SYMPOSIA PAPER Published: 01 January 1973

Influence of Neutron Spectrum and Microstructure on the Postirradiation Creep-Rupture Behavior of an Austenitic Cr-Ni-Ti-B Steel


The influence of neutron irradiation on the postirradiation creep rupture properties of a 15Cr-15Ni-Ti-B steel and their dependence on microstructure and neutron spectra were studied. The steel was tested in three conditions: (a) solution treated at 1150 C (2012 F), (b) solution treated and aged at 1025 C (1877 F), (c) solution treated and aged at 900 C (1652 F). The conditions are characterized by an increasing amount of TiC precipitates going from treatment (a) to (c). The irradiations were carried out in the BR 2 reactor (Mol/Belgium) to a fast neutron fluence of 2 × 1021 n/cm2 (E >0.1 MeV) and in the FR 2 reactor (Karlsruhe) to a thermal neutron fluence of 3 × 1020 n/cm2. The ratio of thermal to fast neutron flux was about 0.66 for BR 2 and 30 for FR 2 irradiations. The irradiation temperature was about 70 C (158 F). The postirradiation creep rupture tests were carried out at 650 C (1202 F).

The changes in creep rupture properties after irradiation were found to be strongly dependent on the neutron spectrum and the thermal pretreatment of the steel. The main results can be summarized as followed: 1. The fast thermal neutron irradiation in the BR 2 caused an increase in rupture life and decrease in creep rate of the steel in the solution-treated condition and also, but to a lower extent, in the 1025 C (1877 F) aged condition. With increasing stress the difference between the irradiated and unirradiated values diminished. 2. Irradiation in the FR 2 caused a decrease in rupture life and increase in creep rate of the 1150 and 1025 C (2102 and 1877 F) annealed conditions. The effect was more pronounced in the solution-treated than in the 1025 C annealed condition. The difference between the irradiated and unirradiated values decreased with decreasing stress. 3. There were no remarkable changes in creep rate and rupture life after irradiation of the steel in the 900 C (1652 F) annealed condition.

The results are discussed in terms of radiation-influenced precipitation processes superimposed by radiation-induced high-temperature embrittlement.

Author Information

Böhm, H
Gesellschaft für Kernforschung mbH, Karlsruhe, West Germany
Wassilew, C
Gesellschaft für Kernforschung mbH, Karlsruhe, West Germany
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Developed by Committee: E10
Pages: 437–450
DOI: 10.1520/STP35466S
ISBN-EB: 978-0-8031-4627-3
ISBN-13: 978-0-8031-0328-3