Mechanical Testing of Additively Manufactured Superalloy Lugs

Abstract

Additively manufactured parts, in spite of their many advantages, face substantial challenges on the path toward certification. This challenge is more pronounced in the quality-demanding aviation industry, where the safety considerations are paramount. A major reason for this challenge is the lack of history associated with additively built parts compared to the traditional cast and wrought components. In assessing the structural integrity of cast and wrought components, material properties obtained from laboratory coupon tests are routinely applied for design calculations of large components. However, for additive manufacturing (AM) parts, questions remain over transferability of properties over multiple length scales due to possible variations in material chemistry, microstructure, and defect. In this work, this issue is investigated by conducting mechanical tests on small simplified lugs of nickel-based superalloy Haynes 282. The lugs are produced by the laser powder bed fusion process. After appropriate heat treatment and machining operations, the lugs are subjected to strength, low cycle fatigue, and crack propagation tests. Multiple tests are carried out in order to assess repeatability. Design calculations are performed to assess whether the test results can be predicted with standard methods. The results in this work generate confidence in predictable, repeatable behavior of the AM built lugs. Continuation of this approach over larger length scales has the potential to build enough confidence so that additively manufactured parts can be used in load-bearing structural elements of the aircraft engine.