scholarly journals Effect of Ti Content on the Behavior of Primary Carbides in H13 Ingots

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 837
Author(s):  
Yu Huang ◽  
Guoguang Cheng ◽  
Meiting Zhu
Keyword(s):  
Three Dimensional ◽  
Dendritic Structure ◽  
Primary Carbide ◽  
Number Density ◽  
Binding Ability ◽  
Electrolysis Method ◽  
C And N ◽  
Primary Carbides ◽  
Ti Content ◽  
Large Primary

The Ti element plays a role in pinning grain boundaries but also has a good binding ability to C and N, forming large primary carbides. Therefore, the effect of Ti content on primary carbides’ behavior in H13 ingots was comprehensively studied. A non-aqueous electrolysis method was used to determine the three-dimensional (3D) characteristics of primary carbides. We found a great difference between the two-dimensional (2D) and the three-dimensional characteristics of primary carbides. When performing 2D analyses, the density of the primary carbides appeared high, while their size was small. The actual characteristics of primary carbides can be obtained only by 3D observation. The primary carbide showed a typical dendritic structure, whose center consisted of Ti–V-rich carbide wrapped by V-rich carbide. As the Ti content increased, the size of the primary carbide increased from 24.9 μm to 41.3 μm, and the number density increases from 25.6 per/mm2 to 43.9 per/mm2. The Ti4C2S2 phase precipitated first, then changed into Ti–V-rich carbide, and finally further partly transformed into V-rich carbide. The addition of elemental Ti promoted the precipitation and transformation of primary carbides, resulting in an increase of the number density and size.

The Effects of Quenching and Tempering Treatment on the Hardness and Microstructures of a Cold Work Steel

2019 ◽  
Vol 4 (1) ◽  
pp. 286-294
Author(s):  
László Tóth ◽  
Réka Fábián
Keyword(s):  
Heat Treatment ◽  
Retained Austenite ◽  
Elevated Temperatures ◽  
Cryogenic Treatment ◽  
Cold Work ◽  
Chromium Steel ◽  
Primary Carbide ◽  
Tempering Temperature ◽  
Tempering Treatment ◽  
Primary Carbides

The X153CrMoV12 ledeburitic chromium steel characteristically has high abrasive wear resistance, due to their high carbon and high chromium contents with a large volume of carbides in the microstructure. This steel quality has high compression strength, excellent deep hardenability and toughness properties, dimensional stability during heat treatment, high resistance to softening at elevated temperatures. The higher hardness of cryogenic treated samples in comparison with conventional quenched samples mean lower quantity of retained austenite as at samples quenched to room temperature and tempered in similar condition. In the microstructure of samples were observed that the primary carbide did not dissolve at 1070°C and their net structure have not been changed during to heat treatment. During to tempering at high temperature the primary carbides have become more and more rounded. After low tempering temperature in martensite were observed some small rounded carbides also, increasing the tempering temperature the quantity of finely dispersed carbides increased, which result higher hardness. The important issues in heat treatment of this steels are the reduction or elimination of retained austenite due to cryogenic treatment.

scholarly journals Effect of Ti(C, N) Particle on the Impact Toughness of B-Microalloyed Steel

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 868 ◽  
Author(s):  
Yu Huang ◽  
Guo-Guang Cheng ◽  
Shi-Jian Li ◽  
Wei-Xing Dai ◽  
You Xie
Keyword(s):  
Impact Toughness ◽  
Microalloyed Steel ◽  
Fracture Initiation ◽  
Sem Analysis ◽  
Number Density ◽  
Size Number ◽  
Microalloying Elements ◽  
The Impact ◽  
Ti Content ◽  
Scanning Electron

Simultaneously improving the toughness and strength of B-microalloyed steel by adding microalloying elements (Nb, V, Ti) has been an extensively usedmethod for researchers. However, coarse Ti(C, N) particle will precipitate during solidification with inappropriate Ti content addition, resulting in poor impact toughness. The effect of the size, number density, and location of Ti(C, N) particle on the impact toughness of B-microalloyed steel with various Ti/N ratios was investigated. Coarse Ti(C, N) particles were investigated to act as the cleavage fracture initiation sites, by using scanning electron microscopy (SEM) analysis. When more coarse Ti(C, N) inclusions were located in ferrite instead of pearlite, the impact toughness of steel with ferrite–pearlite microstructure was lower. Meanwhile, when the size or the number density of Ti(C, N) inclusions was larger, the impact toughness was adversely affected. Normalizing treatment helps to improve the impact property of B-microalloyed steel, owing to the location of Ti(C, N) particles being partly changed from ferrite to pearlite. The formation mechanism of coarse Ti(C, N) particles was calculated by the thermodynamic software Factsage 7.1 and Thermo-Calc. The Ti(C, N) particles formed during the solidification of molten steel, and the N-rich Ti(C, N) phase precipitated first and, then, followed by the C-rich Ti(C, N) phase. Decreasing the Ti and N content is an effective way to inhibit the formation of coarse Ti(C, N) inclusions.

