JP2017225982A - ARC WELDING METHOD OF MOLTEN Zn TYPE PLATED STEEL PLATE, MANUFACTURING METHOD OF WELDED MEMBER AND WELDED MEMBER - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc welding method of a molten Zn type plated steel plate, a manufacturing method of a welded member and the welded member excellent in welded part appearance and welded strength.SOLUTION: An arc welding method includes a process of welding molten Zn type plated steel plates with each other according to a pulse arc welding method which generates an arc by supplying a peak current and a base current alternately. Therein, a distance from a tip of a welding wire 2 to a welding object part on a part abutted to each other of molten Zn type plated steel plates 1, 1' as welding object is such a length that the welding wire 2 and a molten pool 3 produced on the abutted part are not short-circuited with each other and the welding is performed in such a length that the arc does not put out.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an arc welding method for a hot-dip Zn-based plated steel sheet, a method for manufacturing a welded member, and a welded member.

  Hot dip galvanized steel sheets (hot galvanized steel sheets) have good corrosion resistance and are used in a wide range of applications including building members and automobile members. Among them, a hot-dip Zn—Al—Mg plated steel sheet containing 1% by mass or more of Al maintains excellent corrosion resistance over a long period of time, and therefore, the demand is increasing as a material to replace the conventional hot-dip Zn plated steel sheet. In addition, the Al concentration in the plating layer in the conventional hot-dip Zn-plated steel sheet is usually 0.3% by mass or less (see JIS G3302).

  When a hot-dip Zn-based plated steel sheet is used for a building member, an automobile member, etc., it is often assembled using an arc welding method. However, when arc welding is performed on a hot-dip Zn-based plated steel sheet, usually spatter, pits, and blow holes (hereinafter, blow holes include pits unless otherwise specified) are remarkably inferior in arc weldability. This is because the boiling point of Zn (about 906 ° C.) is lower than the melting point of Fe (about 1538 ° C.), so that Zn vapor is generated during arc welding, the arc becomes unstable, and spatter and blow holes are likely to occur. Because. In addition, it is as follows if a sputter | spatter, a blowhole, and a pit are demonstrated using (a)-(c) of FIG. That is, as shown in FIG. 7A, the sputter 111 is, for example, welding slag such as slag or metal particles scattered from the welding wire 102, the molten pool 103 or the like when welding the steel plates 101 and 101 ′. is there. As shown in FIG. 7B, the blow hole 112 is a pore included in the weld bead 106. The weld bead 106 is a portion in which a metal melted at the time of welding (a portion where a part of the base material and the weld metal are melted) is cooled and solidified, and is a weld metal that joins the materials to be welded metallurgically. That's it. Further, as shown in FIG. 7C, the pit 113 means a recess formed by pores appearing on the surface of the weld bead 106.

  When spatter adheres to the plated surface of the hot-dip Zn-based plated steel sheet, not only the appearance of the welded portion is impaired, but also the portion where the spatter adheres becomes the starting point of corrosion. Therefore, if a large amount of spatter adheres, the corrosion resistance is remarkably lowered, which causes a problem. Further, a process of removing the spatter with a wire brush or the like is required, which increases the cost. On the other hand, if blowholes are significantly generated, the welding strength may be reduced, which may be a problem.

In particular, for members that require long-term durability, a hot-dip Zn-plated steel sheet having a thickness of 90 g / m ² or more per side is used, but arc welding increases as the amount of plating per side increases. Since the amount of Zn vapor at the time increases, the generation of spatter and blow holes becomes even more remarkable.

  In addition, in this specification, as for the amount of plating adhesion per one surface of a hot-dip Zn-based plated steel sheet, a material with a small amount of plating may be referred to as thin, and a material with a large amount of plating may be referred to as thick.

  A pulse arc welding method using a welding wire as an electrode has been proposed as a method for suppressing the occurrence of spatter and blowholes during welding of a hot-dip Zn-based plated steel sheet. According to this pulse arc welding method, the droplet transfer from the welding wire used as the electrode to the base material becomes spray transfer, and the droplet is small and spatter is suppressed. In addition, the molten pool (the weld bead portion before solidification) is agitated by the pulse arc, and the molten pool is pushed down to make the molten pool thinner, and the discharge of Zn vapor is promoted to suppress the generation of blowholes. .

  For example, Patent Documents 1 and 2 disclose a pulse arc welding method that suppresses sputtering by controlling the welding wire composition and pulse current waveforms such as peak current, peak period, and frequency within an appropriate range.

