Corrosion Testing for Additive Manufacturing

This technical report presents the current state of knowledge and gap analyses on corrosion testing of metallic materials produced using additive manufacturing (AM) technologies in environments relevant to several industrial applications. The discussed materials were produced primarily via laser powder bed fusion (LPBF), directed energy deposition (DED), and specifically the wire arc additive manufacturing (WAAM) form of DED. Many variables may not be sufficiently detailed in the rapidly evolving state of the art at the time of publication for the assessment of the performance of AM products; some variables such as microstructure, post-build processing, surface condition, residual stress, physical defects, and selection of representative test specimens (size and/or geometry) for a finished product are addressed. This report contains approaches for corrosion and environmental cracking assessment of AM materials, including test details that are relevant to the AM processes for some specific cases. The technical report provides the foundation for the preparation of test standard(s) that apply to AM products.

The variables that affect the corrosion behavior of additive manufactured metallic materials are important to understand in order to successfully fabricate functional AM components. Issues such as the type of AM process, AM build parameters, microstructure, surface condition, specimen geometry, post-processing heat treatments, etc. all affect the finished product. The literature to date does not have sufficient single source papers that cover all of these variables and the variables that are assessed are usually limited to one or two classes of metal alloy systems. Also, though standardized corrosion testing methods are typically appropriate for AM products, the selection and treatment of the test samples used have not been adequately addressed. This technical report was created in order to provide a summary of the current state of knowledge research of the variables that affect the corrosion, cracking, fatigue, and oxidation behavior of AM fabricated parts, including test methodologies. In addition, this report also highlights the limits of the current industry understanding of AM corrosion issues by including a gap analysis.