Carbide dissolution in bearing steels

The conditions leading to precipitate dissolution in a variety of bearing steels are studied. Computational thermodynamics and kinetics are employed to determine the microstructural effects leading to precipitate instability, and further dissolution. It is found that there exists a characteristic threshold value of the driving force that induces dissolution and that carbon migration from cementite towards the dislocation strain fields can play a dominant role. Microstructures not fully precipitated and far from their equilibrium volume fraction appear to be much more stable than their fully developed counterparts. An explanation to the occurrence of lenticular carbides engulfing white etching bands and areas is provided. It is discussed how dislocation development and migration in the neighbourhood of ferrite/carbide interfaces control carbide dissolution.

► Composition and driving force effects on carbide dissolution kinetics are studied.
► Microstructural dependence of carbide dissolution kinetics is studied.
► Precipitate volume fractions far from equilibrium are more stable.
► Formation of lenticular carbides is explained.