Laser Powder Bed Fusion Additive Manufacturing of Oxide Dispersion Strengthened Steel Using Gas Atomized Reaction Synthesis Powder

Oxide dispersion strengthened (ODS) ferritic alloys (especially Fe-Cr alloy matrix) have growing application in nuclear fuel cladding for both fusion and fission reactors. Nano oxide dispersoid spread throughout the grain boundaries offer excellent creep and fatigue resistance as well as improved high temperature strength resistance. These thermally and mechanically stable nano oxide dispersoids within the matrix act as pinning locations which, facilitate improved radiation and creep resistance at high temperatures. Over the years, mechanically alloyed (MA) Fe-based alloys with oxide dispersion strengthening have largely dropped out of the marketplace due to high cost related to problems with complex and unreliable processing (agglomeration). Nevertheless, due to the highly desirable and sought after mechanical properties, there is ongoing research to solve the manufacturability and scalability hurdles. Recent progress in Fe-Cr ODS steels alloys produced by Gas Atomization Reaction Synthesis (GARS) techniques allows exciting research into solving the inherent issues. In this process, a reactive atomization gas (generally Ar-O2) is used to in-situ oxidize the crust of molten metal as it splits and solidifies. This creates a meta stable outer oxide crust which then acts as a reservoir. This research focuses on exploring the feasibility of using a Fe - 14Cr composition produced by GARS method with 3W-0.4Ti-0.3Y by weight % composition in the domain of laser powder bed fusion (LPBF) additive manufacturing method under different atmospheric conditions (Argon and Argon + 3, 5, 7, 10 % oxygen by weight) and extensively evaluate, analyze and report the properties of samples printed under different process parameters like print parameters, atmospheric conditions etc. Additionally, this research also aims to create a process map which will identify parameters that yield density (≥95% relative density) along with establishing process stability and repeatability.