Hot pressing of B{sub 4}C/SiC composites

Energy Technology Data Exchange (ETDEWEB)

Sahin, F.C.; Turhan, E.; Yesilcubuk, S.A.; Addemir, O. [Ystanbul Technical University, Faculty of Chemistry and Metallurgy, Materials and Metallurgical Engineering Dept., Maslak-Ystanbul (Turkey)

2005-07-01

B{sub 4}C/SiC ceramic composites containing 10-20-30 vol % SiC were prepared by hot pressing method. The effect of SiC addition and hot pressing temperature on sintering behaviour and mechanical properties of hot pressed composites were investigated. Microstructures of hot pressed samples were examined by SEM technique. Three different temperatures (2100 deg. C, 2200 deg. C and 2250 deg. C) were used to optimize hot pressing temperature applying 100 MPa pressure under argon atmosphere during the sintering procedure. The highest relative density of 98.44 % was obtained by hot pressing at 2250 deg. C. However, bending strengths of B{sub 4}C/SiC composite samples were lower than monolithic B{sub 4}C in all experimental conditions. (authors)

Heat Treatment Optimization and Properties Correlation for H11-Type Hot-Work Tool Steel

Science.gov (United States)

Podgornik, B.; Puš, G.; Žužek, B.; Leskovšek, V.; Godec, M.

2018-02-01

The aim of this research was to determine the effect of vacuum-heat-treatment process parameters on the material properties and their correlations for low-Si-content AISI H11-type hot-work tool steel using a single Circumferentially Notched and fatigue Pre-cracked Tensile Bar (CNPTB) test specimen. The work was also focused on the potential of the proposed approach for designing advanced tempering diagrams and optimizing the vacuum heat treatment and design of forming tools. The results show that the CNPTB specimen allows a simultaneous determination and correlation of multiple properties for hot-work tool steels, with the compression and bending strength both increasing with hardness, and the strain-hardening exponent and bending strain increasing with the fracture toughness. On the other hand, the best machinability and surface quality of the hardened hot-work tool steel are obtained for hardness values between 46 and 50 HRC and a fracture toughness below 60 MPa√m.

Effect of carbon on mechanical properties of powder-processed Fe ...

Indian Academy of Sciences (India)

The present paper records the results of mechanical tests on iron-phosphorus powder alloys which were made using a hot powder forging technique. In this process mild steel encapsulated powders were hot forged into slabs, hot rolled and annealed to relieve the residual stresses. These alloys were characterized in terms ...

Comparative Evaluations and Microstructure: Mechanical Property Relations of Sintered Silicon Carbide Consolidated by Various Techniques

Science.gov (United States)

Barick, Prasenjit; Chatterjee, Arya; Majumdar, Bhaskar; Saha, Bhaskar Prasad; Mitra, Rahul

2018-04-01

A comparative evaluation between pressureless or self-sintered silicon carbide (SSiC), hot-pressed silicon carbide (HP-SiC), and spark plasma-sintered silicon carbide (SPS-SiC) has been carried out with emphasis on examination of their microstructures and mechanical properties. The effect of sample dimensions on density and properties of SPS-SiC has been also examined. Elastic modulus, flexural strength, and fracture toughness measured by indentation or testing of single-edge notched beam specimens have been found to follow the following trend, HP-SiC > SSiC > SPS-SiC. The SPS-SiC samples have shown size-dependent densification and mechanical properties, with the smaller sample exhibiting superior properties. The mechanical properties of sintered SiC samples appear to be influenced by relative density, grain size, and morphology, as well as the existence of intergranular glassy phase. Studies of fracture surface morphologies have revealed the mechanism of failure to be transgranular in SSiC or HP-SiC, and intergranular in case of SPS-SiC, indicating the dominating influence of grain size and α-SiC formation with high aspect ratio.

Synergetic Effect of Graphene and MWCNTs on Microstructure and Mechanical Properties of Cu/Ti3SiC2/C Nanocomposites

Science.gov (United States)

Jiang, Xiaosong; Song, Tingfeng; Shao, Zhenyi; Liu, Wanxia; Zhu, Degui; Zhu, Minhao

2017-11-01

Multi-walled carbon nanotubes (MWCNTs) and graphenes have been taken for novel reinforcements due to their unique structure and performance. However, MWCNTs or graphenes reinforced copper matrix composites could not catch up with ideal value due to reinforcement dispersion in metal matrix, wettability to metal matrix, and composite material interface. Taking advantage of the superior properties of one-dimensional MWCNTs and two-dimensional graphenes, complementary performance and structure are constructed to create a high contact area between MWCNTs and graphenes to the Cu matrix. Mechanical alloying, hot pressing, and hot isostatic pressing techniques are used to fabricate Cu matrix self-lubricating nanocomposites. Effects of MWCNTs and graphenes on mechanical properties and microstructures of Cu/Ti3SiC2/C nanocomposites are studied. The fracture and strengthening mechanisms of Cu/Ti3SiC2/C nanocomposites are explored on the basis of structure and composition of Cu/Ti3SiC2/C nanocomposites with formation and function of interface.

HotRegion: a database of predicted hot spot clusters.

Science.gov (United States)

Cukuroglu, Engin; Gursoy, Attila; Keskin, Ozlem

2012-01-01

Hot spots are energetically important residues at protein interfaces and they are not randomly distributed across the interface but rather clustered. These clustered hot spots form hot regions. Hot regions are important for the stability of protein complexes, as well as providing specificity to binding sites. We propose a database called HotRegion, which provides the hot region information of the interfaces by using predicted hot spot residues, and structural properties of these interface residues such as pair potentials of interface residues, accessible surface area (ASA) and relative ASA values of interface residues of both monomer and complex forms of proteins. Also, the 3D visualization of the interface and interactions among hot spot residues are provided. HotRegion is accessible at http://prism.ccbb.ku.edu.tr/hotregion.

Mechanical properties of multi-walled carbon nanotube (MWCNT)/polymethyl methacrylite (PMMA) nanocomposite prepared via the coagulation method

Science.gov (United States)

Ismail, Noor Mazni; Aziz, Azizan; Jaafar, Mariatti

2012-06-01

Multi-walled carbon nanotube (MWCNT) is well known as one of the best candidates for reinforcing the next generation of high performance nanocomposites due to its excellent mechanical properties. In this study, MWCNTs were dispersed in polymethyl methacrylite (PMMA) matrix to enhance its mechanical strength. MWCNT/PMMA were prepared by simple coagulation method and then hot-pressed to create nanocomposite film consists of rich nanotubes. Samples were prepared in respect to various high filler loading (1%, 3%, 5%, 7% and 10% wt.). Standard ASTM D790 flexural test was used to evaluate the mechanical properties of the composites. The morphology and surface fracture were observed via scanning electron microscope. The properties of the composites where found to be better than the neat PMMA. Flexural strength & flexural modulus of MWCNT/PMMA nanocomposite showed an improvement up to 24.1% and 107.7% compared to the neat PMMA, respectively. These studies therefore demonstrate that MWCNT/PMMA prepared by coagulation method able to successfully improve mechanical properties of PMMA.

Microstructure, mechanical properties and texture of an AA6061/AA5754 composite fabricated by cross accumulative roll bonding

Energy Technology Data Exchange (ETDEWEB)

Verstraete, K., E-mail: kevin.verstraete@u-psud.fr [Université Paris-Sud, SP2M, ICMMO, UMR CNRS 8182, 91405 Orsay Cedex (France); Helbert, A.L. [Université Paris-Sud, SP2M, ICMMO, UMR CNRS 8182, 91405 Orsay Cedex (France); Brisset, F. [Université Paris-Sud, ICMMO, UMR CNRS 8182, 91405 Orsay Cedex (France); Benoit, A.; Paillard, P. [Institut des Matériaux Jean Rouxel (IMN), UMR 6502, Polytech’Nantes, Nantes Cedex (France); Baudin, T. [Université Paris-Sud, SP2M, ICMMO, UMR CNRS 8182, 91405 Orsay Cedex (France)

2015-07-29

AA6061 alloy is a widely used material in the automotive and aerospace industries, but is prone to hot cracking, which limits its weldability. To prevent this phenomenon, the AA6061/AA5754 composite was formed using a severe plastic deformation technique, Cross Accumulative Roll Bonding (CARB), at an elevated temperature (350 °C) to ensure good bonding between layers. This technique was efficient to maintain a small grain size, even under the process temperature conditions, and consequently, preserve good mechanical properties. The composite had better mechanical properties than the initial aluminium alloys. Microstructure and texture remained stable after two cycles and yield stress tended towards an equal value in the rolling and the transverse directions. After two cycles, the main component was the {001}〈110〉 rotated Cube, which was maintained for up to 10 cycles. Diffusion was more effective as the strain increased. Finally, a tungsten inert gas (TIG) welding process was performed on the composite and confirmed resistance to hot cracking.

PHOTOSPHERIC PROPERTIES OF WARM EUV LOOPS AND HOT X-RAY LOOPS

Energy Technology Data Exchange (ETDEWEB)

Kano, R. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Ueda, K. [Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Tsuneta, S., E-mail: ryouhei.kano@nao.ac.jp [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan)

2014-02-20

We investigate the photospheric properties (vector magnetic fields and horizontal velocity) of a well-developed active region, NOAA AR 10978, using the Hinode Solar Optical Telescope specifically to determine what gives rise to the temperature difference between ''warm loops'' (1-2 MK), which are coronal loops observed in EUV wavelengths, and ''hot loops'' (>3 MK), coronal loops observed in X-rays. We found that outside sunspots, the magnetic filling factor in the solar network varies with location and is anti-correlated with the horizontal random velocity. If we accept that the observed magnetic features consist of unresolved magnetic flux tubes, this anti-correlation can be explained by the ensemble average of flux-tube motion driven by small-scale random flows. The observed data are consistent with a flux tube width of ∼77 km and horizontal flow at ∼2.6 km s{sup –1} with a spatial scale of ∼120 km. We also found that outside sunspots, there is no significant difference between warm and hot loops either in the magnetic properties (except for the inclination) or in the horizontal random velocity at their footpoints, which are identified with the Hinode X-Ray Telescope and the Transition Region and Coronal Explorer. The energy flux injected into the coronal loops by the observed photospheric motion of the magnetic fields is estimated to be 2 × 10{sup 6} erg s{sup –1} cm{sup –2}, which is the same for both warm and hot loops. This suggests that coronal properties (e.g., loop length) play a more important role in giving rise to temperature differences of active-region coronal loops than photospheric parameters.

The effect of processing on the mechanical properties of self-reinforced composites

Science.gov (United States)

Hassani, Farzaneh; Martin, Peter J.; Falzon, Brian G.

2018-05-01

Hot-compaction is one of the most common manufacturing methods for creating recyclable all thermoplastic composites. The current work investigates the compaction of highly oriented self-reinforced fabrics with three processing methods to study the effect of pressure and temperature in the tensile mechanical properties of the consolidated laminates. Hot-press, calender roller and vacuum bag technique were adopted to consolidate bi-component polypropylene woven fabrics in a range of pressures and compaction temperatures. Hot-pressed samples exhibited the highest quality of compaction. The modulus of the hot-pressed samples increased with compaction temperature initially due to the improved interlayer bonding and decreased after a maximum at 150°C because of partial melting of the reinforcement phase. The calender roller technique exhibited to have smaller processing temperature window as the pressure is only applied for a short time and the fabrics start to shrink with increasing the processing temperature. The need for constraining the fabrics through the process is therefore found to be paramount. The Vacuum bag results showed this technique to be the least efficient method because of the low compaction pressure. Microscopic images and void content measurement of the consolidated samples further validate the results from tensile testing.

A Possible Mechanism for Driving Oscillations in Hot Giant Planets

Energy Technology Data Exchange (ETDEWEB)

Dederick, Ethan; Jackiewicz, Jason, E-mail: dederiej@nmsu.edu, E-mail: jasonj@nmsu.edu [New Mexico State University, Las Cruces, NM (United States)

2017-03-10

The κ -mechanism has been successful in explaining the origin of observed oscillations of many types of “classical” pulsating variable stars. Here we examine quantitatively if that same process is prominent enough to excite the potential global oscillations within Jupiter, whose energy flux is powered by gravitational collapse rather than nuclear fusion. Additionally, we examine whether external radiative forcing, i.e., starlight, could be a driver for global oscillations in hot Jupiters orbiting various main-sequence stars at defined orbital semimajor axes. Using planetary models generated by the Modules for Experiments in Stellar Astrophysics and nonadiabatic oscillation calculations, we confirm that Jovian oscillations cannot be driven via the κ -mechanism. However, we do show that, in hot Jupiters, oscillations can likely be excited via the suppression of radiative cooling due to external radiation given a large enough stellar flux and the absence of a significant oscillatory damping zone within the planet. This trend does not seem to be dependent on the planetary mass. In future observations, we can thus expect that such planets may be pulsating, thereby giving greater insight into the internal structure of these bodies.

A Possible Mechanism for Driving Oscillations in Hot Giant Planets

International Nuclear Information System (INIS)

Dederick, Ethan; Jackiewicz, Jason

2017-01-01

The κ -mechanism has been successful in explaining the origin of observed oscillations of many types of “classical” pulsating variable stars. Here we examine quantitatively if that same process is prominent enough to excite the potential global oscillations within Jupiter, whose energy flux is powered by gravitational collapse rather than nuclear fusion. Additionally, we examine whether external radiative forcing, i.e., starlight, could be a driver for global oscillations in hot Jupiters orbiting various main-sequence stars at defined orbital semimajor axes. Using planetary models generated by the Modules for Experiments in Stellar Astrophysics and nonadiabatic oscillation calculations, we confirm that Jovian oscillations cannot be driven via the κ -mechanism. However, we do show that, in hot Jupiters, oscillations can likely be excited via the suppression of radiative cooling due to external radiation given a large enough stellar flux and the absence of a significant oscillatory damping zone within the planet. This trend does not seem to be dependent on the planetary mass. In future observations, we can thus expect that such planets may be pulsating, thereby giving greater insight into the internal structure of these bodies.

Effects of Niobium Microalloying on Microstructure and Properties of Hot-Dip Galvanized Sheet

Energy Technology Data Exchange (ETDEWEB)

Mohrbacher, Hardy [NiobelCon bvba, Brussels (Belgium)

2010-04-15

Niobium microalloying is effective in hot-rolled and cold-rolled steels by providing a fine-grained microstructure resulting in increased strength. To optimize the strengthening effect, alloy design and hot-rolling conditions have to be adapted. As a key issue the dissolution and precipitation characteristics of Nb are discussed in particular with regard to the run-out table conditions. It is then considered how the hot-rolled microstructure and the solute state of Nb interact with the hot-dip galvanizing cycle. The adjusted conditions allow controlling the morphology and distribution of phases in the cold-rolled annealed material. Additional precipitation hardening can be achieved as well. The derived options can be readily applied to produce conventional HSLA and IF high strength steels as well as to modem multiphase steels. It will be explained how important application properties such as strength, elongation, bendability, weldability and delayed cracking resistance can be influenced in a controlled and favorable way. Examples of practical relevance and experience are given.

Atomic properties in hot plasmas from levels to superconfigurations

CERN Document Server

Bauche, Jacques; Peyrusse, Olivier

2015-01-01

This book is devoted to the calculation of hot-plasma properties which generally requires a huge number of atomic data. It is the first book that combines information on the details of the basic atomic physics and its application to atomic spectroscopy with the use of the relevant statistical approaches. Information like energy levels, radiative rates, collisional and radiative cross-sections, etc., must be included in equilibrium or non-equilibrium models in order to describe both the atomic-population kinetics and the radiative properties. From the very large number of levels and transitions involved in complex ions, some statistical (global) properties emerge. The book presents a coherent set of concepts and compact formulas suitable for tractable and accurate calculations. The topics addressed are: radiative emission and absorption, and a dozen of other collisional and radiative processes; transition arrays between level ensembles (configurations, superconfigurations); effective temperatures of configurat...

Workability and mechanical properties of ultrasonically cast Al–Al2O3 nanocomposites

International Nuclear Information System (INIS)

Mula, Suhrit; Pabi, S.K.; Koch, Carl C; Padhi, P.; Ghosh, S.

2012-01-01

Workability and mechanical properties of the ultrasonically cast Al–X wt% Al 2 O 3 (X=2, 3.57 and 4.69) metal matrix nanocomposites were reported in the present investigation. The Al–Al 2 O 3 (average size ∼10 nm) composites showed maximum reduction ratios of 2, 1.75 and 1.41 at room temperature, and 8, 7 and 6 at 300 °C. The elastic modulus, nanoindentation hardness, microhardness and Vickers hardness were measured on the as-cast, cold and hot rolled specimens. The tensile properties were also evaluated for the as-cast composites for different wt% of reinforcement. The microstructural examination was done by optical, scanning and transmission electron microscopy. The strength and workability of the nanocomposites were discussed in the light of dislocation/particle interaction, particle size and its concentration, inter-particle spacing and working temperature. 2 wt% of Al 2 O 3 reinforcement showed better combination of workability and mechanical properties possibly due to better distribution of particulates in the matrix.

Hot soup! Correlating the severity of liquid scald burns to fluid and biomedical properties.

Science.gov (United States)

Loller, Cameron; Buxton, Gavin A; Kerzmann, Tony L

2016-05-01

Burns caused by hot drinks and soups can be both debilitating and costly, especially to pediatric and geriatric patients. This research is aimed at better understanding the fluid properties that can influence the severity of skin burns. We use a standard model which combines heat transfer and biomedical equations to predict burn severity. In particular, experimental data from a physical model serves as the input to our numerical model to determine the severity of scald burns as a consequence of actual fluid flows. This technique enables us to numerically predict the heat transfer from the hot soup into the skin, without the need to numerically estimate the complex fluid mechanics and thermodynamics of the potentially highly viscous and heterogeneous soup. While the temperature of the soup is obviously is the most important fact in determining the degree of burn, we also find that more viscous fluids result in more severe burns, as the slower flowing thicker fluids remain in contact with the skin for longer. Furthermore, other factors can also increase the severity of burn such as a higher initial fluid temperature, a greater fluid thermal conductivity, or a higher thermal capacity of the fluid. Our combined experimental and numerical investigation finds that for average skin properties a very viscous fluid at 100°C, the fluid must be in contact with the skin for around 15-20s to cause second degree burns, and more than 80s to cause a third degree burn. Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.

Effects of hot water pre-extraction on surface properties of bagasse soda pulp.

Science.gov (United States)

Cordeiro, Nereida; Ashori, Alireza; Hamzeh, Yahya; Faria, Marisa

2013-03-01

In this work, the effects of hot water pre-extraction of depithed bagasse on the soda pulping and surface properties were studied. The conditions of hot water pre-extraction were: maximum temperature 170 °C, heat-up time 90 min, time at maximum temperature 10 min, and solid to liquor ratio (S:L) 1:8. Consequently, the pre-extracted and un-extracted bagasse chips were subjected to soda pulping at 160 °C for 1h with 11, 14 and 17% active alkali charge and an S:L of 1:5. The results showed that the hot water pre-extraction increased bagasse surface texture porosity by hemicellulose degradation. Therefore, the delignification was faster for pulping of pre-extracted samples. At a certain charge of alkali, pre-extracted samples showed higher screened yield and lower Kappa number. For instance, at 17% alkali charge, pre-extracted bagasse gave 11.3% higher pulp yield compared with the un-extracted ones. Inverse gas chromatography (IGC) results showed that the hot water pre-extraction changed the active sites on the bagasse surface, decreasing the dispersive energy and the basicity character, and affected the particle morphology. The pulping process decreased the hydrophobicity and the basicity of the bagasse surface. The surfaces of un-extracted and pre-extracted bagasse pulps had similar properties but different morphology. The pulps present higher surface area and permeability with more reactive capacity. Copyright © 2012 Elsevier B.V. All rights reserved.

Rate controlling mechanisms during hot deformation of Mg–3Gd–1Zn magnesium alloy: Dislocation glide and climb, dynamic recrystallization, and mechanical twinning

International Nuclear Information System (INIS)

Mirzadeh, H.; Roostaei, M.; Parsa, M.H.; Mahmudi, R.

2015-01-01

Highlights: • Hot deformation behavior and dynamic recrystallization of GZ31 magnesium alloy. • Deducing the operative deformation mechanisms by constitutive analysis. • Viscous glide as the rate controlling step during hot working of GZ31 alloy. • Characterization of the effect of mechanical twinning on constitutive relations. - Abstract: The flow behavior of the Mg–3Gd–1Zn (GZ31) magnesium alloy during hot working was critically analyzed and dislocation glide in the form of a viscous drag process (viscous glide) was identified as the rate controlling mechanism due to interaction of rare earth Gd atoms with the moving dislocations. Mechanical twinning was shown to significantly affect the level of flow stress at high Zener–Hollomon parameters, i.e. low forming temperatures and high strain rates. Moreover, dynamic recrystallization (DRX) was found to be another responsible phenomenon for deviation of constitutive equations from the theoretical ones, namely the deformation activation energy based on diffusivity and the pre-defined Garofalo’s type hyperbolic sine power, during high-temperature thermomechanical processing of this creep resistant light alloy

ACTIVATED HOT PRESSING BEHAVIOR OF WC NANOPOWDERS

Directory of Open Access Journals (Sweden)

Edwin GEVORKYAN

2010-06-01

Full Text Available The questions of consolidation of nanopowders concerning hot compaction by pressing activated by electric current action are considered. Mechanisms of grain boundary creep-sliding which are sequentially prevalent in a forming of compacted structures under influence of temperature factor and in the presence of a direct electric heating are discussed. Structural-transformational sources and conditions of forming of high physical-mechanical properties of nanopowder refractory solid-state products are described.

X-ray Radiation Mechanisms and the Beaming Effect of Hot Spots ...

Indian Academy of Sciences (India)

Astr. (2011) 32, 193–196 c Indian Academy of Sciences. X-ray Radiation Mechanisms and the Beaming Effect of Hot Spots and Knots in AGN Jets. Jin Zhang1,∗. , Jin-Ming Bai2, Liang Chen2 & Enwei Liang3. 1College of Physics and Electronic Engineering, Guangxi Teachers Education University,. Nanning 530001, China.

Extractive and anatomical wood structure effects on mechanical properties of Caoba wood (Swietenia macrophylla King)

International Nuclear Information System (INIS)

Arevalo Fuentes Rosven Libardo; Hernandez Roger

2008-01-01

The compression tangential to grain of samples of mahogany wood from Peru was examined at different relative humidity levels at 25 Celsius degrade to determine the influence of both extractives and anatomical structure. Matched samples were used to assess the percentage of extractive components by extraction with solvents of increasing polarity: cyclohexane, dichloromethane, acetone, methanol and hot water. Additionally, fourteen anatomical parameters were determined by image analysis. Stepwise regression analysis concluded that mainly anatomical features, such as rays and vessels, rather than extractives, affect the mechanical behaviour of mahogany. These findings are agree with earlier results showing a negative effect of large and multiseriate rays on the mechanical properties of wood when loaded perpendicularly to their long axis. The influence of lumen located extracts soluble in dichloromethane might disallow deformations. Finally, it is postulated that hot water extracts may play a plasticizing role in this species.

Investigation of the hot ductility of a high-strength boron steel

International Nuclear Information System (INIS)

Güler, Hande; Ertan, Rukiye; Özcan, Reşat

2014-01-01

In this study, the high-temperature ductility behaviour of an Al–Si-coated 22MnB5 sheet was investigated. The mechanical properties of Al–Si-coated 22MnB5 boron steel were examined via hot tensile tests performed at temperatures ranging from 400 to 900 °C at a strain rate of 0.083 s −1 . The deformation and fracture mechanisms under hot tensile testing were considered in relation to the testing data and to the fracture-surface observations performed via SEM. The hot ductility of the tested boron steel was observed as a function of increasing temperature and the Al–Si-coated 22MnB5 boron steel exhibited a ductility loss at 700 °C

Processing hot-dip galvanized AHSS grades: a challenging task

Energy Technology Data Exchange (ETDEWEB)

Pichler, A.; Hebesberger, T.; Tragl, E.; Traint, S.; Faderl, J.; Angeli, G.; Koesters, K. [voestalpine Stahl GmbH, Linz (Austria)

2005-07-01

High-strength thin sheet steel grades have gained a considerable market share. At present a very strong demand has been observed for DP (dual-phase), CP (complex phase) and TRIP grades, which are often summarized as advanced high-strength steel grades (AHSS). The potential benefits of applying AHSS grades were impressively demonstrated in the ULSAC-AVC project, in which a remarkable reduction in mass and an increase in stiffness and crash safety were achieved by using a very high share of AHSS steel grades. The present contribution concentrates on hot-dip galvanized AHSS thin sheet grades. The hot-dip galvanizeability of such grades is critically discussed after an overview is provided of the metallurgy of AHSS grades, including microstructure, mechanical properties, phase transformations and required alloy design. Based on these fundamentals, the processing of AHSS grades in the hot-dip galvanizing line is discussed and the resulting properties presented. (orig.)

Mechanical properties of dental resin composites by co-filling diatomite and nanosized silica particles

International Nuclear Information System (INIS)

Wang Hua; Zhu Meifang; Li Yaogang; Zhang Qinghong; Wang Hongzhi

2011-01-01

The aim of this study was to investigate the mechanical property effects of co-filling dental resin composites with porous diatomite and nanosized silica particles (OX-50). The purification of raw diatomite by acid-leaching was conducted in a hot 5 M HCl solution at 80 deg. C for 12 h. Both diatomite and nanosized SiO 2 were silanized with 3-methacryloxypropyltrimethoxysilane. The silanized inorganic particles were mixed into a dimethacrylate resin. Purified diatomite was characterized by X-ray diffraction, UV-vis diffuse reflectance spectroscopy and an N 2 adsorption-desorption isotherm. Silanized inorganic particles were characterized using Fourier transform infrared spectroscopy and a thermogravimetric analysis. The mechanical properties of the composites were tested by three-point bending, compression and Vicker's microhardness. Scanning electron microscopy was used to show the cross-section morphologies of the composites. Silanization of diatomite and nanosized silica positively reinforced interactions between the resin matrix and the inorganic particles. The mechanical properties of the resin composites gradually increased with the addition of modified diatomite (m-diatomite). The fracture surfaces of the composites exhibited large fracture steps with the addition of m-diatomite. However, when the mass fraction of m-diatomite was greater than 21 wt.% with respect to modified nanosized silica (mOX-50) and constituted 70% of the resin composite by weight, the mechanical properties of the resin composites started to decline. Thus, the porous structure of diatomite appears to be a crucial factor to improve mechanical properties of resin composites.

Effect of extrusion processing on the microstructure, mechanical properties, biocorrosion properties and antibacterial properties of Ti-Cu sintered alloys.

Science.gov (United States)

Zhang, Erlin; Li, Shengyi; Ren, Jing; Zhang, Lan; Han, Yong

2016-12-01

Ti-Cu sintered alloys, Ti-Cu(S) alloy, have exhibited good anticorrosion resistance and strong antibacterial properties, but low ductility in previous study. In this paper, Ti-Cu(S) alloys were subjected to extrusion processing in order to improve the comprehensive property. The phase constitute, microstructure, mechanical property, biocorrosion property and antibacterial activity of the extruded alloys, Ti-Cu(E), were investigated in comparison with Ti-Cu(S) by X-ray diffraction (XRD), optical microscopy (OM), scanning electronic microscopy (SEM) with energy disperse spectroscopy (EDS), mechanical testing, electrochemical testing and plate-count method in order to reveal the effect of the extrusion process. XRD, OM and SEM results showed that the extrusion process did not change the phase constitute but refined the grain size and Ti2Cu particle significantly. Ti-Cu(E) alloys exhibited higher hardness and compressive yield strength than Ti-Cu(S) alloys due to the fine grain and Ti2Cu particles. With the consideration of the total compressive strain, it was suggested that the extrusion process could improve the ductility of Ti-Cu alloy(S) alloys. Electrochemical results have indicated that the extrusion process improved the corrosion resistance of Ti-Cu(S) alloys. Plate-count method displayed that both Ti-Cu(S) and Ti-Cu(E) exhibited strong antibacterial activity (>99%) against S. aureus. All these results demonstrated that hot forming processing, such as the extrusion in this study, refined the microstructure and densified the alloy, in turn improved the ductility and strength as well as anticorrosion properties without reduction in antibacterial properties. Copyright © 2016 Elsevier B.V. All rights reserved.

Structure and mechanical properties of TiZr binary alloy after Al addition

International Nuclear Information System (INIS)

Jiang, X.J.; Jing, R.; Liu, C.Y.; Ma, M.Z.; Liu, R.P.

2013-01-01

Microstructure and mechanical properties of hot-rolled TiZrAl alloys were studied. The results showed that the microstructure of all alloys mainly consisted of lamellar α phase. The thickness of the lamellar α phase gradually increased with increasing aluminum content. Moreover, large numbers of stacking faults was observed in Ti–25Zr–15Al (at%) alloy. The aluminum addition strongly affected the mechanical properties of the TiZrAl alloys. With increased aluminum contents, the strength increased evidently, whereas, the elongation decreased. Ti–25Zr–15Al (at%) with the highest aluminum contents in all alloys, possessed the highest tensile strength (σ b =1319 MPa), i.e. strengthened by 41% compared with Ti–25Zr (at%) alloy, and still retained the elongation of 5.5%. According to the classical size and/or modulus misfits model, the effect of aluminum addition was significant in TiZr alloys because of the considerable misfits between aluminum and zirconium

Successful Treatment of Carcinomatous Central Airway Obstruction with Bronchoscopic Electrocautery Using Hot Biopsy Forceps during Mechanical Ventilation

Directory of Open Access Journals (Sweden)

Motoi Ugajin

2017-01-01

Full Text Available We report the case of a 72-year-old man with occlusion of the left main bronchus due to squamous cell carcinoma of the lung. He required tracheal intubation and mechanical ventilation because of the aggravation of atelectasis and obstructive pneumonia. Electrocautery using hot biopsy forceps was performed during mechanical ventilation with a 40% fraction of inspired oxygen. He was extubated following improvement in the atelectasis and obstructive pneumonia and discharged with shrinkage of the tumor after chemotherapy. We describe a safe electrocautery procedure using hot biopsy forceps during mechanical ventilation with reference to previous reports.

