Microstructure and Mechanical Properties of AISI 316L Produced by Directed Energy Deposition-Based Additive Manufacturing: A Review

Abstract

Directed energy deposition (DED) as a metal additive manufacturing technology can be used to produce or repair complex shape parts in a layer-wise process using powder or wire. Thanks to its advantages in the fabrication of net-shape and functionally graded components, DED could attract significant interest in the production of high-value parts for different engineering applications. Nevertheless, the industrialization of this technology remains challenging, mainly because of the lack of knowledge regarding the microstructure and mechanical characteristics of as-built parts, as well as the trustworthiness/durability of engineering parts produced by the DED process. Hence, this paper reviews the published data about the microstructure and mechanical performance of DED AISI 316L stainless steel. The data show that building conditions play key roles in the determination of the microstructure and mechanical characteristics of the final components produced via DED. Moreover, this review article sheds light on the major advancements and challenges in the production of AISI 316L parts by the DED process. In addition, it is found that in spite of different investigations carried out on the optimization of process parameters, further research efforts into the production of AISI 316L components via DED technology is required.

Base Plate Preheating Effect on Microstructure of 316L Stainless Steel Single Track Deposition by Directed Energy Deposition

“…Microstructural tuning in order to tailor mechanical properties has great importance. It is evident from the extensive literature in metal AM [4][5][6][7][8][9][10][11][12][13][14]. Studies on grain morphology, melt pool solidification, solidification texture, the temperature gradient in the melt pool, the affect of cooling rate on morphology, and size of the microstructure are reported for AM [15][16][17][18].…”

Directed Energy Deposition of AISI 316L Stainless Steel Powder: Effect of Process Parameters

“…As reported in Table 3, in fact, the LP parameters cause the solidification of finer γ cells. As suggested in previous work, the high Yield Strength (YS) and Ultimate Tensile Strength (UTS) of AM 316L is mainly related to the fine cell size and dislocation densities [36,37]. Tensile properties of 316L samples produced by LP-DED using LP parameters and a powder provided by a different producer are also reported [7].…”

Process Window for Electron Beam Melting of 316LN Stainless Steel

“…The z-oriented tensile bars fulfilled the yield strength requirement for all tested process settings but failed to comply with the ultimate tensile strength and elongation requirements. Anisotropic mechanical properties in additively manufactured components are a common occurrence and are known to originate in the microstructure [17,22,23]. Thermal treatment throughout the entire build cycle due to elevated build temperatures in the EBMbuild chamber have a history of producing as-built materials with good strength, high ductility, and low residual stress [24], which explains the high elongation at break recorded for the xy-oriented tensile bars.…”

“…Therefore, 316L is a desirable choice for industrial adaptation for EBM. Using 316L(N) for additive manufacturing is not novel in itself; laser-PBF [12][13][14] and directed energy deposition [15][16][17] methods have been used to process 316L feedstock into solid parts. The novelty is found with the adaptation of the EBM process to the 316LN powder feedstock, and where previously mentioned research has demonstrated the feasibility of using EBM for 316LN for producing parts, this work explores the processing parameter space for which good, solid parts can be manufactured.…”