Principles and techniques of radiation hardening. Volume 2. Transient radiation effects in electronics (TREE)

International Nuclear Information System (INIS)

Rudie, N.J.

1976-01-01

The three-volume book is intended to serve as a review of the effects of thermonuclear explosion induced radiation (x-rays, gamma rays, and beta particles) and the resulting electromagnetic pulse (EMP). Volume 2 deals with the following topics: radiation effects on quartz crystals, tantalum capacitors, bipolar semiconductor devices and integrated circuits, field effect transistors, and miscellaneous electronic devices; hardening electronic systems to photon and neutron radiation; nuclear radiation source and/or effects simulation techniques; and radiation dosimetry

Research on SEU hardening of heterogeneous Dual-Core SoC

Science.gov (United States)

Huang, Kun; Hu, Keliu; Deng, Jun; Zhang, Tao

2017-08-01

The implementation of Single-Event Upsets (SEU) hardening has various schemes. However, some of them require a lot of human, material and financial resources. This paper proposes an easy scheme on SEU hardening for Heterogeneous Dual-core SoC (HD SoC) which contains three techniques. First, the automatic Triple Modular Redundancy (TMR) technique is adopted to harden the register heaps of the processor and the instruction-fetching module. Second, Hamming codes are used to harden the random access memory (RAM). Last, a software signature technique is applied to check the programs which are running on CPU. The scheme need not to consume additional resources, and has little influence on the performance of CPU. These technologies are very mature, easy to implement and needs low cost. According to the simulation result, the scheme can satisfy the basic demand of SEU-hardening.

Assessment of surface hardening effects from shot peening on a Ni-based alloy using electron backscatter diffraction techniques

International Nuclear Information System (INIS)

Child, D.J.; West, G.D.; Thomson, R.C.

2011-01-01

An electron backscatter diffraction (EBSD)-based tool is described to assess the depth of strain-hardening effects of shot-peening treatments applied to the Ni-based superalloy, Udimet (copy right) alloy 720Li. The method consists of a statistical analysis of a number of data points from each grain scanned based on the grain orientation spread and their relative position from the shot-peened edge. The output is a quantitative measure of the depth of strain-hardening effects. The tool is used at various shot-peening intensities to demonstrate the ability to distinguish between these changes, using a range of intensities from 4 to 10 Almen. An increase in shot-peening intensity is observed to increase the depth of strain-hardening effects in the alloy. A comparison with residual stress measurements using X-ray diffraction for the same material shows that the strain-hardened depth determined by EBSD extends to approximately half the distance of the residual stress present due to shot peening. A comparison is also made with predicted profiles from the Peenstress SM model and subsequent microhardness testing. A positive correlation is observed between strained hardened depth and surface roughness of the peened samples. In each case, the increases in surface roughness and strain-hardened depth diminish toward the upper end of the shot-peening intensity range studied for this alloy.

Hardening and softening mechanisms of pearlitic steel wire under torsion

International Nuclear Information System (INIS)

Zhao, Tian-Zhang; Zhang, Shi-Hong; Zhang, Guang-Liang; Song, Hong-Wu; Cheng, Ming

2014-01-01

Highlights: • Mechanical behavior of pearlitic steel wire is studied using torsion. • Work hardening results from refinement lamellar pearlitic structure. • Softening results from recovery, shear bands and lamellar fragmentations. • A microstructure based analytical flow stress model is established. - Abstract: The mechanical behaviors and microstructure evolution of pearlitic steel wires under monotonic shear deformation have been investigated by a torsion test and a number of electron microscopy techniques including scanning electron microscopy (SEM) and transmission electron microscopy (TEM), with an aim to reveal the softening and hardening mechanisms of a randomly oriented pearlitic structure during a monotonic stain path. Significantly different from the remarkable strain hardening in cold wire drawing, the strain hardening rate during torsion drops to zero quickly after a short hardening stage. The microstructure observations indicate that the inter-lamellar spacing (ILS) decreases and the dislocations accumulate with strain, which leads to hardening of the material. Meanwhile, when the strain is larger than 0.154, the enhancement of dynamic recovery, shear bands (SBs) and cementite fragmentations results in the softening and balances the strain hardening. A microstructure based analytical flow stress model with considering the influence of ILS on the mean free path of dislocations and the softening caused by SBs and cementite fragmentations, has been established and the predicted flow shear curve meets well with the measured curve in the torsion test

Structure and properties of steel case-hardened by non-vacuum electron-beam cladding of carbon fibers

Science.gov (United States)

Losinskaya, A. A.; Lozhkina, E. A.; Bardin, A. I.

2017-12-01

At the present time, the actual problem of materials science is the increase in the steels performance characteristics. In the paper some mechanical properties of the case-hardened materials received by non-vacuum electron-beam cladding of carbon fibers are determined. The depth of the hardened layers varies from 1.5 to 3 mm. The impact strength of the samples exceeds 50 J/cm2. The wear resistance of the coatings obtained exceeds the properties of steel 20 after cementation and quenching with low tempering. The results of a study of the microhardness of the resulting layers and the microstructure are also given. The hardness of the surface layers exceeds 5700 MPa.

Effects of accelerated electron beam irradiation on surface hardening and fatigue properties in an AISI 4140 steel used for automotive crankshaft

Energy Technology Data Exchange (ETDEWEB)

Choo, S.-H.; Lee, S. [Pohang Univ. of Sci. and Technol. (Korea). Center for Adv. Aerospace Mater.; Golkovski, M.G. [Rossijskaya Akademiya Nauk, Novosibirsk (Russian Federation). Inst. Yadernoj Fiziki

2000-11-30

This study is concerned with the effects of high-energy accelerated electron beam irradiation on surface hardening and improvement of fatigue properties in an AISI 4140 steel currently used for automotive crankshaft. The 4140 steel specimens were irradiated in air by using a high-energy electron beam accelerator, and then microstructure, hardness, and fatigue properties were examined. Beam power was varied in the range of 5.2{proportional_to}7.7 kW by changing beam current. Upon irradiation, the unirradiated microstructure containing band structure was changed to martensite and bainite in the carbon-rich zone or ferrite, bainite, and martensite in the carbon-depleted zone. This microstructural modification improved greatly surface hardness and fatigue properties due to transformation of martensite whose amount and type were determined by heat input during irradiation. Thus, high-energy electron beam irradiation can be effectively applied to the surface hardening process of automotive parts. In order to investigate the thermal cycle during electron beam irradiation of quickly rotating specimens, the thermal analysis was also carried out using an analytical computer simulation. Analytical solutions gave information about the peak temperature, heating and cooling rate, and hardened depth to correlate with the overall microstructural modification. (orig.)

On the Spectral Hardening at gsim300 keV in Solar Flares

Science.gov (United States)

Li, G.; Kong, X.; Zank, G.; Chen, Y.

2013-05-01

It has long been noted that the spectra of observed continuum emissions in many solar flares are consistent with double power laws with a hardening at energies gsim300 keV. It is now widely believed that at least in electron-dominated events, the hardening in the photon spectrum reflects an intrinsic hardening in the source electron spectrum. In this paper, we point out that a power-law spectrum of electrons with a hardening at high energies can be explained by the diffusive shock acceleration of electrons at a termination shock with a finite width. Our suggestion is based on an early analytical work by Drury et al., where the steady-state transport equation at a shock with a tanh profile was solved for a p-independent diffusion coefficient. Numerical simulations with a p-dependent diffusion coefficient show hardenings in the accelerated electron spectrum that are comparable with observations. One necessary condition for our proposed scenario to work is that high-energy electrons resonate with the inertial range of the MHD turbulence and low-energy electrons resonate with the dissipation range of the MHD turbulence at the acceleration site, and the spectrum of the dissipation range ~k -2.7. A ~k -2.7 dissipation range spectrum is consistent with recent solar wind observations.

ON THE SPECTRAL HARDENING AT ∼>300 keV IN SOLAR FLARES

International Nuclear Information System (INIS)

Li, G.; Kong, X.; Zank, G.; Chen, Y.

2013-01-01

It has long been noted that the spectra of observed continuum emissions in many solar flares are consistent with double power laws with a hardening at energies ∼>300 keV. It is now widely believed that at least in electron-dominated events, the hardening in the photon spectrum reflects an intrinsic hardening in the source electron spectrum. In this paper, we point out that a power-law spectrum of electrons with a hardening at high energies can be explained by the diffusive shock acceleration of electrons at a termination shock with a finite width. Our suggestion is based on an early analytical work by Drury et al., where the steady-state transport equation at a shock with a tanh profile was solved for a p-independent diffusion coefficient. Numerical simulations with a p-dependent diffusion coefficient show hardenings in the accelerated electron spectrum that are comparable with observations. One necessary condition for our proposed scenario to work is that high-energy electrons resonate with the inertial range of the MHD turbulence and low-energy electrons resonate with the dissipation range of the MHD turbulence at the acceleration site, and the spectrum of the dissipation range ∼k –2.7 . A ∼k –2.7 dissipation range spectrum is consistent with recent solar wind observations.

The microstructural origin of work hardening stages

DEFF Research Database (Denmark)

Hughes, D. A.; Hansen, N.

2018-01-01

The strain evolution of the flow stress and work hardening rate in stages III and IV is explored by utilizing a fully described deformation microstructure. Extensive measurements by transmission electron microscopy reveal a hierarchical subdivision of grains by low angle incidental dislocation...... addition of the classical Taylor and Hall-Petch formulations. Model predictions agree closely with experimental values of flow stress and work hardening rate in stages III and IV. Strong connections between the evolutionary stages of the deformation microstructure and work hardening rates create a new...... (modern) basis for the classic problem of work hardening in metals and alloys. These connections lead the way for the future development of ultra high strength ductile metals produced via plastic deformation.(c) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved....

Why semiconductors must be hardened when used in space

International Nuclear Information System (INIS)

Winokur, P.S.

2000-01-01

The natural space radiation environment presents a great challenge to present and future satellite systems with significant assets in space. Defining requirements for such systems demands knowledge about the space radiation environment and its effects on electronics and optoelectronics technologies, as well as suitable risk assessment of the uncertainties involved. For mission of high radiation levels, radiation-hardened integrated circuits will be required to preform critical mission functions. The most successful systems in space will be those that are best able to blend standard commercial electronics with custom radiation-hardened electronics in a mix that is suitable for the system of interest

[Microstructural changes in hardened beans (Phaseolus vulgaris)].

Science.gov (United States)

Mujica, Maria Virginia; Granito, Marisela; Soto, Naudy

2015-06-01

(Phaseolus vulgaris). The hardening of Phaseolus vulgaris beans stored at high temperature and high relative humidity is one of the main constraints for consumption. The objective of this research was to evaluate by scanning electron microscopy, structural changes in cotyledons and testa of the hardened beans. The freshly harvested grains were stored for twelve months under two conditions: 5 ° C-34% RH and 37 ° C-75% RH, in order to promote hardening. The stored raw and cooked grains were lyophilized and fractured. The sections of testa and cotyledons were observed in an electron microscope JSM-6390. After twelve months, grains stored at 37 ° C-75% RH increased their hardness by 503%, whereas there were no significant changes in grains stored at 5 ° C-34% RH. At the microstructural level, the cotyledons of the raw grains show clear differences in appearance of the cell wall, into the intercellular space size and texture matrix protein. There were also differences in compaction of palisade and sub-epidermal layer in the testa of raw grains. After cooking, cotyledon cells of the soft grains were well separated while these ofhard grains were seldom separated. In conclusion, the found differences in hard and soft grains showed a significant participation of both structures, cotyledons and testa, in the grains hardening.

Bake hardening of nanograin AA7075 aluminum alloy

International Nuclear Information System (INIS)

Dehghani, Kamran

2011-01-01

Highlights: ► The bake hardening behavior of AA7075 was studied and compared with its coarse-grain counterpart. ► Nanograin AA7075 exhibited 88–100% increase in bake hardenability. ► Nanograin AA7075 exhibited 36–38% increase in final yield strength after baking. ► Maximum bake hardenability and final yield stress were about 185 MPa and 719 MPa. - Abstract: In the present work, the bake hardening of nanostructured AA7075 aluminum alloy was compared with that of its coarse-grain counterpart. Surface severe plastic deformation (SSPD) was used to produce nanograin layers on both surfaces of workpieces. The nanostructured layers were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The thickness of nanostructured layer, having the grains of 50–110 nm, was about 75 μm on each side of workpiece. The bake hardenability of nanograin and coarse-grain AA7075 was then compared by pre-straining to 2, 4 and 6% followed by baking at 100 °C and 200 °C for 20 min. Comparing to coarse-grain case, there was about 88–100% increase in bake hardenability and about 36–38% increase in yield strength after the bake hardening of present nanograin AA7075. Such an increase in bake hardenability and strength was achieved when the thickness of two nanograin layers was about only one-tenth of the whole thickness.

Radiation hardening of metals irradiated by heavy ions

International Nuclear Information System (INIS)

Didyk, A.Yu.; Skuratov, V.A.; Mikhajlova, N.Yu.; Regel', V.R.

1988-01-01

The damage dose dependence in the 10 -4 -10 -2 dpa region of radiation hardening of Al, V, Ni, Cu irradiated by xenon ions with 124 MeV energy is investigated using the microhardness technique and transmission electron microscope. It is shown that the pure metals radiation hardening is stimulated for defects clusters with the typical size less than 5 nm, as in the case of neutron and the light charge ion irradiation

Precipitation and Hardening in Magnesium Alloys

Science.gov (United States)

Nie, Jian-Feng

2012-11-01

Magnesium alloys have received an increasing interest in the past 12 years for potential applications in the automotive, aircraft, aerospace, and electronic industries. Many of these alloys are strong because of solid-state precipitates that are produced by an age-hardening process. Although some strength improvements of existing magnesium alloys have been made and some novel alloys with improved strength have been developed, the strength level that has been achieved so far is still substantially lower than that obtained in counterpart aluminum alloys. Further improvements in the alloy strength require a better understanding of the structure, morphology, orientation of precipitates, effects of precipitate morphology, and orientation on the strengthening and microstructural factors that are important in controlling the nucleation and growth of these precipitates. In this review, precipitation in most precipitation-hardenable magnesium alloys is reviewed, and its relationship with strengthening is examined. It is demonstrated that the precipitation phenomena in these alloys, especially in the very early stage of the precipitation process, are still far from being well understood, and many fundamental issues remain unsolved even after some extensive and concerted efforts made in the past 12 years. The challenges associated with precipitation hardening and age hardening are identified and discussed, and guidelines are outlined for the rational design and development of higher strength, and ultimately ultrahigh strength, magnesium alloys via precipitation hardening.

Radiation Hardened Electronics Destined For Severe Nuclear Reactor Environments

Energy Technology Data Exchange (ETDEWEB)

Holbert, Keith E. [Arizona State Univ., Tempe, AZ (United States); Clark, Lawrence T. [Arizona State Univ., Tempe, AZ (United States)

2016-02-19

Post nuclear accident conditions represent a harsh environment for electronics. The full station blackout experience at Fukushima shows the necessity for emergency sensing capabilities in a radiation-enhanced environment. This NEET (Nuclear Energy Enabling Technologies) research project developed radiation hardened by design (RHBD) electronics using commercially available technology that employs commercial off-the-shelf (COTS) devices and present generation circuit fabrication techniques to improve the total ionizing dose (TID) hardness of electronics. Such technology not only has applicability to severe accident conditions but also to facilities throughout the nuclear fuel cycle in which radiation tolerance is required. For example, with TID tolerance to megarads of dose, electronics could be deployed for long-term monitoring, inspection and decontamination missions. The present work has taken a two-pronged approach, specifically, development of both board and application-specific integrated circuit (ASIC) level RHBD techniques. The former path has focused on TID testing of representative microcontroller ICs with embedded flash (eFlash) memory, as well as standalone flash devices that utilize the same fabrication technologies. The standalone flash devices are less complicated, allowing better understanding of the TID response of the crucial circuits. Our TID experiments utilize biased components that are in-situ tested, and in full operation during irradiation. A potential pitfall in the qualification of memory circuits is the lack of rigorous testing of the possible memory states. For this reason, we employ test patterns that include all ones, all zeros, a checkerboard of zeros and ones, an inverse checkerboard, and random data. With experimental evidence of improved radiation response for unbiased versus biased conditions, a demonstration-level board using the COTS devices was constructed. Through a combination of redundancy and power gating, the demonstration

Electronic Resource Management and Design

Science.gov (United States)

Abrams, Kimberly R.

2015-01-01

We have now reached a tipping point at which electronic resources comprise more than half of academic library budgets. Because of the increasing work associated with the ever-increasing number of e-resources, there is a trend to distribute work throughout the library even in the presence of an electronic resources department. In 2013, the author…

Process for hardening an alkyd resin composition using ionizing radiation. [electron beams, gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Watanabe, T; Murata, K; Maruyama, T

1969-11-27

In an alkyd resin composition having free hydroxide radicals and containing a conjugated unsaturated fatty acid and/or oil as a component thereof, a process for hardening an alkyd resin composition comprises the steps of dissolving into a vinyl monomer, the product obtained by the semi-esterification reaction of said hydroxide radicals with acid anhydrides having polymerizable radicals and hardening by ionizing radiation to provide a coating with a high degree of cross-linking, with favorable properties such as toughness, hardness, chemical resistance and resistance to weather and with the feasibility of being applied as the ground and finish coat on metals, wood, paper, outdoor construction or the like. Any kind of ionization radiation, particularly accelerated electron beams, ..gamma.. radiation can be used at 50/sup 0/C to -5/sup 0/C for a few seconds or minutes, permitting continuous operation. In one example, 384 parts of phthalic anhydride, 115 parts of pentaerythritol, 233 parts of trimethylol ethane, 288 parts of tung fatty acid and 49 parts of para-tertiary-butyl benzoic acid are mixed and heated with 60 parts of xylene to an acid value of 12. In addition, 271 parts of maleic anhydride and 0.6 parts of hydroquinone are admixed with the content and heated to terminate the reaction. 100 parts of a 50% stylene solution of this alkyd resin are mixed with 1 part of a 60% toluene solution of cobalt naphthenate, and then coated on a glass plate and irradiated with high energy electron beams of 300 kV with a dose of 5 Mrad for 1 sec.

Investigation of secondary hardening in Co–35Ni–20Cr–10Mo alloy using analytical scanning transmission electron microscopy

International Nuclear Information System (INIS)

Sorensen, D.; Li, B.Q.; Gerberich, W.W.; Mkhoyan, K.A.

2014-01-01

The mechanism of secondary hardening in MP35N (Co–35Ni–20Cr–10Mo) alloy due to exposures at elevated temperatures has been studied. It was observed that short exposure to elevated temperatures increased the ultimate tensile strength and yield stress while decreasing the elongation of MP35N wires. Upon aging at temperatures from 300 to 900 °C the elastic modulus increased although no changes in crystallographic orientation or microstructure were observed. The grain size and major texture components were unchanged following aging. Analytical scanning transmission electron microscope investigation showed that MP35N is hardened by preferential segregation of molybdenum to stacking faults and deformation twins. It also revealed that the concentration of molybdenum segregation was proportional to the amount of initial cold work before aging

The secondary hardening phenomenon in strain-hardened MP35N alloy

International Nuclear Information System (INIS)

Asgari, S.; El-Danaf, E.; Shaji, E.; Kalidindi, S.R.; Doherty, R.D.

1998-01-01

Mechanical testing and microscopy techniques were used to investigate the influence of aging on the structure and strengthening of MP35N alloy. It was confirmed that aging the deformed material at 600 C for 4 h provided additional strengthening, here referred to as secondary hardening, in addition to the primary strain hardening. The secondary hardening phenomenon was shown to be distinctly different from typical age hardening processes in that it only occurred in material deformed beyond a certain cold work level. At moderate strains, aging caused a shift in the entire stress-strain curve of the annealed material to higher stresses while at high strains, it produced shear localization and limited work softening. The secondary hardening increment was also found to be grain size dependent. The magnitude of the secondary hardening appeared to be controlled by the flow stress in the strain hardened material. A model is proposed to explain the observations and is supported by direct experimental evidence. The model is based on formation of h.c.p. nuclei through the Suzuki mechanism, that is segregation of solute atoms to stacking faults, on aging the strain hardened material. The h.c.p. precipitates appear to thicken only in the presence of high dislocation density produced by prior cold work

Simultaneous surface engineering and bulk hardening of precipitation hardening stainless steel

DEFF Research Database (Denmark)

Frandsen, Rasmus Berg; Christiansen, Thomas; Somers, Marcel A. J.

2006-01-01

This article addresses simultaneous bulk precipitation hardening and low temperature surface engineering of two commercial precipitation hardening stainless steels: Sandvik Nanoflex® and Uddeholm Corrax®. Surface engineering comprised gaseous nitriding or gaseous carburising. Microstructural....... The duration and temperature of the nitriding/carburising surface hardening treatment can be chosen in agreement with the thermal treatment for obtaining optimal bulk hardness in the precipitation hardening stainless steel....... characterisation of the cases developed included X-ray diffraction analysis, reflected light microscopy and micro-hardness testing. It was found that the incorporation of nitrogen or carbon resulted in a hardened case consisting of a combination of (tetragonal) martensite and expanded (cubic) austenite...

Microstructural changes and strain hardening effects in abrasive contacts at different relative velocities and temperatures

Energy Technology Data Exchange (ETDEWEB)

Rojacz, H., E-mail: rojacz@ac2t.at [AC2T research GmbH, Viktor-Kaplan-Straße 2C, 2700 Wiener Neustadt (Austria); Mozdzen, G. [Aerospace & Advanced Composites GmbH, Viktor-Kaplan-Straße 2F, 2700 Wiener Neustadt (Austria); Weigel, F.; Varga, M. [AC2T research GmbH, Viktor-Kaplan-Straße 2C, 2700 Wiener Neustadt (Austria)

2016-08-15

Strain hardening is commonly used to reach the full potential of materials and can be beneficial in tribological contacts. 2-body abrasive wear was simulated in a scratch test, aimed at strain hardening effects in various steels. Different working conditions were examined at various temperatures and velocities. Strain hardening effects and microstructural changes were analysed with high resolution scanning electron microscopy (HRSEM), electron backscatter diffraction (EBSD), micro hardness measurements and nanoindentation. Statistical analysing was performed quantifying the influence of different parameters on microstructures. Results show a crucial influence of temperature and velocity on the strain hardening in tribological contacts. Increased velocity leads to higher deformed microstructures and higher increased surface hardness at a lower depth of the deformed zones at all materials investigated. An optimised surface hardness can be achieved knowing the influence of velocity (strain rate) and temperature for a “tailor-made” surface hardening in tribological systems aimed at increased wear resistance. - Highlights: •Hardening mechanisms and their intensity in tribological contacts are dependent on relative velocity and temperature. •Beneficial surface hardened zones are formed at certain running-in conditions; the scientific background is presented here. •Ferritic-pearlitic steels strain hardens via grain size reduction and decreasing interlamellar distances in pearlite. •Austenitic steels show excellent surface hardening (120% hardness increase) by twinning and martensitic transformation. •Ferritic steels with hard phases harden in the ferrite phase as per Hall-Petch equation and degree of deformation.

Microstructural changes and strain hardening effects in abrasive contacts at different relative velocities and temperatures

International Nuclear Information System (INIS)

Rojacz, H.; Mozdzen, G.; Weigel, F.; Varga, M.

2016-01-01

Strain hardening is commonly used to reach the full potential of materials and can be beneficial in tribological contacts. 2-body abrasive wear was simulated in a scratch test, aimed at strain hardening effects in various steels. Different working conditions were examined at various temperatures and velocities. Strain hardening effects and microstructural changes were analysed with high resolution scanning electron microscopy (HRSEM), electron backscatter diffraction (EBSD), micro hardness measurements and nanoindentation. Statistical analysing was performed quantifying the influence of different parameters on microstructures. Results show a crucial influence of temperature and velocity on the strain hardening in tribological contacts. Increased velocity leads to higher deformed microstructures and higher increased surface hardness at a lower depth of the deformed zones at all materials investigated. An optimised surface hardness can be achieved knowing the influence of velocity (strain rate) and temperature for a “tailor-made” surface hardening in tribological systems aimed at increased wear resistance. - Highlights: •Hardening mechanisms and their intensity in tribological contacts are dependent on relative velocity and temperature. •Beneficial surface hardened zones are formed at certain running-in conditions; the scientific background is presented here. •Ferritic-pearlitic steels strain hardens via grain size reduction and decreasing interlamellar distances in pearlite. •Austenitic steels show excellent surface hardening (120% hardness increase) by twinning and martensitic transformation. •Ferritic steels with hard phases harden in the ferrite phase as per Hall-Petch equation and degree of deformation.

TH-CD-202-02: A Preliminary Study Evaluating Beam-Hardening Artifact Reduction On CT Direct Electron-Density Images

Energy Technology Data Exchange (ETDEWEB)

Li, H; Dolly, S; Zhao, T; Anastasio, M; Mutic, S [Washington University School of Medicine, Saint Louis, MO (United States); Ritter, A; Colombo, V; Raupach, R; Huenemohr, N [Siemens Healthcare GmbH, Deutschland (Germany); Mistry, N [Siemens Medical Solutions USA, Malvern, PA (United States); Yu, L [Mayo Clinic, Rochester, MN (United States)

2016-06-15

Purpose: A prototype reconstruction algorithm that can provide direct electron density (ED) images from single energy CT scans is being currently developed by Siemens Healthcare GmbH. This feature can eliminate the need for kV specific calibration curve for radiation treatemnt planning. An added benefit is that beam-hardening artifacts are also reduced on direct-ED images due to the underlying material decomposition. This study is to quantitatively analyze the reduction of beam-hardening artifacts on direct-ED images and suggest additional clinical usages. Methods: HU and direct-ED images were reconstructed on a head phantom scanned on a Siemens Definition AS CT scanner at five tube potentials of 70kV, 80kV, 100kV, 120kV and 140kV respectively. From these images, mean, standard deviation (SD), and local NPS were calculated for regions of interest (ROI) of same locations and sizes. A complete analysis of beam-hardening artifact reduction and image quality improvement was conducted. Results: Along with the increase of tube potentials, ROI means and SDs decrease on both HU and direct-ED images. The mean value differences between HU and direct-ED images are up to 8% with absolute value of 2.9. Compared to that on HU images, the SDs are lower on direct-ED images, and the differences are up to 26%. Interestingly, the local NPS calculated from direct-ED images shows consistent values in the low spatial frequency domain for images acquired from all tube potential settings, while varied dramatically on HU images. This also confirms the beam -hardening artifact reduction on ED images. Conclusions: The low SDs on direct-ED images and relative consistent NPS values in the low spatial frequency domain indicate a reduction of beam-hardening artifacts. The direct-ED image has the potential to assist in more accurate organ contouring, and is a better fit for the desired purpose of CT simulations for radiotherapy.

Structure of hardened alloys of Sr-Rh system

International Nuclear Information System (INIS)

Dobromyslov, A.V.; Taluth, N.I.

1997-01-01

Methods of X-ray diffraction analysis, optical metallography, transmission electron microscopy and hardness measurement were applied to study the structure of hardened zirconium-rhodium system alloys with rhodium contents up to 4.5 at.%. It is shown that in hardening alloys with rhodium concentration lower 2.2 at.% the eutectoid decomposition takes place and bainite-like structure is formed. A metastable ω-phase is formed in alloys with rhodium concentration equal to 2.65 at.% and above. The formation of ω-phase suppresses the process of eutectoid decomposition

Surface Induction Hardening of Axi-Symmetric Bodies

Czech Academy of Sciences Publication Activity Database

Barglik, J.; Doležel, Ivo; Škopek, M.; Ulrych, B.

2001-01-01

Roč. 1, č. 1 (2001), s. 11-16 ISSN 1335-8243 R&D Projects: GA ČR GA102/01/0184 Grant - others:-(PL) 7T08603716 Keywords : induction heating * induction hardening * numerical solution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

A hardenability test proposal

Energy Technology Data Exchange (ETDEWEB)

Murthy, N.V.S.N. [Ingersoll-Rand (I) Ltd., Bangalore (India)

1996-12-31

A new approach for hardenability evaluation and its application to heat treatable steels will be discussed. This will include an overview and deficiencies of the current methods and discussion on the necessity for a new approach. Hardenability terminology will be expanded to avoid ambiguity and over-simplification as encountered with the current system. A new hardenability definition is proposed. Hardenability specification methods are simplified and rationalized. The new hardenability evaluation system proposed here utilizes a test specimen with varying diameter as an alternative to the cylindrical Jominy hardenability test specimen and is readily applicable to the evaluation of a wide variety of steels with different cross-section sizes.

Comparison of Thermal Creep Strain Calculation Results Using Time Hardening and Strain Hardening Rules

International Nuclear Information System (INIS)

Kim, Junehyung; Cheon, Jinsik; Lee, Byoungoon; Lee, Chanbock

2014-01-01

One of the design criteria for the fuel rod in PGSFR is the thermal creep strain of the cladding, because the cladding is exposed to a high temperature for a long time during reactor operation period. In general, there are two kind of calculation scheme for thermal creep strain: time hardening and strain hardening rules. In this work, thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules are compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule are compared with those by using MACSIS. Thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules were compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule were compared with those by using MACSIS. Tertiary creep started earlier in time hardening rule than in strain hardening rule. Also, calculation results by MACSIS with strain hardening and those obtained by using LIFE-METAL were almost identical to each other

Radiation hardening coating material

International Nuclear Information System (INIS)

McDonald, W.H.; Prucnal, P.J.; DeMajistre, Robert.

1977-01-01

This invention concerns a radiation hardening coating material. First a resin is prepared by reaction of bisphenol diglycidylic ether with acrylic or methacrylic acids. Then the reactive solvent is prepared by reaction of acrylic or methacrylic acids with epichlorhydrine or epibromhydrine. Then a solution consisting of the resin dissolved in the reactive solvent is prepared. A substrate (wood, paper, polyesters, polyamines etc.) is coated with this composition and exposed to ionizing radiations (electron beams) or ultraviolet radiations [fr

Radiation-hardenable diluents for radiation-hardenable compositions

International Nuclear Information System (INIS)

Schuster, K.E.; Rosenkranz, H.J.; Furh, K.; Ruedolph, H.

1979-01-01

Radiation-crosslinkable diluents for radiation-hardenable compositions (binders) consisting of a mixture of triacrylates of a reaction product of trimethylol propane and ethylene oxide with an average degree of ethoxylation of from 2.5 to 4 are described. The ethoxylated trimethylol propane is substantially free from trimethylol propane and has the following distribution: 4 to 5% by weight of monoethoxylation product, 14 to 16% by weight of diethoxylation product, 20 to 30% by weight of triethoxylation product, 20 to 30% by weight of tetraethoxylation product, 16 to 18% by weight of pentaethoxylation product, and 6 to 8% by weight of hexaethoxylation product. The diluents effectively reduce the viscosity of radiation-hardenable compositions and do not have any adverse effect upon their reactivity or upon the properties of the resulting hardened products

Influence of Cooling Condition on the Performance of Grinding Hardened Layer in Grind-hardening

Science.gov (United States)

Wang, G. C.; Chen, J.; Xu, G. Y.; Li, X.

2018-02-01

45# steel was grinded and hardened on a surface grinding machine to study the effect of three different cooling media, including emulsion, dry air and liquid nitrogen, on the microstructure and properties of the hardened layer. The results show that the microstructure of material surface hardened with emulsion is pearlite and no hardened layer. The surface roughness is small and the residual stress is compressive stress. With cooling condition of liquid nitrogen and dry air, the specimen surface are hardened, the organization is martensite, the surface roughness is also not changed, but high hardness of hardened layer and surface compressive stress were obtained when grinding using liquid nitrogen. The deeper hardened layer grinded with dry air was obtained and surface residual stress is tensile stress. This study provides an experimental basis for choosing the appropriate cooling mode to effectively control the performance of grinding hardened layer.

Electron bombardment cross-linking of coating materials. Pt.2. Analysis of patent literature on formulating radiation-hardenable binders

International Nuclear Information System (INIS)

Mileo, J.-C.

1976-01-01

The process of drying paints and varnishes by electron irradiation is analyzed from the chemical standpoint. A review is made of the different methods of producing radiation hardenable resins that have resulted in abundant patent literature. These resins are classified according to the nature of the reactive unsaturations they contain: unsaturations of the maleic ester type; simple (meth)acrylic esters and amides; β-hydroxyl (meth)acrylic esters, their (un)saturated esters and other derivatives; siloxanes; maleimides; allylic unsaturations; saturated resins [fr

Exploration of a radiation hardening stabilized voltage power supply

International Nuclear Information System (INIS)

Xie Zeyuan; Xu Xianguo

2014-01-01

This paper mainly introduces the design method of radiation hardening stabilized voltage power supply that makes use of commercial radiation resistant electronic devices and the test results of radiation performance of the power supply and devices are presented in detail. The experiment results show that the hardened power supply can normally work until 1000 Gy (Si) total dose and 1 × 10 14 n/cm 2 neutron radiation, and it doesn't latchup at about 1 × l0 9 Gy (Si)/s gamma transient dose rate. (authors)

Hardening mechanism of an Ag-Pd-Cu-Au dental casting alloy

International Nuclear Information System (INIS)

Seol, Hyo-Joung; Kim, Gi-Chul; Son, Kuk-Hyeon; Kwon, Yong Hoon; Kim, Hyung-Il

2005-01-01

Age-hardening behaviour and the related microstructural changes were studied to elucidate the hardening mechanism of an Ag-Pd-Cu-Au dental casting alloy by means of hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and electron probe microanalysis (EPMA). By considering hardness test and XRD results together, it was revealed that the hardness increased during the early stage of phase transformation of α into α 1 . In the SEM photographs, two phases of matrix and particle-like structures were observed, and the precipitation of element from the matrix progressed during isothermal aging. By SEM observations and EPMA analysis, it could be supposed that the increase in hardness was caused by the diffusion and aggregation of Cu atoms from the Ag-rich α matrix containing Au and Cu in the early stage of age-hardening process, and that the decrease in hardness was caused by the progress of coarsening of Cu-rich lamellar precipitates in the later stage of the age-hardening process. The changes in the Ag-rich matrix caused both the increase and decrease in hardness, and the CuPd phase containing small amounts of Zn and Sn did not contribute to the hardness changes

Nuclear effects hardened shelters

International Nuclear Information System (INIS)

Lindke, P.

1990-01-01

This paper reports on the Houston Fearless 76 Government Projects Group that has been actively engaged for more than twenty-five years as a sub-contractor and currently as a prime contractor in the design, manufacture, repair and logistics support of custom mobile ground stations and their equipment accommodations. Other associated products include environmental control units (ECU's), mobilizers for shelters and a variety of mobile power generation units (MPU's). Since 1984, Houston Fearless 76 has designed and manufactured four 8 foot by 8 foot x 22 foot nuclear hardened mobile shelters. These shelters were designed to contain electronic data processing/reduction equipment. One shelter is currently being operated by the Air Force as a Defense Intelligence Agency (DIA) approved and certified Special Compartmented Information Facility (SCIF). During the development and manufacturing process of the shelters, we received continual technical assistance and design concept evaluations from Science Applications International Corporation (SAIC) Operations Analysis and Logistics Engineering Division and the Nondestructive Inspection Lab at McClellan AFB. SAIC was originally employed by the Air Force to design the nuclear hardening specifications applied to these shelters

Precipitation hardening of a Cu-free Au-Ag-Pd-In dental alloy

Energy Technology Data Exchange (ETDEWEB)

Seol, Hyo-Joung [Department of Dental Materials, College of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of); Son, Kuk-Hyeon [Department of Dental Materials, College of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of); Yu, Chin-Ho [Department of Dental Materials, College of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of); Kwon, Yong Hoon [Department of Dental Materials, College of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of); Kim, Hyung-Il [Department of Dental Materials, College of Dentistry and Research Institute for Oral Biotechnology, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of)]. E-mail: hilkim@pusan.ac.kr

2005-10-27

The hardening mechanism and related microstructural changes of the Cu-free dental casting alloy composed of Au-Ag-Pd-In was examined by means of hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and electron probe microanalysis (EPMA). The Au-Ag-Pd-In alloy showed apparent age-hardenability. In the SEM photograph, three phases were observed in the solution-treated specimen, that is, the Au-Ag based phase with small amounts of In and Pd as matrix, the InPd phase as particle-like structures, and the Pd-rich phase as lamellar precipitates. By aging the specimen, the very fine Pd-rich inter-granular precipitates grew toward the grain interior as lamellar structure, and finally the coarsened Pd-rich precipitates covered a large part of the Au-Ag based matrix. The hardness increase in the early stage of the age-hardening process was assumed to be caused by the diffusion and aggregation of Pd atoms from the Au-Ag based matrix. The hardness decrease in the later stage of age-hardening process was caused by coarsening of the lamellar precipitates composed of the Pd-rich phase.

Precipitation hardening of a Cu-free Au-Ag-Pd-In dental alloy

International Nuclear Information System (INIS)

Seol, Hyo-Joung; Son, Kuk-Hyeon; Yu, Chin-Ho; Kwon, Yong Hoon; Kim, Hyung-Il

2005-01-01

The hardening mechanism and related microstructural changes of the Cu-free dental casting alloy composed of Au-Ag-Pd-In was examined by means of hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and electron probe microanalysis (EPMA). The Au-Ag-Pd-In alloy showed apparent age-hardenability. In the SEM photograph, three phases were observed in the solution-treated specimen, that is, the Au-Ag based phase with small amounts of In and Pd as matrix, the InPd phase as particle-like structures, and the Pd-rich phase as lamellar precipitates. By aging the specimen, the very fine Pd-rich inter-granular precipitates grew toward the grain interior as lamellar structure, and finally the coarsened Pd-rich precipitates covered a large part of the Au-Ag based matrix. The hardness increase in the early stage of the age-hardening process was assumed to be caused by the diffusion and aggregation of Pd atoms from the Au-Ag based matrix. The hardness decrease in the later stage of age-hardening process was caused by coarsening of the lamellar precipitates composed of the Pd-rich phase

Work Hardening Behavior of 1020 Steel During Cold-Beating Simulation

Science.gov (United States)

CUI, Fengkui; LING, Yuanfei; XUE, Jinxue; LIU, Jia; LIU, Yuhui; LI, Yan

2017-03-01

The present research of cold-beating formation mainly focused on roller design and manufacture, kinematics, constitutive relation, metal flow law, thermo-mechanical coupling, surface micro-topography and microstructure evolution. However, the research on surface quality and performance of workpieces in the process of cold-beating is rare. Cold-beating simulation experiment of 1020 steel is conducted at room temperature and strain rates ranging from 2000 to 4000 s-1 base on the law of plastic forming. According to the experimental data, the model of strain hardening of 1020 steel is established, Scanning Electron Microscopy(SEM) is conducted, the mechanism of the work hardening of 1020 steel is clarified by analyzing microstructure variation of 1020 steel. It is found that the strain rate hardening effect of 1020 steel is stronger than the softening effect induced by increasing temperatures, the process of simulation cold-beating cause the grain shape of 1020 steel significant change and microstructure elongate significantly to form a fibrous tissue parallel to the direction of deformation, the higher strain rate, the more obvious grain refinement and the more hardening effect. Additionally, the change law of the work hardening rate is investigated, the relationship between dislocation density and strain, the relationship between work hardening rate and dislocation density is obtained. Results show that the change trend of the work hardening rate of 1020 steel is divided into two stages, the work hardening rate decreases dramatically in the first stage and slowly decreases in the second stage, finally tending toward zero. Dislocation density increases with increasing strain and strain rate, work hardening rate decreases with increasing dislocation density. The research results provide the basis for solving the problem of improving the surface quality and performance of workpieces under cold-beating formation of 1020 steel.

Electron beam-cured coating

International Nuclear Information System (INIS)

Kishi, Naoyuki

1976-01-01

The method for hardening coatings by the irradiation with electron beams is reviewed. The report is divided into seven parts, namely 1) general description and characteristics of electron beam-cured coating, 2) radiation sources of curing, 3) hardening conditions and reaction behaviour, 4) uses and advantages, 5) latest trends of the industry, 6) practice in the field of construction materials, and 7) economy. The primary characteristics of the electron beam hardening is that graft reaction takes place between base resin and coating to produce strong adhesive coating without any pretreatment. A variety of base resins are developed. High class esters of acrylic acid monomers and methacrylic acid monomers are mainly used as dilutants recently. At present, scanning type accelerators are used, but the practical application of the system producing electron beam of curtain type is expected. The dose rate dependence, the repetitive irradiation and the irradiation atmosphere are briefly described. The filed patent applications on the electron beam hardening were analyzed by the officer of Japan Patent Agency. The production lines for coatings by the electron beam hardening in the world are listed. In the electron beam-cured coating, fifty percent of given energy is consumed effectively for the electron beam hardening, and the solvents discharged from ovens and polluting atmosphere are not used, because the paints of high solid type is used. The running costs of the electron beam process are one sixth of the thermal oven process. (Iwakiri, K.)

The effects of induction hardening on wear properties of AISI 4140 steel in dry sliding conditions

International Nuclear Information System (INIS)

Totik, Y.; Sadeler, R.; Altun, H.; Gavgali, M.

2002-01-01

Wear behaviour of induction hardened AISI 4140 steel was evaluated under dry sliding conditions. Specimens were induction hardened at 1000 Hz for 6, 10, 14, 18, 27 s, respectively, in the inductor which was a three-turn coil with a coupling distance of 2.8 mm. Normalised and induction hardened specimens were fully characterised before and after the wear testing using hardness, profilometer, scanning electron microscopy and X-ray diffraction. The wear tests using a pin-on-disc machine showed that the induction hardening treatments improved the wear behaviour of AISI 4140 steel specimens compared to normalised AISI 4140 steel as a result of residual stresses and hardened surfaces. The wear coefficients in normalised specimens are greater than that in the induction hardened samples. The lowest coefficient of the friction was obtained in specimens induction-hardened at 875 deg. C for 27 s

The effects of induction hardening on wear properties of AISI 4140 steel in dry sliding conditions

Energy Technology Data Exchange (ETDEWEB)

Totik, Y.; Sadeler, R.; Altun, H.; Gavgali, M

2002-02-15

Wear behaviour of induction hardened AISI 4140 steel was evaluated under dry sliding conditions. Specimens were induction hardened at 1000 Hz for 6, 10, 14, 18, 27 s, respectively, in the inductor which was a three-turn coil with a coupling distance of 2.8 mm. Normalised and induction hardened specimens were fully characterised before and after the wear testing using hardness, profilometer, scanning electron microscopy and X-ray diffraction. The wear tests using a pin-on-disc machine showed that the induction hardening treatments improved the wear behaviour of AISI 4140 steel specimens compared to normalised AISI 4140 steel as a result of residual stresses and hardened surfaces. The wear coefficients in normalised specimens are greater than that in the induction hardened samples. The lowest coefficient of the friction was obtained in specimens induction-hardened at 875 deg. C for 27 s.

Electron microscopy study of hardened layers structure at electrospark alloying the VT-18 titanium alloy with aluminium

International Nuclear Information System (INIS)

Pilyankevich, A.N.; Martynenko, A.N.; Verkhoturov, A.D.; Paderno, V.N.

1979-01-01

Presented are the results of metallographic, electron-microscopic, and X-ray structure analysis, of microhardness measurements and of the study of the electrode weight changes at electrospark alloying the VT-18 titanium alloy with aluminium. It is shown, that pulsating thermal and mechanical loadings in the process of electrospark alloying result in the electrode surface electroerosion, a discrete relief is being formed, which changes constantly in the process depending on the alloying time. Though with the process time the cathode weight gain increases, microareas of fracture in the hardened layer appear already at the initial stages of electrospark alloying

Studies on functional polymer films utilizing low energy electron beam

International Nuclear Information System (INIS)

Ando, Masayuki

1992-01-01

Also in adhesives and tackifiers, with the expansion of the fields of application, the required characteristics have become high grade and complex. As one of them, the instantaneous hardening of adhesives can be taken up. In the field of lamination works, the low energy type electron beam accelerators having the linear filament of accelerating voltage below 300 kV were developed in 1970s, and the interest in the development of electron beam-handened adhesives has heightend. The authors have carried out research aiming at heightening the functions of the polymer films obtained by electron beam hardening reaction, and developed the adhesives. In this report, the features of electron beam hardening reaction, the structure and properties of electron beam-hardened polymer films and the molecular design of electron beam-hardened monomer oligomers are described. The feature of electron beam hardening reaction is the cross-linking of high degree as the structure of oligomers is maintained. By controlling the structure at the time of electron beam hardening, the heightening of the functions of electron beam-hardened polymer films is feasible. (K.I.)

Radiation-hardened bulk CMOS technology

International Nuclear Information System (INIS)

Dawes, W.R. Jr.; Habing, D.H.

1979-01-01

The evolutionary development of a radiation-hardened bulk CMOS technology is reviewed. The metal gate hardened CMOS status is summarized, including both radiation and reliability data. The development of a radiation-hardened bulk silicon gate process which was successfully implemented to a commercial microprocessor family and applied to a new, radiation-hardened, LSI standard cell family is also discussed. The cell family is reviewed and preliminary characterization data is presented. Finally, a brief comparison of the various radiation-hardened technologies with regard to performance, reliability, and availability is made

A Novel Radiation Hardened CAM

CERN Document Server

Shojaii, Seyed Ruhollah; The ATLAS collaboration

2018-01-01

This poster describes an innovative Content Addressable Memory cell with radiation hardened (RH-CAM) architecture. The RH-CAM is designed in a commercial 28 nm CMOS technology. The circuit has been simulated in worst-case conditions, and the effects due to single particles are analyzed injecting a fault current into a circuit node. The proposed architecture can perform on-time pattern recognition tasks in harsh environments, such as very front-end electronics in hadron colliders and in space applications.

Strain hardening by dynamic slip band refinement in a high-Mn lightweight steel

International Nuclear Information System (INIS)

Welsch, E.; Ponge, D.; Hafez Haghighat, S.M.; Sandlöbes, S.; Choi, P.; Herbig, M.; Zaefferer, S.; Raabe, D.

2016-01-01

The strain hardening mechanism of a high-Mn lightweight steel (Fe-30.4Mn-8Al-1.2C (wt%)) is investigated by electron channeling contrast imaging (ECCI) and transmission electron microscopy (TEM). The alloy is characterized by a constant high strain hardening rate accompanied by high strength and high ductility (ultimate tensile strength: 900 MPa, elongation to fracture: 68%). Deformation microstructures at different strain levels are studied in order to reveal and quantify the governing structural parameters at micro- and nanometer scales. As the material deforms mainly by planar dislocation slip causing the formation of slip bands, we quantitatively study the evolution of the slip band spacing during straining. The flow stress is calculated from the slip band spacing on the basis of the passing stress. The good agreement between the calculated values and the tensile test data shows dynamic slip band refinement as the main strain hardening mechanism, enabling the excellent mechanical properties. This novel strain hardening mechanism is based on the passing stress acting between co-planar slip bands in contrast to earlier attempts to explain the strain hardening in high-Mn lightweight steels that are based on grain subdivision by microbands. We discuss in detail the formation of the finely distributed slip bands and the gradual reduction of the spacing between them, leading to constantly high strain hardening. TEM investigations of the precipitation state in the as-quenched state show finely dispersed atomically ordered clusters (size < 2 nm). The influence of these zones on planar slip is discussed.

Electronic Resource Management Systems

Directory of Open Access Journals (Sweden)

Mark Ellingsen

2004-10-01

Full Text Available Computer applications which deal with electronic resource management (ERM are quite a recent development. They have grown out of the need to manage the burgeoning number of electronic resources particularly electronic journals. Typically, in the early years of e-journal acquisition, library staff provided an easy means of accessing these journals by providing an alphabetical list on a web page. Some went as far as categorising the e-journals by subject and then grouping the journals either on a single web page or by using multiple pages. It didn't take long before it was recognised that it would be more efficient to dynamically generate the pages from a database rather than to continually edit the pages manually. Of course, once the descriptive metadata for an electronic journal was held within a database the next logical step was to provide administrative forms whereby that metadata could be manipulated. This in turn led to demands for incorporating more information and more functionality into the developing application.

Environmental hardening of a mobile-manipulator system for nuclear environments

International Nuclear Information System (INIS)

Jones, S.L.; Cable, T.; Tulenko, J.S.; Toshkov, S.; Sias, F.R. Jr.

1993-01-01

This research report discusses the radiation hardening of a commercially available mobile robot, the REMOTEC ANDROS. This hardening effort is culminating in the availability of a megarad hardened mobile platform to access areas in nuclear facilities with extremely high levels of radiation (0.1 to 1 Mrad). These radiation levels may be encountered both during routine repair and monitoring activities and accident situations. The project has completed a phase-I U.S. Department of Energy Small Business Innovative Research contract and is now in a phase-II effort with completion scheduled in early 1995. The research involves the evaluation of the material and electrical components of an ANDROS robot to determine the anticipated radiation hardness of the current production version and evaluation of the components that must be replaced or modified to harden the system to higher radiation levels. The work being reported is based on an evaluation of the complete list of all electronic, electrical, and mechanical parts used in the robot and includes initial experimental radiation evaluations performed at the University of Florida

Electronic Resources Management Project Presentation 2012

KAUST Repository

Ramli, Rindra M.

2012-11-05

This presentation describes the electronic resources management project undertaken by the KAUST library. The objectives of this project is to migrate information from MS Sharepoint to Millennium ERM module. One of the advantages of this migration is to consolidate all electronic resources into a single and centralized location. This would allow for better information sharing among library staff.

Hardening of alloys in glow discharge with the use of pulsed electric current

International Nuclear Information System (INIS)

Shipko, M.N.; Pomel'nikova, A.S.; Solunin, A.M.; Solunin, M.A.

2002-01-01

The effect of ex/ternal pulsed electric field on the thickness of a hardened surface layer of a Nd-Fe-B system alloy during chemical heat treatment in a glow discharge is studied. The relationship is established between the hardened layer thickness and the frequency of external electric field which is verified by derived equations for the relation between electron energy and pulsed electric field frequency [ru

Assessment of the effects of atmospheric neutrons on onboard electronic equipment and search for hardening solutions

International Nuclear Information System (INIS)

Renard, S.

2013-01-01

This work deals with the impact of atmospheric neutrons on complex electronic components such as built-in memories or processors. The first part describes the radiation environment, the neutron-matter interaction and the consequences on electronic devices, and presents the commonly used experimental simulations and the testing methods. The potential of laser beam for testing is highlighted. The second chapter presents the development of a testing platform for various types of memories (MRAM and SDRAM). The equipment and the dedicated software are described. A testing platform for processor is also presented. The third chapter is dedicated to the presentation of a 4 Mbit bulk-type SRAM memory and of its testing involving a laser beam equipment. Several results show the presence of error clusters that may endangered the memory as a whole. These error clusters are due to the architecture of the internal addressing scheme of the memory. The simulation of these error clusters must be improved in order to define an optimized strategy of hardening

Study of radiation hardening in reactor pressure vessel steels

International Nuclear Information System (INIS)

Nogiwa, Kimihiro; Nishimura, Akihiko

2008-01-01

In order to investigate the dependence of hardening on copper precipitate diameter and density, in-situ transmission electron microscopy (TEM) observations during tensile tests of dislocation gliding through copper rich-precipitates in thermally aged and neutron irradiated Fe-Cu alloys were performed. The obstacle strength has been estimated from the critical bow-out angle, φ, of dislocations. The obstacle distance on the dislocation line measured from in-situ TEM observations were compared with number density and diameter measured by 3D-AP (three dimensional atom probe) and TEM observation. A comparison is made between hardening estimation based on the critical bowing angles and those obtained from conventional tensile tests. (author)

PRINCIPLES OF CONTENT FORMATION EDUCATIONAL ELECTRONIC RESOURCE

Directory of Open Access Journals (Sweden)

О Ю Заславская

2017-12-01

Full Text Available The article considers modern possibilities of information and communication technologies for the design of electronic educational resources. The conceptual basis of the open educational multimedia system is based on the modular architecture of the electronic educational resource. The content of the electronic training module can be implemented in several versions of the modules: obtaining information, practical exercises, control. The regularities in the teaching process in modern pedagogical theory are considered: general and specific, and the principles for the formation of the content of instruction at different levels are defined, based on the formulated regularities. On the basis of the analysis, the principles of the formation of the electronic educational resource are determined, taking into account the general and didactic patterns of teaching.As principles of the formation of educational material for obtaining information for the electronic educational resource, the article considers: the principle of methodological orientation, the principle of general scientific orientation, the principle of systemic nature, the principle of fundamentalization, the principle of accounting intersubject communications, the principle of minimization. The principles of the formation of the electronic training module of practical studies in the article include: the principle of systematic and dose based consistency, the principle of rational use of study time, the principle of accessibility. The principles of the formation of the module for monitoring the electronic educational resource can be: the principle of the operationalization of goals, the principle of unified identification diagnosis.

Accelerated age hardening by plastic deformation in Al-Cu with minor additions of Si and Ge

International Nuclear Information System (INIS)

Victoria Castro Riglos, M.; Taquire de la Cruz, M.; Tolley, Alfredo

2011-01-01

An extremely fast hardening response with no reduction in peak hardness was obtained in Al-Cu with minor additions of Si and Ge by 8% plastic deformation before artificial aging. The mechanism for the accelerated hardening was determined by detailed characterization with transmission electron microscopy. Plastic deformation was found to enhance the nucleation rate of Si-Ge precipitates, resulting in a higher volume density. Such precipitates catalyzed the formation of θ' precipitates that are responsible for hardening.

Influence of cyclic temperature changes on the microstructure of AISI 4140 after laser surface hardening

International Nuclear Information System (INIS)

Miokovic, T.; Schulze, V.; Voehringer, O.; Loehe, D.

2007-01-01

In recent years laser surface hardening using pulsed laser sources has become an increasingly established technology in engineering industry and has opened up wider possibilities for the application of selective surface hardening. However, the choice of the process parameters is generally based on experience rather than on their empirical influence on the resulting microstructure, and for hardening processes with cyclic temperature changes, almost no correlations between process parameters and hardening results are known. Therefore, some problems regarding the choice of the process parameters and their influence on the resulting microstructure still remain. In particular, there is a lack of data concerning the effect of cyclic temperature changes on hardening. To facilitate process optimization, this paper deals with a detailed characterization of the microstructures created in quenched and tempered AISI 4140 (German grade 42CrMo4) steel following a temperature-dependent laser surface hardening treatment. The structure properties were obtained from microhardness measurements, scanning electron microscopy investigations and X-ray diffraction analysis of retained austenite

Influence of cyclic temperature changes on the microstructure of AISI 4140 after laser surface hardening

Energy Technology Data Exchange (ETDEWEB)

Miokovic, T. [Institute of Materials Science and Engineering I, University of Karlsruhe, 76131 Karlsruhe (Germany); Schulze, V. [Institute of Materials Science and Engineering I, University of Karlsruhe, 76131 Karlsruhe (Germany)]. E-mail: volker.schulze@mach.uni-karlsruhe.de; Voehringer, O. [Institute of Materials Science and Engineering I, University of Karlsruhe, 76131 Karlsruhe (Germany); Loehe, D. [Institute of Materials Science and Engineering I, University of Karlsruhe, 76131 Karlsruhe (Germany)

2007-01-15

In recent years laser surface hardening using pulsed laser sources has become an increasingly established technology in engineering industry and has opened up wider possibilities for the application of selective surface hardening. However, the choice of the process parameters is generally based on experience rather than on their empirical influence on the resulting microstructure, and for hardening processes with cyclic temperature changes, almost no correlations between process parameters and hardening results are known. Therefore, some problems regarding the choice of the process parameters and their influence on the resulting microstructure still remain. In particular, there is a lack of data concerning the effect of cyclic temperature changes on hardening. To facilitate process optimization, this paper deals with a detailed characterization of the microstructures created in quenched and tempered AISI 4140 (German grade 42CrMo4) steel following a temperature-dependent laser surface hardening treatment. The structure properties were obtained from microhardness measurements, scanning electron microscopy investigations and X-ray diffraction analysis of retained austenite.

