Title of Invention	SINTERED FLUX FOR SUMERGRD ARC WELDING
Abstract	Provided is sintered flux for submerged arc welding including: 12.0-24.0wt% SiO2, 24.0-38.0wt% AI2O3, 6.0-13.0wt% TiO2, 2.0-9.0wt% CaO, 7.0-14.0wt% CaF2, 12.0-23.0wt% MnO, 2.0-17.0wt% MgO, and 1.0-5.0wt% Na2O, K2O, Li2O or a mixture thereof. Basicity (B) of the sintered flux satisfies 2.0 £ ° s 6.5. In addition, the sintered flux for submerged arc welding includes 5.0wt% or less particles larger than 1.00mm, 90.0wt% or more particles of 0.20-1.00mm, and 5.0wt% or less particles smaller than 0.20mm. Therefore, it is possible to apply the sintered flux to welding of steel frames, bridges, pipes, ships, marine structures, and so on, requiring for good welding workability even during high-speed welding.

Title of Invention

SINTERED FLUX FOR SUMERGRD ARC WELDING

Abstract

Provided is sintered flux for submerged arc welding including: 12.0-24.0wt% SiO2, 24.0-38.0wt% AI2O3, 6.0-13.0wt% TiO2, 2.0-9.0wt% CaO, 7.0-14.0wt% CaF2, 12.0-23.0wt% MnO, 2.0-17.0wt% MgO, and 1.0-5.0wt% Na2O, K2O, Li2O or a mixture thereof. Basicity (B) of the sintered flux satisfies 2.0 £ ° s 6.5. In addition, the sintered flux for submerged arc welding includes 5.0wt% or less particles larger than 1.00mm, 90.0wt% or more particles of 0.20-1.00mm, and 5.0wt% or less particles smaller than 0.20mm. Therefore, it is possible to apply the sintered flux to welding of steel frames, bridges, pipes, ships, marine structures, and so on, requiring for good welding workability even during high-speed welding.

