Grain Boundary Sliding in High Temperature Creep of a Precipitate-Free 25Cr–20Ni Austenitic Stainless Steel

抄録

Behaviours of the grain boundary sliding (GBS) in high temperature creep of a precipitate-free 25Cr–20Ni austenitic stainless steel were investigated over a range of stress (29.4–44.1 MPa), temperature (1153–1193 K) and grain size (30–540 μm). Results on the GBS measured on the specimen-surface exhibit that the strain resulting from the GBS is less than 14% of the overall strain, the effects of stress, temperature and grain size on the GBS being individually identified. It is, therefore, concluded that the overall strain rate (the steady state creep rate) is controlled by the deformation within grains. It is also found that the formation of intergranular cracks and voids is caused by the GBS. The GBS is thus an important factor for the creep rupture.