JPS6125474B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a flux-cored composite wire for obtaining good weld metal. Regarding welding wires used for inert gas arc welding, particularly MIG welding, it is considered necessary to have a surface as smooth as possible in consideration of current conductivity and feedability. Therefore, even if it is a solid wire, it has the disadvantage that the manufacturing cost is quite high. By the way, flux-cored composite wires have been used in carbon dioxide arc welding for a long time, and they have the advantage of being able to mix alloying elements, slag forming agents, etc. freely and easily, and their manufacturing costs are low, so their utility value is high. It is gradually increasing. One example is inert gas arc welding, especially
Composite wire for MIG welding. On the other hand, solid wires for MIG welding, which have been widely used in the past, have strong requirements for surface finish as mentioned above, and their manufacturing costs are higher than general welding solid wires, such as solid wires for carbon dioxide arc welding and solid wires for submerged arc welding. . Moreover, the above-mentioned tendency is particularly strong in wires for stainless steel, which is one of the preferred welding targets for MIG welding, and also has the following specific drawbacks. In other words, MIG welding wire for stainless steel has
Cr is added as an alloying element to match the chemical composition of the base metal, but inert gas (Ar or
Since a few percent of oxygen is often mixed into He) for gas shielding, high melting point chromium oxide adheres to the weld metal surface. However, this chromium oxide is very hard and it is not easy to remove it, so if multi-layer welding is performed with the chromium oxide remaining, defects such as blowholes and poor fusion will remain in the weld metal, resulting in extremely poor welding. It's inconvenient. For this reason, there is a growing trend to use flux-cored composite wires in MIG welding as well. This wire can not only be manufactured at a lower cost than conventional MIG welding solid wires, but also the composition of alloying elements can be changed freely, and a slag-forming agent can be added to the flux to prevent the formation of scales such as chromium oxide. There are advantages. However, composite wires are made by bending the steel strip so that the cross-sectional shape is circular or rectangular so as to wrap around the flux, regardless of its cross-sectional shape, and making the joints in the longitudinal direction stick together. Because of this, there are places where the joints are discontinuous and where the flux packing density is uneven, making it difficult to stabilize the arc when performing MIG welding. The present invention was developed in view of these circumstances, and its purpose is to prevent most of the slag from adhering to the welding surface by incorporating effective arc stabilizers and alloying elements into the flux-cored composite wire. It is an object of the present invention to provide a composite wire that can perform continuous welding satisfactorily and stably without slag removal. However, the gist of the composite wire of the present invention is as follows (1) ~
(4) It can be summarized into each point. (1) A flux-cored composite wire used for inert gas arc welding, in which the flux contains 0.05 carbonates, calculated as CO ₂ based on the total weight of the wire.
% or less, and contains 0.01 to 1.5% by weight of alkaline inorganic fluoride, and the remainder mainly consists of alloying elements for welding or alloying elements for welding and iron powder, and contains Cr, Mn, Si. The following alloying elements are blended into one or both of the wire sheath and flux, and the Cr content in the wire sheath is C (Ce), the Mn + Si content is C (Mn + Si), and the Cr content in the flux is F (Cr) Mn + Si. When the content is F (Mn + Si) and the flux ratio to the total weight of the wire is expressed as f ≦ 0.5 The proportion of alloying elements to the total electrode weight is 11% ≦ fF (Cr) + (1 - f) C (Cr) ≦ 26% 0.1%≦fF(Mn+Si)+(1-f)C(Mn+Si)≦10%. (2) A flux-cored composite wire used for inert gas arc welding, where the flux contains 0.05 carbonates, calculated as CO ₂ based on the total weight of the wire.
% or less, and contains 0.01 to 1.5% by weight of alkaline inorganic fluoride, and the remainder mainly consists of alloying elements for welding or alloying elements for welding and iron powder, and contains Cr, Mn, Si. Alloying elements consisting of the following are mixed in one or both of the wire sheath and the flux, and the Ni content in the wire sheath is C (Ni), the Cr content is C (Cr), the Mn + Si content is C (Mn + Si), and the Ni in the flux is Content rate is F (Ni) Cr content rate is F (Cr) Mn + Si content rate is F (Mn + Si) When the flux ratio to the total weight of the wire is expressed as f ≦ 0.5 The proportion of alloying elements to the total weight of the electrode is fF ( Ni)+(1-f)C(Ni)≦15% 11%≦fF(Cr)+(1-f)C(Cr)≦26% 0.1%≦fF(Mn+Si)+(1-f)C( It satisfies the formula: Mn + Si)≦10%. (3) A flux-cored composite wire used for inert gas arc welding, in which the flux contains less than 0.05% CO ₂ based on the total weight of the wire, and 0.01 to 1.5% by weight. Contains alkaline inorganic fluoride, the remainder mainly consists of alloy elements for welding or alloy elements for welding and iron powder, and alloy elements consisting of Cr, Mn, and Si are blended in one or both of the wire sheath and flux. Furthermore, the Cr content in the wire sheath is C (Cr), the Mn + Si content is C (Mn + Si), the Mo content is C (Mo), the Cr content in flux is F (Cr), the Mn + Si content is F (Mn + Si) When the Mo content is expressed as F (Mo) and the flux ratio to the total weight of the wire is expressed as f, f≦0.5 The proportion of alloying elements to the total electrode weight is 11%≦fF (Cr) + (1-f)C (Cr) ≦26% 0.1%≦fF(Mn+Si)+(1-f)C(Mn+Si)≦10% fF(Mo)+(1-f)C(Mo)≦7% . (4) A flux-cored composite wire used for inert gas arc welding, where the flux contains 0.05 carbonates, calculated as CO ₂ based on the total weight of the wire.
% or less, and contains 0.01 to 1.5% by weight of alkaline inorganic fluoride, and the remainder mainly consists of alloying elements for welding or alloying elements for welding and iron powder, and contains Cr, Mn, Si. The following alloying elements are blended into one or both of the wire sheath and flux, and the Ni content in the wire sheath is C (Ni), the Cr content is C (Cr), the Mn + Si content is C (Mn + Si), and the Mo content is C (Mo) Ni content in flux is F (Ni) Cr content is F (Cr) Mn + Si content is F (Mn + Si) Mo content is F (Mo) Flux ratio to total wire weight is expressed as f When f≦0.5, the ratio of alloying elements to the total electrode weight is fF(Ni)+(1-f)C(Ni)≦15% 11%≦fF(Cr)+(1-f)C(Cr)≦26 %0.1%≦fF(Mn+Si)+(1-f)C(Mn+Si)≦10% fF(Mo)+(1-f)C(Mo)≦7%. CO ₂ gas generated from carbonates such as CaCO ₃ , MnCO ₃ , SrCO ₃ , BaCO ₃ etc. significantly inhibits the stability of the arc and causes blowholes and poor fusion _. It is desirable to keep it below 0.05%. First, alkaline inorganic fluorides that act as arc stabilizers are not particularly limited in the present invention, but representative examples include NaF,
