Kinetics of residual stresses in thin-walled cylindrical specimens after bilateral surface hardening under creep conditions with rigid constraints on angular and axial linear displacements

A method for solving the problem of relaxing residual stresses after bilateral surface hardening of a hollow cylinder under creep conditions with rigid constraints on the initially specified axial deformation and twist angle is presented. The solution is developed for complex loading regimes including pure thermal exposure, axial loading, torque, internal pressure, and their combinations. A numerical simulation was conducted on a thin-walled cylindrical specimen comprised of X18N10T steel, subjected to a temperature of $T\!=\!600\,^\circ$C, with the inner and outer surfaces subjected to ultrasonic peening. The reconstruction of the initial fields of residual stresses and plastic deformations was carried out based on the known experimental information on the distribution of axial and circumferential stress components in thin surface-hardened areas on the inner and outer surfaces. A phenomenological model of creep of steel alloy X18N10T at $T\!=\!600\,^\circ$C is constructed. The rheological deformation problem within the first two stages of creep was numerically solved using time and radius discretization. The calculations established that the presence of rigid constraints on angular and linear axial displacements resulted in a decrease in the rate of relaxation of residual stresses compared to the case where these constraints are absent. Graphs illustrating the kinetics of residual stresses with respect to the sequence of temperature and loading forces at different timestamps are presented.

thin-walled cylindrical tubes, bilateral surface hardening, residual stresses, creep, relaxation, tension, torsion, internal pressure, displacement constraints