Full Text	BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sintered flux for submerged arc welding, and more particularly, to sintered flux for submerged arc welding of mild steel and high tensile steel of 50kgf/mm2 used in steel frames, bridges, pipes, ships, marine structures, and so on, the sintered flux is capable of obtaining good arc stability, pockmark resistance, slag detachability, pit resistance, and bead shape when used in high-speed welding. 2. Description of the Related Art Submerged arc welding is a welding method in which powder flux is distributed to a certain thickness on a part to be welded, an electrode wire is inserted into the flux, and an arc is generated between an end of the wire and a base metal. Heat from the generated arc melts the wire, the base metal, and the flux. The melted flux forms slag, and the melted metal forms a welding bead. In submerged arc welding, since the welding arc is generated in the flux, it is not exposed to the exterior. In submerged arc welding, since the flux is not in a melted state at the moment welding starts, current does not flow. Therefore, to facilitate generation of arc, steel wool is inserted between the base metal and the wire, or a high frequency is used. When the arc is generated, fused slag and gas are generated by arc heat, and the arc is continuously maintained. Flux for submerged arc welding may be classified as fused flux or sintered flux depending on the manufacturing method. Fused flux is manufactured by mixing raw materials, melting and cooling them in an electric furnace, and crushing them into a predetermined particle size, thereby creating crushed glass particle shapes. Fused flux has advantages of uniform chemical composition, relatively easy removal of slag, low moisture adsorption facilitating storage and treatment, and consistent particle size and composition upon reuse. However, since fused flux should be formed through a high-temperature melting process, it is impossible to add a deoxidizer or an alloy element. That is, since the necessary alloy element should be supplied from a wire, it is very important to appropriately select the wire in the case of using fused flux. The particle size of the fused flux affects fusibility of the flux, a gas discharge state, a bead shape, and so on. The finer the particles, the higher the current applied to the particles. When high current is applied to large flux particles, it is likely to deteriorate arc protection, make beads rough, and generate defects such as pores and undercuts. Sintered flux is manufactured by crushing raw ore and alloy elements to an appropriate size and mixing them, adding a binder such as sodium silicate to bind them to a certain size, and drying and sintering them within a temperature range in which the raw materials are not dissolved. Since there is little loss of a deoxidizer such as Fe-Si, Fe-Mn, and so on, or an alloying agent such as Ni, Cr, Mo, V, and so on from the sintered flux, it is relatively easy to deoxidize the melted metal, adjust the chemical composition of the deposited metal, and adjust the microstructure of the deposited metal. Therefore, sintered flux is mainly used in high-tensile steel and low alloy steel requiring strong deoxidation or adjustment of chemical composition. On the other hand, sintered flux has disadvantages of relatively easy adsorption, variation in chemical components of the deposited metal in accordance with the welding conditions, variation in the chemical composition of each layer in multilayer welding, difficulty in reuse due to atomization upon first use. Therefore, sintered flux should be carefully selected, treated, stored, and used. Recently, engineers seek to increase welding speed and improve productivity in the construction of steel frames, bridges, pipes, ships, marine structures, and so on, using submerged arc welding. However, when welding at high speed with conventional sintered flux for submerged arc welding, it is difficult to obtain arc stability, pockmark resistance, slag detachability, pit resistance, and bead shape, thus lowering welding workability and productivity. SUMMARY OF THE INVENTION The present invention solves the above problems associated with conventional sintered flux for submerged arc welding by providing sintered flux for submerged arc welding appropriate for mild steel and high tensile steel of 50kgf/mm2, and is capable of obtaining good arc stability, pockmark resistance, slag detachability, pit resistance, and bead shape when used in high-speed welding. In order to accomplish the above objects, sintered flux for submerged arc welding in accordance with an exemplary embodiment of the present invention includes 12.0-24.0wt% SiO2, 24.0-38.0wt% AI2O3, 6.0-13.0wt% TiO2, 2.0- 9.0wt% CaO, 7.0-1 4.0wt% CaF2, 12.0-23.0wt% MnO, 2.0-1 7.0wt% MgO, and 1.0-5.0wt% Na2O, K2O, Li2O or a mixture thereof. Preferably, the sintered flux for submerged arc welding in accordance with the present invention is characterized in that basicity(B) expressed by Formula 1 is within a range of 2.0-6.5. [Formula 1] CaO- Mgf) 2.0, S65 More preferably, the sintered flux for submerged arc welding in accordance with the present invention includes 5.0wt% or less particles larger than 1.00mm, 90.0wt% or more particles of 0.20-1. 00mm, and 5.0wt% or less particles smaller than 0.20mm. Sintered flux for submerged arc welding consisting of: 12.0-24.0wt% SiO2, 24.0-38.0wt% AI2O3, 6.0-13.0wt% TiO2, 2.0-9.0wt% CaO, 7.0-14.0wt% CaF2, 12.0-23.0wt% MnO, 2.0-17.0wt% MgO, and 1.0-5.0wt% Na2O, K2O, Li2O or a mixture thereof. DETAILED DESCRIPTION OF THE INVENTION Hereinafter, each element of the above composition will be described in detail. SiO?:12.0-24.0wt% SiO2 is an acidic component and functions to adjust basicity, viscosity, and melting point of fused slag to make a uniform bead shape. SiO2 may be added as oxide or composite oxide from Quartz (SiO2), Quartz sand (SiO2), Wollastonite (CaSiO3), and so on. When 12.0wt% or less SiO2 is contained in the flux, it is likely to generate meandering beads or undercuts due to insufficient viscosity, irregular bead width, and convex beads due to reduction of diffusion. When 24.0wt% or more SiO2 is contained in the flux, basicity of the fused slag is lowered and oxygen in the deposited metal increases, thus deteriorating toughness. In addition, viscosity increases excessively resulting in irregular beads. : 24.0 - 38.0wt% AI2O3 is a neutral component required for forming slag and adjusting basicity to improve welding workability. AI2O3 functions to adjust viscosity and melting point of slag, and improve arc concentration and stability during high current welding, thereby improving welding workability. When 24.0wt% or less AI2O3 is contained in the flux, the viscosity and melting point are lowered to make the bead width and grain irregular and generate defects such as undercuts. When 38.0wt% or more AI2O3 is contained in the flux, solidification temperature increases, causing bead deterioration, and viscosity also increases to form convex beads or generate slag inclusion. AI2O3 may be derived from sources such as Bauxite (AI2CV2H2O), Aluminum oxide (AI2O3), and so on. TiO?: 6.0-1 3.0wt% TiO2 is an acidic component and a slag generator which functions to transfer Ti into welded metal during welding to improve toughness and slag detachability of the welded metal. When 6.0wt% or less TiO2 is contained in the flux, slag detachability is likely to decrease, toughness of the welded metal is reduced, and undercuts may be formed. In addition, when 13.0wt% or more TiC>2 is contained in the flux, the arc is unstable, causing beads with rough grains. Further, the welded metal contains an excessive amount of Ti, which increases the probability of low-temperature cracks. TiO2 may be derived from sources such as Rutile (T\O2), llmenite (FeTiOs), and so on. CaO: 2.0 - 9.0wt% CaO is a basic component useful in adjusting basicity and viscosity, and reducing oxygen in the welded metal, thereby effectively increasing toughness of the welded metal. When 2.0wt% or less CaO is contained in the flux, there is little effect. When 9.0wt% or more CaO is contained in the flux, bead shape and welding workability are deteriorated to generate pockmarks, and viscosity increases resulting in irregular beads. CaO may be derived from sources such as Wollastonite Dolomite (MgCOa'CaCOa), Anorthite (CaO-AI2O3'2SiO2), and so on. CaF,: 7.0 - 14.0wt% CaF2 is a basic component useful in improving fluidity of slag, and generating fluorine gas to reduce vapor partial pressure, thereby effectively decreasing an amount of hydrogen in the deposited metal. When 7.0wt% or less CaF2 is contained in the flux, there is little effect for shielding the welded metal. When 14.0wt% or more CaF2 is contained in the flux, the arc is