JPH0446677B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Industrial Application] The present invention relates to a flux-cored wire for gas-shielded arc welding, and in particular to an iron powder-based flux-cored wire that can reduce the amount of spatter and is particularly suitable for welding mild steel and high-strength steel. It is something. [Conventional technology] In recent years, the use of gas-shielded arc welding, which is advantageous in improving welding efficiency and promoting labor savings, has rapidly become popular in the welding construction of various structures such as ships and bridges. It has been increasing. In particular, iron powder-based flux-cored wire has the characteristics of a higher welding amount and less slag generation than general titania-based flux-cored wire, and its usage tends to increase more and more. However, the biggest drawback of this wire is that it generates a large amount of spatter, which requires a lot of effort to remove.
It can even double. Under these circumstances, there has been a strong desire to develop a flux-cored wire for gas-shielded arc welding that has the two characteristics of high welding amount and low slag, and also generates less spatter. [Problems to be Solved by the Invention] The present invention has been made in view of these circumstances, and its purpose is to reduce the amount of spatter and to reduce the amount of spatter generated.
The object of the present invention is to provide an iron powder-based flux-cored wire that can provide a high welding amount and excellent welding workability. [Means for solving the problem] The iron powder-based flux-cored wire of the present invention contains 40 to 88% iron powder, 10 to 45% deoxidizer, and arc stabilizer.
0.5-5%, and other components especially Al ₂ O ₃
The flux containing 1 to 15% of the slag forming agent (containing 30% or more of slag forming agent) is filled in the steel jacket in an amount of 10 to 30% of the total weight of the wire, and The gist of this is that the amount of carbon is limited to 0.05% or less. [Function] The iron powder-based flux-cored wire according to the present invention obtains a weld metal amount comparable to that of a solid wire by blending iron powder into the flux component, and also reduces the flux component, its blending amount, and C in the entire wire.
By appropriately limiting the amount, spatter can be reduced. In particular, the slag forming agent of the present invention is limited to one whose main component is Al ₂ O ₃ , and the amount of C in the entire wire is Its greatest feature is that it is set at 0.05% or less. This makes it possible to obtain a welded part with excellent bead shape and weld metal performance while achieving the object of the present invention, particularly reducing spatter. The configuration of the present invention will be explained below based on experimental results. The experimental conditions were as follows. [Sample wire] Wire diameter: 1.4mmφ Sheath metal: Mild steel Cross-sectional shape: Figure 4 A below Flux: Iron powder type (Table 1 No. 1 below) Flux rate: 15% [Welding conditions] Welding current: 300A Arc Voltage: 32V Welding speed: 30cm/min Shielding gas: CO ₂ , 20/min Distance between chip and base metal: 20mm Base metal: SM41B (12mmt) Welding method: Bead-on-plate method [method for measuring amount of spatter] Examples described later Figure 1 shows the relationship between the amount of carbon (%) in the total wire and the amount of spatter generated. From FIG. 1, it can be seen that the amount of spatter generated increases rapidly as the carbon content (%) in the total wire increases, particularly up to around 0.05%, but thereafter the change is small. In other words, the amount of carbon (%) in the total wire
It has become clear that if the content is kept below 0.05%, the generation of spatter can be effectively suppressed. Figure 2 shows the relationship between the type of slag forming agent and the amount of spatter. Slag forming agents are generally added as flux components to improve bead shape and weld metal performance, but preliminary experiments have shown that the amount of spatter generated varies significantly depending on the type of slag forming agent. I found out that it is coming. Therefore, the present inventors conducted a detailed study on the type of slag-forming agent and the amount of the slag-forming agent that can more effectively achieve the object of the invention. As a result, as is clear from Fig. 2, TiO ₂ , SiO ₂ ,
It has been found that among the typical slag forming agents such as ZrO ₂ , Al ₂ O ₃ , MnO, Fe ₂ O ₃ and MgO, the amount of spatter generated is the least when Al ₂ O ₃ is used. That is, it has become clear that selecting Al ₂ O ₃ from among various slag forming agents is effective in reducing spatter. Although the reason why Al ₂ O ₃ is effective in reducing spatter is currently not clear, the following may be considered. Generally, the slag forming agent covers the surface of the droplet and moves toward the base metal along with the droplet due to the arc force, but the impact at this time causes the molten slag on the surface of the droplet to scatter and appear as spatter. It is believed that the generation of spatter can be suppressed by weakening the arc force. On the other hand, the repulsive force due to slag evaporation is also considered to be one of the factors that affects the arc force, and it is expected that lower vapor pressure will lead to a smaller arc force. This point
Al ₂ O ₃ has a relatively low vapor pressure, and is expected to have an arc stabilizing effect due to the low ionizing voltage of Al, so it generates less spatter than other slag forming agents. it is conceivable that. Although it has been clarified above that the use of Al ₂ O ₃ is effective as a slag forming agent, the slag forming agent according to the present invention may contain 30% or more of Al ₂ O ₃ as a main component. . This is because if it is less than 30%, the amount of Al ₂ O ₃ in the forming agent will be relatively small, and the effect of reducing spatter will not be sufficiently exhibited. Therefore, other slag forming agents can be arbitrarily selected and blended as subcomponents in a range of less than 70%. These slag forming agents include common oxides such as TiO ₂ , SiO ₂ ,
ZrO ₂ , MnO, MgO or iron oxide (Fe ₂ O ₃ ,
Fe ₂ O ₄ , FeO, etc.), and these can be used alone or in combination of two or more. However, if the slag forming agent is added to the flux in an amount of 15% or more, the amount of slag increases and problems such as slag entrainment occur, which actually defeats the purpose of the present invention. On the other hand, if it is less than 1%, the effect of the slag forming agent cannot be fully exhibited. That is, from the above findings, the iron powder-based flux-cored wire of the present invention is
