Coarsening of TiC in austenitic stainless steel — experiments and simulations in comparison

One way to increase the creep properties and corrosion resistance of austenitic stainless steels is to alloy with titanium, which forms small particles of TiC. When the steels are used at high temperature these particles undergo coarsening and the creep-resistance decreases. There exist two size distributions of TiC, one with sparsely distributed particles of micrometer size and a secondary one of densely distributed particles with sizes of a tenth of a micrometer. The sizes of the secondary TiC have been determined by transmission electron microscopy on samples of an ASTM 316Ti steel that have been heat-treated at 900°C for different times up to 6600 h. The measurements were compared with coarsening simulations with the DICTRA software, which takes into account the multicomponent effects on thermodynamics and diffusion. A good agreement between experiments and calculations is achieved if the interfacial energy, the only adjustable parameter in the simulations, is assumed to be round 0.2 J m−2.