• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년 추계학술발표대회 개요집
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• pp.128-129
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• 2006

To investigate impact property characteristics on the low temperature plate weld metal, the two different plates of the same steel grade were welded and evaluated by Mo bearing and no Mo containing welding consumables. The results are summarized as follows; 1) Multi pass welded Mo bearing weldment was not satisfied with the requirement of tensile strength, while no Mo containing one was satisfied with it 2) In the plate butt weldment, the impact property of weld metal was highly affected by both the welding consumable and plate.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2004년도 춘계 학술발표대회 개요집
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• pp.203-205
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• 2004

Welding sometimes should be done inside-hull after launching. The opposite side is contacted sea-water In this case, it should be a concern that the cooling rate expected very rapid may deteriorate microstructures, and hence these microstructures are hardened, cracking happens, or toughness would be impaired. Therefore, a test program simulating the situation has been planned and welded using the ship class materials (AH32, EH36) with the related welding consumables (E71Tl-1, E81Tl-K2) and then carried out to investigate the effect of cooling rate on weldments quality. Based on the test results, it could be concluded that the welds of which the opposite side of arc is exposed to wet or flowing water are not affected by rapid cooling.

• Journal of Welding and Joining
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• 제5권3호
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• pp.38-45
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• 1987

An investigation was conducted to find out the factors influencing on the impact toughness of austenitic-and duplex stainless steel weld metal. Various welding process with commerically available consumables was adopted to get weld doposited metal. The oxygen content of each weld metal was very sensitiive to welding process, involving flux composition, shielding gas and structural features. The results of this study show tat the content of oxygen as an oxide inclusion significantly affects impact toughness, and .delta.-ferrite distribution is also correlated with resultant toughness value.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.65-66
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• 2005

In order to evaluate disbonding properties caused by hydrogen on the Electro Slag Strip Welding for 1.25Cr-0.5Mo steel, two kinds of welding consumables were selected and tested under the disbonding condition of $97.2kgf/cm^{2}$ at $425^{\circ}C$. Chemical composition of the welds showed that they have similar chemical compositions. The microsturucture investigation, however, indicated that 'A' weld has high ratio of coarse grain area, while B weld has low. Disbonding results showed that high ratio coarse grain welds showed unacceptable, while low ratio coarse grain welds showed acceptable.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.127-128
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• 2007

To investigate mechanical property on the low temperature plate weld metal, the two different plates of the same steel grade were welded and evaluated on the multiple pass welds and both side one run welds with different Mo contents welding consumables. The results are summarized as follows; 1) Welds made by no Mo containing wire showed very low impact values for type of material company. 2) Welds made by 0.25%Mo containing wire showed good impact value regardless of both side one run welds and multiple pass welds. 3) Welds made by 0.5%Mo containing wire showed good impact value for both side one run welds, while it was not acceptable value for multiple pass welds.

• Nuclear Engineering and Technology
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• 제34권6호
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• pp.574-585
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• 2002

The microstructural characteristics and its related mechanical properties of RPV cladding have been investigated using small punch (SP) tests. SA508 Cl.3 RPV steel plates were overlay cladded with the type ER309L welding consumables by submerged arc welding process. Although the RPV clad material had a small portion of 5 ferrite phase, it still showed the ductile to brittle transition behavior The transition temperature was determined by the SP test and it depended on the content of $\sigma$ phase, specimen size, and determination methods. The fracture appearance of SP specimen was changed from circumferential to radial cracking as test temperature became low, and below the transition temperature region, ER309L cladding usually fractured along the 6 ferrite by the low temperature failure of ferrite phase.

• 대한금속재료학회지
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• 제47권3호
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• pp.195-201
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• 2009

This paper is concerned with effects of Mn and heat-input on the mechanical properties of EGW welds. Four different kinds of welding consumables were fabricated by varying Mn contents such as 1.3, 1.5, 1.7, 2.0%Mn and each consumable was welded for EGW on four heat-input conditions between 190 and 340 KJ/Cm. Mn contents were decreased as heat-input increases and alloy elements (C, Si, Ti, B, Al) to deoxidize easily also revealed similar tendency to Mn. Their microstructure, Charpy impact property and strength were investigated, and it is found that Charpy impact property and strength exhibit a strong dependence on change of microstructure by Mn contents and heat-input. The increase of Mn contents or the decrease of heat-input made the microstructure fine and increase volume fraction of acicular ferrite, thereby leading to the great improvement of Charpy impact property and strength. In case of single EGW, optimum Mn contents are over 1.7% for the toughness and strength.

