Cyclic crack resistance of linear friction welded Ti-6Al-4V alloy joints

Kinetic diagrams of the fatigue crack growth rate of Ti-6Al-4V with various structures, namely lamellar, globular, bimodal and its linear friction welds, are presented. The lamellar structure showed a better crack growth resistance than the globular and bimodal structures. Cyclic crack growth resistance of linear friction weld is comparable to that of Ti6Al-4V titanium alloy with lamellar structure. For an alloy with fine-grained globular and bimodal structures for stress intensity < (15-20) MPa m^0.5, the fatigue crack growth rate in linear friction weld is less than in base metal and for stress intensity > (15-20) MPa m^0.5 crack growth rate in linear friction weld is close to the crack growth rate in base metal.