JP2011240370A - Flux cored wire for horizontal fillet gas shield arc welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flux cored wire for horizontal fillet gas shield arc welding, capable of obtaining excellent anti-pit performance and welding workability when it is used for horizontal fillet welding of a primer-coated steel plate in a wide range of welding condition.SOLUTION: The flux cored wire for horizontal fillet gas shield arc welding contains, by mass% based on the total mass of the wire, 1.0-2.0% of Zr oxide in terms of ZrO, 0.5-2.0% of Si oxide in terms of SiO, 0.1-1.0% in the total of one or more of any one or both Al and Al oxide in terms of AlOand 0.1-1.0% in the total of one or more of any one or both of Mg and Mg oxide in terms of MgO, wherein 0.5% of any one or both of Mg and Mg oxide in terms of MgO, 0.2-0.7% in the total of one or more Fe oxides in terms of FeO and Mn oxide in terms of MnO, and 0.05-0.20% in the total of Na compound and K compound in terms of NaO and in terms of KO. The wire also contains ≤0.1% of Ti and Ti oxide in terms of TiO.

Description

  TECHNICAL FIELD The present invention relates to a flux cored wire for horizontal fillet gas shielded arc welding of mild steel, 490 to 590 MPa class high-tensile steel, low-temperature steel, weather-resistant steel, etc. coated with a shop primer, particularly pit resistance and welding work. The present invention relates to a fluxed wire for horizontal fillet gas shield arc welding suitable for improving the performance.

  In fields such as ships and bridge structures, a primary rust preventive paint such as a shop primer or an inorganic zinc primer is applied to the surface of a steel material as a welding base material from the viewpoint of rust prevention. In the primer coated steel sheet coated with such a primer, the ratio of welding by fillet welding is high, and there is still a strong demand for improving the welding material surface in order to improve the welding efficiency of fillet welding.

  However, when the primer coated steel plate is particularly horizontally fillet welded in the above-mentioned demand fields, it becomes easy to generate pits in the weld metal due to the primary anticorrosive paint applied to the steel material, and the bead shape and bead appearance are It will deteriorate. Due to the deterioration of these pits and appearance shape, the welding quality deteriorates, and there is a case where it is necessary to perform welding for reworking again, which causes problems such as an increase in labor burden and an increase in the number of processes. . For this reason, conventionally, various flux-cored wires have been proposed for the purpose of solving these problems.

As a flux-cored wire for horizontal fillet gas shielded arc welding of a primer-coated steel sheet, for example, as disclosed in Patent Document 1, a material containing a small amount of a slag forming agent mainly composed of TiO ₂ (hereinafter referred to as TiO ₂ low Generally referred to as slug wire). In recent years, there has been proposed a technique containing a small amount of a slag forming agent mainly composed of ZrO ₂ (hereinafter referred to as ZrO ₂ -based low slag wire) as disclosed in Patent Documents 2 to 4.

Japanese Patent Laid-Open No. 3-180298 Japanese Patent Laid-Open No. 11-5193 JP 2000-42787 A JP 2004-298912 A

However, the conventional ZrO ₂ -based low slag wire has the advantage of good pit resistance particularly when used under high current and high speed welding conditions, but when used on a relatively low current side, The desired spatter resistance could not be obtained, and it was necessary to improve welding workability such as bead shape, bead appearance, and slag peelability.

  Therefore, in order to solve the above-mentioned problems, the present invention can be used for horizontal fillet welding of a primer coated steel sheet in a wide range of welding conditions such as welding current and welding speed, and excellent pit resistance can be obtained. An object of the present invention is to provide a fluxed wire for horizontal fillet gas shielded arc welding capable of ensuring welding workability.

In order to solve the above-described problems, the inventors of the present invention compared and studied the welding characteristics between the TiO ₂ -based low slag wire and the ZrO ₂ -based low slag wire.

For example, as a general construction condition performed in the field of shipbuilding and bridge structures, a wire diameter of 1.4 mm and a welding speed of 30 to 50 cm / min (welding current of 290 to 340 A) with respect to a target leg length of 5 to 7 mm Under relatively low current and low-speed welding conditions, the TiO ₂ -based low slag wire has a bead shape, appearance and welding workability (arc stability, spatter, slag peelability, etc.) rather than the ZrO ₂ -based low slag wire. Was good. In contrast, ZrO ₂ -based low slag wire generates large spatters under the low current and low speed welding conditions as described above, and the bead shape tends to be convex and rugged. Inferior.

