JPS63123596A - Flux cored wire for welding stainless steel - Google Patents

Abstract

PURPOSE:To provide a welding wire which has good weldability and with which disconnection arises hardly by filling a flux which contains specific ratios of SiO2, ZrO2, etc., and has a specific ratio of the slag content in the flux into a sheath made of a stainless steel contg. specific ratios of Ni and Cr. CONSTITUTION:The austenitic stainless steel is composed of 9.5-15% Ni, 16-27% Cr, and >=50% 3.2XNi%+Cr%. The flux components to be filled into the sheath made of such stainless steel are composed of 1.6-3.7% SiO1, 0.7-2.0% ZrO2, 0.7-4.2% TiO2, 0.1-0.7% metal fluoride and 0.3-2.3% Mn. The slag content in the flux in total is specified to 4.5-9.5 % of the total weight. The flux is filled into a pipe made of the steel strip having the above- mentioned components and the pipe is subjected to a drawing stage, by which the wire is produced. The disconnection of the wire is prevented and the good welding work is executed by the above-mentioned method.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to the improvement of a flux-cored shear wire used for gas-shielded arc welding of stainless steel. The present invention relates to a slack-cored shear wire for stainless steel welding that exhibits good welding workability with little breakage, and also has good wire drawability and extremely low breakage frequency during wire manufacturing.

[Conventional technology]

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

Gas-shielded arc welding of stainless steel using flux-cored wire protects the weld metal by both a slag shield caused by the flux built into the wire and a gas shield caused by the shielding gas. It is rapidly becoming popular because it has good properties and is less prone to defects such as protrusions and poor fusion.

Particularly in recent years, interest in small diameter wires has increased due to their applicability to posture welding and thin plates, and the demand for wires with a diameter of 1.0 mm or less is increasing.

However, in the case of flux type shear wire for stainless steel welding, compared to flux type shear wire for mild steel,
In addition to the fact that the stainless steel itself used as the outer skin has a high work hardenability, it is necessary to adjust the difference between the stainless steel component of the outer skin and the target weld metal component, and to compensate for the wear of the alloy component due to welding. A large amount of alloying elements must be contained in 7Lux, which inevitably leads to a high filling rate of 7Lux and a thin outer skin, which deteriorates wire drawability and reduces wire drawing during wire production. Breakage problems often occur during the process, and this tendency is more pronounced as the diameter becomes smaller.
The productivity of the thin stainless steel 7 lux shear wire was low.

Furthermore, during welding, the electrical resistance of the stainless steel outer skin is high, and the outer skin thickness is thin, resulting in a high current density, so an increase in the amount of spatter is unavoidable.

Particularly when welding stainless steel, it is necessary to remove spatter because it can become a starting point for corrosion, and from the perspective of reducing the number of work hours, it is very important to remove spatter.

There was a strong demand from all sides to reduce the amount of evening emissions.

Regarding this point, the present inventors previously investigated various types of shear wire for the purpose of reducing spatter in gas-shielded arc welding of stainless steel using a 7 lux shear wire, and found that the amount of spatter generated decreases as the slag content in the wire decreases. We found a tendency to
-ZrO□-Tie2 system component composition range was proposed in Japanese Patent Application No. 1982-206222.

However, in actual production, wire breakage often occurs during wire drawing depending on the charge of the outer stainless steel used, especially when the wire diameter is 1. Due to the high frequency of wire breaks in ultra-thin diameter wires smaller than Omyx, productivity was extremely low, and we were forced to take new measures to prevent wire breaks.

As a method to improve these problems, a technique for preventing wire breakage by reducing the particle size of the flux to be filled and reducing the penetration of coarse raw material particles into the inner wall of the outer skin was disclosed in Japanese Patent Laid-Open No. 56-131097. Publication No. or Japanese Patent Application Laid-open No. 1983
-Disclosed in Japanese Patent No. 154300, when these methods are applied to the production of flux-cored shear wire with a stainless steel outer sheath, although a slight reduction in the number of wire breaks is observed, when the 7 lux filling rate is high. It is unlikely that we will be able to completely eliminate the number of breaks in ultra-fine diameter wires, but the increase in raw material costs due to finer particles and the deterioration of flux supply during the flux filling process will cause problems such as flux feeders and It also causes uneven filling due to the inability to steadily discharge 7 lux from -.

