Experimental Studies on Laser Additive Manufacturing of Inconel-625 Structures Using Powder Bed Fusion at 100 µm Layer Thickness

Abstract Laser Additive Manufacturing using Powder Bed Fusion (LAM-PBF) is one of the revolutionary technologies playing a key role in fourth industrial revolution for redefining manufacturing from mass production to mass customization. To upkeep the pace, Raja Ramanna Centre for Advanced Technology (RRCAT) has indigenously developed an LAM-PBF system and it is being used for process and component development for various engineering applications. This paper reports a parametric investigation to evaluate the influence of process parameters on the sample properties and to develop the process window for fabricating complex shaped engineering components. In the present work, an experimental investigation is carried out to investigate the effect of Laser Energy density (LED) on the porosity, microstructure and mechanical properties of SS 316L bulk structures fabricated by LAM-PBF system. LED is a combined parameter simultaneously considering the effect of Laser Power (P), Scan Speed (v), hatch spacing (h) and layer thickness (t). The effect of three LED values such as 83.33 J/mm3, 253.97 J/mm3 and 476.19 J/mm3 is investigated in the present work by building cuboidal samples at a layer thickness of 75 microns. Porosity is estimated using area fraction method in optical microscopy and it is found that the minimum porosity of 0.14 % and pore area of 1.28 mm2 are observed at 253.97 J/mm3. Maximum porosity of 18.85 % is observed at 83 J/mm3 due to incomplete fusion defects. However, porosity observed at 475 J/mm3 is 6.56 % with average pore size of 17.8 mm2. Microstructural studies show primarily columnar growth in all the samples with fine dendrites. The dendrite size is observed to be 3.2 μm, 2.4 μm and 1.46 μm at 83.33 J/mm3, 253.97 J/mm3 and 476.19 J/mm3 respectively. Micro-hardness and single cycle automatic ball indentation studies are found to be in agreement with dendritic size, with lower hardness at larger dendrite size. X-Ray Diffraction (XRD) studies indicate similar peaks at all the conditions, with slight peak shift observed with increase in LED primarily due to higher amount of residual stress. Thus, it can be inferred that LED of 253.97 J/mm3 is suitable for fabricating engineering components due to combination of lower porosity and fine dendritic structure.

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Formation of the Ni3Nb δ-Phase in Stress-Relieved Inconel 625 Produced via Laser Powder-Bed Fusion Additive Manufacturing

Metallurgical and Materials Transactions A ◽

10.1007/s11661-017-4304-6 ◽

2017 ◽

Vol 48 (11) ◽

pp. 5547-5558 ◽

Cited By ~ 54

Author(s):

Eric A. Lass ◽

Mark R. Stoudt ◽

Maureen E. Williams ◽

Michael B. Katz ◽

Lyle E. Levine ◽

...

Keyword(s):

Additive Manufacturing ◽

Inconel 625 ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Δ Phase

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On the Hot Isostatic Pressing of Inconel 625 Structures built using Laser Powder Bed Fusion at Higher Layer Thickness

10.21203/rs.3.rs-982054/v1 ◽

2021 ◽

Author(s):

Saurav Kumar Nayak ◽

Arackal Narayanan Jinoop ◽

Christ Prakash Paul ◽

Vesangi Anil Kumar ◽

Dineshraj Subburaj ◽

...

Keyword(s):

Layer Thickness ◽

Volume Fraction ◽

Hot Isostatic Pressing ◽

Microstructural Analysis ◽

Inconel 625 ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Isostatic Pressing ◽

Elemental Segregation

Abstract This paper reports the effect of Hot Isostatic Pressing (HIPing) on the porosity, microstructure and mechanical properties of Laser Powder Bed Fusion (LPBF) IN625 structures built at a higher layer thickness of 100 µm. It is observed that the process-induced pores/voids of volume fraction (Vf) 0.43% in as-built IN625 structures are reduced significantly to ~ 0.01% after HIPing treatment. The microstructure is changed from fine columnar dendrites to coarse equiaxed dendrites. The microstructural analysis of as-built structures reveals the presence of cellular/ dendritic growth along with elemental segregation of Nb, Si and C and precipitation of Nb-rich carbides. Whereas, coarse recrystallized microstructure along with elemental segregation of Si and precipitation of Nb, Mo and Cr rich carbides are observed in Hot Isostatic Pressed (HIPed) samples. HIPed structures exhibit lower tensile s trength, higher ductility, and lower anisotropy as compared to LPBF built structures. There is a reduction in the Vickers micro-hardness of IN625 samples after HIPing and the values are observed to be similar to their conventional counterparts. Further, an increase in the energy storage capacity of the material is observed after HIPing treatment through Automated Ball Indentation (ABI®) studies. The study paves a way to develop ~100% dense, defect-free and isotropic engineering components using LPBF.