However, for example, when high-speed horizontal fillet welding is performed at a high current such as a wire diameter of 1.4 mm, a welding speed of 60 cm / min or higher, and a welding current of 360 A or higher, the ZrO ₂ -based low slag wire is more TiO ₂ -based. Pit resistance was better than low slag wire.

That is, the present inventor found that the ZrO ₂ -based low slag wire has an advantage of good pit resistance particularly when used under high current and high speed welding conditions, but when used on a relatively low current side. It has been found that it is necessary to improve the welding workability such as the spatter resistance, bead shape, bead appearance, and slag peelability. For this reason, the present inventors have made various wires experimentally and intensively studied in order to solve the problems peculiar to such ZrO ₂ -based low slag wires. As a result, ZrO ₂ which can prevent the generation of pits by making the primer combustion gas easy to release to the outside due to the vigorous stirring action and slag encapsulation of the molten pool is the main component of the slag forming agent, and the convex shape of the bead SiO ₂ is added from the viewpoint of preventing the formation of TiO _2, and the content ratio of other components is adjusted from the viewpoint of exhibiting various functions. Further, TiO ₂ is added from the viewpoint of improving the pit resistance while reducing the thickness of the slag. We have invented a flux-cored wire for horizontal fillet gas shielded arc welding with as little as possible.

The gist of the present invention is that, in a flux-filled wire for horizontal fillet gas shielded arc welding in which a steel outer shell is filled with flux, the mass% is based on the total mass of the wire and the Zr oxide is converted to ZrO ₂ : 1.0 to 2.0%, SiO ₂ conversion value of Si oxides: sum of 0.5 to 2.0%, MgO converted value of the sum of terms of Al ₂ O ₃ value of Al and Al oxides, and Mg and Mg oxides , Total: 0.1 to 1.0%, sum of Mg and Mg oxide converted value of MgO: 0.5% or less, total of Fe oxide converted value of Fe oxide and MnO converted value of Mn oxide: 0.2 to 0.7% of Na and K oxides and compounds, Na ₂ O equivalent value and total of K ₂ O equivalent value: 0.05 to 0.20%, containing Ti and Ti oxide TiO ₂ converted value: 0.1% or less, the balance being mainly extracellular steel Fe content of the iron powder, and wherein the alloy material is a deoxidizing agent and unavoidable impurities.

  Further, it is characterized by further containing 0.005 to 0.035% of the sum of Bi and Bi oxide in terms of Bi.

  Further, it is also characterized in that it further contains an F converted value of metal fluoride: 0.01 to 0.10%.

  According to the flux cored wire for horizontal fillet gas shielded arc welding of the present invention, it is excellent in horizontal fillet welding of a primer coated steel sheet not only in high current and high speed welding conditions but also in a low current region. Since pit resistance is obtained and welding workability is good, it is possible to improve the efficiency of welding and improve the quality of the welded portion.

  Hereinafter, as an embodiment for carrying out the present invention, a fluxed wire for horizontal fillet gas shield arc welding will be described in detail.

In order to solve the above-mentioned problems, the inventors made various types of wires and examined the details. As a result, by using ZrO ₂ as the main component of the slag forming agent, it is possible to obtain a vigorous stirring action of the molten pool with a strong arc force by ZrO ₂ and a uniform slag encapsulation state even if the amount of slag generation is reduced. It has been found that it is possible to easily release the primer combustion gas from the molten pool to the outside and prevent the generation of pits. It has also been found that SiO ₂ can adjust the viscosity of the molten slag to suppress excessive retreat of the molten pool due to arc force and prevent the bead from becoming convex.

Furthermore, by reducing TiO ₂ as much as possible, the thickness of the slag was made thinner than that of the conventional slag, and the pit resistance could be further improved.

  The reason for limiting the component composition and content of the flux cored wire for horizontal fillet gas shielded arc welding of the present invention will be described below. In addition, content of each component composition is shown by the mass% with respect to the wire total mass.

