JPWO2015198627A1 - Arc welding method for molten Zn-Al-Mg-based plated steel sheet, method for producing welded member, and arc welded member - Google Patents

Abstract

The Ti / Al concentration ratio Ti / Al of the plated layer of the hot-dip Zn—Al—Mg-based plated steel sheet is 0.0001 to 0.05, and the relationship between Ti / Al and the inter-plate gap G is expressed by the following formula (1) Satisfied. Ti / Al ≦ 0.02G + 0.01 (1)

Description

  The present invention relates to an arc welding method and a welded member for a hot-dip Zn—Al—Mg-based plated steel sheet that has less spatter and blowhole generation and is excellent in appearance and weld strength.

  Since the hot-dip Zn-based plated steel sheet has good corrosion resistance, it is used in a wide range of applications including building members and automobile members. Among them, the hot-dip Zn—Al—Mg-based steel sheet maintains excellent corrosion resistance for a long period of time, and therefore, the demand is increasing as a material to replace the conventional hot-dip Zn-plated steel sheet.

As described in Patent Documents 1 and 2, the plated layer of the hot-dip Zn—Al—Mg plated steel sheet has a primary Al phase or primary Al phase in a Zn / Al / Zn ₂ Mg ternary eutectic matrix. And Zn has a metal structure in which a single phase is dispersed, and corrosion resistance is improved by Al and Mg. Since a dense and stable corrosion product containing Mg in particular is uniformly formed on the surface of the plated layer, the corrosion resistance of the plated layer is remarkably improved as compared with the hot-dip Zn plated steel sheet.

In the production of a hot-dip Zn-Al-Mg-based steel sheet based on a Zn-Al-Mg ternary alloy, the ternary element having the lowest melting point of about 4% by mass of Al and about 3% by mass of Mg. A composition having a crystal point (about 343 ° C.) is advantageous in terms of energy cost. However, as described in Patent Documents 1 and 2, when the plating bath composition in the vicinity of this ternary eutectic point is adopted, a Zn ₁₁ Mg ₂ phase, actually Al / Zn / Zn ₁₁ Mg ₂ ternary eutectic matrix or a phenomenon in which a Zn ₁₁ Mg ₂ phase in which Al primary crystals or Al primary crystals and Zn single phases are mixed in the matrix is locally crystallized. Get up. This locally crystallized Zn ₁₁ Mg ₂ phase is more easily discolored than the other phases, and if left untreated, this portion has a very conspicuous color tone, and the plating appearance, which is the appearance of the entire plating layer, is marked. Inhibit. Furthermore, since the locally crystallized Zn ₁₁ Mg ₂ phase is preferentially corroded, the corrosion resistance is also lowered.

As a method for suppressing the formation and growth of this Zn ₁₁ Mg ₂ phase, Patent Document 1 adds 0.002 to 0.1% by mass of Ti and 0.001 to 0.045% by mass of B in the plating bath. A method of controlling the plating bath temperature and the cooling rate after plating within an appropriate range is disclosed. Patent Document 2 discloses a method for controlling the plating bath temperature and the cooling rate after plating within an appropriate range. In particular, the method of adding Ti and B to the plating bath is effective in improving the productivity of the hot-dip Zn-Al-Mg plated steel sheet with excellent plating appearance and corrosion resistance because the appropriate range of plating bath temperature and cooling rate is wide. is there.

  Hot-dip Zn-based plated steel sheets are used for building members, automobile members, etc., but in such applications, they are often assembled by gas shield arc welding. However, when arc welding is performed on a hot-dip Zn-based plated steel sheet, spatter, pits, and blow holes (hereinafter, blow holes include pits unless otherwise specified) are remarkably generated, resulting in poor arc weldability. This is because the boiling point of Zn is as low as about 906 ° C. compared with the melting point of Fe of about 1538 ° C., so that Zn vapor is generated during arc welding, the arc becomes unstable due to this Zn vapor, and spatter is generated. In addition, blowholes are generated when the weld metal solidifies before the Zn vapor can escape. When spatter adheres to the plated surface, the appearance of the welded portion, which is the appearance in the vicinity of the welded portion, is deteriorated, and the corrosion resistance is lowered because the portion becomes a starting point of corrosion. On the other hand, if the occurrence of blowholes is significant, the welding strength decreases, which causes a problem.

