Research Projects

The safety and integrity of structural components built from ferrous alloys requires effective resistance to harsh environmental conditions. The operational or processing exposure to hydrogen is a prime example of environment driven degradation. An introduction to a rich hydrogen environment in most metallic systems leads to embrittlement, which could result in a premature failure. In the case of DP steels, the ingress of nominal hydrogen concentration (few atomic ppm) within the complex microstructure causes drastic changes in the mechanical properties. The DP steel microstructure is quite complex as it contains multiple phases that results in unique local mechanics, and various trapping sites for hydrogen, thus examining the various concomitant processes that lead to the mechanical degradation due to hydrogen is still unclear. The ability to accurately measure the hydrogen concentration trapped at various microstructural features across the DP steel is crucial to assess the impact of hydrogen on the local micromechanics. However, the existing experimental characterization techniques are unable to capture this information due to difficulties associated with spatially resolving hydrogen. The key unresolved issues foiling a comprehensive understanding the influence of hydrogen on the deformation behaviour in DP steels: i) the microstructural hydrogen distribution in DP steels in presence of deformation; ii) the role of hydrogen on the strain localization behaviour along the ferrite-martensite interface; and iii) the extent of hydrogen assisted mechanical degradation of DP steels. These issues cannot be answered by solely relying on experimental characterization techniques, due to inability to characterize local hydrogen distribution, and difficulty in accurately quantifying the effect of hydrogen on the deformation behaviour. Therefore, the research objective of this study are: a) quantify the effects of hydrogen on macroscopic deformation behaviour; b) assess the role of hydrogen on dislocation-based plasticity; c) development of a microstructure informed coupled numerical framework; and d) understand the influence of microstructural features and tensile loading on hydrogen diffusion and trapping behaviour. Finally, the goal of this research proposal is to develop a novel hierarchical framework that synergistically combines insights obtained across various length and time scales from modelling and experimental tools to aid in the comprehensive understanding the effect of hydrogen on the deformation behaviour of DP steels.

Hydrogen, Dual-Phase Steels, Strain Localization, Plasticity, H Trapping