[ZrO ₂ converted value of Zr oxide: 1.0 to 2.0%]
ZrO ₂ is added from zircon sand, zirconium oxide, or the like, and raises the solidification temperature of the molten slag to increase the viscosity of the slag, thereby forming a thin slag and increasing the solidification rate. Further, the stirring action of the molten pool can be enhanced to facilitate the release of the primer combustion gas from the molten pool to the outside, thereby preventing the generation of pits. If the ZrO ₂ conversion value of the Zr oxide is less than 1.0%, the stirring action of the molten pool is lowered particularly under low current and low speed welding conditions, and pits are likely to be generated. On the other hand, when the ZrO ₂ conversion value of the Zr oxide exceeds 2.0%, the arc becomes rough particularly under low current and low speed welding conditions, and large spatters occur frequently. Further, since solidification of the molten slag becomes too fast and the viscosity of the slag increases rapidly, pits and gas grooves are likely to be generated. For this reason, the rough appearance of the bead and the tendency of the molten pool to solidify tend to cause unevenness on the surface, resulting in loss of smoothness. Therefore, the ZrO ₂ conversion value of the Zr oxide is set to 1.0 to 2.0%.

[Si oxide SiO ₂ equivalent value: 0.5 to 2.0%]
SiO ₂ is added from silica sand, zircon sand, silica sand soda, etc., and has an action of increasing the viscosity of the molten slag and improving the slag peelability. When the SiO ₂ conversion value of the Si oxide is less than 0.5%, the slag encapsulation state is poor and slag peeling is poor, and the bead shape and bead appearance are also poor. On the other hand, when the SiO ₂ equivalent value of Si oxide exceeds 2.0%, the amount of spatter generated increases. Further, the bead toe (lower plate side) is swollen, the bead shape and the bead appearance are poor, and pits and gas grooves are easily generated. Therefore, the SiO ₂ equivalent value of the Si oxide is 0.5 to 2.0%.

[Total of Al and Al oxide equivalent of Al ₂ O ₃ and Mg and Mg oxide equivalent of MgO: 0.1 to 1.0%, Mg and Mg oxide equivalent of MgO Of 0.5% or less]
Al and Mg are added from metal Al, metal Mg, Al-Mg alloy, etc., and have the effect of improving the impact value of the impact metal of the weld metal as a strong deoxidizer. Further, Al ₂ O ₃ and MgO as deoxidation products at this time are used as molten slag components in the same manner as Al oxide and Mg oxide added from alumina powder (Al ₂ O ₃ ) and magnesia powder (MgO). It acts to prevent the undercut that tends to occur on the bead upright side and to improve the conformability of the bead toe. If the sum of the sum of Al and Al oxide in terms of Al ₂ O ₃ and the sum of Mg and Mg oxide in terms of MgO is less than 0.1%, an undercut occurs on the bead upright side, and the bead The shape and bead appearance are poor. On the other hand, if the sum of the sum of the Al ₂ O ₃ converted value and the MgO converted value exceeds 1.0%, the amount of slag generated increases, pit resistance deteriorates, and slag enveloping occurs and slag is generated. Peelability, bead shape and bead appearance are poor.

However, if the sum of the MgO equivalent values exceeds 0.5%, the arc becomes rough, the spatter is frequently generated, the slag encapsulation state is deteriorated, the bead shape and the bead appearance are poor, and pits are easily generated. Therefore, the sum of the Al ₂ O ₃ equivalent value of Al and Al oxide and the MgO equivalent value of Mg and Mg oxide is 0.1 to 1.0%, provided that Mg and Mg oxide The sum of MgO equivalent values is 0.5% or less.

[Total of Fe oxide equivalent value of Fe oxide and MnO equivalent value of Mn oxide: 0.2 to 0.7%]
Fe oxides such as FeO and Fe ₂ O ₃ , and Mn oxides such as MnO and MnO ₂ , FeO equivalent value of Fe oxide, and the total of MnO equivalent value of Mn oxide is less than 0.2%, The conformability of the bead becomes worse at the lower plate side bead toe, and the bead shape becomes convex, and the slag removability becomes poor. On the other hand, if the total of the FeO equivalent value and the MnO equivalent value exceeds 0.7%, the slag encapsulation state is poor, the slag peelability is poor, the bead toe portion is swollen, and the bead shape and the bead appearance are also bad. Furthermore, the amount of fume generation increases. Therefore, the total of the Fe oxide equivalent value of the Fe oxide and the MnO equivalent value of the Mn oxide is 0.2 to 0.7%.

