KR101449150B1 - Welded joints of cryogenic steel - Google Patents

Welded joints of cryogenic steel Download PDF

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Publication number
KR101449150B1
KR101449150B1 KR1020120135518A KR20120135518A KR101449150B1 KR 101449150 B1 KR101449150 B1 KR 101449150B1 KR 1020120135518 A KR1020120135518 A KR 1020120135518A KR 20120135518 A KR20120135518 A KR 20120135518A KR 101449150 B1 KR101449150 B1 KR 101449150B1
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South Korea
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cryogenic
present
strength
impact toughness
steel
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KR1020120135518A
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Korean (ko)
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KR20140067803A (en
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한일욱
김정길
이봉근
이홍길
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주식회사 포스코
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Priority to KR1020120135518A priority Critical patent/KR101449150B1/en
Application filed by 주식회사 포스코 filed Critical 주식회사 포스코
Priority to CA2947569A priority patent/CA2947569C/en
Priority to CN201380060601.5A priority patent/CN104797730B/en
Priority to PCT/KR2013/010696 priority patent/WO2014081246A1/en
Priority to CA2947571A priority patent/CA2947571C/en
Priority to US14/442,505 priority patent/US9981346B2/en
Priority to CN201610562938.1A priority patent/CN106077993B/en
Priority to CN201610562233.XA priority patent/CN106086625B/en
Priority to CA2890476A priority patent/CA2890476C/en
Publication of KR20140067803A publication Critical patent/KR20140067803A/en
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Publication of KR101449150B1 publication Critical patent/KR101449150B1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Arc Welding In General (AREA)
  • Nonmetallic Welding Materials (AREA)

Abstract

중량%로 C: 0.05~1.30%, Si: 0.2~1.8%, Mn: 0.4~23%, Cr: 0.01~12%, Ni: 23~49%, Mo, Co 및 W 중 1종 이상: 0.01~10%, Al: 0.2%이하, Ti:0.9%이하, Nb 및 V 중 1종 이상: 0.9% 이하, S 및 P 중 1종 이상: 0.035%이하, 잔부 Fe 및 기타 불가피한 불순물로 이루어지는, 극저온강의 용접이음부가 제공된다.
본 발명에 따르면, 극저온 환경에서 충격인성이 우수하고, 상온 항복강도가 뛰어난 서브머지드, 플럭스코어드 및 가스메탈 아크 용접재료를 제공할 수 있다.Co: W: 0.01 to 12%, Ni: 23 to 49%, Mo: Co: W: 0.01 to 10% At least one of Nb and V: not more than 0.9%, at least one of S and P: not more than 0.035%, the balance being Fe and other unavoidable impurities, A welded joint is provided.
According to the present invention, it is possible to provide submerged, flux cored and gas metal arc welding materials excellent in impact toughness and excellent in room temperature yield strength in a cryogenic environment.

Description

극저온강의 용접이음부{WELDED JOINTS OF CRYOGENIC STEEL}{WELDED JOINTS OF CRYOGENIC STEEL}

본 발명은 극저온강의 용접이음부에 관한 것이다. 보다 상세하게는. 서브머지드, 플럭스코어드, 가스메탈 아크 용접으로부터 얻을 수 있는 용접이음부에 관한 것이다.The present invention relates to welded joints of cryogenic steel. More specifically, Welded joints obtainable from submerged, flux cored, and gas metal arc welding.

최근 LNG 수요의 폭발적 증가로 인해 극저온의 LNG의 수송ㆍ보관을 위한 수송설비 및 저장 탱크의 폭발적 증가가 일어나고 있다. LNG를 수송하거나 저장하는 탱크는 필연적으로 LNG 온도인 -162℃ 이하의 온도에서 충격에 충분히 견딜 수 있는 구조로 이루어져야만 한다. 이를 위해 극저온에서의 충격인성이 높은 소재로서대표적으로 사용되는 것은 Al, 9%Ni강, 스테인리스스틸(이하 STS)이다.
Recently, explosive increase in LNG demand has caused explosive increase in transportation facilities and storage tanks for transportation and storage of cryogenic LNG. Tanks that transport or store LNG must, inevitably, be constructed to withstand impact at temperatures below -162 ° C, the LNG temperature. For this purpose, Al, 9% Ni steel, and stainless steel (hereinafter referred to as STS) are typically used as materials having high impact toughness at cryogenic temperatures.

