Abstract:
A computational method is proposed for predicting residual stress relaxation during high-temperature creep following prior surface plastic deformation of solid cylinders with square and V-shaped notches. A series of parametric simulations was performed for cylindrical specimens made of EI698 alloy ($20$ mm length, $3.76$ mm radius) with various notch geometries: depths of $\{0.1; 0.3\}$ mm for square notches, and depths of $\{0.1; 0.3\}$ mm with opening angles of $\{1^\circ, 5^\circ, 15^\circ\}$ for V-notches. The study demonstrates that residual stress field calculations after notching a strengthened cylindrical specimen require an elastoplastic formulation. The steady-state creep law was employed to simulate residual stress relaxation at $700^\circ$C over $100$ hours. A parametric analysis of notch geometry effects on stress relaxation was conducted. Results indicate that after the complete loading cycle "hardening treatment at $20^\circ$C — thermal loading (heating) to $700^\circ$C — $100$-hour creep at $700^\circ$C — thermal unloading (cooling) to $20^\circ$C", despite relaxation, significant compressive residual stresses remain. This confirms the effectiveness of surface plastic strengthening for components with the investigated notch types under high-temperature creep conditions.
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