The effect of initial microstructure on the final properties of press hardened 22MnB5 steels

International Nuclear Information System (INIS)

Järvinen, Henri; Isakov, Matti; Nyyssönen, Tuomo; Järvenpää, Martti; Peura, Pasi

2016-01-01

This paper addresses the relationship between initial microstructure and final properties of press hardened 22MnB5 steels. Four commercial 22MnB5 steels having different initial microstructures were investigated. An experimental press hardening equipment with a flat-die was used to investigate material behavior in the direct press hardening process. Two austenitizing treatments, 450 s and 180 s at 900 °C, were examined. Microstructural characterization with optical and scanning electron microscopes revealed a mixture of martensite and auto-tempered martensite after press hardening. Electron backscatter diffraction data of the transformed martensite was used to reconstruct grain boundary maps of parent austenite. Grain sizes of parent austenite (mean linear intercept) were measured for each material. In addition to microstructural evaluation, quasistatic and high strain rate tensile tests at strain rates of 5×10 −4 s −1 and 400 s −1 , respectively, were performed for press hardened samples. The results show that strength and uniform elongation depend on the initial microstructure of the 22MnB5 steel, when parameters typical to the direct press hardening process are used. Parent austenite grain size was shown to influence the morphology of the transformed martensite, which in turn affects the strength and uniform elongation after press hardening. The tensile properties of the press hardened materials are almost strain rate independent in the studied strain rate range. The obtained results can be used to optimize the properties of 22MnB5 steels in the direct press hardening process. In addition, the here revealed connection between the parent austenite grain size and final steel properties should be taken into account in the development of new press hardening steel grades for automotive industry.

The effect of initial microstructure on the final properties of press hardened 22MnB5 steels

Energy Technology Data Exchange (ETDEWEB)

Järvinen, Henri, E-mail: henri.jarvinen@tut.fi [Department of Materials Science, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Isakov, Matti; Nyyssönen, Tuomo [Department of Materials Science, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Järvenpää, Martti [SSAB Europe Oy, Harvialantie 420, FI-13300 Hämeenlinna (Finland); Peura, Pasi [Department of Materials Science, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland)

2016-10-31

This paper addresses the relationship between initial microstructure and final properties of press hardened 22MnB5 steels. Four commercial 22MnB5 steels having different initial microstructures were investigated. An experimental press hardening equipment with a flat-die was used to investigate material behavior in the direct press hardening process. Two austenitizing treatments, 450 s and 180 s at 900 °C, were examined. Microstructural characterization with optical and scanning electron microscopes revealed a mixture of martensite and auto-tempered martensite after press hardening. Electron backscatter diffraction data of the transformed martensite was used to reconstruct grain boundary maps of parent austenite. Grain sizes of parent austenite (mean linear intercept) were measured for each material. In addition to microstructural evaluation, quasistatic and high strain rate tensile tests at strain rates of 5×10{sup −4} s{sup −1} and 400 s{sup −1}, respectively, were performed for press hardened samples. The results show that strength and uniform elongation depend on the initial microstructure of the 22MnB5 steel, when parameters typical to the direct press hardening process are used. Parent austenite grain size was shown to influence the morphology of the transformed martensite, which in turn affects the strength and uniform elongation after press hardening. The tensile properties of the press hardened materials are almost strain rate independent in the studied strain rate range. The obtained results can be used to optimize the properties of 22MnB5 steels in the direct press hardening process. In addition, the here revealed connection between the parent austenite grain size and final steel properties should be taken into account in the development of new press hardening steel grades for automotive industry.

Implementing CORAL: An Electronic Resource Management System

Science.gov (United States)

Whitfield, Sharon

2011-01-01

A 2010 electronic resource management survey conducted by Maria Collins of North Carolina State University and Jill E. Grogg of University of Alabama Libraries found that the top six electronic resources management priorities included workflow management, communications management, license management, statistics management, administrative…

A non-linear kinematic hardening function

International Nuclear Information System (INIS)

Ottosen, N.S.

1977-05-01

Based on the classical theory of plasticity, and accepting the von Mises criterion as the initial yield criterion, a non-linear kinematic hardening function applicable both to Melan-Prager's and to Ziegler's hardening rule is proposed. This non-linear hardening function is determined by means of the uniaxial stress-strain curve, and any such curve is applicable. The proposed hardening function considers the problem of general reversed loading, and a smooth change in the behaviour from one plastic state to another nearlying plastic state is obtained. A review of both the kinematic hardening theory and the corresponding non-linear hardening assumptions is given, and it is shown that material behaviour is identical whether Melan-Prager's or Ziegler's hardening rule is applied, provided that the von Mises yield criterion is adopted. (author)

Laser transformation hardening effect on hardening zone features and surface hardness of tool steel AISI D2

Directory of Open Access Journals (Sweden)

D. Lesyk

2017-06-01

Full Text Available The relationship of technological input regimes of the laser transformation hardening on change the hardening depth, hardening width, and hardening angle, as well as surface hardness of the tool steel AISI D2 using multifactor experiment with elements of the analysis of variance and regression equations was determined. The laser transformation hardening process implemented by controlling the heating temperature using Nd:YAG fiber laser with scanner, pyrometer and proportional-integral-differential controller. The linear and quadratic regression models are developed, as well as response surface to determine the effect of the heating temperature and feed rate of the treated surface on the energy density of the laser beam, hardening depths, hardening width, hardening angle, and surface hardness are designed. The main effect on the energy density of the laser beam has a velocity laser treatment, on the other hand, the main effect on the geometrical parameters of the laser hardened zone and surface hardness has temperature heating are shown. The optimum magnitudes of the heating temperature (1270 °C and feed rate of the treated surface (90 mm/min for laser transformation hardening of the tool steel AISI D2 using fiber laser with scanner were defined.

Superheat effect on bainite steel hardenability

International Nuclear Information System (INIS)

Kubachek, V.V.; Sklyuev, P.V.

1978-01-01

The bainite hardenability of 34KhN1M and 35 KhN1M2Ph steels has been investigated by the end-face hardening technique. It is established that, as the temperature of austenitization rises from 900 to 1280 deg C, the temperature of bainite transformation increases and bainite hardenability of the steels falls off. A repeated slow heating to 900 deg C of previously overheated 34KhN1M steel breaks up grain, lowers the temperature of the bainite transformation and raises the hardenability to values obtained with ordinary hardening from 900 deg C. A similar heating of previously overheated 35KhN1M2Ph steel is accompanied by restoration of initial coarse grains and maintenance of both the elevated bainite transformation temperature and to lower hardenability corresponding to hardening from the temperature of previous overheating

Managing electronic resources a LITA guide

CERN Document Server

Weir, Ryan O

2012-01-01

Informative, useful, current, Managing Electronic Resources: A LITA Guide shows how to successfully manage time, resources, and relationships with vendors and staff to ensure personal, professional, and institutional success.

Strain hardening rate sensitivity and strain rate sensitivity in TWIP steels

Energy Technology Data Exchange (ETDEWEB)

Bintu, Alexandra [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Vincze, Gabriela, E-mail: gvincze@ua.pt [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Picu, Catalin R. [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Lopes, Augusto B. [CICECO, Department of Materials and Ceramic Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Grácio, Jose J. [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Barlat, Frederic [Materials Mechanics Laboratory, Graduate Institute of Ferrous Technology, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

2015-04-01

TWIP steels are materials with very high strength and exceptional strain hardening capability, parameters leading to large energy absorption before failure. However, TWIP steels also exhibit reduced (often negative) strain rate sensitivity (SRS) which limits the post-necking deformation. In this study we demonstrate for an austenitic TWIP steel with 18% Mn a strong dependence of the twinning rate on the strain rate, which results in negative strain hardening rate sensitivity (SHRS). The instantaneous component of SHRS is large and negative, while its transient is close to zero. The SRS is observed to decrease with strain, becoming negative for larger strains. Direct observations of the strain rate dependence of the twinning rate are made using electron microscopy and electron backscatter diffraction, which substantiate the proposed mechanism for the observed negative SHRS.

Strain hardening rate sensitivity and strain rate sensitivity in TWIP steels

International Nuclear Information System (INIS)

Bintu, Alexandra; Vincze, Gabriela; Picu, Catalin R.; Lopes, Augusto B.; Grácio, Jose J.; Barlat, Frederic

2015-01-01

TWIP steels are materials with very high strength and exceptional strain hardening capability, parameters leading to large energy absorption before failure. However, TWIP steels also exhibit reduced (often negative) strain rate sensitivity (SRS) which limits the post-necking deformation. In this study we demonstrate for an austenitic TWIP steel with 18% Mn a strong dependence of the twinning rate on the strain rate, which results in negative strain hardening rate sensitivity (SHRS). The instantaneous component of SHRS is large and negative, while its transient is close to zero. The SRS is observed to decrease with strain, becoming negative for larger strains. Direct observations of the strain rate dependence of the twinning rate are made using electron microscopy and electron backscatter diffraction, which substantiate the proposed mechanism for the observed negative SHRS

Mechanism of Secondary Hardening in Rapid Tempering of Dual-Phase Steel

Science.gov (United States)

Saha, Dulal Chandra; Nayak, Sashank S.; Biro, Elliot; Gerlich, Adrian P.; Zhou, Y.

2014-12-01

Dual-phase steel with ferrite-martensite-bainite microstructure exhibited secondary hardening in the subcritical heat affected zone during fiber laser welding. Rapid isothermal tempering conducted in a Gleeble simulator also indicated occurrence of secondary hardening at 773 K (500 °C), as confirmed by plotting the tempered hardness against the Holloman-Jaffe parameter. Isothermally tempered specimens were characterized by analytic transmission electron microscopy and high-angle annular dark-field imaging. The cementite (Fe3C) and TiC located in the bainite phase of DP steel decomposed upon rapid tempering to form needle-shaped Mo2C (aspect ratio ranging from 10 to 25) and plate-shaped M4C3 carbides giving rise to secondary hardening. Precipitation of these thermodynamically stable and coherent carbides promoted the hardening phenomenon. However, complex carbides were only seen in the tempered bainite and were not detected in the tempered martensite. The martensite phase decomposed into ferrite and spherical Fe3C, and interlath-retained austenite decomposed into ferrite and elongated carbide.

Hardening by means of ionising radiation

International Nuclear Information System (INIS)

Spoor, H.; Demmler, K.

1979-01-01

The polymerisable ethylic unsaturated mixture can be hardened by means of electron irradiation and used as a corrosion preventive layer. The mixture mainly consists of at least a di-olefinic unsaturated polyester, partial esters of polycarbonic acids, in particular the monoester of dicarbonic acids, with a copolymerizable C-C double bond, and mono-olefine unsaturated hydrocarbons, for example vinyl aromatics. The coatings exhibit good adhesion to the substrate, in particular to metal, and good flexibility. (DG) [de

Low-cycle fatigue behaviors of pre-hardening Hadfield steel

Energy Technology Data Exchange (ETDEWEB)

Chen, Chen [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Lv, Bo [College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); Wang, Fei [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang, Fucheng, E-mail: zfc@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004 (China)

2017-05-17

Low-cycle fatigue behaviors of the pre-hardening (PH) and the water-quenching (WQ) Hadfield steel were studied using optical microscopy, transmission electron microscopy, and electron backscatter diffraction technique. The effect of the PH treatment on low-cycle fatigue behavior of the Hadfield steel was analyzed through comparing the cyclic hardening/softening behaviors and the changing regulations of stress amplitude, internal stress, and effective stress at different total strain amplitudes. Results showed obvious differences in fatigue behaviors between the PH (with a cold rolling deformation degree of 40%) and the WQ Hadfield steels. Transient hardening followed by cyclic stability behavior occurred in the PH Hadfield steel under cyclic loading, whereas cyclic softening behavior was barely observed. The fatigue life of the PH Hadfield steel was higher than that of the WQ Hadfield steel at relatively low strain amplitudes, while a contrary result was obtained at relatively high strain amplitudes. At low strain amplitudes, the deformation twins induced in the PH Hadfield steel could enhance the multiplication and slip process of dislocations, which actually improved the deformation uniformity. The long-range motion of dislocations was intensified at high strain amplitudes. However, the dislocation motion was also blocked by twin boundaries. As a result, the interactions between dislocations and deformation twins enhanced, finally causing severe dislocation accumulation. These two effects of deformation twins on dislocation motion eventually resulted in different low-cycle fatigue behaviors of the PH Hadfield steel.

An Innovative Radiation Hardened CAM Architecture

CERN Document Server

Shojaii, Seyed Ruhollah; The ATLAS collaboration

2018-01-01

This article describes an innovative Content Addressable Memory (CAM) cell with radiation hardened (RH) architecture. The RH-CAM is designed in a commercial 28 nm CMOS technology. The circuit has been simulated in worst-case conditions, and the effects due to single particles have been analyzed by injecting a current pulse into a circuit node. The proposed architecture is suitable for on-time pattern recognition tasks in harsh environments, such as front-end electronics in hadron colliders and in space applications.

Radiation effects in semiconductors: technologies for hardened integrated circuits

International Nuclear Information System (INIS)

Charlot, J.M.

1983-09-01

Various technologies are used to manufacture integrated circuits for electronic systems. But for specific applications, including those with radiation environment, it is necessary to choose an appropriate technologie or to improve a specific one in order to reach a definite hardening level. The aim of this paper is to present the main effects induced by radiation (neutrons and gamma rays) into the basic semiconductor devices, to explain some physical degradation mechanisms and to propose solutions for hardened integrated circuit fabrication. The analysis involves essentially the monolithic structure of the integrated circuits and the isolation technology of active elements. In conclusion, the advantages of EPIC and SOS technologies are described and the potentialities of new technologies (GaAs and SOI) are presented

Radiation effects in semiconductors: technologies for hardened integrated circuits

International Nuclear Information System (INIS)

Charlot, J.M.

1984-01-01

Various technologies are used to manufacture integrated circuits for electronic systems. But for specific applications, including those with radiation environment, it is necessary to choose an appropriate technology or to improve a specific one in order to reach a definite hardening level. The aim of this paper is to present the main effects induced by radiation (neutrons and gamma rays) into the basic semiconductor devices, to explain some physical degradation mechanisms and to propose solutions for hardened integrated circuit fabrication. The analysis involves essentially the monolithic structure of the integrated circuits and the isolation technology of active elements. In conclusion, the advantages of EPIC and SOS technologies are described and the potentialities of new technologies (GaAs and SOI) are presented. (author)

Effect of Annealing on Microstructures and Hardening of Helium-Hydrogen-Implanted Sequentially Vanadium Alloys

Science.gov (United States)

Jiang, Shaoning; Wang, Zhiming

2018-03-01

The effect of post-irradiation annealing on the microstructures and mechanical properties of V-4Cr-4Ti alloys was studied. Helium-hydrogen-irradiated sequentially V-4Cr-4Ti alloys at room temperature (RT) were undergone post-irradiation annealing at 450 °C over periods of up to 30 h. These samples were carried out by high-resolution transmission electron microscopy (HRTEM) observation and nanoindentation test. With the holding time, large amounts of point defects produced during irradiation at RT accumulated into large dislocation loops and then dislocation nets which promoted the irradiation hardening. Meanwhile, bubbles appeared. As annealing time extended, these bubbles grew up and merged, and finally broke up. In the process, the size of bubbles increased and the number density decreased. Microstructural changes due to post-irradiation annealing corresponded to the change of hardening. Dislocations and bubbles are co-contributed to irradiation hardening. With the holding time up to 30 h, the recovery of hardening is not obvious. The phenomenon was discussed by dispersed barrier hardening model and Friedel-Kroupa-Hirsch relationship.

Hardening and softening analysis of pure titanium based on the dislocation density during torsion deformation

Energy Technology Data Exchange (ETDEWEB)

Chen, Han; Li, Fuguo, E-mail: fuguolx@nwpu.edu.cn; Li, Jinghui; Ma, Xinkai; Li, Jiang; Wan, Qiong

2016-08-01

The hardening and softening phenomena during torsion deformation are studied based on the Taylor dislocation model for pure titanium. The hardening and softening phenomena are observed through the hardness analysis during micro-indentation test and micro-hardness test. Besides, the variations of indentation size also verify the existence of hardening and softening phenomena during torsion. The variations of geometric necessary dislocations (GNDs) and statistic store dislocations (SSDs) state that the positions of high dislocation density and low dislocation density correspond to the positions of hardening and softening. The results from the microstructure, grain boundaries evolution and twins analysis indicate the twins play an important role in appearance of hardening and softening phenomena. The appearance of hardening and softening phenomena are attributed to the combination of different slip systems and twinning systems combining with the Schmid Factor (SF) analysis and the transmission electron microscope (TEM). The appearance of hardening and softening phenomena can be explained by the Taylor dislocation theory based on TEM analysis. - Highlights: • The phenomena can be characterized by Taylor dislocation model. • The variation of GNDs leads to the phenomena. • The phenomena are proved by micro-hardness, indentation hardness. • The {10-12} twin and {11-24} twin play an important role in the phenomena.

On the hardenability of Nb-modified metastable beta Ti-5553 alloy

Energy Technology Data Exchange (ETDEWEB)

Campo, K.N.; Andrade, D.R.; Opini, V.C.; Mello, M.G.; Lopes, E.S.N.; Caram, R., E-mail: caram@fem.unicamp.br

2016-05-15

Among the commercially available titanium alloys, the metastable β Ti-5553 alloy (Ti–5Al–5V–5Mo–3Cr–0.5Fe wt.%) is an object of great interest because it is employed in aerospace structural applications, primarily in the replacement of steel components. One of the primary advantages of this alloy is its high hardenability, which allows it to retain the β phase at room temperature, even at low cooling rates, thereby allowing the thermoprocessing of thick parts. The aim of this investigation was to evaluate the effect of the replacement of V with Nb on the hardenability of Ti-5553. Based on the molybdenum equivalent criterion, the Nb-modified Ti-5553 alloy was designed to present 12 wt.% of Nb instead of 5 wt.% of V. Samples of both alloys were prepared by melting them in an arc furnace under an inert atmosphere, heat-treated at high temperatures for 12 h and plastic deformed using swage forging. Finally, these samples were solution heat-treated at temperatures above the β-transus followed by cooling at different rates using water quenching, furnace cooling and a modified Jominy end quench test. Characterization was performed by measuring Vickers hardness, X-ray diffraction, and light optical, scanning electron and transmission electron microscopy. The results obtained indicate that metastable β phase can be retained when the cooling rate is higher than 21 °C/s for both alloys. At lower cooling rates, α phase precipitation was observed, but it appeared to be less evident in the Nb-modified Ti-5553, suggesting that the replacement of V with Nb increased the hardenability of the alloy. - Highlights: • Hardenability of Ti alloys are assessed using a modified Jominy end quench test. • Ti-5553 and Nb-modified Ti-5553 are subjected to continuous cooling experiments. • β phase decomposition kinetics is reduced by replacing V with Nb in Ti-5553. • Nb-modified Ti-5553 features improved hardenability. • Replacement of V with Nb causes the �

Age-hardening susceptibility of high-Cr ODS ferritic steels and SUS430 ferritic steel

Energy Technology Data Exchange (ETDEWEB)

Chen, Dongsheng, E-mail: chen.dongsheng85@gmail.com [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Kimura, Akihiko; Han, Wentuo; Je, Hwanil [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

2015-10-15

Highlights: • The role of oxide particles in α/α′ phase decomposition behavior; microstructure of phase decomposition observed by TEM. • The characteristics of ductility loss caused by age-hardening. • Correlation of phase decomposition and age-hardening explained by dispersion strengthened models. • Age-hardening susceptibility of ODS steels and SUS430 steel. - Abstract: The effect of aging on high-Cr ferritic steels was investigated with focusing on the role of oxide particles in α/α′ phase decomposition behavior. 12Cr-oxide dispersion strengthened (ODS) steel, 15Cr-ODS steel and commercial SUS430 steel were isothermally aged at 475 °C for up to 10,000 h. Thermal aging caused a larger hardening in SUS430 than 15Cr-ODS, while 12Cr-ODS showed almost no hardening. A characteristic of the ODS steels is that the hardening was not accompanied by the significant loss of ductility that was observed in SUS430 steel. After aging for 2000 h, SUS430 steel shows a larger ductile–brittle transition temperature (DBTT) shift than 15Cr-ODS steel, which suggests that the age-hardening susceptibility is lower in 15Cr-ODS steel than in conventional SUS430 steel. Thermal aging leaded to a large number of Cr-rich α′ precipitates, which were confirmed by transmission electron microscopy (TEM). Correlation of age-hardening and phase decomposition was interpreted by Orowan type strengthening model. Results indicate that oxide particles cannot only suppress ductility loss, but also may influence α/α′ phase decomposition kinetics.

Gender Analysis Of Electronic Information Resource Use: The Case ...

African Journals Online (AJOL)

Based on the findings the study concluded that access and use of electronic information resources creates a “social digital divide” along gender lines. The study ... Finally, the library needs to change its marketing strategies on the availability of electronic information resources to increase awareness of these resources.

Users satisfaction with electronic information resources and services ...

African Journals Online (AJOL)

This study investigated users satisfaction on the use of electronic information resources and services in MTN Net libraries in ABU & UNIBEN. Two objectives and one null hypotheses were formulated and tested with respect to the users' satisfaction on electronic information resources and services in MTN Net libraries in ...

Formation and evolution of the hardening precipitates in a Mg-Y-Nd alloy

International Nuclear Information System (INIS)

Barucca, G.; Ferragut, R.; Fiori, F.; Lussana, D.; Mengucci, P.; Moia, F.; Riontino, G.

2011-01-01

The formation and evolution of hardening precipitates in a Mg-Y-Nd (WE43) alloy during artificial ageing at 150 and 210 deg. C is followed by small angle X-ray scattering (SAXS) measurements, Vickers microhardness tests and transmission electron microscopy (TEM) observations. A quantitative description of the alloy studied during the early and advanced stages of the precipitation sequence is presented. In situ SAXS evolution at 210 deg. C of the size, volume fraction and number density of the subnanometer and nanometer particles that evolve in the β'' phase was obtained. TEM and microhardness results indicate that the hardening mechanism is based on β'' transformation of pre-precipitates and their growth at 150 deg. C, while at 210 deg. C hardening is mainly associated with β'' → β' transformation.

Working hardening modelization in zirconium alloys

International Nuclear Information System (INIS)

Sanchez, P.; Pochettino, Alberto A.

1999-01-01

Working hardening effects on mechanical properties and crystallographic textures formation in Zr-based alloys are studied. The hardening mechanisms for different grain deformations and topological conditions of simple crystal yield are considered. Results obtained show that the differences in the cold rolling textures (L and T textures) can be related with hardening microstructural parameters. (author)

Practical aspects of systems hardening

International Nuclear Information System (INIS)

Shepherd, W.J.

1989-01-01

Applications of hardening technology in a practical system require a balance between the factors governing affordability, producibility, and survivability of the finished design. Without careful consideration of the top-level system operating constraints, a design engineer may find himself with a survivable but overweight, unproductive, expensive design. This paper explores some lessons learned in applying hardening techniques to several laser communications programs and is intended as an introductory guide to novice designers faced with the task of hardening a space system

Principles and techniques of radiation hardening. Volume 3. Electromagnetic pulse (EMP) and system generated EMP

International Nuclear Information System (INIS)

Rudie, N.J.

1976-01-01

The three-volume book is intended to serve as a review of the effects of thermonuclear explosion induced radiation (x-rays, gamma rays, and beta particles) and the resulting electromagnetic pulse (EMP). Volume 3 deals with the following topics: selected fundamentals of electromagnetic theory; EMP induced currents on antennas and cables; the EMP response of electronics; EMP hardening; EMP testing; injection currents; internal electromagnetic pulse (IEMP); replacement currents; and system generated electromagnetic pulse (SGEMP) hardening

Microstructural evolution and the variation of tensile behavior after aging heat treatment of precipitation hardened martensitic steel

International Nuclear Information System (INIS)

Shin, Jong-Ho; Jeong, JaeSuk; Lee, Jong-Wook

2015-01-01

The effects of aging temperature on the microstructural evolution and the tensile behavior of precipitation hardened martensitic steel were investigated. Microscopic analysis using transmission electron microscope (TEM) was combined with the microstructural analysis using the synchrotron X-ray diffraction (XRD) to characterize the microstructural evolution with aging temperature. Peak hardness was obtained by precipitation of the Ni 3 Al ordered phase. After aging at temperature range from 420 to 590 °C, spherical Ni 3 Al precipitates and ellipsoidal M 23 C 6 carbides were observed within laths and at lath boundaries, respectively. Strain hardening behavior was analyzed with Ludwik equation. It is observed that the plastic strain regimes can be divided into two different stages by a rapid increase in strain hardening followed by a comparatively lower increase. At the first strain hardening stage, the aged specimen exhibited higher strain hardening exponent than the as-quenched specimen, and the exponent in the aged specimen was not changed considerably with increasing aging temperature. It is revealed that the strain hardening exponents at the first and the second stages were associated with the Ni 3 Al precipitates and the domain size representing the coherent scattering area, respectively. - Highlights: • All of aged specimen exhibited higher strain hardening exponent than the as-quenched specimen at the first stage. • The value of strain hardening exponent in the aged specimen was nearly constant with aging temperature. • Ni 3 Al precipitation dominantly influenced to the increase of strain hardening exponent at the first strain hardening stage. • Domain size was associated with strain hardening exponent at the second strain hardening stage

Microstructural evolution and the variation of tensile behavior after aging heat treatment of precipitation hardened martensitic steel

Energy Technology Data Exchange (ETDEWEB)

Shin, Jong-Ho, E-mail: jongho.shin@doosan.com [Casting and Forging Technology Development Team, Doosan Heavy Industries and Construction, 22 Doosanvolvo-ro, Changwon 642-792 (Korea, Republic of); Jeong, JaeSuk [Materials and Manufacturing Development Team, Doosan Heavy Industries and Construction, 22 Doosanvolvo-ro, Changwon 642-792 (Korea, Republic of); Lee, Jong-Wook [Casting and Forging Technology Development Team, Doosan Heavy Industries and Construction, 22 Doosanvolvo-ro, Changwon 642-792 (Korea, Republic of)

2015-01-15

The effects of aging temperature on the microstructural evolution and the tensile behavior of precipitation hardened martensitic steel were investigated. Microscopic analysis using transmission electron microscope (TEM) was combined with the microstructural analysis using the synchrotron X-ray diffraction (XRD) to characterize the microstructural evolution with aging temperature. Peak hardness was obtained by precipitation of the Ni{sub 3}Al ordered phase. After aging at temperature range from 420 to 590 °C, spherical Ni{sub 3}Al precipitates and ellipsoidal M{sub 23}C{sub 6} carbides were observed within laths and at lath boundaries, respectively. Strain hardening behavior was analyzed with Ludwik equation. It is observed that the plastic strain regimes can be divided into two different stages by a rapid increase in strain hardening followed by a comparatively lower increase. At the first strain hardening stage, the aged specimen exhibited higher strain hardening exponent than the as-quenched specimen, and the exponent in the aged specimen was not changed considerably with increasing aging temperature. It is revealed that the strain hardening exponents at the first and the second stages were associated with the Ni{sub 3}Al precipitates and the domain size representing the coherent scattering area, respectively. - Highlights: • All of aged specimen exhibited higher strain hardening exponent than the as-quenched specimen at the first stage. • The value of strain hardening exponent in the aged specimen was nearly constant with aging temperature. • Ni{sub 3}Al precipitation dominantly influenced to the increase of strain hardening exponent at the first strain hardening stage. • Domain size was associated with strain hardening exponent at the second strain hardening stage.

Effect of ferrite-martensite interface morphology on bake hardening response of DP590 steel

International Nuclear Information System (INIS)

Chakraborty, Arnab; Adhikary, Manashi; Venugopalan, T.; Singh, Virender; Nanda, Tarun; Kumar, B. Ravi

2016-01-01

The effect of martensite spatial distribution and its interface morphology on the bake hardening characteristics of a dual phase steel was investigated. In one case, typical industrial continuous annealing line parameters were employed to anneal a 67% cold rolled steel to obtain a dual phase microstructure. In the other case, a modified annealing process with changed initial heating rates and peak annealing temperature was employed. The processed specimens were further tensile pre-strained within 1–5% strain range followed by a bake hardening treatment at 170 °C for 20 min. It was observed that industrial continuous annealing line processed specimen showed a peak of about 70 MPa in bake-hardening index at 2% pre-strain level. At higher pre-strain values a gradual drop in bake-hardening index was observed. On the contrary, modified annealing process showed near uniform bake-hardening response at all pre-strain levels and a decrease could be noted only above 4% pre-strain. The evolving microstructure at each stage of annealing process and after bake-hardening treatment was studied using field emission scanning electron microscope. The microstructure analysis distinctly revealed differences in martensite spatial distribution and interface morphologies between each annealing processes employed. The modified process showed predominant formation of martensite within the ferrite grains with serrated lath martensite interfaces. This nature of the martensite was considered responsible for the observed improvement in the bake-hardening response. Furthermore, along with improved bake-hardening response negligible loss in tensile ductility was also noted. This behaviour was correlated with delayed micro-crack initiation at martensite interface due to serrated nature.

Solution hardening and strain hardening at elevated temperatures

International Nuclear Information System (INIS)

Kocks, U.F.

1982-10-01

Solutes can significantly increase the rate of strain hardening; as a consequence, the saturation stress, at which strain hardening tends to cease for a given temperature and strain rate, is increased more than the yield stress: this is the major effect of solutes on strength at elevated temperatures, especially in the regime where dynamic strain-aging occurs. It is shown that local solute mobility can affect both the rate of dynamic recovery and the dislocation/dislocation interaction strength. The latter effect leads to multiplicative solution strengthening. It is explained by a new model based on repeated dislocation unlocking, in a high-temperature limit, which also rationalizes the stress dependence of static and dynamic strain-aging, and may help explain the plateau of the yield stress at elevated temperatures. 15 figures

Formation and evolution of the hardening precipitates in a Mg-Y-Nd alloy

Energy Technology Data Exchange (ETDEWEB)

Barucca, G. [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Universita Politecnica delle Marche, Via Brecce Bianche, I-60131 Ancona (Italy); Ferragut, R. [Dipartimento di Fisica, LNESS and CNISM, Politecnico di Milano, Via Anzani 42, I-22100 Como (Italy); Fiori, F. [Dipartimento SAIFET, Sezione di Scienze Fisiche, Universita Politecnica delle Marche, Via Brecce Bianche, I-60131 Ancona (Italy); Lussana, D. [Dipartimento di Chimica IFM and NIS Centre, Universita di Torino, Via P. Giuria 9, I-10125 Torino (Italy); Mengucci, P., E-mail: p.mengucci@univpm.it [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Universita Politecnica delle Marche, Via Brecce Bianche, I-60131 Ancona (Italy); Moia, F. [Dipartimento di Fisica, LNESS and CNISM, Politecnico di Milano, Via Anzani 42, I-22100 Como (Italy); Riontino, G. [Dipartimento di Chimica IFM and NIS Centre, Universita di Torino, Via P. Giuria 9, I-10125 Torino (Italy)

2011-06-15

The formation and evolution of hardening precipitates in a Mg-Y-Nd (WE43) alloy during artificial ageing at 150 and 210 deg. C is followed by small angle X-ray scattering (SAXS) measurements, Vickers microhardness tests and transmission electron microscopy (TEM) observations. A quantitative description of the alloy studied during the early and advanced stages of the precipitation sequence is presented. In situ SAXS evolution at 210 deg. C of the size, volume fraction and number density of the subnanometer and nanometer particles that evolve in the {beta}'' phase was obtained. TEM and microhardness results indicate that the hardening mechanism is based on {beta}'' transformation of pre-precipitates and their growth at 150 deg. C, while at 210 deg. C hardening is mainly associated with {beta}'' {yields} {beta}' transformation.

Organizational matters of competition in electronic educational resources

Directory of Open Access Journals (Sweden)

Ирина Карловна Войтович

2015-12-01

Full Text Available The article examines the experience of the Udmurt State University in conducting competitions of educational publications and electronic resources. The purpose of such competitions is to provide methodological support to educational process. The main focus is on competition of electronic educational resources. The technology of such contests is discussed through detailed analysis of the main stages of the contest. It is noted that the main task of the preparatory stage of the competition is related to the development of regulations on competition and the definition of criteria for selection of the submitted works. The paper also proposes a system of evaluation criteria of electronic educational resources developed by members of the contest organizing committee and jury members. The article emphasizes the importance of not only the preparatory stages of the competition, but also measures for its completion, aimed at training teachers create quality e-learning resources.

Hardening Azure applications

CERN Document Server

Gaurav, Suraj

2015-01-01

Learn what it takes to build large scale, mission critical applications -hardened applications- on the Azure cloud platform. This 208 page book covers the techniques and engineering principles that every architect and developer needs to know to harden their Azure/.NET applications to ensure maximum reliability and high availability when deployed at scale. While the techniques are implemented in .NET and optimized for Azure, the principles here will also be valuable for users of other cloud-based development platforms. Applications come in a variety of forms, from simple apps that can be bui

Non-destructive screening method for radiation hardened performance of large scale integration

International Nuclear Information System (INIS)

Zhou Dong; Xi Shanbin; Guo Qi; Ren Diyuan; Li Yudong; Sun Jing; Wen Lin

2013-01-01

The space radiation environment could induce radiation damage on the electronic devices. As the performance of commercial devices is generally superior to that of radiation hardened devices, it is necessary to screen out the devices with good radiation hardened performance from the commercial devices and applying these devices to space systems could improve the reliability of the systems. Combining the mathematical regression analysis with the different physical stressing experiments, we investigated the non-destructive screening method for radiation hardened performance of the integrated circuit. The relationship between the change of typical parameters and the radiation performance of the circuit was discussed. The irradiation-sensitive parameters were confirmed. The pluralistic linear regression equation toward the prediction of the radiation performance was established. Finally, the regression equations under stress conditions were verified by practical irradiation. The results show that the reliability and accuracy of the non-destructive screening method can be elevated by combining the mathematical regression analysis with the practical stressing experiment. (authors)

CHALLENGES OF ELECTRONIC INFORMATION RESOURCES IN ...

African Journals Online (AJOL)

This paper discusses the role of policy for proper and efficient library services in the electronic era. It points out some of the possible dangers of embarking in electronic resources without a proper focus at hand. Thus, it calls for today's librarians and policy makers to brainstorm and come up with working policies suitable to ...

Effect of aging hardening on in situ synthesis magnesium matrix composites

International Nuclear Information System (INIS)

Zhang Xiuqing; Liao Lihua; Ma Naiheng; Wang Haowei

2006-01-01

Magnesium matrix composites reinforced with TiC particulates was synthesized using in situ synthesis technique. The result of XRD revealed the presence of TiC in precursor blocks and TiC/AZ91 composites. Effect of aging hardening on the composites was described using Brinell hardness measurements and scanning electron microscopy (SEM). The results revealed that the aging hardening peak of TiC/AZ91 composite appeared earlier comparatively with that of AZ91 magnesium alloy. And the appearance of aging hardening peak was earlier under the higher aging temperature such as 200 deg. C. The precipitating behavior of Mg 17 Al 12 phase in AZ91 alloy and TiC/AZ91 composites was described. Little discontinuous was discovered in the composites, and the amount of continuous precipitate in the composite matrix is smaller comparatively to that of AZ91 alloy. These results were analyzed with the fine grain size, much more interface between TiC and magnesium and high-density dislocation in magnesium matrix, which was contributed to the addition of TiC particulates

Improving precipitation hardening behavior of Mg−Zn based alloys with Ce−Ca microalloying additions

Energy Technology Data Exchange (ETDEWEB)

Langelier, B., E-mail: langelb@mcmaster.ca [Mechanical & Mechatronics Engineering, The University of Waterloo, N2L 3G1 (Canada); Canadian Centre for Electron Microscopy, McMaster University, L8S 4L8 (Canada); Korinek, A. [Canadian Centre for Electron Microscopy, McMaster University, L8S 4L8 (Canada); Donnadieu, P. [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France); CNRS, SIMAP, F-38000 Grenoble (France); Esmaeili, S. [Mechanical & Mechatronics Engineering, The University of Waterloo, N2L 3G1 (Canada)

2016-10-15

The precipitation hardening behavior of newly developed Mg−Zn−Ca−Ce alloys, with modified texture and improved ductility, is studied to delineate the microstructural characteristics that lead to effective hardening upon ageing treatments. Advanced electron microscopy and atom probe techniques are used to analyze the structural characteristics in relevance to the hardening potential. It has been found that the formation of a new basal precipitate phase, which evolves from a single atomic layer GP zone, and is finely distributed in both under-aged and peak-aged microstructures, has a significant impact in the improvement of the hardening response compared with the base Mg−Zn alloys. It has also been found that the β′{sub 1} rod precipitates, commonly formed during ageing treatments of Mg−Zn alloys, have their size and distribution significantly refined in the Ca−Ce containing alloys. The role of alloy chemistry in the formation of the fine basal plate GP zones and the refinement in β′{sub 1} precipitation and their relationships to the hardening behavior are discussed. It is proposed that Ca microalloying governs the formation of the GP zones and the enhancement of hardening, particularly in the under-aged conditions, but that this is aided by a beneficial effect from Ce. - Highlights: • Ce−Ca microalloying additions improve hardening in Mg−Zn, over Ce or Ca alone. • Improved hardening is due to refined β′{sub 1} rods, and fine basal plate precipitates. • Atom probe tomography identifies Ca in both β′{sub 1} and the fine basal plates. • The fine basal plates originate as ordered monolayer GP zones with 1:1 Zn:Ca (at.%). • With ageing GP zones become more Zn-rich and transform to the fine basal plates.

Influence of Microstructure and Process Conditions on Simultaneous Low-Temperature Surface Hardening and Bulk Precipitation Hardening of Nanoflex®

DEFF Research Database (Denmark)

Bottoli, Federico; Winther, Grethe; Christiansen, Thomas L.

2015-01-01

Precipitation hardening martensitic stainless steel Nanoflex was low-temperature nitrided or nitrocarburized. In these treatments, simultaneous hardening of the bulk, by precipitation hardening, and the surface by dissolving nitrogen/carbon can be obtained because the treatment temperatures...... and times for these essentially different hardening mechanisms are compatible. The effect of the processing history of the steel on the nitrided/nitrocarburized case was investigated by varying the amounts of austenite and martensite through variation of the degree of plastic deformation by tensile strain...... consisting of martensite results in the deepest nitrided case, while a shallow case develops on a microstructure consisting of austenite. For an initial microstructure consisting of both martensite and austenite a non-uniform case depth is achieved. Simultaneous bulk and surface hardening is only possible...

Devising Strain Hardening Models Using Kocks–Mecking Plots—A Comparison of Model Development for Titanium Aluminides and Case Hardening Steel

Directory of Open Access Journals (Sweden)

Markus Bambach

2016-08-01

Full Text Available The present study focuses on the development of strain hardening models taking into account the peculiarities of titanium aluminides. In comparison to steels, whose behavior has been studied extensively in the past, titanium aluminides possess a much larger initial work hardening rate, a sharp peak stress and pronounced softening. The work hardening behavior of a TNB-V4 (Ti–44.5Al–6.25Nb–0.8Mo–0.1B alloy is studied using isothermal hot compression tests conducted on a Gleeble 3500 simulator, and compared to the typical case hardening steel 25MoCrS4. The behavior is analyzed with the help of the Kocks-Mecking plots. In contrast to steel the TNB-V4 alloy shows a non-linear course of θ (i.e., no stage-III hardening initially and exhibits neither a plateau (stage IV hardening nor an inflection point at all deformation conditions. The present paper describes the development and application of a methodology for the design of strain hardening models for the TNB-V4 alloy and the 25CrMoS4 steel by taking the course of the Kocks-Mecking plots into account. Both models use different approaches for the hardening and softening mechanisms and accurately predict the flow stress over a wide range of deformation conditions. The methodology may hence assist in further developments of more sophisticated physically-based strain hardening models for TiAl-alloys.

Hydrogen embrittlement susceptibility of laser-hardened 4140 steel

Energy Technology Data Exchange (ETDEWEB)

Tsay, L.W.; Lin, Z.W. [Nat. Taiwan Ocean Univ., Keelung (Taiwan). Inst. of Mater. Eng.; Shiue, R.K. [Institute of Materials Sciences and Engineering, National Dong Hwa University, Hualien, Taiwan (Taiwan); Chen, C. [Institute of Materials Sciences and Engineering, National Taiwan University, Taipei, Taiwan (Taiwan)

2000-10-15

Slow strain rate tensile (SSRT) tests were performed to investigate the susceptibility to hydrogen embrittlement of laser-hardened AISI 4140 specimens in air, gaseous hydrogen and saturated H{sub 2}S solution. Experimental results indicated that round bar specimens with two parallel hardened bands on opposite sides along the loading axis (i.e. the PH specimens), exhibited a huge reduction in tensile ductility for all test environments. While circular-hardened (CH) specimens with 1 mm hardened depth and 6 mm wide within the gauge length were resistant to gaseous hydrogen embrittlement. However, fully hardened CH specimens became susceptible to hydrogen embrittlement for testing in air at a lower strain rate. The strength of CH specimens increased with decreasing the depth of hardened zones in a saturated H{sub 2}S solution. The premature failure of hardened zones in a susceptible environment caused the formation of brittle intergranular fracture and the decrease in tensile ductility. (orig.)

Strain hardening of cold-rolled lean-alloyed metastable ferritic-austenitic stainless steels

Energy Technology Data Exchange (ETDEWEB)

Papula, Suvi [Aalto University School of Engineering, Department of Mechanical Engineering, P.O. Box 14200, FI-00076 Aalto (Finland); Anttila, Severi [Centre for Advanced Steels Research, University of Oulu, P.O. Box 4200, 90014 Oulu (Finland); Talonen, Juho [Outokumpu Oyj, P.O. Box 245, FI-00181 Helsinki (Finland); Sarikka, Teemu; Virkkunen, Iikka; Hänninen, Hannu [Aalto University School of Engineering, Department of Mechanical Engineering, P.O. Box 14200, FI-00076 Aalto (Finland)

2016-11-20

Mechanical properties and strain hardening of two pilot-scale lean-alloyed ferritic-austenitic stainless steels having metastable austenite phase, present at 0.50 and 0.30 volume fractions, have been studied by means of tensile testing and nanoindentation. These ferritic-austenitic stainless steels have high strain-hardening capacity, due to the metastable austenite phase, which leads to an improved uniform elongation and higher tensile strength in comparison with most commercial lean duplex stainless steels. According to the results, even as low as 0.30 volume fraction of austenite seems efficient for achieving nearly 40% elongation. The austenite phase is initially the harder phase, and exhibits more strain hardening than the ferrite phase. The rate of strain hardening and the evolution of the martensite phase were found to depend on the loading direction: both are higher when strained in the rolling direction as compared to the transverse direction. Based on the mechanical testing, characterization of the microstructure by optical/electron microscopy, magnetic balance measurements and EBSD texture analysis, this anisotropy in mechanical properties of the cold-rolled metastable ferritic-austenitic stainless steels can be explained by the elongated dual-phase microstructure, fiber reinforcement effect of the harder austenite phase and the presence and interplay of rolling textures in the two phases.

Use of Electronic Resources in a Private University in Nigeria ...

African Journals Online (AJOL)

The study examined awareness and constraints in the use of electronic resources by lecturers and students of Ajayi Crowther University, Oyo, Nigeria. It aimed at justifying the resources expended in the provision of electronic resources in terms of awareness, patronage and factors that may be affecting awareness and use ...

Electronic Resources Management System: Recommendation Report 2017

KAUST Repository

Ramli, Rindra M.

2017-05-01

This recommendation report provides an overview of the selection process for the new Electronic Resources Management System. The library has decided to move away from Innovative Interfaces Millennium ERM module. The library reviewed 3 system as potential replacements namely: Proquest 360 Resource Manager, Ex Libris Alma and Open Source CORAL ERMS. After comparing and trialling the systems, it was decided to go for Proquest 360 Resource Manager.

Challenges in hardening technologies using shallow-trench isolation

International Nuclear Information System (INIS)

Shaneyfelt, M.R.; Dodd, P.E.; Draper, B.L.; Flores, R.S.

1998-02-01

Challenges related to radiation hardening CMOS technologies with shallow-trench isolation are explored. Results show that trench hardening can be more difficult than simply replacing the trench isolation oxide with a hardened field oxide

Neutron energy spectrum influence on irradiation hardening and microstructural development of tungsten

Energy Technology Data Exchange (ETDEWEB)

Fukuda, Makoto, E-mail: makoto.fukuda@qse.tohoku.ac.jp [Tohoku University, Sendai, 980-8579 (Japan); Kiran Kumar, N.A.P.; Koyanagi, Takaaki; Garrison, Lauren M. [Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Snead, Lance L. [Massachusetts Institute of Technology, Cambridge, MA, 02139 (United States); Katoh, Yutai [Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Hasegawa, Akira [Tohoku University, Sendai, 980-8579 (Japan)

2016-10-15

Neutron irradiation to single crystal pure tungsten was performed in the mixed spectrum High Flux Isotope Reactor (HFIR). To investigate the influences of neutron energy spectrum, the microstructure and irradiation hardening were compared with previous data obtained from the irradiation campaigns in the mixed spectrum Japan Material Testing Reactor (JMTR) and the sodium-cooled fast reactor Joyo. The irradiation temperatures were in the range of ∼90–∼800 °C and fast neutron fluences were 0.02–9.00 × 10{sup 25} n/m{sup 2} (E > 0.1 MeV). Post irradiation evaluation included Vickers hardness measurements and transmission electron microscopy. The hardness and microstructure changes exhibited a clear dependence on the neutron energy spectrum. The hardness appeared to increase with increasing thermal neutron flux when fast fluence exceeds 1 × 10{sup 25} n/m{sup 2} (E > 0.1 MeV). Irradiation induced precipitates considered to be χ- and σ-phases were observed in samples irradiated to >1 × 10{sup 25} n/m{sup 2} (E > 0.1 MeV), which were pronounced at high dose and due to the very high thermal neutron flux of HFIR. Although the irradiation hardening mainly caused by defects clusters in a low dose regime, the transmutation-induced precipitation appeared to impose additional significant hardening of the tungsten. - Highlights: • The microstructure and irradiation hardening of single crystal pure W irradiated in HFIR was investigated. • The neutron energy spectrum influence was evaluated by comparing the HFIR results with previous work in Joyo and JMTR. • In the dose range up to ∼1 dpa, the neutron energy spectrum influence of irradiation hardening was not clear. • In the dose range above 1 dpa, the neutron energy influence on irradiation hardening and microstructural development was clearly observed. • The irradiation induced precipitates caused significant irradiation hardening of pure W irradiated in HFIR.

Radiation hardened COTS-based 32-bit microprocessor

International Nuclear Information System (INIS)

Haddad, N.; Brown, R.; Cronauer, T.; Phan, H.

1999-01-01

A high performance radiation hardened 32-bit RISC microprocessor based upon a commercial single chip CPU has been developed. This paper presents the features of radiation hardened microprocessor, the methods used to radiation harden this device, the results of radiation testing, and shows that the RAD6000 is well-suited for the vast majority of space applications. (authors)

use of electronic resources by graduate students of the department

African Journals Online (AJOL)

respondent's access electronic resources from the internet via Cybercafé .There is a high ... KEY WORDS: Use, Electronic Resources, Graduate Students, Cybercafé. INTRODUCTION ... Faculty of Education, University of Uyo, Uyo. Olu Olat ...

On residual stresses and fatigue of laser hardened steels

International Nuclear Information System (INIS)

Lin, Ru.

1992-01-01

This thesis deals with studies on residual stresses and fatigue properties of laser-transformation hardened steels. Two types of specimens, cylinders and fatigue specimens were used in the studies. The cylinders, made of Swedish steels SS 2244 and SS 2258 which correspond to AISI 4140 and AISI 52100 respectively, were locally hardened by a single scan of laser beam in the longitudinal direction, with various laser parameters. Residual stress distributions across the hardened tracks were measured by means of X-ray diffraction. The origins of residual stresses were investigated and discussed. For the fatigue specimens, including smooth and notched types made of Swedish steels SS 2244, SS 2225 and SS 1572 (similar to AISI 4140, AISI 4130 and AISI 1035, respectively), laser hardening was carried out in the gauge section. The residual stress field induced by the hardening process and the fatigue properties by plane bending fatigue test were studied. In order to investigate the stability of the residual stress field, stress measurements were also made on specimens being loaded near the fatigue limits for over 10 7 cycles. Further the concept of local fatigue strength was employed to correlate quantitatively the effect of hardness and residual stress field on the fatigue limits. In addition a group of smooth specimens of SS 2244 was induction hardened and the hardening results were compared with the corresponding laser hardened ones in terms of residual stress and fatigue behaviour. It has been found that compressive stresses exist in the hardened zone of all the specimens studied. The laser hardening condition, the specimen and how the hardening is carried out can significantly affect the residual stress field. Laser hardening can greatly improve the fatigue properties by inducing a hardened and compressed surface layer. (112 refs.)(au)

On residual stresses and fatigue of laser hardened steels

Energy Technology Data Exchange (ETDEWEB)

Lin, Ru.

1992-01-01

This thesis deals with studies on residual stresses and fatigue properties of laser-transformation hardened steels. Two types of specimens, cylinders and fatigue specimens were used in the studies. The cylinders, made of Swedish steels SS 2244 and SS 2258 which correspond to AISI 4140 and AISI 52100 respectively, were locally hardened by a single scan of laser beam in the longitudinal direction, with various laser parameters. Residual stress distributions across the hardened tracks were measured by means of X-ray diffraction. The origins of residual stresses were investigated and discussed. For the fatigue specimens, including smooth and notched types made of Swedish steels SS 2244, SS 2225 and SS 1572 (similar to AISI 4140, AISI 4130 and AISI 1035, respectively), laser hardening was carried out in the gauge section. The residual stress field induced by the hardening process and the fatigue properties by plane bending fatigue test were studied. In order to investigate the stability of the residual stress field, stress measurements were also made on specimens being loaded near the fatigue limits for over 10[sup 7] cycles. Further the concept of local fatigue strength was employed to correlate quantitatively the effect of hardness and residual stress field on the fatigue limits. In addition a group of smooth specimens of SS 2244 was induction hardened and the hardening results were compared with the corresponding laser hardened ones in terms of residual stress and fatigue behaviour. It has been found that compressive stresses exist in the hardened zone of all the specimens studied. The laser hardening condition, the specimen and how the hardening is carried out can significantly affect the residual stress field. Laser hardening can greatly improve the fatigue properties by inducing a hardened and compressed surface layer. (112 refs.)(au).

Precipitation hardening in a 12%Cr-9%Ni-4%Mo-2%Cu stainless steel

International Nuclear Information System (INIS)

Haettestrand, Mats; Nilsson, Jan-Olof; Stiller, Krystyna; Liu Ping; Andersson, Marcus

2004-01-01

A combination of complementary techniques including one-dimensional and three-dimensional atom probe, energy-filtered transmission electron microscopy and conventional transmission electron microscopy has been used to assess the precipitation reactions at 475 deg. C in a 12%Cr-9%Ni-4%Mo-2%Cu precipitation hardening stainless steel. The continuous hardening up to at least 1000 h of ageing was attributed to a sequence of precipitation reactions involving nickel-rich precipitates nucleating at copper clusters followed by molybdenum-rich quasicrystalline precipitates and nickel-rich precipitates of type L1 0 . An estimate of the relative contributions to the strength increment during tempering based on measurements of particle densities was performed. Nickel-rich precipitates were found to play the most important role up to about 40 h of ageing after which the effect of quasicrystalline particles became increasingly important

Laser Surface Hardening of Groove Edges

Science.gov (United States)

Hussain, A.; Hamdani, A. H.; Akhter, R.; Aslam, M.

2013-06-01

Surface hardening of groove-edges made of 3Cr13 Stainless Steel has been carried out using 500 W CO2 laser with a rectangular beam of 2.5×3 mm2. The processing speed was varied from 150-500 mm/min. It was seen that the hardened depth increases with increase in laser interaction time. A maximum hardened depth of around 1mm was achieved. The microhardness of the transformed zone was 2.5 times the hardness of base metal. The XRD's and microstructural analysis were also reported.

Electronic resource management practical perspectives in a new technical services model

CERN Document Server

Elguindi, Anne

2012-01-01

A significant shift is taking place in libraries, with the purchase of e-resources accounting for the bulk of materials spending. Electronic Resource Management makes the case that technical services workflows need to make a corresponding shift toward e-centric models and highlights the increasing variety of e-formats that are forcing new developments in the field.Six chapters cover key topics, including: technical services models, both past and emerging; staffing and workflow in electronic resource management; implementation and transformation of electronic resource management systems; the ro

Ultrafine-Grained Precipitation Hardened Copper Alloys by Swaging or Accumulative Roll Bonding

Directory of Open Access Journals (Sweden)

Igor Altenberger

2015-05-01

Full Text Available There is an increasing demand in the industry for conductive high strength copper alloys. Traditionally, alloy systems capable of precipitation hardening have been the first choice for electromechanical connector materials. Recently, ultrafine-grained materials have gained enormous attention in the materials science community as well as in first industrial applications (see, for instance, proceedings of NANO SPD conferences. In this study the potential of precipitation hardened ultra-fine grained copper alloys is outlined and discussed. For this purpose, swaging or accumulative roll-bonding is applied to typical precipitation hardened high-strength copper alloys such as Corson alloys. A detailed description of the microstructure is given by means of EBSD, Electron Channeling Imaging (ECCI methods and consequences for mechanical properties (tensile strength as well as fatigue and electrical conductivity are discussed. Finally the role of precipitates for thermal stability is investigated and promising concepts (e.g. tailoring of stacking fault energy for grain size reduction and alloy systems for the future are proposed and discussed. The relation between electrical conductivity and strength is reported.

Utilization of electronic information resources by academic staff at ...

African Journals Online (AJOL)

The study investigated the utilization of Electronic Information resources by the academic staff of Makerere University in Uganda. It examined the academic staff awareness of the resources available, the types of resources provided by the Makerere University Library, the factors affecting resource utilization. The study was ...

Study of the precipitation hardening process in recycled Al-Si-Cu cast alloys

Directory of Open Access Journals (Sweden)

Kuchariková L.

2017-03-01

Full Text Available The formation of extremely small uniformly dispersed particles of a second phase within the original phase matrix during heat treatment changed material properties. Therefore the characterization of precipitation had been investigated using high resolution transmission electron microscopy (TEM and electron diffraction of thin foils for an AlSi9Cu3 cast alloy. For investigation the hardening effect onto mechanical properties of aluminium cast was used heat treatment, which consisted from solution treatment at 515°C / 4 hours (h, followed by quenching into water with temperature 50°C and artificial aging using different temperatures 170°C and 190°C with different holding time 2, 4, 8, 16, and 32 hours. The observations of microstructure and substructure reveals that precipitation hardening has caused great changes in size, morphology and distributions of structural components, the formation of precipitates of Cu phases, and the change of mechanical properties as well.

Electronic Resources Management Project Presentation 2012

KAUST Repository

Ramli, Rindra M.

2012-01-01

This presentation describes the electronic resources management project undertaken by the KAUST library. The objectives of this project is to migrate information from MS Sharepoint to Millennium ERM module. One of the advantages of this migration

Hardening Embrittlement and Non-Hardening Embrittlement of Welding-Heat-Affected Zones in a Cr-Mo Low Alloy Steel

Directory of Open Access Journals (Sweden)

Yu Zhao

2018-06-01

Full Text Available The embrittlement of heat affected zones (HAZs resulting from the welding of a P-doped 2.25Cr-1Mo steel was studied by the analysis of the fracture appearance transition temperatures (FATTs of the HAZs simulated under a heat input of 45 kJ/cm with different peak temperatures. The FATTs of the HAZs both with and without tempering increased with the rise of the peak temperature. However, the FATTs were apparently lower for the tempered HAZs. For the as-welded (untempered HAZs, the FATTs were mainly affected by residual stress, martensite/austenite (M/A islands, and bainite morphology. The observed embrittlement is a hardening embrittlement. On the other hand, the FATTs of the tempered HAZs were mainly affected by phosphorus grain boundary segregation, thereby causing a non-hardening embrittlement. The results demonstrate that the hardening embrittlement of the as-welded HAZs was more severe than the non-hardening embrittlement of the tempered HAZs. Consequently, a post-weld heat treatment should be carried out if possible so as to eliminate the hardening embrittlement.

