JP3190224B2 - Submerged arc welding wire for stainless clad steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stainless steel submerged arc welding wire, and more particularly to a welding method capable of economically and efficiently welding clad steel and capable of easily obtaining a sound weld metal. It is about materials.

[0002]

2. Description of the Related Art Conventionally, latent arc welding of stainless clad steel involves welding of stainless steel on a joint material side, welding of a base material on a carbon steel (mild steel or low alloy steel) side, and welding of dissimilar materials between a joint portion and a base material. It is necessary to perform welding separately for each
A welding material suitable for welding at each part was selected, and welding was performed under appropriate welding conditions by combining a solid wire with a molten flux or a fired flux. At the time of welding, the replacement of the welding material is complicated, and there is a problem in terms of efficiency and economy because a welding material suitable for each part is used. In addition, the welded portion of the dissimilar material portion is liable to cause problems such as cracks in the weld metal and deterioration of corrosion resistance. Care must be taken especially in the selection of the welding material and the welding method.

In the welding of stainless steel and dissimilar materials, welding materials are selected so that the welding metal contains a few percent of ferrite in order to ensure crack resistance of the welding metal. The dilution of the base material is large, and it may be difficult to secure the required amount of ferrite. As a countermeasure, there is a method to reduce the dilution of the base material by low current welding, but not only the high efficiency welding by high current, which is the biggest feature of submerged arc welding, but also the problem that welding defects are likely to occur was there. In addition, there is a method of replenishing and adding alloy components such as Cr and Mo from the welding material to secure ferrite. However, adding alloy components from the flux causes the alloy components to be oxidized and depleted, and the alloy does not stably yield so that the welding metal is Has a problem that the target amount of ferrite is not contained.

On the other hand, when an alloy such as Cr or Mo for adding ferrite from a wire is added, the forging and drawing properties of a solid wire are deteriorated, so that the amount of addition is limited, so that productivity and economy are limited. There was also a problem. As another alloying method, there is a filling wire for filling a metal sheath with a flux containing an alloy component or the like. The desired alloy component can be added relatively easily and the productivity is good. Some of them have already been developed as a filling wire for stainless steel.
No. 97098 describes a welding method characterized by filling a wire with an alloying agent so that even if the welding current is reduced, good welding workability is achieved and dilution of the base material is reduced. . This method is related to overlay welding, and the purpose of this method is to lower the welding current and lower the dilution rate of the base material, so that efficient welding with a large current is difficult and economical. Welding cannot be performed.

In addition, the welding workability is improved by filling a stainless steel tubular pipe described in JP-A-58-135793 with a slag agent and a filler composed of a metal powder mainly composed of stainless steel powder of 25% or less. A submerged arc welding wire capable of adjusting the composition of a weld metal is disclosed. This is not to fill the wire with the alloying agent, but because the filler is made of slag and is intended to improve welding workability, the addition of alloy is sufficient even with this wire. Therefore, it is difficult to obtain a weld metal of the desired alloy component. Furthermore, Japanese Patent Application Laid-Open No. 2-197397 discloses a wire in which a metal powder containing O is filled in the outer skin of a low-C austenitic stainless steel, and the filled wire is a low-C stainless steel. The main purpose is to weld steel, and it is difficult to apply the method to welding of dissimilar materials where the base material such as clad steel made of carbon steel is greatly diluted.

Some of the present inventors have disclosed in Japanese Patent Application No. 6-129.
No. 932 filed an application for a multi-electrode inner surface latent arc welding method for a stainless clad steel pipe. This welding method is a method for obtaining the characteristics of the inner surface weld metal by restricting the groove shape on the laminated material side and welding with two or more electrodes. Uses wires. In this welding method, the base material side and the joining material side cannot be welded with the same welding material, and by using the wire of the present invention, it is possible to perform welding on both surfaces with the same welding material.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to a method of welding a cladding material and a base metal in a submerged arc welding of a clad steel by using a wire filled with a metal powder having an adjusted component in an outer skin of austenitic stainless steel. Welding of different materials and welding of dissimilar materials can be performed with the same welding material, but the corrosion resistance of the weld metal of the joint material, the resistance of the weld metal of the dissimilar material and the base material, An object of the present invention is to provide a stainless clad steel latent arc welding wire which has good cracking performance and enables economical and efficient welding.

