CN110402177B

CN110402177B - Arc welding method

Info

Publication number: CN110402177B
Application number: CN201880014586.3A
Authority: CN
Inventors: 木梨光; 梅原悠; 佐藤浩二
Original assignee: Kobe Steel Ltd
Current assignee: Kobe Steel Ltd
Priority date: 2017-03-02
Filing date: 2018-03-02
Publication date: 2021-12-21
Anticipated expiration: 2038-03-02
Also published as: WO2018159844A1; CN110402177A

Abstract

The invention aims to provide an arc welding method which can reduce the generation of splash and has good slag cohesiveness even if the welding speed is increased. One aspect of the present invention relates to an arc welding method for welding a steel plate by controlling feeding of a wire in a forward and backward direction, wherein welding is performed using a wire containing C and containing Si in mass% and an Ar-containing gas such that a frequency in the forward and backward direction of the wire is 35Hz to 160Hz, and the wire is welded by using: 0.2% or more and 1.3% or less, Mn: 0.2% or more, 1.5% or less, and S: 0.01% to 0.05%, and the balance of Fe and unavoidable impurities.

Description

Arc welding method

Technical Field

The present invention relates to an arc welding method.

Background

As arc welding methods capable of reducing the occurrence of spatter during welding of thin steel sheets, arc welding methods in which welding is performed while controlling the feeding of a welding wire in a forward and backward direction and arc welding methods in a pulse control method are known.

For example, patent document 1 discloses a welding method for performing arc welding by repeating short-circuiting and arc striking using a welding wire for welding for a member subjected to surface treatment as an arc welding method for suppressing occurrence of blowholes and occurrence of spatters. The welding method includes: a step of transferring a droplet formed by the welding wire to the member side; and a step of welding the member by pushing the molten pool in a direction opposite to the welding proceeding direction to discharge the gas generated from the member from the generation position. Then, the welding wire is fed backward so that the distance between the welding wire and the molten pool is within a predetermined range, and a predetermined welding current generated by an arc force for pushing the molten pool is supplied so that the welding current is kept constant for a predetermined period of time or is gradually increased or decreased.

For example, patent document 2 discloses a gas-shielded arc welding method in which a welding wire having a predetermined chemical composition is used as a welding wire, and a mixed gas of an inert gas and carbon dioxide is used as a shielding gas to perform pulse MAG welding by a pulse arc method, as a welding method in which spatter is less generated during welding and welding workability is excellent. In the gas-shielded arc welding method described in patent document 1, the pulse frequency is preferably controlled to 60 to 120Hz from the viewpoints of suppression of the amount of spatter generated and prevention of welding defects. In addition, the pulse width is preferably controlled to be 1.0 to 1.3msec from the viewpoint of suppressing the amount of spatter generation and the stability of penetration.

Prior art documents

Patent document

Patent document 1: japanese patent No. 6043969 publication

Patent document 2: japanese patent No. 3523917 publication

However, in some cases, a plating step is performed after arc welding on steel sheets used for automobiles, building materials, electrical equipment, and the like. In this case, if the slag does not sufficiently aggregate at the welded portion during arc welding, the slag remains at the welded portion. Therefore, if slag remains in the welded portion, there is a problem that the adhesion of the coating film formed by the subsequent electroplating cannot be sufficiently secured. Therefore, in such applications, it is required that slag cohesiveness during welding is good.

However, in the arc welding methods described in patent documents 1 and 2, the cohesion of slag is not sufficiently studied, and there is still room for improvement. That is, if slag does not sufficiently aggregate during welding, slag remains in the welded portion, and as a result, the above-described problem may occur. Particularly, in the welding of thin plates, the welding speed is required to be high, and slag cohesion is required to be good even if the welding speed is increased.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide an arc welding method capable of reducing the occurrence of spatter and having good slag cohesion even when the welding speed is increased.

A first aspect of the present invention relates to an arc welding method for welding a steel plate by controlling feeding of a welding wire in a forward and backward direction, wherein welding is performed using a welding wire and an Ar-containing gas such that the frequency of the forward and backward direction of the welding wire is 35Hz to 160Hz,

the welding wire contains C and, in mass%, C

Si: more than 0.2 percent and less than 1.3 percent,

mn: 0.2% or more and 1.5% or less, and

s: more than 0.01 percent and less than 0.05 percent,

the balance being Fe and unavoidable impurities.

