Mechanical Response of Microalloyed Steel Subjected to Nonlinear Deformation

Abstract

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.

Controlling deformation inhomogeneity in the Accumulative Angular Drawing Process assisted by constitutive and multiscale numerical modelling

“…Therefore, more complex models e.g. combined kinematic-isotropic hardening flow rule are developed (Graca et al, 2014). Another modelling approach includes flow rules based on internal variables e.g.…”

“…Material was assumed to be low carbon steel (Muszka, 2013). At macro scale, combined isotropic-kinematic hardening law was implementedmodel parameters were adopted from the previous Authors work (Graca et al, 2014). At micro scale, UHARD user subroutine was used to implement the developed physically-based hardening rule presented in the previous chapter.…”

Full-Field Strain Measurement and Numerical Analysis of a Microalloyed Steel Subjected to Deformation with Strain Path Change

“…Then, based on the model, the dislocation cells' size can be calculated. The detail description of the presented models can be found in [29].…”