Effect of indentation size and grain/sub-grain size on microhardness of high purity tungsten

Liu, Guangyu; Ni, Song; Song, Min

doi:10.1016/s1003-6326(15)63958-9

Cited by 15 publications

(8 citation statements)

References 32 publications

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“…The same results were found for these three samples, with an average of 420 HV and a standard deviation of 13.5. The result is in line with the hardness found by Wen et al [17] and a greater hardness compared to conventional SPS processed Tungsten (in the range of 320 ÷ 400 HV) [18].…”

Section: Selective Laser Melted Tungstensupporting

confidence: 91%

Tungsten Fabricated by Laser Powder Bed Fusion

Rebesan

Bonesso

Gennari

et al. 2021

Berg Huettenmaenn Monatsh

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Additive Manufacturing (AM) is the process that allows the production of complex geometry and lightweight components. Thanks to the high density of refractory metals, AM could be a possible solution for their application in the aerospace field and for biomedical or future nuclear fusion devices. Yet, Laser Powder Bed Fusion (LPBF) of refractory metals as Ta, Mo, and W faces some challenges due to their main properties: high melting point, heat conductivity, and susceptibility to cracks.The purpose of this study is to optimize the process parameters in order to produce high-density Tungsten parts by LPBF on an EOS M100 (maximum power of 170 W). The characterization is performed through physical properties measurements and microstructural analysis. Single Scan Tracks (SSTs) are produced on the top surfaces of Tungsten blocks to evaluate the process parameters that give regular-shape and continuous melt-pools. Both analytical and experimental optimizations of process parameters were performed. Micro-hardness measurements were done for dense bulk specimens. Finally, a description of susceptibility to cracks of additively manufactured Tungsten was performed.

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Section: Selective Laser Melted Tungstensupporting

confidence: 91%

Tungsten Fabricated by Laser Powder Bed Fusion

Rebesan

Bonesso

Gennari

et al. 2021

Berg Huettenmaenn Monatsh

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“…The hardness is maximal for the η 5 specimen, and exceeds 460 HV 0.05 for both η 3 and η 5 specimens. The SLM-processed tungsten specimens show a superior hardness compared with conventional PM or SPS processed tungsten (typically 320–400 HV) [ 39 ]. The reasons are explained below: the residual stresses in SLM layerwise-build parts are quite large, but they are not always disadvantageous.…”

Section: Resultsmentioning

confidence: 99%

Selective laser melting of high-performance pure tungsten: parameter design, densification behavior and mechanical properties

Tan

Zhou

et al. 2018

Science and Technology of Advanced Materials

151

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Selective laser melting (SLM) additive manufacturing of pure tungsten encounters nearly all intractable difficulties of SLM metals fields due to its intrinsic properties. The key factors, including powder characteristics, layer thickness, and laser parameters of SLM high density tungsten are elucidated and discussed in detail. The main parameters were designed from theoretical calculations prior to the SLM process and experimentally optimized. Pure tungsten products with a density of 19.01 g/cm3 (98.50% theoretical density) were produced using SLM with the optimized processing parameters. A high density microstructure is formed without significant balling or macrocracks. The formation mechanisms for pores and the densification behaviors are systematically elucidated. Electron backscattered diffraction analysis confirms that the columnar grains stretch across several layers and parallel to the maximum temperature gradient, which can ensure good bonding between the layers. The mechanical properties of the SLM-produced tungsten are comparable to that produced by the conventional fabrication methods, with hardness values exceeding 460 HV0.05 and an ultimate compressive strength of about 1 GPa. This finding offers new potential applications of refractory metals in additive manufacturing.

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“…From a microstructural point of view, indentation size effect phenomenon is attributed to the evolution of geometrically necessary dislocations (GNDs) beneath the Berkovich indenter. The presence of dislocations caused an increase in the strain gradients, and thus the formation of a plastically deformed zone [22][23][24]. Nix and Gao [22] showed that the density of geometrically necessary dislocations created within the plastic zone bounded by the circle of contact for a conical indenter can be determined based on the indentation depth dependence of the hardness.…”

Section: Geometrically Necessary Dislocation Modelmentioning

confidence: 99%

“…Nix and Gao [22] showed that the density of geometrically necessary dislocations created within the plastic zone bounded by the circle of contact for a conical indenter can be determined based on the indentation depth dependence of the hardness. This model was used to describe the ISE phenomenon in various materials [23][24][25]. The density of the geometrically necessary dislocations increases with the decrease of the indentation depth h. This allows the hardness to be expressed as H 0 , which would be obtained without the presence of the geometrically necessary dislocations, according to the following formula:…”

Section: Geometrically Necessary Dislocation Modelmentioning

confidence: 99%

Effect of Indentation Load on Nanomechanical Properties Measured in a Multiphase Boride Layer

Dziarski¹,

Makuch²

2021

Materials

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The study investigated the dependence of the indentation load on nanomechanical properties for a gas-borided layer produced on Inconel 600-alloy. During the measurements, the indentation load range from 10 mN to 500 mN was used. Three types of tested areas, differing in the concentration of chromium, were examined. The increase in chromium concentration was accompanied by an increase in indentation hardness and Young’s modulus. Simultaneously, the increase in the indentation load resulted in a decrease in the indentation hardness and Young’s modulus, for each type of the tested area. The presence of the indentation size effect was analyzed using four models: Meyer’s law, Hays and Kendall model, Li and Bradt model, Nix and Gao model. For all tested areas, good agreement with the Meyer’s law was obtained. However, areas with a higher chromium concentration were more susceptible to indentation size effect (ISE). The proportional specimen resistance (PSR) model was used to describe the plastic-elastic behavior of the tested materials, as well as to detect the presence of ISE. It was found that the increase in chromium concentration in the tested area was accompanied by a greater tendency to elastic deformation during nanoindentation.

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Effect of indentation size and grain/sub-grain size on microhardness of high purity tungsten

Cited by 15 publications

References 32 publications

Tungsten Fabricated by Laser Powder Bed Fusion

Tungsten Fabricated by Laser Powder Bed Fusion

Selective laser melting of high-performance pure tungsten: parameter design, densification behavior and mechanical properties

Effect of Indentation Load on Nanomechanical Properties Measured in a Multiphase Boride Layer

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