KR100871203B1 - Flux-cored wire for gas shielded arc welding - Google Patents

Abstract

The flux of the flux cored wire for gas shielded arc welding of the present invention is 0.10 to 0.30% by mass of Zr in terms of Zr, 0.30 to 1.0% by mass of ZrO ₂ , and TiO ₂ in terms of the component ratio per mass of the wire. 1.0 to 5.0% by mass, SiO ₂ to 0.30 to 1.0% by mass, and the metal Al source to 0.10 to 0.30% by mass in terms of Al, and at least one of Na and K as an alkali metal source is selected from Na ₂ O and K ₂ O. and in terms of the total amount of 0.04 to 0.10 mass%, and the K ₂ O / Na ₂ O ratio value of 1.0 to 3.0. The flux cored wire of the present invention relates to horizontal fillet welding construction and the like, and is excellent in high-speed weldability and porosity resistance, and also improves slag coating property and slag peelability.

Description

Flux cored wire for gas shield arc welding {FLUX-CORED WIRE FOR GAS SHIELDED ARC WELDING}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to flux-cored wire for gas shield welding in which the metal shell component is mild steel, and more particularly to flux cored wire for gas shield arc welding used for automatic or semi-automatic arc welding.

In general, in the field of shipbuilding and steel bridges, flux cored wires for gas shielded arc welding that enable high efficiency welding construction of welded structures are widely used. In particular, in the case where high efficiency is important, a high speed welding construction method using a two-electrode single pull method or the like is widely employed, and Japanese Patent Laid-Open No. 1999-5193, Japanese Patent Laid-Open No. 2000-42787, and Japanese Patent Laid-Open No. Welding wires and the like described in Japanese Patent Application Laid-Open No. 314985, Japanese Patent Publication No. 1994-69633, and Japanese Patent Application Laid-Open No. 2000-71096 are used. These conventional flux cored wires are designed with a slag component system for the purpose of improving the porosity resistance at the time of high-speed welding, and are also excellent in shape such as contours of beads.

However, in the case of semi-automatic and automatic horizontal fillet welding construction of shipbuilding and steel bridges, it is important that welding slag uniformly coat the entire surface of the weld bead (slag coating property) as important as the porosity. to be. This is because, when the slag unevenly coats the bead surface, the thin portion of the slag has poor peelability, making the slag peeling process difficult. In addition, in the part where slag peeling is bad, the slag adheres and becomes a spot shape, resulting in the bead appearance being damaged.

In the conventional two-electrode single-pull flux cored wire, in particular, when the base material (welding material) welds mild steel low Si and low Mn material, the concentration of MnO and SiO ₂ in the slag is higher than in the case of welding high tensile steel. As a result, the slag viscosity decreases and the slag amount decreases. For this reason, not only becomes the non-uniformity of the slag encapsulation with respect to a bead, but also the phenomenon which a slag adheres to a bead in the part with thin thickness of a slag worsens a bead appearance very much. In addition, the bead shape becomes convex. In the case of welding a steel sheet having an oxide film on the surface is also, are the FeO, Fe ₂ O ₃ in the slag it is contained a lot, the same results since the slag viscosity is lowered. In particular, when the welding speed exceeds 150 cm / min, it deteriorates.

In addition, when slag peelability deteriorates due to the sticking of slag, slag removal work for obtaining a healthy welded part requires unnecessary manpower, which may cause considerable time and cost increase.

However, in the conventional wires described in each of the above-mentioned prior documents, although this high-speed weldability and porosity resistance are excellent, it was not necessarily satisfied from the point of the coating property of a welding slag.

For example, in the welding wires of Japanese Patent Laid-Open No. 1999-5193, Japanese Patent Laid-Open No. 2000-42787, and Japanese Patent Publication No. 194-69633, single welding of a primer steel plate (welding speed = about 100 cm / In order to improve the porosity resistance and workability in the powder), but applied to twin tandem high speed welding (welding speed = 150 to 180 cm / min), when the base material component is biased to the low Si and low Mn side Since the slag generation amount decreases, the slag foreskinability of the weld bead surface is inferior, resulting in a problem that the bead shape and the appearance of the beads become undesirable weld beads. Further, even when the steel sheet is not a primer steel sheet, but also a black skin steel sheet, these prior arts have a problem of poor porosity resistance.

In addition, in the welding wire described in Japanese Patent Laid-Open No. 1998-314985, the purpose is to improve the viscosity of the weld metal so as to prevent bead drooping during lateral welding. Even if it is applied to twin tandem high speed welding (welding speed = 150-180 cm / min) as it is, it is high in viscosity and inferior in high speed, but also inferior in porosity resistance.

