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조상명 釜慶大學校 1998 釜慶大學校 論文集 Vol.3 No.2
Precision resistance spot welding was applied to two kinds of thin stainless steel (STS304) strips to be soft and hard. The hard STS304 was produced by cold working. and the soft STS304 was obtained by solid solution treatment in the present experiment. Thickness of the specimens was 0.2mm. The welding load was varied by 1∼ 18kgf,the range of wdlding current was 500∼1500A. In the welding process, the splash from weldment was ovserved carefully. The welded specimen with lap joint was tested by the tensile shear test. And the nugget of the weldment was investigated by macro-section macro-section ovservation and micro-vickers hardness test. When the welding load was low, the good condition with stable quality and no splash could not be obtained. Therefore, to suppress the splash from the weldment, sufficient welding load and adequate currentwas needed. This approach method was developed for the hard and soft thin STS304 strips. The nugget and heat affected zone in the weldment by the hard STS304 was softened remarkably �� 새 rapid heating and cooling by the welding process. However for the soft STS304, the hardness of the weldment was not changed, but almost uniform. Because of this mechanism, the weldment by the hard STS304 was failed by the plug fracture mostly when welding current had been adative or high. But for the weldment by the soft STS304, the tear fracture was appeared mainly in the same range of current.
조상명 대한용접접합학회 1997 대한용접·접합학회지 Vol.15 No.2
본 보에서는 저항용접시의 발열원리와 너깃의 생성과정 등에 대하여 해설하고, 점용접의 3대 요소와 그에 대한 모니터링 결과를 분석하여 간단한 불량 대책에 관하여 기술하였다.
응력집중의 영향을 고려한 알루미늄합금 A5083-O의 피로균열전파 특성 예측모델
조상명,김종호,김영식 대한용접접합학회 1994 대한용접·접합학회지 Vol.12 No.3
In this study the fatigue crack growth behavior was investigated for the surface cracks in aluminum alloy A5083-O plate and its weldment. Several kinds of specimens were tested at room temperature. The Eccentric specimens(E1.0, E2.5) subjected to combined stresses(tension+bending) were tested and the welded specimens with weld toes(TOE1, TOE2) were tested in order to verify the method to consider the stress concentration such as weld toe. It was ascertained that the surface crack growth property in the weld toe could be predicted by the corrected Pang's equation proposed in this study.
아연도금강판에 대한 중첩펄스 MIG 용접에서의 파형제어와 기공 발생 특성
조상명,김기정,이병우,Cho Sang-Myung,Kim Ki-Jung,Lee Byung-Woo 대한용접접합학회 2005 대한용접·접합학회지 Vol.23 No.1
Recently, application of arc welding to galvanized carbon steel sheet is on the increasing Ould in the fields of automobile and construction industries. In arc welding process, zinc is evaporated in weld pool, even under the appropriate welding condition and produce blowhole and/or pit. Zinc gas cause instability of arc and increase spatter and fume. This research is purposed to minimize the heat-input and the formation of porosities in the welded joint of the galvanized carbon steel sheet using variable polarity AC wave pulse MIG welding system. An appropriate welding condition which showed low spatter and good bead appearance was acquired by applying the AC pulse MIG welding machine to DC duplicated MIG welding with the solid wire. When oxygen gas was added to shield gas of MIG welding for galvanized steel sheet, arc length was increased and arc stability was improved. In the AC duplicated welding, the loss of galvanized layer was decreased as the amount of heat-input was decreased when the EN ratio was increased under the condition that average welding current was evenly set.
내마모판의 광폭 경화육성 용접비드 형성을 위한 트윈토치 CMAW 공정개발
조상명,김성덕,황규민,Cho, Sang-Myung,Kim, Sung-Deok,Hwang, Kyu-Min 대한용접접합학회 2008 대한용접·접합학회지 Vol.26 No.2
The wearplate with Cr-C has been used in condition of severe abrasion. Recently, the demand of wearplate made by hardfacing with Cr-C has increased in the world, but it is lack of supply and expensive due to low productivity. CMAW (Compound Metal Arc Welding) is very useful process of several welding methods to make wearplate. In this paper, twin torch CMAW to use twin torch at the same time was developed to improve productivity and to ensure quality of wear plate. When the distance between two touches was smaller than 30mm, arc blow was occurred. However when the distance was larger than 35mm, there was no arc blow any more. If the oscillation path of each torch was overlapped together, the melt through at the overlapped zone was occurred due to concentrated heat input in substrate. On the other hand, the turning point of each torch was open more than 5mm, separated bead was generated. Therefore twin torch CMAW which has adequate conditions was able to make wearplate having flatter surface at the bead connection than single torch.
$CO_2$용접의 스패터 발생에 미치는 단락시간비 및 단락전류 파형제어의 영향
조상명 대한용접접합학회 2003 대한용접·접합학회지 Vol.21 No.1
The object of this study is to examine the effect of short circuit time ratio (SCTR) and current rise delay time (Td) on the spatter generation at low and medium current range in $CO_2$ welding. The spatter was evaluated by the weight generated in the welding of bead-on-plate for 30 seconds (3 times). Td was varied by order of 0, 0.4, 0.8 and 1.2 msec. At each Td, the short circuit time ratio was varied by the output voltage of the welding power source. In the low current range, it was found that the optimum SCTR was 20~25%, and the minimum spatter generation weight was obtained in the case of Td=0.4msec and SCTR=22% even though the remarkable difference was not showed by the application of Td. In the medium current range, it was confirmed that the arc was stable though the SCTR was increased from 20% to 40% by the control of current wave. Spatter generation weight depended on the variation of Td, and the lowest value of spatter generation weight occurred at Td=0.8~1.2msec.