그러나, Al의 경우 낮은 인장강도로 인해 두꺼운 후판을 사용해야 하며 용접성이 불량하다는 문제점이 있다.
However, in the case of Al, there is a problem that a thick plate is required due to a low tensile strength and weldability is poor.

또한, 9%Ni강의 경우는 용접재료(Inconel 625 소재: Ni 50중량%이상, Cr 20중량%이상 함유)가 고가이고 용접부 항복강도가 낮다는 문제가 있고, STS는 높은 가격, 낮은 열변형율 및 극저온 보증 불가 등의 문제가 있다.
In addition, in the case of 9% Ni steel, there is a problem that the welding material (Inconel 625: at least 50% by weight of Ni and at least 20% by weight of Cr) is expensive and the yield strength of weld portion is low. STS has a high price, There is a problem such that the cryogenic temperature can not be guaranteed.

따라서, 오스테나이트 안정화 원소로서 Ni 대비 저가이면서도 용접성을 확보가능한 극저온용 고Mn계 용접이음부의 개발이 요구되고 있다.
Therefore, it is required to develop a high Mn-based welded joint having low cost and good weldability as compared with Ni as an austenite stabilizing element.

상기한 바와 같이, 극저온 영역인 -196℃ 이하에서 용접구조물의 안정성을 확보하기 위해서는 27J 이상의 충격인성을 나타내는 용접이음부 확보가 필수적이며, 또한, 구조체를 제조하기 위해서는 상온 항복강도가 360MPa이상을 갖는 용접이음부가 필요하다. 이를 해결하기 위한 수단으로는 기존에는 Ni 및 Cr 함량이 높은 소재(Ni 50중량%이상, Cr 20중량%이상 함유)를 사용하여 확보하고 있으나 합금함량 및 가격적인 면에서 낮은 수준의 용접이음부가 존재하지 않는 문제점이 있다.As described above, in order to secure the stability of the welded structure at -196 캜 or lower, which is the cryogenic temperature region, it is necessary to secure a welded portion exhibiting an impact toughness of 27 J or more. Further, in order to manufacture a structure, Welded joints are needed. As a means for solving this problem, a material having high Ni and Cr content (containing at least 50% by weight of Ni and at least 20% by weight of Cr) has been used as a means for solving the problem. However, There is a problem that does not exist.

본 발명의 일 측면은 극저온 환경에서도 인성이 우수한 오스테나이트 상으로 유지시킴과 동시에 용접시 고온균열을 방지하여 우수한 저온 충격인성 및 상온 항복강도를 갖는 서브머지드, 플럭스코어드 및 가스메탈 아크 용접이음부를 제시하고자 한다.
One aspect of the present invention is to provide a welded joint of a submerged, flux cored, and gas metal arc welding having excellent low temperature impact toughness and room temperature yield strength while maintaining a high toughness austenite phase in a cryogenic environment, I would like to present the genital part.

그러나, 본 발명이 해결하고자 하는 과제는 이상에서 언급한 과제로 제한되지 않으며, 언급되지 않은 또 다른 과제들은 아래의 기재로부터 당업자에게 명확하게 이해될 수 있을 것이다.However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

상기와 같은 목적을 달성하기 위하여, 본 발명의 일 측면은, 중량%로, C: 0.05~1.30%, Si: 0.2~1.8%, Mn: 0.4~23%, Cr: 0.01~12%, Ni: 23~49%, Mo, W 및 Co 중 1종 이상: 0.01~10%, Al: 0.2%이하, Ti:0.9%이하, Nb 및 V 중 1종 이상: 0.9% 이하, S 및 P 중 1종 이상: 0.035%이하, 잔부 Fe 및 기타 불가피한 불순물로 이루어지는, 극저온강의 용접이음부를 제공한다.In order to achieve the above object, one aspect of the present invention provides a method of manufacturing a semiconductor device, comprising: 0.05 to 1.30% of C, 0.2 to 1.8% of Si, 0.4 to 23% of Mn, 0.01 to 12% of Cr, At least one of S and P; at least one of S and P; at least one of Mo and W; at least one of Mo and W; : 0.035% or less, the balance Fe and other unavoidable impurities.