unstable and bead shape is deteriorated, gas is generated to produce a rank smell, and pockmarks and undercuts are generated. CaF2 may be derived from sources such as Fluospar (CaF2), and so on. MnO:12.0-23.0wt% MnO is a basic component useful in improving bead shape and adjusting a melting point and viscosity of slag during high-speed welding. When 12.0wt% or less MnO is contained in the flux, there is little effect. When 23.0wt% or more MnO is contained in the flux, CO excessively reacts with a melted part to remarkably deteriorate bead shape or slag detachability. MnO may be derived from sources such as Ferro-Manganese, Manganese oxide (MnO), and so on. MqQ: 2.0 - 17.0wt% MgO is a basic component useful in increasing basicity of the fused slag, and moves hydrogen in the metal into the slag, thereby reducing hydrogen to improve toughness. When 2.0wt% or less MgO is contained in the flux, its effect is insufficient such that the slag is attached to the surface of the welding beads to deteriorate detachability. When 17.0wt% or more MgO is contained in the flux, the arc is unstable to form convex beads, and the melting point of the slag excessively increases, thereby deteriorating detachability. MgO may be derived from sources such as Magnesite (MgCO3), Magnesia clinker (MgO), Dolomite (MgCO3'CaCO3), and so on. NaaO. KaO. LbO. or a mixture thereof: 1.0 - 5.0wt% Na2O, K2O, and Li2O are important components for obtaining arc stability, specifically, maintaining arc stability during high-speed welding. When 1.0wt% or less Na2O, K2O, Li2O, or a mixture thereof is contained in the flux, arc stability is significantly decreased, weld penetration is shortened, and slag inclusion is generated. When 5.0wt% or more Na2O, K2O, Li2O, or a mixture thereof is contained in the flux, convex beads are formed to deteriorate welding workability, and the arc is considerably unstable resulting in reduced moisture adsorption resistance. Na2O, K2O, and Li2O may be derived from sources such as water glass, Cryolite (NasAIFe), Potassium titanate (KjfTiOa), Li-Si, and so on, used to manufacture sintered flux for submerged arc welding. Meanwhile, in addition to flux having the above composition, basicity (B) expressed by Formula 1 is preferably within the range of 2.0-6.5. [Formula 1] 2.0, CaO MgO In Formula 1, CaF2 and MnO are low-melting point chemical components, and CaO and MgO are high-melting point chemical components. That is, the ratio of the sum of CaF2 and MnO (wt%) to the sum of CaO and MgO (wt%) affects the melting point and fluidity of the slag in the sintered flux for submerged arc welding in accordance with the present invention. As a result, welding workability such as arc stability, slag detachability, bead shape, and so on, are largely affected. Therefore, it is possible to limit the range of values of Formula 1 to control a melting point and fluidity of the slag on the basis of an appropriate weight ratio between the low-melting point chemical components and the high-melting point chemical components, thereby obtaining good welding workability, i.e., good arc stability, slag detachability, bead shape, and so on, which is required in the present invention. When the basicity (B), expressed by Formula 1 as the weight ratio of low-melting point chemical components to high-melting point chemical components is smaller than 2.0, the melting point and viscosity of the slag are excessively increased, thus deteriorating bead shape and slag detachability. In addition, pockmarks are likely to be generated. When the basicity (B) is larger than 6.5, arc stability is decreased, thus lowering the melting point of the slag and deteriorating slag detachability. Therefore, in order to obtain sintered flux for submerged arc welding having good welding workability even during high-speed welding, the basicity(B) defined in the present invention should be in the range of 2.0-6.5. In order to obtain welding workability, such as good arc stability, slag detachability, bead shape, and so on, as required in the present invention, the completed flux should have an appropriate particle size distribution. When the flux has an inappropriate particle size distribution, arc protection is deteriorated the beads become rough, and defects such as pores and undercuts are likely generated. An appropriate particle size distribution of the sintered flux for submerged arc welding having the above chemical composition and the basicity (B) may include 5.0wt% or less particles larger than 1.00mm, 90.0wt% or more particles of 0.20-1.00mm, and 5.0wt% or less particles smaller than 0.20mm. When the flux particles larger than 1.00mm are more than 5.0wt%, a space between the particles becomes too large and arc protection is reduced, making the beads rough and readily forming pockmarks. In addition, when the flux particles of 0.20-1.00mm are less than 90.0wt%, convex beads are generated and bead grains become rough. Finally, when the flux particles smaller than 0.20mm are more than 5.0wt%, since gas generated during the submerged arc welding is insufficiently discharged, pockmarks are generated and pits are likely generated. In addition, slag detachability is also deteriorated. Specific welding characteristics of the flux in accordance with the present invention will be understood through the following embodiments. Hereinafter, exemplary embodiments of the present invention will be described in detail, but the following description is not intended to limit the invention in any way. Flux samples having the chemical compositions and basicities listed in the following Table 1 were manufactured. After distributing particles of the flux compositions into a water glass, the water glass was dried and sintered to obtain sintered flux for submerged arc welding having the compositions listed below. "Etc" in Table 1 refers to a mixture of ZrO2, BaO, and FeO, finely contained in each flux composition. n Table 1 n Classification Flux composition, wt% B Si02 AI203 Ti02 CaO CaF2 MnO MgO Na2O,K2O,orLi2O, or mixture thereof Etc Sum IE1 12.0 32.5 10.0 4.0 14.0 18.0 8.0 1.0 0.5 100.6 5.3 IE 2 14.5 27.0 6.0 9.0 10.0 23.0 7.5 2.5 0.5 100.0 4.0 IE 3 21.5 29.0 6.5 5.0 7.0 15.5 12.0 3.0 0.5 100.0 2.6 IE 4 13.0 24.0 8.5 7.0 13.0 16.5 14.0 3.5 0.5 100.0 2.8 IE 5 20.0 30.0 9.0 4.5 9.0 20.0 5.0 1.5 1.0 100.0 6.1 IE 6 24.0 28.5 9.5 3.0 8.5 15.0 5.0 4.0 1.5 100.0 5.2 IE 7 9.0 26.0 13.0 2.0 8.5 12.0 17.0 2.0 0.5 100.0 2.2 IE 8 7.0 38.0 8.0 8.0 7.5 13.0 2.0 5.0 1.5 100.0 4.1 IE 9 23.0 29.0 7.5 3.0 8.0 18.5 9.0 1.5 D.5 100.0 4.4 CE1 26.0 24.0 7.0 1.0 10.0 21.5 B.O 2.0 D.5 100.0 7.0 CE2 20.0 40.0 10.0 5.5 7.0 B.O 5.0 2.5 .0 100.0 2.6 CE3 3.5 25.5 15.0 3.5 11.5 19.5 10.0 D.5 .0 100.0 4.6 CE4 0.0 35.0 6.0 7.5 12.0 20.0 3.0 2.0 .5 100.0 4.7 CE5 5.0 29.5 8.0 4.0 4.5 26.0 11.5 .0 D.5 100.0 3.9 CE6 21.0 20.0 12.0 11.0 9.0 14.0 7.5 4.5 1.0 100.0 2.5 CE7 12.0 26.0 8.5 4.0 8.5 15.0 24.5 1.0 0.5 100.0 1.6 CE8 17.5 27.5 3.o 6.0 9.5 16.5 12.0 7.0 1.0 100.0 2.9 CE9 18.0 25.0 7.0 4.5 17.0 23.0 1.0 4.0 0.5 100.0 14.5 IE = Invention example, CE = Comparative example Welding of a welding wire of Table 3 below to a base metal of Table 2 below was performed using the flux compositions listed in Table 1. Welding conditions are listed in Table 4 below, and welding workability evaluation results are arranged in Tables 5 to 7 below. Tables 5 to 7 list test results of welding workability at welding speeds of 100cm/min, 150cm/min, and 200cm/min, and the same polarity, current, and voltage. Symbols appearing in Tables 5 to 7 have the following meanings: o: good, D: normal, : poor n Table 2n Steel Thickness (mm) Chemical composition of base metal, wt% C Si »\/ln D S SM490 25 0.14 0.34 1.30 0.008 0.010 n Table 3n Wire diameter (mm) Chemical composition of wire, wt% C Si Mn D S 4.8 0.06 0.31 1.10 0.018 0.008 n Table 4n Polarity Current[A] Voltage[V] Speed(cm/min) Note 1 2 3 AC 750 34 100 150 Bead on plate 200 welding nTable 5n Welding conditions: AC 750A-34V-100cm/min. Classification Arc stability Pockmark resistance Slag Detachability Pit resistance Bead shape IE1 o o o o o IE 2 0 o o o o IE 3 o o o o o IE 4 o o o o 0 IE 5 o o o o o IE 6 o o o o o IE 7 o o o o o IE 8 o o o o o IE 9 o o o o o CE1 n n n o n CE2 o D o o n CE3 n D o o D CE4 o D D 0 3 CE5 0 H n o n CE6 H D o n CE7 o D D o D CE8 D o D D 0 CE9 n X D o n n Table 6 n Welding conditions: AC 750A-34V-150cm/min. Classification Arc stability Pockmark resistance Slag Detachability Pit resistance Bead shape IE1 o o o o o IE 2 o o o o o IE 3 o o o o o IE 4 o o o o o IE 5 0 o 0 o o IE 6 o o o o o IE 7 0 o o o o IE 8 o o o o o IE 9 o o o o o CE1 n X D n CE2 o O n o n CE3 n 0 o 3 * CE4 o 3 o 3 X CE5 o 1 X D 1 CE6 o o 1 CE7 o * n 3 CE8 D 0 X D o CE9 X X D 0 D D Table 7n Welding conditions: AC 750A-34V-200cm/min. Classification Arc stability Pockmark resistance Slag