Mechanical properties of various kinds of irradiated austenitic stainless steels

Type 304, 304L, and 21 heats of Type 316 and 347 stainless steels with compositional changes in P, Si, N and Nb were:irradiated in a boiling water reactor to 1.7-2.2x10(25)n/m(2) (E>1MeV) and 3.3-4.0x10(25)n/m(2) (E>1MeV). Tensile tests in 561K air and Micro-Vickers hardness measurements on irradiated and unirradiated specimens were conducted. For alloys irradiated to 1.3-2.1x10(25)n/m(2) (E>1MeV),: the yield stress was dependent on the bulk impurity content. P and Nb enhanced hardening while N suppressed ductility loss in commercial purity 316L and 347L showed a similar tendency. Yield stress was well correlated to:hardness. At 3.2-4.4x10(25)n/m(2) (E>1MeV), all the alloys exhibited a yield drop and fractured without work-hardening and the yield stress was not dependent on the bulk impurity content. The effects on radiation hardening of P and N disappeared with increasing neutron fluence.