Influence of Grain Boundary on the Fatigue Crack Growth of 7050-T7451 Aluminum Alloy Based on Small Time Scale Method

Figure 6

In the unloading stage of 99 cycles, micromorphology of fatigue crack at different loading level: (a) at 1380 N, (b) at 960 N, (c) at 750 N, and (d) at 540 N.

(a)

(b)

(c)

(d)