Influence of Hot-Working Conditions on High-Temperature Properties of a Heat-Resistant Alloy

Science.gov (United States)

Ewing, John F; Freeman, J W

1957-01-01

The relationships between conditions of hot-working and properties at high temperatures and the influence of the hot-working on response to heat treatment were investigated for an alloy containing nominally 20 percent molybdenum, 2 percent tungsten, and 1 percent columbium. Commercially produced bar stock was solution-treated at 2,200 degrees F. to minimize prior-history effects and then rolled at temperatures of 2,200 degrees, 2,100 degrees, 2,000 degrees, 1,800 degrees, and 1,600 degrees F. Working was carried out at constant temperature and with incremental decreases in temperature simulating a falling temperature during hot-working. In addition, a few special repeated cyclic conditions involving a small reduction at high temperature followed by a small reduction at a low temperature were used to study the possibility of inducing very low strengths by the extensive precipitation accompanying such properties. Most of the rolling was done in open passes with a few check tests being made with closed passes. Heat treatments at both 2,050 degrees and 2,200 degrees F. subsequent to working were used to study the influence on response to heat treatment.

An overview of high thermal conductive hot press forming die material development

Directory of Open Access Journals (Sweden)

A.R. Zulhishamuddin

2015-12-01

Full Text Available Most of the automotive industries are using high strength steel components, which are produced via hot press forming process. This process requires die material with high thermal conductivity that increases cooling rate during simultaneous quenching and forming stage. Due to the benefit of high quenching rate, thermal conductive die materials were produced by adding carbide former elements. This paper presents an overview of the modification of alloying elements in tool steel for high thermal conductivity properties by transition metal elements addition. Different types of manufacturing processes involved in producing high thermal conductive materials were discussed. Methods reported were powder metallurgy hot press, direct metal deposition, selective laser melting, direct metal laser sintering and spray forming. Elements likes manganese, nickel, molybdenum, tungsten and chromium were proven to increase thermal conductivity properties. Thermal conductivity properties resulted from carbide network presence in the steel microstructure. To develop feasible and low cost hot press forming die material, casting of Fe-based alloy with carbide former composition can be an option. Current thermal conductivity properties of hot press forming die material range between 25 and 66 W/m.K. The wide range of thermal conductivity varies the mechanical properties of the resulting components and lifetime of HPF dies.

The effect of different stabilizers on the thermostability of electron beam crosslinked polyethylene in hot water

International Nuclear Information System (INIS)

Hassanpour, S.; Khoylou, F.

2003-01-01

Plastic pipes owing to their flexibility, great lengths, easier handling and absence of corrosion have been used for hot-water installations. Crosslinked high-density polyethylene is one of the best materials, being used for this purpose. The useful lifetime of unstabilized polyethylene is predicted to vary from a few months in hot water (30-40 deg. C) to almost two years in cool water (0-10 deg. C). Polyethylene was mixed with different types of stabilizers, in order to increase its durability. The samples were irradiated at 100-150 kGy. The amount of gel fraction and the changes in mechanical properties were measured. Irradiated samples were immersed in hot water for 1000 h. The thermostability of the specimens and the existence of antioxidants were measured by the induction time technique using differential scanning calorimetry at different time intervals. Furthermore, the changes in chemical structure and mechanical properties of the samples during their immersion in hot water were determined

Evaluation of the mechanical properties after thermal treatment of a structural hot rolled multiphase steel

Directory of Open Access Journals (Sweden)

Asensio-Lozano, J.

2007-12-01

Full Text Available The present paper corresponds to the experimental study conducted on a hot rolled (HR multiphase (MP steel, in which hardness, tensile and toughness properties were measured after the application of a series of subcritical and intercritical heat treatments (HT to the hot rolled stock. The aforementioned values were compared to the corresponding ones in the as-rolled state and after normalizing. The microstructure in the longitudinal plane of the strip was analyzed by light optical microscopy in the as-rolled state and in the HT samples. Longitudinal (L and transverse (T tensile and toughness specimens were cut to characterize every condition studied. Toughness properties were evaluated by means of Charpy V-notch tests conducted at 20 °C, 0 °C, –20 °C, –40 °C, –60 °C and –80 °C . It was observed that the yield stress increased with the increase in the heat treatment temperature in the subcritical range, while the tensile strength decreased slightly over the same range of temperatures. Uniform and total elongation only showed a slight improvement when the treatment was conducted at 620 °C and 700 °C, while the best toughness response corresponded to the sample treated at 500 °C for operating temperatures comprised between –40 °C and room temperature (RT.

El presente estudio corresponde al trabajo experimental desarrollado en un acero multifase laminado en caliente, en el que se evaluaron las propiedades de dureza, tracción y tenacidad a impacto, tras realizar tratamientos térmicos subcríticos e intercríticos al material laminado en caliente. Los valores precedentes se comparan con el material de partida laminado en caliente y tras tratamiento de normalizado. Se analiza la microestructura en microscopía óptica de reflexión, en el plano longitudinal tanto en el estado laminado como en las muestras tratadas térmicamente. Se estudiaron los comportamientos longitudinales y transversales en tracción y frente a impacto

Study of hot cracking potential in a 6-ton steel ingot casting

Science.gov (United States)

Yang, Jing'an; Liu, Baicheng; Shen, Houfa

2018-04-01

A new hot cracking potential (HCP) criterion, for the appearance of hot tearing in steel ingot castings, is proposed. The maximum value of the first principal stress, divided by the dynamic yield strength in the brittle temperature range (BTR), was used to identify the HCP. Experiments were carried out on a 6-ton P91 steel ingot in which severe hot tearing was detected in the upper centerline. Another ingot, with a better heat preservation riser, and without hot tearing, was used for comparison. Samples were obtained from the area of the ingot body with hot tearing, and their morphologies were inspected by a X-ray high energy industrial computed tomography. The carbon and sulfur distributions around the hot tearing were characterized by an infrared spectrometry carbon and sulfur analyzer. High temperature mechanical properties were obtained by a Gleeble thermal simulation machine, under different strain rates. Then, thermo-mechanical simulations using an elasto-viscoplastic finite-element model were conducted to analyze the stress and strain evolution during ingot solidification. The results showed that the hot tearing area, which was rich in both carbon and sulfur, was under excessive tensile stress in the BTR, bearing the highest HCP.

An investigation into the effects of conventional heat treatments on mechanical characteristics of new hot working tool steel

Science.gov (United States)

Fares, M. L.; Athmani, M.; Khelfaoui, Y.; Khettache, A.

2012-02-01

The effects of conventional heat treatments, i.e. quenching and tempering, on the mechanical characteristics of non standard hot work tool steel, close to either AISI-H11/H13 are investigated. The major elemental composition differences are in carbon, silicon and vanadium. The objective of the carried heat treatments is to obtain an efficient tool performance in terms of hardness, wear resistance and mechanical strength. Experimental results allow an explanation of the surface properties depending mainly on both chemical composition and optimised preheating parameters. After austenitizing at 1050 °C for 15 min, the as-quenched steel in oil bath exhibited the fully martensitic structure (without bainite) connected to a small fraction of retained austenite and complex carbides mainly of M23C6 type. Twice tempering at 500 °C and 600 °C resulted in initiating the precipitation processes and the secondary hardness effect. As a result, carbide content amounted to 3% while the retained austenite content decreased to 0%. Accordingly, the required mechanical properties in terms of hardness and wear are fulfilled and are adequately favourable in handling both shocks and pressures for the expected tool life. Induced microstructures are revealed using optical and scanning electron microscopes. Phase compositions are assessed by means of X-ray diffraction technique while mechanical characteristics are investigated based on hardness and abrasive wear standard tests.

Mechanical properties evaluation of single and hybrid composites polyester reinforced bamboo, PALF and coir fiber

Science.gov (United States)

Rihayat, T.; Suryani, S.; Fauzi, T.; Agusnar, H.; Wirjosentono, B.; Syafruddin; Helmi; Zulkifli; Alam, P. N.; Sami, M.

2018-03-01

This study aims to determine the composition fiber natural of bamboo, pineapple leaf and coir in single and hybrid composite to see the best characteristics of tensile strength and flexural test by using a Universal Testing Machine (UTM) and observe the effect on the microstructure of the composite through optical and scanning electron microscopy. Bamboo, Palf and coir have synthesis from natural fiber was used as reinforcement in polyester composite using hand lay up or a hot-compression moulding while filler:matrix was used (45%:55wt.%, 70%:30wt.% and 15%:85wt.%). From the variation of the volume fraction between filler and matrix show that mechanical properties of composites increased with increasing amount of filler in the matrix. This is evidenced by the high mechanical properties A:B:C/Ps in compositions 45%: 55wt.% 136 Mpa while flexural strength 93 N and good structure surface morphology. This research has produced a hybrid composite materials that have high mechanical properties and bending compared with conventional synthetic fibers and other materials.

Effect of boron and carbon addition on microstructure and mechanical properties of Ti-15-3 alloy

International Nuclear Information System (INIS)

Sarkar, R.; Ghosal, P.; Muraleedharan, K.; Nandy, T.K.; Ray, K.K.

2011-01-01

Highlights: → Development of β Ti alloys with B and C addition for improved mechanical properties. → Detailed characterization of microstructural constituents using electron microscopy. → Microstructure-mechanical property correlation in this new class of alloys. → Strengthening mechanism in β Ti alloy in the presence of hard and non-deformable phases. - Abstract: A detailed microstructure-mechanical property correlation was carried out in beta titanium alloys (Ti-15V-3Al-3Sn-3Cr) with boron and carbon additions. The alloys were prepared by non-consumable vacuum arc melting followed by hot rolling. Microstructural characterization was carried out using an optical microscope, a scanning electron microscope (SEM), a transmission electron microscope (TEM) and a high resolution TEM (HRTEM). Addition of boron and carbon resulted in the precipitation of TiB and TiC, respectively, and these phases acted as reinforcements. Evaluation of mechanical properties in solution treated and solution treated plus aged condition showed strengthening in the boron and carbon containing alloy with respect to the base. Strengthening in solution treated condition was attributed to a synergistic effect of grain refinement and load transfer in the presence of non-deformable phases. On the other hand, higher strength in boron and carbon containing alloys on aging was ascribed to the presence of finer aged microstructures.

The influence of Cr content on the mechanical properties of ODS ferritic steels

Science.gov (United States)

Li, Shaofu; Zhou, Zhangjian; Jang, Jinsung; Wang, Man; Hu, Helong; Sun, Hongying; Zou, Lei; Zhang, Guangming; Zhang, Liwei

2014-12-01

The present investigation aimed at researching the mechanical properties of the oxide dispersion strengthened (ODS) ferritic steels with different Cr content, which were fabricated through a consolidation of mechanical alloyed (MA) powders of 0.35 wt.% nano Y2O3 dispersed Fe-12.0Cr-0.5Ti-1.0W (alloy A), Fe-16.0Cr-0.5Ti-1.0W (alloy B), and Fe-18.0Cr-0.5Ti-1.0W (alloy C) alloys (all in wt.%) by hot isostatic pressing (HIP) with 100 MPa pressure at 1150 °C for 3 h. The mechanical properties, including the tensile strength, hardness, and impact fracture toughness were tested by universal testers, while Young's modulus was determined by ultrasonic wave non-destructive tester. It was found that the relationship between Cr content and the strength of ODS ferritic steels was not a proportional relationship. However, too high a Cr content will cause the precipitation of Cr-enriched segregation phase, which is detrimental to the ductility of ODS ferritic steels.

Effect of hot-dry environment on fiber-reinforced self-compacting concrete

Science.gov (United States)

Tioua, Tahar; Kriker, Abdelouahed; Salhi, Aimad; Barluenga, Gonzalo

2016-07-01

Drying shrinkage can be a major reason for the deterioration of concrete structures. Variation in ambient temperature and relative humidity cause changes in the properties of hardened concrete which can affect their mechanical and drying shrinkage characteristics. The present study investigated mechanical strength and particularly drying shrinkage properties of self-compacting concretes (SCC) reinforced with date palm fiber exposed to hot and dry environment. In this study a total of nine different fibers reinforced self compacting concrete (FRSCC) mixtures and one mixture without fiber were prepared. The volume fraction and the length of fibers reinforcement were 0.1-0.2-0.3% and 10-20-30 mm. It was observed that drying shrinkage lessened with adding low volumetric fraction and short length of fibers in curing condition (T = 20 °C and RH = 50 ± 5 %), but increased in hot and dry environment.

Effect of different lay-ups on the microstructure, mechanical properties and neutron transmission of neutron shielding fibre metal laminates

International Nuclear Information System (INIS)

Fu, Xuelong; Tang, Xiaobin; Hu, Yubing; Li, Huaguan; Tao, Jie

2016-01-01

A novel neutron shielding fibre metal laminates (NSFMLs) with different lay-ups, composed of stacking layers of AA6061 plates, neutron shielding composite and carbon fibre reinforced polyimide (CFRP), were fabricated using hot molding process in atmospheric environments. The microstructure, mechanical properties and neutron transmission of the NSFMLs were evaluated, respectively. The results indicated that the NSFMLs possessed good mechanical properties owing to the good interfacial adhesion of the components. Tensile strength and elastic modulus of the NSFMLs increased with the numbers of lay-ups, while the elongation to fracture exhibited obvious declining tendency. Flexural strength and modulus of the NSFMLs were improved obviously with the increasing of stacking layers. Neutron transmission of the NSFMLs decreased obviously with increasing the number of lay-ups, owing to the increase of "1"0B areal density. Besides, the effect of carbon fibres on the neutron shielding performance of the NSFMLs was also taken into consideration. - Highlights: • A novel neutron shielding fibre metal laminates (NSFMLs) with different lay-ups was successfully fabricated using hot molding process. • Mechanical properties of the NSFMLs were performed in accordance with relative standards. • Neutron transmission of the NSFMLs was conducted according to the testing results. • The effect of carbon fibres on the neutron transmission of the NSFMLs was also investigated.

Effect of different lay-ups on the microstructure, mechanical properties and neutron transmission of neutron shielding fibre metal laminates

Energy Technology Data Exchange (ETDEWEB)

Fu, Xuelong [College of Material Science & Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 211100 (China); Department of Mechanical and Electronic Engineering, Jiangsu Polytechnic of Finance & Economics, Huai' an, 223003 (China); Tang, Xiaobin; Hu, Yubing; Li, Huaguan [College of Material Science & Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 211100 (China); Tao, Jie, E-mail: taojie@nuaa.edu.cn [College of Material Science & Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 211100 (China)

2016-07-15

A novel neutron shielding fibre metal laminates (NSFMLs) with different lay-ups, composed of stacking layers of AA6061 plates, neutron shielding composite and carbon fibre reinforced polyimide (CFRP), were fabricated using hot molding process in atmospheric environments. The microstructure, mechanical properties and neutron transmission of the NSFMLs were evaluated, respectively. The results indicated that the NSFMLs possessed good mechanical properties owing to the good interfacial adhesion of the components. Tensile strength and elastic modulus of the NSFMLs increased with the numbers of lay-ups, while the elongation to fracture exhibited obvious declining tendency. Flexural strength and modulus of the NSFMLs were improved obviously with the increasing of stacking layers. Neutron transmission of the NSFMLs decreased obviously with increasing the number of lay-ups, owing to the increase of {sup 10}B areal density. Besides, the effect of carbon fibres on the neutron shielding performance of the NSFMLs was also taken into consideration. - Highlights: • A novel neutron shielding fibre metal laminates (NSFMLs) with different lay-ups was successfully fabricated using hot molding process. • Mechanical properties of the NSFMLs were performed in accordance with relative standards. • Neutron transmission of the NSFMLs was conducted according to the testing results. • The effect of carbon fibres on the neutron transmission of the NSFMLs was also investigated.

Development of dissimilar metal transition joint by hot bond rolling

International Nuclear Information System (INIS)

Kurokawa, Hiroyuki; Nakasuji, Kazuyuki; Kajimura, Haruhiko; Nagai, Takayuki; Takeda, Seiichiro.

1997-01-01

Metallurgically bonded transition joints which enable to connect reprocessing equipments made of superior corrosion resistant valve metals (Ti-5Ta, Zr or Ti) to stainless steel piping are required for nuclear fuel reprocessing plants. The authors have developed dissimilar transition joints made of stainless steel and Ti-5Ta, Zr or Ti with an insert metal of Ta by the hot bond rolling process of clad bars and clad pipes, using a newly developed mill called 'rotary reduction mill'. This report presents the manufacturing process of dissimilar transition joints produced from the clad pipe with three layers by the hot bond rolling. First, the method of hot bond rolling of clad pipe is proposed. Then, the mechanical and corrosion properties of the dissimilar transition joints are evaluated in detail by carrying out various tests. Finally, the rolling properties in the clad pipe method are discussed. (author)

High-Temperature Hot Air/Silane Coupling Modification of Wood Fiber and Its Effect on Properties of Wood Fiber/HDPE Composites

Directory of Open Access Journals (Sweden)

Feng Chen

2017-03-01

Full Text Available The surfaces of poplar wood fibers were modified using high-temperature hot air (HTHA treatment and silane coupling agent. The single factor test was then used to investigate the performances (e.g., the change of functional groups, polarity, cellulose crystallinity, and thermal stability of modified poplar wood fibers (mPWF through Fourier transform infrared spectrometry, X-ray diffraction and thermo-gravimetric analysis for the subsequent preparation of wood-plastic composites (WPCs. The effect of HTHA treatment conditions—such as temperature, inlet air velocity, and feed rate—on the performances of WPCs was also investigated by scanning electron microscopy and dynamic mechanical analysis. The main findings indicated that HTHA treatment could promote the hydration of mPWF and improve the mechanical properties of WPCs. Treatment temperature strongly affected the mechanical properties and moisture adsorption characteristics of the prepared composites. With the increase of treated temperature and feed rate, the number of hydroxyl groups, holocellulose content, and the pH of mPWF decreased. The degree of crystallinity and thermal stability and the storage modulus of the prepared composites of mPWF increased. However, dimensional stability and water absorption of WPCs significantly reduced. The best mechanical properties enhancement was observed with treatment temperature at 220 °C. This study demonstrated the feasibility for the application of an HTHA treatment in the WPC production industry.

Relationship between microstructure and mechanical properties in ODS materials for nuclear application

International Nuclear Information System (INIS)

De Carlan, Y.

2013-01-01

Oxide Dispersion Strengthened ferritic/martensitic alloys are developed as prospective cladding materials for future Sodium-Cooled-Fast-Reactors (GEN IV) [1]. These advanced alloys present a good resistance to irradiation and a high creep rupture strength due to a reinforcement by the homogeneous dispersion of hard nano-sized particles (such as Y 2 O 3 or YTiO). ODS alloys are elaborated by powder metallurgy, consolidated by hot extrusion and manufactured into cladding tube using the Pilger cold-rolling process [2, 3]. ODS alloys present usually low ductility and high hardness. The aim of this talk is to present the specificity of the metallurgy of ODS materials in relationship with the main mechanical properties (tensile and creep properties, toughness, transition temperature). Two types of alloys will be presented: Fe-9Cr martensitic ODS and Fe-14Cr ferritic ODS alloys. Mechanical properties of the materials depend on the metallurgical state (fine grains, recrystallized, martensitic) and very different behaviors are observed as a function of final microstructure. For example, for a Fe-9Cr ODS alloy, tempered martensite lets obtaining material with high strength whereas softened ferrite see figure 1 [4] tolerates high deformation levels. (authors)

Mechanical properties of dental resin composites by co-filling diatomite and nanosized silica particles

Energy Technology Data Exchange (ETDEWEB)

Wang Hua; Zhu Meifang [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Li Yaogang [Engineering Research Center of Advanced Glasses Manufacturing Technology, MOE, Donghua University, Shanghai 201620 (China); Zhang Qinghong, E-mail: zhangqh@dhu.edu.cn [Engineering Research Center of Advanced Glasses Manufacturing Technology, MOE, Donghua University, Shanghai 201620 (China); Wang Hongzhi, E-mail: wanghz@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China)

2011-04-08

The aim of this study was to investigate the mechanical property effects of co-filling dental resin composites with porous diatomite and nanosized silica particles (OX-50). The purification of raw diatomite by acid-leaching was conducted in a hot 5 M HCl solution at 80 deg. C for 12 h. Both diatomite and nanosized SiO{sub 2} were silanized with 3-methacryloxypropyltrimethoxysilane. The silanized inorganic particles were mixed into a dimethacrylate resin. Purified diatomite was characterized by X-ray diffraction, UV-vis diffuse reflectance spectroscopy and an N{sub 2} adsorption-desorption isotherm. Silanized inorganic particles were characterized using Fourier transform infrared spectroscopy and a thermogravimetric analysis. The mechanical properties of the composites were tested by three-point bending, compression and Vicker's microhardness. Scanning electron microscopy was used to show the cross-section morphologies of the composites. Silanization of diatomite and nanosized silica positively reinforced interactions between the resin matrix and the inorganic particles. The mechanical properties of the resin composites gradually increased with the addition of modified diatomite (m-diatomite). The fracture surfaces of the composites exhibited large fracture steps with the addition of m-diatomite. However, when the mass fraction of m-diatomite was greater than 21 wt.% with respect to modified nanosized silica (mOX-50) and constituted 70% of the resin composite by weight, the mechanical properties of the resin composites started to decline. Thus, the porous structure of diatomite appears to be a crucial factor to improve mechanical properties of resin composites.

Mechanical properties of hot-pressed SiC-TiC composites

Directory of Open Access Journals (Sweden)

Kamil Kornaus

2017-12-01

Full Text Available SiC-TiC composites, with 0, 5, 10 and 20 vol.% of TiC, were sintered by the hot-pressing technique at temperature of 2000 °C under argon atmosphere. SiC sintering process was activated by liquid phase created by the reaction between Al2O3 and Y2O3, in which it is possible to dissolve passivating oxide layers (SiO2 and TiO2 and partially SiC and TiC carbides. Microstructure observation and density measurements confirmed that the composites were dense with uniformly distributed components. Differences in thermal expansion coefficients between SiC and TiC led to complex stress state occurrence. These stresses combined with the liquid-derived separate phase between grains boundaries increased fracture toughness of the composites, which ranged from 5.8 to 6.3 MPa·m0.5. Opposite to the bending strength, fracture toughness increased with the TiC volume fraction. By means of simulation of residual thermal stresses in the composites, it was found that with the increasing volume fraction of TiC, tensile stress in TiC grains is reduced simultaneously with strong rise of compressive stresses in the matrix.

A thermo-electro-mechanical simulation model for hot wire cutting of EPS foam

DEFF Research Database (Denmark)

Petkov, Kiril; Hattel, Jesper Henri

2016-01-01

A one-dimensional thermo-electro-mechanical mathematical model describing the effects taking place within a Ni-Cr20% wire used in a hot-wire cutting process for free forming and rapid prototyping of expanded polystyrene (EPS) is investigated and simulated. The model implements and solves three semi...... cutting of EPS in contact with a cutting tool made of an electrically heated metal wire attached to a robot device. The finite difference method is used to solve the coupled equations in the two environments (domains) in which the hot-wire operates, namely air and EPS. The model is calibrated against...... experimentally obtained data. Novel findings are a transient temperature-dependent kerfwidth prediction and a relation between kerfwidth and the cutting angle as measured from the horizontal direction. These are important relations in the aim for higher geometrical accuracy of the hot-wire cutting process. (C...

Numerical simulation of the dynamic recrystallization behaviour in hot precision forging helical gears

Directory of Open Access Journals (Sweden)

Feng Wei

2015-01-01

Full Text Available In hot precision forging helical gears, the dynamic recrystallization phenomena will occur, which affect the microstructure of the formed part and in turn decide their mechanical properties. To investigate the effect of deformation temperature on the dynamic recrystallization in hot precision forging helical gears, a three dimensional (3D finite element (FE model was created by coupling the thermo-mechanical model with the microstructure evolution model developed based on the hot compressive experimental data of 20CrMnTiH steel. The hot precision forging process was simulated and the effect laws of the deformation temperature on the microstructure evolution the formed part were investigated. The results show that the dynamic recrystallization volume fraction and the average grain sizes increased with the increasing deformation temperature and the higher deformation temperature is beneficial to dynamic recrystallization and grain refinement.

Hot pressing of nanocrystalline tantalum using high frequency induction heating and pulse plasma sintering

Science.gov (United States)

Jakubowicz, J.; Adamek, G.; Sopata, M.; Koper, J. K.; Siwak, P.

2017-12-01

The paper presents the results of nanocrystalline powder tantalum consolidation using hot pressing. The authors used two different heating techniques during hot pressing: high-frequency induction heating (HFIH) and pulse plasma sintering (PPS). A comparison of the structure, microstructure, mechanical properties and corrosion resistance of the bulk nanocrystalline tantalum obtained in both techniques was performed. The nanocrystalline powder was made to start from the microcrystalline one using the high-energy ball milling process. The nanocrystalline powder was hot-pressed at 1000 °C, whereas, for comparison, the microcrystalline powder was hot pressed up to 1500 °C for proper consolidation. The authors found that during hot pressing, the powder partially reacts with the graphite die covered by boron nitride, which facilitated punches and powder displacement in the die during densification. Tantalum carbide and boride in the nanocrystalline material was found, which can improve the mechanical properties. The hardness of the HFIH and PPS nanocrystalline tantalum was as high as 625 and 615 HV, respectively. The microstructure was more uniform in the PPS nanomaterial. The corrosion resistance in both cases deteriorated, in comparison to the microcrystalline material, while the PPS material corrosion resistance was slightly better than that of the HFIH one.

Effect of zirconium addition on the microstructure and mechanical properties of 15Cr-ODS ferritic Steels consolidated by hot isostatic pressing

Energy Technology Data Exchange (ETDEWEB)

Xu, Haijian, E-mail: haijianxu@eis.hokudai.ac.jp [Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819 (China); Material Science and Engineering, Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Lu, Zheng; Wang, Dongmei; Liu, Chunming [Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819 (China)

2017-01-15

The influence of Zr addition on the microstructure and mechanical properties of mechanically alloyed (MA) ODS ferritic steels were studied in this work. The microstructure characteristics included the grain size, oxide particles number densities, size distributions, crystal structures and compositions. TEM foils measurements were complemented by studies of alloys on carbon extraction replica and focus ion beam (FIB) foils. The tensile properties were carried out at different temperatures. The microstructure and mechanical properties were analyzed and compared with nominal compositions (wt.%): Fe-15Cr-2W-0.3Y{sub 2}O{sub 3} and Fe-15Cr −2W-0.3Zr-0.3Y{sub 2}O{sub 3}. The experimental revealed that the addition of Zr increased the volume fraction of the smallest and equiaxed ferritic grains, number density of nano-oxide particles and decreased the average size of oxide particles within the ferritic matrix, promoting the formation of fine trigonal δ-phase Y{sub 4}Zr{sub 3}O{sub 12} nano-oxides and leading to the enhancement of the mechanical properties of the ODS steels.

The effect of particles in different sizes on the mechanical properties of spray formed steel composites

DEFF Research Database (Denmark)

Petersen, Kenneth; Pedersen, A. S.; Pryds, N.

2000-01-01

particle size of 46 and 134 μm were carried out with respect to their mechanical properties e.g. wear resistance and tensile strength. It was found that the addition of Al2O3 particles to the steel improves its wear properties and reduces the elongation and tensile strength of the material......The main objective of the work was to investigate the effect of addition of ceramic particles with different size distributions on the mechanical properties, e.g. wear resistance and tensile strength, of spray formed materials. The experiments were carried out in a spray-forming unit at Risø...... National Laboratory, Denmark, where composites with a low alloyed boron steel (0.2 wt.% carbon) matrix containing alumina particles were produced. A comparison between cast hot-rolled material without particles, spray formed material without particles and the spray formed composites with an average ceramic...

Mechanical and degradation property improvement in a biocompatible Mg-Ca-Sr alloy by thermomechanical processing.

Science.gov (United States)

Henderson, Hunter B; Ramaswamy, Vidhya; Wilson-Heid, Alexander E; Kesler, Michael S; Allen, Josephine B; Manuel, Michele V

2018-04-01

Magnesium-based alloys have attracted interest as a potential material to comprise biomedical implants that are simultaneously high-strength and temporary, able to provide stabilization before degrading safely and able to be excreted by the human body. Many alloy systems have been evaluated, but this work reports on improved properties through hot extrusion of one promising alloy: Mg-1.0 wt% Ca-0.5 wt%Sr. This alloy has previously demonstrated promising toxicity and degradation properties in the as-cast and rolled conditions. In the current study extrusion causes a dramatic improvement in the mechanical properties in tension and compression, as well as a low in vitro degradation rate. Microstructure (texture, second phase distribution, and grain size), bulk mechanical properties, flow behavior, degradation in simulated body fluid, and effect on osteoblast cyctotoxicity are evaluated and correlated to extrusion temperature. Maximum yield strength of 300 MPa (above that of annealed 316 stainless steel) with 10% elongation is observed, making this alloy competitive with existing implant materials. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Effect of brief heat-curing on microstructure and mechanical properties in fresh cement based mortars

International Nuclear Information System (INIS)

Ballester, P.; Hidalgo, A.; Marmol, I.; Morales, J.; Sanchez, L.

2009-01-01

The effect of temperature on fresh mortar and cement paste was evaluated by simulating the curing conditions of external buildings plastering applied under extremely hot weather. The specimens were heated at controlled temperatures in the 40-80 o C range by exposure to IR radiation over short periods. The effect of soaking for a short time was also examined. The results of compressive strength tests, scanning electron microscopy, infrared spectroscopy and mercury porosimetry helped to characterize the mechanical and physico-chemical properties of the studied sample. Early age behaviour (28 days) in neat cement was barely affected by the temperature. By contrast, exposure to high temperatures caused significant microstructural changes in the mortar. However, successive soaking over short periods was found to reactivate the mechanism of curing and restore the expected mechanical properties. Based on the results, application of cement based mortar at high temperatures is effective when followed by a short, specific soaking process.

Silicon nitride-fabrication, forming and properties

International Nuclear Information System (INIS)

Yehezkel, O.

1983-01-01

This article, which is a literature survey of the recent years, includes description of several methods for the formation of silicone nitride, and five methods of forming: Reaction-bonded silicon nitride, sintering, hot pressing, hot isostatic pressing and chemical vapour deposition. Herein are also included data about mechanical and physical properties of silicon nitride and the relationship between the forming method and the properties. (author)

Hot Surface Ignition

OpenAIRE

Tursyn, Yerbatyr; Goyal, Vikrant; Benhidjeb-Carayon, Alicia; Simmons, Richard; Meyer, Scott; Gore, Jay P.

