JPH11197883A - Nickel base alloy flux containing wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve weldability at all postures and a weld metal performance such as strength, toughness and high temp. crack resistance, by specifying an oxidized Ni amt. contained in flux, an Mo amt. contained in at least one of metal powder or a Ni base alloy outer shell and specifying a thickness ratio for its outer diameter and the thickness. SOLUTION: Flux 2 made of metal oxide, metal powder and metal fluoride is filled in a Ni base alloy outer shell 1 by 20-40% per whole wire weight, a flux covered wire is obtained. In this case, in a weight ratio per the wire weight, oxidized Ni is made to contain 0.2-5%, Mo is made to contain 10-19% in at least one of metal powder or an outer shell 1, the improvement of weld metal performance and the securing of wire productivity are made easy. Further, the outer shell 1 is made to a thickness ratio of 0.08-0.17 for a wire diameter and is made to a cross sectional shape of 0.7-1.2 mm in the thickness and of 0 type without a butt joint to improve the moister absorption prevention of the internal flux 2 and the wire productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to gas shielded arc welding for high strength austenitic stainless steel such as 9% Ni steel used for structures such as LNG tanks and pressure vessels for cryogenic temperatures and steel tubes for thermal power generation boilers. Regarding the flux cored wire used, more specifically 80% Ar + 20
% CO ₂ gas-assisted arc welding using a gas mixture, the welded part has excellent hot cracking resistance and X-ray performance, as well as high strength and high toughness, as well as downward, horizontal fillet, and vertical The present invention relates to a flux cored Ni-base alloy wire having good welding workability in each upward position.

[0002]

2. Description of the Related Art In recent years, flux-cored wires based on Ni-based alloys, such as Inconel-based alloys, which have a higher welding work efficiency than a covered arc welding rod, have been developed for welding extremely low temperature steel such as 9% Ni steel. It is being used in construction work. However, Ni-based alloy flux-cored wires still have many problems in welding metal performance such as hot crack resistance, welding workability, wire productivity, quality stabilization, etc., and carbon steel, stainless steel, etc. The usage ratio has not increased compared to flux cored wires for welding other steel types.

[0003] As this kind of existing wire, Japanese Patent Application Laid-Open No. Hei 6-198488 for TiO ₂ -based flux and Japanese Patent Application Laid-Open No. Hei 7-116891, in which the ratio of TiO ₂ / (carbonate + fluoride) in the flux is controlled, are disclosed. Nevertheless, the flux-cored wires disclosed in these publications have good hot cracking resistance, X-ray performance, cryogenic toughness, strength, welding workability in all positions, wire productivity, when welding 9% Ni steel. It is difficult to ensure a good balance of quality stability and the like.

On the other hand, a new high-alloy austenitic stainless steel has recently been developed for high-strength austenitic stainless steel, such as a steel tube for a thermal power boiler, in order to be applicable to a higher temperature (700 ° C.) environment than before. ing. The flux-cored wire applied to such steel grades can maintain high-temperature characteristics if made of a fully austenitic stainless steel weld metal made of a base metal and a co-metallic material, but still has a problem in high-temperature cracking resistance. An Inconel 625-based flux-cored wire made of a Ni-based alloy having a different component system from that of the base material can be used. However, even in this case, even if high-temperature characteristics can be ensured, there remains a problem in high-temperature cracking resistance. Therefore,
The development of a new flux-cored wire that can satisfy various welding performances even when applied to these applications has been desired.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a welding workability and wire production in all postures while ensuring good weld metal performance such as hot cracking resistance, X-ray performance, toughness, ductility and strength. Ni used for welding 9% Ni steel and high alloy austenitic stainless steel which has good properties and stable quality.
An object of the present invention is to provide a base alloy-based flux cored wire.

[0006]

In order to solve the above-mentioned problems of the present invention, a wire in which a flux composed of a metal oxide, a metal fluoride, and a metal powder is filled in a Ni-based alloy shell is used. Trials were made and various studies were made on the flux composition, flux filling rate, outer skin thickness, cross-sectional shape, wire outer diameter, etc. of these flux-cored wires.