[Total of Na ₂ O converted values and Na ₂ O converted values and K ₂ O converted values of 0.05 and 0.20%]
Na and K are added from potassium feldspar, a solid component of water glass made of sodium silicate or potassium silicate, or a fluorine compound such as sodium fluoride or potassium silicate, not only acting as an arc stabilizer but also a slag forming agent. As a result, it suppresses a rapid increase in viscosity during the solidification process of the molten slag, thereby improving the pit resistance and providing a smooth bead shape. If the total of Na ₂ O converted values and K ₂ O converted values of oxides and compounds of Na and K is less than 0.05%, large spatters occur frequently, and pits and gas grooves are likely to be generated, resulting in uneven surfaces. This results in poor bead shape and bead appearance. On the other hand, if the total of the Na ₂ O converted value and the K ₂ O converted value exceeds 0.20%, the slag peelability, the bead shape and the bead appearance are poor, and the amount of spatter and fume generation increases. Accordingly, the total of Na ₂ O converted values and K ₂ O converted values of oxides and compounds of Na and K is 0.05 to 0.20%.

[TiO ₂ conversion value of Ti and Ti oxide: 0.1% or less]
Addition of Ti and Ti oxide exceeding 0.1% lowers the viscosity of the slag, lowers the solidification temperature of the slag, further increases the thickness of the slag, and the bottom plate side toe of the bead swells to form a bead. Becomes defective and pits are likely to occur. Therefore, the TiO ₂ equivalent value of Ti and Ti oxide is 0.1% or less.

[Sum of Bi-converted values of Bi and Bi oxide: 0.005 to 0.035%]
Bi is added by metal Bi, oxidized Bi, or the like, and has an effect of improving the slag removability, giving gloss to the bead surface and improving the bead appearance. If the total of Bi and Bi oxides in terms of Bi is less than 0.005%, the effect cannot be obtained. If it exceeds 0.035%, the slag at the top of the bead flows, and the entire bead is encapsulated with slag. And the bead appearance is poor. Therefore, the sum of Bi and Bi oxide in terms of Bi is set to 0.005 to 0.035%.

[F conversion value of metal fluoride: 0.01 to 0.10%]
F is added from sodium fluoride, potassium silicofluoride, or the like, and has the effect of improving the directivity of the arc to form a stable molten pool and adjusting the viscosity of the slag to improve the pit resistance. If the F-converted value of the metal fluoride is less than 0.01%, the viscosity is high and pits are likely to occur. On the other hand, if the F-converted value of the metal fluoride exceeds 0.10%, the slag viscosity is lowered and thin slag that is difficult to remove remains on the upper leg portion of the bead, resulting in poor slag peelability, and the bead shape becomes convex. Become. Therefore, the F conversion value of the metal fluoride is set to 0.01 to 0.10%.

  The reason for limiting the constituent requirements of the fluxed wire for horizontal fillet gas shielded arc welding of the present invention has been described above. Other wire components include mild steel, 490-590 MPa class high strength steel, low temperature steel, and weather resistance. The mechanical test of the weld metal component specified for each type of flux cored wire such as steel and the elements and the balance for satisfying the chemical component are mainly the Fe content of the steel outer shell, the Fe content in the alloy iron, the iron powder and Inevitable impurities. As said element, it is the sum total of an outer skin component and a flux, C: 0.03-0.10%, Si: 0.3-1.2%, Mn: 1.0-4.0% are preferable, Others are Ni, Cu, Cr, or the like can be added as a single element or alloyed iron depending on the components of the steel sheet to be welded and the mechanical performance required for the weld metal.