In a preferred embodiment of the first aspect of the present invention, the wire may further contain, in mass%, Al: 0.1% or more and 0.5% or less, Mo: 0.1% or more and 2.0% or less, Ti: 0.3% or less, Cu: 0.4% or less.

In a preferred embodiment of the first embodiment of the present invention, the contents of S and Al in the wire may satisfy 0.3. ltoreq. S.ltoreq.10 + Al. ltoreq.0.7.

In a preferred embodiment of the first embodiment of the present invention, the thickness of the steel sheet may be 0.6mm to 5 mm.

In a preferred embodiment of the first embodiment of the present invention, welding may be performed with a frequency of the wire in the advancing and retreating direction of 45Hz to 130Hz, more preferably 70Hz to 110 Hz.

In a preferred embodiment of the first embodiment of the present invention, welding may be performed with an average value of the welding current of 80A or more and 350A or less and a welding speed of 60cm/min or more.

A second embodiment of the present invention relates to an arc welding method for performing arc welding on a steel sheet by a pulse control method, wherein welding is performed using a wire and an Ar-containing gas such that a voltage pulse frequency is 50Hz or more and 200Hz or less and a voltage pulse width is 1.5ms or more and 10ms or less,

the welding wire contains C and, in mass%, contains

Si: more than 0.2 percent and less than 1.1 percent,

mn: 0.2% or more and 1.4% or less, and

s: more than 0.010 percent and less than 0.050 percent,

the balance being Fe and unavoidable impurities.

In a preferred embodiment of the second embodiment of the present invention, the wire may further contain, in mass%, Al: 0.1% or more and 0.5% or less, Mo: 0.1% or more and 2.0% or less, Cu: 0.4% or less.

In a preferred embodiment of the second embodiment of the present invention, welding may be performed with a peak current of 380A or more and 490A or less.

In a preferred embodiment of the second embodiment of the present invention, welding may be performed with a base current of 80A or more and 180A or less.

In a preferred aspect of the second embodiment of the present invention, welding may be performed with a duty ratio of the pulse current of 0.2 to 0.6.

In a preferred embodiment of the second embodiment of the present invention, the thickness of the steel sheet may be 0.6mm to 5 mm.

According to the arc welding method of the present invention, the occurrence of spatter can be reduced, and slag cohesiveness is good even if the welding speed is accelerated.

Detailed Description

Hereinafter, the mode for carrying out the present invention will be described in detail. The present invention is not limited to the embodiments described below.

[ first embodiment ]

An arc welding method according to a first embodiment of the present invention (hereinafter, also referred to as a welding method of the first embodiment) is an arc welding method for welding a steel plate by feeding a wire in a forward and backward direction, wherein welding is performed using a wire containing C and Si in mass% and an Ar-containing gas such that the frequency of the forward and backward direction of the wire is 35Hz to 160 Hz: 0.2% or more and 1.3% or less, Mn: 0.2% or more, 1.5% or less, and S: 0.01% to 0.05%, and the balance of Fe and unavoidable impurities.

In the welding method according to the first embodiment, arc welding is performed while controlling the feeding of the wire in the advancing and retreating direction. More specifically, the following operations are repeated: the feeding of the wire is controlled in the forward and backward direction to generate an arc, and the wire is advanced (forward feeding) to make the molten metal at the tip of the molten wire contact with the molten pool to extinguish the arc, and then the wire is moved backward (backward feeding) to transit the molten metal. By performing welding in this manner, the occurrence of spatter during welding can be reduced. In the welding method according to the first embodiment, the frequency of the advance and retreat direction of the welding wire is defined by defining one advance (forward feeding) and retreat (backward feeding) of the welding wire as 1 cycle. In the welding method of the first embodiment, for example, Cold Metal Transfer (Cold Metal Transfer) welding or the like is included.

< solder wire >

Next, the reasons for limiting the content of each element in the welding wire used in the welding method according to the first embodiment (hereinafter, also referred to as the welding wire according to the first embodiment or simply the welding wire) will be described below. The contents of these elements are relative to the total mass of the wire. In the present specification, the percentage (% by mass) based on the mass is synonymous with the percentage (% by weight) based on the weight.