Practical guide to electronic resources in the humanities

CERN Document Server

Dubnjakovic, Ana

2010-01-01

From full-text article databases to digitized collections of primary source materials, newly emerging electronic resources have radically impacted how research in the humanities is conducted and discovered. This book, covering high-quality, up-to-date electronic resources for the humanities, is an easy-to-use annotated guide for the librarian, student, and scholar alike. It covers online databases, indexes, archives, and many other critical tools in key humanities disciplines including philosophy, religion, languages and literature, and performing and visual arts. Succinct overviews of key eme

Structural heredity influence upon principles of strain wave hardening

Science.gov (United States)

Kiricheck, A. V.; Barinov, S. V.; Yashin, A. V.

2017-02-01

It was established experimentally that by penetration of a strain wave through material hardened not only the technological modes of processing, but also a technological heredity - the direction of the fibers of the original macrostructure have an influence upon the diagram of microhardness. By penetration of the strain wave along fibers, the degree of hardening the material is less, however, a product is hardened throughout its entire section mainly along fibers. In the direction of the strain waves across fibers of the original structure of material, the degree of material hardening is much higher, the depth of the hardened layer with the degree of hardening not less than 50% makes at least 3 mm. It was found that under certain conditions the strain wave can completely change the original structure of the material. Thus, a heterogeneously hardened structure characterized by the interchange of harder and more viscous areas is formed, which is beneficial for assurance of high operational properties of material.

Thermomechanical properties of radiation hardened oligoesteracrylates

International Nuclear Information System (INIS)

Lomonosova, N.V.; Chikin, Yu.A.

1984-01-01

Thermomechanical properties of radiation hardened oligoesteracrylates are studied by the methods of isothermal heating and thermal mechanics. Films of dimethacrylate of ethylene glycol, triethylene glycol (TGM-3), tetraethylene glycol, tridecaethylene glycol and TGM-3 mixture with methyl methacrylate hardened by different doses (5-150 kGy) using Co 60 installation with a dose rate of 2x10 -3 kGy/s served as a subject of the research. During oligoesteracrylate hargening a space network is formed, chain sections between lattice points of which are in a stressed state. Maximum of deformation is observed at 210-220 deg C on thermomechanical curves of samples hardened by doses > 5 kGy, which form and intensity is dependent on an absorbed dose. Presence of a high-temperature maximum on diaqrams of isometric heating of spatially cross-linked oligoesteracrylates is discovered. High thermal stability of three-dimensional network of radiation hardened oligoesteracrylates provides satisfactory tensile properties (40% of initial strength) in sample testing an elevated temperatures (200-250 deg C)

Utilisation of Electronic Information Resources By Lecturers in ...

African Journals Online (AJOL)

This study assesses the use of information resources, specifically, electronic databases by lecturers/teachers in Universities and Colleges of Education in South Western Nigeria. Information resources are central to teachers' education. It provides lecturers/teachers access to information that enhances research and ...

Nitrogen nutrition and drought hardening exert opposite effects on the stress tolerance of Pinus pinea L. seedlings.

Science.gov (United States)

Villar-Salvador, Pedro; Peñuelas, Juan L; Jacobs, Douglass F

2013-02-01

Functional attributes determine the survival and growth of planted seedlings in reforestation projects. Nitrogen (N) and water are important resources in the cultivation of forest species, which have a strong effect on plant functional traits. We analyzed the influence of N nutrition on drought acclimation of Pinus pinea L. seedlings. Specifically, we addressed if high N fertilization reduces drought and frost tolerance of seedlings and whether drought hardening reverses the effect of high N fertilization on stress tolerance. Seedlings were grown under two N fertilization regimes (6 and 100 mg N per plant) and subjected to three drought-hardening levels (well-watered, moderate and strong hardening). Water relations, gas exchange, frost damage, N concentration and growth at the end of the drought-hardening period, and survival and growth of seedlings under controlled xeric and mesic outplanting conditions were measured. Relative to low-N plants, high-N plants were larger, had higher stomatal conductance (27%), residual transpiration (11%) and new root growth capacity and closed stomata at higher water potential. However, high N fertilization also increased frost damage (24%) and decreased plasmalemma stability to dehydration (9%). Drought hardening reversed to a great extent the reduction in stress tolerance caused by high N fertilization as it decreased frost damage, stomatal conductance and residual transpiration by 21, 31 and 24%, respectively, and increased plasmalemma stability to dehydration (8%). Drought hardening increased tissue non-structural carbohydrates and N concentration, especially in high-fertilized plants. Frost damage was positively related to the stability of plasmalemma to dehydration (r = 0.92) and both traits were negatively related to the concentration of reducing soluble sugars. No differences existed between moderate and strong drought-hardening treatments. Neither N nutrition nor drought hardening had any clear effect on seedling

Discipline, availability of electronic resources and the use of Finnish National Electronic Library - FinELib

Directory of Open Access Journals (Sweden)

Sanna Torma

2004-01-01

Full Text Available This study elaborated relations between digital library use by university faculty, users' discipline and the availability of key resources in the Finnish National Electronic Library (FinELib, Finnish national digital library, by using nationwide representative survey data. The results show that the perceived availability of key electronic resources by researchers in FinELib was a stronger predictor of the frequency and purpose of use of its services than users' discipline. Regardless of discipline a good perceived provision of central resources led to a more frequent use of FinELib. The satisfaction with the services did not vary with the discipline, but with the perceived availability of resources.

The Role of the Acquisitions Librarian in Electronic Resources Management

Science.gov (United States)

Pomerantz, Sarah B.

2010-01-01

With the ongoing shift to electronic formats for library resources, acquisitions librarians, like the rest of the profession, must adapt to the rapidly changing landscape of electronic resources by keeping up with trends and mastering new skills related to digital publishing, technology, and licensing. The author sought to know what roles…

Instabilities in power law gradient hardening materials

DEFF Research Database (Denmark)

Niordson, Christian Frithiof; Tvergaard, Viggo

2005-01-01

Tension and compression instabilities are investigated for specimens with dimensions in the micron range. A finite strain generalization of a higher order strain gradient plasticity theory is implemented in a finite element scheme capable of modeling power law hardening materials. Effects...... of gradient hardening are found to delay the onset of localization under plane strain tension, and significantly reduce strain gradients in the localized zone. For plane strain compression gradient hardening is found to increase the load-carrying capacity significantly....

Age hardening of cold-worked Zr-2.5 wt% Nb pressure tube alloy

International Nuclear Information System (INIS)

Kishore, R.; Singh, R.N.; Dey, G.K.; Sinha, T.K.

1992-01-01

Specimens for hardness and tensile tests, machined from a cold-worked zirconium-2.5% niobium pressure tube, with their axes parallel to longitudinal and transverse directions, were aged for 1 hr. at 300-500 C. The age hardening behaviour was monitored by mechanical tests, electron-microscopy and x-ray diffraction. In addition a few studies were carried on longitudinal tension specimens subjected to prolonged ageing (100-1000 hrs) at 300 C. It was observed that the short-term (1 hour) thermal ageing of this material at 300-400 C caused an increase in both strength and hardness without affecting ductility. It appears that the observed age-hardening is due to precipitation hardening by a niobium-rich phase and softening by recovery of cold-work and that the phenomenon is influenced by crystallographic texture. Further it was noted that a prolonged ageing at 300 C upto 1000 hrs, did not cause any appreciable changes in strength and ductility of the material compared to those obtained by 1 hour ageing at the same temperature. (author). 11 refs., 3 figs., 2 tabs

Analysis of Pedagogic Potential of Electronic Educational Resources with Elements of Autodidactics

Directory of Open Access Journals (Sweden)

Igor A.

2018-03-01

Full Text Available Introduction: in recent years didactic properties of electronic educational resources undergo considerable changes, nevertheless, the question of studying of such complete phenomenon as “an electronic educational resource with autodidactics elements” remains open, despite sufficient scientific base of researches of the terms making this concept. Article purpose – determination of essence of electronic educational resources with autodidactics elements. Materials and Methods: the main method of research was the theoretical analysis of the pedagogical and psychological literature on the problem under study. We used the theoretical (analysis, synthesis, comparison and generalization methods, the method of interpretation, pedagogical modeling, and empirical methods (observation, testing, conversation, interview, analysis of students’ performance, pedagogical experiment, peer review. Results: we detected the advantages of electronic educational resources in comparison with traditional ones. The concept of autodidactics as applied to the subject of research is considered. Properties of electronic educational resources with a linear and nonlinear principle of construction are studied.The influence of the principle of construction on the development of the learners’ qualities is shown. We formulated an integral definition of electronic educational resources with elements of autodidactics, namely, the variability, adaptivity and cyclicity of training. A model of the teaching-learning process with electronic educational resources is developed. Discussion and Conclusions: further development of a problem will allow to define whether electronic educational resources with autodidactics elements pedagogical potential for realization of educational and self-educational activity of teachers have, to modify technological procedures taking into account age features of students, their specialties and features of the organization of process of training of

Preservation and conservation of electronic information resources of ...

African Journals Online (AJOL)

The major holdings of the broadcast libraries of the Nigerian Television Authority (NTA) are electronic information resources; therefore, providing safe places for general management of these resources have aroused interest in the industry in Nigeria for sometimes. The need to study the preservation and conservation of ...

Effect of scandium on structure and hardening of Al–Ca eutectic alloys

Energy Technology Data Exchange (ETDEWEB)

Belov, N.A., E-mail: nikolay-belov@yandex.ru [National Research and Technological University “MISIS”, 4, Leninsky pr., Moscow 119049 (Russian Federation); Naumova, E.A. [Bauman Moscow State Technical University, 5, 2 ul. Baumanskaya, Moscow, 105005 (Russian Federation); Alabin, A.N. [National Research and Technological University “MISIS”, 4, Leninsky pr., Moscow 119049 (Russian Federation); UC RUSAL, 13/1, Nikoloyamskaya st., Moscow, 109240 (Russian Federation); Matveeva, I.A. [UC RUSAL, 13/1, Nikoloyamskaya st., Moscow, 109240 (Russian Federation)

2015-10-15

The phase composition, structure and hardening of alloys in the aluminium corner of the Al–Ca–Sc system were studied in the range up to 10% Ca and up to 1% S≿. The experimental study (optical, scanning and transmission electron microscopy with electron-microprobe analysis, differential thermal analysis and hardness measurements) was combined with Thermo-Calc software simulation for the optimization of the alloy composition. It was shown that only phases of the binary systems (Al{sub 4}Ca and Al{sub 3}Sc) might be in equilibrium with the aluminium solid solution. It was shown that the (Al) + Al{sub 4}Ca eutectic had a much finer structure as compared with the Al–Si eutectic, which suggests a possibility of reaching higher mechanical properties as compared to commercial alloys of the A356 type. The influence of the annealing temperature within the range up to 600 °C on the structure and hardness of the Al–Ca–Sc experimental alloys was studied. It was determined that the maximum hardening corresponded to the annealing at 300 °C, which was due to the precipitation of Al{sub 3}Sc nanoparticles with their further coarsening. With an example of an Al-7.6% Ca-0.3% Sc model experimental alloy, a principal possibility of manufacturing aluminium casting alloys based on the (Al) + Al{sub 4}Ca eutectic was demonstrated. Unlike commercial alloys of the A356 type, the model alloy does not require quenching, as hardening particles are formed in the course of annealing of casting. - Highlights: • Al–Ca–Sc phase diagram in aluminum corner. • Formation of Al{sub 3}Sc nanoparticles in eutectic (Al) + Al{sub 4}Ca during heating at 300–450 °C. • Hardening and thermal stability of proposed (Al–Ca–Sc) and commercial (Al–Si–Mg, 356 type) eutectic alloys.

Radiation hardenable coating mixture

International Nuclear Information System (INIS)

Howard, D.D.

1977-01-01

This invention relates to coatings that harden under radiation and to their compositions. Specifically, this invention concerns unsaturated urethane resins polymerisable by addition and to compositions, hardening under the effect of radiation, containing these resins. These resins feature the presence of at least one unsaturated ethylenic terminal group of structure CH 2 =C and containing the product of the reaction of an organic isocyanate compound with at least two isocyanate groups and one polyester polyol with at least two hydroxyl groups, and one unsaturated monomer compound polymerisable by addition having a single active hydrogen group reacting with the isocyanate [fr

Building an electronic resource collection a practical guide

CERN Document Server

Lee, Stuart D

2004-01-01

This practical book guides information professionals step-by-step through building and managing an electronic resource collection. It outlines the range of electronic products currently available in abstracting and indexing, bibliographic, and other services and then describes how to effectively select, evaluate and purchase them.

Analysis of Human Resources Management Strategy in China Electronic Commerce Enterprises

Science.gov (United States)

Shao, Fang

The paper discussed electronic-commerce's influence on enterprise human resources management, proposed and proved the human resources management strategy which electronic commerce enterprise should adopt from recruitment strategy to training strategy, keeping talent strategy and other ways.

Microstructural evolution at high strain rates in solution-hardened interstitial free steels

International Nuclear Information System (INIS)

Uenishi, A.; Teodosiu, C.; Nesterova, E.V.

2005-01-01

Comprehensive transmission electron microscopical studies have been conducted for solution-hardened steels deformed at high (1000 s -1 ) and low (0.001 s -1 ) strain rates, in order to clarify the effects of strain rate and a jump in strain rate on the evolution of the microstructure and its connection with the mechanical response. It was revealed that the various types of microstructure, observed even within the same specimen, depend on the corresponding grain orientations and their evolution with progressive deformation depends on these microstructure types. At high strain rates, the dislocation density increases especially at low strains and the onset of dislocation organization is delayed. A jump in strain rate causes an increase of the dislocation density inside an organized structure. These results corroborated the mechanical behaviour at high strain rates after compensation for the cross-sectional reduction and temperature increase. The higher work-hardening rate at high strain rates could be connected to a delay in the dislocation organization. The high work-hardening rate just after a jump could be due to an increase of the density of dislocations distributed uniformly inside an organized structure

Using XML Technologies to Organize Electronic Reference Resources

OpenAIRE

Huser, Vojtech; Del Fiol, Guilherme; Rocha, Roberto A.

2005-01-01

Provision of access to reference electronic resources to clinicians is becoming increasingly important. We have created a framework for librarians to manage access to these resources at an enterprise level, rather than at the individual hospital libraries. We describe initial project requirements, implementation details, and some preliminary results.

Fatigue hardening and softening studies on strain hardened 18-8 austenitic stainless steel

International Nuclear Information System (INIS)

Ramakrishna Prasad, C.; Vasudevan, R.

1976-01-01

Metals when subjected to fatigue harden or soften depending on their previous mechanical history. Annealed or mildly cold worked metals are known to harden while severely cold worked metals soften when subjected to fatigue loading. In the present work samples of austenitic 18-8 steel cold worked to 11% and 22% reduction in area were mounted in a vertical pulsator and fatigued in axial tension-compression. Clear cut effects were produced and it was noticed that these depended on the extent of cold work, the amplitude as well as the number of cycles of fatigue and mean stress if any. (orig.) [de

Electronic Resources and Mission Creep: Reorganizing the Library for the Twenty-First Century

Science.gov (United States)

Stachokas, George

2009-01-01

The position of electronic resources librarian was created to serve as a specialist in the negotiation of license agreements for electronic resources, but mission creep has added more functions to the routine work of electronic resources such as cataloging, gathering information for collection development, and technical support. As electronic…

Hardening parts by chrome plating in manufacture and repair

Science.gov (United States)

Astanin, V. K.; Pukhov, E. V.; Stekolnikov, Y. A.; Emtsev, V. V.; Golikova, O. A.

2018-03-01

In the engineering industry, galvanic coatings are widely used to prolong the service life of the machines, which contribute to the increase in the strength of the parts and their resistance to environmental influences, temperature and pressure drops, wear and fretting corrosion. Galvanic coatings have been widely applied in engineering, including agriculture, aircraft building, mining, construction, and electronics. The article focuses on the manufacturing methods of new agricultural machinery parts and the repair techniques of worn parts by chrome plating. The main attention is paid to the unstable methods of chromium deposition (in pulsed and reversing modes) in low-concentration electrolytes, which makes it possible to increase the reliability and durability of the hardened parts operation by changing the conditions of electrocrystallization, that is, directed formation of the structure and texture, thickness, roughness and microhardness of chromium plating. The practical recommendations are given on the current and temperature regimes of chromium deposition and composition of baths used for the restoration and hardening of the machine parts. Moreover, the basic methods of machining allowances removal are analysed.

Study of the mechanisms involved in the laser superficial hardening process of metallic alloys

International Nuclear Information System (INIS)

Silva, Edmara Marques Rodrigues da

2001-01-01

The laser superficial hardening process of a ferrous alloy (gray cast iron) and of an aluminum-silicon alloy was investigated in this work. These metallic alloys are used in the automobile industry for manufacturing cylinders and pistons, respectively. By application of individual pulses and single tracks, the involved mechanisms during the processing were studied. Variables such as energy density, power density, temporal width, beam diameter on the sample surface, atmosphere of the processing region, overlapping and scanning velocity. The hardened surface was characterized by optical and scanning electronic microscopy, dispersive energy microanalysis, X-ray mapping, X-ray diffraction, and measurements of roughness and Vickers microhardness. Depending on the processing parameters, it is possible to obtain different microstructures. The affected area of gray cast iron, can be hardened by remelting or transformation hardening (total or partial) if the reached temperature is higher or not that of melting temperature. Laser treatment originated new structures such as retained austenite, martensite and, occasionally, eutectic of cellular dendritic structure. Aluminum-silicon alloy does not have phase transformation in solid state, it can be hardened only by remelting. The increase of hardness is a function of the precipitation hardening process, which makes the silicon particles smaller and more disperse in the matrix. Maximal values of microhardness (700-1000 HV) were reached with the laser treatment in gray cast iron samples. The initial microhardness is of 242 HV. For aluminum-silicon alloy, the laser remelting increases the initial microhardness of 128 HV to the range of 160-320 HV. The found results give a new perspective for using the CLA/IPEN's laser in the heat treatment area. Besides providing a higher absorptivity to the materials, compared with the CO 2 laser, and optical fiber access, the superficial hardening with Nd:YAG laser, depending on the level of

Application of low energy electron beam to precoated steel plates

International Nuclear Information System (INIS)

Koshiishi, Kenji

1989-01-01

Recently in the fields of home electric appliances, machinery and equipment and interior building materials, the needs for the precoated steel plates having the design and function of high class increase rapidly. In order to cope with such needs, the authors have advanced the examination on the application of electron beam hardening technology to precoated steel plates, and developed the precoated steel plates of high grade and high design 'Super Tecstar EB Series' by utilizing low energy electron beam. The features of this process are (1) hardening can be done at room temperature in a short time-thermally weak films can be adhered, (2) high energy irradiation-the hardening of thick enamel coating and the adhesion of colored films are feasible, (3) the use of monomers of low molecular weight-by high crosslinking, the performance of high sharpness, high hardness, anti-contamination property and so on can be given. The application to precoated steel plate production process is the coating and curing of electron beam hardening type paints, the coating of films with electron beam hardening type adhesives, and the reforming of surface polymer layers by impregnating monomers and causing graft polymerization with electron beam irradiation. The outline of the Super Tecstar EB Series is described. (K.I.)

A review of the stages of work hardening

Energy Technology Data Exchange (ETDEWEB)

Rollett, A.D.; Kocks, U.F.

1993-07-01

Stages of work hardening are reviewed with emphasis on links between each stage. Simple quantitative descriptions are given for each stage. Similarities between stage I, easy glide, and stage IV, large strain hardening, are pointed out both in terms of magnitude of the hardening rate and of the underlying mechanism of dislocation debris accumulation. Stage II is described as an athermal hardening stage that occurs when statistical variations in the dislocation ``forest`` lead to geometrical storage of dislocations. The steadily decreasing hardening rate observed in stage III is characterized by the increasing rate of loss of dislocation density due to dynamic recovery. Stage III appears to have an asymptote to a saturation stress which is determined by the characteristics of the dislocation tangles, or cell walls. The imperfect nature of the dynamic recovery process, however, leads to the accumulation of dislocation debris and this, by analogy with stage 1, causes the apparent saturation stress to rise, thus causing stage IV.

Radiation-hardened bulk Si-gate CMOS microprocessor family

International Nuclear Information System (INIS)

Stricker, R.E.; Dingwall, A.G.F.; Cohen, S.; Adams, J.R.; Slemmer, W.C.

1979-01-01

RCA and Sandia Laboratories jointly developed a radiation-hardened bulk Si-gate CMOS technology which is used to fabricate the CDP-1800 series microprocessor family. Total dose hardness of 1 x 10 6 rads (Si) and transient upset hardness of 5 x 10 8 rads (Si)/sec with no latch up at any transient level was achieved. Radiation-hardened parts manufactured to date include the CDP-1802 microprocessor, the CDP-1834 ROM, the CDP-1852 8-bit I/O port, the CDP-1856 N-bit 1 of 8 decoder, and the TCC-244 256 x 4 Static RAM. The paper is divided into three parts. In the first section, the basic fundamentals of the non-hardened C 2 L technology used for the CDP-1800 series microprocessor parts is discussed along with the primary reasons for hardening this technology. The second section discusses the major changes in the fabrication sequence that are required to produce radiation-hardened devices. The final section details the electrical performance characteristics of the hardened devices as well as the effects of radiation on device performance. Also included in this section is a discussion of the TCC-244 256 x 4 Static RAM designed jointly by RCA and Sandia Laboratories for this application

Deflection hardening behaviour of short fibre reinforced fly ash based geopolymer composites

International Nuclear Information System (INIS)

Shaikh, F.U.A.

2013-01-01

Highlights: • Deflection hardening behaviour is achieved in the DFRGC similar to that observed in DFRCC. • The first crack load or in other word the limit of proportionality (LOP) of DFRGC is similar to that of DFRCC. • The DFRGC also exhibited higher deflection at peak load than DFRCC. • The toughness at peak load of DFRGC is also high than that of DFRCC. • The ductility of DFRGC is also higher than that of DFRCC. - Abstract: This paper reports the newly developed ductile fibre reinforced geopolymer composite (DFRGC) exhibiting deflection hardening and multiple cracking behaviour. The binder of the above composite is different from that used in conventional cement based system. The class F fly ash is used instead of Portland cement in DFRGC and is activated by alkaline liquids (sodium hydroxide and sodium silicate). In this study, two types of fibres namely steel (ST) and polyvinyl alcohol (PVA) fibres are used in mono as well as in ST–PVA hybrid form, with a total volume fraction of 2%. The deflection hardening behaviour of newly developed DFRGC is also compared with that of conventional ductile fibre reinforced cementitious composites (DFRCC). The effects of two different sizes of sand (1.18 mm, and 0.6 mm) and sand/binder ratios of 0.5 and 0.75 on the deflection hardening and multiple cracking behaviour of both DFRGC and DFRCC are also evaluated. Results revel that the deflection hardening and multiple cracking behaviour is achieved in geopolymer based DFRGC similar to that of cement based system. For a given sand size and sand content, comparable deflection hardening behaviour, ultimate flexural strength and the deflection at peak load are observed in both cement and geopolymer based composites irrespective of fibre types and combination. The deflection hardening behaviour of DFRGC is also confirmed by the calculated toughness index values of I 20 > 20. The scanning electron microscope (SEM) study shows no degradation of PVA and steel fibres in the

Electronic Resources Management System: Recommendation Report 2017

KAUST Repository

Ramli, Rindra M.

2017-01-01

This recommendation report provides an overview of the selection process for the new Electronic Resources Management System. The library has decided to move away from Innovative Interfaces Millennium ERM module. The library reviewed 3 system

X-ray beam hardening correction for measuring density in linear accelerator industrial computed tomography

International Nuclear Information System (INIS)

Zhou Rifeng; Wang Jue; Chen Weimin

2009-01-01

Due to X-ray attenuation being approximately proportional to material density, it is possible to measure the inner density through Industrial Computed Tomography (ICT) images accurately. In practice, however, a number of factors including the non-linear effects of beam hardening and diffuse scattered radiation complicate the quantitative measurement of density variations in materials. This paper is based on the linearization method of beam hardening correction, and uses polynomial fitting coefficient which is obtained by the curvature of iron polychromatic beam data to fit other materials. Through theoretical deduction, the paper proves that the density measure error is less than 2% if using pre-filters to make the spectrum of linear accelerator range mainly 0.3 MeV to 3 MeV. Experiment had been set up at an ICT system with a 9 MeV electron linear accelerator. The result is satisfactory. This technique makes the beam hardening correction easy and simple, and it is valuable for measuring the ICT density and making use of the CT images to recognize materials. (authors)

Preparation of Self Hardening-modelling Polyurethane for Wood Repairing and Cracks Injection

International Nuclear Information System (INIS)

Meligi, G.A.; Elnahas, H.H.; Ammar, A.H.

2014-01-01

Self hardening composite as a modelling clay was prepared from polyurethane, two parts (A) and (B) where (A) contains polyol (polyether), vinyl acetate versatic ester copolymer (VAcVe) and magnesium silicate or wood powder and (B) contains toluene diisocyanate (TDI) as a hardening agent. The two parts mixed thoroughly giving soft putty like feel, open working time 1-2 h and cures hard overnight (24 h full cure). Factors affecting working time and full cure were evaluated. Also, measurements of surface hardness, compressive strength, scanning electron microscopy (SEM), water absorption and effect of ionizing radiation were studied. The suggestion for using the prepared polyurethane composite as clay dries as hard as a rock in the field of wood repair and cracks injection for building walls were recommended. Keywords: Polyurethane, modelling clay, radiation, wood repair and cracks injection.

Investigation of a Hardened Cement Paste Grout

DEFF Research Database (Denmark)

Esteves, Luis Pedro; Sørensen, Eigil Verner

This report documents a series of tests performed on a hardened cement paste grout delivered by the client, Det Norske Veritas A/S.......This report documents a series of tests performed on a hardened cement paste grout delivered by the client, Det Norske Veritas A/S....

Bake hardening of ultra-fine grained low carbon steel produced by constrained groove pressing

International Nuclear Information System (INIS)

Alihosseini, H.; Dehghani, K.

2012-01-01

Highlights: ► BH of UFG low carbon steel sheets was studied. ► Three passes of CGP are used for producing of UFG sheets. ► Maximum BH was achieved to the UFG specimen pre-strained 8% by baking at 250 °C. - Abstract: In the present work, the bake hardening of ultra-fine grained low carbon steel was compared with that of its coarse-grain counterpart. The ultra-fine grained sheets were produced by applying three passes of constrained groove pressing resulting the grains of 260–270 nm. The microstructure of ultra-fine grain specimens were characterized using electron back-scatter diffraction technique. Then, the bake hardenability of ultra-fine grain and coarse-grain samples were compared by pre-straining to 4, 6 and 8% followed by baking at 150 °C and 250 °C for 20 min. The results show that in case of baking at 250 °C, there was an increase about 108%, 93%, and 72% in the bake hardening for 4%, 6% and 8% pre-strain, respectively. As for baking at 150 °C, these values were 170%, 168%, and 100%, respectively for 4%, 6% and 8% pre-strain. The maximum in bake hardenability (103 MPa) and final yield stress (563 MPa) were pertaining to the ultra-fine grain specimen pre-strained 8% followed by baking at 250 °C.

The Internet School of Medicine: use of electronic resources by medical trainees and the reliability of those resources.

Science.gov (United States)

Egle, Jonathan P; Smeenge, David M; Kassem, Kamal M; Mittal, Vijay K

2015-01-01

Electronic sources of medical information are plentiful, and numerous studies have demonstrated the use of the Internet by patients and the variable reliability of these sources. Studies have investigated neither the use of web-based resources by residents, nor the reliability of the information available on these websites. A web-based survey was distributed to surgical residents in Michigan and third- and fourth-year medical students at an American allopathic and osteopathic medical school and a Caribbean allopathic school regarding their preferred sources of medical information in various situations. A set of 254 queries simulating those faced by medical trainees on rounds, on a written examination, or during patient care was developed. The top 5 electronic resources cited by the trainees were evaluated for their ability to answer these questions accurately, using standard textbooks as the point of reference. The respondents reported a wide variety of overall preferred resources. Most of the 73 responding medical trainees favored textbooks or board review books for prolonged studying, but electronic resources are frequently used for quick studying, clinical decision-making questions, and medication queries. The most commonly used electronic resources were UpToDate, Google, Medscape, Wikipedia, and Epocrates. UpToDate and Epocrates had the highest percentage of correct answers (47%) and Wikipedia had the lowest (26%). Epocrates also had the highest percentage of wrong answers (30%), whereas Google had the lowest percentage (18%). All resources had a significant number of questions that they were unable to answer. Though hardcopy books have not been completely replaced by electronic resources, more than half of medical students and nearly half of residents prefer web-based sources of information. For quick questions and studying, both groups prefer Internet sources. However, the most commonly used electronic resources fail to answer clinical queries more than half

Correlation of microstructure and strain hardening behavior in the ultrafine-grained Nb-bearing dual phase steels

Energy Technology Data Exchange (ETDEWEB)

Ghatei Kalashami, A. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Kermanpur, A., E-mail: ahmad_k@cc.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Ghassemali, E. [Jönköping University, School of Engineering, Department of Materials and Manufacturing, P.O. Box 1026, SE-551 11 Jönköping (Sweden); Najafizadeh, A. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Mazaheri, Y. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Department of Materials Engineering, Bu-Ali Sina University, Hamedan 65178-38695 (Iran, Islamic Republic of)

2016-12-15

Ultrafine-grained dual phase (DP) steels with different Nb contents (0.00, 0.06 and 0.12 wt%) were produced by cold-rolling followed by intercritical annealing of ferrite/martensite starting microstructure at 770 °C for different holding times. Scanning electron microscopy, equipped with electron backscattered diffraction (EBSD) detector, nanoindentation and tensile testing were used to characterize microstructural evolutions and their correlations to the strain hardening and fracture behavior. EBSD results confirmed the retardation effect of Nb on recrystallization. It was found that the strains stored in the grains and density of geometrically necessary dislocations (GNDs) were increased with the addition of Nb. Strain hardening analysis showed that plastic deformation of the DP steels occurred in three distinct stages, which based on the EBSD results, nanoindentation and fracture analysis, were controlled by microstructural features such martensite volume fraction and size, density of GNDs and individual ferrite and martensite tensile properties.

Hardening by ion implantation of VT1-0 alloy having different grain size

Energy Technology Data Exchange (ETDEWEB)

Nikonenko, Alisa, E-mail: aliska-nik@mail.ru; Kurzina, Irina, E-mail: kurzina99@mail.ru [National Research Tomsk State University, 36, Lenin Str., 634050, Tomsk (Russian Federation); Popova, Natalya, E-mail: natalya-popova-44@mail.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Institute of Strength Physics and Materials Science, SB RAS, 2/4, Akademicheskii Ave., 634021, Tomsk Russia (Russian Federation); Nikonenko, Elena, E-mail: vilatomsk@mail.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Str., 634050, Tomsk (Russian Federation); Kalashnikov, Mark, E-mail: kmp1980@mail.ru [Institute of Strength Physics and Materials Science, SB RAS, 2/4, Akademicheskii Ave., 634021, Tomsk Russia (Russian Federation)

2016-01-15

The paper presents a transmission electron microscopy (TEM) study of the structural and phase state of commercially pure titanium implanted by aluminum ions. TEM study has been carried out for two types of grains, namely coarse (0.4 µm) and small (0.5 µm). This paper presents details of the yield stress calculations and the analysis of strength components for the both grain types in two areas of the modified layer: at a distance of 0-150 nm (surface area I) and ∼300 nm (central area II) from the irradiated surface. It is shown that the ion implantation results in a considerable hardening of the entire thickness of the implanted layer in the both grain types. The grain size has, however, a different effect on the yield stress in areas I and II. Thus, near the ion-alloyed layer, the yield stress decreases with the increase of the grain size, whilst area II demonstrates its increase. Moreover, the contribution to the general hardening of the alloy made by certain hardening mechanisms differs from contributions made by each of these mechanisms in each certain case.

A Study of Tensile Flow and Work-Hardening Behavior of Alloy 617

Science.gov (United States)

Singh, Aditya Narayan; Moitra, A.; Bhaskar, Pragna; Dasgupta, Arup; Sasikala, G.; Bhaduri, A. K.

2018-04-01

The simple power relationship σ = Κɛ p n satisfactorily expresses the tensile flow behavior of many metals and alloys in their uniform plastic strain regime. However, many FCC materials with low stacking fault energy have opposed such power law relationship. Alloy 617, an age-hardenable Ni-based superalloy is also observed not to obey the simple power law relationship neither in its solution-treated nor in its aged conditions. Various flow relationships were used to obtain the best fit for the tensile data, and different relationships were identified for the different aged conditions. The work-hardening rate (θ) demonstrates three distinct regions for all aged conditions, and there is an obvious change in the trend of θ versus σ. In the initial portion, θ decreases rapidly followed by a gradual increase in the second stage and again a decrease in its third stage is perceived in the Alloy 617. These three-stage characteristics are attributed to a commonly known precipitate, γ': Ni3(Ti, Al) which evolves during aging treatment and well recognized under transmission electron microscopy (TEM) observation. TEM results also reveal a slight degree of coarsening in γ' over aging. The tensile flow and the work-hardening behavior are well correlated with other microstructural evolution during the aging treatments.

Numerical and experimental comparison of plastic work-hardening rules

International Nuclear Information System (INIS)

Haisler, W.E.

1977-01-01

The purpose of this paper is to describe recent numerical and experimental correlation studies of several plastic work-hardening rules. The mechanical sublayer model and the combined kinematic-isotropic hardening rules are examined and the numerical results for several structural geometries are compared to experimental results. Both monotonic and cyclic loads are considered. The governing incremental plasticity relations are developed for both work-hardening models. The combined kinematic-isotropic hardening model is developed in terms of a ratio γ which controls the relative contribution of kinematic hardening (yield surface translation) and isotropic hardening (yield surface expansion). In addition to making use of a uniaxial stress-strain curve as input data, the model allows for the input of a yield surface size vs. uniaxial plastic strain curve obtained from a cyclic uniaxial reverse loading test. The mechanical sublayer model is developed in general form and a new method for determining the sublayer parameters (stress weighting factors and yield stresses) is presented. It is demonstrated that former procedures used to obtain the sublayer parameters are inconsistent for multiaxial loading. Numerical and experimental results are presented for a cylinder, circular plate with punch, and a steel pressure vessel. The numerical results are obtained with the computer program AGGIE I. The comparison study indicates that reasonable agreement is obtained with both hardening models; the choice depending upon whether the loading is monotonic or cyclic

Age hardening of a sintered Al-Cu-Mg-Si-(Sn) alloy

International Nuclear Information System (INIS)

Kent, D.; Schaffer, G.B.; Drennan, J.

2005-01-01

The age hardening response of a sintered Al-3.8 wt% Cu-1.0 wt% Mg-0.70 wt% Si alloy with and without 0.1 wt% Sn was investigated. The sequence of precipitation was characterised using transmission electron microscopy. The ageing response of the sintered Al-Cu-Mg-Si-(Sn) alloy is similar to that of cognate wrought 2xxx series alloys. Peak hardness was associated with a fine, uniform dispersion of lath shaped precipitates, believed to be either the β'or Q' phase, oriented along α directions and θ' plates lying on {0 0 1} α planes. Natural ageing also resulted in comparable behaviour to that observed in wrought alloys. Porosity in the powder metallurgy alloys did not significantly affect the kinetics of precipitation during artificial ageing. Trace levels of tin, used to aid sintering, slightly reduced the hardening response of the alloy. However, this was compensated for by significant improvements in density and hardness

ANALYTICAL REVIEW OF ELECTRONIC RESOURCES FOR THE STUDY OF LATIN

Directory of Open Access Journals (Sweden)

Olena Yu. Balalaieva

2014-04-01

Full Text Available The article investigates the current state of development of e-learning content in the Latin language. It is noted that the introduction of ICT in the educational space has expanded the possibility of studying Latin, opened access to digital libraries resources, made it possible to use scientific and educational potential and teaching Latin best practices of world's leading universities. A review of foreign and Ukrainian information resources and electronic editions for the study of Latin is given. Much attention was paid to the didactic potential of local and online multimedia courses of Latin, electronic textbooks, workbooks of interactive tests and exercises, various dictionaries and software translators, databases and digital libraries. Based on analysis of the world market of educational services and products the main trends in the development of information resources and electronic books are examined. It was found that multimedia courses with interactive exercises or workbooks with interactive tests, online dictionaries and translators are the most widely represented and demanded. The noticeable lagging of Ukrainian education and computer linguistics in quantitative and qualitative measures in this industry is established. The obvious drawback of existing Ukrainian resources and electronic editions for the study of Latin is their noninteractive nature. The prospects of e-learning content in Latin in Ukraine are outlined.

Elektronik Bilgi Kaynaklarının Seçimi / Selection of Electronic Information Resources

Directory of Open Access Journals (Sweden)

Pınar Al

2003-04-01

Full Text Available For many years, library users have used only from the printed media in order to get the information that they have needed. Today with the widespread use of the Web and the addition of electronic information resources to library collections, the use of information in the electronic environment as well as in printed media is started to be used. In time, such types of information resources as, electronic journals, electronic books, electronic encyclopedias, electronic dictionaries and electronic theses have been added to library collections. In this study, selection criteria that can be used for electronic information resources are discussed and suggestions are provided for libraries that try to select electronic information resources for their collections.

COMPLEX SURFACE HARDENING OF STEEL ARTICLES

Directory of Open Access Journals (Sweden)

A. V. Kovalchuk

2014-01-01

Full Text Available The method of complex surface hardening of steel detailswas designed. The method is a compound of two processes of hardening: chemical heat treatment and physical vapor deposition (PVD of the coating. The result, achieved in this study is much higher, than in other work on this topic and is cumulative. The method designed can be used in mechanical engineering, medicine, energetics and is perspective for military and space technologies.

Radiation-hardened control system

International Nuclear Information System (INIS)

Vandermolen, R.I.; Smith, S.F.; Emery, M.S.

1993-01-01

A radiation-hardened bit-slice control system with associated input/output circuits was developed to prove that programmable circuits could be constructed to successfully implement intelligent functions in a highly radioactive environment. The goal for this effort was to design and test a programmable control system that could withstand a minimum total dose of 10 7 rads (gamma). The Radiation Hardened Control System (RHCS) was tested in operation at a dose rate that ranged up to 135 krad/h, with an average total dose of 10.75 Mrads. Further testing beyond the required 10 7 rads was also conducted. RHCS performed properly through the target dose of 10 7 rads, and sporadic intermittent failures in some programmable logic devices were noted after ∼ 13 Mrads

Access to electronic resources by visually impaired people

Directory of Open Access Journals (Sweden)

Jenny Craven

2003-01-01

Full Text Available Research into access to electronic resources by visually impaired people undertaken by the Centre for Research in Library and Information Management has not only explored the accessibility of websites and levels of awareness in providing websites that adhere to design for all principles, but has sought to enhance understanding of information seeking behaviour of blind and visually impaired people when using digital resources.

Dislocation-mediated strain hardening in tungsten: Thermo-mechanical plasticity theory and experimental validation

Science.gov (United States)

Terentyev, Dmitry; Xiao, Xiazi; Dubinko, A.; Bakaeva, A.; Duan, Huiling

2015-12-01

A self-consistent thermo-mechanical model to study the strain-hardening behavior of polycrystalline tungsten was developed and validated by a dedicated experimental route. Dislocation-dislocation multiplication and storage, as well dislocation-grain boundary (GB) pinning were the major mechanisms underlying the evolution of plastic deformation, thus providing a link between the strain hardening behavior and material's microstructure. The microstructure of the polycrystalline tungsten samples has been thoroughly investigated by scanning and electron microscopy. The model was applied to compute stress-strain loading curves of commercial tungsten grades, in the as-received and as-annealed states, in the temperature range of 500-1000 °C. Fitting the model to the independent experimental results obtained using a single crystal and as-received polycrystalline tungsten, the model demonstrated its capability to predict the deformation behavior of as-annealed samples in a wide temperature range and applied strain. The relevance of the dislocation-mediated plasticity mechanisms used in the model have been validated using transmission electron microscopy examination of the samples deformed up to different amounts of strain. On the basis of the experimental validation, the limitations of the model are determined and discussed.

Hardening of niobium alloys at precrystallization annealing

International Nuclear Information System (INIS)

Vasil'eva, E.V.; Pustovalov, V.A.

1989-01-01

Niobium base alloys were investigated. It is shown that precrystallization annealing of niobium-molybdenum, niobium-vanadium and niobium-zirconium alloys elevates much more sufficiently their resistance to microplastic strains, than to macroplastic strains. Hardening effect differs sufficiently for different alloys. The maximal hardening is observed for niobium-vanadium alloys, the minimal one - for niobium-zirconium alloys

Library training to promote electronic resource usage

DEFF Research Database (Denmark)

Frandsen, Tove Faber; Tibyampansha, Dativa; Ibrahim, Glory

2017-01-01

Purpose: Increasing the usage of electronic resources is an issue of concern for many libraries all over the world. Several studies stress the importance of information literacy and instruction in order to increase the usage. Design/methodology/approach: The present article presents the results...

Why and How to Measure the Use of Electronic Resources

Directory of Open Access Journals (Sweden)

Jean Bernon

2008-11-01

Full Text Available A complete overview of library activity implies a complete and reliable measurement of the use of both electronic resources and printed materials. This measurement is based on three sets of definitions: document types, use types and user types. There is a common model of definitions for printed materials, but a lot of questions and technical issues remain for electronic resources. In 2006 a French national working group studied these questions. It relied on the COUNTER standard, but found it insufficient and pointed out the need for local tools such as web markers and deep analysis of proxy logs. Within the French national consortium COUPERIN, a new working group is testing ERMS, SUSHI standards, Shibboleth authentication, along with COUNTER standards, to improve the counting of the electronic resources use. At this stage this counting is insufficient and its improvement will be a European challenge for the future.

Multi-MGy Radiation Hardened Camera for Nuclear Facilities

International Nuclear Information System (INIS)

Girard, Sylvain; Boukenter, Aziz; Ouerdane, Youcef; Goiffon, Vincent; Corbiere, Franck; Rolando, Sebastien; Molina, Romain; Estribeau, Magali; Avon, Barbara; Magnan, Pierre; Paillet, Philippe; Duhamel, Olivier; Gaillardin, Marc; Raine, Melanie

2015-01-01

electronics will be exposed. Another important element of the camera is the optical system that transports the image from the scene to the image sensor. This arrangement of glass-based lenses is affected by radiations through two mechanisms: the radiation induced absorption and the radiation induced refractive index changes. The first one will limit the signal to noise ratio of the image whereas the second one will directly affect the resolution of the camera. We'll present at the conference a coupled simulation/experiment study of these effects for various commercial glasses and present vulnerability study of typical optical systems to radiations at MGy doses. The last very important part of the camera is the illumination system that can be based on various technologies of emitting devices like LED, SLED or lasers. The most promising solutions for high radiation doses will be presented at the conference. In addition to this hardening-by-component approach, the global radiation tolerance of the camera can be drastically improve by working at the system level, combining innovative approaches eg. for the optical and illumination systems. We'll present at the conference the developed approach allowing to extend the camera lifetime up to the MGy dose range. (authors)

Multi-MGy Radiation Hardened Camera for Nuclear Facilities

Energy Technology Data Exchange (ETDEWEB)

Girard, Sylvain; Boukenter, Aziz; Ouerdane, Youcef [Universite de Saint-Etienne, Lab. Hubert Curien, UMR-CNRS 5516, F-42000 Saint-Etienne (France); Goiffon, Vincent; Corbiere, Franck; Rolando, Sebastien; Molina, Romain; Estribeau, Magali; Avon, Barbara; Magnan, Pierre [ISAE, Universite de Toulouse, F-31055 Toulouse (France); Paillet, Philippe; Duhamel, Olivier; Gaillardin, Marc; Raine, Melanie [CEA, DAM, DIF, F-91297 Arpajon (France)

2015-07-01

electronics will be exposed. Another important element of the camera is the optical system that transports the image from the scene to the image sensor. This arrangement of glass-based lenses is affected by radiations through two mechanisms: the radiation induced absorption and the radiation induced refractive index changes. The first one will limit the signal to noise ratio of the image whereas the second one will directly affect the resolution of the camera. We'll present at the conference a coupled simulation/experiment study of these effects for various commercial glasses and present vulnerability study of typical optical systems to radiations at MGy doses. The last very important part of the camera is the illumination system that can be based on various technologies of emitting devices like LED, SLED or lasers. The most promising solutions for high radiation doses will be presented at the conference. In addition to this hardening-by-component approach, the global radiation tolerance of the camera can be drastically improve by working at the system level, combining innovative approaches eg. for the optical and illumination systems. We'll present at the conference the developed approach allowing to extend the camera lifetime up to the MGy dose range. (authors)

Improvement of wear resistance of machine elements by plasma spraying followed by hardening in the chlorine-barium melt

International Nuclear Information System (INIS)

Fominykh, V.V.; Stepanov, V.V.

1979-01-01

Proposed is the mathematical model, allowing to choose the optimal regime of sprayed coating hardening in the BaCl 2 salt melt. The method of hardening of machine elements by spraying wear resistance coatings of the Ni-Cr-B-Si alloys is described. It is established that diffusion heating followed by coating melting in the BaCl 2 solution increases the adhesion of sprayed layer to substrate metal. The formation of intermediate intermetallic compounds of the Ni 3 Si and Ni 3 Fe types takes place as a result of diffusion of interacting material atoms and valence electron joining

Combinative hardening effects of precipitation in a commercial aged Al–Cu–Li–X alloy

Energy Technology Data Exchange (ETDEWEB)

Chen, Zhongwei, E-mail: chzw@nwpu.edu.cn; Zhao, Kai; Fan, Li

2013-12-20

The combinative effects of precipitates on microstructure and hardness of an Al–Cu–Li–X alloy (X=Mg, Zn, Mn, Zr) in artificial ageing of 165 °C were investigated by a transmission electron microscopy and hardness test. Results show that the hardness appears at regression in early ageing stage and increases rapidly during subsequent ageing of 16 h. Hardening effects of as-quenched sample are mainly attributed to β′ (Al{sub 3}Zr) dispersoids, quenched-in vacancies and dislocations. Though most of the fine and uniform precipitates θ′ (Al{sub 2}Cu), δ′ (Al{sub 3}Li), σ (Al{sub 5}Cu{sub 6}Mg{sub 2}) and GP zone came into being in ageing of 0.5 h, annihilation of quenched-in vacancies and reduction of dislocation were ascribed to the hardening regression at early stages of ageing. As further ageing is in progress, all precipitates including T{sub 1} (Al{sub 2}CuLi), σ, δ′ and θ′ have appeared during the ageing of 16 h that follows, and their combinative hardening effects are responsible for the rapid hardness increase at peak-ageing.

Investigation of srawberry hardening in low temperatures in vitro

OpenAIRE

Lukoševičiūtė, Vanda; Rugienius, Rytis; Kavaliauskaitė, Danguolė

2007-01-01

Cold resistance of different strawberry varieties in vitro and ability to retain hardening after defrosting and repeated hardening. Phytohormons – gibberellin and abscisic acid added in the growing medium were investigated in Horticulture plant genetic and biotechnology department of LIH. We tried to model common conditions in temperate zone when freeze-thaw cycles often occur during wintertime. For investigation in vitro strawberries for the first time hardened in light at the temperature of...

Exploring visitor acceptability for hardening trails to sustain visitation and minimize impacts

Science.gov (United States)

Cahill, K.L.; Marion, J.L.; Lawson, S.R.

2008-01-01

Protected natural area managers are challenged to provide high quality recreation opportunities and ensure the protection of resources from impacts associated with visitation. Development of visitor use facilities and application of site hardening practices are commonly applied tools for achieving these competing management objectives. This study applies stated choice analysis to examine visitor opinions on acceptability when they are asked to make tradeoffs among competing social, resource and management attributes in backcountry and frontcountry settings of Acadia National Park. This study demonstrates that asking visitors about recreation setting attributes uni-dimensionally, a common approach, can yield less informative responses. Analyses that considered direct tradeoffs revealed more divergent opinions on acceptability for setting attributes than a unidimensional approach. Findings revealed that visitors to an accessible and popular attraction feature supported trail development options to protect resource conditions with unrestricted visitor access. In contrast, visitors to a remote undeveloped island expressed stronger support for no or limited trail development and access restrictions to protect resource conditions.

HARDENING OF CRANE RAILS BY PLASMA DISCRETE-TIME SURFACE TREATMENT

Directory of Open Access Journals (Sweden)

S. S. Samotugin

2017-01-01

Full Text Available Crane wheels and rails are subjected to intensive wear in the process of operation. Therefore, improvement of these components’ performance can be considered a task of high importance. A promising direction in this regard is surface treatment by highly concentrated energy flows such as laser beams or plasma jets. This thesis suggests that the use of gradient plasma surface treatment can improve the performance of crane rails. A research was conducted, according to which hardened zones were deposited on crane rails under different treatment modes. Microhardness was measured both at the surface and in depth using custom-made microsections. The article includes the results of study of plasma surface hardening effects on wear resistance of crane rails. Change of plasma surface treatment parameters (current, plasma torch movement speed, argon gas flow rate allows for desired steel hardness and structure, while the choice of optimal location for hardened zones makes it possible to significantly improve wear resistance and crack resistance. As a result of plasma surface hardening, the fine-grained martensite structure is obtained with mainly lamellar morphology and higher hardness rate compared toinduction hardening or overlaying. Wear test of carbon steels revealed that plasma surfacing reduces abrasive wear rate compared to the irinitial state by 2 to 3 times. Enough sharp boundary between hardened and non-hardened portions has a positive effect on the performance of parts under dynamic loads, contributing to the inhibition of cracks during the transition from solid to a soft metal. For carbon and low alloy rail steels, the properties achieved by plasma surface hardening can effectively replace induction hardening or overlaying.The mode range for plasma surface treatment that allow sobtaining a surface layer with certain operating properties has been determined.

A procedure for the hardening of materials

International Nuclear Information System (INIS)

Dearnaley, G.

1984-01-01

A method of hardening metals or ceramics which have fcc, bcc or hcp structures in which two species of differing atomic radii are introduced into the material to be hardened. One species is of a size such that it can diffuse through the lattice normally. The other is of a size such that it can diffuse readily only along dislocations. Ion bombardment is the preferred method of introducing the species with different atomic radii. The material to be hardened is subjected to heat and plastic deformation so as to cause a large number of dislocations with jogs. The species meet at the jogs where they interact and are trapped and set up strain fields which prevent further deformation of the material. (author)

An Anisotropic Hardening Model for Springback Prediction

Science.gov (United States)

Zeng, Danielle; Xia, Z. Cedric

2005-08-01

As more Advanced High-Strength Steels (AHSS) are heavily used for automotive body structures and closures panels, accurate springback prediction for these components becomes more challenging because of their rapid hardening characteristics and ability to sustain even higher stresses. In this paper, a modified Mroz hardening model is proposed to capture realistic Bauschinger effect at reverse loading, such as when material passes through die radii or drawbead during sheet metal forming process. This model accounts for material anisotropic yield surface and nonlinear isotropic/kinematic hardening behavior. Material tension/compression test data are used to accurately represent Bauschinger effect. The effectiveness of the model is demonstrated by comparison of numerical and experimental springback results for a DP600 straight U-channel test.

An Anisotropic Hardening Model for Springback Prediction

International Nuclear Information System (INIS)

Zeng, Danielle; Xia, Z. Cedric

2005-01-01

As more Advanced High-Strength Steels (AHSS) are heavily used for automotive body structures and closures panels, accurate springback prediction for these components becomes more challenging because of their rapid hardening characteristics and ability to sustain even higher stresses. In this paper, a modified Mroz hardening model is proposed to capture realistic Bauschinger effect at reverse loading, such as when material passes through die radii or drawbead during sheet metal forming process. This model accounts for material anisotropic yield surface and nonlinear isotropic/kinematic hardening behavior. Material tension/compression test data are used to accurately represent Bauschinger effect. The effectiveness of the model is demonstrated by comparison of numerical and experimental springback results for a DP600 straight U-channel test

A COTS-based single board radiation-hardened computer for space applications

International Nuclear Information System (INIS)

Stewart, S.; Hillman, R.; Layton, P.; Krawzsenek, D.

1999-01-01

There is great community interest in the ability to use COTS (Commercial-Off-The-Shelf) technology in radiation environments. Space Electronics, Inc. has developed a high performance COTS-based radiation hardened computer. COTS approaches were selected for both hardware and software. Through parts testing, selection and packaging, all requirements have been met without parts or process development. Reliability, total ionizing dose and single event performance are attractive. The characteristics, performance and radiation resistance of the single board computer will be presented. (authors)

Novel circuits for radiation hardened memories

International Nuclear Information System (INIS)

Haraszti, T.P.; Mento, R.P.; Moyer, N.E.; Grant, W.M.

1992-01-01

This paper reports on implementation of large storage semiconductor memories which combine radiation hardness with high packing density, operational speed, and low power dissipation and require both hardened circuit and hardened process technologies. Novel circuits, including orthogonal shuffle type of write-read arrays, error correction by weighted bidirectional codes and associative iterative repair circuits, are proposed for significant improvements of SRAMs' immunity against the effects of total dose and cosmic particle impacts. The implementation of the proposed circuit resulted in fault-tolerant 40-Mbit and 10-Mbit monolithic memories featuring a data rate of 120 MHz and power dissipation of 880 mW. These experimental serial-parallel memories were fabricated with a nonhardened standard CMOS processing technology, yet provided a total dose hardness of 1 Mrad and a projected SEU rate of 1 x 10 - 12 error/bit/day. Using radiation hardened processing improvements by factors of 10 to 100 are predicted in both total dose hardness and SEU rate

Euler European Libraries and Electronic Resources in Mathematical Sciences

CERN Document Server

The Euler Project. Karlsruhe

The European Libraries and Electronic Resources (EULER) Project in Mathematical Sciences provides the EulerService site for searching out "mathematical resources such as books, pre-prints, web-pages, abstracts, proceedings, serials, technical reports preprints) and NetLab (for Internet resources), this outstanding engine is capable of simple, full, and refined searches. It also offers a browse option, which responds to entries in the author, keyword, and title fields. Further information about the Project is provided at the EULER homepage.

ANISOTROPIC STRAIN-HARDENING IN POLYCRYSTALLINE COPPER AND ALUMINUM

NARCIS (Netherlands)

HESS, F

1993-01-01

A new viscoplastic model for the plastic stress-strain behaviour of f.c.c. metals is presented. In this model the strain hardening results from increasing dislocation densities. The observed stagnation of strain hardening after strain reversals is explained by a lowering of the increase in

Surface hardening of titanium alloys with melting depth controlled by heat sink

Science.gov (United States)

Oden, Laurance L.; Turner, Paul C.

1995-01-01

A process for forming a hard surface coating on titanium alloys includes providing a piece of material containing titanium having at least a portion of one surface to be hardened. The piece having a portion of a surface to be hardened is contacted on the backside by a suitable heat sink such that the melting depth of said surface to be hardened may be controlled. A hardening material is then deposited as a slurry. Alternate methods of deposition include flame, arc, or plasma spraying, electrodeposition, vapor deposition, or any other deposition method known by those skilled in the art. The surface to be hardened is then selectively melted to the desired depth, dependent on the desired coating thickness, such that a molten pool is formed of the piece surface and the deposited hardening material. Upon cooling a hardened surface is formed.

