Preparation, inspection, and optimization of rotary friction welding parameters for 2017aa aluminum alloy specimens

The qualification of the friction stir welding (FSW) process in aerospace requires the production of high-quality joints with a long tool lifespan. This necessitates fine-tuning process parameters such as tool geometry (shoulder and pin dimensions, threading) and feed and rotation speeds. The experimental part involves characterizing the FSW weld joint of the 2017AT451 aluminum alloy through the study of mechanical properties using two thickness specimens and different mechanical parameters varying the tool rotation speed from 950 to 1250 rpm. The results showed that the increase in tool rotation speed leads to significant growth of grains in the Heat-Affected Zone (ZAT) and enhances recrystallization of the near-zone (NZ) microstructure. The analyses and control observations performed on the obtained weld beads have enabled the correlation of joint quality with operational parameters. To achieve this, a local fabrication procedure aimed at producing defect-free joints was devised. Microstructural analysis revealed that the tool's rotation speed influences recrystallization conditions; the higher the rotation speed, the greater the welding energy and the more pronounced the softening of the material in the heat affected zone (HAZ).