KR100800747B1 - Method of gas shielded arc welding and wire for gas shielded arc welding - Google Patents

Abstract

In the gas shielded arc welding method of the present invention, C, 0.12% by mass or less based on the total mass of the wire; Si 0.6-1.5 mass%; Mn 0.8-1.8 mass%; S 0.007-0.040 mass%; 0.03 to 0.18 mass% of Ti; And using Fe as the remainder and the unavoidable impurities, using a wire having a diameter of 0.9 to 1.6 mm, and using a wire extension length of 20 to 25 mm, a welding current of 190 to 350 A, and a welding voltage of 22 to 39 V to the anode. Welded downward using one DC reverse polarity, each containing 37% by mass or more of SiO ₂ , 46% by mass or less of MnO, and 12% by mass or less of TiO ₂ , represented by Equation 1 Slags with values greater than 0.50 are generated.

According to this welding method, the slag is easily peeled even when the steel material is at a high temperature of 200 ° C to 300 ° C.

Description

METHOD OF GAS SHIELDED ARC WELDING AND WIRE FOR GAS SHIELDED ARC WELDING}

The present invention relates to a method for gas shielded arc welding of steel material made of mild steel or high tensile strength steel of 490 to 590 MPa using carbon dioxide or a mixed gas of argon and carbon dioxide as a shielding gas and a wire for gas shielded arc welding. .

In gas shielded arc welding using carbon dioxide or a mixed gas of argon (Ar) and carbon dioxide as the shielding gas, oxygen contained in the shield atmosphere is dissociated by arc heating and then reacts with an alloy component contained in the molten metal to react with the metal oxide. Create This metal oxide is deposited and condensed on the surface of the molten pool to form slag. The amount of slag generated in gas shielded arc welding is influenced by the wire component, the type of shielding gas, the welding state, and the like. For example, more slag is produced when carbon dioxide is used as the shielding gas, and the amount of slag produced decreases when the content of an inert gas such as Ar increases in the shielding gas. In a welding method in which layers are stacked, such as multilayer stack welding, the amount of slag accumulates to cause failure of arc generation, deterioration of arc stability and occurrence of internal defects. Therefore, the slag formed in excess should be properly removed.

Generally, slag is removed using a wire brush, hammer, air hammer using air pressure, and the like. When the slag that is difficult to peel off is removed, a problem arises that the equipment used becomes large, increasing the burden on the operator and the working time. If the temperature of the steel being the material to be welded is low, the slag is easily removed. On the other hand, slag removal tends to be difficult when the steel is a thick plate or when the interpass temperature during welding is high. Therefore, a welding wire and a welding method excellent in the peelability of slag are pursued even when slag is removed in a state where the temperature of the steel is high.

Conventionally, in welding thick plates, high efficiency welding by relatively high current has been mainly used. In this application, Ti-added welding wires are used to stabilize the arc during high current welding. When such a Ti-added wire is used, droplet transfer is stabilized and generation of spatters is suppressed. However, not only does the amount of slag increase, but also the slag becomes hard, resulting in a problem that the slag peeling operation becomes difficult. For this reason, there has been a great demand for improving the peelability of slag formed by the Ti-added wire in order to reduce the burden of slag peeling work in the welding work surface.

In order to reduce the production of welding slag and improve the slag peelability without reducing the welding workability and the mechanical performance of the weld metal, the present inventors are suitable when using CO ₂ gas as the shielding gas, and 0.03 to 0.10 Mass% C, 0.60 to 1.20 mass% Si, 1.20 to 1.60 mass% Mn, 0.010 to 0.025 mass% S, 0.08 to 0.20 mass% Ti, 0.020 to 0.100 mass% Cr and Fe as remainder It contains an unavoidable impurity, and is calculated by the formula A = [Si] / [Mn], where [Si] is the content (mass%) of Si and [Mn] is the content (mass%) of Mn. A gas shielded arc welding wire having an A value of 0.40 to 0.90 is proposed (see Japanese Patent Application Laid-Open (JP-A) No. 320178/1999).

In addition, in order to improve the peelability of slag generated during carbon dioxide arc welding and to reduce the amount of spatters, 0.1% by mass or less of C, 0.5 to 1.0% by mass of Si, 1.2 to 2.0% by mass of Mn, and 0.06 to 0.15% by mass Gas shield arc welding containing% Ti, 0.015 to 0.15% by mass Bi, 0.0020 to 0.0040% by mass Se, 0.02 to 0.03% by mass S, 0.010 to 0.025% by mass O, and Fe as the remainder and unavoidable impurities A wire for this purpose is disclosed (see Japanese Patent Laid-Open No. 52193/1997).