  Similarly to the hot-dip Zn-based plated steel sheet, blowholes are generated in arc-welded hot-dip Zn-Al-Mg-based steel sheets. However, the hot-dip Zn—Al—Mg-based steel sheet has less blowholes than other hot-dip Zn-plated steel sheets and alloyed hot-dip Zn-plated steel sheets, and arc weldability is improved. This cause is thought to be due to Al in the plating layer as described in Non-Patent Document 1. As shown in FIG. 1, Al significantly lowers the viscosity of Fe even in a small amount as compared with Si and Mn. In hot-dip Zn-Al-Mg plated steel sheets, Al in the plating layer is mixed into the weld metal during arc welding, which lowers the viscosity of the weld metal and facilitates the discharge of Zn vapor, reducing the generation of blowholes. It is estimated that

Japanese Patent Publication “Patent No. 3149129” Japanese Patent Gazette “Patent No. 3179401”

Nisshin Steel Technical Report No. 92 (2011) p. 44

As described above, the addition of Ti to the plating bath is effective in improving the appearance of the plating by suppressing the formation and growth of the Zn ₁₁ Mg ₂ phase, but on the other hand, the amount of spatter and blow holes generated increases. Reduces arc weldability. This is because, as shown in FIG. 1, Ti greatly increases the viscosity of Fe by adding a small amount in contrast to Al, so that Ti in the plating layer is mixed in the weld metal and the viscosity of the weld metal increases. I guess. When the viscosity of the weld metal increases, Zn vapor becomes difficult to be discharged from the weld metal and stays. When the retained Zn vapor is ejected all at once, the arc becomes unstable and the occurrence of spatter becomes significant. In addition, blowholes are generated when the weld metal solidifies before the Zn vapor can escape.

  As described above, when Ti is added to the plating bath in order to improve the plating appearance, spatter and blowholes are easily generated, and the appearance and weld strength of the welded portion are reduced. In view of such a current situation, an object of the present invention is to provide an arc welding method and a welded member for a hot-dip Zn—Al—Mg-based plated steel sheet, which are excellent in weld appearance and weld strength.

  As a result of detailed studies by the inventors, the appearance of the plating is impaired by controlling the relationship between the Ti / Al concentration ratio of the plated layer of the hot-dip Zn—Al—Mg-based plated steel sheet and the gap between the sheets within an appropriate range. The present invention has been completed with the knowledge that sputtering and blowholes can be reduced without any problems.

That is, the above-mentioned problem is that the composition of the plated layer of the hot-dip Zn—Al—Mg-based steel sheet is mainly composed of Zn, and is expressed by mass: Al: 1.0-22.0%, Mg: 0.05-10. 0%, Ti: 0.002 to 0.10%, Ti / Al concentration ratio Ti / Al is 0.0001 to 0.05, and the relationship between Ti / Al and inter-plate gap G is as follows: This is achieved by satisfying the expression (1).
Ti / Al ≦ 0.02G + 0.01 (1)

  ADVANTAGE OF THE INVENTION According to this invention, the sputter | spatter and blowhole in arc welding of a hot-dip Zn-Al-Mg type plated steel plate can be reduced, and the welding member excellent in a welded part external appearance, weld strength, and corrosion resistance can be provided.

The figure which showed the influence of the addition element which acts on the viscosity of Fe. The figure which showed typically the pit and blowhole of the lap fillet weld joint. The figure explaining the measurement method of a sputter | spatter adhesion number, and the definition of a blowhole occupation rate. The graph which showed the influence of Ti / Al and the gap between plates on a blowhole in a lap fillet welded joint.

  FIG. 2 schematically illustrates a weld cross-sectional structure of a lap fillet weld joint. This type of welded joint by arc welding is frequently used for automobile chassis. A molten Zn—Al—Mg-based plated steel sheet 1, 1 ′ having a molten Zn—Al—Mg-based plated layer 2 on the surface is disposed so as to overlap the surface of the molten Zn—Al—Mg-based plated steel sheet 1 ′. A weld bead 3 is formed on the end surface of the molten Zn—Al—Mg-based plated steel sheet 1 and both members are joined.