2015-01-01

Undesirable hot surface ignition of flammable liquids is one of the hazards in ground and air transportation vehicles, which primarily occurs in the engine compartment. In order to evaluate the safety and sustainability of candidate replacement fuels with respect to hot surface ignition, a baseline low lead fuel (Avgas 100 LL) and four experimental unleaded aviation fuels recommended for reciprocating aviation engines were considered. In addition, hot surface ignition properties of the gas tu...

Robust tribo-mechanical and hot corrosion resistance of ultra-refractory Ta-Hf-C ternary alloy films.

Science.gov (United States)

Yate, Luis; Coy, L Emerson; Aperador, Willian

2017-06-08

In this work we report the hot corrosion properties of binary and ternary films of the Ta-Hf-C system in V 2 O 5 -Na 2 SO 4 (50%wt.-50%wt.) molten salts at 700 °C deposited on AISI D3 steel substrates. Additionally, the mechanical and nanowear properties of the films were studied. The results show that the ternary alloys consist of solid solutions of the TaC and HfC binary carbides. The ternary alloy films have higher hardness and elastic recoveries, reaching 26.2 GPa and 87%, respectively, and lower nanowear when compared to the binary films. The corrosion rates of the ternary alloys have a superior behavior compared to the binary films, with corrosion rates as low as 0.058 μm/year. The combination and tunability of high hardness, elastic recovery, low nanowear and an excellent resistance to high temperature corrosion demonstrates the potential of the ternary Ta-Hf-C alloy films for applications in extreme conditions.

Mechanical properties of MeV ion-irradiated SiC/SiC composites characterized by indentation technique

International Nuclear Information System (INIS)

Park, J.Y.; Park, K.H.; Kim, W.; Kishimoto, H.; Kohyama, A.

2007-01-01

Full text of publication follows: SiC/SiC composites have been considered as a structural material for advanced fusion concepts. In the core of fusion reactor, those SiC/SiC composites are experienced the complex attacks such as strong neutron, high temperature and transmuted gases. One of the vital data for designing the SiC/SiC composites to the fusion reactor is mechanical properties under the severe neutron irradiation. In this work, various SiC/SiC composites were prepared by the different fabrication processes like CVI (chemical vapor infiltration), WA-CVI (SiC whisker assisted CVI) and hot-pressed method. The expected neutron irradiation was simulated by a silicon self-ion irradiation at a DuET facility; Dual-beam for Energy Technologies, Kyoto University. The irradiation temperature were 600 deg. C and 1200 deg. C, and the irradiation does were 5 dpa and 20 dpa, respectively. The 5.1 MeV Si ions were irradiated to the intrinsic CVI-SiC, SiC whisker reinforced SiC and SiC composites produced by hot-press method. The mechanical properties like hardness, elastic modulus and fracture toughness were characterized by an indentation technique. The ion irradiation caused the increase of the hardness and fracture toughness, which was dependent on the irradiation temperature. SiC whisker reinforcement in the SiC matrix accelerated the increase of the fracture toughness by the ion irradiation. For SiC/SiC composites after the ion irradiation, this work will provide the additional data for the mechanical properties as well as the effect of SiC whisker reinforcement. (authors)

Magnetic and cytotoxic properties of hot-filament chemical vapour deposited diamond

Energy Technology Data Exchange (ETDEWEB)

Zanin, Hudson, E-mail: hudsonzanin@gmail.com [Faculdade de Engenharia Eletrica e Computacao, Departamento de Semicondutores, Instrumentos e Fotonica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N.400, CEP 13 083-852 Campinas, Sao Paulo (Brazil); Peterlevitz, Alfredo Carlos; Ceragioli, Helder Jose [Faculdade de Engenharia Eletrica e Computacao, Departamento de Semicondutores, Instrumentos e Fotonica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N.400, CEP 13 083-852 Campinas, Sao Paulo (Brazil); Rodrigues, Ana Amelia; Belangero, William Dias [Laboratorio de Biomateriais em Ortopedia, Faculdade de Ciencias Medicas, Universidade Estadual de Campinas, Rua Cinco de Junho 350 CEP 13083970, Campinas, Sao Paulo (Brazil); Baranauskas, Vitor [Faculdade de Engenharia Eletrica e Computacao, Departamento de Semicondutores, Instrumentos e Fotonica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N.400, CEP 13 083-852 Campinas, Sao Paulo (Brazil)

2012-12-01

Microcrystalline (MCD) and nanocrystalline (NCD) magnetic diamond samples were produced by hot-filament chemical vapour deposition (HFCVD) on AISI 316 substrates. Energy Dispersive X-ray Spectroscopy (EDS) measurements indicated the presence of Fe, Cr and Ni in the MCD and NCD samples, and all samples showed similar magnetisation properties. Cell viability tests were realised using Vero cells, a type of fibroblastic cell line. Polystyrene was used as a negative control for toxicity (NCT). The cells were cultured under standard cell culture conditions. The proliferation indicated that these magnetic diamond samples were not cytotoxic. - Highlights: Black-Right-Pointing-Pointer Polycrystalline diamonds doped with Fe, Cr and Ni acquire ferromagnetic properties. Black-Right-Pointing-Pointer CVD diamonds have been prepared with magnetic and semiconductor properties. Black-Right-Pointing-Pointer Micro/nanocrystalline diamonds show good cell viability with fibroblast proliferation.

Experimental studies on the production and suppression mechanism of the hot electrons produced by short wavelength laser

International Nuclear Information System (INIS)

Qi Lanying; Jiang Xiaohua; Zhao Xuewei; Li Sanwei; Zhang Wenhai; Li Chaoguang; Zheng Zhijian; Ding Yongkun

1999-12-01

The experiments on gold-disk and hohlraum and plastic hydrocarbon (CH) film targets irradiated by laser beams with wavelength 0.35 μm (Xingguang-II) and 0.53 μm (Shenguang-I) are performed. The characteristics of hot electrons are commonly deduced from spectrum of hard X-ray. Associated with the measurement of backward SRS and 3/2ω 0 , the production mechanism of hot electrons for different target type is analyzed in laser plasma with shorter wavelength. A effective way to suppress hot electrons has been found

Physicochemical and mechanical properties of paracetamol cocrystal with 5-nitroisophthalic acid.

Science.gov (United States)

Hiendrawan, Stevanus; Veriansyah, Bambang; Widjojokusumo, Edward; Soewandhi, Sundani Nurono; Wikarsa, Saleh; Tjandrawinata, Raymond R

2016-01-30

We report novel pharmaceutical cocrystal of a popular antipyretic drug paracetamol (PCA) with coformer 5-nitroisophhthalic acid (5NIP) to improve its tabletability. The cocrystal (PCA-5NIP at molar ratio of 1:1) was synthesized by solvent evaporation technique using methanol as solvent. The physicochemical properties of cocrystal were characterized by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), fourier transform infrared spectroscopy (FTIR), hot stage polarized microscopy (HSPM) and scanning electron microscopy (SEM). Stability of the cocrystal was assessed by storing them at 40°C/75% RH for one month. Compared to PCA, the cocrystal displayed superior tableting performance. PCA-5NIP cocrystal showed a similar dissolution profile as compared to PCA and exhibited good stability. This study showed the utility of PCA-5NIP cocrystal for improving mechanical properties of PCA. Copyright © 2015 Elsevier B.V. All rights reserved.

Software Simulation of Hot Tearing

DEFF Research Database (Denmark)

Andersen, S.; Hansen, P.N.; Hattel, Jesper Henri

1999-01-01

The brittleness of a solidifying alloy in a temperature range near the solidus temperature has been recognised since the fifties as the mechanism responsible for hot tearing. Due to this brittlenes, the metal will crack under even small amounts of strain in that temperature range. We see these hot...... tears in castings close to hot centres, where the level of strain is often too high.Although the hot tearing mechanism is well understood, until now it has been difficult to do much to reduce the hot tearing tendency in a casting. In the seventies, good hot tearing criteria were developed by considering...... the solidification rate and the strain rate of the hot tear prone areas. But, until recently it was only possible to simulate the solidification rate, so that the criteria could not be used effectively.Today, with new software developments, it is possible to also simulate the strain rate in the hot tear prone areas...

The effect of boron addition on microstructure and mechanical properties of biomedical Ti35Nb6Ta alloy

Energy Technology Data Exchange (ETDEWEB)

Málek, Jaroslav, E-mail: malek@ujp.cz [UJP PRAHA a.s., Nad Kamínkou 1345, 156 10 Prague, Zbraslav (Czech Republic); CTU in Prague, Faculty of Mechanical Engineering, Department of Materials Engineering, Karlovo Namesti 13, 121 35 Praha 2 (Czech Republic); Hnilica, František, E-mail: hnilica@ujp.cz [UJP PRAHA a.s., Nad Kamínkou 1345, 156 10 Prague, Zbraslav (Czech Republic); Veselý, Jaroslav, E-mail: vesely@ujp.cz [UJP PRAHA a.s., Nad Kamínkou 1345, 156 10 Prague, Zbraslav (Czech Republic); Smola, Bohumil, E-mail: smola@met.mff.cuni.cz [Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Březina, Vítězslav, E-mail: brezinavita@gmail.com [Masaryk University, Faculty of Medicine, Department of Stomathology, Komenského Náměstí 220/2, 662 43 Brno (Czech Republic); Kolařík, Kamil, E-mail: kamil.kolarik@email.cz [Faculty of Mechanical Engineering, University of West Bohemia, Univerzitní 22, 306 14 Plzeň (Czech Republic)

2014-10-15

The beta-titanium alloys are promising materials for bioapplications but their processing via melting is difficult. Coarse grains have been observed in as-cast specimens. Subsequent thermo-mechanical processing seems to be necessary in order to obtain fine-grained microstructure with better mechanical properties. The grain size can be decreased significantly by addition of small boron amount. In this work Ti–35Nb–6Ta alloy with various B additions (0, 0.05, 0.1, 0.3 and 0.5 wt.%) has been studied. Even the smallest amount of B leads to significant grain refinement in Ti–35Nb–6Ta alloy (from 1300 to about 350 μm). Slight grain refinement has been observed also after hot forging and solution treatment. TiB particles emerged in specimens due to B addition. These particles contribute to changes in mechanical properties not only in hot forged and solution treated specimens (hardness increase from 140 to 180 HV10), but also in cold swaged specimens (hardness from 230 to 250 HV10, tensile strength from 800 to 920 MPa). The hardness values can be increased up to 370 HV10 during aging at 400 °C (specimen with 0.5 wt.% B). It has been observed that specimens with low boron addition 0.05 wt.% possess no cytotoxicity. On the other hand in specimens with 0.1 wt.% B or more slight adverse effect on cytotoxicity has been observed. - Highlights: • The influence of boron on microstructure and mechanical properties has been studied. • Beta-transus temperature has been determined. • Cytotoxicity depending on boron content has been evaluated. • Possibility of final heat treatment has been determined.

Roll-to-roll hot embossing system with shape preserving mechanism for the large-area fabrication of microstructures

Science.gov (United States)

Peng, Linfa; Wu, Hao; Shu, Yunyi; Yi, Peiyun; Deng, Yujun; Lai, Xinmin

2016-10-01

Roll-to-roll (R2R) hot embossing is a promising approach to fulfilling the demands of high throughput fabrication of large-area polymeric components with micro-structure arrays which have been widely employed in the domains of optics, optoelectronics, biology, chemistry, etc. Nevertheless, the characteristic of continuous and fast forming for the R2R hot embossing process limits material flow during filling stage and results in significant springback during demolding stage. As a result, forming defects usually appear and the process window is very narrow which hinders the industrialization of this technology. This study developed a R2R hot embossing machine and proposed a shape preserving mechanism to extend the material filling time and realized the cooling effect during the demolding process. Comparative experiments were conducted on the R2R hot embossing process for micro-pyramid arrays to understand the effect of shape preserving mechanism. The influence of tension force and encapsulation angle to the forming quality was systematically analyzed. Furthermore, the influence of processing parameters has been investigated by using the one-variable-at-a-time method. Afterwards, a series of experiments based on the central composite design approach have been conducted for the analysis of variance and the establishment of empirical models of the R2R hot embossing process. As a result, the process window was extended by the shape preserving mechanism. More importantly, the feeding speed was improved from 0.5 m min-1 to 2.5 m min-1 for the large-area fabrication of micro-pyramid arrays, which is very attractive to the industrialization of this technology.

Inhibition of turbulence in inertial-confinement-fusion hot spots by viscous dissipation.

Science.gov (United States)

Weber, C R; Clark, D S; Cook, A W; Busby, L E; Robey, H F

2014-05-01

Achieving ignition in inertial confinement fusion (ICF) requires the formation of a high-temperature (>10 keV) central hot spot. Turbulence has been suggested as a mechanism for degrading the hot-spot conditions by altering transport properties, introducing colder, mixed material, or reducing the conversion of radially directed kinetic energy to hot-spot heating. We show, however, that the hot spot is very viscous, and the assumption of turbulent conditions in the hot spot is incorrect. This work presents the first high-resolution, three-dimensional simulations of National Ignition Facility (NIF) implosion experiments using detailed knowledge of implosion dynamics and instability seeds and including an accurate model of physical viscosity. We find that when viscous effects are neglected, the hot spot can exhibit a turbulent kinetic energy cascade. Viscous effects, however, are significant and strongly damp small-scale velocity structures, with a hot-spot Reynolds number in the range of only 10-100.

The microstructures and mechanical properties of Al-15Si-2.5Cu-0.5Mg/(wt%)B{sub 4}C composites produced through hot pressing technique and subjected to hot extrusion

Energy Technology Data Exchange (ETDEWEB)

Ozer, Alpay, E-mail: alpiozer@gmail.com

2016-11-01

In this study, B{sub 4}C (5, 10, and 15 wt%) particle-reinforced Ecka Alumix 231{sup ®} aluminum matrix composites were produced through the hot pressing technique. Some of these samples were subjected to hot extrusion as a secondary treatment at 4:1 ratio at a temperature of 555 °C. The obtained samples were subjected to density measurement, hardness test, microstructure analysis, and three-point bending test, and their fracture surfaces were examined. A density of over 99% was found in the samples. Al-rich solid solution and primary Si, CuAl{sub 2}, Al{sub 2}CuMg, and Mg{sub 2}Si phases in the microstructure were determined through X-ray diffraction analysis. Grain sizes were found to be 20 μm and 2 μm in the microstructures of the samples produced through hot pressing technique and of those subjected to additional hot extrusion, respectively. High hardness values were obtained in the samples subjected to hot extrusion. In these samples, wt% B{sub 4}C particle ratio and transverse rupture strength increased considerably. Furthermore, the highest compressive strain value was obtained in the 10 wt% B{sub 4}C particle-reinforced composites subjected to hot extrusion. - Highlights: • Liquid phase formed at the temperature of hot pressing and hot extrusion. • In the samples, over 99.19% density was obtained. • Average matrix grain size was measured to be 2 μm through hot extrusion. • As wt% B{sub 4}C ratio increased, transverse rupture strength values increased. • High compressive strain values were obtained in the hot extrusion samples.

Effect of nanoprecipitates and grain size on the mechanical properties of advanced structural steels

International Nuclear Information System (INIS)

Suarez, M.A.; Alvarez-Perez, M.A.; Alvarez-Fregoso, O.; Juarez-Islas, J.A.

2011-01-01

Highlights: → The composition of the steel responded positively to the thermomechanical processing. → Yield strength was increased due to micrometric grain size of 2.2 μm. → Mechanical properties were improved due to nanometric precipitates of 5 nm. → Yield strength values of the API steel were improved up to 877.9 MPa. - Abstract: The microstructure and nanometric precipitates present in advanced structured steel have been studied by high resolution transmission electron microscopy equipped with energy dispersion X-ray microanalysis, in order to relate the nanometric precipitates and grain size with the improvement of the yield strength value of the API steel. The microstructure and nanometric precipitates of the advanced steel were obtained by a combination of thermo-mechanical controlled hot rolling and accelerated cooling procedures. The API steel composition consisted of hot rolled Nb-Ti microalloyed with: 0.07C, 1.40Mn, 0.24Si, 0.020Al, 0.009P, 0.001S, 0.05Mo, 0.5Cr, 0.05Nb, 0.25Ni, 0.10Cu, 0.012Ti, 0.05N in wt%. As a result, this hot rolled steel tested at a strain rate of 5 x 10 -3 s -1 showed an improved yield strength from 798 MPa to 878 MPa due to the micrometric grain size of 2.2 μm and to the nanometric precipitates with a size of around 5 nm in the microstructure of the steel studied.

Anomalous properties of hot dense nonequilibrium plasmas

International Nuclear Information System (INIS)

Ferrante, G; Zarcone, M; Uryupin, S A

2005-01-01

A concise overview of a number of anomalous properties of hot dense nonequilibrium plasmas is given. The possibility of quasistationary megagauss magnetic field generation due to Weibel instability is discussed for plasmas created in atom tunnel ionization. The collisionless absorption and reflection of a test electromagnetic wave normally impinging on the plasma with two-temperature bi-maxwellian electron velocity distribution function are studied. Due to the wave magnetic field influence on the electron kinetics in the skin layer the wave absorption and reflection significantly depend on the degree of the electron temperature anisotropy. The linearly polarized impinging wave during reflection transforms into an elliptically polarized one. The problem of transmission of an ultrashort laser pulse through a layer of dense plasma, formed as a result of ionization of a thin foil, is considered. It is shown that the strong photoelectron distribution anisotropy yields an anomalous penetration of the wave field through the foil

Properties of hot pressed MgB2/Ti tapes

International Nuclear Information System (INIS)

Kovac, P.; Husek, I.; Melisek, T.; Fedor, J.; Cambel, V.; Morawski, A.; Kario, A.

2009-01-01

Hot axial and hot isostatic pressing was applied for single-core MgB 2 /Ti tapes. Differences in transport current density, n-exponents and critical current anisotropy are discussed and related to the grain connectivity influenced by pressing. The magnetic Hall probe scanning measurements allowed observing the isolated regions for axially hot pressed sample attributed to the longitudinally oriented cracks introduced by pressing. The highest current densities were measured for the tape subjected to hot isostatic pressing due to improved connectivity.

Effect of hot band grain size on development of textures and magnetic properties in 2.0% Si non-oriented electrical steel sheet

Energy Technology Data Exchange (ETDEWEB)

Lee, K.M. [Department of Materials Science and Engineering, Korea University, 5-1, Anam-dong, Sungbuk-Gu, Seoul 136-701 (Korea, Republic of); Huh, M.Y., E-mail: myhuh@korea.ac.kr [Department of Materials Science and Engineering, Korea University, 5-1, Anam-dong, Sungbuk-Gu, Seoul 136-701 (Korea, Republic of); Lee, H.J.; Park, J.T.; Kim, J.S. [Electrical Steel Sheet Research Group, Technical Research Laboratories, POSCO, Goedong-dong, Pohang (Korea, Republic of); Shin, E.J. [Korea Atomic Energy Research Institute, Neutron Science Division, Daejeon 305-353 (Korea, Republic of); Engler, O. [Hydro Aluminium Rolled Products GmbH, Research and Development Bonn, P.O. Box 2468, D-53014 Bonn (Germany)

2015-12-15

The effect of hot band grain size on the development of crystallographic texture and magnetic properties in non-oriented electrical steel sheet was studied. After cold rolling the samples with different initial grain sizes displayed different microstructures and micro-textures but nearly identical macro-textures. The homogeneous recrystallized microstructure and micro-texture in the sample having small grains caused normal continuous grain growth. The quite irregular microstructure and micro-texture in the recrystallized sample with large initial grain size provided a preferential growth of grains in 〈001〉//ND and 〈113〉//ND which were beneficial for developing superior magnetic properties. - Highlights: • We produced hot bands of electrical steel with different grain size but same texture. • Hot band grain size strongly affected cold rolling and subsequent annealing textures. • Homogeneous recrystallized microstructure caused normal continuous grain growth. • Irregular recrystallized microstructure led to selective growth of <001>//ND grains. • Hot band with large grains was beneficial for superior magnetic properties.

The effect of additional elements on the magnetic properties of hot-rolled Nd-Fe-B alloys

International Nuclear Information System (INIS)

Chang, W.C.; Nakamura, H.; Paik, C.R.; Sugimoto, S.; Okada, M.; Homma, M.

1992-01-01

The magnetic properties of hot-rolled Nd 16 Fe bal. B 6 M 1.5 (M = Cu, Ga and Al) and Nd 16 Fe 76 B 5.5 Ga 1.5 Al 1 alloys were investigated, in order to study the role of additive elements in improving the magnetic properties in the Nd-Fe-B system. It is found that the original grain size of Cu, Ga or Ga-Al added alloys is much finer than that of the ternary and Al added alloys. But the grain size is almost identical for all the alloys after hot-rolling at 1000degC with 90% reduction in thickness. The coercivity of hot-rolled alloys with Cu, Ga or Ga-Al addition is not improved as was expected, because Nd-rich liquid phase in these alloys is very easily squeezed out during high-reduction-ratio rolling. Less quantity and nonuniform distribution of Nd-rich phase between distributed grains are believed to be the main reasons to depress the effect on the grain boundary smoothing. This effect is not the same as those observed in the Pr-Fe-B system. The highest magnetic properties achieved in this study are B r = 10 kG, i H c = 8.2 kOe, (BH) max = 18.5 MGOe for the Nd 16 Fe 76.5 B 6 Al 1.5 alloy. (orig.)

Influence of purity level on the mechanical properties of hot isostatically pressed beryllium

International Nuclear Information System (INIS)

Odegard, B.C. Jr.

1979-09-01

The procurement of a quantity of ultra-pure beryllium powder combined with special handling from powder to billet form resulted in the fabrication of high purity beryllium. The mechanical properties of these billets were contrasted to those of commercial grade billets to determine the influence of impurities and powder processing. The tensile test results show that the strength values are primarily dependent on the grain size in a behavior predictable by the Hall-Petch relationship. Only a fraction of the strength differential can be attributed to metallic impurities in solution. The grain size is controlled by the powder size distribution. The ductility is dominated by both grain size and oxide content. The fine grained, low oxide billets exhibited the highest ductilities. There is evidence to suggest that oxide distribution has a large influence on the ductility. The fracture toughness was highest for the high purity beryllium billets

Improvisation of mechanical and electrical properties of Cu by reinforcing MWCNT using modified electro-co-deposition process

Science.gov (United States)

Belgamwar, Sachin U.; Sharma, N. N.

2018-04-01

Multi-walled Carbon nanotubes–copper (MWCNT/Cu) composite powders with variable MWCNT content were synthesized by modified electro-co-deposition method. The electro-co-deposited MWCNT/Cu powders were consolidated by conventional compaction and sintering process. The consolidated products were then hot rolled and cold drawn to fine wires. The MWCNT/Cu composite wire samples were characterized for electrical and mechanical properties. We have been able to achieve an increase of around 8% in electrical conductivity of the form wires repeatedly. It has been observed that there was gradual improvement in the properties with reinforcement of MWCNT in the copper matrix. The betterment of electrical property has been achieved with simultaneous improvement in mechanical properties of the wire. The yield strength of MWCNT/Cu composite wire was found to be four times and the tensile strength two times greater than that of pure copper. The improved properties are attributed to the proper distribution of MWCNTs in the copper matrix and excellent interfacial bonding between MWCNT and composite copper fabricated by the modified method.

Study of the microstructure evolution of ferritic stainless ODS steels during hot working

International Nuclear Information System (INIS)

Karch, Abdellatif

2014-01-01

The production of ODS steels involves a powder consolidation step usually using the hot extrusion (HE) process. The anisotropic properties of extruded materials, especially in the ODS ferritic grades (≥wt%12Cr), need a better understanding of the metallurgical phenomena which may occur during HE and lead to the observed microstructure. The hot working behavior of these materials is of particular interest. The methodology of this work includes the microstructure analysis after interrupted hot extrusion, hot torsion and hot compression (1000-1200 C) tests of ferritic steels with 14%Cr and different amounts in Ti and Y 2 O 3 . The microstructure evolution during hot extrusion process is associated with continuous dynamic recrystallization (CDRX). It leads to the creation of new grains by the formation of low angle boundaries, and then the increase of their misorientation under plastic deformation. The investigations highlight also the role of precipitation on the kinetics of this mechanism; it remains incomplete in the presence of fine and dense nano-precipitates. After hot deformation in torsion and compression, it is noticed that both precipitates and temperature deformation have a significant impact on the deformation mechanisms and microstructure evolution. Indeed, the CDRX is dominant when temperature and amount of reinforcement are limited. However, when they are increased, limited microstructure evolution is observed. In this case, the results are interpreted through a mechanism of strain accommodation at grain boundaries, with low dislocation activity in the bulk of the grains. (author) [fr

Ultrasonic assisted hot metal powder compaction.

Science.gov (United States)

Abedini, Rezvan; Abdullah, Amir; Alizadeh, Yunes

2017-09-01

Hot pressing of metal powders is used in production of parts with similar properties to wrought materials. During hot pressing processes, particle rearrangement, plastic deformation, creep, and diffusion are of the most effective powder densification mechanisms. Applying ultrasonic vibration is thought to result in great rates of densification and therefore higher efficiency of the process is expected. This paper deals with the effects of power ultrasonic on the densification of AA1100 aluminum powder under constant applied stress. The effects of particle size and process temperature on the densification behavior are discussed. The results show that applying ultrasonic vibration leads to an improved homogeneity and a higher relative density. Also, it is found that the effect of ultrasonic vibration is greater for finer particles. Copyright © 2016 Elsevier B.V. All rights reserved.

Defect, Microstructure, and Mechanical Property of Ti-6Al-4V Alloy Fabricated by High-Power Selective Laser Melting

Science.gov (United States)

Cao, Sheng; Chen, Zhuoer; Lim, Chao Voon Samuel; Yang, Kun; Jia, Qingbo; Jarvis, Tom; Tomus, Dacian; Wu, Xinhua

2017-12-01

To improve the selective laser melting (SLM) productivity, a high laser power and accordingly adjusted parameters are employed to facilitate a high build rate. Three distinct processing strategies with incremental build rate are developed for SLM Ti-6Al-4V. Various types of defects are investigated. Further studies were carried out by heat-treatment and hot isostatic pressing to evaluate the influence of microstructure and porosity on mechanical properties. The anisotropic mechanical property in horizontally and vertically build samples were observed, which was attributable to the columnar grains and spatial arrangement of defects. Regardless of anisotropy, a post-SLM heat-treatment at 800°C for 2 h produces a combined high strength and ductility.

LAMI - a planned Brazilian facility to investigate the mechanical and physical properties of structural materials under irradiation

International Nuclear Information System (INIS)

Andrade, Arnaldo H.P.; Lobo, Raquel M.

2011-01-01

The LAMI (Laboratorio de Materiais Irradiados) is a hot laboratory designed to the characterization of irradiated structural material and will constitute one of the main installations of the Brazilian Multipurpose Reactor (RMB). The strong points of LAMI are: to contribute, through theoretical and experimental investigations, to the development of knowledge in materials science in order to be able to predict the evolution of the physical and mechanical material properties under service conditions (irradiation, thermomechanical solicitation, influence of the environment, etc); to characterize the properties of the materials used in the nuclear industry in order to determine their performance and to be able to predict their life expectancy; to establish, maintain and make use of the database generated by these data and to provide expertise on industrial components, in particular to investigate strain or rupture mechanisms. The test materials can be irradiated or not, and originate from surveillance programs, experimental neutron irradiations or simulated irradiation with charged particles. The main line of LAMI will have 10 shielded hot cells. The building also will have an area dedicated to micro and nano structural materials analysis. The mechanical characterization to be carried out within LAMI includes mechanical tests on irradiated materials, comprehension of behavior and damage processes and the incorporation of the test data results in a data bank for capitalization of test results. Planned materials to be tested are going to be metallic alloys used in industrial and experimental reactor: pressure vessel steels, internal stainless steels, austeno-ferritic steels, zirconium alloys and aluminum alloys. (author)

Studies on improvement of mechanical properties of Kenaf-reinforced polypropylene composites

International Nuclear Information System (INIS)

Sarifah Hanisah Syed Abd Aziz; Khairul Zaman Mohd Dahlan

2006-01-01

At present, research in composite materials is being directed at using natural fibres instead of synthetic fibres. Kenaf which is extensively grown in the Far East including Malaysia, has been identified as a bast (stem) fibre with significant market potential. In this work, long and random kenaf fibres were used in the as-received condition and alkalized with a 0.06 M NaOH solution. They were combined with polypropylene thin sheets, sandwiched between layers of kenaf fibres and hot-pressed to form natural fibre composites. The mechanical properties of the composites were investigated to observe the effect of fibre alignment, fibre treatment, the addition of coupling agent and pre-irradiation method used. A general trend was observed whereby alkalized and long fibre composites gave higher flexural modulus and flexural strength compared with random mat and untreated fibres. The long fibre composites also gave a higher work of fracture. However, the correlation between fibre surface treatment and the work of fracture was less clear. The addition of coupling agent at 1% showed a slight improvement on the mechanical performance of the composites whereas pre-irradiation on the polypropylene pellets and fibres before the composite is manufactured showed significant improvement on the mechanical properties. However, the method of moulding used need to be improved to optimize the performance of the composites. (Author)

Effects of high shock pressures and pore morphology on hot spot mechanisms in HMX

Science.gov (United States)

Springer, H. K.; Tarver, C. M.; Bastea, S.

