• Proceedings of the KWS Conference
• /
• 2002.10a
• /
• pp.418-424
• /
• 2002

Korean Fusion Reactor(KSTAR) system consists of a vacuum vessel, in-vessel components, cryostat, thermal shield, super-conducting magnets and magnet supporting structures. These systems are in the final stage of engineering design with the involvement of industrial manufacturers. The overall configuration and the detailed dimensions of the KSTAR structure have been determined and the first stage of manufacturing is progressing now. In this study, the fabrication and assembly sequence were evaluated in viewpoint of high strengthening joints and very high accuracy. Especially for this purpose, the special cleaning process and welding process were proposed for high strengthening austenitic stainless steel which shall be used at cryogenic temperature. The draft procedure qualification data for welding process are presented with precise welding data including special narrow groove design. For the cooling line attachment on the surface of inside wall of magnet structure case, Induction brazing technology is introduced with some special jigging system and some consumables.

• Proceedings of the KWS Conference
• /
• 2002.10a
• /
• pp.652-656
• /
• 2002

The HDM(Hole Drilling Method) is a relatively simple and accurate method in measuring residual stress of welded metal. Various methods of evaluating residual stress are studied in welding field. The method of cutting holes on the plate much affects the accuracy of result. Especially for the hard material like stainless steel difficult to cut preciously is difficult to measure residual stress on welded metal. Because heat conduction of stainless steel is lower than other general steel, the magnitude of residual stress might be different as to changing of welding conditions. Therefore, The distribution of residual stress on the STS304 steel after welding using HDM is evaluated in this paper.

• Journal of Welding and Joining
• /
• v.19 no.5
• /
• pp.548-554
• /
• 2001

The restraint force is required an accurate measurement and analysis to protect weldment from residual stress. Also, this residual stress caused by clacks in weldments are often observed in the weldments of large size nozzles or radial tanks after welding. This paper is preformed on the study of evaluation of welding restraint forces using load cell with STS thin plate which are using pressure vessel steel in the industry field. As a result of this study, as the welding currents are higher and the welding speeds are more slowly, the magnitude of restraint force in process of the flat plate welding hows to be more large. Also, the temperature in process of melting is increasingly rising, then the restraint forces exhibit the compressive forces, whereas the restraint forces during cooling represent extensional force.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2003.10a
• /
• pp.289-294
• /
• 2003

The object of this study is to investigate the effect of compounded welding by using acoustic emission (AE) signals fur weld heat affected zone (HAZ) in tensile testing. This study was carried out a SM 490A high tension steel for electronic shielded metal are welding (SMAW), $\textrm{CO}_2$ gas arc welding and TIG welding. And correspondingly, the root openings are 3, 4 and 2.8mm. Data displays are based on the measured parameters of the AE signals, along with environmental variables such as time and load. These history plots give us useful and powerful information to analyze the results of material evaluation testing.

• Journal of Welding and Joining
• /
• v.5 no.4
• /
• pp.12-21
• /
• 1987

To investigate the suitability of nitrogen gas as an internal purging gas, various properties of GTA welded joints of duplex, 316L stainless steel, Cu-Ni alloy pipe using nitrogen purging gas were evaluated with reference to onew purged with argon gas. Mechanical properties evaluated by the tensile, bending test, and hardness value of welded joints with nitrogen gas purging did not show any difference those with argon gas. General and local corrosion rates of each welded joint prepared by nitrogen gas purging also showed no difference with those prepared by argon gas. Based on the present test results it is confirmed that nitrogen is a suitable purging gas for GTA welding of stainless steels and nonferrous piping systems, which can be used at lower cost instead of argon.

• Journal of Welding and Joining
• /
• v.19 no.6
• /
• pp.664-670
• /
• 2001

The HDM(Hole Drilling Method) is a relatively simple and accurate methods in measuring residual stress of weldment. Various method of evaluating residual stress are studied in welding field. The method of cutting holes on the plate much affects the accuracy of result. Especially for the hard material like stainless which is difficult to cut preciously is difficult to measure residual stress of weldment. Because heat conduction of strainless steel is lower than other general steel, the magnitude of residual stress might be different as to changing of welding conditions. Therefore, the distribution of residual stress on the STS304 steel after welding using HDM is evaluated in this paper.

• Journal of Advanced Marine Engineering and Technology
• /
• v.19 no.4
• /
• pp.42-50
• /
• 1995

To study the effect of welding methods on the Stress Corrosion Cracking (SCC) behavior of welded AISI type 316L and 304 austenitic stainless steel, the Slow Strain Rate Technique(SSRT) has been adopted in the boiling 45 wt% $MgCl_2$ solution. The results are as follows. 1) Welded sections are more susceptible than base metal in SCC, and the rank of SCC, and the rasistance in welding method is TIG, MIG, $CO_2$ and ARC. 2) The Ultimate tensile strength(UTS) and the strain of both base metal and welded joint are reduced as decreasing extension rate. 3) The SCC resistance of 316L base metal and welded sections are superior than that of 304. 4) The tendency of pitting and the SCC suseptibility are agreed well, and the SCC site is welded deposit section in 316L whereas HAZ in 304.

• Proceedings of the KIPE Conference
• /
• 2002.07a
• /
• pp.665-668
• /
• 2002

Joining thin aluminum alloy is difficult using most wilding techniques. Many of problems associated burn-through by the high heat input Common welding techniques are TIG, MIG, and MIG-PULSE welding. The VP-GMAW provides more control of the heat balance in the voiding arc by taking advantage of the different arc characteristics obtained with each of the two polarities. In this paper, we proposed new VP_GMA Welding method by control DSP 320C32, and the characteristic and experiment result-voltage, current, welding bead. penentraion by this method are presented

• Journal of Welding and Joining
• /
• v.17 no.3
• /
• pp.50-54
• /
• 1999

Feasibility study of the application of a developed annealed austenitic stainless steel at cryogenic temperature has been performed for membrane tank of LNG ship. Chemical properties of developed stainless steel are compared with a domestic commercial stainless steel and a foreign stainless steel which are used for LNG ships. Tensile properties at cryogenic temperature and fatigue strength at room temperature are measured for but and lap joints which are TIG welded specimens. Developed stainless steel having a small amount of titanium component shows the finest grain size in the HAZ, compared with the other stainless steel studied. Tensile strength, elongation and fatigue strength of the developed stainless steel are equal to those of the foreign stainless steel studied and are higher than the domestic commercial stainless steel studied.

• Journal of the korean Society of Automotive Engineers
• /
• v.13 no.6
• /
• pp.39-47
• /
• 1991

본 연구논문의 내용은 현재 국내 자동차 업계에서 자동차 배기부품으로 전량 수입되고 있는 STS 409L 스테인레스강을 국산화하기 위한 개발연구에 대한 내용으로서 배기관용 스테인레스강 409L의 제조기술과 관련된 국내외 기술개발 동향과 포항제철 스테인레스 제조설비에 맞는 적정합금성분계와 조업조건을 도출하기 위하여 실험적으로 시험조사하여 품질 제특성을 평가한 연구결과이다. 주요 내용으로서 합금원소가 열연 및 냉연 소둔조업조건에 미치는 영향을 조사하기 위하여, C, N과 Ti 또는 Ti+Nb 원소 첨가를 변화시킨 409L 계열강에 있어서 소둔조업조건에 따른 재결정과 상변태 거동을 조사하엿으며, TIG용접에 의한 용접부의 기계적 특성과 가공성 그리고 고온부식 및 응축수 부식 시험을 통한 내식성 등의 품질 특성 평가를 조사 서술하였다.