Understanding pressure vessel steels: An atom probe perspective

A review of the contributions of the atom probe field-ion microscopy (APFIM) technique to the microstructural characterization of pressure vessel steels and to the understanding of the embrittlement of these materials during neutron irradiation is presented. Atom probe studies have revealed that the microstructure contains a variety of ultrafine clusters and precipitates some of which are only formed during neutron irradiation. Furthermore, there is a complex pattern of segregation of various solutes (including phosphorus, nickel, manganese, or molybdenum) to grain boundaries in some pressure vessel materials, and there may also be additional intergranular precipitation in these materials