The purpose of the present work is to develop a mathematical model allowing the simultaneous prediction of both transformation product portions and mean ferrite grain size from the same common principles as a result of austenite decomposition during continuous cooling of plain carbon steels. The transformation products considered specifically are polygonal ferrite and pearlite. The model is based on the classical equations of nucleation‐growth theory and also contains some empirical parameters. The chemical driving forces for nucleation and composition of elements at the phase interfaces are derived from thermodynamic analysis. Three modes of ferrite nucleation are taken into account that correspond to the nucleation on the austenite grain corners, edges and faces. The model considers the reduction of the nucleation sites due to the occupation of austenite grain boundary surface by ferrite grains. Pearlite transformation starts at the γ/α interface and suppresses further ferrite grain growth. The parameters related to ferrite reaction were determined on the basis of a series of austenite transformation kinetic curves and grain size measurements for a steel with the composition 0.084%C‐0.58%Mn‐0.02%Si obtained by dilatometric technique for cooling rates from 0.032 to 2.5 K/s. The parameters related to pearlite reaction were determined on the basis of the data for a steel with 0.66%C. After determination of the model parameters the model was applied to complex cooling conditions of the run‐out table of the hot strip mill at Voest‐Alpine Stahl Linz GmbH. Predicted ferrite grain size appeared to be 1.2 −1.3 times smaller than the observed one. With regard to experimental data on grain growth in iron, it was suggested that the underestimation of grain size is due to additional ferrite grain growth occurring after the coiling of the steel sheet. Taking that into account provided satisfactory agreement with observed values.

The effects of cooling rate and austenite structure on bainite formation was investigated by means of electron backscatter diffraction analysis and processing of obtained orientation data. Variant pairing tendency of bainitic ferrite was found to depend on the austenite grain size, austenite plastic deformation and cooling rate. In the bainite formed at low cooling rate the variant pairs having the same Bain axis correspondence are more frequent, while at high cooling rate the variant pairs having the same parallel correspondence of close-packed planes are formed side by side preferably. At the same time, these features are influenced significantly by structural state of parent austenite.

In this paper we adduce experimental results showing qualitative correlation between structure and mechanical properties of metallic alloy 82K3XCP within a range of annealing temperatures up to 1 183 K. Specimens were made of industrial material (amorphous metallic glass) and represented thin films (2OxlOxO.03 mm). They were annealed in an oven and then their mechanical properties and structures were defined by microindentation on different polymer substrates and Xray powder technique. X-ray study exposes a complicated phase transformation process within the temperature range, which includes four different structural states: amorphous, two metastable, and "stable". Average particle size was estimated to be 30-50 nm according to broadening of diffraction maximum. Microindentation tests indicate two maximums of Vickers microhardness, whose locations correspond to the metastable structural states independently on the used substrate material. These allows us to conclude following. It is possible to observe directly qualitative correlation between structure and mechanical properties of metallic nanomaterial -annealed metallic glass. Used method of microindentation is structure-sensitive. Registered X-ray patterns draw detailed picture of the complicated phase transformation process, which needs to be investigated further. Discussed correlation allows us to suppose existence of similar correlation between structure and chemical, electromagnetic, or other macroscopic properties ofthe material.

A modeling approach to calculate the kinetics of non-isothermal bainite formation in low carbon microalloyed steels is presented. The model development is based on experimental data obtained by means of deformation dilatometry and electron back scattering diffraction. It is suggested that the misorientations inherited from the plastically deformed austenite make a significant contribution to the misorientation distribution in the final microstructure. Taking the inheritance phenomenon into consideration, the model allows prediction of the transformation kinetics and the effective grain size of bainitic microstructure as a function of the austenite deformation level and the cooling rate.

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