Impact of Deposition Procedures on 410L Multilayer Plasma Transferred Arc Processing

Additive manufacturing (AM), Directed Energy Deposition (DED) technology is an important industrial manufacturing tool to produce mechanical parts without using expensive molds with functionalities otherwise not possible. AM can be carried out to fabricate new components or on maintenance to rebuild the geometry of worn parts. Plasma Transferred Arc (PTA) is a low-cost, high-quality deposition technique that brings significant advantages in AM, and is used to process multilayers of AISI 410L. This study is part of an on-going study that addresses the impact of the deposition direction, bidirectional and unidirectional, and the mass flow (Qm) on the microstructure’s solidification of multilayers. Walls were built using four processing conditions and characterized in regions exposed to a larger and a small number of thermal cycles. Results pointed out that regions exposed to many thermal cycles, exhibited larger ferritic grains with an acicular structure at the grains boundaries and a uniform hardness profile. In contrast, the top region of multilayers exposed to a smaller number of thermal cycles revealed changes to the microstructure and hardness profile. The later exhibiting lower values at the last deposited layers up to 5 thermal cycles where larger grains formed followed by an increase after 8 thermal cycles and the onset of the acicular structure. The low mass flow used allow for good finishing of the multilayers nevertheless the increase in mass flow resulted on an increase in hardness at the different regions and more significant changes at the top layers.