Thermal Behavior and Microstructure Evolution during Laser Deposition with Laser-Engineered Net Shaping: Part II. Experimental Investigation and Discussion

Zheng, Baolong; Zhou, Yizhang; Smugeresky, John E.; Schoenung, Julie M.; Lavernia, Enrique J.

doi:10.1007/s11661-008-9566-6

Cited by 180 publications

(82 citation statements)

References 22 publications

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“…The resulting cooling rates were 6530 K/s, 5980 K/s, and 5560 K/s (6257°C/s, 5707°C/s, and 5287°C/s), respectively. These calculated cooling rates are in good agreement with the specific range of 10 3 to 10 4 K/s for rapid solidification in LENSä process reported by Zheng et al from experimental [39] and computational results. [40,41] The corresponding average minimum grain size was plotted against these three calculated cooling rates, and the results are shown in Figure 11(b).…”

Section: Effect Of Power On Grain Sizesupporting

confidence: 90%

Microstructures and Grain Refinement of Additive-Manufactured Ti-xW Alloys

Mendoza

Samimi

Brice

et al. 2017

Metall Mater Trans A

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It is necessary to better understand the composition-processing-microstructure relationships that exist for materials produced by additive manufacturing. To this end, Laser Engineered Net Shaping (LENSä), a type of additive manufacturing, was used to produce a compositionally graded titanium binary model alloy system (Ti-xW specimen (0 £ x £ 30 wt pct), so that relationships could be made between composition, processing, and the prior beta grain size. Importantly, the thermophysical properties of the Ti-xW, specifically its supercooling parameter (P) and growth restriction factor (Q), are such that grain refinement is expected and was observed. The systematic, combinatorial study of this binary system provides an opportunity to assess the mechanisms by which grain refinement occurs in Ti-based alloys in general, and for additive manufacturing in particular. The operating mechanisms that govern the relationship between composition and grain size are interpreted using a model originally developed for aluminum and magnesium alloys and subsequently applied for titanium alloys. The prior beta grain factor observed and the interpretations of their correlations indicate that tungsten is a good grain refiner and such models are valid to explain the grain-refinement process. By extension, other binary elements or higher order alloy systems with similar thermophysical properties should exhibit similar grain refinement.

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Section: Effect Of Power On Grain Sizesupporting

confidence: 90%

Microstructures and Grain Refinement of Additive-Manufactured Ti-xW Alloys

Mendoza

Samimi

Brice

et al. 2017

Metall Mater Trans A

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“…In the last decades, the research focus has been the optimization of mechanical properties and microstructures of components fabricated by LENS [7][8][9][10][11][12][13][14], and thermal modeling and control over the entire powder deposition process [15][16][17][18][19]. These investigations have provided a clear understanding of the characteristics of LENS and have promoted this technology as a major step towards actual industrial applications.…”

Section: Introductionmentioning

confidence: 99%

Energy Consumption and Saving Analysis for Laser Engineered Net Shaping of Metal Powders

et al. 2016

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Abstract:With the increasing awareness of environmental protection and sustainable manufacturing, the environmental impact of laser additive manufacturing (LAM) technology has been attracting more and more attention. Aiming to quantitatively analyze the energy consumption and extract possible ways to save energy during the LAM process, this investigation studies the effects of input variables including laser power, scanning speed, and powder feed rate on the overall energy consumption during the laser deposition processes. Considering microhardness as a standard quality, the energy consumption of unit deposition volume (ECUDV, in J/mm 3 ) is proposed as a measure for the average applied energy of the fabricated metal part. The potential energy-saving benefits of the ultrasonic vibration-assisted laser engineering net shaping (LENS) process are also examined in this paper. The experimental results suggest that the theoretical and actual values of the energy consumption present different trends along with the same input variables. It is possible to reduce the energy consumption and, at the same time, maintain a good part quality and the optimal combination of the parameters referring to Inconel 718 as a material is laser power of 300 W, scanning speed of 8.47 mm/s and powder feed rate of 4 rpm. When the geometry shaping and microhardness are selected as evaluating criterions, American Iron and Steel Institute (AISI) 4140 powder will cause the largest energy consumption per unit volume. The ultrasonic vibration-assisted LENS process cannot only improve the clad quality, but can also decrease the energy consumption to a considerable extent.