Japanese Patent Laid-Open No. 9-206984 (published on August 12, 1997) JP 2013-184216 A (published September 19, 2013)

However, Patent Documents 1 and ² only disclose an example of a thin-walled hot-dip Zn-plated steel sheet having a coating adhesion amount per side of 45 g / m ^2. There is no description on the method of suppressing spatter and blowholes in

  As described above, the hot-dip Zn-based plated steel sheet is more excellent in corrosion resistance as the coating amount increases, but spatter and blow holes are remarkably generated during arc welding, and the weld appearance and weld strength are reduced. In view of the present situation, the present invention can suppress the occurrence of spatter and blowholes in arc welding even when the hot-dip Zn-based plated steel sheet is thick, and has a welded portion appearance and weld strength that is excellent. An object of the present invention is to provide an arc welding method for a plated steel sheet, a manufacturing method for a welding member, and a welding member.

  As a result of detailed research by the inventors, in arc welding of hot-dip Zn-based plated steel plates, when performing arc welding using a pulsed arc welding method, from the tip of the welding wire, the hot-dip Zn-based plated steel plates to be welded together By optimizing the distance to the weld target part at the contact part, it is possible to suppress the occurrence of spatters and blowholes from thin to thick ones on the hot-dip Zn-plated steel sheet. I got the knowledge. The present invention has been completed based on this finding.

  That is, the arc welding method for hot-dip Zn-based plated steel sheets according to the present invention is an arc welding method for welding hot-dip Zn-based plated steel sheets to each other by a pulsed arc welding method in which an arc is generated by alternately supplying a peak current and a base current. The distance from the tip of the welding wire to the welding target portion at the contact portion between the hot-dip Zn-based plated steel sheets to be welded is short-circuited between the welding wire and the molten pool generated at the contact portion. It is the length which does not carry out and it welds in the length which does not turn off an arc.

  Moreover, it is preferable that the said distance is 2 mm or more and 20 mm or less as for the arc welding method of the hot-dip Zn type plated steel plate in this invention.

  Furthermore, in the arc welding method for a hot-dip Zn-based plated steel sheet according to the present invention, the peak current is preferably 350 A or more and 650 A or less, and the pulse period is preferably 1 ms or more and 20 ms or less.

  Further, in the arc welding method for a hot-dip Zn-based plated steel sheet according to the present invention, the plating layer of the hot-dip Zn-plated steel sheet contains Zn as a main component and contains 1.0% by mass or more and 22.0% by mass or less of Al. can do.

  Furthermore, in the arc welding method for a hot-dip Zn-based plated steel sheet according to the present invention, the plating layer of the hot-dip Zn-plated steel sheet preferably contains 0.05% by mass or more and 10.0% by mass or less of Mg.

  Furthermore, in the arc welding method of the hot-dip Zn-plated steel sheet according to the present invention, the composition of the plating layer of the hot-dip Zn-plated steel sheet is Ti: 0.002-0.1 mass%, B: 0.001-0.05. It is preferable that one or more conditions selected from the group consisting of mass%, Si: 0 to 2.0 mass%, and Fe: 0 to 2.5 mass% are satisfied.

  Moreover, the arc welding method of the hot-dip Zn-based plated steel sheet according to the present invention has a blowhole occupancy Br represented by the following formula (1) of 30% or less, and has a length of 100 mm and a width of 100 mm centered on the weld bead. Arc welding can be performed so that the number of sputters deposited is 20 or less.

Br = (Σdi / L) × 100 (1)
(here,
di: length of the i-th blow hole observed in the weld bead L: length of the weld bead).

The method for manufacturing a welded member in the present invention is a method for manufacturing a welded member in which hot-dip Zn-based plated steel plates are welded to each other by a pulse arc welding method, and the amount of plating adhesion per side of the hot-dip Zn-based plated steel plate is 15 g / m ² or more and 250 g / m ² or less, and the distance from the tip of the welding wire to the welding target part at the contact part between the hot-dip Zn-based plated steel sheets to be welded is 2 mm or more and 20 mm or less, and generates a pulse arc. It is characterized in that the molten Zn-based plated steel sheets are welded to each other by pulse arc welding in which the peak current of the welding current to be applied is 350 A or more and 650 A or less and the cycle of the pulse is 1 ms or more and 20 ms or less.

  ADVANTAGE OF THE INVENTION According to this invention, even if the hot dip Zn system plating steel plate is thick, generation | occurrence | production of the spatter | spatter and blowhole in arc welding can be suppressed, An arc welding method, a manufacturing method of a welding member, and a welding member can be provided.