Further, the welding wire described in Japanese Patent Laid-Open No. 2000-71096 is an invention that improves workability in twin tandems of primer steel plates, and particularly aims to reduce the amount of fume and the amount of sputter. When applied to steel sheets or when applied to twin tandem high speed welding (welding degree = 150 to 180 cm / min), porosity and high speed weldability are inferior.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in the case of welding mild steel low Si, low Mn material and high tensile steel whose surface is coated with inorganic zinc primer or covered with black skin, for horizontal fillet welding construction, etc., high-speed weldability and bet An object of the present invention is to provide a flux cored wire for gas shielded arc welding, which has excellent porosity and improved slag coatability and slag peelability.

The flux cored wire for gas shielded arc welding according to the present invention is a flux cored wire for gas shielded arc welding in which flux is filled in a soft steel shell, and the flux rate of the flux cored wire is 10 to 30%. flux is a sugar component total mass of the wire ratio, 0.10 to 0.30% by mass of a metal as Zr source to Zr in terms of, ZrO ₂ of 0.30 to 1.0 mass%, TiO ₂ 1.0 to 5.0 mass%, SiO ₂ of 0.30 to 1.0 mass% And the metal Al source is 0.10 to 0.30 mass% in terms of Al, and Na and K as alkali metal sources are 0.04 to 0.10 mass% in terms of the total amount of Na ₂ O and the total amount of K ₂ O, and (K ₂ O equivalent) Total amount / Na ₂ O equivalent) ratio is 1.0 to 3.0, and the remainder of the flux is selected from the group consisting of Al ₂ O ₃ , Mg, Fe-Mn, Fe-Si, K ₂ SiF ₆ , MgO and iron. Characterized in that it comprises at least one.

Here, the Zr source as a metal contains Zr and alloy Zr. As described above, in the present specification, the term "as a metal" includes all metals and alloys.

In addition, in the regulation of the components of the wire, and is defined as the total amount in terms of Na ₂ O and K ₂ O in terms of total amount with respect to the Na and K. This is the conversion of all Na compounds and K compounds contained in the flux into Na ₂ O and K ₂ O, respectively. In other words, the weight of all of these compounds, and Na in the Na ₂ O and K ₂ O, if one assumes that the K compound in the Na and K that make up all of Na ₂ O and K ₂ O.

In the flux cored wire for gas shielded arc welding of the present invention described above, the Zr source as the metal is selected from the group consisting of metal zirconium, ferro zirconium (Fe-Zr) and ferrosilizirconium (Fe-Si-Zr), for example. 1 or more types.

In addition, the Al source as a metal is 1 or more types chosen from the group which consists of metal aluminum and ferro aluminum (Fe-Al), for example.

In addition, it is preferred that the metal Zr as a circle of from 0.15 to 0.25% by mass in terms of Zr, ZrO ₂ is 0.35 to 0.55 mass% and, Zr / ZrO ₂ is 0.20 to 0.35 mass%.

The present invention is a flux composition that maintains good slag foreskin in twin tandem high speed welding (welding speed = 150 to 180 cm / min) in a primer steel sheet or black skin steel sheet, and includes three components of ZrO ₂ , TiO ₂ and SiO ₂ . It was completed according to the knowledge that it is indispensable to take a compound balance. In addition to the above, the present invention is characterized in that an Al source and a Zr source as metals are added in order to realize good porosity resistance under the condition of the surface state and components of the base material such as a primer steel sheet or a black skin steel sheet. In particular, these components instead of the addition of Al ₂ O ₃ and ZrO ₂ as an oxide in the flux, it is meant that the addition of a metal component. That is, in the weld metal under the arc, the one added as a metal component has a large degree of freedom of mixing and automatically generates an appropriate amount of slag against the variation of the oxide component resulting from the variation of the steel sheet surface state and the steel sheet component. The inventors have found that even in black skin steel sheets, good slag foreskin and porosity can be compatible. The present invention has been made in accordance with these findings.

According to the present invention, in the horizontal fillet welding, the above-described composition can improve slag coating and slag peeling properties, and also has excellent conventional air resistance and bead appearance, which are excellent in gas shielded arc welding flux cores. You can get a de wire.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described concretely with reference to an accompanying drawing. First, the flux composition of the flux cored wire for gas shielded arc welding of the present invention and the reason for limiting the component thereof will be described. In addition, the following flux composition is a weight ratio (mass%) with respect to the wire total mass.

`` Zr source: 0.10 to 0.30 mass% (Zr equivalent) ''

The Zr source is a deoxidizer and is added in order to reduce the amount of oxygen in the molten metal and to increase the viscosity of the molten metal, thereby suppressing the sagging of the molten metal, further optimizing the viscosity of the slag and improving the foreskinability of the slag. When this Zr source exceeds 0.30 mass% in Zr conversion value, the amount of Mn and Si hold | maintained in a weld metal will become high, and strength will become high too much. Moreover, the effect of deoxidation is low when Zr source is less than 0.10 mass%. More preferably, Zr source is 0.15-0.25 mass%. If the metal Zr source is in the range of 0.15 to 0.25% by mass, the amount of molten metal oxygen is maintained in the molten paper in an appropriate range even when the deoxidation component of the base steel sheet is varied. It is difficult to receive and maintains good slag foreskin and porosity.

