Investigation of Remanufacturing Methods Utilizing Mechanically-Generated and Gas-Atomized Feedstock Production for Directed Energy Deposition Processing Through Specific Energy Consumption Modeling

Marcus A. Jackson,Dan J. Thoma,Frank E. Pfefferkorn 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.3

The objective of this work was to assess the energy consumption of a novel remanufacturing method that utilizes mechanically-generated feedstock for directed energy deposition. Gas-atomization is the state-of-the-art production process for directed energy deposition feedstock, and for this work was incorporated into a remanufacturing process path to provide a comparison method. Specific energy consumption models of remanufacturing utilizing both of these proposed process paths were developed and applied to a case study to investigate energy saving opportunities for future manufacturing paradigms. The energy modelling was done in three stages. First, the mechanically-generated feedstock production energy consumption model was generated from experimental observation. Second, the gas-atomized feedstock production energy consumption model was generated from a combination of experimental observation, reported estimates from the manufacturer, and data found in the literature. Lastly, the energy consumption model of directed energy deposition was derived from experimental observation and compares favorably with reported estimates in the literature. With the models, the specific energy consumption in the two process paths were compared and their application was demonstrated by estimating the energy consumption to remanufacture a bracket. The two feedstock production methods had similar specific energy consumptions. The specific energy consumption of the directed energy deposition process was the greatest component in the respective remanufacturing paths by an order of magnitude; increasing deposition rate is the most important factor for lowering the overall specific energy consumption. The analyzed remanufacturing technologies were estimated to consume less energy than replacement when repairing up to approximately 15% of the original part’s mass.

Influences of deposition strategies on thermo-mechanical characteristics of a multilayer part deposited by a wire feeding type DED process

Bih Lii Chua,안동규,김재구 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.12

Variation in process parameters and deposition strategies has produced different thermo-mechanical characteristics in a part fabricated by a wire feeding type directed energy deposition (DED) process. The purpose of this paper is to select a proper deposition strategy to fabricate a straight wall part using a wire feeding type DED process. The deposition strategies include different deposition directions, deposition patterns and interpass time. In order to investigate the influences of deposition strategies on thermo-mechanical characteristics of fabricated part, three-dimensional finite element analyses (FEAs) have been proposed. A volumetric heat flux has been applied to simulate the transient heat transfer phenomena of the DED process. Influences of different deposition strategies on thermo-mechanical characteristics of fabricated part have been discussed. From the result of residual stress distribution, an appropriate deposition strategy has been selected for the multi-layer deposition. Results of FEAs have been verified through comparison of vertical displacements between estimated results from FEAs and those of experiments.

Phenomenological Modeling of Distortions and Residual Stresses in Direct Energy Deposition of AISI M4 High Speed Tool Steel on D2 Substrate

Kyeongsik Ha,Young Hoon Moon,Tae Hwan Kim,Gyeong Yun Baek,Ki Yong Lee,Do-sik Shim,Wookjin Lee 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.5

This study aimed to develop a computational methodology to estimate the residual stress formation behavior followed by direct energy deposition of high-speed tool steel hard materials. First, evolutions of substrate distortions followed by the depositions of AISI M4 tool steel layers were investigated by experiments and the results were analyzed using the elasticity-based Stoney’s approach. The results revealed significant additional distortion caused by the temperature gradient formed when depositing the first M4 layer. Distortions occurring on depositing the second and subsequent M4 layers could be approximated as linearly increasing with the total M4 layer thickness, indicating a stable inherent shrinkage strain for each layer deposition process. It was also clearly revealed that the elastic Stoney’s approach is not capable of predicting the residual stress in the studied direct energy deposition system as significant plastic deformations are expected to occur. Based on the experimental observations, a phenomenological finite element (FE) model was developed considering the elastoplastic behavior of materials. The FE simulation results showed very good agreement with the experimentally measured distortions during the M4 deposition process in a wide range of deposition areas and thicknesses. Thus, the proposed model can be used effectively for controlling the distortions and analyzing residual stress evolutions during hard-facing or repairing processes using direct energy deposition.

