PSI - Issue 14

Ashok Saxena / Procedia Structural Integrity 14 (2019) 774–781

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Ashok Saxena/ Structural Integrity Procedia 00 (2018) 000 – 000

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under a wide range of transient and steady-state conditions is good but not so for creep-brittle materials for which there does not exist a C t type parameter.

Fig. 1- Finite element simulations of creep crack growth under creep-ductile and creep-brittle conditions [Hall, McDowell and Saxena, 1998]. The specimens analysed were C(T) type with a width of 50.8 mm and a starting crack size of 20.3 mm.

Fig. 2- Creep crack growth behaviour of a creep-brittle Al alloy 2519-T87 [Hamilton et al. 1997]. The lack of uniqueness in the correlation between da/dot and K is apparent in data from various specimens that are identical except in the starting crack size and the applied load.

These results clearly indicate that in the case of creep-ductile materials, approaches that are based on good analytical foundation and supported by extensive data are available to predict crack growth at elevated temperatures. ASTM standard method for measuring creep crack growth times in metals, E1457-15 [2015] is limited only to creep