Cyclic Creep Deformation and Fracture of a Cr-Mo Rotor Steel at Elevated Temperatures

摘要

Static creep and cyclic creep tests were carriedout on a Cr-Mo rotor steel from 0.5 to 0.6 T_m.Cyclic creep retardation occurred under the testconditions.With an increase of stress frequency,cyclic creep strain rate decreases and rupture timeincreases.The cyclic creep strain rate for the stresswave of a square shape is higher than that of a tri-angle shape.The apparent stress exponent of cycliccreep and the apparent activation energy of cycliccreep are both higher than those of static creep.Theminimum strain rate is inversely proportional torupture time for both static and cyclic creeps at dif-ferent stresses,temperatures,frequencies and waveshapes.The cyclic creep retardation mechanism wasexplored by the observation and analysis of the dis-location structure and fracture surface.