Development of a Castable, Free-Machining Titanium Alloy
The addition of La to cp-Ti or Ti alloys, like Ti 6Al 4V, leads to the formation of short-breaking chips. Free-machinability is given by elementary La particles in the Ti matrix. The new alloy Ti 6Al 2Fe 1Mo 0.9La 0.5Cu was developed out of the Ti 6Al 4V alloy and exhibits free-machinability. However, this alloy offers poor castability due to the formation of hot cracks. Thermocalc® simulations discovered that Fe and Cu are broadening the solidification interval of the new alloy, which favors the formation of hot cracks. Therefore, the suitability of other β-stabilizing, like Mn and Cr alloying elements was investigated.
Hajo Dieringa, Norbert Hort and Karl Ulrich Kainer
J. Laukart et al., "Development of a Castable, Free-Machining Titanium Alloy", Materials Science Forum, Vol. 690, pp. 3-6, 2011