JPH0811311B2 - Flux cored wire for stainless steel welding - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a flux cored wire for welding stainless steel, and more particularly, to a wire having improved wire drawability during manufacturing, particularly 1.2 mmφ, 1.0 The present invention relates to a stainless steel flux cored wire in which even wire with a diameter of mmφ or less has a very low frequency of wire breakage during wire drawing.

[Conventional technology]

Conventionally, manual welding with a coated arc welding rod has been mainly used for welding stainless steel, but from the standpoint of efficiency, automatic and semi-automated gas shielded arc welding is progressing.

As gas shielded arc welding of stainless steel, MIG welding method using solid wire, CO ₂ welding using flux cored wire, and MAG welding are generally applied, but blow hole and fusion failure are caused by MIG welding method using solid wire. Since the range of appropriate welding conditions that can easily cause X-ray performance is narrow and the applicable places are limited.

On the other hand, in the case of flux cored wire, the weld metal is protected by both the slag shield and the gas shield by the flux contained in the wire, so the bead shape is good and defects such as blowholes and fusion defects occur. It is rapidly spreading because of its difficulty.

In particular, in recent years, the diameter has been reduced due to the vertical posture and applicability to thinner plates, and the development of ultra-thin diameter wires of 1.0 mmφ or less is desired, and the demand for these thin flux cored wires including 1.2 mmφ Is increasing rapidly.

However, in the case of the flux cored wire for stainless steel welding, the workability of the stainless steel itself used as the outer skin is greater than that of the flux cored wire for mild steel, and the stainless steel component of the outer skin and the target welding A large amount of alloying elements must be included in the flux to adjust the difference with the metal components and to compensate for the consumption of alloying components due to welding. Since the wall thickness was thin, the wire drawing workability was deteriorated, and wire breakage problems often occurred during wire drawing.

This tendency is remarkable as the diameter becomes smaller, and the productivity of the stainless steel flux cored wire becomes lower as the diameter becomes smaller.

As a method for improving such problems, there is a technique for preventing disconnection by reducing the particle size of the flux to be filled and reducing the biting of the coarse raw material particles into the inner wall of the outer cover. No. 56-154300.

However, when these methods are applied to the production of flux cored wire for stainless steel with stainless steel as the outer skin, although the effect of reducing the number of disconnections due to the atomization of the flux is recognized, the flux filling rate seems to exceed 20%. In such cases, or when drawing a wire with a diameter smaller than 1.2 mmφ, the number of wire breaks could not be eliminated.

Further, Japanese Patent Application Laid-Open No. 59-130698 discloses a technique of performing wire drawing while maintaining the Vickers hardness of the outer skin at 300 or less by applying heat treatment, but such a method is inferior in production efficiency. In addition, it has not been possible to completely eliminate the disconnection trouble at the time of manufacturing a small diameter wire with a high filling rate such as 1.0 mmφ.

[Problems to be solved by the invention]

The present invention has been made to solve the above problems, the object is excellent in wire drawability,
In particular, it is to provide a flux cored wire for welding stainless steel, which can prevent breakage even when a thin wire is drawn.

[Means for solving problems]

INDUSTRIAL APPLICABILITY The present invention, in order to prevent wire breakage that occurs at the time of wire drawing of a stainless steel flux cored wire, in addition to the effect of the above-described flux grain refinement and heat treatment, it is essentially a stainless steel used as an outer skin. It is based on the idea that it is most effective to improve the wire drawability of the steel itself.
It is based on the finding that it is necessary to reduce the content of C, S, N, O, especially O, S as much as possible, and the gist of this is to use austenitic stainless steel as the skin 1.
In a flux cored wire with a finished outer diameter of 2 mm or less, C, N, S, O in the outer shell is C by weight ratio; 150 ppm or less,
N; 200ppm or less, S; 70ppm or less, and S (ppm) +
The flux cored wire for welding stainless steel is characterized in that 1.8 × O (ppm) is 160 ppm or less.

[Work]

The present invention will be described in detail below based on various experimental data.

First, the commercially available SUS304L wire and C, O, S, N, etc. were reduced.
The influence of these trace components on the wire drawability of the test molten wire corresponding to SUS304L was investigated.

That is, these wire rods are drawn and reduced, and after final annealing (solution treatment) at 3.6 mmφ, the wire diameter is further reduced by the wire reduction, and the total area reduction ratio to 3.6 mmφ of the wire cross section until the wire breaks occurs. The wire drawability was evaluated. Note that 2.
At the time of wire drawing of 0 mm or less, the drawing speed was slowed down, and consideration was given to reduce the experimental error by selecting the diameter of the die used so that the area reduction rate of the wire cross section after passing through the die was within 10%. Also, the range of each component of the wire used in this experiment is C: 75-341ppm, S by weight ratio, respectively.
i; 0.42-0.69%, Mn: 0.84-1.98%, P: 0.020-0.032
%, S; 8-141 ppm, Ni; 9.21-10.43%, Cr; 18.03-19.52
%, O; 20 to 120 ppm N: 63 to 625 ppm.

