Abstract
n value of Al-Mg alloys is not constant with strain, since it increases to a maximum and decreases. The changes of n value and microstructures during tensile deformation suggest as follows. When n value increases with strain, dislocation density increases. When n value is stable with strain, microstructures change little. When n value decreases with strain, the formation and growth of dislocation cell structures occur and cause to dynamic recovery. The stability of n value is more important than the maximum n value to obtain good formability. The alloys having stable n value with wider strain region are considered as materials with better formability.
