Investigation of internal cracks in aluminium alloy AA7075 forging

AA7075 aluminium alloy is a high strength age hard enable alloy. Although this alloy is not weldable, critical components fabricated out of this alloy have aerospace applications in the form of forgings in T7352 temper condition. In the case under investigation extruded billet was used as input material, and during ultrasonic testing of the forgings, distinct discontinuities were observed. An exhaustive metallographic investigation was taken up in tandem with progressive machining to physically observe the cracks. Morphology and locations of cracks along with the attributable factors were discussed and the remedial measures were suggested.