Influence of interface orientation and surface quality on structural and mechanical properties of SS316L/IN718 block produced using directed energy deposition

Abstract

Functionally graded materials manufactured by additive manufacturing technologies reached high interest in additive manufacturing community over the last decades. High potential of additively manufactured multi-materials was demonstrated by many studies over the last 10 years. Most of the studies dealing with functionally graded materials had one common sign, which is the chemical composition gradient being controlled in the building direction of the final product. Hence, the multi-material interface is mostly situated in horizontal plane (XY) of the product. However, due to a complex geometry of the product, it is not always possible or desirable to achieve certain interface orientation and multi-material interface might incline from the ideal horizontal plane. Typically, corner zones, where interface orientation changes suddenly from horizontal to vertical orientation, are the most critical locations. Therefore, investigation of the interface orientation is important in order to establish the additive manufacturing limitation for certain applications. The current study revealed that the interface inclination has significant influence on the amount and distribution of formed defects at the materials interfaces. Furthermore, it was shown that the interface surface quality in terms of as-deposited surface or machined surface can significantly affects the defects formation. The effect of defects on the tensile specimen's elongation was significant, which based on the interface angle dropped over more than 70%.