Abstract
Creep at stresses below 100MPa and temperatures from 600°C to 750°C was investigated on two types of creep resistant steels: ferritic-martensitic P-91 type and austenitic AISI-316H type. Evidences were found that the creep process at low stresses is very different from that at high stresses in many features. The most important is that the efficiency of strengthening microstructural elements drops down drastically at low stresses. Deformation mechanism of the low stress creep remains unclear, but it is very sensitive to the fine microstructural changes which cannot be simply detected by optical and electron metallography.

Key words
creep test, heat resistant steel

Full text (140 KB)