Amin Abdollahzadeh - PhD student of materials science and engineering, Advanced Materials and Nanotechnology Research Laboratory, Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran
Ali Shokufar - Professor of materials science and engineering, Advanced Materials and Nanotechnology Research Laboratory, Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran
Hamid Omidvar - Associate professor of materials science and engineering, Faculty of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran, Iran
Hamid Haghgooyan - Msc student of materials science and engineering, Faculty of Engineering, Islamic Azad University of Karaj, Karaj, Iran
Mohammad Amini - Msc student of materials science and engineering, Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran

The solid-state nature of the friction stir welding (FSW) process leads to several advantages over fusion welding methods as problems associated with cooling from the liquid phase are avoided. In this study, friction stir welding (FSW) technique was employed for joining AZ۳۱ magnesium plates. Since SiC particles had been injected along the joint line, AZ۳۱/SiC nano-composite was developed in the stir zone (SZ) and the effects of rotational and traveling speeds on grain size, cavities and precipitations of stir zone were investigated. Three rotational speeds ۶۰۰,۸۰۰, ۱۰۰۰ round per minute and four traveling speeds ۲۵, ۷۵, ۱۲۵ and ۱۷۵ millimeter per minute were used for welding of specimens. Microstructural studies showed that increase of traveling and rotational speeds, generally deceased grain size of composites. Also, cavities and Al۳Mn precipitations were identified as main precipitations of composite. Due to apply plastic deformation during FSW, magnesium grains at TMAZ were observed in long shape. Moreover, Al۳Mn precipitations at TMAZ were finer than those at BM.

Friction stir welding, magnesium alloy, SiC nano particles, grain size, precipitations