JP2633755B2 - Cr containing arc welding rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to SUS403, 410, 410S used for various equipments of petroleum refining industry and chemical industry.
Martensitic stainless steel and SUS405,4
30,434 ferritic stainless steel, Cr-containing used for welding these clad steels and overlay welding on carbon steel
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated arc welding rod, and more particularly, to a Cr-containing arc welding rod having excellent deposited metal properties such as high-temperature strength.

[0002]

2. Description of the Related Art Cr-based stainless steel is used for equipment used in an environment that dislikes Ni or in a corrosive environment where stress corrosion cracking is likely to occur, but it is required to have excellent heat resistance such as high-temperature strength. Many. Since such Cr-based stainless steel has poor weldability compared to Cr-Ni-based stainless steel,
As a welding material applied to these steel types, a Cr-based welding rod containing Nb, Ti, and Al is often used in order to suppress precipitation of martensite and refine ferrite crystal grains.

However, the conventional Cr-based welding rod containing Nb, Ti, and Al has a problem that sufficient strength of the deposited metal in a high-temperature environment cannot be obtained.

As this type of welding rod, Japanese Patent Publication No. 49-6 / 1976 is known.
No. 748, "13Cr stainless steel welding rod" and Japanese Patent Publication No. 3-2596, "Chromium stainless steel coated arc welding rod for overlay welding" are known. In addition, a coated arc welding rod having a high-strength deposited metal in a high-temperature environment cannot be obtained.

[0005]

SUMMARY OF THE INVENTION The present invention relates to Nb, T
i, Al-based Cr-based stainless steel coated arc welding rods must have a high-temperature-strength deposited metal, have excellent welded metal performance such as ductility, toughness, and crack resistance, and have good welding workability. It is intended.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have variously adjusted the core component and the coating agent component,
As a result of earnestly examining the relationship between the weld metal performance such as high-temperature strength and welding workability in a Cr-containing stainless steel-coated arc welding rod containing Nb, Ti, and Al, the following findings were obtained. That is, it has been found that if one or both of the core wire and the coating material contain Ni and V in an appropriate amount, and a small amount of Ni and V is added to the deposited metal, the high-temperature strength at 200 to 400 ° C. is significantly increased. .

However, the effect of the addition of Ni and V is significantly reduced when the oxygen content in the core exceeds a predetermined amount, and the ductility and toughness are deteriorated. Therefore, the oxygen content in the core is less than the predetermined amount. Need to be restricted to The present invention is based on the above findings, and the gist of the present invention is that Cr is
11 containing 22%, the outer periphery of the core wire that regulates the O below 0.010%, CaCO ₃ 20 to 60%, a coating agent containing CaF ₂ 15 to 45% by coverage 20-50% In the applied ferritic stainless steel welding rod, Ni is added to one or both of the core wire and the coating agent in a core wire weight ratio of 0.00.
3 to 0.4%, the V contains 0.003 to 0.5%, extending
High temperature strength of the deposited metal without impairing the toughness, toughness and crack resistance
A ferrite stainless steel welding rod characterized by ensuring a high degree of strength.

Here, the core wire weight ratio refers to the ratio represented by the following formula, and the coating compounding ratio in the same formula means the mixing ratio of the added material to the total weight of the coating agent. Further, the coverage means the proportion of the weight of the coating material in the welding rod. Core weight ratio = content in core wire (%) + [mixing ratio in coating agent (%) x coverage (%) / 100]

[0009]

The present invention will be described below together with the operation. Cr-based stainless steels include martensitic stainless steels, and the Cr content in the steel material varies depending on these steel types, but is generally in the range of 11 to 20%. The welding rod of the present invention is applied to such a Cr-based stainless steel and the welding of these clad steels and build-up welding on carbon steel. Since it is necessary to ensure the performance, the Cr content of the deposited metal must be inevitably the same as that of the Cr stainless steel.