As a result, in a wire in which a predetermined amount of Mo is added to the outer skin or the flux, the addition of nickel oxide to the flux improves the ductility, toughness, and hot cracking resistance of the weld metal, and increases the room temperature. And high strength at high temperatures. In addition, in such a wire having a shell and a flux composition, if the filling rate is increased to such an extent that the productivity of the wire is not hindered, the stability of the arc,
It is possible to improve the enclosing property of the slag, the peeling property, the bead shape in the upright and upward postures, etc., and by adjusting the ratio of the skin thickness to the wire outer diameter, as shown in FIG. It was also found that the bead shape was further improved.

The present invention has been made based on these findings, and the gist thereof is as follows. (1) In a Ni-based alloy flux-cored wire in which a flux composed of a metal oxide, a metal powder, and a metal fluoride is filled in an amount of 20 to 40% by weight based on the total weight of the wire, the weight% based on the total weight of the wire In the flux, 0.2 to 5% of nickel oxide and 10 to 19% of Mo contained in at least one of the metal powder and the outer skin are included.
A flux-cored Ni-base alloy wire, characterized in that: (2) The Ni-based alloy flux-cored wire according to (1), wherein the ratio of the thickness of the Ni-based alloy outer skin to the wire outer diameter is 0.08 to 0.17. (3) The Ni-based alloy flux-cored wire according to (1) or (2), wherein the outer skin of the wire is 0.7 to 1.2 mm, and the cross-sectional shape of the wire is an O-shape having no seams matching the outer skin. .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The reasons for specifying various components and the like and the reasons for limiting numerical values in the Ni-based alloy flux-cored wire of the present invention will be described below. First, the outer layer made of a Ni-based alloy in the present invention has, for example, a composition of C: 0.005 to 0.05.
%, Si: 0.3% or less, Mn: 4.0% or less, P:
0.010% or less, S: 0.010% or less, Ni: 60
-80%, Cr: 25% or less, total of one or both of Ti and Al: 0.3-0.8%, total of one or both of Nb and Ta: 3% or less, Mo: 19% or less, W :
5% or less, Fe: 5% or less, Co: 5% or less, Cu: 5
%, B: 0.003% or less, N: 0.02% or less,
The remainder refers to those that are unavoidable impurities, and ensures good high-temperature cracking resistance, ductility, toughness, strength, and other welding performances targeted by the present invention, and suppresses work hardening during wire production as much as possible. It is made of a material that can secure productivity.

[0010] Next, the flux to be filled into the wire outer cover is used for welding workability in all postures, such as strength, ductility, cryogenic toughness, toughness after aging, hot cracking resistance, X-ray performance, and standing. In order to improve each of them, a metal oxide, a metal fluoride, and a metal powder are all essential, and the flux filling rate is required to be 20% or more based on the total weight of the wire. But 40
%, Breakage of the flux-cored wire is extremely likely to occur during the production.

As the metal oxide, TiO ₂ , ZrO
₂ , SiO ₂ , Al ₂ O ₃ , CaO, MgO, BaO,
There are oxides of Na ₂ O, K ₂ O, Mn and Fe, nickel oxide, and the like, which can be added for the purpose of improving welding workability and welding metal performance.

Metal fluorides are CaF ₂ , BaF ₂ , MgF
₂ , AlF ₃ , NaF, LiF, K ₂ ZrF ₆ , K ₂ S
iF _{6 and the} like can be added for the purpose of improving welding workability and weld metal performance.

As the metal powder, Mo, Ti, Zr, A
1, Mn, Si, Fe, Cr, Mg, Nb, Ta, W,
There are Co, B, Ni, Ca and the like, and any of them can be added for the purpose of securing various properties of the deposited metal such as mechanical properties, X-ray performance, and hot cracking resistance, and improving welding workability.

[0014] Of the above-mentioned metal oxides, nickel oxide is added to C, Si, C in the weld metal by adding 0.2% or more.
r, Ti, Al, Nb can be reduced by removing into the slag,
In addition, it contributes to the increase of Ni in the weld metal, and has an effective effect on improving hot cracking resistance, ductility, low-temperature toughness, and toughness after aging. There is a slight effect in improving the bead shape. However, if the amount is too large, the slag is burned and the releasability is deteriorated, and the bead shape in the downward or horizontal fillet posture becomes convex, so that the amount of nickel oxide in the flux is 0.2 to 5% by weight% of the whole wire.
Need to be controlled.

