Mechanism for beneficial effect of boron addition on creep resistance of 9-12% chromium steels

Paper in proceeding, 2006

Energy filtered transmission electron microscopy has been used to study two similar steels after long time aging, with different boron additions, to measure the effect of B on coarsening rate of M23Ce precipitates. The mechanism behind the effect of boron could either be a drastic decrease in the energy of the interface between M23C6 and matrix or a decrease in flux of atoms from a shrinking precipitate to a growing one. We suggest that the latter mechanism is operating, based on atom probe (APFIM) measurements of boron solubility in the matrix and the detection of Mo-B clustering.