본 발명의 일 측면에 따르면, 극저온 환경에서 충격인성이 우수하고, 상온 항복강도가 뛰어난 서브머지드, 플럭스코어드 및 가스메탈 아크 용접이음부를 제공할 수 있다.According to an aspect of the present invention, it is possible to provide a submerged, flux cored and gas metal arc welded joint having excellent impact toughness and excellent room temperature yield strength in a cryogenic environment.

이하, 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자가 용이하게 실시할 수 있도록 본 발명의 극저온강의 용접이음부에 대하여 구체적으로 설명하도록 한다.
BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

일반적으로, 극저온용 고Mn강은 LNG 저장 탱크용으로 사용되는 9%Ni강, STS 304강 등을 대체하기 위해 고Mn을 첨가시킨 강으로 극저온에서도 안정한 오스테나이트 조직을 형성해 추가 열처리 등이 필요하지 않고 용접시 열영향부(HAZ)부에서 인성 열화가 없는 특성을 보유하고 있는 것으로 알려져 있다.
In general, high Mn steel for cryogenic temperature is high Mn added steel to replace 9% Ni steel and STS 304 steel used for LNG storage tanks. It forms stable austenitic structure even at very low temperatures, And it is known that it possesses the characteristic that there is no toughness deterioration in the heat affected zone (HAZ) part during welding.

본 발명의 극저온강의 용접이음부는 극저온용 해양구조물, 에너지, 조선 및 압력용기 등에 사용되는 극저온용 고Mn강을 서브머지드, 플럭스코어드 및 가스메탈 아크 용접(SAW, FCAW and GMAW)함으로써 얻을 수 있는 용접이음부로서 우수한 저온 충격인성 갖도록 설계된다. 따라서, 극저온 환경에서 인성이 우수한 오스테나이트 상으로 유지시킴과 동시에 용접시 고온균열을 방지하도록 성분을 제어함으로써, 우수한 저온 충격인성 및 상온 항복강도를 가진 서브머지드, 플럭스코어드 및 가스메탈 아크 용접 이음부를 제공하게 한다.
The welding part of the cryogenic steel of the present invention is obtained by submerged, flux cored and gas metal arc welding (SAW, FCAW and GMAW) for cryogenic high Mn steel for use in cryogenic marine structures, energy, shipbuilding and pressure vessels And is designed to have excellent low-temperature impact toughness as a welded joint. Therefore, submerged, flux cored and gas metal arc welding with excellent low temperature impact toughness and room temperature yield strength can be achieved by controlling the components so as to keep the toughness of the austenite phase in a cryogenic environment and prevent high temperature cracking during welding Thereby providing a joint.

이를 위하여, 본 발명의 일 측면은, 중량%로, C: 0.05~1.30%, Si: 0.2~1.8%, Mn: 0.4~23%, Cr: 0.01~12%, Ni: 23~49%, Mo, W 및 Co 중 1종 이상: 0.01~10%, Al: 0.2%이하, Ti:0.9%이하, Nb 및 V 중 1종 이상: 0.9% 이하, S 및 P 중 1종 이상: 0.035%이하, 잔부 Fe 및 기타 불가피한 불순물로 이루어지는, 극저온강의 용접이음부를 제공한다.
In one aspect of the present invention, there is provided a ferritic stainless steel comprising 0.05 to 1.30% of C, 0.2 to 1.8% of Si, 0.4 to 23% of Mn, 0.01 to 12% of Cr, 23 to 49% of Ni, At least one of W and Co: 0.01 to 10%, Al at 0.2% or less, Ti at 0.9% or less, at least one of Nb and V at 0.9% or less, at least one of S and P at 0.035% The balance Fe, and other unavoidable impurities.

상기 각 성분의 수치 한정 이유를 설명하면 다음과 같다. 이하, 각 성분의 함량 단위는 특별히 언급하지 않은 경우에는 중량%임에 유의할 필요가 있다.
The reason for limiting the numerical values of the above components will be described as follows. Hereinafter, it is necessary to pay attention that the content unit of each component is weight% unless otherwise stated.