(C)

C is an element for improving strength. In the welding wire of the first embodiment, C may be contained, that is, the content of C may be higher than 0%, but in order to more favorably achieve the above effects, it is preferably 0.02 mass% or more, and more preferably 0.04 mass% or more.

The upper limit of the C content is not particularly limited, but the C content is preferably 0.15 mass% or less, and more preferably 0.10 mass% or less, from the viewpoint of reducing spatters, suppressing thermal cracking, and the like.

(Si)

Si is an effective deoxidizer and is an indispensable element for deoxidizing the weld metal. If the content of Si is less than 0.2 mass%, the deoxidizing effect is impaired, the surface tension is lowered, and pore defects such as pits and blowholes are likely to occur. In addition, the slag cohesiveness is reduced. Therefore, the content of Si is 0.2 mass% or more, preferably 0.3 mass% or more, and more preferably 0.5 mass% or more.

On the other hand, Si has a characteristic that the lower the content, the lower the resistance of the wire, and the lower the resistance of the wire, the more difficult the wire is to melt (the resistance heat becomes low), and therefore the required welding current becomes large, and as a result, the higher the arc force becomes, and the porosity defects such as craters and blowholes can be suppressed. When the content of Si is more than 1.3 mass%, the amount of slag generated on the bead surface increases, and the slag cohesiveness also decreases. Therefore, the content of Si is 1.3 mass% or less, preferably 1.2 mass% or less, and more preferably 1.0 mass% or less.

(Mn)

Mn is an oxygen scavenger effective as Si and is an element that easily bonds to S. If the Mn content is less than 0.2 mass%, the deoxidation and desulfurization effects are impaired, the surface tension is lowered, and pore defects such as pits and blowholes are likely to occur. In addition, the slag cohesiveness is reduced. Therefore, the Mn content is 0.2 mass% or more, preferably 0.3 mass% or more, and more preferably 0.5 mass% or more.

On the other hand, if the Mn content is more than 1.5 mass%, a thin oxide film that is difficult to peel off is generated on the bead surface. In addition, the slag cohesiveness is reduced. Therefore, the Mn content is 1.5 mass% or less, preferably 1.3 mass% or less, and more preferably 1.1 mass% or less.

(S)

S is an element that contributes to the agglomeration of slag, but this effect cannot be obtained when the content is less than 0.01 mass%, and therefore the content of S is 0.01 mass% or more, preferably 0.02 mass% or more.

On the other hand, if the S content is more than 0.05 mass%, the flow on the surface of the molten pool changes greatly, and the slag moves close to the region immediately below the arc and vibrates sharply, and as a result, the coagulation effect is reduced. Therefore, the S content is 0.05 mass% or less, preferably 0.04 mass% or less.

The balance of the wire of the first embodiment is made up of Fe and unavoidable impurities, and the unavoidable impurities include P, Cr, Ni, N, O, and the like, and are allowed to be included in a range that does not impair the effects of the present invention.

In addition, in the welding wire of the first embodiment, at least one of the following components may be added in addition to the chemical components.

(Al)

Al is an element contributing to slag cohesion. In the welding wire of the first embodiment, Al is not necessarily added, but when the content of Al is less than 0.1 mass%, the slag aggregation effect is difficult to obtain, and therefore when Al is added, the content thereof is preferably 0.1 mass% or more, and more preferably 0.2 mass% or more.

On the other hand, if the content of Al is more than 0.5 mass%, the separation of molten droplets is unstable, the vibration of the molten pool is disturbed, and the splashing is increased, and as a result, the slag coagulation effect may be reduced. Therefore, when Al is added, the content thereof is preferably 0.5 mass% or less, more preferably 0.4 mass% or less.

(Mo)

Mo is an element contributing to an increase in strength. In the welding wire according to the first embodiment, Mo is not necessarily added, but in order to exhibit this effect well, Mo is preferably added in an amount of 0.1 mass% or more, more preferably 0.3 mass% or more.

On the other hand, if Mo exceeds 2.0 mass%, an intermetallic compound is formed with Fe at high temperature, and therefore the effect is saturated. Therefore, when Mo is added, the content thereof is preferably 2.0 mass% or less, more preferably 1.5 mass% or less.