Mo is effective in increasing strength and improving hot cracking resistance. However, when Mo is excessively high, ductility, low-temperature toughness and toughness after aging are remarkably deteriorated. It must be controlled to ~ 19%. Here, the amount of Mo in the outer coat means the M in the flux.
Similarly to the o amount, it is a value based on the total weight of the wire, and is obtained by the formula of [Mo weight% in outer skin × (1-flux filling rate)].

Further, the ratio of [skin thickness / wire outer diameter] in the cross section of the finished wire can be controlled by adjusting the filling rate of the flux, the bulk density of the flux, etc. in the flux-cored wire manufacturing process. Is set to 0.17 or less, the arc is stabilized in the low current range of the welding, which contributes to further improvement of the bead shape in the vertical or upward posture. However, when it is less than 0.08, the frequency of occurrence of troubles such as disconnection during wire production increases. The cross section of the wire is cut at a right angle to the longitudinal direction of the wire.
It refers to a polished cross section.

The outer diameter of the finished wire is optimally 0.7 to 1.2 mm in order to make it easier to ensure good welding workability in all postures, such as upright and upward. By making the O cross section without eyes, pits and blow holes due to moisture absorption can be made more difficult to occur, and the use of a wet lubricant and a cleaning liquid becomes easier during wire production. Can improve productivity and stabilize the quality of the flux-cored wire having the outer skin.

[0018]

EXAMPLES The effects of the present invention will be specifically described below with reference to examples. FIG. 2 shows the flux-cored wire of the present invention.
(A) to (d) may be a wire having a cross-sectional shape as shown in FIG. Further, as shown in FIG. 3 (a), if there is no seam, moisture absorption can be avoided and it is even better.

Table 1 shows the chemical components of the test skin.
Table 3 shows the chemical components of the test steel sheet. Tables 4 and 5 show the composition of the flux-cored wire according to the combination of the test sheath and the filling flux.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

[0024]

[Table 5]

In the welding test, welding was performed in the downward, horizontal fillet, and vertical positions. Conditions are as follows: wire diameter: 1.2 mm, shielding gas: 80% Ar + 20% CO ₂ (flow rate: 20 to ₂ )
5 liter / min), welding current: 100-180A
(DC electrode +), welding voltage: 23 to 32 V, welding speed:
The standing posture was about 10 cm / min, and the downward / horizontal fillet was about 35 cm / min using the test plates shown in FIGS.

The hot cracking test was performed using a T-joint test plate shown in FIG. 3 with horizontal fillet welds on both sides, a restraint bead on the first side, a test bead on the second side, and a test bead on the second side. Then, the bead surface excluding the crater and 1 mm below, 2 mm below, and 3 mm below the surface were sequentially ground with a grinder, and the presence or absence of cracks was examined by a penetrant inspection test.
In FIG. 3, i is a base material, and t is 16 mm in plate thickness.

The welding workability test was carried out by horizontal fillet welding and vertical welding using the test plate of the T-joint in FIG. 3 and downward welding using the butt joint in FIG. 3 and 4
I is a base material, t is a plate thickness of 20 mm, and g is a root interval of 1 mm.
2 mm, θ is a groove angle of 45 °.

The tensile test piece of the deposited metal is welded downward to the test plate of FIG. 4 and then JIS Z3111A as shown in FIG.
No. 1 was collected. In addition, the impact test piece was made as shown in FIG.
SZ31114 was collected. An analysis sample of the deposited metal was taken from the weld metal shown in FIGS.

The wire is made of a pipe and a hoop having the chemical components shown in Table 1 as an outer covering material, and has an outer diameter of 2.6 to 14 mm.
After filling a predetermined amount of flux into the inside of a pipe having a wall thickness of 0.6 to 1.4 mm, a wire reduction rate of 30 to 65 in the wire drawing process to reach a product diameter of 0.8 to 1.2 mm. %, Annealing (11) to soften the work hardened skin is performed.
(00 ° C. × 1 to 6 times).