2017-01-01

The shock initiation and detonation behavior of heterogeneous solid explosives is governed by its microstructure and reactive properties. New additive manufacturing techniques offer unprecedented control of explosive microstructures previously impossible, enabling us to develop novel explosives with tailored shock sensitivity and detonation properties. Since microstructure-performance relationships are not well established for explosives, there is little material design guidance for these manufacturing techniques. In this study, we explore the effects of high shock pressures (15-38 GPa) with long shock durations and different pore morphologies on hot spot mechanisms in HMX. HMX is chosen as the model material because we have experimental data on many of the chemical-thermal-mechanical properties required for pore collapse simulations. Our simulations are performed using the multi-physics arbitrary Lagrangian Eulerian finite element hydrocode, ALE3D, with Cheetah-based models for the unreacted and the product equation-of-states. We use a temperature-dependent specific heat with the unreacted equation-of-state and a temperature-dependent viscosity model to ensure accurate shock temperatures for subsequent chemistry. The Lindemann Law model is used for shock melting in HMX. In contrast to previous pore collapse studies at lower shock pressures (≤10 GPa) in HMX and shorter post-collapse burning times, our calculations show that shock melting occurs above 15 GPa due to higher bulk heating and a prominent elongated ("jet-like") hot spot region forms at later times. The combination of the elongated, post-collapse hot spot region and the higher bulk heating with increasing pressure dramatically increases the growth rate of reaction. Our calculations show that the reaction rate, dF/dt, increases with increasing shock pressure. We decompose the reaction rate into ignition ((dF/dt)ig) and growth ((dF/dt)gr) phases to better analyze our results. We define the ignition phase

Effects of asphalt rejuvenator on thermal and mechanical properties on oxidized hot mixed asphalt pavements

Science.gov (United States)

Farace, Nicholas A.; Buttlar, William G.; Reis, Henrique

2016-04-01

The utilization of asphalt rejuvenator, and its effectiveness for restoring thermal and mechanical properties was investigated via Disk-shaped Compact Tension (DC(T)) and acoustic emission (AE) testing for determining mechanical properties and embrittlement temperatures of the mixtures. During the DC(T) testing the fracture energies and peak loads were used to measure the resistance of the rejuvenated asphalt to low temperature cracking. The AE testing monitored the acoustic emission activity while the specimens were cooled from room temperature to -40 °C to estimate the temperature at which thermal cracking began (i.e. the embrittlement temperature). First, a baseline response was obtained by obtaining the mechanical and thermal response of virgin HMA samples and HMA samples that had been exposed to oxidative aging for 36 hours at 135°C. The results showed the virgin samples had much higher peak loads and fracture energies than the 36 hours aged samples. Acoustic Emission showed similar results with the virgin samples having embrittlement temperatures 10 °C cooler than the 36 hours aged specimens. Then, overaged for 36 hours specimens were treated different amounts of rejuvenator (10%, 15%, and 20% by weight of binder content) and left to dwell for increased amount of time periods varying from one to eight weeks. It was observed that the AE results showed an improvement of embrittlement temperature with increasing with the dwell times. The 8 weeks specimens had cooler embrittlement temperatures than the virgin specimens. Finally, the low temperature effects on fracture energy and peak load of the rejuvenated asphalt was investigated. Rejuvenator was applied (10% by weight of binder) to specimens aged 36 hours at 135 °C, and the dwell time was varied from 1 to 4 weeks. The results showed that the peak loads were restored to levels of the virgin specimens, and the fracture energies improved to levels beyond that of the virgin specimens. The results also showed a

Hot-pressing steatite bodies; Obtencion de eseatita por prensado en caliente

Energy Technology Data Exchange (ETDEWEB)

Aparicio Arroyo, E

1967-07-01

Requirements for some special nuclear engineering ceramic shapes are: big size, impervious, dimensional accuracy and good mechanical and dielectric properties. Limitations of te conventional methods and advantages of te hot pressing techniques for the manufacturing of these shapes are discussed. Hot pressing characteristics of a certain steatite powder are studied. Occurrence of an optimum densification temperature just above the tale decomposition range is found. Experimental data show that the height/diameter ratio of the specimen has no effect on the sintering conditions. Increasing darkness from the graphite mould is detected above the optimum temperature. The hot-pressed steatite is compared with a fired dry-pressed sample of the same composition. (Author) 13 refs.

Effect of phosphorus additions on hot pressing temperature and some properties of WC-Co hard alloys

International Nuclear Information System (INIS)

Dotsenko, V.M.; Simkina, Eh.S.; Tsypin, N.V.

1977-01-01

Results of studies on the effect of phosphorus additions on hot pressing temperature and some properties of VK6 and VK15 hard alloys are given. It is shown that alloying of hard alloys with 3-6 wt % phosphorus gives opportunity to lower substantially (for 200-300 deg) their hot pressing temperature. Hardness and density of alloys with phosphorus do not practically change. Some decrease of strength and wear-resistance characteristics is observed which is obviously connected with irregular distribution of phosphorus in the alloy

Mechanical properties of carbon fibre-reinforced polymer/magnesium alloy hybrid laminates

Science.gov (United States)

Zhou, Pengpeng; Wu, Xuan; Pan, Yingcai; Tao, Ye; Wu, Guoqing; Huang, Zheng

2018-04-01

In this study, we prepared fibre metal laminates (FMLs) consisting of high-modulus carbon fibre-reinforced polymer (CFRP) prepregs and thin AZ31 alloy sheets by using hot-pressing technology. Tensile and low-velocity impact tests were performed to evaluate the mechanical properties and fracture behaviour of the magnesium alloy-based FMLs (Mg-FMLs) and to investigate the differences in the fracture behaviour between the Mg-FMLs and traditional Mg-FMLs. Results show that the Mg-FMLs exhibit higher specific tensile strength and specific tensile modulus than traditional Mg-FMLs and that the tensile behaviour of the Mg-FMLs is mainly governed by the CFRP because of the combination of high interlaminar shear properties and thin magnesium alloy layers. The Mg-FMLs exhibit excellent bending stiffness. Hence, no significant difference between the residual displacement d r and indentation depth d i , and the permanent deformation is mainly limited to a small zone surrounding the impact location after the impact tests.

Fabrication and Analysis of the Wear Properties of Hot-Pressed Al-Si/SiCp + Al-Si-Cu-Mg Metal Matrix Composite

Science.gov (United States)

Bang, Jeongil; Oak, Jeong-Jung; Park, Yong Ho

2016-01-01

The aim of this study was to characterize microstructures and mechanical properties of aluminum metal matrix composites (MMC's) prepared by powder metallurgy method. Consolidation of mixed powder with gas atomized Al-Si/SiCp powder and Al-14Si-2.5Cu-0.5Mg powder by hot pressing was classified according to sintering temperature and sintering time. Sintering condition was optimized using tensile properties of sintered specimens. Ultimate tensile strength of the optimized sintered specimen was 228 MPa with an elongation of 5.3% in longitudinal direction. In addition, wear properties and behaviors of the sintered aluminum-based MMC's were analyzed in accordance with vertical load and linear speed. As the linear speed and vertical load of the wear increased, change of the wear behavior occurred in order of oxidation of Al-Si matrix, formation of C-rich layer, Fe-alloying to matrix, and melting of the specimen

Martensite and bainite in steels: transformation mechanism and mechanical properties

International Nuclear Information System (INIS)

Bhadeshia, H.K.D.H.

1997-01-01

Many essential properties of iron alloys depend on what actually happens when one allotropic form gives way to another, i.e. on the mechanism of phase change. The dependence of the mechanical properties on the atomic mechanism by which bainite and martensite grow is the focus of this paper. The discussion is illustrated in the context of some common engineering design parameters, and with a brief example of the inverse problem in which the mechanism may be a function of the mechanical properties. (orig.)

Studies on the mechanical properties of woven jute fabric reinforced poly(l-lactic acid composites

Directory of Open Access Journals (Sweden)

G.M. Arifuzzaman Khan

2016-01-01

Full Text Available Development of ecofriendly biocomposites to replace non-biodegradable synthetic fiber composites is the main objective of this study. To highlight the biocomposites as a perfect replacement, the plain woven jute fabric (WJF reinforced poly(l-lactic acid (PLLA composites were prepared by the hot press molding method. The influence of woven structure and direction on the mechanical properties i.e. tensile, flexural and impact properties was investigated. The average tensile strength (TS, tensile modulus (TM, flexural strength (FS, flexural modulus (FM, and impact strength (IS of untreated woven jute composite (in warp direction were improved about 103%, 211%, 95.2%, 42.4% and 85.9%, respectively and strain at maximum tensile stress for composite samples was enhanced by 11.7%. It was also found that the strengths and modulus of composites in warp direction are higher than those in weft direction. WJF composites in warp and weft directions presented superior mechanical properties than non-woven jute fabric (NWJF composites. Chemical treatment of jute fabric through benzoylation showed a positive effect on the properties of composites. Morphological studies by SEM demonstrated that better adhesion between the treated fabric and PLLA was achieved.

A study on the mechanism of stress corrosion cracking of duplex stainless steels in hot alkaline-sulfide solution

Science.gov (United States)

Chasse, Kevin Robert

Duplex stainless steels (DSS) generally have superior strength and corrosion resistance as compared to most standard austenitic and ferritic stainless grades owing to a balanced microstructure of austenite and ferrite. As a result of having favorable properties, DSS have been selected for the construction of equipment in pulp and paper, chemical processing, nuclear, oil and gas as well as other industries. The use of DSS has been restricted in some cases because of stress corrosion cracking (SCC), which can initiate and grow in either the ferrite or austenite phase depending on the environment. Thorough understanding of SCC mechanisms of DSS in chloride- and hydrogen sulfide-containing solutions has been useful for material selection in many environments. However, understanding of SCC mechanisms of DSS in sulfide-containing caustic solutions is limited, which has restricted the capacity to optimize process and equipment design in pulp and paper environments. Process environments may contain different concentrations of hydroxide, sulfide, and chloride, altering corrosion and SCC susceptibility of each phase. Crack initiation and growth behavior will also change depending on the relative phase distribution and properties of austenite and ferrite. The role of microstructure and environment on the SCC of standard grade UNS S32205 and lean grade UNS S32101 in hot alkaline-sulfide solution were evaluated in this work using electrochemical, film characterization, mechanical testing, X-ray diffraction, and microscopy techniques. Microstructural aspects, which included residual stress state, phase distribution, phase ratio, and microhardness, were related to the propensity for SCC crack initiation in different simulated alkaline pulping liquors at 170 °C. Other grades of DSS and reference austenitic and superferritic grades of stainless steel were studied using exposure coupons for comparison to understand compositional effects and individual phase susceptibility

Mechanical properties of rubberwood oriented strand lumber (OSL: The effect of strand length

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Buhnnum Kyokong

2005-09-01

Full Text Available Effect of strand length on mechanical properties (tension, compression and bending of oriented strand lumber (OSL made of rubberwood (Hevea brasiliensis Muell. Arg. was reported. Three strand lengths of 50 mm, 100 mm, and 150 mm with 1 mm thickness and 15 mm width were used. The strands were mixed with 5% pMDI glue (weight basis in a tumble mixer. The OSL specimens were formed by hot pressing process of unidirectionally aligned strands. Average specific gravity and moisture content were 0.76 and 8.34%, respectively. Tension and compression tests were carried out for directions both parallel and perpendicular to grain while bending test was performed only in parallel direction. Ultimate stresses and moduli of elasticity were examined from the stress-strain curves. It was found that for the parallel-to-grain direction, the longer strand OSL gave higher strength. The role of the strand length did not appear for the direction normal to the grain. The relationship between the mechanical properties of OSL and strand length was well described by the modified Hankinson formula.

Study of the properties of plasma deposited layers of nickel-chrome-aluminium-yttrium coatings resistant to oxidation and hot corrosion

Directory of Open Access Journals (Sweden)

Mihailo R. Mrdak

2012-04-01

Full Text Available The aim of this study was to examine the properties of Ni22Cr10Al1Y layers in order to obtain optimal structural - mechanical properties with the optimization of depositing parameters. Powder was deposited by the atmospheric plasma spray (APS process with the current intensity of 600, 700 and 800A, with a corresponding plasma gun power supply of 22KW, 34KW and 28KW. The evaluation of the Ni22Cr10Al1Y coating layers was made on the basis of their microhardness, tensile strength and microstructure performance. The best performance was obtained in the layers deposited with 800A and the 34KW plasma gun power supply. The coating with the best characteristics was tested to oxidation in the furnace for heat treatment without a protective atmosphere at 1100°C for one hour. The examination of the morphology of Ni22Cr10Al1Y powder particles was carried out on the SEM (Scanning Electron Microscope as well as the EDS analysis of the best layers. The microstructure of the deposited coating layers was examined with a light microscope. The microstructure analysis was performed according to the TURBOMECA standard. The mechanical properties of layers were evaluated by the method HV0.3 for microhardness and by tensile testing for bond strength. The research has shown that plasma gun power supply significantly affects the mechanical properties and microstructure of coatings that are of crucial importance for the protection of components exposed to high temperature oxidation and hot corrosion.

Evaluación de las propiedades mecánicas de una mezcla densa en caliente modificada con asfaltita/Mechanical Properties Evaluation of a hot Asphalt Mixture Modified with Asphaltite

Directory of Open Access Journals (Sweden)

Hugo Alexander Rondón Quintana

2012-12-01

Full Text Available El trabajo evaluó en laboratorio la resistencia mecánica bajo carga monotónica, el módulo resiliente y la resistencia a la deformación permanente que experimenta una mezcla asfáltica cuando se modifica con una asfaltita. Adicionalmente, fue evaluada durante dos años, la influencia del medio ambiente de la ciudad de Bogotá D.C., sobre las propiedades mecánicas de la mezcla modificada. Se concluye que la resistencia mecánica de la mezcla asfáltica modificada incrementa en comparación con la convencional. La tendencia general de las mezclas con el tiempo de exposición al medio ambiente de Bogotá D.C., es experimentar un aumento en los valores de rigidez debido principalmente a procesos de endurecimiento por envejecimiento del ligante asfáltico. Sin embargo, para el caso de las mezclas modificadas y fabricadas con CA 60-70 en los primeros cinco meses de exposición, la rigidez disminuye.The strength under monotonic load, resilient modulus and rutting were evaluated on a hot-mix asphalt (HMAmodified with a natural sphaltite. Additionally, the influence of the environmental conditions of BogotáD.C., was evaluated during two years on the mechanical properties of a modified asphalt mixture. The results show that the mechanical properties evaluated were better for the HMA mixes modified in compared with those with neat asphalts. The asphaltite produces higher mechanical resistance in HMA. The general tendency of the mixtures is increase the modulus with time due to aging of the asphalt cement. However, modified mixtures with AC 60- 70, decrease in stiffness during the first months.

Effect of mechanical alloying atmosphere on the microstructure and Charpy impact properties of an ODS ferritic steel

International Nuclear Information System (INIS)

Oksiuta, Z.; Baluc, N.

2009-01-01

Two types of oxide dispersion strengthened (ODS) ferritic steels, with the composition of Fe-14Cr-2W-0.3Ti-0.3Y 2 O 3 (in weight percent), have been produced by mechanically alloying elemental powders of Fe, Cr, W, and Ti with Y 2 O 3 particles either in argon atmosphere or in hydrogen atmosphere, degassing at various temperatures, and compacting the mechanically alloyed powders by hot isostatic pressing. It was found in particular that mechanical alloying in hydrogen yields a significant reduction in oxygen content in the materials, a lower dislocation density, and a strong improvement in the fast fracture properties of the ODS ferritic steels, as measured by Charpy impact tests.

Thermoelectric properties of p-type (Bi{sub 1{minus}x}Sb{sub x}){sub 2}Te{sub 3} fabricated by mechanical alloying process

Energy Technology Data Exchange (ETDEWEB)

Jung, B Y; Choi, J S; Oh, T S; Hyun, D B

1997-07-01

Thermoelectric properties of polycrystalline (Bi{sub 1{minus}x}Sb{sub x}){sub 2}Te{sub 3} (0.75 {le} x {le} 0.85), fabricated by mechanical alloying and hot pressing methods, have been investigated. Formation of (Bi{sub 0.25}Sb{sub 0.75}){sub 2}Te{sub 3} alloy powder was completed by mechanical alloying for 5 hours at ball-to-material ratio of 5:1, and processing time for (Bi{sub 1{minus}sub x}Sb{sub x}){sub 2}Te{sub 3} formation increased with Sb{sub 2}Te{sub 3} content x. When (Bi{sub 0.25}Sb{sub 0.75}){sub 2}Te{sub 3} was hot pressed at temperatures ranging from 300 C to 550 C for 30 minutes, figure-of-merit increased with hot pressing temperature and maximum value of 2.8 x 10{sup {minus}3}/K could be obtained by hot pressing at 550 C. When hot pressed at 550 C, (Bi{sub 0.2}Sb{sub 0.8}){sub 2}Te{sub 3} exhibited figure-of-merit of 2.92 x 10{sup {minus}3}/K, which could be improved to 2.97 x 10{sup {minus}3}/K with addition of 1 wt% Sb as acceptor dopant.

Mechanical properties and deformation behavior of Al/Al7075, two-phase material

International Nuclear Information System (INIS)

Sherafat, Z.; Paydar, M.H.; Ebrahimi, R.; Sohrabi, S.

2010-01-01

In the present study, mechanical properties and deformation behavior of Al/Al7075, two-phase material were investigated. The two-phase materials were fabricated by mixing commercially pure Al powder with Al7075 chips and consolidating the mixture through hot extrusion process at 500 o C. Mechanical properties and deformation behavior of the fabricated samples were evaluated using tensile and compression tests. A scanning electron microscope was used to study the fracture surface of the samples including different amount of Al powder, after they were fractured in tensile test. The results of the tensile and compression tests showed that with decreasing the amount of Al powder, the strength increases and ductility decreases. Calculation of work hardening exponent (n) indicated that deformation behavior does not follow a regular trend. In a way that the n value was approved to be variable and a strong function of strain and Al powder wt% of the sample. The results of the fractography studies indicate that the type of fracture happened changes from completely ductile to nearly brittle by decreasing the wt% of Al powder from 90% to 40%.

Effect of Pre-Oxidation Treatment of Nano-SiC Particulates on Microstructure and Mechanical Properties of SiC/Mg-8Al-1Sn Composites Fabricated by Powder Metallurgy Combined with Hot Extrusion.

Science.gov (United States)

Li, Chuan-Peng; Wang, Zhi-Guo; Zha, Min; Wang, Cheng; Yu, Hong-Chen; Wang, Hui-Yuan; Jiang, Qi-Chuan

2016-11-26

Nano-SiC particulates (n-SiC p ) reinforced Mg-8Al-1Sn (AT81) composites with different pre-oxidation parameters were fabricated by powder metallurgy (P/M) process combined with hot extrusion. The effects of pre-oxidization treatment of n-SiC p on the microstructure and tensile properties of 0.5 vol % n-SiC p /AT81 composites were investigated accordingly. The distribution of n-SiC p with different pre-oxidation parameters was homogeneous in the composites. Moreover, it was found that a thin MgAl₂O₄ layer formed at the interface when the n-SiC p were pre-oxidized at 1073 K for 2 h, while the MgAl₂O₄ layer became much thicker with pre-oxidization temperature increasing to 1273 K for 2 h. After an appropriate pre-oxidization treatment of n-SiC p at 1073 K for 2 h, the as-extruded 0.5 vol % n-SiC p /AT81 composites exhibited an enhanced strength. It was found that the yield strength (YS) and ultimate tensile strength (UTS) increased from 168 MPa and 311 MPa to 255 MPa and 393 MPa compared with the as-extruded AT81 alloy, reflecting 51.8% and 26.4% increments, respectively. The improvement of mechanical properties should be mainly attributed to the grain refinement and homogeneous distribution of n-SiC p in the composites. Moreover, a well-bonded interface and the formation of an appropriate amount of interfacial product (MgAl₂O₄) benefited the material's mechanical properties.

Size Effect Studies on Tensile Tests for Hot Stamping Steel

Science.gov (United States)

Chen, Xiaodu; Li, Yuanyuan; Han, Xianhong; Zhang, Junbo

2018-02-01

Tensile tests have been widely used to determine basic mechanical properties of materials. However, the properties measured may be related to geometrical factors of the tested samples especially for high-strength steels; this makes the properties' definitions and comparisons difficult. In this study, a series of tensile tests of ultra-high-strength hot-stamped steel were performed; the geometric shapes and sizes as well as the cutting direction were modified. The results demonstrate that the hot-stamped parts were isotropic and the cutting direction had no effect; the measured strengths were practically unrelated to the specimen geometries, including both size and shape. The elongations were slightly related to sample sizes within the studied range but highly depended on the sample shape, represented by the coefficient K. Such phenomena were analyzed and discussed based on microstructural observations and fracture morphologies. Moreover, two widely used elongation conversion equations, the Oliver formula and Barba's law, were introduced to verify their applicability, and a new interpolating function was developed and compared.

Properties of hot luminous stars; Proceedings of the First Boulder-Munich Workshop, Boulder, CO, Aug. 6-11, 1988

International Nuclear Information System (INIS)

Garmany, C.D.

1990-01-01

Various papers on the properties of hot luminous stars are presented. Individual topics addressed include: problems in photometry of early-type stars; digital optical morphology of OB spectra; massive-star content of the Magellanic Clouds; observations of massive OB stars; LSS 3074, a new double-lined early O-type binary; non-LTE line blanketing with elements 1-28; non-LTE analysis of four PG1159 stars; rescaling method for model atmospheres of hot stars; stellar wind albedo effects on hot photospheres; atomic data and models for hot star abundance determinations; ring nebulae analysis as a probe for WR atmospheres; coordinated observations of P Cygni; radiation-driven winds of hot luminous stars; winds of O stars: velocities and ionization; methods of radiative transfer in expanding atmospheres; mass loss from extragalactic O stars; H-alpha observations of O- and B-type stars; applicability of steady models for hot-star winds; mass of the O6Iaf star HD 153919; stellar winds in Beta Lyrae; models of WR stars; observational abundances of WR stars, the all-variable WC7 binary HD193793

Preliminary evaluation of microstructure and mechanical properties on low activation ferritic steels

International Nuclear Information System (INIS)

Hsu, C.Y.; Lechtenberg, T.A.

1985-01-01

Radioactive waste disposal has become a primary concern for the selection of materials for the structural components for fusion reactors. One way to minimize this potential environmental problem is to use structural materials in which the induced radioactivity decays quickly to levels that allow for near-surface disposal under 10CFR61 rules. The primary objective of this work is to develop low activation ferritic steels that exhibit mechanical and physical properties approximately equivalent to the HT-9 and 9Cr-1Mo steels, but which only contain elements that would permit near-surface disposal under 10CFR61 after exposure to fusion neutrons. A preliminary evaluation of the microstructure and mechanical properties of a 9Cr-2.5W-0.3V-0.15C (GA3X) low activation ferritic steel has been performed. An optimum heat treatment condition has been defined for GA3X steel. The properties and microstructure of the quenched and tempered specimens were characterized via hardness measurement and optical metallographic observation. The hot-microhardness and ductility parameter measurements were used to estimate the tensile properties at elevated temperatures. The estimated tensile strengths of GA3X steel at elevated temperatures are comparable to both 9Cr-1Mo and the modified 9Cr-1Mo steels. These preliminary results are encouraging in that they suggest that suitable low activation alloys can be successfully produced in this ferritic alloy class

Effect of segregations on mechanical properties and crack propagation in spring steel

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B. Žužek

2015-10-01

Full Text Available Considerable efforts have been made over the last decades to improve performance of spring steels, which would increase the service time of springs and also allow vehicles weight reduction. There are different possibilities of improving properties of spring steels, from modifying the chemical composition of steels to optimizing the deformation process and changing the heat treatment parameters. Another way of improving steel properties is through refining the microstructure and reducing amount of inclusions. Therefore, the focus of the current investigation was to determine the effect of more uniform and cleaner microstructure obtained through electro-slag remelting (ESR of steel on the mechanical and dynamic properties of spring steel, with special focus on the resistance to fatigue crack propagation. Effect of the microstructure refinement was evaluated in terms of tensile strength, elongation, fracture and impact toughness, and fatigue resistance under bending and tensile loading. After the mechanical tests the fracture surfaces of samples were analyzed using scanning electron microscope (SEM and the influence of microstructure properties on the crack propagation and crack propagation resistance was studied. Investigation was performed on hot rolled, soft annealed and vacuum heat treated 51CrV4 spring steel produced by conventional continuous casting and compared with steel additional refined through ESR. Results shows that elimination of segregations and microstructure refinement using additional ESR process gives some improvement in terms of better repeatability and reduced scattering, but on the other hand it has negative effect on crack propagation resistance and fatigue properties of the spring steel.

Influence of WC addition on the microstructure and mechanical properties of NbC-Co cermets

International Nuclear Information System (INIS)

Huang, S.G.; Li, L.; Van der Biest, O.; Vleugels, J.

2007-01-01

NbC-24.5 wt.% Co cermets with up to 30 wt.% WC were obtained by solid state hot pressing at 1300 o C under a pressure of 45 MPa for 10 min and pressureless liquid phase sintering at 1360 o C for 60 min. The effect of WC addition on the microstructure and mechanical properties of NbC-Co based cermets was investigated. The hot pressed cermets exhibited interconnected and irregular niobium carbide (NbC) or (Nb,W)C grains, whereas the shape of the NbC grains changed from faceted with rounded corners to spherical, as the WC content increased in the pressureless sintered cermets. The undissolved WC increased with increasing WC addition. A clear core/rim structure was observed in the hot pressed cermets with 10-30 wt.% WC additions, whereas this structure was gradually eliminated when pressureless sintering. The hardness remains nearly constant whereas the fracture toughness slightly increases with increasing WC addition. The dissolution of WC in the Co binder and NbC grains, as well as the formation of a solid solution (Nb,W)C phase were supported by thermodynamic calculations

Selected mechanical properties of aluminum composite materials reinforced with SiC particles

Directory of Open Access Journals (Sweden)

A. Kurzawa

2008-07-01

Full Text Available This work presents the results of research concerning influence of ceramic particles’ content of silicon carbide on selected mechanical properties of type AW-AlCu4Mg2Mn - SiC composite materials. Composites produced of SiC particles with pressure infiltration method of porous preform and subject to hot plastic forming in the form of open die forging were investigated. The experimental samples contained from 5% up to 45% of reinforcing SiC particles of 8÷10μm diameter. Studies of strength properties demonstrated that the best results, in case of tensile strength as well as offset yield strength, might be obtained while applying reinforcement in the amount of 20-25% vol. of SiC. Application of higher than 25% vol. contents of reinforcing particles leads to gradual strength loss. The investigated composites were characterized by very high functional properties, such as hardness and abrasive wear resistance, whose values increase strongly with the increase of reinforcement amount. The presented results of the experiments shall allow for a more precise component selection of composite materials at the stage of planning and design of their properties.

The Influence of Irradiation and Accelerated Aging on the Mechanical and Tribological Properties of the Graphene Oxide/Ultra-High-Molecular-Weight Polyethylene Nanocomposites

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Guodong Huang

2016-01-01

Full Text Available Graphene oxide/ultra-high-molecular-weight polyethylene (GO/UHMWPE nanocomposite is a potential and promising candidate for artificial joint applications. However, after irradiation and accelerated aging, the mechanical and tribological behaviors of the nanocomposites are still unclear and require further investigation. GO/UHMWPE nanocomposites were successfully fabricated using ultrasonication dispersion, ball-milling, and hot-pressing process. Then, the nanocomposites were irradiated by gamma ray at doses of 100 kGy. Finally, GO/UHMWPE nanocomposites underwent accelerated aging at 80°C for 21 days in air. The mechanical and tribological properties of GO/UHMWPE nanocomposites have been evaluated after irradiation and accelerated aging. The results indicated that the incorporation of GO could enhance the mechanical, wear, and antiscratch properties of UHMWPE. After irradiation, these properties could be further enhanced, compared to unirradiated ones. After accelerated aging, however, these properties have been significantly reduced when compared to unirradiated ones. Moreover, GO and irradiation can synergistically enhance these properties.

Bio-Inspired nacre-like nanolignocellulose-poly (vinyl alcohol)-TiO2 composite with superior mechanical and photocatalytic properties.

Science.gov (United States)

Chen, Yipeng; Wang, Hanwei; Dang, Baokang; Xiong, Ye; Yao, Qiufang; Wang, Chao; Sun, Qingfeng; Jin, Chunde

2017-05-12

Nacre, the gold standard for biomimicry, provides an excellent example and guideline for assembling high-performance composites. Inspired by the layered structure and extraordinary strength and toughness of natural nacre, nacre-like nanolignocellulose/poly (vinyl alcohol)/TiO 2 composites possessed the similar layered structure of natural nacre were constructed through hot-pressing process. Poly (vinyl alcohol) and TiO 2 nanoparticles have been used as nanofillers to improve the mechanical performance and synchronously endow the superior photocatalytic activity of the composites. This research would be provided a promising candidate for the photooxidation of volatile organic compounds also combined with outstanding mechanical property.

Hot embossing and mechanical punching of biodegradable microcontainers for oral drug delivery

DEFF Research Database (Denmark)

Petersen, Ritika Singh; Mahshid, Rasoul; Andersen, Nis Korsgaard

2015-01-01

A process has been developed to fabricate discrete three-dimensional microcontainers for oral drug delivery application in Poly-L-Lactic Acid (PLLA) polymer. The method combines hot embossing for the definition of holes in a PLLA film and mechanical punching to penetrate the polymer layer around...... and shapes of microcontainers. Finally, the process is compatible with roll-to-roll processing that could lead to low cost high volume production. © 2014 Elsevier B.V. All rights reserved....

Effects of Deep Cryogenic Treatment on the Wear Resistance and Mechanical Properties of AISI H13 Hot-Work Tool Steel

Science.gov (United States)

Çiçek, Adem; Kara, Fuat; Kıvak, Turgay; Ekici, Ergün; Uygur, İlyas

2015-11-01

In this study, a number of wear and tensile tests were performed to elucidate the effects of deep cryogenic treatment on the wear behavior and mechanical properties (hardness and tensile strength) of AISI H13 tool steel. In accordance with this purpose, three different heat treatments (conventional heat treatment (CHT), deep cryogenic treatment (DCT), and deep cryogenic treatment and tempering (DCTT)) were applied to tool steel samples. DCT and DCTT samples were held in nitrogen gas at -145 °C for 24 h. Wear tests were conducted on a dry pin-on-disk device using two loads of 60 and 80 N, two sliding velocities of 0.8 and 1 m/s, and a wear distance of 1000 m. All test results showed that DCT improved the adhesive wear resistance and mechanical properties of AISI H13 steel. The formation of small-sized and uniformly distributed carbide particles and the transformation of retained austenite to martensite played an important role in the improvements in the wear resistance and mechanical properties. After cleavage fracture, the surfaces of all samples were characterized by the cracking of primary carbides, while the DCT and DCTT samples displayed microvoid formation by decohesion of the fine carbides precipitated during the cryo-tempering process.