[0008]

Means for Solving the Problems In order to conduct various studies on a submerged arc welding wire made of stainless clad steel, the present inventors used an austenitic stainless steel shell and prepared a metal powder blended so that the weld metal became a target component. A wire filled with was produced and a welding experiment was performed in combination with a commercially available flux. As a result, by controlling the components to a specific range and performing welding using a wire in which the Cr equivalent / Ni equivalent is adjusted to the specific range, the stainless steel as the joining material and the carbon steel as the base material are simultaneously welded. The corrosion resistance of the weld metal sufficiently satisfies the PID value of the following equation (2), which is an example of a method for evaluating the corrosion resistance performance (usually, good at> 25), and further does not cause σ embrittlement in the weld metal. It has been found that a ferrite is crystallized to a certain extent and a sound weld metal free of cracks can be obtained. In addition, when carbon steel on the base metal side is welded, martensite is prevented from being precipitated in the weld metal even when the base metal is diluted and the appropriate amount of ferrite is contained, so that crack resistance is excellent. We have also learned that metals can be easily obtained. PID = Cr + 3.3Mo + 16N (2)

The present invention has been made based on these findings. That is, the gist of the present invention is as follows: (1) A filler wire formed by filling an austenitic stainless steel sheath with a flux composed of an alloying agent. , As the total amount of components contained in one or both of the stainless steel shell and the flux, in terms of wire weight ratio,
C: 0.02 to 0.10%, Si: 0.05 to 1.0
%, Cr: 20 to 40%, Mo: 5.0 to 11.5%,
Mn: 0.3-5.0%, Ni: 6-16%, N: 0.
005 to 0.25%, the balance being Fe and other unavoidable components normally contained in the stainless steel shell, and the value A shown in the following formula (1) is 2.0 to 5.0. A latent arc welding wire for stainless clad steel, characterized in that: A = Cr equivalent (Cr + Mo + 1.5Si + 0.5Nb) / Ni equivalent (30C + 0.5Mn + Ni + 0.4Cu + 30N) (1) (2) Nb: 0. 02-4.0%, Cu: 0.05-
The latent arc welding wire for stainless clad steel according to the above (1), which contains 2.0% of one or two kinds.

[0010]

Hereinafter, the present invention will be described in detail. First, the outer skin will be described. The reasons for limiting the outer skin to austenitic stainless steel are as follows. The filling rate can be reduced, and component segregation hardly occurs in the weld metal, and the productivity is good. The outer skin of ferritic or martensitic stainless steel is basically inferior in workability and requires a large amount of alloy material to be added. Therefore, the filling rate is high, disconnection occurs frequently, and the productivity is extremely poor. Therefore, austenitic stainless steel is used as the outer skin.

Next, the reason for limiting the total amount of components contained in one or both of the stainless steel sheath and the filling flux will be described.

C: 0.02 to 0.10% C is required to be 0.02% or more in order to secure the strength and crack resistance of the carbon steel on the base metal side. However, if it exceeds 0.10%, the corrosion resistance of the stainless steel on the laminated material side is deteriorated. Therefore, C is limited to 0.02 to 0.10%.

Si: 0.05 to 1.0% Si is effective for improving the welding workability, particularly the bead shape and bead appearance. If it is less than 0.05%, there is no effect, and if it exceeds 1.0%, the crack resistance of the weld metal deteriorates. Therefore, Si is limited to 0.05 to 1.0%.

Mn: 0.3 to 5.0% Mn is effective for stabilizing the austenite phase like Ni. If the wire weight ratio is less than 0.3%, the effect is not recognized, and if it exceeds 5%, precipitation of ferrite in the weld metal is hindered and crack resistance is deteriorated. Therefore, Mn is limited to 0.3 to 5.0%.

Ni: 6 to 16% Ni stabilizes the austenite phase and is effective against non-oxidizing acids. If the wire weight ratio is less than 6%, sufficient corrosion resistance cannot be obtained, and if it exceeds 16%, not only the effect is saturated, but also the precipitation of ferrite in the weld metal is hindered and the crack resistance is deteriorated. Therefore, Ni is limited to 6 to 16%.