  FIG. 2A is a cross-sectional view of a welded portion in which pits 4 are generated without allowing Zn vapor to escape from the weld metal. FIG. 2B is a cross-sectional view of the welded portion where the blown holes 5 are generated by confining Zn vapor in the weld metal. FIGS. 2A and 2B are cross sections of a welded portion when no gap between plates is provided. If there is no gap between the plates, there is no route for the Zn vapor to escape only from the front side of the weld metal 3, so that pits and blow holes are likely to occur. Further, when Zn vapor staying in the weld metal is ejected at once, the arc becomes unstable and spatter is generated. FIG. 2C is a cross-sectional view of the welded portion when the inter-plate gap 6 is provided. When the inter-plate gap 6 is provided, Zn vapor is also discharged to the inter-plate gap 6 side, so that the effect of suppressing the generation of both sputtering and blow holes is great.

  However, depending on the shape of the arc welded structural member, the gap between the plates may not be provided or may not be increased. Therefore, in the present invention, the viscosity of the weld metal is lowered by appropriately managing the Ti / Al concentration ratio Ti / Al of the plated layer of the molten Zn—Al—Mg-based plated steel sheet according to the gap between the plates, and the Zn vapor. Discharge is promoted to suppress spatter and blowholes.

Molten Zn-Al having a plating adhesion amount of 90 g / m ² per side with the Mg concentration of the plating layer kept constant at 3% by mass, the Al concentration varied from 1 to 22% by mass, and the Ti concentration was varied from 0 to 0.10%. -A Mg-based plated steel sheet sample was produced in the laboratory. The sample size was 3.2 mm thick, 100 mm wide, and 200 mm long. This sample was lap fillet welded with an overlap margin of 30 mm, a weld bead length L = 180 mm, and a gap between plates of 0 to 2.0 mm. An X-ray transmission photograph of the arc welded portion was taken, the blow hole length integrated value Σdi (mm) schematically shown in FIG. 3 was measured, and the blow hole occupation ratio Br was calculated from the following equation (3). . Further, the number of sputters deposited in a region having a width of 100 mm and a length of 100 mm centered on the weld bead 3 indicated by a dotted line in FIG. 3 was visually measured.
Br = (Σdi / L) × 100 (3)

  FIG. 4 shows the results of investigating the effects of the Ti / Al and inter-plate gaps on the blow hole occupancy Br and the number of sputter deposits. According to the Architectural Thin Plate Welded Joint Design and Construction Manual (Architecture Thin Plate Welded Joint Design and Construction Manual Editorial Committee), it is said that there is no problem in welding strength if the blowhole occupancy Br is 30% or less. . Further, if the number of sputters deposited is 20 or less, the spatter is not noticeable and the influence on the corrosion resistance is small. Therefore, in FIG. 4, the case where the blowhole occupancy is 30% or less and the number of sputter deposits of 20 or less is indicated by ◯, and the case where the blowhole occupancy exceeds 30% or the amount of sputter adherence exceeds 20 is plotted by ●. In the region where Ti / Al is less than the straight line in FIG. 4, the blow hole occupancy Br is 30% or less and the number of sputters is 20 or less. Sputter and blow can be achieved by appropriately managing the inter-plate gap G and Ti / Al. It can be seen that holes can be reduced.

  Here, FIG. 4 shows a result of investigation when the Mg concentration of the plating layer is kept constant at 3% by mass. However, since the boiling point of Mg is lower than the melting point of Fe and Mg evaporates before Fe melts, the Mg concentration has little effect on the viscosity of the weld metal. Therefore, even if the Mg concentration changes, the blow hole occupancy Br can be suppressed to 30% or less and the number of sputter deposits can be suppressed to 20 or less by setting Ti / Al to a region below the straight line in FIG.

