Influence of Smoke on Metallographic Structure of Short Circuited Melted Mark

2012 ◽  
Vol 591-593 ◽  
pp. 945-948 ◽  
Author(s):  
Lian Tie Wang ◽  
Wei Gao
Keyword(s):  
Grain Size ◽  
Carbon Content ◽  
Oxygen Content ◽  
Grain Shape ◽  
Short Circuit ◽  
Element Distribution ◽  
Gas Composition ◽  
Metallographic Structure ◽  
Smoke Particles ◽  
Normal Environment

When fire breaks out, the gas composition and concentration as well as smoke concentration of burning part vary from those in normal environment. The gas and smoke absorbed during solidification of short circuited melted mark occurred in such environment will certainly have an effect on grain shape, grain size, holes distribution and impurity element distribution of organization of melted mark. The gas in the environment has a certain influence on the organization of short circuited melted mark, but the influence is smaller than that of smoke. The reason may be that the gas is mingled with certain amount of tiny smoke particles inevitably which play a role in the solidification of melted mark. Compared with short-circuit samples in normal atmosphere, carbon content of short-circuit samples increases and oxygen content decreases in the environment of smoke.

Statistical Assessment of the Effects of Grain-Structure Representation and Micro-Properties on the Behavior of Bonded Block Models for Brittle Rock Damage Prediction

2021 ◽  
Vol 13 (14) ◽  
pp. 7889
Author(s):  
Carlos Efrain Contreras Inga ◽  
Gabriel Walton ◽  
Elizabeth Holley
Keyword(s):  
Grain Size ◽  
Grain Shape ◽  
Grain Structure ◽  
Minor Effect ◽  
Unique Contribution ◽  
Structure Generation ◽  
Structure Representation ◽  
The Real ◽  
Study Results ◽  
Block Models

The ability to predict the mechanical behavior of brittle rocks using bonded block models (BBM) depends on the accuracy of the geometrical representation of the grain-structure and the applied micro-properties. This paper evaluates the capabilities of BBMs for predictive purposes using an approach that employs published micro-properties in combination with a Voronoi BBM that properly approximates the real rock grain-structure. The Wausau granite, with Unconfined Compressive Strength (UCS) of 226 MPa and average grain diameter of 2 mm, is used to evaluate the effectiveness of the predictive approach. Four published sets of micro-properties calibrated for granites with similar mineralogy to the Wausau granite are used for the assessment. The effect of grain-structure representation in Voronoi BBMs is analyzed, considering grain shape, grain size and mineral arrangement. A unique contribution of this work is the explicit consideration of the effect of stochastic grain-structure generation on the obtained results. The study results show that the macro-properties of a rock can be closely replicated using the proposed approach. When using this approach, the micro-properties have a greater impact on the realism of the predictions than the specific grain-structure representation. The grain shape and grain size representations have a minor effect on the predictions for cases that do not deviate substantially from the real average grain geometry. However, the stochastic effect introduced by the use of randomly-generated Voronoi grain-structures can be significant, and this effect should be considered in future studies.

Effects of oxygen content on microstructure and impact toughness of high heat input flux-cored wire weld metals

2018 ◽  
Vol 115 (4) ◽  
pp. 410
Author(s):  
Fengyu Song ◽  
Yanmei Li ◽  
Ping Wang ◽  
Fuxian Zhu
Keyword(s):  
Grain Size ◽  
Impact Toughness ◽  
Weld Metal ◽  
Oxygen Content ◽  
Heat Input ◽  
High Heat ◽  
Cored Wire ◽  
Weld Metals ◽  
High Heat Input ◽  
The Impact

Three weld metals with different oxygen contents were developed. The influence of oxygen contents on the microstructure and impact toughness of weld metal was investigated through high heat input welding tests. The results showed that a large number of fine inclusions were formed and distributed randomly in the weld metal with oxygen content of 500 ppm under the heat input condition of 341 kJ/cm. Substantial cross interlocked acicular ferritic grains were induced to generate in the vicinity of the inclusions, primarily leading to the high impact toughness at low temperature for the weld metal. With the increase of oxygen content, the number of fine inclusions distributed in the weld metal increased and the grain size of intragranular acicular ferrites decreased, which enhanced the impact toughness of the weld metal. Nevertheless, a further increase of oxygen content would contribute to a great diminution of the austenitic grain size. Following that the fraction of grain boundary and the start temperature of transformation increased, which facilitated the abundant formation of pro-eutectoid ferrites and resulted in a deteriorative impact toughness of the weld metal.

