Study on fatigue property of laser welded joints of TC4 titanium alloy sheet

The tensile and fatigue properties of TC4 titanium alloy sheet and its laser welded joints were investigated. The results showed that the strength of laser welded joints was increased and the elongation rate was decreased compared with that of base metal. The tensile fracture of laser welded joints was found on base metal. The fatigue life of laser welded joints was higher than that of base metal under low stress levels, nevertheless, the fatigue life of laser welded joints was lower than that of base metal under high stress levels. In fatigue crack expansion zone, base metal was tough transgranular fracture, however, a mixed fracture characteristics of tough and brittle was noted on fractographs of fusion zone. In transient crack zone, the SEM fractographs of base metal consisted of equal-axis ductile voids, the fusion zone mainly consisted of course transgranular cleavage facets.