Abstract
Directed energy deposition (DED) process is recognized as an alternative technology to produce the complex-shape AISI 316L components. The critical production step in this technology is the optimization of process parameters that can directly affect the final properties of the components. To optimize the process parameters, the residual defects of specimens produced with different combinations of process parameters are evaluated, and the optimum condition is chosen. Therefore, the residual defects assessment is a vital step in finding the optimum process parameters; therefore, this evaluation should be carried out carefully. One of the main issues in the production of AISI 316L by DED process is oxidation during the process that should be considered besides the other defects such as porosity and cracks. However, the identification between the oxides and porosities is not an easy task, and so this study aims to provide more clear insight into the evaluation of pores and oxides in DED 316L samples. The outcomes of this work show that at the best process parameters suitable for a porosity-free sample, there are some oxides that can be misinterpreted as porosity and consequently deteriorate the mechanical properties of the dense sample.
Highlights
Metal additive manufacturing (AM) is a production technology to build 3D complex-shape components layer by layer by using a computer-aided design (CAD) file [1, 2]
The main difference between these two AM typologies is related to the way of material feeding: in powder bed systems, there is a layer of powder that is selectively melted, whereas in powder/wire feed processes, as directed energy deposition (DED), the powder or wire is injected into the melt pool [9]
It is found that the presence of these oxides in the surface of particles can play a negative role on the oxide formation during the DED process
Summary
Metal additive manufacturing (AM) is a production technology to build 3D complex-shape components layer by layer by using a computer-aided design (CAD) file [1, 2]. This process allows producing precise geometric shapes in the bottom-up method [3]. There has been an increasing interest in AM technology to be used in different industries, such as automotive, aerospace and medicine [4, 5] The motivation for this interest is because of the flexibility in design and rapid productivity of metal AM technologies in the building of the complex and high-value parts in a single step [6]. The main difference between these two AM typologies is related to the way of material feeding: in powder bed systems, there is a layer of powder that is selectively melted, whereas in powder/wire feed processes, as directed energy deposition (DED), the powder or wire is injected into the melt pool [9]
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