(Ti)

Ti is a strong deoxidizing element, reduces the oxygen content of the molten metal, and can lower the surface tension, and therefore is effective when the oxygen content in the wire is high. However, if the amount is more than 0.3% by mass, a large amount of slag is generated. Therefore, when Ti is added, the content thereof is preferably 0.3 mass% or less, more preferably 0.2 mass% or less.

(Cu)

Cu is an element effective for improving the electrical conductivity and the rust resistance. When Cu is contained, the lower limit of the content is not particularly limited, but is preferably 0.1 mass% or more in order to more satisfactorily obtain this effect. In addition, the content of Cu is preferably 0.4 mass% or less from the viewpoint of suppressing the occurrence of thermal cracking. In the wire of the first embodiment, Cu plating may be performed as needed. Here, Cu is a total value of a portion included in the base material of the welding wire and a portion plated with Cu.

(0.3≤S×10+Al≤0.7)

In the welding wire according to the first embodiment, the contents of S and Al preferably satisfy the following relational expression. In this case, the slag cohesiveness can be further improved by adjusting the contents of S and Al so as to satisfy the relational expression.

0.3≤S×10+Al≤0.7

(diameter of welding wire)

In the first embodiment, the diameter of the welding wire is not particularly limited, and may be appropriately selected from the range in which it is generally used. The diameter of the welding wire is, for example, 0.8mm to 1.4 mm. The same applies to the second embodiment described later.

(method for manufacturing welding wire)

As a method for manufacturing the welding wire, for example, a wire rod of a steel material having a predetermined composition may be drawn to a predetermined diameter. The drawing process may be either a method using a hole die or a method using a roller die. In addition, when Cu plating is performed, wire drawing may be performed after Cu plating. The same applies to the second embodiment described later.

< protective gas >

The shielding gas used in the welding method of the first embodiment may contain Ar, or may be composed of only Ar. Alternatively, the catalyst may contain CO in addition to Ar₂And O₂For example, about 5 to 30 vol% of CO may be used₂Or O₂And the balance is a protective gas for Ar. In addition, the protective gas may contain N as an inevitable impurity₂、H₂And the like.

Here, the higher the content ratio of Ar in the shield gas, the smaller the amount of slag, and therefore, the higher the content ratio of Ar in the shield gas is desired. From this viewpoint, the content ratio of Ar is preferably 70 vol% or more, and more preferably 80 vol% or more. On the other hand, as described above, the protective gas may be composed of only Ar (that is, the content of Ar may be 100 vol%), but for example, the content of Ar may be 70 vol% or less. The same applies to the second embodiment described later.

< frequency of advance and retreat direction of welding wire >

In the welding method according to the first embodiment, when the feeding of the wire in the advancing and retreating direction is controlled, the frequency of the advancing and retreating direction of the wire is controlled to be 35Hz or more and 160Hz or less.

As a result of extensive studies, the present inventors have found that when the natural frequency of molten metal is about several tens Hz and the frequency of the wire in the forward/backward direction is controlled to be within an appropriate range so as to match the natural frequency of the molten pool, the vibration of the molten pool surface becomes optimum, the flow of molten metal on the molten pool surface changes so as to wind up the slag, and the slag cohesiveness can be improved. When the frequency of the wire in the advancing/retreating direction is less than 35Hz, short-circuiting occurs frequently during the peak current period, regular droplet transfer cannot be performed, the molten pool is disturbed by vibration, and the frequency of the wire in the advancing/retreating direction is 35Hz or more, preferably 45Hz or more, and more preferably 70Hz or more in order to obtain good slag cohesion. On the other hand, if the frequency of the wire in the advancing/retreating direction is higher than 160Hz, the effect of pressing the melt pool by the arc in the peak period is reduced, and sufficient melt pool amplitude cannot be obtained, and good slag cohesiveness cannot be obtained, so the frequency of the wire in the advancing/retreating direction is 160Hz or less, preferably 150Hz or less, more preferably 130Hz or less, and still more preferably 110Hz or less.

< parent material >

In the welding method according to the first embodiment, the base material to be welded may be a steel sheet, and the composition, thickness, and the like of the steel sheet are not particularly limited, but for example, a thin steel sheet having a thickness of 0.6mm or more and 5.0mm or less may be applied. The steel type may be, for example, mild steel, or high tensile steel of 590MPa class. The surface of the base material may be subjected to various plating treatments such as zinc plating and aluminum plating. The same applies to the second embodiment described later.