Furthermore, JP-A-59-130698 discloses a technique for wire drawing while maintaining the Vickers hardness of the outer sheath at 300 or less by applying heat treatment, but such a method requires an increase in the number of heat treatments. However, production efficiency is poor and costs are high.

:Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned problems, and its purpose is to reduce the amount of spatter generated and have good welding workability. Moreover, it has excellent wire drawability,
The purpose of the present invention is to provide a flux-type wire for stainless steel welding that is extremely unlikely to break, especially when drawing a small diameter wire.

:Means for Solving the Problem] As a result of intensive study by the present inventors with the aim of reducing spatter in gas-shielded arc welding of stainless steel using a 7-lux shear wire, the amount of spatter generated is determined by the amount of slag components contained in the wire. S10□-ZrOz-
We have found the range of T102 components.

On the other hand, in order to prevent wire breakage that occurs during wire drawing of stainless steel flux-cored shear wires, apart from the effects of flux refinement and heat treatment as mentioned above, there are essentially the following:
It is necessary to improve the drawability of the stainless steel itself used as the outer sheath, and we have come to the conclusion that it is effective to increase the content of the alloy components Ni and Cr in the stainless steel sheath than ever before. .

The present invention is based on the above findings, and its gist is that the Ni content is 9.5 to 15%, the Cr content is 16 to 27%, and 3.2XNi(4)+Cr
(!l) is 50% or more in the austenitic stainless steel sheath, as a flux component at least 1.6 to 3.7% SiO0.7 to 2.0 based on the total weight of the wire.
% Z T02. 0.7~4.2% 2' T10□, 0.1~0.7% metal fluoride, 0.3~
A flux-cored shear wire for stainless steel welding is characterized in that it contains 2.3% Mn and the total slag component in the flux is 4.5 to 9.5% of the total weight of the wire.

The present invention will be explained in detail below along with its operation.

[Effect]

First of all, what is the 7 lacs shear wire of the present invention? Fig. 1 (,)
A wire with a cross-sectional shape as shown in ~(d),
This means that a filling 7 lux 2 is enclosed by a shell 1 made of pipe or steel strip.

The present invention is based on the following experimental results.

First, using SUS 304L steel strips and pipes, we manufactured flux wood shear wires with a wire diameter of 1.2n equivalent to JIS Z 3323YF-308L with different cross-sectional shapes, flux compositions, and filling rates as shown in Figure 1. , DCRP 200A 3 on SUS 304L steel plate
Carbon dioxide arc welding was performed under welding conditions of 1 N30 an/-, and the spatter generated at that time was collected in a copper collection container and weighed, compared, and the factors that affect the amount of spatter generated were studied. The studied range of the filling rate was 9 to 30%.

As a result, a clear correlation was found between the amount of slag components in the wire and the amount of spatter generated.

In other words, Figure 2 shows the relationship between the content of slag components in the wire and the amount of spatter generated.The amount of slag ivy generated is almost independent of the flux prescription, wire cross-sectional shape, and flux filling rate. It was found that the slag content decreases as the amount of slag components in the wire decreases. This is because a wire with a low slag component content has a low flux filling rate, a thick outer skin thickness, or a high amount of metal components in the flux), and the proportion of metal substances in the wire cross section is low. This is considered to be due to the fact that the current density during welding substantially decreased as a result of the increase.

However, the slag in 72, 21-man shear wire for gas-shielded arc welding has the function of adjusting the bead shape and protecting the weld metal, and generally, if its amount is insufficient,
The above effects cannot be achieved, the bead shape and bead appearance deteriorate, and the slag is stuck to the bead surface, so it is not possible to simply reduce the amount of slag.

