The aim of the performed experiments was to determine the influence of deformation and of austenitization temperature on the kinetics of phase transformations during cooling of high-carbon steel (0.728 wt. % C). The CCT and DCCT diagrams for austenitization temperature 940°C and DCCT diagram for austenitization temperature 1000°C were constructed with the use of dilatometric tests. On the basis of obtained results, a featureless effect of austenitization temperature and deformation on the kinetics of phase transformations during cooling of investigated steel was observed. Critical cooling rates for the transformation of martensite in microstructure fluctuated from 5 to 7°C · s–1 (depending on the parameters of austenitization and deformation), but only at cooling rates higher than 8°C · s–1 a dominant share of martensite was observed in the investigated steel, which resulted in the significant increase of hardness.

Hot Isostatic Pressing elaboration of Norem02, an austenitic-ferritic hypereutectoid stainless steel, leads to the formation of an austenitic matrix with a mixture of acicular M7C3 and globular M23C6 carbides. The sintering tests, carried out by using an AISI 304L container, showed that the final microstructure and the carbides’ distribution of the HIPed Norem02 are strongly influenced by the process parameters (heating and cooling rate, sintering time, holding temperature and pressure) and by the particles’ size, microstructure and phase distribution of the initial powder. The morphological, crystallographic and chemical analysis of the sintered samples were completed by comprehension of the diffusion phenomena at the Norem02/304L interface, enabling the establishment of a correlation between elaboration process and final microstructure.

A hot compression test was conducted on a Gleeble-3500 thermo-simulation machine to study the critical conditions and kinetics of dynamic recrystallization in a high-carbon tool steel. The critical conditions for the initiation of dynamic recrystallization were determined using the working-hardening theory. The quantitative relationship between the critical characteristics of dynamic recrystallization and the hot deformation parameters were elucidated based on two different methods:the apparent method and physically based method. It was found that the two methods both have high applicability for the investigated steel, but the physically-based method needs less parameters and makes it possible to study the effect of different factors. A dynamic recrystallization kinetics model was used to calculate the recrystallization volume fraction under different conditions. The calculation results matched well with the data obtained from the flow curves.