1. State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University Xi'an Shaanxi 710072 P. R. China
2. Aeronautical Key Laboratory for Welding and Joining Technologies AVIC Manufacturing Technology Institute Beijing 100024 P. R. China
3. Center for Process R&D Xi'an Aero-engine Ltd. Xi'an Shaanxi 710021 P. R. China