Effects of grain size and grain shape in granular flow simulations

2014 ◽  
pp. 1453-1458
Author(s):  
S Moriguchi ◽  
K Terada ◽  
J Kato ◽  
S Takase ◽  
T Kyoya
Keyword(s):  
Grain Size ◽  
Granular Flow ◽  
Grain Shape ◽  
Flow Simulations

scholarly journals The Effect of Lath Martensite Microstructures on the Strength of Medium-Carbon Low-Alloy Steel

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 232 ◽  
Author(s):  
Chen Sun ◽  
Paixian Fu ◽  
Hongwei Liu ◽  
Hanghang Liu ◽  
Ningyu Du ◽  
...  
Keyword(s):  
Grain Size ◽  
Carbon Content ◽  
Lath Martensite ◽  
Block Size ◽  
Martensitic Steels ◽  
Austenite Grain Size ◽  
Medium Carbon ◽  
Transmission Electron ◽  
Lath Width ◽  
Effective Grain Size

Different austenitizing temperatures were used to obtain medium-carbon low-alloy (MCLA) martensitic steels with different lath martensite microstructures. The hierarchical microstructures of lath martensite were investigated by optical microscopy (OM), electron backscattering diffraction (EBSD), and transmission electron microscopy (TEM). The results show that with increasing the austenitizing temperature, the prior austenite grain size and block size increased, while the lath width decreased. Further, the yield strength and tensile strength increased due to the enhancement of the grain boundary strengthening. The fitting results reveal that only the relationship between lath width and strength followed the Hall–Petch formula of. Hence, we propose that lath width acts as the effective grain size (EGS) of strength in MCLA steel. In addition, the carbon content had a significant effect on the EGS of martensitic strength. In steels with lower carbon content, block size acted as the EGS, while, in steels with higher carbon content, the EGS changed to lath width. The effect of the Cottrell atmosphere around boundaries may be responsible for this change.

Forskolin-induced HCO3- current across apical membrane of the frog corneal epithelium

1990 ◽  
Vol 259 (2) ◽  
pp. C215-C223 ◽  
Author(s):  
O. A. Candia
Keyword(s):  
Corneal Epithelium ◽  
Apical Membrane ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Short Circuit Current ◽  
Pump Current ◽  
Gas Composition ◽  
Apical Side ◽  
Disulfonic Stilbene ◽  
Stimulation Of

Forskolin (and other Cl- secretagogues) does not affect the very small Na(+)-originated short-circuit current (Isc) across frog corneal epithelium bathed in Cl- free solutions. However, forskolin in combination with increased PCO2 bubbling of the solutions (5-20% CO2) stimulated Isc proportionally to PCO2 to a maximum of approximately 8 microA/cm2. This current could be eliminated and reinstated by sequentially changing the gas composition of the bubbling to 100% air and 20% CO2-80% air. The same effects were observed when PCO2 changes were limited to the apical-side solution. Stroma-to-tear HCO3- movement was deemed unlikely, since the increase in Isc was observed with a HCO3(-)-free solution on the stromal side and CO2 gassing limited to the tear side. From the effects of ouabain and tryptamine, at least 80% of the Isc across the basolateral membrane can be accounted for by the Na+ pump current plus K+ movement from cell to bath. Methazolamide also inhibited Isc. Current across the apical membrane cannot be attributed to an electronegative Na(+)-HCO3- symport given the insensitivity of Isc to a disulfonic stilbene and the fact that stroma-to-tear Na+ fluxes did not increase on stimulation of Isc. The tear-to-stroma Na+ flux also remained unaltered, negating an increased apical bath-to-cell Na+ flow. The forskolin-20% CO2 manipulation produced a depolarization of the intracellular potential, a reduction in the apical-to-basolateral resistance ratio, and a decrease in transepithelial resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Optical Simulation and Investigation of the Effect of Hysteresis on the Perovskite Solar Cells

NANO ◽  
2019 ◽  
Vol 14 (10) ◽  
pp. 1950127 ◽  
Author(s):  
Farhad Jahantigh ◽  
S. M. Bagher Ghorashi
Keyword(s):  
Grain Size ◽  
Solar Cells ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Perovskite Solar Cells ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Transport Layer

