JPH08206877A - Submerged arc welding wire for stainless clad steel - Google Patents

Abstract

PURPOSE: To obtain a submerged arc welding wire for a stainless clad steel with which a defectless weld metal is cost effectively and efficiently obtd. by using a wire formed by filling metallic powder adjusted in components into a sheath made of an austenitic stainless steel. CONSTITUTION: This submerged arc welding wire for the stainless clad steel is produced by filling a flux composed of an alloy agent into the sheath made of the austenitic stainless steel. Either or both of the stainless steel sheath and the flux contain, by the weight of the wire, 0.02 to 0.10% C, 0.05 to 1.0% Si, 0.3 to 5.0% Mn, 6 to 16% Ni, 20 to 40% Cr, 5.0 to 11.5% Mo and 0.005 to 0.25% N as the total weight of the components incorporated therein and consist of the balance Fe with inevitable impurities. A in the following formula is so determined as to attain 2.0 to 5.0. A=Cr equiv. (Cr+Mo+1.5Si+0.5Nb)/Ni equiv. (30C+0.5Mn+Ni+0.4Cu+30N).

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 welding of clad steel economically and efficiently, and yet it is possible to easily obtain a sound weld metal. It is about materials.

[0002]

2. Description of the Related Art Conventional submerged arc welding of stainless clad steel includes welding of stainless steel on the side of the laminated material, welding of carbon steel (mild steel or low alloy steel etc.) on the base metal, and welding of dissimilar material between the base metal and the base metal. It is necessary to weld separately with
Welding materials were selected under appropriate welding conditions by selecting a welding material suitable for welding each part and combining a solid wire with a melting type flux or a firing type flux. In the welding process, since a molten metal suitable for each part is used, the work of replacing the welding material is complicated, and there is a problem in terms of efficiency and economy. In addition, problems such as cracking of the weld metal and deterioration of corrosion resistance tend to occur at the welded portion of the dissimilar material portion, and particular attention must be paid to the selection of welding material and the welding construction method.

In the welding of stainless steel and dissimilar materials, the welding material is selected so that the welding metal contains a few percent of ferrite in order to secure the crack resistance of the welding metal. The base material may be so diluted that it may be difficult to secure the necessary amount of ferrite. As a countermeasure, there is a method to reduce the dilution of the base metal by low current welding, but the problem that not only the high efficiency welding due to high current that is the main feature of submerged arc welding is not possible but also welding defects easily occur was there. In addition, there is a method of supplementing and adding alloy components such as Cr and Mo for securing ferrite from the welding material. However, addition of alloy components from the flux causes oxidative consumption of the alloy components, and a stable alloy yield does not occur. However, there was a problem that the target amount of ferrite was not contained.

On the other hand, when alloys such as Cr and Mo for securing ferrite from the wire are added, solid wire deteriorates forgeability and wire drawability, so that the addition amount is limited, and productivity and economically Also had a problem. As another alloy addition method, there is a filling wire for filling a metal sheath with a flux containing alloy components and the like. The target alloy component can be added relatively easily and the productivity is good, and there are some which have already been developed as a filling wire for stainless steel.
A welding method has been proposed which is characterized in that by filling an alloying agent in a wire described in No. 97098, good welding workability is obtained even when the welding current is lowered and the base metal is diluted less. . This method is related to overlay latent arc welding, and the purpose of this method is to lower the welding current to reduce the dilution rate of the base metal, so efficient welding with a large current is difficult and economical. Welding is not possible.

In addition, welding workability is improved by filling a stainless tubular pipe described in JP-A-58-135793 with a slag agent and a filler composed of metal powder mainly composed of stainless powder of 25% or less. , A latent arc welding wire in which the composition of the weld metal can be adjusted is disclosed. This is because the filler is composed of a slag agent instead of filling the alloy agent in the wire, and the purpose is to improve welding workability. It is difficult to obtain the intended weld metal of the alloy composition. Further, in Japanese Patent Laid-Open No. 2-197397, the present inventors disclose a wire filled with a metal powder containing O in the outer shell of a low C austenitic stainless steel. Its main purpose is to weld steel, and it is difficult to apply it to dissimilar material welding, which greatly dilutes the base material such as clad steel with carbon steel as the base material.

Some of the inventors of the present invention have filed Japanese Patent Application No. 6-129.
No. 932 has filed an application for a multi-electrode inner surface latent arc welding method for stainless clad steel pipes. This welding method is a method for obtaining the characteristics of the inner surface weld metal by controlling the groove shape on the side of the mating material and welding with electrodes of two or more poles. You are using wires. In this welding method, the base material side and the mating material side cannot be welded with the same welding material, and both surfaces can be constructed with the same welding material by using the wire of the present invention.

