Load-independent creep constraint parameter and its application

A load-independent creep constraint parameter R* was proposed, and its load-independence was validated using finite element results in previous studies. A fixed distance r = 0.2 mm from a crack tip is chosen to define the R, and the R* at steady-state creep can be used to evaluate constraint level with little conservatism for whole creep time. The R can be used for ranking constraint levels for different specimens or components, and for predicting constraint-dependent creep crack growth rates. The constraint-dependent creep crack growth rate equations of a Cr-Mo-V steel have been obtained, and it may be used in creep life assessments. (C) 2013 Elsevier Ltd. All rights reserved.