WorldWideScience

Sample records for age hardening

  1. Design of an age hardening Mg-Li alloy and its aging behavior

    Institute of Scientific and Technical Information of China (English)

    Hao Zhong; Peiying Liu; Tietao Zhou; Huanxi Li

    2005-01-01

    An effort was made to design an age hardening Mg-Li alloy based on the phase diagrams calculated by means of "THERMO-CALC"-a thermodynamic software. Experiments were carried out to verify the calculated results by melting the alloy and examining its structure and aging behavior. The results show that the alloy possesses a structure constituent as expected, besides,the alloy has apparent aging behavior and over aging happens even at lower temperature. Metastable (Mg, Li, Al, Zn) phase has been identified when the hardness reaches the aging peak. With the increase of the aging time, (Mg, Li, Al, Zn) phase transforms to stable α phase and over aging happens.

  2. 'Age-hardened alloy' based on bulk polycrystalline oxide ceramic

    Science.gov (United States)

    Gurnani, Luv; Singh, Mahesh Kumar; Bhargava, Parag; Mukhopadhyay, Amartya

    2015-05-01

    We report here for the first time the development of 'age-hardened/toughened' ceramic alloy based on MgO in the bulk polycrystalline form. This route allows for the facile development of a 'near-ideal' microstructure characterized by the presence of nanosized and uniformly dispersed second-phase particles (MgFe2O4) within the matrix grains, as well as along the matrix grain boundaries, in a controlled manner. Furthermore, the intragranular second-phase particles are rendered coherent with the matrix (MgO). Development of such microstructural features for two-phase bulk polycrystalline ceramics is extremely challenging following the powder metallurgical route usually adopted for the development of bulk ceramic nanocomposites. Furthermore, unlike for the case of ceramic nanocomposites, the route adopted here does not necessitate the usage of nano-powder, pressure/electric field-assisted sintering techniques and inert/reducing atmosphere. The as-developed bulk polycrystalline MgO-MgFe2O4 alloys possess considerably improved hardness (by ~52%) and indentation toughness (by ~35%), as compared to phase pure MgO.

  3. Continuous Hardening During Isothermal Aging at 723 K (450 °C) of a Precipitation Hardening Stainless Steel

    Science.gov (United States)

    Celada-Casero, Carola; Chao, Jesús; Urones-Garrote, Esteban; San Martin, David

    2016-06-01

    The isothermal aging behavior of a cold-rolled precipitation hardening stainless steel has been studied at 723 K (450 °C) for holding times up to 72 hours. The precipitation hardening has been investigated using microhardness Vickers (Hv), thermoelectric power (TEP) measurements, and tensile testing. Microhardness compared to TEP measurements is more sensitive to detect the initial stages of aging. Two precipitation regimes have been observed: the first one related to the formation of Cu-clusters for aging times below 1 hour and a second one associated with formation of Ni-rich precipitates. The results show that the material exhibits an outstanding continuous age strengthening response over the aging time investigated, reaching a hardness of 710 ± 4 HV1 and an ultimate tensile strength (σ UTS) of 2.65 ± 0.02 GPa after 72 hours. Engineering stress-plastic strain curves reveal that the strength increases and the ductility decreases as the aging time increases. However, after prolonged holding times (24-72 hours) and, although small, a rise in both the strength and the total elongation is observed. The precipitation kinetics can be well predicted over the entire range of aging times by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. Finally, a reliable linear hardness-yield strength correlation has been found, which enables a rapid evaluation of the strength from bulk hardness measurements.

  4. Effects of Ce additions on the age hardening response of Mg–Zn alloys

    International Nuclear Information System (INIS)

    The effects of Ce additions on the precipitation hardening behaviour of Mg–Zn are examined for a series of alloys, with Ce additions at both alloying and microalloying levels. The alloys are artificially aged, and studied using hardness measurement and X-ray diffraction, as well as optical and transmission electron microscopy. It is found that the age-hardening effect is driven by the formation of fine precipitates, the number density of which is related to the Zn content of the alloy. Conversely, the Ce content is found to slightly reduce hardening. When the alloy content of Ce is high, large secondary phase particles containing both Ce and Zn are present, and remain stable during solutionizing. These particles effectively reduce the amount of Zn available as solute for precipitation, and thereby reduce hardening. Combining hardness results with thermodynamic analysis of alloy solute levels also suggests that Ce can have a negative effect on hardening when present as solutes at the onset of ageing. This effect is confirmed by designing a pre-ageing heat treatment to preferentially remove Ce solutes, which is found to restore the hardening capability of an Mg–Zn–Ce alloy to the level of the Ce-free alloy. - Highlights: • The effects of Ce additions on precipitation in Mg–Zn alloys are examined. • Additions of Ce to Mg–Zn slightly reduce the age-hardening response. • Ce-rich secondary phase particles deplete the matrix of Zn solute. • Hardening is also decreased when Ce is present in solution. • Pre-ageing to preferentially precipitate out Ce restores hardening capabilities

  5. 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...

  6. Ageing and work-hardening behaviour of a commercial AA7108 aluminium alloy

    International Nuclear Information System (INIS)

    In the 7xxx aluminium alloying system several mechanisms influence the hardening behaviour of the alloys, e.g. particle size and distribution, dislocation density and alloying elements in solid solution. This work is an experimental study of ageing and work-hardening considering a commercial AA7108 alloy in the as-cast and homogenized condition. Tensile specimens have been exposed to a solution heat treatment and a two-step age-hardening treatment with varying time at the final temperature. The tensile data for the different tempers have been evaluated in elucidation of already existing models based on a one-parameter framework. The precipitate size and distribution have been further investigated in the transmission electron microscope for a selection of tempers, and the influence of these parameters on the work-hardening behaviour has been discussed.

  7. Precipitation Reactions in Age-Hardenable Alloys During Laser Additive Manufacturing

    Science.gov (United States)

    Jägle, Eric A.; Sheng, Zhendong; Wu, Liang; Lu, Lin; Risse, Jeroen; Weisheit, Andreas; Raabe, Dierk

    2016-03-01

    We describe and study the thermal profiles experienced by various age-hardenable alloys during laser additive manufacturing (LAM), employing two different manufacturing techniques: selective laser melting and laser metal deposition. Using scanning electron microscopy and atom probe tomography, we reveal at which stages during the manufacturing process desired and undesired precipitation reactions can occur in age-hardenable alloys. Using examples from a maraging steel, a nickel-base superalloy and a scandium-containing aluminium alloy, we demonstrate that precipitation can already occur during the production of the powders used as starting material, during the deposition of material (i.e. during solidification and subsequent cooling), during the intrinsic heat treatment effected by LAM (i.e. in the heat affected zones) and, naturally, during an ageing post-heat treatment. These examples demonstrate the importance of understanding and controlling the thermal profile during the entire additive manufacturing cycle of age-hardenable materials including powder synthesis.

  8. Analysis of modulus hardening in an artificial aged Al–Cu–Mg alloy by atom probe tomography

    International Nuclear Information System (INIS)

    The individual contribution of different Cu–Mg co-clusters by modulus hardening to age-hardening response of an Al–Cu–Mg alloy at 170 °C is evaluated based on Vickers hardness measurements and quantitative atom probe tomography analysis. The present results show that it is order hardening of large Cu-Mg co-clusters or GPB zones rather than modulus hardening significantly contributes to the second stage of hardening. Despite prolonged aging from 5 min to 8 h leads to a noticeable change in the number density and the volume fraction of different Cu-Mg co-clusters, interestingly, the total critical shear stress of Cu-Mg co-clusters by modulus hardening fluctuates slightly, indicating the modulus hardening effect almost keeps unchanged at the hardness plateau. Besides, the shear modulus of Cu-Mg co-clusters is found to remain constant as aging prolongs at 170 °C

  9. Integrated Precipitate Simulation for Friction Stir Welding of Age Hardening Aluminium Alloys

    OpenAIRE

    Hersent, Emmanuel

    2010-01-01

    Friction stir welding (FSW) is a recent welding process invented by The Welding Institute (TWI). It is particularly interesting for the aeronautical sector due to its capacity to weld 2XXX and 7XXX age-hardening aluminium alloys, which were previously considered unweldable. This relatively new process is currently the subject of active research. This work aims to simulate the hardness profile of an AA2024-T3 friction stir weld. AA2024-T3 is an age hardening aluminium alloy, so it is necessary...

  10. Magnetic evaluation of the hardening and softening of thermally aged iron-copper alloys

    International Nuclear Information System (INIS)

    We evaluated the variations of the magnetic hysteretic behaviour of Fe-1wt%Cu model alloy samples due to thermal aging and over-aging. In these alloys, the formation and growth of Cu-precipitates during the thermal aging process results in mechanical hardening, whereas for aging times higher than a certain critical value, mechanical softening occurs. Magnetic hysteretic properties such as permeability, remanence, peak value and width of the local interaction field distribution, which is related to the Preisach model, are measured as a function of various Cu-precipitation stages obtained by time dependent heat treatments at 773 K (500 deg. C). We found that all magnetic parameters exhibit an extremum value for the peak hardening sample. Furthermore, the variation of permeability, remanence, and the peak value of the local interaction field distribution mimics the behaviour of the reciprocal value of the yield stress as a function of aging time. These results suggest that the magnetic domain wall movement is hindered mainly by Cu-precipitates upon thermal aging. The peak hardening values of the investigated magnetic parameters change by approximately 50% when compared with the initial values. This pronounced sensitivity indicates the potential of magnetic non-destructive evaluation for the assessment of the hardening and softening phenomena induced by Cu-precipitation

  11. Modifications of the Response of Materials to Shock Loading by Age Hardening

    Science.gov (United States)

    Millett, Jeremy C. F.

    2015-10-01

    The shock response of two age-hardened alloys, aluminum 6061 and copper-2 wt pct beryllium (CuBe), has been investigated in terms of their microstructual state; either solution treated or age hardened. While age hardening induces large increases in strength at quasi-static strain rates, age hardening does not produce the same magnitude of strength increase during shock loading. Examination of the shocked microstructures (of 6061) indicates that the presence of a fine distribution of precipitates throughout the microstructure hinders the motion and generation of dislocations and hence reduces the strain-rate sensitivity of the aged material, thus allowing the properties of the solution-treated state to approach those of the aged. It has also been observed that the shear strength of solution-treated CuBe is near identical to that of pure copper. It is suggested that this is the result of two competing processes; large lattice strains as beryllium substitutes onto the copper lattice inducing a high degree of solution strengthening acting against a reduction in shear strength caused by twinning in the alloy.

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

    International Nuclear Information System (INIS)

    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 Ni3Al ordered phase. After aging at temperature range from 420 to 590 °C, spherical Ni3Al precipitates and ellipsoidal M23C6 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 Ni3Al 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. • Ni3Al 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

  13. Nature of strain aging stages in bake hardening steel for automotive application

    International Nuclear Information System (INIS)

    Strain aging behavior of industrially produced ultra low carbon bake hardening (BH) steel for automotive application was investigated. The aging process was studied by the dynamic Young's modulus and amplitude-independent dislocation internal friction measurements with acoustic methods. Analysis of the revealed strain aging stages was carried out and has resulted in the conclusion that formation of interstitial atoms atmospheres on the dislocations is accompanied and substantially affected by the dissolution of their grain boundary segregations

  14. Influence of natural aging on the precipitation hardening of an AlMgSi alloy

    International Nuclear Information System (INIS)

    The influence of natural aging on precipitation hardening of an Al-Mg-Si alloy was investigated by mechanical testing and quantitative transmission electron microscopy. It was found that natural aging increases yield stress and reduces ductility, which is attributed to the formation of Mg/Si clusters. The evolution of tensile properties saturates after around 7 days natural aging. Artificial aging for 30 min at 180 deg. C after solution treatment resulted in an important increase in yield strength and loss of ductility, due to the rapid precipitation of the β'' intermediate phase. Previous natural aging progressively reduces the strengthening effect of 30 min/180 deg. C artificial aging, completely suppressing it after 7 days pre-aging. Microhardness evolution during 180 deg. C artificial aging was followed in samples that were aged immediately after quenching, and with 7 days natural aging before artificial aging. In addition, microstructural characterization using TEM was carried out at specific artificial aging times. Previous natural aging was found to reduce the initial hardening rate, producing a delay in the formation of β'' precipitates. The peak-aging condition was reached almost at the same aging time. However, longer β'' precipitates with a lower volume fraction were observed when artificial aging was preceded by natural aging.

  15. Hardening of aged duplex stainless steels by spinodal decomposition.

    Science.gov (United States)

    Danoix, F; Auger, P; Blavette, D

    2004-06-01

    Mechanical properties, such as hardness and impact toughness, of ferrite-containing stainless steels are greatly affected by long-term aging at intermediate temperatures. It is known that the alpha-alpha' spinodal decomposition occurring in the iron-chromium-based ferrite is responsible for this aging susceptibility. This decomposition can be characterized unambiguously by atom probe analysis, allowing comparison both with the existing theories of spinodal decomposition and the evolution of some mechanical properties. It is then possible to predict the evolution of hardness of industrial components during service, based on the detailed knowledge of the involved aging process. PMID:15233853

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

    International Nuclear Information System (INIS)

    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′ (Al3Zr) dispersoids, quenched-in vacancies and dislocations. Though most of the fine and uniform precipitates θ′ (Al2Cu), δ′ (Al3Li), σ (Al5Cu6Mg2) 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 T1 (Al2CuLi), 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

  17. Age-hardening characteristic of an Al-Zn-Mg-Cu alloy produced by spray deposition

    Institute of Scientific and Technical Information of China (English)

    WANG Feng; XIONG Baiqing; ZHANG Yongan; ZHU Baohong; LIU Hongwei; ZHANG Zhihui; WANG Zixing

    2007-01-01

    Al-10.8Zn-2.8Mg-1.9Cu alloy was synthesized by spray atomization and deposition technique. GP zones and age-hardening process in the alloy were investigated using high-resolution electron microscopy (HREM), selected area diffraction (SAD), and differential scanning calorimetry (DSC) analysis. The results indicated that spray deposition process accelerated the aging kinetics of the alloy at an aging temperature of 120℃, thereby reducing the peak aging time to 16 h.GPI and GPⅡ are the two types of zones that are major precipitates for the alloy under peak-aged condition. The precipitation sequence for the alloy is also discussed.

  18. Age hardening in beryllium-aluminum-silver alloys

    International Nuclear Information System (INIS)

    Three different alloys of beryllium-aluminum-silver were processed to powder by centrifugal atomization in a helium atmosphere. Alloy compositions were, by weight percent, Be-47.5Al-2.5Ag, Be-47Al-3Ag, and Be-46Al-4Ag. Due to the low solubility of both aluminum and silver in beryllium, the silver was concentrated in the aluminum phase, which separates from the beryllium in the liquid phase. A fine, continuous composite beryllium-aluminum microstructure was formed, which did not significantly change after hot isostatic pressing. Samples of hot isostatically pressed material were solution treated at 550 C for 1 h, followed by a water quench. Aging temperatures were 150, 175, 200, and 225 C for times ranging from half an hour to 65 h. Results indicate that peak hardness was reached in 36--40 h at 175 C and 12--16 h at 200 C aging temperature, relatively independent of alloy composition

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

    International Nuclear Information System (INIS)

    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.

  20. Resistivity measurement by eddy current methods for real-time monitoring of age hardening in heat treatable alloys

    OpenAIRE

    James, Robert Bailey

    1996-01-01

    In this research, the design of an eddy current sensor system that continuously monitors age hardening during aging of heat treatable alloys was modified to allow for operation at temperatures up to 595 deg C. With two eddy current coils in an impedance bridge circuit, eddy currents are generated in a pure aluminum reference sample standard and an age harden able test sample. The difference in the resistivity of the aging test sample relative to the reference sample results in a bridge unbala...

  1. Development and Determination of the Age Hardening Characteristics of Al-2.00Mg-2.66Si Wrought Alloy

    OpenAIRE

    Ihom, A.P.; Offiong, Aniekan

    2016-01-01

    International audience The study, was carried out by developing the alloy using the foundry route of melting, alloying, and casting. The produced test samples were machined to produce test specimens which were subjected to precipitation hardening treatment. The test specimens were for impact and hardness test to inference the response of the developed alloy to age hardening treatment. The ageing temperature was 190 o C, and the ageing time was from 1-5 hrs. The control specimen was not age...

  2. 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

  3. MICROSTRUCTURES AND THE STRUCTURE STABILITY OF INCONEL 725, A NEW AGE-HARDENABLE CORROSION RESISTANT SUPERALLOY

    Institute of Scientific and Technical Information of China (English)

    J.X. Dong; M.C. Zhang; S.K. Mannan

    2003-01-01

    INCONEL725 is a highly corrosion resistant nickel based alloy capable of being age-hardened to high strength levels. The microstructure observations and the phase iden-tification after a standard heat treatment were investigated. The results show thatmary carbide phase TiC, as well as M6C carbide and a little extent MC (mainly TiC)precipitates which nucleate mainly at grain boundaries. An isothermal aging studywas carried out on this alloy for up to 10 000 hours at 593℃. This additional agingdid not affect the tensile strength. However, microstructures show that the thermalexposure has a little additional effect. With increasing the exposure time, the size ofcipitated at grain boundaries have an increased and complex tendency on a few grainboundaries. The experimental results illustrate the excellent structure stability of theage-hardenable IN725 at 593℃.