In order to create a slag component system that does not impair slag encapsulation and slag removability even with a small amount of slag, we have repeatedly studied the slag melting point and fluidity, and as a result, we have developed a 5102-ZrO2-T102 system with a numerical range as described below. Found the slag.

Next, in order to investigate the influence of the outer stainless steel components on wire drawability, with the aim of improving the wire drawability, steel strips of type 1581 with varying amounts of Ni and Cr were used as shown in Table 1. Create a pipe with a diameter of 8B and a wall thickness of 1.1,
Among them is 5IO210%.

ZrO26%, TiO□5% t FeO2%,
At20.1%.

NaF 1%, Mn 5%, At-Mg 1%
The wire was filled with a flux consisting of 18% Ni, 48% Cr so that the filling rate was 24%, and was subjected to light tube wire drawing and three times of bright annealing to obtain a 7 lux shear wire with a diameter of 1.6.

And after final annealing at 1.6 m+φ, 1.0
The number of times each wire was broken until it reached the finished diameter of miφ was investigated for each die.

The results are shown in Table 2. Wires with outer shells containing higher amounts of Nl and Cr alloy components had a lower frequency of wire breakage and showed a tendency to be able to be drawn to small diameters without breakage.

Therefore, in order to confirm the influence of these Ni and Cr contents in more detail, the horizontal axis shows the Cr content in the outer stainless steel, and the vertical axis shows the Ni content, and the wire drawability was plotted.

As this figure shows, Ni in the outer stainless steel,
As the Cr content increases, wire breakage becomes less likely, especially at 3.2.
It was found that when the value of XNi (%) + Cr (%) was 50 or more, wire breakage hardly occurred.

Note that the mark O (outer skin unevenness, 7°9) in Figure 3 indicates that wire breakage occurred several times during the final wire drawing, but wire breaks of this magnitude could be prevented by making slight adjustments to the die schedule during actual production. It was judged to be within the possible range.

The reasons for limiting each numerical value other than the above defined in the present invention will be described above.

First, the Ni content in the stainless steel outer shell is 9.5 to 15.
The reason for setting q6 is that if it is less than 9.54, the amount of Ni in the weld metal will be small, and it will be difficult to design a prescription for a flux choir as defined in JIS Z 3323, for example. Furthermore, when the Cr content is relatively high, the amount of ferrite is large and cracks occur during hot rolling, making it impossible to make steel bands or pipes.

If the shear wire exceeds 15, the Ni content in the weld metal is too high.
There is no need for an amount of Ni exceeding 1.

The reason for setting the Cr content in the stainless steel outer skin to 16-27% is that if it is less than 16%, the amount of Cr in the weld metal will be small.)
This is because it becomes impossible to design the wire prescription.

If the Cr content exceeds 27 inches, there will be a large amount of ferrite, and as mentioned above, cracks will occur during hot rolling. Further, according to the current wire standards, there is no need for a Cr content exceeding 27%.

Next, regarding the flux component, 8102 is a necessary component to form a slag with good encapsulation, but 1.6
If it is less than 3.7%, the effect cannot be exhibited and the slag encapsulation property deteriorates, and if it exceeds 3.7%, the slag seizes and the releasability deteriorates. 5102 Raw materials include silica sand, silica stone, and wollastonite.

Sub-components of raw materials such as zircon sand and potassium feldspar can be used.

Z ro 2 is an effective ingredient for imparting fluidity to slag and reducing the amount of slag; if it is less than 0.7%, its effect is insufficient; on the other hand, if it exceeds 2.0%, If the flux is difficult to melt, the difference in melting time between the wire outer sheath and the internal flux increases and the shear arc condition deteriorates. As raw materials, zirconium oxide, zircon flour, zircon sand, etc. can be used.

