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Abstract: A calculating method is put forward for predicting the
fracture toughness of SPF/DB interfaces according to the process
parameters, and further, a corresponding interfacial fracture toughness
analysis and prediction software system for TC4/TA2 are developed. For
the calculating method, first, based on the theoretical analyses and
experimental results, the growing model of the diffusion bonded
interfaces is established, then the formula for calculating the
thickness of interface layer is obtained and the calculation for
material transition parameter m is established. Secondly, the modified
general criterion for fracture toughness under mixed-mode loading is
proposed for fitting the functional model of the fracture toughness
curves of the interfaces in the diffusion bonded component. The results
that are computed agree very well with experimental data. The analytical
results show that within the limits permitted of process parameters, the
fracture toughness increases with increase in forming temperature,
forming pressure and in time applied pressure. Among them, the influence
of forming pressure is maximum, the influence of time and temperature
are in proper order. In order to increasing the interfacial fracture
toughness of the components diffusion-bonded, the fracture mode mixture
of the fracture tip in the interfaces must be increased with the
interfacial layer design. The process parameters above mentioned are
just concerned with the fracture mode mixture of the fracture tip
closely.
Key words: Superplastic forming Diffusion bonding Interface layer
Fracture toughness Titanium alloy
CLC No: TG301
高等学校博士学科点专项科研基金资助项目(98069912).
Received 20010918, received in revised form 20011224
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