Abstract
Creep damage is one of the main failure mechanisms of high Cr heat-resistant steel in power plants. Due to the complex changes of stress, strain, and damage at the tip of a creep crack with time, it is difficult to accurately evaluate the effects of residual stress on the creep rupture mechanism. In this study, two levels of residual stress were introduced in P92 high Cr alloy specimens using the local out-of-plane compression approach. The specimens were then subjected to thermal exposure at the temperature of 650 °C for accelerated creep tests. The chemical composition of P92 specimens was obtained using an FLS980-stm Edinburgh fluorescence spectrometer. Then, the constitutive coupling relation between the temperature and material intrinsic flow stress was established based on the Gibbs free energy principle. The effects of prior residual stress on the creep rupture mechanism were investigated by the finite element method (FEM) and experimental method. A comparison of the experimental and simulated results demonstrates that the effect of prior residual stress on the propagation of micro-cracks and the creep rupture time is significant. In sum, the transgranular fracture and the intergranular fracture can be observed in micrographs when the value of prior residual stress exceeds and is less than the material intrinsic flow stress, respectively.
Highlights
Creep deformation and failure in high-temperature structures are serious problems in industry and are becoming even more serious under the current increasing pressures of energy, economics, and sustainability [1,2,3]
This study has investigated the effect of prior residual stress on the creep rupture mechanism for P92 steel
The different prior residual stress levels were introduced into the P92 specimens, were are subjected to thermal exposure at the temperature of 650 ◦ C for accelerated creep tests
Summary
Creep deformation and failure in high-temperature structures are serious problems in industry and are becoming even more serious under the current increasing pressures of energy, economics, and sustainability [1,2,3]. P92 high Cr alloy steels are widely used as high-temperature construction materials in power plants due to their high creep strength, good molding property to be processed, and superior heat properties [4,5]. Such components employed in power plants are continually exposed to high temperatures and high steam pressures, and creep crack growth could occur within these high-temperature regimes, causing the failure of these components [6]. It is essential to investigate the influences of residual stress on the creep rupture mechanism for high Cr alloy steel
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