C(탄소): 0.05~1.30%C (carbon): 0.05 to 1.30%

C는 용접금속의 강도를 확보하고, 용접금속의 극저온 충격인성 확보를 위한 오스테나이트 안정화 원소로 현존하는 가장 강력한 원소이며, 아울러, 침입형 원소로 상온 항복강도를 증가시킬 수 있는 필수적인 원소이다. 그러나 C함량이 0.05%미만으로 첨가될 강도가 낮아지므로 이를 대체할 수 있는 합금원소의 함량이 증가되어야 한다. 외와는 반대로, 1.30%초과 함유하는 경우 용접시 Mn, Cr 등의 합금원소와 결합하여 MC, M23C6 등의 카바이드를 생성하여 저온에서 충격인성 저하 및 균열이 발생되는 문제점이 있다.
C is the most powerful element existing as an austenite stabilizing element for securing the strength of the weld metal and securing the impact resistance of the weld metal at a cryogenic temperature and is an indispensable element capable of increasing the room temperature yield strength with an interstitial element. However, as the C content is less than 0.05%, the strength to be added is lowered, so that the content of the alloying element that can replace it must be increased. Contrary to the above, when it is contained in an amount exceeding 1.30%, there arises a problem that a shock toughness deteriorates and cracks are generated at low temperature by producing carbide such as MC and M23C6 in combination with alloying elements such as Mn and Cr at the time of welding.

실리콘(silicon( SiSi ): 0.2~1.8%): 0.2 to 1.8%

Si의 함량이 0.2% 미만인 경우에 용접금속 내의 탈산효과가 불충분하고 용접금속의 유동성을 저하시키며, 1.8%를 초과하는 경우에는 용접금속 내에 편석 등을 유발하여 용접이음부에 크랙을 발생시키는 문제점을 갖는다.
If the content of Si is less than 0.2%, the deoxidizing effect in the weld metal is insufficient and the flowability of the weld metal deteriorates. If the content of Si exceeds 1.8%, segregation occurs in the weld metal, .

망간(manganese( MnMn ): 0.4~23%): 0.4 to 23%

Mn은 저온안정상인 오스테나이트를 생성시키는 주요 원소로 필수적으로 첨가되어야 하는 소재이며, Ni에 비해 매우 저렴한 원소이다. 0.4% 미만이 첨가될 경우 충분한 오스테나이트가 생성되지 않음으로 인해 극저온에서의 인성이 매우 낮게 발생하며, 23%를 초과하면 편석의 과다 및 고온균열의 유발, 유해한 흄(Fume)의 발생 등의 단점이 있다.
Mn is an essential element which is a key element for producing austenite which is a stable low-temperature phase, and is a very inexpensive element compared to Ni. When less than 0.4% is added, sufficient austenite is not produced, resulting in very low toughness at a very low temperature. When the content exceeds 23%, disadvantages such as excessive segregation and high temperature cracking and generation of harmful fumes .

크롬(chrome( CrCr ): 0.01~12% ): 0.01 to 12%

Cr은 페라이트 안정화 원소로 일정 Cr의 첨가를 통해 오스테나이트 안정화 원소의 함량을 낮출 수 있는 장점을 나타내며, 내부식성 및 강도를 향상시키는 원소로서 작용하게 된다. Cr의 함량은 0.01중량%이상 소량 첨가되어도 강도 향상 및 내부식특성 향상이 된다. 그러나, 12%를 초과하는 Cr이 첨가될 경우 Cr계 탄화물의 과다생성으로 인해 극저온 인성이 낮아지는 문제점이 있다.
Cr is an element stabilizing ferrite and shows the advantage of lowering the content of austenite stabilizing element through addition of certain Cr, and acts as an element improving corrosion resistance and strength. When Cr is added in a small amount of 0.01 wt% or more, the strength and the corrosion resistance are improved. However, when Cr exceeding 12% is added, there is a problem that the cryogenic toughness is lowered due to excessive production of Cr-based carbide.

