SEDL / STP / STP1175-EB / STP23961S

Microstructural Studies in Fast Reactor Irradiated FV448 Ferritic-Martensitic Alloy Plate and Weldment

Morgan, TS
Research student and Professor, Institute of Polymer Technology and Materials Engineering, University of Technology, Loughborough, Leicestershire

Little, EA
Senior Scientist, Materials and Chemistry Division, Harwell Laboratory, Oxfordshire,

Faulkner, RG
Research student and Professor, Institute of Polymer Technology and Materials Engineering, University of Technology, Loughborough, Leicestershire

Pages: 15    Published: Jan 1994

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Abstract

The microstructure of an off-normal 12%Cr FV448-grade ferritic-martensitic weldment with 4.7 wt.% nickel addition has been compared with that of parent plate following fast reactor irradiation at 465°C to damage levels in the range 28–46 dpa. The fully martensitic weld metal exhibits instability under irradiation and transforms to a duplex austenitic/-martensitic structure with high void swelling in the austenite. Irradiation-induced precipitation differs between weldment and parent plate. M⁶X and G-phase are dominant phases formed in the plate; however, large δ-ferrite grains in the heat-affected zone contain only G-phase. Differences in precipitation in FV448 observed in earlier studies can be rationalized in terms of parameters which influence radiation-induced segregation.