Technological plasticity and structure in stainless steels during hot-working

Purpose: The high-temperature plastic deformation is coupled with dynamic processes of recovery influencing the structure and properties of alloys. One of crucial issues is finding the interdependence between the hot plastic deformation process parameters, the structure and properties. Design/methodology/approach: Hot plastic deformation was carried out using a torsion plastometer in the temperature range of 900-1150°C at a strain rate of 0.04-4 s-1. The plastometric investigations enabled the determination of the influence of deformation parameters on technological plasticity. Investigations of the samples’ structures were carried out using a light and electron microscope, by a thin film method. A quantitative analysis of structural changes was performed using the „MetIlo” image analysis programme. Findings: Results of the investigations have been provided referring to the influence of the hot plastic deformation process on the microstructure and the substructure as well as technological plasticity of steels of an austenitic, ferritic and ferritic-austenitic structure. Mathematical models were developed which link the deformation process parameters to the grain size obtained after the deformation as well as the mechanical properties determined in a torsion test. Practical implications: The research carried out enabled the understanding of the phenomena taking place during deformation and annealing of the investigated alloy. The results will constitute the basis for modelling the structural changes. Originality/value: The results obtained are vital for designing an effective thermo - mechanical processing technology for the investigated steels.