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Ji-Sun Kim,In-Ju Kim,김영곤 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.6
The automotive industry has a target goal to improve fuel consumption due to restricted exhaust gas regulation. For this reason, the applicability of lightweight material, Al alloys, Mg alloys is also being expanded. In this concept, high strength steel, DP590 and light alloy, AL5052 are joined in the right place of the car body. However, it is difficult to join to steel and aluminum by conventional fusion welding. Generally, in respect to dissimilar metal joining by fusion welding, intermetallic compound layer is formed at the joint interface, hot cracking is generated. In this study, the effect of the current waveform on the mechanical characteristics and microstructure in Delta spot welding process of dissimilar metal was investigated. As results, Intermetallic compound (IMC) layer was reduced from 2.355 μm to 1.09 μm by using Delta spot welding process; also the welding current range improved by 50% in the delta spot welding, higher than in the inverter resistance welding. To conclude, the delta spot welding process adopting the process tapes contributes to improving the welding quality for dissimilar metals (Al5052 and DP590) due to a decrease in IMC layer.
Shim, Junghyun,Faridh, Mohd,Yu, Jiyoung,Rhee, Sehun SAGE Publications 2016 Proceedings of the Institution of Mechanical Engin Vol.230 No.5
<P>Resistance spot welding is one of the most commonly used processes for joining-metal the automotive, and electronics industry. When joining a car body, the method of welding dissimilar three sheets, including high strength steel is frequently used. Studies on the dissimilar welding of high strength steel and low carbon steel are being conducted in an attempt to improve the weldability. However, the dissimilar welding of TWIP steel with other steel grades is extremely challenging due to the high resistivity of the base metal. Therefore, further studies are required to improve the weldability of three sheets including the low carbon steel. In general, the resistance spot welding process is conducted in the field by the constant current control method. In this study, the constant power control method was applied in order to reduce the occurrence of expulsion and to improve the weldability of three dissimilar steel sheets consisting of SGACEN, DP steel, and TWIP steel. The constant current control was compared with constant power control, through the evaluation of weldability by using the suitable welding range lobe curve, which takes into account the tensile shear strength, and nugget diameter. Additionally, the current, voltage, resistance, and power signal were also analyzed. The constant power control prevented the occurrence of expulsion as a result of high heat not being generated at the early stage, compared to the constant current control method. Regarding the welding time being long, an increase in heat was applied so that there was a considerable improvement of weldability, compared to the constant current control.</P>
Chantasri, Sakchai,Poonnayom, Pramote,Kaewwichit, Jesada,Roybang, Waraporn,Kimapong, Kittipong The International Promotion Agency of Culture Tech 2015 International Journal of Advanced Culture Technolo Vol.3 No.1
This article is aimed to study the effects of resistance spot welding (RSW) on the lap joint properties between AA1100 aluminum alloy and SGACD zinc coated steel and its properties. The summarized experimental results are as follows. The summarized experimental results are as follows. The optimum welding parameters that produced maximum tensile shear strength of 2200 N was a welding current of 95 kA, a holding time of 10 cycles, and a welding pressure of 0.10 MPa. Increasing of welding current, increased the tensile shear strength of the joint and also increased the amount of aluminum dispersion at the joint interface. The lap joint of steel over the aluminum (Type I) showed the higher joint tensile shear strength than a lap joint of aluminum over the steel (Type II). The indentation depth and the ratio of the indentation depth to the plate thickness decreased when the welding current was increased in the type I lap joint and also decreased when the welding current was decreased in the type II lap joint. The interface structure showed the formation of the brittle $FeAl_3$ intermetallic compound that deteriorated the joint strength.
Sakchai Chantasri,Pramote Poonnayom,Jesada Kaewwichit,Waraporn Roybang,Kittipong Kimapong 국제문화기술진흥원 2015 International Journal of Advanced Culture Technolo Vol.3 No.1
This article is aimed to study the effects of resistance spot welding (RSW) on the lap joint properties between AA1100 aluminum alloy and SGACD zinc coated steel and its properties. The summarized experimental results are as follows. The summarized experimental results are as follows. The optimum welding parameters that produced maximum tensile shear strength of 2200 N was a welding current of 95 kA, a holding time of 10 cycles, and a welding pressure of 0.10 MPa. Increasing of welding current, increased the tensile shear strength of the joint and also increased the amount of aluminum dispersion at the joint interface. The lap joint of steel over the aluminum (Type I) showed the higher joint tensile shear strength than a lap joint of aluminum over the steel (Type II). The indentation depth and the ratio of the indentation depth to the plate thickness decreased when the welding current was increased in the type I lap joint and also decreased when the welding current was decreased in the type II lap joint. The interface structure showed the formation of the brittle FeAl3 intermetallic compound that deteriorated the joint strength.
