JPH11114693A - Coated electrode for austenitic stainless steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated electrode for austenitic stainless steel capable of preventing a coated layer from falling off during welding and excellent in welding workability of arc stability, spatter generation, slag enclosing, etc. SOLUTION: In this electrode, an austenitic stainless steel containing, by weight, <=0.02% C is used as a core wire, and the core wire is coated with a coating flux, in terms of the total weight thereof, 65-95% slag forming agent composed of 10-40% carbonate, 10-39% fluorite, 11-30% silicon ash stone housing particle size of <=150 μm, 1-15% zirconium oxide having particle size of <=50 μm and 5-35% metal powder at the coating rate of 20-40%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a chemical device, a container,
The present invention relates to a coated arc welding rod used for welding low carbon austenitic stainless steel having good intergranular corrosion resistance used in plants and the like. More specifically, the deposited metal is a low-carbon austenitic stainless steel with the same level of base metal as the base metal, has excellent intergranular corrosion resistance, and can be easily welded in all positions, such as downward and vertical, and has good adhesion of the coating. It relates to an arc welding rod.

[0002]

2. Description of the Related Art Among stainless steels, low-carbon austenitic stainless steels have excellent corrosion resistance such as intergranular corrosion resistance and are used in chemical plants and nuclear facilities.

As this type of coated arc welding rod, Japanese Patent Publication No. Sho 5
No. 7-31519, the amount of limestone, fluorite, zirconium oxide, iron oxide and the ratio of limestone to fluorite are limited.
Japanese Patent Publication No. 2-42311 proposes a coated arc welding rod for stainless steel which contains a specific amount of TiO ₂ , CaO, and fluoride as a coating agent and can very easily perform all-position welding. However, the above-mentioned technique has a problem that the coating is easily chipped off particularly during welding, and the welding workability such as arc stability, spatter generation amount and slag encapsulation property is not sufficient.

[0004]

SUMMARY OF THE INVENTION The present invention provides a low-carbon austenitic stainless steel which prevents chipping of a coating during welding and is excellent in welding workability such as arc stability, generation of spatter, encapsulation of slag, and the like. An object of the present invention is to provide a coated arc welding rod for steel.

[0005]

DISCLOSURE OF THE INVENTION In order to prevent chipping of a coating during welding of a low carbon austenitic stainless steel coated arc welding rod, the present invention has studied various core components and coating composition. As a result, by reducing the particle size of wollastonite and zirconium oxide, and by limiting the amount of addition, the synergistic effect of them improves the adhesion of the coating and eliminates the chipping of the coating at the time of welding. It has been found that this method is effective in improving the welding workability such as the bead shape, arc stability, and reduction in the amount of spatter generated.

The present invention has been made on the basis of the above findings. The gist of the present invention is as follows: (1) A core made of austenitic stainless steel having a C content of 0.02% or less by weight. And wollastonite having a particle size of 150 μm or less with respect to the total weight of the coating agent around the core wire.
30% zirconium oxide having a particle size of 50 μm or less
A coating agent containing a total of 65 to 95% of a slag forming agent containing 15 to 15% and a metal powder of 5 to 35% has a coating ratio of 20 to 40%.
A coated arc welding rod for austenitic stainless steel, wherein the coated arc welding rod is coated with a%.

(2) A core of austenitic stainless steel having a C content of 0.02% or less by weight, and around the core wire, 10 to 40% of a carbonate based on the total weight of the coating agent;
10-30% fluorite and 1 wollastonite with a particle size of 150 μm or less
1 to 30%, and a total of 65 to 95% of a slag forming agent containing 1 to 15% of zirconium oxide having a particle size of 50 μm or less,
The coating agent containing 5 to 35% of metal powder has a coating rate of 20 to
A coated arc welding rod for austenitic stainless steel characterized by being coated at 40%.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting various numerical values of the coated arc welding rod for austenitic stainless steel of the present invention will be described below.

First, the core wire used for the coated arc welding rod of the present invention is austenitic stainless steel which is a co-metallic base metal since the base metal to be welded is a low-carbon austenitic stainless steel. However, the carbon content in the core wire is set to 0.040% or less in order to reduce the carbon content of the deposited metal in consideration of the amount added from the coating agent.
Its upper limit must be at most 0.02%.