scholarly journals Solar wind control of plasma number density in the near-Earth plasma sheet: three-dimensional structure

2008 ◽  
Vol 26 (12) ◽  
pp. 4031-4049 ◽  
Author(s):  
D. Nagata ◽  
S. Machida ◽  
S. Ohtani ◽  
Y. Saito ◽  
T. Mukai
Keyword(s):  
Solar Wind ◽  
Density Dependence ◽  
High Latitude ◽  
Plasma Sheet ◽  
Strong Dependence ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Lower Latitude ◽  
Number Density ◽  
Three Dimensional Structure

Abstract. The plasma number density in the near-Earth plasma sheet depends on the solar wind number density and the north-south component of interplanetary magnetic field (IMF Bz) with time lag and duration of several hours. We examined the three-dimensional structure of such dependences by fitting observations of plasma sheet and solar wind to an empirical model equation. Analyses were conducted separately for northward and southward IMF conditions. Effects of solar wind speed and IMF orientation were also examined by further subdivision of the dataset. Based on obtained results, we discuss (i) the relative contribution of the ionosphere and solar wind to plasma sheet mass supply, (ii) the entry mechanisms for magnetosheath particles, and (iii) the plasma transport in the plasma sheet. We found that solar wind number density dependence is weaker and IMF Bz dependence is stronger for faster solar wind with southward IMF, which suggests the contribution of ionospheric particles. Further from the Earth, different interplanetary conditions result in different structures of solar wind dependence, which indicate different solar wind entry mechanisms: (1) southward IMF results in a strong dependence on solar wind number density in the flank high-latitude region, (2) slow solar wind with northward IMF leads to lower-latitude peaks of solar wind number density dependence in the flank region, (3) fast solar wind with northward IMF results in a strong dependence on solar wind number density at the down-tail dusk flank equator, and (4) solar wind number density dependence is stronger in the downstream of quasi-parallel bow shock. These features are attributable to (1) low-latitude dayside reconnection entry, (2) high-latitude dayside reconnection entry, (3) entry due to decay of Kelvin-Helmholtz vortices, and (4) diffusive entry mediated by kinetic Alfven waves, respectively. Effect of IMF Bz and its time lags show plasma sheet reconfiguration associated with enhanced convective transport under southward IMF. Duration of IMF Bz effect under northward IMF is interpreted in terms of turbulent diffusive transport.

scholarly journals Inclusion Characteristics in 95CrMo Steels with Different Calcium and Sulfur Contents

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 619 ◽  
Author(s):  
Xiang Li ◽  
Xiao Long ◽  
Linzhu Wang ◽  
Shouhao Tong ◽  
Xiutao Wang ◽  
...  
Keyword(s):  
Outer Layer ◽  
Three Dimensional ◽  
Average Diameter ◽  
Inclusion Size ◽  
Number Density ◽  
Cooling Process ◽  
Oxide Inclusions ◽  
Industrial Experiments ◽  
Size Number

In order to study the effect of Ca and sulfur contents on the characteristics of inclusions, industrial experiments using 95CrMo steel were conducted. SEM-EDS detections and stereological analysis were used to probe the characteristics of inclusions, including their compositions, morphologies, size, number density, and distribution. The results indicate that there were mainly three types of inclusions in 95CrMo steel billets with 6–18 ppm Ca and 30–100 ppm S: inclusions with single-phased morphology mainly composed of oxides; isolated MnS/CaS-only inclusions; inclusions with multi-phased morphology. The three-dimensional inclusion size distribution suggests that there were more Type-1 inclusions with a small size in low S containing steels. The average diameter of all types of inclusions increased with increasing Ca or S content in 95CrMo steel, indicating that the formation of MnS and CaS coarsened their size. The density distribution of inclusions indicates that the more inclusions there are, the more easily they aggregate and collide. Moreover, it is presumably concluded that the formation of sulfide in the outer layer of oxide inclusions weaken the attraction between oxide inclusions. The equilibrated transformation and formation of inclusions during the cooling process of 95CrMo steel was discussed based on thermodynamic calculation. The equilibrated transformation trajectory of inclusions in 95CrMo steel during the cooling process was Ca2SiO4 + MgO → Ca3MgSi2O8 → Spinel + CaS, which was corresponding to the detected results. The precipitation regular of sulfide was obtained. The formation mechanism for three types of inclusions was discussed.

