Modeling Cu precipitation in tempered martensitic steels

A numerical model of competitive precipitation at grain boundaries, or more specifically at lath boundaries, on dislocations and in the matrix was developed to simulate Cu precipitation during tempering of low carbon martensitic steels. The Cu nucleus was assumed to be a bcc cluster at all nucleation sites. The influence of solute-depletion around the lath boundaries and dislocations on the precipitation in the matrix was taken into account. Because of the high density of dislocations and the small lath size both nucleation and growth of Cu particles in the matrix tend to be suppressed, and in some cases particles in the matrix dissolved at prolonged holding. These results seem to be consistent with experimental observations reported in the literature.