`` ZrO ₂ : 0.30 to 1.00 mass% ''

ZrO ₂ is a slag forming agent and is added to adjust the solidification temperature and viscosity of the molten slag and to improve the bead shape. When ZrO ₂ exceeds 1.00 mass%, the slag melting point increases, and the viscosity of the slag increases, resulting in deterioration of slag encapsulation and porosity resistance. If ZrO ₂ is less than 0.30% by mass, solidification of the molten slag is slowed, resulting in deterioration of slag foreskin and bead shape. More preferably, ZrO ₂ is 0.35 to 0.55 mass%. When the ZrO ₂ is in the range of 0.35 to 0.55% by mass, suitable slag viscosity can be maintained, and therefore, good slag coatability and porosity resistance can be maintained even at high speed welding exceeding 150 cm / min.

`` TiO ₂ : 1.00 to 5.00 mass% ''

TiO ₂ is a slag forming agent and is added to improve the stability of the arc, and to evenly coat the bead surface to improve bead appearance. When TiO ₂ exceeds 5.00 mass%, the amount of slag produced is too large, the viscosity of the molten slag becomes high, and the porosity deteriorates. On the other hand, if the amount of TiO ₂ is less than 1.00 mass%, the slag formation amount is insufficient, resulting in deterioration of slag coatability and slag peelability.

`` SiO ₂ : 0.30 to 1.00 mass% ''

SiO ₂ is a slag forming agent and is added to improve slag peelability and appearance gloss of weld beads. If SiO ₂ exceeds 1.0% by mass, the microporous deteriorates bet too much the viscosity of the molten slag becomes high. On the other hand, if SiO ₂ is less than 0.30 mass%, the bead shape is deteriorated at the same time the viscosity of the slag that runs out of the slag encapsulated degradation.

`` Metal Al source: 0.10 to 0.30 mass% (Al equivalent) ''

The metal Al source acts as a deoxidizer and is added to reduce the amount of oxygen in the weld metal, to secure toughness, and to adjust the expansion of the arc and the fluidity of the molten metal. When the metal Al source exceeds 0.30 mass%, the solidification rate of the molten slag becomes too high, solidification unevenness occurs, and the bead shape and the porosity resistance deteriorate. On the other hand, when metal Al source is less than 0.10 mass%, the viscosity of a weld metal will fall and deterioration of porosity by lack of deoxidation.

"The Na and K as an alkali metal source, the total amount in terms of Na ₂ O and 0.04 to 0.10% by weight of the sum of the total amount in terms of K ₂ O"

Na and K have an effect of stabilizing the arc, and are also added to lower the viscosity of the slag and to facilitate the rise of pores, thereby facilitating the breakup to the outside. When Na and K exceed 0.10 mass% by the sum of the total amount of Na ₂ O and the total amount of K ₂ O, the viscosity of the molten slag becomes too high and the bead shape deteriorates. On the contrary, if it is less than 0.04 mass%, there will be no effect on arc stability and a bead shape will become bad.

"K ₂ O conversion total amount / Na ₂ O conversion total amount: 1.00-3.00"

When the total amount of K ₂ O equivalent / Na ₂ O equivalent total ratio exceeds 3.00, the arc becomes excessively strong, the sputter increases, and the bead shape becomes poor. Moreover, when the total amount of K ₂ O equivalents / Na ₂ O equivalents is less than 1.00, the arc becomes weak and the bead shape becomes poor.

`` Zr / ZrO ₂ : 0.20 to 0.35 ''

The ratio Zr / ZrO ₂ of the metal Zr source and ZrO ₂ is preferably 0.20 to 0.35. If the Zr / ZrO ₂ ratio is in the range of 0.20 to 0.35, it is hardly affected by the variation of the base material and the presence or absence of black skin or primer coating on the surface of the base material, and the best slag coating property and porosity resistance can be achieved.

The flux rate of the flux cored wires of the present invention is suitably 10% to 30% applied to ordinary flux cored wires. Less than 10% makes it difficult to add the necessary alloying elements from the flux only. Adding these elements from the sheath increases the raw material cost, and also increases the manufacturing cost due to the deterioration of freshness due to the increase in the sheath strength due to the alloy addition. Flux rates exceeding 30% tend to break due to thinner skins, resulting in deterioration of freshness, leading to increased manufacturing costs.

As components that may be included in the flux in addition to the above-described flux components, there may be mentioned components described in the following examples, and others, Al ₂ O ₃ , Mg, and the like.