TlO2 forms a dense slag with good peelability, but 0
．． If it is less than 7%, the effect will not be exhibited, and if it exceeds 4.2%, the fluidity of the slag will deteriorate, the amount of slag required to ensure slag envelopment will increase, and slag will occur. It becomes easier. Raw materials include rutile, titanium white, and titanium slag.

Illuminite, and titanates such as potassium titanate, sodium titanate, and calcium titanate are used alone or in combination.

Metal fluoride is added to adjust the melting point of slag and improve pitting resistance. If it is less than 0.1 q6, pitting resistance cannot be ensured, and if it exceeds 0.7%, the slag melting point is too low. As the bead shape deteriorates, the amount of snow ivy increases due to the generation of fluorine gas. C as a metal fluoride
aF2, NaF.

AtIP, MgF2. Although LiF and the like are used alone or in combination, within the above range, no particular difference was observed in the effect of any of the 7° compounds.

In the present invention, the slag component refers to non-metallic components such as oxides and fluorides;
In addition to heptadide, At203 g F*Oe is used to adjust the basicity of slag and finely adjust the melting point and fluidity of slag.
MgO* CaOe MnOtBaO, Cr2O3, Nip used for adjusting alloy yield.

Na2O, K2O, Li2O used for arc condition adjustment
3.

Furthermore, pbo is used to improve slag removability.

B1□03 etc. Furthermore, p as an impurity of these raw materials
, s, etc. are also included.

In the present invention, one point is that the total slag component including these is in the range of 4.5 to 9.5% of the total weight of the wire, but this means that the slag component amount is 9.5% or less. If it exceeds the limit, not only will the amount of ivy increase rapidly as described above, but also the drawability of the wire will deteriorate.

If it is less than 4.5%, no matter how good the slag type is, the amount of slag will be insufficient and it will be impossible for the slag to cover the bead surface.

Excessive amounts of alkali metal oxides such as Na2O and K2O will cause an increase in ivy, so the total amount should be within 0.6 cm, while low melting point compounds such as Bi2O and PbO will cause deterioration of the bead shape and decrease in toughness. Therefore, the total: fi 0.
2% or less is desirable for each.

In addition, depending on the raw material particle size, flux components, filling method, etc., flux may be used after being granulated with a binding agent. , K2
It is necessary to mix the raw materials by taking into consideration the possibility that O, etc. will increase.

Next, Mn is added as a deoxidizing agent, and has the effect of improving cracking resistance and stabilizing the arc, but if it is less than 0.3%, the effect cannot be exhibited, and if 2.3% Exceeding this will impair slag fluidity and slag removability.

Note that the term Mn refers to metal manganese or ferromanganese, and does not include Mn derived from iron powder or stainless steel powder.

This is because Mn, which is contained in iron powder or stainless steel powder in an amount of about 2 tres at most, cannot be expected to be effective as a deoxidizing agent.

Now, referring to the cross-sectional shape of the wire, as stated at the beginning, the present invention does not specifically adopt a wire cross-sectional shape. However, in wires with a simple circular cross section as shown in Figures 1(a) to (c), the welding current flows only to the outer skin of the wire, which delays the melting of the flux in the core, resulting in a disordered arc). Concentration becomes worse,
Although there is a tendency for slag entrainment to occur, in such cases it is desirable to increase the amount of metal components in the 7 lacs (for example, 65 lacs or more). This is because a large amount of metal powder with a relatively low melting point infiltrates between the high melting point oxides such as 810 * TiOe and ZrO2 that form the main component of slag, causing the metal itself to become the point of arc generation. This is thought to be due to the fact that the high melting point oxide is melted first even if it does not become a generation point, so the entire 7 lux is extremely easily melted, and as a result, there is no difference in the timing of melting with the outer skin.

For this purpose, it is necessary to determine the alloying component concentration of the alloying agent used and the flux filling rate depending on the outer skin component to be used and the target weld metal component.

The effects of the present invention will be illustrated in more detail by examples below.