Effects of Electronic Information Resources Skills Training for Lecturers on Pedagogical Practices and Research Productivity

Science.gov (United States)

Bhukuvhani, Crispen; Chiparausha, Blessing; Zuvalinyenga, Dorcas

2012-01-01

Lecturers use various electronic resources at different frequencies. The university library's information literacy skills workshops and seminars are the main sources of knowledge of accessing electronic resources. The use of electronic resources can be said to have positively affected lecturers' pedagogical practices and their work in general. The…

EFFECT OF HARDENING TIME ON DEFORMATION-STRENGTH INDICATORS OF CONCRETE FOR INJECTION WITH A TWO-STAGE EXPANSION DURING HARDENING IN WATER

Directory of Open Access Journals (Sweden)

Tatjana N. Zhilnikova

2017-01-01

Full Text Available Abstract. Objectives Concretes for injection with a two-stage expansion are a kind of selfstressing concrete obtained with the use of self-stressing cement.The aim of the work is to study the influence of the duration of aging on the porosity, strength and self-stress of concrete hardening in water, depending on the expansion value at the first stage. At the first stage, the compacted concrete mixture is expanded to ensure complete filling of the formwork space. At the second stage, the hardening concrete expands due to the formation of an increased amount of ettringite. This process is prolonged in time, with the amount of self-stress and strength dependant on the conditions of hardening. Methods  Experimental evaluation of self-stress, strength and porosity of concretes that are permanently hardened in water, under air-moist and air-dry conditions after different expansion at the first stage. The self-stress of cement stone is the result of superposition of two processes: the hardening of the structure due to hydration of silicates and its expansion as a result of hydration of calcium aluminates with the subsequent formation of ettringite. The magnitude of self-stress is determined by the ratio of these two processes. The self-stress of the cement stone changes in a manner similar to the change in its expansion. The stabilisation of expansion is accompanied by stabilisation of self-stress of cement stone. Results  The relationship of self-stress, strength and porosity of concrete for injection with a two-stage expansion on the duration and humidity conditions of hardening, taking into account the conditions of deformation limitation at the first stage, is revealed. Conclusion During prolonged hardening in an aqueous medium, self-stresses are reduced up to 25% with the exception of expansion at the first stage and up to 20% with an increase in volume up to 5% at the first stage. The increase in compressive strength is up to 28% relative to

Application of a three-feature dispersed-barrier hardening model to neutron-irradiated Fe-Cr model alloys

Science.gov (United States)

Bergner, F.; Pareige, C.; Hernández-Mayoral, M.; Malerba, L.; Heintze, C.

2014-05-01

An attempt is made to quantify the contributions of different types of defect-solute clusters to the total irradiation-induced yield stress increase in neutron-irradiated (300 °C, 0.6 dpa), industrial-purity Fe-Cr model alloys (target Cr contents of 2.5, 5, 9 and 12 at.% Cr). Former work based on the application of transmission electron microscopy, atom probe tomography, and small-angle neutron scattering revealed the formation of dislocation loops, NiSiPCr-enriched clusters and α‧-phase particles, which act as obstacles to dislocation glide. The values of the dimensionless obstacle strength are estimated in the framework of a three-feature dispersed-barrier hardening model. Special attention is paid to the effect of measuring errors, experimental details and model details on the estimates. The three families of obstacles and the hardening model are well capable of reproducing the observed yield stress increase as a function of Cr content, suggesting that the nanostructural features identified experimentally are the main, if not the only, causes of irradiation hardening in these model alloys.

Investigation of hardening behavior in Xe ion-irradiated Zr–1Nb

Energy Technology Data Exchange (ETDEWEB)

Yan, Chunguang [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); China Institute of Atomic Energy, Beijing 102413 (China); Wang, Rongshan [Life Management Technology Center, Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Dai, Xianyuan [Fujian Fuqing Nuclear Power Co., Ltd., Fuqing 350318 (China); Wang, Yanli, E-mail: wangyl@ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Xitao [Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083 (China); Bai, Guanghai; Zhang, Yanwei [Life Management Technology Center, Suzhou Nuclear Power Research Institute, Suzhou 215004 (China)

2016-05-15

Irradiation hardening behavior of Zr–1Nb was examined by nanoindentation, slow positron annihilation technique, transmission electron microscopy and coplanar extremely asymmetric X-ray diffraction technique. Samples were irradiated at a dose rate of 2.78 × 10{sup −4} dpa/s to peak doses of 0.15, 0.5, 1.5 and 2.5 dpa with 6.37 MeV Xe{sup 26+} ion beam at room temperature. The increase in hardness as a function of dose followed a power law expression with the exponent of 0.46. With increasing irradiation dose, more mono-, di- and trivacancies were induced, but their concentration remained constant once formed due to the equilibrium between the formation and recombination of vacancy type clusters during irradiation. Meanwhile, the dislocation loops were also introduced and their linear density increased with dose. The dislocation loops played an important role in the irradiation hardening behavior. But the exact contribution of each microstructural components to the overall hardness still needs further study.

Dislocation Starvation and Exhaustion Hardening in Mo-alloy Nanofibers

Energy Technology Data Exchange (ETDEWEB)

Chisholm, Claire [University of California, Berkeley & LBNL; Bei, Hongbin [ORNL; Lowry, M. B. [University of California, Berkeley; Oh, Jason [Hysitron, Inc., MN; Asif, S.A. Syed [Hysitron, Inc., MN; Warren, O. [Hysitron, Inc., MN; Shan, Zhiwei [Xi' an Jiaotong University, China & Hysitron, Inc., MN; George, Easo P [ORNL; Minor, Andrew [University of California, Berkeley & LBNL

2012-01-01

The evolution of defects in Mo alloy nanofibers with initial dislocation densities ranging from 0 to 1.6 1014 m2 were studied using an in situ push-to-pull device in conjunction with a nanoindenter in a transmission electron microscope. Digital image correlation was used to determine stress and strain in local areas of deformation. When they had no initial dislocations the Mo alloy nanofibers suffered sudden catastrophic elongation following elastic deformation to ultrahigh stresses. At the other extreme fibers with a high dislocation density underwent sustained homogeneous deformation after yielding at much lower stresses. Between these two extremes nanofibers with intermediate dislocation densities demonstrated a clear exhaustion hardening behavior, where the progressive exhaustion of dislocations and dislocation sources increases the stress required to drive plasticity. This is consistent with the idea that mechanical size effects ( smaller is stronger ) are due to the fact that nanostructures usually have fewer defects that can operate at lower stresses. By monitoring the evolution of stress locally we find that exhaustion hardening causes the stress in the nanofibers to surpass the critical stress predicted for self-multiplication, supporting a plasticity mechanism that has been hypothesized to account for the rapid strain softening observed in nanoscale bcc materials at high stresses.

Enhanced bake-hardening response of an Al–Mg–Si–Cu alloy with Zn addition

Energy Technology Data Exchange (ETDEWEB)

Guo, M.X., E-mail: mingxingguo@skl.ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Sha, G., E-mail: gang.sha@njust.edu.cn [School of Materials Science and Engineering, Nanjing University of Science and Technology, Jiangsu 210094 (China); Cao, L.Y. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Liu, W.Q. [Key Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Zhang, J.S.; Zhuang, L.Z. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

2015-07-15

This study reports that Zn addition greatly enhances the bake-hardening response of an Al–Mg–Si–Cu alloy. The pre-aged alloy exhibits a high strength increment of 135 MPa after paint baking. Differential scanning calorimetry, atom probe tomography and high-resolution transmission electron microscopy reveal that Zn addition and pre-aging have significant effects on the solute nanostructure formation. Zn atoms partition into solute clusters/GP zones, and reduce the activation energy of β” precipitation in the alloy. - Highlights: • Zn addition can improve the bake-hardening response of an Al–Mg–Si–Cu alloy. • Zn addition can stabilize the solute clusters/GP zones from dissolution. • Zn addition can reduce the size of clusters formed in the pre-aging treatment. • Zn partitioned into solute clusters/GP zones and β” in the Zn-containing Al alloy.

Radiation hardening of semiconductor parts

International Nuclear Information System (INIS)

Anon.

1993-01-01

This chapter is an overview of total-ionizing-dose and single-event hardening techniques and should be used as a guide to a range of research publications. It should be stressed that there is no clear and simple route to a radiation-tolerant silicon integrated circuit. What works for one fabrication process may not work for another, and there are many complex interactions within individual processes and designs. The authors have attempted to highlight the most important factors and those process changes which should bring improved hardness. The main point is that radiation-hardening as a procedure must be approached in a methodical fashion and with a good understanding of the response mechanisms involved

Energetic model of metal hardening

Directory of Open Access Journals (Sweden)

Ignatova O.N.

2011-01-01

Full Text Available Based on Bailey hypothesis on the link between strain hardening and elastic lattice defect energy this paper suggests a shear strength energetic model that takes into consideration plastic strain intensity and rate as well as softening related to temperature annealing and dislocation annihilation. Metal strain hardening was demonstrated to be determined only by elastic strain energy related to the energy of accumulated defects. It is anticipated that accumulation of the elastic energy of defects is governed by plastic work. The suggested model has a reasonable agreement with the available experimental data for copper up to P = 70 GPa , for aluminum up to P = 10 GPa and for tantalum up to P = 20 GPa.

Age-hardening and related phase transformation in an experimental Ag-Cu-Pd-Au alloy

International Nuclear Information System (INIS)

Seol, Hyo-Joung; Lee, Doung-Hun; Lee, Hee-Kyung; Takada, Yukyo; Okuno, Osamu; Kwon, Yong Hoon; Kim, Hyung-Il

2006-01-01

The age-hardening behaviour, phase transformation and related microstructural changes of an experimental Ag-Cu-Pd-Au alloy were examined by means of hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and electron probe microanalysis (EPMA). The specimen alloy showed apparent age-hardenability at the aging temperatures of 350 deg. C and 400 deg. C. By aging the solution-treated specimen at 400 deg. C, two phases of the Ag-rich α 1 phase and the Pd-containing Cu-rich α 2 phase were transformed into four phases of the Ag-rich α 1 ' phase, the Cu-rich α 2 ' phase, the CsCl-type CuPd phase and the AuCu(I) ordered phase. Microstructure of the solution-treated specimen consisted of the Ag-rich α 1 matrix, Cu-rich α 2 particle-like structures of various sizes and the lamellar structure of the α 1 and α 2 phases. When the peak hardness was obtained, the very fine lamellar structure consisting of the Ag-rich α 1 ' and Cu-rich α 2 ' phases was newly formed in the matrix. By further aging, the very fine lamellar structure grew and coarsened apparently, and the matrix was covered with the coarsened lamellar structure. The hardness increase was considered to be caused mainly by the diffusion and precipitation of Cu from the Ag-rich α 1 matrix, and the hardness decrease in the latter stage of age-hardening process was caused by the coarsening of the very fine lamellar structure. The CsCl-type CuPd phase and the AuCu(I) ordered phase did not contribute to the hardness increase

Nonlinear kinematic hardening under non-proportional loading

International Nuclear Information System (INIS)

Ottosen, N.S.

1979-07-01

Within the framework of conventional plasticity theory, it is first determined under which conditions Melan-Prager's and Ziegler's kinematic hardening rules result in identical material behaviour. Next, assuming initial isotropy and adopting the von Mises yield criterion, a nonlinear kinematic hardening function is proposed for prediction of metal behaviour. The model assumes that hardening at a specific stress point depends on the direction of the new incremental loading. Hereby a realistic response is obtained for general reversed loading, and a smooth behaviour is assured, even when loading deviates more and more from proportional loading and ultimately results in reversed loading. The predictions of the proposed model for non-proportional loading under plane stress conditions are compared with those of the classical linear kinematic model, the isotropic model and with published experimental data. Finally, the limitations of the proposaed model are discussed. (author)

Hardening cookies in web-based systems for better system integrity

International Nuclear Information System (INIS)

Mohamad Safuan Sulaiman; Mohd Dzul Aiman Aslan; Saaidi Ismail; Abdul Aziz Mohd Ramli; Abdul Muin Abdul Rahman; Siti Nurbahyah Hamdan; Norlelawati Hashimuddin; Sufian Norazam Mohamed Aris

2012-01-01

IT Center (ITC) as technical support and provider for most of web-based systems in Nuclear Malaysia has conducted a study to investigate cookie vulnerability in a system for better integrity. A part of the result has found that cookies in a web-based system in Nuclear Malaysia can be easily manipulated. The main objective of the study is to harden the vulnerability of the cookies. Two levels of security procedures have been used and enforced which consist of 1) Penetration test (Pen Test) 2) Hardening procedure. In one of the system, study has found that 121 attempts threats have been detected after the hardening enforcement from 23 March till 20 September 2012. At this stage, it can be concluded that cookie vulnerability in the system has been hardened and integrity has been assured after the enforcement. This paper describes in detail the penetration and hardening process of cookie vulnerability for better supporting web-based system in Nuclear Malaysia. (author)

Electronic Commerce Resource Centers. An Industry--University Partnership.

Science.gov (United States)

Gulledge, Thomas R.; Sommer, Rainer; Tarimcilar, M. Murat

1999-01-01

Electronic Commerce Resource Centers focus on transferring emerging technologies to small businesses through university/industry partnerships. Successful implementation hinges on a strategic operating plan, creation of measurable value for customers, investment in customer-targeted training, and measurement of performance outputs. (SK)

Hardening mechanisms of spray formed Al-Zn-Mg-Cu alloys with scandium and other elemental additions

International Nuclear Information System (INIS)

Sharma, M.M.; Amateau, M.F.; Eden, T.J.

2006-01-01

The hardening mechanisms in spray formed Al-Zn-Mg-Cu alloys with additions of chromium, zinc and scandium were studied. The microstructure of the spray formed alloys was analyzed by transmission electron microscopy. A range of tensile strengths were achieved, and varied based on elemental additions, and second phase particle strengthening. To explain the significantly higher strength in one alloy with scandium, theoretical results due to the yield stress of Al-Zn-Mg-Cu alloys as a function of volume fraction and precipitate particle size, were compared to experimental data. Both the possibilities of coherency and order strengthening are examined. The significant additional hardening achieved in the alloy with scandium is attributed to small ordered particles of Al 3 Sc, which precipitated during aging

Microstructural evolution, mechanical properties, and strain hardening behavior of ultrafine grained commercial pure copper during the accumulative roll bonding process

Energy Technology Data Exchange (ETDEWEB)

Fattah-alhosseini, A. [Department of Materials Engineering, Bu-Ali Sina University, Hamedan 65178-38695 (Iran, Islamic Republic of); Imantalab, O., E-mail: o.imantalab@gmail.com [Department of Materials Engineering, Bu-Ali Sina University, Hamedan 65178-38695 (Iran, Islamic Republic of); Mazaheri, Y. [Department of Materials Engineering, Bu-Ali Sina University, Hamedan 65178-38695 (Iran, Islamic Republic of); Keshavarz, M.K. [Department of Engineering Physics, Polytechnique Montreal, Montreal (Canada)

2016-01-05

In this study, the microstructural evolution, mechanical properties, and strain hardening behavior of commercial pure copper processed by the accumulative roll bonding (ARB) were investigated. Transmission electron microscopy (TEM) micrographs and atomic force microscopy (AFM) images indicated that with increasing the number of ARB cycles, the grain size of samples decreased. An Ultrafine grained (UFG) structure with an average grain size of about 200 nm was achieved after four cycles of ARB. The yield and ultimate tensile strength of pure copper with the UFG microstructure was reached about 360 MPa and 396 MPa (about 400% and 100% higher than that of the annealed state), respectively. All ARB-processed copper samples showed lower strain hardening exponent in comparison with the annealed state. Moreover, the strain hardening rate increased with increasing ARB cycles up to 3 cycles and then decreased.

Microstructural evolution, mechanical properties, and strain hardening behavior of ultrafine grained commercial pure copper during the accumulative roll bonding process

International Nuclear Information System (INIS)

Fattah-alhosseini, A.; Imantalab, O.; Mazaheri, Y.; Keshavarz, M.K.

2016-01-01

In this study, the microstructural evolution, mechanical properties, and strain hardening behavior of commercial pure copper processed by the accumulative roll bonding (ARB) were investigated. Transmission electron microscopy (TEM) micrographs and atomic force microscopy (AFM) images indicated that with increasing the number of ARB cycles, the grain size of samples decreased. An Ultrafine grained (UFG) structure with an average grain size of about 200 nm was achieved after four cycles of ARB. The yield and ultimate tensile strength of pure copper with the UFG microstructure was reached about 360 MPa and 396 MPa (about 400% and 100% higher than that of the annealed state), respectively. All ARB-processed copper samples showed lower strain hardening exponent in comparison with the annealed state. Moreover, the strain hardening rate increased with increasing ARB cycles up to 3 cycles and then decreased.

The effect of Sc additions on the microstructure and age hardening behaviour of as cast Al–Sc alloys

International Nuclear Information System (INIS)

Costa, S.; Puga, H.; Barbosa, J.; Pinto, A.M.P.

2012-01-01

Highlights: ► The Sc effect on the microstructure and ageing behaviour of Al–Sc alloys is studied. ► Cast into copper mould allows the elimination of solution heat treatment. ► Directly aged as cast alloys exhibits higher hardness and precipitation kinetics. ► Sc addition and optimised ageing result in an increase in Al–Sc mechanical properties. -- Abstract: The grain refinement effect and the ageing behaviour of Al–0.5 wt.% Sc, Al–0.7 wt.% Sc, and Al–1 wt.% Sc alloys are studied on the basis of optic microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) observations and hardness measurements. In Al–Sc alloys the higher grain refinement is observed for Sc contents greater than 0.5 wt.% accompanied by a notorious morphology modification, from coarse columnar grains to a fine perfect equiaxed structure. The as cast structures are characterised by a rich supersaturated solid solution in Sc, that promotes a great age hardening response at 250 °C and 300 °C. The age hardening curves also demonstrate a low overageing kinetics for all the alloys. Although the higher Sc content in solid solution for the alloys with 0.7 and 1 wt.% Sc, the age hardening response of all the Al–Sc alloys remains similar. The direct age hardening response of the as cast Al–0.5 wt.% Sc is shown to be greater than the solutionised and age hardened alloy.

Spaceradiation effects on electronics

International Nuclear Information System (INIS)

Salminen, Arto.

1989-01-01

The failure mechanisms and radiation hardening of electronic devices in spaceborne environment are considered. Radiation hardened components and radiation shielding of electronics are described. Because of the radiation belts and particle radiation from the Sun, the near earth space is hostile to electronics. Besides cosmic radiation represents fully random failure source, against which redundant methods have to be applied. Failures caused by absorbed doses can be dealt with component selection, layout adjustment and addition of absorber. Prepairing for radiation damage presupposes the calculation of absorbed doses and SEU-cross sections from flight parameters. Thus the expected lifetime for spacecraft can be estimated. The above observations belong to the domain of normal routine operation in space electronic engineering and product assurance, which has a crucial meaning in space technology. Devices are to operate years without failure in demanding conditions. The reliable products are result of careful consideration of space environment from the beginning of device design. This applies especially to component selection and circuit design

Formulating the strength factor α for improved predictability of radiation hardening

Energy Technology Data Exchange (ETDEWEB)

Tan, L., E-mail: tanl@ornl.gov; Busby, J.T.

2015-10-15

Analytical equations were developed to calculate the strength factors of precipitates, Frank loops, and cavities in austenitic alloys, which strongly depend on barrier type, size, geometry and density, as well as temperature. Calculated strength factors were successfully used to estimate radiation hardening using the broadly employed dispersed barrier-hardening model, leading to good agreement with experimentally measured hardening in neutron-irradiated type 304 and 316 stainless steel variants. The formulated strength factor provides a route for more reliable hardening predictions and can be easily incorporated into component simulations and design.

Stage IV work-hardening related to disorientations in dislocation structures

DEFF Research Database (Denmark)

Pantleon, W.

2004-01-01

The effect of deformation-induced disorientations on the work-hardening of metals is modelled based on dislocation dynamics. Essentially, Kocks’ dislocation model describing stage III hardening is extended to stage IV by incorporation of excess dislocations related to the disorientations....... Disorientations evolving from purely statistical reasons — leading to a square root dependence of the average disorientation angle on strain — affect the initial work-hardening rate (and the saturation stress) of stage III only slightly. On the other hand, deterministic contributions to the development...... of disorientations, as differences in the activated slip systems across boundaries, cause a linear increase of the flow stress at large strains. Such a constant work-hardening rate is characteristic for stage IV....

Scintillation-Hardened GPS Receiver

Science.gov (United States)

Stephens, Donald R.

2015-01-01

CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

Extracting material response from simple mechanical tests on hardening-softening-hardening viscoplastic solids

Science.gov (United States)

Mohan, Nisha

Compliant foams are usually characterized by a wide range of desirable mechanical properties. These properties include viscoelasticity at different temperatures, energy absorption, recoverability under cyclic loading, impact resistance, and thermal, electrical, acoustic and radiation-resistance. Some foams contain nano-sized features and are used in small-scale devices. This implies that the characteristic dimensions of foams span multiple length scales, rendering modeling their mechanical properties difficult. Continuum mechanics-based models capture some salient experimental features like the linear elastic regime, followed by non-linear plateau stress regime. However, they lack mesostructural physical details. This makes them incapable of accurately predicting local peaks in stress and strain distributions, which significantly affect the deformation paths. Atomistic methods are capable of capturing the physical origins of deformation at smaller scales, but suffer from impractical computational intensity. Capturing deformation at the so-called meso-scale, which is capable of describing the phenomenon at a continuum level, but with some physical insights, requires developing new theoretical approaches. A fundamental question that motivates the modeling of foams is `how to extract the intrinsic material response from simple mechanical test data, such as stress vs. strain response?' A 3D model was developed to simulate the mechanical response of foam-type materials. The novelty of this model includes unique features such as the hardening-softening-hardening material response, strain rate-dependence, and plastically compressible solids with plastic non-normality. Suggestive links from atomistic simulations of foams were borrowed to formulate a physically informed hardening material input function. Motivated by a model that qualitatively captured the response of foam-type vertically aligned carbon nanotube (VACNT) pillars under uniaxial compression [2011,"Analysis of

Development of Bake Hardening Effect by Plastic Deformation and Annealing Conditions

Directory of Open Access Journals (Sweden)

Kvačkaj, T.

2006-01-01

Full Text Available The paper deals with the classification of steel sheets for automotives industry on the basis of strength and structural characteristics. Experimental works were aimed to obtain the best possible strengthening parameters as well as work hardening and solid solution ferrite hardening, which are the result of thermal activation of interstitial carbon atoms during paint-baking of auto body. Hardening process coming from interstitial atoms is realized as two-step process. The first step is BH (bake hardening effect achieved by interaction of interstitial atoms with dislocations. The Cottrels atmosphere is obtained. The second step of BH effect is to produced the hardening from precipitation of the carbon atoms in e-carbides, or formation of Fe32C4 carbides. WH (work hardening effect is obtained as dislocation hardening from plastic deformations during sheet deep drawing. Experimental works were aimed at as to achieve such plastic material properties after cold rolling, annealing and skin-pass rolling, which would be able to classify the material ZStE220BH into the drawing categories at the level of DQ – DDQ. As resulting from the experimental results, the optimal treatment conditions for the maximal sum (WH+BH = 86 MPa are as follows: total cold rolling deformation ecold = 65 %, annealing temperature Tanneal. = 700 °C.

The maraging steel corrosion properties with hardening of different kinds after double aging

Directory of Open Access Journals (Sweden)

L. V. Tarasenko

2014-01-01

Full Text Available The paper proposes to use high-strength corrosion-resistant maraging steels, which were developed for aircraft industry instead of carbon steel with coating to improve operation properties of the forcemeasuring resilient member in electronic strain-gauge balance.It examines the possibility to apply the martensitic-aging steels of Fe-Cr-Ni-Mo-Ti (ЭП678 and Fe-Cr-Ni-Mo-Cu-Nb (ЭП817 alloying systems. It was shown, that a traditional heat strain-hardening treatment including hardening and overageing of this steels provides combination of durability viscosity and corrosion- resistance, but at the same time it increases nonelastic effects and lowers the limit of elasticity because of reversing austenite formation. In this connection, it was proposed to use hardening with double aging i.e. main and low-temperature aging with no austenite formation as heat strainhardening treatment of steels for force-measuring resilient member. The goal of this work was to study the influence of double aging on the structure and properties of ЭП678 (06Х14Н6Д2МБТ and ЭП817 (03Х111Н10М2Т steels.The modes of double aging for ЭП817 steel were conformed to 4500С + 400 0С and 475 0С+ 400 0С, for ЭП678 steel – 530 0С + 500 0С. The structure and properties of hardened steels after main and double aging were compared.Metallographic analysis of samples after electrolytic etching was conducted with Leitz Metallovert microscope while the CamScan 4DV raster electronic microscope was used for Microroentgen-spectral analysis. The quantity of austenite was controlled with computerized setting DRON-4, the hardness was measured with ТК-2М instrument, corrosion-resistance was estimated with polarized curves, which were taken using a П-5848 potentiostat.The conducted research has shown, that double aging causes the additional hardening of steels due to disintegration of martensite and formation of dispersed Cu – corpuscles in ЭП817 steel and of Ni3Ti

Application of submerged induction hardening; Ekichu koshuha yakiire no jitsuyoka

Energy Technology Data Exchange (ETDEWEB)

Nishimori, Y; Nagai, Y; Amii, Y [Mazda Motor Corp., Hiroshima (Japan); Tanaka, Y [Netsuren Co. Ltd., Tokyo (Japan); Mizuma, T [Toyo Advanced Technologies Co. Ltd., Hiroshima (Japan)

1997-10-01

As a cost-cutting measure, the linerless diesel engine was adopted by applying submerged induction hardening process which can harden partial inner surface of cylinder block bore. In applying this process, (1) development of induction coil which can form any shape of quenched pattern and (2) the development of machining technology which can hone precisely the distorted bore after quenching, were important. With these improvements, submerged Induction hardening was made practical. 1 ref., 11 figs.

Changes in Structural Characteristics of Hypoeutectic Al-Si Cast Alloy after Age Hardening

Directory of Open Access Journals (Sweden)

Lenka HURTALOVÁ

2012-09-01

Full Text Available The contribution describes influence of the age-hardening consist of solution treatment at 515 °C with holding time 4 hours, water quenching at 40 °C and artificial aging at different temperature 150 °C, 170 °C and 190 °C with different holding time 2, 4, 8, 16 and 32 hours on mechanical properties (tensile strength and Brinell hardness and changes in morphology of eutectic Si, Fe-rich and Cu-rich intermetallic phases in secondary (recycled AlSi9Cu3 cast alloy. A combination of different analytical techniques (light microscopy upon black-white and colour etching, scanning electron microscopy (SEM upon deep etching and energy dispersive X-ray analysis (EDX were therefore been used for the identification of the various phases. Quantitative study of changes in morphology of eutectic Si, Cu-rich and Fe-rich phases was carried out using Image Analyzer software NIS-Elements. Mechanical properties were measured in line with EN ISO. Age-hardening led to changes in microstructure include the spheroidization and coarsening of eutectic silicon, gradual disintegration, shortening and thinning of Fe- rich intermetallic phases, the dissolution of precipitates and the precipitation of finer hardening phase (Al2Cu further increase in the hardness and tensile strength in the alloy.DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2430

Plastic limit pressure of spherical vessels with combined hardening involving large deformation

International Nuclear Information System (INIS)

Leu, S.-Y.; Liao, K.-C.; Lin, Y.-C.

2014-01-01

The paper aims to investigate plastic limit pressure of spherical vessels of nonlinear combined isotropic/kinematic hardening materials. The Armstrong-Frederick kinematic hardening model is adopted and the Voce hardening law is incorporated for isotropic hardening behavior. Analytically, we extend sequential limit analysis to deal with combined isotropic/kinematic hardening materials. Further, exact solutions of plastic limit pressure were developed analytically by conducting both static and kinematic limit analysis. The onset of instability was also derived and solved iteratively by Newton's method. Numerically, elastic–plastic analysis is also performed by the commercial finite-element code ABAQUS incorporated with the user subroutine UMAT implemented with user materials of combined hardening. Finally, the problem formulation and the solution derivations presented here are validated by a very good agreement between the numerical results of exact solutions and the results of elastic–plastic finite-element analysis by ABAQUS. -- Highlights: • Sequential limit analysis is extended to consider combined hardening. • Exact solutions of plastic limit pressure are developed. • The onset of instability of a spherical vessel is derived and solved numerically

Process design of press hardening with gradient material property influence

International Nuclear Information System (INIS)

Neugebauer, R.; Schieck, F.; Rautenstrauch, A.

2011-01-01

Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press-hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.

Kinematic Hardening: Characterization, Modeling and Impact on Springback Prediction

International Nuclear Information System (INIS)

Alves, J. L.; Bouvier, S.; Jomaa, M.; Billardon, R.; Oliveira, M. C.; Menezes, L. F.

2007-01-01

The constitutive modeling of the materials' mechanical behavior, usually carried out using a phenomenological constitutive model, i.e., a yield criterion associated to the isotropic and kinematic hardening laws, is of paramount importance in the FEM simulation of the sheet metal forming processes, as well as in the springback prediction. Among others, the kinematic behavior of the yield surface plays an essential role, since it is indispensable to describe the Bauschinger effect, i.e., the materials' answer to the multiple tension-compression cycles to which material points are submitted during the forming process. Several laws are usually used to model and describe the kinematic hardening, namely: a) the Prager's law, which describes a linear evolution of the kinematic hardening with the plastic strain rate tensor b) the Frederick-Armstrong non-linear kinematic hardening, basically a non-linear law with saturation; and c) a more advanced physically-based law, similar to the previous one but sensitive to the strain path changes. In the present paper a mixed kinematic hardening law (linear + non-linear behavior) is proposed and its implementation into a static fully-implicit FE code is described. The material parameters identification for sheet metals using different strategies, and the classical Bauschinger loading tests (i.e. in-plane forward and reverse monotonic loading), are addressed, and their impact on springback prediction evaluated. Some numerical results concerning the springback prediction of the Numisheet'05 Benchmark no. 3 are briefly presented to emphasize the importance of a correct modeling and identification of the kinematic hardening behavior

Effect of alloying element partitioning on ferrite hardening in a low alloy ferrite-martensite dual phase steel

Energy Technology Data Exchange (ETDEWEB)

Ebrahimian, A., E-mail: ebrahimiana@yahoo.com; Ghasemi Banadkouki, S.S.

2016-11-20

In this paper, the effect of carbon and other alloying elements partitioning on ferrite hardening behavior were studied in details using a low alloy AISI4340 ferrite-martensite dual phase (DP) steel. To do so, various re-austenitised samples at 860 °C for 60 min were isothermally heated at 650 °C from 3 to 60 min and then water–quenched to obtain the final ferrite-martensite DP microstructures containing different ferrite and martensite volume fractions. Light and electron microscopic observations were supplemented with electron dispersive spectroscopy (EDS) and nanoindentation tests to explore the localized compositional and hardening variations within ferrite grains in DP samples. The experimental results showed that the ferrite hardness was varied with progress of austenite to ferrite phase transformation in DP samples. In the case of a particular ferrite grain in a particular DP sample, despite a homogeneous distribution of carbon concentration, the ferrite hardness was significantly increased by increasing distance from the central location toward the interfacial α/γ areas. Beside a considerable influence of martensitic phase transformation on adjacent ferrite hardness, these results were rationalized in part to the significant level of Cr and Mo pile-up at α/γ interfaces leading to higher solid solution hardening effect of these regions. The reduction of potential energy developed by attractive interaction between C-Cr and C-Mo couples toward the carbon enriched prior austenite areas were the dominating driving force for pile-up segregation.

Computer modelling of age hardening for cast aluminium alloys

International Nuclear Information System (INIS)

Wu, Linda; Ferguson, W George

2009-01-01

Age hardening, or precipitation hardening, is one of the most widely adopted techniques for strengthening of aluminium alloys. Although various age hardening models have been developed for aluminium alloys, from the large volume of literature reviewed, it appears that the bulk of the research has been concentrated on wrought aluminium alloys, only a few of the established precipitation models have been applied to the casting aluminium alloys. In the present work, there are two modelling methods that have been developed and applied to the casting aluminium alloys A356 and A357. One is based on the Shercliff-Ashby methodology to produce a process model, by which we mean a mathematical relationship between process variables (alloy composition, ageing temperature and time) and material properties (yield strength or hardness) through microstructure evolution (precipitate radius, volume fraction). The other method is based on the Kampmann and Wagner Numerical (KWN) model which deals with concomitant nucleation, growth and coarsening and is thus capable of predicting the full evolution of the particle size distribution and then a strength model is used to evaluate the resulting change in hardness or yield strength at room temperature by taking into account contributions from lattice resistance, solid solution hardening and precipitation hardening.

A project of X-ray hardening correction in large ICT

International Nuclear Information System (INIS)

Fang Min; Liu Yinong; Ni Jianping

2005-01-01

This paper presents a means of polychromatic X-ray beam hardening correction using a standard function to transform the polychromatic projection to monochromatic projection in large Industrial Computed Tomography (ICT). Some parameters were defined to verify the validity of hardening correction in large ICT and optimized. Simulated experiments were used to prove that without prior knowledge of the composition of the scanned object, the correction method using monochromatic reconstruction arithmetic could remove beam hardening artifact greatly. (authors)

Influence of Hardening Model on Weld Residual Stress Distribution

Energy Technology Data Exchange (ETDEWEB)

Mullins, Jonathan; Gunnars, Jens (Inspecta Technology AB, Stockholm (Sweden))

2009-06-15

This study is the third stage of a project sponsored by the Swedish Radiation Safety Authority (SSM) to improve the weld residual stress modelling procedures currently used in Sweden. The aim of this study was to determine which material hardening model gave the best agreement with experimentally measured weld residual stress distributions. Two girth weld geometries were considered: 19mm and 65mm thick girth welds with Rin/t ratios of 10.5 and 2.8, respectively. The FE solver ABAQUS Standard v6.5 was used for analysis. As a preliminary step some improvements were made to the welding simulation procedure used in part one of the project. First, monotonic stress strain curves and a mixed isotropic/kinematic hardening model were sourced from the literature for 316 stainless steel. Second, more detailed information was obtained regarding the geometry and welding sequence for the Case 1 weld (compared with phase 1 of this project). Following the preliminary step, welding simulations were conducted using isotropic, kinematic and mixed hardening models. The isotropic hardening model gave the best overall agreement with experimental measurements; it is therefore recommended for future use in welding simulations. The mixed hardening model gave good agreement for predictions of the hoop stress but tended to under estimate the magnitude of the axial stress. It must be noted that two different sources of data were used for the isotropic and mixed models in this study and this may have contributed to the discrepancy in predictions. When defining a mixed hardening model it is difficult to delineate the relative contributions of isotropic and kinematic hardening and for the model used it may be that a greater isotropic hardening component should have been specified. The kinematic hardening model consistently underestimated the magnitude of both the axial and hoop stress and is not recommended for use. Two sensitivity studies were also conducted. In the first the effect of using a

Influence of Hardening Model on Weld Residual Stress Distribution

International Nuclear Information System (INIS)

Mullins, Jonathan; Gunnars, Jens

2009-06-01

This study is the third stage of a project sponsored by the Swedish Radiation Safety Authority (SSM) to improve the weld residual stress modelling procedures currently used in Sweden. The aim of this study was to determine which material hardening model gave the best agreement with experimentally measured weld residual stress distributions. Two girth weld geometries were considered: 19mm and 65mm thick girth welds with Rin/t ratios of 10.5 and 2.8, respectively. The FE solver ABAQUS Standard v6.5 was used for analysis. As a preliminary step some improvements were made to the welding simulation procedure used in part one of the project. First, monotonic stress strain curves and a mixed isotropic/kinematic hardening model were sourced from the literature for 316 stainless steel. Second, more detailed information was obtained regarding the geometry and welding sequence for the Case 1 weld (compared with phase 1 of this project). Following the preliminary step, welding simulations were conducted using isotropic, kinematic and mixed hardening models. The isotropic hardening model gave the best overall agreement with experimental measurements; it is therefore recommended for future use in welding simulations. The mixed hardening model gave good agreement for predictions of the hoop stress but tended to under estimate the magnitude of the axial stress. It must be noted that two different sources of data were used for the isotropic and mixed models in this study and this may have contributed to the discrepancy in predictions. When defining a mixed hardening model it is difficult to delineate the relative contributions of isotropic and kinematic hardening and for the model used it may be that a greater isotropic hardening component should have been specified. The kinematic hardening model consistently underestimated the magnitude of both the axial and hoop stress and is not recommended for use. Two sensitivity studies were also conducted. In the first the effect of using a

The Natural Aging Effect on Hardenability in Al-Mg-Si: A Complex Interaction between Composition and Heat Treatment Parameters

Directory of Open Access Journals (Sweden)

Alex Poznak

2018-05-01

Full Text Available The technological relevance of Al-Mg-Si alloys has been rapidly growing over the last decade. Of particular interest to current and future applications is the problematic negative effect of prior natural aging on subsequent artificial age hardening. The influence of natural aging is dependent on both processing and compositional variables and has origins that are far from well-understood. This work examines the hardenability of 6000 series alloys under a wide range of conditions, paying particular attention to the natural aging effect. Experimental variables include alloy composition (Mg + Si, Mg/Si, cooling rate after solutionization, and duration of prior natural aging. Hardenability was evaluated with full hardness and conductivity aging curves for each condition, as well as select Transmission Electron Microscopy (TEM. Results are discussed based on the actions of naturally aged solute clusters during artificial aging. In particular, a complex interaction between vacancy concentration, cluster stability, and precipitation driving force is suggested.

Age-hardening and related phase transformation in an experimental Ag-Cu-Pd-Au alloy

Energy Technology Data Exchange (ETDEWEB)

Seol, Hyo-Joung [Department of Dental Materials, College of Dentistry, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of); Lee, Doung-Hun [Department of Dental Materials, College of Dentistry, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of); Lee, Hee-Kyung [Department of Dental Technology, Daegu Health College, San 7 Taejeon-dong, Buk-gu, Daegu 702-722 (Korea, Republic of); Takada, Yukyo [Division of Dental Biomaterials, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575 (Japan); Okuno, Osamu [Division of Dental Biomaterials, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575 (Japan); Kwon, Yong Hoon [Department of Dental Materials, College of Dentistry, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of); Kim, Hyung-Il [Department of Dental Materials, College of Dentistry, Pusan National University, 1-10 Ami-dong, Seo-gu, Pusan 602-739 (Korea, Republic of)]. E-mail: hilkim@pusan.ac.kr

2006-01-05

The age-hardening behaviour, phase transformation and related microstructural changes of an experimental Ag-Cu-Pd-Au alloy were examined by means of hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and electron probe microanalysis (EPMA). The specimen alloy showed apparent age-hardenability at the aging temperatures of 350 deg. C and 400 deg. C. By aging the solution-treated specimen at 400 deg. C, two phases of the Ag-rich {alpha}{sub 1} phase and the Pd-containing Cu-rich {alpha}{sub 2} phase were transformed into four phases of the Ag-rich {alpha}{sub 1}{sup '} phase, the Cu-rich {alpha}{sub 2}{sup '} phase, the CsCl-type CuPd phase and the AuCu(I) ordered phase. Microstructure of the solution-treated specimen consisted of the Ag-rich {alpha}{sub 1} matrix, Cu-rich {alpha}{sub 2} particle-like structures of various sizes and the lamellar structure of the {alpha}{sub 1} and {alpha}{sub 2} phases. When the peak hardness was obtained, the very fine lamellar structure consisting of the Ag-rich {alpha}{sub 1}{sup '} and Cu-rich {alpha}{sub 2}{sup '} phases was newly formed in the matrix. By further aging, the very fine lamellar structure grew and coarsened apparently, and the matrix was covered with the coarsened lamellar structure. The hardness increase was considered to be caused mainly by the diffusion and precipitation of Cu from the Ag-rich {alpha}{sub 1} matrix, and the hardness decrease in the latter stage of age-hardening process was caused by the coarsening of the very fine lamellar structure. The CsCl-type CuPd phase and the AuCu(I) ordered phase did not contribute to the hardness increase.

Concrete, hardened: Self desiccation

DEFF Research Database (Denmark)

Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard; Persson, Bertil

1999-01-01

The test method covers the determination of internal relative humidity (RH) in hardened concrete and cement mortar using RH instruments. The determination of RH is done on crushed samples of concrete or cement motar. This test method is only for measuring equipment which gives off or takes up...

Radiation-hardened CMOS/SOS LSI circuits

International Nuclear Information System (INIS)

Aubuchon, K.G.; Peterson, H.T.; Shumake, D.P.

1976-01-01

The recently developed technology for building radiation-hardened CMOS/SOS devices has now been applied to the fabrication of LSI circuits. This paper describes and presents results on three different circuits: an 8-bit adder/subtractor (Al gate), a 256-bit shift register (Si gate), and a polycode generator (Al gate). The 256-bit shift register shows very little degradation after 1 x 10 6 rads (Si), with an increase from 1.9V to 2.9V in minimum operating voltage, a decrease of about 20% in maximum frequency, and little or no change in quiescent current. The p-channel thresholds increase from -0.9V to -1.3V, while the n-channel thresholds decrease from 1.05 to 0.23V, and the n-channel leakage remains below 1nA/mil. Excellent hardening results were also obtained on the polycode generator circuit. Ten circuits were irradiated to 1 x 10 6 rads (Si), and all continued to function well, with an increase in minimum power supply voltage from 2.85V to 5.85V and an increase in quiescent current by a factor of about 2. Similar hardening results were obtained on the 8-bit adder, with the minimum power supply voltage increasing from 2.2V to 4.6V and the add time increasing from 270 to 350 nsec after 1 x 10 6 rads (Si). These results show that large CMOS/SOS circuits can be hardened to above 1 x 10 6 rads (Si) with either the Si gate or Al gate technology. The paper also discusses the relative advantages of the Si gate versus the Al gate technology

Beam hardening correction algorithm in microtomography images

International Nuclear Information System (INIS)

Sales, Erika S.; Lima, Inaya C.B.; Lopes, Ricardo T.; Assis, Joaquim T. de

2009-01-01

Quantification of mineral density of bone samples is directly related to the attenuation coefficient of bone. The X-rays used in microtomography images are polychromatic and have a moderately broad spectrum of energy, which makes the low-energy X-rays passing through a sample to be absorbed, causing a decrease in the attenuation coefficient and possibly artifacts. This decrease in the attenuation coefficient is due to a process called beam hardening. In this work the beam hardening of microtomography images of vertebrae of Wistar rats subjected to a study of hyperthyroidism was corrected by the method of linearization of the projections. It was discretized using a spectrum in energy, also called the spectrum of Herman. The results without correction for beam hardening showed significant differences in bone volume, which could lead to a possible diagnosis of osteoporosis. But the data with correction showed a decrease in bone volume, but this decrease was not significant in a confidence interval of 95%. (author)

Beam hardening correction algorithm in microtomography images

Energy Technology Data Exchange (ETDEWEB)

Sales, Erika S.; Lima, Inaya C.B.; Lopes, Ricardo T., E-mail: esales@con.ufrj.b, E-mail: ricardo@lin.ufrj.b [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Lab. de Instrumentacao Nuclear; Assis, Joaquim T. de, E-mail: joaquim@iprj.uerj.b [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Inst. Politecnico. Dept. de Engenharia Mecanica

2009-07-01

Quantification of mineral density of bone samples is directly related to the attenuation coefficient of bone. The X-rays used in microtomography images are polychromatic and have a moderately broad spectrum of energy, which makes the low-energy X-rays passing through a sample to be absorbed, causing a decrease in the attenuation coefficient and possibly artifacts. This decrease in the attenuation coefficient is due to a process called beam hardening. In this work the beam hardening of microtomography images of vertebrae of Wistar rats subjected to a study of hyperthyroidism was corrected by the method of linearization of the projections. It was discretized using a spectrum in energy, also called the spectrum of Herman. The results without correction for beam hardening showed significant differences in bone volume, which could lead to a possible diagnosis of osteoporosis. But the data with correction showed a decrease in bone volume, but this decrease was not significant in a confidence interval of 95%. (author)

Evaluation of hardening by ion irradiation in molybdenum using nanoindentation techniques

International Nuclear Information System (INIS)

Iwakiri, Hirotomi; Watanabe, Hideo; Yoshida, Naoaki

1997-01-01

As a part of fundamental research on interaction of plasma and wall, some model experiments on loading of particles such as He, H and so forth suffered by plasma facing material were conducted for Mo in high Z material. As an evaluation method for it, nanoindentation technique was proposed. By this method, the hardness evaluation in surface neighboring damage range was conducted. As a result, in the helium irradiated materials, sufficient hardening was observed even at low dpa range impossible to recognize hardening on heavy ion and deuterium irradiated materials, and extreme hardening was established by formation of helium bubble at high dpa region. Furthermore, in the helium irradiated materials, recovery of hardening could not be observed even for annealed materials at 1173 K for 1 hr after irradiation. From such results, hardening promotion work due to helium and extreme thermal stability of the formed defects were elucidated. (B.K.)

Experiment research on grind-hardening of AISI5140 steel based on thermal copensation

Energy Technology Data Exchange (ETDEWEB)

Huang, Xiang Ming; Ren, Ying Hui; Zheng, Bo; Zhou, Zhixiong [College of Mechanical and Vehicle Engineering, Hunan University, Changsha, Hunan (China); Deng, Zhao Hui [Key Laboratory for High Efficiency and Precision Machining of Difficult-to-Cut Material of Hunan Province, Hunan (China)

2016-08-15

The grind-hardening process utilizes the heat generated to induce martensitic phase transformation. However, the maximum achievable harden layer depth is limited due to high grinding forces, and the tensile residual stress appears on the ground surface in the grind-hardening process. This paper proposes a new grind-hardening technology using thermal compensation. The workpiece of AISI5140 steel is preheated by electric resistance heating, and ground under the condition of the workpiece temperature 25°C, 120°C, 180°C and 240°C. The grinding force, harden layer depth and surface quality including residual stress on ground surface, surface roughness and micro-hardness are investigated. The experimental results show that a deep harden layer with a fine grain martensite can be obtained with the thermal compensation. The ground workpiece surface produces a certain compressive residual stress, and the residual compressive stress value increases with preheating temperature. As the preheating temperature increases, grinding force slightly decreases, while there is slightly increment of surface roughness. Compared with the conventional grind-hardening process, both the harden layer depth and residual stress distribution are significantly improved.

Radiation-Hardened Electronics for Advanced Communications Systems

Science.gov (United States)

Whitaker, Sterling

2015-01-01

Novel approach enables high-speed special-purpose processors Advanced reconfigurable and reprogrammable communication systems will require sub-130-nanometer electronics. Legacy single event upset (SEU) radiation-tolerant circuits are ineffective at speeds greater than 125 megahertz. In Phase I of this project, ICs, LLC, demonstrated new base-level logic circuits that provide SEU immunity for sub-130-nanometer high-speed circuits. In Phase II, the company developed an innovative self-restoring logic (SRL) circuit and a system approach that provides high-speed, SEU-tolerant solutions that are effective for sub-130-nanometer electronics scalable to at least 22-nanometer processes. The SRL system can be used in the design of NASA's next-generation special-purpose processors, especially reconfigurable communication processors.

Grind hardening process

CERN Document Server

Salonitis, Konstantinos

2015-01-01

This book presents the grind-hardening process and the main studies published since it was introduced in 1990s.  The modelling of the various aspects of the process, such as the process forces, temperature profile developed, hardness profiles, residual stresses etc. are described in detail. The book is of interest to the research community working with mathematical modeling and optimization of manufacturing processes.

Concurrent strengthening of ultrafine-grained age-hardenable Al-Mg alloy by means of high-pressure torsion and spinodal decomposition

International Nuclear Information System (INIS)

Tang, Yongpeng; Goto, Wataru; Hirosawa, Shoichi; Horita, Zenji; Lee, Seungwon; Matsuda, Kenji; Terada, Daisuke

2017-01-01

In this study, the age-hardening behavior and precipitate microstructures of severely-deformed and then artificially-aged Al-13.4 wt%Mg alloy has been investigated by Vickers hardness test, X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and atom probe tomography (APT). The combined processing of high-pressure torsion (HPT) and aging treatment at a temperature below spinodal lines results in a higher attained hardness of ∼HV296 with an age-hardenability (i.e ΔHV31 ± 2) comparable to that of the undeformed specimen without HPT (i.e. ΔHV33 ± 2). The corresponding TEM microstructures consist of modulated structures associated with spinodal decomposition, and quantitative estimation of the amplitude, as well as the wavelength, of Mg fluctuations was successfully conducted by APT for the first time for this alloy system. The linear relationship between the increment of Vickers hardness and the estimated amplitude of the undeformed specimen supposed that Kato's spinodal-hardening mechanism works even in the HPTed specimen with a high number density of grain boundaries. Therefore, our proposed strategy; i.e. taking advantage of spinodal decomposition, is regarded as a convincing approach to achieving concurrent strengthening by ultrafine-grained and precipitation hardenings for the alloys that decompose via spinodal decomposition.

Comparative Study of Hardening Mechanisms During Aging of a 304 Stainless Steel Containing α'-Martensite

Science.gov (United States)

Jeong, S. W.; Kang, U. G.; Choi, J. Y.; Nam, W. J.

2012-09-01

Strain aging and hardening behaviors of a 304 stainless steel containing deformation-induced martensite were investigated by examining mechanical properties and microstructural evolution for different aging temperature and time. Introduced age hardening mechanisms of a cold rolled 304 stainless steel were the additional formation of α'-martensite, hardening of α'-martensite, and hardening of deformed austenite. The increased amount of α'-martensite at an aging temperature of 450 °C confirmed the additional formation of α'-martensite as a hardening mechanism in a cold rolled 304 stainless steel. Additionally, the increased hardness in both α'-martensite and austenite phases with aging temperature proved that hardening of both α'-martensite and austenite phases would be effective as hardening mechanisms in cold rolled and aged 304 stainless steels. The results suggested that among hardening mechanisms, hardening of an α'-martensite phase, including the diffusion of interstitial solute carbon atoms to dislocations and the precipitation of fine carbide particles would become a major hardening mechanism during aging of cold rolled 304 stainless steels.

Analysis of the work-hardening process in spheroidized steels

International Nuclear Information System (INIS)

Pacheco, J.L.

1981-07-01

An elementary model for the work-hardening process in duplex-structures steels (ferrite - spheroidite) is proposed and tested on low, medium and high carbon content, which seems to give good results concerning the influence of the volume fraction and particle size of the second phase on the work-hardening behaviour. (Author) [pt

Design and characterization of cellulose nanocrystal-enhanced epoxy hardeners

Science.gov (United States)

Shane X. Peng; Robert J. Moon; Jeffrey P. Youngblood

2014-01-01

Cellulose nanocrystals (CNCs) are renewable, sustainable, and abundant nanomaterial widely used as reinforcing fillers in the field of polymer nanocomposites. In this study, two-part epoxy systems with CNC-enhanced hardeners were fabricated. Three types of hardeners, Jeffamine D400 (JD400), diethylenetriamine (DETA), and (±)-trans-1,2- diaminocyclohexane (DACH), were...

Physical and Thermodynamical Properties of Water Phases in Hardening Portland Cement Systems

DEFF Research Database (Denmark)

Hansen, T. Bæk

The present study is devoted to the description of water phases in hardening portland cement paste systems containing a significant amount of micro-filler and having a low to moderate water/powder ratio. Emphasis has been placed on the early stages of the hardening process.......The present study is devoted to the description of water phases in hardening portland cement paste systems containing a significant amount of micro-filler and having a low to moderate water/powder ratio. Emphasis has been placed on the early stages of the hardening process....

Precipitation of β′ phase and hardening in dental-casting Ag–20Pd–12Au–14.5Cu alloys subjected to aging treatments

International Nuclear Information System (INIS)

Kim, Yonghwan; Niinomi, Mitsuo; Hieda, Junko; Nakai, Masaaki; Cho, Ken; Fukui, Hisao

2014-01-01

The age-hardening behavior of the dental-casting Ag–20Pd–12Au–14.5Cu alloy subjected to aging treatment at around 673 K is well known, and this hardening has been widely employed in various applications. To date, the age-hardening of this alloy has been explained to attribute to the precipitation of a β phase, which is a B2-type ordered CuPd phase or PdCu x Zn 1−x phase. In this study, results obtained from microstructural observations using a transmission electron microscopy and a scanning transmission electron microscopy revealed that a fine L1 0 -type ordered β′ phase precipitated in the matrix and a coarse-structure region (consisting of Ag- and Cu-rich regions) appeared after aging treatment at 673 K and contributed to increase in hardness. The microstructure of the coarse β phase, which existed before aging treatment, did not change by aging treatment. Thus, it is concluded that the fine β′ phase precipitated by aging treatment contributed more to increase in hardness than the coarse-structure region and coarse β phase. - Highlights: • Hardness of Ag–20Pd–12Au–14.5Cu alloy increased significantly by aging treatment. • A fine β′ phase and a coarse structure region appeared after aging treatment. • The microstructure of a coarse β phase did not change by aging treatment. • It is considered that the fine β′ phase contributed most to age-hardening

Radiation hardening revisited: Role of intracascade clustering

DEFF Research Database (Denmark)

Singh, B.N.; Foreman, A.J.E.; Trinkaus, H.

1997-01-01

be explained in terms of conventional dispersed-barrier hardening because (a) the grown-in dislocations are not free, and (b) irradiation-induced defect clusters are not rigid indestructible Orowan obstacles. A new model called 'cascade-induced source hardening' is presented where glissile loops produced...... directly in cascades are envisaged to decorate the grown-in dislocations so that they cannot act as dislocation sources. The upper yield stress is related to the breakaway stress which is necessary to pull the dislocation away from the clusters/loops decorating it. The magnitude of the breakaway stress has...

Unusual hardening behaviour in heavily cryo-rolled Cu-Al-Zn alloys during annealing treatment

Energy Technology Data Exchange (ETDEWEB)

Gong, Y.L. [Faculty of Science, Kunming University of Science and Technology, Kunming 650500 (China); Ren, S.Y. [Ningbo Powerway Alloy Material Co., Ltd, Ningbo 315135 (China); Zeng, S.D. [Yunnan Institute of Measuring and Testing Technology, Kunming 650228 (China); Zhu, X.K., E-mail: xk_zhu@hotmail.com [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650500 (China)

2016-04-06

Three nanostructured Cu-Al-Zn alloys were produced via rolling at the liquid nitrogen temperature. The deformed Cu alloys were then annealed at 150–300 °C for 1 h. The two alloys with high solute content and thus with low stacking fault energy exhibit unusual annealing hardening, namely, an increase in hardness and strength and a decrease in tensile elongation after annealing at 150 and 200 °C. From X-ray diffraction (XRD) analysis and microstructural observations by transmission electron microscopy (TEM), it is found that microstrain and dislocation density decrease after annealing at 200 °C because of the recovery of dislocations and the lattice parameter decreases due to solute segregation. Meanwhile, the twin density of the two Cu alloys increases and grain size remains basically unchanged. It is shown that the formation of annealing twins and stacking faults and the segregation of solute atoms may be the main causes of unusual annealing hardening.

USE OF ELECTRONIC EDUCATIONAL RESOURCES WHEN TRAINING IN WORK WITH SPREADSHEETS

Directory of Open Access Journals (Sweden)

Х А Гербеков

2017-12-01

Full Text Available Today the tools for maintaining training courses based on opportunities of information and communication technologies are developed. Practically in all directions of preparation and on all subject matters electronic textbook and self-instruction manuals are created. Nevertheless the industry of computer educational and methodical materials actively develops and gets more and more areas of development and introduction. In this regard more and more urgent is a problem of development of the electronic educational resources adequate to modern educational requirements. Creation and the organization of training courses with use of electronic educational resources in particular on the basis of Internet technologies remains a difficult methodical task.In article the questions connected with development of electronic educational resources for use when studying the substantial line “Information technologies” of a school course of informatics in particular for studying of spreadsheets are considered. Also the analysis of maintenance of a school course and the unified state examination from the point of view of representation of task in him corresponding to the substantial line of studying “Information technologies” on mastering technology of information processing in spreadsheets and the methods of visualization given by means of charts and schedules is carried out.

