Design of Joint Properties by Friction Powder Processing

摘要

Friction powder processing (FPP) has been developed based on the principle of friction stir welding (FSW) or friction stir processing (FSP). The FPP is a method to design the properties of the processed area by performing FSP after powder with a controlled composition is placed in the gap between two plates. The FPP experiments were performed using a tool with the shoulder diameter of 15mm and the probe diameter of 6mm. The tool traveled at 100mm/min and rotated at 1500rpm. A1050 aluminum was used as the plate. Pure Al powder (89μm average grain diameter) and pure Cu powder (106μm average grain diameter) were used as the additives. When using pure Al powder, the pure Al powder left in the base metal after the first pass is sufficiently stirred by performing the second pass and then a good joint without defects is obtained. However, more than three passes are not effective for improving the strength of the welded area. When using pure Cu powder, nanoscale Al_2Cu precipitates are uniformly formed in the stir zone, and accordingly, the hardness is significantly increased.