In situ rolling friction stir welding for joining AA2219

In the present work, in situ rolling friction stir welding (IRFSW) was introduced to join a couple of 3-mm thick AA2219. This IRFSW tool consisted of a stir pin, a shoulder and four rolling balls. The efficacy of rolling tool had been proved to eliminate the weld flashes and improve the mechanical properties. The average tensile strength of optimized joint was increased from 175 MPa to 198 MPa and the average elongation was almost the same compared with conventional FSW joint. The microhardness of different weld zones near the upper surface of IRFSW joint varied significantly and was higher than that of the conventional FSW joint. Especially in the soften zone, the microhardness was improved from 55.3 HV to 66.4 HV and had more than 20% increase. The grain size in RZ was the smallest due to the function of rolling balls which introduced the rolling pressure that had an important effect on the dynamic recrystallization. The typical joint fractured from HAZ adjacent to TMAZ on retreating side. Furthermore, the failure of specimen presented a ductile fracture in the typical joint.