니켈(nickel( NiNi ): 23~49%): 23 ~ 49%

Ni은 오스테나이트 안정화 원소로 필수적으로 첨가되어야 하는 소재이나, 매우 높은 가격대를 유지함으로 인해 23~49%를 유지하는 것이 바람직하며, 극저온 충격인성을 증가시키는 역할을 담당하지만, Ni를 첨가시 상온 항복강도가 낮아지는 특성을 나타내므로 23~49% 수준이 적당하다.
Ni is an essential material to be added as an austenite stabilizing element, but it is desirable to maintain 23 to 49% because it maintains a very high price range. It plays a role of increasing cryogenic impact toughness. However, when Ni is added, Since the strength is lowered, 23 ~ 49% is suitable.

몰리브덴(molybdenum( MoMo ), 코발트(), Cobalt CoCo ) 및 텅스텐(W) 중 1종 이상: 0.01%~10% ) And tungsten (W): 0.01% to 10%

Mo, Co, W은 기지의 항복 및 인장 강도를 향상시키는 원소로 0.01중량%이상 소량 첨가되어도 강도를 향상시키는 효과를 발휘하지만, 10%를 초과하는 경우에는 이들의 탄화물 생성을 촉진하여 극저온 인성을 저하시키는 단점이 있다.
Mo, Co, and W are elements that improve the yield and tensile strength of the matrix. However, when Mo is added in an amount of 0.01 wt% or less, the effect of improving the strength is exhibited. .

알루미늄(aluminum( AlAl ): 0.2%이하 ): Not more than 0.2%

Al를 첨가할 경우 강도를 감소시키며, 아울러, SFE(Stacking Fault Energy)를 증가시켜 저온에서의 인성을 확보할 수 있게 만드는 역할을 한다. 그러나, 0.2%를 초과하는 성분이 포함될 경우 산화물이 과다하게 용접부에서 발생함으로 인해 극저온 충격인성을 저하시키는 단점이 있다.
When Al is added, the strength is decreased. In addition, SFE (Stacking Fault Energy) is increased to ensure toughness at low temperatures. However, when a component exceeding 0.2% is contained, oxide is excessively generated at the welded portion, which causes a deterioration in cryogenic impact toughness.

타이타늄(Titanium ( TiTi ): 0.9% 이하): Not more than 0.9%

Ti를 첨가할 경우 항복강도와 인장강도를 증가시키는 역할을 하게 된다. 그러나, 0.9%를 초과하는 성분이 포함될 경우 용접부에서 크랙을 발생시키는 단점이 있다.
When Ti is added, it serves to increase yield strength and tensile strength. However, when a component exceeding 0.9% is contained, cracks are generated in the welded portion.

니오븀(Niobium ( NbNb ) 및 바나듐(V) 중 1종 이상: 0.9%이하) And vanadium (V): not more than 0.9%

Nb와 V는 상온 강도를 증가시키는 원소이며, 이들 원소가 0.9%를 초과하는 경우에는 크랙이 발생하므로 중량%로 0.9%이하를 갖는 것이 바람직하다.
Nb and V are elements which increase the strength at room temperature. When these elements exceed 0.9%, cracks are generated. Therefore, it is preferable that Nb and V are not more than 0.9% by weight.

황(S) 및 인(P) 중 1종 이상: 0.035%이하At least one of sulfur (S) and phosphorus (P): not more than 0.035%

S와 P은 전형적인 고온균열을 발생시키는 원소로, 가급적 낮은 수준으로 관리되어야 하며, 불가피하게 첨가되더라도 0.035%이하 수준으로 관리되어야 한다.
S and P are typical elements that generate high-temperature cracks and should be managed at a level as low as possible, and even if added inevitably, they should be maintained at a level of 0.035% or less.

상기 필수적인 성분들 이외에, 본 발명의 용접이음부는 중량%로 N: 0.001~0.6% 및 B: 0.0001~0.008% 중의 1종 또는 2종 이상을 더 포함하여 본 발명의 효과를 더욱 향상시킬 수 있다.
In addition to the essential components, the weld joint of the present invention further includes one or more of N: 0.001 to 0.6% and B: 0.0001 to 0.008% by weight, thereby further improving the effect of the present invention .

