Advances in metal Additive Manufacturing (AM) have increased its potential for use in the manufacture of components for commercial aircraft. Through both increased design freedom and substantial weight savings, metal AM is considered capable of transforming the
aerospace industry. Yet, variability in the mechanical properties of the printed metals (from a single machine and across multiple machines) is not understood, and is currently a critical obstacle to applications in this industry. As OEMs look towards industrialization of this process, mechanical property variability is a primary challenge. Furthermore, the absence of statistically-based descriptions for mechanical properties (e.g. in the MMPDS Handbook), make the certification of metal AM parts far more complicated than that for wrought form components.
In this proposed three-year research program, a team of investigators led by the University of Washington will evaluate the variability in mechanical properties of Grade 5 Ti6Al4V produced by laser powder bed fusion (LPBF) additive manufacturing. The overall objective of this JAMS-AMTAS proposal is to develop statistical descriptions for key static and fatigue properties and characterize the degree of property variability resulting from a tightly controlled set of build conditions. The three specific objectives are:
- characterize mechanical properties of Ti6Al4V produced by LPBF AM under both static and cyclic loading conditions following a ‘round-robin’ approach that involves six partners
- develop statistical descriptions for the mechanical property distributions that reflect variability of a single machine, multiple machines, printing zones and build replications
- evaluate the chemical composition, microstructure, and porosity of the metals and distinguish the contributions of metal quality to property variability and statistical control
A key quality of this program is that all partners will be printing metal using consistent and qualified feedstock, machine and processing parameters. As such, the results will provide robust statistical descriptions for mechanical properties of the metal that reflects variability over the build envelope, within and across machines, as well with powder reuse and potential degradation over time. By virtue of its design, the proposed effort will produce data that could ultimately help contribute to the development of procedures for both building LPBF parts and pursuing certification. Results from this program will help the aerospace industry produce metal components with improved safety, and facilitate greater application of this technology in producing parts for stress critical applications.