Development of methods for the characterisation and modelling of precipitation in steels

The aims of this project were to compare different methods (both existing and novel) of characterising precipitate composition, growth and dissolution in steel, and to draw conclusions as to the methods that are most effective. In parallel, new mathematical models have been developed to describe precipitation, coarsening and dissolution of carbide and carbonitride phases, using equilibrium boundary conditions obtained from thermodynamic models. Experimental data for these models are obtained under isothermal conditions, but some models are extended so as to simulate real (anisothermal) processes of HSLA and IF steel manufacturing. The models thus developed have been tested by comparison with experimental measurements of the nature, volume fractions and particle sizes of precipitated second phases obtained under isothermal conditions.