Detachability Pit resistance Bead shape IE1 o o ~ o [ " 0 o IE 2 o o o o o IE 3 o o o o o IE 4 o o o o o IE 5 o o o o o IE 6 o o o o o IE 7 o o o o o IE 8 o o o 0 0 IE 9 o o o o o CE1 X X X o n CE2 o 0 D o X CE3 X o o o X CE4 o o o o X CE5 0 n X o X CE6 o X o o X CE7 o X n n X CE8 X 0 X D o CE9 X X X o n Referring to Tables 5 to 7, it will be appreciated that the Exemplary Embodiments of the present invention have good welding workability, i.e., arc stability, pockmark resistance, slag detachability, pit resistance, bead shape, and so on, even when welding speed is increased. Meanwhile, in the case of Comparative Example 1, since SiO2 content is higher than the range of the present invention, CaO content is lower than the range of the present invention, and the basicity(B) as defined herein is higher than the range of the present invention, Table 5 does not list good results in arc stability, pockmark resistance, slag detachability, and bead shape at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, pockmark resistance and slag detachability are further deteriorated. And, Table 7 shows that when welding speed is further increased to 200cm/min, arc stability is also deteriorated. In the case of Comparative Example 2, since AI2O3 content is higher than the range of the present invention, and MnO content is lower than the range of the present invention, Table 5 does not list good results for bead shape at a welding speed of 100cm/min. Moreover, Table 6 shows that when welding speed is increased to 150cm/min, slag detachability becomes poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, bead shape further deteriorates. In the case of Comparative Example 3, since TiO2 content is higher than the range of the present invention, and content of Na2O, K2O, Li2O, or a mixture thereof is lower than the range of the present invention, Table 5 does not list good results for arc stability and bead shape at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, bead shape results are poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, arc stability deteriorates. In the case of Comparative Example 4, since SiO2 content is lower than the range of the present invention, Table 5 does not list good results for bead shape at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, bead shape results are poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, bead shape remains poor. In the case of Comparative Example 5, since CaF2 content is lower than the range of the present invention, and MnO content is higher than the range of the present invention, Table 5 does not list good results for pockmark resistance, slag detachability, and bead shape at a welding speed of 100cm/min. Further, Table 6 shows that when welding speed is increased to 150cm/min, slag detachability further deteriorates, and Table 7 indicates that when welding speed is further increased to 200cm/min, bead shape deteriorates. In the case of Comparative Example 6, since AI2O3 content is lower than the range of the present invention, and CaO content is higher than the range of the present invention, Table 5 does not list good results for pockmark resistance, and bead shape at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, pockmark resistance is poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, bead shape also deteriorates. In the case of Comparative Example 7, since MgO content is higher than the range of the present invention, and basicity(B) as defined herein is lower than the range of the present invention, Table 5 does not list good results for pockmark resistance, slag detachability, and bead shape at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, pockmark resistance is poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, pit resistance and bead shape deteriorate. In the case of Comparative Example 8, since TiO2 content is lower than the range of the present invention, and content of Na2O, K2O, Li2O, or a mixture thereof is higher than the range of the present invention, Table 5 does not list good results for arc stability, slag detachability, and pit resistance at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, slag detachability is poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, arc stability deteriorates. In the case of Comparative Example 9, since CaF2 content is higher than the range of the present invention, MgO content is lower than the range of the present invention, and basicity(B) as defined herein is higher than the range of the present invention, Table 5 does not list good results for arc stability, slag detachability, bead shape, and pockmark resistance at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, arc stability is poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, slag detachability deteriorates. The sintered flux for submerged arc welding of Exemplary Embodiment 1 of Table 1, whose basicity (B) satisfies 2.0 s B = 2(CaF2+MnO)/(CaO+MgO) £ 6.5, was divided into eight flux particle size distributions listed in Table 8. Welding workability evaluation results of the sintered flux for submerged arc welding having the particle size distributions of Table 8 are listed in Table 9. Welding conditions were AC 750A-34V-100cm/min. Symbols used in Table 9 have the following meanings: o: good, D: normal, x; poor. DTable 8D Classification Particle size distribution, wt% 1.00mm or more 1.00mm -0.20mm 0.20mm or less Sum IE 10 5.0 90.0 6.0 100.0 IE 11 1.0 95.0 4.0 100.0 IE 12 4.0 95.5 0.5 100.0 IE 13 3.0 93.0 4.0 100.0 CE10 b.o 91.0 3.0 100.0 CE11 2.5 90.5 7.0 100.0 CE12 10.0 85.0 5.0 100.0 CE13 e.o 80.0 15.0 100.0 nTable 9n Classification Arc Stability __^_j Pockmark resistance Slag pit detachability resistance Bead shape IE 10 0 o o o o IE 11 o o o o o IE 12 o o o o o IE 13 o o o o o CE10 X X o o X CE11 0 X o X o CE12 X X X 0 X CE13 o X X X X Referring to Tables 8 and 9, it will be appreciated that the present invention provides good arc stability, pockmark resistance, slag detachability, pit resistance, and bead shape when the sintered flux for submerged arc welding includes 5.0wt% or less particles larger than 1.00mm, 90.0wt% or more particles of 0.20-1.00mm, and 5.0wt% or less particles smaller than 0.20mm. Meanwhile, in the case of Comparative Example 10 of Table 8, since the content of particles larger than 1.00mm is higher than the range of the present invention, Table 9 shows poor results for arc stability, pockmark resistance, and bead shape. In the case of Comparative Example 1 1 of Table 8, since the content of particles smaller than 0.20mm is higher than the range of the present invention, Table 9 shows poor results for pockmark resistance and pit resistance. In the case of Comparative Example 12 of Table 8, since the content of particles larger than 1.0mm is higher than the range of the present invention, and the content of particles of 0.20mm-1.00mm is lower than the range of the present invention, Table 9 lists poor results for arc stability, pockmark resistance, slag detachability, and bead shape. In the case of Comparative Example 13 of Table 8, since the content of particles of 0.20mm-1.00mm is lower than the range of the present invention, and the content of particles smaller than 0.20mm is higher than the range of the present invention, Table 9 lists poor results for the pockmark resistance, slag detachability, pit resistance, and bead shape. As can be seen from the foregoing, the present invention provides a chemical composition used in sintered flux for submerged arc welding whose basicity (B) satisfies 2.Q less particles larger than 1.00mm, 90.0wt% or more particles of 0.20-1. 00mm, and 5.0wt% or less particles smaller than 0.20mm. Accordingly, it is possible to obtain sintered flux for submerged arc welding having good welding workability, i.e., arc stability, pockmark resistance, slag detachability, pit resistance, and bead shape, even when welding speed is increased. Although the present invention has been described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that a variety of modifications and variations may be made to the present invention without departing from the spirit or scope of the present invention defined in the appended claims, and their equivalents. WE CLAIM: 1. Sintered flux for submerged arc welding consisting of: 12.0-24.0wt% SiO2, 24.0-38.0wt% Al2O3, 6.0-13.0wt% TiO2, 2.0-9.0wt% CaO, 7.0-14.0wt% CaF2, 12.0-23.0wt% MnO, 2.0-17.0wt% MgO, and 1.0-5.0wt% Na2O, K2O, Li2O or a mixture thereof, wherein the sintered flux comprises 5.0wt% or less particles larger than 1.00mm, 90.0wt% or more particles of 0.20-1.00mm, and 5.0wt% or less particles smaller than 0.20mm 2. The sintered flux for submerged arc welding according to claim 1, wherein basicity (B) of the sintered flux satisfies the following Formula 1: [Formula 1] (Formula Removed)