Graphite and boron carbide composites made by hot-pressing

International Nuclear Information System (INIS)

Miyazaki, K.; Hagio, T.; Kobayashi, K.

1981-01-01

Composites consisting of graphite and boron carbide were made by hot-pressing mixed powders of coke carbon and boron carbide. The change of relative density, mechanical strength and electrical resistivity of the composites and the X-ray parameters of coke carbon were investigated with increase of boron carbide content and hot-pressing temperature. From these experiments, it was found that boron carbide powder has a remarkable effect on sintering and graphitization of coke carbon powder above the hot-pressing temperature of 2000 0 C. At 2200 0 C, electrical resistivity of the composite and d(002) spacing of coke carbon once showed minimum values at about 5 to 10 wt% boron carbide and then increased. The strength of the composite increased with increase of boron carbide content. It was considered that some boron from boron carbide began to diffuse substitutionally into the graphite structure above 2000 0 C and densification and graphitization were promoted with the diffusion of boron. Improvements could be made to the mechanical strength, density, oxidation resistance and manufacturing methods by comparing with the properties and processes of conventional graphites. (author)

Micro–macro-characterisation and modelling of mechanical properties of gas metal arc welded (GMAW) DP600 steel

Energy Technology Data Exchange (ETDEWEB)

Ramazani, A., E-mail: ali.ramazani@iehk.rwth-aachen.de [Department of Ferrous Metallurgy, RWTH Aachen University, D-52072 Aachen (Germany); Mukherjee, K. [Department of Ferrous Metallurgy, RWTH Aachen University, D-52072 Aachen (Germany); Abdurakhmanov, A. [Welding and Joining Institute, RWTH Aachen University, D-52072 Aachen (Germany); Prahl, U. [Department of Ferrous Metallurgy, RWTH Aachen University, D-52072 Aachen (Germany); Schleser, M.; Reisgen, U. [Welding and Joining Institute, RWTH Aachen University, D-52072 Aachen (Germany); Bleck, W. [Department of Ferrous Metallurgy, RWTH Aachen University, D-52072 Aachen (Germany)

2014-01-01

Dual-phase (DP) steels show combined high strength and adequate formability. However, during welding, their microstructural feature of dispersion of hard martensite islands in the soft ferrite matrix is lost and the properties deteriorate. The current research aims to study the mechanical properties of the welded joint, taking into account the effect of features of all regions, such as microstructure, chemical composition and the area fraction, on the macroscopic mechanical properties of the welded joint. Hot rolled DP 600 steel was gas metal arc welded (GMAW) and tensile specimens were made with a welded joint. In the heat-affected zone (HAZ), the microstructure varied from bainite to coarse grained ferrite and tempered martensite. Chemical composition of every quantified region in the welded specimen was also identified using electron probe microanalysis (EPMA). Macromechanical FE modelling was employed to simulate the mechanical properties of the welded tensile specimen. 2D representative volume elements (RVE) for different parts of the welded region were constructed from real microstructure. 2D simulated flow curves were corrected to 3Ds using a developed correlation factor. Finally, the tensile test of welded material with inhomogeneous morphology was simulated and good agreement between experimental and predicted flow curve was achieved.

Micro–macro-characterisation and modelling of mechanical properties of gas metal arc welded (GMAW) DP600 steel

International Nuclear Information System (INIS)

Ramazani, A.; Mukherjee, K.; Abdurakhmanov, A.; Prahl, U.; Schleser, M.; Reisgen, U.; Bleck, W.

2014-01-01

Dual-phase (DP) steels show combined high strength and adequate formability. However, during welding, their microstructural feature of dispersion of hard martensite islands in the soft ferrite matrix is lost and the properties deteriorate. The current research aims to study the mechanical properties of the welded joint, taking into account the effect of features of all regions, such as microstructure, chemical composition and the area fraction, on the macroscopic mechanical properties of the welded joint. Hot rolled DP 600 steel was gas metal arc welded (GMAW) and tensile specimens were made with a welded joint. In the heat-affected zone (HAZ), the microstructure varied from bainite to coarse grained ferrite and tempered martensite. Chemical composition of every quantified region in the welded specimen was also identified using electron probe microanalysis (EPMA). Macromechanical FE modelling was employed to simulate the mechanical properties of the welded tensile specimen. 2D representative volume elements (RVE) for different parts of the welded region were constructed from real microstructure. 2D simulated flow curves were corrected to 3Ds using a developed correlation factor. Finally, the tensile test of welded material with inhomogeneous morphology was simulated and good agreement between experimental and predicted flow curve was achieved

Preparation of Baking-Free Brick from Manganese Residue and Its Mechanical Properties

Directory of Open Access Journals (Sweden)

Ping Wang

2013-01-01

Full Text Available The increasing amount of waste residue produced during the electrolytic preparation process of manganese has nowadays brought about serious environmental problems. The research on utilization of manganese slag has been a hot spot around the world. The utilization of manganese slag is not only environment friendly, but also economically feasible. In the current work, a summarization of the main methods to produced building materials from manganese slag materials was given. Baking-free brick, a promising building material, was produced from manganese slag with the addition of quicklime and cement. The physical properties, chemical composition, and mechanical performances of the obtained samples were measured by several analyses and characterization methods. Then the influence of adding materials and molding pressure during the preparation of baking-free brick samples on their compressive strength properties was researched. It is concluded that the baking-free brick prepared from manganese residue could have excellent compressive strength performance under certain formula.

Influence of Plastic Deformation on Martensitic Transformation During Hot Stamping of Complex Structure Auto Parts

Science.gov (United States)

Shen, Yuhan; Song, Yanli; Hua, Lin; Lu, Jue

2017-04-01

The ultra-high strength steel auto parts manufactured by hot stamping are widely applied for weight reduction and safety improvement. During the hot stamping process, hot forming and quenching are performed in one step wherein plastic deformation and phase transformation simultaneously take place and affect each other. Thereinto, the influence of deformation on martensitic transformation is of great importance. In the present paper, the influence of plastic deformation on martensitic transformation during hot stamping of complex structure auto parts was investigated. For this purpose, a B-pillar reinforced panel in B1500HS steel was manufactured by hot stamping, and the process was simulated by finite element software based on a thermo-mechanical-metallurgical coupled model. Considering various deformation degrees, the microstructures and mechanical properties at four typical locations of the hot stamped B-pillar reinforced panel were detected. The results show that the martensitic content and the microhardness increase with the increase in the deformation amount. There are two reasons causing this phenomenon: (1) the increase in mechanical driving force and (2) the increased probability of the martensitic nucleation at crystal defects. The x-ray diffraction analysis indicates the carbon enrichment in retained austenite which results from the carbon diffusion during the low-carbon martensite formation. Furthermore, the carbon content decreases with the increase in the deformation amount, because the deformation of austenite suppresses the carbon diffusion.

Fiscal 1981 Sunshine Project research report. Research on underground reinjection mechanism of hot water; 1981 nendo nessui no chika kangen mechanism no chosa kenkyu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1982-03-01

This report summarizes the fiscal 1981 research result on the behavior and flow mechanism of underground reinjected hot water, and the effect of reinjected hot water on the ground. In the tracer survey in Takinoue area, Iwate prefecture, the re-upwelling rate and mixing rate of reinjected hot water were lower than those in previous surveys, showing the smaller effect of hot water on productivity. In Nigori-Gawa area, Hokkaido, natural conditions prior to industrial production and reinjection were observed by tracer survey. In the simulation research, it was confirmed that the hydraulic structural model and analysis technique established by previous researches are effective for new production and reinjection systems different from previous ones enough. On observation of minute earthquakes, study was made on the effect of reinjected hot water on the ground in Takinoue area. In Nigori-Gawa area, the data were collected under natural conditions prior to industrial production and reinjection through minute earthquake observations. (NEDO)

Microstructure and mechanical properties of Ti–22Al–25Nb alloy fabricated by vacuum hot pressing sintering

Energy Technology Data Exchange (ETDEWEB)

Jia, Jianbo, E-mail: jiajianbohit@163.com [National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); School of Mechanical Engineering, Beihua University, Jilin 132021 (China); Zhang, Kaifeng; Jiang, Shaosong [National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China)

2014-10-20

A study has been undertaken to verify the feasibility of using a powder metallurgy (P/M) approach to fabricate Ti–22Al–25Nb alloys. Pre-alloyed powders with a nominal composition of Ti–22Al–25Nb (at%) obtained by argon atomization were sieved to the spherical size less than 180 μm and used for the fabrication of P/M Ti–22Al–25Nb alloys via hot pressing in vacuum. Vacuum hot pressing sintering was carried out in a temperature range of 950–1200 °C with a pressure of 35 MPa for 1 h followed by furnace cooling. Microstructure and phase composition examinations of the as-atomized powders and hot pressed (HP'ed) samples were conducted by applying optical microscopy, back-scatter electron imaging and X-ray diffraction analysis. Tensile tests were studied at room temperature and 650 °C, respectively. The results showed that all HP'ed samples were composed of coarse equiaxed B2 grains, fine lamellar O phase inside the B2 grains, and some α{sub 2} along B2 grain boundaries. The elongations of HP'ed samples were less than 3.95%, indicating the bad ductility at room temperature. However, the elongations were improved as the tensile temperature increased to 650 °C. The sample sintered at 1050 °C exhibited a better ductility with the elongation of 7.97% at 650 °C than that of other samples.

Powder metallurgy Al–6Cr–2Fe–1Ti alloy prepared by melt atomisation and hot ultra-high pressure compaction

International Nuclear Information System (INIS)

Dám, Karel; Vojtěch, Dalibor; Průša, Filip

2013-01-01

Al--6Cr--2Fe--1Ti alloy was prepared by melt atomisation into rapidly solidified powder. The powder was compacted using uniaxial hot compression at an ultra-high pressure (6 GPa). The samples were pressed at 300, 400 and 500 °C. The structure, mechanical properties and thermal stability were examined and compared with those of the commercially available Al--12Si--1Cu--1Mg--1Ni casting alloy, which is considered thermally stable. It was shown that the hot compression at ultra-high pressure results in a compact and pore-free material with excellent mechanical properties. The elevated pressing temperatures were found to be effective at increasing the mechanical stability after applying the ultra-high pressure. The results of thermal stability testing revealed that the mechanical properties do not change significantly at high temperature, even after 100 h of annealing at 400 °C. In addition, the Al--6Cr--2Fe--1Ti alloy exhibited very good creep resistance. A comparison between the commercial Al--12Si--1Cu--1Mg--1Ni alloy and the powder metallurgy alloy shows that this alloy has significantly better mechanical properties and thermal stability.

Powder metallurgy Al-6Cr-2Fe-1Ti alloy prepared by melt atomisation and hot ultra-high pressure compaction

Energy Technology Data Exchange (ETDEWEB)

Dam, Karel, E-mail: Karel.Dam@vscht.cz [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Vojtech, Dalibor; Prusa, Filip [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)

2013-01-10

Al--6Cr--2Fe--1Ti alloy was prepared by melt atomisation into rapidly solidified powder. The powder was compacted using uniaxial hot compression at an ultra-high pressure (6 GPa). The samples were pressed at 300, 400 and 500 Degree-Sign C. The structure, mechanical properties and thermal stability were examined and compared with those of the commercially available Al--12Si--1Cu--1Mg--1Ni casting alloy, which is considered thermally stable. It was shown that the hot compression at ultra-high pressure results in a compact and pore-free material with excellent mechanical properties. The elevated pressing temperatures were found to be effective at increasing the mechanical stability after applying the ultra-high pressure. The results of thermal stability testing revealed that the mechanical properties do not change significantly at high temperature, even after 100 h of annealing at 400 Degree-Sign C. In addition, the Al--6Cr--2Fe--1Ti alloy exhibited very good creep resistance. A comparison between the commercial Al--12Si--1Cu--1Mg--1Ni alloy and the powder metallurgy alloy shows that this alloy has significantly better mechanical properties and thermal stability.

Hot-Gas Filter Ash Characterization Project

Energy Technology Data Exchange (ETDEWEB)

Swanson, M.L.; Hurley, J.P.; Dockter, B.A.; O`Keefe, C.A.

1997-07-01

Large-scale hot-gas filter testing over the past 10 years has revealed numerous cases of cake buildup on filter elements that has been difficult, if not impossible, to remove. At times, the cake can blind or bridge between candle filters, leading to filter failure. Physical factors, including particle-size distribution, particle shape, the aerodynamics of deposition, and system temperature, contribute to the difficulty in removing the cake, but chemical factors such as surface composition and gas-solid reactions also play roles in helping to bond the ash to the filters or to itself. This project is designed to perform the research necessary to determine the fuel-, sorbent-, and operations-related conditions that lead to blinding or bridging of hot-gas particle filters. The objectives of the project are threefold: (1) Determine the mechanisms by which a difficult-to-clean ash is formed and how it bridges hot-gas filters (2) Develop a method to determine the rate of bridging based on analyses of the feed coal and sorbent, filter properties, and system operating conditions and (3) Suggest and test ways to prevent filter bridging.

Mechanical properties of rock at high temperatures

International Nuclear Information System (INIS)

Kinoshita, Naoto; Abe, Tohru; Wakabayashi, Naruki; Ishida, Tsuyoshi.

1997-01-01

The laboratory tests have been performed in order to investigate the effects of temperature up to 300degC and pressure up to 30 MPa on the mechanical properties of three types of rocks, Inada granite, Sanjoume andesite and Oya tuff. The experimental results indicated that the significant differences in temperature dependence of mechanical properties exist between the three rocks, because of the difference of the factors which determine the mechanical properties of the rocks. The effect of temperature on the mechanical properties for the rocks is lower than that of pressure and water content. Temperature dependence of the mechanical properties is reduced by increase in pressure in the range of pressure and temperature investigated in this paper. (author)

Application of powder metallurgy and hot rolling processes for manufacturing aluminum/alumina composite strips

Energy Technology Data Exchange (ETDEWEB)

Zabihi, Majed, E-mail: m.zabihi@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Toroghinejad, Mohammad Reza, E-mail: toroghi@cc.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Shafyei, Ali, E-mail: shafyei@cc.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

2013-01-10

In this study, aluminum matrix composites (AMC) with 2, 4, 6 and 10 wt% alumina were produced using powder metallurgy (PM), mechanical milling (MM) and vacuum hot pressing (VHP) techniques; then, this was followed by the hot-rolling process. During hot rolling, AMCs with 6 and 10 wt% Al{sub 2}O{sub 3} were fractured whereas strip composites with 2 and 4 wt% Al{sub 2}O{sub 3} were produced successfully. Microstructure and mechanical properties of the samples were investigated by optical and scanning electron microscopes and tensile and hardness tests, respectively. Microscopic evaluations of the hot-rolled composites showed a uniform distribution of alumina particles in the aluminum matrix. It was found that with increasing alumina content in the matrix, tensile strength (TS) and hardness increased and the percentage of elongation also decreased. Scanning electron microscope (SEM) was used to investigate aluminum/alumina interfaces and fracture surfaces of the hot rolled specimens after tensile test. SEM observations demonstrated that the failure mode in the hot-rolled Al-2 wt% Al{sub 2}O{sub 3} composite strips is a typical ductile fracture, while the failure mode was shear ductile fracture with more flat surfaces in Al-4 wt% Al{sub 2}O{sub 3} strips.

Microstructure evolution and mechanical properties of a particulate reinforced magnesium matrix composites forged at elevated temperatures

International Nuclear Information System (INIS)

Deng, K.K.; Wu, K.; Wang, X.J.; Wu, Y.W.; Hu, X.S.; Zheng, M.Y.; Gan, W.M.; Brokmeier, H.G.

2010-01-01

SiCp/AZ91 magnesium matrix composite was fabricated by stir casting. The as-cast ingots were cut into cylindrical billets, and then forged at different temperatures (320, 370, 420, 470 and 520 deg. C) at a constant RAM speed of 15 mm/s with 50% reduction. The microstructure evolution of the composites during forging was investigated by optical microscope, scanning electron microscope, and transmission electron microscope. The texture of the forged composites was measured by neutron diffraction. Mechanical properties of the composite at different forging temperatures were tested by tensile tests at room temperature. It was found that a strong basal plane texture formed during forging, and the intensity of basal plane texture weakened as forging temperatures increased. The particle distribution in the composite was significantly improved by hot forging. Typical microstructures were obtained after forging at different temperatures and the composite with different microstructures offered different mechanical properties during tensile test.

Evidence of thermal conduction depression in hot coronal loops

Science.gov (United States)

Wang, Tongjiang; Ofman, Leon; Sun, Xudong; Provornikova, Elena; Davila, Joseph

2015-08-01

Slow magnetoacoustic waves were first detected in hot (>6 MK) flare loops by the SOHO/SUMER spectrometer as Doppler shift oscillations in Fe XIX and Fe XXI lines. These oscillations are identified as standing slow-mode waves because the estimated phase speeds are close to the sound speed in the loop and some cases show a quarter period phase shift between velocity and intensity oscillations. The observed very rapid excitation and damping of standing slow mode waves have been studied by many authors using theories and numerical simulations, however, the exact mechanisms remain not well understood. Recently, flare-induced longitudinal intensity oscillations in hot post-flare loops have been detected by SDO/AIA. These oscillations have the similar physical properties as SUMER loop oscillations, and have been interpreted as the slow-mode waves. The multi-wavelength AIA observations with high spatio-temporal resolution and wide temperature coverage allow us to explore the wave excitation and damping mechanisms with an unprecedented detail to develope new coronal seismology. In this paper, we present accurate measurements of the effective adiabatic index (γeff) in the hot plasma from the electron temperature and density wave signals of a flare-induced longitudinal wave event using SDO/AIA data. Our results strikingly and clearly reveal that thermal conduction is highly depressed in hot (˜10 MK) post-flare loops and suggest that the compressive viscosity is the dominant wave damping mechanism which allows determination of the viscosity coefficient from the observables by coronal seismology. This new finding challenges our current understanding of thermal energy transport in solar and stellar flares, and may provide an alternative explanation of long-duration events and enhance our understand of coronal heating mechanism. We will discuss our results based on non-ideal MHD theory and simulations. We will also discuss the flare trigger mechanism based on magnetic topology

The preparation and mechanical properties of carbon–carbon/lithium–aluminum–silicate composite joints

International Nuclear Information System (INIS)

Li, Ke-zhi; Wang, Jie; Ren, Xiao-bin; Li, He-jun; Li, Wei; Li, Zhao-qian

2013-01-01

Highlights: ► First study to join carbon cloth laminated C–C composites to LAS glass–ceramics. ► First study on the flexural property of C–C/LAS joints at different temperatures. ► The joint flexural strength at 800 °C can increase 14.1% than at room temperature. ► A quasi-ductile fracture behavior can be found in the C–C/LAS joints. -- Abstract: Silica carbide modified carbon cloth laminated C–C composites have been successfully joined to lithium–aluminum–silicate (LAS) glass–ceramics using magnesium–aluminum–silicate (MAS) glass–ceramics as interlayer by vacuum hot-press technique. The microstructure, mechanical properties and fracture mechanism of C–C/LAS composite joints were investigated. SiC coating modified the wettability between C–C composites and LAS glass–ceramics. Three continuous and homogenous interfaces (i.e. C–C/SiC, SiC/MAS and MAS/LAS) were formed by element interdiffusions and chemical reactions, which lead to a smooth transition from C–C composites to LAS glass–ceramics. The C–C/LAS joints have superior flexural property with a quasi-ductile behavior. The average flexural strength of C–C/LAS joints can be up to 140.26 MPa and 160.02 MPa at 25 °C and 800 °C, respectively. The average shear strength of C–C/LAS joints achieves 21.01 MPa and the joints are apt to fracture along the SiC/MAS interface. The high retention of mechanical properties at 800 °C makes the joints to be potentially used in a broad temperature range as structural components.

The Effects of Carbon Nanotubes on the Mechanical and Wear Properties of AZ31 Alloy

Directory of Open Access Journals (Sweden)

Mingyang Zhou

2017-12-01

Full Text Available Carbon nanotube (CNT-reinforced AZ31 matrix nanocomposites were successfully fabricated using a powder metallurgy method followed by hot extrusion. The influence of CNTs on microstructures, mechanical properties, and wear properties were systematically investigated by optical microscope (OM, scanning electron microscope (SEM, X-ray diffraction (XRD, hardness test, tensile test, and wear test. The results revealed that the nanocomposites showed a slightly smaller grain size compared with the matrix and uniform distribution that CNTs could achieve at proper content. As a result, the addition of CNTs could weaken basal plane texture. However, the yield strength and ultimate tensile strength of the composites were enhanced as the amount of CNTs increased up to 2.0 wt. %, reaching maximum values of 241 MPa (+28.2% and 297 MPa (+6.1%, respectively. The load transfer mechanism, Orowan mechanism, and thermal mismatch mechanism played important roles in the enhancement of the yield strength, and several classical models were employed to predict the theoretical values. The effect of CNT content on the friction coefficient and weight loss of the nanocomposites was also studied. The relationships between the amount of CNTs, the friction coefficient, and weight loss could be described by the exponential decay model and the Boltzmann model, respectively.

Effects of interface roughness on the annealing behaviour of laminated Ti-Al composite deformed by hot rolling

DEFF Research Database (Denmark)

Du, Y.; Fan, G.H.; Yu, Tianbo

2015-01-01

A laminated Ti-Al composite has been fabricated by hot compaction and hot rolling of alternate layers of commercial purity Ti and Al sheets with a thickness of 200 μm. The hot compaction temperature was 500˚C and in a following step the composite has been reduced 50% in thickness by hot rolling....... The fully consolidated composite has been annealed at 300˚C and 500˚C for different length of time. As a result of the differences in crystal structure and mechanical properties between Ti and Al protrusions and retrusions formed at the interface. A heterogeneous interface has thereby been created...

Weld Metallurgy and Mechanical Properties of High Manganese Ultra-high Strength Steel Dissimilar Welds

Science.gov (United States)

Dahmen, Martin; Lindner, Stefan; Monfort, Damien; Petring, Dirk

The increasing demand for ultra-high strength steels in vehicle manufacturing leads to the application of new alloys. This poses a challenge on joining especially by fusion welding. A stainless high manganese steel sheet with excellent strength and deformation properties stands in the centre of the development. Similar and dissimilar welds with a metastable austenitic steel and a hot formed martensitic stainless steel were performed. An investigation of the mixing effects on the local microstructure and the hardness delivers the metallurgical features of the welds. Despite of carbon contents above 0.4 wt.% none of the welds have shown cracks. Mechanical properties drawn from tensile tests deliver high breaking forces enabling a high stiffness of the joints. The results show the potential for the application of laser beam welding for joining in assembly of structural parts.

THE MECHANICAL GREENHOUSE: BURIAL OF HEAT BY TURBULENCE IN HOT JUPITER ATMOSPHERES

International Nuclear Information System (INIS)

Youdin, Andrew N.; Mitchell, Jonathan L.

2010-01-01

The intense irradiation received by hot Jupiters suppresses convection in the outer layers of their atmospheres and lowers their cooling rates. 'Inflated' hot Jupiters, i.e., those with anomalously large transit radii, require additional sources of heat or suppressed cooling. We consider the effect of forced turbulent mixing in the radiative layer, which could be driven by atmospheric circulation or by another mechanism. Due to stable stratification in the atmosphere, forced turbulence drives a downward flux of heat. Weak turbulent mixing slows the cooling rate by this process, as if the planet were irradiated more intensely. Stronger turbulent mixing buries heat into the convective interior, provided the turbulence extends to the radiative-convective boundary. This inflates the planet until a balance is reached between the heat buried into and radiated from the interior. We also include the direct injection of heat due to the dissipation of turbulence or other effects. Such heating is already known to slow planetary cooling. We find that dissipation also enhances heat burial from mixing by lowering the threshold for turbulent mixing to drive heat into the interior. Strong turbulent mixing of heavy molecular species such as TiO may be necessary to explain stratospheric thermal inversions. We show that the amount of mixing required to loft TiO may overinflate the planet by our mechanism. This possible refutation of the TiO hypothesis deserves further study. Our inflation mechanism requires a deep stratified layer that only exists when the absorbed stellar flux greatly exceeds the intrinsic emitted flux. Thus, it would be less effective for more luminous brown dwarfs and for longer period gas giants, including Jupiter and Saturn.

FE-simulation of hot forging with an integrated heat treatment with the objective of residual stress prediction

Science.gov (United States)

Behrens, Bernd-Arno; Chugreeva, Anna; Chugreev, Alexander

2018-05-01

Hot forming as a coupled thermo-mechanical process comprises numerous material phenomena with a corresponding impact on the material behavior during and after the forming process as well as on the final component performance. In this context, a realistic FE-simulation requires reliable mathematical models as well as detailed thermo-mechanical material data. This paper presents experimental and numerical results focused on the FE-based simulation of a hot forging process with a subsequent heat treatment step aiming at the prediction of the final mechanical properties and residual stress state in the forged component made of low alloy CrMo-steel DIN 42CrMo4. For this purpose, hot forging experiments of connecting rod geometry with a corresponding metallographic analysis and x-ray residual stress measurements have been carried out. For the coupled thermo-mechanical-metallurgical FE-simulations, a special user-defined material model based on the additive strain decomposition method and implemented in Simufact Forming via MSC.Marc solver features has been used.

EFFECT OF HARDENER ON MECHANICAL PROPERTIES OF CARBON FIBRE REINFORCED PHENOLIC RESIN COMPOSITES

Directory of Open Access Journals (Sweden)

S. SULAIMAN

2008-04-01

Full Text Available In this paper the effect of hardener on mechanical properties of carbon reinforced phenolic resin composites is investigated. Carbon fibre is one of the most useful reinforcement materials in composites, its major use being the manufacture of components in the aerospace, automotive, and leisure industries. In this study, carbon fibres are hot pressed with phenolic resin with various percentages of carbon fibre and hardener contents that range from 5-15%. Composites with 15% hardener content show an increase in flexural strength, tensile strength and hardness. The ultimate tensile strength (UTS, flexural strength and hardness for 15% hardener are 411.9 MPa, 51.7 MPa and 85.4 HRR respectively.

Ablation resistance and mechanical/conductive properties of ZrB{sub 2} reinforced carbon based composites

Energy Technology Data Exchange (ETDEWEB)

Li, X.T.; Shi, J.L.; Zhang, H.; Zhang, G.B.; Guo, Q.G.; Liu, L. [Chinese Academy of Sciences, Taiyuan (China)

2007-02-15

Zirconium diboride reinforced carbon (ZrB{sub 2}/C) particulate composites are prepared from petroleum coke, coal tar pitch, and ZrB{sub 2} powder by hot-pressing. The ablation, mechanical, thermal, and electrical properties of the composites are studied. Results show that the composites have excellent flexural strength and thermal conductivity, with highest values reaching 131 MPa and 161 W/mK for a 10% ZrB{sub 2} addition in raw materials. The electrical resistivity reduces rapidly with increasing amount of ZrB{sub 2}. The values of mass and linear ablation rates are lower in the composites than those measured for pure carbon, decreasing with increasing ZrB{sub 2} content, confirming that these materials are promising for ultrahigh temperature materials. Correlations between properties and microstructure of the composites are also discussed.

Structure and Mechanical Properties of Friction Stir Weld Joints of Magnesium Alloy AZ31

Science.gov (United States)

Nagasawa, T.; Otsuka, M.; Yokota, T.; Ueki, T.

The applicability of friction stir welding to hot rolled sheet of commercial magnesium alloy AZ31 plates has been investigated. Friction stir weld joint showed mechanical strength comparable to that of base material, though the ductility remained at one half of that of the latter. The results are consistent with the microstructure which is characterized by a fine grained bond layer bounded by-intermediate grained base metals. It is found that both anodizing treatment and insertion of aluminum foil between batting faces do not degrade the joint properties at all. The results suggest that friction stir welding can be potentially applied to magnesium alloy.

Fluid mechanics in dentinal microtubules provides mechanistic insights into the difference between hot and cold dental pain.

Science.gov (United States)

Lin, Min; Luo, Zheng Yuan; Bai, Bo Feng; Xu, Feng; Lu, Tian Jian

2011-03-23

Dental thermal pain is a significant health problem in daily life and dentistry. There is a long-standing question regarding the phenomenon that cold stimulation evokes sharper and more shooting pain sensations than hot stimulation. This phenomenon, however, outlives the well-known hydrodynamic theory used to explain dental thermal pain mechanism. Here, we present a mathematical model based on the hypothesis that hot or cold stimulation-induced different directions of dentinal fluid flow and the corresponding odontoblast movements in dentinal microtubules contribute to different dental pain responses. We coupled a computational fluid dynamics model, describing the fluid mechanics in dentinal microtubules, with a modified Hodgkin-Huxley model, describing the discharge behavior of intradental neuron. The simulated results agreed well with existing experimental measurements. We thence demonstrated theoretically that intradental mechano-sensitive nociceptors are not "equally sensitive" to inward (into the pulp) and outward (away from the pulp) fluid flows, providing mechanistic insights into the difference between hot and cold dental pain. The model developed here could enable better diagnosis in endodontics which requires an understanding of pulpal histology, neurology and physiology, as well as their dynamic response to the thermal stimulation used in dental practices.

Double-sided laser beam welded T-joints for aluminum-lithium alloy aircraft fuselage panels: Effects of filler elements on microstructure and mechanical properties

Science.gov (United States)

Han, Bing; Tao, Wang; Chen, Yanbin; Li, Hao

2017-08-01

In the current work, T-joints consisting of 2.0 mm thick 2060-T8/2099-T83 aluminum-lithium alloys for aircraft fuselage panels have been fabricated by double-sided fiber laser beam welding with different filler wires. A new type wire CW3 (Al-6.2Cu-5.4Si) was studied and compared with conventional wire AA4047 (Al-12Si) mainly on microstructure and mechanical properties. It was found that the main combined function of Al-6.2%Cu-5.4%Si in CW3 resulted in considerable improvements especially on intergranular strength, hot cracking susceptibility and hoop tensile properties. Typical non-dendritic equiaxed zone (EQZ) was observed along welds' fusion boundary. Hot cracks and fractures during the load were always located within the EQZ, however, this typical zone could be restrained by CW3, effectively. Furthermore, changing of the main intergranular precipitated phase within the EQZ from T phase by AA4047 to T2 phase by CW3 also resulted in developments on microscopic intergranular reinforcement and macroscopic hoop tensile properties. In addition, bridging caused by richer substructure dendrites within CW3 weld's columnar zone resulted in much lower hot cracking susceptibility of the whole weld than AA4047.