  Further, the flux cored wire for horizontal fillet gas shielded arc welding of the present invention has the above-described limited flux in the total mass of the wire in the outer shell of mild steel and low alloy steel with good wire drawing workability after flux filling. On the other hand, after filling about 8 to 18%, the diameter is reduced to a predetermined wire diameter (0.9 to 1.6 mm) by hole die drawing or cassette roller rolling. It should be noted that any seamless or seam type wire without a gap penetrating the steel outer shell can be applied.

  According to the present invention, by adjusting the components of the flux-cored wire for horizontal fillet gas shielded arc welding within the above-mentioned range, not only when using high current and high speed welding conditions but also in a low current region. In addition, it is possible to obtain excellent pit resistance in horizontal fillet welding of a primer coated steel sheet, improve welding workability, and improve welding efficiency and weld quality.

  An embodiment of a flux cored wire for horizontal fillet gas shield arc welding to which the present invention having the above-described configuration is applied will be described in detail.

  First, as a test material, after filling a mild steel shell with a flux, the diameter was reduced (intermediate annealing was performed once for softening and dehydrogenation of the shell), and the flux filling rate shown in Table 1 was 16.0%, and the wire diameter was 1 Various types of seamless-type flux-cored wires having no through-holes in a 4 mm steel outer skin were produced.

  A horizontal fillet welding test was conducted with an automatic welder using a T-shaped fillet specimen of an inorganic zinc primer-coated steel sheet, using trial wires made of the components shown in Table 1. The specimen is steel grade SM490B, the thickness of the specimen is 12 mm, the specimen length is 1.0 m, the primer coating steel sheet has a primer film thickness of about 30-40 μm, and primer coating is also applied to the bottom and vertical plate end faces of the T-shaped fillet specimen. There is. While these steel plates were pressed, they were tack welded in a state where there was no gap between the lower plate and the standing plate to obtain test specimens.

Welding conditions Welding current 300A (supply polarity DC +), arc voltage 30～32V, welding speed 40 cm / min, wire extension length (chip - Distance between preform) 25 mm, shielding gas CO ₂ gas (gas flow rate 25 l / min ), The pit resistance, bead shape, bead appearance, slag peelability, and spatter occurrence were evaluated.

  In addition, pit resistance shows (circle): No pit and a gas groove, (triangle | delta): 1-10 piece / m, x: frequent occurrence (11 piece / m or more). The results are shown in Table 2.

In Table 1 and Table 2, the wire No. 1-8 are examples of the present invention, wire Nos. 9 to 21 are comparative examples. Wire No. which is an example of the present invention. 1 to 8 are ZrO ₂ converted value, SiO ₂ converted value, total of Al ₂ O ₃ converted value and MgO converted value and single MgO converted value, total of FeO converted value and MnO converted value, and Na ₂ O converted Value and K ₂ O converted value are all within the range specified in the present invention, and TiO ₂ converted value is less than 0.1%, so pit resistance, bead shape, bead appearance, slag Both the peelability and the amount of spatter generated were better or better. In addition, wire No. including Bi Nos. 1, 3, 4 and 7 have very good slag removability, and wire No. 1 containing metal fluoride. 1 to 3, 5 and 6 had high arc directivity and stable molten pools were obtained.

  Furthermore, a separate wire No. As a result of performing horizontal fillet welding in the same manner under high-speed welding conditions with a welding current of 400A (power polarity DC +), arc voltage of 37-38V, high current of 90cm / min. The bead shape, the bead appearance and the slag peelability were more than satisfactory and the amount of spatter was small, which was a very satisfactory result.

Wire No. being compared No. 9 had a ZrO ₂ conversion value less than the range defined in the present invention, so the stirring action of the molten pool was lowered and pits were generated. Further, since the F conversion value is large, the viscosity of the slag is reduced, and a thin slag that is difficult to remove remains on the upper leg portion of the bead, resulting in poor slag peelability, and the bead shape is convex and defective.

Wire No. No. 10 had a ZrO ₂ converted value larger than the range specified in the present invention, so that the arc became rough, the amount of spatter was large, and the viscosity of the slag was increased, so the pit resistance and bead appearance were poor.

Wire No. No. 11 had a SiO ₂ conversion value less than the range defined in the present invention, so the slag encapsulation state was poor and slag peeling was poor, and the bead shape and bead appearance were also poor.

