• 제목/요약/키워드: Underwater steel plate

검색결과 27건 처리시간 0.021초

TMCP강의 습식수중 아크용접부의 냉각특성 개선에 관한 연구 (Study on Cooling Characteristic Improvement in Underwater Wet Arc Welding of TMCP Steelplate)

  • 김민남
    • 한국해양공학회지
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    • 제6권2호
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    • pp.113-124
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    • 1992
  • The offshore industry created a need for quality wet weld repairs. Wet welding is a fast method of repair providing sound, structural quality welds. It requires less support equipment than a similar underwater dry weld repair or the alternative mechanical connections. Compared to welds made in air, underwater wet welds are plagued by increased hardness due to rapid quenching by the surrounding water. In this paper is described the experimntal study of improving the cooling rates of wet welds of TMCP steel plate by shielding around weld arc surroundings. The principal results of this experimental investigation can be summarized as follows : By shielding around weld arc surrounding, the cooling rates resulting from wet welds on TMCP steel plate could be lower than that of nonshielded wet welds and the fesibility on high quality of mecanical properties of wet weld on TMCP steel plate was carried out with shielded weld arc surrounding.

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수중강판의 결함 및 열화 검출을 위한 탄성파 유한요소 시뮬레이션 (Finite Element Simulation of Elastic Waves for Detecting Defects and Deteriorations in Underwater Steel Plates)

  • 우진호;나원배
    • 한국해양공학회지
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    • 제27권3호
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    • pp.61-66
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    • 2013
  • This paper presents the results of finite element simulations of elastic wave propagation in an underwater steel plate and the verification of a proposed method utilizing elastic wave-based damage detection. For the simulation and verification, we carried out the following procedures. First, three-dimensional finite element models were constructed using a general purpose finite element program. Second, two types of damages (mechanical defects and deteriorations) were applied to the underwater steel plate and three parameters (defect location, defect width, and depth) were considered to adjust the severity of the applied damages. Third, elastic waves were generated using the oblique incident method with a Gaussian tone burst, and the response signals were obtained at the receiving point for each defect or deterioration case. In addition, the received time domain signals were analyzed, particularly by measuring the magnitudes of the maximum amplitudes. Finally, the presence and severity of each type of damage were identified by the decreasing ratios of the maximum amplitudes. The results showed that the received signals for the models had the same global pattern with minor changes in the amplitudes and phases, and the decreasing ratio generally increased as the damage area increased. In addition, we found that the defect depth was more critical than the width in the decrease of the amplitude. This mainly occurred because the layout of the depth interfered with the elastic wave propagation in a more severe manner than the layout of the width. An inverse analysis showed that the proposed method is applicable for detecting mechanical defects and quantifying their severity.

Underwater Laser Cutting of Thick Stainless Steel in Various Cutting Directions for Application to Nuclear Decommissioning

  • Shin, Jae Sung;Oh, Seong Y.;Park, Seung-Kyu;Kim, Taek-Soo;Park, Hyunmin;Lee, Jonghwan
    • 방사성폐기물학회지
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    • 제19권3호
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    • pp.279-287
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    • 2021
  • For application in nuclear decommissioning, underwater laser cutting studies were conducted on thick stainless-steel plates for various cutting directions using a 6 kW fiber laser. For cutting along the horizontal direction with horizontal laser irradiation, the maximum cutting speed was 110 mm·min-1 for a 48 mm thick stainless-steel plate. For cutting along the vertical direction with horizontal laser irradiation, a maximum speed of 120 mm·min-1 was obtained for the same thickness, which confirmed that the cutting performance was similar but slightly better. Moreover, when cutting with vertically downward laser irradiation, the maximum cutting speed was 120 mm·min-1 for a plate of the same thickness. Thus, the cutting performance for vertical irradiation was nearly identical to that for horizontal irradiation. In conclusion, it was possible to cut thick stainless-steel plates regardless of the laser irradiation and cutting directions, although the assist gas rose up due to buoyancy. These observations are expected to benefit laser cutting procedures during the actual dismantling of nuclear facilities.

