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Dr. Hunter Martin
October 12 @ 11:00 am - 12:00 pm
Affiliation: HRL Laboratories
The Role of Inoculation in Processing Additively Manufactured High-Strength Aluminum Alloys
ABSTRACT: Metal additive manufacturing, or 3D printing, has the potential to be an incredibly disruptive technology for the fabrication and integration of complex components in a variety of industries, ranging from automotive and aerospace to medical devices and sporting goods. Until recently, additive manufacturing of metals was mostly used for non-critical or prototyping applications, however a global push for improved energy efficiency via light weighting and topological optimization, as well as reduced cost via lower material waste and near net-shape fabrication, is pushing metal additive manufacturing out of the prototype stage and into full scale production. There has been relatively little focus on improvements of the materials which are used in additive manufacturing, which have been limited to a few “weldable” alloy systems such as Al10SiMg, Ti6Al4V, and Inconel 718. While these alloy systems have provided a good first step in development of the additive industry, they are extremely limited when compared to the >5000 different alloy compositions available in either cast or wrought forms. This limitation is driven by the unique processing conditions of additive manufacturing which differ significantly from conventional bulk material production developed over centuries, if not millennia.
This presentation will investigate the unique solidification conditions present during additive manufacturing of aluminum alloys and attempt to understand how novel inoculant methodologies may be used to not only control microstructure evolution of model unalloyed aluminum systems but extend the available alloy systems beyond what was previously considered amenable to the additive process. Until now, microstructure control in additive was limited to parametric manipulation, however this has been difficult to broadly implement across all alloy systems. This presentation will provide background information to understand the solidification conditions present in laser powder bed fusion as well as a methodology for inoculation of additive alloys and mechanistic discussion utilizing a model unalloyed aluminum system. Finally, this presentation will demonstrate that utilization of this inoculation approach can in fact eliminate the crack susceptibility of high strength aluminum alloys (Al7075 and Al6061) and produce crack free additive aluminum with strengths 2X that of the most common commercial Al10SiMg alloy system.
BIOGRPAHY: Hunter Martin received his Ph.D. from the University of California, Santa Barbara, in Materials and B.Sc. in Material Science and Engineering from the University of Washington, Seattle. After undergraduate studies he worked for multiple small companies as an engineer developing new nanostructured alloy systems. Dr. Martin currently works for HRL Laboratories LLC. In Malibu Ca, where he develops new alloy systems for additive manufacturing with a focus on microstructure control.