Modelling of steel phenomena and their interactions – an internal variable approach

Abstract

Stress-and strain-dependent phase transformations (PT), transformation-induced plasticity (TRIP) and its interaction with classical plasticity (CP) are important phenomena in the material behaviour of steel, and they may cause distortion of work-pieces. These phenomena are intensively studied in experiments and their modelling is a current field of investigations. A complex model of material behaviour for simulation and distortion controlling must include the models of relevant phenomena. It is the aim of the current paper to contribute to the formulation of such a model. We use internal variables for describing special effects in the material behaviour in the context of macroscopic continuum mechanics and include them in the thermodynamically consistent modelling.Keywords

Transformation‐induced plasticity: Modelling and analysis in 3‐d with more than two phases

“…[1][2][3][4]). PT's occurring under non-vanishing deviatoric stress (smaller than the yield stress of the weaker phase) lead to a permanent anisotropic deformation which cannot be described by classical plasticity (CP) at the macroscopic level.…”

“…Its modelling contains some open questions, in particular in case of varying loads and of interaction with CP (cf. [2,4]). In this note we present macroscopic models for TRIP in the multi-phase case.…”

“…For uniaxial tension under constant stress S and constant temperature θ there it has been found by experiments (cf. [1][2][3][4] and the literature cited therein):…”

“…The maximum term in (2) ensures that only forming phases currently contribute to TRIP (cf. [4]). Generally, the parameters κ i (i = 1, ..., m) may depend on θ and further entities.…”

“…A linear ansatz for X trip and X cp (backstress associated with CP) taking a possible interaction of TRIP and CP into account (cf. [2,4]) reads as…”