[0010] The composition other than C of the austenitic stainless steel core wire is expressed in terms of% by weight;
i: 8 to 16%, Mo: 4% or less, Mn: 0.5 to 2.
5%, Si: 0.1 to 0.6%, P: 0.03% or less,
S: 0.03% or less, Al: 0.05% or less, Ti;
0.05% or less, N; 0.1% or less, the balance being F
Those comprising e and unavoidable impurities are preferred.

The components added to the coating agent include calcium carbonate, magnesite, dolomite, barium carbonate, lithium carbonate, etc. as carbonates, and these components improve arc stability and spraying. Add for purpose. 10%
If it is less than that, the effect cannot be sufficiently obtained. 4
If it is added in excess of 0%, the amount of spatter increases and the encapsulation of the slag deteriorates. Therefore, the total of one or more carbonates needs to be 10 to 40%.

Fluorite is added for the purpose of improving the fluidity and arc stability of slag, but if it is less than 10%, its effect cannot be sufficiently obtained. If added in excess of 30%, the amount of spatter generated will increase. Therefore fluorite is 10-3
Must be 0%.

[0013] Wollastonite is added for the purpose of improving the fixation of the coating, improving the fluidity of the slag, and obtaining a smooth bead shape in the upright position. Can not get to. If the addition exceeds 30%, the fluidity of the slag becomes too large, and the bead shape in the downward position becomes convex. Therefore, wollastonite must be 11 to 30%, but 11 to 26% is preferable.

Zirconium oxide is added for the purpose of improving the fixation of the coating, improving the arc stability, and forming a slag having a good encapsulation property. I can't get it. If added in excess of 15%, spattering occurs frequently. Therefore, zirconium oxide is 1-1.
It must be 5%, but preferably 4-10%.

[0015] Further, the particle size of wollastonite and zirconium oxide greatly affects the occurrence of chipping of the coating during welding.
If the particle size of wollastonite exceeds 150 μm, or if the particle size of zirconium oxide exceeds 50 μm, the coating will have small cracks during firing and drying of the welding rod, causing chipping of the coating during welding. . Therefore, the particle size of wollastonite and zirconium oxide must be 150 μm or less and 50 μm or less, respectively.

Slag forming agents other than carbonate, fluorite, wollastonite and zirconium oxide include iron oxide, alumina, rutile, silica sand, manganese oxide, calcium oxide, SiO ₂ and Na from water glass which are usually contained. _{There are 2} O and K ₂ O, and one or more of these components are added as required for the purpose of welding workability such as arc stability and slag fluidity. If the total amount of the slag forming agent containing the carbonate, fluorite, wollastonite and zirconium oxide is less than 65%, the arc becomes unstable. Conversely, if the addition exceeds 95%, the protection cylinder becomes too deep, the arc persistence is poor, and the arc becomes unstable. Therefore, the total slag forming agent must be adjusted to 65-95%.

The metal powder is Ti, Al, Cr, Ni, M
There are n, Fe-Al, Fe-Si, Fe-Mo, etc., and one or more of them can be added mainly for the purpose of improving the deoxidizing agent, the alloying agent, and the welding workability, and these effects appear at 5% or more. If it is added in excess of 35%, the burning resistance to sticks will deteriorate.
Therefore, the metal powder must be 5 to 35%.

The present invention relates to a coating agent having the above-mentioned composition, in which the C content of the deposited metal is 0.04% or less, and in order to secure various performances of welding workability, the coating ratio (based on the total weight of the welding rod). Coating weight) should be 20-40%.

Further, referring to a method of manufacturing a coated arc welding rod, a coating agent mixed and mixed with a core wire is prepared, and then wet-mixing is performed while a fixing agent (aqueous solution of potassium silicate and sodium silicate) is added to the coating agent. , A coating agent is applied around the cord, and after coating, drying and firing are performed at 150 to 400 ° C. for about 1 to 3 hours.

