Stainless steel welding wire used in LNG tank manufacturing

Abstract

The present invention relates to a stainless steel welding wire for manufacturing LNG tanks, and more particularly to a stainless steel welding wire for manufacturing LNG tanks that can obtain a weld metal with excellent tensile strength and impact value by adjusting the contents of Ni, Mn, Mo, and Cr. The stainless steel welding wire for manufacturing LNG tanks of the present invention can be applied to welding all of 9% nickel steel, high manganese steel, and stainless steel by adjusting the contents of Ni, Mn, Mo, and Cr, and has the effect of obtaining a weld metal with excellent cryogenic toughness in the weld region.

Description

[Technical field]

[0001] The present invention relates to a stainless steel welding wire used in the manufacture of LNG tanks, and more particularly to a stainless steel welding wire used in the manufacture of LNG tanks, in which the contents of Ni, Mn, Cr and Mo can be adjusted so that a weld metal having excellent strength and cryogenic impact toughness can be obtained from the wire. [Background technology]

[0002] Liquefied gases such as liquefied natural gas (LNG) with a boiling point of -164°C, liquid oxygen with a boiling point of -183°C, and liquid nitrogen with a boiling point of -196°C require cryogenic storage. Therefore, in order to store these gases, structures such as pressure vessels made of materials that have sufficient toughness and strength at cryogenic temperatures are required.

[0003] Cr-Ni-based stainless steel, 9% Ni steel, and 5000 series aluminum alloys have been commonly used as materials that can be used at low temperatures in liquefied gas environments. However, when using aluminum alloys, there are problems such as high alloy costs, large design thickness due to low strength, and limited specifications due to poor weldability. Cr-Ni-based stainless steel and 9% Ni steel overcome the low strength problem of aluminum, but they must contain excessive nickel, which increases manufacturing costs, making their application problematic.

[0004] Furthermore, as another technology for stainless steels used for liquefied gas, so-called nickel-free (Ni-free) high magnesium steels that do not use nickel at all have been used. However, such technology has problems such as increased costs and increased load on heat treatment equipment due to an increase in the number of heat treatment cycles. Therefore, as disclosed in Korean Patent No. 10-135843, a technology was developed to ensure cryogenic toughness by using austenite as the main structure instead of ferrite.

[0005] Conventional wires used for welding such structural steels have been developed to be selectively applied to 9% Ni steel, stainless alloy, or high magnesium steel according to the physical properties of the structural steels in order to satisfy the strength and impact resistance of the structure after welding. However, if the application is limited by the material of the structural steel, it causes confusion in the work process and is disadvantageous from an economic point of view. Therefore, there is a need to develop a welding material that can be welded without restrictions due to the material of the structural steel members and also provides excellent cryogenic toughness to the welded part. Summary of the Invention [Problem to be solved by the invention]

[0006] In order to solve the above problems, the present invention aims to provide a stainless steel welding wire for use in LNG tank manufacturing, which has suitable physical properties required for LNG tanks. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a stainless steel welding wire containing 6.0-15.0 wt% Ni, 13.0-25.0 wt% Cr, 1.0-10.0 wt% Mn, 5.0 wt% or less (excluding 0 wt%) Mo, 0.05-1.0 wt% Si, a C content of 0.5 wt% or less (excluding 0 wt%), a total content of P and S of 0.1 wt% or less (excluding 0 wt%), and the balance containing Fe and unavoidable impurities, and the stainless steel welding wire used in the manufacture of LNG tanks satisfies the following relational expression 1: to provide. [Equation 1] {Cr+Mo} / {Ni+Mn+30(C+N)}>1

[0008] Further provided is a stainless steel welding wire having a composition including 6.0-15.0 wt% Ni, 13.0-25.0 wt% Cr, 1.0-10.0 wt% Mn, and 0.05-1.0 wt% Si, with a C content of 0.5 wt% or less (excluding 0 wt%), a total content of P and S limited to 0.1 wt% or less (excluding 0 wt%), at least one element (Q) selected from the group consisting of Mo, W, and Nb in an amount of 0.1-5.0 wt%, and the balance including Fe and unavoidable impurities, wherein the stainless steel welding wire used in the manufacture of LNG tanks satisfies the following Relation 2. [Equation 2] {Cr+Q} / {Ni+Mn+30(C+N)}>1