Cr: 20 to 40% Cr is a basic component of stainless steel and forms a passive oxide film and is effective against oxidizing acids. In order to ensure corrosion resistance, the wire weight ratio must be 20% or more, and 40%
If it exceeds, the weld metal becomes brittle due to precipitation of the σ phase. Therefore,
Limit Cr to 20-40%.

Mo: 5.0 to 11.5% Mo is extremely effective for obtaining high corrosion resistance in the form of coexistence with Cr, Ni and the like. If the wire weight ratio is less than 5.0%, sufficient corrosion resistance cannot be obtained. If the wire weight ratio exceeds 11.5%, a σ phase is precipitated like Cr and the weld metal is embrittled. Therefore, Mo
To 5.0-11.5%.

N: 0.005 to 0.25% N is extremely effective for obtaining high corrosion resistance in the form of coexistence with Cr, Ni, Mo and the like. It is also effective for stabilizing the austenite phase. 0.00 by wire weight ratio
If it is less than 5%, the effect is not obtained, and if it exceeds 0.25%, bubbles are generated in the weld metal, and a healthy weld metal cannot be obtained. Therefore, N is limited to 0.005 to 0.25%.

Nb: 0.02 to 4.0% Nb fixes C of the stainless steel on the laminated material side and improves corrosion resistance. It is also effective for solid solution strengthening to improve strength. 0.
If it is less than 02%, there is no effect, and if it exceeds 4.0%, the crack resistance of the weld metal deteriorates. Therefore, Nb is set to 0.02 to 4.
Limit to 0%.

Cu: 0.05-2.0% Cu is effective for improving the corrosion resistance to non-oxidizing acids. If the content is less than 0.05%, the effect is not obtained.
%, The effect saturates. Therefore, Cu is reduced to 0.
Restrict to 05-2.0%.

Other Impurities and Allowable Range Other impurities such as S, P, O, Ti, Na and W are preferably 2.5% or less in order to secure the performance of the weld metal.

Cr equivalent (Cr + Mo + 1.5Si + 0.
5Nb) / Ni equivalent (30C + 0.5Mn + Ni + 0.
4Cu + 30N): 2.0-5.0 The Cr equivalent / Ni equivalent has a large effect on the formation of ferrite for preventing high-temperature cracking of the weld metal. If it is less than 2.0, no ferrite is formed and the crack resistance is deteriorated. If it exceeds 5.0, the ferrite becomes excessive and a sigma phase is generated, which causes the weld metal to become brittle. Therefore, Cr equivalent / Ni equivalent is limited to 2.0 to 5.0.

It is advantageous to use a simple metal as the metal powder to be filled, in order to reduce the filling rate. Metal Cr, metal Ni, metal Mo, metal Mn, etc. can be blended depending on the target component. It can be added with Cr nitride, Fe-Cr nitride, Fe-Mn nitride or the like.

There are two types of fillers: a state in which metal powder is mixed and mixed, and a state in which fine particles are granulated with water glass. The effect of using either filler is not changed. Is better when granulated and filled.
When a granulated filler is used, water glass such as sodium silicate and potassium silicate used in granulation becomes coarser when the added amount exceeds 10%, and the filling property is deteriorated, and a predetermined filling rate is obtained. Can not be. In addition, from the viewpoint of the composition of the alloying agent, the filler is dried after granulation, so that there is almost no mixing of moisture, and the solid mass of water glass is mixed. Does not affect metal performance. The solid mass of water glass is generally about 30% to 40%, and 12
% Is acceptable. From the viewpoint of granulation and solid mass, the amount of water glass added is desirably 10% or less.

If the filling ratio exceeds 40%, the wire may break during wire drawing, so the filling ratio is preferably 40% or less.