Full Text

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to sintered flux for submerged arc welding, and more particularly, to sintered flux for submerged arc welding of mild steel and high tensile steel of 50kgf/mm2 used in steel frames, bridges, pipes, ships, marine structures, and so on, the sintered flux is capable of obtaining good arc stability, pockmark resistance, slag detachability, pit resistance, and bead shape when used in high-speed welding.
2. Description of the Related Art
Submerged arc welding is a welding method in which powder flux is distributed to a certain thickness on a part to be welded, an electrode wire is inserted into the flux, and an arc is generated between an end of the wire and a base metal. Heat from the generated arc melts the wire, the base metal, and the flux. The melted flux forms slag, and the melted metal forms a welding bead. In submerged arc welding, since the welding arc is generated in the flux, it is not exposed to the exterior.
In submerged arc welding, since the flux is not in a melted state at the moment welding starts, current does not flow. Therefore, to facilitate generation of arc, steel wool is inserted between the base metal and the wire, or a high frequency is used. When the arc is generated, fused slag and gas are generated by arc heat, and the arc is continuously maintained.
Flux for submerged arc welding may be classified as fused flux or sintered flux depending on the manufacturing method. Fused flux is

manufactured by mixing raw materials, melting and cooling them in an electric furnace, and crushing them into a predetermined particle size, thereby creating crushed glass particle shapes. Fused flux has advantages of uniform chemical composition, relatively easy removal of slag, low moisture adsorption facilitating storage and treatment, and consistent particle size and composition upon reuse.
However, since fused flux should be formed through a high-temperature melting process, it is impossible to add a deoxidizer or an alloy element. That is, since the necessary alloy element should be supplied from a wire, it is very important to appropriately select the wire in the case of using fused flux. The particle size of the fused flux affects fusibility of the flux, a gas discharge state, a bead shape, and so on. The finer the particles, the higher the current applied to the particles.
When high current is applied to large flux particles, it is likely to deteriorate arc protection, make beads rough, and generate defects such as pores and undercuts.
Sintered flux is manufactured by crushing raw ore and alloy elements to an appropriate size and mixing them, adding a binder such as sodium silicate to bind them to a certain size, and drying and sintering them within a temperature range in which the raw materials are not dissolved. Since there is little loss of a deoxidizer such as Fe-Si, Fe-Mn, and so on, or an alloying agent such as Ni, Cr, Mo, V, and so on from the sintered flux, it is relatively easy to deoxidize the melted metal, adjust the chemical composition of the deposited metal, and adjust the microstructure of the deposited metal.

Therefore, sintered flux is mainly used in high-tensile steel and low alloy steel requiring strong deoxidation or adjustment of chemical composition. On the other hand, sintered flux has disadvantages of relatively easy adsorption, variation in chemical components of the deposited metal in accordance with the welding conditions, variation in the chemical composition of each layer in multilayer welding, difficulty in reuse due to atomization upon first use. Therefore, sintered flux should be carefully selected, treated, stored, and used.
Recently, engineers seek to increase welding speed and improve productivity in the construction of steel frames, bridges, pipes, ships, marine structures, and so on, using submerged arc welding. However, when welding at high speed with conventional sintered flux for submerged arc welding, it is difficult to obtain arc stability, pockmark resistance, slag detachability, pit resistance, and bead shape, thus lowering welding workability and productivity.
SUMMARY OF THE INVENTION
The present invention solves the above problems associated with conventional sintered flux for submerged arc welding by providing sintered flux for submerged arc welding appropriate for mild steel and high tensile steel of 50kgf/mm2, and is capable of obtaining good arc stability, pockmark resistance, slag detachability, pit resistance, and bead shape when used in high-speed welding.
In order to accomplish the above objects, sintered flux for submerged arc welding in accordance with an exemplary embodiment of the present invention includes 12.0-24.0wt% SiO2, 24.0-38.0wt% AI2O3, 6.0-13.0wt% TiO2, 2.0-

9.0wt% CaO, 7.0-1 4.0wt% CaF2, 12.0-23.0wt% MnO, 2.0-1 7.0wt% MgO, and 1.0-5.0wt% Na2O, K2O, Li2O or a mixture thereof.
Preferably, the sintered flux for submerged arc welding in accordance with the present invention is characterized in that basicity(B) expressed by Formula 1 is within a range of 2.0-6.5. [Formula 1]
CaO- Mgf)
2.0, S65
More preferably, the sintered flux for submerged arc welding in accordance with the present invention includes 5.0wt% or less particles larger than 1.00mm, 90.0wt% or more particles of 0.20-1. 00mm, and 5.0wt% or less particles smaller than 0.20mm.
Sintered flux for submerged arc welding consisting of: 12.0-24.0wt% SiO2, 24.0-38.0wt% AI2O3, 6.0-13.0wt% TiO2, 2.0-9.0wt% CaO, 7.0-14.0wt% CaF2, 12.0-23.0wt% MnO, 2.0-17.0wt% MgO, and 1.0-5.0wt% Na2O, K2O, Li2O or a mixture thereof.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, each element of the above composition will be described in detail.
SiO?:12.0-24.0wt%
SiO2 is an acidic component and functions to adjust basicity, viscosity, and melting point of fused slag to make a uniform bead shape.

SiO2 may be added as oxide or composite oxide from Quartz (SiO2), Quartz sand (SiO2), Wollastonite (CaSiO3), and so on.
When 12.0wt% or less SiO2 is contained in the flux, it is likely to generate meandering beads or undercuts due to insufficient viscosity, irregular bead width, and convex beads due to reduction of diffusion. When 24.0wt% or more SiO2 is contained in the flux, basicity of the fused slag is lowered and oxygen in the deposited metal increases, thus deteriorating toughness. In addition, viscosity increases excessively resulting in irregular beads.
: 24.0 - 38.0wt%
AI2O3 is a neutral component required for forming slag and adjusting basicity to improve welding workability. AI2O3 functions to adjust viscosity and melting point of slag, and improve arc concentration and stability during high current welding, thereby improving welding workability.
When 24.0wt% or less AI2O3 is contained in the flux, the viscosity and melting point are lowered to make the bead width and grain irregular and generate defects such as undercuts. When 38.0wt% or more AI2O3 is contained in the flux, solidification temperature increases, causing bead deterioration, and viscosity also increases to form convex beads or generate slag inclusion.
AI2O3 may be derived from sources such as Bauxite (AI2CV2H2O), Aluminum oxide (AI2O3), and so on.
TiO?: 6.0-1 3.0wt%

