Investigation of the interaction between recovery and precipitation in a model austenitic alloy: Experimental and modelling results

We investigated the microstructural evolution of six austenitic alloys containing increasing amounts of Nb and C. The experiments involved the room-temperature deformation of tensile samples in the solution-treated condition, followed by annealing treatments at 700-950°C. The samples were characterized using the techniques of small-angle neutron scattering, election microscopy and yield stress measurements. We interpreted the results in terms of a physically-based model that takes into account the processes of precipitation and recovery as well as their interactions. Given the initial deformation, alloy composition and annealing temperature, the model evaluates the precipitate size, number and volume fraction as well as the evolution of the dislocation density and yield stress. The model predictions and the experimental results are in good qualitative agreement. Quantitative agreement is possible through the adjustment of some of the less well-known physical quantities. Our results indicate that the softening behavior at low temperatures is dominated by the interaction between recovery and the strain-induced precipitation of NbC. The implications for strain-accumulation during industrial finish-rolling are briefly discussed.