Tailoring Laves phase and mechanical properties of directed energy deposited Inconel 718 thin-wall via a gradient laser power method

Purpose Laser melting deposition (LMD) is an advanced additive manufacturing (AM) technology without powder waste, and nickel-based alloys with different Nb contents were created one-time by adjusting the ratio of mixed powders via a dual-feed system. Here, the authors provide a systematic report on the effects of the Nb content on the microstructure, Laves phase segregation and mechanical properties of as-received LMD nickel-based alloys. The effects of the Nb content on the microstructure, precipitation evolution and mechanical properties of the subsequent heat-treated LMD samples are also discussed in this paper. Design/methodology/approach Thus, the present research aims to obtain a better understanding of the effect of Nb content on the microstructural and mechanical properties of the as-received LMD Inconel 718 alloys through high-throughput sample fabrication. The microstructures were characterized by scanning electron microscopy and energy-dispersive spectroscopy, electron back-scattered diffraction and transmission electron microscopy methods. The mechanical properties were obtained from compressive tests and nano-indentation tests. Electrochemical tests, including electrochemical impedance spectroscopy and potentiodynamic polarizations, were carried out to evaluate the durability of the Inconel 718 alloys. Results can provide a factual basis for future applications of the functionally graded by AM technology. Findings The grain size of the as-received LMD Inconel 718 alloys decreased with the Nb content. The Laves phase distribution at the macro level was relatively uniform and the Laves phase exhibited a 1.5-fold nano-hardness compared with the matrix. The strength improvement for the as-received LMD Inconel 718 alloys with Nb content was attributed to grain refinement and enhancement of the Laves phase in terms of both hardness and content. Meanwhile, the corrosion resistance increased with the increase of the Nb content, especially for the pitting potential, which was attributed to the optimization of carbide precipitates due to the strong affinity between niobium and carbon. Originality/value The results provide a factual basis for the Nb content effect in LMD nickel-based alloys, and this method can greatly promote the development of new materials. The authors believe that this study makes a significant contribution to the literature and is suitable for publication.

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Mechanical Properties of High Strength Aluminum Alloy EN AW-7075 Additively Manufactured by Directed Energy Deposition

Metals ◽

10.3390/met10050579 ◽

2020 ◽

Vol 10 (5) ◽

pp. 579

Author(s):

Anika Langebeck ◽

Annika Bohlen ◽

Rüdiger Rentsch ◽

Frank Vollertsen

Keyword(s):

Mechanical Properties ◽

Additive Manufacturing ◽

Laser Power ◽

Energy Deposition ◽

Positive Impact ◽

Lightweight Design ◽

High Strength ◽

Tensile Tests ◽

Directed Energy Deposition ◽

Directed Energy

A manifold variety of additive manufacturing techniques has a significant positive impact on many industry sectors. Large components are often manufactured via directed energy deposition (DED) instead of using powder bed fusion processes (PBF). The advantages of the DED process are a high build-up rate with values up to 300 cm3/h and a nearly limitless build-up volume. In combination with the lightweight material aluminum it is possible to manufacture large lightweight components with geometries adapted to customer requirements in small batches. This contributes the pursuit of higher efficiency of machines through lightweight materials as well as lightweight design. A low-defect additive manufacturing of high strength aluminum EN AW-7075 powder via DED is an important challenge. The laser power has a significant influence on the remaining porosity. By increasing the laser power from 2 kW to 4 kW the porosity in single welding tracks can be lowered from 2.1% to only (0.09 ± 0.07)% (n = 3). However, when manufacturing larger specimens; the remaining porosity is higher than in single tracks; which can be attributed to the oxide skin on the preceding welding tracks. Further investigations regarding the mechanical properties were carried out. In tensile tests an ultimate tensile strength of (222 ± 17) MPa (n = 6) was measured. The DED processed EN AW-7075 shows comparable mechanical properties to PBF processed EN AW-7075.

