KR100615686B1 - A metal cored wire with superior low temperature toughness - Google Patents

Abstract

The present invention relates to a metal-based flux filling wire.

The present invention, in weight% to the wire, C: 0.01 ~ 0.05%, Si: 0.6 ~ 1.2%, Mn: 1.6 ~ 3.2%, at least one selected from the group consisting of Al, Ti, Mg and Zr: 0.1 ~ Iron with 0.5% and S content of 0.08 ~ 0.12%: 10 ~ 20%, plus fluoride 0.02 ~ 0.2% in F, 0.01 ~ 0.1% CO ₂ + CO ₃ It consists of a metal type flux filling wire which contains a containing compound and is excellent in low-temperature toughness which consists of remaining Fe and an unavoidable impurity.

The present invention can provide a metal-based flux filling wire that can ensure high temperature crack resistance and impact toughness at low temperatures.

Low temperature toughness, high temperature crack resistance, flux-filled wire, carbonic acid, fluoride, S content

Description

A metal cored wire with superior low temperature toughness

The present invention relates to a metal-based flux-filled wire used for welding steel sheets for mild steel and 50kg high-tensile steel, as well as carbon steel for low-temperature pressure vessels and offshore structures, and more particularly, high temperature crack resistance of weld metal. The present invention relates to a metal flux filling wire having excellent impact toughness at low temperatures (-40 to -50 ° C).

Metal-based flux filling wire has a wide range of application in all industries due to its excellent welding efficiency and workability. However, the welding efficiency is high, but the low-temperature impact toughness of the weld metal is not sufficiently secured, or hot cracking of the weld metal is likely to occur in welding of a narrow gap. In addition, the sludge generated during one-pass welding is not easy to obtain a beautiful bead appearance, and the labor time for removing the slag formed in the bead appearance is increased, and the multi-pass is increased. In welding, there is a problem that a welding defect may occur due to mixing of slag that is not removed.

Conventional techniques for solving this problem include Japanese Laid-Open Patent Publication No. 2003-094196 and Korean Laid-open Patent Publication 2003-0050710.

Japanese Laid-Open Patent Publication No. 2003-094196 is related to the wire weight, C: 0.02 to 0.15%, Si: 0.3 to 1.5%, Mn: 0.8 to 3.0%, Ti: 0.1 to 0.35%, and B: 0.002 to 0.02%, Al: 0.05 to 0.3%, Mg: 0.05 to 0.5%, Mn + Si + 3Al + 4Mg: 2.5 to 5, Flux filling rate: 3 to 10% It is about. However, the prior art is effective in improving the fault resistance or reducing the amount of spatter generated, but it is not easy to remove the slag generated after welding due to the sporadically occurring oxide on the bead surface, and at -40 ° C. In order to secure low temperature impact toughness, it is essential to add special elements such as Ni and Mo.

In addition, Korean Patent Laid-Open Publication No. 2003-0050710 of the prior art, in the flux filling wire configured by filling the flux in the steel shell, in the weight percent of the wire, C: 0.01 ~ 0.045%, Si: 0.5 ~ 1.5 %, Mn: 1.0 to 3.0%, S: 0.001 to 0.025%, Iron: 9.0 to 22.5%, sum of two or more components selected from the group consisting of Na, K, Li, Rb and Cs: 0.01 to 0.25%, remaining It is composed of iron and unavoidable impurities, the oxygen content in the iron powder is 1.5% or less, Mn / (100 × S) is a metal-based flux filling wire, characterized in that controlled to 1 to 4, arc stabilizer It is an object of the present invention to provide a metal-based filling wire that stabilizes arc transition and controls surface slag generation to obtain a healthy welded part by appropriately controlling the content of S as well as adding a deoxidizer. However, the above-mentioned prior art is not good at low temperature shocks at -40 ° C and -50 ° C, and no special technology has been proposed that can prevent segregation of "S" which is a cause of high temperature cracking.

The present invention is to solve the problems of the prior art, by using the iron controlled "S" in the production of flux-filled wire to prevent local segregation of "S" in the flux to ensure high temperature crack resistance, carbonic acid It is an object of the present invention to provide a metal-based flux filling wire which can secure impact toughness at low temperature by appropriately controlling the use of the group.