Single Scans of Ti‑6Al‑4V by Directed Energy Deposition: A Cost and Time Effective Methodology to Assess the Proper Process Window

Alessandro Carrozza,Federico Mazzucato,Alberta Aversa,Mariangela Lombardi,Federica Bondioli,Sara Biamino,Anna Valente,Paolo Fino 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9

Directed energy deposition is an additive manufacturing technology which usually relies on prototype machines or hybridsystems, assembled with parts from different producers. Because of this lack of standardization, the optimization of the processparameters is often a mandatory step in order to develop an efficient building process. Although, this preliminary phaseis usually expensive both in terms of time and cost. The single scan approach allows to drastically reduce deposition time andmaterial usage, as in fact only a stripe per parameters combination is deposited. These specimens can then be investigated,for example in terms of geometrical features (e.g. growth, width) and microstructure to assess the most suitable processwindow. In this work, Ti-6Al-4V single scans, produced by means of directed energy deposition, corresponding to a total of50 different parameters combinations, were analyzed, focusing on several geometrical features and relative parameters correlations. Moreover, considering the susceptibility of the material to oxygen pick-up, the necessity of an additional shieldinggas system was also evaluated, by comparing the specimens obtained with and without using a supplementary argon flow. A process window, which varies according to the user needs, was found together with a relationship between microstructureand process parameters, in both shielding scenarios.

에너지 밀도 및 분말 증착 밀도를 고려한 직접 에너지 증착법 기반 Ti-6Al-4V 합금의 적층공정 최적화

이유경,김은성,천세호,설재복,성효경,오정석,김형섭,이태경,남태현,김정기 한국분말재료학회(구 한국분말야금학회) 2021 한국분말재료학회지 (KPMI) Vol.28 No.6

The process optimization of directed energy deposition (DED) has become imperative in the manufacture of reliable products. However, an energy-density-based approach without a sufficient powder feed rate hinders the attainment of an appropriate processing window for DED-processed materials. Optimizing the processing of DEDprocessed Ti-6Al- 4V alloys using energy per unit area (Eeff) and powder deposition density (PDDeff) as parameters helps overcome this problem in the present work. The experimental results show a lack of fusion, complete melting, and overmelting regions, which can be differentiated using energy per unit mass as a measure. Moreover, the optimized processing window (Eeff = 44~47 J/mm2 and PDDeff = 0.002~0.0025 g/mm2) is located within the complete melting region. This result shows that the Eeff and PDDeff-based processing optimization methodology is effective for estimating the properties of DED-processed materials.

에너지 제어 용착을 이용한 스테인리스 316L의 적층 특성 및 기계적 물성 평가

양승원(Seung-weon Yang),이협(Hyub Lee),심도식(Do-Sik Shim) 한국기계가공학회 2021 한국기계가공학회지 Vol.20 No.6

Directed energy deposition (DED) is an additive manufacturing technology involving a focused high-power laser or electron beam propagating over the substrate, resulting in melt pool formation while simultaneously supplying metal powder to the melt pool area to deposit the material. DED is performed to repair and strengthen parts in various applications, as it can be easily integrate local area cladding and cross-material deposition. In this study, we characterize stainless steel 316 L parts fabricated via DED based on various deposition conditions and geometries to widen the application of DED. The deposition characteristics are investigated by varying the laser power and powder feed rate. Multilayer deposition with a laser power of 362 W and a powder feed rate of 6.61 g/min indicate a height closest to the design value while affording high surface quality. The microhardness of the specimen increases from the top to the bottom of the deposited area. Tensile tests of specimens with two different deposition directions indicate that horizontally long specimens with respect to a substrate demonstrate a higher ultimate tensile strength and yield strength than vertically long specimens with lower elongation.

Adhesion with Aluminum for Material Surfaces Additively Manufactured by Directed Energy Deposition

Ju‑Young Jeong,Hyun‑Sung Kang,Su‑Ho Kim,Ki‑Yong Lee,Dong‑Ju Kim,Dosik Shim 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.6

The adhesion of aluminum to molds or tools is common during the production of aluminum alloy products for vehicle light weighting. It reduces the productivity and quality, and thus, it needs to be prevented. This study attempted to use directed energy deposition (DED) to deposit a heterogeneous material on the surface of a mold material to prevent the aluminum adhesion. The powders used in the heterogeneous material deposition included the Fe-based alloys D2 and H13, Ni-based alloy Inconel718, and Co-based alloy Stellite21. Immersion tests and wear tests were performed to test the deposits’ reactivity with aluminum. After the immersion of deposited samples into melted aluminum, the smallest amount of adhesion was observed on the D2 surface. The H13-deposited zone had the highest value of hardness. However, the hardness of the deposited surface did not display a close relationship with aluminum adhesion. In addition, the H13- and Stellite21-deposited zones displayed high thermal conductivity compared with the other two specimens. The microimages and elemental analyses revealed that the adhesion was formed owing to metallurgical fusion. During the wear tests, the temperature increased owing to the friction between the aluminum pins and deposited specimens. Stellite21 and H13 produced a smaller temperature increase than Inconel718 and D2. From the wear test, it was observed that the aluminum pin material adhered to the wear specimen surface for the D2-, H13- and Inconel718-deposited specimens. Thick aluminum adhesion layers were formed in the case of the D2 and Inconel718 specimens. Nevertheless, aluminum adhesion could not be observed on the Stellite21 specimen’s surface, whereas typical wear scars caused by wearing were apparent. It can be concluded that adhesion with aluminum varies according to the alloy elements contained in the metal alloy as well as the thermal conductivity of the deposited materials.