Figure 1 shows the results sorted by O and S contents. In the figure, ◎ indicates that the wire drawability is particularly excellent, total area reduction rate is 90% or more, and ○ is 87% or more and 90%. Less than, △
Indicates 82% or more and less than 87%, and x indicates less than 82%.

As shown in this figure, the drawability of the wire is greatly affected by the O and S contents. When the sum of S content (ppm) and 1.8 times the O content (ppm) exceeds 180 ppm, It is clear that, irrespective of the content of other components, there is no wire having particularly excellent wire drawability.

On the other hand, even when the sum of 1.8 times the S content and the O content is 180 ppm or less, not only the excellent wire drawability but also the total area reduction rate of less than 90% is considerably observed. This is considered to be due to the effects of components other than O and S.

Therefore, as a result of examining these data in detail, it was clarified that a wire rod having a low O and S content but having a relatively poor wire drawability has a high C or N content. That is, FIG. 2 shows S + 1.8 of the data shown in FIG.
Only the data where the value of × O is 180 ppm or less is rearranged by the C and N contents, and it is clear that the wire drawability deteriorates when the C and N contents exceed 150 ppm and 200 ppm, respectively. It was

From the figure, the effects of the components on the wire drawability of the wire are:
The effects of O, S, and then N, C are large, and reducing these components as much as possible is effective in improving the wire drawability.
By setting 150ppm or less, N 200ppm or less, S 70ppm or less, and S (ppm) + 1.8 x O (ppm) 160ppm or less, it is clear that a wire rod having particularly excellent wire drawability can be obtained. became.

Note that these series of wire drawability evaluation experiments were carried out with solid wires that were not filled with flux.However, in the case of experiments using flux cored wires, fluctuations in the flux filling rate, uneven thickness, etc. This is due to variations in the wire drawability of the wire itself as the outer skin, which cannot be accurately evaluated.

Therefore, the following experiments confirmed the influence of the outer stainless steel composition on the flux cored wire.

That is, the plate having the composition shown in Table 1 has a thickness of 0.2 mm and a width of 6 mm.
The SUS304L steel strip was molded into a U shape, and a flux composed of an oxide, a fluoride, an alloying agent, and a deoxidizing agent was filled in the inside of the SUS304L steel in a weight ratio of 20% to form a wire having an outer diameter of 2.0 mmφ.

When this wire was drawn and gradually reduced in diameter, the diameter of the wire in which the wire was broken was investigated.

The results are shown in Table 1 together with O, S, C, N.
The lower the content of steel strip, the finer the diameter can be drawn. Especially, C is 150ppm or less, N is 200ppm or less, S is 70ppm or less, and S (ppm) + 1.8 x O (ppm) is 160ppm or less. By this, it was found that a thin wire with a diameter of 1.0 mm can be easily obtained, and the tendency similar to that of the solid wire described above is exhibited.

The reason for limiting the numerical values of the present invention is based on the above experimental results. The C and N contents in the outer coating stainless steel are 150 ppm or less and 200 ppm or less, respectively, because C and N exceed these numerical values. In this case, no matter how the O and S contents are reduced, the wire drawability of the outer cover stainless steel is inferior, and the flux cored wire having a small diameter cannot be produced with high productivity.

Also, S (ppm) + 1.8 x O (ppm) was set to 160 ppm or less. As is clear from the experimental results, when this exceeds 160 ppm, no matter how much C and N are reduced, the outer stainless steel This is because the wire drawability of steel is not improved and it is difficult to obtain a thin flux cored wire.

Further, the outer skin targeted by the present invention has a finish diameter of 1.2 mm or less, which has conventionally been a problem of occurrence of wire breakage during wire drawing.

[Examples] The effects of the present invention will be described more specifically below with reference to Examples.

Example 1 SUS30 having an outer diameter of 8.5 mm and a wall thickness of 1.0 mm with different O, S, N and C contents
19% TiO ₂ , 8% ZrO ₂ , 4% SiO ₂ , 4% FeO, 3% Al ₂ were granulated in a 4L pipe using an inorganic binder, then dried and sized.
O ₃ , 2% NaF, 5% Mn, 2% Fe-Al, 1.5% Ni, 14% Cr, 37% SUS30
A flux composed of 4 L stainless powder was used in a weight ratio of 26
% And then bright annealing (5.2mmφ, 3.0mmφ, 1.7mmφ, 1.3mm)
φ) process to obtain JIS Z3323YF-308L applicable flux cored wire original wire.

