Microstructure-based constitutive model for pearlitic nanolamellar structuresBy Jon Alkorta (CEIT and TECNUN (University of Navarra))
Co-authors: José Manuel Martínez-Esnaola (CEIT and TECNUN (University of Navarra))
Peter de Jaeger (NV Bekaert SA)
Javier Gil Sevillano (CEIT and TECNUN (University of Navarra))
A new constitutive model for nanolamellar crystal structures was developed and adapted to a nanolamellar multi-colony pearlitic steel. The model, a two-phase continuum model, considers the plastic anisotropy of ferrite derived from its lamellar structure but neglects that of cementite and ignores the crystal nature of both constituents. The ferritic plastic constitutive equation takes into account a dependence on both the pearlitic spacing (arising from the confined slip of dislocations in the lamellae) and the strengthening from the evolving intralamellar dislocation density. As the model does not consider any dissolution of cementite, the plastic strain range covered by the model is in the domain where the lamellar structure and volume fraction of cementite are conserved (<2.5) and for (nominally) room temperature. The model naturally captures the macroscopic anisotropy and the internal microstresses developed due to the different mechanical behaviour of both phases. It is also able to describe the lamellar evolution (orientation and interlamellar spacing) with good accuracy. The model also captures the plastic instability due to kinking of the lamellar structure and shear band formation.
Ⓒ Photos:Toerisme Leuven