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KR-20260064257-A - Flux cored wire and welded metal obtained using the same

KR20260064257AKR 20260064257 AKR20260064257 AKR 20260064257AKR-20260064257-A

Abstract

A flux-cored wire according to one embodiment of the present disclosure is a flux-cored wire in which flux is filled into a steel sheath, wherein, in weight percent relative to the total weight of the steel sheath, the steel sheath comprises TiO₂ : 4.5~8.0%, C: 0.04~0.08%, Si: 0.30~0.65%, Mn+Ni: 4.50~6.00%, Mg: 0.40~0.80%, B: 0.001~0.010%, Mo: 0.15~0.45%, Nb: 0.010% or less, V: 0.010% or less, P+S: 0.010% or less, Na+K: 0.1~0.5%, and the remainder being Fe and unavoidable impurities, wherein the F equivalent amount of the alkali and alkaline earth metal-based fluorine compound is 0.02~0.10%, and the following formula The value of A defined by 1 can be 10.0 to 12.5. [Equation 1]

Inventors

  • 신경수
  • 조영호
  • 김홍재
  • 유동현
  • 조진환
  • 최현석
  • 차인환
  • 김호준

Assignees

  • 에이치디한국조선해양 주식회사
  • 현대종합금속 주식회사
  • 에이치디현대미포 주식회사

Dates

Publication Date
20260507
Application Date
20241031

Claims (8)

  1. As a flux-cored wire with flux filled in a steel sheath, In weight percent relative to the total weight of the steel sheath, the steel sheath comprises TiO2 : 4.5~8.0%, C: 0.04~0.08%, Si: 0.30~0.65%, Mn+Ni: 4.50~6.00%, Mg: 0.40~0.80%, B: 0.001~0.010%, Mo: 0.15~0.45%, Nb: 0.010% or less, V: 0.010% or less, P+S: 0.010% or less, Na+K: 0.1~0.5%, and the remainder being Fe and unavoidable impurities. The F equivalent content of alkali and alkaline earth metal-based fluorine compounds is 0.02~0.10%, and Flux-cored wire having a value of A defined by the following Equation 1, ranging from 10.0 to 12.5. [Equation 1]
  2. In claim 1, Flux-cored wire containing the above Mn in the range of 2.5 to 3.5%.
  3. In claim 1, Flux-cored wire containing the above Ni in the range of 2.0 to 2.7%.
  4. In claim 1, The flux-cored wire, wherein the flux is included in a weight ratio of 13.0 to 18.0% with respect to the total weight of the flux-cored wire including the steel sheath and the flux.
  5. Welded metal obtained using a flux-cored wire according to any one of claims 1 to 4.
  6. In claim 5, A weld metal having a yield strength of 690 MPa or higher at 25°C.
  7. In claim 5, A weld metal having an elongation of 15% or more at 25°C.
  8. In claim 5, A weld metal having a Charpy impact toughness of 46 J or higher at -40℃.

Description

Flux-cored wire and welded metal obtained using the same The present disclosure relates to a flux-cored wire and a weld metal obtained using the same. Recently, the shipbuilding industry has seen a growing demand for Carbon Capture, Utilization & Storage (CCUS) technologies related to the capture, utilization, and storage of CO2 , driven by the need to reduce CO2 , which causes greenhouse effects. With this rising demand for CCUS technologies, there is an expected increase in demand for liquefied carbon dioxide ( LCO2 ) carriers , which are useful for efficiently storing CO2 while transporting it over long distances to processing sites. Meanwhile, considering the increase in the size of liquefied carbon dioxide ( LCO2 ) carriers and the issue of increased design pressure in LCO2 storage tanks installed on LCO2 carriers due to market demand, there is a need to develop welding materials capable of having high strength and high toughness properties. In particular, since liquefied carbon dioxide ( LCO2 ) storage tanks are used under low temperature and high pressure conditions, the welding materials used for them must also be capable of withstanding low temperature (approx. -40°C) and high pressure (approx. 18 bar) conditions; however, existing welding materials often lacked low-temperature impact toughness. Figure 1 shows an image of the crack shape of micro-segregation appearing in the weld of Comparative Example 10 of the present disclosure, taken using a scanning electron microscope. FIG. 2 schematically illustrates an example of a post-weld heat treatment (PWHT) profile applicable in the present disclosure. FIG. 3 schematically illustrates an example of a specimen for evaluating crack resistance according to the present disclosure, showing an assembled specimen of 200 x 150 (mm) in width and length with a Y-groove weld formed thereon. Figure 4 shows a part of the specimen of Figure 3, made using a 50mm thick steel material (S690QL) to have a bevel angle of 60° and a root gap of 2mm. The present invention is capable of various modifications and may have various embodiments, and specific embodiments are to be illustrated and described in detail. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as “comprising” or “having” are intended to specify the presence of the components, materials, features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other components, materials, features, numbers, steps, actions, components, parts, or combinations thereof. Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application. In this disclosure, % means weight % unless otherwise stated. Hereinafter, preferred embodiments of the present disclosure will be described in more detail. A flux-cored wire according to one embodiment of the present disclosure is a flux-cored wire in which flux is filled into a steel sheath, wherein, in weight percent relative to the total weight of the steel sheath, the steel sheath comprises TiO₂ : 4.5~8.0%, C: 0.04~0.08%, Si: 0.30~0.65%, Mn+Ni: 4.50~6.00%, Mg: 0.40~0.80%, B: 0.001~0.010%, Mo: 0.15~0.45%, Nb: 0.010% or less, V: 0.010% or less, P+S: 0.010% or less, Na+K: 0.1~0.5%, and the remainder being Fe and unavoidable impurities, wherein the F equivalent amount of the alkali and alkaline earth metal-based fluorine compound is 0.02~0.10%, and the following formula The value of A defined by 1 can be 10.0 to 12.5. [Equation 1] Titanium dioxide ( TiO2 ) serves as an arc stabilizer and is a major component of a slag-forming agent. In addition, in the present disclosure, the content of titanium dioxide ( TiO2 ) needs to be controlled to ensure weldability and appropriate impact toughness. A flux-cored wire according to one embodiment of the present disclosure may contain 4.5 to 8.0% titanium dioxide ( TiO2 ) as a weight percent relative to the total weight of the steel sheath. If the TiO2 content is less than 4.5%, slag solidification is reduced, making it difficult to perform horizontal fixed-position weldi