Thermal-mechanical fatigue crack growth in B-1900+Hf

Thermal-mechanical fatigue crack growth (TMFCG) rates in B-1900+Hf were measured under strain-controlled conditions in the temperature range 400-925 C. A poor correlation between isothermal and TMFCG rates under elastic and fully plastic conditions was observed when test data were analyzed using a strain-based approach. A stress-based approach taking into account the hardening and softening behavior of the material and load shedding provided an adequate description of the isothermal and TMFCG rates. Also, the isothermal crack growth rates at minimum and maximum temperatures provided upper and lower bounds, respectively, on the TMFCG rates.