IRRADIATION EMBRITTLEMENT OF MICROALLOYED FERRITIC STEELS

TISCON-50 and TISTEN-52 are two microalloyed and grain refined high st rength steels of Messrs TISCO, Jamshedpur. The former, produced as col d twisted bar, is used in the reinforced cement concrete (RCC) and the latter, produced as hot-rolled plate, has structural applications. An investigation was carried out to assess the irradiation stability of these steels. Tension and Charpy impact test specimens were irradiated to fast neutron fluences between 1.7 x 10(17) and 1.0 x 10(19) ncm-2 (E > 1 MeV), at less than 150-degrees-C. The increase in the yield str ength and the increase in the ductile to brittle transition temperatur e (DBTT) following irradiation were measured and compared with that of the pressure vessel steel SA212B irradiated under similar conditions. It was inferred from this investigation that both the steels possesse d adequate residual mechanical properties, after neutron irradiations to fluence levels equivalent to their expected end of life exposure.