JPS63252694A - Flux-cored wire for self-shield arc welding - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an ultra-small diameter flux-cored wire for self-shielded arc welding that can perform stable welding with low current.

(Prior art) What is a flux-cored wire for self-shielded arc welding? It usually contains metal fluoride as a shielding agent from the outside air, metal fluoride as a slag agent, metal carbonate or oxide, denitrification agent, and deoxidizing agent inside the steel sheath. At, My, and even Si as required for mechanical performance.
It is filled with alloying agents such as , Mn, Ni, etc., and it is easy to handle because there is no need to supply shielding gas or spray flux from the outside, and it also has excellent wind resistance. It is thought that the fields of its use will continue to expand in the future.

Current fields of application of flux-cored wires for self-shielded arc welding include welding of steel pipe piles using large diameter wires with a wire diameter of 2.4 to 3.2 mm.

It is limited to welding of architectural steel frames or marine structures using wires with a wire diameter of 1.6 to 2.4 mm.

Flux-cored wires for self-shielded arc welding, which are applied to these fields, have been variously improved, but
The diameter of the wire is approximately 1.6 mm or more.

For example, JP-A-61-169196, JP-A-61
The flux-cored wire for self-shielded arc welding disclosed in Publication No. 180697 has a wire diameter of 2.01.
φ is exemplified, and JP-A-61-176496 only exemplifies a wire diameter of 1.8 φ.

By the way, many things are now manufactured by welding, such as ships,
All kinds of things are manufactured by welding, from large structures such as moon structures, tanks, and high-rise pills, to small objects such as cars, bicycles, and even toys. The most suitable welding method is used depending on the product to be manufactured, and whether the product being manufactured here is small or not.

If the thickness of the plate to be welded is thin, it is necessary to use ultra-thin diameter wire and use a low current to prevent welding from dripping. Currently, solid wires with a wire diameter of about 0.8 wφ are available as such ultra-thin diameter wires, but solid wires require supply of shielding gas from the outside, which is inconvenient.

(Problems to be solved by the invention) The present invention has been made by focusing on the above-mentioned circumstances, and includes:
The purpose of the present invention is to provide a flux-cored wire for self-shielded arc welding with an ultra-small diameter that allows stable welding with low current and takes full advantage of its simplicity.

(Means for Solving the Problems) The gist of the present invention is to provide a flux-cored wire for self-shielded arc welding in which a steel sheath is filled with flux, and the wire diameter is 0.6 to 1. OWφ, 'carbon equivalent of steel sheath (Ceq = C+T+π+π+Cr M.

-+-) is 0.030 to 0.110, flux filling rate (ratio of flux weight to total wire weight) is 5 to 20%, Vickers hardness of wire sheath H
The present invention provides a flux-cored wire for self-shielded arc welding, characterized in that the flux (indicated by v) is 120 to 230.

(Function) When the object to be welded is a thin plate, for example, a steel plate with a diameter of 11 or less, it is possible to weld the weld without dripping or to suppress the amount of weld deposit, for example, welding with a bead width of 5 or less. This is a flux-cored wire for self-shielded arc welding, and in order to do so, the wire diameter must be made small and welding must be carried out at a low current. When we investigated the relationship, we found it as shown in Figure 1. Figure 1 was obtained through the following experiment.

That is, self-shielded arc welding in which mild steel steel (C=O, 018%, Mn=0.24T, AA=O, oz%, other unavoidable components are included, and the balance is Fe) is filled with 15% flux. Wire diameter: 0°5, 0.6
, 0.8, 1.0, 1.2, 1.4+n
Wires of φ were manufactured, each wire was welded downward, and the lowest current that would yield a stable and good bead was investigated.

As a result, in order to be able to weld steel plates with a thickness of 1 mm or less as described above, and to have a bead width of 5 m or less, the welding current must be 5 m.
It was found that the wire diameter should be 0 A or less and the wire diameter should be 1.0 haze φ or less. In addition, the wire of 0.5 rmφ was loose at the tip of the current-carrying tip in the solution, and the arc was unstable. Therefore, the wire diameter of the present invention is 0.6 to 1. oIIIs
Let it be φ.

The chemical composition of the steel sheath affects the drawability of the wire, and as in the wire of the present invention, 1. When it comes to ultra-thin diameter wires of less than omφ,
The impact is particularly large. Steel sheaths typically contain C, Si, Mn
, A! Contains P, S, and N as other impurity elements.
, O etc. are also included, but Ceq (= C0Mn
SiNiCrM.

-+ -+ -+ -+ -) exceeding 0.110 cm, the wire sheath becomes too hard during wire drawing and wire breakage is likely to occur; conversely, when Ceq is less than 0.030%, the wire strength decreases. If it is insufficient, it is easy to break the wire. Therefore, the Ce of the steel sheath
q is 0.30 to 0.110%.

Next, regarding the flux filling rate, in self-shielded arc welding, by adding M to the filling flux, 1 u of nitrogen that has entered from the atmosphere fixes it and makes it harmless, thus preventing defects such as bits and blowholes. are doing. Therefore, if the flux filling rate is less than 5 inches, the amount of M for nitrogen fixation and the slag agent necessary for bead formation will be insufficient, resulting in defects such as pits and plowholes, and the bead shape will change. It may get worse. On the other hand, if the wire exceeds 20 inches, the wire will easily break during wire drawing, and the outer diameter will be 1.0.
It becomes difficult to manufacture wires with a diameter smaller than flφ. Therefore, the flux filling rate is set to 5 to 20 inches.

