• Journal of Advanced Marine Engineering and Technology
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• 제37권8호
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• pp.877-885
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• 2013

선박 기관실의 해수 배관은 염소이온 농도와 전기 전도성이 높은 해수가 빠른 속도로 유동하는 환경에 놓여 있게 된다. 따라서 부식성이 강한 염소 이온으로 인해 배관 내부에 국부 부식이 발생하여 해수가 누설되는 경우가 종종 발생하고 있다. 그래서 해수 배관의 누설 부위에 대해 일반적으로 선박 내에서 여러 가지 피복아크용접봉을 사용하여 교류 아크용접기로 보수용접을 한다. 본 연구에서는 해수파이프 등에 E4301, E4311, E4313 및 E4316과 같은 피복아크용접봉으로 용접한 경우, 용접부위에 대해 영역별로 내식성 차이를 전기화학적 방법으로 비교 분석하고, 각각의 용접부위에 대한 미세조직 관찰 및 미소 비커스 경도를 측정하였다. E4313의 용접봉을 사용한 용접부가 다른 용접봉을 사용한 용접부에 비해 가장 낮은 경도 값을 나타내었으나 내식성은 가장 우수하게 나타나고 있다. 그리고 용접봉의 종류에 관계없이 용접부는 모재보다 상대적으로 내식성이 더 우수하였고, 경도도 더 높은 값을 나타내었다.

• 한국공작기계학회논문집
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• 제14권3호
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• pp.87-95
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• 2005

The object of this study is to investigate the effect of joinability by using acoustic emission(AE) signals and doing a pattern recognition for weld heat affected zone(HAZ) in tensile testing. This study was carried out an SWS 490A high tension steel for electric shielded metal arc welding(SMAW), $CO_2$ gas arc welding and TIG welding. And correspondingly, the root openings are 3, 4 and 2.8mm. The results of the tensile test of weld HAZ come out electric shield arc welding $>\;CO_2$ gas arc welding > TIG welding in case of single welding. It is believed that this is a phenomenon where difference of its root opening or base metal thickness. Also, the technique of AE is ideally suited to study variables which control time and stress dependent fracture or damage process in metallic materials.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.40-48
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• 2004

The object of this study is to investigate the effect of joinability by using acoustic emission (AE) signals and doing a pattern recognition for weld heat affected zone (HAZ) in tensile testing. This study was carried out an SWS 490A high tension steel for electric shielded metal arc welding (SMAW), $CO_2$ gas arc welding and TIG welding. And correspondingly, the root openings are 3, 4 and 2.8mm. The results of the tensile test of weld HAZ come out electric shield arc welding > $CO_2$ gas arc welding > TIG welding in case of single welding. It is believed that this is a phenomenon where difference of its root opening or base metal thickness. Also, the technique of AE is ideally suited to study variables which control time and stress dependent fracture or damage process in metallic materials.

• 한국산학기술학회논문지
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• 제6권2호
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• pp.122-128
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• 2005

본 연구에서는 구조용강 SM520을 사용하여 교량용 박스 제작시 플럭스 코어드 아크용접법에서 가스실드방식과 셀프실드방식의 두 공정으로 제작된 용접부를 건전성, 기계적 성질 및 미세조직에서 비교하였다. 그 결과 두 용접 프로세스에 의해 제작된 용접부들은 매크로 조직 및 비파괴 검사 결과 건전성이 입증되었고, 항복 및 인장강도가 각각 $462{\sim}549\;MPa$와 $548{\sim}640\;MPa$였고, CVN 충격치는 $-20^{\circ}C$에서 요구값인 40J을 충족하였다. 결과적으로, 고속철도나 고속도로 건설시 사용되는 교량용 SM520강 박스 제조시 고소 및 강풍 조건하에서 용접할 때 셀프실드 아크용접법은 기존의 가스실드 아크 용접법과 비교하여 대등한 용접 특성들을 보였기 때문에 현장 시공시 적용 타당성이 있다고 사료된다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.363-370
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• 2003

The object of this study is to investigate the effect of compounded welding by using an acoustic emission (AE) signals and doing a source location for weld heat affected zone (HAZ) through tensile testing. This study was carried out a SM 490A high tension steel for electronic shielded metal arc welding (SMAW), $CO_2$ gas arc welding and TIG welding. Data displays are based on the measured parameters of the AE signals, along with environmental variables such as time and load. These history plots are displays showing the chronological course of the test. Also, source location gives the X- and Y-coordinates of the AE source.

• 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.

