| Abstract Scope |
Grain boundary engineering (GBE) is a process aimed at creating a high fraction of low energy boundaries in metals, improving their resistance to issues like crack propagation and corrosion. This technique often requires multiple deformation and annealing cycles, which are time-consuming and limited to simple geometries in wrought alloys. Laser additive manufacturing (AM) enables near-net shaping in a single step, hence possibly overcoming this challenge. However, its rapid heating and cooling cycles create complex microstructures with significant thermal strains. While ,these conditions can lead to dynamic recrystallization, low energy boundaries are rarely observed in additively manufactured metals. In this presentation, we will present several strategies to introduce such boundaries in AM microstructures, including; 1) post-build annealing to trigger recrystallization, 2) engineering the deposition strategy to stimulate strain-induced grain growth, 3) designing the solidification pathway to trigger phase transformations, 4) tailoring the structure of the solidifying liquid. These approaches will be illustrated through the case example of austenitic stainless steels, critical structural materials with a broad range of applications. The implications of GBE microstructures will be discussed in the context of outstanding societal and technological challenges. |