However, the welding wires described in the above-described patent documents JP-A-320178 / 1999 and JP-A-52193 / 1997 have excellent peelability of slag when the temperature of the steel is sufficiently low, but immediately after welding, that is, steel Has a problem that peeling of slag is difficult under conditions of a high temperature of about 200 to 300 ° C.

In order to solve the above problems, an object of the present invention is to provide a gas shielded arc welding method and a gas shielded arc welding method in which slag can be easily peeled off even under a high temperature of about 200 to 300 ° C. .

The first aspect of the present invention is C 0.12% by mass or less based on the total mass of the wire; Si 0.6-1.5 mass%; Mn 0.8-1.8 mass%; S 0.007-0.040 mass%; And a wire containing 0.03 to 0.18 mass% of Ti, having a diameter of 0.9 to 1.6 mm, using carbon dioxide or a mixed gas of argon and carbon dioxide as the shielding gas, and having a wire extension length of 20 to 25 mm and a welding current. Is welded downward to weld steel made of mild steel or 490 to 590 MPa class high tensile strength steel using DC reverse polarity with wire as the anode under conditions of 190 to 350A and welding voltage of 22 to 39V. It relates to a gas shielded arc welding method containing not less than mass% SiO ₂ , not more than 46 mass% MnO and not more than 12 mass% TiO ₂ , wherein slag with an A value of 0.50 or more is produced by Equation 1 below:

Equation 1

Where

The content of SiO ₂ (% by mass) is expressed as [SiO _2],

Content (mass%) of MnO is represented as [MnO],

The content of TiO ₂ (% by mass) is expressed as [TiO _2].

In this method, slags each containing 37% by mass or more of SiO ₂ , 46% by mass or less of MnO, and 12% by mass or less of TiO ₂ and having an A value of 0.50 or more represented by Equation 1 above are formed. Can be. Slag having such a composition range is excellent in peelability, the slag can be easily peeled off even at a high temperature of about 200 to 300 ℃ steel materials.

The effect of the wire used in the gas shielded arc welding method is not lost even if the wire further contains Zr or Al, or both. In this case, the total content of Ti, Zr and Al is preferably adjusted to 0.25% by mass or less based on the total mass of the wire. When Zr is contained, the A value is obtained by the following equation (2):

Further, the wire used in the gas shielded arc welding method may contain at least one element selected from the group consisting of Ni, Cr, and Mo. In this case, the total content of Ni, Cr and Mo is preferably adjusted to 0.60 mass% or less based on the total mass of the wire.

The wire for gas shielded arc welding of the present invention suitable as a wire for use in gas shielded arc welding of mild steel or high strength steel of 490 to 590 MPa class using carbon dioxide or a mixed gas of argon and carbon dioxide is a shielding gas. Of the wire using DC reverse polarity using the carbon dioxide, or a mixed gas of argon and carbon dioxide, with the wire as the anode under the condition that the wire extension length is 20 to 25 mm, the welding current is 190 to 350 A, and the welding voltage is 22 to 39 V. C 0.12 mass% or less, based on the total mass; Si 0.6-1.5 mass%; Mn 0.8-1.8 mass%; S 0.007-0.040 mass%; And 0.03 to 0.18 mass% of Ti, and when welding the target steel with a wire having a diameter of 0.9 to 1.6 mm, each of 37 mass% or more of SiO ₂ , 46 mass% or less of MnO, and 12 masses in terms of oxide and containing TiO _2% or less, the content of SiO ₂ (% by mass) is displayed as [SiO _2], and the content (% by weight) of MnO is displayed as [MnO] the content (% by weight) of TiO ₂ is Generating slag having an A value of 0.50 or more represented by the equation (1) expressed as [TiO ₂ ].