• Journal of Welding and Joining
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• 제33권5호
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• pp.35-40
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• 2015

Characterization of microstructures and mechanical properties of 83mm thickness EH36-TM welds produced by the combined flux cored arc (FCA) and electro gas (EG) welding processes has been studied with the two different groove conditions, single-V (SV) and double-V (DV) bevels. The welding consumables used for FCA and EG welding processes were ASME/AWS A5.29 (E81T1-K2) and A5.26 (EG72T), respectively. Experimental results showed that all the mechanical properties of welds such as tensile property, CVN toughness and Vickers hardness met IACS requirements. The tensile strength of EG welded plates were reduced by approximately 4% (DV: 3.8%, SV: 4.2%) compared to the base metal. The hardness value of SV-beveled weld metal was slightly lower than that of DV-beveled one. There were no significant differences as per welding groove conditions except for the weld metal. In addition, at the fusion line, the toughness of SV condition was 20J lower and the weld metal was 40J lower than DV condition, respectively. On the basis of microstructural analysis, grain boundary ferrite (GBF) structures for SV condition were 2 times higher volume fraction than for DV condition and their packet sizes were coarsened to almost double. It was thus suggested that the GBF volume fractions and packet sizes in the weld metal of EH36-TM steel plates are the most important factors affecting the mechanical properties of the combined FCA and EG welded joint. Nevertheless, all the results of welds with both DV and SV conditions were found to be excellent.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2010년도 춘계학술발표대회 초록집
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• pp.69-69
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• 2010

최근 컨테이너 선박의 초대형화로 극후물 고장력 강재인 항복응력 460MPa급 고장력강인 EH47이 개발되었다. 두께 80mm의 극후물 용접에서 용접생산성 향상을 위하여 EGW/FCAW로 양면 용접이 검토되고, 입열량은 최대 300kJ/cm의 대입열 용접이 요구된다. 이를 위해서는 강재 및 용접재료 모두 300kJ/cm 용접부 성능이 선급 규격을 만족하여야 함은 물론 마지막 조립단계에서 적용되기 때문에 용접재료의 용접작업성도 매우 크게 요구되고 있다. 먼저 대입열 용접금속에서 요구되는 저온 충격인성($vE_{-20^{\circ}C}{\geq}57J$)을 만족하기 위하여는 용접금속의 미세조직 제어가 필요하며, 특히 조대한 입계페라이트 생성을 억제하고 미세한 입내 페라이트를 균일 분포하는 것이 중요하지만, 이를 위해 용접금속의 소입성이 지나치게 높이면 경화조직인 베이나이트 분율이 증가하여 오히려 용접금속 저온 충격인성을 저하시키므로, 적절한 용접금속의 성분 제어가 중요하다. 한편 용접부는 선급에서 요구하는 최소 강도인 570MPa를 만족하기 위하여 용접금속의 소성구속 현상을 활용하여 용접부 인장강도를 확보 할 수 있음을 확인했다. 이를 위해서는 용접금속의 적정한 경화도 확보가 필요하였다. 전술한 바와 같이 대입열 용접금속 저온 충격인성 확보와 용접부 강도 측면을 고려하여 용접금속 최적의 탄소당량 범위를 제시코자 하였다. 한편 용접재료의 용접작업성은 EGW용접의 용적이행 현상은 자유비행이행으로 이루어지고 있으며 특성상 용접중 용적과 용융지 사이에 많은 순간단락 현상을 동반하고 있으며, 슬래그 유동이 불안정하면 아크 꺼짐 현상도 관찰되고 있다. 따라서, 현장용접시 원할한 용접작업성을 확보할 수 있는 평가 기준으로써 아크 전류 및 전압의 변동 정도를 설정하고, 용접재료의 용접작업성 확보 기준을 제시코자 하였다.