Effect of Mean Grain Size in the Time of Flight for Lcr Waves

2012 ◽  
Author(s):  
Alexandre Aparecido Buenos ◽  
Auteliano Antunes dos Santos ◽  
Paulo Pereira ◽  
Cleudiane Soares Santos
Keyword(s):  
Grain Size ◽  
Time Of Flight ◽  
Heat Treating ◽  
Ultrasonic Methods ◽  
Mean Grain Size ◽  
Bulk Waves ◽  
Different Temperatures ◽  
A36 Steel ◽  
The Mean ◽  
Austenitic Grain Size

The ultrasonic methods are widely used for evaluation of materials for its inexpensive and practical features. Among the largely used ultrasonic methods is the Critically Refracted Longitudinal Waves (Lcr), which applies longitudinal bulk waves travelling right below the surface, parallel to it. The method can be used to measure stresses near the surface through acoustoelasticity. However, the materials microstructure directly influences the propagation of these waves. The mean grain size is one of the factors that affect the wave speed. The purpose of this paper is to evaluate the effect of mean austenitic grain size in the time of flight (TOF) of Lcr wave. Samples (CDPs) of ASTM A36 steel were manufactured with dimensions of 5/8″ × 6″ × 12″. These were submitted to heat treating at the different temperatures ranges and cooled in air to generate different grain sizes. The results were compared to the grain size estimated in the literature and obtained from optical microscopy. The study showed a clear dependence of TOF on mean austenitic grain size for ASTM A36 steel. Such effect has to be studied to allow stress measurements with Lcr waves.

scholarly journals Preparation of high-entropy carbides by different sintering techniques

2021 ◽  
Vol 56 (19) ◽  
pp. 11237-11247 ◽  
Author(s):  
Johannes Pötschke ◽  
Manisha Dahal ◽  
Mathias Herrmann ◽  
Anne Vornberger ◽  
Björn Matthey ◽  
...  
Keyword(s):  
Grain Size ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Vacuum Sintering ◽  
X Ray ◽  
High Entropy ◽  
Mean Grain Size ◽  
The Mean ◽  
Gas Pressure Sintering ◽  
Hardness Values

AbstractDense (Hf, Ta, Nb, Ti, V)C- and (Ta, Nb, Ti, V, W)C-based high-entropy carbides (HEC) were produced by three different sintering techniques: gas pressure sintering/sinter–HIP at 1900 °C and 100 bar Ar, vacuum sintering at 2250 °C and 0.001 bar as well as SPS/FAST at 2000 °C and 60 MPa pressure. The relative density varied from 97.9 to 100%, with SPS producing 100% dense samples with both compositions. Grain size measurements showed that the substitution of Hf with W leads to an increase in the mean grain size of 5–10 times the size of the (Hf, Ta, Nb, Ti, V,)C samples. Vacuum-sintered samples showed uniform grain size distribution regardless of composition. EDS mapping revealed the formation of a solid solution with no intermetallic phases or element clustering. X-ray diffraction analysis showed the structure of mostly single-phase cubic high-entropy carbides. Hardness measurements revealed that (Hf, Ta, Nb, Ti, V)C samples possess higher hardness values than (Ta, Nb, Ti, V, W)C samples.

scholarly journals Fabrication of (SiC-AlN)/ZrB2 Composite with Nano-Micron Hybrid Microstructure via PCS-Derived Ceramics Route

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 334
Author(s):  
Aidong Xia ◽  
Jie Yin ◽  
Xiao Chen ◽  
Zhengren Huang ◽  
Xuejian Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Raw Materials ◽  
Secondary Phase ◽  
Pressing Temperature ◽  
Xrd Pattern ◽  
Mean Grain Size ◽  
The Mean

In this work, a (SiC-AlN)/ZrB2 composite with outstanding mechanical properties was prepared by using polymer-derived ceramics (PDCs) and hot-pressing technique. Flexural strength reached up to 460 ± 41 MPa, while AlN and ZrB2 contents were 10 wt%, and 15 wt%, respectively, under a hot-pressing temperature of 2000 °C. XRD pattern-evidenced SiC generated by pyrolysis of polycarbosilane (PCS) was mainly composed by 2H-SiC and 4H-SiC, both belonging to α-SiC. Micron-level ZrB2 secondary phase was observed inside the (SiC-AlN)/ZrB2 composite, while the mean grain size (MGS) of SiC-AlN matrix was approximately 97 nm. This unique nano-micron hybrid microstructure enhanced the mechanical properties. The present investigation provided a feasible tactic for strengthening ceramics from PDCs raw materials.