MOULDING MIXTURES HARDENING PROCESS BASED ON LIGNIN-BASE SULPHONATE BINDER

Directory of Open Access Journals (Sweden)

V. N. Ektova

2004-01-01

Full Text Available Hardening of agglutinant sands on lignosulphonate binding agent is the result of two processes: oxidation-reduction in the system lignosulphonate acids — persulfuric natrium in the early stages of hardening and hydration of cement in the latter stages.

A new constitutive equation for strain hardening and softening of fcc metals during severe plastic deformation

International Nuclear Information System (INIS)

Wei, W.; Wei, K.X.; Fan, G.J.

2008-01-01

The stress-strain relationship for strain hardening and softening of high-purity aluminum and copper, which were deformed by equal channel angular pressing (ECAP) at ambient temperature, was analyzed by combining the Estrin and Mecking (EM) model and an Avrami-type equation with experimental data during severe plastic deformation. The initial strain hardening can be described by the EM model, while the flow stress arrives at the peak stress after it was saturated. However, strain softening similar to plastic deformation at high temperatures is observed after the peak stress. Moreover, the peak strain at the maximum flow stress is ∼4 for copper and ∼2 for aluminum. A new constitutive equation was developed to describe strain softening at high strain levels, which was supported well by tensile, compression and microhardness tests at room temperature and low strain rate. It was observed that dynamic recovery and recrystallization occurs in copper, and recrystallized grains and their growth in aluminum. The results indicate that dynamic recovery and recrystallization was the dominant softening mechanism, which was confirmed by scanning electron microscopy-electron channeling contrast observations and the abnormal relationship between the imposed strain during ECAP and subsequent recrystallization temperature after ECAP

Precipitation hardening in dilute Al–Zr alloys

Directory of Open Access Journals (Sweden)

Pedro Henrique Lamarão Souza

2018-01-01

Full Text Available The aim of this study was to investigate the effect of solute content (hipoperitectic Al–0.22 wt.%Zr and hiperperitectic Al–0.32 wt.%Zr on the precipitation hardening and microstructural evolution of dilute Al–Zr alloys isothermally aged. The materials were conventionally cast in a muffle furnace, solidified in a water-cooled Cu mold and subsequently heat-treated at the temperature of 650 K (377 °C for 4, 12, 24, 100 and 400 h. Mechanical characterization was performed at room temperature, using a microhardness tester and microstructural characterization was carried out on a Transmission Electron Microscope – TEM. The observed microhardness values increased during isothermal aging, due to the precipitation of nanometer-scale Al3Zr L12 particles. Peak strength was achieved within 100 h of aging. After aging for 400 h, microhardness values presented a slight decrease for both alloys, thus indicating overaging due to the coalescence of precipitates. Microhardness values increased with solute content, due to the precipitation of a higher number density of finer precipitates. After 400 h of heat-treating, coalescence was higher for the alloy with lower solute content and, also, the presence of antiphase boundaries – APBs, planar faults associated with the L12 to D023 structural transition, were observed. Comparing theoretical calculations of the increment in strength due to precipitation strengthening with experimental results, it was observed that their values are in reasonable agreement. The Orowan dislocation looping mechanism takes place during precipitation hardening for both alloys in the peak hardness condition.

Strain-hardening behavior and microstructure development in polycrystalline as-cast Mg-Zn-Y alloys with LPSO phase subjected to cyclic loading

Energy Technology Data Exchange (ETDEWEB)

Shiraishi, Kazuma [Department of Materials Science and Engineering, Kumamoto University, 2-39-1, Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan); Mayama, Tsuyoshi, E-mail: mayama@kumamoto-u.ac.jp [Priority Organization for Innovation and Excellence, Kumamoto University, 2-39-1, Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan); Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Yamasaki, Michiaki [School of Mechanical and Mining Engineering, The University of Queensland, St Lucia, Brisbane, Qld 4072 (Australia); Magnesium Research Center/Department of Materials Science and Engineering, Kumamoto University, 2-39-1, Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan); Kawamura, Yoshihito [Magnesium Research Center/Department of Materials Science and Engineering, Kumamoto University, 2-39-1, Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)

2016-08-30

The strain-hardening behavior and microstructural development of polycrystalline as-cast Mg-Zn-Y alloys with various volume fractions of the long-period stacking ordered (LPSO) phase subjected to cyclic loading were experimentally evaluated. For all alloys, cyclic loading tests with a constant strain amplitude of 0.5% for up to 100 cycles showed asymmetric cyclic hardening behavior. That is, the absolute value of the compressive peak stress significantly increased during cyclic loading while the tensile peak stress slightly decreased. With increasing volume fraction of the LPSO phase, the stress amplitude significantly increased. Cyclic loading tests after compressive preloading up to 200 or 250 MPa resulted in a significant increase in the stress amplitude, while a number of kink bands developed during preloading. For the cyclic hardening behavior, the contribution of the increase in kinematic hardening was significant in the alloys with a higher volume fraction of the LPSO phase. Transmission electron microscopy observation of the cyclically deformed Mg{sub 85}Zn{sub 6}Y{sub 9} alloy indicated the formation of a deformation-induced band, where the crystal structure was transformed from 18R-LPSO to hcp-Mg with the exclusion of solute elements.

Radiation-hardened optoelectronic components: detectors

International Nuclear Information System (INIS)

Wiczer, J.J.

1986-01-01

In this talk, we will survey recent research in the area of radiation hardened optical detectors. We have studied conventional silicon photodiode structures, special radiation hardened silicon photodiodes, and special double heterojunction AlGaAs/GaAs photodiodes in neutron, gamma, pulsed x-ray and charged particle environments. We will present results of our work and summarize other research in this area. Our studies have shown that detectors can be made to function acceptably after exposures to neutron fluences of 10 15 n/cm 2 , total dose gamma exposures of 10 8 rad (Si), and flash x-ray environments of 10 8 rad/sec (Si). We will describe detector structures that can operate through these conditions, pre-rad and post-rad operational characteristics, and experimental conditions that produced these results. 23 refs., 10 figs., 1 tab

Increase of resistance to cracking on stress relieving of hardened steel

International Nuclear Information System (INIS)

Velichko, V.V.; Zabil'skij, V.V.; Mikheev, G.M.

1995-01-01

Regularities of increase of resistance to cracking during stress relieving of hardened low-alloyed steels were studied, using complex of methods. Effect of carbon, stress concentrator radius, duration and temperature of stress relieving was studies in particular. Results of investigating kinetics of change of physicomechanical properties, hydrogen desorption from hardened specimens showed, that increase of resistance to cracking was caused by desorption from grain boundaries of diffusion-mobile hydrogen, formed during hardening. 18 refs., 8 figs

Some aspects of plasticity in hardened face-centred cubic metals

International Nuclear Information System (INIS)

Jackson, P.J.; Nathanson, P.D.K.

1978-01-01

The plasticity of crystals of f.c.c. metals hardened by solute atoms, neutron irradiation, quenching and by dislocation distributions not characteristic of the active mode of testing is reviewed, with emphasis being placed on the simiularity of slip after various hardening treatments. Normal work hardening is not treated. The reasons for this exclusion are discussed. It is concluded that correlated slip is a normal aspect of deformation, and that diffuse uncorrelated slip occurs only when secondary dislocation multiplication is promoted, e.g. by obstacles introduced by prior slip, or by the presence of hard impenetrable obstacles of another material or phase [af

Work hardening behavior study of structural alloys for cryogenic applications

International Nuclear Information System (INIS)

Chu, D.; Morris, J.W. Jr.

1992-01-01

Previous investigation on aluminum-lithium alloys have indicated different dependencies of the work hardening behavior on temperature. This variation in temperature dependence is attributed to differences in microstructure rather than composition. An understanding of the microstructural effect on the observed thermal dependency is important as it may allow the tailoring of deformation properties through mechanical processing. Work hardening analyses on other aluminum alloys and a number of structural steels have been performed to better elucidate the role played by microstructure in determining the work hardening behavior. In the paper correlations between the differences in mechanical behavior and the various microstructures observed are presented

General analytical shakedown solution for structures with kinematic hardening materials

Science.gov (United States)

Guo, Baofeng; Zou, Zongyuan; Jin, Miao

2016-09-01

The effect of kinematic hardening behavior on the shakedown behaviors of structure has been investigated by performing shakedown analysis for some specific problems. The results obtained only show that the shakedown limit loads of structures with kinematic hardening model are larger than or equal to those with perfectly plastic model of the same initial yield stress. To further investigate the rules governing the different shakedown behaviors of kinematic hardening structures, the extended shakedown theorem for limited kinematic hardening is applied, the shakedown condition is then proposed, and a general analytical solution for the structural shakedown limit load is thus derived. The analytical shakedown limit loads for fully reversed cyclic loading and non-fully reversed cyclic loading are then given based on the general solution. The resulting analytical solution is applied to some specific problems: a hollow specimen subjected to tension and torsion, a flanged pipe subjected to pressure and axial force and a square plate with small central hole subjected to biaxial tension. The results obtained are compared with those in literatures, they are consistent with each other. Based on the resulting general analytical solution, rules governing the general effects of kinematic hardening behavior on the shakedown behavior of structure are clearly.

Skin hardening effect in patients with polymorphic light eruption: comparison of UVB hardening in hospital with a novel home UV-hardening device.

Science.gov (United States)

Franken, S M; Genders, R E; de Gruijl, F R; Rustemeyer, T; Pavel, S

2013-01-01

An effective prophylactic treatment of patients with polymorphic light eruption (PLE) consists of repeated low, gradually increasing exposures to UVB radiation. This so-called UV(B) hardening induces better tolerance of the skin to sunlight. SunshowerMedical company (Amsterdam) has developed an UV (B) source that can be used during taking shower. The low UV fluence of this apparatus makes it an interesting device for UV hardening. In a group of PLE patients, we compared the effectiveness of the irradiation with SunshowerMedical at home with that of the UVB treatment in the hospital. The PLE patients were randomized for one of the treatments. The hospital treatment consisted of irradiations with broad-band UVB (Waldmann 85/UV21 lamps) twice a week during 6 weeks. The home UV-device was used each day with the maximal irradiation time of 6 min. The outcome assessment was based on the information obtained from patients' dermatological quality of life (DLQI) questionnaires, the ability of both phototherapies to reduce the provocation reaction and from the patients' evaluation of the long-term benefits of their phototherapies. Sixteen patients completed treatment with SunshowerMedical and thirteen completed treatment in hospital. Both types of phototherapy were effective. There was a highly significant improvement in DLQI with either treatment. In most cases, the hardening reduced or even completely suppressed clinical UV provocation of PLE. The patients using SunshowerMedical at home were, however, much more content with the treatment procedure than the patients visiting the dermatological units. Both treatments were equally effective in the induction of skin tolerance to sunlight in PLE patients. However, the home treatment was much better accepted than the treatment in the hospital. © 2011 The Authors. Journal of the European Academy of Dermatology and Venereology © 2011 European Academy of Dermatology and Venereology.

Effects of solute elements on irradiation hardening and microstructural evolution in low alloy steels

Energy Technology Data Exchange (ETDEWEB)

Fujii, Katsuhiko, E-mail: fujiik@inss.co.jp [Institute of Nuclear Safety System Inc., 64 Sata, Mihama 919-1205 (Japan); Ohkubo, Tadakatsu, E-mail: OHKUBO.Tadakatsu@nims.go.jp [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Fukuya, Koji, E-mail: fukuya@inss.co.jp [Institute of Nuclear Safety System Inc., 64 Sata, Mihama 919-1205 (Japan)

2011-10-01

The effects of the elements Mn, Ni, Si and Cu on irradiation hardening and microstructural evolution in low alloy steels were investigated in ion irradiation experiments using five kinds of alloys prepared by removing Mn, Ni and Si from, and adding 0.05 wt.%Cu to, the base alloy (Fe-1.5Mn-0.5Ni-0.25Si). The alloy without Mn showed less hardening and the alloys without Ni or Si showed more hardening. The addition of Cu had hardly any influence on hardening. These facts indicated that Mn enhanced hardening and that Ni and Si had some synergetic effects. The formation of solute clusters was not confirmed by atom probe (AP) analysis, whereas small dislocation loops were identified by TEM observation. The difference in hardening between the alloys with and without Mn was qualitatively consistent with loop formation. However, microstructural components that were not detected by the AP and TEM were assumed to explain the hardening level quantitatively.

Analytical Study of Usage of Electronic Information Resources at Pharmacopoeial Libraries in India

Directory of Open Access Journals (Sweden)

Sunil Tyagi

2014-02-01

Full Text Available The objective of this study is to know the rate and purpose of the use of e-resource by the scientists at pharmacopoeial libraries in India. Among other things, this study examined the preferences of the scientists toward printed books and journals, electronic information resources, and pattern of using e-resources. Non-probability sampling specially accidental and purposive technique was applied in the collection of primary data through administration of user questionnaire. The sample respondents chosen for the study consists of principle scientific officer, senior scientific officer, scientific officer, and scientific assistant of different division of the laboratories, namely, research and development, pharmaceutical chemistry, pharmacovigilance, pharmacology, pharmacogonosy, and microbiology. The findings of the study reveal the personal experiences and perceptions they have had on practice and research activity using e-resource. The major findings indicate that of the total anticipated participants, 78% indicated that they perceived the ability to use computer for electronic information resources. The data analysis shows that all the scientists belonging to the pharmacopoeial libraries used electronic information resources to address issues relating to drug indexes and compendia, monographs, drugs obtained through online databases, e-journals, and the Internet sources—especially polices by regulatory agencies, contacts, drug promotional literature, and standards.

OCCUPATIONAL ASTHMA CAUSED BY A HARDENER CONTAINING AN ALIPHATIC AND A CYCLOALIPHATIC DIAMINE

NARCIS (Netherlands)

ALEVA, RM; AALBERS, R; KOETER, GH; DEMONCHY, JGR

An otherwise healthy 44-yr-old man experienced a serious attack of bronchial obstruction after working with resins and hardeners, releasing fumes of a mixture of an aliphatic and a cycloaliphatic diamine hardener. Eight hours after deliberate challenge with the hardener a large increase of airway

Technology of hardening fills for mined spaces

International Nuclear Information System (INIS)

Simek, P.; Holas, M.; Chyla, A.; Pech, P.

1985-01-01

The technology is described of hardening fills for mined spaces of uranium deposits in North Bohemian chalk. A special equipment was developed for the controlled preparation of a hardening mixture. The composition of the fill is determined by the strength of the filled rock, expecially by the standard strength, i.e., the minimal strength of the filling under uniaxial pressure. The said parameter determines the consumption of binding materials and thereby the total costs of the filling. A description is presented of the filling technology, including rabbit tube transport of the mixture and quality control. (Pu)

Effect of hardening methods of moulding sands with water glass on structure of bonding bridges

Directory of Open Access Journals (Sweden)

M. Stachowicz

2010-07-01

Full Text Available Research on influence of hardening methods on structure of bonding bridges in moulding sands with sodium water glass is presented.Moulding sands with addition of 2.5 % of binder with molar module 2.0 were hardened with CO2 and dried in traditional way or hardenedwith microwaves. It was proved that the hardening method affects structure of bonding bridges, correlating with properties of the hardened moulding sands. It was found that strength of the moulding sands hardened with microwaves for 4 min is very close to that measured after traditional drying at 110 °C for 120 min. So, application of microwave hardening ensures significant shortening of the process time to the value comparable with CO2 hardening but guaranteeing over 10-fold increase of mechanical properties. Analysis of SEM images of hardened moulding sands permitted explaining differences in quality parameters of moulding sands by connecting them with structure of the created bonding bridges.

Generation Mechanism of Work Hardened Surface Layer in Metal Cutting

Science.gov (United States)

Hikiji, Rikio; Kondo, Eiji; Kawagoishi, Norio; Arai, Minoru

Finish machining used to be carried out in grinding, but it is being replaced by cutting with very small undeformed chip thickness. In ultra precision process, the effects of the cutting conditions and the complicated factors on the machined surface integrity are the serious problems. In this research, work hardened surface layer was dealt with as an evaluation of the machined surface integrity and the effect of the mechanical factors on work hardening was investigated experimentally in orthogonal cutting. As a result, it was found that work hardened surface layer was affected not only by the shear angle varied under the cutting conditions and the thrust force of cutting resistance, but also by the thrust force acting point, the coefficient of the thrust force and the compressive stress equivalent to the bulk hardness. Furthermore, these mechanical factors acting on the depth of the work hardened surface layer were investigated with the calculation model.

Page 170 Use of Electronic Resources by Undergraduates in Two ...

African Journals Online (AJOL)

undergraduate students use electronic resources such as NUC virtual library, HINARI, ... web pages articles from magazines, encyclopedias, pamphlets and other .... of Nigerian university libraries have Internet connectivity, some of the system.

Solution and precipitation hardening of two-phase gamma titanium alloy; Mischkristall- und Ausscheidungshaertung zweiphasiger Gamma-Titanaluminidlegierungen

Energy Technology Data Exchange (ETDEWEB)

Christoph, U. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Werkstofforschung

1997-12-31

The present study on solution and precipitation hardening of two-phase gamma titanium aluminides was directed towards improved creep resistance. Alloys were systematically doped with carbon up to 0.37 atomic percent. Solid solutions and precipitates of carbon were formed by different thermal treatments. The hardening obtained as a result of the different precipitate conditions was measured by deformation experiments between 293 and 973 K. An increase of yield stress of up to 300 MPa was observed for finely distributed perovskite precipitates. This increase of yield stress was maintained up to 973 K and was shown to be dominantly athermal in character from activation parameter measurements. Electron microscopic investigations confirmed the athermal nature of the perovskite precipitates to dislocation motion. The precipitates thus act as barriers to dislocation glide over a wide temperature range and can therefore increase the creep resistance at the anticipated operation temperature of 973 K. In addition to studying the mechanism of precipitation hardening, the pinning of dislocations by the formation of impurity atmospheres has also been investigated. This phenomenon is effective at intermediate temperatures of around 550 K and is thought to be caused by very mobile elements such as iron and boron. These elements are present in all alloys of technical relevance. (orig.) 158 refs.

The Use of Fuzzy Systems for Forecasting the Hardenability of Steel

Directory of Open Access Journals (Sweden)

Sitek W.

2016-06-01

Full Text Available The goal of the research carried out was to develop the fuzzy systems, allowing the determination of the Jominy hardenability curve based on the chemical composition of structural steels for quenching and tempering. Fuzzy system was created to calculate hardness of the steel, based on the alloying elements concentrations, and to forecast the hardenability curves. This was done based on information from the PN-EN 10083-3: 2008. Examples of hardenability curves calculated for exemplar steels were presented. Results of the research confirmed that fuzzy systems are a useful tool in evaluation the effect of alloying elements on the properties of materials compared to conventional methods. It has been demonstrated the practical usefulness of the developed models which allows forecasting the steels’ Jominy hardenability curve.

Unit rupture work as a criterion for quantitative estimation of hardenability in steel

International Nuclear Information System (INIS)

Kramarov, M.A.; Orlov, E.D.; Rybakov, A.B.

1980-01-01

Shown is possible utilization of high sensitivity of resistance to fracture of structural steel to the hardenability degree in the course of hardening to find the quantitative estimation of the latter one. Proposed is a criterion kappa, the ratio of the unit rupture work in the case of incomplete hardenability (asub(Tsub(ih))) under investigation, and the analoguc value obtained in the case of complete hardenability Asub(Tsub(Ch)) at the testing temperature corresponding to the critical temperature Tsub(100(M). Confirmed is high criterion sensitivity of the hardened steel structure on the basis of experimental investigation of the 40Kh, 38KhNM and 38KhNMFA steels after isothermal hold-up at different temperatures, corresponding to production of various products of austenite decomposition

Determination of the strain hardening rate of metals and alloys by X ray diffraction

International Nuclear Information System (INIS)

Cadalbert, Robert

1977-01-01

This report for engineering graduation is based on the study of X ray diffraction line profile which varies with the plastic strain rate of the metal. After some generalities of strain hardening (consequence of a plastic deformation on the structure of a polycrystalline metal, means to study a strain hardened structure, use of X ray diffraction to analyse the strain hardened crystalline structure), the author reports the strain hardening rate measurement by using X ray diffraction. Several aspects are addressed: principles, experimental technique, apparatus, automation and programming of the measurement cycle, method sensitivity and precision. In the next part, the author reports applications: measurement of the strain hardening rate in different materials (tubes with hexagonal profile, cylindrical tubes in austenitic steel), and study of the evolution of strain hardening with temperature [fr

Model of e-learning with electronic educational resources of new generation

Directory of Open Access Journals (Sweden)

A. V. Loban

2017-01-01

Full Text Available Purpose of the article: improving of scientific and methodical base of the theory of the е-learning of variability. Methods used: conceptual and logical modeling of the е-learning of variability process with electronic educational resource of new generation and system analysis of the interconnection of the studied subject area, methods, didactics approaches and information and communication technologies means. Results: the formalization complex model of the е-learning of variability with electronic educational resource of new generation is developed, conditionally decomposed into three basic components: the formalization model of the course in the form of the thesaurusclassifier (“Author of e-resource”, the model of learning as management (“Coordination. Consultation. Control”, the learning model with the thesaurus-classifier (“Student”. Model “Author of e-resource” allows the student to achieve completeness, high degree of didactic elaboration and structuring of the studied material in triples of variants: modules of education information, practical task and control tasks; the result of the student’s (author’s of e-resource activity is the thesaurus-classifier. Model of learning as management is based on the principle of personal orientation of learning in computer environment and determines the logic of interaction between the lecturer and the student when determining the triple of variants individually for each student; organization of a dialogue between the lecturer and the student for consulting purposes; personal control of the student’s success (report generation and iterative search for the concept of the class assignment in the thesaurus-classifier before acquiring the required level of training. Model “Student” makes it possible to concretize the learning tasks in relation to the personality of the student and to the training level achieved; the assumption of the lecturer about the level of training of a

RESOURCE SAVING TECHNOLOGICAL PROCESS OF LARGE-SIZE DIE THERMAL TREATMENT

Directory of Open Access Journals (Sweden)

L. A. Glazkov

2009-01-01

Full Text Available The given paper presents a development of a technological process pertaining to hardening large-size parts made of die steel. The proposed process applies a water-air mixture instead of a conventional hardening medium that is industrial oil.While developing this new technological process it has been necessary to solve the following problems: reduction of thermal treatment duration, reduction of power resource expense (natural gas and mineral oil, elimination of fire danger and increase of process ecological efficiency. 

A survey of the use of electronic scientific information resources among medical and dental students

Directory of Open Access Journals (Sweden)

Aarnio Matti

2006-05-01

Full Text Available Abstract Background To evaluate medical and dental students' utilization of electronic information resources. Methods A web survey sent to 837 students (49.9% responded. Results Twenty-four per cent of medical students and ninteen per cent of dental students searched MEDLINE 2+ times/month for study purposes, and thiry-two per cent and twenty-four per cent respectively for research. Full-text articles were used 2+ times/month by thirty-three per cent of medical and ten per cent of dental students. Twelve per cent of respondents never utilized either MEDLINE or full-text articles. In multivariate models, the information-searching skills among students were significantly associated with use of MEDLINE and full-text articles. Conclusion Use of electronic resources differs among students. Forty percent were non-users of full-text articles. Information-searching skills are correlated with the use of electronic resources, but the level of basic PC skills plays not a major role in using these resources. The student data shows that adequate training in information-searching skills will increase the use of electronic information resources.

Age-hardening of an Al-Li-Cu-Mg alloy (2091) processed by high-pressure torsion

Energy Technology Data Exchange (ETDEWEB)

Lee, Seungwon, E-mail: chominamlsw@gmail.com [Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan); WPI, International Institute for Carbon-Neutral Energy Research (I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); Horita, Zenji [Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan); WPI, International Institute for Carbon-Neutral Energy Research (I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); Hirosawa, Shoichi [Department of Mechanical Engineering and Materials Science, Yokohama National University, Yokohama 240-8501 (Japan); Matsuda, Kenji [Graduate School of Science and Engineering for Research, University of Toyama, Toyama 930-8555 (Japan)

2012-06-01

This research presents the successful strengthening of an Al-Li-Cu-Mg alloy (2091) through the simultaneous use of grain refinement and age hardening. Following solid-solution treatment, the alloy was processed by high-pressure torsion (HPT) at room temperature and the grain size was refined to {approx}140 nm. The Vickers microhardness increased with increasing strain, and saturated to a constant level of 225 Hv. A further increase in the hardness to {approx}275 Hv was achieved by aging the HPT-processed alloy at 100 Degree-Sign C and 150 Degree-Sign C. Bending tests for the samples treated using the peak aging conditions demonstrated that the stress was significantly increased while considerable ductility was retained. Transmission electron microscopy revealed that the small grains are well retained even after prolonged aging, and the precipitation of fine {delta} Prime particles occurred within the small grains, which confirms that simultaneous strengthening from grain refinement and age hardening is feasible in this alloy.

Segmentation-free empirical beam hardening correction for CT

Energy Technology Data Exchange (ETDEWEB)

Schüller, Sören; Sawall, Stefan [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120 (Germany); Stannigel, Kai; Hülsbusch, Markus; Ulrici, Johannes; Hell, Erich [Sirona Dental Systems GmbH, Fabrikstraße 31, 64625 Bensheim (Germany); Kachelrieß, Marc, E-mail: marc.kachelriess@dkfz.de [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)

2015-02-15

Purpose: The polychromatic nature of the x-ray beams and their effects on the reconstructed image are often disregarded during standard image reconstruction. This leads to cupping and beam hardening artifacts inside the reconstructed volume. To correct for a general cupping, methods like water precorrection exist. They correct the hardening of the spectrum during the penetration of the measured object only for the major tissue class. In contrast, more complex artifacts like streaks between dense objects need other techniques of correction. If using only the information of one single energy scan, there are two types of corrections. The first one is a physical approach. Thereby, artifacts can be reproduced and corrected within the original reconstruction by using assumptions in a polychromatic forward projector. These assumptions could be the used spectrum, the detector response, the physical attenuation and scatter properties of the intersected materials. A second method is an empirical approach, which does not rely on much prior knowledge. This so-called empirical beam hardening correction (EBHC) and the previously mentioned physical-based technique are both relying on a segmentation of the present tissues inside the patient. The difficulty thereby is that beam hardening by itself, scatter, and other effects, which diminish the image quality also disturb the correct tissue classification and thereby reduce the accuracy of the two known classes of correction techniques. The herein proposed method works similar to the empirical beam hardening correction but does not require a tissue segmentation and therefore shows improvements on image data, which are highly degraded by noise and artifacts. Furthermore, the new algorithm is designed in a way that no additional calibration or parameter fitting is needed. Methods: To overcome the segmentation of tissues, the authors propose a histogram deformation of their primary reconstructed CT image. This step is essential for the

Segmentation-free empirical beam hardening correction for CT.

Science.gov (United States)

Schüller, Sören; Sawall, Stefan; Stannigel, Kai; Hülsbusch, Markus; Ulrici, Johannes; Hell, Erich; Kachelrieß, Marc

2015-02-01

The polychromatic nature of the x-ray beams and their effects on the reconstructed image are often disregarded during standard image reconstruction. This leads to cupping and beam hardening artifacts inside the reconstructed volume. To correct for a general cupping, methods like water precorrection exist. They correct the hardening of the spectrum during the penetration of the measured object only for the major tissue class. In contrast, more complex artifacts like streaks between dense objects need other techniques of correction. If using only the information of one single energy scan, there are two types of corrections. The first one is a physical approach. Thereby, artifacts can be reproduced and corrected within the original reconstruction by using assumptions in a polychromatic forward projector. These assumptions could be the used spectrum, the detector response, the physical attenuation and scatter properties of the intersected materials. A second method is an empirical approach, which does not rely on much prior knowledge. This so-called empirical beam hardening correction (EBHC) and the previously mentioned physical-based technique are both relying on a segmentation of the present tissues inside the patient. The difficulty thereby is that beam hardening by itself, scatter, and other effects, which diminish the image quality also disturb the correct tissue classification and thereby reduce the accuracy of the two known classes of correction techniques. The herein proposed method works similar to the empirical beam hardening correction but does not require a tissue segmentation and therefore shows improvements on image data, which are highly degraded by noise and artifacts. Furthermore, the new algorithm is designed in a way that no additional calibration or parameter fitting is needed. To overcome the segmentation of tissues, the authors propose a histogram deformation of their primary reconstructed CT image. This step is essential for the proposed

Anomalous precipitation hardening in Al-(1 wt%)Cu thin films

NARCIS (Netherlands)

Bergers, L. J. C.; De Hosson, J. Th. M.; Geers, M. G. D.; Hoefnagels, J. P. M.

2018-01-01

This paper concentrates on the precipitation hardening of Al-(1 wt%)Cu thin films. It is shown that in contrast to bulk, the well-known approach of precipitation hardening in confined systems like thin layers and thin films does not operate in the conventional way. This work analyses and discusses

Access to electronic information resources by students of federal ...

African Journals Online (AJOL)

The paper discusses access to electronic information resources by students of Federal Colleges of Education in Eha-Amufu and Umunze. Descriptive survey design was used to investigate sample of 526 students. Sampling technique used was a Multi sampling technique. Data for the study were generated using ...

Adoption and use of electronic information resources by medical ...

African Journals Online (AJOL)

This study investigated the adoption and use of electronic information resources by medical science students of the University of Benin. The descriptive survey research design was adopted for the study and 390 students provided the data. Data collected were analysed with descriptive Statistics(Simple percentage and ...

Residual stresses relaxation in surface-hardened half-space under creep conditions

Directory of Open Access Journals (Sweden)

Vladimir P. Radchenko

2015-09-01

Full Text Available We developed the method for solving the problem of residual stresses relaxation in surface-hardened layer of half-space under creep conditions. At the first stage we made the reconstruction of stress-strain state in half-space after plastic surface hardening procedure based on partial information about distribution for one residual stress tensor component experimentally detected. At the second stage using a numerical method we solve the problem of relaxation of self-balanced residual stresses under creep conditions. To solve this problem we introduce the following Cartesian system: x0y plane is aligned with hardened surface of half-space and 0z axis is directed to the depth of hardened layer. We also introduce the hypotheses of plane sections parallel to x0z and y0z planes. Detailed analysis of the problem has been done. Comparison of the calculated data with the corresponding test data was made for plane specimens (rectangular parallelepipeds made of EP742 alloy during T=650°C after the ultrasonic hardening with four hardening modes. We use half-space to model these specimens because penetration's depth of residual stresses is less than specimen general size in two digit exponent. There is enough correspondence of experimental and calculated data. It is shown that there is a decay (in modulus of pressing residual stresses under creep in 1.4–1.6 times.

Ion irradiation-induced swelling and hardening effect of Hastelloy N alloy

Energy Technology Data Exchange (ETDEWEB)

Zhang, S.J. [Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Li, D.H.; Chen, H.C.; Lei, G.H.; Huang, H.F.; Zhang, W.; Wang, C.B. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Yan, L., E-mail: yanlong@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Fu, D.J. [Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Tang, M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2017-06-15

The volumetric swelling and hardening effect of irradiated Hastelloy N alloy were investigated in this paper. 7 MeV and 1 MeV Xe ions irradiations were performed at room temperature (RT) with irradiation dose ranging from 0.5 to 27 dpa. The volumetric swelling increases with increasing irradiation dose, and reaches up to 3.2% at 27 dpa. And the irradiation induced lattice expansion is also observed. The irradiation induced hardening initiates at low ion dose (≤1dpa) then saturates with higher ion dose. The irradiation induced volumetric swelling may be ascribed to excess atomic volume of defects. The irradiation induced hardening may be explained by the pinning effect where the defects can act as obstacles for the free movement of dislocation lines. And the evolution of the defects' size and number density could be responsible for the saturation of hardness. - Highlights: •Irradiation Swelling: The irradiation induced volumetric swelling increases with ion dose. •Irradiation Hardening: The irradiation hardening initiates below 1 dpa, then saturates with higher ion dose (1–10 dpa). •Irradiation Mechanism: The irradiation phenomena are ascribed to the microstructural evolution of the irradiation defects.

Helium-induced hardening effect in polycrystalline tungsten

Science.gov (United States)

Kong, Fanhang; Qu, Miao; Yan, Sha; Zhang, Ailin; Peng, Shixiang; Xue, Jianming; Wang, Yugang

2017-09-01

In this paper, helium induced hardening effect of tungsten was investigated. 50 keV He2+ ions at fluences vary from 5 × 1015 cm-2 to 5 × 1017 cm-2 were implanted into polycrystalline tungsten at RT to create helium bubble-rich layers near the surface. The microstructure and mechanical properties of the irradiated specimens were studied by TEM and nano-indentor. Helium bubble rich layers are formed in near surface region, and the layers become thicker with the rise of fluences. Helium bubbles in the area of helium concentration peak are found to grow up, while the bubble density is almost unchanged. Obvious hardening effect is induced by helium implantation in tungsten. Micro hardness increases rapidly with the fluence firstly, and more slowly when the fluence is above 5 × 1016 cm-2. The hardening effect of tungsten can be attributed to helium bubbles, which is found to be in agreement with the Bacon-Orowan stress formula. The growing diameter is the major factor rather than helium bubbles density (voids distance) in the process of helium implantation at fluences below 5 × 1017 cm-2.

Where Do Electronic Books Fit in the College Research Arsenal of Resources?

Science.gov (United States)

Barbier, Patricia

2007-01-01

Student use of electronic books has become an accepted supplement to traditional resources. Student use and satisfaction was monitored through an online course discussion board. Increased use of electronic books indicate this service is an accepted supplement to the print book collection.

CASE-HARDENING OF STAINLESS STEEL

DEFF Research Database (Denmark)

2004-01-01

The invention relates to case-hardening of a stainless steel article by means of gas including carbon and/or nitrogen, whereby carbon and/or nitrogen atoms diffuse through the surface into the article. The method includes activating the surface of the article, applying a top layer on the activated...

Role of grain refinement in hardening of structural steels at preliminary thermomechanical treatment

International Nuclear Information System (INIS)

Bukhvalov, A.B.; Grigor'eva, E.V.; Davydova, L.S.; Degtyarev, M.V.; Levit, V.I.; Smirnova, N.A.; Smirnov, L.V.

1981-01-01

The hardening mechanism during preliminary thermomechanical treatment with deformation by cold rolling or hydroextrusion is studied on structural 37KhN3M1 and 38KhN3MFA steels. Specimens have been tested on static tension, impact strength and fracture toughness. It is shown that hydroextrusion application instead of rolling does not change the hardening effect of preliminary thermomechanical treatment (PTMT). It is established that the increase of preliminary deformation degree and the use of accelerated short term hardening heating provides a bett er grain refinement and the increase of PTMT hardening effect [ru

Investigation of magnesium oxychloride cement at the initial hardening stage

Directory of Open Access Journals (Sweden)

Averina Galina

2018-01-01

Full Text Available The paper investigates the process of variation of magnesium oxychloride cement deformations at the initial hardening stage depending on the activity of magnesium oxide powder which is determined by the parameters of the source material burning. Investigation is focused on magnesium cements obtained from pure magnesium hydroxide. Source materials were burnt at various temperatures with the purpose to obtain magnesium oxide powder with different activity. Regular content of hydrated phases was determined in hardened magnesium cement prepared on the basis of binders with different activity. The study reveals the influence of magnesium oxide powder activity on the process of deformation occurrence in hardened magnesium cement and its tendency to crack formation.

Aspect-oriented security hardening of UML design models

CERN Document Server

Mouheb, Djedjiga; Pourzandi, Makan; Wang, Lingyu; Nouh, Mariam; Ziarati, Raha; Alhadidi, Dima; Talhi, Chamseddine; Lima, Vitor

2015-01-01

This book comprehensively presents a novel approach to the systematic security hardening of software design models expressed in the standard UML language. It combines model-driven engineering and the aspect-oriented paradigm to integrate security practices into the early phases of the software development process. To this end, a UML profile has been developed for the specification of security hardening aspects on UML diagrams. In addition, a weaving framework, with the underlying theoretical foundations, has been designed for the systematic injection of security aspects into UML models. The

Optimization of hardening/softening behavior of plane frame structures using nonlinear normal modes

DEFF Research Database (Denmark)

Dou, Suguang; Jensen, Jakob Søndergaard

2016-01-01

Devices that exploit essential nonlinear behavior such as hardening/softening and inter-modal coupling effects are increasingly used in engineering and fundamental studies. Based on nonlinear normal modes, we present a gradient-based structural optimization method for tailoring the hardening...... involving plane frame structures where the hardening/softening behavior is qualitatively and quantitatively tuned by simple changes in the geometry of the structures....

Micromilling of hardened tool steel for mould making applications

DEFF Research Database (Denmark)

Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

2005-01-01

geometries as those characterizing injection moulding moulds. The realization of the micromilling process in connection with hardened tool steel as workpiece material is particularly challenging. The low strength of the miniaturized end mills implies reduction and accurate control of the chip load which...... wear. This paper presents the micromilling process applied to the manufacturing of micro injection moulding moulds in hardened tool steel, presenting experimental evidence and possible solutions to the above-mentioned issues....

Orowan strengthening and forest hardening superposition examined by dislocation dynamics simulations

International Nuclear Information System (INIS)

Queyreau, Sylvain; Monnet, Ghiath; Devincre, Benoit

2010-01-01

Rule of mixtures are an essential feature of the modeling of plastic deformation in complex materials in which more than one strain-hardening mechanism is involved. In this work, use is made of dislocation dynamics simulations to characterize the individual and the superposed contributions of two major mechanisms of crystal plasticity, i.e. Orowan strengthening and forest hardening. Based on a formal description of each hardening mechanism, evidence is presented to show that a quadratic rule of mixtures has the ability to predict quantitatively the flow stress of complex materials such as reactor pressure vessel steel.

Effect of strain rate and temperature on strain hardening behavior of a dissimilar joint between Ti–6Al–4V and Ti17 alloys

International Nuclear Information System (INIS)

Wang, S.Q.; Liu, J.H.; Chen, D.L.

2014-01-01

Highlights: • Only stage III hardening occurs after yielding in Ti–6Al–4V/Ti17 dissimilar joints. • Voce stress and strength of the joints increase with increasing strain rate. • With increasing strain rate, hardening capacity and strain hardening exponent decrease. • With increasing temperature, hardening capacity and strain hardening exponent increase. • Strain rate sensitivity of the joints decreases as the true strain increases. - Abstract: The aim of this study was to evaluate the influence of strain rate and temperature on the tensile properties, strain hardening behavior, strain rate sensitivity, and fracture characteristics of electron beam welded (EBWed) dissimilar joints between Ti–6Al–4V and Ti17 (Ti–5Al–4Mo–4Cr–2Sn–2Zr) titanium alloys. The welding led to significant microstructural changes across the joint, with hexagonal close-packed martensite (α′) and orthorhombic martensite (α″) in the fusion zone (FZ), α′ in the heat-affected zone (HAZ) on the Ti–6Al–4V side, and coarse β in the HAZ on the Ti17 side. A distinctive asymmetrical hardness profile across the dissimilar joint was observed with the highest hardness in the FZ and a lower hardness on the Ti–6Al–4V side than on the Ti17 side, where a soft zone was present. Despite a slight reduction in ductility, the yield strength (YS) and ultimate tensile strength (UTS) of the joints lay in-between the two base metals (BMs) of Ti–6Al–4V and Ti17, with the Ti17 alloy having a higher strength. While the YS, UTS, and Voce stress of the joints increased, both hardening capacity and strain hardening exponent decreased with increasing strain rate or decreasing temperature. Stage III hardening occurred in the joints after yielding. The hardening rate was strongly dependent on the strain rate and temperature. As the strain rate increased or temperature decreased, the strain hardening rate increased at a given true stress. The strain rate sensitivity evaluated via

Strain hardening of aluminium alloy 3004 in the deep drawing and ironing processes

International Nuclear Information System (INIS)

Courbon, J.; Duval, J.L.

1993-01-01

The evolution of material hardening resulting from the canmaking operations on aluminium beverage cans has been investigated. Tensile tests in cup walls revealed that deep drawing induced softening in the hoop direction and hardening in the meridian direction. This anisotropy is retained in the ironing operation. Changes in strain path on a heavily cold-rolled material probably cause such a complex behaviour. To determine hardening laws for deep drawing, simple shear tests were thus performed because of the strain path similarity. They allowed to determine hardening laws over larger strains than tension could reach and revealed a saturation of stress. Altogether they proved adapted to the understanding of deep drawing. (orig.)

Strategic Planning for Electronic Resources Management: A Case Study at Gustavus Adolphus College

Science.gov (United States)

Hulseberg, Anna; Monson, Sarah

2009-01-01

Electronic resources, the tools we use to manage them, and the needs and expectations of our users are constantly evolving; at the same time, the roles, responsibilities, and workflow of the library staff who manage e-resources are also in flux. Recognizing a need to be more intentional and proactive about how we manage e-resources, the…

REVIEW OF MOODLE PLUGINS FOR DESIGNING MULTIMEDIA ELECTRONIC EDUCATIONAL RESOURCES FROM LANGUAGE DISCIPLINES

Directory of Open Access Journals (Sweden)

Anton M. Avramchuk

2015-09-01

Full Text Available Today the problem of designing multimedia electronic educational resources from language disciplines in Moodle is very important. This system has a lot of different, powerful resources, plugins to facilitate the learning of students with language disciplines. This article presents an overview and comparative analysis of the five Moodle plugins for designing multimedia electronic educational resources from language disciplines. There have been considered their key features and functionality in order to choose the best for studying language disciplines in the Moodle. Plugins are compared by a group of experts according to the criteria: efficiency, functionality and easy use. For a comparative analysis of the plugins it is used the analytic hierarchy process.

Investigation of selective oxidation in bake hardenable steel

International Nuclear Information System (INIS)

Madeira, Laureanny; Lins, Vanessa Cunha Freitas; Faria, Guilherme Augusto de; Guimaraes, Juliana Porto; Alvarenga, Evandro de Azevedo; Vilela, Jose Mario Carneiro

2010-01-01

The present work aims to characterize a steel bake hardenable (BH), annealed in three different dew points (-60°C, -30°C and 0°C), as the occurrence of selective oxidation, using the techniques of X-ray photo electronic spectroscopy (XPS), glow discharge optical emission spectroscopy (GDOES) and atomic force microscopy (AFM). The analysis by XPS showed that the alloying elements oxidized at different intensities for each dew point. Analysis by GDOES revealed that the surface and subsurface concentrations of these elements also varied with the dew point. The AFM images revealed that the size and shape of the oxides were different for each dew point. At the dew points of -30°C and -60°C the formation of oxides was local, while at 0°C the growth of oxides occurred uniform y on the surface of steels. (author)

Work hardening correlation for monotonic loading based on state variables

International Nuclear Information System (INIS)

Huang, F.H.; Li, C.Y.

1977-01-01

An absolute work hardening correlation in terms of the hardness parameter and the internal stress based on the state variable approach was developed. It was found applicable to a variety of metals and alloys. This correlation predicts strain rate insensitive work hardening properties at low homologous temperatures and produces strain rate effects at higher homologous temperatures without involving thermally induced recovery processes

Induction hardening of tool steel for heavily loaded aircraft engine components

Directory of Open Access Journals (Sweden)

Rokicki P.

2017-03-01

Full Text Available Induction hardening is an innovative process allowing modification of the materials surface with more effective, cheaper and more reproducible way to compare with conventional hardening methods used in the aerospace industry. Unfortunately, high requirements and strict regulation concerning this branch of the industry force deep research allowing to obtain results that would be used for numerical modelling of the process. Only by this way one is able to start the industrial application of the process. The main scope of presented paper are results concerning investigation of microstructure evolution of tool steel after single-frequency induction hardening process. The specimens that aim in representing final industrial products (as heavily loaded gears, were heat- -treated with induction method and subjected to metallographic preparation, after which complex microstructure investigation was performed. The results obtained within the research will be a basis for numerical modelling of the process of induction hardening with potential to be introduced for the aviation industrial components.

Simulating the influence of scatter and beam hardening in dimensional computed tomography

Science.gov (United States)

Lifton, J. J.; Carmignato, S.

2017-10-01

Cone-beam x-ray computed tomography (XCT) is a radiographic scanning technique that allows the non-destructive dimensional measurement of an object’s internal and external features. XCT measurements are influenced by a number of different factors that are poorly understood. This work investigates how non-linear x-ray attenuation caused by beam hardening and scatter influences XCT-based dimensional measurements through the use of simulated data. For the measurement task considered, both scatter and beam hardening are found to influence dimensional measurements when evaluated using the ISO50 surface determination method. On the other hand, only beam hardening is found to influence dimensional measurements when evaluated using an advanced surface determination method. Based on the results presented, recommendations on the use of beam hardening and scatter correction for dimensional XCT are given.

GRAVITY PIPELINE TRANSPORT FOR HARDENING FILLING MIXTURES

Directory of Open Access Journals (Sweden)

Leonid KROUPNIK

2015-12-01

Full Text Available In underground mining of solid minerals becoming increasingly common development system with stowing hardening mixtures. In this case the natural ore array after it is replaced by an artificial excavation of solidified filling mixture consisting of binder, aggregates and water. Such a mixture is prepared on the surface on special stowing complexes and transported underground at special stowing pipelines. However, it is transported to the horizons of a few kilometers, which requires a sustainable mode of motion of such a mixture in the pipeline. Hardening stowing mixture changes its rheological characteristics over time, which complicates the calculation of the parameters of pipeline transportation. The article suggests a method of determining the initial parameters of such mixtures: the status coefficient, indicator of transportability, coefficient of hydrodynamic resistance to motion of the mixture. These indicators characterize the mixture in terms of the possibility to transport it through pipes. On the basis of these indicators is proposed methodology for calculating the parameters of pipeline transport hardening filling mixtures in drift mode when traffic on the horizontal part of the mixture under pressure column of the mixture in the vertical part of the backfill of the pipeline. This technique allows stable operation is guaranteed to provide pipeline transportation.

Effect of ethephon on hardening of Pachystroma longifolium seedlings

Directory of Open Access Journals (Sweden)

João Alexandre Lopes Dranski

2013-06-01

Full Text Available Immediately after planting, tree seedlings face adverse environmental and biotic stresses that must be overcome to ensure survival and to yield a desirable growth. Hardening practices in the nursery may help improve seedling stress resistance through reduction of aboveground plant tissues and increased root volume and biomass. We conducted an assay to quantify changes in the morphogenesis following application of ethephon on seedlings of Pachystroma longifolium (Ness I. M. Johnst.during hardening. The results showed no effect of the ethephon treatments on the number of leaves but a reduction of up to 50% in seedling height increment, and an increase in stem diameter increment of up to 44% with the 600 mg L-1 ethephon treatment, which consequently altered seedling Dickson Quality Index. Our results indicate that ethephon may help to promote desired morphological changes that occur during seedling hardening in nurseries.

The effect of voids on the hardening of body-centered cubic Fe

Energy Technology Data Exchange (ETDEWEB)

Nakai, Ryosuke, E-mail: ryosuke.nakai@jupiter.qse.tohoku.ac.jp [Department of Quantum Science and Energy Engineering, Tohoku University, 6-6-01-2, Aramaki-Aza-Aoba, Aobaku, Sendai, Miyagi, 980-8579 (Japan); Yabuuchi, Kiyohiro, E-mail: k-yabuuchi@iae.kyoto-u.ac.jp [Department of Quantum Science and Energy Engineering, Tohoku University, 6-6-01-2, Aramaki-Aza-Aoba, Aobaku, Sendai, Miyagi, 980-8579 (Japan); Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 (Japan); Nogami, Shuhei, E-mail: shuhei.nogami@qse.tohoku.ac.jp [Department of Quantum Science and Energy Engineering, Tohoku University, 6-6-01-2, Aramaki-Aza-Aoba, Aobaku, Sendai, Miyagi, 980-8579 (Japan); Hasegawa, Akira, E-mail: akira.hasegawa@qse.tohoku.ac.jp [Department of Quantum Science and Energy Engineering, Tohoku University, 6-6-01-2, Aramaki-Aza-Aoba, Aobaku, Sendai, Miyagi, 980-8579 (Japan)

2016-04-01

The mechanical properties of metals are affected by various types of defects. Hardening is usually described through the interaction between dislocations and obstacles, in the so-called line tension theory. The strength factor in the line tension theory represents the resistance of a defect against the dislocation motion. In order to understand hardening from the viewpoint of the microstructure, an accurate determination of the strength factor of different types of defects is essential. In the present study, the strength factor of voids in body-centered cubic (BCC) Fe was investigated by two different approaches: one based on the Orowan equation to link the measured hardness with the average size and density of voids, and the other involving direct observation of the interaction between dislocations and voids by transmission electron microscope (TEM). The strength factor of voids induced by ion irradiation estimated by the Orowan equation was 0.6, whereas the strength factor estimated by the direct TEM approach was 0.8. The difference in the strength factors measured by the two approaches is due to the positional relationship between dislocations and voids: the central region of a void is stronger than the tip. Moreover, the gliding plane and the direction of dislocation may also affect the strength factor of voids. This study determined the strength factor of voids in BCC Fe accurately, and suggested that the contribution of voids to the irradiation hardening is larger than that of dislocation loops and Cu-rich precipitates. - Highlights: • The strength factor of voids in BCC Fe was experimentally investigated. • The strength factor of voids estimated by the line tension theory was 0.6. • The strength factor of voids estimated by the bowing angle of dislocations was 0.8. • The different strength factors are due to the positional relationship.

Designing of the chemical composition of steels basing on the hardenability of constructional steels

International Nuclear Information System (INIS)

Dobrzanski, L.A.; Sitek, W.

2003-01-01

The paper presents the original method of modelling of the relationships between chemical composition of alloy constructional steel and its hardenability, employing neural networks. Basing on the experimental results of the hardenability investigations, which employed Jominy method, the model of the neural networks was developed and fully verified experimentally. The model makes it possible to obtain Jominy hardenability curves basing on the steel chemical composition. The model of neural networks, making it possible to design the steel chemical composition, basing on the known Jominy hardenability curve shape, was developed also and fully verified numerically. (author)

Modern ICT Tools: Online Electronic Resources Sharing Using Web ...

African Journals Online (AJOL)

Modern ICT Tools: Online Electronic Resources Sharing Using Web 2.0 and Its Implications For Library And Information Practice In Nigeria. ... The PDF file you selected should load here if your Web browser has a PDF reader plug-in installed (for example, a recent version of Adobe Acrobat Reader). If you would like more ...

Update on radiation-hardened microcomputers for robotics and teleoperated systems

International Nuclear Information System (INIS)

Sias, F.R. Jr.; Tulenko, J.S.

1993-01-01

Since many programs sponsored by the Department of Defense are being canceled, it is important to select carefully radiation-hardened microprocessors for projects that will mature (or will require continued support) several years in the future. At the present time there are seven candidate 32-bit processors that should be considered for long-range planning for high-performance radiation-hardened computer systems. For Department of Energy applications it is also important to consider efforts at standardization that require the use of the VxWorks operating system and hardware based on the VMEbus. Of the seven processors, one has been delivered and is operating and other systems are scheduled to be delivered late in 1993 or early in 1994. At the present time the Honeywell-developed RH32, the Harris RH-3000 and the Harris RHC-3000 are leading contenders for meeting DOE requirements for a radiation-hardened advanced 32-bit microprocessor. These are all either compatible with or are derivatives of the MIPS R3000 Reduced Instruction Set Computer. It is anticipated that as few as two of the seven radiation-hardened processors will be supported by the space program in the long run

ANALISIS ARAH DAN PERLAKUAN SERAT TAPIS SERTA RASIO EPOXY HARDENER TERHADAP SIFAT FISIS DAN MEKANIS KOMPOSIT TAPIS/EPOXY

Directory of Open Access Journals (Sweden)

Putu Lokantara

2012-11-01

Full Text Available Tapis kelapa (Coconut filter as natural fiber, in this time its resources very copius but no longer be exploited and thrown off hand as waste though in fact its used for other material dissimilar inovatif and high economic valuable that is as one of natural fiber alternative to be composite. The objective of this research is to investigate the behavior changing of physical and mechanical properties of composite tapis kelapa as reinforcement and epoxy 7120 with hardener Versamid 140 as matrix. The fiber is treated with the chemical NaOH and KMnO4 with percentage 0.5%, 1%, and 2% in weight, respectively. The ratio of epoxy and hardener is 7:3 and 6:4, and fiber orientation 0o, 45o, dan 90o. For testing of the speciment in tensile test with ASTM standard D3039 and three point bending test with ASTM standard D790. The result of this research obtained that fiber treatment with KMnO4 give the better effect to machine properties compared to NaOH. Variation of percentage 0.5%, 1%, and 2% NaOH and KMnO4 give the effect in fiber surface which higher percentage make the cleaner of surface, decrease of wax contain, and roughness of fiber surface so that stronger of linkage of fiber and matrix and increase of tensile strength, bending strength, and bending modulus of the composite. The highest tensile strength, modulus of elasticity and bending strength are 70.23 MPa, 446.24 GPa and 97.81 MPa respectively reached at composite with ratio epoxy/hardener 7:3; by 2% KMnO4 and fiber orientation 45o. While the highest modulus of elasticity is 385.48 GPa reached at composite with the ratio epoxy/hardener 6:4; 2% KMnO4 and fiber orientation 90o. Keywords: Tensile Strength, bending strength, ratio of epoxy/hardener, NaOH, KMnO4

The capability of pulsed laser radiation for cutting band saws hardening

Directory of Open Access Journals (Sweden)

Marinin Evgeny

2017-01-01

Full Text Available The article deals with the possibilities of pulsed laser radiation for hardening the band saws. The regimes of pulsed laser hardening the band saws of 1 mm thick made of tool steel 9CrV are grounded theoretically and experimentally tested. Selected and justified modes of treatment harden in the autohardening mode without additional heat removal. The results of the experimental research of microhardness are presented and formed as a result of processing of the microstructure. Selected modes increase the microhardness of the surface to 8500 MPa and form ultra highly dispersed structure in the surface layer characterized by high resistance to abrasion.

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

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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.

Radiation hardening and embrittlement of some refractory metals and alloys

International Nuclear Information System (INIS)

Fabritsiev, S.; Pokrovskyb

2007-01-01

Tungsten is proposed for application in the ITER divertor and limiter as plasma facing material. The tungsten operation temperature in the ITER divertor is relatively high. Hence, the ductile properties of tungsten will be controlled by the low temperature radiation embrittlement. The mechanism of radiation hardening and embrittlement under neutron irradiation at low temperature is well studied for FCC metals, in particular for copper. At the same time, low-temperature radiation hardening of BCC materials, in particular for refractory metals, is less studied. This study presents the results of investigation into radiation hardening and embrittlement of pure metals: W, Mo and Nb, and W-Re and Ta-4W alloys. The materials were in the annealed conditions. The specimens were irradiated in the SM-2 reactor to doses of 10 -4 -10 -1 dpa at 80 C and then tested for tension at 80 C. The study of the stress-strain curves of unirradiated specimens revealed a yield drop for W, Mo, Nb, Ta-4W, W-Re. After the yield drop some metals (Mo,Nb) retain their capability for strain hardening and demonstrate a high elongation (20-50%). Radiation hardening is maximum in Mo (∝400MPa) and minimum in Nb (∝100 MPa). In this case the dependence slope for Nb is similar to that for pure copper irradiated in SM-2 under the same conditions. Ii and Ta-4W have a higher slope. Measurement of electrical resistivity of irradiated specimens showed that for all materials it is increased monotonously with an increase in the irradiation dose. A minimum gain in electrical resistivity with a dose was observed for Nb (∝3% at 0.1 dpa). As for Mo it was essentially higher, i.e. ∝ 30%. The gain was maximum for W-Re alloy. Comparison of radiation hardening dose dependencies obtained in this study with the data for FCC metals (Cu) showed that in spite of the quantitative difference the qualitative behavior of these two classes of metals is similar. (orig.)