It is a figure which shows typically the pulse current waveform in the pulse arc welding method. It is sectional drawing which shows a pulse arc welding phenomenon typically. (A) is a schematic diagram showing a positional relationship between a welding wire and a contact portion between hot-dip Zn-based plated steel sheets in the case of fillet welding by a lap joint in the method for arc welding of hot-dip Zn-plated steel sheets in the embodiment of the present invention. It is sectional drawing shown typically, (b) is sectional drawing which shows typically the said positional relationship in the case of fillet welding by a T-shaped joint. It is a top view explaining the measuring method of the blowhole occupation rate in the welding member formed by welding hot-dip Zn system plated steel plates. It is a top view explaining the measuring method of the sputter | spatter adhesion number in the welding member formed by welding hot-dip Zn series plated steel plates. It is sectional drawing which shows typically the arc welding phenomenon in the conventional arc welding method without a pulse. (A) is sectional drawing which shows typically a sputter | spatter, (b) is sectional drawing which shows a blow hole typically, (c) is sectional drawing which shows a pit typically.

  Embodiments of the present invention will be described below. The following description is for better understanding of the gist of the invention and does not limit the present invention unless otherwise specified. Moreover, in this specification, "A-B" has shown that it is A or more and B or less.

  In the following description, in order to facilitate understanding of the arc welding method of the hot-dip Zn-based plated steel sheet in the embodiment of the present invention, first, the arc welding phenomenon in the conventional pulse welding arc welding method will be described with reference to FIG. Next, an outline of a general pulse arc welding method will be described with reference to FIG. 1 and FIG. The principle of pulse arc welding in the embodiment of the present invention is the same as that of a general pulse arc welding method.

  FIG. 6 is a sectional view schematically showing an arc welding phenomenon in a conventional arc welding method without a pulse. As shown in FIG. 6, in the arc welding method without a pulse, for example, when the molten Zn-based plated steel plate 201/201 ′ is welded, the droplet 205 generated from the welding wire 202 contacts (short-circuits) the molten pool. A short-circuit transition phenomenon occurs. In this case, a large amount of spatter may be generated by jetting Zn vapor in a portion where the droplets 205 and the molten pool are mixed. Moreover, since Zn vapor is difficult to escape, a large amount of blow holes are generated.

  Next, an outline of a general pulse arc welding method will be described. FIG. 1 is a diagram schematically showing a pulse current waveform in the pulse arc welding method. As shown in FIG. 1, the pulse arc welding method is an arc welding method in which a peak current IP and a base current IB are alternately and repeatedly supplied, and the peak current IP is set to be equal to or higher than a critical current at which the droplets are sprayed. Is done. The time during which the peak current IP flows is defined as a peak period PP, and the pulse period of the pulse current composed of the peak current IP and the base current IB is defined as a period PFQ. When the peak current IP is set to be equal to or higher than the critical current, an effect of drawing the droplet at the wire tip due to electromagnetic force (electromagnetic pinch effect) occurs, and this electromagnetic pinch effect causes a constriction on the droplet at the tip of the welding wire. The droplets are atomized and regular droplet transfer (spray transfer) is performed for each pulse period. Thereby, a droplet transfers to a molten pool smoothly and generation | occurrence | production of a sputter | spatter is suppressed.

  FIG. 2 is a cross-sectional view schematically showing the pulse arc welding phenomenon. Here, fillet welding using a lap joint will be described as an example. As shown in FIG. 2, in the pulse arc welding method in which the peak current value is appropriately set, small droplets 5 are sprayed from the welding wire 2 to the molten pool 3, so that a short circuit is unlikely to occur, and the pulse arc 4 As a result, the molten pool 3 immediately below the arc is pushed down, the depth of the molten pool is reduced and stirred, and the discharge of Zn vapor is promoted to suppress the occurrence of spatter and blowholes. A portion where the molten pool 3 is cooled and solidified becomes a weld bead 6.

  More specifically, in such a pulse arc welding method, as the distance between the tip of the welding wire 2 and the molten pool 3, that is, the arc length becomes shorter, the effect of pushing down the molten pool 3 by the pulse arc 4 becomes larger. Steam discharge is promoted. However, if the arc length becomes too short, the tip of the welding wire 2 and the molten pool 3 are short-circuited and sparked, and the molten pool 3 is blown away and a large amount of spatter is generated. In particular, when the molten Zn-based plated steel sheet is thick, the amount of Zn vapor generated increases, so that Zn vapor does not escape from the molten pool 3 even if the pulse arc welding method is used. The molten pool 3 undulates at a stroke, and the tip of the welding wire 2 is short-circuited to cause spattering.