[0007]

DISCLOSURE OF THE INVENTION The present invention, in the latent arc welding of clad steel, uses a wire filled with a metal powder whose composition is adjusted in the outer skin of an austenitic stainless steel, thereby welding the base metal and the base metal. It is now possible to perform welding using the same welding material instead of welding with different welding materials and welding of different materials, and it is now possible to perform welding with the same welding material. It is intended to provide a latent arc welding wire of stainless clad steel which has good crackability and enables economical and efficient welding.

[0008]

Means for Solving the Problems In order to carry out various studies on a latent arc welding wire of stainless clad steel, the present inventors have used an austenitic stainless steel skin and prepared a metal powder containing the weld metal as a target component. A wire filled with was prototyped and a welding experiment was conducted in combination with a commercially available flux. As a result, by controlling the components within a specific range and performing welding using a wire having a Cr equivalent / Ni equivalent adjusted within a specific range, the stainless steel of the laminated material and the carbon steel of the base material are simultaneously welded. Also, the corrosion resistance of the weld metal sufficiently satisfies the PID value of the following formula (2), which is an example of the corrosion resistance evaluation method (normally> 25 is considered to be good), and further, the weld metal does not undergo σ embrittlement. It has been found that ferrite is crystallized to some extent to obtain a sound weld metal free from cracks. When welding the carbon steel on the base metal side, even if the base metal is highly diluted, it prevents the precipitation of martensite in the weld metal and, by containing an appropriate amount of ferrite, good crack resistance welding. We have also found that metals can be easily obtained. PID = Cr + 3.3Mo + 16N (2)

The present invention has been made on the basis of these findings, that is, the gist of the present invention is (1) a filling wire obtained by filling a flux composed of an alloying agent in an austenitic stainless steel outer shell. , The total weight of the components contained in one or both of the stainless steel shell and flux, in the wire weight ratio,
C: 0.02 to 0.10%, Si: 0.05 to 1.0
%, Cr: 20-40%, Mo: 5.0-11.5%,
Mn: 0.3-5.0%, Ni: 6-16%, N: 0.
Content of 005 to 0.25%, the balance being Fe and other unavoidable components usually 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, which is adjusted so 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 (1) above, which contains 2.0% of one or two kinds.

[0010]

The present invention will be described in detail below. First, the outer skin will be described. The reason for limiting the outer skin to austenitic stainless steel is as follows.Austenitic stainless steel has better workability than stainless steels such as ferritic and martensitic stainless steels, and also contains a large amount of added alloy components. The filling rate can be lowered, 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 since it is necessary to add a large amount of alloy material, the filling rate becomes high, frequent disconnection occurs, and productivity is very poor. Therefore, austenitic stainless steel is used as the skin.

Next, the reasons for limiting the total amount of the components contained in one or both of the stainless steel shell 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 side of the laminated material deteriorates. 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% Like Ni, Mn is effective for stabilizing the austenite phase. If the wire weight ratio is less than 0.3%, the effect is not recognized, and if it exceeds 5%, the precipitation of ferrite in the weld metal is prevented and the crack resistance is deteriorated. Therefore, Mn is limited to 0.3 to 5.0%.

Ni: 6-16% 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 precipitation of ferrite in the weld metal is impeded to deteriorate crack resistance. Therefore, Ni is limited to 6 to 16%.

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

Mo: 5.0-11.5% Mo is extremely effective in obtaining high corrosion resistance in the form of coexistence with Cr, Ni and the like. If the weight ratio of the wire is less than 5.0%, sufficient corrosion resistance cannot be obtained, and if it exceeds 11.5%, the σ phase precipitates similarly to Cr and the weld metal becomes brittle. Therefore, Mo
Is limited to 5.0-11.5%.

N: 0.005 to 0.25% N is extremely effective to obtain high corrosion resistance in the form of coexistence with Cr, Ni, Mo and the like. It is also effective for stabilizing the austenite phase. Wire weight ratio 0.00
If it is less than 5%, there is no effect, and if it exceeds 0.25%, bubbles are generated in the weld metal and a sound 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 side of the laminated material and improves the corrosion resistance. It is also effective in improving strength by solid solution strengthening. 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 0.02-4.
Limit to 0%.

Cu: 0.05 to 2.0% Cu is effective for improving the corrosion resistance to non-oxidizing acids. If it is less than 0.05%, there is no effect, and 2.0
If it exceeds%, the effect is saturated. Therefore, Cu is 0.
It is limited to 05 to 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 weld metal performance.

Cr equivalent (Cr + Mo + 1.5Si + 0.
5 Nb) / Ni equivalent (30 C + 0.5 Mn + Ni + 0.
4Cu + 30N): 2.0 to 5.0 Cr equivalent / Ni equivalent greatly affects the formation of ferrite that prevents hot cracking of the weld metal, and if it is less than 2.0, ferrite is not formed and crack resistance deteriorates. When it exceeds 5.0, ferrite is excessive and sigma phase is generated, which causes embrittlement of the weld metal. Therefore, the 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 because the filling rate is lowered, and metal Cr, metal Ni, metal Mo, metal Mn, etc. can be blended depending on the target component, but when N is added, It can be added with Cr nitride, Fe-Cr nitride, Fe-Mn nitride, or the like.