TiO2 is an acidic component and a slag generator which functions to transfer Ti into welded metal during welding to improve toughness and slag detachability of the welded metal.
When 6.0wt% or less TiO2 is contained in the flux, slag detachability is likely to decrease, toughness of the welded metal is reduced, and undercuts may be formed. In addition, when 13.0wt% or more TiC>2 is contained in the flux, the arc is unstable, causing beads with rough grains. Further, the welded metal contains an excessive amount of Ti, which increases the probability of low-temperature cracks.
TiO2 may be derived from sources such as Rutile (T\O2), llmenite (FeTiOs), and so on.
CaO: 2.0 - 9.0wt%
CaO is a basic component useful in adjusting basicity and viscosity, and reducing oxygen in the welded metal, thereby effectively increasing toughness of the welded metal.
When 2.0wt% or less CaO is contained in the flux, there is little effect. When 9.0wt% or more CaO is contained in the flux, bead shape and welding workability are deteriorated to generate pockmarks, and viscosity increases resulting in irregular beads.
CaO may be derived from sources such as Wollastonite Dolomite (MgCOa'CaCOa), Anorthite (CaO-AI2O3'2SiO2), and so on.
CaF,: 7.0 - 14.0wt%

CaF2 is a basic component useful in improving fluidity of slag, and generating fluorine gas to reduce vapor partial pressure, thereby effectively decreasing an amount of hydrogen in the deposited metal.
When 7.0wt% or less CaF2 is contained in the flux, there is little effect for shielding the welded metal. When 14.0wt% or more CaF2 is contained in the flux, the arc is unstable and bead shape is deteriorated, gas is generated to produce a rank smell, and pockmarks and undercuts are generated.
CaF2 may be derived from sources such as Fluospar (CaF2), and so on.
MnO:12.0-23.0wt%
MnO is a basic component useful in improving bead shape and adjusting a melting point and viscosity of slag during high-speed welding.
When 12.0wt% or less MnO is contained in the flux, there is little effect. When 23.0wt% or more MnO is contained in the flux, CO excessively reacts with a melted part to remarkably deteriorate bead shape or slag detachability.
MnO may be derived from sources such as Ferro-Manganese, Manganese oxide (MnO), and so on.
MqQ: 2.0 - 17.0wt%
MgO is a basic component useful in increasing basicity of the fused slag, and moves hydrogen in the metal into the slag, thereby reducing hydrogen to improve toughness.
When 2.0wt% or less MgO is contained in the flux, its effect is insufficient such that the slag is attached to the surface of the welding beads to deteriorate

detachability. When 17.0wt% or more MgO is contained in the flux, the arc is unstable to form convex beads, and the melting point of the slag excessively increases, thereby deteriorating detachability.
MgO may be derived from sources such as Magnesite (MgCO3), Magnesia clinker (MgO), Dolomite (MgCO3'CaCO3), and so on.
NaaO. KaO. LbO. or a mixture thereof: 1.0 - 5.0wt%
Na2O, K2O, and Li2O are important components for obtaining arc stability, specifically, maintaining arc stability during high-speed welding.
When 1.0wt% or less Na2O, K2O, Li2O, or a mixture thereof is contained in the flux, arc stability is significantly decreased, weld penetration is shortened, and slag inclusion is generated. When 5.0wt% or more Na2O, K2O, Li2O, or a mixture thereof is contained in the flux, convex beads are formed to deteriorate welding workability, and the arc is considerably unstable resulting in reduced moisture adsorption resistance.
Na2O, K2O, and Li2O may be derived from sources such as water glass, Cryolite (NasAIFe), Potassium titanate (KjfTiOa), Li-Si, and so on, used to manufacture sintered flux for submerged arc welding.
Meanwhile, in addition to flux having the above composition, basicity (B) expressed by Formula 1 is preferably within the range of 2.0-6.5.
[Formula 1]

2.0,

CaO MgO

In Formula 1, CaF2 and MnO are low-melting point chemical components, and CaO and MgO are high-melting point chemical components. That is, the ratio of the sum of CaF2 and MnO (wt%) to the sum of CaO and MgO (wt%) affects the melting point and fluidity of the slag in the sintered flux for submerged arc welding in accordance with the present invention. As a result, welding workability such as arc stability, slag detachability, bead shape, and so on, are largely affected. Therefore, it is possible to limit the range of values of Formula 1 to control a melting point and fluidity of the slag on the basis of an appropriate weight ratio between the low-melting point chemical components and the high-melting point chemical components, thereby obtaining good welding workability, i.e., good arc stability, slag detachability, bead shape, and so on, which is required in the present invention.
When the basicity (B), expressed by Formula 1 as the weight ratio of low-melting point chemical components to high-melting point chemical components is smaller than 2.0, the melting point and viscosity of the slag are excessively increased, thus deteriorating bead shape and slag detachability. In addition, pockmarks are likely to be generated. When the basicity (B) is larger than 6.5, arc stability is decreased, thus lowering the melting point of the slag and deteriorating slag detachability.
Therefore, in order to obtain sintered flux for submerged arc welding having good welding workability even during high-speed welding, the basicity(B) defined in the present invention should be in the range of 2.0-6.5.
In order to obtain welding workability, such as good arc stability, slag detachability, bead shape, and so on, as required in the present invention, the

completed flux should have an appropriate particle size distribution. When the flux has an inappropriate particle size distribution, arc protection is deteriorated the beads become rough, and defects such as pores and undercuts are likely generated.
An appropriate particle size distribution of the sintered flux for submerged arc welding having the above chemical composition and the basicity (B) may include 5.0wt% or less particles larger than 1.00mm, 90.0wt% or more particles of 0.20-1.00mm, and 5.0wt% or less particles smaller than 0.20mm.
When the flux particles larger than 1.00mm are more than 5.0wt%, a space between the particles becomes too large and arc protection is reduced, making the beads rough and readily forming pockmarks.
In addition, when the flux particles of 0.20-1.00mm are less than 90.0wt%, convex beads are generated and bead grains become rough.
Finally, when the flux particles smaller than 0.20mm are more than 5.0wt%, since gas generated during the submerged arc welding is insufficiently discharged, pockmarks are generated and pits are likely generated. In addition, slag detachability is also deteriorated.
Specific welding characteristics of the flux in accordance with the present invention will be understood through the following embodiments.
Hereinafter, exemplary embodiments of the present invention will be described in detail, but the following description is not intended to limit the invention in any way.
Flux samples having the chemical compositions and basicities listed in the following Table 1 were manufactured. After distributing particles of the flux

compositions into a water glass, the water glass was dried and sintered to obtain sintered flux for submerged arc welding having the compositions listed below.
"Etc" in Table 1 refers to a mixture of ZrO2, BaO, and FeO, finely contained in each flux composition. n Table 1 n