Effect of gas release in hot molding on flexural strength of composite friction brake

Science.gov (United States)

Rusdja, Andy Permana; Surojo, Eko; Muhayat, Nurul; Raharjo, Wijang Wisnu

2018-02-01

Composite friction brake is a vital part of braking system which serves to reduce the speed of vehicle. To fulfill the requirement of brake performance, composite friction brake must have friction and mechanical characteristic as required. The characteristics of composite friction brake are affected by brake material formulation and manufacturing parameter. In the beginning of hot molding, intermittent hot pressing was carried out to release the gases that consist of ammonia gas and water vapor. In composite friction brake, phenolic resin containing hexamethylenetetramine (HMTA) is often used as a binder. During hot molding, the reaction of phenolic resin and HMTA forms ammonia gas. Hot molding also generates water vapor because raw materials absorb moisture from environment when they are placed in storage. The gas release in hot molding is supposed affecting mechanical properties because it avoid entrapped gas in composite, so that this research investigated effect of gas release on flexural strength. Manufacturing of composite specimen was carried out as follow: mixing of raw materials, cold molding, and hot molding. In this research, duration of intermittent hot pressing and number of gas release were varied. The flexural strength of specimen was measured using three point bending test. The results showed that flexural strength specimens that were manufactured without gas release, using 4 times gas release with intermittent hot pressing for 5 and 10 seconds were not remarkably different. Conversely, hot molding using 4 times gas release with intermittent hot pressing for 15 seconds decreased flexural strength of composite. Hot molding using 2, 4, and 8 times gas release with intermittent hot pressing for 10 seconds also had no effect on increasing flexural strength. Increasing of flexural strength of composite was obtained only by using 6 times gas release with intermittent hot pressing for 10 seconds.

The influence of delta ferrite in the AISI 416 stainless steel hot workability

International Nuclear Information System (INIS)

Cardoso, P.H.S.; Kwietniewski, C.; Porto, J.P.; Reguly, A.; Strohaecker, T.R.

2003-01-01

Delta ferrite in martensitic stainless steels may have an adverse effect on the mechanical properties of these materials at high temperature. The occurrence of such phase is determined by the material chemical composition (mainly Cr and C), as-received microstructure condition and hot working temperature. The aim of this investigation is to assess the influence of delta ferrite on the hot workability of the martensitic AISI 416 stainless steel. Hence, different heats of this material (differing in chemical composition and as-received microstructure) were submitted to heating tests in order to observe the microstructural transformations that take place at high temperature and then examine the influence of these transformations on the mechanical behaviour. Phase characterisation and quantification were carried out using scanning electron microscopy/energy-dispersive X-ray microanalysis and image analysis. The heating tests were performed in the temperature range of 1100-1350 deg. C and hot workability in two heats with different delta ferrite content was assessed by hot torsion tests in the temperature range of 1000-1250 deg. C. The results have indicated that chemical composition and as-received microstructure strongly affect delta ferrite formation, which in turn deteriorates hot workability of the martensitic AISI 416 stainless steel

Microstructure, mechanical properties, and thermoelectric properties of hot-extruded p-type Te-doped Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} compounds

Energy Technology Data Exchange (ETDEWEB)

Park, K; Seo, J; Lee, C

1997-07-01

The p-type Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} compounds with Te dopant (4.0 and 6.0 wt%) and without dopant were fabricated by hot extrusion in the temperature range of 300 to 510 C under an extrusion ratio of 20:1. The undoped and Te doped compounds were highly dense and showed high crystalline quality. The grains contained many dislocations and were fine equiaxed ({approximately}1.0 {micro}m) owing to the dynamic recrystallization during the extrusion. The hot extrusion gave rise to the preferred orientation of grains. The bending strength and the figure of merit of the undoped and Te doped compounds were increased with increasing the extrusion temperature. The Te dopant significantly increased the figure of merit. The values of the figure of merit of the undoped and 4.0 wt% Te-doped compounds hot extruded at 440 C were 2.11 x 10{sup {minus}3}/K and 2.94 x 10{sup {minus}3}/K, respectively.

Effect of HIP temperatures on the microstructure and mechanical properties of carbide dispersed Ti-48Al-1Mn mechanically alloyed compacts

International Nuclear Information System (INIS)

Ameyama, Kei; Hashii, Mitsuya; Imai, Nobuyuki; Fujii, Toshinori; Sasaki, Nobuyuki.

1996-01-01

The effect of hot isostatic pressing (HIP) temperature on the microstructure and mechanical properties of Ti-48 mol%Al-1 mol%Mn compacts fabricated by mechanical alloying was investigated. N-heptane was used as a process control agent for the mechanical alloying. The compacts HIP treated at 1173, 1373 or 1573 K showed an ultra-fine equiaxed grain structure, i.e., a microduplex structure, consisting of TiAl (γ) and Ti 2 AlC phases, and their average grain sizes were 185 nm, 510 nm and 1.5 μm, respectively. The γ phase was considered to be formed by an α → γ massive transformation during heating. On the other hand, the compacts HIP treated at 1623 or 1673 K showed quite different microstructures from the above HIP compacts. The 1623 K-HIP compact was composed of equiaxed γ grains, whose size was approximately 11.5 μm, rectangular shaped Ti 2 AlC particles, and a small amount of the grain boundary nucleated α phase. Although the 1673 K-HIP compact showed a microstructure similar to the 1623 K-HIP compact, the γ grains were coarsened to be approximately 27.8 μm in diameter and the Ti 2 AlC particles were more elongated rectangles. Furthermore, the amount of the grain boundary nucleated α phase was increased and the lamella α phase nucleated at γ twin boundaries was observed in the 1673 K-HIP compact. Mechanical properties determined by compressive testing at various temperatures made clear that the compacts HIP treated at 1173, 1373 or 1573 K have good workability at elevated temperatures and those HIP treated at 1623 or 1673 K have good high temperature strength. These mechanical properties were influenced significantly by the microstructure, especially by the grain size and morphology of the Ti 2 AlC phase. (author)

Characterization of a hot-rolled Cu--Al--Ni--Ti shape memory alloy

International Nuclear Information System (INIS)

Segui, C.; Pons, J.; Cesari, E.

1999-01-01

The changes in the martensitic transformation of a Cu-Al-Ni-Ti alloy hot-rolled at different temperatures have been studied in detail, covering different aspects such as ageing in the parent phase at temperatures ranging between 250 and 350 o C, stabilisation of the martensite and betatization of the previously hot-rolled specimens. Besides the evolution of transformation temperatures upon different thermal treatments, special attention has been paid to the changes in mechanical properties of the alloy, such as elastic modulus and internal friction. These results are analysed in relation to the microstructural changes as observed by transmission electron microscopy. (orig.)

Reinforcing effect of graphene on the mechanical properties of Al2O3/TiC ceramics

Science.gov (United States)

Li, Zuo-li; Zhao, Jun; Sun, Jia-lin; Gong, Feng; Ni, Xiu-ying

2017-12-01

Multilayer graphene (MLG)-reinforced Al2O3/TiC ceramics were fabricated through hot pressing sintering, and the reinforcing effect of MLG on the microstructure and mechanical properties of the composites was investigated by experiment and simulation. The simulation of dynamic crack initiation and propagation was investigated based on the cohesive zone method. The results show that the composite added with 0.2wt% MLG has excellent flexural strength and high fracture toughness. The major reinforcing mechanisms are the synergistic effect by strong and weak bonding interfaces, MLG pull-out, and grain refinement resulting from the addition of MLG. In addition, the aggravating of crack deflection, branching, blunting, and bridging have indispensable contribution to the improvement of the as-designed materials.

Reinforcing effect of graphene on the mechanical properties of Al2O3/TiC ceramics

Institute of Scientific and Technical Information of China (English)

Zuo-li Li; Jun Zhao; Jia-lin Sun; Feng Gong; Xiu-ying Ni

2017-01-01

Multilayer graphene (MLG)-reinforced Al2O3/TiC ceramics were fabricated through hot pressing sintering, and the reinforcingef-fect of MLG on the microstructure and mechanical properties of the composites was investigated by experiment and simulation. The simula-tion of dynamic crack initiation and propagation was investigated based on the cohesive zone method. The results show that the composite added with 0.2wt% MLG has excellent flexural strength and high fracture toughness. The major reinforcing mechanisms are the synergistic effect by strong and weak bonding interfaces, MLG pull-out, and grain refinement resulting from the addition of MLG. In addition, the ag-gravating of crack deflection, branching, blunting, and bridging have indispensable contribution to the improvement of the as-designed mate-rials.

Mechanical properties of hot bituminous mixes manufactured with recycled aggregate of Silestone® waste

Directory of Open Access Journals (Sweden)

Rubio, M. C.

2011-03-01

Full Text Available This article presents the results of a research project which analyzes the viability of incorporating waste material from decorative quartz solid surfacing in the manufacture of hot bituminous mixes. For this purpose, various bituminous mixes were manufactured with waste aggregate in different percentage. A set of tests were carried out that permitted the characterization of the mechanical behavior of these mixes. The results of these tests were similar to the results obtained when conventional mixes made from virgin quarry aggregate were tested. The results for moisture sensitivity as well as for wheel track rutting on mixes showed the optimal performance of this waste material even under very demanding traffic conditions. Laboratory studies showed that the use of this waste material in the manufacture of bituminous mixes is technically viable and can provide high-quality recycled aggregates at a very low cost, which can be used in the pavement of road.

Este artículo muestra los resultados de un proyecto de investigación que tiene por objeto analizar la viabilidad de incorporación de residuos procedentes de piedra decorativa en la fabricación de mezclas bituminosas en caliente. Para ello se fabricaron mezclas con áridos reciclados de residuos procedentes de piedra decorativa en distintos porcentajes, realizando un conjunto de ensayos que posibilitaron caracterizar el comportamiento mecánico de dichas mezclas. Los resultados obtenidos fueron similares a los de las mezclas convencionales fabricadas con áridos vírgenes procedentes de cantera. Los valores de resistencia conservada ante la acción del agua y deformación en pista, pusieron de manifiesto la aptitud del residuo incluso ante las condiciones de tráfico más exigentes. Los trabajos realizados en el laboratorio indican que la utilización del residuo en la fabricación de mezclas bituminosas es técnicamente viable, pudiendo obtenerse áridos reciclados de gran calidad y

AECL hot-cell facilities and post-irradiation examination services

International Nuclear Information System (INIS)

Schankula, M.H.; Plaice, E.L.; Woodworth, L.G.

1998-04-01

This paper presents an overview of the post-irradiation examination (PIE) services available at AECL's hot-cell facilities (HCF). The HCFs are used primarily to provide PIE support for operating CANDU power reactors in Canada and abroad, and for the examination of experimental fuel bundles and core components irradiated in research reactors at the Chalk River Laboratories (CRL) and off-shore. A variety of examinations and analyses are performed ranging from non-destructive visual and dimensional inspections to detailed optical and scanning electron microscopic examinations. Several hot cells are dedicated to mechanical property testing of structural materials and to determine the fitness-for-service of reactor core components. Facility upgrades and the development of innovative examination techniques continue to improve AECL's PIE capabilities. (author)

AECL hot-cell facilities and post-irradiation examination services

International Nuclear Information System (INIS)

Schankula, M.H.; Plaice, E.L.; Woodworth, L.G.

1995-01-01

This paper presents an overview of the post-irradiation examination (PIE) services available at AECL's hot-cell facilities (HCF). The HCFs are used primarily to provide PIE support for operating CANDU power reactors in Canada and abroad, and for the examination of experimental fuel bundles and core components irradiated in research reactors at the Chalk River Laboratories (CRL) and off-shore. A variety of examinations and analysis are performed ranging from non-destructive visual and dimensional inspections to detailed optical and scanning electron microscopic examinations. Several hot cells are dedicated to mechanical property testing of structural materials and to determine the fitness-for-service of reactor core components. Facility upgrades and the development of innovative examination techniques continue to improve AECL's PIE capabilities. (author)

Production and mechanical properties of Ti-5Al-2.5Fe-xCu alloys for biomedical applications.

Science.gov (United States)

Yamanoglu, Ridvan; Efendi, Erdinc; Kolayli, Fetiye; Uzuner, Huseyin; Daoud, Ismail

2018-01-30

In this study, the mechanical, antibacterial properties and cell toxicity response of Ti-5Al2.5Fe alloy with different copper contents were investigated. The alloys were prepared by high-energy ball milling using elemental Ti, Al, Fe, and Cu powders and consolidated by a uniaxial vacuum hot press. Staphylococcus aureus strain ATCC 29213 and Escherichia coli strain ATCC 25922 were used to determine the antibacterial properties of the sintered alloys. The in vitro cytotoxicity of the samples was evaluated with HeLa (ATTC, CCL-2) cells using thiazolyl blue tetrazolium bromide. The mechanical behavior of the samples was determined as a function of hardness and bending tests and analyzed by scanning electron microscopy, energy dispersive x-ray spectroscopy, optical microscopy and x-ray diffraction (XRD). The results showed that the Cu content significantly improved the antibacterial properties. Cu addition prevented the formation of E. coli and S. aureus colonies on the surface of the samples. All samples exhibited very good cell biocompatibility. The alloys with different copper contents showed different mechanical properties, and the results were correlated by microstructural and XRD analyses in detail. Our results showed that Cu has a great effect on the Ti5Al2.5Fe alloy and the alloy is suitable for biomedical applications with enhanced antibacterial activity.

Investigation on the feasibility of coffee husk (endocarp) as efficient filler material for enhancing physical and mechanical properties of styrofoam based particleboard

Science.gov (United States)

Milawarni; Nurlaili; Ernayusnianti

2018-03-01

This research focuses on introducing a coffee husk as viable and efficient filler for enhancing physical and mechanical properties of Styrofoam based particleboard. Heat treatment method was adopted to produce the particleboard from the mixture of coffee husk (CH) with Styrofoam (PS). Styrofoam is material derived from polystyrene. The aim of this research is to get the appropriate weight composition between coffee husks with PS and to identify the physical and mechanical properties of the produced particleboard. The composition of coffee husk varies between 0-90%wt. The manufacture of particleboard i.e. coffee husk milled with size 20/10 mesh then soak with 10% NaOH for 2 hours, rinsed with clean water and dried and weight according to the composition. The mixture of CH and PS is inserted into mold and put into hot-press. The result shows from physical properties that density, water absorption and thick development test corresponding with SNI 03-2105-2006 standard, the mechanical properties shows MOR test meets the standard on the addition of CH 10-50%, while the MOE test has not meet the standard.

Hot Gas Halos in Galaxies

Science.gov (United States)

Mulchaey, John

Most galaxy formation models predict that massive low-redshift disk galaxies are embedded in extended hot halos of externally accreted gas. Such gas appears necessary to maintain ongoing star formation in isolated spirals like the Milky Way. To explain the large population of red galaxies in rich groups and clusters, most galaxy evolution models assume that these hot gas halos are stripped completely when a galaxy enters a denser environment. This simple model has been remarkably successful at reproducing many observed properties of galaxies. Although theoretical arguments suggest hot gas halos are an important component in galaxies, we know very little about this gas from an observational standpoint. In fact, previous observations have failed to detect soft X-ray emission from such halos in disk galaxies. Furthermore, the assumption that hot gas halos are stripped completely when a galaxy enters a group or cluster has not been verified. We propose to combine proprietary and archival XMM-Newton observations of galaxies in the field, groups and clusters to study how hot gas halos are impacted by environment. Our proposed program has three components: 1) The deepest search to date for a hot gas halo in a quiescent spiral galaxy. A detection will confirm a basic tenet of disk galaxy formation models, whereas a non-detection will seriously challenge these models and impose new constraints on the growth mode and feedback history of disk galaxies. 2) A detailed study of the hot gas halos properties of field early-type galaxies. As environmental processes such as stripping are not expected to be important in the field, a study of hot gas halos in this environment will allow us to better understand how feedback and other internal processes impact hot gas halos. 3) A study of hot gas halos in the outskirts of groups and clusters. By comparing observations with our suite of simulations we can begin to understand what role the stripping of hot gas halos plays in galaxy

Structure and Properties of Silica Glass Densified in Cold Compression and Hot Compression

Science.gov (United States)

Guerette, Michael; Ackerson, Michael R.; Thomas, Jay; Yuan, Fenglin; Bruce Watson, E.; Walker, David; Huang, Liping

2015-10-01

Silica glass has been shown in numerous studies to possess significant capacity for permanent densification under pressure at different temperatures to form high density amorphous (HDA) silica. However, it is unknown to what extent the processes leading to irreversible densification of silica glass in cold-compression at room temperature and in hot-compression (e.g., near glass transition temperature) are common in nature. In this work, a hot-compression technique was used to quench silica glass from high temperature (1100 °C) and high pressure (up to 8 GPa) conditions, which leads to density increase of ~25% and Young’s modulus increase of ~71% relative to that of pristine silica glass at ambient conditions. Our experiments and molecular dynamics (MD) simulations provide solid evidences that the intermediate-range order of the hot-compressed HDA silica is distinct from that of the counterpart cold-compressed at room temperature. This explains the much higher thermal and mechanical stability of the former than the latter upon heating and compression as revealed in our in-situ Brillouin light scattering (BLS) experiments. Our studies demonstrate the limitation of the resulting density as a structural indicator of polyamorphism, and point out the importance of temperature during compression in order to fundamentally understand HDA silica.

Investigations on the Manufacturing and Mechanical Properties of Spun Yarns Made from Staple CF for Thermoset Composites

Directory of Open Access Journals (Sweden)

Hasan Mir Mohammad Badrul

2017-12-01

Full Text Available This article reports the results of investigations carried out to produce yarns consisting of staple carbon fiber (CF obtained from process waste for the manufacturing of composites suitable especially for thermoset applications. For this purpose, a comparative analysis is done on processability between 100% staple CF and 60 weight% staple CF mixed with 40 weight% PVA fibers in carding, drawing and spinning process. The hybrid yarns are produced by varying twist level. The PVA fibers of the hybrid yarn are then dissolved using hot water treatment. The mechanical properties of yarns consisting of 100% staple CF and hybrid yarns consisting of staple CF and PVA before and after hot water treatment are investigated. Furthermore, test specimen is also prepared by impregnating 100% staple CF yarn and the hybrid yarns (after the dissolving of PVA with epoxy resin. The results of the tensile test of the yarns in consolidated state reveals that the hybrid yarn produced with 80 T/m after hot water treatment exhibits approximately 75% of the tensile strength of virgin filament tow, and it is expected that the hybrid yarns can be applied for the manufacturing of thermoset based composites for load bearing structures.

Chronic alcohol abuse in men alters bone mechanical properties by affecting both tissue mechanical properties and microarchitectural parameters.

Science.gov (United States)

Cruel, M; Granke, M; Bosser, C; Audran, M; Hoc, T

2017-06-01

Alcohol-induced secondary osteoporosis in men has been characterized by higher fracture prevalence and a modification of bone microarchitecture. Chronic alcohol consumption impairs bone cell activity and results in an increased fragility. A few studies highlighted effects of heavy alcohol consumption on some microarchitectural parameters of trabecular bone. But to date and to our knowledge, micro- and macro-mechanical properties of bone of alcoholic subjects have not been investigated. In the present study, mechanical properties and microarchitecture of trabecular bone samples from the iliac crest of alcoholic male patients (n=15) were analyzed and compared to a control group (n=8). Nanoindentation tests were performed to determine the tissue's micromechanical properties, micro-computed tomography was used to measure microarchitectural parameters, and numerical simulations provided the apparent mechanical properties of the samples. Compared to controls, bone tissue from alcoholic patients exhibited an increase of micromechanical properties at tissue scale, a significant decrease of apparent mechanical properties at sample scale, and significant changes in several microarchitectural parameters. In particular, a crucial role of structure model index (SMI) on mechanical properties was identified. 3D microarchitectural parameters are at least as important as bone volume fraction to predict bone fracture risk in the case of alcoholic patients. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Microstructure evolution of superalloy for large exhaust valve during hot forging

International Nuclear Information System (INIS)

Jeong, H.S.; Cho, J.R.; Park, H.C.

2004-01-01

The nickel-based alloy Nimonic 80A possesses strength, and corrosion, creep and oxidation resistance at high temperature. These products are used for aerospace, marine engineering and power generation, etc. The control of forging parameters such as strain, strain rate, temperature and holding time is important because the microstructure change in hot working affects the mechanical properties. It is necessary to understand the microstructure variation evolution. The microstructure change evolution occurs by recovery, recrystallization and grain growth phenomena. The dynamic recrystallization evolution has been studied in the temperature range 950-1250 deg. C and strain rate range 0.05-5s-1 using hot compression tests. The metadynamic recrystallization and grain growth evolution has been studied in the temperature range 950-1250 deg. C and strain rate range 0.05, 5s-1, holding time range 5, 10, 100, 600 sec using hot compression tests. Modeling equations are developed to represent the flow curve, recrystallized grain size, recrystallized fraction and grain growth phenomena by various tests. Parameters of modeling equation are expressed as a function of the Zener-Hollomon parameter. The modeling equation for grain growth is expressed as a function of initial grain size and holding time. The developed modeling equation was combined with thermo-viscoplastic finite element modeling to predict various microstructure change evolution during thermo mechanical processing. The predicted grain size in developed FE simulation results is compared with results obtained in various tests. In order to obtain a final microstructure and good mechanical properties in forging, the FEM would become a useful tool in the simulation of the microstructure development

Bibliography on Hot Isostatic Pressing (HIP) Technology

Science.gov (United States)

1992-11-01

Nimonic API, Rene’ 77 2. MA753, IN-853 7 3. C-103,WC-103 4. Alloy 454, PWA 1480 5. Mar- M250 , Maraging (250) 6. Rene 150, PA 101 (low C) 7. Inconel 718...Pressure Welding Parameters Bryant. W. A. Weld J 54 (12), 433-S-435-S, 1975 ( AD-DI02 316 Key Words: AISI 4340. MAR- M250 . AISI 1020, 9Ni-4Co steel. Inconel...creep rupture. hot corrosion, oxidation, grain size, thermomechanical treatment MAR- M250 1. Microstructures and Mechanical Properties of HIP

Preparation and Investigation of Mechanical Properties and Optical Clarity of Polyvinylbutyral Film

Directory of Open Access Journals (Sweden)

Morteza Hajian

2013-01-01

Full Text Available Polyvinyl butyral (PVB was synthesized by condensation reaction of polyvinyl alcohol (PVA with butanal in aqueous medium containing an effective emulsifier and an inorganic acid as catalyst. The product was characterized by, IR, TG and DTG techniques. Percentage of vinyl alcohol groups in the PVB was determined by a chemical method according to a standard method. Some clear and soft film samples containing the PVB and some high boiling point plasticizers were made by hot press. For this purpose plasticizers such as bis(2-ethylhexylphthalate (DOP and bis(2-ethylhexyl terephthalate (DOTP were purchased and the triethylene glycol bis(2-ethylhexanoate (TEGB was synthesized. The film samples containing 30 percent mixture of triethylene glycol bis(2-ethylhexanoate and bis (2-ethylhexylphthalate with ratio 65/35 showed some improved mechanical and optical properties.

Real-time observations of mechanical stimulus-induced enhancements of mechanical properties in osteoblast cells

International Nuclear Information System (INIS)

Zhang Xu; Liu Xiaoli; Sun Jialun; He Shuojie; Lee, Imshik; Pak, Hyuk Kyu

2008-01-01

Osteoblast, playing a key role in the pathophysiology of osteoporosis, is one of the mechanical stress sensitive cells. The effects of mechanical load-induced changes of mechanical properties in osteoblast cells were studied at real-time. Osteoblasts obtained from young Wister rats were exposed to mechanical loads in different frequencies and resting intervals generated by atomic force microscopy (AFM) probe tip and simultaneously measured the changes of the mechanical properties by AFM. The enhancement of the mechanical properties was observed and quantified by the increment of the apparent Young's modulus, E * . The observed mechanical property depended on the frequency of applied tapping loads. For the resting interval is 50 s, the mechanical load-induced enhancement of E * -values disappears. It seems that the enhanced mechanical property was recover able under no additional mechanical stimulus

Effect of moisture and freeze-thaw on mechanical properties of CRM asphalt mixture

Energy Technology Data Exchange (ETDEWEB)

Kim, Nak-Seok; Cho, Kee-Ju [Kyonggi University, Suwon(Korea)

2000-06-30

This paper presents the experimental test results on moisture and freeze-thaw resistance of hot mix crumb rubber modified (CRM) asphalt concrete mixture. To compare the differences in mechanical properties of conventional and CRM asphalt concretes, various tests were conducted under different moisture conditions and freeze-thaw cycles. Marshall mix design was also performed to determine the optimum asphalt contents for the both asphalt concrete mixtures. Test results revealed that the moisture and freeze-thaw resistance of CRM asphalt mixture was superior to the conventional asphalt concrete. As a result, it is considered that the utilization of waste tires in asphalt pavements has the potential of minimizing the damage due to the moisture and freeze-thaw. (author). 9 refs., 4 tabs., 8 figs.

Modelling and simulations in hot deformation of steels

International Nuclear Information System (INIS)

Cabrera, J.M.

2002-01-01

Traditionally, hot forming has been employed to provide shape to metals. Nowadays, however, hot working not only produces the desired geometry, but also the mechanical characteristics required. An understanding of the thermomechanical behaviour of metals, and particularly steels, is essential in the simulation and control of the hot forming operations. Moreover, a right prediction of the final properties needs from accurate descriptions of the microstructural features occurring during the shaping step. For this purpose, the determination of constitutive equations describing the stress σ - strain ε relationships at a given strain rate ε, temperature T and initial microstructure, is a useful task. In this sense, computer simulations of hot working processes proportionate a benchmark to engineers and researchers and allow decreasing the cost of developing products and processes. With regard to the prediction of the final microstructure, the simulation of the hot plastic deformation usually gives unsatisfactory results. This is due to the inadequate constitutive equations employed by the conventional and commercial software available to describe the hot flow behaviour. There are scarce models which couple the typical hot working variables (temperature, strain and strain rate) with microstructural characteristics such as grain size. In this review work is presented how the latter limitation can be overcome by using physical-based constitutive equations, some of which have been partially developed by the present authors, where account of the interaction between microstructure and processing variables is taken. Moreover, a practical derivation of the latter expressions on an AISI-304 steel is presented. To conclude, some examples of industrial applications of the latter approach are also presented. Copyright (2002) AD-TECH - International Foundation for the Advancement of Technology Ltd

Effect of yttrium addition on the microstructure and mechanical properties of ODS RAF steels

International Nuclear Information System (INIS)

Auger, M.A.; Castro, V. de; Leguey, T.; Tarcísio-Costa, J.; Monge, M.A.; Muñoz, A.; Pareja, R.

2014-01-01

An oxide dispersion strengthened (ODS) alloy with nominal composition Fe–14Cr–2W–0.3Ti–0.24Y (wt.%) was produced by mechanical alloying using elemental powders, and subsequent hot isostatic pressing. The microstructure of the material and characteristics of the oxide particle dispersion were investigated by electron microscopy. The effect of heat treatments on the microhardness and tensile properties at room temperature was also studied. The results show that a fine dispersion of Y–O-rich nanoparticles is achieved, together with larger (Cr, Ti)-rich precipitates. The absence of Ti is apparent in the majority of these nanoparticles, in contrast with reported results for ODS Ti-modified steels processed with Y 2 O 3 addition

Transport properties of hot gluonic matter

CERN Document Server

Bluhm, Marcus

2012-01-01

We discuss the temperature dependence of the scaled jet quenching parameter of hot gluonic matter within a quasiparticle approach. A pronounced maximum in the vicinity of the transition temperature is observed, where the ratio of the scaled jet quenching parameter and the inverse specific shear viscosity increases above typical values for weakly coupled systems.

Hot carrier dynamics in plasmonic transition metal nitrides

Science.gov (United States)

Habib, Adela; Florio, Fred; Sundararaman, Ravishankar

2018-06-01

Extraction of non-equilibrium hot carriers generated by plasmon decay in metallic nano-structures is an increasingly exciting prospect for utilizing plasmonic losses, but the search for optimum plasmonic materials with long-lived carriers is ongoing. Transition metal nitrides are an exciting class of new plasmonic materials with superior thermal and mechanical properties compared to conventional noble metals, but their suitability for plasmonic hot carrier applications remains unknown. Here, we present fully first principles calculations of the plasmonic response, hot carrier generation and subsequent thermalization of all group IV, V and VI transition metal nitrides, fully accounting for direct and phonon-assisted transitions as well as electron–electron and electron–phonon scattering. We find the largest frequency ranges for plasmonic response in ZrN, HfN and WN, between those of gold and silver, while we predict strongest absorption in the visible spectrum for the VN, NbN and TaN. Hot carrier generation is dominated by direct transitions for most of the relevant energy range in all these nitrides, while phonon-assisted processes dominate only below 1 eV plasmon energies primarily for the group IV nitrides. Finally, we predict the maximum hot carrier lifetimes to be around 10 fs for group IV and VI nitrides, a factor of 3–4 smaller than noble metals, due to strong electron–phonon scattering. However, we find longer carrier lifetimes for group V nitrides, comparable to silver for NbN and TaN, while exceeding 100 fs (twice that of silver) for VN, making them promising candidates for efficient hot carrier extraction.