Another embodiment of the present invention is C 0.12% by mass or less based on the total mass of the wire; Si 0.6-1.5 mass%; Mn 0.8-1.8 mass%; S 0.007-0.040 mass%; And a wire containing 0.03 to 0.18 mass% of Ti, having a diameter of 0.9 to 1.6 mm, using carbon dioxide or a mixed gas of argon and carbon dioxide as the shielding gas, having a wire extension length of 20 mm and a welding current of 320 A. The present invention relates to a gas shielded arc welding wire which is carried out by downward welding of steel made of mild steel or high strength steel of 490 to 590 MPa using DC reverse polarity with the anode as the wire under a welding voltage of 35 V. A slag containing 37% by mass or more of SiO ₂ , 46% by mass or less of MnO, and 12% by mass or less of TiO ₂ and having an A value of 0.50 or more represented by the following Equation 1 is generated:

Equation 1

Where

The content of SiO ₂ (% by mass) is expressed as [SiO _2], the content (% by weight) of MnO are designated as [MnO], the content of TiO ₂ (% by mass) is expressed as [TiO _2].

Each of the wires for gas shielded arc welding does not lose the effect of the wires even if Zr or Al, or both are additionally contained. In this case, the total content of Ti, Zr and Al is preferably adjusted to 0.25 mass or less based on the total mass of the wire. When Zr is contained, the A value is obtained by the above equation (2).

In addition, the wire for gas shielded arc welding may contain at least one element selected from the group consisting of Ni, Cr and Mo. In this case, the total content of Ni, Cr, and Mo is preferably adjusted to 0.6% by mass or less based on the total mass of the wire.

The wire used in the gas shielded arc welding method according to an embodiment of the present invention is described in detail below. In order to solve the above problem, the present inventors conducted an intensive study on slag peelability focusing on the chemical composition of slag. As a result, the inventors have found that the chemical composition of slag affects slag peelability and plays an important role in controlling slag peelability. Based on this finding, the present inventors have completed the present invention by optimizing not only the slag component which makes the peelability excellent but also the wire component which forms such slag under the welding conditions described later.

That is, the wire used in the gas shielded arc welding method of the present invention is used for gas shielded arc welding of steel made of mild steel or high strength steel of 490 to 590 MPa class using carbon dioxide or a mixed gas of argon and carbon dioxide as a shielding gas. As a wire for satisfying at least the following composition; C 0.12 mass% or less; Si 0.6-1.5 mass%; Mn 0.8-1.8 mass%; S 0.007-0.040 mass%; 0.03 to 0.18 mass% of Ti; And Fe and inevitable impurities as remainder. In addition to each of the above components, the wire also further contains at least one element selected from the group consisting of Zr, Al, Ni, Cr and Mo. In this case, the total content of Ti, Zr and Al is preferably adjusted to 0.25 mass% or less, and the total content of Ni, Cr and Mo is preferably adjusted to 0.60 mass% or less.

The reason for adding each component to the wire for use in the gas shielded arc welding method and the reason for limiting the value of each component will then be described.

1.C: 0.12 mass% or less

Carbon (C) not only has an effect as a deoxidizing element in the molten metal, but also is an effective element for securing the strength of the weld metal. However, if the content of C exceeds 0.12% by mass based on the total mass of the wire, the amount of spatter increases during welding, deteriorating welding workability. Therefore, content of C is set to 0.12 mass% or less based on the gross mass of a wire.

2. Si: 0.6-1.5 mass%

Silicon (Si) is an excellent deoxidation element because it is easy to oxidize. Although Si has the effect of substantially reducing oxygen in the weld metal, Si is an element that acts as a major component of slag in combination with oxygen. In addition, Si improves bead shape and compatibility between the bead and the parent metal, affects the distribution state of the slag, and has an effect of easily peeling the slag from the weld metal. However, when the content of Si is less than 0.6% by mass based on the total mass of the wire, the deoxidation effect of Si is reduced and internal defects such as blowholes are likely to occur. On the other hand, when content of Si exceeds 1.50 mass% based on the gross mass of a wire, the mechanical strength, especially toughness of a weld metal will fall. Therefore, Si content is set to 0.6 mass%-1.5 mass% based on the total mass of a wire.

3. Mn: 0.8-1.8 mass%

Like Si, manganese (Mn) is not only an element that promotes deoxidation, but also an element that acts as a major component of slag in combination with oxygen. Mn has the effect of greatly improving the microstructure of the molten metal and improving the strength and toughness of the weld metal. However, when the Mn content is less than 0.8% by mass based on the total mass of the wire, the deoxidation effect of Si decreases, internal defects such as pores occur, and the toughness of the weld metal is reduced. On the other hand, when content of Mn exceeds 1.8 mass% based on the total mass of a wire, slag becomes hard and slag peelability deteriorates. Therefore, content of Mn is set to 0.8-1.8 mass% based on the gross mass of a wire.