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

    International Nuclear Information System (INIS)

    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 α1 phase and the Pd-containing Cu-rich α2 phase were transformed into four phases of the Ag-rich α1' phase, the Cu-rich α2' phase, the CsCl-type CuPd phase and the AuCu(I) ordered phase. Microstructure of the solution-treated specimen consisted of the Ag-rich α1 matrix, Cu-rich α2 particle-like structures of various sizes and the lamellar structure of the α1 and α2 phases. When the peak hardness was obtained, the very fine lamellar structure consisting of the Ag-rich α1' and Cu-rich α2' 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 α1 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

  5. Effect of cold work on the age hardening behaviour of A1 2014 A1 alloy

    International Nuclear Information System (INIS)

    The Al 2014 alloy was hardened to a considerable extent by subjecting it to solution-heat-treatment at 502C for 2 hours water quenching and then aging, both natural and artificial. Hardness increased to 113HV from the as-cast value of 85HV during natural aging and increased further to 136HV and 145HV when aged at 180 degree C and 232 degree C for only one hour. The hardness increased significantly when the alloy was cold worked to various degrees by rolling after solution treatment and water quenching, and then artificially aged. Maximum hardness values obtained were 188.7 HV and 191.6 HV which corresponded to 44% and 48% cold deformation respectively at the aging temperature of 180 degree C for only one hour aging time. (author)

  6. Aging of medium strength aluminum alloy friction stir welds produced by different process parameter after tensile strain hardening

    International Nuclear Information System (INIS)

    Effect of tool rotation rate and travel speed on aging of 6082T6 friction stir welds after tensile strain hardening were investigated using Vickers microhardness (HV) measurements and precipitation hardening concepts. Tensile tests were performed at constant strain rate up to natural fracture followed by aging at low and medium temperatures. The results showed that HV measured on strain hardened FSW joints was not very sensitive to travel speeds experienced during FSW process, at constant rotation rate; anyway, strain hardening was very effective on hardness and induce an average increase by 20–25% in the stirred zone (SZ). Strain hardening was also very effective on aging at 200 °C, while it was not at 300 °C. At this temperature, HV assumed uniform values along joint cross section. - Highlights: • FSW joints have been investigated after tensile deformation and aging. • Tensile strain hardening induces a 20–25% HV increment in the stirred zone. • Subsequent aging at 200 °C did not substantially modify hardness profiles. • After aging at 300 °C, HV values were uniform and lower than HV minimum

  7. Aging of medium strength aluminum alloy friction stir welds produced by different process parameter after tensile strain hardening

    Energy Technology Data Exchange (ETDEWEB)

    Cerri, Emanuela, E-mail: emanuela.cerri@unipr.it; Leo, Paola

    2014-10-15

    Effect of tool rotation rate and travel speed on aging of 6082T6 friction stir welds after tensile strain hardening were investigated using Vickers microhardness (HV) measurements and precipitation hardening concepts. Tensile tests were performed at constant strain rate up to natural fracture followed by aging at low and medium temperatures. The results showed that HV measured on strain hardened FSW joints was not very sensitive to travel speeds experienced during FSW process, at constant rotation rate; anyway, strain hardening was very effective on hardness and induce an average increase by 20–25% in the stirred zone (SZ). Strain hardening was also very effective on aging at 200 °C, while it was not at 300 °C. At this temperature, HV assumed uniform values along joint cross section. - Highlights: • FSW joints have been investigated after tensile deformation and aging. • Tensile strain hardening induces a 20–25% HV increment in the stirred zone. • Subsequent aging at 200 °C did not substantially modify hardness profiles. • After aging at 300 °C, HV values were uniform and lower than HV minimum.

  8. Influence of ECAP on the fatigue behavior of age-hardenable 2xxx aluminum alloy

    Science.gov (United States)

    Namdar, M.; Jahromi, S. A. Jenabali

    2015-03-01

    The fatigue behavior under load control and the mechanical properties of commercial 2011 aluminum as an age-hardenable Al alloy was studied. To estimate the effects of the equal channel angular pressing (ECAP) process, solution heat treatments, and aging on the fatigue life, tests were conducted at four different stages: furnace cooling; furnace cooling plus one ECAP pass; solid solution heat treatment, quenching, one ECAP pass plus aging at peak age level; and the T6 condition. Only one pass was possible at room temperature because of the high strength of the material. The fracture surface morphology and microstructure after fatigue were evaluated by scanning electron microscopy (SEM). The experimental results revealed that the optimum fatigue life under load control, the tensile strength, and the Vickers hardness of the material were interdependent. The optimum fatigue life under load control was achieved by increasing the tensile strength and hardness of the material.

  9. Influence of ECAP on the fatigue behavior of age-hardenable 2xxx aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    M. Namdar; S.A. Jenabali Jahromi

    2015-01-01

    The fatigue behavior under load control and the mechanical properties of commercial 2011 aluminum as an age-hardenable Al al-loy was studied. To estimate the effects of the equal channel angular pressing (ECAP) process, solution heat treatments, and aging on the fa-tigue life, tests were conducted at four different stages:furnace cooling;furnace cooling plus one ECAP pass;solid solution heat treatment, quenching, one ECAP pass plus aging at peak age level;and the T6 condition. Only one pass was possible at room temperature because of the high strength of the material. The fracture surface morphology and microstructure after fatigue were evaluated by scanning electron mi-croscopy (SEM). The experimental results revealed that the optimum fatigue life under load control, the tensile strength, and the Vickers hardness of the material were interdependent. The optimum fatigue life under load control was achieved by increasing the tensile strength and hardness of the material.

  10. Structural and age hardening characteristics of near eutectic Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Kamalpreet; Pandey, Om Prakash [Thapar Univ., Patiala (India). School of Physics and Materials Science

    2010-09-15

    In the present work structural features of near eutectic Al-Si and Al-Si-Cu alloys prepared by a normal melting and casting route are studied. It is observed that morphology of Si plays an important role in enhancing the mechanical properties of Al-Si alloys. In order to modify the Si network in the matrix of Al some immiscible elements such as Pb, Sn, Cd and Bi have been added in small quantities to the alloy. Since the structure developed after casting governs the mechanical properties, it is essential to understand the structural features before testing the mechanical properties. Taking into consideration the age hardening characteristics of the alloys, microstructural assessment and a thermal study of these alloys have been done. Thermal analysis shows that immiscible elements are homogeneously distributed in the alloys. It is observed that the addition of Pb leads to a rosette type structure, whereas in the case of Cd and Sn blunt and twisted Si needles can be seen. The structural features of the eutectic change to hypoeutectic completely on addition of Bi. The shift in the eutectic depression on addition of a ternary element causes a change in the morphology of Si. Addition of Cu to the Al-Si alloys gives precipitation hardening characteristics. (orig.)

  11. Effect of Al Addition on ω Precipitation and Age Hardening of Ti-Al-Mo-Fe Alloys

    Science.gov (United States)

    Li, Chenglin; Lee, Dong-Geun; Mi, Xujun; Ye, Wenjun; Hui, Songxiao; Lee, Yongtai

    2016-05-01

    The effect of Al addition on ω precipitation and age-hardening behavior of Ti-9.2Mo-2Fe and Ti-2Al-9.2Mo-2Fe alloy during aging treatment was investigated. The results showed that athermal and isothermal ω phase formation in Ti-2Al-9.2Mo-2Fe alloy was suppressed to a certain extent due to Al addition. In addition, a small amount of athermal ω phase was observed in the β matrix with a size of about ~5 nm during water quenching from above the β transus temperature for both alloys. Isothermal ω formation was also found during aging at temperatures ranging from 573 K to 773 K (300 °C to 500 °C) in both alloys, although it had a limited time of stability at 773 K (500 °C). The hardening due to isothermal ω precipitation exhibited no over-aging as long as ω phase existed in both alloys, and ω phase played a more important role in hardening than α phase. And the ω phase in 50 to 100 nm size exhibited the best hardening effect in Ti-9.2Mo-2Fe alloy. Similarly, α phase with 100 to 200 nm in length showed better hardening effects in Ti-2Al-9.2Mo-2Fe alloy. Both the alloys showed stronger age hardening at an intermediate temperature of 673 K (400 °C) and in the first aging stage at a higher temperature of 773 K (500 °C) due to the sufficiently fine size (50 nm), while they exhibited weaker age hardening at a lower temperature of 573 K (300 °C) and long period aging at a higher temperature of 773 K (500 °C) due to incomplete ω formation and/or coarsening of α phase. No over or peak aging stage was found at 573 K and 673 K (300 °C and 400 °C) during the aging for 72 hours, while the peak hardness values of both alloys aged at 773 K (500 °C) were obtained in the first stage of aging. The hardness of the alloys was very sensitive to size and volume fraction of ω phase, which depends on aging temperature, time, and composition of the involved alloys.

  12. Investigation of Clusters in Medium Carbon Secondary Hardening Ultra-high-strength Steel After Hardening and Aging Treatments

    Science.gov (United States)

    Veerababu, R.; Balamuralikrishnan, R.; Muraleedharan, K.; Srinivas, M.

    2015-06-01

    Clusters, containing between 10 and 1000 atoms, have been investigated in a martensitic secondary hardening ultra-high-strength steel austenitized at 1173 K (900 °C) for 1 hour and tempered at either 768 K or 783 K (495 °C or 510 °C) for 4 or 8 hours using 3D atom probe. The presence of clusters was unambiguously established by comparing the observed spatial distribution of the different alloying elements against the corresponding distribution expected for a random solid solution. Maximum separation envelope method has been used for delineating the clusters from the surrounding "matrix." Statistical analysis was used extensively for size and composition analyses of the clusters. The clusters were found to constitute a significant fraction accounting for between 1.14 and 2.53 vol pct of the microstructure. On the average, the clusters in the 783 K (510 °C) tempered sample were coarser by ~65 pct, with an average diameter of 2.26 nm, relative to the other samples. In all samples, about 85 to 90 pct of the clusters have size less than 2 nm. The percentage frequency histograms for carbon content of the clusters in 768 K and 783 K (495 °C and 510 °C) tempered samples revealed that the distribution shifts toward higher carbon content when the tempering temperature is higher. It is likely that the presence of these clusters exerts considerable influence on the strength and fracture toughness of the steel.

  13. Precipitation hardening and microstructure evolution of the Ti-7Nb-10Mo alloy during aging.

    Science.gov (United States)

    Yi, Ruowei; Liu, Huiqun; Yi, Danqing; Wan, Weifeng; Wang, Bin; Jiang, Yong; Yang, Qi; Wang, Dingchun; Gao, Qi; Xu, Yanfei; Tang, Qian

    2016-06-01

    A biomedical β titanium alloy (Ti-7Nb-10Mo) was designed and prepared by vacuum arc self-consumable melting. The ingot was forged and rolled to plates, followed by quenching and aging. Age-hardening behavior, microstructure evolution and its influence on mechanical properties of the alloy during aging were investigated, using X-ray diffraction, transmission electron microscopy, tensile and hardness measurements. The electrochemical behavior of the alloy was investigated in Ringer's solution. The microstructure of solution-treated (ST) alloy consists of the supersaturated solid solution β phase and the ωath formed during athermal process. The ST alloy exhibits Young's modulus of 80 GPa, tensile strength of 774 MPa and elongation of 20%. The precipitation sequences during isothermal aging at different temperatures were determined as β+ωath→β+ωiso (144 h) at Taging=350-400 °C, β+ωath→β+ωiso+α→β+α at Taging=500°C, and β+ωath→β+α at Taging=600-650 °C, where ωiso forms during isothermal process. The mechanical properties of the alloy can be tailored easily through controlling the phase transition during aging. Comparing with the conventional Ti-6Al-4V alloy, the Ti-7Nb-10Mo alloy is more resistant to corrosion in Ringer's solution. Results show that the Ti-7Nb-10Mo alloy is promising for biomedical applications. PMID:27040253

  14. Coarsening and Age Hardening Behaviors of γ'Particles in GH742 During High Temperature Treatment

    Institute of Scientific and Technical Information of China (English)

    LI Hong-yu; SONG Xi-ping; WANG Yan-li; CHEN Guo-liang

    2009-01-01

    The coarsening and ageing hardening behaviors of γ' particles in superalloy GH742 have been investigated by field emission scanning electron microscopy (FESEM), coarsening kinetics calculation and microhardness testing when ageing at 1 050, 950 and 900 ℃ for different time. The cube of γ particle size and ageing time follows a linear law as predicted by LSW theory. The particle size distributions give better fit to the LSW theoretical distribution. The activation energy for γ' coarsening is accurately determined to have 245. 06±14. 42 kJ/mol when considering the effect of temperature on the solution concentrations in matrix. Based on the activation energy, the coarsening kinetics of γ' particle is predicted as r3t=7.35×1015Ce/Texp-(245 060±14 420)/RT t. The microhardness studies indicate that microhardness decreases rapidly with increasing the ageing temperature and it has a maximum value corresponding to a critical particle size beyond which the microhardness increase stalls with increasing the ageing time.

  15. Correlation of Fe/Cr phase decomposition process and age-hardening in Fe–15Cr ferritic alloys

    International Nuclear Information System (INIS)

    The effects of thermal aging on the microstructure and mechanical properties of Fe–15Cr ferritic model alloys were investigated by TEM examinations, micro-hardness measurements and tensile tests. The materials used in this work were Fe–15Cr, Fe–15Cr–C and Fe–15Cr–X alloys, where X refers to Si, Mn and Ni to simulate a pressure vessel steel. Specimens were isothermally aged at 475 °C up to 5000 h. Thermal aging causes a significant increase in the hardness and strength. An almost twice larger hardening is required for embrittlement of Fe–15Cr–X relative to Fe–15Cr. The age-hardening is mainly due to the formation of Cr-rich α′ precipitates, while the addition of minor elements has a small effect on the saturation level of age-hardening. The correlation of phase decomposition process and age-hardening in Fe–15Cr alloy was interpreted by dispersion strengthened models

  16. Influence of the microstructure of an age hardening alloy on its cyclic mechanical behaviour after transient heat treatments

    OpenAIRE

    Bardel, Didier

    2014-01-01

    In order to assemble the pressure vessel of experimental Reactor Jules Horowitz (RJH) of France in the future, the electron beam welding process will be used. Several ferrules in a 6061-T6 age hardening aluminum alloy are used for manufacturing this vessel. The fine precipitation state (T6) is affected significantly by the electron beam welding process. Consequently, this microstructural degradation leads to an evolution of the mechanical behaviour and thus will affect the distribution of res...

  17. Application of artificial neural networks for modelling correlations in age hardenable aluminium alloys

    Directory of Open Access Journals (Sweden)

    F. Musharavati

    2010-07-01

    Full Text Available Purpose: This paper discusses some of the preliminary results of an ongoing research on the applications of artificial neural networks (ANNs in modelling, predicting and simulating correlations between mechanical properties of age hardenable aluminium alloys as a function of alloy composition.Design/methodology/approach: Appropriate combinations of inputs and outputs were selected for neural network modelling. Multilayer feedforward networks were created and trained using datasets from public literature. Influences of alloying elements, alloy composition and processing parameters on mechanical properties of aluminium alloys were predicted and simulated using ANNs models.Two sample t-tests were used to analyze the prediction accuracy of the trained ANNs.Findings: Good performances of the neural network models were achieved. The models were able to predict mechanical properties within acceptable margins of error and were able to provide relevant simulated data for correlating alloy composition and processing parameters with mechanical properties. Therefore, ANNs models are convenient and powerful tools that can provide useful information which can be used to identify desired properties in new aluminium alloys for practical applications in new and/or improved aluminium products.Research limitations/implications: Few public data bases are available for modelling properties. Minor contradictions on the experimental values of properties and alloy compositions were also observed. Future work will include further development of simulated data into property charts.Practical implications: Correlations between mechanical properties and alloy compositions can help in identifying a suitable alloy for a new or improved aluminum product application. In addition, availability of simulated structure-process-property data or charts assists in reducing the time and costs of trial and error experimental approaches by providing near-optimal values that can be used

  18. Age-hardening effect and formation of nanoscale composite precipitates in a NiAlMnCu-containing steel

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojiao [Key Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Sha, Gang, E-mail: gang.sha@njust.edu.cn [School of Materials Science & Engineering, Nanjing University of Science and Technology, Jiangsu 210094 (China); Shen, Qin [Key Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Liu, Wenqing, E-mail: wqliu@staff.shu.edu.cn [Key Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China)

    2015-03-11

    A NiAlMnCu-containing steel during ageing at 500 °C up to 100 h exhibits an interesting age-hardening effect. Careful atom probe tomography investigations confirm that small clusters, enriched with Ni, Al, Mn and Cu, formed in the steel after a short ageing of 0.25 h. Composite precipitates, consisting of a NiAl-rich and a Cu-rich component side by side, formed after 4 h ageing, a phenomenon which corresponded to a peak of 445 VHN in hardness. A decrease in hardness of the steel occurred after ageing for 100 h, due to the coarsening of the composite precipitates. Quantitative chemical composition measurements reveal that early-stage formation of composite precipitates involves the decomposition of metastable solute clusters, and their growth is associated with the further partitioning of solutes from the ferrite matrix into the composite precipitates.