〔Example〕

Various wires corresponding to JISZ 3323 with the compositions shown in Table 4 were manufactured using stainless steel /4 tubes and steel strips with the compositions shown in Table 3. That is, the one using guibe as the outer skin is the seamless type shown in Fig. 1 (&), and after final annealing with a wire diameter of 1.1°n,
The finished diameter was drawn to f1lφ. Furthermore, for wires finished without disconnection, DCRP 130A 27
SUS 304 under V 20 cm/5kcl welding conditions
Flat plate welding was performed on L steel plate and welding workability was investigated.

In addition, the cross-sectional shape shown in FIG. 1(d) is used for the outer skin made of steel band, and 2. After molding with Otsxφ, 1.2
The wire was drawn to a finished diameter of flφ. Furthermore, for wires finished without disconnection, DCRP 200A31V30
Flat plate welding was performed in the same manner as above under the welding conditions of cIn/-, and the welding workability was compared.

The results are shown in Table 4. Wire cables using stainless steel strips or Tsukuib with low Ni content and low 3.2 x Ni(4) + Cr(A) values as the outer sheath
, 2, 3, 4, 5, 6, 7, and 20.48 all had poor wire drawability, and wire breakage occurred during the wire drawing process.

In addition, sio□, ZrO□, wire flattened with low metal fluoride content 12, 15, 17, 26, 30° 31.3
8, 41, 42. Wire A with low slag content 12
, 23, Wire A43 with a high Tie2 content had insufficient slag encapsulation.

Furthermore, 5102 or wire flat 1 with high Mn content
9, 24, 37, Wire 423, 25.41 with low Tie2 content had poor slag releasability; Wire 16, 25.41 with high OZ rO2 content. and M
Wire 410 with a low n content had poor arc condition.

Further, in the case of wire wires 18, 38, 11, and 36°53, which have a large amount of metal fluoride or slag components in the wire, the amount of spatter generated increased.

In particular, in the case of wire 1627, which had a large amount of slag component and a high 7 lux filling rate, wire breakage occurred despite the good wire drawability of the stainless steel sheath.

On the other hand, the Nl and Cr contents of the outer stainless steel are high, and 3.2 × Nl (%) + Cr (4
) value of 50 or more, and the flux component range and slag component amount are appropriate.In the case of the present invention's 7-lux shear wire, there is no occurrence of wire breakage, good arc condition, and no spatter generation. The amount was small, there were no problems with slag envelopment and slag removability, and extremely good welding workability was exhibited.

In addition, the evaluation of welding workability in Table 4 is as follows.

◎: Very good, O: Good, Δ: Slightly poor, ×: Poor.

〔Effect of the invention〕

As described above, the present invention prevents wire breakage in the wire drawing process by specifying the amount of the stainless steel alloy component used as the outer sheath, as well as the amount of the 7 lux component and slag component contained therein. This is a flux-cored shear wire for welding stainless steel with good welding workability and improved productivity, and is particularly effective in producing ultra-thin diameter wire.

[Brief explanation of the drawing]

Figure 1 (a) # (b) t (e) # (d) is a schematic diagram showing the cross-sectional shape of various flux shear wires, and Figure 2 shows the relationship between the slag component content in the wire and the amount of spatter generated. Figures 3 and 3 are diagrams showing the influence of Ni and Cr contents on the wire drawing of outer stainless steel. 1... Outer skin 2... Filling flux 3.
... seam. Figure 1 Figure 2

Claims (1)

[Claims] Ni content is 9.5-15%, Cr content is 16-27
% and 3.2×Ni (%) + Cr (%) is 50% or more in the austenitic stainless steel outer skin, as a flux component at least 1.6% based on the total weight of the wire.
~3.7% SiO_2, 0.7-2.0% ZrO_
2, 0.7-4.2% TiO_2, 0.1-0.7%
metal fluoride, 0.3 to 2.3% Mn, and the total slag component in the flux is 4% of the total weight of the wire.
．． A flux-cored wire for stainless steel welding, characterized in that the flux is 5 to 9.5%.