질소(N): 0.001~0.6%Nitrogen (N): 0.001 to 0.6%

N은 강도를 증가시키며 C과 동일한 특성을 나타내는 원소이다. 0.6% 초과의 경우 용접부에서 기공이 발생되므로 0.6%이하로 유지하여야 하며, 더구나, 0.75%이상 용접이음부에 함유될 경우 질화물이 과다하게 생성되어 충격인성이 저하되는 단점이 있다.
N is an element that increases strength and exhibits the same properties as C. If it exceeds 0.6%, porosity will be generated in the welded portion. Therefore, it should be maintained at 0.6% or less. Further, when the welded portion is contained in the welded portion of 0.75% or more, excessive nitride is formed and impact toughness is deteriorated.

보론(B): 0.0001~0.008%Boron (B): 0.0001 to 0.008%

B은 침입형 강도증가 원소로 미소량을 첨가하더라도 항복 및 인장강도를 증가시킬 수 있는 장점을 갖고 있다. 그러나, 다량 첨가될 경우 크랙이 발생하므로 0.008%이하로 관리되어야 한다.
B has the advantage of increasing the yield and tensile strength even when a small amount is added to the interstitial strength increasing element. However, if it is added in a large amount, cracks are generated, so it should be controlled to 0.008% or less.

본 발명의 나머지 성분은 철(Fe)이다. 다만, 통상의 제조과정에서는 원료 또는 주위 환경으로부터 의도되지 않는 불순물들이 불가피하게 혼입될 수 있으므로, 이를 배제할 수는 없다. 이들 불순물들은 통상의 제조과정의 기술자라면 누구라도 알 수 있는 것이기 때문에 그 모든 내용을 특별히 본 명세서에서 언급하지는 않는다.
The remainder of the present invention is iron (Fe). However, in the ordinary manufacturing process, impurities which are not intended from the raw material or the surrounding environment may be inevitably incorporated, so that it can not be excluded. These impurities are not specifically mentioned in this specification, as they are known to any person skilled in the art of manufacturing.

본 발명의 용접 이음부는 상기 성분들을 포함하면서도, 상기 Mo, Co 및 W 중 1종 이상(이하, 'Mo+W+Co'로 표기함), Nb 및 V 중 1종 이상(이하, 'Nb+V'로 표기함), Ni, Cr, Al, Ti은 하기 관계식 1을 만족할 수 있다. The weld joint of the present invention includes at least one of Mo, Co and W (hereinafter referred to as' Mo + W + Co '), Nb and V (hereinafter referred to as' Nb + V '), Ni, Cr, Al, and Ti can satisfy the following relational expression (1).

(관계식 1) 1.5Ni - 8Cr - 2.5(Mo+W+Co) - 20Al - 29Ti - 55(Nb+V) ≥ 0 ( Mo + W + Co) - 20Al - 29Ti - 55 (Nb + V)? 0

상기 관계식 1을 만족하는 경우, 극저온인 -196℃에서 충격인성이 27J이상을 유지할 수 있다.
When the above relational expression 1 is satisfied, impact toughness of 27 J or more can be maintained at -196 캜 which is a cryogenic temperature.

또한, 본 발명의 용접 이음부는 상기 성분들을 포함하면서도, 상기 C, Mn, Cr, Ni, Mo+Co+W, Ti 및 Nb+V은 하기 관계식 2를 만족할 수 있다. Further, the weld joint of the present invention includes the above components, but C, Mn, Cr, Ni, Mo + Co + W, Ti and Nb +

(관계식 2) 98.5C - 1.08Mn + 9.73Cr - 1.52Ni + 10.3(Mo+W+Co) + 122Ti + 34.7(Nb+V) ≥ 0 ( Mo + W + Co) + 122Ti + 34.7 (Nb + V)? 0 (Mo + W + Co) + 98.7C - 1.08Mn + 9.73Cr - 1.52Ni + 10.3

상기 관계식 2를 만족하는 경우, 상온에서의 항복강도가 360Mpa 이상을 나타낼 수 있다.
When the above-mentioned relational expression (2) is satisfied, the yield strength at room temperature may be 360 MPa or more.