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Hybrid Manufacturing: Influence of Directed Energy Deposition Parameters on Microstructure and Layer Adhesion of Stainless Steel 316L

10.31399/asm.cp.ht2019p0018 ◽

2019 ◽

Author(s):

Jakob D. Hamilton ◽

Samantha Sorondo ◽

Andrew Greeley ◽

Bruce E. Kahn ◽

Patricia Cyr ◽

...

Keyword(s):

Mechanical Properties ◽

Stainless Steel ◽

Laser Power ◽

Energy Deposition ◽

Scanning Speed ◽

Hybrid Manufacturing ◽

Stainless Steel 316L ◽

Directed Energy Deposition ◽

Deposition Parameters ◽

Directed Energy

Abstract In-envelope hybrid manufacturing systems comprised of directed energy deposition (DED) and machining provide flexibility for the fabrication of complex geometries with minimal setup changes. However, for these manufacturing set ups, the effects of deposition parameters such as laser power and scanning speed on the quality of the build remain relatively unexplored. An important aspect for developing components with reliable mechanical properties is a thorough understanding of DED thermodynamics during fabrication. Therefore, DED thermodynamics were defined based on the strengthening properties derived from the thermal gradient (G) and solidification rate (R) of the melt pool. Other factors influencing DED thermodynamics include substrate geometry and surface finish which are expected to affect cooling rates and adhesion, respectively. In this work, stainless steel 316L specimens were fabricated varying laser power intensity, scanning speed, and deposition substrate. The effect of these parameters on the microstructure of the sample components were analyzed. Microstructural evolution at various points within and between layers was studied and correlated to localized hardness. An increase in mechanical properties for fine, equiaxed grains demonstrates the Hall-Petch principle for strengthening of components.

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Effect of Nb addition on the microstructure and mechanical properties of Inconel 718 fabricated by laser directed energy deposition

Materials Characterization ◽

10.1016/j.matchar.2021.111601 ◽

2021 ◽

pp. 111601

Author(s):

Huaqiang Liu ◽

Kai Guo ◽

Jie Sun ◽

Hao Shi

Keyword(s):

Mechanical Properties ◽

Inconel 718 ◽

Energy Deposition ◽

Directed Energy Deposition ◽

Microstructure And Mechanical Properties ◽

Directed Energy ◽

Nb Addition

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Effect of Processing Parameters On Mechanical Properties of Inconel718 Superalloy Fabricated By Direct Energy Deposit

10.21203/rs.3.rs-1148378/v1 ◽

2021 ◽

Author(s):

Tianhao Jia ◽

Bin Zou ◽

Wenbo Liu ◽

Ting Lei ◽

Hongjian Ding

Keyword(s):

Mechanical Properties ◽

Inconel 718 ◽

Laser Power ◽

Scanning Speed ◽

Processing Parameters ◽

Machining Parameters ◽

Remarkable Effect ◽

Energy Deposit ◽

Direct Energy ◽

Forming Angle

Abstract In this study, Inconel718 specimens with good mechanical properties were prepared by direct energy deposit (DED) with different laser processing parameters. The mechanical properties of Inconel718 samples fabricated by laser direct energy deposit method without heat treatment were measured. The fractures and metallographic structures of prepared Inconel718 were observed, and the mechanism of the effect of diverse machining parameters on mechanical properties of Inconel718 was analyzed from the micro level. The results showed the microstructures of depositions of Inconel 718 specimens prepared by DED were compact with fine grains and anisotropic microstructures, where macroscopic defects were barely seen. The mechanical properties and microstructures of Inconel718 were influenced by processing parameters, among which the forming angle and laser power had the most remarkable effect. According to the experimental data, it could be observed that the Inconel718 specimens prepared by DED had the best performance under the circumstance of 1400W laser power, 1.0mm layer thickness, 600mm/min scanning speed, 1.3mm hatch spacing, and 90° forming angle, whose ultimate tensile strength (UTS) and macro hardness were 1016.10MPa and 36.2HRC respectively. The UTS of Inconel 718 manufactured by DED was close to that of Inconel718 prepared by traditional forging, and even it had higher hardness.

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