9 Comparative Study of Laser Weldability of Titanium Alloys
307
Fig. 9.6 Metallographic images of the different zones of Ti 6 Al 4 V butt weld, at the indicated
magnifications
suppressed by the excess of stabilizers of phase β, since the concentration of molybdenum equivalent ([Mo]eq) is approximately 12. Bania [15] affirm that martensite
α´ does not precipitate if [Mo]eq is greater than 10. In addition, the low hardness
observed in both the FZ and the HAZ may be due to the formation of the α phase
in the HAZ and the presence of metastable/retained β phase in the FZ [16]. In any
case, it seems that the heat treatment related by the laser welding process provokes
the loss of the previous precipitation hardening process at the Ti 5 Al 5 V 5 Mo 3 Cr alloy.
Additionally, the tensile strength of these laser welds has been evaluated. Tensile
tests were performed to unwelded base metal standard specimens for the three alloys
307
Fig. 9.6 Metallographic images of the different zones of Ti 6 Al 4 V butt weld, at the indicated
magnifications
suppressed by the excess of stabilizers of phase β, since the concentration of molybdenum equivalent ([Mo]eq) is approximately 12. Bania [15] affirm that martensite
α´ does not precipitate if [Mo]eq is greater than 10. In addition, the low hardness
observed in both the FZ and the HAZ may be due to the formation of the α phase
in the HAZ and the presence of metastable/retained β phase in the FZ [16]. In any
case, it seems that the heat treatment related by the laser welding process provokes
the loss of the previous precipitation hardening process at the Ti 5 Al 5 V 5 Mo 3 Cr alloy.
Additionally, the tensile strength of these laser welds has been evaluated. Tensile
tests were performed to unwelded base metal standard specimens for the three alloys