Influence of pin size on welding shape and mechanical properties of friction stir welded 2014 Al alloy
(1.黑龙江省哈尔滨市哈尔滨工业大学现代焊接生产技术国家重点实验室2.State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001, China)
Abstract: The influence of pin size on microstructure and mechanical properties of friction stir welded 2014 Al alloy was investigated. Three different size stir pins were used to carry out the welding process. The results show that the size of the pin has a significant effects on the joint structure and mechanical properties. For one given thickness material, excellent weld can be achieved by using a appropriate size friction stir tool. The appearance of the weld is good and no obvious defect is found using this tool. The grain of the weld nugget is very fine and the precipitation distributes equably. The weld structure can change smoothly from the weld nugget to the thermo-mechanic affected zone. The tensile strength is high enough and the synthesis mechanical properties of the weld are very good. When welded by an improper size pin, some defects such as voids and crack often occur in the weld, and which strongly affect the mechanical properties of the weld.
Key words: 2014 Al alloy； friction stir pin； friction stir welding； shape； mechanical property