Irradiation creep induced stress relaxation of Inconel 718

Torsional creep tests were conducted on Inconel 718 specimens under 17 MeV proton irradiation at 300 degreesC for doses up to similar to0.08 dpa. The stress dependence of the irradiation creep rate was measured by increasing the maximum applied sheer stress from 150 up to 450 MPa. The experimental r esults show that the stress dependence of the irradiation creep rate is lin ear in the whole stress range applied. The irradiation creep constant kappa = 1.2 x 10(-11) (dpa(-1)Pa(-1)) at 300 degreesC. The calculated creep indu ced stress relaxation amounts to similar to 10% after 0.1 dpa. The results are discussed in relation to the operating condition of an ITER-like machin e, where Inconel 718 bolts are used to mechanically attach the shielding bl anket to the back plate. (C) 2000 Elsevier Science B.V. All rights reserved .