This work aims to collect tool life data, to study the effect of tool geometry on the machinability of Duplex Stainless Steels and to identify suitable tool geometries for continuous cutting operations. Some experimental tests were carried out in continuous cutting operations; in particular, both turning and drilling tools were tested on DIN X2 CrNiMoN 22 5.

Several performance indexes were taken into account: tool life, built-up edge formation, type of chip etc.. As far as turning tests are involved, sintered carbides tips were tested. Five different tool types were investigated to point out the effect of coatings, tool grades, cutting angles and edge finishing (honing).

Cobalt-alloyed High Speed Steel tools were used for drilling tests; two different tool diameters were taken into account. The effect of cutting speed on tool life was studied in both operations; the r-exponent in Taylor's law was evaluated and its value proved to be unexpectedly high. In other words, tool life in cutting Duplex Stainless steels is less affected by cutting speed than when cutting other classes of steels, at least within the range of speeds investigated (as suggested by the tool maker).

The behaviour above mentioned could be exploited to improve tool performances in machining of Duplex Stainless Steels when specific cutting parameters are pointed out.