Grant: Discovery Grants Program - Individual

This research program focuses on a fundamental engineering challenge: striking a balance between strength and ductility in metallic materials, particularly precipitation hardening martensitic stainless steels (PH-MSS). These materials exhibit impressive mechanical properties and corrosion resistance, ideal candidates for high-load, high-friction, and high-temperature environments. The adoption of additive manufacturing (AM) technologies for PH-MSS production significantly reduces design-to-market timelines and production costs. However, AM PH-MSS faces challenges including strength-ductility trade-off, textured grain structures, and anisotropic properties, making it difficult to attain balanced mechanical properties with predominantly refined and texture-free grain structures. This research program is committed to developing practical solutions for fabricating novel PH-MSS matrix composites that aim to strike a harmonious balance between high-strength and substantially enhanced ductility. This will be achieved by strategically incorporating Titanium-based ceramic particles into the PH-MSS matrix during the AM process, serving as both inoculants and reinforcements. The research goal is pursued through four key objectives: 1) develop a theoretical framework for evaluating the grain-refining effectiveness of ceramic-based inoculants during AM, 2) establish an industry-scalable process for AM-ready MSS composite feedstock powder production, 3) devise strategies for defect-free production of ceramic-reinforced PH-MSS parts through various AM modalities, and 4) investigate primary strengthening and grain-refining mechanisms in each AM-fabricated composites. First, an Interdependence Model will be utilized to identify factors controlling final grain size during AM. Using this theoretical framework, two Titanium-based ceramic inoculants with high grain refining efficiency will be selected. Second, the effectiveness of two powder production methods, i.e., gas atomization and ball milling, will be explored for production of the selected composite feedstock powders with varying size and volume fractions of reinforcing particles, followed by thorough characterization. Third, different AM modalities (laser powder bed fusion and arc directed energy deposition) will be employed to understand the composite feedstock powders response to these AM technologies. Finally, advanced mechanical testing and microstructural evaluation will assess primary strengthening and grain refining mechanisms in each composite, validating the theoretical framework developed in the first phase. The successful execution of this research program will broaden the applications of these advanced materials across various industries in Canada. This program will train highly qualified personnel with expertise in Materials Science and Manufacturing, emphasizing Equity, Diversity, and Inclusion, who will contribute to Canada's future competitiveness in industry and research institutions.