Cooling Process for Directional Solidification in Directed Energy Deposition

2018 ◽  
Author(s):  
Keiya Ishiyama ◽  
Ryo Koike ◽  
Yasuhiro Kakinuma ◽  
Tetsuya Suzuki ◽  
Takanori Mori
Keyword(s):  
Directional Solidification ◽  
Thermal Gradient ◽  
Large Scale ◽  
Energy Deposition ◽  
Production Efficiency ◽  
Production Costs ◽  
Special Structure ◽  
Mechanical Stiffness ◽  
Directed Energy Deposition ◽  
Directed Energy

Additive manufacturing (AM) for metals has attracted attention from industry because of its great potential to enhance production efficiency and reduce production costs. Directed energy deposition (DED) is a metal AM process suitable to produce large-scale freeform metal products. DED entails irradiating the baseplate with a laser beam and launching the metal powder onto the molten spot to produce a metal part on the baseplate. Because the process enables powder from different materials to be used, DED is widely applicable to valuable production work such as for a dissimilar material joint, a graded material, or a part with a special structure. With regard to parts with a special structure, directional solidification can prospectively be used in the power plant and aerospace industries because it can enhance the stiffness in a specific direction via only a simple process. However, conventional approaches for directional solidification require a special mold in order to realize a long-lasting thermal gradient in the part. On the other hand, from the viewpoint of thermal distribution in a produced part, DED is able to control the gradient by controlling the position of the molten pool, i.e., the position of the laser spot. Moreover, unlike casting, the thermal gradient can be precisely oriented in the expected direction, because the laser supplies heat energy on the regulated spot. In this study, the applicability of DED to directional solidification in Inconel® 625 is theoretically and experimentally evaluated through metal structure observation and Vickers hardness measurements. Furthermore, the effect of two different cooling processes on directional solidification is also considered with the aim of improving the mechanical stiffness of a part produced by DED. The observations and experimental results show that both the cooling methods (baseplate cooling and intermittent treatment with coolant) are able to enhance the hardness while retaining the anisotropy.

Nanomechanical Characterization of Additive Manufactured GRCop-42 Alloy Developed by Directed Energy Deposition Methods

2020 ◽  
Author(s):  
Trupti Suresh ◽  
Scott Landes ◽  
Todd Letcher ◽  
Anamika Prasad ◽  
Paul Gradl ◽  
...  
Keyword(s):  
Energy Deposition ◽  
Mechanical And Thermal Properties ◽  
Rocket Engines ◽  
Mechanical Stiffness ◽  
Surface Profiling ◽  
Directed Energy Deposition ◽  
Heat Treated ◽  
Microstructural Evaluation ◽  
Liquid Rocket ◽  
Directed Energy

Abstract Propulsion applications such as combustion chambers and nozzles for liquid rocket engines require the use of unique materials with superior mechanical and thermal properties. GRCop-42 (Cu-4 wt.% Cr-2 wt.% Nb) is one such candidate material developed by NASA and is now being manufactured using additive manufacturing (AM) techniques. AM offers a unique processing environment different from traditional metal fabrication processes. This study characterized the mechanical and structural properties of as-deposited and heat-treated GRCop-42 manufactured with Blown Powder Directed Energy Deposition (BPD) based on preliminary testing. The materials were characterized using several techniques including surface profiling by laser microscopy, mechanical stiffness by instrumented indentation, crystal structure, residual stress measurements using XRD and residual XRD, and chemical composition and microstructural evaluation using SEM with EBSD. The results of the study are compared using the BPD techniques for samples in the as-deposited and heat-treated conditions.

scholarly journals Correction to: Characterization and Optimization of Process Parameters for Directed Energy Deposition Powder-Fed Laser System

2021 ◽  
Author(s):  
Daniel Andres Rojas Perilla ◽  
Johan Grass Nuñez ◽  
German Alberto Barragan De Los Rios ◽  
Fabio Edson Mariani ◽  
Reginaldo Teixeira Coelho
Keyword(s):  
Process Parameters ◽  
Energy Deposition ◽  
Laser System ◽  
Directed Energy Deposition ◽  
Optimization Of Process Parameters ◽  
Directed Energy

scholarly journals Hot-Wire Laser-Directed Energy Deposition: Process Characteristics and Benefits of Resistive Pre-Heating of the Feedstock Wire

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 634
Author(s):  
Agnieszka Kisielewicz ◽  
Karthikeyan Thalavai Pandian ◽  
Daniel Sthen ◽  
Petter Hagqvist ◽  
Maria Asuncion Valiente Bermejo ◽  
...  
Keyword(s):  
Heat Input ◽  
Energy Deposition ◽  
Fine Tuning ◽  
Hot Wire ◽  
Process Stability ◽  
Electrical Signals ◽  
Melt Pool ◽  
Directed Energy Deposition ◽  
Directed Energy ◽  
The Stability

This study investigates the influence of resistive pre-heating of the feedstock wire (here called hot-wire) on the stability of laser-directed energy deposition of Duplex stainless steel. Data acquired online during depositions as well as metallographic investigations revealed the process characteristic and its stability window. The online data, such as electrical signals in the pre-heating circuit and images captured from side-view of the process interaction zone gave insight on the metal transfer between the molten wire and the melt pool. The results show that the characteristics of the process, like laser-wire and wire-melt pool interaction, vary depending on the level of the wire pre-heating. In addition, application of two independent energy sources, laser beam and electrical power, allows fine-tuning of the heat input and increases penetration depth, with little influence on the height and width of the beads. This allows for better process stability as well as elimination of lack of fusion defects. Electrical signals measured in the hot-wire circuit indicate the process stability such that the resistive pre-heating can be used for in-process monitoring. The conclusion is that the resistive pre-heating gives additional means for controlling the stability and the heat input of the laser-directed energy deposition.

High productivity fluence based control of Directed Energy Deposition (DED) part geometry

2021 ◽  
Vol 65 ◽  
pp. 407-417
Author(s):  
Geng Li ◽  
Kyle Odum ◽  
Curtis Yau ◽  
Masakazu Soshi ◽  
Kazuo Yamazaki
Keyword(s):  
Energy Deposition ◽  
High Productivity ◽  
Part Geometry ◽  
Directed Energy Deposition ◽  
Directed Energy
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