습식 수중 아크용접봉의 국산화개발에 관한 기초연구 (A Basic Study on the Development of Domestic Underwater Wet Arc Welding Electrode)

  • 김민남;김복인
    • Journal of Advanced Marine Engineering and Technology
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    • 제25권5호
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    • pp.1122-1129
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    • 2001
  • Underwater wet arc welding process was experimentally investigated by using the six types of flux coated electrodes of 3.2 mm diameter and the KR-RA steel plate of 11 mm thickness as base metal. Two types of electrodes were domestic covered arc welding electrode(CR13, CR14) and another two types of wet welding electrodes(UWCS, TN20)were imported goods, and the other two type (UWX1, UWX2) were individually designed flux coated electrodes for experimental welding purpose. Main experimental results are summerized as follows: 1. It is ascertained that individually designed flux coated electrode(UWX1) could be used in practice with KR-RA steel plate for underwater wet arc bead welds. 2. Welding arc can be generated easily and considerably kept in stable using TN20 and UWX1 electrodes. 3. The micro Vickers hardness value and the portion of martensite in the HAZ were increased in all the electrodes by rapid cooling rate, but it is relatively maintain stable for UWCS, TN20 and UWX1 electrodes.

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연강의 습식 수중 아크 용접 특성에 관한 연구 (A Study on the Properties of Underwater Wet Arc Welding for the Mild Steels)

  • 곽희환;김창규
    • 동력기계공학회지
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    • 제11권1호
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    • pp.107-114
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    • 2007
  • Underwater wet arc welds were experimentally performed on 11mm thick SS400 mild steel plate as base metal by using six different types of flux coated electrodes of 4.0mm diameter; KSKR, KSKT, USBL, JPUW, UWEA, and UWEB. As results, the developed flux coated underwater electrode had a good weldability compared with other domestic terrestrial electrodes. By rapid cooling rate, the hardness value of HAZ were increased by quenching effects. Mechanical properties for the multi-pass butt-welding specimen are also tested experimentally. The feasibility of the developed underwater electrode was experimentally studied and the results achieved in this wet arc welds have shown that the developed wet welding electrode UWEB can have a degree of integrity.

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SWS490강의 습식수중용접특성 (The Underwater Wet Welding Characteristics of SWS490 Steel)

  • Park, Gi-Yong;Lee, Sang-Yul;Lee, Byung-Hoon
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 1997년도 특별강연 및 추계학술발표 개요집
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    • pp.147-150
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    • 1997
  • The characteristics of underwater welding of SWS490 steel were investigated. The bead-on-plate type welding with one or three pass using ilmenite and water-proofed type electrodes was performed by varying welding currents and the sizes of electrodes used. The amounts of hydrogen absorbed inter the weld metal were measured according to the JIS Z 3118 specification and the results were interpreted in terms of the cold cracking behaviours of the welded steel. The microstructural changes as well as the microhardness distribution after underwater welding were also investigated using Vickers microhardness tester and S.E.M (scanning electron microscopy) and O.M (optical microscopy). The results indicated that the cold cracking could be avoided by three pass welding under low current with an electrode with a small diameter.

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피복성분에 의한 수중용접봉의 아크 안정성 개선에 관한 실험연구 (An Experimental Study on the Arc Stability Improvement of Underwater Wet Welding with Flux Ingredients)

  • 김복인;노창석;정교헌;김민남
    • 한국해양공학회지
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    • 제15권4호
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    • pp.73-79
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    • 2001
  • Underwater wet bead-on-plate welds were experimentally performed on 11mm thick SS400 steel plate as base metal by using six different types of flux coated electrodes of 3.2mm diameter. Two kinds of different flux coated wet arc electrodes (UW-1, UW-2) were individually designed flux materials, three kinds of the electrodes (E4301, E4311, E4313) were terrestrial electrodes and the another one (TN20) was an imported underwater wet welding electrode. As results, the individually designed flux coated underwater electrode, UW-2 and TN20 had a good starting and the excellent arc stability compared with other electrodes. No significant difference of bead appearance could be detected, but the slag detachability of TN20 electrodes was relatively undesirable. By rapid cooling rate, the hardness value and the portion of martensite of HAZ were increased, but it was considerably maintain stable for TN20 and UW-2 electrodes. The individually designed flux coated electrode, UW-2 could be used in practice for underwater bead welds.