Wire No. No. 12 has a SiO ₂ conversion value larger than the range specified in the present invention, so that a large amount of spatter is generated, and pits and gas grooves are also generated. Met.

Wire No. In No. 13, since the total of the Al ₂ O ₃ converted value and the MgO converted value was less than the range defined in the present invention, an undercut occurred on the bead stand plate side, and the bead shape and bead appearance were poor. Moreover, since it did not contain a fluorine compound, four pits were generated.

Wire No. No. 14, since the sum of the Al ₂ O ₃ converted value and the MgO converted value is larger than the range defined in the present invention, the amount of slag generation increases, pit properties occur frequently, slag encapsulation occurs, slag peelability, bead shape The bead appearance was also poor.

  Wire No. No. 15 has an MgO equivalent value larger than the range specified in the present invention, so that the arc becomes rough, the amount of spatter generated is large, the slag encapsulation state is poor, the bead shape and the bead appearance are poor, and six pits are generated.

  Wire No. No. 16, since the total of the FeO converted value and the MnO converted value is less than the range defined in the present invention, the conformability of the bead becomes worse at the lower plate side bead toe, the bead shape becomes convex, and the slag peeling is also poor. became. Moreover, since there are many Bi conversion values, the slag of the upper part of the bead flowed and it became impossible to encapsulate, and the bead appearance was poor.

Wire No. In No. 17, the ZrO ₂ conversion value was less than the range defined in the present invention, so the stirring action of the molten pool was lowered and pits were generated. Moreover, since the sum of the FeO converted value and the MnO converted value is larger than the range specified in the present invention, the slag encapsulation was poor, the slag peelability was poor, the bead toe portion was swollen, and the bead shape and appearance were also poor.

Wire No. No. 18 has a Na ₂ O converted value and a K ₂ O converted value less than the range specified in the present invention, so that large spatters frequently occur, pits and gas grooves are generated, and the bead appearance is a rough surface appearance. there were.

Wire No. In No. 19, since the total of Na ₂ O converted value and K ₂ O converted value was larger than the range defined in the present invention, the slag peelability, bead shape and bead appearance were poor, and the amount of spatter was large. Moreover, since it did not contain a fluorine compound, two pits were generated.

Wire No. No. 20 had a TiO ₂ conversion value larger than the range defined in the present invention, so pits were generated and the bead shape was poor. Further, since the Bi converted value was less than the range defined in the present invention, the bead appearance was not glossy and was somewhat poor.

Wire No. No. 21 had a TiO ₂ conversion value larger than the range defined in the present invention, so pits were generated and the bead shape was poor. Further, since the Bi-converted value is larger than the range defined in the present invention, the slag at the upper part of the bead flows and cannot be encapsulated, and the bead appearance is poor.

Claims (3)

In fluxed wire for horizontal fillet gas shield arc welding, which is formed by filling the steel outer shell with flux,
% By mass relative to the total mass of the wire
ZrO ₂ conversion value of Zr oxide 1.0 to 2.0%
SiO ₂ converted value of Si oxide 0.5 to 2.0%
Sum of Al ₂ O ₃ equivalent value of Al and Al oxide, and sum of MgO equivalent value of Mg and Mg oxide: 0.1 to 1.0%,
Sum of MgO converted value of Mg and Mg oxide: 0.5% or less,
Total of FeO equivalent value of Fe oxide and MnO equivalent value of Mn oxide: 0.2 to 0.7%,
Total terms of Na ₂ O values and K ₂ O conversion value of oxides and compounds of Na and K: containing from 0.05 to 0.20%,
TiO ₂ conversion value of Ti and Ti oxide: 0.1% or less, the balance being mainly the Fe content of the steel outer shell, iron powder, alloying agent, deoxidizing agent and inevitable impurities Flux-cored wire for meat gas shielded arc welding.   The flux cored wire for horizontal fillet gas shielded arc welding according to claim 1, further comprising 0.005 to 0.035% of the Bi equivalent value of Bi and Bi oxide.   The flux-cored wire for horizontal fillet gas shielded arc welding according to claim 1 or 2, further comprising an F converted value of metal fluoride: 0.01 to 0.10%.