CREEP CAVITY NUCLEATION AND GROWTH IN 12CR-MO-V STEEL

Quantitative measurements of the number of cavities per unit area, mean cavity size, and cavitated area fraction are carried out on creep tested specimens of a 12Cr-Mo-V martensitic steel. Both interrupted and ruptured specimens are included. Cavities initiate at an early stage of tests. The number of cavities, mean cavity size, and cavitated area fraction exhibit a continued increase with increasing strain and time. At rupture, the number of cavities is about 30 000 mm(-2), and the mean cavity size has a maximum value of about 2.5 mu m. The cavitated area fraction is approximately 0.1% at 1% strain, 0.5% at 2% strain, and 10% at rupture. Cavity initiation and growth are analysed regarding temperature, stress, strain, and str ain rate. A constrained cavity growth model is discussed and compared with the experimental results.