< welding conditions >

In the welding method according to the first embodiment, the welding conditions such as the welding current, the welding voltage, the welding speed, and the welding posture are not particularly limited, and may be appropriately adjusted within a range in which the arc welding method is applicable.

Here, the average value of the welding current is, for example, 80A or more and 350A or less, and preferably 100A or more and 300A or less. The welding speed is, for example, 60cm/min or more. According to the welding method of the first embodiment, welding can be performed with good slag cohesion under these welding conditions.

[ second embodiment ]

An arc welding method according to a second embodiment of the present invention (hereinafter, also referred to as a welding method of the second embodiment) is an arc welding method for performing arc welding on a steel sheet by a pulse control method, wherein welding is performed using a wire containing C and Si in mass% and a gas containing Ar, with a voltage pulse frequency of 50Hz or more and 200Hz or less and a voltage pulse width of 1.5ms or more and 10ms or less: 0.2% or more and 1.1% or less, Mn: 0.2% or more and 1.4% or less, and S: 0.010% to 0.050%, and the balance of Fe and inevitable impurities.

< solder wire >

The contents of the respective elements of the welding wire used in the welding method of the second embodiment and appropriate ranges thereof are as follows. The reason for limiting the numerical value is the same as that of the first embodiment.

(C)

Lower limit: more than 0%, preferably 0.02% by mass or more, more preferably 0.04% by mass or more

Upper limit: preferably 0.15 mass% or less, more preferably 0.10 mass% or less

(Si)

Lower limit: 0.2 mass% or more, preferably 0.3 mass% or more, and more preferably 0.5 mass% or more

Upper limit: 1.1% by mass or less, preferably 1.0% by mass or less, more preferably 0.9% by mass or less (Mn)

Upper limit: 1.4% by mass or less, preferably 1.3% by mass or less, more preferably 1.1% by mass or less (S)

Lower limit: 0.010 mass% or more, preferably 0.020 mass% or more

Upper limit: 0.050% by mass or less, preferably 0.040% by mass or less

The balance of the wire of the second embodiment is made up of Fe and unavoidable impurities, and the unavoidable impurities include Ti, P, Cr, Ni, N, O, and the like, and are allowed to be contained within a range not to impair the effects of the present invention.

In addition, in the welding wire of the second embodiment, at least one of Al, Mo, and Cu may be added in addition to the above chemical components, and the appropriate range of the addition amount and the reason thereof are the same as those of the first embodiment.

< pulse control Condition >

Next, pulse control conditions in the welding method according to the second embodiment will be described.

(voltage pulse frequency: 50 Hz-200 Hz inclusive)

(voltage pulse width: 1.5ms or more and 10ms or less)

In the welding method according to the second embodiment, when arc welding is performed by the pulse control method, pulses are controlled as follows: the voltage pulse frequency (hereinafter, also simply referred to as pulse frequency) is set to 50Hz to 200Hz, and the voltage pulse width (hereinafter, also simply referred to as pulse width) is set to 1.5ms to 10 ms.

As a result of intensive studies, the present inventors have found that when the natural frequency of molten metal is about several tens Hz and the frequency and width of pulses are controlled to be in appropriate ranges in accordance with the natural frequency of droplets, the vibration of the molten pool becomes optimum, and the flow of molten metal on the surface of the molten pool can be changed so as to be entrained in the slag, thereby improving the slag cohesiveness.

If the pulse frequency is higher than 200Hz and/or the pulse width is lower than 1.5ms, the effect of pushing the molten pool from the arc during the peak period is reduced, and a sufficient amplitude of the molten pool cannot be obtained, making it difficult to obtain good slag cohesion. Therefore, the pulse frequency is 200Hz or less, and the pulse width is 1.5ms or more. The pulse frequency is preferably 180Hz or less, more preferably 150Hz or less. The pulse width is preferably 3ms or more, and more preferably 5ms or more.