KF, _LiF , _K2TiF6 , _{Na3AlF3 , Li2SiF6 ,}
Such as Na ₂ SiF ₆ , K ₂ SiF ₆ , BaF ₂ , AlF ₃ etc.
Mention may be made of the fluorides of group elements, in particular of alkali metals, alkaline earth metals, aluminum group and the like.
These fluorides are usually incorporated into the flux, but should be in an amount of 0.01 to 1.5% by weight based on the total weight of the wire. The blending ratio in the flux should be changed depending on the flux rate, but as described later, the flux rate (f) in the present invention is defined as 50% by weight or less, so
[Blending ratio in f x flux] is 0.01 to 1.5% by weight
You should take care to ensure that. For example, alkaline inorganic fluoride serves as a stable source of alkali metals and lowers the ionization voltage in the arc atmosphere, so if the wire of the present invention is used, arc stability will be extremely good. If it exceeds this, the arc voltage will drop too much and the arc will tend to be short-circuited, which is not preferable. It is difficult to set a lower limit for the amount of fluoride to be added, and the above effects can be obtained if the fluoride is present even in a small amount. However, in order to obtain a reliable effect, 0.01% by weight is required.
It is necessary to mix the above. Next, in order to ensure the above-mentioned effect of the alkaline inorganic fluoride, it is desirable to adjust the flux ratio (ratio of flux weight to total wire weight: f) to 0.5 or less. The reason for this is that when the flux ratio exceeds 0.5, the degree of dispersion of the fluoride in the flux decreases and its effect becomes smaller. Although it is difficult to set the lower limit, it is generally recommended to set it to 0.1. By the way, it has been found that when such a fluoride is used, in addition to the above-mentioned arc stabilizing effect, it is possible to obtain the effect that MIG welding of stainless steel can be performed satisfactorily even when shielding with Ar gas alone. In other words, in MIG welding using solid wire, it is difficult to maintain a stable arc even if shielded with Ar gas alone, and this drawback has been addressed by mixing several percent oxygen gas as mentioned above. Ta. However, this caused problems due to the adhesion of chromium oxide. On the other hand, when the fluoride-containing composite wire of the present invention is used, a stable arc can be obtained continuously without using oxygen gas, and this is compatible with the effect of suppressing chromium oxide production by using a slag forming agent as described later. As a result, it has become possible to largely eliminate the drawbacks of known techniques. Next, alloy elements added to the wire of the present invention will be explained. These alloying elements include Ni, Cr, Mn,
These are Si and Mo, and among these, Cr, Mn, and Si are essentially blended in any composite wire.
These essential alloying elements are added to one or both of the wire sheath and flux, but they must satisfy the ranges shown in the above formulas. First, Ni is added especially when it is desired to improve the toughness and corrosion resistance of the weld zone, but as shown in the previous equation, if it is added in an amount exceeding 15% (alloying elements transferred into the weld metal), cracking resistance will deteriorate. The practical upper limit was set at 15% to show the tendency, but depending on the steel type of the metal to be welded and the purpose, it may not be necessary to add it. Cr also has the function of improving the corrosion resistance of welded parts, and this effect is most effectively exhibited especially when the object to be welded is stainless steel. The upper and lower limits must satisfy the range shown in the above formula, and the lower limit is the amount necessary to exhibit corrosion resistance, and if the upper limit is exceeded, problems will arise in terms of toughness and embrittlement at high temperatures. Next, Mn and Si must be included in the composite wire as described above, and the content range shown in the above formula is determined by taking into consideration both the deoxidizing ability and the slag forming ability. Although there was no need to set an upper limit, if it was too large, the amount of slag would increase, which could impede welding workability, so an upper limit of 10% was set for the time being. The slag forming agent mentioned in the above description mainly refers to the present alloy element, but if necessary, other slag forming agents consisting of oxides such as those in the examples below may be used in combination. Of course. However, the amount added is preferably 1.25% or less in wire weight ratio and 5% or less in flux blending ratio. That is, the oxide content is 5% in the flux blending ratio.
This is because if the slag exceeds the bead surface, the rate of slag covering the bead surface will increase, which will hinder the welding of the crater, making it difficult to obtain a sound weld without welding defects. This is because slag removal becomes necessary during the next pass welding, making it impossible to achieve the intended purpose. Finally, Mo has the effect of imparting corrosion resistance in a non-oxidizing environment. However, if the upper limit determined by the above formula is exceeded, there is a risk that the toughness may deteriorate, so although the upper limit was set at 7%, it may not be necessary to add it depending on the steel type of the metal to be welded, the application, etc. As mentioned above, the elements contained in the wire sheath and/or flux must satisfy the above formula, but in the case of inert gas welding, the alloy components of the wire are almost 100% in the weld metal. Therefore, it is easy to understand that each of the above formulas approximately corresponds to the chemical composition of the weld metal. Next, embodiments of the present invention will be described. Note that all percentages below mean percentages by weight. Example 1 A flux having the composition shown in Table 1 was placed on a mild steel hoop having a width of 12 mm and a thickness of 0.7 mm, and after bending and forming, a composite wire of 1.6 mmφ was manufactured (flux ratio: 0.25). Pure Ar is used as shielding gas (flow rate:
20/min), butt welding was performed using DCRP (welding current: 350A, welding voltage: 28V). The shape of the groove is: plate thickness: 19mm, V-groove, groove angle: 45
root height: 3 mm, root gap: almost zero, and the base material was SUS410. The alloying element content in the wire sheath is as shown in Table 2, and the chemical composition in the weld metal is shown in Table 3.

