Intergranular mechanical behavior in a blade groove-like component by crystal plasticity model with cohesive zone model

Abstract

Creep-induced intergranular mechanical behavior was investigated in the first blade groove-like component on a steam turbine rotor. The involved method combined the crystal plasticity constitutive model with the cohesive zone model, to describe the stress-strain behavior inside the material’s grains and to model the traction-separation responses at the grain boundaries, respectively. Three displacement-drive FE submodels of the blade groove-like component were established to explore the effects of cohesive elements and predefined initial cracks. It was found that the cohesive elements relieved the stress concentration and eased the effects of material heterogeneity among the grains. With predefined initial cracks, the grain boundaries around the fillet surface were more greatly deformed to satisfy the overall displacement compatibility. The grain boundaries far inside of the blade groove, however, were extruded due to the bending behavior of the blade groove. Analysis of the overall intergranular mechanical behavior confirmed the long-term inhibitory effect of the initial cracks on further cracking.