4.S: 0.007-0.040 mass%

Sulfur (S) has the effect of promoting slag aggregation by acting as a surface activator during welding to reduce the surface tension of the molten droplets, make the molten droplets smaller, and at the same time reduce the surface energy of the molten metal. In addition, S not only weakens the interfacial bond between the slag and the weld metal after aggregation, but also has an effect of embrittling the slag to improve the peelability of the slag. On the other hand, when S is added to the wire in an excessive amount, stable transfer of molten droplets is suppressed in high current welding using carbon dioxide, and the amount of spatter generated increases. In addition, when the slag aggregates excessively, it has an adverse effect on the peelability of the slag, so that the content of S in the wire needs to be adjusted to an appropriate range. In particular, when the content of S is less than 0.007% by mass based on the total mass of the wire, sufficient promotion of the peelability of the slag cannot be achieved. On the other hand, when the content of S exceeds 0.04 mass% based on the total mass of the wire, the arc stability is reduced, and the amount of spatter generated is increased. Therefore, content of S is set to 0.007%-0.040 mass% based on the total mass of a wire.

5. Ti: 0.03% to 0.18% by mass

Titanium (Ti) is not only an element that strongly promotes deoxidation, but also a major component of slag. Ti is added to the wire used in high current welding using carbon dioxide because Ti has the effect of stabilizing molten droplet transfer by enhancing the surface tension and viscosity of the molten droplet surface. However, when Ti is used, the slag becomes hard and hard, and the amount of slag increases, resulting in deterioration of slag peelability. In particular, when the content of Ti is less than 0.03% by mass based on the total mass of the wire, the arc becomes unstable and weld deposition as in the case of welding of thick plates, multilayer stack welding, etc., which are the main targets of the present invention. When a relatively large current is used in a large amount welding method, the amount of spatter generated is greatly increased. On the other hand, when the content of Ti exceeds 0.18% by mass based on the total mass of the wire, the slag becomes hard and hard, and since the amount of slag increases, the peelability of the slag is greatly deteriorated. Therefore, the content of Ti is set to 0.03 to 0.18 mass% based on the total mass of the wire.

The wire used in the gas shielded arc welding method of the present invention is composed of zirconium (Zr), aluminum (Al), nickel (Ni), chromium (Cr), and molybdenum (Mo) as necessary in addition to the above-mentioned components. It may further contain one or more elements selected from the group. Each of Zr and Al acts as a strong deoxidation material and improves the cleanability and mechanical properties of the weld metal. In addition, Ni, Cr and Mo increase the hardness of the weld metal and thus improve the mechanical properties of the weld metal. It is to be noted that Ti, Zr and Al are the main components of slag, and when the total content of Ti, Zr and Al exceeds 0.25%, the slag is excessively formed, resulting in inferior slag peelability and arc instability. In addition, when the total content of Ni, Cr, and Mo exceeds 0.60%, the strength of the weld metal is too large for the strength of the parent metal, which is not preferable. Therefore, when Zr or Al, or both are added, it is preferable to set the total content of Ti, Zr, and Al to 0.25 mass% or less. When Ni and Cr or Mo or both are added, the total content of Ni, Cr and Mo is preferably set to 0.60 mass% or less.

Unavoidable impurities contained in the wire used in the gas shielded arc welding method of the present invention include P, Cu, Nb, V, W, and the like. Cu is sometimes contained as copper plating of the wire, but does not affect the slag peelability, which is the effect of the present invention.

Welding conditions in the gas shielded arc welding method of the present invention are described below. The wire of the present invention has a diameter of 0.9 to 1.6 mm and is used for gas shielded arc welding of steel made of mild steel or high tensile strength steel of 490 to 590 MPa using carbon dioxide or a mixed gas of carbon dioxide and Ar as the shielding gas. Welding is carried out in a downward position using DC reverse polarity with the wire as the anode under the conditions of a welding current of 190 to 350 A, a welding voltage of 22 to 39 V, and a wire extension length of 20 to 25 mm.

In addition, each in terms of oxide, and contains at least 37 mass% SiO _2, 46% by mass or less of MnO and TiO ₂ of less than 12% by mass, the content of SiO ₂ (% by mass) is displayed as [SiO _2], MnO The slag whose content (mass%) is represented as [MnO], and whose A value represented by the formula (1) in which the content of TiO ₂ (mass%) is represented as [TiO ₂ ], is formed during welding. When Zr or Al or both are further contained, it should be noted that the total content of Ti, Zr and Al is 0.25 mass% or less. At this time, when Zr is contained, the A value is obtained by the above expression (2).