[0009] Further, there is provided a stainless steel welding wire for producing a weld metal containing 8.0-14.0 wt% Ni, 15.0-23.0 wt% Cr, 1.0-8.0 wt% Mn, 4.0 wt% or less (excluding 0 wt%) Mo, 0.05-1.0 wt% Si, with the total content of C and N limited to 0.01-0.2 wt%, the total content of P and S limited to 0.1 wt% or less (excluding 0 wt%), and the balance containing Fe and unavoidable impurities, wherein the stainless steel welding wire used in the manufacture of LNG tanks satisfies the following Relational Formula 1. [Equation 1] {Cr+Mo} / {Ni+Mn+30(C+N)}>1

[0010] Further provided is a stainless steel welding wire for producing a weld metal comprising 8.0-14.0 wt% Ni, 15.0-23.0 wt% Cr, 1.0-8.0 wt% Mn, 0.05-1.0 wt% Si, the total content of C and N being limited to 0.01-0.2 wt%, the total content of P and S being limited to 0.1 wt% or less (excluding 0 wt%), at least one element (Q) selected from the group consisting of Mo, W and Nb in an amount of 0.1-4.0 wt%, and the balance comprising Fe and unavoidable impurities, wherein the stainless steel welding wire used in the manufacture of LNG tanks satisfies the following Relation 2: [Equation 2] {Cr+Q} / {Ni+Mn+30(C+N)}>1 Effect of the Invention

[0011] The stainless steel welding wire used in the LNG tank manufacturing according to the present disclosure can be used to weld 9% nickel steel members, high manganese steel members, and stainless steel members by controlling the content of Mo and Cr. The stainless steel welding wire has the effect of obtaining a weld metal having excellent cryogenic toughness in the welded portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described in detail below.

[0013] As used herein, the term "weld metal" refers to the metal resulting from solidification of a molten mixture of the weld metal and base metal during welding.

[0014] As used herein, the term "deposited metal" refers to metal transferred from the filler metal (i.e., wire), which is the metallic material added to the weld metal area during welding.

[0015] According to one aspect of the present invention, there is provided a stainless steel welding wire for use in LNG tank manufacturing, the flux cored wire having a sheath with embedded flux, the welding wire having a composition including Mn, Mo, Cr and Ni in predetermined weight percent relative to the total weight of the welding wire.

[0016] More specifically, there is provided a stainless steel welding wire used in the manufacture of LNG tanks, the welding wire components including 6.0-15.0 wt% Ni, 13.0-25.0 wt% Cr, 1.0-10.0 wt% Mn, 5.0 wt% or less (excluding 0 wt%) Mo, 0.05-1.0 wt% Si, the C content being limited to 0.5 wt% or less (excluding 0 wt%), the total content of P and S being limited to 0.1 wt% or less (excluding 0 wt%), the balance being Fe and unavoidable impurities, and the stainless steel welding wire satisfies the following relational expression 1. [Equation 1] {Cr+Mo} / {Ni+Mn+30(C+N)}>1

[0017] Ni: 6.0-15.0wt% Nickel (Ni) is a chemical component that stabilizes the austenite structure. If the nickel content is less than 6.0wt%, the austenite structure becomes unstable, which is not preferable. If the nickel content is more than 15.0wt%, the hot cracking resistance decreases, which is not preferable. Therefore, the nickel content is preferably limited to the range of 6.0-15.0wt%.

[0018] Cr: 13.0-25.0wt% Chromium (Cr) is a chemical component that improves the strength of the weld metal and stabilizes the austenitic structure. If the chromium content is less than 13.0 wt%, sufficient strength cannot be obtained, which is undesirable. If the chromium content is more than 25.0 wt%, the low-temperature impact toughness of the weld metal decreases, which is undesirable. Therefore, it is preferable that the chromium content is limited to the range of 13.0-25.0 wt%.

