Analysis of crack in aluminium alloy AA2219 weldment

Aluminium alloy AA2219 is used for fabrication of propellant tanks of launch vehicles. After welding of one of the heat treated plate (T87 temper condition) with a rolled ring (T851 temper condition), crack has been noticed near the weldment. A thorough metallographic analysis was carried out to investigate the cause for development of crack, using optical and scanning electron microscope. Morphology of cracks alongwith the attributable factors are discussed and the remedial measures are suggested.