[0026]

EXAMPLES Examples of the present invention will be described below. The wire was 4.0 mm after filling the filler into the austenitic outer skin.
It was drawn to φ and used for the test. Table 1 shows the composition of the hull subjected to the test. Table 2 shows the composition of the filler used in the test. Table 3 shows the flux composition for the latent arc welding used.
Table 4 shows the chemical components of the laminated material and the base material of the stainless clad steel subjected to the test. Table 5 shows the welding conditions. Table 6 shows the chemical composition of a wire obtained by filling the outer skin of Table 1 with the filler of Table 2 at a filling rate of 30%. Combining the wire of Table 6 with the latent arc flux of Table 3 and performing a one-pass butt welding on both sides of the steel sheet of Table 4 processed into the groove shape of FIG. 1 under the welding conditions of Table 5, the accuracy test of the weld metal performance Was carried out.
Table 7 shows the chemical composition of the weld metal on the cladding material side, the results of the corrosion test, the results of the measurement of the amount of ferrite, and the results of the X-ray transmission test and the side bending test of the joint weld metal. The pitting corrosion test (JISG05) was performed on the corrosion test that passed the X-ray transmission test.
77) was carried out, and the judgment that pitting occurred at 30 ° C. was rejected. The amount of ferrite was measured with a ferrite meter. The integrity of the weld metal is determined by an X-ray transmission test (JISZ31
06) and the side bending test (JISZ3122).

From the above results, the wire symbols 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1 of the present invention were obtained.
The weld metal welded using Nos. 2 and 13 is 0.8-1
Contains 7.2% ferrite, no cracks or weld defects such as blowholes were observed in the X-ray transmission test,
A good bending ductility was also exhibited in the side bending test, and a sound weld metal without cracks in the welded portion was obtained. In addition, no pitting was observed in the pitting test, and good corrosion resistance was obtained.

On the other hand, the wire symbol 14 of the comparative example has too much Ni in the wire and the Cr equivalent / Ni equivalent is too small, and the symbol 15 has too much Ni and N in the wire and Mo is insufficient.
Cr equivalent / Ni equivalent is too small, symbol 16 has too much Mo in the wire, symbol 17 has too much Nb in the wire, symbol 1
8 is insufficient in Si and Cu in the wire, symbol 19 is insufficient in Cr in the wire, Nb is excessive, symbol 20 is excessive in Cr in the wire, Mo is insufficient, and symbol 21 is insufficient in the wire. Is excessive in Si and Mn is insufficient, symbol 22 is excessive in C and Si in the wire and Mo is insufficient, symbol 23 is insufficient C and Si in the wire, and symbol 24 is excessive in Mn and 24 in the wire. C, Si, Ni, N are insufficient, Mo is too large and Cr equivalent / Ni equivalent is too large, and symbol 25 indicates C, S in the wire.
Insufficient i, Ni, Mo, N, Cr excess and Cr equivalent / N
Problems such as corrosion test, X-ray transmission test, side bending test and the like occurred for each reason such as i-equivalent being too large, and good weld metal could not be obtained.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[Table 4]

[Table 5]

[0032]

[Table 6]

[0033]

[Table 7]

[0034]

[Table 8]

[0035]

[Table 9]

[0036]

As described above, by using the stainless clad steel submerged arc welding wire of the present invention, a sound weld metal can be easily obtained even when the stainless clad steel is welded with the same welding material. And made it possible to perform welding work economically and efficiently.

[Brief description of the drawings]

FIG. 1 shows a groove shape for welding a joint of stainless clad steel.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-178375 (JP, A) JP-B-37-6614 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 35/368 B23K 35/30 B23K 35/40

Claims (2)

(57) [Claims] 1. A filling wire comprising an austenitic stainless steel sheath filled with a flux composed of an alloying agent, wherein one of the stainless steel sheath and the flux is used.
Or as a total amount of components contained in both, C: 0.02 to 0.10%, Si: 0.05 to 1.0%, Mn: 0.3 to 5.0%, Ni : 6 to 16%, Cr: 20 to 40%, Mo: 5.0 to 11.5%, N: 0.005 to 0.25%, the balance being Fe and unavoidable impurities,
A latent arc welding wire for stainless clad steel, wherein the value A shown in the following equation (1) is set to 2.0 to 5.0. A = Cr equivalent (Cr + Mo + 1.5Si + 0.5Nb) / Ni equivalent (30C + 0.5Mn + Ni + 0.4Cu + 30N) (1) 2. The method according to claim 1, wherein one or two of Nb: 0.02 to 4.0% and Cu: 0.05 to 2.0% are contained in a wire weight ratio. Submersible arc welding wire for stainless clad steel.