[0019] Mn: 1.0-10.0wt% Manganese (Mn) is a chemical component that stabilizes the austenite structure and improves deoxidation and weldability. If the manganese content is less than 1.0 wt%, it is not preferable because it does not provide sufficient deoxidation. If the manganese content is more than 10.0 wt%, the segregation of the weld metal in the final solidification region is accelerated, thereby lowering the melting point of the molten metal and reducing hot cracking resistance. Therefore, it is preferable that the manganese content is limited to the range of 1.0-10.0 wt%.

[0020] Mo: 5.0wt% or less (excluding 0wt%) Molybdenum (Mo) has the effect of improving the strength of the weld metal. If the Mo content is low, sufficient strength cannot be obtained, which is undesirable. If the Mo content is more than 5.0 wt%, the toughness of the weld metal decreases, and the segregation of Mo accelerates, which results in a decrease in hot cracking resistance, which is undesirable. Therefore, it is preferable that the Mo content is limited to a range of 5.0 wt% or less.

[0021] Si: 0.05-1.0wt% Silicon (Si) is a chemical component that improves deoxidation and weldability. If the Si content is less than 0.05wt%, the deoxidation effect is insufficient. If the Si content is more than 1.0wt%, it is not preferable because it increases the cracking sensitivity due to the formation of Laves phase. Therefore, it is preferable to limit the Si content to 0.05-1.0wt%.

[0022] C: 0.5wt% or less (excluding 0wt%) Carbon (C) has the effect of improving the strength of the weld metal, but if it is added in excess, there is a problem that carbides are formed and the toughness is reduced. Therefore, the C content is set to 0.5 wt% or less based on the total weight of the wire. More specifically, the C content may be set to 0.1 wt% or less to prevent the toughness of the weld metal from being reduced.

[0023] P+S: 0.1wt% or less (excluding 0wt%) Phosphorus (P) and sulfur (S) are the elements that mainly affect hot cracking. P and S form compounds with low melting points, which may cause hot cracking. In the present invention, the total content of P and S is preferably less than 0.1 wt%.

[0024] The balance may be Fe and unavoidable impurities. Furthermore, copper (Cu) may be contained in an amount of 0.5wt% or less (excluding 0wt%). Copper (Cu) is a precipitation hardening element, and the Cu content is preferably limited to 0.5wt% or less. It is not preferable for the Cu content to be greater than 0.5wt%, since hardenability increases and thus low-temperature impact toughness decreases. Nitrogen (N) may be further contained in an amount of 0.2wt% or less. N is a solid solution hardening element, and the N content is preferably limited to 0.2wt% or less. If the N content is greater than 0.2wt%, low-temperature impact toughness decreases and a fully austenitic structure occurs, which is not preferable, since hot cracking resistance and porosity resistance decrease.

[0025] In the welding wire of the present invention, the relationship between the contents of Mn, Cr and Mo is adjusted to obtain the physical properties required for the welded region. The adjustment is preferably made so that the value defined by the relational expression 1 exceeds 1. If the value is less than 1, it is difficult to ensure the strength and cryogenic toughness (i.e., values ​​related to impact), resulting in a deterioration in the quality of the welded metal region.

[0026] Furthermore, the present invention provides a stainless steel welding wire for manufacturing LNG tanks, comprising 8.0-15.0 wt% Ni, 13.0-25.0 wt% Cr, 1.0-10.0 wt% Mn, 0.05-1.0 wt% Si, a C content of 0.5 wt% or less (excluding 0 wt%), a total content of P and S limited to the range of 0.1 wt% or less (excluding 0 wt%), at least one element (Q) selected from the group consisting of Mo, W and Nb is contained in an amount of 0.1-5.0 wt%, and the balance is Fe and unavoidable impurities, and the welding wire satisfies Relation 2. [Equation 2] {Cr+Q} / {Ni+Mn+30(C+N)}>1

[0027] Specifically, the content range of each component in the composition is as explained above.