  19. Age-hardening effect and formation of nanoscale composite precipitates in a NiAlMnCu-containing steel

    International Nuclear Information System (INIS)

    A NiAlMnCu-containing steel during ageing at 500 °C up to 100 h exhibits an interesting age-hardening effect. Careful atom probe tomography investigations confirm that small clusters, enriched with Ni, Al, Mn and Cu, formed in the steel after a short ageing of 0.25 h. Composite precipitates, consisting of a NiAl-rich and a Cu-rich component side by side, formed after 4 h ageing, a phenomenon which corresponded to a peak of 445 VHN in hardness. A decrease in hardness of the steel occurred after ageing for 100 h, due to the coarsening of the composite precipitates. Quantitative chemical composition measurements reveal that early-stage formation of composite precipitates involves the decomposition of metastable solute clusters, and their growth is associated with the further partitioning of solutes from the ferrite matrix into the composite precipitates

  20. The effect of interrupted aging on the yield strength and uniform elongation of precipitation-hardened Al alloys

    International Nuclear Information System (INIS)

    The yield strength and elongation are both important properties of engineering alloys. In precipitation-hardenable alloys, these properties are directly related to the interaction between the precipitates and mobile dislocations and an inverse correlation is usually observed. It was recently reported that bimodal microstructures containing both shearable and shear-resistant precipitates, generated by interrupted aging schedules, can simultaneously increase both the yield strength and the uniform elongation in selected Al alloys. This is an effect of considerable technological significance but the physical origin is not understood. An explanation for the interrupted aging effect is offered in this contribution. The mechanical response of a model Al–Cu alloy after interrupted aging has been characterized using uniaxial tensile tests and tension–compression Bauschinger tests. The undeformed and deformed microstructures have been characterized using transmission electron microscopy, scanning transmission electron microscopy and differential scanning calorimetry. It is shown that dissolution of the shearable Guinier–Preston (GP) zones occurs during uniaxial deformation, and that the repartition of solute from the GP zones to the matrix can provide a positive contribution to strain hardening that is quantitatively capable of explaining the observations of enhanced elongation. The result depends on the effect of the repartitioned solute on the plasticity of the Al matrix and, using a series of Al–X (X = Cu, Mg, Si, Zn) binary solid solutions, the effect of solute in solution on the mechanical response is quantified. This information is incorporated into models for the yield strength and strain hardening of precipitate-containing microstructures. It is suggested that simultaneous increases in both strength and elongation due to interrupted aging may be expected in 2xxx series alloys but are less likely to be significant in the 6xxx series alloys and are unlikely in

  1. Age-hardening characteristics of δ-alumina fibre reinforced aluminium-silicon LM-13 alloy metal matrix composites

    OpenAIRE

    Akbulut, H; Durman, M.; F. Yilmaz

    1993-01-01

    Metal Matrix Composites (MMCs) with an aluminium-silicon based LM-13 alloy and short-staple Saffil (δ-alumina) fibres with volume fractions of 0.10, 0.15, 0.20, 0.25 and 0.30 have been produced using a pressure liquid infiltration process. The standard T6 heat treatment procedure was applied to both the unreinforced matrix alloy and the composites, and the effect of the fibres on the age-hardening characteristics of the composites has been investigated by means of hardness measurements.

  2. Effects of substituting ytterbium for scandium on the microstructure and age-hardening behaviour of Al–Sc alloy

    International Nuclear Information System (INIS)

    In order to reduce the cost of Al–Sc alloys and maintain their mechanical properties, the microstructure and mechanical properties of Al–0.24 wt% Sc–0.07 wt% Yb in comparison with Al–0.28 wt% Sc alloys were studied. The aging behaviour, precipitate morphologies, precipitate coarsening and precipitation hardening of both alloys were investigated. The average diameter and the size distribution of nanoscale Al3Sc and Al3(Sc,Yb) precipitates at various aging conditions were measured. Transmission electron microscopy (TEM) and high-resolution TEM were used to deeply understand the precipitate evolution. A maximum hardness around 73 (HV30) was obtained with a precipitate diameter from 4.3 to 5.6 nm for both alloys

  3. Pre-treatment to Improve the Bake-hardening Response in the Naturally Aged Al-Mg-Si Alloy

    Institute of Scientific and Technical Information of China (English)

    Chin-Hui Shen

    2011-01-01

    This paper describes pre-treatment methods to improve the bake-hardening response of naturally aged AA6022 (Al-0.6Mg-1.0Si), which is an alloy used in automotive body panels. These methods are used to accelerate the artificial aging process, which proceeds 30-day period of natural aging. The precipitation behavior of the sheets of this aluminum alloy was analyzed by differential scanning calorimetry (DSC) and electrical conductivity measurements, and subsequently confirmed by microstructure observations by transmission electron microscopy (TEM). Tensile tests and microhardness measurements were performed to determine the mechanical properties of the samples. Under simulated paint-baking conditions (30 min at 170℃), the microhardness and the yield strength (YS) of the pre-strained + pre-aged samples were found to be 113 HV and 225 MPa, respectively. These values are considerably higher than those of pre-aged samples, and they did not decrease significantly during the initial stage of artificial aging.

  4. Improved age-hardening behavior of Mg–Sn–Mn alloy by addition of Ag and Zn

    International Nuclear Information System (INIS)

    Highlights: ► Age-hardening response of Mg–Sn–Mn alloy is enhanced by Ag and Ag + Zn. ► Ag promotes the nucleation and growth of the major Mg2Sn precipitates. ► Zn refines the Mg2Sn, promotes the formation of the blocky Mg54Ag17 phase. ► Ag segregates in the Mg2Sn precipitates. ► A new orientation relationship between Mg54Ag17 with α-Mg is discovered. - Abstract: The effect of 0.5 at% Ag and its combination with 0.4 at% Zn on the precipitation hardening behavior of Mg–1.5Sn–0.5Mn (at%) alloy have been investigated using hardness measurements and transmission electron microscopy (TEM). The results show that sole addition of Ag can remarkably improve the peak hardness from 58HV to 77HV after ageing at 200 °C, which is attributed to the increased number density, the size and so the volume fraction of the Mg2Sn lath precipitates. A combination addition of Ag and Zn further improves the peak-hardness to 83HV and the time to peak hardness has been reduced from 120 h to 100 h. The joint addition of Ag and Zn both increases the number density and refines the Mg2Sn precipitates. Zn also promotes the Mg2Sn precipitates lying on the non-basal plane of matrix, as well as the blocky Mg54Ag17 phase which has an orientation relationship with α-Mg matrix as (0 0 1)ε′//(0 0 0 1)α, [2 0 0]ε′//[ 1 −1 2 0]α, [0 −2 0]ε′//[1 −1 0 0]α. In the peak-aged Ag modified alloys, Ag atoms are segregated in the Mg2Sn precipitates. Nucleation, growth and coarsening of the Mg2Sn precipitates simultaneously occur as the ageing proceeds. The growth of Mg2Sn precipitates exhibits a significant anisotropic behavior. Addition of Ag can promote the precipitation process during the underage period and retarding the growth of Mg2Sn during the overage period, leading to a more thermal stable microstructure of the Ag and Ag + Zn modified alloys, from which only a small hardness decrease after 700 h ageing is detected.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yonghwan [Department of Biomaterials Science, Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Niinomi, Mitsuo, E-mail: niinomi@imr.tohoku.ac.jp [Department of Biomaterials Science, Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Hieda, Junko; Nakai, Masaaki; Cho, Ken [Department of Biomaterials Science, Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Fukui, Hisao [Department of Dental Materials Science, School of Dentistry, Aichi-Gakuin University, Nagoya 464-0045 (Japan)

    2014-03-01

    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{sub x}Zn{sub 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{sub 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.

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

    International Nuclear Information System (INIS)

    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 PdCuxZn1−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 L10-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

  7. Age hardening, fracture behavior and mechanical properties of QE22 Mg alloy

    Directory of Open Access Journals (Sweden)

    F. Khan MD

    2015-09-01

    Full Text Available The microstructure, mechanical properties and fracture behavior of an as-received QE22 alloy have been investigated under different thermal conditions, including solution treated (ST, under aged (UA, peak aged (PA and over aged (OA conditions. A significant increase in hardness of 27%, yield strength of 60% and ultimate tensile strength of 19% was observed in peak aged sample as compared to solution treated sample. The improvements of mechanical strength properties are mainly associated with the metastable λ and β′ precipitates. Grain growth was not observed in the ST samples after subjecting to UA and PA treatments due to the presence of eutectic Mg12Nd particles along the grain boundaries. In over aged sample, significant grain growth occurred because of dissolution of eutectic phase particles. Different natures of crack initiation and propagation were observed under different thermal conditions during tensile testing at room temperature. The mode of failure of solution treated sample is transgranular, cleavage and twin boundary fractures. A mixed mode of transgranular, intergranular, cleavage and twin boundary failure is observed in both peak aged and over aged samples.

  8. Precipitation sequence and its effect on age hardening of alumina-forming austenitic stainless steel

    International Nuclear Information System (INIS)

    The precipitation sequence during ageing of Fe–14Cr–20Ni–0.9Nb–2.5Al based alumina-forming austenitic (AFA) steel was explored through a transmission electron microscopy analysis and a small angle neutron scattering experiment. The samples were aged at 700 °C for up to 504 h. Particles of NbC, M23C6 and Ni3Al-type L12 were observed in the early stage of ageing. Metastable L12 particles were formed both in grain interior and along grain boundary. M23C6 carbides precipitated along grain boundary accompanied with precipitation of L12 particles. After ageing for longer than 48 h, particles of B2-NiAl and Laves-Fe2Nb were newly formed. We suggest the possibility of phase transition from L12 to B2 with increase in ageing time. Finally, this study examined the change of mechanical properties during ageing through a Gleeble hot tension test and a Vickers hardness test, and then the relationship between precipitation behavior and mechanical properties was carefully investigated and discussed in terms of precipitation behavior

  9. Precipitation sequence and its effect on age hardening of alumina-forming austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Joonoh, E-mail: mjo99@kims.re.kr [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, Changwon, Gyeongnam 642-831 (Korea, Republic of); Lee, Tae-Ho [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, Changwon, Gyeongnam 642-831 (Korea, Republic of); Heo, Yoon-Uk [Graduate Institute of Ferrous Technology, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Gyeongbuk 790-784 (Korea, Republic of); Han, Young-Soo [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Kang, Jun-Yun; Ha, Heon-Young [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, Changwon, Gyeongnam 642-831 (Korea, Republic of); Suh, Dong-Woo [Graduate Institute of Ferrous Technology, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Gyeongbuk 790-784 (Korea, Republic of)

    2015-10-01

    The precipitation sequence during ageing of Fe–14Cr–20Ni–0.9Nb–2.5Al based alumina-forming austenitic (AFA) steel was explored through a transmission electron microscopy analysis and a small angle neutron scattering experiment. The samples were aged at 700 °C for up to 504 h. Particles of NbC, M{sub 23}C{sub 6} and Ni{sub 3}Al-type L1{sub 2} were observed in the early stage of ageing. Metastable L1{sub 2} particles were formed both in grain interior and along grain boundary. M{sub 23}C{sub 6} carbides precipitated along grain boundary accompanied with precipitation of L1{sub 2} particles. After ageing for longer than 48 h, particles of B2-NiAl and Laves-Fe{sub 2}Nb were newly formed. We suggest the possibility of phase transition from L1{sub 2} to B2 with increase in ageing time. Finally, this study examined the change of mechanical properties during ageing through a Gleeble hot tension test and a Vickers hardness test, and then the relationship between precipitation behavior and mechanical properties was carefully investigated and discussed in terms of precipitation behavior.

  10. Effects of Cu and Ag additions on age-hardening behavior during multi-step aging in Al--Mg--Si alloys

    International Nuclear Information System (INIS)

    Low Cu and Ag additions (≤0.10 at%) were found to strongly affect the age-hardening behavior in Al--Mg--Si alloys with Mg+Si>1.5 at%. The hardness increased during aging at 170 °C and the formation of β″ precipitates was kinetically accelerated. The activation energy of the formation of the β″ phase was calculated to 127, 105, 108 and 99 KJmol−1 in the base, Cu-added, Ag-added and Cu--Ag-added alloys, respectively using the Kissinger method. The negative effect of two-step aging caused by the formation of Cluster (1) during natural aging was not overcome by the addition of microalloying elements. However, it was suppressed by the formation of Cluster (2) through a pre-aging at 100 °C. Quantitative analysis of the precipitate microstructure was performed using a transmission electron microscope equipped with a parallel electron energy loss spectrometer for the determination of specimen thickness. The formation of Cluster (2) was found to increase the number density of β″ precipitates, whereas the formation of Cluster (1) decreased the number density and increased the needle length. The effects of low Cu and Ag additions in combination with multi-step aging are discussed based on microstructure observations and hardness and resistivity measurements.

  11. 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.

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

    International Nuclear Information System (INIS)

    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

  13. Characterization and modeling of the influence of artificial aging on the microstructural evolution of age-hardenable AlSi{sub 10}Mg(Cu) aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Larráyoz Izcara, X., E-mail: xabier.larrayoz.izcara@volkswagen.de [Group Research, Volkswagen AG, Berliner Ring 2, 38436 Wolfsburg (Germany); Guirao Blank, A., E-mail: alejandro.javier.guirao.blank@volkswagen.de [Group Research, Volkswagen AG, Berliner Ring 2, 38436 Wolfsburg (Germany); Pyczak, F., E-mail: florian.pyczak@hzg.de [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max Planck Str. 1, 21502 Geesthacht (Germany); Staron, P., E-mail: peter.staron@hzg.de [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max Planck Str. 1, 21502 Geesthacht (Germany); Schumann, S., E-mail: soenke.schumann@volkswagen.de [Group Research, Volkswagen AG, Berliner Ring 2, 38436 Wolfsburg (Germany); Huber, N., E-mail: norbert.huber@hzg.de [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max Planck Str. 1, 21502 Geesthacht (Germany)

    2014-07-29

    A comprehensive analysis of the effect of the artificial aging on the Mg{sub 2}Si precipitation distribution of the age-hardenable AlSi{sub 10}Mg(Cu) aluminum alloy from T6 to T7 condition is presented considering the influence of temperature and time of the aging conditions. A complete quantitative characterization of the strengthening distributions covering a broad range of aging conditions was obtained using the small angle neutron scattering (SANS) technique, complemented with high-resolution transmission electron microscopy (HTEM). This information was successfully used to fit Robson's precipitation model for the prediction of the precipitation distribution as a function of time and temperature. Based on the measured precipitation behavior a sigmoidal function of the interfacial energy was added to Robson's model. As a result a unique set of modeling parameters was obtained for the whole precipitation process and range of temperatures considered. Robson's model is shown to be a powerful tool for predicting the evolution of these nanometer-scale particles in industrial and complex aging processes, which are critical for designing new components based on the material requirements.

  14. Characterization and modeling of the influence of artificial aging on the microstructural evolution of age-hardenable AlSi10Mg(Cu) aluminum alloys

    International Nuclear Information System (INIS)

    A comprehensive analysis of the effect of the artificial aging on the Mg2Si precipitation distribution of the age-hardenable AlSi10Mg(Cu) aluminum alloy from T6 to T7 condition is presented considering the influence of temperature and time of the aging conditions. A complete quantitative characterization of the strengthening distributions covering a broad range of aging conditions was obtained using the small angle neutron scattering (SANS) technique, complemented with high-resolution transmission electron microscopy (HTEM). This information was successfully used to fit Robson's precipitation model for the prediction of the precipitation distribution as a function of time and temperature. Based on the measured precipitation behavior a sigmoidal function of the interfacial energy was added to Robson's model. As a result a unique set of modeling parameters was obtained for the whole precipitation process and range of temperatures considered. Robson's model is shown to be a powerful tool for predicting the evolution of these nanometer-scale particles in industrial and complex aging processes, which are critical for designing new components based on the material requirements

  15. Influence of a treatment of age hardening on the mechanical properties of Inconel 625 in the presence of hydrogen gas

    International Nuclear Information System (INIS)

    Inconel 625 presents good mechanical properties and has excellent corrosion behaviour with temperatures being able to reach 1000oC. These mechanical properties are obtained by a heat treatment of structural hardening. Utilization of this super alloy for hydrogen gas must be preceded by a study of its embrittlement. The method of rupture of the discs, under hydrogen pressure or helium pressure has to undertake this study at ambient temperature. We show that for this material, obtaining the mechanical characteristics, by the heat treatment of hyper-hardening and by application of structural hardening, the ambient temperature of a catastrophic embrittlement vis-a-vis hydrogen gas

  16. Age hardening in rapidly solidified and hot isostatically pressed beryllium-aluminum-silver alloys

    International Nuclear Information System (INIS)

    Three different alloys of beryllium, aluminum and silver were processed to powder by centrifugal atomization in a helium atmosphere. Alloy compositions were, by weight, 50% Be, 47.5% Al, 2.5% Ag, 50% Be, 47% Al, 3% Ag, and 50% Be, 46% Al, 4% Ag. Due to the low solubility of both aluminum and silver in beryllium, the silver was concentrated in the aluminum phase, which appeared to separate from the beryllium in the liquid phase. A fine, continuous composite beryllium-aluminum microstructure was formed, which did not significantly change after hot isostatically pressing at 550 C for one hour at 30,000 psi argon pressure. Samples of HIP material were solution treated at 550 C for one hour, followed by a water quench. Aging temperatures were 150, 175, 200 and 225 C for times ranging from one half hour to 65 hours. Hardness measurements were made using a diamond pyramid indenter with a load of 1 kg. Results indicate that peak hardness was reached in 36--40 hours at 175 C and 12--16 hours at 200 C aging temperature, relatively independent of alloy composition

  17. Friction Stir Welding of Age-Hardenable Aluminum Alloys: A Parametric Approach Using RSM Based GRA Coupled With PCA

    Science.gov (United States)

    Vijayan, D.; Rao, V. S.