또한, 본 발명의 용접 이음부는 상기 성분들을 포함하면서도, 상기 Si, Al 및 Ti는 하기 관계식 3을 만족할 수 있다.Further, the weld joint of the present invention includes the above components, but Si, Al, and Ti can satisfy the following relation (3).

(관계식 3) Si+Al+Ti ≤ 2.0 (Relational expression 3) Si + Al + Ti? 2.0

Si+Al+Ti > 2.0의 경우에는 균열이 발생될 수 있기 때문에 이와 같이 제어한다.
In the case of Si + Al + Ti > 2.0, cracks may be generated and thus controlled.

이하, 실시예를 통해 본 발명을 상세히 설명한다. 다만, 하기 실시예는 본 발명을 보다 상세히 설명하기 위한 예일 뿐, 본 발명의 권리범위를 제한하지는 않는다.
Hereinafter, the present invention will be described in detail with reference to Examples. However, the following examples are only for illustrating the present invention in more detail and do not limit the scope of the present invention.

[[ 실시예Example ]]

용접방법을 달리하면서 하기 표 1 및 표 2에 나타낸 바와 같은 성분을 갖는 용접 이음부를 준비하였다. 각 성분의 함량 단위는 중량%이다.
Weld joints having the components shown in the following Tables 1 and 2 were prepared while changing the welding method. The content unit of each component is% by weight.

용접방법으로는 서브머지드 아크 용접(SAW; Submerged Arc Welding), 플럭스코어드 아크 용접(FCAW; Flux Corded Arc Welding), 가스메탈 아크 용접(GMAW(or MCW); Gas Metal Arc Welding)을 실시하였다.As the welding method, Submerged Arc Welding (SAW), Flux Corded Arc Welding (FCAW), Gas Metal Arc Welding (GMAW (or MCW)) were performed .

SAW의 경우 플럭스 AB계(일반 상용 플럭스)를 사용하여 입열량 2.4~3.0 kJ/mm으로 용접을 실시하였다. In the case of SAW, welding was carried out with 2.4 ~ 3.0 kJ / mm heat input using flux AB system (general commercial flux).

FCAW의 경우 100% CO2 조건에서 입열량 1.7 kJ/mm으로 용접을 실시하였다.For FCAW, welding was performed at 1.7 kJ / mm in 100% CO 2 condition.

GMAW(또는 MCW)의 경우 80%Ar+20%CO2 조건에서 입열량 1.7 kJ/mm으로 용접을 실시하였다.
In case of GMAW (or MCW), welding was carried out at 1.7 kJ / mm heat input under 80% Ar + 20% CO 2 condition.

이 후, 용접이음부의 균열기공 여부, -196℃에서의 충격인성, 상온 항복강도를 측정하여 하기 표 1 및 표 2에 함께 나타내었다. 충격인성(CVN@-196℃) 값의 단위는 J이며, 항복강도의 단위는 MPa이다. 또한 '＋'로 연결된 성분들은 해당 성분들의 1종 이상의 함량을 의미한다.
After that, whether or not cracks were formed in the weld joint, the impact toughness at -196 DEG C, and the yield strength at room temperature were measured and are shown in Tables 1 and 2 below. The unit of impact toughness (CVN @ -196 ℃ ) is J, and the unit of yield strength is MPa. Also, the components connected by '+' mean the content of one or more of the components.

Figure 112012098264118-pat00001
Figure 112012098264118-pat00001

Figure 112012098264118-pat00002
Figure 112012098264118-pat00002

상기 표 1 및 표 2의 결과를 통해 본 발명의 합금 성분 및 관계식을 만족하는 발명재의 경우 균일기공이 나타나지 않았으며, 충격인성은 -196℃의 극저온에서 모두 27J 이상으로 나타났으며, 상온 항복강도는 모두 360MPa 이상의 성능을 보여 준다.From the results shown in Tables 1 and 2, uniform pores were not found in the inventive material satisfying the alloy component and the relational expression of the present invention. The impact toughness was 27J or more at a cryogenic temperature of -196 ° C, All exhibit performance over 360 MPa.