  Therefore, in the present invention, the short-circuit between the tip of the welding wire 2 and the molten pool 3 is prevented, and even if the molten Zn-based plated steel sheet is thick, the influence of Zn vapor is suppressed to stabilize the droplet transfer, Suppresses spatter and blowholes.

  In addition, the meaning of the term pulse arc welding method in this specification is as follows. That is, generally, in various arc welding methods, it is possible to generate a pulse arc by applying a pulse voltage. Among such various pulse arc welding methods, the pulse arc welding method of the present invention is a pulse arc welding method. MAG (Metal Active Gas) welding method and pulsed MIG (Metal Inert Gas) welding method are targeted. In other words, the present invention performs welding while simultaneously melting the welding wire and the base metal by an arc generated between the welding wire and the base material, and at the time of welding, a pulse in which a shielding gas exists around the arc. It relates to the arc welding method.

  This embodiment will be described in detail below.

[Positional relationship between the welding wire and the contact portion between the hot-dip Zn-plated steel sheets before welding]
The positional relationship between the welding wire and the contact portion between the hot-dip Zn-plated steel sheets before welding in the arc welding method for hot-dip Zn-plated steel sheets in the present embodiment will be described with reference to FIG.

  FIG. 3 (a) shows the contact between the welding wire 2 and the molten Zn-based plated steel sheet 1 · 1 ′ in the case of fillet welding by a lap joint in the arc welding method of the molten Zn-based plated steel sheet in the present embodiment. 7 is a cross-sectional view schematically showing a positional relationship with a part 7. FIG. FIG. 3B is a cross-sectional view schematically showing the positional relationship between the welding wire 2 and the contact portion 7 between the hot-dip Zn-based plated steel plates 1 and 1 ′ in the case of fillet welding with a T-shaped joint. . 3 (a) and 3 (b) both show a cross section in a direction perpendicular to the welding direction and a state before welding.

  As shown in (a) and (b) of FIG. 3, before welding, the hot-dip Zn-based plated steel plate 1 and the hot-zinc-plated steel plate 1 ′ to be welded can be arranged in various joint shapes. In (a) of FIG. 3, it arrange | positions at a lap joint, and is arrange | positioned at the T-shaped joint in (b) of FIG. Between the arranged hot-dip Zn-based plated steel plate 1 and hot-dip Zn-plated steel plate 1 ′, a contact portion 7 is formed as a contact surface with which they contact each other. Here, the end portion closest to the tip of the welding wire 2 in the contact portion 7 is referred to as a corner portion 7a. The corner portion 7a is a portion where a weld bead 6 (see FIG. 4) is formed at a portion where the molten Zn-based plated steel plate 1 and the molten Zn-based plated steel plate 1 'are adjacent to each other.

  In other words, the corner portion 7a is formed with the molten Zn-based plated steel plate 1 and the molten Zn-based plated steel plate 1 ′ in a state where the molten Zn-based plated steel plate 1 and the molten Zn-based plated steel plate 1 ′ are arranged in an arbitrary joint shape. This is a portion irradiated with an arc for welding, and can also be referred to as a welding target portion. In the case where the joint shape is a butt joint, the weld target portion is on the side of the welding wire 2 on the surface where the end portion of the molten Zn-based plated steel plate 1 and the end portion of the molten Zn-based plated steel plate 1 ′ face each other. An edge (ridgeline) is meant.

  As described above, in order to suppress the occurrence of spatter due to a short circuit between the tip of the welding wire 2 and the molten pool 3, it is important to manage the arc length within an appropriate range. However, referring again to FIG. 2, the weld pool 3 moves up and down within a very short time in synchronism with the waveform of the pulse arc 4 due to the depressing effect of the pulse arc 4. It is difficult to measure and manage itself. Therefore, in the present invention, as shown in FIGS. 3A and 3B, welding is performed at a contact portion 7 between the hot-dip Zn-based plated steel sheets before welding from the wire tip portion 2 a that is the tip of the welding wire 2. The distance D to the corner 7a on the wire 2 side is such a length that the welding wire 2 and the molten pool 3 are not short-circuited with each other, and the pulse arc 4 is not extinguished.