Content of the slag component described in this application is "oxide conversion content", melt | dissolves the slag calculated by welding, measures the content of the metal component of the oxide which comprises a slag by the method similar to a wet analysis, It is the value calculated | required by converting content into oxide content, respectively. At this time, it is necessary to know the valence of each metal element, but in reality it is difficult to obtain the exact valence of each metal element. In order to conveniently measure the oxide content, in the present invention, Si is the only SiO ₂ , Mn is MnO, Fe is FeO, Ti is TiO ₂ , Zr is ZrO ₂ , Al is Al ₂ O ₃ , Cr is converted into Cr ₂ O ₃ , S is converted into S (monomer), and Bi is converted into Bi ₂ O ₃ . It should be noted that simple and well calibrated assay methods such as fluorescence assays may also be used in place of wet assay methods.

The reason for limiting each component value of the slag generated in the gas shielded arc welding method of the present invention is explained below.

6. SiO ₂ : 37 mass% or more

Slags containing an appropriate amount of SiO ₂ are susceptible to cracking as a result of vitrification and less likely to swell because of their tendency to aggregate. Therefore, SiO ₂ has the effect of improving slag peelability. However, when the content of SiO ₂ is less than 37% by mass based on the total mass of slag, the slag is hard and thin and distributed over a wide range, making it difficult to peel the slag.

7.MnO: 46 mass% or less

MnO is a component that not only makes the slag harder but also makes the slag peeling difficult by making the bond between the slag and the weld metal stronger. In particular, when the MnO content exceeds 46 mass% based on the total mass of the slag, the slag becomes hard, furthermore, sticking to the bead surface in high current welding causes deterioration of slag peelability, Peeling becomes very difficult.

8. TiO ₂ 12 mass% or less

TiO ₂ has a great influence on the content of slag and is a component that makes it difficult to peel slag by hardening the slag. Specifically, when the TiO ₂ content exceeds 12% by mass based on the total mass of the slag, the slag itself becomes hard, and the amount of slag generated increases to make the slag harder and thicker so that the slag fracture is further increased. It makes it difficult and worsens the peelability of slag.

9.A value: 0.50 or more

The hardness and fracture of the slag is affected by the component balance of the entire slag as well as the respective content of the components contained in the slag. In particular, immediately after welding, slag peelability under conditions in which the steel (parent metal) is at a high temperature of about 200 to 300 ° C is excellent when the slag is in a stable glassy state. The inventors have found that a preferred composition that meets the above conditions can be obtained by reducing TiO ₂ (ZrO ₂ when Zr is contained) and MnO and increasing SiO ₂ , which is found by Equation 1 or 2 above. Are shown. As a result of a series of in-depth studies related to the balance of slag components, the inventors have found that the slag peelability is based on SiO ₂ content (mass%) [SiO ₂ ] vs. MnO content (mass%) [MnO] and TiO ₂ content (mass%) [TiO _{It has been found} that the ratio of ₂ ], i.e., improved by setting the A value represented by Equation 1 or 2 above 0.5. When A value is less than 0.50, slag becomes hard and slag peelability deteriorates.

In the gas shielded arc welding method of the present invention, even if the steel is at a high temperature of about 200 to 300 ° C, the slag can be easily peeled off by causing the slag having the above-described composition to be formed.

It should be noted that the slag produced by the gas shielded arc welding method of the present invention contains metal particles having a Fe component or the like as a main component in addition to the above-described oxides. In the remainder, for example, some Fe is a very fine particle of metallic iron remaining in the slug. Since these components other than an oxide have a low content, they are treated as oxides in the present invention. Therefore, the slag component other than the above-mentioned components produced by the gas shielded arc welding method of the present invention, that is, the balance is almost FeO.

When carbon dioxide and a mixed gas thereof are used as the shielding gas, copper (Cu) may be plated on the surface of the welding wire at, for example, about 0.2% by mass based on the total mass of the wire. It has been proved that such Cu has no influence on the peelability of slag, and when the wire surface used in the gas shielded arc welding method of the present invention is plated with Cu, the peelability of slag is not affected. In addition, even if the wire used in the gas shielded arc welding method of the present invention does not have a Cu plating layer on its surface, excellent slag peelability can be achieved.

