JPH07164185A - Wire for gas shielded arc welding - Google Patents

Abstract

PURPOSE:To provide a wire for gas shielded arc welding capable of decreasing the short-time short circuit between a wire and a molten pool and arc cut off. CONSTITUTION:The wire for gas shielded arc welding is ultrasonically cleaned in an org. solvent, such as petroleum ether, and the solvent after removal of the wire body is filtered by using filter paper (membrane filter) having 0.2mum pore size. The residues on the filter paper are regarded as impurities and the impurities sticking to the wire surface are decreased in such a manner that the mass thereof attains <=5mug per square cm of the apparent surface area of the wire. Further, the mass of the impurities failing to pass the filter paper of 10mum pore size is preferably decreased to >=40% of the extracted impurity mass and further, the copper component quantity of the extracted impurities is preferably specified to >=30%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved wire for gas shielded arc welding.

[0002]

2. Description of the Related Art Gas shielded arc welding, which is carried out in manufacturing industrial machinery, automobiles, steel frames, etc., is required to improve performance year after year, and high speed, high quality, and high efficiency are required. Improvements have been made. As one of the improvement methods, the examination of the shield gas component and the inverter control of the welding power source are being carried out.

However, in order to efficiently obtain a high quality welded portion at low cost, it is most important to prevent defects due to instability of the welding arc and maintain a stable welding arc for a long time. The instability of the welding arc referred to here is, of course, not only fluctuations in the arc length that can be seen with the naked eye, but also short breaks in the arc that cannot be recognized with the naked eye, and short-circuiting between the wire and the molten pool for a short time (hereinafter, short-circuiting). Note) etc. are included.

When the welding arc becomes unstable, the shape of the molten pool fluctuates irregularly, and defects such as bead shapes such as undercuts and overlaps are likely to occur. In addition, in the multi-layer welding, a slag inclusion defect is likely to occur.
In addition, the unstable arc causes fatigue of the operator and causes a decrease in welding efficiency.

Various proposals have been made so far for stabilizing the arc. For example, in Japanese Examined Patent Publication No. 3-77035, a potassium carboxylic acid salt is fixed to the wire surface after removing the residual lubricant, and the amount of the fixed amount and the amount of free iron powder or free copper powder generated in the fixing process are regulated. Describes that the arc discharge phenomenon is stabilized.
Further, in Japanese Patent Laid-Open No. 61-3696, the amount of copper powder remaining on the surface of a wire having a copper plating is regulated to prevent abrasion of a conductive copper chip and blockage of a flexible conduit tube for wire feeding. It is stated.

However, in these conventional techniques,
We have not been able to sufficiently reduce the occurrence of short-term arc breaks and short circuits that cannot be recognized with the naked eye.
This caused welding defects and unnecessary fatigue of workers.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art and to sufficiently reduce short-circuits and arc breaks between the wire and the molten pool, which lead to welding defects and operator fatigue. It is to provide a wire for gas shielded arc welding.

[0008]

Means for Solving the Problems As a means for solving the above problems, according to the present invention, the impurities in a gas shielded arc welding wire are ultrasonically cleaned in an organic solvent such as petroleum ether, After removing the main body, it is filtered using a filter paper (membrane filter) with a pore size of 0.2 μm,
The apparent surface area of the wire (wire apparent surface area) =
When (average value of wire diameter) × (circularity) × (wire length), the wire for gas shield arc welding is characterized in that the apparent surface area of the wire is 5 μg or less per 1 cm 2. .

Further, in another invention, the pore size is further 10 μm.
It is characterized in that the mass of impurities that do not pass through the filter paper (membrane filter) is set to 40% or less of the mass of the extracted impurities.

Further, in another aspect of the present invention, the amount of the copper component of the extracted impurities (in the case of a copper compound, the amount converted to copper)
Is set to 30% or more.

[0011]

The present invention will be described in more detail below.

From the results of observing the welding arc phenomenon using a high-speed video or a data recorder and the results of analysis of the wire and the wire surface, the present inventors have confirmed that the substances adhering to the wire surface are different from the current-carrying tip and the wire. It was found to interfere with electrical contact and destabilize the arc. The substances referred to here are dust and residual wire drawing lubricants, those that have been altered, copper powder or iron powder, and alkali or alkaline earth compounds attached as an arc stabilizer.