Next, we will discuss the hardness of the wire sheath. In automatic or semi-automatic welding using franked wire, the wire is fed to the tip of the welding torch via a conduit cable that guides the wire with a feed roller of a wire feeder. meanwhile,
There is a feeding resistance applied to the wire, and the magnitude of the resistance varies depending on the length of the conduit cable (1.5 to 3 m or more in some cases), the degree of bending of the conduit cable, and the shape of the welding torch. If the resistance is large, the pressure on the feed roller must be increased to feed with strong force. However, unlike solid wire, flux-cored wire, which has 7 lux in the center of the wire cross section, is easily deformed by force when tightened by rollers, and the deformed wire cannot pass through the hole in the power supply tip at the tip of the welding torch. Therefore, the flux-cored wire needs to have deformation resistance that can withstand the pressure of the rollers so that the wire can be fed stably. The deformation resistance depends on the hardness of the wire outer skin, and the wire diameter of the present invention is 0.6 to 1.0 mmφ.
In flux-cored wire for self-shielded arc welding, if the Vickers toughness of the wire sheath is less than 120, the wire will be deformed by the pressure of the feed roller, making feeding unstable and causing arc disturbance. Wire feeding may stop and welding may be interrupted. On the other hand, the hardness of the wire sheath is 2.
If the wire diameter exceeds 30, the wire is likely to break during wire drawing, and if the wire diameter is 0.6 to 1. It is difficult to manufacture a wire with an extremely small diameter of olEllφ. Therefore, the Vickers hardness of the wire sheath is set to 120-230. Note that the stiffness of the wire sheath varies depending on its carbon equivalent and wire drawing variation, but in the case of the present invention, it is possible to obtain a wire with a predetermined hardness by selecting the wall thickness of the steel sheath during flux filling. Can be done.

The effects of the constituent elements of the uninvented wire and the reasons for numerical limitations are as described above, but the type of filling flux is not particularly limited, and is currently being used as the filling flux for flux-cored wires for self-shielded arc welding. You can use whatever you have.

In addition, the cross-sectional shape of the wire of the present invention is as shown in Figs. 2, 3, and 4, in addition to the open seam wire having a seam on the circumference of the steel sheath, as shown in Fig. 5. Any closed seam wire without eyes may be used.

(Example) Ten types of wires shown in Table 1 were manufactured. That is, the second
Using mild steel sheaths with different carbon equivalents as shown in the table,
Wire diameter 0.6 to 1.2 with varying flux filling rate
．． A wire of φ was manufactured, and a welding workability test was conducted using a steel plate with a thickness of 21 in a downward position. The results are shown in Table 1.

As shown in Table 1, the present invention wires N11l to 5 are:
Both wire drawability and wire feedability were good, and in terms of welding workability, all wires could be welded at a constant t of 50 A or less, and their porosity resistance was also good.

Next, we will discuss the comparison wire.

No. 6 was a case in which a steel sheath with too high carbon equivalent was used, and the wire became hard during wire drawing, resulting in significant wire breakage and poor wire drawability. Therefore, we did not conduct a bath exposure experiment.

No. 7 is a case where the filling rate is low, and the wire drawability and wire feedability are both good, but the bead shape is poor due to lack of slag agent and M, and bits are generated.

M8 had a high filling rate, which resulted in frequent wire breakage and poor wire drawability. Therefore, no welding experiments were conducted.

(No. 9 is made of steel) When the carbon equivalent of the wire is too low, the tensile strength of the wire is insufficient and wire drawing is easily interrupted, and the resulting wire has a low Vickers hardness, so the feeding roller The wire was deformed and welding was not possible.

11n 10 is when the wire diameter is 1.2 φ, and has good wire drawability, wire feedability, bead shape, and porosity resistance, but because the wire diameter is large, the lower limit of the appropriate current is high at 60A. As a result, the bead width also increases, so it was excluded from the wires of the present invention.

(Effects of the Invention) As explained above, according to the flux-cored wire for self-shielded arc welding of the present invention, stable welding is possible with low current, and it is easy to weld ultra-thin plates or small objects both indoors and outdoors. It is something that can be done.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the wire diameter and the minimum value of the appropriate welding current for that wire, Figures 2, 3, and 4 are cross-sectional views of open seam wire, and Figure 5 is a diagram of the closed seam wire. FIG. 1... Steel sheath 2... Filling flux

Claims (1)

[Claims] In flux-cored wire for self-shielded arc welding, which is made by filling a steel sheath with flux, the wire diameter is 0.
．． 6 to 1.0 mmφ, carbon equivalent of steel sheath (Ceq=C+
Mn/6+Si/24+Ni/40+Cr/5+Mo/
4) is 0.030 to 0.110%, flux filling rate (ratio of flux weight to total wire weight) is 5 to 20%, and Vickers hardness of steel sheath (indicated by Hv).
1. A flux-cored wire for self-shielded arc welding, characterized in that: 120 to 230.