On the other hand, if the pulse frequency is less than 50Hz and/or the pulse width is greater than 10ms, the peak period becomes long, and the droplet formation becomes excessively large, so that the droplet transition becomes unstable, and as a result, the vibration of the molten pool is disturbed, and it is difficult to obtain good slag cohesiveness. In addition, spatter is liable to occur, and the bead appearance is deteriorated. Therefore, the pulse frequency is 50Hz or more and the pulse width is 10ms or less. The pulse frequency is preferably 55Hz or higher, and more preferably 60Hz or higher. The pulse width is preferably 9ms or less, and more preferably 8ms or less.

In the welding method according to the second embodiment, it is preferable that the pulse current during welding is controlled as follows.

(Peak Current: 380A or more and 490A or less)

During peak current, the molten pool is pressed by the arc force while the droplet is formed. Here, in the welding method according to the second embodiment, the peak current is not particularly limited, but is preferably 380A or more and 490A or less from the viewpoint of the following. That is, when the peak current is less than 380A, there is a possibility that a sufficient arc force for pressing the molten pool cannot be obtained. Therefore, the peak current is preferably 380A or more, more preferably 400A or more, and further preferably 410A or more.

On the other hand, if the peak current is higher than 490A, the droplet formation becomes too large, and the droplet is irregularly short-circuited to the melt pool, and there is a possibility that the melt pool cannot be regularly vibrated. Further, the arc force is too large, and the convection flow in which the slag is pushed backward with respect to the welding traveling direction may become too strong. As a result, the aggregation of slag may be inhibited. Therefore, the peak current is preferably 490A or less, more preferably 480A or less, and still more preferably 460A or less.

(base current: 80A or more and 180A or less)

During the base current, the droplet formed by the peak current is easily detached by reducing the arc force. Here, in the welding method according to the second embodiment, the base current is not particularly limited, but is preferably 80A or more and 180A or less from the viewpoint of the following. That is, when the base current is less than 80A, the range of the operating current may be significantly limited. Therefore, the base current is preferably 80A or more, more preferably 90A or more, and further preferably 100A or more.

On the other hand, if the base current is higher than 180A, the linear energy becomes too large, and burnthrough may easily occur when welding thin plates. Therefore, the base current is preferably 180A or less, more preferably 160A or less, and still more preferably 150A or less.

(duty ratio: 0.2 to 0.6)

In the welding method according to the second embodiment, the duty ratio of the pulse current is not particularly limited, but is preferably 0.2 to 0.6 from the viewpoint of the following. That is, if the duty ratio is less than 0.2, the peak current period is too short compared to the base current period, and the effect of pressing the molten pool by the arc cannot be sufficiently obtained, and the molten pool cannot be sufficiently vibrated, and as a result, the slag coagulation effect may be reduced. Therefore, the duty ratio of the pulse current is preferably 0.2 or more, and more preferably 0.3 or more.

On the other hand, if the duty ratio is higher than 0.6, short-circuiting frequently occurs during the peak current period, spatters frequently occur, and the vibration of the molten pool tends to be irregular, and as a result, the slag coagulation effect may be reduced. Therefore, the duty ratio of the pulse current is preferably 0.6 or less, and more preferably 0.5 or less.

In the welding method according to the second embodiment, the average current of the pulse current is not particularly limited, and may be appropriately determined according to appropriate ranges of the peak current, the base current, and the duty ratio. The average current as the pulse current is, for example, 250A or more and 350A or less.

< welding conditions >

In the welding method according to the second embodiment, the welding conditions such as the welding speed and the welding posture are not particularly limited, and may be appropriately adjusted within a range applicable to the arc welding method.

The welding speed is, for example, 70cm/min or more. According to the welding method of the second embodiment, even if the welding speed is increased, welding can be performed with good slag cohesion.

Examples

The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples, and can be modified and practiced within a range that can meet the gist of the present invention, and all of these are included in the technical scope of the present invention.

Hereinafter, the first embodiment will be described with reference to examples and comparative examples.

Using a wire having a diameter of 1.2mm and having a composition shown in tables 1 and 2, the frequency in the forward and backward direction of the wire was controlled to be the frequency shown in tables 1 and 2, and welding was performed under the following conditions.

(1) Steel plate

A steel plate having a length of 200mm, a width of 60mm and a thickness of 3.2mm was used. Also, the steel grade of the steel sheet is SPHC 590.

(2) Welding posture

Horizontal lap fillet welding is performed.

