Bimetals produced by explosive welding and subjected to surface mechanical attrition treatment (SMAT) were investigated. It is expected that the way of manufacturing and the morphology of nano- crystalline and multilayered materials obtained by the "top down" group of methods such as severe plastic deformation (SPD) has significant influence on the deformation mechanisms. The basic materials investigated in the paper were microalloyed steel and Nickel super-alloy. Bimetals were subsequently subjected to the deformation by compression test under dynamic and quasi-static conditions. Microstructural study based on light microscopy and scanning electron microscopy was performed focused presumably on the plastic flow of the deformed metallic laminate.

Development of a reliable model of phase transformations in steels presents significant challenges, not only metallurgical but also connected to numerical solutions and implementation. The model proposed in this paper is dedicated to austenitic transformation during heating and ferritic transformation during cooling. The goal was to find a solution which allows for the decreasing of computing time without noticeable decreasing the accuracy and reliability of the model. Proceedings to achieve this goal were twofold. Statistically Similar Representative Volume Element was used as a representation of the microstructure. It allowed for the reducing of the complexity of the computational domain. For the purpose of the model, carbon diffusion was assumed to be the main driving force for both transformations. A coupled finite element–level set method was used to describe growth of a new phase. The model was verified and validated by comparing the results with the experimental data. Numerical tests of the model were performed for the industrial intercritical annealing process.

Studies of the effects of inhomogeneity of UFG (ultrafine-grained) microstructure evolution have been performed on severely deformed specimens produced by AAD (angular accumulative drawing), followed by wire drawing and wire flattening processes i.e. “top-down” systems of the grain refinement process. In this paper, deformation behavior and size effects are illustrated by means of UFG microalloyed steel with different combinations of microstructure length scale and deformation inhomogeneity. The refined and severely elongated structures were investigated by light microscopy, TEM and EBSD. Of particular importance was the understanding of the effects of strain path, microalloying elements and deformation inhomogeneity on grain refinement and dislocation substructure formation processes.

Microalloyed steels have been the subject of theoretical and experimental studies revealing their exceptional mechanical response under nonlinear deformation conditions. In microalloyed steels, especially in multiphase steels, the mechanical properties are adjusted by combination of microstructure components with different levels of theirs mechanical responses, including hardness and ductility. A comprehensive studies have revealed that a transition from the development of usual bulk dislocation microstructures to more architecture ones occurs when the applied strain path allows to cumulate the deformation energy what is also strictly connected with the chemical and structural compositions of analyzed materials. The study presented here aims at understanding the complex strengthening mechanisms as well as microstructure evolution and to provide a link with the mechanical behaviour of investigated steels under nonlinear deformation conditions. The proper choice of the work hardening model for the cyclic plastic deformation is essential for predicting the inhomogeneities occurring during metal forming. Aim of the current work is to discuss the differences between various hardening models with respect to their capabilities in capturing complex deformation models and possibilities of their direct application to finite element modelling of such deformation processes. The results of experimental studies are integrated with computer modelling and dislocation theory to provide insight into the unprecedented combination of properties achieved in certain multiphase steels such as ultra-high flow strengths, good ductility and workability. Finally, based upon results obtained in performed computer simulations, conclusions regarding the possibilities of potential application of the work hardening models in the identification process parameters, trough the inverse analysis, are drawn.