As described above, the gas shielded arc welding method of the present invention assumes that steel materials made of mild steel or high tensile strength steel of 490 to 590 MPa class are welded by gas shielded arc welding using carbon dioxide or a mixed gas of carbon dioxide and Ar as shielding gas. Provided is a gas shielded arc welding method using wires in a suitable wire composition range under suitable welding conditions. In addition, the slag composition is defined to meet certain conditions based on the finding that the slag composition generated during welding acts as a control factor for slag peelability. That is, in order for the slag composition to meet predetermined conditions, the range of suitable wire composition and suitable welding conditions is further limited. However, it is difficult to completely limit the range so that the slag composition satisfies a predetermined condition only by the wire composition and the welding condition. Since the basis of the present invention lies in the fact that slag peelability is enhanced by adjusting the slag composition, the method of the present invention was determined to be limited by the conditions of the wire composition, the welding conditions and the achieved slag composition. It is not particularly difficult to select conditions that satisfy the conditions of slag composition from the limited wire composition and welding conditions. This choice can be realized by simple trial and error. As a representative method, the slag composition is adjusted by increasing or decreasing the content of related elements added to the wire. For example, if the slag composition does not meet the defined range because of insufficient SiO ₂ , its adjustment is performed by gradually increasing the amount of SiO ₂ added to the wire within the defined range.

Also a gas shield arc welding wire is the subject of the present invention. The wire for gas shielded arc welding of this invention is a wire suitable for gas shielded arc welding of the steel material which consists of mild steel or high strength steel of 490-590 MPa grade using carbon dioxide or mixed gas of carbon dioxide and Ar as a shielding gas. The wire composition of the wire for gas shielded arc welding of the present invention is optimized for the applications described above. Specifically, the range of wire composition is the same as defined in the gas shielded arc welding method of the present invention. The diameter of the wire is as defined in the gas shielded arc welding method of the present invention; That is, 0.9 to 1.6 mm. In addition, as a requirement for the wire to allow welding with excellent slag peelability, the wire is used as the anode under arbitrary conditions with a wire extension length of 20 to 25 mm, a welding current of 190 to 350 A, and a welding voltage of 22 to 39 V. When performing downward welding using DC reverse polarity, each contains 37 mass% or more of SiO ₂ , 46 mass% or less of MnO, and 12 mass% or less of TiO ₂ in terms of oxide, and the content of SiO ₂ (mass% ) Is expressed as [SiO ₂ ], the content (mass%) of MnO is expressed as [MnO], and the value of A represented by Equation 1 in which the content of TiO ₂ (mass%) is represented by [TiO ₂ ]. You have to create slag that is 0.50 or more. As another requirement for a wire that allows welding with good slag peelability, downward welding is performed using DC reverse polarity with the wire as the anode under conditions of 20 mm wire extension length, 320 A welding current and 35 V welding voltage. when performed, each in terms of oxide, and contains at least 37 mass% SiO _2, 46% by mass or less of MnO and TiO ₂ of less than 12% by mass, the content of SiO ₂ (% by mass) is displayed as [SiO _2] , The slag whose content (mass%) is represented as [MnO], and the A value represented by the formula (1) in which the content of TiO ₂ (mass%) is represented as [TiO ₂ ], should be generated. Accordingly, the wire of the present invention is a wire that is more limited in terms of the composition of the slag in which the wire of the above composition range is produced during welding under certain conditions.

The wire for gas shielded arc welding of the present invention further contains at least one of Zr and Al, similar to the wire used in the gas shielded arc welding method of the present invention, and the total content of Ti, Zr and Al is It is 0.25 mass% or less based on total mass. When Zr is contained, the A value may be a value calculated by Equation 2 above.

In addition to the components described above, the gas shielded arc welding wire of the present invention is selected from the group consisting of zirconium (Zr), aluminum (Al), nickel (Ni), chromium (Cr), and molybdenum (Mo) as necessary. It may further contain one or more elements.

Example

In the following, the effects of the examples of the present invention are explained in comparison with the effects of the comparative examples which depart from the scope of the present invention. In this embodiment, after the wire is formed, the raw materials whose respective components are adjusted to have the composition shown in Table 1 are first melted and cast in vacuum using a 150 kg vacuum induction furnace (VIF), and then perpendicular to the longitudinal axis direction by high temperature forging. The area was to have a height of 155 mm and a width of 155 mm. In addition, these regions perpendicular to the longitudinal axis direction were fabricated and hot rolled to have a height of 5.5 mm and a width of 5.5 mm. This hot rolled material was then subjected to cold wire drawing to give a diameter of 2.4 mm, Cu was plated on the wire surface, and drawn to a diameter of 1.2 mm or less. In this way, the wires described in Examples 1-11 and Comparative Examples 1-9 were formed. At this time, the Cu plating layer component of the surface of each wire is Cu and an unavoidable impurity, These total content was adjusted to 0.2 mass% based on the wire total mass. The values shown in Table 1 below indicate the content of each component based on the total mass of the wire including such a Cu plating layer.