(3) Protective gas

In examples 1 to 28 of Table 1 and examples 30 to 59 of Table 2, Ar +20 vol% CO was used as a shielding gas₂。

In example 29 of table 1 and example 60 of table 2, 100 vol% CO was used as the shielding gas₂。

(4) Welding current and welding voltage

With a welding current: 240A, welding voltage: and (8) carrying out welding at 18V.

(5) Welding speed and welding length

The welding speed was 100 cm/min. In addition, the welding length: the welding is performed to 150 mm.

In tables 1 and 2 and table 3 described later, the "wire component (% by mass)" represents the component amount (% by mass) in the total mass of the wire. Incidentally, "-" means that the content is less than the detection limit. In addition, the Cu content shown in tables 2 and 3 contains a Cu plated portion. The balance being Fe and inevitable impurities.

(evaluation of slag cohesion)

The slag on the surface of the weld bead was visually observed over a welding length of 150mm, collected, and evaluated according to the following criteria. Incidentally, X is a non-conformity and X is a non-conformity.

Very good: more than 90% by weight of the total amount of slag is present (condensed) in the vicinity of the crater portion.

O: in the total amount of slag, at least 50% by weight and less than 90% by weight of slag is present (condensed) in the vicinity of the crater portion.

X: only less than 50% by weight of the slag is present (condensed) in the vicinity of the crater portion.

[ Table 1]

[ Table 2]

Of examples 1 to 60, examples 1 to 20 and examples 30 to 51 are examples, and examples 21 to 29 and examples 52 to 60 are comparative examples. As shown in tables 1 and 2, examples 1 to 20 and examples 30 to 51 exhibited good slag cohesiveness.

In examples 21 and 52, the S content in the wire was too small, and in examples 22 and 53, the S content in the wire was too large, so that the slag cohesion was deteriorated.

In examples 23 and 54, the frequency in the wire advancing and retreating direction was too high, and in examples 24 and 55, the frequency in the wire advancing and retreating direction was too low, and therefore, the slag cohesiveness was deteriorated.

In examples 25 and 56, the Si content in the wire was too small, and in examples 26 and 57, the Si content in the wire was too large, so that the slag cohesion was deteriorated.

In examples 27 and 58, the Mn content in the wire was too small, and in examples 28 and 59, the Mn content in the wire was too large, so that the slag cohesion was deteriorated.

In examples 29 and 60, 100% CO containing no Ar was used as the shielding gas₂The slag cohesiveness deteriorates due to the gas.

Next, a second embodiment will be described below by way of examples and comparative examples.

Arc welding was performed using a wire having a diameter of 1.2mm and a composition shown in table 3 under the following conditions while controlling the pulse.

(1) Steel plate

(2) Welding posture

Horizontal lap fillet welding is performed.

(3) Protective gas

In examples 61 to 90 and 92 to 93 of Table 3, Ar +20 vol% CO was used as a shielding gas₂。

In example 91 of Table 3, 100 vol% CO was used as the shielding gas₂。

(4) Pulse control conditions

The pulse frequency (Hz), pulse width (ms), peak current (a), base current (a), and duty ratio were controlled according to the conditions shown in table 3, and welding was performed.

(5) Welding speed and welding length

(evaluation of slag cohesion)

The proportion (wt%) of slag existing (agglomerated) in the vicinity of the crater portion was determined by visually observing slag on the surface of the weld bead over a welding length of 150mm, collecting the slag on the surface, and calculating the total amount of slag, and is shown in the column "slag agglomeration proportion (wt%)" in table 3. Here, if the proportion of slag present (agglomerated) in the vicinity of the crater portion is 60 wt% or more, the slag agglomeration performance can be evaluated as good. In the case where the proportion of slag existing (agglomerated) in the vicinity of the crater portion is less than 60% by weight and the slag cohesion is poor, the results are described as "x" in the column "slag agglomeration proportion (% by weight)" in table 3, and the description of the proportion is omitted.

(evaluation of bead appearance)

The appearance of the weld bead obtained in each example was evaluated by the following criteria.