기계 부품 재제조를 위한 DED 공정 조건에 따른 적층 및 잔류응력 특성 분석

김단아,이광규,안동규 한국소성∙가공학회 2021 소성가공 : 한국소성가공학회지 Vol.30 No.3

Recently, there has been an increased interest in the remanufacturing of mechanical parts using metal additive manufacturing processes in regards to resource recycling and carbon neutrality. DED (directed energy deposition) process can create desired metallic shapes on both even and uneven substrate via line-by-line deposition. Hence, DED process is very useful for the repair, retrofit and remanufacturing of mechanical parts with irregular damages. The objective of the current paper is to investigate the effects DED process parameters, including the effects of power and the scan speed of the laser, on deposition and residual stress characteristics for remanufacturing of mechanical parts using experiments and finite element analyses (FEAs). AISI 1045 is used as the substrate material and the feeding powder. The characteristic dimensions of the bead shape and the heat affected zone (HAZ) for different deposition conditions are obtained from the experimental results. Efficiencies of the heat flux model for different deposition conditions are estimated by the comparison of the results of FEAs with those of experiments in terms of the width and the depth of HAZ. In addition, the influence of the process parameters on residual stress distributions in the vicinity of the deposited region is investigated using the results of FEAs. Finally, a suitable deposition condition is predicted in regards to the bead formation and the residual stress.

PBF (Powder Bed Fusion)와 DED (Directed Energy Deposition)의 연속 공정으로 적층제조된 630 스테인레스강의 마모 거동에 관한 연구

김태건,신광용,이기용,심도식 한국정밀공학회 2023 한국정밀공학회지 Vol.40 No.6

Hybrid additive manufacturing (AM) refers to a combination of two metal AM techniques: material deposition by powder bed fusion (PBF) and additional building by directed energy deposition (DED). This study focused on differentcharacteristics in accordance with relative deposition directions of PBF and DED during hybrid AM production. Characteristics of the sample fabricated by hybrid AM (i.e., hybrid sample) were compared with those of the samplefabricated by PBF or DED. Ferrite was dominant in the microstructure of PBF deposits with very fine retained austenite observed locally. In contrast, lath martensite and retained austenite were formed uniformly in the microstructure of DED deposits. Different microstructures in the two processes were attributed to differences of cooling rate. In DED deposits, microhardness was significantly decreased owing to a high retained austenite fraction. However, in the hybrid sample, microhardness was rapidly increased in the HAZ owing to aging heat treatment for long-term deposition. Principal wear mechanisms of PBF and DED samples were oxidative wear and plastic deformation, respectively.

DED 공정의 다중 비드 적층 시 비정상 열전달 특성 분석

이광규(Kwang Kyu Lee),안동규(Dong Gyu Ahn) 대한기계학회 2021 大韓機械學會論文集A Vol.45 No.4

이 연구에서는 DED 공정을 이용하여 S45C 구조용 강 위 Inconel 625 및 Stellite 21 초합금 다중비드 적층 시 발생하는 열전달 특성을 3차원 비선형 유한요소 해석을 통해 고찰하고자 한다. 실험 결과를 이용하여 비드간 거리와 오버랩이 고려된 유한요소 해석 모델을 개발하였다. 열원은 가우시안 분포를 가지는 체적 열원 모델을 사용하였다. 열손실은 대류 및 복사 조건이 동시에 고려된 온도의존 등가열손실 모델을 활용하였다. 단일 비드 적층 해석을 통하여 재료에 따른 열원 효율을 도출하였다. 이열비드 적층 해석에서는 적층 간 시간과 적층 방향에 따른 열전달 특성 변화를 분석하였다. 최종적으로 평면 및 다층 적층 해석을 통해 적층 중 발생하는 열전달 특성 및 온도 이력 변화를 고찰하였다. The goal of this study is to investigate transient heat transfer during Inconel 625 and Stellite 21 multi-bead deposition on S45C structural steel using a directed energy deposition (DED) process. Using experimental results, a finite element (FE) model, considering the hatch distance and overlap, is developed to analyze three-dimensional transient heat transfer characteristics. A volumetric heat flux with a gaussian distribution and an equivalent heat loss model, including temperature dependent convection and irradiation, are used. The efficiencies of heat flux for different deposition materials are estimated through an FE analysis (FEA) for single line bead. The influence of the interpass time and the deposition direction on the formation of heat affected zone (HAZ) is examined through FEAs for double bead deposition. Finally, the variation of temperature distributions and thermal histories during multi-lines and multi-layers deposition is investigated.