As a slag forming agent, a slag forming agent containing 30% or more of Al ₂ O ₃ (based on the total amount of slag forming agent) must be contained in an essential amount of 1 to 15%. Next, the relationship between the flux rate and the amount of spatter, which is another important requirement for achieving low spatter, will be explained. FIG. 3 shows the relationship between the flux rate and the amount of spatter. As is clear from FIG. 3, the amount of spatter generated decreases as the flux rate increases. This is thought to be because droplet transfer tends to become a spray during welding as the flux rate increases. However, if the flux rate is set too high, the thickness of the outer metal will become too thin and the wire will become soft, making the feeding unstable during welding work and causing defects such as undercuts due to arc instability. It becomes easier to do. On the other hand, if the flux rate is too low, the amount of spatter will increase and other components such as iron powder and slag forming agent will not be sufficiently blended. From these facts, it was concluded that it is desirable for the iron powder-based flux-cored wire of the present invention to have a flux rate in the range of 10 to 30%. The main components of the iron powder-based flux-cored wire of the present invention have been described above, but the present invention is particularly advantageous in that, compared to the conventional technology, (1) the amount of C in the entire wire is low;
It is characterized by using a slag forming agent whose main component is Al ₂ O ₃ and (3) setting the flux rate to 10 to 30%, which can significantly reduce the amount of spatter generated. It is. However, the present invention cannot be completed by satisfying only the above three elements; in order to fully achieve the purpose of the present invention, the following general requirements for iron powder-based flux-cored wires must also be met. There is a need. That is, by fully considering the relationship with the amount of spatter generation and taking into account the properties originally required as a flux component, the preferred content of each component is determined as follows. Iron powder: 40-88% In order to fully achieve the effect of improving welding efficiency, which is a characteristic of iron powder-based flux-cored wire, the iron powder is 40% to 88%.
% or more should be added. However, if it exceeds 88%, other components such as slag forming agents will be relatively reduced, resulting in poor bead shape, insufficient sealing and welding defects such as bits and blowholes, and arc instability. This would actually defeat the purpose of the present invention, such as increasing the occurrence of spatter. Deoxidizing agent: 10-45% As the name suggests, deoxidizing agent is an effective component to reduce the amount of non-metallic inclusions in weld metal and improve the physical properties of weld metal through deoxidizing action, and is a typical component. Examples include metals such as Mn, Si, Al, Mg, Ti, and Zr, and iron alloys thereof. Of course, these may be used alone or in combination of two or more. If the amount of deoxidizer is less than 10%, deoxidation will be insufficient and the X-ray performance will be poor. Therefore, it must be contained at 10% or more. But 45
%, the deoxidation becomes excessive and the toughness and cracking resistance of the weld metal deteriorate. Note that the deoxidizing agent suppresses the generation of CO (or CO ₂ ) gas, which causes spatter, and is therefore effective in reducing spatter, and from this point of view, it is recommended that the content be preferably in the range of 25 to 45%. . Arc stabilizer: 0.5-5% Arc stabilizer refers to a substance that easily ionizes in the arc, such as Li, Na, K, Rb, Cs, Ca, Sr,
Examples include oxides such as Ba, fluorides, carbonates, and nitrates. Although these materials are effective in stabilizing the arc and reducing spatter, 0.5%
If it is less than 5%, the effect cannot be sufficiently exhibited, and if it exceeds 5%, the amount of slag and fume generated increases, which is not preferable. Practically preferred arc stabilizers include K ₂ Ti ₄ O ₉ , K ₂ SiO ₃ ,
Examples include Na ₂ SiO ₃ , K ₂ ZrO ₃ , K ₂ ZrSiO ₅ and LiFeO ₂ . As the outer skin metal used in the present invention, cold-rolled steel or hot-rolled steel with good deep drawability is used from the viewpoint of formability, but as is clear from the above, one with as little C content as possible is used. It is more advantageous to do so. Furthermore, since Mn, Si, etc. in the metal act as deoxidizing agents and have the effect of suppressing the amount of CO and CO ₂ generated during droplet transfer, it is advantageous to include them to some extent.
However, if these contents are too high, workability will decrease, so the Mn content in the outer metal should be 2.0% or less, and the Si content should be 2.0% or less.
It is best to keep it below 1.0%. The wire drawing lubricants used when manufacturing the iron powder-based flux-cored wire of the present invention include higher fatty acid ester-based (higher fatty acid salts such as Na, K, Ca, Mg, and Ba), MooS ₂ -based, and Teflon. All conventionally known lubricants can be used, such as lubricants based on lubricants, graphite-based, etc. However, in terms of low C content,
MoS ₂ based lubricants are particularly preferred. The amount of lubricant applied is preferably 0.5 to 2 g/10 kg of wire. Further, in the present invention, the wire can have any cross-sectional shape. For example, although four types of wire cross-sectional shapes are illustrated in FIGS. 4A to 4D, the wire may have any of these shapes. However, it is more preferable to use a wire with a seamless outer shell metal as shown in D. If D is used, the arc stability will be further improved and it will be more effective in reducing the amount of spatter. Further, in the case of D, there is an advantage that metal plating such as Cu or Al can be applied without any problem in order to improve wire feedability and rust resistance. The appropriate plating amount is 0.05 to 0.30%; less than 0.05% does not sufficiently improve feedability;
If it exceeds %, the melting rate will decrease and work efficiency will be lowered. Wire diameter depends on the application
It can be arbitrarily determined from 1.2mφ, 1.6mmφ, 2.0mmφ, 2.4mmφ, 3.2mmφ, etc. By the way, the steel types to which the iron powder-based flux-cored wire of the present invention is used are mainly mild steel and high-strength steel, but are not particularly limited to these. Of course, it is also possible to apply. Furthermore, although carbon dioxide gas is most commonly used as the shielding gas, it is of course possible to use Ar, He, or a mixture thereof. [Example] Wires having the compositions shown in Table 1 were produced by a conventional method. Wire diameter is 1.2mmφ, cross-sectional shape is No.1~14,
Nos. 16 to 20 are A in FIG. 4, and No. 15 is D in FIG. 4 (Cu plating amount 0.20%). It is also the No. 1 lubricant.
~14, No.16~20 are MoS ₂ type (C content ≦0.01%), No.15
Mineral oil type was used. The mild steel used as the outer shell metal of the wire contains C: 0.01%,
Mn: 0.35%, Si: 0.01%, P: 0.015%, S:
It was 0.01%. Bead-on-plate welding was performed on each of the wires prepared above under the following conditions, and the amount of spatter generated at that time was investigated, and the results shown in Table 1 (amount of spatter generated) were obtained. [Welding conditions] Welding current: 280A Arc voltage: 34V Welding speed: 30cm/min Shielding gas: CO ₂ , 20/min Distance between chip and base metal: 20mm Base material: SM41B (12mmt) In addition, to measure the amount of spatter The device shown in FIG. 5 (3 is a spatter collection plate, 4 is a wire feeding device, 5 is
6 indicates a torch, 6 indicates a base material, and 7 indicates a trolley). That is, the amount of spatter generated was determined by collecting spatter scattered around the arc point using a collecting plate shown in FIG. 5 and measuring the weight. The measurement time was 1 minute, and the value per unit time (g/min) was calculated (n=3). In addition, the amount of slag generated can be determined by collecting the slag generated during one minute of welding and measuring its weight.
min) was determined (n=3).

