A combined thermo-mechanical model for Tribological Surface Transformations

Some of the French railroad network’s rails have been affected for the last about twenty years or so by an undesirable physical phenomenon known as Tribological Surface Transformations (TSTs), which are irreversible, quasi-surface solid–solid phase transformations. Although the physical causes of TSTs have not yet been clearly established, it seems likely that the mechanical loads combined with the thermal effects of the wheel/rail contacts may be largely responsible. The present study is based on the assumption that the combined thermo-mechanical constraints may generate solid–solid phase transformations. The thermo-mechanical model developed on these lines was based on previous studies on TRansformation Induced Plasticity (TRIP), which are extended here to account for TSTs. The ability of the model to describe TSTs initiation and development is also assessed by performing a 2-D finite element analysis.

► Tribological Surface Transformations are quasi-surface solid–solid phase transformations.
► We model irreversible phase transformations in a thermo-mechanical framework.
► We exhibit conditions for the local equations to be thermodynamically consistent.
► Main lines of the numerical procedure for solving the structural problem are presented.
► Numerical reproductions of Tribological Surface Transformations are given and discussed.