Relationship between in-reactor stress relaxation and irradiation creep

Stress relaxation and irradiation creep data are available for 20% CW 316 SS samples fabricated from the same heat of material. The stress relaxation and irradiation creep tests were both performed in bending. The stress relaxation was calculated using an irradiation creep correlation formulated using the irradiation creep data. The calculations were in excellent agreement with the measurements and show that stress relaxation may be calculated using irradiation creep data when the proper methods are used. The methods for this calculation include the use of a transient exponential decay coefficient with a dose rate consistent with the stress relaxation application, the use of irradiation creep coefficients derived from tests with material consistent with the stress relaxation application and the use of irradiation creep data with the same stress state. (orig.)