Perovskite solar cells have recently been considered to be an auspicious candidate for the advancement of future photovoltaic research. A power conversion efficiency (PCE) as high as 22% has been reported to be reached, which can be obtained through an inexpensive and high-throughput solution process. Modeling and simulation of these cells can provide deep insights into their fundamental mechanism of performance. In this paper, two different perovskite solar cells are designed by using COMSOL Multiphysics to optimize the thickness of each layer and the overall thickness of the cell. Electric potential, electron and hole concentrations, generation rate, open-circuit voltage, short-circuit current and the output power were calculated. Finally, PCEs of 20.7% and 26.1% were predicted. Afterwards, according to the simulation results, the role of the hole transport layer (HTL) was investigated and the optimum thickness of the perovskite was measured to be 200[Formula: see text]nm for both cells. Therefore, the spin coating settings are selected so that a coating with this thickness for cell 1 is deposited. In order to compare the performance of HTM layer, solar cells with a Spiro-OMeTAD HTM and without the HTM layer in their structure were fabricated. According to the obtained photovoltaic properties, the solar cell made with Spiro-OMeTAD has a more favorable open-circuit voltage ([Formula: see text]), short-circuit current density ([Formula: see text]), fill factor (FF) and PCE compared to the cell without the HTM layer. Also, hysteresis depends strongly on the perovskite grain size, because large average grain size will lead to an increase in the grain’s contact surface area and a decrease in the density of grain boundaries. Finally, according to the results, it was concluded that, in the presence of a hole transport layer, ion transfer was better and ion accumulation was less intense, and therefore, the hysteresis decreases.

Novel OsGRAS19 mutant, D26, positively regulates grain shape in rice (Oryza sativa)

2019 ◽  
Vol 46 (9) ◽  
pp. 857 ◽  
Author(s):  
Zhimin Lin ◽  
Jingwan Yan ◽  
Jun Su ◽  
Huaqing Liu ◽  
Changquan Hu ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Grain Size ◽  
Transcription Factor ◽  
Grain Shape ◽  
Rice Yield ◽  
Reproductive Development ◽  
Cell Number ◽  
Rice Grain ◽  
Regulatory Effect ◽  
Site Mutation

Grain size is an important factor in rice yield. Several genes related to grain size have been reported, but most of them are determined by quantitative trail loci (QTL) traits. Gene D26 is a novel site mutation of OsGRAS19 and involved in the brassinosteroid (BR) signalling pathway. However, whether D26 is involved in the process of rice reproductive development remains unclear. Here, gene cloning and functional analysis revealed that D26 has an obvious regulatory effect on grain size. Overexpression or CRISP/Cas9 mutant of D26 also showed that grain size was positively influenced. Cellular analyses show that D26 modulates grain size by promoting cell division and regulating the cell number in the upper epidermis of the glume. The overexpression results further suggest that the level of D26 expression positively impacts grain length and leaf angles and that the expression of several known grain size genes is involved in the regulation. Based on our results, D26, as a transcription factor, effectively improves rice grain shape.

scholarly journals A Unified Model for Plasticity in Ferritic, Martensitic and Dual-Phase Steels

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 764
Author(s):  
Shuntaro Matsuyama ◽  
Enrique I. Galindo-Nava
Keyword(s):  
Grain Size ◽  
Dislocation Density ◽  
Carbon Content ◽  
Grain Boundaries ◽  
Uniform Elongation ◽  
High Strength Steels ◽  
High Strength ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Dislocation Generation

Unified equations for the relationships among dislocation density, carbon content and grain size in ferritic, martensitic and dual-phase steels are presented. Advanced high-strength steels have been developed to meet targets of improved strength and formability in the automotive industry, where combined properties are achieved by tailoring complex microstructures. Specifically, in dual-phase (DP) steels, martensite with high strength and poor ductility reinforces steel, whereas ferrite with high ductility and low strength maintains steel’s formability. To further optimise DP steel’s performance, detailed understanding is required of how carbon content and initial microstructure affect deformation and damage in multi-phase alloys. Therefore, we derive modified versions of the Kocks–Mecking model describing the evolution of the dislocation density. The coefficient controlling dislocation generation is obtained by estimating the strain increments produced by dislocations pinning at other dislocations, solute atoms and grain boundaries; such increments are obtained by comparing the energy required to form dislocation dipoles, Cottrell atmospheres and pile-ups at grain boundaries, respectively, against the energy required for a dislocation to form and glide. Further analysis is made on how thermal activation affects the efficiency of different obstacles to pin dislocations to obtain the dislocation recovery rate. The results are validated against ferritic, martensitic and dual-phase steels showing good accuracy. The outputs are then employed to suggest optimal carbon and grain size combinations in ferrite and martensite to achieve highest uniform elongation in single- and dual-phase steels. The models are also combined with finite-element simulations to understand the effect of microstructure and composition on plastic localisation at the ferrite/martensite interface to design microstructures in dual-phase steels for improved ductility.

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