A microstructural comparison of two nuclear-grade martensitic steels using small-angle neutron scattering

Results are presented of a small-angle neutron scattering (SANS) study on two 10-13% Cr martensitic stainless steels of interest for nuclear applications, viz. DIN 1.4914 (MANET specification, for fusion reactors) and AISI 410. The investigation has focused principally on microstructural effects associated with the differences in chromium content between the two alloys. The size distribution functions determined from nuclear and magnetic SANS components for the two steels given identical heat treatments are in accord with an interpretation based on the presence of similar to 1 nm size C-Cr aggregates in the microstructure. Much larger (similar to 10 nm) scattering inhomogeneities with different magnetic contrast are also present and tentatively identified as carbides.