Modified θ projection model-based constant-stress creep curve for alloy 690 steam generator tube material
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초록
Steam generator (SG) tubes in a nuclear power plant can undergo rapid changes in pressure and temperatureduring an accident; thus, an accurate model to predict short-term creep damage is essential. The theta (q) projection method has been widely used for modeling creep-strain behavior under constantstress. However, many creep test data are obtained under constant load, so creep rupture behavior undera constant load cannot be accurately simulated due to the different stress conditions. This paper proposesa novel methodology to obtain the creep curve under constant stress using a modified q projectionmethod that considers the increase in true stress during creep deformation in a constant-load creep test. The methodology is validated using finite element analysis, and the limitations of the methodology arealso discussed. The paper also proposes a creep-strain model for alloy 690 as an SG material and a novelcreep hardening rule we call the damage-fraction hardening rule. The creep hardening rule is applied toevaluate the creep rupture behavior of SG tubes. The results of this study show its great potential toevaluate the rupture behavior of an SG tube governed by creep deformation.
Abstract
Steam generator (SG) tubes in a nuclear power plant can undergo rapid changes in pressure and temperatureduring an accident; thus, an accurate model to predict short-term creep damage is essential. The theta (q) projection method has been widely used for modeling creep-strain behavior under constantstress. However, many creep test data are obtained under constant load, so creep rupture behavior undera constant load cannot be accurately simulated due to the different stress conditions. This paper proposesa novel methodology to obtain the creep curve under constant stress using a modified q projectionmethod that considers the increase in true stress during creep deformation in a constant-load creep test. The methodology is validated using finite element analysis, and the limitations of the methodology arealso discussed. The paper also proposes a creep-strain model for alloy 690 as an SG material and a novelcreep hardening rule we call the damage-fraction hardening rule. The creep hardening rule is applied toevaluate the creep rupture behavior of SG tubes. The results of this study show its great potential toevaluate the rupture behavior of an SG tube governed by creep deformation.
참고문헌 (27)
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