    2014-04-01

    Age-hardenable aluminum alloys, primarily used in the aerospace, automobile and marine industries (2×××, 6××× and 7×××), can be welded using solid-state welding techniques. Friction stir welding is an emerging solid-state welding technique used to join both similar and dissimilar materials. The strength of a friction stir welded joint depends on the joining process parameters. Therefore, a combination of the statistical techniques of a response surface methodology based on a grey relational analysis coupled to a principal component analysis was proposed to select the process parameters suitable for joining AA 2024 and AA 6061 aluminum alloys via friction stir welding. The significant process parameters, such as rotational speed, welding speed, axial load and pin shapes (PS) were considered during the statistical experiment. The results indicate that the square PS plays a vital role and yields an ultimate tensile strength of 141 MPa for an elongation of 12 % versus cylinder and taper pin profiles. The root cause for joint strength loss and fracture mode was analyzed using scanning electron microscopy. Severe material flow during macro defects, such as pin holes and porosity, degrades the joint strength by approximately 44 % for AA 2024 and 51 % for AA 6061 fabricated FS-welded aluminum alloys relative to the base material. The results of this approach are useful for accurately controlling the response and optimize the process parameters.

  18. Influence of secondary ageing temperature on hardening and residual elastic stresses in AlMgSi and AlMgSiCu alloys

    International Nuclear Information System (INIS)

    The investigations were conducted on samples of AlMgSi and AlMgSiCu alloys quenched, aged and cold worked with 20, 40, 60 and 85 % reduction in area. Secondary ageing was carried out at 200 and 250 deg C. Residual stresses wee determined by X-ray diffraction method. It was shown that cold deformation effect on hardness and residual stresses is dependent on alloy composition. The hardening due to secondary ageing is more pronounced for AlMgSi alloy at 200 deg C and for AlMgSiCu alloy at 250 deg C. Positive residual stresses increase with secondary ageing temperature

  19. Initial precipitation and hardening mechanism during non-isothermal aging in an Al–Mg–Si–Cu 6005A alloy

    International Nuclear Information System (INIS)

    The characterization of precipitation and hardening mechanism during non-isothermal aging had been investigated using high resolution transmission electron microscopy for an Al–Mg–Si–Cu 6005A alloy. It was proposed that the needle-shaped β″ precipitates with a three-dimension coherency strain-field and an increased number density in the Al matrix provided the maximum strengthening effect for the Al–Mg–Si–Cu 6005A alloy. Simultaneously, it was also found that the formation and evolution of clusters in the early precipitation were associated with the vacancy binding energy, during which Si atoms played an important role in controlling the numbers density of Mg/Si co-clusters, and the excess Si atoms provided the increased number of nucleation sites for the subsequent precipitates to strengthen and improve the precipitation rate. Finally, based on the experimental observation and theoretical analysis, the precipitation sequence during the early precipitation in the Al–Mg–Si–Cu 6005A alloy was proposed as: supersaturated solid solution → Si-vacancy pairs, Mg-vacancy pairs and Mg clusters → Si clusters, and dissolution of Mg clusters → Mg atoms diffusion into the existing Si clusters → Mg/Si co-clusters → GP zone. - Highlights: • β″ precipitates provide the maximum strengthening effect for the 6005A alloy. • Si atoms play an important role in controlling the numbers of Mg/Si co-clusters. • The early aging sequence is deduced based on the solute-vacancy binding energy

  20. Effect of rolling speed on microstructure and age-hardening behaviour of Al-Mg-Si alloy produced by twin roll casting process

    International Nuclear Information System (INIS)

    Highlights: → Effect of rolling speed on as-cast and solutionized Al-Mg-Si alloys produced by TRC process. → Effect of rolling speed on microstructure of Al-Mg-Si alloys. → Correlation of rolling speed with age-hardening properties. -- Abstract: In the present investigation the microstructure and age-hardening behaviour of Al-Mg-Si alloy prepared by twin roll casting (TRC), varying rolling speed (i.e., 3, 4, and 5 rpm), were studied. The as-cast samples were subjected to optical microscopy (OM) to understand the effect of rolling speed on the alloy microstructure. Significant difference in grain size and shape was observed for all the alloys in as-cast condition. The as-cast samples were solutionized at 540 oC for 2 h followed by isothermal heating at 180 oC for different time intervals. Thereafter, the as-cast and solutionized samples were subjected to scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). Segregation of solute atoms at grain boundaries were observed for both as-cast as well as solutionized samples. Age-hardening results show that time to attain peak hardness decreases for the alloy produced by higher rolling speed.

  1. Influence of trace Ti on the microstructure, age hardening behavior and mechanical properties of an Al–Zn–Mg–Cu–Zr alloy

    International Nuclear Information System (INIS)

    The influence of trace Ti on the microstructure and precipitation process of a Zr-containing Al–Zn–Mg–Cu alloy was investigated. The introduction of Ti results in not only the refinement of α-Al grains, but also an early-stage age hardening behavior during aging treatment process. High-resolution transmission electron microscopy results indicate that Ti can decrease the coarsening tendency of L12 precipitates and accelerate the growth rate of GP II as well as its evolution to η' phase. The mechanism was discussed. Accordingly, the tensile strength, elongation and wear property were obviously improved

  2. Electron microscopy studies of the age-hardening behaviors in 6005A alloy and microstructural characterizations of precipitates

    International Nuclear Information System (INIS)

    Highlights: ► TEM and HREM are used to elucidate an anti overaged softening behavior in Al–0.65Mg–0.73Si–0.13Cu alloy. ► The β″ precipitate not only has a 2-dimensions coherency strain-field, but also has the smaller size and a high density. ► The strengthening of three main precipitates on alloy can be summarized as: β″ > Q′ > β′. ► The β″, β′ and Q′ precipitates have 12 orientation variants with Al matrix, respectively. ► Moiré fringes are used to verify the lattice parameters and orientation variants of precipitates. - Abstract: High-resolution electron microscopy was used to research the age-hardening behaviors in 6005A alloy and the microstructural characterizations of precipitates. It was found that β″, β′ and Q′ precipitates had 12 orientation variants, respectively, the smaller size and a high-density β′′ precipitates existed in alloy for a long time, which played a very important role in controlling an anti-overaged softening behavior in 6005A alloy. Further, by the crystallographic interface and morphology analysis, a main reason was that a 2-dimensions coherency strain-field not only had the high-density β′′ precipitates become the biggest obstacle of dislocations movement, but also made them transform into β′ and Q′ precipitates with more difficulty. Moreover, it was also found that β′ and Q′ precipitates had weaker relatively strain-fields, the larger size and a lower density, which were largely associated with the reduction in hardness that occurred upon overaging. Further, the strengthening of precipitates on alloys could be summarized as: β″ > Q′ > β′. Based on the structural information, the quantitative Moiré fringes analytical technique was also used to verify the lattice parameters and orientation of precipitates.

  3. Atom probe analysis on interaction between Cr and N in bake-hardening steels with anti-aging properties at RT

    International Nuclear Information System (INIS)

    One-dimensional atom probe (1DAP) analysis was performed on chromium and nitrogen added bake hardening steel sheets that have both high bake-hardenability and anti-aging properties at room temperature (RT). The atomic data of more than 2 million atoms were collected for sample steels with and without low-temperature aging after recrystallization annealing and quenching. The correlation in atomic position between chromium and nitrogen atoms in a solid solution was investigated by a statistical analysis using the binomial distribution function. In the samples with low-temperature aging, the probability that a chromium atom was observed near a nitrogen atom was significantly higher than that estimated from the null hypothesis that there was no attractive atomic interaction. This suggests that there is an attractive interaction between a nitrogen atom and a chromium atom in bcc iron, which led to the anti-aging properties at RT. In contrast, such correlation was not observed definitely in the samples without low-temperature aging, which implied that the atomic pair formation is a thermal activation process

  4. Study on hardening mechanisms in aluminium alloys

    Directory of Open Access Journals (Sweden)

    P. K. Mandal

    2016-01-01

    Full Text Available The Al-Zn-Mg alloys are most commonly used age-hardenable aluminium alloys. The hardening mechanism is further enhanced in addition of Sc. Sc additions to aluminium alloys are more promising. Due to the heterogeneous distribution of nano-sized Al3Sc precipitates hardening effect can be accelerated. Mainly, highlight on hardening mechanism in Al-Zn-Mg alloys with Sc effect is to study. In addition, several characterisations have been done to age-hardening measurements at elevated temperatures from 120oC to 180 oC. The ageing kinetics has also been calculated from Arrhenius equation. Furthermore, friction stir processing (FSP can be introduced to surface modification process and hardened the cast aluminium alloys. In this study, hardening mechanism can be evaluated by Vicker’s hardness measurement and mechanical testing is present task.

  5. Influence of Thermal Aging on the Microstructure and Mechanical Behavior of Dual-Phase, Precipitation-Hardened, Powder Metallurgy Stainless Steels

    Science.gov (United States)

    Stewart, J. L.; Williams, J. J.; Chawla, N.

    2012-01-01

    The effects of thermal aging on the microstructure and mechanical behavior of dual-phase, precipitation-hardened, powder metallurgy (PM) stainless steels of varying ferrite-martensite content were examined. Quantitative analyses of the inherent porosity and phase fractions were conducted on the steels, and no significant differences were noted with respect to aging temperature. Tensile strength, yield strength, and elongation to fracture all increased with increasing aging temperature reaching maxima at 811 K (538 °C) in most cases. Increased strength and decreased ductility were observed in steels of higher martensite content. Nanoindentation of the individual microconstituents was employed to obtain a fundamental understanding of the strengthening contributions. Both the ferrite and martensite nanohardness values increased with aging temperature and exhibited similar maxima to the bulk tensile properties.

  6. Comparative study of structure formation and mechanical behavior of age-hardened Ti–Nb–Zr and Ti–Nb–Ta shape memory alloys

    International Nuclear Information System (INIS)

    This work sets out to study the peculiar effects of aging treatment on the structure and mechanical behavior of cold-rolled and annealed biomedical Ti–21.8Nb–6.0Zr (TNZ) and Ti–19.7Nb–5.8Ta (TNT) (at.%) shape memory alloys by means of transmission electron microscopy, X-ray diffractometry, functional fatigue and thermomechanical testing techniques. Dissimilar effects of aging treatment on the mechanical behavior of Zr- and Ta-doped alloys are explained by the differences in the ω-phase formation rate, precipitate size, fraction and distribution, and by their effect on the alloys' critical stresses and transformation temperatures. Even short-time aging of the TNZ alloy leads to its drastic embrittlement caused by “overaging”. On the contrary, during aging of the TNT alloy, formation of finely dispersed ω-phase precipitates is gradual and controllable, which makes it possible to finely adjust the TNT alloy functional properties using precipitation hardening mechanisms. To create in this alloy nanosubgrained dislocation substructure containing highly-dispersed coherent nanosized ω-phase precipitates, the following optimum thermomechanical treatment is recommended: cold rolling (true strain 0.37), followed by post-deformation annealing (600 °C, 15–30 min) and age-hardening (300 °C, 30 min) thermal treatments. It is shown that in TNT alloy, pre-transition diffraction effects (diffuse reflections) can “mask” the β-phase substructure and morphology of secondary phases. - Highlights: • TNZ alloy is characterized by much higher ω-phase precipitation rate than TNT alloy. • Difference in precipitation rates is linked to the difference in Zr and Ta diffusion mobility. • Aging of nanosubgrained TNZ alloy worsens its properties irrespective of the aging time. • Aging time of nanosubgrained TNT alloy can be optimized to improve its properties

  7. Comparative study of structure formation and mechanical behavior of age-hardened Ti–Nb–Zr and Ti–Nb–Ta shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Inaekyan, K. [Ecole de Technologie Superieure, 1100, Notre-Dame Str. West, Montreal Quebec H3C 1K3 (Canada); Brailovski, V., E-mail: vladimir.brailovski@etsmtl.ca [Ecole de Technologie Superieure, 1100, Notre-Dame Str. West, Montreal Quebec H3C 1K3 (Canada); Prokoshkin, S. [National University of Science and Technology “MISIS”, Leninskiy prosp. 4, Moscow 119049 (Russian Federation); Pushin, V. [Institute of Metal Physics, Ural Branch of Russian Academy of Sciences, 18, S. Kovalevskoy Str., Ekaterinburg 620199 (Russian Federation); Dubinskiy, S.; Sheremetyev, V. [Ecole de Technologie Superieure, 1100, Notre-Dame Str. West, Montreal Quebec H3C 1K3 (Canada); National University of Science and Technology “MISIS”, Leninskiy prosp. 4, Moscow 119049 (Russian Federation)

    2015-05-15

    This work sets out to study the peculiar effects of aging treatment on the structure and mechanical behavior of cold-rolled and annealed biomedical Ti–21.8Nb–6.0Zr (TNZ) and Ti–19.7Nb–5.8Ta (TNT) (at.%) shape memory alloys by means of transmission electron microscopy, X-ray diffractometry, functional fatigue and thermomechanical testing techniques. Dissimilar effects of aging treatment on the mechanical behavior of Zr- and Ta-doped alloys are explained by the differences in the ω-phase formation rate, precipitate size, fraction and distribution, and by their effect on the alloys' critical stresses and transformation temperatures. Even short-time aging of the TNZ alloy leads to its drastic embrittlement caused by “overaging”. On the contrary, during aging of the TNT alloy, formation of finely dispersed ω-phase precipitates is gradual and controllable, which makes it possible to finely adjust the TNT alloy functional properties using precipitation hardening mechanisms. To create in this alloy nanosubgrained dislocation substructure containing highly-dispersed coherent nanosized ω-phase precipitates, the following optimum thermomechanical treatment is recommended: cold rolling (true strain 0.37), followed by post-deformation annealing (600 °C, 15–30 min) and age-hardening (300 °C, 30 min) thermal treatments. It is shown that in TNT alloy, pre-transition diffraction effects (diffuse reflections) can “mask” the β-phase substructure and morphology of secondary phases. - Highlights: • TNZ alloy is characterized by much higher ω-phase precipitation rate than TNT alloy. • Difference in precipitation rates is linked to the difference in Zr and Ta diffusion mobility. • Aging of nanosubgrained TNZ alloy worsens its properties irrespective of the aging time. • Aging time of nanosubgrained TNT alloy can be optimized to improve its properties.

  8. An Extended Age-Hardening Model for Al-Mg-Si Alloys Incorporating the Room-Temperature Storage and Cold Deformation Process Stages

    Science.gov (United States)

    Myhr, Ole Runar; Grong, Øystein; Schäfer, Carmen

    2015-12-01

    In this article, a new age-hardening model for Al-Mg-Si alloys is presented (named NaMo-Version 2), which takes into account the combined effect of cold deformation and prolonged room-temperature storage on the subsequent response to artificial aging. As a starting point, the original physical framework of NaMo-Version 1 is revived and used as a basis for the extension. This is permissible, since a more in-depth analysis of the underlying particle-dislocation interactions confirms previous expectations that the simplifying assumption of spherical precipitates is not crucial for the final outcome of the calculations, provided that the yield strength model is calibrated against experimental data. At the same time, the implementation of the Kampmann-Wagner formalism means that the different microstructure models can be linked together in a manner that enforces solute partitioning and competition between the different hardening phases which form during aging ( e.g., clusters, β″ and β'). In a calibrated form, NaMo-Version 2 exhibits a high degree of predictive power, as documented by comparison with experiments, using both dedicated nanostructure and yield strength data as a basis for the validation. Hence, the model is deemed to be well-suited for simulation of thermomechanical processing of Al-Mg-Si alloys involving cold-working operations like sheet forming and stretch bending in combination with heat treatment and welding.

