JPH0255696A - Flux cored wire for gas shielded arc welding - Google Patents

Abstract

PURPOSE:To decrease the amt. of the spatters to be generated by incorporating BaF2, Al, Mg, Fe, Mn, and Si respectively at specific % by weight into the flux and regulating the flux filling ratio to a prescribed ratio. CONSTITUTION:The flux cored wire is formed by incorporating 3-10% BaF2, 3-30% Al, 1-10% Mg, 40-80% Fe, 5-25% Mn, and 2-15% Si by weight into the flux and filling the flux into the cavity of a sheath metal at 10-30% ratio. Gas shielded arc welding is further executed with the polarity ot an electrode as a DC positive polarity at the time of welding. The BaF2, Al and Mg components in the wax respectively improve the arc stability and further, the Mn, Fe and Si improve welding quality. Since the DC positive polarity electrode is used, the BaF2 component contribute to the formation of smaller and smoother droplets. The amt. of the spatters to be generated is eventually decreased.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a gas-shielded arc welding flux-cored wire, which is characterized by low spatter generation especially at low currents, and is suitable for welding mild steel and high-strength steel, especially welding thin plates, etc. The present invention relates to a suitable gas-shielded arc welding flux-cored wire. (Prior art and problems to be solved) Gas-shielded arc welding flux-cored wire has good welding workability (spatter, arc stability, etc.) and welding efficiency, as well as excellent bead appearance. Due to its advantages, its usage tends to increase more and more. However, 1. Normal flux-cored wires do not necessarily have a wide welding current range, and it is difficult to obtain a good spray arc, especially in the low current range. Therefore, in welding work using a low current (approximately 100 to 200 A) such as thin plate welding, a large amount of spatter is generated, and welding workability cannot be said to be good. The present invention was made under the following circumstances, and
It is an object of the present invention to provide a gas-shielded arc welding flux-cored wire that enables stable spray arc over a particularly wide current range and has good welding workability. (Means for Solving the Problems) In order to achieve the above object, the present inventors conducted research from various directions with emphasis on the composition of the included flux. , and it has been discovered that this is possible by using DC with positive polarity. That is, in the present invention, BaF: 3 to 10%, An: 3, based on the total weight of the flux, are added to the cavity surrounded by the outer metal.
~30% 1Mg: 1-10%, Fe: 40-80%, M
A flux-cored wire for gas-shielded arc welding for direct current positive polarity, characterized in that it is filled with a flux having a composition of n: 5-15% and Si: 2-15% at a flux filling rate of 10-30%. This is a summary. The gas-shielded arc welding flux-cored wire of the present invention has the above-mentioned configuration, and its features include that as a DC positive polarity gas-shielded wire, BaF is used as the filling flux;
, Al, Mg, etc., it is possible to exhibit characteristics such as low spatter. In other words, in order to achieve the characteristics of ``a stable spray arc and less spatter generation, even when welding at low currents,''
The following ■ to ■ are the most important. ■Apply DC positive polarity when welding. ■BaF2, Afl, Mg as main components in flux
were added at the same time. The present invention will be explained in more detail below. First, the reasons for limiting the flux components in the present invention will be explained. Note that the amount of each component is a ratio to the total weight of the flux. As a result of various studies on the flux composition of flux-cored wire for gas-shielded arc welding, the present inventors first focused on fluoride and investigated the relationship between fluoride in flux and the amount of spatter generated and welding workability. In addition,
The test wire and welding conditions in the experiment were as shown in ■ and ■ below, and spatter was collected as shown in Figure 1.
A method was used in which the test plate 4 was covered with a copper hollow collector 1 that was open only in areas that did not impede the movement of the welding torch 2, and the spatter after welding was collected in the collector 1. Ω - Furnace metal: Mild steel flux and flux rate = (Na 1 in the examples described below)
The amount and type of fluoride were changed based on No. 2, and FeJl was increased or decreased according to the amount of fluoride. Other components are the same as Nα12) Wire cross-sectional shape: (A in Figure 7) Wire diameter: 1.4n+s+φ 4-sho welding current: 150A, DCEN (direct current positive polarity) Arc voltage: 18v Welding speed = 40c Ken/■in Seal gas
+ amW Furthermore, Figure 2 shows the results of various studies on the types of fluoride that should be added, and Figure 3 shows the results of various studies on the types of fluoride that should be added, and Figure 3 shows the results for investigating the appropriate addition amount of BaF, which was selected as an essential component based on the results of Figure 2. The test results are shown when the amount of addition is increased or decreased.6 First, when different types of fluoride were examined, as shown in Figure 2, good results were obtained with alkali metal or alkaline earth metal fluorides. Among them, BaF was the best in terms of sputtering, etc., so BaF was essential as the fluoride to be added. Furthermore, as is clear from Fig. 3, the amount of spatter generated tends to be significantly reduced by adding 3 to 10% BaF to the flux, and welding workability is also very good within this range. When it was less than 3%, the amount of spatter generated was large and workability was poor, and when it exceeded 10%, the bead appearance was poor. Therefore, the amount of BaF in the flux is 3-10%
It turned out that it was necessary to stop the temperature within the range of . (2) 15P4 Punishment Al and Mg have been known to be effective components for improving the physical properties of weld metal through their deoxidizing action, but in the present invention, stable arc welding is possible. Both are indispensable flux raw materials to carry out this process. Furthermore, as a result of various studies, the present inventors have found that spatter can be reduced by adding Al and Mg. Therefore, in order to find the appropriate amounts of Al and Mg to be added, we investigated the relationship between the amount of Al and Mg in the flux wire and the amount of spatter generated. Note that the test wires and welding conditions were in accordance with the conditions ① and ① described above and in Fig. 1. As a result, first, as shown in FIG.
If the amount is less than 3% of the total flux, the arc will be unstable and the amount of spatter generated will be very large. However, if it exceeds 30%, problems such as excessive deoxidation, increased Al content in the weld metal, decreased toughness, and unfavorable bead appearance occur. Therefore, the amount of aluminum in the flux is in the range of 3 to 30%. Further, as shown in FIG. 5, if the amount of magnesium in the wire is less than 1% of the total flux, the arc is unstable and a large amount of spatter is generated. However, if it exceeds 10%, the arc blowing becomes too strong, making it unsuitable for welding thin plates, and excessive deoxidation causes deterioration of weld metal performance and deterioration of bead appearance. Therefore, the amount of magnesium is in the range of 1 to 10%. Note that typical addition forms of Al and Mg include pure Al,
Fe-Al, pure Mg, Fe-Mg, AQ-Mg
Examples include powders such as. (3) Fe Since Fe has the effect of increasing the amount of deposited metal and increasing welding efficiency, it has the effect of relatively reducing the amount of slag generated with respect to the weld metal. For that purpose, it is necessary to add 40% or more. However, when Fei exceeds 80%, other components such as deoxidizer, fluoride, Al1. The amount of Mg etc. decreases relatively, resulting in deterioration of workability (especially sputtering) and performance. Therefore, Feff1 is 40-80%
The range shall be . Note that Fe is mainly added as iron powder, but Fe-Mn, Fe-8L, Fe-kQ, Fe-M
Of course, this also includes the case where it is added in the form of an alloy such as g. (4) Mn Mn is retained in the weld metal through deoxidation reaction, imparts toughness, and improves impact performance. In order to achieve this effect, it is necessary to add at least 5% or more of the total amount of flux. However, addition of more than 15% is not preferable because it causes an abnormal increase in the strength of the weld metal or causes excessive deoxidation in coexistence with Al. Therefore, the amount of Mn is in the range of 5 to 15%. It goes without saying that Mn may be added not only in the form of metal Mn but also in the form of an alloy such as Fe-Mn. (5) Like Mn, 5i SL is necessary to ensure performance, but it also improves the compatibility between the base metal and weld metal, and adjusts the viscosity of the slag to achieve a flat and good bead. Add for. For this purpose, at least 2% is necessary. However, addition of more than 15% impairs the toughness of the weld metal and deteriorates impact performance. Therefore, the amount of Si is in the range of 2 to 15%. It goes without saying that Si may be added not only in the form of metal Si but also in the form of alloys such as Fe-5i and Cu-5L. (6) The filling rate of flux to the outer skin metal of Yuniri Menghisa is 10 to 30%.
A range of is preferred. If it is less than 10%, it will not be possible to fill a sufficient amount of metal powder, slab forming agent, etc., and the original performance will not be exhibited. On the other hand, if it exceeds 30%, the outer metal must be made thinner, the wire becomes softer, and the feedability deteriorates. Electricity conductivity and arc stability are also deteriorated, and undercuts and the like are more likely to occur. Therefore, the flux filling factor is 10
The range is 30%. (7) Other conditions (flux component, metal sheath) As mentioned above, in the present invention, BaF, , A Q ,
Although Mg, Fe, Mn, and Si are essential flux components, it is of course possible to add arc stabilizers, slag forming agents, alloy components, etc. in addition to these essential components as necessary. For example, with regard to fluoride, it is of course possible to add other fluorides in addition to BaF, but if added, considering the purpose of the present invention, an alkali metal or alkaline earth metal It is desirable to use fluoride of
Also, regarding the amount added, BaF2 in the total fluoride is 50%.
It is recommended to add other fluorides to achieve the above. Furthermore, if the amount of C in the wire is too large, it will affect the amount of fume and spatter generated. The effect is BaF
Although the degree is smaller than that of Al21Mg, it is recommended to suppress it to 0.08% or less based on the total weight of the wire. (8) In the present invention, it is essential to use DC positive polarity in welding. Regarding polarity, there are alternating current and direct current, and in the case of direct current, there are two types: direct current reverse polarity (DCEP) and direct current positive polarity (DCEN), and generally DC reverse polarity is used. However, in the wire of the present invention, the polarity during welding must be DC positive polarity from the viewpoint of welding workability (arc stability, spatter, etc.), and AC and DC reverse polarity are not practical for welding. Can not. In other words, as an example of the effect of polarity is shown in Figure 6 (results were carried out according to welding conditions ① in the above test), with the wire of the present invention, good work was achieved only with DC positive polarity. It can be seen that the characteristics (amount of spatter generated, etc.) are shown. This is one of the major features of the present invention. This can be considered as follows. Generally, when a welding wire is used with DC (-) (direct current positive polarity), a *12 force is applied to the droplet by cations at the tip of the wire, which prevents the droplet from detaching. As a result, welding workability (spatter, arc stability, etc.) is poor. However, in the case of the barium fluoride-based flux-cored wire according to the present invention, in addition to the impact force caused by the cations peculiar to positive polarity, a large reaction force due to the evaporation of high vapor pressure BaF, etc. acts on the droplet, so the wire The droplet at the tip is impacted by the resultant force, transforms into a small droplet grain, and smoothly transfers to the base material. Therefore, DC(-)
It shows good workability (spatter, arc stability, etc.). Note that the cross-sectional shape of the wire is not limited in any way; for example,
Various shapes shown in FIGS. (A) to (D) can be used. In the case of shape (D) (seamless), AΩ is applied to the wire surface.
, Cu, etc. may be applied, and the amount of plating (wt% relative to the total weight of the wire) is preferably 0.005 to 0.20%. If it is less than 0.05%, rust resistance, feedability, electrical conductivity, etc. If it exceeds 0.20%, productivity and toughness of the weld metal will decrease, which is not desirable. In addition, the wire diameter is not limited at all and can be adjusted depending on the application.
2mm, 1.4mm, 1.6ms+, 2.0+
The diameter can be set as appropriate from m, 2.4 mm, 3.2 mm, etc., but from the viewpoint of thin plate welding and arc stability, a diameter of 1°2 to 1.6 m is desirable. Furthermore, CO3 and Ar-CO2 are used as shielding gases.
Any mixed gas etc. can be used. Further, as for applicable steel types, the present invention is preferably applied to mild steel and high-strength steel, but it is of course applicable to other steel types. The present invention is particularly suitable for welding thin plates. In addition, all-position welding is possible. Next, examples of the present invention will be shown. (Example) Flux-cored wires having various flux compositions shown in Tables 1 and 2 (wire diameter: 1.4 φ, outer sheath:
A wire cross-sectional shape of mild steel (the shape shown in FIG. 7(A)) was prepared, and gas-shielded arc welding was performed on a mild steel base material (thickness: 6 mm) under the following welding conditions. Table 3 shows the results of evaluating the amount of spatter generated and other welding workability. ' Article -' Welding current: 150A Arc voltage: 19v Welding speed: Approx. 40cm/1lin Shielding gas: CO, (Flow rate: 20 Q/win)
Wire protrusion length: 20n+m Polarity: DCENC (DC positive polarity) Posture: Horizontal fillet As shown in Table 3, all five examples of the present invention are excellent in welding workability, mainly in terms of the amount of spatter generated. There were no problems during manufacturing. On the other hand, in comparative examples under conditions outside the scope of the present invention, there was a lot of spatter. Alternatively, if there is little spatter, workability, etc. (bead appearance, welding efficiency) is poor.

