723919.fig.006a
(a)
723919.fig.006b
(b)
Figure 6: Surface layer microstructure after the: (a) EDM U = 80 (V), I = 48 (A), Ti = 400 (μs), (b) EDM U = 80 (V), I = 48 (A), Ti= 400 (μs), Tp = 50 (μs) and roto-peen  (rev/min),  (min).