[0010] Since Cr is an inevitable main element, it is preferable to add Cr mainly to the core wire and to supplement the addition to the coating material. That is, the Cr content in the core wire is 1
When the content is less than 1 %, the amount of Cr in the coating material must be increased, and the heat resistance of the coating material is significantly adversely affected.
Good welding workability cannot be obtained. Conversely, C
If the amount of r exceeds 22%, the amount of Cr in the deposited metal becomes excessive, and the toughness is significantly deteriorated.

Next, oxygen contained as an impurity in the core wire deteriorates the ductility and toughness of the deposited metal and promotes the oxidative consumption of Cr, Nb, V, Ti, Al, etc. added as an alloying agent. Therefore, in the welding rod for controlling V which is easily oxidized to a very small range as in the present invention, it is difficult to adjust the amount of V added to the deposited metal to an appropriate range unless it is limited to 0.010% or less. .

CaCO ₃ added to the coating agent is CO ₂
It generates gas to block nitrogen, oxygen and hydrogen from the atmosphere, and at the same time, forms a basic slag to protect the deposited metal. However, when the content in the coating material is less than 20%, these effects become ineffective. It is not exhibited, and the welding workability such as bar burning resistance also deteriorates. If it exceeds 60%, spatters occur frequently.

CaF ₂ lowers the melting point and viscosity of slag to produce slag with good fluidity, and is therefore effective in preventing defects in pits and blowholes. However, such an effect appears when the addition is 15% or more, but when it exceeds 45%, the arc becomes unstable and spatter occurs frequently.

If the coverage is too small, the stability of the arc and the resistance to burning are deteriorated. On the other hand, if the coverage is too large, the protection tube of the coating becomes deep, the arc length increases, and it becomes difficult to maintain the arc. The lower limit was 20% and the upper limit was 50%.

[0015] If Ni and V are added together in the appropriate amount ranges, the high-temperature strength of the deposited metal increases. This N
The addition of i and V is performed from one or both of the core wire and the coating agent. Ni is less than 0.003% and V is 0.1% by total weight ratio of the core wire.
If it is less than 003, there is no effect. Ni is 0.4%
If V exceeds 0.5%, the room temperature tensile strength decreases, and if V exceeds 0.5%, ductility and toughness decrease.
It is necessary to control the V content to 3 to 0.4% and the V content to 0.003 to 0.5%, respectively.

The welding rod of the present invention contains SiO ₂ , TiO ₂ , Al ₂ O ₃ , CaO, Mg as other components.
Metal oxides such as O, K ₂ O, Na ₂ O, BaCO ₃ ,
Carbonates such as MgCO ₃ , MgF ₂ , AlF ₃ , BaF
₂ , metal fluorides such as Na ₃ AlF ₆ , Cr, Mo , N
Metal powders such as b, Al, Ti, Mg, Mn, and Fe can be added to the coating.

As described above, the welding rod of the present invention has
At the same time as limiting the oxygen content and simultaneously controlling the Ni, V content added to one or both of the core wire and the coating material and the CaCO ₃ and CaF ₂ content in the coating material to appropriate ranges. Thereby, it has high strength even in a high temperature environment, and can improve various performances and welding workability of other deposited metals.

Here, the method of manufacturing the welding rod will be described. A powder of a coating material mixed and mixed with a core wire is prepared, and the coating material powder is wet-mixed with a binder of water glass (potassium silicate, sodium silicate aqueous solution). Then, after covering the core wire, drying and firing are performed at 200 to 450 ° C. for about 1 hour or more.

[0019]

Embodiments of the present invention will be described below. Table 1
Shows the chemical components of the test core wire. Table 2 shows the composition of the coated arc welding rod by the combination of the test core wire and the coating agent. Table 3 shows the chemical composition of the steel sheet used, and Table 4 shows Table 2
The results of the room temperature and high temperature tensile tests, the results of the impact test at 0 ° C., and the results of the welding workability test of the deposited metal welded using the coated arc welding rod of No. 1 and the steel sheet of Table 3 are shown.