[Left below]

(Effects of the Invention) As detailed above, according to the present invention, since a flux-cored wire filled with a flux of a specific composition at a predetermined flux rate is used with direct current positive polarity, it is possible to The welding current range is wider than that of wire, and low spatter welding is possible with a spray arc that is stable even in the low current range.

[Brief explanation of the drawing]

Figures 1 (a) to (c) are spatter collectors (copper hollow)
A diagram showing the outline (structure, dimensions (,,+n,)) of
) is a plan view, (b) is a side view, (c) is a front view,
Figure 2 shows the amount of spatter generated when various fusilides are used as flux raw materials (addition amount: 5%), and Figure 3 shows the proportion of B a F z II in the total amount of flux.
Figure 4 is a diagram showing the relationship between the amount of Al in the total amount of flux and the amount of spatter generated. Figure 5 is a diagram showing the relationship between the amount of Mg in the total amount of flux and the amount of spatter generated. FIG. 6 is a diagram showing the relationship between wire polarity (DC reverse polarity, DC positive polarity, AC) and the amount of spatter generated. FIGS. 7A to 7D are diagrams each showing an example of the cross-sectional shape of a flux-cored wire. 1... Spatter collector, 2... Welding torch, 3...
-Wire, 4...Test plate (material to be welded), F...Flux, M...Sheath metal. Patent author Takashi Nakamura, Patent attorney representing Kobe Steel, Ltd. Fig. 1 Fig. 2 Fig. 3 Various fluoride compounds Fig. 4 AJLq (WT-7a nof l oxidation toughness t (wt%)) Fig. 5 Figure 7 (A) (B) Figure 6 Procedure Amendment Band September 17, 1986

Claims (1)

[Claims] In the cavity surrounded by the outer metal, per total weight of flux,
BaF_2: 3-10%, Al: 3-30%, Mg: 1
-10%, Fe: 40-80%, Mn: 5-15%, and Si: 2-15% at a flux filling rate of 10-30%. Flux-cored wire for gas shielded arc welding.