核电站弯管棘轮特性的试验研究

Pressurized piping in nuclear industries suffers complicated multi-axial loadings which may lead to significant ratcheting deformation. It is vital to ensure that these components are designed and in operation against ratcheting in nuclear industries. With a multi-axial fatigue test machine, ratcheting effect was studied experimentally for pressurized Z2CND18.12N austenitic stainless steel elbows under fully reversed bending. The experiment results show that the ratcheting strain occurs mainly in the hoop direction while there is less ratcheting strain in the axial direction. The maximum ratcheting strain of outside surface of elbows occurred mainly in the hoop direction at intrados, followed by 45 direction and at flanks. The minimum ratcheting strain was found at extrados. Both ratcheting strain and ratcheting strain rate increase with increasing pressure or reversed bending load. The prior cycling with higher loading restrains the ratcheting behavior of following cycling with lower loading.