The welding conditions were as follows: using a welding rod having a rod diameter of 4.0 mmφ, welding current 140 A (AC), arc voltage 22
It welded to the test plate of the groove shape shown in FIG. In FIG. 1, the plate thickness t = 20 mm, the groove angle θ =
45 ° and the root interval G = 12 mm.

The high-temperature tensile test piece of the deposited metal is JIS Z0
567 (diameter: 6 mmφ), room temperature tensile test piece is JIS Z3
JIS Z31124 was sampled for 11 A1 and an impact test piece. The post-weld heat treatment was performed before processing the test piece.
10Nb welding rod is 850 ° C × 2h (slowly cooled to 590 ° C., then air-cooled). D430Nb welding rod and 770 ° C × 2 welding rod having SUS434 equivalent welding metal component.
h (slow cooling to 590 ° C. followed by air cooling).

The coated arc welding rod Nos. 1 to
No. 12 is a comparative example. 13 to 21 are the present invention. As is clear from the results in Table 4, Reference numeral 1 denotes a welding rod containing a large amount of Cr in the coating agent because the amount of Cr in the core wire is less than 11 %, but has poor welding workability such as bar burning resistance.

No. In No. 2, since the amount of Cr in the core wire exceeded 22%, the amount of Cr in the deposited metal was excessive, and the toughness at 0 ° C. was low. No. Reference numeral 3 denotes a D430Nb-based welding rod. Since the oxygen content in the core wire exceeds 0.010%, the oxidative consumption of V added to the core wire is promoted, and the high-temperature strength is low. Also, the toughness at 0 ° C. is low.

No. In No. 4, since the content of calcium carbonate exceeds 60%, the arc state and bead appearance are poor, and spatter frequently occurs. No. 5 has less than 15% of CaF ₂ ,
The fluidity of the slag is poor. No. 6 is 45 CaF ₂
%, The arc state is poor, and spatter frequently occurs.

No. Since No. 7 has a coverage of less than 20%, welding workability such as bar burning resistance is poor, and No. 7 having a coverage of more than 50%. 8 has a bad arc state. No. In No. 9, the amount of Ni contained in one or both of the core wire and the coating agent was less than 0.003% by weight of the core wire. In No. 10, since V is 0.003%, all the welding rods have low high-temperature strength. No. No. 11 has low room temperature strength because Ni exceeds 0.4%. In No. 12, since V exceeds 0.5%, the toughness at 0 ° C. is low.

On the other hand, in the welding rod of the present invention, 13
Nos. 21 to 21 had high strength at high temperature and room temperature, and also had good toughness at 0 ° C and welding work. The evaluation of welding workability and the overall evaluation in Table 4 indicate [○: good, Δ: slightly poor, ×: poor].

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

[Table 4]

[0031]

[Table 5]

[0032]

[Table 6]

[0033]

[Table 7]

[0034]

[Table 8]

[0035]

As described above, the present invention relates to the "Cr and O content in the core wire", "CaCO ₃ and CaF _{2 in the} coating agent", " By controlling one or both of Ni and V ”and“ coverage ”within appropriate ranges, the high-temperature strength and other various performances of the deposited metal are improved, which can contribute to the improvement of the quality of the Cr-based stainless steel weld.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a groove shape of a test plate used for welding workability, high-temperature and room-temperature tensile tests, impact tests, and the like. t Plate thickness θ Groove angle G Root interval

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-161496 (JP, A) Seiichi Ando et al. Hou Shuppan, P. 187-190

Claims (1)

(57) [Claims] 1. An outer periphery of a core wire containing 11 to 22% of Cr (% by weight, the same applies hereinafter) and restricting O to 0.010% or less, wherein CaCO ₃ is 20 to 60% and CaF ₂ is 15 to 15%. 4
Off coated on coverage 20-50% coating agent containing 5%
In a ferrite-based stainless steel welding rod, one or both of the core wire and the coating agent contains Ni in a total weight ratio of the core wire of 0.003 to 0.003%.
0.4%, 0.003 ~ 0.5% V , ductility, toughness
High-temperature strength of the deposited metal without impairing the
Ferritic stainless welding rod, characterized in that the holding.