Then, the oxide film (black film) formed on the surface of the steel sheet (SM490) having a length of 300 mm, a width of 125 mm, and a thickness of 25 mm was removed with a grinder, using carbon dioxide as the shielding gas, a welding current of 320 A, a welding voltage of 35 V, and a wire extension length. Gas shielded arc welding of 6 layers-6 passes in the downward welding position was performed using the wires of Examples 1-11 and Comparative Examples 1-9 at a downward welding position using DC reverse polarity with the wire as the anode under conditions of 20 mm. . At this time, welding was stopped in the 5-layer-5 pass and the peelability of the slag was evaluated on the bead surface of the fifth layer.

For slag peelability, the peelable slag was removed using a brush when the temperature of the steel sheet dropped to 250 ° C., and then the appearance of the beads was visually checked and photographed. From the photograph of the bead outline, the slag peeling rate, that is, the ratio (= Y / X) of the area Y (pixel number) of the area where the bead surface is visible to the total bead area X (pixel number) was measured. The result of slag peeling rate of 30% or more is considered acceptable. After completion of the 6 layer-6 pass welding, the slag on the bead surface was collected and the composition analysis of the produced slag was performed by wet analysis. The results are summarized in Table 2 below.

As shown in Table 2 above, all of the wires of Examples 1 to 11 within the scope of the present invention show a slag peeling rate greater than 30% even when the steel is in a high temperature state, and provides excellent slag peelability. However, the arc stability of the wire of Example 10 is somewhat inferior because the total content of Ti, Zr and Al exceeds 0.25% by mass. In addition, the strength of the wire of Example 11 is too large to carry out, because the total content of Ni, Cr, and Mo exceeds 0.60 mass%.

On the other hand, the slag peeling property of the wire of Comparative Example 1 in which the SiO ₂ content in the slag is smaller than the range of the present invention and the A value is smaller than the range of the present invention is due to the fact that the Si content in the wire is smaller than the range of the present invention. Reduced. The slag peelability of the wire of Comparative Example 2 is less than 30%, and its welding workability is also inferior because the content of Si in the wire is larger than the range of the present invention. The slag peelability of the wire of Comparative Example 3 was greatly reduced because the content of C in the wire exceeded the scope of the present invention, and its welding workability was lowered due to the increase in the amount of spatter. The slag peelability of the wire of Comparative Example 4 is less than 30% and pores are generated because the content of Mn in the wire is lower than the range of the present invention. Since the content of Mn in the wire exceeds the range of the present invention, the slag peelability of the wire of Comparative Example 5 in which the content of MnO in the slag exceeds the range of the present invention is greatly reduced.

The slag peeling property of the wire of the comparative example 6 was smaller than 30% because content of S in a wire exceeds the range of this invention. Although the slag peelability of the wire of Comparative Example 7 is greater than 50%, its workability is inferior because the content of Ti in the wire is smaller than the range of the present invention. Not only does the content of TiO _{2 in} the slag exceed the range of the present invention, but the slag peelability of the wire of Comparative Example 8 in which the A value is smaller than the range of the present invention because the content of Ti in the wire exceeds the range of the present invention. Deteriorated significantly. The slag peelability of the wire of Comparative Example 9 is inferior because of the stickiness of the slag because the content of S in the wire is smaller than the scope of the present invention.

According to the present invention, there is provided a gas shielded arc welding method and a wire for gas shielded arc welding in which the slag can be easily peeled off even under the condition that the steel is in a high temperature state of about 200 to 300 ° C.