Mechanical and tribological properties of ceramic-matrix friction materials with steel fiber and mullite fiber

International Nuclear Information System (INIS)

Wang, Fahui; Liu, Ying

2014-01-01

Highlights: • Interaction of mixing the steel and mullite fibers can improve the mechanical properties. • Mixing the steel and mullite fibers can also improve friction stability. • Friction coefficient increases with increasing additional mullite fiber content. • Ceramic-matrix friction material shows sever fade due to mullite fibers agglomerated. - Abstract: The purpose of the present work was to investigate and compare the mechanical and tribological behaviors of ceramic-matrix friction material (CMFM) with steel fiber (SF), mullite fiber (MF), and mixing SF and MF. The CMFM was prepared by hot-pressing sintering, and the tribological behaviors were determined using a constant speed friction tester. The worn surfaces and wear debris were observed by a scanning electron microscopy (SEM). Experiment results show that the combination of SF and MF can improve the mechanical properties that each single fiber does not have. The sever fade for the specimen reinforced by single MF during the whole friction testing can be attributed to the poor interface cohesive strength between MF and matrix. Mixing the SF and MF can improve the friction stability, and the friction coefficients for friction material with a mixture of the SF and MF increases with increasing MF content. For all specimens, increasing in the friction temperatures result in the increase of wear rates

Material development for grade X80 heavy-wall hot induction bends

International Nuclear Information System (INIS)

Wang Xu; Xiao Furen; Fu Yanhong; Chen Xiaowei; Liao Bo

2011-01-01

Highlights: ► The new material for X80 heavy wall thickness hot induction bend was designed. ► The continuous cooling transformation (CCT) diagrams were determined. ► The steel adapts to manufacture of X80 heavy-wall thickness hot induction bend. ► The optimum manufactural processes were obtained. ► The bending temperature is about 990 °C, and tempering is about 600 °C. - Abstract: A new steel for grade X80 heavy wall thickness hot induction bends was designed based on the chemical compositions of commercial X80 steels in this work. Then, its continuous cooling transformation (CCT) diagram was determined with Gleeble-3500 thermo-mechanical simulator. Furthermore, the effects of heat treatment technology on its microstructure and mechanical property were investigated, and the technology parameters of the heat treatment were optimized. The results show that the acicular ferrite and/or bainite transformations are promoted, the polygonal ferrite and pearlite transformation are restrained, because proper amount of alloying elements were added into the new steel. Therefore, the strength of this new steel is improved markedly, even if the cooling rate is lower, which ensure the higher strength distribution along cross section of the heavy wall thickness. It is significant for the manufacture of grade X80 heavy wall thickness hot induction bends in the second West-to-East gas transportation pipeline project of China.

Spray forming and mechanical properties of a new type powder metallurgy superalloy

International Nuclear Information System (INIS)

Jia Chong-Lin; Ge Chang-Chun; Xia Min; Gu Tian-Fu

2015-01-01

The deposited billet of a new type powder metallurgy (PM) superalloy FGH4095M for use in turbine disk manufacturing has been fabricated using spray forming technology. The metallurgical quality of the deposited billet was analyzed in terms of density, texture, and grain size. Comparative research was done on the microstructure and mechanical properties between the flat disk preform prepared with hot isostatic pressing (HIP) and the same alloy forgings prepared with HIP followed by isothermal forging (IF). The results show that the density of the spray-formed and nitrogen-atomized deposit billet is above 99% of the theoretical density, indicating a compact structure. The grains are uniform and fine. The billet has weak texture with a random distribution in the spray deposition direction and perpendicular to the direction of deposition. A part of atomizing nitrogen exists in the preform in the form of carbonitride. Nitrogen-induced microporosity causes the density reduction of the preform. Compared with the process of HIP+IF, the superalloy FGH4095M after HIP has better mechanical properties at both room temperature and high temperature. The sizes of the γ′ phase are finer in microstructure of the preform after HIP in comparison with the forgings after HIP+IF. This work shows that SF+HIP is a viable processing route for FGH4095M as a turbine-disk material. (paper)

Densification and Mechanical Properties of ZrN-Nb Composites

Directory of Open Access Journals (Sweden)

ZHANG Yan

2018-02-01

Full Text Available Densification of zirconium nitride (ZrN ceramics was investigated by vacuum hot pressing at temperatures range from 1500℃to 2000℃with Nb as sintering additive. Densification was enhanced with Nb addition. ZrN with 5mol% Nb addition achieved a relative density of 98.5% at 1600℃.XRD and lattice parameter measurements indicated that there were structural differences between samples sintered in different temperatures. It was likely that due to the presence of point defects by changes in stoichiometry, the kinetics of mass transport enhanced. As a result, the relative density of the zirconium nitride (ZrN ceramics have been improved, thus the fully densed ZrN ceramics can be prepared in a relative low temperature. The density, the room-temperature mechanical properties of ZrN ceramics are increased after the addition of Nb. Zirconium nitride (ZrNdoped with Nb sintered at 1600℃ are measured and obtained elasticity modulus of 238 GPa, flexural strength of 463.3 MPa, fracture toughness of 7.0 MPa·m1/2 and hardness of 10.7 GPa.

X-ray and SZ constraints on the properties of hot CGM

Science.gov (United States)

Singh, Priyanka; Majumdar, Subhabrata; Nath, Biman B.; Silk, Joseph

2018-05-01

We use observations of stacked X-ray luminosity and Sunyaev-Zel'dovich (SZ) signal from a cosmological sample of ˜80, 000 and 104,000 massive galaxies, respectively, with 1012.6 ≲ M500 ≲ 1013M⊙ and mean redshift, z¯ ˜ 0.1 - 0.14 to constrain the hot Circumgalactic Medium (CGM) density and temperature. The X-ray luminosities constrain the density and hot CGM mass, while the SZ signal helps in breaking the density-temperature degeneracy. We consider a simple power-law density distribution (ne∝r-3β) as well as a hydrostatic hot halo model, with the gas assumed to be isothermal in both cases. The datasets are best described by the mean hot CGM profile ∝r-1.2, which is shallower than an NFW profile. For halo virial mass ˜1012 - 1013M⊙, the hot CGM contains ˜ 20 - 30% of galactic baryonic mass for the power-law model and 4 - 11% for the hydrostatic halo model, within the virial radii. For the power-law model, the hot CGM profile broadly agrees with observations of the Milky Way. The mean hot CGM mass is comparable to or larger than the mass contained in other phases of the CGM for L* galaxies.

Microstructural and mechanical properties analysis of extruded Sn–0.7Cu solder alloy

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Abdoul-Aziz Bogno

2015-01-01

Full Text Available The properties and performance of lead-free solder alloys such as fluidity and wettability are defined by the alloy composition and solidification microstructure. Rapid solidification of metallic alloys is known to result in refined microstructures with reduced microsegregation and improved mechanical properties of the final products as compared to normal castings. The rapidly solidified Sn-based solders by melt spinning were shown to be suitable for soldering with low temperature and short soldering duration. In the present study, rapidly solidified Sn–0.7 wt.%Cu droplets generated by impulse atomization (IA were achieved as well as directional solidification under transient conditions at lower cooling rate. This paper reports on a comparative study of the rapidly solidified and the directionally solidified samples. Different but complementary characterization techniques were used to fully analyze the solidification microstructures of the samples obtained under the two cooling regimes. These include X-ray diffractometry (XRD and scanning electron microscopy (SEM. In order to compare the tensile strength and elongation to fracture of the directionally solidified ingot and strip castings with the atomized droplet, compaction and extrusion of the latter were carried out. It was shown that more balanced and superior tensile mechanical properties are available for the hot extruded samples from compacted as-atomized Sn–0.7 wt.%Cu droplets. Further, elongation-to-fracture was 2–3× higher than that obtained for the directionally solidified samples.

Structure and properties of highly oriented polyoxymethylene produced by hot stretching

International Nuclear Information System (INIS)

Zhao Xiaowen; Ye Lin

2011-01-01

Research highlights: → Highly oriented POM was fabricated through solid hot stretching technology → Tensile strength and modulus of POM increased remarkably with draw ratio. → The crystal structure of POM changed from spherulite to mat texture by drawing. → Crystallinity and orientation factor of POM increased remarkably by drawing. → The mechanical structure model of microfibril of POM was established. - Abstract: Highly oriented self-reinforced polyoxymethylene (POM) was successfully fabricated through solid phase hot stretching technology. The tensile strength and modulus increased with draw ratio, which reached 900 MPa and 12 GPa, respectively at a high draw ratio of 900% without remarkable drop of the elongation at break. The structure and morphology of the drawn products were studied and the mechanical structure model of microfibril of POM was established. Raman spectral exhibited a low-frequency shift, which indicated two types of molecular chains with different response to the stress. During drawing, the spherulitic structure of POM was broken up and the mat texture crystals were formed. With the increase of draw ratio, the melting peak moved to high temperature and an additional shoulder peak ascribed to melting of highly chain-extended and oriented crystalline blocks was observed. X-ray diffraction showed that the crystallinity and orientation factor increased, while the grain size perpendicular to (1 0 0) crystal plane of POM decreased by drawing. The α relaxation peak corresponding to the glass transition temperature of POM (T g ) moved to high temperature with draw ratio. The section morphology of drawn POM exhibited a fibrillar structure which contributed to the significantly high tensile strength and modulus of the product.

Enhanced performance of nano-sized SiC reinforced Al metal matrix nanocomposites synthesized through microwave sintering and hot extrusion techniques

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M. Penchal Reddy

2017-10-01

Full Text Available In the present study, nano-sized SiC (0, 0.3, 0.5, 1.0 and 1.5 vol% reinforced aluminum (Al metal matrix composites were fabricated by microwave sintering and hot extrusion techniques. The structural (XRD, SEM, mechanical (nanoindentation, compression, tensile and thermal properties (co-efficient of thermal expansion-CTE of the developed Al-SiC nanocomposites were studied. The SEM/EDS mapping images show a homogeneous distribution of SiC nanoparticles into the Al matrix. A significant increase in the strength (compressive and tensile of the Al-SiC nanocomposites with the addition of SiC content is observed. However, it is noticed that the ductility of Al-SiC nanocomposites decreases with increasing volume fraction of SiC. The thermal analysis indicates that CTE of Al-SiC nanocomposites decreases with the progressive addition of hard SiC nanoparticles. Overall, hot extruded Al 1.5 vol% SiC nanocomposites exhibited the best mechanical and thermal performance as compared to the other developed Al-SiC nanocomposites. Keywords: Al-SiC nanocomposites, Microwave sintering, Hot extrusion, Mechanical properties, Thermal expansion

Fabrication and properties of graphene reinforced silicon nitride composite materials

International Nuclear Information System (INIS)

Yang, Yaping; Li, Bin; Zhang, Changrui; Wang, Siqing; Liu, Kun; Yang, Bei

2015-01-01

Silicon nitride (Si 3 N 4 ) ceramic composites reinforced with graphene platelets (GPLs) were prepared by hot pressed sintering and pressureless sintering respectively. Adequate intermixing of the GPLs and the ceramic powders was achieved in nmethyl-pyrrolidone (NMP) under ultrasonic vibration followed by ball-milling. The microstructure and phases of the Si 3 N 4 ceramic composites were investigated by Field Emission Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The effects of GPLs on the composites' mechanical properties were analyzed. The results showed that GPLs were well dispersed in the Si 3 N 4 ceramic matrix. β-Si 3 N 4, O′-sialon and GPLs were present in the hot-pressed composites while pressureless sintered composites contain β-Si 3 N 4 , Si, SiC and GPLs. Graphene has the potential to improve the mechanical properties of both the hot pressed and pressureless sintered composites. Toughening effect of GPLs on the pressureless sintered composites appeared more effective than that on the hot pressed composites. Toughening mechanisms, such as pull-out, crack bridging and crack deflection induced by GPLs were observed in the composites prepared by the two methods

Statistical properties of laser hot spots produced by a random phase plate

International Nuclear Information System (INIS)

Rose, H.A.; DuBois, D.F.

1993-01-01

A quantitative theory of laser hot spots, which control plasma instabilities in real laser--plasma interactions, is presented in the case of random phase plate (RPP) optics. It is shown that the probability density of intense hot spots with intensity I, P hot (I), is given by P hot (I)∼(I/I 0 2 )exp(-I/I 0 ) where I 0 is the average intensity, and that the detailed amplitude and phase variation of the laser field in the vicinity of an intense hot spot is uniquely specified by the optics and is deterministic. These hot spots may be the source of below threshold stimulated Raman scattering (SRS) and its variation with I 0 is shown to be super exponential. A brief preview of a quantitative nonlinear theory of hot-spot-induced laser filamentation is presented

Mechanical Properties of Advanced Gas-Cooled Reactor Stainless Steel Cladding After Irradiation

Science.gov (United States)

Degueldre, Claude; Fahy, James; Kolosov, Oleg; Wilbraham, Richard J.; Döbeli, Max; Renevier, Nathalie; Ball, Jonathan; Ritter, Stefan

2018-05-01

The production of helium bubbles in advanced gas-cooled reactor (AGR) cladding could represent a significant hazard for both the mechanical stability and long-term storage of such materials. However, the high radioactivity of AGR cladding after operation presents a significant barrier to the scientific study of the mechanical properties of helium incorporation, said cladding typically being analyzed in industrial hot cells. An alternative non-active approach is to implant He2+ into unused AGR cladding material via an accelerator. Here, a feasibility study of such a process, using sequential implantations of helium in AGR cladding steel with decreasing energy is carried out to mimic the buildup of He (e.g., 50 appm) that would occur for in-reactor AGR clad in layers of the order of 10 µm in depth, is described. The implanted sample is subsequently analyzed by scanning electron microscopy, nanoindentation, atomic force and ultrasonic force microscopies. As expected, the irradiated zones were affected by implantation damage (steel cladding is retained despite He2+ implantation.

Physical and Mechanical Properties of Jute Mat Reinforced Epoxy Composites

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S.M Sadaf

2011-11-01

Full Text Available Cellulose jute fibre offers a number of benefits as reinforcement for synthetic polymers since it has a high specific strength and stiffness, low hardness, relatively low density and biodegradability. To reduce moisture uptake and hence to improve the mechanical properties of the composites, bleached jute mats were incorporated as reinforcing elements in the epoxy matrix. Composites at varying volume fractions and different orientations of jute mat were fabricated by hot compression machine under specific pressures and temperatures. Tensile, flexure, impact and water absorption tests of composites were conducted. Jute mat oriented at (0 ± 45–90° composites showed reduced strength compared to (0–90° fibre mat composites. Impact strength and water uptake of high volume fraction jute mat reinforced composites was higher compared to that of lower volume fraction composites. Fracture surfaces of jute mat composites were analyzed under SEM. Fracture surface of (0–90° jute mat oriented composites showed twisted fibres, while (0 ± 45–90° jute mat oriented composites had fibre pull-out without any twisting. Overall, composites containing 52% jute mat at orientations of (0–90° showed better properties compared to other fabricated composites.

Effect of seaweed on mechanical, thermal, and biodegradation properties of thermoplastic sugar palm starch/agar composites.

Science.gov (United States)

Jumaidin, Ridhwan; Sapuan, Salit M; Jawaid, Mohammad; Ishak, Mohamad R; Sahari, Japar

2017-06-01

The aim of this paper is to investigate the characteristics of thermoplastic sugar palm starch/agar (TPSA) blend containing Eucheuma cottonii seaweed waste as biofiller. The composites were prepared by melt-mixing and hot pressing at 140°C for 10min. The TPSA/seaweed composites were characterized for their mechanical, thermal and biodegradation properties. Incorporation of seaweed from 0 to 40wt.% has significantly improved the tensile, flexural, and impact properties of the TPSA/seaweed composites. Scanning electron micrograph of the tensile fracture showed homogeneous surface with formation of cleavage plane. It is also evident from TGA results that thermal stability of the composites were enhanced with addition of seaweed. After soil burial for 2 and 4 weeks, the biodegradation of the composites was enhanced with addition of seaweed. Overall, the incorporation of seaweed into TPSA enhances the properties of TPSA for short-life product application such as tray, plate, etc. Copyright © 2017 Elsevier B.V. All rights reserved.

Mechanical properties of modified low cobalt powder metallurgy Udimet 700 type alloys

Science.gov (United States)

Harf, Fredric H.

1989-01-01

Eight superalloys derived from Udimet 700 were prepared by powder metallurgy, hot isostatically pressed, heat treated and their tensile and creep rupture properties determined. Several of these alloys displayed properties superior to those of Udimet 700 similarly prepared, in one case exceeding the creep rupture life tenfold. Filter clogging by extracted gamma prime, its measurement and significance are discussed in an appendix.

Some mechanical properties of borided AISI H13 and 304 steels

International Nuclear Information System (INIS)

Taktak, Sukru

2007-01-01

In the present study, mechanical properties of borides formed on AISI H13 hot work tool and AISI 304 stainless steels have been investigated. Both steels have high chromium content and have a widespread use in the engineering application. Boriding treatment was carried out in slurry salt bath consisting of borax, boric acid, and ferrosilicon at temperature range of 800-950 deg. C for 3, 5, and 7 h. X-ray diffraction analysis of boride layers on the surface of steels revealed various peaks of FeB, Fe 2 B, CrB, and Ni 3 B. Metallographic studies showed that the boride layer has a flat and smooth morphology in the 304 steel while H13 steel was a ragged morphology. The characterization of the boride layer is also carried out by means of the micro-hardness, surface roughness, adhesion, and fracture toughness studies

Selected mechanical properties of modified beech wood

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Jiří Holan

2008-01-01

Full Text Available This thesis deals with an examination of mechanical properties of ammonia treated beach wood with a trademark Lignamon. For determination mechanical properties were used procedures especially based on ČSN. From the results is noticeable increased density of wood by 22% in comparison with untreated beach wood, which makes considerable increase of the most mechanical wood properties. Considering failure strength was raised by 32% and modulus of elasticity was raised at average about 46%.

The comparison of two continuum damage mechanics-based material models for formability prediction of AA6082 under hot stamping conditions

Science.gov (United States)

Shao, Z.; Li, N.; Lin, J.

2017-09-01

The hot stamping and cold die quenching process has experienced tremendous development in order to obtain shapes of structural components with great complexity in automotive applications. Prediction of the formability of a metal sheet is significant for practical applications of forming components in the automotive industry. Since microstructural evolution in an alloy at elevated temperature has a large effect on formability, continuum damage mechanics (CDM)-based material models can be used to characterise the behaviour of metals when a forming process is conducted at elevated temperatures. In this paper, two sets of unified multi-axial constitutive equations based on material’s stress states and strain states, respectively, were calibrated and used to effectively predict the thermo-mechanical response and forming limits of alloys under complex hot stamping conditions. In order to determine and calibrate the two material models, formability tests of AA6082 using a developed novel biaxial testing system were conducted at various temperatures and strain rates under hot stamping conditions. The determined unified constitutive equations from experimental data are presented in this paper. It is found that both of the stress-state based and strain-state based material models can predict the formability of AA6082 under hot stamping conditions.

Fabrication of Al-based composites reinforced with in situ devitrified Al{sub 84}Ni{sub 8.4}Y{sub 4.8}La{sub 1.8}Co{sub 1} particles by hot pressing consolidation

Energy Technology Data Exchange (ETDEWEB)

Yang, Qing, E-mail: buaayq00@gmail.com; Zhang, Yitan; Zhang, Haiping; Zheng, Ruixiao; Xiao, Wenlong; Ma, Chaoli, E-mail: machaoli@buaa.edu.cn

2015-11-05

In this study, Al{sub 84}Ni{sub 8.4}Y{sub 4.8}La{sub 1.8}Co{sub 1} particles reinforced Al-based composites were prepared by hot pressing sintering and subsequent hot extrusion. The glassy powders were produced by gas atomization and then employed to mechanical milling. After hot pressing sintering, the nano-scale intermetallic compounds precipitated from metallic glass matrix due to higher temperature than super-cooled liquid region. The mechanical properties of 2024 alloy were improved by addition of glassy particles. The ultimate compressive stress increased from 482 MPa for 2024 alloy to 545 MPa, 627 MPa and 735 MPa for composites with 20 w.t.% 40 w.t.% and 60 w.t.% glassy powders addition, respectively, together with considerable fracture strain ranging between 2.9% and 13.6%. And the mechanical properties could be predicted by using the Rule of Mixture, which predicts the mechanical properties of the bulks from the volume weighed average of the constituent properties. - Highlights: • The composites are fabricate by hot pressing and extrusion. • The single phase of amorphous alloy is obtained by sieving. • The nano-scale compounds precipitates from glassy matrix. • The compressive strength reaches to the value of 735 MPa. • The strength can fit well with rule of mixture.

Microstructures and mechanical properties of aging materials

International Nuclear Information System (INIS)

Liaw, P.K.; Viswanathan, R.; Murty, K.L.; Simonen, E.P.; Frear, D.

1993-01-01

This book contains a collection of papers presented at the symposium on ''Microstructures and Mechanical Properties of Aging Materials,'' that was held in Chicago, IL. November 2-5, 1992 in conjunction with the Fall Meeting of The Minerals, Metals and Materials Society (TMS). The subjects of interest in the symposium included: (1) mechanisms of microstructural degradation, (2) effects of microstructural degradation on mechanical behavior, (3) development of life prediction methodology for in-service structural and electronic components, (4) experimental techniques to monitor degradation of microstructures and mechanical properties, and (5) effects of environment on microstructural degradation and mechanical properties. Individual papers have been processed separately for inclusion in the appropriate data bases

Effects of Fiber Content on Mechanical Properties of CVD SiC Fiber-Reinforced Strontium Aluminosilicate Glass-Ceramic Composites

Science.gov (United States)

Bansal, Narottam P.

1996-01-01

Unidirectional CVD SiC(f)(SCS-6) fiber-reinforced strontium aluminosilicate (SAS) glass-ceramic matrix composites containing various volume fractions, approximately 16 to 40 volume %, of fibers were fabricated by hot pressing at 1400 C for 2 h under 27.6 MPa. Monoclinic celsian, SrAl2Si2O8, was the only crystalline phase formed, with complete absence of the undesired hexacelsian phase, in the matrix. Room temperature mechanical properties were measured in 3-point flexure. The matrix microcracking stress and the ultimate strength increased with increase in fiber volume fraction, reached maximum values for V(sub f) approximately equal to 0.35, and degraded at higher fiber loadings. This degradation in mechanical properties is related to the change in failure mode, from tensile at lower V(sub f) to interlaminar shear at higher fiber contents. The extent of fiber loading did not have noticeable effect on either fiber-matrix debonding stress, or frictional sliding stress at the interface. The applicability of micromechanical models in predicting the mechanical properties of the composites was also examined. The currently available theoretical models do not appear to be useful in predicting the values of the first matrix cracking stress, and the ultimate strength of the SCS-6/SAS composites.

Mechanical properties and microstructure of copper alloys and copper alloy-stainless steel laminates for fusion reactor high heat flux applications

Science.gov (United States)

Leedy, Kevin Daniel

A select group of copper alloys and bonded copper alloy-stainless steel panels are under consideration for heat sink applications in first wall and divertor structures of a planned thermonuclear fusion reactor. Because these materials must retain high strengths and withstand high heat fluxes, their material properties and microstructures must be well understood. Candidate copper alloys include precipitate strengthened CuNiBe and CuCrZr and dispersion strengthened Cu-Alsb2Osb3 (CuAl25). In this study, uniaxial mechanical fatigue tests were conducted on bulk copper alloy materials at temperatures up to 500sp°C in air and vacuum environments. Based on standardized mechanical properties measurement techniques, a series of tests were also implemented to characterize copper alloy-316L stainless steel joints produced by hot isostatic pressing or by explosive bonding. The correlation between mechanical properties and the microstructure of fatigued copper alloys and the interface of copper alloy-stainless steel laminates was examined. Commercial grades of these alloys were used to maintain a degree of standardization in the materials testing. The commercial alloys used were OMG Americas Glidcop CuAl25 and CuAl15; Brush Wellman Hycon 3HP and Trefimetaux CuNiBe; and Kabelmetal Elbrodur and Trefimetaux CuCrZr. CuAl25 and CuNiBe alloys possessed the best combination of fatigue resistance and microstructural stability. The CuAl25 alloy showed only minimal microstructural changes following fatigue while the CuNiBe alloy consistently exhibited the highest fatigue strength. Transmission electron microscopy observations revealed that small matrix grain sizes and high densities of submicron strengthening phases promoted homogeneous slip deformation in the copper alloys. Thus, highly organized fatigue dislocation structure formation, as commonly found in oxygen-free high conductivity Cu, was inhibited. A solid plate of CuAl25 alloy hot isostatically pressed to a 316L stainless steel

Birth, life and death of hot nuclei

International Nuclear Information System (INIS)

Suraud, E.; Tamain, B.; Gregoire, C.

1989-01-01

Intermediate energy heavy-ions (10-100 MeV/u) are the most powerful tool to study hot nuclear matter properties. In this paper we give a review of experimental and theoretical works which support this statement. The first challenge is to achieve hot nuclei formation. The second one is to study their properties. The formation step is governed by the relative influence of nucleon-nucleon collisions and mean field effects. Fundamental quantities such as excited matter decay time, thermalization time, relaxation time for collective modes are of major importance and are compared with typical collision times. It appears that semi-classical theories are able to give a reasonable description of the collision and that they are a good guide for defining further experiments. We show how it has been possible to experimentally establish that very hot equilibrated nuclei are really formed. Their decay properties are not basically different from decay properties at lower bombarding energy. However specific channels are open: in that sense, we take stock of the multifragmentation process. Moreover, compression effects may be an important feature of this energy range. Future studies will involve heavier projectiles around 30-50 MeV/u. They will be the best probe for hot and compressed nuclear matter studies

Upgrades of Hanford Engineering Development Laboratory hot cell facilities

International Nuclear Information System (INIS)

Daubert, R.L.; DesChane, D.J.

1987-01-01

The Hanford Engineering Development Laboratory operates the 327 Postirradiation Testing Laboratory (PITL) and the 324 Shielded Materials Facility (SMF). These hot cell facilities provide diverse capabilities for the postirradiation examination and testing of irradiated reactor fuels and materials. The primary function of these facilities is to determine failure mechanisms and effects of irradiation on physical and mechanical properties of reactor components. The purpose of this paper is to review major equipment and facility upgrades that enhance customer satisfaction and broaden the engineering capabilities for more diversified programs. These facility and system upgrades are providing higher quality remote nondestructive and destructive examination services with increased productivity, operator comfort, and customer satisfaction

Chemical composition and oxidative stability of jussara (Euterpe edulis M.) oil extracted by cold and hot mechanical pressing

International Nuclear Information System (INIS)

Da Cunha, A.L.A.; Freitas, S.P.; Godoy, R.L.O.; Cabral, L.M.C.; Tonon, R.V.

2017-01-01

The aim of this work was to evaluate the effect of mechanical pressing on jussara oil yield, oxidative stability and carotenoid profile with or without heat application. Firstly, jussara pulp was centrifuged for juice extraction, and the resulting cake was dried until reaching 10% moisture content. Then, oil extraction was performed in an expeller press at 25 ºC (cold pressing) and at 50 ºC (hot pressing). The process performance was evaluated by the oil yield, and the crude jussara oil was characterized for fatty acid composition, acid value, carotenoid profile and oxidative stability. Jussara oil contained 74% unsaturated fatty acids, mainly oleic and linoleic acids (48% and 24%, respectively). The oil yield was almost twice as high for the hot process as compared to the cold one. Additionally, hot pressing resulted in 25% higher total carotenoid content as compared to cold pressing, with β-carotene as the most abundant one. Hot and cold pressing showed no difference in oil oxidative stability and fatty acid composition. [es

Nanocrystalline Al-based alloys - lightweight materials with attractive mechanical properties

International Nuclear Information System (INIS)

Latuch, J; Cieslak, G; Dimitrov, H; Krasnowski, M; Kulik, T

2009-01-01

In this study, several ways of bulk nanocrystalline Al-based alloys' production by high-pressure compaction of powders were explored. The effect of chemical composition and compaction parameters on the structure, quality and mechanical properties of the bulk samples was studied. Bulk nanocrystalline Al-Mm-Ni-(Fe,Co) alloys were prepared by ball-milling of amorphous ribbons followed by consolidation. The maximum microhardness (540 HV0.1) was achieved for the samples compacted at 275 deg. C under 7.7 GPa (which resulted in an amorphous bulk) and nanocrystallised at 235 deg. C for 20 min. Another group of the produced materials were bulk nanocrystalline Al-Si-(Ni,Fe)-Mm alloys obtained by ball-milling of nanocrystalline ribbons and consolidation. The hardness of these samples achieved the value five times higher (350HV) than that of commercial 4xxx series Al alloys. Nanocrystalline Al-based alloys were also prepared by mechanical alloying followed by hot-pressing. In this group of materials, there were Al-Fe alloys containing 50-85 at.% of Al and ternary or quaternary Al-Fe-(Ti, Si, Ni, Mg, B) alloys. Microhardness of these alloys was in the range of 613 - 1235 HV0.2, depending on the composition.

Computational Prediction of Hot Spot Residues

Science.gov (United States)

Morrow, John Kenneth; Zhang, Shuxing

2013-01-01

Most biological processes involve multiple proteins interacting with each other. It has been recently discovered that certain residues in these protein-protein interactions, which are called hot spots, contribute more significantly to binding affinity than others. Hot spot residues have unique and diverse energetic properties that make them challenging yet important targets in the modulation of protein-protein complexes. Design of therapeutic agents that interact with hot spot residues has proven to be a valid methodology in disrupting unwanted protein-protein interactions. Using biological methods to determine which residues are hot spots can be costly and time consuming. Recent advances in computational approaches to predict hot spots have incorporated a myriad of features, and have shown increasing predictive successes. Here we review the state of knowledge around protein-protein interactions, hot spots, and give an overview of multiple in silico prediction techniques of hot spot residues. PMID:22316154

Improvement of the mechanical properties and corrosion resistance of biodegradable β-Ca3(PO4)2/Mg-Zn composites prepared by powder metallurgy: the adding β-Ca3(PO4)2, hot extrusion and aging treatment.