  9. Effects of in situ formation of TiB{sub 2} particles on age hardening behavior of Cu–1 wt% Ti–1 wt% TiB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sobhani, Mohsen, E-mail: m_sobhani@iust.ac.ir [Center of Excellence for High Strength Alloys Technology (CEHSAT), School of Metallurgy and Materials Engineering, Iran University of Science and Technology, IUST, Tehran 16845-118 (Iran, Islamic Republic of); Mirhabibi, Alireza [Center of Excellence for Ceramic Materials in Energy and Environmental Applications(CECMEEA), IUST, Tehran 16845-118 (Iran, Islamic Republic of); Arabi, Hossein [Center of Excellence for High Strength Alloys Technology (CEHSAT), School of Metallurgy and Materials Engineering, Iran University of Science and Technology, IUST, Tehran 16845-118 (Iran, Islamic Republic of); Brydson, R.M.D. [Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2013-08-10

    Age hardenable Cu–1 wt% Ti–1 wt% TiB{sub 2} composite was produced by adding boron powder to Cu–Ti melt. TiB{sub 2} nano-particles were formed via in situ reaction between titanium and boron in the melt. This composite was aged in a temperature range of 300–550 °C for a period of 1–25 h. Then, the age hardening behavior of the composite was compared with that of the binary Cu–2 wt% Ti alloy. The microstructure of the composite was examined with a high-resolution transmission electron microscope (HRTEM). The results of this study showed that TiB{sub 2} particles can act as a heterogeneous nucleation site for β′(Cu{sub 4}Ti) precipitates. Substantial increase in tensile and yield stress of composite (i.e. 63% and 186% respectively) occurred relative to the solution state, after ageing at 450 °C for 10 h. The maximum strengthening of the composite was associated with precipitation of metastable Cu{sub 4}Ti near the ultra hard TiB{sub 2} particles within the matrix. However, the results of this research show that the mechanical properties of aged composites are in good agreement with those of binary Cu–2 wt% Ti alloy; the maximum values of the hardness and electrical conductivity of the composite (i.e. 258 HV, 28% IACS) and the binary Cu–2 wt% Ti alloy (i.e. 264 HV, 17% IACS) were obtained when solution treated samples were aged at 450 °C for 10 h and 15 h, respectively.

  10. Precipitation hardening in Pb-0.08wt.%Ca-x%Sn alloys--the role of the pre-ageing

    International Nuclear Information System (INIS)

    The precipitation hardening mechanism in both supersaturated and pre-aged Pb-0.08%Ca-x%Sn alloys was investigated by means of hardness and calorimetric measurements (differential scanning calorimetry, DSC) and transmission electron microscopy observations. DSC studies have shown that a pre-ageing treatment of the ternary alloys at 363 K has a favourable effect by reducing the driving force of the overaging process. Furthermore, this preliminary treatment seems to give a finer and denser particle distribution than for only quenched alloys. This latter effect could explain the higher hardness of the pre-aged alloys. For the tin-rich alloy (∼2.0 wt.%), the pre-ageing treatment considerably reduces the micro-segregation of Sn at the grain (sub-)boundary. This phenomenon is accompanied by an increase of the precipitate tin content and also by the appearance of a lattice parameter mismatch of 2.9% between the L12 precipitate and the lead matrix. From all of these experimental results, it appears that the processes leading to the reduction in interfacial energy are not the rate determining step for the overageing

  11. 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.

  12. Modelling of Dynamic Strain Aging with a Dislocation-Based Isotropic Hardening Model and Investigation of Orthogonal Loading

    NARCIS (Netherlands)

    Berisha, B.; Hora, P.; Tong, L.; Wahlen, A.; Boogaard, van den A.H.

    2008-01-01

    Based on experimental results, a dislocation material model describing the dynamic strain aging effect at different temperatures is presented. One and two stage loading tests were performed in order to investigate the influence of the loading direction as well as the temperature influence due to the

  13. Precipitation Hardening and Statistical Modeling of the Aging Parameters and Alloy Compositions in Al-Cu-Mg-Ag Alloys

    Science.gov (United States)

    Al-Obaisi, A. M.; El-Danaf, E. A.; Ragab, A. E.; Soliman, M. S.

    2016-06-01

    The addition of Ag to Al-Cu-Mg systems has been proposed to replace the existing high-strength 2xxx and 7xxx Al alloys. The aged Al-Cu-Mg-Ag alloys exhibited promising properties, due to special type of precipitates named Ω, which cooperate with other precipitates to enhance the mechanical properties significantly. In the present investigation, the effect of changing percentages of alloying elements, aging time, and aging temperature on the hardness values was studied based on a factorial design. According to this design of experiments (DOE)—23 factorial design, eight alloys were cast and hot rolled, where (Cu, Mg, and Ag) were added to aluminum with two different levels for each alloying element. These alloys were aged at different temperatures (160, 190, and 220 °C) over a wide range of time intervals from 10 min. to 64 h. The resulting hardness data were used as an input for Minitab software to model and relate the process variables with hardness through a regression analysis. Modifying the alloying elements' weight percentages to the high level enhanced the hardness of the alloy with about 40% as compared to the alloy containing the low level of all alloying elements. Through analysis of variance (ANOVA), it was figured out that altering the fraction of Cu had the greatest effect on the hardness values with a contribution of about 49%. Also, second-level interaction terms had about 21% of impact on the hardness values. Aging time, quadratic terms, and third-level interaction terms had almost the same level of influence on hardness values (about 10% contribution). Furthermore, the results have shown that small addition of Mg and Ag was enough to improve the mechanical properties of the alloy significantly. The statistical model formulated interpreted about 80% of the variation in hardness values.

  14. Reverse α′ → γ transformation mechanisms of martensitic Fe–Mn and age-hardenable Fe–Mn–Pd alloys upon fast and slow continuous heating

    International Nuclear Information System (INIS)

    The mechanisms governing the reverse martensite (α′) to austenite (γ) transformation (α′ → γ) and the effect of prior precipitation on the austenite reversion are investigated for martensitic Fe–Mn alloys containing 5 and 10 wt.% Mn and their age-hardenable variants with the addition of 1 wt.% Pd, respectively. Dilatometric experiments employing heating rates between 0.5 and 200 K min−1, atom-probe tomography measurements on continuously heated specimens and thermo-kinetic simulations were performed. On fast heating (200 K min−1), the α′ → γ transformation appeared in a single stage and can be regarded as a partitionless and interface-controlled reaction. In comparison to the binary alloys, the transformation temperatures of the Pd-containing steels are considerably increased, due to precipitates which act as obstacles to migrating austenite/martensite interfaces. For low heating rates of 0.5 and 2 K min−1, splitting of the α′ → γ transformation into two consecutive stages is observed for both the binary and the ternary alloys. With the assistance of thermo-kinetic simulations, a consistent description of this phenomenon is obtained. The first transformation stage is associated with the decomposition of the martensite matrix into Mn-rich and Mn-deficient regions, and the austenite formation is dominated by long-range diffusion. In the second stage, the austenite reversion mechanism changes and the Mn-depleted regions transform in a predominantly interface-controlled mode. This is corroborated by the results for the ternary alloys. The precipitates mainly impede the austenite formation in the second stage, which occurs over a considerably wider temperature range compared to the binary alloys

  15. Effect of reinforcing particle type on morphology and age-hardening behavior of Al–4.5 wt.% Cu based nanocomposites synthesized through mechanical milling

    International Nuclear Information System (INIS)

    The effects of reinforcing particle type (SiC and TiC) on morphology and precipitation hardening behavior of Al–4.5%Cu based nanocomposites synthesized via mechanical milling were investigated in the current work. In order to study the microstructure and morphology of mechanically milled powder, X-ray diffraction technique, scanning electron microscopy and high resolution transmission electron microscopy were utilized. Results revealed that at the early stages of mechanical milling, when reinforcing particles are polycrystal, the alloying process is enhanced more in the case of using the TiC particles as reinforcement. But, at the final stages of mechanical milling, when reinforcing particles are single crystal, the alloying process is enhanced more in the case of using the SiC ones. Transmission electron microscopy results demonstrated that Al–4.5 wt.%Cu based nanocomposite powders were synthesized and confirmed that the mutual diffusion of aluminum and copper occurs through the interfacial plane of (200). The hardness results showed that not only does introducing 4 vol.% of reinforcing particles (SiC or TiC) considerably decrease the porosity of the bulk composite samples, but also it approximately doubles the hardness of Al–4.5 wt.%Cu alloy (53.4 HB). Finally, apart from TEM and scanning electron microscopy observation which are localized, a decline in hardness in the TiC and SiC contained samples, respectively, after 1.5 and 2 h aging time at 473 K proves the fact that the size of SiC particles is smaller than the size of the TiC ones. - Highlights: ► HRTEM results show mutual diffusion of Al and Cu occurs through the (200) planes. ► TiC particles enhance alloying process more than the SiC ones at the early stages of MM. ► SiC particles enhance alloying process more than the TiC ones at the final stages of MM

  16. Key role of work hardening in superconductivity/superfluidity, heat conductivity and ultimate strain increase, evolution, cancer, aging and other phase transitions

    CERN Document Server

    Kisel, V P

    2009-01-01

    The shear/laminar flow of liquids/gas/plasma/biological cells (BC), etc. is equivalent to dislocation-like shear of solids. The turbulent flow is the next stage of deformation/ multiplication of dislocation-like defects and their ordering in sub-grains and grain-boundaries, then grains slip-rotation in the direction approximately perpendicular to the shear flow. It is shown that phase transitions are governed by unified deformation hardening/softening under hydrostatic pressure, particle irradiation and impurity (isotope) chemical pressure, hard confining conditions and cooling, etc. thus changing electric, magnetic, ferroelectric, thermal, optical properties.1-2 Dislocation-like work hardening, DWH, is determined by non-monotonous properties of dislocation double edge-cross-jog slip, and ultrastrong DWH gives the lowest drag for any dislocation-like plasticity at phase transitions. This provides the same micromechanisms of the ultimate stage of conventional deformation (superfluidity) of ordinary liquids, i....

  17. Laser Hardening of Metals

    Institute of Scientific and Technical Information of China (English)

    Institute for Laser Physics; V.A.Serebryakov; K.V.Gratzianov; A.S.Eremenko; A.A.Timopheev; SPBSUITMO; M.V.Volkov

    2006-01-01

    Results of experiments on laser hardening of various materials with intensity 109~1010W/cm2 are represented. Nd:glass laser with energy up to 45J with a pulse duration ~30ns was used as a source of ra diation. Comparative researches of the laser peening for the various target areas are fulfilled. Results of laser hardening were determined by the microstructure analysis. The new approach to creation of the industrial laser for peening is discussed.

  18. Analysis of the unstressed lattice spacing, d0, for the determination of the residual stress in a friction stir welded plate of an age-hardenable aluminum alloy – Use of equilibrium conditions and a genetic algorithm

    International Nuclear Information System (INIS)

    Procedures based on equilibrium conditions (stress and bending moment) have been used to obtain an unstressed lattice spacing, d0, as a crucial requirement for calculating the residual stress (RS) profile across a joint conducted on a 10 mm thick plate of age-hardenable AA2024 alloy by friction stir welding (FSW). Two procedures have been used that take advantage of neutron diffraction measurements. First, equilibrium conditions were imposed on sections parallel to the weld so that a constant d0 value corresponding to the base material region could be calculated analytically. Second, balance conditions were imposed on a section transverse to the weld. Then, using the data and a genetic algorithm, suitable d0 values for the different regions of the weld have been found. For several reasons, the comb method has proved to be inappropriate for RS determination in the case of age-hardenable alloys. However, the equilibrium conditions, together with the genetic algorithm, has been shown to be very suitable for determining RS profiles in FSW joints of these alloys, where inherent microstructural variations of d0 across the weld are expected

  19. 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

  20. Electronic system hardening methodology

    International Nuclear Information System (INIS)

    The notion of hardened systems can be found in several applications (nuclear power plants, alarm systems, research installations..). Their development correspond to the functional necessity to take into account a specific radiative environment. The starting point of each hardening study is the definition of the radiative environmental constraints representative of the application. In addition to these external constraints, the specific functional characteristics of each system are considered: control or interface systems in nuclear industry, in-board control systems, remote handling systems, etc. This paper summarizes the methodology followed according to the experience gained in previous studies and anticipating the future needs. (J.S.). 6 refs., 5 figs

  1. 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...

  2. Effect of mushy state rolling on age-hardening and tensile behavior of Al-4.5Cu alloy and in situ Al-4.5Cu-5TiB2 composite

    International Nuclear Information System (INIS)

    Research highlights: → Mushy state rolling of composites reduces peak-aging times to ∼7.5-10% of that of as-cast alloy. → Uniform Cu atom distribution achieved in matrices by mushy state rolling enhances aging kinetics. → Uniform precipitate distribution obtained by mushy state rolling leads to higher microhardness. → Peak-age tensile strength and strain hardening rates are found to increase on mushy state rolling. - Abstract: The effect of mushy state rolling on aging kinetics of stir-cast Al-4.5Cu alloy and in situ Al-4.5Cu-5TiB2 composite and their tensile behavior in solution-treated (495 deg. C) or differently aged (170 deg. C) conditions, has been investigated. As-cast or pre-hot rolled alloy and composite samples were subjected to single or multiple mushy state roll passes to 5% thickness reduction at temperatures for 20% liquid content. Peak-aging times of mushy state rolled composite matrices have been found as ∼7.5-10% of that of as-cast alloy. Such enhancement in aging kinetics is attributed to homogeneity in Cu atom distribution as well as increase in matrix dislocation density due to thermal expansion coefficient mismatch between Al and TiB2, matrix grain refinement and particle redistribution, achieved by mushy state rolling. Uniform precipitate distribution in mushy state rolled composite matrices leads to greater peak-age microhardness with higher yield and ultimate tensile strengths than those in as-cast alloy and composite.

  3. 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.

  4. 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.

  5. RHOBOT: Radiation hardened robotics

    International Nuclear Information System (INIS)

    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

  6. Nuclear effects hardened shelters

    International Nuclear Information System (INIS)

    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

  7. 超低碳铜时效强化钢的热稳定性%Thermal stability of ultra-low-carbon copper-bearing age-hardening steel

    Institute of Scientific and Technical Information of China (English)

    刘翊之; 杨才福; 柴锋; 张永权; 苏航

    2013-01-01

    研究了400℃至800℃再加热处理后超低碳铜时效强化钢组织和性能的变化.利用光学显微镜、扫描电镜、透射电镜观察和X射线衍射分析了不同温度再加热处理后钢显微组织和ε-Cu沉淀的特征.结果表明,再加热温度不高于650℃的条件下,钢的强度和韧性未明显下降,即具有优良的热稳定性;再加热温度高于650℃则钢的屈服强度明显降低,这是由于基体组织发生明显的回复以及ε-Cu沉淀粗化;再加热温度高于700℃钢的韧性明显降低,这是大量高硬度M/A岛组织出现所造成.分析表明基体组织的回复,ε-Cu沉淀的数量和尺寸及M/A岛组织是影响超低碳铜时效强化钢热稳定性的主要因素.%Microstructure and mechamical properties of a ultra-low-carbon copper-bearing age-hardening steel under reheated treatment between 400 ℃ to 800 ℃ were investigated.OM,SEM,TEM and XRD were used to characterize microstructure and ε-Cu precipitates of the tested steel under reheat treatment at different temperatures.Strength and toughness of tested steel do not decrease significantly when reheat temperature below 650 ℃,which means the tested steel exhibits excellent thermal stability.Due to recovery of matrix microstructure and coalescence of ε-Cu precipitates,yield strength of the tested steel decreases significantly when reheat temperature above 650 ℃.Due to appearance of high hardness M/A island,toughness of the tested steel decreases markedly when reheat temperature above 700 ℃.The results indicate that recovery of matrix microstructure,size and quantity of ε-Cu precipitates and M/A island are mainly facters affecting thermal stability of the ultra-low-carbon copper-bearing age-hardening steel.

  8. The Effect Of Two-Stage Age Hardening Treatment Combined With Shot Peening On Stress Distribution In The Surface Layer Of 7075 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Kaczmarek Ł.

    2015-09-01

    Full Text Available The article present the results of the study on the improvement of mechanical properties of the surface layer of 7075 aluminum alloy via two-stage aging combined with shot peening. The experiments proved that thermo-mechanical treatment may significantly improve hardness and stress distribution in the surface layer. Compressive stresses of 226 MPa±5.5 MPa and hardness of 210±2 HV were obtained for selected samples.

  9. Radiation hardenable coating composition

    International Nuclear Information System (INIS)

    Compositions for a radiation hardenable coating material are provided which are easily workable and have superior weather and corrosion resisting properties required for the precoat metal. The main constituent of the composition comprises (a) 20-60% by weight of a first polymer having a molecular weight of not less than 3,000 and containing 0.1-0.4 unsaturated radicals per molecular weight of 1,000, (b) 10-60% by weight of a second polymer having a molecular weight of not less than 1,000 and containing 1-5 unsaturated radicals per molecular weight of 1,000, and (c) 70-5% by weight of vinyl monomers copolymerizable with the first polymer (a) and the second polymer (b). The high energy electron beam irradiating process is employed as a method of hardening these compositions. The energy level of the electron beams range between 0.1 to 3 MeV. In one of the examples, the first polymer was made by polymerizing 200 g of ethyl acetate, 185 g of ethyl acrylate, 15 g of acrylic acid, 5.3 g of azobisbutyl nitrile and 25 g of n-dodecyl mercaptan by heating, and then adding 8.5 g of glycidyl methacrylate, 40 g of hydroquinone and 50 g of tributylbenzyl ammonium chloride by heating. The second polymer was made by polymerizing 200 g of ethyl acetate, 162 g of ethyl acrylate, 38 g of acrylic acid, 5.3 g of azobisbutyl nitrile and 6.0 g of n-dodecyl mercaptan by heating, and then adding 47 g of glycidyl methacrylate, 40 mg of hydroquinone and 500 mg of triethyl benzoyl ammonium chloride by heating. A coating material was made by mixing 30 parts of the first polymer, 40 parts of the second polymer and 30 parts of methyl methacrylate with some pigments. (Iwakiri, K.)

