mass% or less.

<ZrO ₂ : 0.5 to 5.0 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 0.5% by mass, the above effect can not be sufficiently obtained. On the other hand, if the ZrO ₂ content exceeds 5.0 mass%, the deterioration of the slag foaming property is caused and the slag peeling property is remarkably deteriorated. Therefore, the content of ZrO _{2 in the} flux is set to 0.5 to 5.0 mass% per mass of the wire. The ZrO ₂ content is preferably 1.0 mass% or more. Further, it is preferably 4.0 mass% or less.

<Al ₂ O ₃ : 2.0 mass% or less in the flux>

Al ₂ O ₃ causes deterioration of slag releasability. Therefore, the content of Al ₂ O _{3 in the} flux is 2.0 mass% or less per mass of the wire. The Al ₂ O ₃ content is preferably 1.5 mass% or less. On the other hand, the lower limit value is not specifically defined, but it is preferable that Al ₂ O ₃ is not contained.

&Lt; Total to alkali-metal converted value of alkali metal compound consisting of Na, K and Li: 0.1 to 2.0 mass% in flux >

Alkali metals such as Na, K, and Li have an effect of improving arc stability. These may be added as a fluoride or a composite oxide, and the alkali metal compound composed of Na, K and Li should be added in a total amount of 0.1 to 2.0 mass% in terms of alkali metal. 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 sum of Na, K and Li in the flux is an alkali-converted value, and is set to 0.1 to 2.0 mass% per mass of the wire. The sum of Na, K and Li is preferably 1.5 mass% or less.

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

Fluorine has an effect of reducing water-borne pore defects. If the fluorine conversion value to fluoride is less than 0.1% by mass, the effect of reducing pore defects can not be obtained. On the other hand, if the fluorine conversion value with respect to the fluoride exceeds 1.0% by mass, the arc stability is deteriorated. 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 0.2% by mass or more. Further, it is preferably 0.8 mass% or less.

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

Bi is segregated in the final solidification zone of the weld metal, deteriorating the hot cracking resistance of the weld metal. Therefore, the content of the Bi compound is set to be 0.01 mass% or less in terms of Bi, based on the total mass of the wire. The content of the Bi compound is preferably 0.001 mass% or less in terms of Bi. On the other hand, the lower limit value is not particularly specified, but it is preferable that the Bi compound is not contained.

<The balance of flux>

The remainder of the flux is added with Fe and Fe alloy, and the remainder of the flux is 30 to 65 mass% of the total mass of the wire. In addition, other inevitable impurities are included. The content of the inevitable impurities in the flux is preferably 1.0 mass% or less, more preferably 0.5 mass% or less, based on the total mass of the wire.

<Remainder of flux cored wire: inevitable impurities>

The balance of the components as a whole of the flux cored wire is an inevitable impurity. The inevitable impurities include, for example, P, S, Co, V and the like. The content of unavoidable impurities in the wire is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, based on the total mass of the wire. In particular, P and S are preferably 0.040 mass% or less in total in order to improve the high temperature cracking resistance.

The flux cored wire may contain a Ca compound and a Ba compound as a slag forming agent in addition to the above inevitable impurities. However, for these compounds, the Ca-converted value, the Ba-converted value Is preferably a predetermined amount as shown below.

&Lt; Ca conversion value relative to Ca compound: 1.0 mass% or less >

Ca lowers the melting point of the slag and deteriorates the workability of welding of the electron beam. By reducing Ca, a bead shape with a good slag releasing property and a flat electron shape can be obtained. Therefore, the content of the Ca compound is set to 1.0 mass% or less in terms of Ca, based on the total mass of the wire. The content of the Ca compound is preferably 0.5% by mass or less in terms of Ca. On the other hand, although the lower limit value is not specifically defined, it is preferable that the Ca compound is not contained.

&Lt; Ba conversion value relative to Ba compound: 1.0% or less >

Ba lowers the melting point of the slag and deteriorates the workability of welding of the electron beam. By reducing Ba, it is possible to obtain a bead shape which is further improved in slag releasing property and flat in electron sheathing. Accordingly, the content of the Ba compound is set to 1.0 mass% or less in terms of Ba, based on the total mass of the wire. The content of the Ba compound is preferably 0.5% by mass or less in terms of Ba. On the other hand, the lower limit value is not specifically defined, but it is preferable that the Ba compound is not contained.