Estimation of radiation hardening in ferritic steels using the cluster dynamics models

Energy Technology Data Exchange (ETDEWEB)

Kwon, Jun Hyun; Kim, Whung Whoe; Hong, Jun Hwa [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2005-07-01

Evolution of microstructure under irradiation brings about the mechanical property changes of materials, of which the major concern is radiation hardening in this work. Radiation hardening is generally expressed in terms of an increase in yield strength as a function of radiation dose and temperature. Cluster dynamics model for radiation hardening has been developed to describe the evolution of point defects clusters (PDCs) and copperrich precipitates (CRPs). While the mathematical models developed by Stoller focus on the evolution of PDCs in ferritic steels under neutron irradiation, we slightly modify the model by including the CRP growth and estimate the magnitude of hardening induced by PDC and CRP. The model is then used to calculate the changes in yield strength of RPV steels. The calculation results are compared to measured yield strength values, obtained from surveillance testing of PWR vessel steels in France.

THE MODEL OF LINGUISTIC TEACHERS’ COMPETENCY DEVELOPMENT ON DESIGNING MULTIMEDIA ELECTRONIC EDUCATIONAL RESOURCES IN THE MOODLE SYSTEM

Directory of Open Access Journals (Sweden)

Anton M. Avramchuk

2017-10-01

Full Text Available The article is devoted to the problem of developing the competency of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system. The concept of "the competence of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system" is justified and defined. Identified and characterized the components by which the levels of the competency development of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system should be assessed. Developed a model for the development of the competency of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system, which is based on the main scientific approaches, used in adult education, and consists of five blocks: target, informative, technological, diagnostic and effective.

Effect of bainitic transformation on bake hardening in TRIP assisted steel

International Nuclear Information System (INIS)

Das, S.; Timokhina, I.; Singh, S.B.; Pereloma, E.; Mohanty, O.N.

2012-01-01

Highlights: ► Bainitic transformation in TRIP-assisted steel can lead to a very good bake hardening response as demonstrated by other researchers also. ► No extra deformation is needed. Dislocations can be generated in situ during the transformation itself. ► Detail characterisation and theoretical treatments showed bainite plates are sufficiently enriched with extra carbon atoms which can migrate and lock the dislocations. - Abstract: Bake hardening is a phenomenon where freshly generated dislocations get pinned down by the migrating carbon atoms under the influence of temperature employed in paint baking shop. Experimentally, a minimal 2% deformation is given to generate such new dislocations. On the other hand, after bainitic transformation, steel contains a large number of dislocations as well as excess carbon atoms in bainite, a combination of which is capable of producing bake hardening effect. In the current analysis, one grade of transformation induced plasticity aided steel was chosen to study the effect of isothermal bainitic transformation on subsequent bake hardening response, without giving any deformation assuming that the previous treatment would have generated sufficient dislocations which could be pinned down by the migrating carbon atoms under the influence of thermal treatment of the bake hardening process. The final microstructure was characterised by many techniques, using Thermo-Calc, optical microscopy, XRD analysis and 3-DAP. A good agreement was observed amongst all the techniques employed.

Two Back Stress Hardening Models in Rate Independent Rigid Plastic Deformation

Science.gov (United States)

Yun, Su-Jin

In the present work, the constitutive relations based on the combination of two back stresses are developed using the Armstrong-Frederick, Phillips and Ziegler’s type hardening rules. Various evolutions of the kinematic hardening parameter can be obtained by means of a simple combination of back stress rate using the rule of mixtures. Thus, a wide range of plastic deformation behavior can be depicted depending on the dominant back stress evolution. The ultimate back stress is also determined for the present combined kinematic hardening models. Since a kinematic hardening rule is assumed in the finite deformation regime, the stress rate is co-rotated with respect to the spin of substructure obtained by incorporating the plastic spin concept. A comparison of the various co-rotational rates is also included. Assuming rigid plasticity, the continuum body consists of the elastic deformation zone and the plastic deformation zone to form a hybrid finite element formulation. Then, the plastic deformation behavior is investigated under various loading conditions with an assumption of the J2 deformation theory. The plastic deformation localization turns out to be strongly dependent on the description of back stress evolution and its associated hardening parameters. The analysis for the shear deformation with fixed boundaries is carried out to examine the deformation localization behavior and the evolution of state variables.

Developing Humanities Collections in the Digital Age: Exploring Humanities Faculty Engagement with Electronic and Print Resources

Science.gov (United States)

Kachaluba, Sarah Buck; Brady, Jessica Evans; Critten, Jessica

2014-01-01

This article is based on quantitative and qualitative research examining humanities scholars' understandings of the advantages and disadvantages of print versus electronic information resources. It explores how humanities' faculty members at Florida State University (FSU) use print and electronic resources, as well as how they perceive these…

The effect of the initial microstructure in terms of sink strength on the ion-irradiation-induced hardening of ODS alloys studied by nanoindentation

Science.gov (United States)

Duan, Binghuang; Heintze, Cornelia; Bergner, Frank; Ulbricht, Andreas; Akhmadaliev, Shavkat; Oñorbe, Elvira; de Carlan, Yann; Wang, Tieshan

2017-11-01

Oxide dispersion strengthened (ODS) Fe-Cr alloys are promising candidates for structural components in nuclear energy production. The small grain size, high dislocation density and the presence of particle matrix interfaces may contribute to the improved irradiation resistance of this class of alloys by providing sinks and/or traps for irradiation-induced point defects. The extent to which these effects impede hardening is still a matter of debate. To address this problem, a set of alloys of different grain size, dislocation density and oxide particle distribution were selected. In this study, three-step Fe-ion irradiation at both 300 °C and 500 °C up to 10 dpa was used to introduce damage in five different materials including three 9Cr-ODS alloys, one 14Cr-ODS alloy and one 14Cr-non-ODS alloy. Electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), small angle neutron scattering (SANS), and nanoindentation testing were applied, the latter before and after irradiation. Significant hardening occurred for all materials and temperatures, but it is distinctly lower in the 14Cr alloys and also tends to be lower at the higher temperature. The possible contribution of Cr-rich α‧-phase particles is addressed. The impact of grain size, dislocation density and particle distribution is demonstrated in terms of an empirical trend between total sink strength and hardening.

Branching structure and strain hardening of branched metallocene polyethylenes

International Nuclear Information System (INIS)

Torres, Enrique; Li, Si-Wan; Costeux, Stéphane; Dealy, John M.

2015-01-01

There have been a number of studies of a series of branched metallocene polyethylenes (BMPs) made in a solution, continuous stirred tank reactor (CSTR) polymerization. The materials studied vary in branching level in a systematic way, and the most highly branched members of the series exhibit mild strain hardening. An outstanding question is which types of branched molecules are responsible for strain hardening in extension. This question is explored here by use of polymerization and rheological models along with new data on the extensional flow behavior of the most highly branched members of the set. After reviewing all that is known about the effects of various branching structures in homogeneous polymers and comparing this with the structures predicted to be present in BMPs, it is concluded that in spite of their very low concentration, treelike molecules with branch-on-branch structure provide a large number of deeply buried inner segments that are essential for strain hardening in these polymers

Branching structure and strain hardening of branched metallocene polyethylenes

Energy Technology Data Exchange (ETDEWEB)

Torres, Enrique; Li, Si-Wan; Costeux, Stéphane; Dealy, John M., E-mail: john.dealy@mcgill.ca [Department of Chemical Engineering, McGill University, Montreal, Quebec H3A 0C4 (Canada)

2015-09-15

There have been a number of studies of a series of branched metallocene polyethylenes (BMPs) made in a solution, continuous stirred tank reactor (CSTR) polymerization. The materials studied vary in branching level in a systematic way, and the most highly branched members of the series exhibit mild strain hardening. An outstanding question is which types of branched molecules are responsible for strain hardening in extension. This question is explored here by use of polymerization and rheological models along with new data on the extensional flow behavior of the most highly branched members of the set. After reviewing all that is known about the effects of various branching structures in homogeneous polymers and comparing this with the structures predicted to be present in BMPs, it is concluded that in spite of their very low concentration, treelike molecules with branch-on-branch structure provide a large number of deeply buried inner segments that are essential for strain hardening in these polymers.

Effect of strengthening mechanisms on cold workability and instantaneous strain hardening behavior during grain refinement of AA 6061-10 wt.% TiO2 composite prepared by mechanical alloying

International Nuclear Information System (INIS)

Sivasankaran, S.; Sivaprasad, K.; Narayanasamy, R.; Iyer, Vijay Kumar

2010-01-01

Research highlights: → Various strengthening mechanisms such as solid solution, grain size, precipitate, dislocation and dispersion strengthening promoted yield strength of the composites → The 5 h sintered composite yielded a large plastic strain (23%) at ambient temperature. → The domination of interparticle friction effects, grain size and dislocation strengthening diminished the deformation capacity of the composites greater than 5 h of milling. → Ultra-fine grained composite (40 h) yielded a high strength (>1000 MPa). → The proposed instantaneous new Poisson's ratio and the instantaneous strain hardening index used to study the extent of plastic zone and strain levels of the composite. - Abstract: The mechanical alloying (MA) of AA 6061 alloy reinforced with 10 wt.% fine anatase-titania composites powder milled with different timings (1, 5, 10, 20, 30, and 40 h) was cold consolidated and sintered. The main purpose of this study is to investigate the effect of microstructure and the various strengthening mechanisms such as solid solution, grain size, precipitate, dislocation and dispersion strengthening during grain refinement of AA 6061-10 wt.% TiO 2 composite via MA on cold working and strain hardening behavior. The sintered composite preforms were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope. The strengthening mechanisms were estimated by using simplified models available in the literatures. The evaluation of cold deformation behavior under triaxial stress condition through room temperature cold-upsetting tests (incremental loads) was studied by correlating the strengthening mechanisms. Among the developed strengthening mechanisms the grain size and dislocation strengthening mechanisms diminished the deformation capacity of the composites. The strain hardening behavior was also examined by proposing instantaneous strain hardening index (n i ). The value of maximum instantaneous strain

Effect of Pre-Aging Conditions on Bake-Hardening Response of Al-0.4 wt%Mg-1.2 wt%Si-0.1 wt%Mn Alloy Sheets

International Nuclear Information System (INIS)

Lee, Kwang-jin; Woo, Kee-do

2011-01-01

Pre-aging heat treatment after solution heat treatment (SHT) of Al-0.4 wt%Mg-1.2 wt%Si-0.1 wt%Mn alloy sheets for auto-bodies was carried out to investigate the effect of pre-aging and its conditions on the bake-hardening response. Mechanical properties were evaluated by a tensile and Vickers hardness test. Microstructural observation was also performed using a transmission electron microscope (TEM). It was revealed that pre-aging treatments play a great role in the bake-hardening response. In addition, it was found that the sphere-shaped nanosized clusters that can directly transit to the needle-shaped β” phase during the paint-bake process, not being dissolved into the matrix, are formed at 343 K. The result, reveals that the dominant factor of the bake-hardening response is the pre-aging temperature rather than the pre-aging time.

The surface fatigue life of contour induction hardened AISI 1552 gears

Science.gov (United States)

Townsend, Dennis P.; Turza, Alan; Chaplin, Mike

1995-07-01

Two groups of spur gears manufactured from two different materials and heat treatments were endurance tested for surface fatigue life. One group was manufactured from AISI 1552 and was finished ground to a 0.4 micron (16 micro-in.) rms surface finish and then dual frequency contour induction hardened. The second group was manufactured from CEVM AISI 9310 and was carburized, hardened, and ground to a 0.4 micron (16 micro-in.) rms surface finish. The gear pitch diameter was 8.89 cm (3.5 in.). Test conditions were a maximum Hertz stress of 1.71 GPa (248 ksi), a bulk gear temperature of approximately 350 K (170 F) and a speed of 10,000 rpm. The lubricant used for the tests was a synthetic paraffinic oil with an additive package. The test results showed that the 10 percent surface fatigue (pitting) life of the contour hardened AISI 1552 test gears was 1.7 times that of the carburized and hardened AISI 9310 test gears. Also there were two early failures of the AISI 1552 gears by bending fatigue.

Fatigue of coated and laser hardened steels

International Nuclear Information System (INIS)

La Cruz, P. de.

1990-01-01

In the present work the effect of ion nitriding, laser hardening and hot dip galvanizing upon the fatigue limit and notch sensitivity of a B-Mn Swedish steel SS 2131 have been investigated. The fatigue tests were performed in plane reverse bending fatigue (R=1). The quenched and tempered condition was taken as the reference condition. The microstructure, microhardness, fracture surface and coating appearance of the fatigue surface treated specimens were studied. Residual stress and retained austenite measurements were also carried out. It was found that ion nitriding improves the fatigue limit by 53 % for smooth specimens and by 115 % for notched specimens. Laser hardening improves the fatigue limit by 18 % and 56 % for smooth and notched specimen respectively. Hot dip galvanizing gives a slight deterioration of the fatigue limit (9 % and 10 % for smooth and notched specimen respectively). Ion nitriding and laser hardening decrease the value of the notch sensitivity factor q by 78 % and 65 % respectively. Hot dip galvanizing does not modify it. A simple schematic model based on a residual stress distribution, has been used to explain the different effects. It seems that the presence of the higher compressive residual stresses and the higher uniformity of the microstructure may be the causes of the better fatigue performance of ion nitrided specimens. (119 refs.) (author)

Strain path and work-hardening behavior of brass

International Nuclear Information System (INIS)

Sakharova, N.A.; Fernandes, J.V.; Vieira, M.F.

2009-01-01

Plastic straining in metal forming usually includes changes of strain path, which are frequently not taken into account in the analysis of forming processes. Moreover, strain path change can significantly affect the mechanical behavior and microstructural evolution of the material. For this reason, a combination of several simple loading test sequences is an effective way to investigate the dislocation microstructure of sheet metals under such forming conditions. Pure tension and rolling strain paths and rolling-tension strain path sequences were performed on brass sheets. A study of mechanical behavior and microstructural evolution during the simple and the complex strain paths was carried out, within a wide range of strain values. The appearance and development of deformation twinning was evident. It was shown that strain path change promotes the onset of premature twinning. The work-hardening behavior is discussed in terms of the twinning and dislocation microstructure evolution, as revealed by transmission electron microscopy

Design Features of Hardening Turners with Outstripping Plastic Deformation

Directory of Open Access Journals (Sweden)

V. M. Yaroslavtsev

2014-01-01

Full Text Available An efficiency of the cutting method with outstripping plastic deformation (OPD in lathe works is defined in many respects by design features of the add-on devices for mechanical hardening of a cut-off layer material in the course of cutting. Applied on lathes, deforming OPD devices can have differing dimensions, placement on the lathe, drive type (manual, electric, hydraulic, pneumatic, pneumohydraulic, electromagnetic, and autonomy degree towards the metalcutting equipment and industrial equipment.At the same time there are a number of inherent design features of work-hardening devices the modernized lathes with OPD use for machining. Now the OPD standard devices implement two principle construction options: loading device is placed on the machine or on the OPD slide support separate of the tool, or it is structurally aligned with the cutting tool. In the latter case the OPD device for turning is called a tool mandrel, which is mounted in a tool post of the machine or, at large dimensions, such a mandrel is mounted on the machine instead of the tool mandrel.When designing the OPD devices, is important to take into consideration production requirements and recommendations for the technological equipment, developed in the course of creation, working off and introduction of such installations for mechanical hardening of material. In compliance with it, OPD devices, their placement on the machine, and working displacements shouldn't limit technological capabilities of the applied metal-cutting equipment. OPD stresses have to be smoothly regulated, with maximum loads being limited to admissible values for the machine model to be modernized. It is necessary to ensure synchronized longitudinal and cross displacements of the cutting tool and OPD hardener with respect to the axis of billet rotation to enable regulation and readjustment of the hardener and tool placement. It ought to foresee the increased mobile components rigidity and manufacturing

THE MECHANISM OF HARDENING OF ALLOYED STEELS IN IMPULSE MAGNETIC FIELD

Directory of Open Access Journals (Sweden)

A. V. Alifanov

2012-01-01

Full Text Available In this paper, a model describing the mechanism of hardening steels in a pulsed magnetic field is provided. The model is based on the consideration of induction currents in the grain bulk ferrite, on the surface of the workpiece near the inductor. The influence of doping efficiency of the process of hardening is established.

A unified theoretical and experimental study of anisotropic hardening

International Nuclear Information System (INIS)

Boehler, J.P.; Raclin, J.

1981-01-01

The purpose of this work is to develop a consistent formulation of the constitutive relations regarding anisotropic hardening materials. Attention is focused on the appearance and the evolution of mechanical anisotropies during irreversible processes, such as plastic forming and inelastic deformation of structures. The representation theorems for anisotropic tensor functions constitute a theoretical basis, allowing to reduce arbitrariness and to obtain a unified formulation of anisotropic hardening. In this approach, a general three-dimensional constitutive law is developed for prestrained initially orthotropic materials. Introduction of the plastic behavior results in the general forms of both the flow-law and the yield criterion. The developed theory is then specialized for the case of plane stress and different modes of anisotropic hardening are analyzed. A new generalization of the Von Mises criterion is proposed, in considering a homogeneous form of order two in stress and employing the simplest combinations of the basic invariants entering the general form of the yield condition. The proposed criterion involves specific terms accounting for the initial anisotropy, the deformation induced anisotropy and correlative terms between initial and induced anisotropy. The effects of prestrainings result in both isotropic and anisotropic hardening. An adequate experimental program, consisting of uniaxial tensile tests on oriented specimens of prestrained sheet-metal, was performed, in order to determine the specific form and the evolution of the anisotropic failure criterion for soft-steel subjected to different irreversible prestrainings. (orig.)

Influence of coolant motion on structure of hardened steel element

Directory of Open Access Journals (Sweden)

A. Kulawik

2008-08-01

Full Text Available Presented paper is focused on volumetric hardening process using liquid low melting point metal as a coolant. Effect of convective motion of the coolant on material structure after hardening is investigated. Comparison with results obtained for model neglecting motion of liquid is executed. Mathematical and numerical model based on Finite Element Metod is described. Characteristic Based Split (CBS method is used to uncouple velocities and pressure and finally to solve Navier-Stokes equation. Petrov-Galerkin formulation is employed to stabilize convective term in heat transport equation. Phase transformations model is created on the basis of Johnson-Mehl and Avrami laws. Continuous cooling diagram (CTPc for C45 steel is exploited in presented model of phase transformations. Temporary temperatures, phases participation, thermal and structural strains in hardening element and coolant velocities are shown and discussed.

Structural characterisation of oxygen diffusion hardened alpha-tantalum PVD-coatings on titanium.

Science.gov (United States)

Hertl, C; Koll, L; Schmitz, T; Werner, E; Gbureck, U

2014-08-01

Titanium substrates were coated with tantalum layers of 5 μm thickness using physical vapour deposition (PVD). The tantalum layers showed a (110)-preferred orientation. The coated samples were hardened by oxygen diffusion. Using X-ray diffraction the crystallographic structure of the tantalum coatings was characterised, comparing untreated and diffusion hardened specimen conditions. Oxygen depth profiles were determined by glow discharge spectrometry. The hardening effect of the heat treatment was examined by Vickers microhardness testing. The increase of surface hardness caused by oxygen diffusion was at least 50%. Copyright © 2014 Elsevier B.V. All rights reserved.

Electronic resource management systems a workflow approach

CERN Document Server

Anderson, Elsa K

2014-01-01

To get to the bottom of a successful approach to Electronic Resource Management (ERM), Anderson interviewed staff at 11 institutions about their ERM implementations. Among her conclusions, presented in this issue of Library Technology Reports, is that grasping the intricacies of your workflow-analyzing each step to reveal the gaps and problems-at the beginning is crucial to selecting and implementing an ERM. Whether the system will be used to fill a gap, aggregate critical data, or replace a tedious manual process, the best solution for your library depends on factors such as your current soft

Effects of solute elements on hardening of thermally-aged RPV model alloys

International Nuclear Information System (INIS)

Dohi, Kenji; Nishida, Kenji; Nomoto, Akiyoshi; Soneda, Naoki; Liu, Li; Sekimura, Naoto; Li Zhengcao

2012-01-01

The investigation of effects of solute elements on the copper-enriched cluster, which is a cause of radiation embrittlement of reactor pressure vessel steels, is needed in order to understand the mechanism of the hardening and the cluster formation. The dependence of the hardness change and the formation of thermally-aged Fe-Cu model alloys doped Ni, Si and Mn on aging time are investigated using Vickers harness tester and three dimensional atom probe. Ni addition suppresses hardening, and Si addition accelerates hardening slightly at the initial stage of the aging. Mn addition accelerates hardening much more but does not almost affect the peak hardness. Ni and Si addition increase the number density and the size of the cluster, while Mn addition remarkably increases the number density and the size of the cluster at the initial stage of the aging. In addition, there is no clear correlation between the square root of the volume fraction of the clusters and the hardness change for all of the alloys. The reasons are considered to be the decrease in the solute hardening caused by the cluster formation and the difference in the shear modulus of the cluster due to the difference in the chemical composition of the cluster. (author)

Effect of bainitic transformation on bake hardening in TRIP assisted steel

Energy Technology Data Exchange (ETDEWEB)

Das, S., E-mail: sourav.das@tatasteel.com [Research and Development, Tata Steel Limited, Jamshedpur (India); Timokhina, I. [Centre for Material and Fibre Innovation/Science and Technology, Deakin University (Australia); Singh, S.B. [Metallurgical and Materials Engineering, IIT Kharagpur (India); Pereloma, E. [BlueScope Steel Metallurgy Centre, University of Wollongong (Australia); Mohanty, O.N. [RSB Metaltech, RSB Group, Jamshedpur (India)

2012-02-01

Highlights: Black-Right-Pointing-Pointer Bainitic transformation in TRIP-assisted steel can lead to a very good bake hardening response as demonstrated by other researchers also. Black-Right-Pointing-Pointer No extra deformation is needed. Dislocations can be generated in situ during the transformation itself. Black-Right-Pointing-Pointer Detail characterisation and theoretical treatments showed bainite plates are sufficiently enriched with extra carbon atoms which can migrate and lock the dislocations. - Abstract: Bake hardening is a phenomenon where freshly generated dislocations get pinned down by the migrating carbon atoms under the influence of temperature employed in paint baking shop. Experimentally, a minimal 2% deformation is given to generate such new dislocations. On the other hand, after bainitic transformation, steel contains a large number of dislocations as well as excess carbon atoms in bainite, a combination of which is capable of producing bake hardening effect. In the current analysis, one grade of transformation induced plasticity aided steel was chosen to study the effect of isothermal bainitic transformation on subsequent bake hardening response, without giving any deformation assuming that the previous treatment would have generated sufficient dislocations which could be pinned down by the migrating carbon atoms under the influence of thermal treatment of the bake hardening process. The final microstructure was characterised by many techniques, using Thermo-Calc, optical microscopy, XRD analysis and 3-DAP. A good agreement was observed amongst all the techniques employed.

Influence of alloying elements on the irradiation hardening and environmental sensitivity of zirconium alloys

International Nuclear Information System (INIS)

Pettersson, K.; Hallstadius, L.; Bergqvist, H.; Nylund, A.; Wikstroem, C.

1992-01-01

Ten different alloys of zirconium have been tested with regard to the effect of irradiation on their mechanical properties and their sensitivity to environmentally induced failure. Two different environments were used: iodine vapour and liquid cesium with an addition of 2% cadmium. The neutron dose was 10 21 n/cm 2 (E>1MeV) and the irradiation temperature was about 300 degrees C. All alloy additions increased the irradiation hardening. Especially notable was the large effect of titanium and tin on irradiation hardening. A limited amount of transmission electron microscopy was carried out in order to find an explanation to the effects. The testing in different environments showed that there is no clear correlation between environmental sensitivity and yield stress. For materials of similar yield stress an alloyed material tends to be more sensitive to environmental cracking than a material which only contains oxygen as an impurity. There also seems to be an effect of oxygen on the environmental cracking sensitivity. A material with 910 ppm oxygen was considerably more sensitive to cracking than a material with 470 ppm oxygen despite the fact that the yield stress values differed by only 90 MPa

Radiation Hardened 10BASE-T Ethernet Physical Layer (PHY)

Science.gov (United States)

Lin, Michael R. (Inventor); Petrick, David J. (Inventor); Ballou, Kevin M. (Inventor); Espinosa, Daniel C. (Inventor); James, Edward F. (Inventor); Kliesner, Matthew A. (Inventor)

2017-01-01

Embodiments may provide a radiation hardened 10BASE-T Ethernet interface circuit suitable for space flight and in compliance with the IEEE 802.3 standard for Ethernet. The various embodiments may provide a 10BASE-T Ethernet interface circuit, comprising a field programmable gate array (FPGA), a transmitter circuit connected to the FPGA, a receiver circuit connected to the FPGA, and a transformer connected to the transmitter circuit and the receiver circuit. In the various embodiments, the FPGA, transmitter circuit, receiver circuit, and transformer may be radiation hardened.

Electronic Resource Management System. Vernetzung von Lizenzinformationen

Directory of Open Access Journals (Sweden)

Michaela Selbach

2014-12-01

Full Text Available In den letzten zehn Jahren spielen elektronische Ressourcen im Bereich der Erwerbung eine zunehmend wichtige Rolle: Eindeutig lässt sich hier ein Wandel in den Bibliotheken (fort vom reinen Printbestand zu immer größeren E-Only-Beständen feststellen. Die stetig wachsende Menge an E-Ressourcen und deren Heterogenität stellt Bibliotheken vor die Herausforderung, die E-Ressourcen effizient zu verwalten. Nicht nur Bibliotheken, sondern auch verhandlungsführende Institutionen von Konsortial- und Allianzlizenzen benötigen ein geeignetes Instrument zur Verwaltung von Lizenzinformationen, welches den komplexen Anforderungen moderner E-Ressourcen gerecht wird. Die Deutsche Forschungsgemeinschaft (DFG unterstützt ein Projekt des Hochschulbibliothekszentrums des Landes Nordrhein-Westfalen (hbz, der Universitätsbibliothek Freiburg, der Verbundzentrale des Gemeinsamen Bibliotheksverbundes (GBV und der Universitätsbibliothek Frankfurt, in dem ein bundesweit verfügbares Electronic Ressource Managementsystem (ERMS aufgebaut werden soll. Ein solches ERMS soll auf Basis einer zentralen Knowledge Base eine einheitliche Nutzung von Daten zur Lizenzverwaltung elektronischer Ressourcen auf lokaler, regionaler und nationaler Ebene ermöglichen. Statistische Auswertungen, Rechteverwaltung für alle angeschlossenen Bibliotheken, kooperative Datenpflege sowie ein über standardisierte Schnittstellen geführter Datenaustausch stehen bei der Erarbeitung der Anforderungen ebenso im Fokus wie die Entwicklung eines Daten- und Funktionsmodells. In the last few years the importance of electronic resources in library acquisitions has increased significantly. There has been a shift from mere print holdings to both e- and print combinations and even e-only subscriptions. This shift poses a double challenge for libraries: On the one hand they have to provide their e-resource collections to library users in an appealing way, on the other hand they have to manage these

A radiation-hardened SOI-based FPGA

International Nuclear Information System (INIS)

Han Xiaowei; Wu Lihua; Zhao Yan; Li Yan; Zhang Qianli; Chen Liang; Zhang Guoquan; Li Jianzhong; Yang Bo; Gao Jiantou; Wang Jian; Li Ming; Liu Guizhai; Zhang Feng; Guo Xufeng; Chen, Stanley L.; Liu Zhongli; Yu Fang; Zhao Kai

2011-01-01

A radiation-hardened SRAM-based field programmable gate array VS1000 is designed and fabricated with a 0.5 μm partial-depletion silicon-on-insulator logic process at the CETC 58th Institute. The new logic cell (LC), with a multi-mode based on 3-input look-up-table (LUT), increases logic density about 12% compared to a traditional 4-input LUT The logic block (LB), consisting of 2 LCs, can be used in two functional modes: LUT mode and distributed read access memory mode. The hierarchical routing channel block and switch block can significantly improve the flexibility and routability of the routing resource. The VS1000 uses a CQFP208 package and contains 392 reconfigurable LCs, 112 reconfigurable user I/Os and IEEE 1149.1 compatible with boundary-scan logic for testing and programming. The function test results indicate that the hardware and software cooperate successfully and the VS1000 works correctly. Moreover, the radiation test results indicate that the VS1000 chip has total dose tolerance of 100 krad(Si), a dose rate survivability of 1.5 x 10 11 rad(Si)/s and a neutron fluence immunity of 1 x 10 14 n/cm 2 . (semiconductor integrated circuits)

The Electron Microscopy Outreach Program: A Web-based resource for research and education.

Science.gov (United States)

Sosinsky, G E; Baker, T S; Hand, G; Ellisman, M H

1999-01-01

We have developed a centralized World Wide Web (WWW)-based environment that serves as a resource of software tools and expertise for biological electron microscopy. A major focus is molecular electron microscopy, but the site also includes information and links on structural biology at all levels of resolution. This site serves to help integrate or link structural biology techniques in accordance with user needs. The WWW site, called the Electron Microscopy (EM) Outreach Program (URL: http://emoutreach.sdsc.edu), provides scientists with computational and educational tools for their research and edification. In particular, we have set up a centralized resource containing course notes, references, and links to image analysis and three-dimensional reconstruction software for investigators wanting to learn about EM techniques either within or outside of their fields of expertise. Copyright 1999 Academic Press.

Beam-hardening correction in CT based on basis image and TV model

International Nuclear Information System (INIS)

Li Qingliang; Yan Bin; Li Lei; Sun Hongsheng; Zhang Feng

2012-01-01

In X-ray computed tomography, the beam hardening leads to artifacts and reduces the image quality. It analyzes how beam hardening influences on original projection. According, it puts forward a kind of new beam-hardening correction method based on the basis images and TV model. Firstly, according to physical characteristics of the beam hardening an preliminary correction model with adjustable parameters is set up. Secondly, using different parameters, original projections are operated by the correction model. Thirdly, the projections are reconstructed to obtain a series of basis images. Finally, the linear combination of basis images is the final reconstruction image. Here, with total variation for the final reconstruction image as the cost function, the linear combination coefficients for the basis images are determined according to iterative method. To verify the effectiveness of the proposed method, the experiments are carried out on real phantom and industrial part. The results show that the algorithm significantly inhibits cup and strip artifacts in CT image. (authors)

Literature survey on phase composition of hardened cement paste containing fly ash

International Nuclear Information System (INIS)

Otsuka, Taku; Yamamoto, Takeshi

2015-01-01

The purpose of this literature survey is to collect the knowledge on the effect of fly ash in hardened cement paste and the information about evaluation of physicochemical performance based on phase composition of hardened cement paste. The performance of hardened cement paste containing fly ash is affected by the property of fly ash, hydration of cement and pozzolanic reaction of fly ash. Some properties of fly ash such as density and chemical composition are reflected in phase composition, showing the progress of cement hydration and pozzolanic reaction. Therefore clarification of the relationship of phase composition and performance will lead to appropriate evaluation of the property of fly ash. The amount of pore, chemical shrinkage, pore solution, compressive strength, Young modulus and alkali silica reaction have relations to the phase composition of hardened cement paste. It is considered as future subject to clarify the relationship of phase composition and performance for various properties of fly ash. (author)

RHOBOT: Radiation hardened robotics

Energy Technology Data Exchange (ETDEWEB)

Bennett, P.C.; Posey, L.D. [Sandia National Labs., Albuquerque, NM (United States)

1997-10-01

A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program.

RHOBOT: Radiation hardened robotics

International Nuclear Information System (INIS)

Bennett, P.C.; Posey, L.D.

1997-10-01

A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program

Technical Communicator: A New Model for the Electronic Resources Librarian?

Science.gov (United States)

Hulseberg, Anna

2016-01-01

This article explores whether technical communicator is a useful model for electronic resources (ER) librarians. The fields of ER librarianship and technical communication (TC) originated and continue to develop in relation to evolving technologies. A review of the literature reveals four common themes for ER librarianship and TC. While the…

Numerical analysis of drilling hole work-hardening effects in hole-drilling residual stress measurement

Science.gov (United States)

Li, H.; Liu, Y. H.

2008-11-01

The hole-drilling strain gage method is an effective semi-destructive technique for determining residual stresses in the component. As a mechanical technique, a work-hardening layer will be formed on the surface of the hole after drilling, and affect the strain relaxation. By increasing Young's modulus of the material near the hole, the work-hardening layer is simplified as a heterogeneous annulus. As an example, two finite rectangular plates submitted to different initial stresses are treated, and the relieved strains are measured by finite element simulation. The accuracy of the measurement is estimated by comparing the simulated residual stresses with the given initial ones. The results are shown for various hardness of work-hardening layer. The influence of the relative position of the gages compared with the thickness of the work-hardening layer, and the effect of the ratio of hole diameter to work-hardening layer thickness are analyzed as well.

Radiation hardening of oxygen-doped niobium by 14-MeV neutrons

International Nuclear Information System (INIS)

Bradley, E.R.; Jones, R.H.

1983-09-01

The flow properties of niobium containing 185 and 480 wt ppM oxygen have been studied following irradiation at 300K with T(d,n) neutrons to fluence levels ranging from 6 x 10 20 to 2 x 10 22 m -2 . Two hardening stages connected by a plateau region were observed in the niobium containing 185 wt ppM oxygen. Increasing the oxygen content by 300 wt ppM oxygen shifted the beginning of the high-fluence hardening stage from 6 x 10 21 to 1 x 10 21 m -2 , thereby eliminating the plateau region. This shift resulted in 1.5 times more hardening in the oxygen-doped niobium irradiated to fluence levels above 5 x 10 21 m -2

Characterization of the work hardening structure of austenitic steels by X-ray diffraction. Application to the determination of work hardening gradients and the study of recovery

International Nuclear Information System (INIS)

Cadalbert, Robert; Baron, J.L.

1977-01-01

A method has been developed to determine quantitatively the work hardening of austenitic steels by measurement of the broadening of X-ray diffraction lines. This simple, rapid, accurate and sensible method enables to determine work hardening variations in the thickness of a material. The complete automation of the measurement cycle using a small computer enables to carry out numerous determinations and to process data with accuracy. The unit developed is well adapted to the testing of metallic materials. It is also possible with this method to study the evolution of work hardening in a metal as a function of heat treatments. For instance, the determination of the recovery curves of the crystal lattice in austenitic steels allows to investigate the influence of additions (Mo, Ti) on the recovery kinetics [fr

DEVELOPMENT AND RESEARCH OF ULTRASONIC OSCILLATORY SYSTEM FOR HARDENING OF SPRING PLATE BILLETS

Directory of Open Access Journals (Sweden)

V. A. Tomilo

2015-01-01

Full Text Available Various schemes of ultrasonic oscillatory system are developed: with a «force nonsensitive» support, with a «force sensitive» support, with the deforming steel balls in bulk. Results of the ultrasonic treatment showed that hardening of a surface of the samples took place when the vibration amplitude of a radiator exceeds a certain level. The level of hardening increases with increase in amplitude of fluctuations of a radiator. Higher level of hardening is registered when the surface is treated by steel balls.

Temperature dependence of work hardening in sparsely twinning zirconium

International Nuclear Information System (INIS)

Singh, Jaiveer; Mahesh, S.; Roy, Shomic; Kumar, Gulshan; Srivastava, D.; Dey, G.K.; Saibaba, N.; Samajdar, I.

2017-01-01

Fully recrystallized commercial Zirconium plates were subjected to uniaxial tension. Tests were conducted at different temperatures (123 K - 623 K) and along two plate directions. Both directions were nominally unfavorable for deformation twinning. The effect of the working temperature on crystallographic texture and in-grain misorientation development was insignificant. However, systematic variation in work hardening and in the area fraction and morphology of deformation twins was observed with temperature. At all temperatures, twinning was associated with significant near boundary mesoscopic shear, suggesting a possible linkage with twin nucleation. A binary tree based model of the polycrystal, which explicitly accounts for grain boundary accommodation and implements the phenomenological extended Voce hardening law, was implemented. This model could capture the measured stress-strain response and twin volume fractions accurately. Interestingly, slip and twin system hardness evolution permitted multiplicative decomposition into temperature-dependent, and accumulated strain-dependent parts. Furthermore, under conditions of relatively limited deformation twinning, the work hardening of the slip and twin systems followed two phenomenological laws proposed in the literature for non-twinning single-phase face centered cubic materials.

Residual stress analysis of drive shafts after induction hardening

Energy Technology Data Exchange (ETDEWEB)

Lemos, Guilherme Vieira Braga; Rocha, Alexandre da Silva; Nunes, Rafael Menezes, E-mail: lemos_gl@yahoo.com.br [Universidade Federal do Rio Grande do Sul (UFRS), Porto Algre, RS (Brazil); Hirsch, Thomas Karl [Stiftung Institut für Werkstofftechnik (IWT), Bremen (Germany)

2014-08-15

Typically, for automotive shafts, shape distortion manifests itself in most cases after the induction hardening by an effect known as bending. The distortion results in a boost of costs, especially due to machining parts in the hardened state to fabricate its final tolerances. In the present study, residual stress measurements were carried out on automotive drive shafts made of DIN 38B3 steel. The samples were selected in consequence of their different distortion properties by an industrial manufacturing line. One tested shaft was straightened, because of the considerable dimensional variation and the other one not. Firstly, the residual stress measurements were carried out by using a portable diffractometer, in order to avoid cutting the shafts and evaluate the original state of the stresses, and afterwards a more detailed analysis was realized by a conventional stationary diffractometer. The obtained results presented an overview of the surface residual stress profiles after induction hardening and displayed the influence of the straightening process on the redistribution of residual stresses. They also indicated that the effects of the straightening in the residual stresses cannot be neglected. (author)

The natural aging and precipitation hardening behaviour of Al-Mg-Si-Cu alloys with different Mg/Si ratios and Cu additions

Energy Technology Data Exchange (ETDEWEB)

Ding, Lipeng [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 China (China); Jia, Zhihong, E-mail: zhihongjia@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 China (China); Zhang, Zhiqing; Sanders, Robert E.; Liu, Qing [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 China (China); Yang, Guang [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Centre for Dielectric Research, Xi’an Jiaotong University, Xi’an 710049 (China)

2015-03-11

The natural aging and artificial aging behaviours of Al-Mg-Si-Cu alloys with different Mg/Si ratios and Cu additions were investigated using Vickers microhardness measurements, differential scanning calorimetry (DSC) analysis and transmission electron microscopy (TEM) characterisation. Excess Si and Cu additions enhanced the alloy hardening ability during natural (NA) and artificial aging (AA). Alloys with low Cu and high Si contents exhibited higher precipitation hardening than alloys rich in Mg during artificial aging. In contrast, the alloys with high amounts of Cu were less dependent on the Mg/Si ratio during precipitation hardening due to their similar aging kinetics. The main precipitate phases that contributed to the peak-aging hardness were the L, Q′ and β″ phases. In the over-aging conditions, the alloys rich in Mg and Cu had finer and more numerous precipitates than their Si-rich equivalents due to the preferential precipitation of the L phase. The combination of excess Mg and high Cu resulted in an alloy with a relatively low hardness in T4 temper and a relatively higher hardness after the paint baking cycle. Thus, this alloy has good potential for use in auto body panel applications.

BUSFET - A Novel Radiation-Hardened SOI Transistor

International Nuclear Information System (INIS)

Dodd, P.E.; Draper, B.L.; Schwank, J.R.; Shaneyfelt, M.R.

1999-01-01

A partially-depleted SOI transistor structure has been designed that does not require the use of specially-processed hardened buried oxides for total-dose hardness and maintains the intrinsic SEU and dose rate hardness advantages of SOI technology

Hardening in AlN induced by point defects

International Nuclear Information System (INIS)

Suematsu, H.; Mitchell, T.E.; Iseki, T.; Yano, T.

1991-01-01

Pressureless-sintered AIN was neutron irradiated and the hardness change was examined by Vickers indentation. The hardness was increased by irradiation. When the samples were annealed at high temperature, the hardness gradually decreased. Length was also found to increase and to change in the same way as the hardness. A considerable density of dislocation loops still remained, even after the hardness completely recovered to the value of the unirradiated sample. Thus, it is concluded that the hardening in AIN is caused by isolated point defects and small clusters of point defects, rather than by dislocation loops. Hardness was found to increase in proportion to the length change. If the length change is assumed to be proportional to the point defect density, then the curve could be fitted qualitatively to that predicted by models of solution hardening in metals. Furthermore, the curves for three samples irradiated at different temperatures and fluences are identical. There should be different kinds of defect clusters in samples irradiated at different conditions, e.g., the fraction of single point defects is the highest in the sample irradiated at the lowest temperature. Thus, hardening is insensitive to the kind of defects remaining in the sample and is influenced only by those which contribute to length change

Work hardening and plastic equation of state of tantalum

International Nuclear Information System (INIS)

Gypen, L.A.; Aernoudt, E.; Deruyttere, A.

1983-01-01

The influence of cold deformation on the thermal and athermal components of the flow stress of tantalum was investigated. Up to high deformation levels the strain hardening is due only to the development of internal stress fields; the effective stress remains almost constant. The athermal strain hardening of tantalum is parabolic at low deformation levels (epsilon < 0.5) and linear at high deformation levels, as for other bcc metals. Hart's plastic equation of state is shown to be valid for tantalum at room temperature in the whole deformation range investigated (from epsilon = 0.005 to epsilon = 2.8). (author)

MODEL OF AN ELECTRONIC EDUCATIONAL RESOURCE OF NEW GENERATION

Directory of Open Access Journals (Sweden)

Anatoliy V. Loban

2016-01-01

Full Text Available The mathematical structure of the modular architecture of an electronic educational resource (EER of new generation, which allows to decompose the process of studying the subjects of the course at a hierarchically ordered set of data (knowledge and procedures for manipulating them, to determine the roles of participants of process of training of and technology the development and use of EOR in the study procrate.

Specific features of precipitation hardening of austenitic steels with various base. 2. Kinetics and mechanism of carbide precipitation

International Nuclear Information System (INIS)

Kositsyna, I.I.; Sagaradze, V.V.; Khakimova, O.N.

1997-01-01

Electron microscopic studies were carried out to determine the kinetics and mechanisms of precipitation hardening in Fe-Mn, Fe-Mn-Cr, Fe-Cr-Mn-N, Fe-Cr-Ni and Fe-Ni base stainless steels (45G20M2F2, 50Kh16G15N6M2F2, 45Kh18N10G10M2F2, 40Kh18Ni18M2F2, 45N26M2F2). The steels were heat treated under various conditions. It is revealed that in manganese steels the particles of vanadium carbide nucleate according to homogeneous mechanism at all aging temperatures (600-750 deg C). The presence of chromium in the matrix promotes the transition to heterogeneous mechanism of carbide nucleation and growth. With nickel content increasing the plasticity of precipitation hardened steels gets better due to more intense diffusion of atoms and vacancies to grain boundaries and, hence, the widening of near-boundary zones free of carbide particles

Ferrous arrowheads and their oil quench hardening: Some early Indian evidence

Science.gov (United States)

Dube, R. K.

2008-05-01

A wide variety of ferrous arrowheads were in use in ancient India. Several typical chemical analyses of arrowheads found from archaeological excavation carried out at Kaushambi are reported in this paper. The average carbon content of these arrowheads varied from as low as 0.1 wt.% to approximately 0.9 wt.%. Literary evidence for oil quench hardening of ferrous arrowheads, as reported in famous Sanskrit epics—the Rāmāyana and the Mahābhārata—have been discussed in this paper. This type of quench hardening was intentionally adopted as it helped in preventing distortion and formation of quench cracks in arrowheads. The oil quench-hardened arrowheads were rubbed on stones to sharpen them, which also brought about tempering of martensite due to frictional heat.

Strain hardening behavior and microstructural evolution during plastic deformation of dual phase, non-grain oriented electrical and AISI 304 steels

Energy Technology Data Exchange (ETDEWEB)

Soares, Guilherme Corrêa; Gonzalez, Berenice Mendonça; Arruda Santos, Leandro de, E-mail: leandro.arruda@demet.ufmg.br

2017-01-27

Strain hardening behavior and microstructural evolution of non-grain oriented electrical, dual phase, and AISI 304 steels, subjected to uniaxial tensile tests, were investigated in this study. Tensile tests were performed at room temperature and the strain hardening behavior of the steels was characterized by three different parameters: modified Crussard–Jaoul stages, strain hardening rate and instantaneous strain hardening exponent. Optical microscopic analysis, X-ray diffraction measurements, phase quantification by Rietveld refinement and hardness tests were also carried out in order to correlate the microstructural and mechanical responses to plastic deformation. Distinct strain hardening stages were observed in the steels in terms of the instantaneous strain hardening exponent and the strain hardening rate. The dual phase and non-grain oriented steels exhibited a two-stage strain hardening behavior while the AISI 304 steel displayed multiple stages, resulting in a more complex strain hardening behavior. The dual phase steels showed a high work hardening capacity in stage 1, which was gradually reduced in stage 2. On the other hand, the AISI 304 steel showed high strain hardening capacity, which continued to increase up to the tensile strength. This is a consequence of its additional strain hardening mechanism, based on a strain-induced martensitic transformation, as shown by the X-ray diffraction and optical microscopic analyses.

Segregation assisted microtwinning during creep of a polycrystalline L12-hardened Co-base superalloy

International Nuclear Information System (INIS)

Freund, Lisa P.; Messé, Olivier M.D.M.; Barnard, Jonathan S.; Göken, Mathias; Neumeier, Steffen; Rae, Catherine M.F.

2017-01-01

A polycrystalline L1 2 -hardened Co-base superalloy was creep deformed at 750 °C. The investigation of the deformed microstructure in the transmission electron microscope revealed microtwinning to be the prevailing deformation mechanism. The detected twins spanned the entire grain and cut through both, γ and γ′. Detailed high-resolution transmission electron microscopy investigations indicated that twin growth takes place by the slip of single a/6 〈112〉 partial dislocations along the twin boundary. Further analysis of the twin boundaries in the γ′ phase revealed segregation of elements known to decrease the stacking fault energy and a local depletion of γ′ forming elements. We propose that this segregation behavior enables subsequent a/6〈112〉 dislocations to easily slip along the twin boundary and further thicken the twins in the process.

Significance of rate of work hardening in tempered martensite embrittlement

International Nuclear Information System (INIS)

Pietikainen, J.

1995-01-01

The main explanations for tempered martensite embrittlement are based on the effects of impurities and cementite precipitation on the prior austenite grain boundaries. There are some studies where the rate of work hardening is proposed as a potential reason for the brittleness. One steel was studied by means of a specially developed precision torsional testing device. The test steel had a high Si and Ni content so ε carbide and Fe 3 C appear in quite different tempering temperature ranges. The M S temperature is low enough so that self tempering does not occur. With the testing device it was possible to obtain the true stress - true strain curves to very high deformations. The minimum toughness was always associated with the minimum of rate of work hardening. The change of deformed steel volume before the loss of mechanical stability is proposed as at least one reason for tempered martensite embrittlement. The reasons for the minimum of the rate of work hardening are considered. (orig.)

Precipitation hardening of cast Zr-containing A356 aluminium alloy

International Nuclear Information System (INIS)

Baradarani, B.; Raiszadeh, R.

2011-01-01

The effect of small additions of zirconium on the hardness, grain size, precipitate type and size of cast A356 aluminium alloy was investigated. The cast alloys were solution treated and then artificially aged for different periods of time. Hardness tests and scanning electron microscope (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) studies were carried out on the as-cast, as-solutionised and age-hardened specimens. Incoherent, coarse Al 3 Zr particles formed in the microstructure during the solidification of the alloy and caused grain refinement in the as-cast structure. These particles dissolved and reprecipitated as smaller-size particles during the solution treatment, causing the hardness of the alloy to remain constant at high temperatures for long periods of time due to the slow diffusion of Zr in the α-Al.

Study of a design criterion for 316L irradiated represented by a strain hardened material

International Nuclear Information System (INIS)

Gouin, H.

1999-01-01

The aim of this study is to analyse the consequence of radiation on different structure submitted to imposed displacement loading and for damages due to plastic instability or rupture. The main consequence of radiation is a material hardening with a ductility decrease. This effect is similar to initial mechanical hardening: the mechanical properties (determined on smooth tensile specimen) evolve in the same way while irradiation or mechanical hardening increase. So in this study, radiation hardening is simulated by mechanical hardening (swaging). Tests were carried out for which two damages were considered: plastic instability and rupture. These two damages were studied with initial mechanical hardening (5 tested hammering rate 0, 15, 25, 35 and 45% on 316L stainless steel). Likewise two types of loading were studied: tensile or bending loading on specimens with or without geometrical singularities (notches). From tensile tests, two deformation criteria are proposed for prevention against the two quoted damages. Numerical study is carried out allowing to confirm hypothesis made at the time of the tensile test result interpretation and to validate the rupture criterion by applying on bending test. (author)

Method of case hardening depth testing by using multifunctional ultrasonic testing instrument

International Nuclear Information System (INIS)

Salchak, Y A; Sednev, D A; Ardashkin, I B; Kroening, M

2015-01-01

The paper describes usability of ultrasonic case hardening depth control applying standard instrument of ultrasonic inspections. The ultrasonic method of measuring the depth of the hardened layer is proposed. Experimental series within the specified and multifunctional ultrasonic equipment are performed. The obtained results are compared with the results of a referent method of analysis. (paper)

Effect of pre-hardening on the lifetime of type 304L austenitic stainless steels

International Nuclear Information System (INIS)

Kpodekon, C.

2010-01-01

This study deals with the effect of the loading history on the cyclic behavior and the fatigue life of two kinds (THYSSEN and CLI) of 304L stainless steel at room temperature. The experiments have been performed using two specimens' categories. The first one (virgin) has been submitted to only classical fatigue tests while in the second category, prior to the fatigue test, the specimen is subjected to a pre-hardening process under either monotonic or cyclic strain control. Cyclic softening followed by cyclic hardening are observed for the virgin specimens while only cyclic softening is exhibited by the pre-hardened specimens. The obtained results show that fatigue life is strongly influenced by the pre-hardening: it seems beneficial under stress control but detrimental under strain control, even in the presence of a compressive mean stress. The results are discussed regarding the cyclic evolution of the elastic modulus as well as the isotropic and kinematic parts of the strain hardening, and strain energy density per cycle, in different configurations: with or without prehardening,stress or strain control. (author)

Age hardening in mechanically alloyed Al-Mg-Li-C-O

Energy Technology Data Exchange (ETDEWEB)

Papazian, J.M. (Corporate Research Center, Grumman Corporation, Bethpage, NY (USA)); Gilman, P. (Allied-Signal Inc., Morristown, NJ (USA))

1990-05-01

The age-hardening behavior of a series of mechanically alloyed Al-Mg-Li-C-O alloys containing 3.0-4.0 wt.% Mg and 1.3-1.75 wt.% Li was studied using hardness tests, differential scanning calorimetry (DSC) and transmission electron microscopy. The hardness tests showed an increased hardness after 100degC aging in all the alloys containing at least 1.5 at.% Li. Likewise, the calorimetry results showed the presence of pronounced precipitate dissolution peaks in these same alloys after 100degC aging. The volume fraction of precipitates formed (as measured by the dissolution enthalpies of the DSC peaks) increased systematically with increasing solute content. Transmission electron microscopy after 100 and 190degC aging showed images and diffraction spots similar to those of {delta}' (Al{sub 3}Li). Comparison of the DSC results with results from binary Al-Li and Al-Mg alloys indicated that the precipitates formed in the Al-Mg-Li-C-O alloys were similar to those formed in binary Al-Li alloys, and that the primary role of the magnesium was to lower the solid solubility of lithium. (orig.).

Effect of solute elements on hardening of thermally-aged RPV model alloys

International Nuclear Information System (INIS)

Nomoto, A.; Nishida, K.; Dohi, K.; Soneda, N.; Liu, L.; Sekimura, N.; Li, Z.

2015-01-01

Embrittlement correlation methods for irradiated reactor pressure vessel (RPV) steels have been developed worldwide to predict the amount of embrittlement during plant operation. The effect of chemical composition on embrittlement is not fully understood, particularly the process of solute atom behavior during solute atom formation. In this series of slides we report the results of thermal ageing experiments of RPV model alloys in order to obtain information on the effect of chemical composition on the hardening process. We can draw the following conclusions. First, the addition of Ni or Si alone to Fe-Cu model alloys does not have clear effect but the addition of Mn to Fe-Cu-Ni alloy accelerates the cluster formation and hardening drastically, the effect of composition on the cluster strength is not clear. Secondly, the hardening process before the hardening peak has linear correlation with APT (Atom Probe Tomography) results and the RSS (Root-Sum-Square)sum model seems to explain the relationship between increase in hardness and APT data in a more consistent manner

Comparison of hardenability calculation methods of the heat-treatable constructional steels

Energy Technology Data Exchange (ETDEWEB)

Dobrzanski, L.A.; Sitek, W. [Division of Tool Materials and Computer Techniques in Metal Science, Silesian Technical University, Gliwice (Poland)

1995-12-31

Evaluation has been made of the consistency of calculation of the hardenability curves of the selected heat-treatable alloyed constructional steels with the experimental data. The study has been conducted basing on the analysis of present state of knowledge on hardenability calculation employing the neural network methods. Several calculation examples and comparison of the consistency of calculation methods employed are included. (author). 35 refs, 2 figs, 3 tabs.

Synthesis of a new hardener agent for self-healing epoxy resins

Science.gov (United States)

Raimondo, Marialuigia; Guadagno, Liberata; Naddeo, Carlo; Longo, Pasquale; Mariconda, Annaluisa; Agovino, Anna

2014-05-01

Actually, the development of smart composites capable of self-repair in aeronautical structures is still at the planning stage owing to complex issues to overcome. One of the critical points in the development of self-healing epoxy resin is related to the impossibility to employ primary amines as hardeners. In this paper, the synthesis of a new hardener for self-healing resins is shown together with applicability conditions/ranges.

BUSFET -- A radiation-hardened SOI transistor

International Nuclear Information System (INIS)

Schwank, J.R.; Shaneyfelt, M.R.; Draper, B.L.; Dodd, P.E.

1999-01-01

The total-dose hardness of SOI technology is limited by radiation-induced charge trapping in gate, field, and SOI buried oxides. Charge trapping in the buried oxide can lead to back-channel leakage and makes hardening SOI transistors more challenging than hardening bulk-silicon transistors. Two avenues for hardening the back-channel are (1) to use specially prepared SOI buried oxides that reduce the net amount of trapped positive charge or (2) to design transistors that are less sensitive to the effects of trapped charge in the buried oxide. In this work, the authors propose a partially-depleted SOI transistor structure for mitigating the effects of trapped charge in the buried oxide on radiation hardness. They call this structure the BUSFET--Body Under Source FET. The BUSFET utilizes a shallow source and a deep drain. As a result, the silicon depletion region at the back channel caused by radiation-induced charge trapping in the buried oxide does not form a conducting path between source and drain. Thus, the BUSFET structure design can significantly reduce radiation-induced back-channel leakage without using specially prepared buried oxides. Total dose hardness is achieved without degrading the intrinsic SEU or dose rate hardness of SOI technology. The effectiveness of the BUSFET structure for reducing total-dose back-channel leakage depends on several variables, including the top silicon film thickness and doping concentration, and the depth of the source. 3-D simulations show that for a body doping concentration of 10 18 cm -3 , a drain bias of 3 V, and a source depth of 90 nm, a silicon film thickness of 180 nm is sufficient to almost completely eliminate radiation-induced back-channel leakage. However, for a doping concentration of 3 x 10 17 cm -3 , a thicker silicon film (300 nm) must be used

Coatings hardenable by ionizing radiation and their applications

International Nuclear Information System (INIS)

Aronoff, E.J.; Labana, S.S.