[0028] Mo, W, and Nb have the effect of improving the strength of the weld metal, and at least one of them may be selectively included. If the content of at least one element selected from the group consisting of Mo, W, and Nb is less than 0.1 wt%, sufficient strength cannot be obtained, which is not preferable. If the content of at least one element selected from the group consisting of Mo, W, and Nb is more than 5.0 wt%, the toughness of the weld metal decreases, and the hot crack resistance decreases, which is not preferable. Therefore, it is preferable that the content of each element is limited to 0.1-5.0 wt%. In the relational formula 2, Q may be any one of Mo, [Mo+W], [Mo+Nb], [Mo+W+Nb], W, Nb, and [W+Nb]. More specifically, the relational formula 2 may be 1.5>{Cr+Q} / {Ni+Mn+30(C+N)}>1. If the value of Relation 2 is greater than 1.5 or less than 1, it is difficult to ensure strength and cryogenic toughness (i.e., values ​​related to impact), and the quality of the weld metal area decreases.

[0029] Specifically, the stainless steel welding wire of the present invention may additionally contain W in an amount of 2.0 wt% or less, or may contain W instead of Mo. Tungsten (W) has the same effect as Mo. That is, W and Mo improve the strength of the weld metal. If the W content is more than 2.0 wt%, the toughness of the weld metal may decrease. Therefore, it is preferable that the W content is limited to a range of 2.0 wt% or less.

[0030] Furthermore, the stainless steel welding wire of the present invention may additionally contain Nb in an amount of 1.5wt% or less instead of Mo, or Nb instead of Mo. Niobium (Nb) has the same effect as Mo. That is, Ni and Mo improve the strength of the weld metal. If the Nb content is more than 1.5wt%, the toughness of the weld metal may decrease. Therefore, it is preferable that the Nb content is limited to a range of 1.5wt% or less.

[0031] According to another aspect of the present invention, there is provided a stainless steel welding wire for use in manufacturing an LNG tank, wherein a deposited metal obtained from the welding wire contains 8.0-14.0 wt% Ni, 15.0-23.0 wt% Cr, 1.0-8.0 wt% Mn, 4.0 wt% or less (excluding 0 wt%) Mo, 0.05-1.0 wt% Si, the total content of C and N is limited to a range of 0.01-0.2 wt%, the total content of P and S is limited to a range of 0.1 wt% or less (excluding 0 wt%), the balance being Fe and unavoidable impurities, and the welding wire satisfies [Relationship 1]. [Equation 1] {Cr+Mo} / {Ni+Mn+30(C+N)}>1

[0032] The properties of the deposited metal vary depending on the alloy composition of the welding wire. For example, the alloy composition determines whether the properties required for manufacturing LNG tanks can be obtained. By using the welding wire according to the present invention, it is possible to obtain a deposited metal having excellent strength, toughness, and impact value.

[0033] Nickel (Ni) is a chemical component that stabilizes the austenite structure. If the nickel content is less than 8.0wt%, the austenite structure becomes unstable, which is undesirable. If the nickel content is more than 14.0wt%, the hot cracking resistance decreases, which is undesirable. Therefore, the nickel content is preferably limited to the range of 8.0-15.0wt%.

[0034] Chromium (Cr) is a chemical component that improves the strength of the weld metal and stabilizes the austenite structure. If the chromium content is less than 15.0 wt%, sufficient strength cannot be obtained, which is undesirable. If the chromium content is more than 23.0 wt%, the low-temperature impact toughness of the weld metal decreases, which is undesirable. Therefore, it is preferable that the chromium content is limited to the range of 15.0-23.0 wt%.

[0035] Manganese (Mn) is a chemical component that stabilizes the austenite structure and improves deoxidation and weldability. If the manganese content is less than 1.0 wt%, it is not preferable because it does not provide sufficient deoxidation. If the manganese content is more than 8.0 wt%, the segregation of the weld metal in the final solidification region is accelerated, thus reducing the hot cracking resistance. Therefore, it is preferable that the manganese content is limited to the range of 1.0-8.0 wt%.

