Evolution of Lath Substructure and Internal Stresses in a 9% Cr Steel during Creep

The changes in the dislocation substructure and internal stresses in a tempered 9% Cr heat resistant steel during creep at 923 K were studied. The mean lath size gradually increased from 330 nm for the initial tempered state to 740 nm once the specimen had crept to failure under a nominal stress of 118 MPa after 1271 hours. Correspondingly, the dislocation density within the lath decreased from 6.2 × 1014 m−2 to ~1014 m−2. The tempered structure...