Very good: smooth bead appearance with less surface irregularities

O: no undercut and good appearance of weld bead

X: uneven bead boundary, surface unevenness, and poor bead appearance

[ Table 3]

Of examples 61 to 93, examples 61 to 82 are examples, and examples 83 to 93 are comparative examples. As shown in Table 3, in examples 61 to 82, good slag cohesiveness was obtained. In addition, the bead appearance was also good.

In example 83, the S content in the wire was too small, and in example 84, the S content in the wire was too large, so that the slag cohesion was deteriorated.

In example 85, the pulse frequency was too high, and therefore, the slag cohesiveness was deteriorated. In example 86, the pulse frequency was too low, and therefore, the slag cohesiveness was deteriorated and the bead appearance was also poor.

In example 87, since the Si content in the wire was too small, slag cohesion was deteriorated and bead appearance was also poor. In example 88, since the Si content in the wire was too high, the slag cohesiveness was deteriorated.

In example 89, the Mn content in the wire was too small, and in example 90, the Mn content in the wire was too large, so that the slag cohesiveness was deteriorated.

In example 91, 100% CO containing no Ar was used as the shielding gas₂The slag cohesiveness deteriorates due to the gas.

In example 92, since the pulse width was too small, the slag cohesiveness was deteriorated. In example 93, the pulse width was too large, and the Mn content in the wire was too large, so that the slag cohesiveness was deteriorated and the bead appearance was also poor.

The present invention has been described in detail with reference to the specific embodiments, but it is apparent to the practitioner that various changes and modifications can be made without departing from the spirit and scope of the invention. Also, the present application is based on japanese patent application filed on 3/2/2017 (japanese patent application 2017-. All references cited herein are incorporated by reference in their entirety.

Claims

1. An arc welding method for welding a steel plate by controlling the feed of a wire in the forward and backward direction, wherein welding is performed by using a wire and an Ar-containing gas so that the frequency of the forward and backward direction of the wire is 35Hz or more but 160Hz or less,

the welding wire contains C and contains in mass%

Si: 0.2% or more but 1.3% or less,

Mn: 0.2% or more but 1.5% or less, and

s: 0.01% or more but 0.05% or less,

the balance being Fe and unavoidable impurities.

2. The arc welding method of claim 1, wherein the wire further contains at least one of the following elements in mass%:

al: 0.1% or more but 0.5% or less,

Mo: 0.1% or more but 2.0% or less,

Ti: less than 0.3 percent of,

Cu: less than 0.4 percent.

3. The arc welding method of claim 2, wherein the contents of S and Al in the wire satisfy 0.3. ltoreq. S x 10+ Al. ltoreq.0.7.

4. The arc welding method according to claim 1, wherein a plate thickness of the steel plate is 0.6mm or more and 5mm or less.

5. The arc welding method according to claim 1, wherein the welding is performed such that a frequency of a forward and backward direction of the wire is 45Hz or more but 130Hz or less.

6. The arc welding method according to claim 5, wherein the welding is performed such that the frequency of the advancing and retreating direction of the wire is 70Hz or higher but 110Hz or lower.

7. The arc welding method according to any one of claims 1 to 6, wherein the welding is performed at a welding speed of 60cm/min or more with an average value of the welding current of 80A or more and 350A or less.

8. An arc welding method for performing arc welding on a steel plate by a pulse control method, wherein welding is performed by using a wire and an Ar-containing gas, with a voltage pulse frequency of 50Hz or more but 200Hz or less, a voltage pulse width of 1.5ms or more but 10ms or less, and a duty ratio of a pulse current of 0.2 or more but 0.6 or less,

the welding wire contains C and is characterized by containing

Si: 0.2% or more but 1.1% or less,

Mn: 0.2% or more but 1.4% or less, and

s: 0.010% or more but 0.050% or less,

the balance being Fe and unavoidable impurities.

9. The arc welding method of claim 8, wherein the wire further comprises at least one of the following elements in mass%:

al: 0.1% or more but 0.5% or less,

Mo: 0.1% or more but 2.0% or less,

Cu: less than 0.4 percent.

10. The arc welding method according to claim 8, wherein the welding is performed with a peak current of 380A or more and 490A or less.

11. The arc welding method according to claim 8, wherein welding is performed with a base current of 80A or more and 180A or less.

12. The arc welding method according to any one of claims 8 to 11, wherein a plate thickness of the steel plate is 0.6mm or more and 5mm or less.