scholarly journals ShuTu: Open-Source Software for Efficient and Accurate Reconstruction of Dendritic Morphology

2017 ◽  
Author(s):  
Dezhe Z. Jin ◽  
Ting Zhao ◽  
David L. Hunt ◽  
Rachel P. Tillage ◽  
Ching-Lung Hsu ◽  
...  
Keyword(s):  
Software Package ◽  
Three Dimensional ◽  
Dendritic Structure ◽  
Dendritic Tree ◽  
Structural Data ◽  
Computer Models ◽  
Dendritic Morphology ◽  
Automated Identification ◽  
Action Potential Firing ◽  
Potential Firing

AbstractNeurons perform computations by integrating inputs from thousands of synapses – mostly in the dendritic tree – to drive action potential firing in the axon. One fruitful approach to understanding this process is to record from neurons using patch-clamp electrodes, fill the recorded neuron with a substance that allows subsequent staining, reconstruct the three-dimensional architecture of the dendrites, and use the resulting functional and structural data to develop computer models of dendritic integration. Accurately producing quantitative reconstructions of dendrites is typically a tedious process taking many hours of manual inspection and measurement. Here we present ShuTu, a new software package that facilitates accurate and efficient reconstruction of dendrites imaged using bright-field microscopy. The program operates in two steps: (1) automated identification of dendritic process, and (2) manual correction of errors in the automated reconstruction. This approach allows neurons with complex dendritic morphologies to be reconstructed rapidly and efficiently, thus facilitating the use of computer models to study dendritic structure-function relationships and the computations performed by single neurons.Significance StatementWe developed a software package – ShuTu – that integrates automated reconstruction of stained neurons with manual error correction. This package facilitates rapid reconstruction of the three-dimensional geometry of neuronal dendritic trees, often needed for computational simulations of the functional properties of these structures.

scholarly journals Influence of the Decelerator Grid on the Optical Performance of the Ion Thruster

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Chang Lu ◽  
Yide Zhao ◽  
Jie Wan ◽  
Yuchuan Chu ◽  
Liang Zheng ◽  
...  
Keyword(s):  
Previous Experiment ◽  
Three Dimensional ◽  
Great Influence ◽  
Optical Performance ◽  
Number Density ◽  
Ion Thruster ◽  
Immersed Finite Element Method ◽  
Particle In Cell ◽  
Immersed Finite Element ◽  
Simulation Results

In order to reduce the erosion of the ion thruster accelerator grid, which is caused by charge-exchange (CEX) ions, the 2-grid optical system is added to a decelerator grid to block the reflux CEX ions. The previous experiment and simulation results have proven that the decelerator grid can effectively reduce the Pit and Groove erosion. However, the influence of the decelerator grid on the optical performance has not yet been studied well. In this paper, a three-dimensional Immersed Finite Element Method-Particle in Cell-Monte Carlo Collision (IFE-PIC-MCC) algorithm was adopted to investigate the effect of the decelerator grid on the optical performance under crossover and normal circumstances. Results show that the decelerator grid has no effect on the focusing state and the distribution of beam ions. It also has little effect on the CEX ions from the upstream and extraction (center) regions. However, it has great influence on the downstream CEX ions. When the upstream plasma number density is small, the decelerator grid will cause most of the downstream reflux CEX ions to impinge on the accelerator grid aperture barrel, resulting in the significant increase of the Barrel erosion of the accelerator grid. With the increase of the upstream plasma number density, the downstream reflux CEX ions tend to impact the downstream surface of the decelerator grid, which means the decelerator grid begins to block the downstream backflow of CEX ions.

Mechanical Properties and Structure of Laser Beam and Wide Gap Brazed Joints Produced Using Mar M247–Amdry DF3 Powders

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Alexandre Gontcharov ◽  
Yuan Tian ◽  
Paul Lowden ◽  
Mathieu Brochu
Keyword(s):  
Mechanical Properties ◽  
Laser Beam ◽  
Three Dimensional ◽  
Dendritic Structure ◽  
Gamma Prime ◽  
High Gamma ◽  
Weld Properties ◽  
Bulk Chemical ◽  
Brazed Joints ◽  
Wide Gap

The microstructure and mechanical properties of materials produced by wide gap brazing (WGB) and laser beam (LBW) cladding with different blends of Mar M247 and Amdry DF-3 brazing powders were studied. It was shown that LBW Mar M247-based materials comprised of 0.6 to 1 wt % B were weldable. The weld properties were superior to WGB deposits with the same bulk chemical composition, due to the formation of a dendritic structure typical for welded joints, and the precipitation of cuboidal borides of Cr, Mo, and W in the ductile Ni–Cr based matrix. Both materials were found to have useful properties for three-dimensional (3D) additive manufacturing (AM) and repair components manufactured from high gamma prime precipitation hardened superalloys.

