Prediction of creep crack growth behavior in Cr–Mo–V steel specimens with different constraints for a wide range of C∗

• Stress dependent creep ductility trends are implemented in a creep damage model.
• Creep crack growth rates in specimens with different constraints are predicted.
• The creep crack growth rate increases with increasing specimen constraint.
• Constraint effects arise from the interaction of stress state and creep ductility.
• Constraint dependent creep crack growth rate data should be obtained and used.

The stress dependent creep ductility and strain rate model were implemented in a ductility exhaustion based damage model, and the creep crack growth rates in Cr–Mo–V steel specimens with different constraints over a wide range of C∗-integral have been predicted by finite element analyses. The predicted creep crack growth rates agree well with the existing experimental data. The creep crack growth rate increases with increasing specimen constraint, and the specimen constraint has effect on the C∗-integral values of the slope turning points on the crack growth rate curves. The mechanical mechanism of specimen constraint effects on creep crack growth behavior was analyzed and discussed. The results show that the constraint effects on the creep crack growth behavior for a wide range of C∗-integral mainly arise from interaction of crack-tip stress states and stress dependent creep ductility of the steel. The constraint dependent creep crack growth rate data in a wide range of C∗-integral should be obtained and used in creep life assessments of components.