The project: 'Improve Bendability of Ultra-High Strength Abrasion-Resistant Steels'
Abrasion-resistant steels are used extensively in construction, agriculture and mining for their capability of withstanding severe wear and tear, extending operational life and minimizing repair and replacement costs. However, forming of these strong steel grades may lead to issues such as splitting during bending. The bending behavior of these steel grades is currently poorly understood. Extensive microstructural characterization and mechanical testing of these grades has been performed trying to unravel the factors that influence failure. While these studies have revealed the complexity of the fully martensitic microstructure with microstructural variation toward the surface, they have not shown the root causes of failure, thus a clear path to design grades with better bendability is lacking. Therefore, the goal of this project is to unravel the micromechanical origin of the poor bendability of the abrasion resistant steel grades and to reveal critical microstructural configurations that should be avoided by heat treatment and alloy design.PhD vacancy with a focus on in-situ micro-mechanical testing and micromechanical modeling
To address the goal, a multi-scale integrated experimental-numerical micromechanical approach is adopted, with the following ingredients:
Section Mechanics of Materials and the Multiscale Mechanics Laboratory
in-situ SEM bending tests observing at the macro- to micro- to nano-scale, providing the evolution of strain fields overlaid on detailed EBSD microstructure maps, to establish the link between shear band formation, damage formation, and crack initiation and propagation;
- identification of the key micro-deformation mechanisms by high-resolution SEM-DIC testing and strain mapping of ultra-thin '2D' specimens, characterized à-priori by two-sided EBSD mapping yielding grain and phase orientations and prior austenite grain reconstruction;
- micromechanical modelling of these '2D' specimen tests, including their full 3D microstructure, enabling one-to-one comparison of numerical to experimental strain fields, to unravel the origin of the complex micro-deformation mechanisms and provide processing guidelines.
You will work in the Section of Mechanics of Materials (www.tue.nl/mechmat
), Department of Mechanical Engineering, which is globally recognized for its research on experimental analysis, theoretical understanding and predictive modelling of complex mechanical behavior in engineering materials at different length scales (e.g, plasticity, damage, fracture,…), which emerges from the physics and mechanics of the underlying multi-phase microstructure. An integrated numerical-experimental approach is generally adopted for this goal.
You will carry out the state-of-the-art high-resolution in-situ SEM micro-mechanical experiments at the Multiscale Mechanics Laboratory (www.tue.nl/multiscale-lab
), led by dr. Johan Hoefnagels (www.tue.nl/hoefnagels-group
), which bridges the gap between traditional materials science and mechanical characterization labs, by integrating micro-mechanical testing with real-time and in-situ microscopic observation.