Study on the element segregation and Laves phase formation in the laser metal deposited IN718 superalloy by flat top laser and gaussian distribution laser

Chen, Yuan; Yi, Guo; Xu, Mengjia; Ma, Chunfei; Zhang, Qunli; Wang, Liang; Yao, Jianhua; Li, Zhuguo

doi:10.1016/j.msea.2019.03.096

Cited by 130 publications

(29 citation statements)

References 35 publications

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“…It is apparent from Figure 8a-c that the top regions have higher segregation of such Nb-rich eutectic phases compared to other regions, which was confirmed by the area fraction analyses as shown in Figure 8e. The modelling work performed by Nie et al [27] provides insight into the expected cooling rates along the height of the bead and consequently the variation in secondary dendrite arm spacing for Alloy 718. conditions, leading to higher inter-dendritic spacing and precipitation of more Nb-rich phases [25,28]. It is apparent from Figure 8a-c that the top regions have higher segregation of such Nb-rich eutectic phases compared to other regions, which was confirmed by the area fraction analyses as shown in Figure 8e.…”

Section: Nb-rich Eutectic Phasessupporting

confidence: 59%

“…The EDS point analyses revealed that the white particulates were indeed Nb-rich precipitates as shown in Figure 8d, for which the elemental analysis is tabulated in Table 4. Along the height of the deposit further away from the substrate, the segregation was higher and the cooling rates also decreased due to limited heat flux conditions, leading to higher inter-dendritic spacing and precipitation of more Nb-rich phases [25,28]. It is apparent from Figure 8a-c that the top regions have higher segregation of such Nb-rich eutectic phases compared to other regions, which was confirmed by the area fraction analyses as shown in Figure 8e.…”

Section: Nb-rich Eutectic Phasessupporting

confidence: 56%

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Effect of Direct Energy Deposition Process Parameters on Single-Track Deposits of Alloy 718

Sreekanth

Ghassemali

Hurtig

et al. 2020

Metals

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The effect of three important process parameters, namely laser power, scanning speed and laser stand-off distance on the deposit geometry, microstructure and segregation characteristics in direct energy deposited alloy 718 specimens has been studied. Laser power and laser stand-off distance were found to notably affect the width and depth of the deposit, while the scanning speed influenced the deposit height. An increase in specific energy conditions (between 0.5 J/mm2 and 1.0 J/mm2) increased the total area of deposit yielding varied grain morphologies and precipitation behaviors which were comprehensively analyzed. A deposit comprising three distinct zones, namely the top, middle and bottom regions, categorized based on the distinct microstructural features formed on account of variation in local solidification conditions. Nb-rich eutectics preferentially segregated in the top region of the deposit (5.4–9.6% area fraction, Af) which predominantly consisted of an equiaxed grain structure, as compared to the middle (1.5–5.7% Af) and the bottom regions (2.6–4.5% Af), where columnar dendritic morphology was observed. High scan speed was more effective in reducing the area fraction of Nb-rich phases in the top and middle regions of the deposit. The <100> crystallographic direction was observed to be the preferred growth direction of columnar grains while equiaxed grains had a random orientation.

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Section: Nb-rich Eutectic Phasessupporting

confidence: 59%

Section: Nb-rich Eutectic Phasessupporting

confidence: 56%

Effect of Direct Energy Deposition Process Parameters on Single-Track Deposits of Alloy 718

Sreekanth

Ghassemali

Hurtig

et al. 2020

Metals

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“…Niobium is one of the elements present in IN718 and it is highly prone to segregation and tends to form some undesirable phases such as the δ and the Laves phases, which is known for degrading tensile ductility, fatigue and creep rupture properties [124][125][126]. High concentration of niobium has been reported by other researchers which catalyse the formation of Laves phase, depleting the strengthening ϒ'' phase.…”

Section: Effects Of Laves Phasesmentioning

confidence: 99%

“…High concentration of niobium has been reported by other researchers which catalyse the formation of Laves phase, depleting the strengthening ϒ'' phase. The Laves phase provides crack initiation and propagation sites during the melting of the metal powder [125] and is a general observation when IN718 alloy undergoes a process in a high temperature environment [127] such as heat treatment [61,128,129] or during the powder deposition of the AM process [66,109,130].…”

Section: Effects Of Laves Phasesmentioning

confidence: 99%

A Critical Review of the Material Characteristics of Additive Manufactured IN718 for High Temperature Application

Yong¹,

Gibbons²,

West³

2020

Preprint

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This paper reviews state of the art Additive Manufactured (AM) IN718 alloy intended for high temperature applications. AM processes have been around for decades and have gained traction in the past five years due to the huge economic benefit it brings to manufacturers. It is crucial for the scientific community to look into AM IN718 applicability in order to see a step-change in the production. Microstructural studies reveal that the grain structure plays a significant role in determining the fatigue lifespan of the material. Controlling IN718 respective phases such as the &upsih;’', δ and Laves phase is seen to be crucial. Literature reviews have shown that the mechanical properties of AM IN718 were very close to its wrought counterpart when treated appropriately. Higher homogenization temperature and longer ageing were recommended to dissolve the damaging phases. Various surface enhancement techniques were examined to find out their compatibility to AM IN718 alloy that is intended for high temperature application. Laser shock peening (LSP) technology stands out due to the ability to impart low cold work which helps in containing the beneficial compressive residual stress it brings in high temperature fatigue environment.

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“…Du et al [25] predicted the evolution of the microstructure of Ni-based materials during the multi-track laser melting process. Chen et al [26] studied the phase formation of laves during the laser cladding process using different laser models. Hofman et al [27] established a model for the determination of the clad geometry and dilution in laser cladding.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Thermal Evolution and Solidification Behavior of Laser Cladding AlSiTiNi Composite Coatings

Liu

et al. 2019

Coatings

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In order to better understand how a high energy input and a fast cooling rate affect the geometric morphology and microstructure of laser cladding aluminum composite coatings, a three-dimensional (3D) transient finite element model (FEM) has been established to study the temperature field evolution during laser cladding of AlSiTiNi coatings on a 304 stainless steel substrate. In this model, a planar Gauss heat source and a temperature selection judgment mechanism are used to simulate the melting and solidification process as well as the geometric morphology of the laser cladding coatings. The differences in physical characteristics of the cladding materials before and after melting are considered. The results of thermal simulations, including temperature history, temperature gradient, and solidification rate, of the laser cladding coatings are investigated. Corresponding experiments, conducted using an IPG-YLS-5000 fiber laser, are used to verify the simulation results. The experimental observations agree well with the theoretical predictions, which indicates that the established model is valid.

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Study on the element segregation and Laves phase formation in the laser metal deposited IN718 superalloy by flat top laser and gaussian distribution laser

Cited by 130 publications

References 35 publications

Effect of Direct Energy Deposition Process Parameters on Single-Track Deposits of Alloy 718

Effect of Direct Energy Deposition Process Parameters on Single-Track Deposits of Alloy 718

A Critical Review of the Material Characteristics of Additive Manufactured IN718 for High Temperature Application

Numerical Simulation of Thermal Evolution and Solidification Behavior of Laser Cladding AlSiTiNi Composite Coatings

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