The method of producing the flux cored wire according to the present invention is not particularly limited and may be manufactured by a general manufacturing process. For example, a stainless steel hoop is formed into a U-shape, a U-shaped shaping hoop is filled with flux, a flux is molded into a tubular shape filled in the inside, .

The material of the sheath can be used without particular limitation, such as a steel type of stainless steel, and the element composition in the total weight of the flux cored wire can be set within the above range.

The flux cored wire according to the present invention is not particularly limited as long as the shield gas used in the welding of the low temperature steel of 5% Ni steel or various austenitic stainless steels is used. For example, Ar gas, carbon dioxide gas (carbon dioxide, CO ₂ ), oxygen gas (O ₂ ), mixed gas thereof, and the like can be used. These may include oxygen, nitrogen, hydrogen, and the like as inevitable impurities.

In particular, it can be suitably used for gas shield arc welding using an Ar + CO ₂ mixed gas.

The same welding power source, welding torch, and feeder used in welding can be used in the same manner as in the conventional art.

<Welding materials>

The flux cored wire according to the present invention is preferably used for welding stainless steel or 5% Ni steel for low temperature applications. Preferred characteristics of the welded article using the wire are as follows.

(The tensile strength)

The tensile strength obtained in the test according to the weldment of the AWS B4.0 is more preferably not less than 570N / mm ² or greater preferred, and 600N / mm ^2.

(Low temperature toughness)

The toughness of the welded material is preferably 27 J or more and more preferably 34 J or more in Charpy test at -196 캜 according to AWS B4.0.

(Fault tolerance)

In the evaluation based on the RT test of AWS A5.22 of the welded product, it is preferable that the acceptance criteria are satisfied. More preferably, the number of defects having a diameter of 0.8 mm or more and the number of defects having a diameter of 0.4 mm or more and less than 0.8 mm is 10 or less .

(High temperature cracking resistance)

The bead surface immediately after welding can be evaluated by performing a penetration test on the surface of the bead and examining the presence or absence of cracks. More specifically, in the FISCO crack test, it is preferable that no crack is generated when the welding current is 180 A and the welding speed is 40 cpm, and it is more preferable that no crack occurs when the welding current is 200 A and the welding speed is 40 cpm .

(Arc stability)

The arc stability at the time of welding is preferably a volume transition close to the spray transfer and a relatively small spatter. It is more preferable that the volume is small and the spray is less spatter.

(Slag releasability)

The slag peeling property after welding is preferably such that the slag is peeled off with a force of not more than a degree of hitting with a hammer lightly, and it is more preferable that the slag peel off naturally.

(Intrinsic nature)

It is preferable that the bead shape satisfies the acceptance criteria of the fillet in accordance with AWS A5.22, and it is more preferable that the bead shape is a flat bead shape.

Example

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples, and it is possible to carry out the present invention by making changes within the scope of the present invention, And are included in the technical scope of the present invention.

&Lt; Examples 1 to 14 and Comparative Examples 1 to 10 &

A flux cored wire having the chemical composition shown in Table 2 was produced using the jacket having the chemical composition shown in Table 1.

The wire diameter of the obtained flux cored wire was all 1.2 mm, and the flux rate was 21 to 34 mass%.

On the other hand, the chemical compositions in Tables 1 and 2 are expressed in mass% with respect to the total mass of the wire. The term &quot; Bi &quot; means a Bi-converted value for a Bi compound, &quot; F &quot; means a fluorine-converted value for fluoride, &quot; Na + K + Li &quot; means an alkali metal converted value for an alkali metal compound composed of Na, K, Respectively. Further, "expression A" is a value represented by [Ni + 30 x (C + N) + 0.5 x Mn + 12.4] among the contents of each component contained in the wire, and "expression B" Of the content of [Cr + Mo + 1.5 x Si + 0.5 x Nb].

The properties of the obtained flux cored wire and the welded material welded using the wire were evaluated.