1976-01-01

The invention deals with the production of a coating medium which can be hardened by ionizing radiation. The composition includes tetravinyl compounds containing no free hydroxyl groups which were obtained by the conversion of di-epoxides with acryl or methacryl acid via the intermediary step of a divinyl ester condensation product. The intermediary product is converted with acryloyl or methacryloyl halides. The mass still contains non-polymerisable solvent (such as tolual, xylol), pigments and fillers. It is of advantage if the di-epoxide has a molecular weight of 140 to 500. Furthermore, coatings are to be made of this coating medium which are hardened by ionizing radiation at temperatures between 20 0 C and 70 0 C. 19 examples. (HK) [de

An outbreak of contact dermatitis from toluenesulfonamide formaldehyde resin in a nail hardener

NARCIS (Netherlands)

de Wit, F. S.; de Groot, A. C.; Weyland, J. W.; Bos, J. D.

1988-01-01

8 cases of contact dermatitis from toluenesulfonamide formaldehyde resin in a nail hardener are presented. Most patients had used nail lacquers containing this resin for many years without trouble, but became sensitized to the resin shortly after the introduction of this particular nail hardener. A

Compression of pulsed electron beams for material tests

Science.gov (United States)

Metel, Alexander S.

2018-03-01

In order to strengthen the surface of machine parts and investigate behavior of their materials exposed to highly dense energy fluxes an electron gun has been developed, which produces the pulsed beams of electrons with the energy up to 300 keV and the current up to 250 A at the pulse width of 100-200 µs. Electrons are extracted into the accelerating gap from the hollow cathode glow discharge plasma through a flat or a spherical grid. The flat grid produces 16-cm-diameter beams with the density of transported per one pulse energy not exceeding 15 J·cm-2, which is not enough even for the surface hardening. The spherical grid enables compression of the beams and regulation of the energy density from 15 J·cm-2 up to 15 kJ·cm-2, thus allowing hardening, pulsed melting of the machine part surface with the further high-speed recrystallization as well as an explosive ablation of the surface layer.

Nonlinear response to the multiple sine wave excitation of a softening--hardening system

International Nuclear Information System (INIS)

Koplik, B.; Subudhi, M.; Curreri, J.

1979-01-01

In studying the earthquake response of the HTGR core, it was observed that the system can display softening--hardening characteristics. This is of great consequence in evaluating the structural safety aspects of the core. In order to obtain a better understanding of the governing parameters, an investigation was undertaken with a single-degree-of-freedom system having a softening--hardening spring characteristic and excited by multiple sine waves. A parametric study varying the input amplitudes and the spring characteristic was performed. Transients were introduced into the system, and the jump phenomena between the lower softening characteristics to the higher hardening curve was studied

Deep Drawing Simulation Of High And Ultrahigh Strength Steels Under Consideration Of Anisotropic Hardening

International Nuclear Information System (INIS)

Roll, Karl; Faust, Alexander; Kessler, Lutz

2007-01-01

In today's sheet metal forming simulation, most attention is paid to yield loci functions, which describe the anisotropy of the material in yielding. The coefficients, defining the shape of the yield locus in these functions are usually fitted at a certain level of plastic work and are then valid for the whole range of plastic deformation. Modern high and ultrahigh strength steels, especially those with induced plasticity, may often exhibit only a very small anisotropy in yielding, but a severe anisotropy in work hardening for different loading conditions. This behavior can not be described by fitting the yield locus at a specific value of plastic deformation. An approach to take into account the anisotropic hardening of sheet metals is to provide different yield curves for several loading conditions and expand the yield locus dependent on the current form of load. By doing this, one can use a comparatively simple yield locus, like that of Hill from 1948, because all anisotropy is given by the different hardening curves. For the commercial FEM code LS DYNA the material model MATFEM Generalized Yield is available as a user subroutine, which supports this approach. In this paper, forming simulation results of different yield loci are compared with experimental results. The simulations were carried out in LS-DYNA with the Barlat 89 and 2000 yield loci and isotropic hardening and with the GenYld model combining a Hill 48 yield locus and anisotropic hardening. The deep drawing experiments were conducted on a hydraulic press, measuring binder and punch forces. The deformation of the sheet was measured by optical grid analysis. A comparison of the simulated and measured plastic strains shows that using a model including anisotropic hardening can produce better results than the usage of a complex yield locus but isotropic hardening for the examined materials. This might be interesting for e.g. spring back simulations. By combining a simple yield locus with anisotropic

Method for surface treatment by electron beams

International Nuclear Information System (INIS)

Panzer, S.; Doehler, H.; Bartel, R.; Ardenne, T. von.

1985-01-01

The invention has been aimed at simplifying the technology and saving energy in modifying surfaces with the aid of electron beams. The described beam-object geometry allows to abandon additional heat treatments. It can be used for surface hardening

Importance of calcium and magnesium in water - water hardening

Science.gov (United States)

Barloková, D.; Ilavský, J.; Kapusta, O.; Šimko, V.

2017-10-01

Basic information about importance of calcium and magnesium in water, about their properties, effect to human health, problems what can cause under the lower ( 5 mmol/L) concentrations in water supply distribution systems, the most commonly used methods of water hardening are presented. The article contains the water hardening results carried out during the pilot plant experiments in WTP Hriňová and WTP Turček. For water hardening, treated water at the end of the process line, i.e., after coagulation, sedimentation and filtration, saturated with CO2 and filtrated through half-burnt dolomite material (PVD) was used. The results show that the filtration rate is 17.1 m/h in the case of WTP Hriňová and 15.2 m/h in the case of WTP Turček to achieve the recommended concentration of Ca and Mg in the treated water after the addition of CO2 and filtration through PVD. The longer the water contact time with PVD (depending on the CO2 content), the more water is enriched with magnesium, but the calcium concentration has not so much increased.

On the grain boundary hardening in a B-bearing 304 austenitic stainless steel

International Nuclear Information System (INIS)

Yao, X.X.

1999-01-01

The precipitates, (Cr,Fe) 23 (C,B) 6 carbides and (Cr,Fe) 2 B borides, formed along the grain boundaries in a 304 austenitic stainless steel containing boron of 33 ppm after solution treatment at 1100 C for 1 h followed by isothermal ageing for 0.5 h at temperatures ranging from 750 to 1050 C have been identified. The influence of these precipitates on the grain boundary hardening has been investigated by means of micro-Vickers hardness measurements. It is found that the degree of grain boundary hardening below 900 C decreases, while it increases above 900 C with increasing ageing temperature. The dissolution of (Cr,Fe) 23 (C,B) 6 carbides and the precipitation of (Cr,Fe) 2 B borides are associated with the changes of grain boundary hardening in this B-bearing 304 austenitic stainless steel between 750 and 1100 C. The non-equilibrium boron segregation enhances the grain boundary hardening when the ageing temperature is above 900 C. (orig.)

Plastic limit analysis with non linear kinematic strain hardening for metalworking processes applications

International Nuclear Information System (INIS)

Chaaba, Ali; Aboussaleh, Mohamed; Bousshine, Lahbib; Boudaia, El Hassan

2011-01-01

Limit analysis approaches are widely used to deal with metalworking processes analysis; however, they are applied only for perfectly plastic materials and recently for isotropic hardening ones excluding any kind of kinematic hardening. In the present work, using Implicit Standard Materials concept, sequential limit analysis approach and the finite element method, our objective consists in extending the limit analysis application for including linear and non linear kinematic strain hardenings. Because this plastic flow rule is non associative, the Implicit Standard Materials concept is adopted as a framework of non standard plasticity modeling. The sequential limit analysis procedure which considers the plastic behavior with non linear kinematic strain hardening as a succession of perfectly plastic behavior with yielding surfaces updated after each sequence of limit analysis and geometry updating is applied. Standard kinematic finite element method together with a regularization approach is used for performing two large compression cases (cold forging) in plane strain and axisymmetric conditions

Thermal stress ratcheting analysis of a time-hardening structure

International Nuclear Information System (INIS)

Hada, Kazuhiko

1999-01-01

Thermal stress ratcheting and shakedown is analyzed for a time-hardening structure: the yield stress increases as time goes on under exposure to neutron irradiation or thermal aging. New three modes of ratcheting and shakedown are identified as transition to other deformation modes. Stress regimes and thermal ratchet strains are formulated as a function of time-increasing yield stress. Moreover, a new model of trouble occurrence frequency as a modification to a bath-tube curve is proposed for calculating a time period of a thermal cycle. Application of the proposed formulation tells us a benefit of taking into account the time hardening due to neutron irradiation. (author)

Recent developments in turning hardened steels - A review

Science.gov (United States)

Sivaraman, V.; Prakash, S.

2017-05-01

Hard materials ranging from HRC 45 - 68 such as hardened AISI H13, AISI 4340, AISI 52100, D2 STL, D3 STEEL Steel etc., need super hard tool materials to machine. Turning of these hard materials is termed as hard turning. Hard turning makes possible direct machining of the hard materials and also eliminates the lubricant requirement and thus favoring dry machining. Hard turning is a finish turning process and hence conventional grinding is not required. Development of the new advanced super hard tool materials such as ceramic inserts, Cubic Boron Nitride, Polycrystalline Cubic Boron Nitride etc. enabled the turning of these materials. PVD and CVD methods of coating have made easier the production of single and multi layered coated tool inserts. Coatings of TiN, TiAlN, TiC, Al2O3, AlCrN over cemented carbide inserts has lead to the machining of difficult to machine materials. Advancement in the process of hard machining paved way for better surface finish, long tool life, reduced tool wear, cutting force and cutting temperatures. Micro and Nano coated carbide inserts, nanocomposite coated PCBN inserts, micro and nano CBN coated carbide inserts and similar developments have made machining of hardened steels much easier and economical. In this paper, broad literature review on turning of hardened steels including optimizing process parameters, cooling requirements, different tool materials etc., are done.

Coefficient of work-hardening in stage-IV

CSIR Research Space (South Africa)

Nabarro, FRN

1994-04-15

Full Text Available The theory of work hardening in stage IV depends on the relation between the relative misorientation Psi of neighbouring subgrains and the plastic strain gamma (Psi = B gamma exp). The value of the constant B is suggested to be better related...

Influence of anisotropic hardening on longitudinal welding strains and stresses

International Nuclear Information System (INIS)

Gatovskij, K.M.; Revutskij, M.N.

1981-01-01

The algorithm and program for estimation of longitudinal welding strains and stresses with account of hardening and Bauschinger effect, which expand the possibilities of more complete description of stress change during thermodeformation welding cycles at bead surfacing on plate made of the 06Kh18N9T steel and AMg61 alloy. It is shown that for metals, deformation curves which are characterized by considerable yield moduli (Esub(T)/E>=0.05) hardening effect is considerable and its account leads to the decrease of stress level in the heataffected zone (down to 20%) [ru

Irradiation hardening and localized deformation of neutron-irradiated α-iron single crystals

International Nuclear Information System (INIS)

Mughrabi, H.; Stroehle, D.; Wilkens, M.

1981-01-01

The early yielding behaviour of neutron-irradiated α iron single crystals orientated for single slip was investigated as a function of neutron dose. In the range of neutron doses between approx. equal to 10 18 and approx. equal to 10 19 n/cm 2 , the irradiation hardening increment was found to be almost constant. Qualitative modifications of this behaviour were observed in the case of predeformed specimens. The localized deformation of the neutron-irradiated specimens by dislocation channelling was investigated by slip-line observations, transmission electron microscopy and X-ray topography. A model of localized deformation is proposed in order to explain the development of the observed asymmetric dislocation double layers which bound the channels and transmit characteristic misorientations. (orig.)

Radiation response of two Harris semiconductor radiation hardened 1k CMOS RAMs

International Nuclear Information System (INIS)

Abare, W.E.; Huffman, D.D.; Moffett, G.E.

1982-01-01

This paper describes the testing of two types 1K CMOS static RAMs in various transient and steady state ionizing radiation environments. Type HM 6551R (256x4 bits) and type HM 6508R (1024x1 bit) RAMs were evaluated. The RAMs are radiation hardened versions of Harris' commercial RAMs. A brief description of the radiation hardened process is presented

Effect of dynamic strain aging on isotropic hardening in low cycle fatigue for carbon manganese steel

International Nuclear Information System (INIS)

Huang, Zhi Yong; Chaboche, Jean-Louis; Wang, Qing Yuan; Wagner, Danièle; Bathias, Claude

2014-01-01

Carbon–manganese steel A48 (French standard) is used in steam generator pipes of nuclear reactor pressure vessels at high temperatures (about 200 °C). The steel is sensitive to dynamic strain aging in monotonic tensile test and low cycle fatigue test at certain temperature range and strain rate. Its isotropic hardening behavior observed from experiments has a hardening, softening and hardening evolution with the effect of dynamic strain aging. The isotropic hardening model is improved by coupling the dislocation and dynamic strain aging theory to describe the behavior of A48 at 200 °C

Effect of dynamic strain aging on isotropic hardening in low cycle fatigue for carbon manganese steel

Energy Technology Data Exchange (ETDEWEB)

Huang, Zhi Yong, E-mail: huangzy@scu.edu.cn [Sichuan University, School of Aeronautics and Astronautics, No. 29 Jiuyanqiao Wangjiang Road, Chengdu 610064 (China); Chaboche, Jean-Louis [ONERA, DMSM, 29 avenue de la Division Lecerc, F-92320 Chatillon (France); Wang, Qing Yuan [Sichuan University, School of Aeronautics and Astronautics, No. 29 Jiuyanqiao Wangjiang Road, Chengdu 610064 (China); Wagner, Danièle; Bathias, Claude [Université ParisOuest Nanterre La Défense (France)

2014-01-01

Carbon–manganese steel A48 (French standard) is used in steam generator pipes of nuclear reactor pressure vessels at high temperatures (about 200 °C). The steel is sensitive to dynamic strain aging in monotonic tensile test and low cycle fatigue test at certain temperature range and strain rate. Its isotropic hardening behavior observed from experiments has a hardening, softening and hardening evolution with the effect of dynamic strain aging. The isotropic hardening model is improved by coupling the dislocation and dynamic strain aging theory to describe the behavior of A48 at 200 °C.

Development of Test Method for Simple Shear and Prediction of Hardening Behavior Considering the Branchings Effect

International Nuclear Information System (INIS)

Kim, Dongwook; Bang, Sungsik; Kim, Minsoo; Lee, Hyungyil; Kim, Naksoo

2013-01-01

In this study we establish a process to predict hardening behavior considering the Branchings effect for zircaloy-4 sheets. When a metal is compressed after tension in forming, the yield strength decreases. For this reason, the Branchings effect should be considered in FE simulations of spring-back. We suggested a suitable specimen size and a method for determining the optimum tightening torque for simple shear tests. Shear stress-strain curves are obtained for five materials. We developed a method to convert the shear load-displacement curve to the effective stress-strain curve with Fea. We simulated the simple shear forward/reverse test using the combined isotropic/kinematic hardening model. We also investigated the change of the load-displacement curve by varying the hardening coefficients. We determined the hardening coefficients so that they follow the hardening behavior of zircaloy-4 in experiments

Development of Test Method for Simple Shear and Prediction of Hardening Behavior Considering the Branchings Effect

Energy Technology Data Exchange (ETDEWEB)

Kim, Dongwook; Bang, Sungsik; Kim, Minsoo; Lee, Hyungyil; Kim, Naksoo [Sogang Univ., Seoul (Korea, Republic of)

2013-10-15

In this study we establish a process to predict hardening behavior considering the Branchings effect for zircaloy-4 sheets. When a metal is compressed after tension in forming, the yield strength decreases. For this reason, the Branchings effect should be considered in FE simulations of spring-back. We suggested a suitable specimen size and a method for determining the optimum tightening torque for simple shear tests. Shear stress-strain curves are obtained for five materials. We developed a method to convert the shear load-displacement curve to the effective stress-strain curve with Fea. We simulated the simple shear forward/reverse test using the combined isotropic/kinematic hardening model. We also investigated the change of the load-displacement curve by varying the hardening coefficients. We determined the hardening coefficients so that they follow the hardening behavior of zircaloy-4 in experiments.

Plasma nitriding - an eco friendly surface hardening process

International Nuclear Information System (INIS)

Mukherjee, S.

2015-01-01

Surface hardening is a process of heating the metal such that the surface gets only hardened. This process is adopted for many components like gears, cams, and crankshafts, which desire high hardness on the outer surface with a softer core to withstand the shocks. So, to attain such properties processes like carburising, nitriding, flame hardening and induction hardening are employed. Amongst these processes nitriding is the most commonly used process by many industries. In nitriding process the steel material is heated to a temperature of around 550 C and then exposed to atomic nitrogen. This atomic nitrogen reacts with iron and other alloying elements and forms nitrides, which are very hard in nature. By this process both wear resistance and hardness of the product can be increased. The atomic nitrogen required for this process can be obtained using ammonia gas (gas nitriding), cyanide based salt bath (liquid nitriding) and plasma medium (plasma nitriding). However, plasma nitriding has recently received considerable industrial interest owing to its characteristic of faster nitrogen penetration, short treatment time, low process temperature, minimal distortion, low energy use and easier control of layer formation compared with conventional techniques such as gas and liquid nitriding. This process can be used for all ferrous materials including stainless steels. Plasma nitriding is carried out using a gas mixture of nitrogen and hydrogen gas at sub atmospheric pressures hence, making it eco-friendly in nature. Plasma nitriding allows modification of the surface layers and hardness profiles by changing the gas mixture and temperature. The wide applicable temperature range enables a multitude of applications, beyond the possibilities of gas or salt bath processes. This has led to numerous applications of this process in industries such as the manufacture of machine parts for plastics and food processing, packaging and tooling as well as pumps and hydraulic, machine

Applicability of Voce equation for tensile flow and work hardening behaviour of P92 ferritic steel

International Nuclear Information System (INIS)

Sainath, G.; Choudhary, B.K.; Christopher, J.; Isaac Samuel, E.; Mathew, M.D.

2015-01-01

Detailed analysis of true stress (σ)-true plastic strain (ε) data indicated that tensile flow behaviour of P92 ferritic steel can be adequately described by Voce equation at strain rates ranging from 3.16 × 10 −5 to 1.26 × 10 −3  s −1 over a temperature range 300–923 K. The steel exhibited two-stage work hardening in the variations of instantaneous work hardening rate (θ = dσ/dε) with stress. At all the strain rates, the variations in σ-ε, θ-σ and work hardening parameters associated with Voce equation with temperature exhibited three distinct temperature regimes. At intermediate temperatures, the variations in σ-ε, θ-σ and work hardening parameters with temperature and strain rate exhibited anomalous behaviour due to the occurrence of dynamic strain ageing in the steel. The shift in θ-σ towards low stresses, and rapid decrease in flow stress and work hardening parameters with increasing temperature and decreasing strain rate suggested dominance of dynamic recovery at high temperatures. - Highlights: • Tensile flow and work hardening behaviour of P92 steel has been examined. • Applicability of Voce equation to P92 steel is demonstrated. • Three temperature regimes in flow and work hardening has been observed. • Good match between predicted and the experimental tensile properties has been shown

Nanoparticle amount, and not size, determines chain alignment and nonlinear hardening in polymer nanocomposites

Science.gov (United States)

Varol, H. Samet; Meng, Fanlong; Hosseinkhani, Babak; Malm, Christian; Bonn, Daniel; Bonn, Mischa; Zaccone, Alessio

2017-01-01

Polymer nanocomposites—materials in which a polymer matrix is blended with nanoparticles (or fillers)—strengthen under sufficiently large strains. Such strain hardening is critical to their function, especially for materials that bear large cyclic loads such as car tires or bearing sealants. Although the reinforcement (i.e., the increase in the linear elasticity) by the addition of filler particles is phenomenologically understood, considerably less is known about strain hardening (the nonlinear elasticity). Here, we elucidate the molecular origin of strain hardening using uniaxial tensile loading, microspectroscopy of polymer chain alignment, and theory. The strain-hardening behavior and chain alignment are found to depend on the volume fraction, but not on the size of nanofillers. This contrasts with reinforcement, which depends on both volume fraction and size of nanofillers, potentially allowing linear and nonlinear elasticity of nanocomposites to be tuned independently. PMID:28377517

An energy-based beam hardening model in tomography

International Nuclear Information System (INIS)

Casteele, E van de; Dyck, D van; Sijbers, J; Raman, E

2002-01-01

As a consequence of the polychromatic x-ray source, used in micro-computer tomography (μCT) and in medical CT, the attenuation is no longer a linear function of absorber thickness. If this nonlinear beam hardening effect is not compensated, the reconstructed images will be corrupted by cupping artefacts. In this paper, a bimodal energy model for the detected energy spectrum is presented, which can be used for reduction of artefacts caused by beam hardening in well-specified conditions. Based on the combination of the spectrum of the source and the detector efficiency, the assumption is made that there are two dominant energies which can describe the system. The validity of the proposed model is examined by fitting the model to the experimental datapoints obtained on a microtomograph for different materials and source voltages

Niobium effects on the austenitic grain growth and hardenability of steels for mechanical construction

International Nuclear Information System (INIS)

Vieira, R.R.; Arruda Camargo, L.M. de; Oliveira Junior, G.G. de; Dias Filho, A.G.C.

1983-01-01

The austenitic grain growth and hardenability of SAE 86XX and 5120 steels modified with 0,001 to 0,20 per-cent niobium content were studied when submitted to case hardening and quenching heat treatments. The results show that niobium controlS the austenite grain size better than molybdenum up to 950 0 C austenitization temperature. The hardenability, evaluated by the Jominy test which the modified SAE 8640 steels, is more strongly inflencied by the grain refining resulting from niobium addition than by any other supposed effect. (Author) [pt

Hardened Solar Array High Temperature Adhesive.

Science.gov (United States)

1981-04-01

SHERWOOO. D SASIU.IS F3361S-0-C-201S UNCLASSI ED 1AC-SCG-IOOIIR AFVAL-TR-OL-201? NLm,,hinii EhhhEE11I1 AFWAL-TR-81- 2017 i : HARDENED SOLAR ARRAY D HIGH...Tg and as a consequence forms a film on the container and also precipitates as tacky waxlike particles, rather than the desired flocullated

Effect of Nonlinear Hardening of Lead Rubber Bearing on Long Term Behavior of Base Isolated Containment Building

International Nuclear Information System (INIS)

Park, Junhee; Choun, Young-Sun; Kim, Min-Kyu

2015-01-01

The rubber material used in laminated rubber bearings is the hyper elastic material whose stress-strain relationship can be defined as nonlinearly elastic. From the previous research, it was presented that the rubber hardness and stiffness was increased by the aging of LRB. The mechanical properties of LRB changed by aging can directly affect a nonlinear hardening behavior. Therefore it is needed to consider the nonlinear hardening effect for exactly evaluating the seismic safety of base isolated structure during the life time. In this study, the seismic response analysis of base isolated containment building was performed by using the bilinear model and the hardening model to identify the effect of structural response on the nonlinear hardening behavior of isolator. Moreover the floor response spectrum of base isolated structure considering the aging was analyzed by according to the analysis model of LRB.. The hardening behavior of lead rubber bearing occurs at high strain. Therefore it is reasonable to assume that the hysteretic model of LRB is the nonlinear hardening model for exactly evaluating the seismic response of base isolated structure. The nonlinear analysis of base isolated containment was performed by using the nonlinear hardening variables which was resulted from the test results and finite element analysis. From the analysis results, it was represented that the FRS was higher about 40% with nonlinear hardening model than with the bilinear model. Therefore the seismic response of base isolated structure with bilinear model can be underestimated than the real response. It is desired that the nonlinear hardening model of LRB is applied for the seismic risk evaluation requiring the ultimate state of LRB

Work hardening characteristics of gamma-ray irradiated Al-5356 alloy

International Nuclear Information System (INIS)

Saad, G.; Fayek, S.A.; Fawzy, A.; Soliman, H.N.; Nassr, E.

2014-01-01

Effects of γ-irradiation and deformation temperatures on the hardening behavior of Al-5356 alloy have been investigated by means of stress–strain measurements. Wire samples irradiated with different doses (ranging from 500 to 2000 kGy) were strained at different deformation temperatures T w (ranging from 303 to 523 K) and a constant strain rate of 1.5×10 −3 s −1 . The effect of γ-irradiation on the work-hardening parameters (WHP): yield stress σ y , fracture stress σ f , total strain ε T and work-hardening coefficient χ p of the given alloy was studied at the applied deformation temperature range. The obtained results showed that γ-irradiation exhibited an increase in the WHP of the given alloy while the increase in its deformation temperature showed a reverse effect. The mean activation energy of the deformation process was calculated using an Arrhenius-type relation, and was found to be ∼80 kJ/mole, which is close to that of grain boundary diffusion in aluminum alloys

GUIDELINES FOR EVALUATION OF PSYCHOLOGICAL AND PEDAGOGICAL QUALITY CHARACTERISTICS OF ELECTRONIC EDUCATIONAL RESOURCES

Directory of Open Access Journals (Sweden)

Galina P. Lavrentieva

2014-05-01

Full Text Available The article highlights the causes of insufficient effective use of electronic learning resources and sets out the guidelines on ways to solve the aforementioned problems. The set of didactic, methodical, psychological, pedagogical, design and ergonomic quality requirements is considered for evaluation, selection and application of information and communication technologies in the educational process. The most appropriate mechanisms for the ICT introduction into the learning process are disclosed as it should meet the specific learning needs of the student and the objectives of the educational process. The guidance for psycho-educational assessment of quality of electronic educational resources is provided. It is argued that the effectiveness of the ICT use is to be improved by means of quality evaluation mechanisms involved into the educational process.

Reduction of metal artifacts: beam hardening and photon starvation effects

Science.gov (United States)

Yadava, Girijesh K.; Pal, Debashish; Hsieh, Jiang

2014-03-01

The presence of metal-artifacts in CT imaging can obscure relevant anatomy and interfere with disease diagnosis. The cause and occurrence of metal-artifacts are primarily due to beam hardening, scatter, partial volume and photon starvation; however, the contribution to the artifacts from each of them depends on the type of hardware. A comparison of CT images obtained with different metallic hardware in various applications, along with acquisition and reconstruction parameters, helps understand methods for reducing or overcoming such artifacts. In this work, a metal beam hardening correction (BHC) and a projection-completion based metal artifact reduction (MAR) algorithms were developed, and applied on phantom and clinical CT scans with various metallic implants. Stainless-steel and Titanium were used to model and correct for metal beam hardening effect. In the MAR algorithm, the corrupted projection samples are replaced by the combination of original projections and in-painted data obtained by forward projecting a prior image. The data included spine fixation screws, hip-implants, dental-filling, and body extremity fixations, covering range of clinically used metal implants. Comparison of BHC and MAR on different metallic implants was used to characterize dominant source of the artifacts, and conceivable methods to overcome those. Results of the study indicate that beam hardening could be a dominant source of artifact in many spine and extremity fixations, whereas dental and hip implants could be dominant source of photon starvation. The BHC algorithm could significantly improve image quality in CT scans with metallic screws, whereas MAR algorithm could alleviate artifacts in hip-implants and dentalfillings.

Availability, Use and Constraints to Use of Electronic Information Resources by Postgraduates Students at the University of Ibadan

Directory of Open Access Journals (Sweden)

Dare Samuel Adeleke

2017-12-01

Full Text Available Availability, awareness and use of electronic resources provide access to authoritative, reliable, accurate and timely access to information. The use of electronic information resources (EIRs can enable innovation in teaching and increase timeliness in research of postgraduate students which will eventual result into encouragement of the expected research-led enquiry in this digital age. The study adopted a descriptive survey design. Samples of 300 of postgraduate students within seven out 13 Faculties were randomly selected. Data were collected using questionnaire designed to elicit response from respondents and data were analyzed using descriptive statistics methods percentages, mean, and standard deviation. Results indicated that internet was ranked most available and used in the university. Low level of usage of electronic resources, in particular, full texts data bases is linked to a number of constraints: Interrupted power supply was ranked highest among other factors as speed and capacity of computers, retrieval of records with high recall and low precision, retrieving records relevant to information need, lack of knowledge of search techniques to retrieve information effectively, non possession of requisite IT skills and problems accessing the internet. The study recommended that usage of electronic resources be made compulsory, intensifying awareness campaigns concerning the availability, training on use of electronic resources and the problem of power outage be addressed.

Modeling and Analysis of Deformation for Spiral Bevel Gear in Die Quenching Based on the Hardenability Variation

Science.gov (United States)

Zhang, Yingtao; Wang, Gang; Shi, Wankai; Yang, Lin; Li, Zhichao

2017-07-01

Spiral bevel gears are widely used to transmit energy between intersecting axes. The strength and fatigue life of the gears are improved by carburizing and quenching. A die quenching process is used to control the deformation of the gear. The deformation is determined by the variations in the hardenability for a certain die quenching process. The relationship between hardenability, phase transformation and deformation needs to be studied to minimize deformation during the adjustment of the die quenching process parameters. In this paper, material properties for 22CrMoH steel are determined by the results of Jominy tests, dilatometry experiments and static mechanical property tests. The material models were built based on testing results under the consideration of hardenability variation. An finite element analysis model was developed to couple the phase transformation and deformation history of the complete carburizing and die quenching process for the spiral bevel gears. The final microstructures in the gear were bainite for low hardenability steel and a mixture of bainite and ferrite for high hardenability steel. The largest buckling deformation at the gear bottom surface is 0.375 mm at the outer circle for the low hardenability gear and 0.091 mm at the inner circle for the high hardenability gear.

BUSFET - A Novel Radiation-Hardened SOI Transistor

International Nuclear Information System (INIS)

Schwank, J.R.; Shaneyfelt, M.R.; Draper, B.L.; Dodd, P.E.

1999-01-01

The total-dose hardness of SOI technology is limited by radiation-induced charge trapping in gate, field, and SOI buried oxides. Charge trapping in the buried oxide can lead to back-channel leakage and makes hardening SOI transistors more challenging than hardening bulk-silicon transistors. Two avenues for hardening the back-channel are (1) to use specially prepared SOI buried oxides that reduce the net amount of trapped positive charge or (2) to design transistors that are less sensitive to the effects of trapped charge in the buried oxide. In this work, we propose a new partially-depleted SOI transistor structure that we call the BUSFET--Body Under Source FET. The BUSFET utilizes a shallow source and a deep drain. As a result, the silicon depletion region at the back channel caused by radiation-induced charge trapping in the buried oxide does not form a conducting path between source and drain. Thus, the BUSFET structure design can significantly reduce radiation-induced back-channel leakage without using specially prepared buried oxides. Total dose hardness is achieved without degrading the intrinsic SEU and dose rate hardness of SOI technology. The effectiveness of the BUSFET structure for reducing total-dose back-channel leakage depends on several variables, including the top silicon film thickness and doping concentration and the depth of the source. 3-D simulations show that for a doping concentration of 10 18 cm -3 and a source depth of 90 nm, a silicon film thickness of 180 nm is sufficient to almost completely eliminate radiation-induced back-channel leakage. However, for a doping concentration of 3x10 17 cm -3 , a thicker silicon film (300 nm) must be used

Microstructure and properties of cast iron after laser surface hardening

Directory of Open Access Journals (Sweden)

Stanislav

2013-12-01

Full Text Available Laser surface hardening of cast iron is not trivial due to the material’s heterogeneity and coarse-grained microstructure, particularly in massive castings. Despite that, hardening of heavy moulds for automotive industry is in high demand. The present paper summarises the findings collected over several years of study of materials structure and surface properties. Phase transformations in the vicinity of graphite are described using examples from production of body parts in automotive industry. The description relates to formation of martensite and carbide-based phases, which leads to hardness values above 65 HRC and to excellent abrasion resistance.

Changes in hardness of magnesium alloys due to precipitation hardening

Directory of Open Access Journals (Sweden)

Tatiana Oršulová

2018-04-01

Full Text Available This paper deals with the evaluation of changes in hardness of magnesium alloys during precipitation hardening that are nowadays widely used in different fields of industry. It focuses exactly on AZ31, AZ61 and AZ91 alloys. Observing material hardness changes serves as an effective tool for determining precipitation hardening parameters, such as temperature and time. Brinell hardness measurement was chosen based on experimental needs. There was also necessary to make chemical composition analysis and to observe the microstructures of tested materials. The obtained results are presented and discussed in this paper.

Evaluation of combined hardening parameters for type 304LN stainless steel under strain-controlled cyclic loading

International Nuclear Information System (INIS)

Kumar, Abhishek; Vishnuvardhan, S.; Raghava, G.

2016-01-01

Low cycle fatigue (LCF) is the primary degradation mechanism affecting coolant piping of pressurized water reactor (PWR) caused by combination of pressure and transient mechanical or thermal loads. In the case of LCF, stresses are high enough for plastic deformation to occur and the fatigue life is correlated with the cyclic plastic strain. Modelling cyclic plastic deformation of a material requires hardening parameters, which have to be obtained from LCF test results. It is customary in low cycle fatigue tests that the strain ranges are kept constant and the stresses are allowed to vary which typically leads to a hysteresis loop that consists of linear and nonlinear parts. In this paper, numerical studies on mechanical behaviour of Type 304LN stainless steel under fully reversed strain-controlled cyclic loading have been carried out. A linear combination of the two hardening types, isotropic and kinematic, governed by a scalar parameter, β (0 ≤β ≤ 1) is used. A value of β=1 indicates a pure isotropic hardening while a value of β=0 indicates pure kinematic hardening. The details of the combined isotropic-kinematic hardening model are also presented. Constitutive relations for the classical von Mises theory along with a bilinear hardening theory have been used. The model is implemented in finite element software ABAQUS using a user subroutine written in FORTRAN, UMAT. An iterative method is adopted to arrive at the model's hardening parameters and the value of β. (author)

Secondary Hardening Behavior in Super Duplex Stainless Steels during LCF in Dynamic Strain Ageing Regime

OpenAIRE

Chai, Guocai; Andersson, Marcus

2013-01-01

Cyclic deformation behaviors in five modified duplex stainless steel S32705 grades have been studied at 20 °C, 200 °C, 250° and 350 °C. The influence of temperature and nitrogen concentration on the occurrence of the second hardening phenomenon, in the stress response curve was focused. An increase in nitrogen concentration can have a positive effect on dynamic strain ageing by increasing the first hardening and also the second hardening behavior during cyclic deformation. Furthermore, an inc...

A Study on Developing Evaluation Criteria for Electronic Resources in Evaluation Indicators of Libraries

Science.gov (United States)

Noh, Younghee

2010-01-01

This study aimed to improve the current state of electronic resource evaluation in libraries. While the use of Web DB, e-book, e-journal, and other e-resources such as CD-ROM, DVD, and micro materials is increasing in libraries, their use is not comprehensively factored into the general evaluation of libraries and may diminish the reliability of…

Microstructural evolution and strain hardening behavior of the cold-drawn austenitic stainless steels

International Nuclear Information System (INIS)

Choi, Jeom Yong; Jin, Won

1998-01-01

The strain induced α ' -martensite formation and the strain hardening behavior of metastable austenitic stainless steel during cold drawing have been investigated. The strain induced α ' -martensite nucleates mainly at the intersection of the mechanical twins rather than ε-martensite. It could be explained by the increase of stacking fault energy which arises from the heat generated during high speed drawing and, for AISI 304/Cu, the additional effect of Cu additions. The strain hardening behavior of austenitic stainless steel is strongly related to the microstructural evolution accompanied by strain induced α ' -martensite. The work hardening rates of cold-drawn 304 increased with increasing interstitial element(C,N) contents which affect the strength of the strain induced α ' -martensite

Instability analysis of a fully plastic center-cracked strip of a power hardening material

International Nuclear Information System (INIS)

Zahoor, A.; Paris, P.C.

1978-01-01

An approach for predicting unstable crack growth in a power hardening material is discussed. A fully plastic center-cracked strip of finite width under plane strain conditions, which involves J-controlled crack growth, is analyzed. The conditions for unstable crack growth are identified in terms of a non-dimensional parameter, the Tearing Modulus, T, which incorporates the effect of elastic system compliance on the cracked structure as well as the influence of hardening. Numerical results also illustrate the strong influences on stability of both the strain hardening characteristics of the material and certain geometrical proportions which greatly influence the system compliance. (author)

Numerical predicting of the structure and stresses state in hardened element made of tool steel

Directory of Open Access Journals (Sweden)

A. Bokota

2008-03-01

Full Text Available The paper presents numerical model of thcrmal phcnomcna, phasc transformation and mcchanical phcnomcna associated with hardeningof carbon tool steel. Model for evaluation or fractions OF phases and their kinetics bascd on continuous heating diagram (CHT andcontinuous cooling diagram (CCT. The stresses generated during hardening were assumed to rcsult from ~hermal load. stntcturaI plasticdeformations and transformation plasricity. Thc hardened material was assumed to be elastic-plastic, and in ordcr to mark plastic strains the non-isothermal plastic law of flow with the isotropic hardening and condition plasticity of Huber-Misses were used. TherrnophysicaI values of mechanical phenomena dependent on bo~hth e phase composition and temperature. In the numerical example thc simulated estimation of the phasc Fraction and strcss distributions in the hardened axisimmetrical elemcnt was performed.

On the correlation between irradiation-induced microstructural features and the hardening of reactor pressure vessel steels

International Nuclear Information System (INIS)

Lambrecht, M.; Meslin, E.; Malerba, L.; Hernandez-Mayoral, M.; Bergner, F.; Pareige, P.; Radiguet, B.; Almazouzi, A.

2010-01-01

A correlation is attempted between microstructural observations by various complementary techniques, which have been implemented within the PERFECT project and the hardening measured by tensile tests of reactor pressure vessel steel and model alloys after irradiation to a dose of ∼7 x 10 19 n cm -2 . This is done, using the simple hardening model embodied by the Orowan equation and applying the most suitable superposition law, as suggested by a parametric study using the DUPAIR line tension code. It is found that loops are very strong obstacles to dislocation motion, but due to their low concentration, they only play a minor role in the hardening itself. For the precipitates, the contrary is found, although they are quite soft (due to their very small sizes and their coherent nature), they still play the dominant role in the hardening. Vacancy clusters are important for the formation of both loops and precipitates, but they will play almost no role in the hardening by themselves.

A tool for Load Modeling in Induction Hardening Equipment Driven by Power Semiconductor Systems

International Nuclear Information System (INIS)

Suarez Antola, R.; Suarez Bagnasco, D.

2006-01-01

Kelvin effect (Skin effect) is used in surface hardening produced by induction heating of gears, camforms, camshafts and other work pieces of fairly complex geometries.The induction heating equipment for surface hardening of metals and alloys (using LF or medium frequencies in the jargon of induction heating) is composed by a coil or coil assembly and a power semiconductor driving system up to 50kHz. The load seen by the driving system is equivalent to a transformer. The primary corresponds to the excitation coil or coil assembly, and the work piece corresponds to a short-circuited secondary. To asses the electrical load it is necessary to determine the variations in skin depth from place to place due to local curvature effects in the work piece, and its variations in space and time due to variations in conductivity and magnetic properties coupled with thermal effects. In these and others technical applications of Kelvin effect it is often necessary to be able to relate local skin depths with local curvatures of the surface of electrically conductive bodies.The purpose of this paper is twofold. First, derive a closed form analytical formula that relates the local skin depth with the local mean curvature and the well known skin depth for a flat conductive body. The limits of applicability of this formula are discussed. The predicted skin depths are compared with available experimental results obtained in the framework of surface hardening processes. Second, apply the above mentioned formula to describe the electrical load of the induction heating equipment in the conditions used for surface hardening. In the choice or design of an induction heating system the parameters of the intended process (depth of Kelvin effect, temperatures to be reached and duration of the heating process, amongst others) put restrictions over the coils and the power driving system. To determine the best shape and size of induction coils or coil assemblies, the complex thermal and

Model Identification and FE Simulations: Effect of Different Yield Loci and Hardening Laws in Sheet Forming

International Nuclear Information System (INIS)

Flores, P.; Lelotte, T.; Bouffioux, C.; El Houdaigui, F.; Habraken, A.M.; Duchene, L.; Bael, A. van; He, S.; Duflou, J.

2005-01-01

The bi-axial experimental equipment developed by Flores enables to perform Baushinger shear tests and successive or simultaneous simple shear tests and plane-strain tests. Such experiments and classical tensile tests investigate the material behavior in order to identify the yield locus and the hardening models. With tests performed on two steel grades, the methods applied to identify classical yield surfaces such as Hill or Hosford ones as well as isotropic Swift type hardening or kinematic Armstrong-Frederick hardening models are explained. Comparison with the Taylor-Bishop-Hill yield locus is also provided. The effect of both yield locus and hardening model choice will be presented for two applications: Single Point Incremental Forming (SPIF) and a cup deep drawing

Model Identification and FE Simulations: Effect of Different Yield Loci and Hardening Laws in Sheet Forming

Science.gov (United States)

Flores, P.; Duchêne, L.; Lelotte, T.; Bouffioux, C.; El Houdaigui, F.; Van Bael, A.; He, S.; Duflou, J.; Habraken, A. M.

2005-08-01

The bi-axial experimental equipment developed by Flores enables to perform Baushinger shear tests and successive or simultaneous simple shear tests and plane-strain tests. Such experiments and classical tensile tests investigate the material behavior in order to identify the yield locus and the hardening models. With tests performed on two steel grades, the methods applied to identify classical yield surfaces such as Hill or Hosford ones as well as isotropic Swift type hardening or kinematic Armstrong-Frederick hardening models are explained. Comparison with the Taylor-Bishop-Hill yield locus is also provided. The effect of both yield locus and hardening model choice will be presented for two applications: Single Point Incremental Forming (SPIF) and a cup deep drawing.

Disorientations and their role on the work-hardening in stage IV

DEFF Research Database (Denmark)

Pantleon, W.

2005-01-01

statistical reasons still lead to stage III behavior and a saturation of the ow stress, but deterministic contributions to the development of disorienta- tions, as dierences in activated slip systems across boundaries, cause a linear increase of the flow stress at large strains. Such a constant work......The eect of deformation-induced disorientations on work-hardening of metals is modelled by dislocation dynamics. By incorporating excess dislocations related to disori- entations, Kocks' dislocation model describing stage III hardening is extended to stage IV. Disorientations evolving from purely...

Conditions for pseudo strain-hardening in fiber reinforced brittle matrix composites

International Nuclear Information System (INIS)

Li, V.C.; Wu, H.W.

1992-01-01

Apart from imparting increased fracture toughness, one of the useful purposes of reinforcing brittle matrices with fibers is to create enhanced composite strain capacity. This paper reviews the conditions underwhich such a composite will exhibit the pseudo strain-hardening phenomenon. The presentation is given in a unified manner for both continuous aligned and discontinuous random fiber composites. It is demonstrated that pseudo strain hardening can be practically designed for both gills of composites by proper tailoring of material structures. 18 refs., 8 figs., 2 tabs

Rapid hardening induced by electric pulse annealing in nanostructured pure aluminum

DEFF Research Database (Denmark)

Zeng, Wei; Shen, Yao; Zhang, Ning

2012-01-01

Nanostructured pure aluminum was fabricated by heavy cold-rolling and then subjected to recovery annealing either by applying electric pulse annealing or by traditional air furnace annealing. Both annealing treatments resulted in an increase in yield strength due to the occurrence of a “dislocation...... source-limited hardening” mechanism. However, the hardening kinetics was substantially faster for the electric pulse annealed material. Detailed microstructural characterization suggested that the rapid hardening during electric pulse annealing is related to an enhanced rate of recovery of dislocation...

Study on the Influence of the Work Hardening Models Constitutive Parameters Identification in the Springback Prediction

International Nuclear Information System (INIS)

Oliveira, M.C.; Menezes, L. F.; Alves, J.L.; Chaparro, B.M.

2005-01-01

The main goal of this work is to determine the influence of the work hardening model in the numerical prediction of springback. This study will be performed according with the specifications of the first phase of the 'Benchmark 3' of the Numisheet'2005 Conference: the 'Channel Draw'. Several work hardening constitutive models are used in order to allow a better description of the different material mechanical behavior. Two are classical pure isotropic hardening models described by a power law (Swift) or a Voce type saturation equation. Those two models were also combined with a non-linear (Lemaitre and Chaboche) kinematic hardening rule. The final one is the Teodosiu microstructural hardening model. The study is performed for two commonly used steels of the automotive industry: mild (DC06) and dual phase (DP600) steels. The mechanical characterization, as well as the constitutive parameters identification of each work hardening models, was performed by LPMTM, based on an appropriate set of experimental data such as uniaxial tensile tests, monotonic and Bauschinger simple shear tests and orthogonal strain path tests, all at various orientations with respect to the rolling direction. All the simulations were carried out with the CEMUC's home code DD3IMP (contraction of 'Deep Drawing 3-D IMPlicit code')

Surface modification on PMMA : PVDF polyblend: hardening under ...

Indian Academy of Sciences (India)

Unknown

Keywords. Polyblend; surface modification; microhardness; hardening; plasticization; segmental mobility. 1. Introduction. Polymeric materials have a specific feature of stability towards various aggressive chemical environments, which depends on a multiplicity of factors like structure and nature of the polymers and chemical ...

Simulation-aided investigation of beam hardening induced errors in CT dimensional metrology

DEFF Research Database (Denmark)

Tan, Ye; Kiekens, Kim; Welkenhuyzen, Frank

2014-01-01

are mutually correlated, it remains challenging to interpret measurement results and to identify the distinct error sources. Since simulations allow isolating the different affecting factors, they form a useful complement to experimental investigations. Dewulf et al (2012 CIRP Ann. Manuf. Technol. 61 495......–8) investigated the influence of beam hardening correction parameters on the diameter of a calibrated steel pin in different experimental set-ups. It was clearly shown that an inappropriate beam hardening correction can result in significant dimensional errors. This paper confirms these results using simulations...... of a pin surrounded by a stepped cylinder: a clear discontinuity in the measured diameter of the inner pin is observed where it enters the surrounding material. The results are expanded with an investigation of the beam hardening effect on the measurement results for both inner and outer diameters...

THE MODEL OF LINGUISTIC TEACHERS’ COMPETENCY DEVELOPMENT ON DESIGNING MULTIMEDIA ELECTRONIC EDUCATIONAL RESOURCES IN THE MOODLE SYSTEM

OpenAIRE

Anton M. Avramchuk

2017-01-01

The article is devoted to the problem of developing the competency of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system. The concept of "the competence of teachers of language disciplines on designing multimedia electronic educational resources in the Moodle system" is justified and defined. Identified and characterized the components by which the levels of the competency development of teachers of language disciplines on designing ...

Effects of residual stress on irradiation hardening in stainless steels

Energy Technology Data Exchange (ETDEWEB)

Okubo, N.; Kondo, K.; Kaji, Y. [Japan Atomic Energy Agency, Tokai-mura, Naga-gun, Ibaraki-ken (Japan); Miwa, Y. [Nuclear Energy and Science Directorate, Japan Atomic Energy Agency, Tokai-mura, Ibaraki-ken (Japan)

2007-07-01

Full text of publication follows: Structural materials in fusion reactor with water cooling system will undergo corrosion in aqueous environment and heavier irradiation than that in LWR. Irradiation assisted stress corrosion (IASCC) may be induced in stainless steels exposed in these environment for a long term of reactor operation. The IASCC is considered to be caused in a welding zone. It is difficult to predict and estimate the IASCC, because several irradiation effects (irradiation hardening, swelling, irradiation induced stress relaxation, etc) work intricately. Firstly, effects of residual stress on irradiation hardening were investigated in stainless steels. Specimens used in this study were SUS316 and SUS316L. By bending deformation, the specimens with several % plastic strain, which corresponds to weld residual stress, were prepared. Ion irradiations of 12 MeV Ni{sup 3+} were performed at 330, 400 and 550 deg. C to 45 dpa in TIARA facility at JAEA. No bent specimen was simultaneously irradiated with the bent specimen. The residual stress was estimated by X-ray residual stress measurements before and after the irradiation. The micro-hardness was measured by using nano-indenter. The irradiation hardening and the stress relaxation were changed by irradiation under bending deformation. The residual stress did not relax even for the case of the higher temperature aging at 500 deg. C for the same time of irradiation. The residual stress after ion irradiation, however, relaxed at these experimental temperatures in SUS316L. The hardness was obviously suppressed in bent SUS316L irradiated at 300 deg. C to 6 or 12 dpa. It was evident that irradiation induced stress relaxation occasionally suppressed the irradiation hardening in SUS316L. (authors)

Determining the level of awareness of the physicians in using the variety of electronic information resources and the effecting factors.

Science.gov (United States)

Papi, Ahmad; Ghazavi, Roghayeh; Moradi, Salimeh

2015-01-01

Understanding of the medical society's from the types of information resources for quick and easy access to information is an imperative task in medical researches and management of the treatment. The present study was aimed to determine the level of awareness of the physicians in using various electronic information resources and the factors affecting it. This study was a descriptive survey. The data collection tool was a researcher-made questionnaire. The study population included all the physicians and specialty physicians of the teaching hospitals affiliated to Isfahan University of Medical Sciences and numbered 350. The sample size based on Morgan's formula was set at 180. The content validity of the tool was confirmed by the library and information professionals and the reliability was 95%. Descriptive statistics were used including the SPSS software version 19. On reviewing the need of the physicians to obtain the information on several occasions, the need for information in conducting the researches was reported by the maximum number of physicians (91.9%) and the usage of information resources, especially the electronic resources, formed 65.4% as the highest rate with regard to meeting the information needs of the physicians. Among the electronic information databases, the maximum awareness was related to Medline with 86.5%. Among the various electronic information resources, the highest awareness (43.3%) was related to the E-journals. The highest usage (36%) was also from the same source. The studied physicians considered the most effective deterrent in the use of electronic information resources as being too busy and lack of time. Despite the importance of electronic information resources for the physician's community, there was no comprehensive knowledge of these resources. This can lead to less usage of these resources. Therefore, careful planning is necessary in the hospital libraries in order to introduce the facilities and full capabilities of the

Stress corrosion cracking evaluation of precipitation-hardening stainless steel

Science.gov (United States)

Humphries, T. S.; Nelson, E. E.

1970-01-01

Accelerated test program results show which precipitation hardening stainless steels are resistant to stress corrosion cracking. In certain cases stress corrosion susceptibility was found to be associated with the process procedure.

A Radiation Hardened Housekeeping Slave Node (RH-HKSN) ASIC

Data.gov (United States)

National Aeronautics and Space Administration — This projects seeks to continue the development of the Radiation Hardened Housekeeping Slave Node (RH-HKSN) ASIC. The effort has taken parallel paths by implementing...

Radiation-Hardened Circuitry Using Mask-Programmable Analog Arrays. Final Report

Energy Technology Data Exchange (ETDEWEB)

Britton, Jr., Charles L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ericson, Milton Nance [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bobrek, Miljko [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Blalock, Benjamin [Univ. of Tennessee, Knoxville, TN (United States)

2015-12-01

As the recent accident at Fukushima Daiichi so vividly demonstrated, telerobotic technologies capable of withstanding high radiation environments need to be readily available to enable operations, repair, and recovery under severe accident scenarios where human entry is extremely dangerous or not possible. Telerobotic technologies that enable remote operation in high dose rate environments have undergone revolutionary improvement over the past few decades. However, much of this technology cannot be employed in nuclear power environments due the radiation sensitivity of the electronics and the organic insulator materials currently in use. This is the final report of the activities involving the NEET 2 project Radiation Hardened Circuitry Using Mask-Programmable Analog Arrays. We present a detailed functional block diagram of the proposed data acquisition system, the thought process leading to technical decisions, the implemented system, and the tested results from the systems. This system will be capable of monitoring at least three parameters of importance to nuclear reactor monitoring: temperature, radiation level, and pressure.

Managing Selection for Electronic Resources: Kent State University Develops a New System to Automate Selection

Science.gov (United States)

Downey, Kay

2012-01-01

Kent State University has developed a centralized system that manages the communication and work related to the review and selection of commercially available electronic resources. It is an automated system that tracks the review process, provides selectors with price and trial information, and compiles reviewers' feedback about the resource. It…

Numerical simulations of progressive hardening by using ABAQUS FEA software

Directory of Open Access Journals (Sweden)

Domański Tomasz

2018-01-01

Full Text Available The paper concerns numerical simulations of progressive hardening include phase transformations in solid state of steel. Abaqus FEA software is used for numerical analysis of temperature field and phase transformations. Numerical subroutines, written in fortran programming language are used in computer simulations where models of the distribution of movable heat source, kinetics of phase transformations in solid state as well as thermal and structural strain are implemented. Model for evaluation of fractions of phases and their kinetics is based on continuous heating diagram and continuous cooling diagram. The numerical analysis of thermal fields, phase fractions and strain associated progressive hardening of elements made of steel were done.

Effect of aluminizing on hardenability of steel (S45C)

Science.gov (United States)

Prayitno, D.; Sugiarto, R.

2018-01-01

The objective of research is to know the effect of aluminizing on hardenability of steel (S45C). The research methodologies were as follows. The Steels (S45C) were machined into the Jominy test samples. Next the samples were preheating at 700 ° C for 30 minutes and then the samples were dipped into the molten of aluminium for 3 minutes as a hot dip aluminizng method. The aluminium molten was 700 ° C. Then the samples were cooled into room temperatures. Finally the samples were into the jominy tested. The results show that the aluminizing (include the preheating process) increases the hardenability of steel (S45C).

Effects of kinematic hardening rules on thermal ratchetting analysis of cylinders subjected to cyclically moving temperature distribution

International Nuclear Information System (INIS)

Ohno, N.; Kobayashi, M.

1995-01-01

In the present work, thermal ratchetting in a cylinder subjected to a cyclically moving temperature front (i.e. liquid surface induced thermal ratchetting) was analyzed by implementing in a finite element method the four kinds of plasticity models with different kinematic hardening rules. The following findings were thus obtained concerning effects of the kinematic hardening rules on the analysis. (1) If transition nonlinear hardening after yielding is disregarded, the thermal ratchetting becomes significant, as seen in the results of the PP and LKH models. Especially the PP model, which does not express any strain hardening, predicts steady development of the thermal ratchetting. (2) If significant mechanical ratchetting is allowed in the modeling of kinematic hardening, the thermal ratchetting becomes marked, as seen in the results of the AF model. (3) Model dependence of the thermal ratchetting is more noticeable when the difference of temperature at the temperature front, ΔT, is smaller. (4) The OW model makes the thermal ratchetting stop at a smaller number of cycles when ΔT is smaller. On the other hand, the LKH and AF models allow that the thermal ratchetting to develop more constantly when ΔT is smaller. As seen from the above findings, the analysis of liquid surface induced thermal ratchetting has great dependence on the kinematic hardening rules employed. Especially the PP model, which has been used often to analyze the thermal ratchetting so far, gives too large development of the thermal ratchetting. Thus we may say that in order to improve the analysis it is necessary to use an appropriate kinematic hardening model which is capable of expressing appropriately both mechanical ratchetting and transient nonlinear hardening after yielding. (author)

system hardening architecture for safer access to critical business

African Journals Online (AJOL)

eobe

System hardening is a defence strategy, where several different security measures are applied at various layers, all of which .... commerce have tremendously imparted on corporate services ..... Technology and Exploring Engineering, Vol. 2,.

End-of-life resource recovery from emerging electronic products

DEFF Research Database (Denmark)

Parajuly, Keshav; Habib, Komal; Cimpan, Ciprian

2016-01-01

Integrating product design with appropriate end-of-life (EoL) processing is widely recognized to have huge potentials in improving resource recovery from electronic products. In this study, we investigate both the product characteristics and EoL processing of robotic vacuum cleaner (RVC), as a case...... of emerging electronic product, in order to understand the recovery fate of different materials and its linkage to product design. Ten different brands of RVC were dismantled and their material composition and design profiles were studied. Another 125 RVCs (349 kg) were used for an experimental trial...... at a conventional ‘shred-and-separate’ type preprocessing plant in Denmark. A detailed material flow analysis was performed throughout the recycling chain. The results show a mismatch between product design and EoL processing, and the lack of practical implementation of ‘Design for EoL’ thinking. In the best...