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실드 수중용접의 교계에 관한 연구 (Study on Effect of Underwater Shield Welding)

  • 김민남;오세규;서강태;박정배
    • 한국해양공학회지
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    • 제5권1호
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    • pp.81-87
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    • 1991
  • In this paper, an attempt has been taken for improving the weldability of wer welds of TMCP steel plate by shielding around weld arc surroundings. The principal results of this experimental investigation can be summarized as follows: 1) The cooling rates resulting from wet wlds with the developed electrode on TMCP steel plate could be lower than that of the non-shieled wet welds. 2) The metallurgical characteristics in umderwater wet welds of TMCP steel plate and the developed electrode could be improved by shielding around weld arc surroundings.

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SMAW 수중 다층용접시 용접부 특성에 관한 연구 (A Study on the effect of the multi-pass SMAW welding on the characteristic of the underwater welding areas)

  • 최기용;이상율;이보영;이병훈;이상용;박성두
    • Journal of Welding and Joining
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    • 제16권4호
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    • pp.55-62
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    • 1998
  • While excellent joint quality has been obtained using dry chamber underwater welding methods, the size limitations imposed by this process restrict its use for underwater construction work. The wet underwater shielded metal-arc welding eliminates this restriction but suffers from poor weld properties by the 1-pass bead-on-plate welding due to the excessive diffusible hydrogen. On the other hand, in the wet underwater welding, it is well known that the quantity of diffusible hydrogen in multi-pass welded parts reduce to less than that in 1-pass welded parts. Therefore, in this paper, welding experiments are made the 3-pass bead-on-plate welds by using TMCP and normalized steel plates and E4301 and cellulose coated electrode. After that, The amounts of the hydrogen absorbed into the 3-pass welded area were measured according to the JIS Z 3118 specification. The microstructural changes as well as the microhardness distribution after the underwater 3-pass welding were also investigated using Vickers microhardness tester and S.E.M and O.M. The results indicated that the quantity of diffusible hydrogen in 3-pass welded areas was reduced little less than a half of one of that in 1-pass welded areas at the specific welding condition. As a result, the cold cracking of 3-pass welded areas decreased by reduced effect of diffusible hydrogen. In the underwater 3-pass welding, the micrography of cold cracking fracture surface showed mainly the cleavage of hydrogen embrittlement.

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유연재 코팅 평판의 난류 변동압력 특성에 관한 실험적 연구 (Experimental Study on the Characteristics of Turbulent Wall Pressure Fluctuation Over Compliant Coatings)

  • 박경훈;이승재;신구균
    • 한국음향학회지
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    • 제26권6호
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    • pp.293-300
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    • 2007
  • 수중운동체가 주행할 때 수중운동체의 표면에는 난류 경계층이 형성되고, 난류 경계층 내 벽면 변동압력은 탄성체인 수중운동체의 표면을 가진시켜 유동 유기 소음을 발생시킨다. 이러한 유체 소음을 감소시키기 위한 하나의 방법으로 수중운동체 표면에 유연재를 부착하여 수중운동체의 유동 유기 방사 소음을 감소시키는 방법이 제안되기도 한다. 본 논문에서는 유연재 부착에 따른 수중에서의 유체소음의 변화 특성을 살펴보기 위하여 유연재가 코팅되지 않은 강판 시편과, 고무 재질의 Neoprene 및 폴리우레탄 재질의 유연재가 부착된 강판시편을 저소음 공동수조에 설치한 후 여러 가지 유속 조건에서 유체소음의 주요 소음원인 난류 경계층 내 벽면 변동압력을 측정하고 그 결과를 비교 분석하였다. 그 결과 유연재를 코팅한 경우에는 유연재로 인하여 난류 경계층의 두께가 두꺼워지는 등 경계층 유동이 변화하지만, 유연재에서의 난류 에너지의 소산으로 인하여 고주파수 대역에서 약 10dB의 벽면 변동압력의 감소 효과를 확인할 수 있었다.