Estimation of creep fracture life for Hastelloy XR by Q parameter

A Q* parameter was applied to an estimation of the creep crack growth rate for Hastelloy XR under creep conditions at very high temperatures. Creep fracture times were evaluated and examined with the parameter derived by integrating the creep crack growth rate formula expressed in terms of the Q* parameter for notched and smooth specimens. The Q* parameter could characterize creep crack growth rate successfully including the early stage of crack propagation. It is shown that the parameter (T(log sub 10 t sub f +20)x10 exp )3 ) derived from the Q* parameter can compare and estimate the difference in geometry of specimen, ductility of material and so on, using the identical parameter and this parameter is of engineering value.