• 한국산업보건학회지
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• 제4권1호
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• pp.71-80
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• 1994

This study was conducted to evaluate worker exposure to welding fume in automobile body shop and to evaluate metal components by type of welding. The results are summarized as follows: 1. Average concentrations of total welding fume without and with ventilation were $5.2mg/m^3$ and $2.49mg/m^3$, respectively. Thus, the average reduction rate of total fume by ventilation was 52.1 %. 2. The highest fume concentration was indicated at shielded arc welding, followed by $CO_2$ gas welding, argon arc welding, and spot welding in order of decreasing concentration. 3. Average respirable fume concentrations without and with ventilation were $2.97mg/m^3$ and $1.64mg/m^3$, respectively. 4. Further analysis of welding fume indicated that total fume consisted of $Fe_2O_3$, ZnO, Mn, Pb, and CuO, in order of decreasing amount. Combined effect of metals was below the American Conference of Governmental Industrial Hygienists (ACGIH)Threshold Limit Values (TLVs).

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.244-249
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• 2007

In several locations of the pressurized water reactors, dissimilar metal welds using inconel welding wires are used to join the low alloy steel nozzles to stainless steel pipes. To evaluate the integrity and design the dissimilar welds, tensile and fracture properties variations are needed. In this study, dissimilar metal welds composed of SA508 Gr.3 LAS, inconel 82/182 weld, and TP316 stainless steel were prepared by gas tungsten arc welding and shielded metal arc welding technique. Microstructures were observed using optical and electron microscopes. Different tensile and fracture properties were observed depending on the specimen sampling position at room temperature and $320^{\circ}C,$ and that was discussed based on the microstructure characteristics. It was found that the strength at the bottom of weld was greater than at the top of the weld. Also, from the test data using small punch specimen, more detailed tensile property variations were evaluated.

• 한국산학기술학회논문지
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• 제20권8호
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• pp.649-656
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• 2019

조선소, 교량 구조물, 건설기계, 플랜트 산업 등 다양한 분야에서 폭 넓게 활용되고 있는 이산화탄소 아크용접(FCAW: Flux Cored Arc Welding)은 피복 아크 용접(SMAW: Shielded Metal Arc Welding)의 단점을 보완하기 위한 대안으로 1950년대 초 개발되었다. FCAW는 모든 자세에서 용접이 가능하고 작업여건 변수가 많은 현장에서 우수한 품질을 얻을 수 있는 장점이 있어 탄소강과 합금강의 중판, 후판 용접에 많이 사용되고 있다. 본 연구에서는 FCAW를 이용하여 SS400(일반구조용 압연강재)와 SM490A(용접구조용 압연강재)를 이종용접한 후 용접부의 기계적 특성(인장시험, 굽힘시험, 경도시험, 충격시험, 매크로시험)을 분석하고 다음과 같은 결론을 도출하였다. 인장시험 결과, 모든 용접자세에서 KS 규격 인장강도 범위($400{\sim}510N/mm^2$)를 만족하였다. 굽힘시험 결과, 대부분의 시편에서 굽힘시 표면의 터짐 현상이나 기타 결점이 나타나지 않았고, 소성변형 후에도 충분한 인성을 발휘하는 것을 확인할 수 있었다. 경도시험 결과, 모든 결과 값이 KS B 0893의 규격치 350Hv보다 낮게 나타나 양호한 것으로 판단된다. 충격시험 결과, 모든 결과가 KS 기준 수치인 27J 보다 큰 것으로 나타났다. 매크로시험 결과 용접부의 형상별로 균일한 조직 상태를 나타냈으며, 용접부 전단면에 걸쳐 내부 결함, 기포 또는 불순물 등이 발견되지 않아 라미네이션의 우려가 없는 것으로 나타났다.

• 한국산업보건학회지
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• 제10권1호
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• pp.32-44
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• 2000

The practice of welding stainless steel is known to produce various valance states of chromium. $CO_2$ flux cored arc welding on stainless was performed in fume collection chamber. Content of total chromium and hexavalent chromium in fumes, content of hexavalent chromium in total chromium, solubility of hexavalent chromium were investigated. Content of total chromium in fumes increases from 2~3% to 7~9% as a function of input energy, but hexavalent chromium, less than 1.2% in fumes, is not related to input energy. Hexavalent chromium in fumes exists as solubles up to 90%. Content of total chromium in flux cored arc welding fumes and solubility of hexavalent chromium are similar to shielded metal arc welding fumes, but content of hexavalent chromium is similar to metal inert gas welding fumes. These characteristics are relevant to flux of wires and $CO_2$ shielding gas.