[0036] Molybdenum (Mo) has the effect of improving the strength of the weld metal. If the Mo content is low, sufficient strength cannot be obtained, which is undesirable. If the Mo content is more than 4.0 wt%, the toughness of the weld metal decreases, segregation accelerates, and therefore the hot cracking resistance decreases. Therefore, it is preferable that the Mo content is limited to a range of 4.0 wt% or less.

[0037] If the Si content is less than 0.05wt%, the deoxidizing effect is insufficient. If the Si content is more than 1.0wt%, the cracking sensitivity increases due to the formation of Laves phase, which is not preferable. Therefore, the Si content is preferably limited to the range of 0.05-1.0wt%.

[0038] Carbon (C) has the effect of improving the strength of the weld metal, but if it is added in excess, carbides are formed, which causes a problem of reduced toughness. N is a solid solution strengthening element, and if added in excess, it reduces low-temperature impact toughness and produces a fully austenitic structure, which is undesirable because it reduces hot cracking resistance and porosity resistance. Therefore, the total content of C and N is preferably limited to the range of 0.01-0.5wt%.

[0039] Phosphorus (P) and sulfur (S) are the elements that mainly affect hot cracking. P and S form compounds with low melting points, which may cause hot cracking. In the present invention, the total content of P and S is preferably less than 0.1 wt%.

[0040] The balance may be Fe and unavoidable impurities. Copper (Cu) may further be included in an amount of 0.5wt% or less (excluding 0wt%). Copper (Cu) is a precipitation hardening element, and the Cu content is preferably limited to 0.5wt% or less. A Cu content of more than 0.5wt% is not preferred because it increases hardenability and therefore reduces low-temperature impact toughness. Nitrogen (N) may further be included in an amount of 0.2wt% or less. N is a solid solution hardening element, and the N content is preferably limited to 0.2wt% or less. If the N content is more than 0.2wt%, the low-temperature impact toughness decreases and a fully austenitic structure occurs, which is not preferred because it reduces hot cracking resistance and porosity resistance.

[0041] On the other hand, with respect to the stainless steel welding wire of the present invention and the weld metal obtained from the wire, the content of each component is preferably controlled so as to satisfy [Relational formula 1].

[0042] [Relationship 1] is {Cr+Mo} / {Ni+Mn+30(C+N)}>1. It is preferable to control so that the value defined by the relationship 1 is greater than 1. If the value is less than 1, it is difficult to ensure the strength and cryogenic toughness (i.e., values ​​related to impact), resulting in a deterioration of the quality of the weld metal area. In particular, when {Cr+Mo} / {Ni+Mn+30(C+N)}>1 is satisfied, the deposited metal obtained from the welding wire has a yield point of 400 MPa or more, a tensile strength of 640 MPa or more, and an elongation of 30% or more. Furthermore, the Charpy impact test shows that the deposited metal exhibits an impact value of 27 J or more at -196°C.

[0043] The present invention further provides a stainless steel welding wire for use in the manufacture of LNG tanks, in which the deposited metal obtained from the welding wire has a chemical composition including 8.0-14.0 wt% Ni, 15.0-23.0 wt% Cr, 1.0-8.0 wt% Mn, and 0.05-1.0 wt% Si, the total content of C and N is limited to the range of 0.01-0.2 wt%, the total content of P and S is limited to the range of 0.1 wt% or less (excluding 0 wt%), at least one element (Q) selected from the group consisting of Mo, W, and Nb is contained in an amount of 0.1-4.0 wt%, and the balance is Fe and unavoidable impurities, and the composition of the deposited metal satisfies [Relationship 2], which is {Cr+Q} / {Ni+Mn+30(C+N)}>1.

[0044] Specifically, the content range of each component of the composition is as explained above.

[0045] When the composition further contains W or Nb, or when Mo is replaced with W or Nb, the stainless steel welding wire of the invention or the deposited metal obtained therefrom preferably satisfies the following Relation 2. In Relation 2, Q may be any one of Mo, [Mo+W], [Mo+Nb], [Mo+W+Nb], W, Nb, and [W+Nb]. More strictly, Relation 2 may be 1.5>{Cr+Q} / {Ni+Mn+30(C+N)}>1. When the value of Relation 2 is 1.5 or more or 1 or less, it is difficult to ensure strength and cryogenic toughness (i.e., values ​​related to impact), resulting in a deterioration of the quality of the weld metal area.