Example

Next, the Example and comparative example for demonstrating the effect of this invention are demonstrated. Table 1 below shows the shell (mild steel) composition (mass%) of the used wire. Table 2 further shows the flux composition filled in the shell. In Table 2, K ₂ O and Na ₂ O represents the total amount in terms of K ₂ O and Na ₂ O in terms of total amount, respectively. Table 3 below shows the welding construction conditions. The welding results are shown in Table 4 below.

In addition, the flux rate of each wire was 14 to 16%. In addition, the flux component other than the components shown in Table 2, alloying elements, a deoxidizer Fe-Mn, Fe-Si, as the slag component as MgO, other K ₂ SiF ₆ and was iron.

In addition, in the evaluation item of Table 4, "slag coatability" evaluated with the number of points of the slag non-foreskin part of a bead. When this non-pore part was 0 places, it was (circle), when it was one place, (triangle | delta), when it was 2 or 3 places, (triangle | delta), and when it was 4 or more places, it was set as x. In addition, "slag peelability" is ◎ when the slag around the slag lightly hit once with a hammer is completely peeled off, ○ when peeled off 2-3 times, △, when peeled off 4 to 6 times The case where it peeled off 7 times or more was made into x. "Porosity resistance" was evaluated by the number of pits with respect to the welding length of 600 mm. When the number of pits is 0, ◎, one is ○, two is △, and three or more is x. "Bead appearance shape" refers to the appearance and beads of the bead end for the appearance of the bead as the evaluation judgment material, and the macroscopic observation of the bead shape is performed on the basis of the judgment of whether the bead shape is a convex part. The shape was comprehensively evaluated. In the case where the bead end portion had a good contour, the imitation did not become disturbed, and the bead shape was not convex,?,?

As shown in Tables 2 and 4, in Examples 1 to 10 of the present invention, all of slag coatability, slag peelability, porosity resistance, and bead appearance were excellent. On the other hand, since Comparative Example 1 has less Zr, Comparative Examples 3 and 4 have ZrO ₂ out of the range of the present invention, and since Comparative Example 5 has less TiO ₂ , Comparative Example 7 has less SiO ₂ , Comparative example 11, since ₂ O + K ₂ O is Na small, poor slag encapsulated resistance and the slag removability. In Comparative Example 2, since Zr is excessively large, in Comparative Example 4, since because of the ZrO ₂ is too large, Comparative Example 6, since the TiO ₂ is too large, in Comparative Example 8 is the SiO ₂ is too large, Comparative Examples 9 and 10 since Al is get out from the scope of the present invention, Comparative example 12, because the Na ₂ O + K ₂ O is too large, bad bet-porous. In addition, Comparative Examples 13 and 14 had bad bead shapes because K ₂ O / Na ₂ O was out of the range of the present invention.

The flux cored wire according to the present invention has excellent slag abrasion resistance as well as excellent high speed weldability and porosity resistance when welding mild steel low Si, low Mn material and high tensile strength steel whose surface is coated with inorganic zinc primer or covered with black skin. And slag peelability can be exhibited.

Claims (4)

A flux cored wire for gas shielded arc welding, in which flux is filled in a soft steel shell, wherein the flux cored wire has a flux ratio of 10 to 30%, and the flux is a component ratio per mass of the wire, and a Zr source as a metal is obtained. 0.10 to 0.30 mass% in Zr, 0.30 to 1.0 mass% in ZrO ₂ , 1.0 to 5.0 mass% in TiO ₂ , 0.30 to 1.0 mass% in SiO ₂ , and 0.10 to 0.30 mass% in Al equivalent And 0.04 to 0.10 mass% of Na and K as alkali metal sources in the sum of the total amount of Na ₂ O and the total amount of K ₂ O, and the value of the ratio (total amount of K ₂ O / total amount of Na ₂ O) is 1.0. To 3.0, and the flux for gas shielded arc welding comprising at least one selected from the group consisting of Al ₂ O ₃ , Mg, Fe-Mn, Fe-Si, K ₂ SiF ₆ , MgO and iron as the remainder of the flux. Cored wire. The method of claim 1, A flux cored wire for gas shielded arc welding, wherein the Zr source as a metal is at least one selected from the group consisting of metal zirconium, ferro zirconium (Fe-Zr), and ferrosilizirconium (Fe-Si-Zr). The method of claim 1, A flux cored wire for gas shielded arc welding, wherein the Al source as a metal is at least one member selected from the group consisting of metal aluminum and ferro aluminum (Fe-Al). The method of claim 1, A flux nose wire for gas shielded arc welding, wherein the Zr source as a metal is 0.15 to 0.25 mass%, ZrO ₂ is 0.35 to 0.55 mass%, and Zr / ZrO ₂ is 0.20 to 0.35 mass% in terms of Zr.