【table】

【table】

[Table] In this example, the arc stability was extremely good and the welding workability was excellent. Moreover, the X-ray performance was JIS class 1, and the side bend, face bend, and root bend of the welded part were all good, and no cracking occurred. Furthermore, Table 4 shows the results of a tensile test using all welded metal pieces.

[Table] Example 2 A composite wire with a diameter of 1.6 mm was manufactured in the same manner as in Example 1 using the flux having the composition shown in Table 5 (flux ratio: 0.25). The same base metals were butt-welded under exactly the same conditions as in Example 1, using pure Ar gas as a shielding gas (flow rate: 20/min). Table 6 shows the alloy content in the wire sheath, and Table 7 shows the chemical components in the weld metal.

【table】

【table】

[Table] Welding workability, X-ray performance, and bending of the welded part were the same as in Example 1, and were extremely good.
Table 8 shows the results of a tensile test using all welded metal pieces.

[Table] Example 3 A composite wire with a diameter of 1.6 mm was manufactured using a SUS304 steel hoop with a width of 12 mm and a thickness of 0.9 mm. The composition of the flux is as shown in Table 9, and the flux ratio was 0.12%. Butt welding was performed under the same conditions as in Example 1, except that the material to be welded was SUS304 steel. Table 10 shows the alloying element components in the wire sheath, and Table 11 shows the chemical components in the weld metal.

【table】

【table】

[Table] Welding workability, joint performance, etc. were extremely good as in Examples 1 and 2, and the tensile test results are shown in Table 12.

