978031.fig.001a
(a)
978031.fig.001b
(b)
978031.fig.001c
(c)
978031.fig.001d
(d)
978031.fig.001e
(e)
978031.fig.001f
(f)
Figure 1: Microstructure of the NZ for (a) base metal and for rotation speeds of (b) 400, (c) 600, (d) 900, (e) 1200, and (f) 1500 rpm.