[0046] Specifically, the deposited metal obtained by welding from the stainless steel welding wire of the present invention may further contain W in an amount of 2.0 wt% or less instead of Mo. Tungsten (W) has the same effect as Mo. That is, W and Mo improve the strength of the weld metal. If the W content is more than 2.0 wt%, the toughness of the weld metal decreases. Therefore, it is preferable that the W content is limited to the range of 2.0 wt% or less.

[0047] Specifically, the deposited metal obtained by welding from the stainless steel welding wire of the present invention may further contain Nb in an amount of 1.5 wt%, or may contain Nb instead of Mo. Niobium (Nb) has the same effect as Mo. That is, Nb and Mo improve the strength of the weld metal. If the Nb content is more than 1.5 wt%, the toughness of the weld metal decreases. Therefore, it is preferable that the Nb content is limited to a range of 1.5 wt% or less.

[0048] In the stainless steel welding wire according to the present invention, the stainless steel welding wire can be applied to any one of flux cored arc welding (FCAW), submerged arc welding (SAW), gas metal arc welding (GMAW), gas tungsten arc welding (GTAW), inert gas metal arc welding (MIG) and inert gas tungsten arc welding (TIG). The application of the welding wire is not limited by the welding method. Preferably, the welding wire of the present invention is applied to submerged arc welding (SAW).

[0049] In connection with the stainless steel welding wire according to the present invention, the physical properties of the weld metal region according to the relationship between the contents of Cr, Mo and Mn will be described in detail with reference to the following examples and comparative examples, but the scope of the present invention is not limited by these examples.

[0050] A stainless steel welding wire for submerged arc welding (SAW) was prepared having the chemical composition shown in Table 1. [Table 1] TIFF0007607657000002.tif197159

[0051] Submerged arc welding (SAW) was performed with each welding material. In the case of SAW, welding was performed with a heat input of 10.0-18.0 kJ / cm. A wire with a diameter of 2.4 mm was used for SAW. A bevel was formed with a bevel angle of 30° on the bevel surface of a 9% Ni steel plate with a thickness of 20 mm, which is one of the base materials for manufacturing LNG tanks. The base materials were then aligned with a root spacing of 3 mm, and a weld joint was formed by one-pass welding using the same type of FCAW welding at the narrow part of the groove (root part) to form a weld joint. The weld joint was visually inspected for arc stability, slag detachability, crack resistance of the weld joint, and bead appearance (presence or absence of holes). The inspection results were classified into the following four grades: ◎: excellent, O: good, △: fair, X: unsatisfactory. The results are shown in Table 2 below. [Table 2]

[0052] Referring to Table 2, it was found that in the case of No. 11, which does not satisfy the relational expression 1, the arc stability and bead appearance were not satisfactory. Furthermore, it was found that in the cases of No. 12, 14 and 16, which do not satisfy the relational expression 2, the rate of cracks was high. It was found that in the cases of No. 20 and 27, cracks occurred according to the Mn content. Next, the yield strength (YS), tensile strength (TS), elongation (EL) and Charpy impact energy (at -196°C) of the welded joints were measured. The obtained results are shown in Table 3 below. [Table 3]

[0053] Referring to Table 3, it was found that the yield point, tensile strength and especially the impact value were low in the case of Nos. 12-20 which did not satisfy the relational formula 1. In contrast, in the case of Nos. 1-10 which were prepared so as to satisfy the composition range of the present invention, a yield point of 400 MPa or more, a tensile strength of 650 MPa or more, an elongation of 38% or more and an impact value of 35 J or more were ensured.