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Insights on Laser Additive Manufacturing of Invar 36

Advances in Civil and Industrial Engineering - Additive Manufacturing Applications for Metals and Composites ◽

10.4018/978-1-7998-4054-1.ch004 ◽

2020 ◽

pp. 71-93

Author(s):

Mostafa Yakout ◽

M. A. Elbestawi

Keyword(s):

Mechanical Properties ◽

Thermal Expansion ◽

Additive Manufacturing ◽

Coefficient Of Thermal Expansion ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Laser Additive Manufacturing ◽

Powder Bed ◽

Iron Nickel ◽

Am Processes

Recently, additive manufacturing (AM) became a promising technology to manufacture complex structures with acceptable mechanical properties. The laser powder-bed fusion (L-PBF) process is one of the most common AM processes that has been used for producing a wide variety of metals and composites. Invar 36 is an austenite iron-nickel alloy that has a very low coefficient of thermal expansion; therefore, it is a good candidate for the L-PBF process. This chapter covers the state-of-the-art for producing Invar 36 using the L-PBF process. The chapter aims at describing research insights of using metal AM techniques in producing Invar 36 components. Like most of nickel-based alloys, Invar 36 is weldable but hard-to-machine. However, there are some challenges while processing these alloys by laser. This chapter also covers the challenges of using the L-PBF process for producing nickel-based alloys. In addition, it reports the L-PBF conditions that could be used to produce fully dense Invar 36 components with mechanical properties comparable to the wrought Invar 36.

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On the measurement of effective powder layer thickness in laser powder-bed fusion additive manufacturing of metals

Progress in Additive Manufacturing ◽

10.1007/s40964-018-0064-0 ◽

2018 ◽

Vol 4 (2) ◽

pp. 109-116 ◽

Cited By ~ 9

Author(s):

Yahya Mahmoodkhani ◽

Usman Ali ◽

Shahriar Imani Shahabad ◽

Adhitan Rani Kasinathan ◽

Reza Esmaeilizadeh ◽

...

Keyword(s):

Additive Manufacturing ◽

Layer Thickness ◽

Powder Layer ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed

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Additive Manufacturing and Hot-fire Testing of Bimetallic GRCop-84 and C-18150 Channel-Cooled Combustion Chambers Using Powder Bed Fusion and Inconel 625 Hybrid Directed Energy Deposition

AIAA Propulsion and Energy 2019 Forum ◽

10.2514/6.2019-4390 ◽

2019 ◽

Author(s):

Paul R. Gradl ◽

Christopher S. Protz ◽

Kevin Zagorski ◽

Vishal Doshi ◽

Hannah McCallum

Keyword(s):

Additive Manufacturing ◽

Energy Deposition ◽

Inconel 625 ◽

Powder Bed Fusion ◽

Fire Testing ◽

Combustion Chambers ◽

Powder Bed ◽

Directed Energy Deposition ◽

Directed Energy

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Simulation Study of Hatch Spacing and Layer Thickness Effects on Microstructure in Laser Powder Bed Fusion Additive Manufacturing using a Texture-Aware Solidification Potts Model

Journal of Materials Engineering and Performance ◽

10.1007/s11665-021-06110-7 ◽

2021 ◽

Author(s):

Joseph Pauza ◽

Anthony Rollett

Keyword(s):

Additive Manufacturing ◽

Layer Thickness ◽

Potts Model ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Microstructure Control ◽

Powder Bed ◽

Laser Parameters ◽

Link Type ◽

Hatch Spacing

AbstractMicrostructure control in the laser powder bed fusion additive manufacturing processes is a topic of major interest because of the submillimeter length scale at which the manufacturing process occurs. The ability to control the process at the melt pool scale allows for microstructure control that few other manufacturing techniques can match. The majority of work on microstructure control has focused on altering laser parameters to control solidification conditions (Ref (R.R. Dehoff, M.M. Kirka, W.J. Sames, H. Bilheux, A.S. Tremsin, L.E. Lowe, and S.S. Babu, Site Specific Control of Crystallographic Grain Orientation through Electron Beam Additive Manufacturing, Mater. Sci. Technol., 2014, 31(8), p 931–938. R. Shi, S.A. Khairallah, T.T. Roehling, T.W. Heo, J.T. McKeown, and M.J. Matthews, Microstructural Control in Metal Laser Powder Bed Fusion Additive Manufacturing Using Laser Beam Shaping Strategy, Acta Mater., 2020, 184, p 284–305, https://doi.org/10.1016/j.actamat.2019.11.053.)). Other machine parameters, besides the laser parameters, have also been shown to affect the microstructure of AM parts (Ref (N. Nadammal, S. Cabeza, T. Mishurova, T. Thiede, A. Kromm, C. Seyfert, L. Farahbod, C. Haberland, J.A. Schneider, P.D. Portella, and G. Bruno, Effect of Hatch Length on the Development of Microstructure, Texture and Residual Stresses in Selective Laser Melted Superalloy Inconel 718, Mater. Des., 2017, 134, p 139–150, https://doi.org/10.1016/j.matdes.2017.08.049. F. Geiger, K. Kunze, and T. Etter, Tailoring the Texture of IN738LC Processed by Selective Laser Melting (SLM) by Specific Scanning Strategies, Mater. Sci. Eng. A, 2016, 661, p 240–246, https://doi.org/10.1016/j.msea.2016.03.036.)). We propose an investigation of the effects of hatch spacing and layer thickness on microstructure development in laser powder bed fusion additive manufacturing. A Monte Carlo Potts model with textured solidification capabilities is used to study the effects of these parameters on a unidirectional scan strategy. The simulation results reveal substantial changes in grain morphology as well as texture. Additionally, EVP-FFT crystal plasticity simulations were performed to evaluate the effect of the microstructural shifts on mechanical response. The conclusions from this work elucidate the effects of these parameters on part microstructure as predicted by the texture-aware solidification Potts model and inform understanding of how bulk texture is predicted by the simulation approach.

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