The hot-dip Zn—Al—Mg-based plated steel sheet and arc welding conditions of the present invention will be described in detail.
[Fused Zn-Al-Mg plated steel sheet]
The composition of the plated layer of the hot-dip Zn—Al—Mg-based plated steel sheet of the present invention is composed of Zn as a main component, and by mass%, Al: 1.0 to 22.0%, Mg: 0.05 to 10.0%, Ti: 0.002 to 0.10% and inevitable impurities are contained. The plating layer composition substantially reflects the hot-dip plating bath composition. Although the method of hot dipping is not particularly limited, it is generally advantageous in terms of cost to use an in-line annealing type hot dipping equipment. Hereinafter, the component elements of the plating layer will be described. “%” Of the plating layer component element means “mass%” unless otherwise specified.

  Al is effective in improving the corrosion resistance of the plated steel sheet, and suppresses the generation of Mg oxide dross in the plating bath. In order to fully exhibit these actions, it is necessary to secure an Al content of 1.0% or more, and it is more preferable to secure an Al content of 4.0% or more. On the other hand, when the Al content increases, a brittle Fe—Al alloy layer easily grows on the base of the plating layer, and excessive growth of the Fe—Al alloy layer causes a decrease in plating adhesion. As a result of various studies, the Al content is more preferably 22.0% or less, and may be controlled to 15.0% or less, or even 10.0% or less.

When Ti is contained in the hot dipping bath, the effect of suppressing the formation and growth of Zn ₁₁ Mg ₂ phase during hot dipping is exhibited. When the amount of Ti added is less than 0.002%, the suppression effect is insufficient. When it exceeds 0.1%, the appearance of the plating layer surface (plating appearance) is poor due to the formation and growth of Ti-Al-based precipitates during plating. It becomes a factor causing. For this reason, in this invention, Ti addition amount is limited to 0.002-0.1%.

As described above, both Al and Ti are effective in improving the plating quality. However, in arc welding, Al lowers the viscosity of the weld metal to suppress spatter and blowholes. Conversely, Ti is the viscosity of the weld metal. Is considered to promote the generation of spatter and blowholes. Therefore, in the present invention, the Ti / Al concentration ratio Ti / Al of the plating layer is adjusted to be 0.0001 to 0.05, so that both the plating appearance and the sputter and blowhole suppression are compatible. Thereby, the defect of the surface external appearance of both the external appearance (plating external appearance) of a plating layer and the external appearance (welding part external appearance) vicinity of a welding part can be suppressed. When Ti / Al is less than 0.0001, the Ti concentration is low, and the effect of suppressing the formation and growth of the Zn ₁₁ Mg ₂ phase is insufficient. On the other hand, when Ti / Al exceeds 0.05, the viscosity of the weld metal is increased by Ti, and the generation of spatter and blow holes is promoted.

Mg exhibits the effect | action which produces | generates a uniform corrosion product on the surface of a plating layer, and raises the corrosion resistance of a plated steel plate remarkably. The Mg content is more preferably 0.05% or more, and more preferably 1.0% or more. On the other hand, if the Mg content in the plating bath increases, Mg oxide-based dross is likely to occur, which causes a deterioration in the quality of the plating layer, so the Mg content is set to a range of 10.0% or less. Mg has a boiling point of about 1091 ° C., which is lower than the melting point of Fe,
Like Zn, it is considered that it evaporates during arc welding and causes spatter and blowholes, so the Mg content is preferably 10.0% or less.

B, like Ti, has the effect of suppressing the formation and growth of Zn ₁₁ Mg ₂ phase, so B may be added to the plating layer. In the case of B, it is more effective to make the addition amount 0.001% or more. However, excessive addition of B causes a defect in the appearance (plating appearance) of the plating layer surface due to Ti-B or Al-B-based precipitates, so it is desirable that B is in the range of 0.05% or less. .

  When Si is contained in the hot dipping bath, excessive growth of the Fe—Al alloy layer formed at the interface between the plating original plate surface and the plating layer is suppressed, and the workability of the hot-dip Zn—Al—Mg plated steel sheet is improved. This is advantageous. Therefore, Si can be contained as necessary. In that case, it is more effective to set the Si content to 0.005% or more. However, since excessive Si content causes an increase in the dross amount in the hot dipping bath, the Si content is preferably 2.0% or less.

