Effects of Neutron Irradiation on Tensile Properties in High-Purity Fe–Cr Alloys

The tensile properties of high- and low-purity Fe–9, –18 and –30Cr alloys irradiated by neutrons up to a dose of 5 × 10²⁴ n/m² (E >1 MeV) at 613, 673, or 763 K have been examined. The yield strength and the ultimate strength are increased and the elongation is decreased by irradiation. The enhancement of these strengths due to the irradiation has a tendency to increase with chromium and impurity content. Large stress drops are often observed, especially at 763 K, in stress–strain curves of high-purity and high-chromium-content alloys except for Fe–9Cr alloys. Irradiation-induced precipitates, with 2% larger interplanar spacings than the α'-phase, on dislocation loops are more easily formed in the specimens of higher chromium content and higher purity. The precipitates are formed even in the irradiated Fe–9Cr alloy of high purity. The stress drop behaviour during the tensile tests is predominant in the specimens of higher chromium content and higher purity.