The filler may be in the state of being mixed and mixed with metal powder or in the state of being granulated into fine particles with water glass. The effect is the same regardless of which filler is used, but when the outer skin is a pipe It is better to fill after granulating.
When a granulated filler is used, the water glass of sodium silicate, potassium silicate, etc. used during granulation becomes coarse particles when the addition amount exceeds 10%, and the filling property deteriorates, and the prescribed filling rate is obtained. I will not be able to. From the viewpoint of the composition of the alloying agent, since the filler is dried after granulation, there is almost no mixing of water, and the solid mass of water glass is mixed, but if the solid mass is within 5%, welding workability and welding Does not affect metal performance. Generally, the solid mass of water glass is about 30% to 40%.
Permitted up to about%. The amount of water glass added is preferably 10% or less in view of granulation property and solid mass.

If the filling rate exceeds 40%, wire breakage may occur during wire drawing, so the filling rate is preferably 40% or less.

[0026]

EXAMPLE An example of the present invention will be described below. The wire was 4.0 mm after the austenitic outer shell was filled with the filler.
The wire was drawn up to φ and used for the test. Table 1 shows the composition of the outer skin used in the test. Table 2 shows the composition of the filler used in the test. Table 3 shows the flux composition for latent arc welding used.
Table 4 shows the chemical composition of the laminated material and the base material of the stainless clad steel used in the test. Table 5 shows the welding conditions. Table 6 shows the chemical composition of the wire obtained by filling the outer shell of Table 1 with the filler of Table 2 at a filling rate of 30%. The wire of Table 6 and the latent arc flux of Table 3 were combined and the steel plate of Table 4 processed into the groove shape of FIG. Was carried out.
Table 7 shows the chemical composition of the weld metal on the laminated material side, the corrosion test result, the ferrite amount measurement result, and the X-ray transmission test and side bending test result of the joint weld metal. Regarding the corrosion test, those that have passed the X-ray transmission test are pitting corrosion test (JISG05
77) was carried out, and the judgment was that those in which pitting corrosion occurred at 30 ° C. were rejected. The amount of ferrite was measured with a ferrite meter. The soundness of the weld metal is determined by the X-ray transmission test (JIS Z31
06) and side bending test (JIS Z3122).

From the above results, the wire symbols 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 11, of the examples of the present invention are shown.
Weld metal welded with 2 and 13 is 0.8-1
Since it contains 7.2% ferrite, no welding defects such as cracks and blowholes are observed in the X-ray transmission test,
In the side bending test as well, good bend ductility was exhibited, and a weld metal was obtained without cracks in the welded portion. Regarding the corrosion resistance on the side of the laminated material, no pitting corrosion was observed in the pitting corrosion 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 lacks Mo.
Cr equivalent / Ni equivalent is too small, symbol 16 has excessive Mo in the wire, symbol 17 has excessive Nb in the wire, symbol 1
8 is insufficient in Si in the wire, excessive in Cu, symbol 19 is insufficient in Cr in the wire, excessive Nb, symbol 20 is excessive in Cr in the wire, Mo is insufficient, and symbol 21 is in the wire Of Si is excessive and Mn is insufficient, symbol 22 is excessive C and Si in the wire and Mo is insufficient, symbol 23 is insufficient C and Si in the wire, symbol Mn is excessive and symbol 24 is in the wire Of C, Si, Ni, N is insufficient, Mo is excessive, Cr equivalent / Ni equivalent is too large, and symbol 25 is C, S in the wire.
i, Ni, Mo, N are insufficient, Cr is excessive, Cr equivalent / N
Problems such as corrosion test, X-ray transmission test, and side bending test occurred due to the reason that the i equivalent was too large, and a 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 latent arc welding wire of the present invention, it is possible to easily obtain a sound weld metal even if the stainless-clad steel is welded with the same welding material. In addition, welding work can be performed economically and efficiently.

[Brief description of drawings]

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

Claims (2)

[Claims] 1. A filling wire obtained by filling a flux composed of an alloying agent in an austenitic stainless steel skin, one of the stainless steel skin and the flux,
Or, as a total amount of components contained in both, in a wire weight ratio, 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%, and the balance Fe and unavoidable impurities,
Further, a latent arc welding wire for stainless clad steel, wherein the value A shown in the following formula (1) is 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. A wire weight ratio containing one or two of Nb: 0.02 to 4.0% and Cu: 0.05 to 2.0%. Submarine arc welding wire for stainless clad steel.