An analytical study on cracking directions and damage in thermal fatigue crazing subjected to variable amplitude loadings

• Published in: Journal of materials science Vol. 49; no. 16; pp. 5546 - 5563
• Main Authors: Lei, Bai-Mao, Tran, Van-Xuan, Taheri, Saïd, Wan, Li, Zhou, Yu
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.08.2014; Springer; Springer Nature B.V
• Subjects: Amplitudes; Axial stress; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Crack initiation; Crack propagation; Crazing; Crystallography and Scattering Methods; Damage; Electric power-plants; Exact solutions; Fatigue; Fatigue cracking; Fatigue failure; Fatigue testing machines; Fracture mechanics; Materials; Materials Science; Mathematical analysis; Mathematical models; Nuclear energy; Nuclear power plants; Orientation; Planes; Polymer Sciences; Power plants; Residual stress; Shipments data; Solid Mechanics; Stresses; Thermal fatigue; Thermal stress; Variation; Stress Amplitude; Pipe Wall; 304L Stainless Steel; Critical Angle; Weld Residual Stress
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-014-8249-5

In this paper, the effects of biaxial mean stress, mainly contributed by the weld residual stress, and thermal loading conditions on cracking directions and damage in high cycle thermal fatigue crazing subjected to variable amplitude loadings are investigated by a combined analytical and computational approach. The cracking directions are related to the orientation of the critical plane defined by the maximum damage. Analytical solutions of the critical plane orientation under constant amplitude biaxial tension/compression loadings are first derived and then employed to study the effects of biaxial mean stress on the critical plane orientation. The critical plane orientation appears to strongly depend on the dominant direction defined by the larger maximum stress. The developed analytical solution of the critical plane orientation and the analytical solution of the thermal stress from the literature are employed to study the effects of thermal loading conditions on the critical plane orientation. The critical plane orientation does not seem to significantly depend on the frequency, the amplitude and the mean value of the fluid temperature fluctuations, and the heat transfer film coefficient between the fluid and the pipe wall. The critical plane orientation under variable amplitude loadings is also studied, and an approximate solution is proposed for convenient engineering applications. The critical plane orientations are used to partially explain the observed cracking directions in the high cycle thermal fatigue crazing in the old residual heat removal system of a nuclear power plant. Finally, the effects of biaxial mean stress and thermal loading conditions on the fatigue crack initiation life are discussed.