216 B. El Aoud et al. Fig. 26.2 SEM micrographs of laser cut kerf surfaces at laser power Pu=2 kW, the cutting speed V =2400 mm/min and the gas pressure p=2 bars: (a) Titanium alloy Ti-6Al-4 V alloy, (b) pure Titanium Ti Fig. 26.3 Kerf width size variation with the laser cutting speed for Ti-6Al-4V and pure Titanium Ti at Pu=2kWand p =2 bars Fig. 26.4 Kerf width size variation with the laser power for Ti-6Al-4V and pure Titanium Ti at V =1440 mm/min and p=2bars It should be noted that high temperature exothermic reactions results in excessive energy generation contributing to the laser beam energy in the cutting section [16]. This causes deep striation patterns at the surface [17]. Figures 26.3 and 26.4 show the effect of two output laser parameters; cutting speed (V) and Laser power (Pu) on the kerf width variation for two different materials; Titanium alloy (Ti-6Al-4V) and pure Titanium (Ti). It is evident from Fig. 26.3 that the kerf width size decreases as the cutting speed increases. This is associated with the formation of large molten layer due to the excessive energy provided via ectothermic reactions in the cut section. In fact, when using slow cutting speed more heat would be introduced to the specimen and then more materials will be melted and ejected causing the kerf to increase.
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