Properties of repair welded joint of 2219 aluminum alloy under two heat-treated state

VP-TIG welded joint of 2219 aluminum alloy with different heat-treated state of CYS and C10S used in launch vehicle tank was repaired,the microstructure and mechanical properties of a repair welded joint was analyzed. The results show that the elongation of welded joint at the low and room temperature decreases with the increase of numbers of repair welding,which has declined to 16. 7% and 24. 6% respectively. During the tensile test,the fracture path of samples both occur in the side of 2219CYS fusion zone,and the grains size of the fusion zone in the side of 2219CYS is markedly larger than that of 2219C10S. The intercrystalline segregation of eutectic phase and growth and coarsening of brittle eutectic phase on boundary caused by welding thermal cycle are the main reason for the decreases of mechanical properties. The growth of grains in FZ and HAZ lead to the decrease of joint elongation.