  Here, for example, when pulse arc welding is performed on the joint shapes shown in FIGS. 3A and 3B, the welding wire 2 moves in a direction perpendicular to the paper surface, and sequentially welds the welding target portions. Will go. Therefore, the distance D indicates the length of the perpendicular drawn from the wire tip 2a as a point to the welding object (the corner 7a or the edge on the welding wire 2 side) as a line. Yes. In addition, the straight line passing through the central axis of the welding wire 2 does not necessarily pass through the corner portion 7a, and the straight line only needs to pass through the vicinity of the corner portion 7a. Therefore, in a broad sense, the distance D is defined as a point where the straight line passing through the central axis of the welding wire 2 intersects the molten Zn-based plated steel sheet 1 or the molten Zn-based plated steel sheet 1 ′ (welding target part) and the wire tip 2a. Is the distance between.

  Thus, in the arc welding method for the hot-dip Zn-based plated steel sheet of the present embodiment, the distance D from the wire tip 2a to the corner 7a is such that the welding wire 2 and the molten pool 3 do not short-circuit each other. Weld and maintain the length so that the arc does not turn off. This method does not measure the arc length itself but welds while maintaining the distance D, so that spatter and blowholes are easily generated in arc welding even if the hot-dip Zn-plated steel sheet is thick. Can be suppressed with a simple configuration.

  In the arc welding method of the hot-dip Zn-plated steel sheet of the present embodiment, the distance D from the wire tip 2a to the corner 7a is preferably in the range of 2 to 20 mm. When the distance D is less than 2 mm, the welding wire 2 and the molten pool 3 are short-circuited and spatter occurs. When spatter is generated, stirring by depressing the molten pool 3 is not performed, so that Zn vapor is not discharged and blow holes are generated. On the other hand, when the distance D exceeds 20 mm, the arc is extinguished, so-called arc breakage occurs. When the arc break occurs, when the welding wire 2 is short-circuited to the molten pool 3 and the pulse arc 4 is re-ignited, the spark is blown off and the molten pool 3 is blown off to generate spatter. Further, while the pulse arc 4 is extinguished, stirring by pushing down the molten pool 3 is not performed, so that Zn vapor is not discharged and blow holes are generated. In addition, when the distance D exceeds 20 mm, the arc spreads and the pinch effect due to the electromagnetic force is weakened, so that the droplet 5 is difficult to break. End up.

  Here, since the metal of the wire tip 2a moves to the molten pool 3 during pulse arc welding of the molten Zn-based plated steel sheet, the tip of the welding wire 2 gradually increases the voltage to the welding wire 2. It will go back to the supply side. Since the distance D can vary depending on various welding conditions, it is not uniquely determined. The range D is in the range of 2 to 20 mm by appropriately adjusting the supply speed of the welding wire 2, the peak current IP and the period PFQ described later. Adjusted in.

  Thus, by setting the distance D from the wire tip 2a to the corner 7a to be in the range of 2 to 20 mm, spatter and blowholes are effectively generated even when the hot-dip Zn-based plated steel sheet is thick. Therefore, it is possible to provide an arc welding method for a hot-dip Zn-based plated steel sheet having excellent weld appearance and weld strength.

  Next, preferable specific examples of various conditions used in the arc welding method of the hot-dip Zn-based plated steel sheet according to the present embodiment will be described.

[Peak current]
The peak current IP for generating the pulse arc is preferably in the range of 350 to 650A. For example, when the supply speed of the welding wire 2 is 15 m / min or more and the peak current IP falls below 350 A, the welding wire 2 becomes insufficiently melted, the supply of the welding wire 2 becomes excessive, and the distance D falls below 2 mm. Moreover, arc force becomes weak and the stirring effect by pushing down of the molten pool 3 becomes weak. On the contrary, when the peak current IP exceeds 650 A, the welding wire 2 is excessively melted, the distance D exceeds 20 mm, and arc breakage or coarsening of the droplet 5 occurs.

〔period〕
The pulse period PFQ in the pulse arc is preferably in the range of 1 to 20 ms. When the period PFQ is shortened, the number of times the molten pool 3 is pushed down by the pulse arc 4 increases, so that the discharge of Zn vapor is promoted. However, if the period PFQ becomes too short, when the supply speed of the welding wire 2 is slow (for example, 3 m / min or less), the welding wire 2 becomes excessively melted and the distance D exceeds 20 mm, and the arc breaks. And the droplets 5 become coarse. As a result, droplet transfer becomes unstable and spatter occurs. On the other hand, if the period PFQ becomes too long, the welding wire 2 is insufficiently melted, the distance D is less than 2 mm, and the short circuit with the molten pool 3 is caused to generate spatter. Further, since the number of times the molten pool 3 is pushed down by the pulse arc 4 is reduced, Zn vapor is not discharged, and spatter and blow holes are generated.