That is, it was found that all substances adhering to the surface of the wire adversely affect the electrical contact between the current-carrying tip and the wire. However, depending on the substance, there was a large influence, and a substance having a large size had a greater adverse effect than the difference in the components, and it was recognized that the metallic impurities tended to have a smaller adverse effect than the non-metallic impurities.

There are various possible methods for analyzing the substance adhering to the wire surface. As a result of various tests conducted by the present inventors, a method of ultrasonically cleaning the wire in an organic solvent such as petroleum ether is found. It was the most effective. In this method, the wire is ultrasonically cleaned in an organic solvent such as petroleum ether, and after removing the wire body, it is filtered using a filter paper (membrane filter) with a pore size of 0.2 μm, and the residue on the filter paper is treated as impurities.
(Hereinafter referred to as impurities). According to this method, a wire of several kg or more can be easily analyzed, so that a trace amount of impurities can be accurately captured.
Although it is the degree of ultrasonic cleaning at this time, it is too strong that a sound wire surface is damaged and copper powder or iron powder is generated. With respect to the cleaning time, the cleaning time is increased, and the end point is when the amount of impurities is stable.

From the viewpoint of electrical contact between the current-carrying tip and the wire, the amount of impurities per apparent surface area of the wire is defined. Here, the apparent surface area of wire is (apparent surface area of wire) = (average value of wire diameter) x (circularity)
It is represented by x (wire length).

Next, the reasons for limiting the numerical values in the present invention will be described in detail.

The welding wire of the present invention is characterized in that the amount of impurities is 5 μg or less per 1 cm 2 of the apparent surface area of the wire. If the impurities exceed 5 μg / cm ² , the arc becomes unstable, and arc breaks and short circuits remarkably increase, so that welding defects such as undercuts and overlaps are likely to occur, and the operator is likely to feel fatigue. If the amount of impurities is further reduced to 2 μg or less, the number of welding defects sharply decreases, and better results are obtained.

The size of the impurities is 10
It is more preferable that the mass of impurities that do not pass through the filter paper (membrane filter) of μm is 40% or less of the mass of impurities extracted. If it exceeds 40%, arc instability for a relatively long time increases rapidly, and large welding defects are likely to occur.
Further, it is preferably 20% or less, and large welding defects are sharply reduced, so that the quality is improved.

Further, it is even more preferable that the amount of copper component of impurities (in the case of a copper compound, the amount converted to copper) is 30% or more. If the amount of impurities is the same, the arc instability phenomenon tends to decrease as the amount of copper component increases.
It is remarkable when it is 0% or more, and sharply decreases when it is 50% or more.

The composition of the solid wire for welding may be any as long as it is within the range specified in JIS Z3312, and the effects of the present invention can be sufficiently exhibited. For example, C: 0.001 to 0.15%,
Si: 0.30 to 1.10%, Mn: 0.85 to 2.60%,
P: 0.001 to 0.030%, S: 0.001 to 0.03
A composition containing 0% and Cu: 0.01 to 0.50% with the balance being iron and inevitable impurities is desirable. The reasons for controlling each component are as follows.

C: 0.001 to 0.15% C is an essential component for obtaining deoxidation and strength of the weld metal, but if it is less than 0.001%, both deoxidation and strength are insufficient. Further, if it exceeds 0.15%, high temperature cracking is likely to occur in the weld metal, so 0.001 to 0.15% is desirable.

Si: 0.30 to 1.10% Si is an indispensable component for deoxidizing the weld metal.
If it is less than 30%, deoxidation is insufficient, and if it exceeds 1.10%, the toughness of the weld metal is likely to decrease, so that it is 0.30 to.
1.10% is desirable.

Mn: 0.85 to 2.60% Mn is an essential component for obtaining deoxidation and strength of the weld metal, but if it is less than 0.85%, both deoxidation and strength are insufficient. Further, if it exceeds 2.60%, low temperature cracking tends to occur in the weld metal, so 0.85 to 2.60% is desirable.

P: 0.001 to 0.030% P is an essential component for obtaining a smooth detachment of the droplet from the tip of the wire, but if it is less than 0.001%, its effect is insufficient. Further, if it exceeds 0.030%, high temperature cracking easily occurs in the weld metal, and therefore 0.001 to 0.001.
030% is desirable.