[Table] Since the present invention is constructed as described above, it does not cause slag such as Cr oxide to adhere to the surface of the weld metal, does not require the conventional slag removal work, and is extremely stable. It is now possible to obtain arcs continuously. Moreover, the effect of avoiding slag adhesion allows for good welding of the crater, making it possible to ensure a sound welded portion free of welding defects. In addition, in the case of stainless steel, pure Ar alone can provide good welding workability, and when combined with the use of a slag forming agent, it has become possible to obtain good welded joints.

Claims (1)

[Scope of Claims] 1. A flux-cored composite wire used for inert gas arc welding, the flux containing carbonate in an amount of 0.05% or less calculated as CO ₂ based on the total weight of the wire, and Contains 0.01 to 1.5% by weight of alkaline inorganic fluoride, the remainder mainly consists of alloying elements for welding or alloying elements for welding and iron powder, and alloying elements consisting of Cr, Mn, and Si are used for the wire sheath and flux. Cr content in the wire sheath is C (Cr) Mn + Si content is C (Mn + Si) Cr content in the flux is F (Cr) Mn + Si content is F (Mn + Si) When the flux ratio to weight is expressed as f, f≦0.5 The ratio of alloying elements to the total electrode weight is 11%≦fF(Cr)+(1-f)C(Cr)≦26% 0.1%≦fF(Mn+Si) A composite wire characterized by satisfying the following formula: +(1-f)C(Mn+Si)≦10%. 2 Flux-cored composite wire used for inert gas arc welding, in which the flux contains less than 0.05% carbonate, calculated as _CO2 , based on the total weight of the wire, and contains 0.01 to 1.5% by weight of carbonate. Contains alkaline inorganic fluoride, the remainder mainly consists of alloy elements for welding or alloy elements for welding and iron powder, and alloy elements consisting of Cr, Mn, and Si are blended in one or both of the wire sheath and flux. Furthermore, the Ni content in the wire sheath is C (Ni), the Cr content is C (Cr), the Mn + Si content is C (Mn + Si), the Ni content in flux is F (Ni), the Cr content is F (Cr) When the Mn + Si content is expressed as F (Mn + Si) and the flux ratio to the total weight of the wire is expressed as f ≦ 0.5 The proportion of alloying elements to the total electrode weight is fF (Ni) + (1 - f) C (Ni) ≦ 15% The following formula must be satisfied: 11%≦fF(Cr)+(1-f)C(Cr)≦26% 0.1%≦fF(Mn+Si)+(1-f)C(Mn+Si)≦10% A composite wire featuring: 3 Flux-cored composite wire used for inert gas arc welding, in which the flux contains less than 0.05% carbonate, calculated as CO ₂ based on the total weight of the wire, and 0.01 to 1.5% by weight. Contains alkaline inorganic fluoride, the remainder mainly consists of alloy elements for welding or alloy elements for welding and iron powder, and alloy elements consisting of Cr, Mn, and Si are blended in one or both of the wire sheath and flux. Furthermore, the Cr content in the wire sheath is C (Cr), the Mn + Si content is C (Mn + Si), the Mo content is C (Mo), the Cr content in flux is F (Cr), the Mn + Si content is F (Mn + Si) When the Mo content is expressed as F (Mo) and the flux ratio to the total weight of the wire is expressed as f, f≦0.5 The proportion of alloying elements to the total electrode weight is 11%≦fF (Cr) + (1-f)C (Cr) ≦26% 0.1%≦fF(Mn+Si)+(1-f)C(Mn+Si)≦10% fF(Mo)+(1-f)C(Mo)≦7% A composite wire featuring: 4 Flux-cored composite wire used for inert gas arc welding, the flux contains 0.05% carbonate, calculated as _CO2 , based on the total weight of the wire.
Contains 0.01 to 1.5% by weight of alkaline inorganic fluoride, and the remainder mainly consists of alloying elements for welding or alloying elements for welding and iron powder, and contains less than Cr, Mn, and Si. The following alloying elements are blended into one or both of the wire sheath and flux, and the Ni content in the wire sheath is C (Ni), the Cr content is C (Cr), the Mn+Si content is C (Mn+Si), the Mo content is C (Mo) Ni content in flux is F (Ni) Cr content is F (Cr) Mn + Si content is F (Mn + Si) Mo content is F (Mo) Flux ratio to total wire weight is expressed as f In f≦0.5, the ratio of alloying elements to the total electrode weight is fF(Ni)+(1-f)C(Ni)≦15% 11%≦fF(Cr)+(1-f)C(Cr)≦26% It is characterized by satisfying the formula: 0.1%≦fF(Mn+Si)+(1-f)C(Mn+Si)≦10% fF(Mo)+(1-f)C(Mo)≦7% composite wire.