〔Shielding gas〕
In the pulse mag welding method, an Ar—CO ₂ mixed gas is used as a shielding gas in order to cause the droplets to be sprayed. This shielding gas is also used to shield the periphery of the arc being welded and the molten pool from the atmosphere. Also in this embodiment, Ar—CO ₂ mixed gas is used as the shielding gas. As Ar—CO ₂ mixed gas, Ar-30 vol% CO ₂ gas, Ar-20 vol% CO ₂ gas, Ar-10 vol% CO ₂ gas, or Ar-5 vol% with further reduced CO ₂ concentration CO ₂ gas may be used.

  Further, when the pulse MIG welding method is used in the present embodiment, the shielding gas is an argon gas or an argon-helium mixed gas.

(Fitting shape)
In addition to fillet welding with the lap joint shown in (a) of FIG. 3 and fillet welding with the T-shaped joint shown in (b) of FIG. 3, a corner joint, a cross joint, a metal fitting, a flare joint, etc. The present invention can be applied to any joint shape. The present invention can also be applied to butt welding using a butt joint, a corner joint, a cross joint, and a T-shaped joint.

[Hot Zn-plated steel sheet]
In the present embodiment, the hot-dip Zn-plated steel sheet to be welded has a plated layer such as a hot-dip Zn-plated steel sheet, an alloyed hot-dip Zn-plated steel sheet, a hot-dip Zn-Al-plated steel sheet, and a hot-dip Zn-Al-Mg-plated steel sheet. A hot-dip galvanized steel sheet mainly composed of Zn is preferred.

Among the hot-dip Zn-based plated steel sheets, the hot-dip Zn-Al-Mg plated steel sheets contain Al: 1.0 to 22.0 mass%, Mg: 0.05 to 10.0 mass%, and are excellent in corrosion resistance. It is. The plating layer of the hot-dip Zn—Al—Mg plated steel sheet is Ti: 0.002 to 0.1% by mass in order to suppress the formation and growth of a Zn ₁₁ Mg ₂ phase that causes the appearance and corrosion resistance of the plating layer to deteriorate. , B: You may add 0.001-0.05 mass%. In addition, Si is added up to 2.0% by mass in order to suppress excessive growth of the Fe-Al alloy layer formed at the interface between the plating plate surface and the plating layer and improve the adhesion of the plating layer during processing. May be.

[Amount of plating]
When the coating amount of the hot-dip Zn-based plated steel sheet is small, it is disadvantageous for maintaining the corrosion resistance and sacrificial anticorrosive action of the plated surface over a long period of time. As a result of various studies, it is more effective to set the amount of plating deposited on one surface to 15 g / m ² or more. On the other hand, if the coating adhesion amount per side exceeds 250 g / m ² , the amount of Zn vapor generated becomes too large, and spatter and blow holes are generated even when the arc welding method of the hot-dip Zn-based plated steel sheet of this embodiment is used. Therefore, it is preferable that the plating adhesion amount per side is 250 g / m ² or less.

(Welding wire)
As the welding wire 2, it is preferable to use JIS Z3312 YGW11 or JIS Z3312 YGW12. In addition to these, various solid wires defined in JIS Z3312 may be used, and other types may be used. For example, a platingless wire, a flux-cored wire, a slag wire, or the like may be used.

  The wire diameter of the welding wire 2 can use the diameter of 1.2 mm, for example, and may be the diameter of 0.8-1.6 mm.

  In the present embodiment, the supply speed of the welding wire 2 is set in the range of 3 m / min to 15 m / min. Thereby, it is possible to suppress the welding wire 2 from being insufficiently melted and the welding wire 2 from being excessively melted. The supply speed of the welding wire 2 described above may be set according to the set value of the average welding current.

[Welding speed]
The welding speed can be set to 0.4 m / min, for example, and may be set in the range of 0.1 to 2.0 m / min according to various welding conditions.

[Blow hole occupancy, number of spatters attached]
According to the arc welding method of the hot-dip Zn-plated steel sheet of the present embodiment, welding of hot-dip Zn-plated steel sheets can be performed while suppressing the occurrence of spatter and blowholes. Can be provided. Evaluation of the welded member (blow hole occupancy, number of spatter deposits) will be described with reference to FIGS.