Classification Flux composition, wt% B

Si02 AI203 Ti02 CaO CaF2 MnO MgO Na2O,K2O,orLi2O, or mixture thereof Etc Sum

*IE1 12.0 32.5 10.0 4.0 14.0 18.0 8.0 1.0 0.5 100.6 5.3
IE 2 14.5 27.0 6.0 9.0 10.0 23.0 7.5 2.5 0.5 100.0 4.0
IE 3 21.5 29.0 6.5 5.0 7.0 15.5 12.0 3.0 0.5 100.0 2.6
IE 4 13.0 24.0 8.5 7.0 13.0 16.5 14.0 3.5 0.5 100.0 2.8
IE 5 20.0 30.0 9.0 4.5 9.0 20.0 5.0 1.5 1.0 100.0 6.1
IE 6 24.0 28.5 9.5 3.0 8.5 15.0 5.0 4.0 1.5 100.0 5.2
IE 7 9.0 26.0 13.0 2.0 8.5 12.0 17.0 2.0 0.5 100.0 2.2
IE 8 7.0 38.0 8.0 8.0 7.5 13.0 2.0 5.0 1.5 100.0 4.1
IE 9 23.0 29.0 7.5 3.0 8.0 18.5 9.0 1.5 D.5 100.0 4.4
*CE1 26.0 24.0 7.0 1.0 10.0 21.5 B.O 2.0 D.5 100.0 7.0
CE2 20.0 40.0 10.0 5.5 7.0 B.O 5.0 2.5 .0 100.0 2.6
CE3 3.5 25.5 15.0 3.5 11.5 19.5 10.0 D.5 .0 100.0 4.6
CE4 0.0 35.0 6.0 7.5 12.0 20.0 3.0 2.0 .5 100.0 4.7
CE5 5.0 29.5 8.0 4.0 4.5 26.0 11.5 .0 D.5 100.0 3.9

CE6 21.0 20.0 12.0 11.0 9.0 14.0 7.5 4.5 1.0 100.0 2.5
CE7 12.0 26.0 8.5 4.0 8.5 15.0 24.5 1.0 0.5 100.0 1.6
CE8 17.5 27.5 3.o 6.0 9.5 16.5 12.0 7.0 1.0 100.0 2.9
CE9 18.0 25.0 7.0 4.5 17.0 23.0 1.0 4.0 0.5 100.0 14.5
*IE = Invention example, *CE = Comparative example
Welding of a welding wire of Table 3 below to a base metal of Table 2 below was performed using the flux compositions listed in Table 1.
Welding conditions are listed in Table 4 below, and welding workability evaluation results are arranged in Tables 5 to 7 below. Tables 5 to 7 list test results of welding workability at welding speeds of 100cm/min, 150cm/min, and 200cm/min, and the same polarity, current, and voltage. Symbols appearing in Tables 5 to 7 have the following meanings: o: good, D: normal, *: poor
n Table 2n

Steel Thickness (mm) Chemical composition of base metal, wt%

C Si »\/ln D S
SM490 25 0.14 0.34 1.30 0.008 0.010
n Table 3n

Wire diameter (mm) Chemical composition of wire, wt%

C Si Mn D S
4.8 0.06 0.31 1.10 0.018 0.008
n Table 4n

Polarity Current[A] Voltage[V] Speed(cm/min) Note

1 2 3

AC 750 34 100 150 Bead on plate 200 welding
nTable 5n
Welding conditions: AC 750A-34V-100cm/min.

Classification Arc stability Pockmark resistance Slag Detachability Pit resistance Bead shape
IE1 o o o o o
IE 2 0 o o o o
IE 3 o o o o o
IE 4 o o o o 0
IE 5 o o o o o
IE 6 o o o o o
IE 7 o o o o o
IE 8 o o o o o
IE 9 o o o o o
CE1 n n n o n
CE2 o D o o n
CE3 n D o o D
CE4 o D D 0 3
CE5 0 H n o n
CE6 H D o n

CE7 o D D o D
CE8 D o D D 0
CE9 n X D o n
n Table 6 n
Welding conditions: AC 750A-34V-150cm/min.

Classification Arc stability Pockmark resistance Slag Detachability Pit resistance Bead shape
IE1 o o o o o
IE 2 o o o o o
IE 3 o o o o o
IE 4 o o o o o
IE 5 0 o 0 o o
IE 6 o o o o o
IE 7 0 o o o o
IE 8 o o o o o
IE 9 o o o o o
CE1 n * X D n
CE2 o O n o n
CE3 n 0 o 3 *
CE4 o 3 o 3 X
CE5 o 1 X D 1
CE6 o o 1
CE7 o * n 3

CE8 D 0 X D o
CE9 X X D 0 D
D Table 7n
Welding conditions: AC 750A-34V-200cm/min.

Classification Arc stability Pockmark resistance Slag Detachability Pit
resistance Bead shape
IE1 o o ~ o [ "
0 o
IE 2 o o o o o
IE 3 o o o o o
IE 4 o o o o o
IE 5 o o o o o
IE 6 o o o o o
IE 7 o o o o o
IE 8 o o o 0 0
IE 9 o o o o o
CE1 X X X o n
CE2 o 0 D o X
CE3 X o o o X
CE4 o o o o X
CE5 0 n X o X

CE6 o X o o X
CE7 o X n n X
CE8 X 0 X D o
CE9 X X X o n
Referring to Tables 5 to 7, it will be appreciated that the Exemplary Embodiments of the present invention have good welding workability, i.e., arc stability, pockmark resistance, slag detachability, pit resistance, bead shape, and so on, even when welding speed is increased.
Meanwhile, in the case of Comparative Example 1, since SiO2 content is higher than the range of the present invention, CaO content is lower than the range of the present invention, and the basicity(B) as defined herein is higher than the range of the present invention, Table 5 does not list good results in arc stability, pockmark resistance, slag detachability, and bead shape at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, pockmark resistance and slag detachability are further deteriorated. And, Table 7 shows that when welding speed is further increased to 200cm/min, arc stability is also deteriorated.
In the case of Comparative Example 2, since AI2O3 content is higher than the range of the present invention, and MnO content is lower than the range of the present invention, Table 5 does not list good results for bead shape at a welding speed of 100cm/min. Moreover, Table 6 shows that when welding speed is increased to 150cm/min, slag detachability becomes poor, and Table 7

indicates that when welding speed is further increased to 200cm/min, bead shape further deteriorates.
In the case of Comparative Example 3, since TiO2 content is higher than the range of the present invention, and content of Na2O, K2O, Li2O, or a mixture thereof is lower than the range of the present invention, Table 5 does not list good results for arc stability and bead shape at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, bead shape results are poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, arc stability deteriorates.
In the case of Comparative Example 4, since SiO2 content is lower than the range of the present invention, Table 5 does not list good results for bead shape at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, bead shape results are poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, bead shape remains poor.
In the case of Comparative Example 5, since CaF2 content is lower than the range of the present invention, and MnO content is higher than the range of the present invention, Table 5 does not list good results for pockmark resistance, slag detachability, and bead shape at a welding speed of 100cm/min. Further, Table 6 shows that when welding speed is increased to 150cm/min, slag detachability further deteriorates, and Table 7 indicates that when welding speed is further increased to 200cm/min, bead shape deteriorates.
In the case of Comparative Example 6, since AI2O3 content is lower than the range of the present invention, and CaO content is higher than the range of