The present invention for achieving the above object is selected from the group consisting of C: 0.01% to 0.05%, Si: 0.6% to 1.2%, Mn: 1.6% to 3.2%, Al, Ti, Mg and Zr in weight% of the wire. At least one species: 0.1 to 0.5%, S content of 0.08 to 0.12% Iron: 10 to 20%, and F2 amount of 0.02 to 0.2% fluoride, CO ₂ + CO ₃ equivalent 0.01 It relates to a metal-based flux-filled wire having a low-temperature toughness comprising a carbonic acid group-containing compound of ~ 0.1%, consisting of the remaining Fe and unavoidable impurities.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention prevents segregation of "S" in the flux by applying S-controlled iron to the manufacture of the flux-filled wire, and as a result, prevents segregation of "S" in the weld metal, thereby securing a weld metal excellent in high temperature cracking. It is characterized by. In addition, by using S-controlled iron, it is easy to remove the glass oxide slag generated during welding, and not only to obtain beautiful beads, but also to prevent the incorporation of slag that may occur during multilayer welding, thereby obtaining a healthy weld metal. have.

In addition, the present invention is characterized by obtaining a deposited metal having good low temperature impact toughness at -40 to -50 ° C by appropriately controlling the use of carbonic acid groups (CO ₂ , CO ₃ ).

% By weight of wire, C: 0.01-0.05% (hereinafter, only referred to as '%')

The C is added to the steel jacket, flux as a component affecting the mechanical performance and workability of the weld metal, it is preferable to control the content in a certain range. If the content of C is less than 0.01%, the structure of the weld metal is softened and the impact toughness is not only worsened, but the tensile strength is significantly lowered. If the content of C is more than 0.05%, brittle phenomena appear in the structure of the weld metal and the tensile strength is increased. Not only the impact toughness is sharply lowered but also the spatter is increased and the welding fume is excessively increased. Therefore, the content of C is preferably limited to 0.01 to 0.05%.

Si: 0.6 ~ 1.2%

The Si not only acts as a strong deoxidizer, but also affects the mechanical properties of the deposited metal and the behavior of the molten metal. If the content is less than 0.6%, pores are generated in the deposited metal due to the deoxidizer shortage and the behavior of the molten metal is deteriorated. The bead appearance worsens, and if it exceeds 1.2%, the excess Si is not completely dissolved in the tissue, causing embrittlement, and increasing the fluidity of the deposited metal, causing bead sag during the horizontal fillet welding, and the glass slag on the bead surface. Since there is a problem that the appearance of the beads worsens as the formation is excessive, the content of Si is preferably limited to 0.6 ~ 1.2%.

Mn: 1.6-3.2%

The Mn not only has a great influence on the tensile strength of the deoxidizer and the deposited metal, but is also an effective component for suppressing the formation of the FeS compound causing the high temperature crack while stably forming the MnS compound. If the content of Mn is less than 1.6%, excess "S" which is not stabilized with Mn forms FeS, which increases the sensitivity of hot cracking and significantly reduces the tensile strength of the deposited metal. The increase results in a drop in toughness. Therefore, the content of Mn is preferably limited to 1.6 to 3.2%.

At least one selected from the group consisting of Al, Ti, Mg and Zr: 0.1-0.5%

The components are effective in reducing the amount of oxygen and nitrogen in the deposited metal and stabilizing the arc, and have a great influence on the microstructure formation and impact toughness of the deposited metal by stabilizing the oxygen and nitrogen of the deposited metal. If the content of the components is less than 0.1% causes the deterioration of low-temperature impact toughness due to coarsening of the welded metal structure, if exceeding 0.5% there is a problem that excessively microstructure is formed on the welded metal causing high temperature cracking. Therefore, the content of the components is preferably limited to 0.1 ~ 0.5%.

Iron: 10-20%

The iron is an effective component to exhibit the effects of high performance and solid solution amount, which is a characteristic of the metal-based flux filling wire. If the content is less than 10%, the above-described effect is not obtained. Due to excessive increase in workability and poor appearance of the beads, there is a problem, the iron content is limited to 10 to 20% It is preferable.

In addition, "S" in the iron powder has a great influence on the workability and physical properties of the metal-based flux filling wire. In terms of workability, a small amount of oxide that is essentially produced during welding by containing a certain amount of S (here, oxide is not an oxide obtained by adding an oxide raw material, but oxygen present in molten metal in molten metal [remaining in the metal) Oxygen flowing from outside of oxygen + molten metal] and oxides formed by combining with elements such as Si, Mn, Al, Mg, Ti, Na, Mg, Ca, Zr, etc. By controlling the behavior of), beautiful beads can be obtained. That is, an appropriate amount of "S" increases the viscosity of the oxides produced during welding, resulting in agglomeration with each other. The slag formed in this way is easy to remove after welding, and the bead appearance is good. However, even if the content of S is excessive or the content is appropriate (side segregation) in a portion of the wire, there is a possibility that problems such as high temperature crack generation of the weld metal, lowering the tensile strength, lowering the elongation.