Claims (9)

In the gas shielded arc welding method, 0.12 mass% or less of C based on the total mass of the wire; Si 0.6-1.5 mass%; Mn 0.8-1.8 mass%; S 0.007-0.040 mass%; And 0.03 to 0.18 mass% of Ti, the remainder being Fe and an unavoidable impurity, using a wire having a diameter of 0.9 to 1.6 mm, Use carbon dioxide or a mixed gas of argon and carbon dioxide as the shielding gas, and use DC reverse polarity with the wire as the anode under the condition that the wire extension length is 20 to 25 mm, the welding current is 190 to 350 A, and the welding voltage is 22 to 39 V. Downward welding of mild steel or steel made of high-strength steel of 490 to 590 MPa class, At this time, each of the gas containing slag having 37% by mass or more of SiO ₂ , 46% by mass or less of MnO, and 12% by mass or less of TiO ₂ , and having an A value of 0.50 or more, represented by Equation 1 below. Shield Arc Welding Method: Equation 1

Where The content of SiO ₂ (% by mass) is expressed as [SiO _2], Content (mass%) of MnO is represented as [MnO], The content of TiO ₂ (% by mass) is expressed as [TiO _2]. The method of claim 1, The wire further contains at least one of Zr and Al, The total content of Ti, Zr and Al is 0.25 mass% or less based on the total mass of the wire, When Zr is contained, the gas shield arc welding method in which the A value is obtained by the following equation (2): Equation 2

The method of claim 1, A gas shielded arc welding method, wherein the wire further contains at least one element selected from the group consisting of Ni, Cr, and Mo, wherein the total content of Ni, Cr, and Mo is 0.60 mass% or less based on the total mass of the wire. In the gas shield arc welding wire, The wire is C 0.12% by mass or less based on the total mass of the wire; Si 0.6-1.5 mass%; Mn 0.8-1.8 mass%; S 0.007-0.040 mass%; And 0.03 to 0.18 mass% of Ti, the remainder being Fe and inevitable impurities, The wire has a diameter of 0.9 to 1.6 mm, As a shielding gas, DC reverse polarity using the wire as the anode under arbitrary conditions using carbon dioxide or a mixed gas of argon and carbon dioxide and having a wire extension length of 20 to 25 mm, a welding current of 190 to 350 A, and a welding voltage of 22 to 39 V When welding the steel material consisting of mild steel or high tensile strength steel of 490 to 590 MPa class, and downward welding, each contains 37% by mass or more of SiO ₂ , 46% by mass or less of MnO and 12% by mass or less of TiO ₂ , A gas shielded arc welding wire for generating slag having an A value of 0.50 or more represented by Equation 1 below: Equation 1

Where The content of SiO ₂ (% by mass) is expressed as [SiO _2], Content (mass%) of MnO is represented as [MnO], The content of TiO ₂ (% by mass) is expressed as [TiO _2]. The method of claim 4, wherein The wire further contains at least one of Zr and Al, The total content of Ti, Zr and Al is 0.25 mass% or less based on the total mass of the wire, When Zr is contained, A value is a wire for gas shielded arc welding obtained by the following equation (2): Equation 2

The method of claim 4, wherein A wire for gas shielded arc welding, in which the wire further contains at least one element selected from the group consisting of Ni, Cr, and Mo, wherein the total content of Ni, Cr, and Mo is 0.60% by mass or less based on the total mass of the wire. In the gas shield arc welding wire, 0.12 mass% or less of C based on the total mass of the wire; Si 0.6-1.5 mass%; Mn 0.8-1.8 mass%; S 0.007-0.040 mass%; And 0.03 to 0.18 mass% of Ti, the remainder being Fe and an unavoidable impurity, using a wire having a diameter of 0.9 to 1.6 mm, Mild steel or 490 to 590 MPa using carbon reversed or a mixed gas of argon and carbon dioxide as the shielding gas, DC reverse polarity with the wire as the anode under the condition that the wire extension length is 20 mm, the welding current is 320 A and the welding voltage is 35 V. Down welded steel made of high tensile steel A gas shielded arc containing 37% by mass or more of SiO ₂ , 46% by mass or less of MnO, and 12% by mass or less of TiO ₂ , respectively, and producing slag having an A value of 0.50 or more, represented by Equation 1 below. Welding wire: Equation 1

Where The content of SiO ₂ (% by mass) is expressed as [SiO _2], Content (mass%) of MnO is represented as [MnO], The content of TiO ₂ (% by mass) is expressed as [TiO _2]. The method of claim 7, wherein The wire further contains at least one of Zr and Al, The total content of Ti, Zr and Al is 0.25 mass% or less based on the total mass of the wire, When Zr is contained, A value is a wire for gas shielded arc welding obtained by the following equation (2): Equation 2

The method of claim 7, wherein A wire for gas shielded arc welding, in which the wire further contains at least one element selected from the group consisting of Ni, Cr, and Mo, wherein the total content of Ni, Cr, and Mo is 0.60% by mass or less based on the total mass of the wire.