  10. Effect of Aging Temperature on the Mechanical Properties of Cold Hardening Microalloyed Bainitic Steel%时效温度对贝氏体型冷作强化非调质钢力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    杨金峰; 惠卫军; 于同仁; 孙维; 龙晋明

    2011-01-01

    研究了时效温度对一种低碳Mn-B-Ti系贝氏体型冷作强化非调质钢力学性能的影响。结果表明:试验料的强度随时效温度的升高先是增加,并在250℃时存在一个峰值,随后强度又随时效温度的升高而降低,当温度升高到400℃以上时强度明显降低;试验料的塑性和屈强比则随时效温度的升高逐渐增加,其中后者增加的幅度更显著。与未充氢试样相比,试验料拉拔并充氢后的延迟断裂性能显著降低。随着时效温度的升高,充氢试样中的氢含量降低,缺口抗拉强度RBN和延迟断裂强度比R缓慢增加,当时效温度大于200℃时,RBN和R则明显增加。因此,在满足保载永久伸长变形量及强度和塑性要求的前提下,应选择合适的时效温度,以保证材料的延迟断裂性能。%The effect of aging temperature on the mechanical properties of low carbon Mn-B-Ti type cold hardening mieroalloyed bainitic steel was investigated. Experimental results show that strength increases at first and reaches a peak at about 250 ℃, and then decreases with the increase of aging temperature. The decrease of strength is more significant when aging temperature is higher than 400℃. Both ductility and strength ratio increase with increasing aging temperature, while the latter is more significant. The charging of hydrogen significantly impairs the delayed fracture property of the steel subject to 30% cold drawing. Hydrogen content decreases with increasing aging tern perature and thus both notch tensile strength and delayed fracture strength ratio increase. The increase of notch ten- sile strength and delayed fracture strength ratio is more noticeable when aging temperature is higher than 200℃. Therefore, with the precondition of required low permanent deformation, strength and ductility, aging temperature should be chosen carefully to maintain a relatively high application property of delayed fracture resistance.

  11. Concrete hardening accelerator containing galvanic sludge (rus

    Directory of Open Access Journals (Sweden)

    Stepanov S.V.

    2012-12-01

    Full Text Available One of the most effective ways to reduce power inputs to the manufacture of concrete and reinforced concrete products is the use of hardening accelerator additives that reduce the time or lower the temperature of thermal processing. From economic and ecological points of view it is expedient to use the by-products and waste industry for the production of additives. In this paper we propose the use of galvanic sludge, which structure contains oxide, hydroxide and aluminum sulphate. Its use leads to an increase in the strength of cement stone in the first hours and days of hardening, as the number of Ettringite increases in the system. As galvanic sludge is a fine product, it is more effectively used in conjunction with superplasticizer, resulting in a complex chemical additive. Application of such additives enables to triple the durability of the cement stone at the age of 12 hours, and to increase in two times the concrete strength at the age of 1 day of hardening. The effectiveness of additives remains constant when changing the mobility of the mixture, that allows applying it in different ways of forming concrete products.

  12. Effect of Al2Cu precipitates size and mass transport on the polarisation behaviour of age-hardened Al-Si-Cu-Mg alloys in 0.05 M NaCl

    International Nuclear Information System (INIS)

    Research highlights: → Influence of the size distribution of Al-Cu phases on the electrochemical behaviour of well defined alloys under controlled mass transport conditions (RDE). → Oxygen reduction occurs only the Al2Cu phases. → Thinner Al-Cu grains the oxygen reduction current deviates at high rotation rates from the Levich behaviour. - Abstract: The electrochemical behaviour of age-hardened Al-Si-Cu-Mg alloys was investigated in a 0.05 M NaCl solution under controlled mass transport conditions using a rotating disk electrode. This work aimed at getting better understanding of the effect of the alloy microstructure, in particular the size distribution of Al2Cu phase, on the corrosion behaviour of the alloy. Three different size distributions of the Al2Cu phase were obtained through appropriate heat treatments. The cathodic reduction of oxygen was found to occur mainly on the Al2Cu phases acting as preferential cathodes. Small sized Al2Cu phases were found to promote at high rotation rates a transition from a 4 electron to a 2 electron dominated oxygen reduction mechanisms.

  13. Effect of Al{sub 2}Cu precipitates size and mass transport on the polarisation behaviour of age-hardened Al-Si-Cu-Mg alloys in 0.05 M NaCl

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, A.C., E-mail: catarina.vieira@engmateriais.eng.uminho.p [University of Minho, Centre for Mechanics and Materials Technologies (CT2M), 4800-058 Guimaraes (Portugal); Pinto, A.M.; Rocha, L.A. [University of Minho, Centre for Mechanics and Materials Technologies (CT2M), 4800-058 Guimaraes (Portugal); Mischler, S. [Ecole Polytechnique Federale de Lausanne (EPFL), Tribology and Interface Chemistry Group, 1015 Lausanne (Switzerland)

    2011-04-15

    Research highlights: {yields} Influence of the size distribution of Al-Cu phases on the electrochemical behaviour of well defined alloys under controlled mass transport conditions (RDE). {yields} Oxygen reduction occurs only the Al{sub 2}Cu phases. {yields} Thinner Al-Cu grains the oxygen reduction current deviates at high rotation rates from the Levich behaviour. - Abstract: The electrochemical behaviour of age-hardened Al-Si-Cu-Mg alloys was investigated in a 0.05 M NaCl solution under controlled mass transport conditions using a rotating disk electrode. This work aimed at getting better understanding of the effect of the alloy microstructure, in particular the size distribution of Al{sub 2}Cu phase, on the corrosion behaviour of the alloy. Three different size distributions of the Al{sub 2}Cu phase were obtained through appropriate heat treatments. The cathodic reduction of oxygen was found to occur mainly on the Al{sub 2}Cu phases acting as preferential cathodes. Small sized Al{sub 2}Cu phases were found to promote at high rotation rates a transition from a 4 electron to a 2 electron dominated oxygen reduction mechanisms.

  14. A Multi Response Optimization of Tool Pin Profile on the Tensile Behavior of Age-hardenable Aluminum Alloys during Friction Stir Welding

    Directory of Open Access Journals (Sweden)

    D. Vijayan

    2014-05-01

    Full Text Available The main aim of this study is to select a suitable tool pin profile to maximize the tensile behavior (Ultimate Tensile Strength and Tensile Elongation of Friction stir welded aluminum alloys of AA 2024 and AA 6061. The age-hardnable aluminum alloys of 2xxx, 6xxx and 7xxx series are extensively used in automobile and aircraft industries because of its high strength to weight ratio, formability and ductility. These alloys are vulnerable to cracking (2xxx and 7xxx and highly melt (6xxx in conventional fusion welding techniques. Friction stir welding is an emerging solid state welding technique which is best suitable for joining these aluminum alloys. The influential process and tool parameters that are affecting the FS welded joints are such as tool rotational speed, welding speed, axial load and tool pin profile. Dissimilar friction stir welded joints of AA 2024 and AA 6061 aluminum alloys are fabricated using a friction stir welding process to examine the influence of the tool pin profiles on tensile properties on various crucial process parameters. A Box-Behnken design with four input parameters, three levels and 30 runs is used to conduct the experiments and Response Surface Method (RSM is used to develop the mathematical model. The experimental results were predicted at the 95% confidence level. The macro defects in the welds and the modes of tensile fracture are discussed in detail to reveal the root cause of failure in the fabricated samples. The rotating tool equipped with a square pin generated the highest ultimate tensile strength (143 MPa with a 12% elongation. A microstructure variation on dissimilar alloys which result 44% reduction in tensile strength on AA2024 and 51% reduction in tensile strength on AA6061 aluminum alloys was observed on the stir zones.

  15. System-Level Radiation Hardening

    Science.gov (United States)

    Ladbury, Ray

    2014-01-01

    Although system-level radiation hardening can enable the use of high-performance components and enhance the capabilities of a spacecraft, hardening techniques can be costly and can compromise the very performance designers sought from the high-performance components. Moreover, such techniques often result in a complicated design, especially if several complex commercial microcircuits are used, each posing its own hardening challenges. The latter risk is particularly acute for Commercial-Off-The-Shelf components since high-performance parts (e.g. double-data-rate synchronous dynamic random access memories - DDR SDRAMs) may require other high-performance commercial parts (e.g. processors) to support their operation. For these reasons, it is essential that system-level radiation hardening be a coordinated effort, from setting requirements through testing up to and including validation.

  16. Explosive Surface Hardening of Austenitic Stainless Steel

    Science.gov (United States)

    Kovacs-Coskun, T.

    2016-04-01

    In this study, the effects of explosion hardening on the microstructure and the hardness of austenitic stainless steel have been studied. The optimum explosion hardening technology of austenitic stainless steel was researched. In case of the explosive hardening used new idea mean indirect hardening setup. Austenitic stainless steels have high plasticity and can be easily cold formed. However, during cold processing the hardening phenomena always occurs. Upon the explosion impact, the deformation mechanism indicates a plastic deformation and this deformation induces a phase transformation (martensite). The explosion hardening enhances the mechanical properties of the material, includes the wear resistance and hardness. In case of indirect hardening as function of the setup parameters specifically the flayer plate position the hardening increased differently. It was find a relationship between the explosion hardening setup and the hardening level.

  17. Radiation-hardenable diluents for radiation-hardenable compositions

    International Nuclear Information System (INIS)

    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

  18. Precipitation hardening of zirconium based martensites

    International Nuclear Information System (INIS)

    The precipitation of intermetallic compounds from supersaturated solid solutions obtained by fast quenching from the high temperature β-phase field has considerable potential for developing zirconium based alloys with high yield strengths. Zirconium based martensites are metastable constituents and therefore decompose both during quenching (autotempering) and when subsequently heated above room temperature. The nature of the tempering reaction in these martensites is rather complex and depends upon the alloy content and the ageing temperature. The β eutectoid alloys were chosen to investigate the tempering behaviour as they were expected to exhibit significant ageing response. Both molybdenum and silicon stabilise the β phase in zirconium and have limited solubility in α-zirconium. Thus the Zr-Mo and the Zr-Si based martensites can, in principle, be significantly hardened by rapid quenching and ageing treatments. (author)

  19. 应变时效对双相钢和低合金高强钢屈服强度及应变硬化率的影响%Effect of Strain Aging on Yield Strength and Strain Hardening Rate of Dual Phase Steel and High Strength Low Alloy Steel

    Institute of Scientific and Technical Information of China (English)

    吴青松; 欧阳页先

    2012-01-01

    The effect of strain aging on yield strength and strain hardening rate of a dual phase steel and a high strength low alloy(HSLA) steel was studied by mechanical properties test and microstructure observation.The results show that the yield strength of the dual phase steel and the HSLA steel increased by 106 MPa and 28 MPa after 2% pre-strain.After pre-strain and bake,the yield strength of dual phase steel increased by 149 MPa,while yield strength of HSLA steel increased by 66 MPa only.After pre-strain or bake hardening,the strain hardening rate of both steels dropped,but the dual phase steel still had very high strain hardening ability close to the strain hardening rate of HSLA steel without pre-strain.It was ferrire-martensite that made the dual phase steel had higher strain hardening ability than the HSLA steel.%通过力学性能测试和显微组织观察研究了应变时效对双相钢和低合金高强钢屈服强度及应变硬化率的影响。结果表明:经过2%预应变之后,双相钢的屈服强度提高了106MPa,低合金高强钢的屈服强度提高了28MPa;预应变之后再经历烘烤,双相钢的屈服强度提高了149MPa,而低合金高强钢的屈服强度只提高了66MPa;预应变或烘烤硬化之后,两种钢的应变硬化率均降低,但双相钢仍然具有很强的应变硬化能力,其应变硬化率接近于低合金高强钢未预应变条件下的;铁素体马氏体组织赋予了双相钢比低合金高强钢更强的应变硬化能力。

  20. Onycholysis induced by nail hardener.

    Science.gov (United States)

    Helsing, Per; Austad, Joar; Talberg, Hans Jørgen

    2007-10-01

    Nail hardeners appeared in the market during the 1960s. They were basically solutions of formaldehyde. The first adverse effects were published in 1966 (1). Reactions were onycholysis, chromonychia, subungual haemorrhage, and hyperkeratosis. Onycholysis may be non-inflammatory or inflammatory, and is accompanied by throbbing pain. Inflammatory reactions are followed by paronychia and occasional dermatitis on the digital pulpa. PMID:17868227

  1. Induction Hardening of Ferromagnetic Bodies

    Czech Academy of Sciences Publication Activity Database

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

    č. 1 (2002), s. 28-29. ISSN 0340-3521 R&D Projects: GA ČR GA102/01/0184; GA MŠk ME 542 Grant ostatní: PSC(PL) 7T08603716 Keywords : Induction heating * induction hardening * ferromagnetic bodies Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  2. DURABILITY OF HARDENED FLY ASH PASTE

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The mechanical properties and durability ( mainly frost-resistance and carbonation resistance ) of fly ash-CaO-CaSO4 .2H2O hardened paste are studied. The relationship among durability of harden ed fly ash paste, the quantity and distribution of hydrates and the initial p aste texture of hardened fly ash paste is presented.

  3. Working hardening modelization in zirconium alloys

    International Nuclear Information System (INIS)

    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)

  4. Radiation-hardened bulk CMOS technology

    International Nuclear Information System (INIS)

    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

  5. Radiation-hardened control system

    International Nuclear Information System (INIS)

    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 107 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 107 rads was also conducted. RHCS performed properly through the target dose of 107 rads, and sporadic intermittent failures in some programmable logic devices were noted after ∼ 13 Mrads

  6. 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 char...... 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.......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...

  7. On the Precipitation Hardening of Selective Laser Melted AlSi10Mg

    Science.gov (United States)

    Aboulkhair, Nesma T.; Tuck, Chris; Ashcroft, Ian; Maskery, Ian; Everitt, Nicola M.

    2015-08-01

    Precipitation hardening of selective laser melted AlSi10Mg was investigated in terms of solution heat treatment and aging duration. The influence on the microstructure and hardness was established, as was the effect on the size and density of Si particles. Although the hardness changes according to the treatment duration, the maximum hardening effect falls short of the hardness of the as-built parts with their characteristic fine microstructure. This is due to the difference in strengthening mechanisms.

  8. Method of hardening a fluid mass

    NARCIS (Netherlands)

    Zitha, P.L.J.; Jansen, J.D.

    2003-01-01

    The invention relates to a method of hardening a fluid mass in contact with a wall, in a desirable shape. According to the invention, the fluid mass is a magneto-rheological fluid mixture that in addition to at least one hardening component comprises a particulate magnetic component, with minimally

  9. Improved hardening theory for cyclic plasticity.

    Science.gov (United States)

    Vos, R. G.; Armstrong, W. H.

    1973-01-01

    A temperature-dependent version of a combined hardening theory, including isotropic and kinematic hardening, is presented within the framework of recent plasticity formulations. This theory has been found to be especially useful in finite-element analysis of aerospace vehicle engines under conditions of large plastic strain and low-cycle fatigue.

  10. 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....

  11. Challenges in hardening technologies using shallow-trench isolation

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. Challenges in hardening technologies using shallow-trench isolation

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

  15. Precipitation hardening of biodegradable Fe-Mn-Pd alloys

    International Nuclear Information System (INIS)

    This work presents a phenomenological description of the precipitation controlled hardening of a new biodegradable Fe-based alloy developed to fulfill the requirements of temporary implant applications. Pronounced strengthening of the solution-treated martensitic Fe-10Mn-1Pd (in wt.%) alloy upon isothermal aging at temperatures within the ferrite-austenite phase field is observed and attributed to the thermally activated formation of coherent plate-like Pd-rich precipitates on {1 0 0} planes of the matrix. The onset and the early stages of alloy decomposition were studied using two complementary techniques: transmission electron microscopy and three-dimensional atom probe analysis. Three distinct regions of the hardening kinetics are recognized and closely correlated to the evolution of the alloy microstructure. Upon aging, clustering of Pd atoms within the Fe-Mn solid solution occurs. The very small clusters grow, coarsen and adopt a plate-like shape, rearranging mutually to reduce the overall elastic strain energy. The elastic interaction of the dislocation substructure with Pd-rich precipitates of evolving morphology affects the dislocation mobility and is responsible for the hardness evolution of the alloy. A study of the hardening kinetics shows that the process exhibits all the features characteristic of maraging steels.