In order to take advantage of the S and suppress the disadvantages, the present invention is to control the iron in the metal-based flux filling wire to contain a certain amount of iron, thereby preventing segregation of the S to obtain the desired workability and physical properties will be.

If the content of S in the iron powder is less than 0.08%, the workability improvement effect according to the S content cannot be expected. If the content of S in the iron content exceeds 0.12%, S in the iron powder is excessively high, cracking of the weld metal occurs, tensile strength decreases, and elongation decreases. Can be. Therefore, the content of S in the iron powder is preferably limited to 0.08 ~ 0.12%.

Fluoride: 0.02 ~ 0.2% in F equivalent

The fluoride is an effective component for stabilizing the arc and suppressing the spatter generation. If the content is less than 0.02% in terms of F, the arc becomes unstable, the generation of thick spatter increases, and if the concentration exceeds 0.2%, the concentration of the arc is increased. In addition to weakening, the formation of oxides increases, forming unbelievable weld beads. Therefore, the fluoride is preferably limited to 0.02 to 0.2% in terms of F.

The fluoride is not particularly limited and may be added in the form of NaF, K ₂ SiF ₆ , LiF, BaF ₂ , CaF ₂ , MgF ₂ , Na ₃ AlF ₆ , SrF ₂ , KAlF _4, and the like.

Carbonate-containing compound: 0.01 to 0.1% in terms of CO ₂ + CO ₃

Compounds containing carbonic acid groups readily emit carbonic acid at low temperatures below the melting point of the metal when arcing occurs, and the released carbonic acid converts the arc atmosphere into an oxidizing atmosphere, and also increases the arc partial pressure due to the carbonic acid group, and together with the shielding gas. Maximize the blocking effect from outside air.

That is, by effectively blocking the oxygen and nitrogen that can be introduced from the outside atmosphere, not only restricts the amount of nitrogen and oxygen that can be introduced into the molten pool, but also, as mentioned above, the oxidative atmosphere forms the deoxidation and denitrification atmosphere of the molten metal. This results in a very healthy deposited metal with low nitrogen and oxygen control in the deposited metal. Conventional techniques for controlling nitrogen and oxygen in the deposited metal have been to use strong deoxidizer and denitrifier raw materials. The use of such deoxidizer and denitrifier has caused problems of excessively increasing arc power or deteriorating bead appearance. . Therefore, in the present invention, by using an appropriate amount of raw materials including carbonic acid groups, the same effect as using the deoxidizer and the denitrifier can be obtained while minimizing the use of the deoxidizer and the denitrifier, and a healthy weld metal exhibiting excellent impact toughness at -40 to -50 ° C. It is possible to obtain a beautiful bead appearance.

When the carbonic acid group-containing compound is less than 0.01% in terms of CO ₂ + CO _3, not only the above-described effect can be obtained, but also the impact toughness is deteriorated at low temperatures (-40 to -50 ° C.), and a beautiful bead appearance can be obtained. If it exceeds 0.1%, the partial pressure of CO and CO _{2 in} the arc pillar is increased, coarse spatter is generated, such as arc anxiety, and there is a problem of rapidly deteriorating workability. Therefore, the carbonic acid group-containing compound is preferably limited to 0.01 to 0.1% in terms of CO ₂ + CO ₃ .

In addition, the carbonate group-containing compound is not particularly limited and may be added in the form of CaCO ₃ , Na ₂ CO ₃ , BaCO _3, or the like.

Hereinafter, the present invention will be described in detail by way of examples, which are only preferred embodiments of the present invention, but the scope of the present invention is not limited by the description of these embodiments.

EXAMPLE

A flux filling wire having a diameter of 1.2 mm having a composition as shown in Tables 1 to 4 was prepared. Using the flux-filled wires prepared as described above, the SM490A welding base material having a thickness of 12 mm was welded under the welding conditions as shown in Table 5 below. Bead appearance, spatter generation, high temperature crack resistance, tensile strength and impact toughness of the welded sites were evaluated, and the results are shown in Table 6 below.

