J. Kacher, G. Kennedy, S. Saiyara, N. Baltodano, A. Balandin, N. Thadhani
Georgia Institute of Technology,
United States
Keywords: H2 reduction, net-shape fabrication, steel
Summary:
We describe a novel technology for producing net-shaped engineered lattice and cellular structures of alloy steels by solid-state hydrogen-based direct reduction of extruded structures made from oxide powders. Fine iron oxide powders are combined with other oxides, as dictated by the desired steel alloy, and a polymeric binder, which can then be extruded using a commercial extruder into the desired lattice/cellular structure. The extruded structures is reduced in a flowing atmosphere containing hydrogen and solid-state sintered to obtain the final net-shaped alloy steel products. Direct hydrogen reduction of the extruded green bodies of the hematite/magnetite containing pastes allows zero process emissions fabrication of lightweight net-shaped alloy steel products with less total energy consumption due to lower process temperature requirements and avoidance of subtractive metal working processes. This approach provides geometrical flexibility, as parts with intricate internal structures can be extruded, and is amenable to the production of a wide variety of steels and other metal alloys. In this talk, I will discuss progress in understanding extrusion kinetics and reduction/sintering behavior of three different steel alloys: a commodity carbon steel, austenitic stainless steel, and an advanced maraging steel.