the present invention, Table 5 does not list good results for pockmark resistance, and bead shape at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, pockmark resistance is poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, bead shape also deteriorates.
In the case of Comparative Example 7, since MgO content is higher than the range of the present invention, and basicity(B) as defined herein is lower than the range of the present invention, Table 5 does not list good results for pockmark resistance, slag detachability, and bead shape at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, pockmark resistance is poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, pit resistance and bead shape deteriorate.
In the case of Comparative Example 8, since TiO2 content is lower than the range of the present invention, and content of Na2O, K2O, Li2O, or a mixture thereof is higher than the range of the present invention, Table 5 does not list good results for arc stability, slag detachability, and pit resistance at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, slag detachability is poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, arc stability deteriorates.
In the case of Comparative Example 9, since CaF2 content is higher than the range of the present invention, MgO content is lower than the range of the present invention, and basicity(B) as defined herein is higher than the range of the present invention, Table 5 does not list good results for arc stability, slag

detachability, bead shape, and pockmark resistance at a welding speed of 100cm/min. In addition, Table 6 shows that when welding speed is increased to 150cm/min, arc stability is poor, and Table 7 indicates that when welding speed is further increased to 200cm/min, slag detachability deteriorates.
The sintered flux for submerged arc welding of Exemplary Embodiment 1 of Table 1, whose basicity (B) satisfies 2.0 s B = 2(CaF2+MnO)/(CaO+MgO) £ 6.5, was divided into eight flux particle size distributions listed in Table 8. Welding workability evaluation results of the sintered flux for submerged arc welding having the particle size distributions of Table 8 are listed in Table 9. Welding conditions were AC 750A-34V-100cm/min.
Symbols used in Table 9 have the following meanings: o: good, D: normal, x; poor.
DTable 8D

Classification Particle size distribution, wt%

1.00mm or more 1.00mm -0.20mm 0.20mm or less Sum
IE 10 5.0 90.0 6.0 100.0
IE 11 1.0 95.0 4.0 100.0
IE 12 4.0 95.5 0.5 100.0
IE 13 3.0 93.0 4.0 100.0
CE10 b.o 91.0 3.0 100.0
CE11 2.5 90.5 7.0 100.0

CE12 10.0 85.0 5.0 100.0
CE13 e.o 80.0 15.0 100.0
nTable 9n

Classification Arc
Stability
__^_j Pockmark resistance Slag pit detachability resistance Bead shape
IE 10 0 o o o o
IE 11 o o o o o
IE 12 o o o o o
IE 13 o o o o o
CE10 X X o o X
CE11 0 X o X o
CE12 X X X 0 X
CE13 o X X X X
Referring to Tables 8 and 9, it will be appreciated that the present invention provides good arc stability, pockmark resistance, slag detachability, pit resistance, and bead shape when the sintered flux for submerged arc welding includes 5.0wt% or less particles larger than 1.00mm, 90.0wt% or more particles of 0.20-1.00mm, and 5.0wt% or less particles smaller than 0.20mm.
Meanwhile, in the case of Comparative Example 10 of Table 8, since the content of particles larger than 1.00mm is higher than the range of the present invention, Table 9 shows poor results for arc stability, pockmark resistance, and bead shape.

In the case of Comparative Example 1 1 of Table 8, since the content of particles smaller than 0.20mm is higher than the range of the present invention, Table 9 shows poor results for pockmark resistance and pit resistance.
In the case of Comparative Example 12 of Table 8, since the content of particles larger than 1.0mm is higher than the range of the present invention, and the content of particles of 0.20mm-1.00mm is lower than the range of the present invention, Table 9 lists poor results for arc stability, pockmark resistance, slag detachability, and bead shape.
In the case of Comparative Example 13 of Table 8, since the content of particles of 0.20mm-1.00mm is lower than the range of the present invention, and the content of particles smaller than 0.20mm is higher than the range of the present invention, Table 9 lists poor results for the pockmark resistance, slag detachability, pit resistance, and bead shape.
As can be seen from the foregoing, the present invention provides a chemical composition used in sintered flux for submerged arc welding whose basicity (B)
satisfies 2.Q less particles larger than 1.00mm, 90.0wt% or more particles of 0.20-1. 00mm, and 5.0wt% or less particles smaller than 0.20mm. Accordingly, it is possible to obtain sintered flux for submerged arc welding having good welding workability, i.e., arc stability, pockmark resistance, slag detachability, pit resistance, and
bead shape, even when welding speed is increased.
Although the present invention has been described with reference to

certain exemplary embodiments thereof, it will be understood by those skilled in the art that a variety of modifications and variations may be made to the present invention without departing from the spirit or scope of the present invention defined in the appended claims, and their equivalents.

WE CLAIM:
1. Sintered flux for submerged arc welding consisting of: 12.0-24.0wt%
SiO2, 24.0-38.0wt% Al2O3, 6.0-13.0wt% TiO2, 2.0-9.0wt% CaO, 7.0-14.0wt%
CaF2, 12.0-23.0wt% MnO, 2.0-17.0wt% MgO, and 1.0-5.0wt% Na2O, K2O, Li2O
or a mixture thereof, wherein the sintered flux comprises 5.0wt% or less particles
larger than 1.00mm, 90.0wt% or more particles of 0.20-1.00mm, and 5.0wt% or
less particles smaller than 0.20mm
2. The sintered flux for submerged arc welding according to claim 1,
wherein basicity (B) of the sintered flux satisfies the following Formula 1:
[Formula 1]
(Formula Removed)

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=JBgw3lhkRCnPOR30GmrcSQ==&loc=+mN2fYxnTC4l0fUd8W4CAA==

« Previous Patent

Next Patent »

Patent Number

277983

Indian Patent Application Number

2149/DEL/2006

PG Journal Number

51/2016

Publication Date

09-Dec-2016

Grant Date

07-Dec-2016

Date of Filing

28-Sep-2006

Name of Patentee

KISWEL LTD

Applicant Address

721-3 HAKJANG-DONG SASANG-GU BUSAN 617-843 KOREA

Inventors:

#	Inventor's Name	Inventor's Address
1	NOH, TAE HOON	58-2 SEONGIU DONG, CHANGWONSI GYEONGNAM 641-120 KOREA

PCT International Classification Number

B23K35/38

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10-2005-0109937	2005-11-17	Republic of Korea