Then, this wire original wire was further drawn, and the relationship between the number of wire breaks until reaching the finish diameter of 1.0 mmφ and the outer pipe component was investigated. The test results are shown in Table 2.

Example 2 SUS31 having an outer diameter of 7.0 mm and a wall thickness of 1.0 mm with different O, S, N and C contents
After granulating with an inorganic binder in a 6L pipe, drying,
29% TiO ₂ , 11% ZrO ₂ , 6% SiO ₂ , 6% FeO, 4% Al ₂ O ₃ ,
A flux consisting of 2% NaF, 7% Mn, 2% Fe-Al, 8% Ni, 21% Cr, 3% Mo was filled to a wire weight ratio of 19%, and the wire was drawn and brightened in a hydrogen atmosphere. Annealing (5.
0mmφ, 3.0mmφ, 1.6mmφ, 1.2mmφ) process, JIS Z33
23YF-316L corresponding flux cored wire was obtained.

The original wire was further drawn, and the relationship between the number of wire breaks until reaching the finishing diameter of 1.0 mmφ and the components of the outer pipe material was investigated. The test results are shown in Table 3.

Example 3 SUS30 having an outer diameter of 7.0 mm and a wall thickness of 1.1 mm having different O, S, N and C contents
17% TiO ₂ , 16% ZrO ₂ , 12% SiO ₂ , 6% FeO, 4% A that has been granulated in a 9S pipe with an inorganic binder, then dried and sized.
bright in _{l 2 O 3, 2% NaF} , 7% Mn, 2% Fe-Al, 7% Ni, a flux consisting of 25% Cr and filled so as to be 18% by the wire weight further drawing and a hydrogen atmosphere Annealing (5.0mm
φ, 3.0mmφ, 1.6mmφ, 1.2mmφ) process, JIS Z3323Y
The flux cored wire corresponding to F-309L was obtained.

This wire original wire was further drawn, and the relationship between the number of wire breakages until reaching the finishing diameter of 0.9 mmφ and the outer pipe material composition was investigated. The test results are shown in Table 4.

The results of Examples 1 to 3 are as shown in Tables 2 to 4, respectively, and Comparative Examples 2, 3, 7, 11 having a high C content in the outer pipe material and Comparative Example 4 having a high N content. , 5,6,8,12, and Comparative Examples 4,5,6,9,10,13 with high S + 1.8 × O value, the wire drawability was poor in all cases and the wire was drawn 10 to 30 times per 100 kg. Some degree of disconnection occurred, and without breakage, the weight of the finished product as one continuous wire without break was small, and the yield as a product was extremely low.

On the other hand, in the present invention examples 1 to 10 in which the pipe material having a low O, S, N, C content was used, almost all of the wire original wire was used for each product diameter without breaking. It could be finished as a continuous wire.

〔The invention's effect〕

As described above, the present invention uses C in the stainless steel used as the outer skin of the flux cored wire for welding the stainless steel,
By reducing N, S, and O, the wire drawability of the wire is improved, and disconnection troubles frequently occur in the conventional wire drawing process, which is an industrially unprofitable flux cored with an extremely fine diameter of 1.0 mmφ or less. This makes it possible to manufacture the wire with high productivity.

Further, even in the production of 1.2 mmφ wire, the wire drawability of the wire itself is improved, so that it is expected that productivity will be improved by reducing the number of times of annealing and the number of dies, which will greatly contribute to the industry.

Further, the present invention is more effective when combined with techniques such as atomization of the contained flux raw material and dehydrogenation treatment.

[Brief description of drawings]

Figure 1 shows all the data on the effects of O and S on the drawability of stainless steel, and Figure 2 shows S (ppm) + 1.8 x O.
It is a figure which shows the influence of C and N on wire drawability about the data whose (ppm) is 160 ppm or less.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuo Enomoto 5-10-1 Fuchinobe, Sagamihara City, Kanagawa Pref., Second Research Laboratory, Nippon Steel Corp. (72) Norihisa Ishitsubo 5 Fuchinobe, Sagamihara City, Kanagawa Prefecture ―10-1 Inside Nippon Steel Co., Ltd. Technical Research Institute No. 2 (56) Reference JP 58-202993 (JP, A) JP 57-16187 (JP, B2)

Claims (1)

[Claims] 1. In a flux cored wire having an outer diameter of 1.2 mm or less and an austenitic stainless steel outer shell, C, N, S, O in the outer shell is C: 150 ppm or less N: 200 ppm or less by weight ratio. S; 70ppm or less and S (ppm) + 1.8 × O (ppm) is 160ppm or less, stainless steel welding flux cored wire.