The high temperature crack resistance was evaluated as good or bad according to the first layer welding to the specimen, depending on the presence of cracks on the surface of the weld bead.

  division Flux Filled Wire Composition (wt% of wire)  C  Si  Mn  1 or more of Al, Ti, Mg and Zr iron content  Fluoride F conversion amount Carbonate-containing compound CO ₂ + CO ₃ equivalent  content  S content in iron Inventive Example 1 0.022 0.8 3.0 0.30 12 0.08 0.021 0.07 Inventive Example 2 0.022 0.9 2.9 0.23 18 0.08 0.151 0.05 Inventive Example 3 0.043 1.1 2.4 0.28 17 0.09 0.175 0.07 Inventive Example 4 0.037 1.2 2.5 0.19 11 0.09 0.192 0.08 Inventive Example 5 0.031 1.0 1.9 0.29 20 0.10 0.148 0.05 Inventive Example 6 0.041 1.2 1.7 0.15 19 0.10 0.200 0.01 Inventive Example 7 0.035 0.6 2.9 0.34 19 0.11 0.117 0.03 Inventive Example 8 0.043 0.6 2.5 0.50 14 0.12 0.185 0.04 Inventive Example 9 0.011 0.7 1.9 0.42 13 0.12 0.034 0.06 Comparative Example 1 0.052 1.4 1.5 0.18 14 0.07 0.035 0.01 Comparative Example 2 0.008 0.5 3.3 0.20 13 0.13 0.020 0.09 Comparative Example 3 0.035 1.2 1.8 0.09 9 0.08 0.300 0.10 Comparative Example 4 0.041 1.1 1.1 0.52 8 0.10 0.019 0.01 Comparative Example 5 0.042 0.6 2.8 0.31 9 0.12 0.175 0.12 Comparative Example 6 0.038 0.6 2.0 0.50 24 0.08 0.182 0.01 Comparative Example 7 0.024 1.0 1.6 0.51 22 0.07 0.158 0.07 Comparative Example 8 0.045 1.0 1.9 0.35 23 0.13 0.212 0.08 Comparative Example 9 0.011 0.55 1.1 0.27 23 0.07 0.022 0.06

At least one component selected from Al, Ti, Mg, and Zr in Table 1 was prepared as shown in Table 2 below.

division Al Ti Mg Zr Sum Inventive Example 1 0.2 0.1 - - 0.30 Inventive Example 2 0.15 - 0.08 - 0.23 Inventive Example 3 0.15 - - 0.13 0.28 Inventive Example 4 - 0.1 0.09 - 0.19 Inventive Example 5 - - 0.14 0.15 0.29 Inventive Example 6 0.15 - - - 0.15 Inventive Example 7 - 0.1 - 0.24 0.34 Inventive Example 8 0.25 - 0.25 - 0.50 Inventive Example 9 0.1 0.22 0.1 - 0.42 Comparative Example 1 0.09 - 0.09 - 0.18 Comparative Example 2 - 0.1 - 0.1 0.20 Comparative Example 3 - - - 0.09 0.09 Comparative Example 4 0.1 0.2 0.1 0.12 0.52 Comparative Example 5 0.1 - 0.1 0.11 0.31 Comparative Example 6 0.2 0.2 - 0.1 0.50 Comparative Example 7 0.3 0.01 0.2 - 0.51 Comparative Example 8 - 0.15 0.2 - 0.35 Comparative Example 9 0.2 - - 0.07 0.27

The fluoride of Table 1 was prepared as shown in Table 3 below.

division NaF K ₂ SiF ₆ LiF BaF ₂ CaF ₂ MgF ₂ Na ₃ AlF ₆ SrF ₂ KAlF ₄ Fluoride F conversion amount Inventive Example 1 0.022 0.021 - - - - - - - 0.021 Inventive Example 2 - 0.193 0.070 - - - - - - 0.151 Inventive Example 3 0.066 - 0.061 - - 0.164 - - - 0.175 Inventive Example 4 0.199 0.174 0.016 - - - - - - 0.192 Inventive Example 5 - - - 0.461 - - - - 0.090 0.148 Inventive Example 6 - - - - - - - 0.354 - 0.200 Inventive Example 7 - - 0.068 - - 0.110 - - - 0.117 Inventive Example 8 - - - - - - 0.341 - - 0.185 Inventive Example 9 - - - - 0.070 - - - - 0.034 Comparative Example 1 0.044 0.029 - - - - - - - 0.035 Comparative Example 2 - - 0.027 - - - - - - 0.020 Comparative Example 3 0.044 - - - - - - - 0.523 0.300 Comparative Example 4 - - - - - - 0.035 - - 0.019 Comparative Example 5 - - - 0.807 - - - - - 0.175 Comparative Example 6 - - - - 0.185 0.151 - - - 0.182 Comparative Example 7 - - - - - - - 0.177 0.108 0.158 Comparative Example 8 - 0.120 0.205 - - - - - - 0.212 Comparative Example 9 0.049 - - - - - - - - 0.022

