Fabrication of SS316L to Ni80Cr20 graded structures by 3D plasma metal deposition

Powder metallurgy and thermal spraying has been used traditionally to manufacture functionally graded materials (FGMs).However, only simple geometries can be made with these processes and the compositional gradients cannot be tailored. Thesedisadvantages can be overcome by employing additive manufacturing (AM). 3D plasma metal deposition (3DPMD) is a newtechnique that combines the advantages of plasma powder and additive processes. This process allows the production ofstructures with mixtures of different materials and powder fraction targeting changes in local properties and microstructures.For example, up to four powders, which can be different in terms of chemistry and powder fraction, can be mixed within one layerto adapt the local properties of the structure. The feasibility of functionally graded structures of stainless steel 316L (SS316L) andNi80-20 alloy was studied. Two configurations, transition between the steel and the Ni-based alloy, were tested. The first one ishard transition, SS316L on the bottom and Ni80-20 on the top. The second one, a smooth transition between both materials wascreated with 50% of steel and 50% of Ni-based alloy. Optical microscopy and scanning electron microscopy were used tocharacterize the microstructures. The manufactured part showed good appearance, without any external defects and acceptablegeometric accuracy. The layer thickness was aroundz= 1 mm for both structures. Regarding the microstructural characterization,both materials displayed a dendritic structure. In the SS316L, the microstructure was composed by an austenitic matrix withδ-ferrite located in the grain boundaries. The microstructure of the Ni80-20 was characterized as an austenitic matrix, with someM7C3and M23C6precipitates. In addition, the Laves phase was also observed.     «

Powder metallurgy and thermal spraying has been used traditionally to manufacture functionally graded materials (FGMs).However, only simple geometries can be made with these processes and the compositional gradients cannot be tailored. Thesedisadvantages can be overcome by employing additive manufacturing (AM). 3D plasma metal deposition (3DPMD) is a newtechnique that combines the advantages of plasma powder and additive processes. This process allows the production ofstructures with mixtures of...     »