  In the hot dipping bath, Fe is likely to be mixed because the steel sheet is immersed and passed. When Fe is mixed in the Zn—Al—Mg plating layer, the corrosion resistance is lowered, so the Fe content is preferably 2.5% or less.

If the coating amount of the molten Zn—Al—Mg based steel sheet is small, it is disadvantageous for maintaining the corrosion resistance and sacrificial anticorrosive action of the plated surface for a long period of time. As a result of various studies, it is more effective to set the plating adhesion amount per side to 20 g / m ² or more. On the other hand, when the amount of plating adhesion increases, the amount of evaporated Zn during welding increases, and sputtering and blowholes are likely to occur. For this reason, it is desirable that the amount of plating deposited on one side be 250 g / m ² or less.

Here, the plating adhesion amount per side may be measured by the weight method as follows. First, a test piece having a predetermined shape (for example, a disk shape with a diameter of 50 mm or a square shape with a size of 50 × 50 mm) is collected from a molten Zn—Al—Mg-based steel sheet, and the weight M0 of the test piece is measured. Next, a sealing tape is applied to the entire area of one surface of the test piece, and immersed in hydrochloric acid diluted to about 10% by volume, and the plating layer on the surface on which the sealing tape is not applied is dissolved. Thereafter, the test piece is washed with water and dried, the sealing tape is peeled off, and the weight M1 is measured. And (M0-M1) is remove | divided by the area of a test piece, and the plating adhesion amount (g / m < ² >) per single side | surface is calculated.

[Arc welding conditions]
As described above, the inter-plate gap G facilitates the discharge of Zn vapor from the weld metal, and thus is effective in suppressing spatter and blow holes. However, when the inter-plate gap G is not provided due to the design of the welded structure member or when the inter-plate gap G cannot be increased, the Ti and Al concentrations Ti / Al of the plating layer are set according to the inter-plate gap G (1 ). Thereby, the blow hole occupation ratio Br is suppressed to 30% or less, and the strength of the welded portion is equal to or higher than that of the base material. In addition, the number of sputters deposited is 20 or less.
Ti / Al ≦ 0.02G + 0.01 (1)

  Further, when the gap G between the plates exceeds 2.0 mm, the throat thickness is reduced and the welding strength is reduced or perforation occurs. Therefore, the upper limit of the gap G between the plates is preferably 2 mm.

Moreover, in this invention, it is preferable to make the welding heat input Q shown by following (2) Formula into the range of 2000-12000 J / cm. When the welding heat input Q is less than 2000 J / cm, the cooling rate of the weld metal is increased, and the weld metal is solidified before Zn vapor is discharged from the weld metal, and blow holes are likely to occur. On the other hand, if the welding heat input exceeds 12000 J / cm, the amount of Zn evaporation increases and sputtering and blowholes are likely to occur.
Q = (I × V) / v (2)
Here, I is the welding current (A), V is the arc voltage (V), and v is the welding speed (cm / sec).

In the present invention, the type of shielding gas is not particularly limited, but it is inexpensive carbon dioxide gas, Ar-20 volume% CO ₂ gas having a large sputter suppression effect, or Ar-5 volume% CO ₂ gas with a further reduced CO ₂ concentration. Etc. are suitable.

  A hot-melt Zn—Al—Mg plated steel sheet arc welded member arc welded under the above arc welding conditions has a blowhole occupancy Br of 30% or less and a sputter deposition number of 20 or less, and is excellent in welded portion appearance, corrosion resistance, and welding strength.

As described above, in the arc welding method of the hot-dip Zn—Al—Mg-based plated steel sheet according to the present embodiment, the composition of the plating layer is mainly composed of Zn, and is in mass%, Al: 1.0 to 22. 0%, Mg: 0.05 to 10.0%, Ti: 0.002 to 0.10%, Ti / Al concentration ratio Ti / Al is 0.0001 to 0.05, and Ti / Al and the inter-plate gap G satisfy the following formula (1).
Ti / Al ≦ 0.02G + 0.01 (1)

  The inter-plate gap G is preferably 2 mm or less.

