Mechanical properties of unirradiated and irradiated reduced-activation martensitic steels with and without nickel compared to properties of commercial steels

摘要

Tensile and Charpy specimens of four normalized-and-tempered martensitic steels were irradiated to 23-33 dpa at 376-405 degrees C in the Experimental Breeder Reactor (EBR-II). The steels were the ORNL reduced-activation steel 9Cr-2WVTa and that containing 2% Ni (9Cr-2WVTa-2Ni), modified 9Cr-lMo (9Cr-2WVTa), and Sandvik HT9 (12Cr-1MoVW). Two tempering conditions were used for 9Cr-2WVTa and 9Cr-2WVTa 2Ni: 1 h at 700 degrees C and 1 h at 750 degrees C. The 9Cr-1MoVNb and 12Cr-1MoVW were tempered 1 h at 760 degrees C. These heat treatments produced tempered-martensite microstructures for all steels except 9Cr-2WVTa-2Ni tempered at 750 degrees C, where a duplex structure of tempered and untempered martensite formed. Based on changes in tensile and Charpy impact properties, the results demonstrated the superiority in strength and ductility of the 9Cr-2WVTa reduced-activation steel over the commercial steels. Comparison of the mechanical properties after irradiation of 9Cr-2WVTa-2Ni and 9Cr-2WVTa steels indicated a favorable effect of nickel that could lead to development of a heat treatment for improved irradiation resistance. Published by Elsevier B.V.