저항 점 용접을 이용한 AISI 316 스테인레스강과 용융아연도금 강판의 이종접합
이진범,남대근,강남현,김양도,오원태,박영도,Lee, Jin-Bum,Nam, Dae-Geun,Kang, Nam-Hyun,Kim, Yang-Do,Oh, Weon-Tae,Park, Yeong-Do 한국재료학회 2009 한국재료학회지 Vol.19 No.7
The spot weldability of dissimilar metal joints between stainless steels (AISI316) and interstitial free (IF) steels were investigated. This study was aimed to determine the spot welding parameters for a dissimilar metal joint and to evaluate the dissimilar metal joint's weldability, including its welding nugget shape, tensileshear strength, hardness, and microstructure. The fracture surface was investigated by using a Scanning Electron Microscopy (SEM). The experimental results showed that the shape of nugget was asymmetric, in which the fusion zone of the STS316 sheet was larger due to the higher bulk-resistance. The microstructure of the fusion zone was fully martensite. In order to evaluate the microstructure further, dilution of stainless steels were calculated and imposed onto the Schaeffler diagram. The predicted microstructure from the Schaeffler diagram was martensite. In order to confirm the predicted microstructure, XRD measurements were carried out. The results showed that that initial weld nugget was composed of austenite and martensite.
하지웅(Jiwoong Ha),허훈(Hoon Huh),임승찬(Seung-Chan Lim),이홍우(Hongwoo Lee),남재복(Jae-Bok Nam) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
This paper is concerned with the failure characteristics and the failure criterion of spot welds of a dissimilar AHSS combination under combined axial and shear loading conditions. In order to keep the constant ratio of the axial load to the shear load acting on the spot weld during the failure test, the testing fixture and the specimen proposed by Song et al. for a loading angle ranging from 0° to 75° and the newly designed fixture and specimen for loading angle of 90° are used for the failure tests to obtain failure loads and to identify the failure behavior of spot weld of a dissimilar AHSS combination. The newly designed fixture and specimen can obtain more correct failure loads as preventing rotation of spot welds during the failure tests at a loading angle of 90°. The failure loads of spot welds were investigated with experiments for the spot weld of DP780 1.2t and DP980 1.2t steel sheet combination. The failure loads obtained at various loading angles are utilized to construct the failure criterion proposed Song and Huh for description of failure behavior of spot welds in the crash analysis or the strength analysis of an auto-body.
Optimization of RSW process parameters on tensile strength by taguchi method
S. Raja,K. Vignesh,M. Ravikumar,R. Sanjeevi 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.1
The aim of this research is to improve the Resistance Spot Welding (RSW) process characteristics of AISI SS316L joints ontensile shear load (TSL). The RSW process parameters like electrode diameter of 6mm to 8mm, welding current of 7 kA to9 kA, heating cycle periods of 7 to 9 are selected. The 2 mm sheet thickness has been selected for the welding trials and tensileshear test has been involved for all the trials for the purpose of identifying the TSL. Taguchi optimization technique is usedfor design the experiment with the help of Minitab software. It is observed that maximum TSL of 16 kN is observed by settingthe parameters at 6mm electrode diameter, 9 kA welding current and heating cycles of 9. The ANOVA table confirms thatwelding current majorly affects the quality of weld and all the trials are observed with interfacial failure.
오영현,류현정,김태정,최민수,이태선 대한금속·재료학회 2019 대한금속·재료학회지 Vol.57 No.11
Resistance Element Welding (REW) is a novel processing technology developed to join dissimilar materials such as aluminum and steel. It uses an auxiliary steel rivet (element) inserted into an aluminum sheet that forms a resistance spot weld with the steel sheet, and the aluminum work piece is mechanically joined by the interlocking rivet. The versatility and agility of REW is advantageous, especially in the automotive industry. However, the head of the rivet often extends out externally over the work piece, and the misalignment of the electrode with the head can be problematic since inserting the head and the weld are performed in separate stages. In the present paper, we performed REW using a headless rivet which has minimal to no overhanging part above the aluminum surface. The lap-shear strength of REW is higher than self-piercing rivets, which makes REW a promising solution for extending applications of multi-material structures. The microstructure of the joint involves a fusion zone which mainly consists of martensite, and the failure occurs near the heat affected zone. This study finds that the electrode-rivet alignment needs to be optimized to manage the optimal nugget size and to avoid current arcing through the aluminum work piece.