Specifically, tensile strength, low temperature toughness, fault resistance, and high temperature crack resistance were evaluated as the weld metal performance. Further, evaluation of arc stability, slag peeling property, and bead shape in the upward and upward welding position was evaluated as welding workability.

On the other hand, the workability of the welding was evaluated by fillet welding of the upper and lower sides. 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 concrete method of each evaluation is as follows, and the evaluation results are shown in Table 3.

(The tensile strength)

The tensile strength of the welded product was evaluated by a test in accordance with AWS B4.0. If the tensile strength of 600N / mm ² or more made by the ◎ (very good), and the evaluation, 570N / mm ² and less than 600N / mm ² ○ (good), less than 570N / mm ² as × (poor).

(Low temperature toughness)

Evaluation of low-temperature toughness was carried out by Charpy test at -196 캜 according to AWS B4.0. When the absorbed energy was 34 J or more, the evaluation was evaluated as? (Extremely good), and 27? To less than 34 J was rated? (Good) and less than 27 J was evaluated as? (Poor).

(Fault tolerance)

Evaluation of fault tolerance was carried out by RT test according to AWS A5.22. When the number of defects having a diameter of 0.8 mm or more and the number of defects having a diameter of 0.4 mm or more and less than 0.8 mm were 10 or less, the evaluation was rated as? (Extremely good) , And those that did not satisfy the acceptance criteria were rated as &quot; poor &quot;.

(High temperature cracking resistance)

Immediately after welding, the surface of the beads was subjected to a penetration test to determine whether or not cracks existed. Specifically, in the FISCO crack test, when the welding current is 200 A and the welding speed is 40 cpm, if the crack does not occur, the evaluation is evaluated as? (Extremely good), and when the welding current is 180 A and the welding speed is 40 cpm, (Good), a welding current of 180 A and a welding speed of 40 cpm.

(Arc stability)

The arc stability at the time of welding was evaluated as ⊚ (extremely good) when the volume was small and the spatter was small and the spatter was small, and the volume of the transition was close to that of the spray and the spatter was relatively small. It was determined that x (bad) was generated when the bulb was transferred and a large amount of spatter was generated.

(Slag releasability)

The slag peeling property after welding was determined to be? (Poor) when the slag was naturally peeled off (fairly good), the peeled off by lightly hitting with a hammer was good (good), and the slag was peeled on the bead surface and was not peeled off .

(Intrinsic nature)

(Very good) when the welding was performed in the direction of upward and upward welding, and the case of satisfying the criteria of the fillet according to AWS A5.22, (Good), and those which did not satisfy the determination criteria and became convex beads were evaluated as &quot; poor &quot;.

Claims (3)

A stainless steel flux cored wire filled with a flux on the outer surface of a stainless steel,
Per total mass of wire,
0.01 to 0.04 mass% of C,
0.2 to 0.8% by mass of Si,
Mn: 0.5 to 5.0 mass%
Cu: 3.0 mass% or less,
Ni: 13 to 33 mass%
Cr: 15 to 29 mass%
Mo: 2.0 to 6.0 mass%
Nb: 1.0 mass% or less, and
N: 0.08 to 0.25 mass%
In addition, in the flux,
TiO ₂ : 4.0 to 12.0 mass%
0.05 to 3.0% by mass of SiO ₂ ,
ZrO _2: 0.5~5.0 mass%
2.0% by mass or less of Al ₂ O ₃ ,
Bi conversion of Bi: 0.01 mass% or less,
0.37 to 2.0% by mass in terms of alkali metal equivalents relative to the alkali metal compound consisting of Na, K and Li, and
0.1 to 1.0 mass% in terms of fluorine with respect to the fluoride, and the balance of Fe and inevitable impurities. The method according to claim 1,
Wherein the content of each component contained in the wire satisfies the following relational expression.
A / B? 1.4
A = Ni + 30 x (C + N) + 0.5 x Mn + 12.4
B = Cr + Mo + 1.5 x Si + 0.5 x Nb 3. The method according to claim 1 or 2,
(B) a Ba conversion value of not more than 1.0% by mass (not more than 0%) with respect to the Ba compound, (A) a Ca conversion value of not more than 1.0% Or a combination thereof. The stainless steel flux cored wire according to claim 1,