SEDL / STP / STP1366-EB / STP12416S

Irradiation Behavior of Ferritic-Martensitic 9–12%Cr Steels

Horsten, MG
Materials scientists, NRG (former ECN), LE Petten,

van Osch, EV
Materials scientists, NRG (former ECN), LE Petten,

Gelles, DS
Staff scientists, PNNL Materials Research Department, Richland, WA

Hamilton, ML
Staff scientists, PNNL Materials Research Department, Richland, WA

Pages: 15    Published: Jan 2000

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Abstract

A dedicated series of irradiation experiments has been executed in the high flux reactor (HFR) in Petten (Netherlands) to evaluate the irradiation behavior of ferritic-martensitic 9–12%Cr steels at temperatures in the range of 70°C to 370°C and damage dose levels up to 3 dpa. Materials investigated in the program comprise Mod.9%Cr (9Cr-1Mo-0.2V-0.08Nb), HT9 (12Cr-1Mo-0.5W-0.5Ni-0.3V), MANET type steel (10Cr-0.5Mo-0.6Ni-0.2V-0.15Nb), NF616 (9Cr-2W-0.5Mo-0.2V-0.07Nb) and HCM12A (12Cr-2W-1Cu-0.4Mo-0.3Ni-0.2V-0.05Nb). The 9–12%Cr steels show severe hardening and ductility reduction at room temperature (RT) after neutron irradiation. Strength, ductility and toughness of material irradiated at 70°C gradually recover with increase in test temperature. Similar ductility trends of material irradiated at 300°C are observed as for unirradiated material, but recovery with increase in temperature is not observed below temperatures of 400°C. The 9%Cr steels show less hardening and reduction in ductility than the 10–12%Cr steels. The reduction of area and 0.2% yield stress correlate well with the upper-shelf energy and ductile-to-brittle transition temperature, respectively, both for the unirradiated and irradiated condition. In general, the 9%Cr steels show more resistance to irradiation at 300°C than the 10–12%Cr steels with respect to fracture toughness.