• Proceedings of the KWS Conference
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• 1993.10a
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• pp.61-63
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• 1993

• Proceedings of the KWS Conference
• /
• 1993.10a
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• pp.119-121
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• 1993

• Proceedings of the KWS Conference
• /
• 1992.10a
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• pp.196-198
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• 1992

• Proceedings of the KWS Conference
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• 2001.10a
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• pp.60-61
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• 2001

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.1
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• pp.49-59
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• 1984

Optimizing investigation of characteristics of underwater welding by a gravity type arc welding process was experimentally carried out by using six types of domestic coated welding electrodes for welding of domestic marine structural steel plates (KR Grade A-1, SWS41A, SWS41B,) in order to develop the underwater welding techniques in practical use. Main results obtained are summarized as follows: 1. The absorption speed of the coating of domestic coated lime titania type welding-electrode became constant at about 60 minutes in water and it was about 0.18%/min during initial 8 minutes of absorption time. 2. Thus, the immediate welding electrode could be used in underwater welding for such a short time in comparison with the joint strength of in-atmosphere-and on-water-welding by dry-, wet-or immediate-welding-electrode. 3. By bead appearance and X-ray inspection, ilmenite, limetitania and high titanium oxide types of electrodes were found better for underwater-welding of 10 mm KR Grade A-1 steel plates, while proper welding angle, current and electrode diameter were 6$0^{\circ}C$, above 160A and 4mm respectively under 28cm/min of welding speed. 4. The weld metal tensile strength or proof stress of underwater-welded-joints has a quadratic relationship with the heat input, and the optimal heat input zone is about 13 to 15KJ/cm for 10mm SWS41A steel plates, resulting from consideration upon both joint efficiency of above-100% and recovery of impact strength and strain. Meanwhile, the optimal heat input zone resulting from tension-tension fatigue limit above the base metal's of SWS41A plates is 16 to 19KJ/cm. Reliability of all the empirical equations reveals 95% confidence level. 6. The microstructure of the underwater welds of SES41A welded in such a zone has no weld defects such as hydrogen brittleness with supreme high hardness, since the HAZ-bond boundary area adjacent to both surface and base metal has only Hv400 max with the microstructure of fine martensite, bainite, pearlite and small amount of ferrite.

• Journal of Welding and Joining
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• v.14 no.5
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• pp.40-48
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• 1996

• Proceedings of the KWS Conference
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• 2000.04a
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• pp.267-271
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• 2000

• NEWSLETTER 전기공업
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• no.97-20 s.189
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• pp.27-39
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• 1997

• NEWSLETTER 전기공업
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• no.96-8 s.153
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• pp.14-51
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• 1996

• Journal of Welding and Joining
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• v.12 no.3
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• pp.1-17
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• 1994