  16. 3-D Temperature and Stress Simulations of Hardening Concrete

    DEFF Research Database (Denmark)

    Jensen, Poul; Buhr, Birit; Thorborg, Jesper; Hattel, Jesper; Jeppesen, Per; Coff, Niels

    2003-01-01

    When concrete is cast, heat develops. When the concrete cools down there is a risk that thermal gradients induce cracks in the structure. In the Middle East this is especially important as extensive heat builds up due to the high ambient temperatures. Possible formed cracks will have a detrimental...... effect on the overall durability of the structure, especially when placed in or close to a marine environment, and especially if placed in a hot and aggressive environment. In order to minimize the risk of inducing thermal cracks, temperature and stress requirements during the hardening period must be...... the thermo-mechanical conditions during hydration of early age concrete. Material properties as a function of maturity and environmental conditions form the basis of the model. This paper presents temperature and stress calculation results using MAGMAconcrete, and proposed hardening precautions for...

  17. 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 grad...... 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.......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...

  18. Microstructure and strain hardening of steels

    International Nuclear Information System (INIS)

    In the present work, the relation between metallurgical microstructures and strain hardening behaviour of both fcc and bcc steels was investigated. In order to obtain large strains, a new experimental method was developed and the data mathematically prepared for further analysis. It was found that the strain hardening rate increases with decreasing particle size or increasing yield stress of ferritic steels. The strain hardening rate is found to be correlated to the specific microstructure. A new model was formulated to describe large deformations. This has been done on the basis of already existing models. According to the new model, the strain hardening in stage IV is caused by the dislocations in cell interiors instead of those in the cell walls. (orig.)

  19. COMPLEX SURFACE HARDENING OF STEEL ARTICLES

    Directory of Open Access Journals (Sweden)

    A. V. Kovalchuk

    2015-05-01

    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.

  20. Unsaturated polyesters for radiation hardened coatings

    International Nuclear Information System (INIS)

    A review on investigations into the field of electron hardening of polyester coatings is presented. Different compounds subject to hardening are considered. Two trends in the development of methods to increase radiation sensitivity of polyester compounds are pointed out. On the one hand, selection of more active components, modification of polyester with compounds easily copolymerized with monomer, or use of monomers, active in the reaction of copolymerization with polyesters, on the other hand, introduction of catalytic additions-accelerators of the process

  1. Minimum distortion induction hardening of crankshafts; Verzugsminimiertes Induktionshaerten von Kurbelwellen

    Energy Technology Data Exchange (ETDEWEB)

    Dappen, Stefan; Amiri, Farsad [SMS Elotherm GmbH, Remscheid (Germany)

    2008-07-01

    On induction hardening of crankshafts, undesirable distortions occur on the workpiece, especially during fillet hardening. The process patented by SMS Elotherm solves this problem by a combination of distortion simulations, a suitable hardening sequence, systematic power control and special mechanical handling. This article presents the fundamentals and the current techniques of minimum distortion hardening. (orig.)

  2. Hardening of ion-irradiated A533B steels investigated with nanoindentation technique

    International Nuclear Information System (INIS)

    Neutron irradiation embrittlement of reactor pressure vessel (RPV) steels is one of the critical issues on aging management for long term operation of nuclear power plants. Mechanistic understanding of embrittlement is a key to accurate prediction of embrittlement, especially after long term operation where the mechanical test data are sparse. Since matrix hardening is the source of the embrittlement, we focus on matrix hardening of A533B bainitic pressure vessel steel. Bainitic matrix is composed of lath structure made by ferrite and carbides, therefore it is important to understand how this structure affects hardening behavior, and to understand irradiation response of each phase. As the typical dimension of lath structure of A533B is about one micron, nanoindentation technique is suitable for the estimation of hardening of each phase. MV ion accelerators were used for controlled irradiation because MeV ion irradiation can produce defects to the depth greater than the depth where plastic deformation induced by indentation reaches. The nanoindentation results for irradiated steels up to 1 dpa indicate (1) indentation onto carbide colony results in greater hardness than ferrite in unirradiated steels (2) both phases are hardened by ion irradiation, and the irradiation hardening of carbide colony is more significant than ferrite phase. (author)

  3. Influence of electrified surface of cementitious materials on structure formation of hardened cement paste

    Science.gov (United States)

    Alekseev, A.; Gusakov, A.

    2015-01-01

    To provide high strength and durability of concrete it is necessary to study the influence of physical and chemical and mechanical principles of dispersed cementitious systems. The experimental bench was developed to study the influence of electrified surface of cementitious materials on structure formation of hardened cement paste. The test bench allows accelerating the processes of dissolution of cementing materials in water due to influence of electric discharge on their surface. Cement activation with high-voltage corona discharge when AC current is applied allows increasing the ultimate compressive strength of hardened cement paste by 46% at the age of one day and by 20% at the age of 28 days.

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Park, Junhee; Choun, Young-Sun; Kim, Min-Kyu [KAERI, Daejeon (Korea, Republic of)

    2015-05-15

    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.

  6. Applications or radiation polymerization hardening to composites

    International Nuclear Information System (INIS)

    Comprehensive investigation has been made into the application of the polymerization hardening by radiation, particularly electron beam, to the composites of polymers and other materials. The report is divided into four parts, namely 1) characteristics and problems of the reaction of curing by radiation polymerization, 2) improvement of the bonding capability of high molecular weight materials, 3) bonding by radiation, and 4) composites made by the impregnation and polymerization hardening of monomers. The first part includes the effects of dose rate, temperature rise during the hardening, the peculiarity of electron beam irradiation at high dose rate, reaction environment and additive effects. Main conclusions are as follows: caution must be taken to the amount of residual double bonds because they affect the quality of hardened polymers; the polymerization hardening reaction at high dose rate cannot be analogized by that at low dose rate; and the presence of the inhibitors of radical reaction is not preferable. The second part includes the surface treatment by irradiation and radiation graft polymerization. The irradiation of electron beam and chromic acid treatment are the most effective processes for the surface treatment, but some caution is required. The third part includes hair plantation and laminated films. The uses of adhesive tapes and vinyl wall papers are anticipated. The fourth part includes fiber reinforced plastics (FRP), concrete-polymer composites (CPC) and wood-plastic composites (WPC). (Iwakiri, K.)

  7. Deformation behaviour of dispersion hardened nanocrystalline copper

    OpenAIRE

    J.P. Stobrawa; Z.M. Rdzawski

    2006-01-01

    Purpose: The aim of this work was to describe deformation behaviour of nanocrystalline copper dispersion-hardened with nanoparticles of tungsten carbide and yttria.Design/methodology/approach: Tests were made with the Cu, Cu-WC and Cu-Y2O3 micro-composites containing up to 3 % of a hardening phase. These were obtained by powder metallurgy techniques, i.e. milling the input powders in the planetary ball mills, compacting and sintering. The mechanical properties (hardness, 0,2 YS, elongation du...

  8. Investigation of Hardened Filling Grout Samples

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.

     Suzlon Wind Energy A/S requested on August 28, 2007 an investigation of 2 samples of a hardened filling grout to be carried out, comprising drilling and strength determination of 4 test cylinders, and description of the surface characteristics of the samples....... Suzlon Wind Energy A/S requested on August 28, 2007 an investigation of 2 samples of a hardened filling grout to be carried out, comprising drilling and strength determination of 4 test cylinders, and description of the surface characteristics of the samples....

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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 α1. 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

  11. Oxidation hardening kinetics of the rheological function G'/('/G') in asphalts

    KAUST Repository

    Juristyarini, Pramitha

    2011-07-29

    The authors used 9 asphalts oxidized at various temperatures and pressures to determine the hardening kinetics for the DSR function, an easily measured and meaningful surrogate for 15C ductility that relates well to age-related binder deterioration. For each asphalt, there is a rapid initial period that slows to a constant rate period. This constant rate period can be represented by carbonyl formation (oxidation) rate times a hardening susceptibility (HS). For the DSR function and viscosity, the HS and initial jump were pressure-but not temperature-dependent. The DSR function initial jump was relatively higher than the viscosity initial jump. © 2011 Taylor & Francis Group, LLC.

  12. Patterning and hardening of gold black infrared absorber by shadow mask deposition with ethyl cyanoacrylate

    Science.gov (United States)

    Panjwani, Deep; Nader-Esfahani, Nima; Maukonen, Doug; Rezadad, Imen; Boroumand, Javaneh; Smith, Evan; Nath, Janardan; Peale, R. E.

    2013-06-01

    Patterning of gold-black infrared absorbing films by stencil lithography and hardening by polymer infusion is reported. Gold black nano-structured films are deposited through a thin metal shadow mask in a thermal evaporator in ~400 mTorr pressure of inert gas, followed by ethyl cyanoacrylate fuming through the same mask to produce rugged IR absorptive patterns of ~100 micron scale dimensions. Infrared absorptivity is determined by transmission and reflectivity measurements using a Fourier spectrometer and infrared microscope. Results indicate that the optimized hardening process reduces the usual degradation of the absorptivity with age. This work has potential application to infrared array bolometers.

  13. Synergetic effect of Er and Zr on the precipitation hardening of Al-Er-Zr alloy

    International Nuclear Information System (INIS)

    The precipitation hardening of dilute Al-Er, Al-Zr and Al-Er-Zr alloys was investigated by microhardness measurements and transmission electron microscopy. The Al-0.04Er (at.%) alloy obtains its maximum aging hardness of 400 MPa due to the precipitation of Al3Er. The Al-0.04Er-0.08Zr obtains a maximum hardness of 560 MPa, which is significant greater than that of the Al-Er and Al-Zr alloys. The synergetic effect of Er and Zr on the precipitation hardening of Al-Er-Zr alloys is discussed.

  14. Induction surface hardening of hard coated steels

    DEFF Research Database (Denmark)

    Pantleon, Karen; Kessler, Olaf; Hoffmann, Franz;

    1999-01-01

    , the scratch test is used to estimate critical loads for cohesive and adhesive failure of the coatings. Additionally, distortion measurements are carried out. The results emphasize the advantage of induction surface hardening as a method of subsequent heat treatment of CVD-coated steels....

  15. 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...

  16. Mesoscopic model for ferromagnets with isotropic hardening

    Czech Academy of Sciences Publication Activity Database

    Roubíček, Tomáš; Kružík, Martin

    2005-01-01

    Roč. 56, č. 1 (2005), s. 107-135. ISSN 0044-2275 R&D Projects: GA AV ČR IAA1075005 Institutional research plan: CEZ:AV0Z10750506 Keywords : variational inequalities * ferromagnetism * hysteresis, hardening Subject RIV: BA - General Mathematics Impact factor: 0.455, year: 2005

  17. HISTORY OF THE HARDENING OF STEEL : SCIENCE AND TECHNOLOGY

    OpenAIRE

    Vanpaemel, J.

    1982-01-01

    The knowledge of the hardening phenomenon was achieved through a very cumulative process without any discontinuity or 'scientific crisis' . The history of the hardening shows a definite interrelationship between technological approach (or the application-side) and academic science .

  18. HTPro: Low-temperature Surface Hardening of Stainless Steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lundin; Somers, Marcel A. J.

    Low-temperature surface hardening of stainless steel provides the required performance properties without affecting corrosion resistance.......Low-temperature surface hardening of stainless steel provides the required performance properties without affecting corrosion resistance....

  19. Hardenability of steels for oil industry

    Directory of Open Access Journals (Sweden)

    M. Gojic

    2007-08-01

    Full Text Available Purpose: Alloying elements in steels are used for a various reasons. One of the most important is the achievement of higher strength in required shapes and sizes. Often in very large sections of steels are used for production of the oil country tubular goods (OCTG. Therefore the hardenability of steels is an important property aim for the appropriate concentration of alloying elements needed to harden the section of steel for oil industry. In this study the hardenability, the cooling rates and microstructures of low alloy Cr-Mo and Mn-Mo steels were investigated.Design/methodology/approach: The cooling rate determines the amount of martensite structure. Hardenability test was carried out by Jominy method. During Jominy testing the temperature changes were monitored by means of CrNi-Ni thermocouples which are connected to eight-channel digital/analogues converter. Microstructure was determined using a scanning electron microscopy (SEM.Findings: The cooling rates in the temperature range between 1133 and 973 K at different distances from the quenched end of low alloy Cr-Mo and Mn-Mo steels were found. Also the hardness and microstructures against the distances from quenched end are determined.Research limitations/implications: It is known that carbon has a marked the effect on hardenability of steel, but its use at higher levels is limited because lower toughness and increased probability of distortion and cracking during heat treatment and welding. Addition of manganese at low alloy steels is very useful for improvement of their hardenability.Practical implications: Chemical composition of low alloy steels for oil industry is usually complex and defined in most cases by standard which give range of concentration of the important alloying elements (Cr, Mo, Mn, etc. as well as the upper limits of impurity elements (S and P. Alloying elements increase the cost of the steel and from these reason it is important to select only steels which required to

  20. Cryptographic Path Hardening: Hiding Vulnerabilities in Software through Cryptography

    OpenAIRE

    Ganesh, Vijay; Carbin, Michael; Rinard, Martin

    2012-01-01

    We propose a novel approach to improving software security called Cryptographic Path Hardening, which is aimed at hiding security vulnerabilities in software from attackers through the use of provably secure and obfuscated cryptographic devices to harden paths in programs. By "harden" we mean that certain error-checking if-conditionals in a given program P are replaced by equivalent" we mean that adversaries cannot use semi-automatic program analysis techniques to reason about the hardened pr...

  1. Feasibility Studies on Underwater Laser Surface Hardening Process

    OpenAIRE

    Biao Jin; Min Li; TaeWoo Hwang; YoungHoon Moon

    2015-01-01

    Laser surface hardening process is a very promising hardening method for ferrous and nonferrous alloys where transformations occur during cooling after laser melting in the solid state. This study experimentally characterizes laser surface hardening of tool steel in both water and air. For the underwater operation, laser surface scanning is performed over the tool steel surface which is immersed in water. The laser surface hardening tests are performed with a maximum 200 W fiber laser with a ...

  2. MLC mediated beam hardening effects in IMRT

    International Nuclear Information System (INIS)

    Purpose: Beam hardening effects due to photons passing through the multi-leaf collimator (MLC) frequently exist in Intensity Modulated Radiotherapy (IMRT) fields. A fast online dose transmission verification system, MBMC (Measurement Based Monte Carlo), can verify IMRT delivery by using a fluence efficiency map to replace MLC geometry and movement simulation. This system, however, ignores beam hardening effects, and assumes that dose disturbances through the MLC are not significant for IMRT fields. This assumption has to be justified before it can be applied in the clinic. Methods: In this study, we simulated several field sizes (0.5 × 0.5, 1 × 1, 3 × 3, 5 × 5, and 10 × 10 cm2) to evaluate the dose influence of beam hardening effects under clinical conditions. In addition, a LATCH technique was used during simulation processes, which can record each particle interaction with specific gantry components, to distinguish between dose contribution from the total beam and MLC mediated beam. Results: The MLC indeed caused significant beam hardening effects, but the dose contribution fraction from the MLC was noticeable only for field sizes less than 1 × 1 cm2. Furthermore, in mixed fields containing both the total beam and MLC mediated beam, the maximum dose deviation due to the presence of the MLC is small even for the 0.5 × 0.5 cm2 field size (∼2%). Conclusions: The MLC causes noticeable beam hardening effects, but this effect results in only slight dose differences that are only noticeable for small field sizes in IMRT delivery. The use of a fluence efficiency map was feasible in our MBMC system.

  3. 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.

  4. Precipitation mechanisms and subsequent hardening kinetics in the β-CEZ alloy

    International Nuclear Information System (INIS)

    The β-CEZ alloy : Ti-5%Al-2%Sn-4%Zr-4%Mo-2%Cr-1%Fe is a near β titanium alloy. Since its processing routes include heat treatment (consisting of solution treatment and ageing), it has been decided to study the influence of the β phase stability on α phase precipitation and hardening kinetics. Small sized specimens, coming from industrial heats, have been heat treated above and below the β transus, and then water quenched. Therefore, several degree of β stability are obtained. When it is increased (i.e. the solution treatment temperature is lowered), α or ω phases precipitations are delayed, as well as the hardening phenomena. Moreover, the ω stability domain is reduced. The mechanisms of α or ω precipitation are discussed, and related to the hardening kinetics. (orig.)