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“…[10] The entire process was carried out in Ar environment to avoid oxidation, and the oxygen level in the glove box was maintained around 5 ppm during deposition. A 316L stainless steel plate was used as the substrate.…”

mentioning

confidence: 99%

“…These nanoprecipitates likely evolved during tempering or aging cycles, which is typically imposed by the inherent cyclic thermal environment during LENS deposition, leading to some solid-state transformations. [10] The mechanical tensile test results of the LENSdeposited IN625 alloy, IN625 + 10 wt pct TiC/Ni MMC, IN625 + 20 wt pct TiC/Ni MMC, and IN625 + 14 wt pct TiC MMC are summarized in Figure 4. Both the yield strength (YS), 560 MPa, and percent elongation (pct EL), 46, of LENS-deposited IN625 alloy are higher than those of conventional wrought IN625 (conventional IN625 at RT: YS is 496 MPa and EL is 38 pct [7] ).…”

mentioning

confidence: 99%

The Influence of Ni-Coated TiC on Laser-Deposited IN625 Metal Matrix Composites

Zheng

Topping

Smugeresky

et al. 2010

Metall Mater Trans A

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IN625 Ni-based metal matrix composites (MMCs) components were deposited using Laser Engineered Net-Shaping (LENS) with Ni-coated and uncoated TiC reinforcement particles to provide insight into the influence of interfaces on MMCs. The microstructures and spatial distribution of TiC particles in the deposited MMCs were characterized, and the mechanical responses were investigated. The results demonstrate that the flowability of the mixed powders, the integrity of the interface between the matrix and the TiC particles, the interaction between the laser beam and the TiC ceramic particles, and the mechanical properties of the LENS-deposited MMCs were all effectively improved by using Ni-coated TiC particles. DOI: 10.1007/s11661-009-0126-5 Ó The Author(s) 2010. This article is published with open access at Springerlink.com Particle-reinforced metallic matrix composites (MMCs) are of interest in many applications due to their multifunctionality, which yields combinations of properties, such as high specific strength, stiffness, and toughness, and a low coefficient of thermal expansion, that are unachievable with conventional materials. [1] Ni-based MMCs with ceramic reinforcements are used in a wide range of industrial operations with cutting, rolling, pelletizing, stamping, piercing, drawing, punching, etc.[2] Various synthesis methods, including casting and powder metallurgy techniques, have been used for conventional manufacturing of MMCs. [3,4] The presence of undesirable interfacial reactions and particle segregation represents two key issues that have limited the use of casting methods, partially due to an extended contact time between ceramic particles and the molten metal and density differences between ceramic and metals. In contrast, whereas conventional powder metallurgical routes avoid the presence of a liquid phase, these are relatively complex processes frequently limited in terms of product geometry. The LENS* process, incorporating features from stereolithography and laser cladding, is a laser-assisted direct metal manufacturing process that provides a pathway to produce net-shaped components from a three-dimensional (3-D) computeraided design file.[5] The primary advantages associated with LENS are the following: a small heat affected zone with high cooling rate resulting in fine microstructures; easy gradient deposition of multiple materials within a single component; and fully dense near-net-shape metal components. However, only spherical powders with diameters of 36 to 150 lm are recommended for use in LENS processing.[6] Thus, optimization of the LENS requires fundamental study of the influence of fine and irregular shaped ceramics particles in the case of MMCs.The strength and stability of the interfacial region between the reinforcement particles and metal matrix govern the mechanical properties of MMCs, and extensive efforts have been devoted to understanding and manipulating the interfacial behavior in MMCs. In the case of metal-ceramic MMCs, it is often desirable to promote wettability while ...

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Thermal Behavior and Microstructure Evolution during Laser Deposition with Laser-Engineered Net Shaping: Part II. Experimental Investigation and Discussion

Cited by 180 publications

References 22 publications

Microstructures and Grain Refinement of Additive-Manufactured Ti-xW Alloys

Microstructures and Grain Refinement of Additive-Manufactured Ti-xW Alloys

Energy Consumption and Saving Analysis for Laser Engineered Net Shaping of Metal Powders

The Influence of Ni-Coated TiC on Laser-Deposited IN625 Metal Matrix Composites

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