〔Effect of the invention〕

The present invention is constructed as described above, and by modifying the composition of the flux, it is possible to secure a high amount of welded metal in an iron powder-based flux-cored wire comparable to that of a solid wire, and to reduce the amount of spatter generated. .

[Brief explanation of the drawing]

Figure 1 shows the relationship between the amount of carbon in the total wire and the amount of spatter, Figure 2 shows the relationship between the type of slag forming agent and the amount of spatter, Figure 3 shows the effect of flux rate on the amount of spatter, and Figure 4 shows the relationship between the amount of spatter and the amount of spatter in the wire. Fig. 5 shows the cross-sectional shape of Fig. 5, and Fig. 5 shows an apparatus for measuring the amount of spatter. DESCRIPTION OF SYMBOLS 1...Flux, 2...Sheath metal, 3...Spatter collection plate, 4...Wire feeding device, 5...Torch, 6...
Base material, 7... trolley.

Claims (1)

[Claims] 1. Contains iron powder: 40 to 88% (weight%, same hereinafter), deoxidizer: 10 to 45%, and arc stabilizer: 0.5 to 5%, and also contains Al ₂ O ₃
A flux containing 1 to 15% of a slag forming agent containing 30% or more of An iron powder-based flux-cored wire characterized by limiting the amount of carbon inside to 0.05% or less. 2. The iron powder-based flux-cored wire according to claim 1, wherein the sheath metal is seamless.