반면에, 비교재의 경우는 균열기공, 충격인성, 항복강도 중 적어도 어느 하나에서 열위한 결과를 보여주어 용접이음부로서 부적격한 것으로 판명되었다.On the other hand, in the case of the comparative material, the results for heat in at least one of the crack pore, the impact toughness, and the yield strength were shown to be inadequate as a weld part.

Claims (7)

중량%로, C: 0.05~1.30%, Si: 0.2~1.8%, Mn: 0.4~23%, Cr: 0.01~12%, Ni: 23~49%, Mo, Co 및 W 중 1종 이상: 0.01~10%, Al: 0.2%이하, Ti:0.9%이하, Nb 및 V 중 1종 이상: 0.9% 이하, S 및 P 중 1종 이상: 0.035%이하, 잔부 Fe 및 기타 불가피한 불순물로 이루어지고, 상온 항복강도는 360MPa 이상인 극저온강의 용접이음부.Co: 0.05 to 1.30%, Si: 0.2 to 1.8%, Mn: 0.4 to 23%, Cr: 0.01 to 12%, Ni: 23 to 49% At least one of Nb and V: not more than 0.9%, at least one of S and P: not more than 0.035%, the balance being Fe and other unavoidable impurities, Welding of cryogenic steel at room temperature yield strength of 360MPa or more. 제 1항에 있어서,
상기 용접이음부는 중량%로 N: 0.001~0.6%, B: 0.0001~0.008% 중의 1종 또는 2종 이상을 더 포함하는, 극저온강의 용접이음부.The method according to claim 1,
Wherein the weld joint further comprises one or more of N: 0.001 to 0.6% by weight, and B: 0.0001 to 0.008% by weight. 제 1항 또는 제 2항에 있어서,
상기 Mo, Co 및 W 중 1종 이상(이하, 'Mo+Co+W'로 표기함), Nb 및 V 중 1종 이상(이하, 'Nb+V'로 표기함), Ni, Cr, Al, Ti은 하기 관계식 1을 만족하는, 극저온강의 용접이음부.
(관계식 1) 1.5Ni - 8Cr - 2.5(Mo+W+Co) - 20Al - 29Ti - 55(Nb+V) ≥ 03. The method according to claim 1 or 2,
(Hereinafter, referred to as 'Mo + Co + W'), at least one of Nb and V (hereinafter referred to as 'Nb + V'), Ni, Cr, Al , And Ti satisfies the following relational expression (1).
(Mo + W + Co) - 20Al - 29Ti - 55 (Nb + V)? 0 제 1항 또는 제 2항에 있어서,
상기 Mo, Co 및 W 중 1종 이상(이하, 'Mo+Co+W'로 표기함), Nb 및 V 중 1종 이상(이하, 'Nb+V'로 표기함), C, Mn, Cr, Ni, Ti은 하기 관계식 2를 만족하는, 극저온강의 용접이음부.
(관계식 2) 98.5C - 1.08Mn + 9.73Cr - 1.52Ni + 10.3(Mo+W+Co) + 122Ti + 34.7(Nb+V) ≥ 03. The method according to claim 1 or 2,
(Hereinafter referred to as 'Mo + Co + W'), one or more of Nb and V (hereinafter referred to as 'Nb + V'), C, Mn, Cr , Ni and Ti satisfy the following relational expression (2).
(Mo + W + Co) + 122Ti + 34.7 (Nb + V)? 0 (Mo + W + Co) + 98.7C - 1.08Mn + 9.73Cr - 1.52Ni + 10.3 제 1항 또는 제 2항에 있어서,
상기 Si, Al 및 Ti는 하기 관계식 3을 만족하는, 극저온강의 용접이음부.
(관계식 3) Si+Al+Ti ≤ 2.03. The method according to claim 1 or 2,
Wherein the Si, Al, and Ti satisfy the following relational expression (3).
(Relational expression 3) Si + Al + Ti? 2.0 제 1항 또는 제 2항에 있어서,
상기 용접이음부의 충격인성은 -196℃의 극저온에서 27J 이상인 것인, 극저온강의 용접이음부.3. The method according to claim 1 or 2,
Wherein the impact toughness of the weld joint is at least 27 J at a cryogenic temperature of -196 캜. 삭제delete
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