The Study on the Fabrication of Nano-Structured Steel by Cold Rolling and Annealing of Martensite

2013 ◽  
Vol 634-638 ◽  
pp. 1807-1810
Author(s):  
Guang Xu ◽  
Jing Yang ◽  
Tao Xiong ◽  
Peng Deng ◽  
Long Fei Cao
Keyword(s):  
Grain Size ◽  
Cold Rolling ◽  
High Strength ◽  
Total Elongation ◽  
Plain Carbon Steel ◽  
Mean Grain Size ◽  
Cold Rolling And Annealing ◽  
The Mean ◽  
Martensite Microstructure ◽  
Very High

Sub-nano structured steel was obtained by cold rolling and annealing martensite microstructure for a plain carbon steel. The mean grain size is several hundreds nanometer. The steel has very high strength and also good total elongation.

scholarly journals Paleolimnology of Lake Yamanaka as reflected on particle-size distribution

1970 ◽  
Vol 14 ◽  
pp. 35-42 ◽  
Author(s):  
Danda Pani Adhikari
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Size Distribution ◽  
Central Japan ◽  
Size Frequency Distribution ◽  
Factors Affecting ◽  
Mean Grain Size ◽  
The Mean ◽  
Main Factors ◽  
Lake Size

A 17.63 m long bore-hole core extracted from the deepest part of Lake Yamanaka, one of the Fuji-five Lakes at the northeasternfoot of Mount Fuji, central Japan, composed of sediment with intercalations of scoria fallout deposits. The sediment of the upper11.4 m was investigated for grain-size distribution by using a laser diffraction particle size analyser. The mean grain-size profileshowed various degrees of fluctuations, both short-and long-terms, and the size-frequency distribution revealed unimodal-trimodalmixing of sediments. Changes in lake size and water depth appear to be the main factors affecting the variability in the grain-sizedistribution and properties. The lake level appears low during 7000–5000 cal BP and 2800–1150 cal BP and relatively high during5000–2800 cal BP and 1150 cal BP– present.DOI: http://dx.doi.org/10.3126/bdg.v14i0.5437Bulletin of the Department of Geology Vol.14 2011, pp.35-42 

Microstructure and Mechanical Performance of AZ31-1.7 Wt.% Si Alloy Processed by Cyclic Channel Die Compression

2010 ◽  
Vol 667-669 ◽  
pp. 457-461
Author(s):  
Wei Guo ◽  
Qu Dong Wang ◽  
Man Ping Liu ◽  
Tao Peng ◽  
Xin Tao Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Mechanical Performance ◽  
Chinese Script ◽  
Cast State ◽  
Microstructure And Mechanical Properties ◽  
Mean Grain Size ◽  
The Matrix ◽  
The Mean

Cyclic channel die compression (CCDC) of AZ31-1.7 wt.% Si alloy was performed up to 5 passes at 623 K in order to investigate the microstructure and mechanical properties of compressed alloys. The results show that multi-pass CCDC is very effective to refine the matrix grain and Mg2Si phases. After the alloy is processed for 5 passes, the mean grain size decreases from 300 μm of as-cast to 8 μm. Both dendritic and Chinese script type Mg2Si phases break into small polygonal pieces and distribute uniformly in the matrix. The tensile strength increases prominently from 118 MPa to 216 MPa, whereas the hardness of alloy deformed 5 passes only increase by 8.4% compared with as-cast state.