Stability of Computational Algorithms Used in Molecular Dynamics Simulations

1995 ◽  
Vol 117 (3) ◽  
pp. 531-534 ◽  
Author(s):  
Akira Satoh
Keyword(s):  
Transport Coefficients ◽  
Three Dimensional ◽  
Divergence Time ◽  
Linear Functions ◽  
Time Interval ◽  
Thermodynamic Quantities ◽  
Number Density ◽  
Time Intervals ◽  
Dynamics Simulations ◽  
The Relationship

The present study focuses on a three-dimensional Lennard-Jones system in a thermodynamic equilibrium in order to discuss divergence processes, the relationship between time intervals and divergence times, and the influence of time intervals on thermodynamic quantities and transport coefficients under various number density and temperature. It is found that the velocities of molecules in a system gradually increase with time until the system suddenly diverges exponentially. The time interval-divergence time relationship can be expressed in approximate terms as linear functions if the data are plotted on logarithmic scales, and the system diverges more easily as temperature or number density increases. Thermodynamic quantities show the influence of large time intervals more clearly than do transport coefficients.

Gigacycle Fatigue Response of PM versus Ingot Metallurgy Tool Steels

2011 ◽  
Vol 672 ◽  
pp. 23-30 ◽  
Author(s):  
Herbert Danninger ◽  
Christian Sohar ◽  
Christian Gierl Mayer ◽  
Agnieszka Betzwar-Kotas ◽  
Brigitte Weiss
Keyword(s):  
Tool Steel ◽  
High Speed ◽  
Cold Work ◽  
Ingot Metallurgy ◽  
Tool Steels ◽  
Endurance Strength ◽  
Steel Grades ◽  
Primary Carbides ◽  
Effect Of The Composition ◽  
Large Primary

In this work, the gigacycle fatigue response of several tool steel grades has been studied using an ultrasonic resonance testing device. It showed that both with ingot metallurgy (IM) and powder metallurgy (PM) tool steels, a true fatigue limit does not exist up to 10E10 cycles. PM steels resulted in significantly higher endurance strength levels than IM grades. However, there was virtually no effect of the composition and hardness of the materials, both for PM and IM grades cold work tool steels and high speed steels exhibiting virtually the same S-N curves. In the IM tool steel grades, crack initiation started at large primary carbides or carbide clusters, while in the PM grades, nonmetallic inclusions were the critical sites. In any case it is very important to avoid introducing residual stresses into the specimen surfaces during preparation, which would markedly shift the endurance strength levels.

scholarly journals Mammalian spermatozoa and cumulus cells bind to a 3D model generated by recombinant zona pellucida protein-coated beads

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Julieta Gabriela Hamze ◽  
Analuce Canha-Gouveia ◽  
Blanca Algarra ◽  
María José Gómez-Torres ◽  
María Concepción Olivares ◽  
...  
Keyword(s):  
Zona Pellucida ◽  
Molecular Mechanisms ◽  
3D Model ◽  
Mammalian Species ◽  
Three Dimensional ◽  
Cumulus Cells ◽  
Mammalian Sperm ◽  
Gamete Recognition ◽  
Specific Proteins ◽  
C And N

AbstractThe egg is a spherical cell encapsulated by the zona pellucida (ZP) which forms a filamentous matrix composed of several glycoproteins that mediate gamete recognition at fertilization. Studies on molecular mechanisms of sperm-egg binding are limited in many mammalian species by the scarcity of eggs, by ethical concerns in harvesting eggs, and by the high cost of producing genetically modified animals. To address these limitations, we have reproduced a three-dimensional (3D) model mimicking the oocyte’s shape, by means of magnetic sepharose beads coated with recombinant ZP glycoproteins (BZP) and cumulus cells. Three preparations composed of either ZP2 (C and N-termini; BZP2), ZP3 (BZP3) or ZP4 (BZP4) were obtained and characterized by protein SDS-PAGE, immunoblot and imaging with confocal and electron microscopy. The functionality of the model was validated by adhesion of cumulus cells, the ability of the glycoprotein-beads to support spermatozoa binding and induce acrosome exocytosis. Thus, our findings document that ZP-beads provide a novel 3D tool to investigate the role of specific proteins on egg-sperm interactions becoming a relevant tool as a diagnostic predictor of mammalian sperm function once transferred to the industry.

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