Atomic Scale Investigation of Solutes and Precipitates in High Strength Steels
Two steels, ferritic, high strength with interphase precipitation and nanobainitic, were used to show the advances in and application of atom probe. The coexistence of the nanoscale, interphase Nb-Mo-C clusters and stoichiometric MC nanoparticles was found in the high strength steel after thermomechanical processing. Moreover, the segregation of carbon at different heterogeneous sites such as grain boundary that reduces the solute element available for fine precipitation was observed. The APT study of the solutes redistribution between the retained austenite and bainitic ferrite in the nanobainitic steel revealed: (i) the presence of two types of the retained austenite with higher and lower carbon content and (ii) segregation of carbon at the local defects such as dislocations in the bainitic ferrite during the isothermal hold.
L. Pentti Karjalainen, David A. Porter and Seppo A. Järvenpää
P. Hodgson et al., "Atomic Scale Investigation of Solutes and Precipitates in High Strength Steels", Materials Science Forum, Vol. 762, pp. 14-21, 2013