Evaluation of Static Liquefaction Characteristics of Saturated Loose Sand Through the Mean Grain Size and Extreme Grain Sizes

2017 ◽  
Vol 35 (5) ◽  
pp. 2079-2105 ◽  
Author(s):  
Leila Hazout ◽  
Zein El-Abidine Zitouni ◽  
Mostefa Belkhatir ◽  
Tom Schanz
Keyword(s):  
Grain Size ◽  
Loose Sand ◽  
Grain Sizes ◽  
Static Liquefaction ◽  
Mean Grain Size ◽  
The Mean

Magnetite/Nickel andMagnetite/Cobalt Multilayer Nanostructures Obtained by Pulsed Laser Deposition

2003 ◽  
Vol 777 ◽  
Author(s):  
Monica Sorescu ◽  
Agnieszka Grabias ◽  
Lucian Diamandescu
Keyword(s):  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
X Ray Diffraction ◽  
Multilayer Nanostructures ◽  
Mean Grain Size ◽  
Different Temperatures ◽  
The Mean ◽  
Metal Layers ◽  
Magnetite Phase

AbstractNanostructured magnetite/T multilayers, with T = Ni, Co, Cr, have been prepared by pulsed laser deposition. The thickness of individual magnetite and metal layers takes values in the range of 5 - 40 nm with a total multilayer thickness of 100 -120 nm. X-ray diffraction has been used to study the phase characteristics as a function of thermal treatment up to 550 °C. Small amounts of maghemite and hematite were identified together with prevailing magnetite phase after treatments at different temperatures. The mean grain size of magnetite phase increases with temperature from 12 nm at room temperature to 54 nm at 550 °C. The thermal behavior of magnetite in multilayers in comparison with powder magnetite is discussed.

Simulation of Fabrication for Single-Phase Al2O3 Ceramic Tool Materials at Different Fabrication Temperature

2010 ◽  
Vol 150-151 ◽  
pp. 1358-1363
Author(s):  
Bin Fang ◽  
Chuan Zhen Huang ◽  
Chong Hai Xu ◽  
Sheng Sun
Keyword(s):  
Mechanical Properties ◽  
Computer Simulation ◽  
Grain Size ◽  
Monte Carlo ◽  
Single Phase ◽  
Two Dimensional ◽  
Ceramic Tool ◽  
Tool Materials ◽  
Mean Grain Size ◽  
The Mean

The fabrication is a key process for the preparation of ceramic tool materials, which governs the mechanical properties of ceramic tool materials under the condition of the same compositions. A computer simulation coupled with fabrication temperature for the hot-pressing process of single-phase ceramic tool materials has been developed using a two-dimensional hexagon lattice model mapped from the realistic microstructure without considering the presence of pores. The fabrication of single-phase Al2O3 is simulated. The mean grain size of simulated microstructure by Monte Carlo Potts model integrated with fabrication temperature increases with an increase in fabrication temperature, which is consistent with the experiment results.

Synthesis and Dispersity of YBCO Powder Produced by Oxalic Acid Precipitation Method

2015 ◽  
Vol 645-646 ◽  
pp. 145-150 ◽  
Author(s):  
Ai Qin Wang ◽  
Hui Hui Han ◽  
Min Li ◽  
Jing Pei Xie ◽  
Qing Jie Wu ◽  
...  
Keyword(s):  
Grain Size ◽  
Oxalic Acid ◽  
Technological Parameter ◽  
Oxalic Acid Solution ◽  
Acid Precipitation ◽  
Precipitation Method ◽  
Test Results ◽  
Ph Values ◽  
Mean Grain Size ◽  
The Mean

The YBCO powder was prepared by oxalic acid precipitation method and consequent annealing. The correlation between pH values of oxalic acid solution and the precipitation percentage of precursors were analysed based on thermodynamics analysis. The differential scanning calorimetryanalysis (DSC) was used to confirm the synthetic technological parameter. The phases of powder in each process were investigated by XRD. The microstructures of each powder were tested by SEM and TEM. The mean grain size was calculated by the scherrer’s equation. The test results indicated that the YBCO powder with high purity, less impurities, smaller particle, but severe agglomeration, was Y123 when annealing at 900°C. However, adding dispersants could effectively solve the severe agglomeration. The size of YBCO particles was nanosized and coincided with the calculation.

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