• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년도 춘계 학술대회 개요집
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• pp.257-259
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• 2006

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년도 춘계 학술대회 개요집
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• pp.109-111
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• 2006

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.348-350
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• 2007

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1992년도 특별강연 및 추계학술발표 개요집
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• pp.196-198
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• 1992

• Journal of Welding and Joining
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• 제13권4호
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• pp.46-54
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• 1995

The cold cracking susceptibility of a variety of weld metals deposited by GMAW with several kinds of commercial solid wires for high strength-toughness steel was investigated. G-BOP test and LB-TRC test were carried out to study the effects of preheat, chemical composition and hydrogen level on the weld metal cold cracking. The results obtained are as follows. 1) 10% CPT obtained by G-BOP test was the most valuable criteria for evaluating the cold cracking susceptibility of weld metals compared with percentage of cracking at room temperature and crack free temperature, and it had good correlation with the results of LB-TRC test. 2) Cold cracking susceptibility of weld metals was high in the row of MG100A, MG100C, MG100D and MG100B. Welds deposited with MG130 and MG80 showed similar icidents of cracking with MG100C and MG100B respectively, even though their strength levels were different. 3) Diffusible hydrogen level in weld metals which has good relation with hydrogen content in wire itself was the most critical factor for controlling the cold cracking susceptibility of weld metal.

• 한국해양공학회지
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• 제13권3호통권33호
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• pp.49-56
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• 1999

Welding is a reliable process and is mainly adopted for fabricating heavy structures. Recently, transverse cracks in the weld metal is serious problem, and they affect cost, efficiency, safety and joint reliability for various welded structures. In this view of point, this study investigated the potential factors for weld metal transverse crack. The main results obtained are as follows; 1) The content of diffusible hydrogen in the commercial flux cored are welding wire was remarkable change by manufacturer. 2) The diffusible hydrogen content was thd main factor for weld metal transverse cracks. 3) Weld metal was immune to transverse cracking under the condition of low diffusible hydrogen content of high restraint condition. 4) The factors for weld metal transverse crack would be the content of diffusible hydrogen and restraint of weld joint.

• 대한기계학회논문집
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• 제17권8호
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• pp.2033-2042
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• 1993

In conventional SCC susceptibility test, there are constant strain test, constant load test, slow strain rate test(SSRT) and K$_{ISCC}$ test. Among them, the SSRT method is much more aggressive in producing SCC than the other tests, so that the test time of it is considerably reduced. But this SSRT method has mostly been worked using the uniaxial tensile specimen untill now. Therefore, the SSRT method using the tensile specimen(Ten-SSRT) has much difficulty in SCC susceptibility evaluation of a localized region like weldment and the advantage material of high order. Recentely, the small punch(SP) test method using miniaturized small specimen is the very effective test method for fracture strength evaluation of a localized region like weldment and fusion reactor wall irradiated in the nuclear power plant. This paper investigated the possibility of SCC susceptibility evaluation by the SP-SSRT method using the miniaturized small specimen. Therefore, we obtained the result that the SP-SSRT had the possibility for the evaluations of SCC susceptibility for shorter time to corrosive environment compare to Ten-SSRT which was conventional method.

• Journal of Welding and Joining
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• 제6권3호
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• pp.27-36
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• 1988

In fabrication of various welded structures made of high strength steels, the occurence of hydrogen assisted cracking and embrittlement in HAZ is prime importance. The present work was carried out to clarify the effect of chemical compositions, especially B and/or Ti addition on the cold cracking susceptibility and HAZ embrittlement in low crabon equivalent steel. Tests results showed that the addtio of optimum boron content in steel with low Pem value i.e., below 0.20 % was the best way to improve the weldability as well as the mechanicla properties of $60kg/mm^2$ grade quenched and tempered high strength steels.

• Journal of Welding and Joining
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• 제8권3호
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• pp.39-52
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• 1990

The research is to insure the soundness of the stainless steel overlaid weld metal(21/4Cr-IMo steel + SUS 309L) for a pressure vessel application. Detail studies were conducted for the PWHT influence on the micrstructure and intergranular corrosion characteristics of the overlaid weld metal as well as initiation of hydrogen embrittlement crack(or Disbonding) when welded metal are exposed to the hydrogen atmosphere. Hydrogen was experimentally charged to the overlaid weld metal in order to study PWHT effect on the susceptibility of hydrogen embrittlement crack. The results of this research are as follows: 1. At the bond region, austenite grain of the stainless steel side became coarsed and Cr23C6 type carbide was precipitated at the coarsed austenitic grain boundaries. Intergranular Corrosion width(by Straiss test) increased with increasing PWHT temperature and PWHT time.

• 한국재료학회지
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• 제3권4호
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• pp.361-371
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• 1993

응력부식균열(SCC) 감수성평가를 위한 여러 시험방법들중 저변형율시험방법은 비교적 \ulcorner은 시간내에 금속재료의 SCC감수성을 평가하기 위한 효과적인 시험방법이다. 그러나 저변형율 시험방법만으로 SCC과정의 미시적 파괴거동ㅇ르 분석하는 것은 매우 어렵다. 종래, 음향방출(AE)시험은 재료의 파괴과정시 미시균열의 개시 및 전파거동을 감시하는데 유효한 기법으로 잘 알려져 있다. 그러므로 본 논문에서는 저변형율시험과 음향방출시험을 이용하여 SCC의 전파과정과 AE신호 특성사이의 상호관계를 분석하였다. 실험결과, 재료의 미시파괴 과정에서 발생하는 AE신호들은 뚜렷히 시험환경에 의존하였으며, 인공해수중에서 SCC과정시 발생된 AE신호 특성은 Air상태 보다 상당히 크게 나타났다. 그리고 SCC거동은 AE신호의 진폭인자로서 명확하게 평가할 수 있다.