[0054] Furthermore, regarding the content of Mo, W or Nb, a stainless steel welding wire having the chemical composition shown in Table 4 was prepared according to Relation 2. The evaluation results of the properties of the welded joint after welding are shown in Table 5 below. [Table 4] [Table 5]

[0055] Referring to Tables 4 and 5, it was found that when W or Nb was added as an additional component or instead of Mo, and the value of the relationship between Mn and W or Nb was in the range of 25-28, which is outside the range of the composition of the present invention, the low temperature impact value was low. Furthermore, it was also confirmed that when the value was in the range of 29-35 and did not satisfy the relationship 2, the impact value was also low. Therefore, it can be seen that when W and Nb are added as additional components or instead of Mo, it is preferable that the content ratio of the chemical components is adjusted according to the relationship 2.

[0056] The stainless steel welding wire according to the present invention has a feature that a weld metal having excellent strength and cryogenic impact toughness can be obtained from the stainless steel welding wire because the manganese content is limited to a range of 10 wt% or less and the Mo and Cr contents are appropriately controlled. The stainless steel welding wire according to the present invention is applicable to welding of 9% nickel steel, high manganese steel and stainless steel, and has an advantageous effect of obtaining a weld metal having excellent cryogenic toughness in the welded region.

[0057] The features and technical advantages of the present invention have been described above in a broad manner so that the appended claims may be better understood. Those skilled in the art will appreciate that the present invention may be embodied in other different forms without departing from the technical spirit or basic characteristics of the illustrated embodiments. It will therefore be understood that the above-described examples are for illustrative purposes only and are not limiting in all respects. The scope of the present invention is defined by the following claims, not the above detailed description, and all changes or modifications that come within the meaning and scope of the claims, and their equivalents, should be construed as being within the scope of the present invention.

Claims

1. 1. A stainless steel welding wire for manufacturing an LNG tank, comprising: The welding wire has a composition including 6.0-15.0 wt% Ni, 13.0-25.0 wt% Cr, 1.0-10.0 wt% Mn, and 0.05-1.0 wt% Si; The C content is 0.5 wt% or less (excluding 0 wt%). The total content of P and S is limited to 0.1 wt% or less (excluding 0 wt%). The element (Q) consisting of Mo, W and Nb, or W and Nb, or Mo and Nb, is contained in an amount of 0.1-5.0 wt %; The welding wire is a stainless steel welding wire, which satisfies the following Relation 2: [Relationship 2] {Cr+Q} / {Ni+Mn+30(C+N)}>1

2. A deposited metal for manufacturing an LNG tank, comprising: The weld metal is formed from a welding wire having a composition including 8.0-14.0 wt.% Ni, 15.0-23.0 wt.% Cr, 1.0-8.0 wt.% Mn, and 0.05-1.0 wt.% Si; The total content of C and N is in the range of 0.01-0.2 wt%. The total content of P and S is limited to 0.1 wt% or less (excluding 0 wt%). An element (Q) consisting of Mo, W and Nb, or W and Nb, or Mo and Nb, in an amount of 0.1-4.0 wt. %; The welding wire satisfies the following Relational Expression 2: welding metal. [Relationship 2] {Cr+Q} / {Ni+Mn+30(C+N)}>1

3. The welding wire can be applied to any one of submerged arc welding (SAW), gas metal arc welding (GMAW), gas tungsten arc welding (GTAW), inert gas metal arc welding (MIG) and inert gas tungsten arc welding (TIG); 2. The stainless steel welding wire of claim 1.

4. The welding wire forming the deposited metal can be applied to any one of submerged arc welding (SAW), gas metal arc welding (GMAW), gas tungsten arc welding (GTAW), inert gas metal arc welding (MIG) and inert gas tungsten arc welding (TIG). The weld metal of claim 2.

5. The welding wire contains 4.0 wt % or less (excluding 0 wt %) Mo, and the welding wire satisfies the following Relational Expression 1:

2. The stainless steel welding wire of claim 1. [Relationship 1] {Cr+Mo} / {Ni+Mn+30(C+N)}>1

6. The welding wire forming the deposited metal contains 4.0 wt % or less (excluding 0 wt %) Mo, and the welding wire satisfies the following Relational Expression 1: The weld metal of claim 2. [Relationship 1] {Cr+Mo} / {Ni+Mn+30(C+N)}>1

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