The molten Zn—Al—Mg based plated steel sheet preferably has a plating adhesion amount of 20 to 250 g / m ² per side.

Moreover, it is preferable that the arc welding method sets the welding heat input Q shown by the following formula (2) in the range of 2000 to 12000 J / cm.
Q = (I × V) / v (2)
Here, I is the welding current (A), V is the arc voltage (V), and v is the welding speed (cm / sec).

Furthermore, the welded member obtained by arc welding of the molten Zn—Al—Mg-based plated steel sheet or a molding material made from the same under the above conditions has a blowhole occupancy ratio Br represented by the following expression (3) of 30% or less. It is preferable that the weld joint strength is excellent.
Br = (Σdi / L) × 100 (3)
However, Σdi is the integrated value (mm) of the blowhole length, and L is the weld bead length (mm).

  Further, the welded member obtained by arc welding of the molten Zn—Al—Mg-based plated steel sheet or a molding material made of the same under the above conditions has a sputter deposition number of 20 in the region of 100 mm in length and 100 mm in width centering on the weld bead. It is preferable that the number is less than or equal to the number, and thereby the welded portion appearance and corrosion resistance are excellent.

  Further, the plating layer may contain one or more selected from the group consisting of B: 0.001 to 0.05%, Si: 0 to 2.0%, and Fe: 0 to 2.5%. Good.

A cold-rolled steel strip having a thickness of 3.2 mm and a width of 1000 mm having the composition shown in Table 1 is used as a plating base plate, and this is passed through a hot dipping line to obtain a molten Zn-Al-Mg system having various plating layer compositions. A plated steel sheet was produced. The plating layer composition and the plating adhesion amount are shown in Table 2 described later. Each molten Zn—Al—Mg-based plated steel sheet was visually observed to investigate whether a Zn ₁₁ Mg ₂ -based phase was generated.

上記溶融Ｚｎ−Ａｌ−Ｍｇ系めっき鋼板から幅１００ｍｍ、長さ２００ｍｍのサンプルを切り出し、重ね隅肉継手溶接法でガスシールドアーク溶接を行い、前述の方法でブローホール占有率Ｂｒとスパッタ付着個数を測定した。アーク溶接条件とブローホール占有率Ｂｒおよびスパッタ付着個数の測定結果を表２に示す。

A sample having a width of 100 mm and a length of 200 mm is cut out from the above molten Zn-Al-Mg-based plated steel sheet, gas shielded arc welding is performed by the lap fillet joint welding method, and the blow hole occupation ratio Br and the number of sputtered deposits are determined by the method described above. It was measured. Table 2 shows the measurement results of the arc welding conditions, the blowhole occupation ratio Br, and the number of sputtered deposits.

表２のＮｏ．１〜１９，３２〜３５に示すように、めっき層組成が、Ｚｎを主成分とし、質量％で、Ａｌ：１.０〜２２.０％、Ｍｇ：０.０５〜１０.０％、Ｔｉ：０.００２〜０.１０％を含有し、かつ、めっき層のＴｉとＡｌの濃度比Ｔｉ／Ａｌが０．０００１〜０．０５であり、Ｔｉ／Ａｌと板間ギャップＧの関係がＴｉ／Ａｌ≦０．０２Ｇ＋０．０１ を満たす実施例では、Ｚｎ_１１Ｍｇ_２系相が観察されず、ブローホール占有率は３０％以下、スパッタ付着個数は２０以下であった。本実施例から、本発明により溶接部外観と耐食性および溶接強度に優れた溶融Ｚｎ−Ａｌ−Ｍｇ系めっき鋼板アーク溶接部材が得られることがわかる。

No. in Table 2 As shown in 1-19 and 32-35, the plating layer composition is composed mainly of Zn, and is in mass%, Al: 1.0 to 22.0%, Mg: 0.05 to 10.0%, Ti : 0.002 to 0.10%, the Ti / Al concentration ratio Ti / Al of the plating layer is 0.0001 to 0.05, and the relationship between Ti / Al and the inter-plate gap G is Ti In the example satisfying /Al≦0.02G+0.01, the Zn ₁₁ Mg ₂ phase was not observed, the blowhole occupancy was 30% or less, and the number of sputter deposits was 20 or less. From this example, it can be seen that the present invention can provide a welded Zn-Al-Mg-based plated steel sheet arc welded member having excellent weld appearance and corrosion resistance and weld strength.