  FIG. 4 is a plan view for explaining a method for measuring the blowhole occupancy rate in the welded member 10 formed by welding the molten Zn-based plated steel plates. As shown in FIG. 4, a weld bead 6 is formed on a welded member 10 formed by welding a hot-dip Zn-based plated steel plate 1 and a hot-dip Zn-based plated steel plate 1 ′, and the weld bead 6 has a blow hole 6a. Many have. Further, the length in the longitudinal direction (weld line direction) of the weld bead 6 is defined as a length L, and the length of the i-th blow hole from one end of the weld bead 6 is defined as di. Here, for example, when the joint shape is a T-shaped joint, the molten Zn-based plated steel sheet 1 and the molten Zn-based plated steel sheet 1 ′ shown in FIG. 4 are three-dimensionally welded vertically.

  According to the architectural thin plate welded joint design and construction manual (architecture thin plate welded joint design and construction manual editing committee), the integrated value of the length di of each blowhole 6a schematically shown in FIG. If the blowhole occupancy Br calculated by the following equation (1) from the measured value of the integrated value Σdi (mm) obtained by measuring and integrating the lengths of all the blowholes 6a formed in the bead 6 is 30% or less It is said that there is no problem in welding strength. The welded member 10 in the present invention has a blowhole occupation ratio Br of 30% or less, and is excellent in welding strength.

Br = (Σdi / L) × 100 (1)
here,
di: length of the i-th blow hole observed in the weld bead L: length of the weld bead.

  FIG. 5 is a plan view for explaining a method of measuring the number of spatter deposits on the welded member 10 formed by welding the molten Zn-based plated steel plates. If the number of sputter deposits in the region 8 having a length of 100 mm and a width of 100 mm centered on the weld bead 6 indicated by the dotted line in FIG. Here, the center of the region 8 may be the center of the weld bead 6, and the length of 100 mm is 50 mm from the weld bead 6 to one (hot Zn-plated steel sheet 1) and the other (hot Zn-plated steel sheet 1). ') Means 50mm on the side. At this time, for example, when the joint shape of the welding member 10 is a T-shaped joint, the length 100 mm of the region 8 may be 50 mm in the perpendicular direction with the weld bead 6 as the center. Further, the width of 100 mm means the width of the region 8 in the same direction as the longitudinal direction of the weld bead 6.

  The welding member 10 according to the present invention has 20 or less spatter deposits in the region 8 and is excellent in weld appearance and corrosion resistance.

  Using four types of hot-dip Zn-based plated steel sheets shown in Table 1, lap fillet welded joints were constructed and pulse arc welding was performed. The welding wire 2 used was JIS Z3312 YGW12 having a diameter of 1.2 mm, a welding speed of 0.4 m / min, a bead length of 180 mm, and an overlap margin of 30 mm.

  Further, during welding, the welding state of the portion including the tip of the welding wire 2 and the corner 7a on the welding wire 2 side in the contact portion 7 between the hot-dip Zn-based plated steel sheets before welding is high under the conditions shown below. The distance D from the tip of the welding wire 2 to the corner 7a was measured by taking a picture with a speed camera. After pulsed arc welding, the number of sputtered deposits and blowhole occupancy Br were measured by the methods described above.

[High-speed camera shooting conditions]
High-speed camera: M310 manufactured by Novitec Corporation
Laser light source for visualization: CAVLUX HF manufactured by Cavitra
Pulse wavelength: 810 nm
Number of frames: 4000 frames / second.

  Tables 2 and 3 show the types of hot-dip Zn-based plated steel sheets, pulse arc welding conditions, distance D from the tip of welding wire 2 to corner 7a, the number of sputter deposits, and the measurement results of blowhole occupancy Br. .

  Table 2 uses a molten Zn-6% Al-3% Mg plated steel sheet as the molten Zn-based plated steel sheet, the type of shield gas, the peak current IP, the period PFQ, and the distance D from the tip of the welding wire 2 to the corner 7a. This is the result of investigating the number of sputtered deposits and the blow hole occupation ratio Br by changing.

  No. in which the distance D, the peak current IP, and the period PFQ are within the scope of the present invention. Examples 1 to 20 have less than 20 spatter deposits and less than 30% blowhole occupancy. From this example, spatter and blowholes are suppressed according to the present invention, and the arc has excellent weld appearance and weld strength. It can be seen that a welded member is obtained.

  On the other hand, the distance D, peak current IP, and period PFQ are out of the condition range of the present invention. In the comparative examples 21 to 26, spatter and blowhole are remarkably generated, and an arc welded member excellent in the appearance and weld strength of the weld cannot be obtained.

