Microstructural Evaluation and Welding Reliability of Friction Stir Welding Al and Cu Dissimilar Metals

• Main Authors: Shiau-Jiun Jiang, 江曉均
• Other Authors: Chung-Wei Yang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/rksqs9

碩士 === 國立虎尾科技大學 === 材料科學與綠色能源工程研究所 === 102 === Wrought aluminum (Al) and Cu alloys are generally used by welding with structural homogeneous or dissimilar joints for the engineering applications. However, high temperature of the traditional fusion welding will reduce the weldability and the joining strength of Al/Cu joints. Thus, the development of friction stir welding (FSW) of dissimilar metals, which has energy consumption, eco-friendly and simple welding process, has been focused by many researchers. The aim of the present study is to join the dissimilar Al and Cu alloys by the FSW technique. The AA1050, AA6061-T6 rolled Al alloys, commercial C1100 and C2600 Cu alloys are selected to conduct a friction stir welding of the Al/Cu dissimilar joints, microstructural analysis and microhardness variation of the stir welding zone, and tensile bonding tests for Al/Cu, dissimilar joints. The results indicate that dissimilar AA1050/C1100, AA6061-T6/C1100 and AA1050/C2600 alloys are successfully joined by the FSW technique. The microstructural observation along WD cross-sections showed that the above-mentioned FSW dissimilar alloys are welded with a defect-free welding zone by the significant plastic flow. The microhardness is increased after the welding. In addition, intermetallic compounds (IMCs) of Cu9Al4 and AlCu2 are found at FSW Al/Cu joint interface. Tensile testing results of these dissimilar joints show that the tensile welding strength of AA1050/C1100, AA6061-T6/C1100 and AA1050/C2600 alloys are 107.73, 212.2, and 54.17 MPa, respectively. The Weibull statistical analysis results show that the fracture of the above-mentioned FSW Al/Cu dissimilar joints belongs to an increasing failure rate (IFR) type. The FSW technique is a reliable joining process to weld the Al and Cu dissimilar alloys.