S: 0.001 to 0.030% S is an essential component for obtaining a smooth detachment of the droplet from the tip of the wire, but if it is less than 0.001%, its effect is insufficient. Further, if it exceeds 0.030%, high temperature cracking easily occurs in the weld metal, and therefore 0.001 to 0.001.
030% is desirable.

Cu: 0.01 to 0.50% or less Cu is an essential component for obtaining the electrical conductivity of the wire and the strength of the weld metal, but if it is less than 0.01%, the electrical conductivity and strength are insufficient. If it exceeds 0.50%, high temperature cracking is likely to occur in the weld metal, and therefore 0.01 to 0.5.
0% is desirable. Cu is also a form of plating on the wire surface,
It may be either a solid solution form or a wire grain boundary precipitate form, but in order to improve the electric conductivity of the wire, the form of plating on the wire surface is 0.10 to 0.40.
% Is desirable.

Remainder: Iron and inevitable impurities Examples of inevitable impurities include Be, B, N, Mg,
Ca, V, Co, Zn, As, Se, Sr, Y, Nb, Cd, I
The content of n, Sn, Sb, Te, Ba, W, Hg, Tl, Pb, Bi, etc. may be 0.05% or less, respectively, and 0.50% or less in total. It is desirable that the amount of impurities is small, but removing impurities unnecessarily leads to a rapid increase in manufacturing costs. If any one of the above elements exceeds 0.05%, adverse effects such as an increase in arc instability and an increase in crack susceptibility are adversely affected, so 0.05% or less is preferable for each. Further, even if the total amount of these elements exceeds 0.50%, the same adverse effect is exerted, so the total amount is preferably 0.50% or less.

In addition to the above components, if necessary, one or more of the following components may be contained in appropriate amounts.

Ni: 0.01 to 1.80% Ni is an effective component for obtaining the low temperature toughness and strength of the weld metal, but if it is less than 0.01%, both the low temperature toughness and the strength are insufficient, and If it exceeds 1.80%, hot cracking of the weld metal is likely to occur, so 0.01 to 1.80% is desirable.

Cr: 0.01 to 0.70% Cr is an effective component for obtaining the strength of the weld metal,
If it is less than 0.01%, it is insufficient, and if it exceeds 0.70%, the weld metal tends to have insufficient elongation and cold cracking tends to occur, so 0.01 to 0.70% is desirable.

Mo: 0.01 to 0.65% Mo is an effective component for obtaining the low temperature toughness and strength of the weld metal, but if it is less than 0.01%, both the low temperature toughness and the strength are insufficient. If it exceeds 0.65%, high-temperature cracking is likely to occur in the weld metal and the elongation of the weld metal tends to be insufficient, so 0.01 to 0.65% is desirable.

Al: 0.01 to 0.50% Al is an effective component for deoxidizing the weld metal and shaping the weld bead, but if less than 0.01%, both deoxidation and bead shaping properties are insufficient. If it exceeds 0.50%, high temperature cracking is likely to occur in the weld metal, and therefore 0.01 to 0.5.
0% is desirable.

Ti + Zr: 0.01 to 0.30% Ti and Zr are effective components for deoxidizing the weld metal and reducing spatter. However, if less than 0.01%, both deoxidation and spatter are insufficient. Yes, and if it exceeds 0.30%, high temperature cracking is likely to occur in the weld metal, so 0.01 to 0.3
0% is desirable. Further, Ti is more effective than Zr in reducing spatter, and a range of Ti> Zr is more desirable.

Next, examples of the present invention will be described.

【Example】

Rolling or wire drawing → Heat treatment (if necessary) → Washing → Copper plating → Washing → Finishing wiredrawing → Washing → Adding oil for feeding or rust prevention → Rewinding spool or manufacturing large capacity pack Regarding the welding wire with a diameter of 1.2 mm created by appropriately changing the process conditions, impurities and arc breakage,
When the short circuit, the welding defect and the fatigue degree of the operator were examined, the results shown in Table 1 were obtained.

Among these processes, the contribution of the finish wire drawing process is relatively large, and it is difficult to sufficiently remove impurities in the subsequent cleaning process unless proper management of the lubricant and wire drawing die is performed. It was Further, unless damage to the wire surface is minimized in each cleaning step, the wire surface is likely to peel off due to contact with the flexible conduit tube when the wire is used, which impedes feeding. It was also noted that the cleaning method must be properly selected according to the type and amount of impurities to be removed.

