Abstract:A 1420 aluminum-lithium alloy forging used in a key project cracked when it was deposited in quarry.
In this paper, fraction analysis, metallographic analysis and mechanical property analysis were employed to investigate
the reason why cracking phenomenon happened. The results indicated that the cracking problem was delayed
cracking. Local stress concentration appeared in the R area, where micro-surface cracking formed at the phase of water-
cooling. In the process of the long-time storage, the surface of the forging was corroded, resulting in stress occurred.
Under the gradual action of residual stress and stress corrosion, micro-crack enlarged to be perforated crack,
which resulted in the cracking of the forging. Fortunately, such defect could be prevented by cutting the forging’s internal/
external surface away and then detected with fluoroscopy.
