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B. Bagheri,M. Abbasi 대한용접·접합학회 2019 대한용접·접합학회지 Vol.37 No.3
In the current research, friction stir vibration welding (FSVW) process was introduced for welding of Al5083 alloy as a new method to improve mechanical and microstructure characteristics of joining zone. Vibration through a motor was added regularly to weld line during the friction stir welding process. Finite element method (FEM) to verify experimental results in different vibration frequencies used. The results showed that grain size in the weld region reduces as vibration frequency increases. The increasing in straining results in the improvement of dislocation density, and leads to more development of high angle grain boundaries because of dynamic recrystallization. The grain size of base metal is 64 μm, while it is about 17 and 9 μm during FSW and FSVW respectively. Besides, strength, hardness and formability index of FSV welded samples were tremendous than that of FS welded ones. Ultimate tensile strength (UTS) increases from 180 MPa for FSW to 225 MPa as 48 Hz frequency vibration was used. The thrust force curve indicated that the time required to reach the highest thrust level as well as the peak thrust value reduce as the vibration frequency increases. This novel way can enhance the application of FSW, and it has suggested for utilization in various industries.
Microstructures and mechanical properties of friction stir welded dissimilar steel-copper joints
M. Jafari,M. Abbasi,D. Poursina,A. Gheysarian,B. Bagheri 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.3
Welding dissimilar metals by fusion welding is challenging. It results in welding defects. Friction stir welding (FSW) as a solid-state joining method can overcome these problems. In this study, 304L stainless steel was joined to copper by FSW. The optimal values of the welding parameters traverse speed, rotational speed, and tilt angle were obtained through Response surface methodology (RSM). Under optimal welding conditions, the effects of welding pass number on the microstructures and mechanical properties of the welded joints were investigated. Results indicated that appropriate values of FSW parameters could be obtained by RSM and grain size refinement during FSW mainly affected the hardness in the weld regions. Furthermore, the heat from the FSW tool increased the grain size in the Heat-affected zones (HAZs), especially on the copper side. Therefore, the strength and ductility decreased as the welding pass number increased because of grain size enhancement in the HAZs as the welding pass number increased.