Doctor of Philosophy
School of Mechanical, Materials and Mechatronic Engineering
Peng, Ching-Tun, Deformation behaviour and finite element method modelling of TWinning induced plasticity (TWIP) steel, Doctor of Philosophy thesis, School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, 2014. http://ro.uow.edu.au/theses/4131
TWinning Induced Plasticity (TWIP) steels have been placed as promising materials for the next generation of auto-related materials as well as the military applications due to their exceptional energy absorption ability. The present work investigates the compression and blast behaviour of Fe-18Mn-1.5Al-0.6C TWIP steel using various diffraction techniques and single crystal plasticity finite element method modelling.
The compression behaviour of TWIP steel has been investigated at various strain rates with different strains, including a Split Hopkinson Pressure Bar (SHPB) apparatus, and the results exhibited outstanding strain hardening. This unique feature is ascribed to mechanical twinning occurring during deformation which was proven by microstructural and crystallographic characterization and analysis. Mechanical twinning heavily generate during straining while slip makes a contribution. Tensile deformation favours twinning activity as compared to compression. An Explosive Bulge Test (EBT) was successfully conducted on the TIWP steel which provides a feasible way of strengthening the material and the grain refinement, caused by this pre-blast technique, was the main strengthening mechanism.
This is the first time a Crystal Plasticity Finite Element Method (CPFEM) model, based on single crystal assumption, was constructed in Abaqus environment with user material subroutine to simulate the course of nano-indentation of a TWIP steel. The crystal orientation, being necessary input parameters, of the TWIP steel was obtained from Electron BackScattered Diffraction (EBSD). Three unknown self hardening parameters were determined by fitting the experimental and simulated load-displacement curves.