Science.gov (United States)

Yan, Yang; Kang, Yijun; Li, Ding; Yu, Kun; Xiao, Tao; Deng, Youwen; Dai, Han; Dai, Yilong; Xiong, Hanqing; Fang, Hongjie

2017-05-01

In this study, 10%β-Ca 3 (PO 4 ) 2 /Mg-6%Zn (wt.%) composites with Mg-6%Zn alloy as control were prepared by powder metallurgy. After hot extrusion, the as-extruded composites were aged for 72h at 150°C. The effects of the adding β-Ca 3 (PO 4 ) 2 , hot extrusion and aging treatment on their microstructure, mechanical properties and corrosion resistance were investigated. The XRD results identified α-Mg, MgZn phase and β-Ca 3 (PO 4 ) 2 phase in these composites. After hot extrusion, grains were significantly refined, and the larger-sized β-Ca 3 (PO 4 ) 2 particles and coarse MgZn phases were broken into linear-distributed β-Ca 3 (PO 4 ) 2 and MgZn phases along the extrusion direction. After aging treatment, the elements of Zn, Ca, P and O presented a more homogeneous distribution. The compressive strengths of the β-Ca 3 (PO 4 ) 2 /Mg-Zn composites were approximately double those of natural bone, and their densities and elastic moduli matched those of natural bone. The immersion tests and electrochemical tests revealed that the adding β-Ca 3 (PO 4 ) 2 , hot extrusion and aging treatment could promote the formation of protective corrosion product layer on the sample surface in Ringer's solution, which improved corrosion resistance of the β-Ca 3 (PO 4 ) 2 /Mg-Zn composites. The XRD results indicated that the corrosion product layer contained Mg(OH) 2 , β-Ca 3 (PO 4 ) 2 and hydroxyapatite (HA). The cytotoxicity assessments showed the as-extruded β-Ca 3 (PO 4 ) 2 /Mg-Zn composite aged for 72h was harmless to L-929 cells. These results suggested that the β-Ca 3 (PO 4 ) 2 /Mg-Zn composites prepared by powder metallurgy were promising to be used for bone tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

Experimental investigation on influence of porous material properties on drying process by a hot air jet

International Nuclear Information System (INIS)

Di Marco, P; Filippeschi, S

2012-01-01

The drying process of porous media is a subject of scientific interest, and different mathematical approaches can be found in the literature. A previous paper by the same authors showed that the celebrated Martin correlation for hot air jet heat and mass transfer yields different degrees of accuracy (from 15% to 65%, increasing at high values of input power) if tested on different fabrics, the remaining conditions being the same. In this paper the fabric drying has been experimentally investigated more in depth. A dedicated experimental apparatus for hot jet drying was assembled and operated, in which a hot jet impinges perpendicularly onto a wet fabric. A calibrated orifice was adopted to measure the jet flow rate, with an accuracy better than 3%. The drying power was determined by continuously weighing with a precision scale a moistened patch exposed to the drying jet. The effect of the time of the exposure and the initial amount of water has been evaluated for each sample. During the hot jet exposure, the temperature distribution over the wet patch has been observed by an infrared thermo-camera. A mathematical model of water transport inside and outside the fabric was developed, in order to evidence the governing transport resistances. The theoretical predictions have been compared with the experimental results, and showed the necessity to modify correlations and models accounting for fabric properties.

[Experimental study on two-way application of traditional Chinese medicines capable of promoting blood circulation and removing blood stasis with neutral property in cold and hot blood stasis syndrome I].

Science.gov (United States)

Hao, Er-Wei; Deng, Jia-Gang; Du, Zheng-Cai; Yan, Ke; Zheng, Zuo-Wen; Wang, Qin; Huang, Li-Zhen; Bao, Chuan-Hong; Deng, Xiu-Qiong; Lu, Xiao-Yan; Tang, Zhi-Ling

2012-11-01

To study the action characteristics of "two-way application and conditioned dominance" of traditional Chinese medicines with neutral property by observing the action characteristic of 10 traditional Chinese medicines capable of promoting blood circulation and removing blood stasis with neutral property in the microcirculation in rats with heat stagnation and blood stasis syndrome. The rat model with heat stagnation and blood stasis syndrome was established by injecting carrageenan and dry yeast, and the rat model with cold stagnation and blood stasis syndrome was built by the body freezing method. Ten traditional Chinese medicines with neutral property, including 5 with hot property and 5 with cold property, were selected for intervention to observe blood flow rate and flow state indicators in rat auricles and make a comparative analysis on action characteristics of traditional Chinese medicines with neutral property. ANOVA showed that among the 10 traditional Chinese medicines with neutral property, 6 such as Typhae Pollen, Sappan Lignum and Vaccariae Semen can obviously increase the blood flow rate (P traditional Chinese medicines with cold property can increase the blood flow rate (P medicines showed no notable effect; among the 5 traditional Chinese medicines with hot property, Carthamus tinctorius and Ligusticum chuanxiong can increase the blood flow rate (P traditional Chinese medicines with natural and cold properties showed similar effect on heat stagnation and blood stasis syndrome and better effect in increasing blood flow rate than those with hot property; those with natural and hot properties showed similar effect and better effect in increasing blood flow rate than those with cold property. Under the condition of heat stagnation and blood stasis syndrome, traditional Chinese medicines with neutral property have the similar action characteristics with those with cold property; wile under the condition of cold stagnation and blood stasis syndrome

Mechanical Properties of Composite Materials

Directory of Open Access Journals (Sweden)

Mitsuhiro Okayasu

2014-10-01

Full Text Available An examination has been made of the mechanical and failure properties of several composite materials, such as a short and a long carbon fiber reinforced plastic (short- and long-CFRP and metal based composite material. The short CFRP materials were used for a recycled CFRP which fabricated by the following process: the CFRP, consisting of epoxy resin with carbon fiber, is injected to a rectangular plate cavity after mixing with acrylonitrile butadiene styrene resin with different weight fractions of CFRP. The fatigue and ultimate tensile strength (UTS increased with increasing CFRP content. These correlations, however, break down, especially for tensile strength, as the CFPR content becomes more than 70%. Influence of sample temperature on the bending strength of the long-CFRP was investigated, and it appears that the strength slightly degreases with increasing the temperature, due to the weakness in the matrix. Broken fiber and pull-out or debonding between the fiber and matrix were related to the main failure of the short- and long-CFRP samples. Mechanical properties of metal based composite materials have been also investigated, where fiber-like high hardness CuAl2 structure is formed in aluminum matrix. Excellent mechanical properties were obtained in this alloy, e.g., the higher strength and the higher ductility, compared tothe same alloy without the fiber-like structure. There are strong anisotropic effects on the mechanical properties due to the fiber-like metal composite in a soft Al based matrix.

TEM study of a hot-pressed Al2O3-NbC composite material

Directory of Open Access Journals (Sweden)

Wilson Acchar

2005-03-01

Full Text Available Alumina-based composites have been developed in order to improve the mechanical properties of the monolithic matrix and to replace the WC-Co material for cutting tool applications. Al2O3 reinforced with refractory carbides improves hardness, fracture toughness and wear resistance to values suitable for metalworking applications. Al2O3-NbC composites were uniaxially hot-pressed at 1650 °C in an inert atmosphere and their mechanical properties and microstructures were analyzed. Sintered density, average grain size, microhardness and fracture toughness measurements and microstructural features were evaluated. Results have shown that the mechanical properties of alumina-NbC are comparable to other carbide systems. Microstructural analysis has shown that the niobium carbide particles are mainly located at the grain boundaries of alumina grains, which is an evidence of the "pinning effect", produced by NbC particles.

Casting defects and mechanical properties of high pressure die cast Mg-Zn-Al-RE alloys

Energy Technology Data Exchange (ETDEWEB)

Xiao, Wenlong; Easton, Mark A.; Zhu, Suming; Nie, Jianfeng [CAST Cooperative Research Centre, Department of Materials Engineering Monash University, Melbourne, VIC (Australia); Dargusch, Matthew S. [School of Mechanical and Mining Engineering, University of Queensland, Brisbane, QLD (Australia); Gibson, Mark A. [CSIRO Process Science and Engineering, Melbourne, VIC (Australia); Jia, Shusheng [Key Laboratory of Automobile Materials, Ministry of Education, Department of Materials Science and Engineering Jilin University, Changchun (China)

2012-02-15

The die casting defects and tensile properties of high pressure die cast (HPDC) Mg-Zn-Al-RE alloys with various combinations of Zn and Al were studied. The results show that die casting defects in Mg-Zn-Al-RE alloys are affected by the percentage of Zn and Al contents. The hot tearing susceptibility (HTS) of Mg-Zn-Al-RE alloys tends to increase with increasing Zn content up to 6 wt%, while a further increase of Al and/or Zn content reduces the HTS. In tensile tests, the yield strength (YS) is generally improved by increasing Zn or Al content, whereas the tensile strength (TS) and ductility appear to depend largely on the presence of casting defects. Compared with Mg-Zn-Al alloys, the mechanical properties of the Mg-Zn-Al-RE alloy are significantly improved. The Mg-4Zn-4Al-4RE alloy is found to have few casting defects and the optimal tensile properties. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Influence of stress on martensitic transformation and mechanical properties of hot stamped AHSS parts

International Nuclear Information System (INIS)

Chang, Y.; Li, X.D.; Zhao, K.M.; Wang, C.Y.; Zheng, G.J.; Hu, P.; Dong, H.

2015-01-01

Non-isothermal tension and compression tests of 22MnB5 boron steel were carried out in this study. How different stress state influences the martensitic transformation of advanced high strength steel (AHSS) parts was analyzed. The analysis reveals that the martensitic transformation starting temperature (M s ) changes with different stress states. Specifically, the M s temperature rises with increasing tensile stress, however, it rises first and then drops with increasing compressive stress. Moreover, a higher initial forming temperature leads to a higher M s temperature under the same stress. Simulation of an actual hot-formed AHSS B-pillar together with the microscopic metallography, hardness and martensitic content shows that in higher tensile stress dominated area, the martensitic content and hardness are usually higher than in other areas. Although the stress can promote the M s temperature, a lower cooling rate may lead to less martensite fraction

Influence of stress on martensitic transformation and mechanical properties of hot stamped AHSS parts

Energy Technology Data Exchange (ETDEWEB)

Chang, Y.; Li, X.D. [School of Automotive Engineering, National Key Laboratory of Industrial Equipment Structural Analysis, Dalian University of Technology, Dalian 116024 (China); Zhao, K.M., E-mail: kmzhao@dlut.edu.cn [School of Automotive Engineering, National Key Laboratory of Industrial Equipment Structural Analysis, Dalian University of Technology, Dalian 116024 (China); Wang, C.Y. [Institute for Special Steels, Central Iron & Steel Research Institute, Beijing 100081 (China); Zheng, G.J.; Hu, P. [School of Automotive Engineering, National Key Laboratory of Industrial Equipment Structural Analysis, Dalian University of Technology, Dalian 116024 (China); Dong, H. [Institute for Special Steels, Central Iron & Steel Research Institute, Beijing 100081 (China)

2015-04-01

Non-isothermal tension and compression tests of 22MnB5 boron steel were carried out in this study. How different stress state influences the martensitic transformation of advanced high strength steel (AHSS) parts was analyzed. The analysis reveals that the martensitic transformation starting temperature (M{sub s}) changes with different stress states. Specifically, the M{sub s} temperature rises with increasing tensile stress, however, it rises first and then drops with increasing compressive stress. Moreover, a higher initial forming temperature leads to a higher M{sub s} temperature under the same stress. Simulation of an actual hot-formed AHSS B-pillar together with the microscopic metallography, hardness and martensitic content shows that in higher tensile stress dominated area, the martensitic content and hardness are usually higher than in other areas. Although the stress can promote the M{sub s} temperature, a lower cooling rate may lead to less martensite fraction.

Study of anisotropic mechanical properties for aeronautical PMMA

Directory of Open Access Journals (Sweden)

Wei Shang

Full Text Available For the properties of polymer are relative to its structure, the main purpose of the present work is to investigate the mechanical properties of the aeronautical PMMA which has been treated by the directional tensile technology. Isodyne images reveal the stress state in directional PMMA. And then, an anisotropic mechanical model is established. Furthermore, all mechanical parameters are measured by the digital image correlation method. Finally, based on the anisotropic mechanical model and mechanical parameters, the FEM numerical simulation and experimental methods are applied to analyze the fracture mechanical properties along different directions.

Effect of yttrium addition on the microstructure and mechanical properties of ODS RAF steels

Energy Technology Data Exchange (ETDEWEB)

Auger, M.A., E-mail: maria.auger@materials.ox.ac.uk [Departamento de Física, Universidad Carlos III de Madrid, Av Universidad 30, 28911 Leganés (Spain); Department of Materials, University of Oxford, Parks Road, OX1 3PH Oxford (United Kingdom); Castro, V. de; Leguey, T.; Tarcísio-Costa, J.; Monge, M.A.; Muñoz, A.; Pareja, R. [Departamento de Física, Universidad Carlos III de Madrid, Av Universidad 30, 28911 Leganés (Spain)

2014-12-15

An oxide dispersion strengthened (ODS) alloy with nominal composition Fe–14Cr–2W–0.3Ti–0.24Y (wt.%) was produced by mechanical alloying using elemental powders, and subsequent hot isostatic pressing. The microstructure of the material and characteristics of the oxide particle dispersion were investigated by electron microscopy. The effect of heat treatments on the microhardness and tensile properties at room temperature was also studied. The results show that a fine dispersion of Y–O-rich nanoparticles is achieved, together with larger (Cr, Ti)-rich precipitates. The absence of Ti is apparent in the majority of these nanoparticles, in contrast with reported results for ODS Ti-modified steels processed with Y{sub 2}O{sub 3} addition.

Hot isostatic pressing of glass-zeolite composites

International Nuclear Information System (INIS)

Hash, M.C.; Pereira, C.; Lewis, M.A.

1996-01-01

Glass-zeolite waste forms are being developed for immobilizing the chloride waste salt generated from the electrometallurgical treatment of spent fuel. Glass-zeolite composites with high densities were made using hot isostatic pressing (HIP) techniques. Processing parameters were investigated to yield desirable structural ceramic properties such as mechanical, chemical, and thermal stability. Limits for these parameters were determined by differential thermal and thermogravimetric analysis. The resulting ceramic properties such as bulk density, open or apparent porosity, and leach resistance were determined. In addition, phase equilibria and particle-size distribution were observed by optical light and electron microscopy. Pre-HIP processing techniques were also studied to ensure intimate mixing of the glass and zeolite powders. Particle size distributions resulting from dry blending procedure are appropriate for needed flow and packing characteristics

Impact properties of reduced activation ferritic/martensitic steel, F82H jointed by hot isostatic pressing

Energy Technology Data Exchange (ETDEWEB)

Ogiwara, H.; Tanigawa, H. [Japan Atomic Energy Agency, Tokai-mura, Naga-gun, Ibaraki-ken (Japan); Hirose, T. [Blanket Engineering Group, Japan Atomic Energy Agency, Naka, Ibaraki (Japan); Enoeda, M. [Naka Fusion Research Establishment, J.A.E.R.I., Japan Atomic Energy Research Institute, Ibaraki-ken (Japan); Kohyama, A. [Kyoto Univ., lnstitute of Advanced Energy (Japan)

2007-07-01

Full text of publication follows: Reduced-activation ferritic/martensitic steels are the leading candidate structural material for the blanket system of fusion reactors. The important issue at the current stage is the finalization of a detailed manufacturing specification for ITER test blanket module. Hot isostatic pressing (HIP) process is one of the most important methods to fabricate the first wall with cooling channels. The objective of this paper is to optimize HIP condition to obtain the excellent joints mechanical properties. The materials used were F82H steels. The joint was produced by solid state HIP method. Before HIP treatments, specimens were heated in vacuum condition to out-gas. This treatment was conducted to decrease oxidation on the surfaces. HIP treatments were carried out for 2 h at 1100 deg. C - 140 MPa. The specimens were normalized at 960 deg. C for 0.5 h and tempered at 750 deg. C for 1.5 h. The bonding interface was characterized by scanning electron microscopy. Charpy impact tests and tensile tests were conducted to evaluate the mechanical properties of the HIP joint. Impact tests revealed that there were no significant differences in the ductile-brittle transition temperatures of HIP jointed specimens and base metal specimens, but the upper-shelf energy (USE) of the HIP joint specimens at room temperature was only about 10% of that of the base metal specimens. SEM observations of the fracture surface of HIP joint specimens revealed that a large number of oxides were formed on the HIP joint. This result indicates that oxides formed on the HIP joint are the dominant factor of the impact properties. Based on these results, the pre-HIP treatment conditions had been optimized to reduce the number of oxides, and USE of HIP joint specimens increased to about 50% of that of the base metal. The detailed analyses on the HIP joint microstructure will be reported. (authors)

Study on the Hot Extrusion Process of Advanced Radiation Resistant Oxide Dispersion Strengthened Steel Tubes

Energy Technology Data Exchange (ETDEWEB)

Choi, Byoungkwon; Noh, Sanghoon; Kim, Kibaik; Kang, Suk Hoon; Chun, Youngbum; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Ferritic/martensitic steel has a better thermal conductivity and swelling resistance than austenitic stainless steel. Unfortunately, the available temperature range of ferritic/martensitic steel is limited at up to 650 .deg. C. Oxide dispersion strengthened (ODS) steels have been developed as the most prospective core structural materials for next generation nuclear systems because of their excellent high strength and irradiation resistance. The material performances of this new alloy are attributed to the existence of uniformly distributed nano-oxide particles with a high density, which is extremely stable at high temperature in a ferritic/martensitic matrix. This microstructure can be very attractive in achieving superior mechanical properties at high temperatures, and thus, these favorable microstructures should be obtained through the controls of the fabrication process parameters during the mechanical alloying and hot consolidation procedures. In this study, a hot extrusion process for advanced radiation resistant ODS steel tube was investigated. ODS martensitic steel was designed to have high homogeneity, productivity, and reproducibility. Mechanical alloying and hot consolidation processes were employed to fabricate the ODS steels. A microstructure observation and creep rupture test were examined to investigate the effects of the optimized fabrication conditions. Advanced radiation resistant ODS steel has been designed to have homogeneity, productivity, and reproducibility. For these characteristics, modified mechanical alloying and hot consolidation processes were developed. Microstructure observation revealed that the ODS steel has uniformly distributed fine-grain nano-oxide particles. The fabrication process for the tubing is also being propelled in earnest.

Study on the Hot Extrusion Process of Advanced Radiation Resistant Oxide Dispersion Strengthened Steel Tubes

International Nuclear Information System (INIS)

Choi, Byoungkwon; Noh, Sanghoon; Kim, Kibaik; Kang, Suk Hoon; Chun, Youngbum; Kim, Tae Kyu

2014-01-01

Ferritic/martensitic steel has a better thermal conductivity and swelling resistance than austenitic stainless steel. Unfortunately, the available temperature range of ferritic/martensitic steel is limited at up to 650 .deg. C. Oxide dispersion strengthened (ODS) steels have been developed as the most prospective core structural materials for next generation nuclear systems because of their excellent high strength and irradiation resistance. The material performances of this new alloy are attributed to the existence of uniformly distributed nano-oxide particles with a high density, which is extremely stable at high temperature in a ferritic/martensitic matrix. This microstructure can be very attractive in achieving superior mechanical properties at high temperatures, and thus, these favorable microstructures should be obtained through the controls of the fabrication process parameters during the mechanical alloying and hot consolidation procedures. In this study, a hot extrusion process for advanced radiation resistant ODS steel tube was investigated. ODS martensitic steel was designed to have high homogeneity, productivity, and reproducibility. Mechanical alloying and hot consolidation processes were employed to fabricate the ODS steels. A microstructure observation and creep rupture test were examined to investigate the effects of the optimized fabrication conditions. Advanced radiation resistant ODS steel has been designed to have homogeneity, productivity, and reproducibility. For these characteristics, modified mechanical alloying and hot consolidation processes were developed. Microstructure observation revealed that the ODS steel has uniformly distributed fine-grain nano-oxide particles. The fabrication process for the tubing is also being propelled in earnest

Microstructure and Mechanical Properties of Fe-18Mn-18Cr-0.5N Austenitic Nonmagnetic Stainless Steel in Asymmetric Hot Rolling

Science.gov (United States)

Song, Y. L.; Li, C. S.; Ma, B.; Han, Y. H.

2017-05-01

Asymmetric hot rolling (ASHR) with a mismatch speed ratio of 1.15 in a single pass was applied to Fe-18Mn-18Cr-0.5N steel and was compared with symmetric hot rolling (SHR). The results indicated that a through-thickness microstructure gradient was formed in the plate due to the shear strain (0.36) introduced by ASHR. A fine-grained layer with the average size of 3 μm was achieved at the top surface of ASHR plate, while numerous elongated grains with a few recrystallized grains were presented at the center layer. The texture was distributed randomly at the top surface of ASHR plate, and a weaker intensity of typical hot-rolled texture in austenitic steel was obtained at the center layer of ASHR plate compared to SHR plate. An excellent combination of microhardness, strength and ductility was obtained in the ASHR plate, which was attributed to gradient microstructure induced by ASHR.

Efficient transfer of large-area graphene films onto rigid substrates by hot pressing.

Science.gov (United States)

Kang, Junmo; Hwang, Soonhwi; Kim, Jae Hwan; Kim, Min Hyeok; Ryu, Jaechul; Seo, Sang Jae; Hong, Byung Hee; Kim, Moon Ki; Choi, Jae-Boong

2012-06-26

Graphene films grown on metal substrates by chemical vapor deposition (CVD) method have to be safely transferred onto desired substrates for further applications. Recently, a roll-to-roll (R2R) method has been developed for large-area transfer, which is particularly efficient for flexible target substrates. However, in the case of rigid substrates such as glass or wafers, the roll-based method is found to induce considerable mechanical damages on graphene films during the transfer process, resulting in the degradation of electrical property. Here we introduce an improved dry transfer technique based on a hot-pressing method that can minimize damage on graphene by neutralizing mechanical stress. Thus, we enhanced the transfer efficiency of the large-area graphene films on a substrate with arbitrary thickness and rigidity, evidenced by scanning electron microscope (SEM) and atomic force microscope (AFM) images, Raman spectra, and various electrical characterizations. We also performed a theoretical multiscale simulation from continuum to atomic level to compare the mechanical stresses caused by the R2R and the hot-pressing methods, which also supports our conclusion. Consequently, we believe that the proposed hot-pressing method will be immediately useful for display and solar cell applications that currently require rigid and large substrates.

Present status of mechanical testing technology at the Research Hot Laboratory

International Nuclear Information System (INIS)

Kizaki, M.; Tobita, T.; Koya, T.; Kikuchi, T.

1993-01-01

Mechanical tests of irradiated metallic materials at the Research Hot Laboratory(RHL) have been carried out for 30 years to support material research in JAERI and to evaluate the irradiation integrity of pressure vessel steel in commercial power plant. Two tensile testing machines and one Charpy impact testing machine are available for the examinations. One of the tensile testing machines has 1000 kgf load capacity under the vacuum of ∼ 10 -7 torr at the temperature of 1300degC max.. The other one has 10 tonf load capacity, and is utilized for the multi-purpose tests such as tensile and compressive tests in air atmosphere at the temperature between -160 and 900degC. Examinations cover tensile test, bending test, J ic fracture toughness test, low cycle fatigue test and so on. Charpy impact testing machine with notched-bar specimen is instrumented with 30 kgf-m capacity in the temperature range of -140 - 240 degC. To support these mechanical tests in RHL, special jigs, devices and instruments have been developed. (author)

Effect of Titanium on the Microstructure and Mechanical Properties of High-Carbon Martensitic Stainless Steel 8Cr13MoV

Directory of Open Access Journals (Sweden)

Wen-Tao Yu

2016-08-01

Full Text Available The effect of titanium on the carbides and mechanical properties of martensitic stainless steel 8Cr13MoV was studied. The results showed that TiCs not only acted as nucleation sites for δ-Fe and eutectic carbides, leading to the refinement of the microstructure, but also inhibited the formation of eutectic carbides M7C3. The addition of titanium in steel also promoted the transformation of M7C3-type to M23C6-type carbides, and consequently more carbides could be dissolved into the matrix during hot processing as demonstrated by the determination of extracted carbides from the steel matrix. Meanwhile, titanium suppressed the precipitation of secondary carbides during annealing. The appropriate amount of titanium addition decreased the size and fraction of primary carbides in the as-cast ingot, and improved the mechanical properties of the annealed steel.

Determination of Proper Austenitization Temperatures for Hot Stamping of AISI 4140 Steel

Science.gov (United States)

Samadian, Pedram; Parsa, Mohammad Habibi; Shakeri, Amid

2014-04-01

High strength steels are desirable materials for use in automobile bodies in order to reduce vehicle weight and increase the safety of car passengers, but steel grades with high strength commonly show poor formability. Recently, steels with controlled microstructures and compositions are used to gain adequate strength after hot stamping while maintaining good formability during processing. In this study, microstructure evolutions and changes in mechanical properties of AISI 4140 steel sheets resulting from the hot stamping process at different austenitization temperatures were investigated. To determine the proper austenitization temperatures, the results were compared with those of the cold-worked and cold-worked plus quench-tempered specimens. Comparisons showed that the austenitization temperatures of 1000 and 1100 °C are proper for hot stamping of 3-mm-thick AISI 4140 steel sheets due to the resultant martensitic microstructure which led to the yield and ultimate tensile strength of 1.3 and 2.1 GPa, respectively. Such conditions resulted in more favorable simultaneous strength and elongation than those of hot-stamped conventional boron steels.

Microstructural analysis of hot press formed 22MnB5 steel

Science.gov (United States)

Aziz, Nuraini; Aqida, Syarifah Nur; Ismail, Izwan

2017-10-01

This paper presents a microstructural study on hot press formed 22MnB5 steel for enhanced mechanical properties. Hot press forming process consists of simultaneous forming and quenching of heated blank. The 22MnB5 steel was processed at three different parameter settings: quenching time, water temperature and water flow rate. 22MnB5 was processed using 33 full factorial design of experiment (DOE). The full factorial DOE was designed using three factors of quenching time, water temperature and water flow rate at three levels. The factors level were quenching time range of 5 - 11 s, water temperature; 5 - 27°C and water flow rate; 20 - 40 L/min. The as-received and hot press forming processed steel was characterised for metallographic study and martensitic structure area percentage using JEOL Field Emission Scanning Electron Microscopic (FESEM). From the experimental finding, the hot press formed 22MnB5 steel consisted of 50 to 84% martensitic structure area. The minimum quenching time of 8 seconds was required to obtain formed sample with high percentage of martensite. These findings contribute to initial design of processing parameters in hot press forming of 22MnB5 steel blanks for automotive component.

Mechanical Properties of Organic Semiconductors for Stretchable, Highly Flexible, and Mechanically Robust Electronics.

Science.gov (United States)

Root, Samuel E; Savagatrup, Suchol; Printz, Adam D; Rodriquez, Daniel; Lipomi, Darren J

2017-05-10

Mechanical deformability underpins many of the advantages of organic semiconductors. The mechanical properties of these materials are, however, diverse, and the molecular characteristics that permit charge transport can render the materials stiff and brittle. This review is a comprehensive description of the molecular and morphological parameters that govern the mechanical properties of organic semiconductors. Particular attention is paid to ways in which mechanical deformability and electronic performance can coexist. The review begins with a discussion of flexible and stretchable devices of all types, and in particular the unique characteristics of organic semiconductors. It then discusses the mechanical properties most relevant to deformable devices. In particular, it describes how low modulus, good adhesion, and absolute extensibility prior to fracture enable robust performance, along with mechanical "imperceptibility" if worn on the skin. A description of techniques of metrology precedes a discussion of the mechanical properties of three classes of organic semiconductors: π-conjugated polymers, small molecules, and composites. The discussion of each class of materials focuses on molecular structure and how this structure (and postdeposition processing) influences the solid-state packing structure and thus the mechanical properties. The review concludes with applications of organic semiconductor devices in which every component is intrinsically stretchable or highly flexible.

Effects of curing type, silica fume fineness, and fiber length on the mechanical properties and impact resistance of UHPFRC

Directory of Open Access Journals (Sweden)

Hasan Şahan Arel

Full Text Available The effects of silica fume fineness and fiber aspect ratio on the compressive strength and impact resistance of ultra high-performance fiber-reinforced concrete (UHPFRC are investigated experimentally. To this end, UHPFRC mixtures are manufactured by combining silica fumes with different fineness (specific surface areas: 17,200, 20,000, and 27,600 m2/kg and hooked-end steel fibers with various aspect ratios (lengths: 8, 13, and 16 mm. The samples are subjected to standard curing, steam curing, and hot-water curing. Compressive strength tests are conducted after 7-, 28-, 56-, and 90-day curing periods, and an impact resistance experiment is performed after the 90th day. A steam-cured mixture of silica fumes with a specific surface area of 27,600 m2/kg and 16-mm-long fibers produce better results than the other mixtures in terms of mechanical properties. Moreover, impact resistance increases with the fiber aspect ratio. Keywords: Curing, Fineness, UHPFRC, Mechanical properties, Fiber

Material development for grade X80 heavy-wall hot induction bends

Energy Technology Data Exchange (ETDEWEB)

Wang Xu [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); CNPC Bohai Petroleum Equipment Manufacture Co. Ltd., Qingxian 062658 (China); Xiao Furen, E-mail: frxiao@ysu.edu.cn [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Fu Yanhong [CNPC Bohai Petroleum Equipment Manufacture Co. Ltd., Qingxian 062658 (China); Chen Xiaowei [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); CNPC Bohai Petroleum Equipment Manufacture Co. Ltd., Qingxian 062658 (China); Liao Bo, E-mail: cyddjyjs@263.net [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

2011-12-15

Highlights: Black-Right-Pointing-Pointer The new material for X80 heavy wall thickness hot induction bend was designed. Black-Right-Pointing-Pointer The continuous cooling transformation (CCT) diagrams were determined. Black-Right-Pointing-Pointer The steel adapts to manufacture of X80 heavy-wall thickness hot induction bend. Black-Right-Pointing-Pointer The optimum manufactural processes were obtained. Black-Right-Pointing-Pointer The bending temperature is about 990 Degree-Sign C, and tempering is about 600 Degree-Sign C. - Abstract: A new steel for grade X80 heavy wall thickness hot induction bends was designed based on the chemical compositions of commercial X80 steels in this work. Then, its continuous cooling transformation (CCT) diagram was determined with Gleeble-3500 thermo-mechanical simulator. Furthermore, the effects of heat treatment technology on its microstructure and mechanical property were investigated, and the technology parameters of the heat treatment were optimized. The results show that the acicular ferrite and/or bainite transformations are promoted, the polygonal ferrite and pearlite transformation are restrained, because proper amount of alloying elements were added into the new steel. Therefore, the strength of this new steel is improved markedly, even if the cooling rate is lower, which ensure the higher strength distribution along cross section of the heavy wall thickness. It is significant for the manufacture of grade X80 heavy wall thickness hot induction bends in the second West-to-East gas transportation pipeline project of China.