NICOP - Understanding the complex microstructure of Additively Manufactured Alloys (AMAs) and its relationship to durability
Abstract
Additively manufactured alloys (AMAs) are already being used in Naval applications, with a rapid increase in use projected. To date," the use of components manufactured by AMAs are assumed to have a corrosion resistance equivalent to that of a component manufacture"d from wroughtmaterials of the same nominal composition. However, the corrosion risk associated with the use of these components is"" essentially unknown.AMAs, which are inclusive of 3D printed alloys, are distinct from conventional wrought alloys. To describe it"" concisely, a wrought alloy is prepared by melting, casting and comparatively slow solidification, followed by a number of thermomec""hanical processing steps that may take hundreds of hours to complete. In contrast, AMAs are nominally prepared (in the context of th""is proposal) with a melting and solidification process that leads to the final structure in a timeframe of << 1 second. As such, thi"s truncation in processing leads to significantly different structures ~ in spite of the same bulk composition ~ and hence different" properties in wrought alloys versus AMAs.Therefore, these ~differences~ in structure and properties expose an important knowledge" gap that needs to be addressed. This is of relevance to Naval applications in the context of the alloy being studied (316L stainles"s steel, which is the staple of corrosion resistant Naval alloys), but the metallurgical findings are of relevance to the nascent fi""eld of AMAs more strategically. To thisend, findings on the simple 316L alloy will be translated to high strength (and more complex"") stainless steels, in addition to compositionally complex alloy in this project.The desired outcomes of the project are to unambig"uously characterize the microstructures formed in AMAs as a function of processing parameters when produced by ~selective laser melt"ing~ (also known as laser powder processing or powder bed production), and to understand the factors that control the effects of AMA"" defects, including the role of porosity connectedness, on corrosionbehaviour, and non-equilibrium elemental segregation and phases" formed during processing of AMA. The project will harness state of the art analytical electron microscopy and be inclusive of elec"tron, x-ray and atom probe techniques capable of probing down to the atomic scale. The work will be presented to ONR/ONRG via report""s and project reviews, and will be published openly subject to approval from ONR. This work will form an important platform from whi"ch broader work in AMAs can proceed (such as understanding the corrosion and physical properties relative tomicrostructure). The project will also seek to integrate into the activities in AMAs focused on durability at the University of Virginia and Penn State Uni"versity, and alloy development at the University of Akron, by providing valuable D&I research.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 26, 2018
- Source ID
- N629091812077
Entities
People
- Nick Birbilis
Organizations
- Monash University
- Office of Naval Research
- United States Navy