  Table 3 shows the number of sputtered deposits and blowhole occupancy Br by performing welding under various pulse arc welding conditions and distances D using types of hot-dip Zn-plated steel sheets having various plating compositions and adhesion amounts. It is a result.

No. As shown to 27-39, in the Example in which the distance D from the front-end | tip of the welding wire 2 to the corner part 7a, the peak current IP, the period PFQ, and the coating adhesion amount are in the scope of the present invention, any hot-dip Zn-based plated steel sheet Sputtering and blowholes are also suppressed in the welded member. In particular, no. Coating weight in 35 to 38 has spattering and blowholes is suppressed from with diluted in 15 g / m ² to a thickness basis weight of 250 g / m ^2, dip Zn-base plated steel excellent in weld strength and weld appearance It can be seen that an arc welding member is obtained.

On the other hand, no. In the comparative examples of 40 to 48, the plating adhesion amount exceeds 250 g / m ² which is the upper limit of the present invention, and the distance D from the tip of the welding wire 2 to the corner portion 7a, the peak current IP, and the period PFQ are of the present invention. Even within the range, the generation of Zn vapor is remarkable, so that the generation of spatter and blowholes cannot be suppressed, and a hot-dip Zn-based plated steel-iron-welded member excellent in weld appearance and weld strength has not been obtained.

1.1 'Hot-dip Zn-based plated steel plate 2 Welding wire 2a Wire tip (tip of welding wire)
3 weld pool 4 pulse arc 5 droplet 6 weld bead 7 abutting part 7a corner (weld part)
8 areas (area where the number of spatters is counted)
10 Welded parts

Claims (8)

An arc welding method for welding molten Zn-based plated steel sheets by a pulsed arc welding method in which an arc is generated by alternately supplying a peak current and a base current,
The distance from the tip of the welding wire to the welding target portion at the contact portion between the molten Zn-based plated steel sheets to be welded is such that the welding wire and the molten pool generated at the contact portion do not short-circuit each other. An arc welding method for a hot-dip Zn-based plated steel sheet, characterized by welding with a length that does not extinguish the arc.   The said distance is 2 mm or more and 20 mm or less, The arc welding method of the hot-dip Zn type plated steel plate of Claim 1 characterized by the above-mentioned.   The arc welding method for hot-dip Zn-based plated steel sheets according to claim 1 or 2, wherein the peak current is 350 A or more and 650 A or less, and the cycle of the pulse is 1 ms or more and 20 ms or less.   The plated layer of the hot-dip Zn-based plated steel sheet contains Zn as a main component and contains 1.0% by mass or more and 22.0% by mass or less of Al. An arc welding method for the hot-dip Zn-based plated steel sheet.   5. The arc welding method for a hot-dip Zn-plated steel sheet according to claim 4, wherein the plated layer of the hot-dip Zn-plated steel sheet contains 0.05% by mass or more and 10.0% by mass or less of Mg.   The composition of the plated layer of the hot-dip Zn-based plated steel sheet is Ti: 0.002 to 0.1 mass%, B: 0.001 to 0.05 mass%, Si: 0 to 2.0 mass%, and Fe: The arc welding method for a hot-dip Zn-based plated steel sheet according to claim 5, wherein at least one condition selected from the group consisting of 0 to 2.5 mass% is satisfied. Arc welding is performed so that the blow hole occupancy Br represented by the following formula (1) is 30% or less, and the number of sputter deposits in the region of 100 mm in length and 100 mm in width with the weld bead as the center is 20 or less. The arc welding method for hot-dip Zn-plated steel sheets according to any one of claims 1 to 6.
Br = (Σdi / L) × 100 (1)
(here,
di: length of the i-th blow hole observed in the weld bead L: length of the weld bead) A method for producing a welded member in which hot-dip Zn-based plated steel sheets are welded together by a pulse arc welding method,
The plating adhesion amount per side of the hot-dip Zn-based plated steel sheet is 15 g / m ² or more and 250 g / m ² or less,
The distance from the tip of the welding wire to the welding target portion at the contact portion between the molten Zn-based plated steel sheets to be welded is 2 mm or more and 20 mm or less, and the peak current of the welding current that generates the pulse arc is 350 A or more and 650 A or less. A method for producing a welded member, comprising welding the hot-dip Zn-based plated steel sheets by pulse arc welding with a pulse period of 1 ms to 20 ms.

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