The amount of impurities is the amount extracted by the above method. In the table, "total amount of impurities" represents the mass of impurities trapped in a filter paper having a pore size of 0.2 µm per apparent surface area of the wire. "Proportion of 10 μm or more" is 10
This is the ratio of the amount of impurities captured by μm filter paper to the total amount of impurities. “Ratio of copper in impurities” is the ratio of copper in impurities (copper compound converted to copper) in the total amount of impurities.

Regarding the arc stability, DCE
P, 220A-30V-60cm / min, shield gas C
Under the welding condition of O ₂ , the arc voltage is shorted to 20V or less, 4
The arc was cut off at 0 V or more, and the number of times of occurrence of these per second was examined. Regarding welding defects, each wire was welded at a welding length of about 20 m, and the number of undercuts and the number of Augi laps per 1 m were examined.

The chemical composition of the solid wire used was C: 0.04%, Si: 0.75%, Mn: 1.70.
%, P: 0.015%, S: 0.010%, Cu: 0.25
%, Ni: 0.02%, Cr: 0.04%, Mo <0.005
%, Al: 0.008%, and the balance of 96.5% or more Fe and unavoidable impurities.

In Table 1, as shown in Examples Nos. 1 to 25 of the present invention, the amount of impurities is 5 μ per 1 cm 2 of the wire surface area.
It can be seen that the arc instability that leads to welding defects can be sufficiently reduced by setting the g or less. It is better that the amount of impurities is small, and if it is less than 2 μg, the arc can be further stabilized.

Further, as shown in Examples Nos. 11 to 25 of the present invention, it is understood that the arc instability can be further reduced by reducing the large-sized impurities of 10 μm or more to 40% or less.

Further, the copper in the impurities was mainly present in the form of copper powder, and it was recognized that the adverse effect thereof was smaller than that of the non-metallic impurities. It is presumed that this is because the density of the copper powder is high, so the volume is relatively small, and the electrical conductivity of copper is high. As shown in Inventive Examples Nos. 20 to 25, this tendency was remarkable when the amount of the copper component of the extracted impurities (the copper compound was converted to copper) was 30% or more.

The same result was obtained not only for the wire having a diameter of 1.2 mm shown in this embodiment but also for wires having other diameters and chemical components. Similar results were obtained with a copper-plated flux-cored wire.

[0044]

[Table 1]

[0045]

As described in detail above, according to the present invention,
Since we can provide a wire for gas shielded arc welding in which the amount of impurities on the wire surface is controlled within the limit, the welding arc has excellent stability, welding defects due to arc instability do not easily occur even at high speed welding, and worker fatigue is reduced. The effect of contributing to the industry such as reduction and improvement of quality and efficiency is extremely remarkable.

Claims (5)

[Claims] 1. A wire for gas shielded arc welding is cleaned with ultrasonic waves in an organic solvent such as petroleum ether to remove the wire body, and then a filter paper (membrane filter) having a pore diameter of 0.2 μm is used. The mass of impurities extracted by the method of filtering the residue on the filter paper as impurities is calculated by calculating the apparent surface area of the wire as (apparent surface area of wire) = (average value of wire diameter) x (circular ratio) x (length of wire). Sa)), the wire for gas shielded arc welding is characterized in that the apparent surface area of the wire is 5 μg or less per square cm. 2. The gas shielded arc welding according to claim 1, wherein the mass of impurities that do not pass through a filter paper (membrane filter) having a pore size of 10 μm is set to 40% or less of the mass of the extracted impurities. For wire. 3. The amount of copper component of the extracted impurities
(The amount converted to copper in the case of a copper compound) is 30% or more, The wire for gas shield arc welding according to claim 1 or 2, characterized in that 4. The composition of the solid wire in% by weight (hereinafter the same), C: 0.001 to 0.15%, Si: 0.30 to.
1.10%, Mn: 0.85 to 2.60%, P: 0.001
~ 0.030%, S: 0.001-0.030%, Cu:
The gas shielded arc welding wire according to claim 1, 2 or 3, comprising 0.01 to 0.50% and the balance being iron and inevitable impurities. 5. Ni: 0.01 to 1.80%, Cr:
0.01 to 0.70%, Mo: 0.01 to 0.65%, Al:
The gas shielded arc welding wire according to claim 4, which contains one or more of 0.01 to 0.50% and Ti + Zr: 0.01 to 0.30% or less.