(a)

(b)

(c)

(d)

(e)

Figure 5: Macrographs of the weld seams obtained using different laser power of CO2 laser (fixed welding parameter: υ = 4 m/min). (a) 6.8 KW, (b) 7.2 KW, (c) 7.5 KW, (d) 7.8 KW, and (e) 8.0 KW.