Creep crack growth(CCG)of high temperature welded components can affect the reliability of welded structures containing defects.For P92 steel welded joints,two sets of material configurations of the HAZ center crack and HAZ/BM crack model are designed,and the influence mechanism of creep properties mismatch on crack tip constraint QM*and CCG are studied.The result show that in terms of the HAZ center cracks,secondary cracks may occur if the surrounding creep soft material is constrained by the creep hard material at the crack tip;increasing the creep strength of WM still cause the more severe creep damage of BM if the creep strength of HAZ and BM remain unchanged.For HAZ interface cracks,secondary crack may form if the creep soft material at the interface is constrained by the creep hard material,but the tendency to form secondary cracks is weaker.Whether a central HAZ crack or an interfacial crack,a narrower HAZ width presented a stronger mismatch effect.The CCG prediction method based on C*-QM*for creep properties mismatched welded joints is established,and the accuracy of CCG prediction method incorporating constraint effect is verified by the experiment results.This method can solve the accurate prediction for the CCG rate of welded components with different creep properties mismatch degrees.
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