The carbonic acid group-containing compound of Table 1 was prepared as shown in Table 4 below.

division CaCO ₃ Na ₂ CO ₃ BaCO ₃ Carbonate-containing compound CO ₂ + CO ₃ equivalent Inventive Example 1 0.050 0.071 - 0.07 Inventive Example 2 0.083 - - 0.05 Inventive Example 3 - 0.053 0.165 0.07 Inventive Example 4 0.033 0.035 0.165 0.08 Inventive Example 5 - 0.088 - 0.05 Inventive Example 6 - - 0.041 0.01 Inventive Example 7 - - 0.124 0.03 Inventive Example 8 0.033 0.035 - 0.04 Inventive Example 9 0.033 - 0.165 0.06 Comparative Example 1 0.017 - - 0.01 Comparative Example 2 - 0.071 0.206 0.09 Comparative Example 3 0.083 0.088 - 0.10 Comparative Example 4 - 0.016 - 0.01 Comparative Example 5 0.100 - 0.247 0.12 Comparative Example 6 - 0.016 - 0.01 Comparative Example 7 0.050 0.071 - 0.07 Comparative Example 8 0.033 0.035 0.165 0.08 Comparative Example 9 0.100 - - 0.06

Welding technique Protective gas Gas flow rate Welding current Welding voltage Welding speed Welding station Auto Carriage Forward Ar + 20% CO ₂ 20ℓ / min 280 ~ 290A 29 ~ 30V 30 ~ 32CPM 50 cm

division Bead Appearance Spatter occurrence High temperature crack resistance Tensile Strength (MPa) -40 ℃ impact toughness (J) -50 ° C Impact Toughness (J) Comprehensive Evaluation Inventive Example 1 Good Good Good 601 145 109 Good Inventive Example 2 Good Good Good 611 141 101 Good Inventive Example 3 Good Good Good 592 157 111 Good Inventive Example 4 Good Good Good 600 156 105 Good Inventive Example 5 Good Good Good 575 164 124 Good Inventive Example 6 Good Good Good 584 139 99 Good Inventive Example 7 Good Good Good 622 127 98 Good Inventive Example 8 Good Good Good 601 132 91 Good Inventive Example 9 Good Good Good 588 156 115 Good Comparative Example 1 Bad Bad Bad 459 49 32 Bad Comparative Example 2 Bad Good Bad 713 81 61 Bad Comparative Example 3 Bad Bad Good 550 70 29 Bad Comparative Example 4 Bad Good Bad 649 72 42 Bad Comparative Example 5 Bad Bad Good 572 68 28 Bad Comparative Example 6 Bad Good Good 533 44 19 Bad Comparative Example 7 Bad Good Bad 711 62 22 Bad Comparative Example 8 Bad Good Bad 578 78 43 Bad Comparative Example 9 Bad Good Bad 448 81 40 Bad

As can be seen from Table 6, the invention examples (1-9) satisfying the scope of the present invention has not only excellent impact toughness at low temperatures of -40 ~ -50 ℃ but also bead appearance, spatter generation, high temperature resistant Cracking properties were also good.

However, Comparative Examples (1 to 9), which did not satisfy the scope of the present invention, had low impact toughness at low temperatures, and were not good in workability and high temperature crack resistance.

As described above, according to the present invention, the metal which can secure the high temperature cracking property by preventing the segregation of S using the iron whose S is controlled, and the impact toughness at low temperature can be secured by appropriately controlling the use of carbonic acid groups. System flux filling wire can be provided.

Claims (1)

By weight relative to the wire, C: 0.01 to 0.05%, Si: 0.6 to 1.2%, Mn: 1.6 to 3.2%, at least one selected from the group consisting of Al, Ti, Mg and Zr: 0.1 to 0.5%, S Iron content controlled at 0.08 to 0.12%: 10 to 20%, including fluorides with 0.02 to 0.2% in terms of F, and carbonic acid-containing compounds with 0.01 to 0.1% in terms of CO ₂ + CO ₃ And a metal-based flux-filled wire having excellent low temperature toughness made of remaining Fe and unavoidable impurities.