[0020]

EXAMPLES Table 1 shows the chemical components of the test core wire. Tables 2 and 3 show the composition of the coated arc welding rod obtained by combining the test core wire and the coating agent.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3] The welding method is a SUS304 welding rod with a rod diameter of 4.0 mm.
Using a plate thickness of 6 mm as a base material and a welding current of 100 to 140
A, arc voltage 21-25V, welding speed 50-250m
m / min, and the welding workability test was carried out by downward bead-on-plate welding and fillet upright welding. The number of chippings of the coating was obtained by measuring the number of chippings of the coating with one welding rod in downward bead-on-plate welding, and expressed as an average value of 10 repetitions. Tables 4 and 5 show the test results. In the table, welding rod symbol No. 1 to 10 are examples of the present invention; 11 to 20 are comparative examples.

[0024]

[Table 4]

[0025]

[Table 5] No. 1 of the present invention example. 1 to 10 are suitable for the amount of C in the core wire, the amount of carbonate of the coating agent, the amount of fluorite, the amount and particle size of wollastonite, the amount and particle size of zirconium oxide, the total amount of slag agent, the amount of metal powder and the coverage Therefore, there is no chipping of the coating,
The welding workability was good in both downward and vertical position welding, and the results were extremely satisfactory, such as the C content of the weld metal was low.

In the comparative example, welding rod No. In No. 11, the C content of the core wire and the carbonate of the coating agent were high, so that the C content of the weld metal was high, the amount of spatter generated was large, and the slag encapsulation was poor.

The welding rod No. In No. 12, since the carbonate of the coating agent was low and the fluorite was high, the arc was unstable and the amount of spatter generated was large.

The welding rod No. In No. 13, the coating was chipped, the fluidity of the slag was poor, the arc was unstable, and the bead shape was poor because the fluorite and wollastonite of the coating agent were low.

The welding rod No. In No. 14, since the wollastonite as the coating agent was high and the coverage was low, the arc was unstable, the fluidity of the slag became large, and the beads became convex in the downward welding position.

The welding rod No. In No. 15, since the coating agent had high zirconium oxide and a high coverage, the arc was unstable and the amount of spatter generated was large.

The welding rod No. No. 16 had no zirconium oxide as a coating agent, the total amount of the slag forming agent was low, and the metal powder was high, so that the coating was chipped, the arc was unstable, the slag encapsulation was poor, and furthermore, bar burning occurred. .

The welding rod No. In No. 17, since there was no metal powder of the coating agent and the total amount of the slag forming agent was high, the arc was unstable.

The welding rod No. In No. 18, since the metal powder of the coating agent was high and the total amount of the slag forming agent was low, the arc was unstable and bar burning also occurred.

The welding rod No. No. 19, the wollastonite particle size of the coating agent was No. In No. 20, since the particle diameter of zirconium oxide was large, chipping of the coating occurred in each case.

[0035]

As described above, according to the present invention, a coated arc welding rod in which a weld metal is excellent in intergranular corrosion resistance, has no coating chipping during welding, and has excellent welding workability in all position welding. And contribute to the improvement of the quality of stainless steel welds.

Claims (2)

[Claims] An austenitic stainless steel having a C content of 0.02% or less in weight% is used as a core wire, and wollastonite having a particle size of 150 μm or less is surrounded around the core wire with respect to the total weight of the coating agent. The total amount of the slag forming agent containing 1 to 15% of 30% and zirconium oxide having a particle size of 50 μm or less is 65 to 95.
%, And a coating agent containing 5 to 35% of metal powder has a coating rate of 2
A coated arc welding rod for austenitic stainless steel, which is coated with 0 to 40%. 2. A core made of austenitic stainless steel having a C content of 0.02% or less by weight, and around the core, 10-40% of a carbonate based on the total weight of the coating agent, and fluorite. 10 to 30%, wollastonite having a particle size of 150 μm or less
0% and zirconium oxide having a particle size of 50 μm or less
A coating agent containing a total of 65 to 95% of a slag forming agent containing 15% and a metal powder of 5 to 35% has a coating ratio of 20 to 40%.
A coated arc welding rod for austenitic stainless steel, characterized by being coated with: