Abstract:
To investigate the crack growth characteristics of diffusion bonded (DB) laminates of TC4 titanium alloy with ϕ6 centered hole, the reduplicated fatigue tests for 8mm thick TC4 plate, three-layer DB laminates and three-layer DB laminates with localized ϕ12 no-welded area were conducted under the constant amplitude fatigue stress inserted periodically with marker load. The crack growth (
a,
N) data were obtained by quantitative fractography. The analysis on the failure surface shows that the typical semi-elliptic surface crack are found for the 8mm plate; the untypical semi-elliptic surface crack for the 3-layer DB laminate; the corner quarter-elliptic crack for the localized no-welded DB laminate whose crack growth could be divided to three phase. The comparison on the d
a/d
N-
a curves of those coupons shows that the crack growth characteristic of the DB laminate has no difference with the 8mm thick plate, while the localized ϕ12 no-welded area decreases the crack growth rate and improves the damage tolerance property of the DB laminate.