On the other hand, No. in Table 3 where Ti and B were not added to the plating layer. In Comparative Examples 20 and 21, a Zn ₁₁ Mg ₂ phase was observed. No. Ti / Al is outside the scope of the invention. In the comparative examples of 22 to 26, blowhole occupancy is 38 to 58%, and blowholes are remarkably generated, and the number of sputter deposits is 23 to 33, and spatter is also remarkably generated. Moreover, the plating adhesion amount per one side exceeds 250 g / m ² . No. 27 and No. 28, and No. of heat input less than 2000 J / cm or more than 12000 J / cm. In the reference examples 29 to 31 as well, there was a tendency that the blowhole occupancy and the number of sputtered deposits increased.

1, 1 ′ Molten Zn—Al—Mg plated steel sheet 2 Plating layer 3 Weld bead 4 Pit 5 Blow hole 6 Inter-plate gap

Claims (9)

The composition of the plating layer is mainly composed of Zn, and contains, by mass, Al: 1.0 to 22.0%, Mg: 0.05 to 10.0%, Ti: 0.002 to 0.10%. An arc welding method for a molten Zn-Al-Mg-based plated steel sheet that joins the molten Zn-Al-Mg-based plated steel sheets,
The plating layer has a Ti / Al concentration ratio Ti / Al of 0.0001 to 0.05,
An arc welding method for a hot-dip Zn—Al—Mg-based plated steel sheet in which the relationship between Ti / Al and the inter-plate gap G satisfies the following formula (1).
Ti / Al ≦ 0.02G + 0.01 (1) ^2. The arc welding method for a hot-dip Zn—Al—Mg-based plated steel sheet according to claim 1, wherein the coating amount per one side is 20 to 250 g / m ² . The arc welding method for a hot-dip Zn-Al-Mg-based plated steel sheet according to claim 1 and 2, wherein arc welding is performed in a range where the welding heat input Q represented by the following formula (2) is 2000 to 12000 J / cm.
Q = (I × V) / v (2)
Where I is the welding current (A), V is the arc voltage (V), and v is the welding speed (cm / sec).   The arc welding method for a hot-dip Zn-Al-Mg-based plated steel sheet according to any one of claims 1 to 3, wherein the inter-plate gap G is 2 mm or less.   The composition of the plated layer of the hot-dip Zn—Al—Mg-based steel sheet is further B: 0.001 to 0.05%, Si: 0 to 2.0%, Fe: 0 to 2.5% in mass%. The arc welding method for a hot-dip Zn-Al-Mg-based plated steel sheet according to any one of claims 1 to 4, comprising 1 or 2 or more selected from the group consisting of: The arc welding method for hot-dip Zn-Al-Mg-based plated steel sheets according to claim 1, wherein arc welding is performed so that a blow hole occupation ratio Br represented by the following formula (3) is 30% or less.
Br = (Σdi / L) × 100 (3)   The arc welding method for hot-dip Zn-Al-Mg-based plated steel sheets according to claim 1 or 6, wherein arc welding is performed so that the number of sputter deposits in a region of 100 mm length and 100 mm width centering on the weld bead is 20 or less. The blowhole occupation rate Br shown by the following formula (3) is 30% or less,
A welded member arc-welded by the arc welding method according to any one of claims 1 to 5.
Br = (Σdi / L) × 100 (3)
However, Σdi is the integrated value (mm) of the blowhole length, and L is the weld bead length (mm). The number of sputter adhesion in the region of 100 mm in length and 100 mm in width with the weld bead as the center is 20 or less.
A welded member arc-welded by the arc welding method according to any one of claims 1 to 5.

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