Flux-cored wire symbols W1 to W6 in Tables 4 and 6 showing the test results are the present invention, and W7 to W18 in Tables 5 and 7 are comparative examples.

[0031]

[Table 6]

[0032]

[Table 7]

In Comparative Example W7, since the amount of nickel oxide in the flux was too small, the ductility and cryogenic toughness of the weld metal were low, and hot cracking also occurred. In Comparative Example W8, the amount of nickel oxide in the flux was too large, and the slag removability was too poor. Since W9 has too much Mo in the flux, the ductility and the cryogenic toughness of the weld metal are low.

In Comparative Example W10, the amount of M
o Since the total amount was too small, hot cracking occurred in the weld metal. In Comparative Example W11, since the total amount of Mo in the outer shell and the flux was too large, the ductility and the cryogenic toughness of the weld metal were low. In Comparative Example W12, since the flux filling rate was too low, the slag encapsulating property and the peelability were poor, and the bead shape in the upright posture was also poor.

On the other hand, W1 to W6 of the present invention had good welding properties and good productivity without disconnection during wire production. In addition, the welding workability evaluation symbols in Table 4 are good:
、, slightly defective: Δ, defective: x.

Next, by adjusting the particle size and bulk density of the flux with respect to the wire W1, the ratio of the outer wall thickness to the wire outer diameter was changed to 0.06 to 0.19, and the wires W1 to ah were prototyped. Then, the vertical bead shape and the presence or absence of disconnection during wire production were examined. Table 8 shows the results.

[0037]

[Table 8]

From these results, the ratio of the skin thickness to the wire outer diameter is particularly preferably in the range of 0.08 to 0.17 from the viewpoint of the bead shape in the upright posture and the wire breakage. 0.7 to 1.2 mm is preferable (W1-e to h).

As a result of examining the pit resistance of the fillet welded portions by changing the wire cross-sectional shape of the W1 wire as shown in FIG. 2 (W1-eh), the cross-sectional shape of FIG. The wire was particularly good (W1-e). The test wire was at room temperature 30 ° C and 80% humidity before the welding test.
For 24 hours.

[0040]

As described above, the Ni-based alloy flux-cored wire of the present invention satisfies all the constituent requirements of the present invention, thereby improving the welding workability in all-position welding, and
It enables the improvement of weld metal performance such as strength, toughness, hot cracking resistance, and the productivity of wire. According to the present invention, improvement in work efficiency and improvement in quality of a welded portion can be expected in welding 9% Ni steel and high alloy austenitic stainless steel.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a wire outer diameter, a skin thickness, a vertical bead shape, and occurrence of wire breakage.

FIGS. 2A, 2B, 2C, and 2D are schematic views showing various cross-sectional shapes of a flux-cored wire.

FIG. 3 is a schematic diagram of a test plate shape of a T-joint used in an example.

FIG. 4 is a schematic diagram of a test plate shape of a butt joint used in an example.

FIG. 5 is a schematic view showing a sampling position of a tensile test piece used in an example.

FIG. 6 is a schematic view showing a position at which an impact test piece is collected in an example.

[Explanation of symbols]

 1 outer skin 2 flux i base material t plate thickness g root interval θ groove angle

Claims (3)

[Claims] 1. A Ni-based alloy flux-cored wire in which a flux composed of a metal oxide, a metal powder, and a metal fluoride is filled in a Ni-based alloy outer cover in a weight percentage of 20 to 40% by weight based on the total weight of the wire. 0.2 to 5% by weight of nickel oxide in the flux, and 10% of Mo contained in at least one of the metal powder and the shell by weight.
Ni-based alloy flux-cored wire characterized by having a content of about 19%. 2. The Ni-based alloy flux-cored wire according to claim 1, wherein the ratio of the thickness of the Ni-based alloy outer skin to the wire outer diameter is 0.08 to 0.17. 3. The Ni-base alloy flux according to claim 1, wherein the outer skin of the wire is 0.7 to 1.2 mm, and the cross-sectional shape of the wire is an O-shape having no seams with the outer skin. Cored wire.