Study of the mechanisms involved in the laser superficial hardening process of metallic alloys; Estudo dos mecanismos envolvidos no processo de endurecimento superficial a laser de ligas metalicas

Energy Technology Data Exchange (ETDEWEB)

Silva, Edmara Marques Rodrigues da

2001-07-01

The laser superficial hardening process of a ferrous alloy (gray cast iron) and of an aluminum-silicon alloy was investigated in this work. These metallic alloys are used in the automobile industry for manufacturing cylinders and pistons, respectively. By application of individual pulses and single tracks, the involved mechanisms during the processing were studied. Variables such as energy density, power density, temporal width, beam diameter on the sample surface, atmosphere of the processing region, overlapping and scanning velocity. The hardened surface was characterized by optical and scanning electronic microscopy, dispersive energy microanalysis, X-ray mapping, X-ray diffraction, and measurements of roughness and Vickers microhardness. Depending on the processing parameters, it is possible to obtain different microstructures. The affected area of gray cast iron, can be hardened by remelting or transformation hardening (total or partial) if the reached temperature is higher or not that of melting temperature. Laser treatment originated new structures such as retained austenite, martensite and, occasionally, eutectic of cellular dendritic structure. Aluminum-silicon alloy does not have phase transformation in solid state, it can be hardened only by remelting. The increase of hardness is a function of the precipitation hardening process, which makes the silicon particles smaller and more disperse in the matrix. Maximal values of microhardness (700-1000 HV) were reached with the laser treatment in gray cast iron samples. The initial microhardness is of 242 HV. For aluminum-silicon alloy, the laser remelting increases the initial microhardness of 128 HV to the range of 160-320 HV. The found results give a new perspective for using the CLA/IPEN's laser in the heat treatment area. Besides providing a higher absorptivity to the materials, compared with the CO{sub 2} laser, and optical fiber access, the superficial hardening with Nd:YAG laser, depending on the

Use of electronic sales data to tailor nutrition education resources for an ethnically diverse population.

Science.gov (United States)

Eyles, H; Rodgers, A; Ni Mhurchu, C

2010-02-01

Nutrition education may be most effective when personally tailored. Individualised electronic supermarket sales data offer opportunities to tailor nutrition education using shopper's usual food purchases. The present study aimed to use individualised electronic supermarket sales data to tailor nutrition resources for an ethnically diverse population in a large supermarket intervention trial in New Zealand. Culturally appropriate nutrition education resources (i.e. messages and shopping lists) were developed with the target population (through two sets of focus groups) and ethnic researchers. A nutrient database of supermarket products was developed using retrospective sales data and linked to participant sales to allow tailoring by usual food purchases. Modified Heart Foundation Tick criteria were used to identify 'healthier' products in the database suitable for promotion in the resources. Rules were developed to create a monthly report listing the tailored and culturally targeted messages to be sent to each participant, and to produce automated, tailored shopping lists. Culturally targeted nutrition messages (n = 864) and shopping lists (n = 3 formats) were developed. The food and nutrient database (n = 3000 top-selling products) was created using 12 months of retrospective sales data, and comprised 60%'healthier' products. Three months of baseline sales data were used to determine usual food purchases. Tailored resources were successfully mailed to 123 Māori, 52 Pacific and 346 non-Māori non-Pacific participants over the 6-month trial intervention period. Electronic supermarket sales data can be used to tailor nutrition education resources for a large number of ethnically diverse supermarket shoppers.

Thermal hardening of saturated clays. Application to underground storage of radioactive wastes

International Nuclear Information System (INIS)

Picard, Jean-Marc

1994-01-01

Saturated clays submitted to constant mechanical loading and slow temperature increase frequently undergo irreversible contractions. This phenomena is described here by means of a change of plastic limits induced by temperature only, called thermal hardening. Constitutive laws adapted to this kind of plastic behaviour can be formulated within a general framework that satisfies thermodynamical principles. It shows that this coupling results from the presence of a latent heat during the isothermal hardening of plastic limits. A thermomechanical extension of Cam Clay model is then proposed and used in the analysis of laboratory thermomechanical tests performed on clay materials. Making use of tests already published, we show the adequacy of the concept of thermal hardening for clay behaviour. Some clay from deep geological formation considered for the disposal of radioactive waste exhibit thermal hardening in laboratory tests. The consequences for the underground storage facilities during the thermal loading created by the waste are investigated by means of in situ tests as well as numerical computation. The measurement around a heating probe buried in the clay mass demonstrate the significance of thermo-hydro-mechanical couplings. An accurate understanding of in situ measurements is achieved by means of numerical modeling in which the interaction between the various loading of the tests (excavation, pore pressure seepage, and heating) is carefully taken into account. Thermal hardening of the clay appears to be of little influence in these in situ tests. On the other hand, the magnitude of thermo-hydro-mechanical couplings observed in situ are higher than might have been expected from laboratory tests. A more accurate prediction is obtained if one takes into account the more stiffer behaviour of clays when they are subjected to small deformations. (authors)

Epoxy modified bitumen : Chemical hardening and its interpretation

NARCIS (Netherlands)

Apostolidis, P.; Pipintakos, G.; van de Ven, M.F.C.; Liu, X.; Erkens, Sandra; Scarpas, Athanasios

2018-01-01

Epoxy modified bitumen (EMB) is a promising technology for long lasting paving materials ensuring higher resistance to rutting, oxygen- and moisture-induced damage. In this paper, an analysis of the chemical reactions that take place during the chemical hardening process (curing) of epoxy modified

Effect of Fibers and Filler Types on Fresh and Hardened Properties of Self-Compacting Concrete

Directory of Open Access Journals (Sweden)

Saeed K. Rejeb* , Majid Kh . N. Ayad A. M.

2014-04-01

Full Text Available This paper deals with studying the fresh and hardened properties of self-compacting concrete, by using three types of filler (silica fume, clinker powder & lime stone powder, and two types of fibers (steel & glass fibers with volume fractions of (0.5% and (0.1% respectively. For each type of fillers, the fresh properties are measured by using Slump test, J- ring and V- funnel, while hardened properties include the compressive strength, splitting tensile strength and flexural strength. The results show that adding fibers to the self-compacting concrete (SCC well reduces the workability and improves the hardened properties. Also, the study concluded that better workability is obtained by using (lime stone, silica fume and clinker powder as fillers, respectively. While the higher hardened properties are gained by using silica fume were rather than those of other types of fillers 

Simulation of irradiation hardening of Zircaloy within plate-type dispersion nuclear fuel elements

Science.gov (United States)

Jiang, Yijie; Wang, Qiming; Cui, Yi; Huo, Yongzhong; Ding, Shurong

2011-06-01

Within plate-type dispersion nuclear fuel elements, the metal matrix and cladding attacked continuously by fast neutrons undergo irradiation hardening, which might have remarkable effects upon the mechanical behaviors within fuel elements. In this paper, with the irradiation hardening effect of metal materials mainly considered together with irradiation growth effect of the cladding, the three-dimensional large-deformation constitutive relations for the metal matrix and cladding are developed. The method of virtual temperature increase in the previous studies is further developed to model the irradiation swelling of fuel particles; the method of anisotropic thermal expansion is introduced to model irradiation growth of the cladding; and a method of multi-step-temperature loading is proposed to simulate the coupling features of irradiation-induced swelling of the fuel particles together with irradiation growth of the cladding. Above all, based on the developed relationship between irradiation growth at certain burnup and the loaded virtual temperatures, with considering that certain burnup corresponds to certain fast neutron fluence, the time-dependent constitutive relation due to irradiation hardening effect is replaced by the virtual-temperature-dependent one which is introduced into the commercial software to simulate the irradiation hardening effects of the matrix and cladding. Numerical simulations of the irradiation-induced mechanical behaviors are implemented with the finite element method in consideration of the micro-structure of the fuel meat. The obtained results indicate that when the irradiation hardening effects are introduced into the constitutive relations of the metal matrix and cladding: (1) higher maximum Mises stresses for certain burnup at the matrix exist with the equivalent plastic strains remaining almost the same at lower burnups; (2) the maximum Mises stresses for certain burnup at the cladding are enhanced while the maximum equivalent

Simulation of irradiation hardening of Zircaloy within plate-type dispersion nuclear fuel elements

Energy Technology Data Exchange (ETDEWEB)

Jiang Yijie; Wang Qiming; Cui Yi; Huo Yongzhong [Department of Mechanics and Engineering Science, Fudan University, Shanghai 200433 (China); Ding Shurong, E-mail: dsr1971@163.com [Department of Mechanics and Engineering Science, Fudan University, Shanghai 200433 (China)

2011-06-15

Within plate-type dispersion nuclear fuel elements, the metal matrix and cladding attacked continuously by fast neutrons undergo irradiation hardening, which might have remarkable effects upon the mechanical behaviors within fuel elements. In this paper, with the irradiation hardening effect of metal materials mainly considered together with irradiation growth effect of the cladding, the three-dimensional large-deformation constitutive relations for the metal matrix and cladding are developed. The method of virtual temperature increase in the previous studies is further developed to model the irradiation swelling of fuel particles; the method of anisotropic thermal expansion is introduced to model irradiation growth of the cladding; and a method of multi-step-temperature loading is proposed to simulate the coupling features of irradiation-induced swelling of the fuel particles together with irradiation growth of the cladding. Above all, based on the developed relationship between irradiation growth at certain burnup and the loaded virtual temperatures, with considering that certain burnup corresponds to certain fast neutron fluence, the time-dependent constitutive relation due to irradiation hardening effect is replaced by the virtual-temperature-dependent one which is introduced into the commercial software to simulate the irradiation hardening effects of the matrix and cladding. Numerical simulations of the irradiation-induced mechanical behaviors are implemented with the finite element method in consideration of the micro-structure of the fuel meat. The obtained results indicate that when the irradiation hardening effects are introduced into the constitutive relations of the metal matrix and cladding: (1) higher maximum Mises stresses for certain burnup at the matrix exist with the equivalent plastic strains remaining almost the same at lower burnups; (2) the maximum Mises stresses for certain burnup at the cladding are enhanced while the maximum equivalent

Radiation-hardened nonvolatile MNOS RAM

International Nuclear Information System (INIS)

Wrobel, T.F.; Dodson, W.H.; Hash, G.L.; Jones, R.V.; Nasby, R.D.; Olson, R.J.

1983-01-01

A radiation hardened nonvolatile MNOS RAM is being developed at Sandia National Laboratories. The memory organization is 128 x 8 bits and utilizes two p-channel MNOS transistors per memory cell. The peripheral circuitry is constructed with CMOS metal gate and is processed with standard Sandia rad-hard processing techniques. The devices have memory retention after a dose-rate exposure of 1E12 rad(Si)/s, are functional after total dose exposure of 1E6 rad(Si), and are dose-rate upset resistant to levels of 7E8 rad(Si)/s

Optimization of resistively hardened latches

International Nuclear Information System (INIS)

Gagne, G.; Savaria, Y.

1990-01-01

The design of digital circuits tolerant to single-event upsets is considered. The results of a study are presented on which an analytical model was used to predict the behavior of a standard resistively hardened latch. It is shown that a worst case analysis for all possible single-event upset situations (on the latch or in the logic) can be derived from studying the effects of a transient disturbed write cycle. The existence of an intrinsic minimum write period to tolerate a transient of a given duration is also demonstrated

Multiple regression analysis of Jominy hardenability data for boron treated steels

International Nuclear Information System (INIS)

Komenda, J.; Sandstroem, R.; Tukiainen, M.

1997-01-01

The relations between chemical composition and their hardenability of boron treated steels have been investigated using a multiple regression analysis method. A linear model of regression was chosen. The free boron content that is effective for the hardenability was calculated using a model proposed by Jansson. The regression analysis for 1261 steel heats provided equations that were statistically significant at the 95% level. All heats met the specification according to the nordic countries producers classification. The variation in chemical composition explained typically 80 to 90% of the variation in the hardenability. In the regression analysis elements which did not significantly contribute to the calculated hardness according to the F test were eliminated. Carbon, silicon, manganese, phosphorus and chromium were of importance at all Jominy distances, nickel, vanadium, boron and nitrogen at distances above 6 mm. After the regression analysis it was demonstrated that very few outliers were present in the data set, i.e. data points outside four times the standard deviation. The model has successfully been used in industrial practice replacing some of the necessary Jominy tests. (orig.)

Availability, Level of Use and Constraints to Use of Electronic Resources by Law Lecturers in Public Universities in Nigeria

Science.gov (United States)

Amusa, Oyintola Isiaka; Atinmo, Morayo

2016-01-01

(Purpose) This study surveyed the level of availability, use and constraints to use of electronic resources among law lecturers in Nigeria. (Methodology) Five hundred and fifty-two law lecturers were surveyed and four hundred and forty-two responded. (Results) Data analysis revealed that the level of availability of electronic resources for the…

NEW APPROACH FOR TECHNOLOGY OF VOLUMETRIC – SUPERFICIAL HARDENING OF GEAR DETAILS OF THE BACK AXLE OF MOBILE MACHINES

Directory of Open Access Journals (Sweden)

A. I. Mihluk

2010-01-01

Full Text Available The new approach for technology of volumetric – superficial hardening of gear details of the back axle made of steel lowered harden ability is offered. This approach consisting in formation of intense – hardened condition on all surface of a detail.

The method of modelling of relationships between hardenability and chemical composition of the constructional alloy steels

International Nuclear Information System (INIS)

Dobrzanski, L.A.; Sitek, W.

1998-01-01

Basing on the experimental results of the hardenability investigations, which employed Jominy method, the model of the neural networks was developed and fully verified experimentally. The model makes it possible to obtain Jominy hardenability curves basing on the steel chemical composition. The model of neural networks, making it possible to design the steel chemical composition, basing on the known Jominy hardenability curve shape, was developed also and fully verified numerically. The practical usability of the models developed is presented. (author)

Microstructural and Mechanical Study of Press Hardening of Thick Boron Steel Sheet

Science.gov (United States)

Pujante, J.; Garcia-Llamas, E.; Golling, S.; Casellas, D.

2017-09-01

Press hardening has become a staple in the production of automotive safety components, due to the combination of high mechanical properties and form complexity it offers. However, the use of press hardened components has not spread to the truck industry despite the advantages it confers, namely affordable weight reduction without the use of exotic materials, would be extremely attractive for this sector. The main reason for this is that application of press hardened components in trucks implies adapting the process to the manufacture of thick sheet metal. This introduces an additional layer of complexity, mainly due to the thermal gradients inside the material resulting in though-thickness differences in austenitization and cooling, potentially resulting in complex microstructure and gradient of mechanical properties. This work presents a preliminary study on the press hardening of thick boron steel sheet. First of all, the evolution of the sheet metal during austenitization is studied by means of dilatometry tests and by analysing the effect of furnace dwell time on grain size. Afterwards, material cooled using different cooling strategies, and therefore different effective cooling rates, is studied in terms of microstructure and mechanical properties. Initial results from finite element simulation are compared to experimental results, focusing on the phase composition in through thickness direction. Results show that industrial-equivalent cooling conditions do not lead to gradient microstructures, even in extreme scenarios involving asymmetrical cooling.

Characterization and Strain-Hardening Behavior of Friction Stir-Welded Ferritic Stainless Steel

Science.gov (United States)

Sharma, Gaurav; Dwivedi, Dheerendra Kumar; Jain, Pramod Kumar

2017-12-01

In this study, friction stir-welded joint of 3-mm-thick plates of 409 ferritic stainless steel (FSS) was characterized in light of microstructure, x-ray diffraction analysis, hardness, tensile strength, ductility, corrosion and work hardening properties. The FSW joint made of ferritic stainless steel comprises of three distinct regions including the base metal. In stir zone highly refined ferrite grains with martensite and some carbide precipitates at the grain boundaries were observed. X-ray diffraction analysis also revealed precipitation of Cr23C6 and martensite formation in heat-affected zone and stir zone. In tensile testing of the transverse weld samples, the failure eventuated within the gauge length of the specimen from the base metal region having tensile properties overmatched to the as-received base metal. The tensile strength and elongation of the longitudinal (all weld) sample were found to be 1014 MPa and 9.47%, respectively. However, in potentiodynamic polarization test, the corrosion current density of the stir zone was highest among all the three zones. The strain-hardening exponent for base metal, transverse and longitudinal (all weld) weld samples was calculated using various equations. Both the transverse and longitudinal weld samples exhibited higher strain-hardening exponents as compared to the as-received base metal. In Kocks-Mecking plots for the base metal and weld samples at least two stages of strain hardening were observed.

Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

Science.gov (United States)

Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

2016-01-01

The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications. PMID:26892834

Radiation effects on and dose enhancement of electronic materials

International Nuclear Information System (INIS)

Srour, J.R.; Long, D.M.

1984-01-01

This book describes radiation effects on and dose enhancement factors for electronic materials. Alteration of the electrical properties of solid-state devices and integrated circuits by impinging radiation is well-known. Such changes may cause an electronic subsystem to fail, thus there is currently great interest in devising methods for avoiding radiation-induced degradation. The development of radiation-hardened devices and circuits is an exciting approach to solving this problem for many applications, since it could minimize the need for shielding or other system hardening techniques. Part 1 describes the basic mechanisms of radiation effects on electronic materials, devices, and integrated circuits. Radiation effects in bulk silicon and in silicon devices are treated. Ionizing radiation effects in silicon dioxide films and silicon MOS devices are discussed. Single event phenomena are considered. Key literature references and a bibliography are provided. Part II provides tabulations of dose enhancement factors for electronic devices in x-ray and gamma-ray environments. The data are applicable to a wide range of semiconductor devices and selected types of capacitors. Radiation environments discussed find application in system design and in radiation test facilities

The role of strain hardening in the transition from dislocation-mediated to frictional deformation of marbles within the Karakoram Fault Zone, NW India

Science.gov (United States)

Wallis, David; Lloyd, Geoffrey E.; Hansen, Lars N.

2018-02-01

The onset of frictional failure and potentially seismogenic deformation in carbonate rocks undergoing exhumation within fault zones depends on hardening processes that reduce the efficiency of aseismic dislocation-mediated deformation as temperature decreases. However, few techniques are available for quantitative analysis of dislocation slip system activity and hardening in natural tectonites. Electron backscatter diffraction maps of crystal orientations offer one such approach via determination of Schmid factors, if the palaeostress conditions can be inferred and the critical resolved shear stresses of slip systems are constrained. We analyse calcite marbles deformed in simple shear within the Karakoram Fault Zone, NW India, to quantify changes in slip system activity as the rocks cooled during exhumation. Microstructural evidence demonstrates that between ∼300 °C and 200-250 °C the dominant deformation mechanisms transitioned from dislocation-mediated flow to twinning and frictional failure. However, Schmid factor analysis, considering critical resolved shear stresses for yield of undeformed single crystals, indicates that the fraction of grains with sufficient resolved shear stress for glide apparently increased with decreasing temperature. Misorientation analysis and previous experimental data indicate that strain-dependent work hardening is responsible for this apparent inconsistency and promoted the transition from dislocation-mediated flow to frictional, and potentially seismogenic, deformation.

A systematic review of portable electronic technology for health education in resource-limited settings.

Science.gov (United States)

McHenry, Megan S; Fischer, Lydia J; Chun, Yeona; Vreeman, Rachel C

2017-08-01

The objective of this study is to conduct a systematic review of the literature of how portable electronic technologies with offline functionality are perceived and used to provide health education in resource-limited settings. Three reviewers evaluated articles and performed a bibliography search to identify studies describing health education delivered by portable electronic device with offline functionality in low- or middle-income countries. Data extracted included: study population; study design and type of analysis; type of technology used; method of use; setting of technology use; impact on caregivers, patients, or overall health outcomes; and reported limitations. Searches yielded 5514 unique titles. Out of 75 critically reviewed full-text articles, 10 met inclusion criteria. Study locations included Botswana, Peru, Kenya, Thailand, Nigeria, India, Ghana, and Tanzania. Topics addressed included: development of healthcare worker training modules, clinical decision support tools, patient education tools, perceptions and usability of portable electronic technology, and comparisons of technologies and/or mobile applications. Studies primarily looked at the assessment of developed educational modules on trainee health knowledge, perceptions and usability of technology, and comparisons of technologies. Overall, studies reported positive results for portable electronic device-based health education, frequently reporting increased provider/patient knowledge, improved patient outcomes in both quality of care and management, increased provider comfort level with technology, and an environment characterized by increased levels of technology-based, informal learning situations. Negative assessments included high investment costs, lack of technical support, and fear of device theft. While the research is limited, portable electronic educational resources present promising avenues to increase access to effective health education in resource-limited settings, contingent

Technologies Enabling Custom Radiation-Hardened Component Development, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Two primary paths are available for the creation of a Rad-Hard ASIC. The first approach is to use a radiation hardened process such as existing Rad-Hard foundries....

Radiation Hardened Ethernet PHY and Switch Fabric, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Innoflight will develop a new family of radiation hardened (up to 3 Mrad(Si)), fault-tolerant, high data-rate (up to 8 Gbps), low power Gigabit Ethernet PHY and...

Direct single electron detection with a CMOS detector for electron microscopy

International Nuclear Information System (INIS)

Faruqi, A.R.; Henderson, R.; Pryddetch, M.; Allport, P.; Evans, A.

2005-01-01

We report the results of an investigation into the use of a monolithic active pixel sensor (MAPS) for electron microscopy. MAPS, designed originally for astronomers at the Rutherford Appleton Laboratories, was installed in a 120 kV electron microscope (Philips CM12) at the MRC Laboratory in Cambridge for tests which included recording single electrons at 40 and 120 keV, and measuring signal-to-noise ratio (SNR), spatial resolution and radiation sensitivity. Our results show that, due to the excellent SNR and resolution, it is possible to register single electrons. The radiation damage to the detector is apparent with low doses and gets progressively greater so that its lifetime is limited to 600,000-900,000 electrons/pixel (very approximately 10-15 krad). Provided this detector can be radiation hardened to reduce its radiation sensitivity several hundred fold and increased in size, it will provide excellent performance for all types of electron microscopy

The W alloying effect on thermal stability and hardening of nanostructured Cu–W alloyed thin films

Science.gov (United States)

Zhao, J. T.; Zhang, J. Y.; Hou, Z. Q.; Wu, K.; Feng, X. B.; Liu, G.; Sun, J.

2018-05-01

In order to achieve desired mechanical properties of alloys by manipulating grain boundaries (GBs) via solute decoration, it is of great significance to understand the underlying mechanisms of microstructural evolution and plastic deformation. In this work, nanocrystalline (NC) Cu–W alloyed films with W concentrations spanning from 0 to 40 at% were prepared by using magnetron sputtering. Thermal stability (within the temperature range of 200 °C–600 °C) and hardness of the films were investigated by using the x-ray diffraction, transmission electron microscope (TEM) and nanoindentation, respectively. The NC pure Cu film exhibited substantial grain growth upon all annealing temperatures. The Cu–W alloyed films, however, displayed distinct microstructural evolution that depended not only on the W concentration but also on the annealing temperature. At a low temperature of 200 °C, all the Cu–W alloyed films were highly stable, with unconspicuous change in grain sizes. At high temperatures of 400 °C and 600 °C, the microstructural evolution was greatly controlled by the W concentrations. The Cu–W films with low W concentration manifested abnormal grain growth (AGG), while the ones with high W concentrations showed phase separation. TEM observations unveiled that the AGG in the Cu–W alloyed thin films was rationalized by GB migration. Nanoindentation results showed that, although the hardness of both the as-deposited and annealed Cu–W alloyed thin films monotonically increased with W concentrations, a transition from annealing hardening to annealing softening was interestingly observed at the critical W addition of ∼25 at%. It was further revealed that an enhanced GB segregation associated with detwinning was responsible for the annealing hardening, while a reduced solid solution hardening for the annealing softening.

Study of magnetic hardening in Sm(Co/sub 1-x/Cu/sub x/)/sub 5/ alloy

International Nuclear Information System (INIS)

Awan, M.S.; Bhatti, A.S.; Farooque, M.

2008-01-01

Magnetic hardening has been examined in the samarium (Sm), cobalt (Co) and copper (Cu) fused permanent magnets by correlating the magnetic properties with annealing temperature and microstructure of the samples. For the Sm(Co/sub 1-x/Cu/sub x/)/sub 5/ system, with various copper contents (x=0, 0.2, 0.3, 0.4 and 0.5) the shape of initial magnetization curve indicated that the magnetic hardening process involved in these types of magnets consists of domain wall pinning type. This is consistent with the microstructure studies which show the existence of nonmagnetic Cu-rich precipitates in the Co-rich matrix. Copper substituted samples were annealed in the temperature range (300 -1000) degree C for 3h under the protective atmosphere of argon (Ar) gas. Both cast and annealed samples prepared by tri-arc melting technique exhibit two-phase microstructure responsible for enhanced magnetic properties. Metallographic and surface studies were carried out using a digital optical microscope (OM). X-ray diffraction (XRD) studies confirmed that the alloys solidefied in the hexagonal crystal structure. The lattice parameters and unit cell volume increase with increasing Cu content. Scanning electron microscope (SEM) coupled with energy dispersive X-ray (EDX) was used to examine the surface morphology, compositional variations, elemental segregations, formation and effect of annealing on the different phases. Later these parameters were related to the magnetic properties. Copper-rich phase precipitates in the Co- rich matrix may serves as the pinning centers for the domain wall motion. Introduction of these pinning centers improved the magnetic hardening of the alloy. Annealing the Cu-substituted alloy further improved the magnetic properties. During annealing, diffusion of copper played the key role for enhanced magnetic properties. It was found that both Cu substitution and subsequent annealing are the dominating factors determining the magnetic properties of these magnetic

The W alloying effect on thermal stability and hardening of nanostructured Cu-W alloyed thin films.

Science.gov (United States)

Zhao, J T; Zhang, J Y; Hou, Z Q; Wu, K; Feng, X B; Liu, G; Sun, J

2018-05-11

In order to achieve desired mechanical properties of alloys by manipulating grain boundaries (GBs) via solute decoration, it is of great significance to understand the underlying mechanisms of microstructural evolution and plastic deformation. In this work, nanocrystalline (NC) Cu-W alloyed films with W concentrations spanning from 0 to 40 at% were prepared by using magnetron sputtering. Thermal stability (within the temperature range of 200 °C-600 °C) and hardness of the films were investigated by using the x-ray diffraction, transmission electron microscope (TEM) and nanoindentation, respectively. The NC pure Cu film exhibited substantial grain growth upon all annealing temperatures. The Cu-W alloyed films, however, displayed distinct microstructural evolution that depended not only on the W concentration but also on the annealing temperature. At a low temperature of 200 °C, all the Cu-W alloyed films were highly stable, with unconspicuous change in grain sizes. At high temperatures of 400 °C and 600 °C, the microstructural evolution was greatly controlled by the W concentrations. The Cu-W films with low W concentration manifested abnormal grain growth (AGG), while the ones with high W concentrations showed phase separation. TEM observations unveiled that the AGG in the Cu-W alloyed thin films was rationalized by GB migration. Nanoindentation results showed that, although the hardness of both the as-deposited and annealed Cu-W alloyed thin films monotonically increased with W concentrations, a transition from annealing hardening to annealing softening was interestingly observed at the critical W addition of ∼25 at%. It was further revealed that an enhanced GB segregation associated with detwinning was responsible for the annealing hardening, while a reduced solid solution hardening for the annealing softening.

Radiation-Hardened Memristor-based Memory for Extreme Environments, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — NASA space exploration missions require radiation-hardened memory technologies that can survive and operate over a wide temperature range. Memristors...

Design optimization of radiation-hardened CMOS integrated circuits

International Nuclear Information System (INIS)

1975-01-01

Ionizing-radiation-induced threshold voltage shifts in CMOS integrated circuits will drastically degrade circuit performance unless the design parameters related to the fabrication process are properly chosen. To formulate an approach to CMOS design optimization, experimentally observed analytical relationships showing strong dependences between threshold voltage shifts and silicon dioxide thickness are utilized. These measurements were made using radiation-hardened aluminum-gate CMOS inverter circuits and have been corroborated by independent data taken from MOS capacitor structures. Knowledge of these relationships allows one to define ranges of acceptable CMOS design parameters based upon radiation-hardening capabilities and post-irradiation performance specifications. Furthermore, they permit actual design optimization of CMOS integrated circuits which results in optimum pre- and post-irradiation performance with respect to speed, noise margins, and quiescent power consumption. Theoretical and experimental results of these procedures, the applications of which can mean the difference between failure and success of a CMOS integrated circuit in a radiation environment, are presented

Linear Friction Welding Process Model for Carpenter Custom 465 Precipitation-Hardened Martensitic Stainless Steel

Science.gov (United States)

2014-04-11

Carpenter Custom 465 precipitation-hardened martensitic stainless steel to develop a linear friction welding (LFW) process model for this material...Model for Carpenter Custom 465 Precipitation-Hardened Martensitic Stainless Steel The views, opinions and/or findings contained in this report are... Martensitic Stainless Steel Report Title An Arbitrary Lagrangian-Eulerian finite-element analysis is combined with thermo-mechanical material

work hardening, recovery and recrystallization of alloys containing dispersed precipitates

International Nuclear Information System (INIS)

Padilha, A.F.

1989-01-01

This paper reviews the work hardening, recovery and recrystallization mechanisms in alloys containing dispersed precipitates. In the section on work hardening, the influence od spacing, particle size and shape on the density and distribution of dislocations have been discussed. They represent a large part of the energy stored in the material following drformation, which in turn is driving force for recrystallization. Next, the role of precipitates on recovery, on the formation and the growth of recrystallized regions has been discussed in detail. The competition between recovery and recrystallization and recrystallization of supersaturated solid solutions have also been mentioned. Finally, the technological relevance of the aspects treated in this paper has been discussed. (author) [pt

Experimental drying shrinkage of hardened cement pastes as a function of relative humidity

DEFF Research Database (Denmark)

Hansen, Kurt Kielsgaard; Baroghel, V.B.

1996-01-01

The results of an experimental study concerning drying shrinkage measured as a function of relative humidity on thin specimens of mature hardened cement pastes are presented. The results obtained at two laboratories are compared.......The results of an experimental study concerning drying shrinkage measured as a function of relative humidity on thin specimens of mature hardened cement pastes are presented. The results obtained at two laboratories are compared....

Work hardening and mechanical equation of state in some metals in monotonic loading

International Nuclear Information System (INIS)

Wire, G.L.; Ellis, F.V.; Li, C.Y.

The work hardening coefficients of Type 316 stainless steel, niobium, and 1100 aluminum alloy are measured in tensile tests. It is demonstrated experimentally that in the measured stress, plastic strain rate, and temperature range the work hardening coefficient depends only on stress and plastic strain rate. The significance of the experimental results is discussed in terms of the concept of the mechanical equation of state for plastic deformation. 13 figures

Observation of a New Mechanism Balancing Hardening and Softening in Metals

DEFF Research Database (Denmark)

Yu, Tianbo; Hansen, Niels; Huang, Xiaoxu

2014-01-01

Plastic deformation of metals refines the microstructure and increases the strength through work hardening, but this effect of deformation is counterbalanced by dynamic recovery. After large strain, the microstructure typically shows a lamellar morphology, with finely spaced lamellar boundaries...... connected by triple junctions. Here, we report that mechanically assisted triple junction motion is an important contributor to dynamic recovery, leading to an almost steady state. Triple junction motion replaces two boundaries by one, while maintaining the structural morphology. The observation...... rationalizes both a decreasing work hardening rate and the approach to a dynamic equilibrium of structural refinement at large strains....

Calculation of calcium diffusion coefficient of cement hardenings using minute pore data

International Nuclear Information System (INIS)

Hitomi, Takashi; Takeda, Nobufumi; Iriya, Keishiro

2009-01-01

This report describes the calculations of the diffusion coefficient of the Ca ion of cement hardenings using minute pore data. The observed hardenings were ordinary Portland cement (OPC), low-heat Portland cement with fly ash (LPC+FA) and highly fly ash containing silica fume cement (HFSC). The samples were cured in the standard and artificially leached by accelerated test. Minute pore datas of the cement hardenings were acquired with image processing of internal structural information obtained from high resolution X-ray computed tomography observations. Upon analysis, several voxels are combined into one bigger voxel, the diffusion coefficient of the voxels were determined in proportion to the number of voxels which were included in. The results reveal that the change in the calcium diffusion coefficient of OPC due to leaching was large, but the LPC+FA and HFSC cements exhibited even greater changes than OPC. It is suggested that the diffusion coefficients are proportional to the Ca/Si ratio of the samples. (author)

Microstructural evolution and hardening of GH3535 alloy under energetic Xe ion irradiation at room temperature and 650 °C

Science.gov (United States)

Huang, Hefei; Gao, Jie; Radiguet, Bertrand; Liu, Renduo; Li, Jianjian; Lei, Guanhong; Huang, Qing; Liu, Min; Xie, Ruobing

2018-02-01

The GH3535 alloy was irradiated with 7 MeV Xe26+ ions to a dose of 10 dpa at room temperature (RT) and 650 °C, and subsequently examined using Transmission Electron Microscopy (TEM) and nanoindentation. High numbers of nano-sized black dots, identified as dislocation loops were observed in both irradiated samples. The dislocation loops detected at the high temperature irradiated sample (size/number density: 9.5 nm/1.9 × 1021 m-3) were found to be larger in size but less in amount as compared to that of the case of RT irradiation (6.9 nm/18.7 × 1021 m-3). In addition, the large-sized Mo-Cr rich precipitates (16.4 nm/3.7 × 1021 m-3) were observed in the sample irradiated at 650 °C. Moreover, the Xe bubbles, with smaller size (2.9 nm) but higher number density (77.8 × 1021 m-3) among the irradiated induced defects, were also detected in the case of high temperature irradiated sample via the diffusion and aggregation of Xe atoms. Nanoindentaion measurements showed a hardening phenomenon for the irradiated sample, and the hardness increment is higher in the case of high temperature irradiated sample. Dispersed barrier-hardening (DBH) model was applied to predict the hardening produced from the irradiation induced defects. The yield strength increment calculated based on TEM observations and the nanohardness increment measured using nanoindentation are in excellent agreement.

SAGES: a suite of freely-available software tools for electronic disease surveillance in resource-limited settings.

Directory of Open Access Journals (Sweden)

Sheri L Lewis

Full Text Available Public health surveillance is undergoing a revolution driven by advances in the field of information technology. Many countries have experienced vast improvements in the collection, ingestion, analysis, visualization, and dissemination of public health data. Resource-limited countries have lagged behind due to challenges in information technology infrastructure, public health resources, and the costs of proprietary software. The Suite for Automated Global Electronic bioSurveillance (SAGES is a collection of modular, flexible, freely-available software tools for electronic disease surveillance in resource-limited settings. One or more SAGES tools may be used in concert with existing surveillance applications or the SAGES tools may be used en masse for an end-to-end biosurveillance capability. This flexibility allows for the development of an inexpensive, customized, and sustainable disease surveillance system. The ability to rapidly assess anomalous disease activity may lead to more efficient use of limited resources and better compliance with World Health Organization International Health Regulations.

SEGR- and SEB-hardened structure with DSPSOI in power MOSFETs

Science.gov (United States)

Tang, Zhaohuan; Fu, Xinghua; Yang, Fashun; Tan, Kaizhou; Ma, Kui; Wu, Xue; Lin, Jiexing

2017-12-01

Single event irradiation-hardened power MOSFET is the most important device for DC/DC converter in space environment application. Single event gate rupture (SEGR) and single event burnout (SEB), which will degrade the running safety and reliability of spacecraft, are the two typical failure modes in power MOSFETs. In this paper, based on recombination mechanism of interface between oxide and silicon, a novel hardened power MOSFETs structure for SEGR and SEB is proposed. The structure comprises double stagger partial silicon-on-insulator (DSPSOI) layers. Results show that the safety operation area (SOA) of a 130 V N-channel power MOSFET in single event irradiation environment is enhanced by up to 50% when the linear-energy-transfer value of heavy ion is a constant of 98 MeV·cm2/mg in the whole incident track, and the other parameters are almost maintained at the same value. Thus this novel structure can be widely used in designing single event irradiation-hardened power MOSFETs. Project supported by the National Natural Science Foundation of China (No. 61464002), the Grand Science and Technology Special Project in Guizhou Province of China (No. [2015]6006), and the Ministry of Education Open Foundation for Semiconductor Power Device Reliability (No. 010201).

Use and Cost of Electronic Resources in Central Library of Ferdowsi University Based on E-metrics

Directory of Open Access Journals (Sweden)

Mohammad Reza Davarpanah

2012-07-01

Full Text Available The purpose of this study was to investigate the usage of electronic journals in Ferdowsi University, Iran based on e-metrics. The paper also aimed to emphasize the analysis of cost-benefit and the correlation between the journal impact factors and the usage data. In this study experiences of Ferdowsi University library on licensing and usage of electronic resources was evaluated by providing a cost-benefit analysis based on the cost and usage statistics of electronic resources. Vendor-provided data were also compared with local usage data. The usage data were collected by tracking web-based access locally, and by collecting vender-provided usage data. The data sources were one-year of vendor-supplied e-resource usage data such as Ebsco, Elsevier, Proquest, Emerald, Oxford and Springer and local usage data collected from the Ferdowsi university web server. The study found that actual usage values differ for vendor-provided data and local usage data. Elsevier has got the highest usage degree in searches, sessions and downloads. Statistics also showed that a small number of journals satisfy significant amount of use while the majority of journals were used less frequent and some were never used at all. The users preferred the PDF rather than HTML format. The data in subject profile suggested that the provided e-resources were best suited to certain subjects. There was no correlation between IF and electronic journal use. Monitoring the usage of e-resources gained increasing importance for acquisition policy and budget decisions. The article provided information about local metrics for the six surveyed vendors/publishers, e.g. usage trends, requests per package, cost per use as related to the scientific specialty of the university.

Application of electron beam irradiation, (1). Development and application of electron beam processors

International Nuclear Information System (INIS)

Katsumura, Yosuke

1994-01-01

This paper deals with characteristics, equipment (principle and kinds), present conditions, and future issues in the application of electron beam irradiation. Characteristics of electron beams are described in terms of the following: chemical and biological effects of radiation; energy and penetrating power of electron beams; and principle and kinds of electron beam accelerator. Industrial application of electron beam irradiation has advantages of high speed procedure and producibility, less energy, avoidance of poisonous gas, and extreme reduction of organic solvents to be used. The present application of electron beam irradiation cen be divided into the following: (1) hardening of resin or coated membrane; (2) improvement of macromolecular materials; (3) environmental protection; (4) sterilization; (5) food sterilization. The present equipment for electron beam irradiation is introduced according to low energy, medium energy, and high energy equipment. Finally, future issues focuses on (1) the improvement of traceability system and development of electron dosimetric techniques and (2) food sterilization. (N.K.)

The shrinkage of hardening cement paste and mortar

NARCIS (Netherlands)

Haas, de G.D.; Kreijger, P.C.; Niël, E.M.M.G.; Slagter, J.C.; Stein, H.N.; Theissing, E.M.; Wallendael, van M.

1975-01-01

This paper is an abstract from the report of the commission B10: "The influence of the shrinkage of cement on the shrink-age of concrete", of the Netherlands Committee for Concrete Research. Measurements of pulse velocity, volume shrinkage and heat of hydration on hardening portland cement support

Radiation hardening of optical fibers and fiber sensors for space applications: recent advances

Science.gov (United States)

Girard, S.; Ouerdane, Y.; Pinsard, E.; Laurent, A.; Ladaci, A.; Robin, T.; Cadier, B.; Mescia, L.; Boukenter, A.

2017-11-01

In these ICSO proceedings, we review recent advances from our group concerning the radiation hardening of optical fiber and fiber-based sensors for space applications and compare their benefits to state-of-the-art results. We focus on the various approaches we developed to enhance the radiation tolerance of two classes of optical fibers doped with rare-earths: the erbium (Er)-doped ones and the ytterbium/erbium (Er/Yb)-doped ones. As a first approach, we work at the component level, optimizing the fiber structure and composition to reduce their intrinsically high radiation sensitivities. For the Erbium-doped fibers, this has been achieved using a new structure for the fiber that is called Hole-Assisted Carbon Coated (HACC) optical fibers whereas for the Er/Ybdoped optical fibers, their hardening was successfully achieved adding to the fiber, the Cerium element, that prevents the formation of the radiation-induced point defects responsible for the radiation induced attenuation in the infrared part of the spectrum. These fibers are used as part of more complex systems like amplifiers (Erbium-doped Fiber Amplifier, EDFA or Yb-EDFA) or source (Erbium-doped Fiber Source, EDFS or Yb- EDFS), we discuss the impact of using radiation-hardened fibers on the system radiation vulnerability and demonstrate the resistance of these systems to radiation constraints associated with today and future space missions. Finally, we will discuss another radiation hardening approach build in our group and based on a hardening-by-system strategy in which the amplifier is optimized during its elaboration for its future mission considering the radiation effects and not in-lab.

Microstructure-property relationships and constitutive response of plastically graded case hardened steels

Science.gov (United States)

Klecka, Michael A.

Case hardened materials, popularly used in many demanding engineering applications such as bearings, gears, and wear/impact surfaces, have high surface hardness and a gradient in material properties (hardness, yield strength, etc.) as a function of depth; therefore, they behave as plastically graded materials. In the current study, two different commercially available case carburized steels along with two through hardened steels are characterized to obtain relationships among the volume fraction of subsurface carbides, indentation hardness, elastic modulus, and yield strength as a function of depth. A variety of methods including microindentation, nanoindentation, ultrasonic measurements, compression testing, rule of mixtures, and upper and lower bound models are used to determine the relationships for elastic modulus and compare the experimental results with model predictions. In addition, the morphology, composition, and properties of the carbide particles are also determined. The gradient in hardness with depth in graded materials is commonly determined using microindentation on the cross-section of the material which contains the gradation in microstructure or composition. In the current study, a novel method is proposed to predict the hardness gradient profile using solely surface indentations at a range of loads. The method does not require the graded material to be sectioned, and has practical utility in the surface heat-treatment industry. For a material with a decreasing gradient in hardness, higher indent loads result in a lower measured hardness due to the influence of the softer subsurface layers. A power-law model is presented which relates the measured surface indentation hardness under increasing load to the subsurface gradient in hardness. A coordinated experimental and numerical study is presented to extract the constitutive response of graded materials, utilizing relationships between hardness, plastic deformation, and strain hardening response

Investigation on the effect of chemical composition on the texture and bake hardening I F steels

International Nuclear Information System (INIS)

Kariman, M.; Motaghi, A.; Raygan, Sh.; Habibi Parsa, M.; Nili Ahmadabadi, M.

2008-01-01

Interstitial free steels have good formability and also excellent deep draw ability. These features make them one of the applicable materials in automotive industry. Chemical composition and thermomechanical treatment used to process these steels have important role in final properties of them. In this study, the effect of chemical composition on texture, anisotropic properties and bake harden ability of these steels were investigated. The results showed that contribution of vanadium as a weak carbonitride former element with titanium as strong carbonitride former could change the texture of steels. Replacing titanium with vanadium caused harmful effect on mechanical properties. In this research deep drawing properties of five steels were compared based on I {111} / I{001} and I {111} / I{110} parameters. The results of bake harden ability test showed that there were critical limits for vanadium volume fractions above which bake harden properties was improved. It was shown that the bake harden properties of Nb-steels were better than that of Ti-steels. This was due to the better solution of Nb(C,N) compared to Ti(C,N). Addition of vanadium to Ti-steels may improve bake harden properties of I F steels

MICROSTRUCTURAL FEATURES EVALUATION OF AGE-HARDENED A 226 CAST ALLOY BY IMAGE ANALYSIS

Directory of Open Access Journals (Sweden)

Lenka Kuchariková

2018-01-01

Full Text Available Age-hardening provides one of the most widely used mechanisms for the strengthening of aluminum alloys. The age-hardening involves three steps: solution treatment, quenching and aging. The temperature of solution treatment and aging is very important in order to reach desired properties of castings. The optimum temperature of solution treatment and aging led to formation microstructural features in form which does not lead to decreasing properties, but increasing ones. The major microstructural features in A 226 cast alloys which are responsible for increasing properties are: eutectic Si particles, Cu-rich phases, Fe-rich phases and porosity. The increase of properties depends on morphology, size and volume of microstructural features. In order to assess age-hardening influence on microstructural features in A226 cast alloys were used as possibilities of evaluation by means of image analysis. Quantitative analysis decelerate changes in microstructure includes the spheroidization and coarsening of eutectic silicon, gradual disintegration, shortening and thinning of Fe-rich intermetallic phases, the dissolution of precipitates and the precipitation of finer hardening phase (Al2Cu further increase in the hardness and tensile strength in the alloy. Changes of mechanical properties were measured in line with STN EN ISO.

Influence of Cultivar on the Postharvest Hardening of Trifoliate Yam (Dioscorea dumetorum Tubers

Directory of Open Access Journals (Sweden)

Christian Siadjeu

2016-01-01

Full Text Available The influence of cultivar on the postharvest hardening of Dioscorea dumetorum tubers was assessed. 32 cultivars of D. dumetorum tubers were planted in April 2014, harvested at physiological maturity, and stored under prevailing tropical ambient conditions (19–28°C, 60–85% RH for 0, 5, 14, 21, and 28 days. Samples were evaluated for cooked hardness. Results showed that one cultivar, Ibo sweet 3, was not affected by the hardening phenomenon. The remaining 31 were all subject to the hardening phenomenon at different degree. Cooked hardness increased more rapidly in cultivars with many roots on the tuber surface compared to cultivars with few roots on the tuber surface. When both the characteristics flesh colour and number of roots on tuber surface were associated, cooked hardness in cultivars with yellow flesh and many roots increased more rapidly than in cultivars with white flesh and many roots, whereas cooked hardness in cultivars with yellow flesh and few roots increased more slowly than in cultivars with white flesh and few roots. Accessions collected in high altitude increased more rapidly compared to accessions collected in low altitude. The cultivar Ibo sweet 3 identified in this study could provide important information for breeding program of D. dumetorum against postharvest hardening phenomenon.

METHYL JASMONATE AND STEM BENDING HARDENING AND INITIAL GROWTH OF Cordia trichotoma SEEDLINGS

Directory of Open Access Journals (Sweden)

Danielle Acco Cadorin

2015-12-01

Full Text Available The submission of seedlings to mechanical stimuli and plant growth regulator promote their hardening and can be included in the routine of nurseries, favoring the survival and initial growth in the field. The study aimed to evaluate the effects of applying methyl jasmonate and stem bending in hardening and initial growth of Cordia trichotoma seedlings. Seedlings were subjected to 20 stem bending daily for 4 weeks; 20 stem bending daily for 8 weeks; 50 µmol.L-1 of methyl jasmonate applied weekly for 4 weeks; 50 µmol.L-1 of methyl jasmonate applied weekly for 8 weeks and the control treatment. The design was a completely randomized, with five repetitions of the fourteen seedlings. Seedlings submitted to hardening treatments showed less increment in height, greater increment in stem diameter and less value for strength index. Seedlings of control treatment had greater loss of root tissue electrolytes and less potential for root regeneration. In the field, 180 days after planting, seedlings submitted to eight weeks of stem bending and eight methyl jasmonate applications showed greater increment in height and stem diameter. The results indicate that both stem bending such as methyl jasmonate application for eight weeks are effective in promoting hardening and improve the starting performance in field of Cordia trichotoma seedlings.

Configurable Radiation Hardened High Speed Isolated Interface ASIC, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — NVE Corporation will design and build an innovative, low cost, flexible, configurable, radiation hardened, galvanically isolated, interface ASIC chip set that will...

Mechanical properties of metastable austenitic steels, strengthened by hydroextruction and structural hardening

International Nuclear Information System (INIS)

Beresnev, B.I.; Georgieva, I.Ya.; Eshchenko, R.N.; Teplov, V.A.

1981-01-01

Different regimes of complex strengthening of steels of Fe-Ni-Mo-C system by phase hardening and plastic deformation by hydroextrusion are investigated. It is stated that the degree of strengthening depends on consequence of strengthening operations. Plastic deformation by hydroextrusion of steels stre--ngthened by phase hardening ensures increase of strength (Δσsub(0.2)=500 MPa) at high plasticity (delta=25%). Maximal values of strength properties can be achieved if hydroextrusion is conducted before and after thansverse α→γ-transformation [ru

System Hardening Architecture for Safer Access to Critical Business ...

African Journals Online (AJOL)

System Hardening Architecture for Safer Access to Critical Business Data. ... and the threat is growing faster than the potential victims can deal with. ... in this architecture are applied to the host, application, operating system, user, and the ...

Characterization and hardenability evaluation of gray cast iron used in the manufacture of diesel engine cylinder liners

Directory of Open Access Journals (Sweden)

Edgar L. Castellanos-Leal

2017-09-01

Full Text Available The increment of the mechanical properties (surface hardness of engine cylinder is one of the principal goals for foundry company, to increase the competitiveness of their products in the local and foreign market. This study focused on the characterization of the gray cast iron used in the production of engine cylinder liners and metallurgical parameters determination in the design of conventional quenching heat treatment. The characterization was performed by material hardenability evaluation using Grossmann method, and Jominy test; the austenitizing temperature and the severity of cooling medium to a proper hardening of material were selected. Results revealed that the excellent hardness value obtained is attributed to the suitable hardenability of the gray cast iron and adequate severity selection for hardening treatment.

Hardening XL. Induction technology with rotating crankshaft; Haerten XL. Induktionstechnik mit rotierender Kurbelwelle

Energy Technology Data Exchange (ETDEWEB)

Dappen, Stefan; Schibisch, Dirk M. [SMS Elotherm GmbH, Remscheid (Germany)

2013-03-15

Crankshafts are used in combustion engines, transforming the con rod's stroke into a rotary motion for driving the axle shaft. Along with this, torsional and flexural fatigue appears and demands a special heat treatment process. The induction hardening with a rotating crankshaft has mostly replaced competitive methods and provides the engine builders with a flexible production process for varying geometries, different hardening zones as well as increasing production rates. (orig.)

Comparison of single and consecutive dual frequency induction surface hardening of gear wheels

Science.gov (United States)

Barglik, J.; Ducki, K.; Kukla, D.; Mizera, J.; Mrówka-Nowotnik, G.; Sieniawski, J.; Smalcerz, A.

2018-05-01

Mathematical modelling of single and consecutive dual - frequency induction surface hardening systems are presented and compared. The both models are solved by the 3D FEM-based professional software supported by a number of own numerical procedures. The methodology is illustrated with some examples of surface induction hardening of a gear wheel made of steel 41Cr4. The computations are in a good accordance with experiments provided on the laboratory stand.

Building and Managing Electronic Resources in Digital Era in India with Special Reference to IUCAA and NIV, Pune: A Comparative Case Study

Science.gov (United States)

Sahu, H. K.; Singh, S. N.

2015-04-01

This paper discusses and presents a comparative case study of two libraries in Pune, India, Inter-University Centre for Astronomy and Astrophysics and Information Centre and Library of National Institute of Virology (Indian Council of Medical Research). It compares how both libraries have managed their e-resource collections, including acquisitions, subscriptions, and consortia arrangements, while also developing a collection of their own resources, including pre-prints and publications, video lectures, and other materials in an institutional repository. This study illustrates how difficult it is to manage electronic resources in a developing country like India, even though electronic resources are used more than print resources. Electronic resource management can be daunting, but with a systematic approach, various problems can be solved, and use of the materials will be enhanced.

Induction surface hardening of hard coated steels

Energy Technology Data Exchange (ETDEWEB)

Pantleon, K.; Kessler, O.; Hoffann, F.; Mayr, P. [Stiftung Inst. fuer Werkstofftechnik, Bremen (Germany)

1999-11-01

The properties of hard coatings deposited using CVD processes are usually excellent. However, high deposition temperatures negatively influence the substrate properties, especially in the case of low alloyed steels. Therefore, a subsequent heat treatment is necessary to restore the properties of steel substrates. Here, induction surface hardening is used as a method of heat treatment after the deposition of TiN hard coatings on AISI 4140 (DIN42CrMo4) substrates. The influences of the heat treatment on both the coating and the substrate properties are discussed in relation to the parameters of induction heating. Thereby, the heating time, heating atmosphere and the power input into the coating-substrate compounds are varied. As a result of induction surface hardening, the properties of the substrates are improved without losing good coating properties. High hardness values in the substrate near the interface allow the AISI 4140 substrates to support TiN hard coatings very well. Consequently, higher critical loads are measured in scratch tests after the heat treatment. Also, compressive residual stresses in the substrate are generated. In addition, only a very low distortion appears. (orig.)

Preparation of Dispersion-Hardened Copper by Internal Oxidation

DEFF Research Database (Denmark)

Brøndsted, Povl; Sørensen, Ole Toft

1978-01-01

Internal oxidation experiments in CO2/CO atmospheres on Cu-Al alloys for preparation of dispersion-hardened Cu are described. The oxygen pressures of the atmospheres used in the experiments were controlled with a solid electrolyte oxygen cell based on ZrO2 (CaO). The particle size distributions o...

Radiation-hardened CMOS integrated circuits

International Nuclear Information System (INIS)

Pikor, A.; Reiss, E.M.

1980-01-01

Substantial effort has been directed at radiation-hardening CMOS integrated circuits using various oxide processes. While most of these integrated circuits have been successful in demonstrating megarad hardness, further investigations have shown that the 'wet-oxide process' is most compatible with the RCA CD4000 Series process. This article describes advances in the wet-oxide process that have resulted in multimegarad hardness and yield to MIL-M-38510 screening requirements. The implementation of these advances into volume manufacturing is geared towards supplying devices for aerospace requirements such as the Defense Meterological Satellite program (DMSP) and the Global Positioning Satellite (GPS). (author)

Behavior of surface residual stress in explosion hardened high manganese austenitic cast steel due to repeated impact loads

International Nuclear Information System (INIS)

Oda, Akira; Miyagawa, Hideaki

1985-01-01

Explosion hardened high manganese austenitic cast steel is being tried for rail crossing recently. From the previous studies, it became clear that high tensile residual stress was generated in the hardened surface layer by explosion and microcracks were observed. In this study, therefore, the behavior of surface residual stress in explosion hardened steel due to repeated impact loads was examined and compared with those of the original and shot peened steels. The results obtained are summarized as follows: (1) In the initial stage of the repetition of impact, high tensile surface residual stress in explosion hardened steel decreased rapidly with the repetition of impact, while those of the original and shot peened steels increased rapidly. This difference was attributed to the difference in depth of the work hardened layer in three testing materials. (2) Beyond 20 impacts the residual stress of three test specimens decreased gradually, and at more than 2000 impacts the compressive stress of about 500 MPa was produced regardless of the histories of working of testing materials. (3) The linear law in the second stage of residual stress fading was applicable to this case, and the range of the linear relationship was related to the depth of the work hardened layer of testing material. (4) From the changes in half-value breadth and peak intensity of diffraction X-ray, it was supposed that a peculiar microscopic strain exists in explosion hardened steel. (author)

Space Qualified, Radiation Hardened, Dense Monolithic Flash Memory, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Radiation hardened nonvolatile memories for space is still primarily confined to EEPROM. There is high density effective or cost effective NVM solution available to...

A Low Power Rad-Hard ADC for the KID Readout Electronics, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The proposal aims to develop a radiation hardened analog-to-digital converter (ADC) required for the Kinetic Inductance Detector (KID) readout electronics. KIDs are...

New Stainless Steel Alloys for Low Temperature Surface Hardening?

DEFF Research Database (Denmark)

Christiansen, Thomas Lundin; Dahl, Kristian Vinter; Somers, Marcel A. J.

2015-01-01

The present contribution showcases the possibility for developing new surface hardenable stainless steels containing strong nitride/carbide forming elements (SNCFE). Nitriding of the commercial alloys, austenitic A286, and ferritic AISI 409 illustrates the beneficial effect of having SNCFE presen...

Re-hardening of hadron transverse mass spectra in relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Ohnishi, A.; Otuka, N.; Sahu, P.K.; Isse, M.; Nara, Y.

2001-01-01

We analyze the spectra of pions and protons in heavy-ion collisions at relativistic energies from 2 A GeV to 65 + 65 A GeV by using a jet-implemented hadron-string cascade model. In this energy region, hadron transverse mass spectra first show softening until SPS energies, and re-hardening may emerge at RHIC energies. Since hadronic matter is expected to show only softening at higher energy densities, this re-hardening of spectra can be interpreted as a good signature of the quark-gluon plasma formation. (author)