  5. The role of interstitial nitrogen in the precipitation hardening reactions in high-chromium ferritic steels

    International Nuclear Information System (INIS)

    The effects of exposure to temperatures in the range 475 - 800 C on the hardness and associated microstructure of high chromium ferritic steels has been investigated. Low-carbon 26Cr-1Mo steels containing 0,02 - 0,04% nitrogen were found to constitute an age hardening system when quenched from a temperature of nitrogen solubility and exposed at temperatures in the range 600 - 700 C. TEM observations on thin foils revealed that hardening was associated with the formation of a high density of Cr-N zones. Ageing at 475 C and 550 C produced hardening due to the formation of chromium-rich ferrite phases α' as result of the miscibility gap in the Fe-Cr phase diagram. However the presence of interstitial nitrogen in solution in the steel considerably reduced the rate of hardening, especially at 475 C. This type of decomposition occurs by a mechanism of nucleation and growth, forming zones similar to those formed during an ageing at 600 C. When depleted of interstitial nitrogen, the specimens aged at 475 C underwent spinodal decomposition. Thus nitrogen in solid solution was found to have a significant effect on the 475 C hardening reaction. Precision X-ray diffraction measurements revealed the presence of secondary diffraction peaks associated with the Bragg peaks, which confirmed the formation of Cr-rich phases during ageing at 475 C. The calculated associated lattice parameter measurements allowed estimates of the compositions of the decomposition phases to be made. These were calculated to be about 6-18% Cr in the Fe-rich and 60-80% Cr in the Cr-rich phases of the 26Cr-1Mo steel

  6. Aging.

    Science.gov (United States)

    Park, Dong Choon; Yeo, Seung Geun

    2013-09-01

    Aging is initiated based on genetic and environmental factors that operate from the time of birth of organisms. Aging induces physiological phenomena such as reduction of cell counts, deterioration of tissue proteins, tissue atrophy, a decrease of the metabolic rate, reduction of body fluids, and calcium metabolism abnormalities, with final progression onto pathological aging. Despite the efforts from many researchers, the progression and the mechanisms of aging are not clearly understood yet. Therefore, the authors would like to introduce several theories which have gained attentions among the published theories up to date; genetic program theory, wear-and-tear theory, telomere theory, endocrine theory, DNA damage hypothesis, error catastrophe theory, the rate of living theory, mitochondrial theory, and free radical theory. Although there have been many studies that have tried to prevent aging and prolong life, here we introduce a couple of theories which have been proven more or less; food, exercise, and diet restriction. PMID:24653904

  7. Radiation-hardened transistor and integrated circuit

    Science.gov (United States)

    Ma, Kwok K.

    2007-11-20

    A composite transistor is disclosed for use in radiation hardening a CMOS IC formed on an SOI or bulk semiconductor substrate. The composite transistor has a circuit transistor and a blocking transistor connected in series with a common gate connection. A body terminal of the blocking transistor is connected only to a source terminal thereof, and to no other connection point. The blocking transistor acts to prevent a single-event transient (SET) occurring in the circuit transistor from being coupled outside the composite transistor. Similarly, when a SET occurs in the blocking transistor, the circuit transistor prevents the SET from being coupled outside the composite transistor. N-type and P-type composite transistors can be used for each and every transistor in the CMOS IC to radiation harden the IC, and can be used to form inverters and transmission gates which are the building blocks of CMOS ICs.

  8. A scaleable, radiation hardened shallow trench isolation

    Energy Technology Data Exchange (ETDEWEB)

    Brady, F.T.; Maimon, J.D.; Hurt, M.J.

    1999-12-01

    Shallow Trench Isolation (STI) is rapidly replacing LOCOS (Local Oxidation of Silicon) as the device isolation process of choice. However, little work has been done to characterize the radiation-hardness capability of devices built with STI. In this paper, some of the basics of STI devices are examined, such as the radiation response of unhardened STI devices. The authors discuss several issues affecting the total dose hardness of unhardened STI. These issues have critical implications for the hardness of CMOS built using STI in commercial foundries. Finally, data from hardened STI devices are presented. Total dose hardened STI devices are demonstrated on devices with gate widths down to 0.5 {micro}m.

  9. Construction procedures using self hardening fly ash

    Science.gov (United States)

    Thornton, S. I.; Parker, D. G.

    1980-07-01

    Fly ash produced in Arkansas from burning Wyoming low sulfur coal is self-hardening and can be effective as a soil stabilizing agent for clays and sands. The strength of soil-self hardening fly ash develops rapidly when compacted immediately after mixing. Seven day unconfined compressive strengths up to 1800 psi were obtained from 20% fly ash and 80% sand mixtures. A time delay between mixing the fly ash with the soil and compaction of the mixture reduced the strength. With two hours delay, over a third of the strength was lost and with four hours delay, the loss was over half. Gypsum and some commercial concrete retarders were effective in reducing the detrimental effect of delayed compaction. Adequate mixing of the soil and fly ash and rapid compaction of the mixtures were found to be important parameters in field construction of stabilized bases.

  10. Radiation-chemical hardening of epoxyoligoesteracrylates

    International Nuclear Information System (INIS)

    The paint and varnish epoxide compositions radiation-hardened with the following warm-up (γ-radiation of 60%, dose rate 1 Gy/s; accelerated electrons, dose rate 1.7 kGy/s) are obtained. Therewith both methods of epoxy group inclusions into a three-dimensional net are coincided: preliminary epoxy resin modification by methacrylic acid and inclusion ternary amine into compositions. Physicomechanical and electric characteristics of oligomeric compositions are presented

  11. Continual Induction Hardening of Long Iron Pipes

    Czech Academy of Sciences Publication Activity Database

    Barglik, J.; Doležel, Ivo; Karban, P.; Kwiecien, I.; Ulrych, B.

    Gliwice - Ustroň: Politechnika Slaska, 2005, s. 59-62. ISBN 83-85940-27-8. [International Conference on Fundamentals of Electrotechnics and Circuit Theory - IC SPETO 2005 /28./. Gliwice - Ustroň (PL), 11.05.2005-14.05.2005] Institutional research plan: CEZ:AV0Z20570509 Keywords : induction hardening * electromagnetic and temperature fields * long iron pipes Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  12. Rapid-1 Hardening Accelerator Concrete Admixture

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    SIKA Rapid-1 is a concrete admixture that allows the development of very early high strengths in concrete consisting of commonly used mix components. Unlike concrete set accelerators, it does not reduce set time or long-term strength, and it does not corrode steel reinforcing. This hardening accelerator allows placement of fresh concrete without early stiffening, followed by a period of very rapid strength gain after initial set.

  13. 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.

  14. 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)

  15. Fatigue of coated and laser hardened steels

    International Nuclear Information System (INIS)

    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)

  16. Beam hardening correction algorithm in microtomography images

    International Nuclear Information System (INIS)

    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)

  17. 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.

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

    International Nuclear Information System (INIS)

    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

  19. Deformation behaviour of dispersion hardened nanocrystalline copper

    Directory of Open Access Journals (Sweden)

    J.P. Stobrawa

    2006-04-01

    Full Text Available Purpose: The aim of this work was to describe deformation behaviour of nanocrystalline copper dispersion-hardened with nanoparticles of tungsten carbide and yttria.Design/methodology/approach: Tests were made with the Cu, Cu-WC and Cu-Y2O3 micro-composites containing up to 3 % of a hardening phase. These were obtained by powder metallurgy techniques, i.e. milling the input powders in the planetary ball mills, compacting and sintering. The mechanical properties (hardness, 0,2 YS, elongation during compression test and microstructure were examined by the optical, scanning and transmission electron microscopy.Findings: Analysis of the initial nanocrystalline structure of these materials was made, and its evolution during deformation process was investigated with an account of the hardening effect and the changes in the mechanical and plastic properties. Results of this analysis have been discussed based on the existing theories related to hardening of nanocrystalline materials.Research limitations/implications: The powder metallurgy techniques make it possible to obtain copper-based bulk materials by means of milling input powders in the planetary ball, followed by compacting and sintering. Additional operations of hot extrusion are also often used. There is some threat, however, that during high-temperature processing or using these materials at elevated or high temperatures this nanometric structure may become unstable. The studies have shown the importance of “flows” in the consolidated materials such as pores or regions of poor powder particles joining which significantly deteriorate mechanical properties of compacted and sintered powder micro composites.Practical implications: A growing trend to use new copper-based functional materials is observed recently world-wide. Within this group of materials particular attention is drawn to those with nanometric grain size of a copper matrix, which exhibit higher mechanical properties than

  20. Empirical beam hardening correction (EBHC) for CT

    Energy Technology Data Exchange (ETDEWEB)

    Kyriakou, Yiannis; Meyer, Esther; Prell, Daniel; Kachelriess, Marc [Institute of Medical Physics, University of Erlangen-Nuernberg, 91052 Erlangen (Germany)

    2010-10-15

    Purpose: Due to x-ray beam polychromaticity and scattered radiation, attenuation measurements tend to be underestimated. Cupping and beam hardening artifacts become apparent in the reconstructed CT images. If only one material such as water, for example, is present, these artifacts can be reduced by precorrecting the rawdata. Higher order beam hardening artifacts, as they result when a mixture of materials such as water and bone, or water and bone and iodine is present, require an iterative beam hardening correction where the image is segmented into different materials and those are forward projected to obtain new rawdata. Typically, the forward projection must correctly model the beam polychromaticity and account for all physical effects, including the energy dependence of the assumed materials in the patient, the detector response, and others. We propose a new algorithm that does not require any knowledge about spectra or attenuation coefficients and that does not need to be calibrated. The proposed method corrects beam hardening in single energy CT data. Methods: The only a priori knowledge entering EBHC is the segmentation of the object into different materials. Materials other than water are segmented from the original image, e.g., by using simple thresholding. Then, a (monochromatic) forward projection of these other materials is performed. The measured rawdata and the forward projected material-specific rawdata are monomially combined (e.g., multiplied or squared) and reconstructed to yield a set of correction volumes. These are then linearly combined and added to the original volume. The combination weights are determined to maximize the flatness of the new and corrected volume. EBHC is evaluated using data acquired with a modern cone-beam dual-source spiral CT scanner (Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany), with a modern dual-source micro-CT scanner (TomoScope Synergy Twin, CT Imaging GmbH, Erlangen, Germany), and with a modern

  1. Precipitation hardening in ternary alloys of the Al-Sc-Cu and Al-Sc-Si systems

    International Nuclear Information System (INIS)

    The processes of precipitation hardening in cast ternary alloys of the Al-Sc-Cu and Al-Sc-Si systems were studied in the temperature range of aging from 100 to 450 C and at exposures to 200 h. It was shown that the CuAl2 and ScAl3 phases were involved in the process of aging in ternary Al-Sc-Cu alloys, and the Si and V (AlSiSc) phases, in ternary Al-Sc-Si alloys with excess silicon in a supersaturated solid solution. The V phase was for the first time revealed as the hardening phase in aluminum alloys

  2. Effect of Overaging on Solute Distributions and Bake Hardening Phenomenon in Bake Hardening Steels%Effect of Overaging on Solute Distributions and Bake Hardening Phenomenon in Bake Hardening Steels

    Institute of Scientific and Technical Information of China (English)

    WANG Hua; SHI Wen; HE Yan-lin; LU Xiao-gang; LI Lin

    2012-01-01

    Specimens of two different kinds of bake hardening steels (BH-Mn and BH-P) were prepared and treated with different annealing processes (water quenching and overaging). A novel technique of three dimensional atom probe was used to investigate solute distributions in these steels. The results indicate that C concentration decreases, whereas V increases during overaging in both bake hardening steels. The conclusion that no vanadium carbides pre- cipitate during the overaging is therefore originally obtained by microanalysis in bake hardening steels. Moreover, bake hardening values of all the specimens were tested by tensile experiments with 2 0/~ pre-deformation. However, those of overaged specimens were further measured with higher levels of pre-deformation because no bake hardening phenomenon was present at 2% pre-deformation. As the pre-deformation increases from 2% to 6% and 8%, both overaged steels show bake hardening values, and the value data are almost the same.

  3. Coating compositions hardenable by ionization beams

    International Nuclear Information System (INIS)

    Coating compositions hardenable by ionizing radiation are described which contain as binding agents a mixture of at least 1 unsaturated olefin compound containing urethane groups, and at least 1 further unsaturated olefin compound that may be copolymerized. The unsaturated olefin compound containing the urethane groups is a reaction product of a compound containing carboxylic acid groups and a compound containing at least 1 isocyanate group where the mixture of the two olefins may contain conventional additives of the lacquer industry. 6 claims, no drawings

  4. Computer Modeling of Continual Induction Hardening

    Czech Academy of Sciences Publication Activity Database

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

    Orlando, Florida: International Institute of Informatics and Systemics, 2003, s. 400-405. ISBN 980-6560-01-9. [World Multiconference on Systemics, Cybernetics and Informatics - SCI 2003 /7./. Orlando, Florida (US), 27.07.2003-30.07.2003] R&D Projects: GA ČR GA102/01/0184; GA MŠk ME 542 Grant ostatní: PSRC(PL) 4T08C 04823 Institutional research plan: CEZ:AV0Z2057903 Keywords : induction heating * induction hardening * harmonic electromagnetic field Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  5. Enabling Strain Hardening Simulations with Dislocation Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Arsenlis, A; Cai, W

    2006-12-20

    Numerical algorithms for discrete dislocation dynamics simulations are investigated for the purpose of enabling strain hardening simulations of single crystals on massively parallel computers. The algorithms investigated include the /(N) calculation of forces, the equations of motion, time integration, adaptive mesh refinement, the treatment of dislocation core reactions, and the dynamic distribution of work on parallel computers. A simulation integrating all of these algorithmic elements using the Parallel Dislocation Simulator (ParaDiS) code is performed to understand their behavior in concert, and evaluate the overall numerical performance of dislocation dynamics simulations and their ability to accumulate percents of plastic strain.

  6. Hardening device, by inserts, of electronic component against radiation

    International Nuclear Information System (INIS)

    The hardening device includes at least two materials, one with high atomic number with respect to the other. One of these materials is set as inserts in a layer of the other material. The hardening device is then made by stacking of such layers, the insert density varying from one layer to the other, making thus vary the atomic number resulting from the hardening device along its thickness, following a predefined law

  7. STUDIES ON HARDENING AND ACCLIMITIZATION OF MICROPROPAGATED PLANTLETS OF BANANA CV. GRAND NAINE

    Directory of Open Access Journals (Sweden)

    S AHMED

    2016-09-01

    Full Text Available The experimental plant material of cv. Grand Naine was raised through tissue culture on MS medium using suckers as explants. The MS medium supplemented with BAP 4.00 mg/L+ IAA 2.00 mg/L was used for shoot multiplication. The rooting was obtained on MS (half strength medium fortified with IBA 1.00 mg/L and activated charcoal 200 mg/L. The in vitro rooted plantlets were hardened and acclimatized by using different treatments. Plants transplanted at the age of 4 weeks after root initiation gave maximum survival (100.00 % during transplanting. These plants were hardened in glass beaker and polythene bags singly or in cluster. The maximum survival during hardening (100.00 % was observed by covering the plantlets with glass beaker individually and kept in culture room. Out of various potting mixture tried, the potting mixture containing soil: sand and FYM (2:1:1 v/v/v gave maximum height and survival of plantlets. The results showed that out of different potting mixtures used for hardening soil: sand and FYM (2:1:1 v/v/v showed cent percent survival.

  8. Metal Artifact Reduction for Polychromatic X-ray CT Based on a Beam-Hardening Corrector.

    Science.gov (United States)

    Park, Hyoung Suk; Hwang, Dosik; Seo, Jin Keun

    2016-02-01

    This paper proposes a new method to correct beam hardening artifacts caused by the presence of metal in polychromatic X-ray computed tomography (CT) without degrading the intact anatomical images. Metal artifacts due to beam-hardening, which are a consequence of X-ray beam polychromaticity, are becoming an increasingly important issue affecting CT scanning as medical implants become more common in a generally aging population. The associated higher-order beam-hardening factors can be corrected via analysis of the mismatch between measured sinogram data and the ideal forward projectors in CT reconstruction by considering the known geometry of high-attenuation objects. Without prior knowledge of the spectrum parameters or energy-dependent attenuation coefficients, the proposed correction allows the background CT image (i.e., the image before its corruption by metal artifacts) to be extracted from the uncorrected CT image. Computer simulations and phantom experiments demonstrate the effectiveness of the proposed method to alleviate beam hardening artifacts. PMID:26390451

  9. Anomalous aging behavior of a Ni–Mo–Cr–Re alloy

    International Nuclear Information System (INIS)

    In age hardening nickel alloys, an aging time up to a few hours is usually required to allow hardening phase to nucleate and grow particularly when the hardening kinetics are controlled by subsitutional diffusion. To reduce the aging time and therefore improve the production efficiency, deformation can be used to accelerate the aging process. We designed and studied an alloy with accelerated age hardening rates by considering various atomistic parameters so that an age-hardening material can be produced with an aging time less than 5 min without deformation. Contrary to most of the alloys, deformation decelerated the aging. The atomic resolution electron microscopy studies indicated that the hardening kinetics was related to the formation of the nano-particles and location of the doped atoms.

  10. Configurable Radiation Hardened High Speed Isolated Interface ASIC Project

    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...

  11. The mechanism of irradiation hardening of iron model alloys

    International Nuclear Information System (INIS)

    The mechanism of irradiation hardening of iron-model alloys is reviewed. Irradiation hardening consists of several components which are caused by several sorts of damage structures, namely hardeners. The contribution of each hardener, that is, cooper clusters and matrix defects such as microvoids and interstitial dislocation loops (I-loops) to irradiation hardening is quantitatively evaluated based on the microstructure-hardening correlation studies. Neutron and electron irradiation hardening and post-irradiation annealing behavior in iron model alloys have been investigated. Neutron irradiations were performed in the Japan Material Testing Reactor (JMTR) up to the maximum neutron fluence of 7 x 1019 n/cm2 (>1MeV) with different neutron fluxes ranging from 1.5 x 1011 to 1013 n/cm2, with using a multi-division temperature-control irradiation rig that enabled to remove a part of the specimens during reactor operation under controlling irradiation temperature. Electron irradiations were performed up to electron doses between 2.1 x 1019 e-/cm2 (0.9 mdpa) and 5.1 x 1020 e-/cm2 (22 mdpa) at around 290degC. Tensile tests were carried out at a crosshead speed of 0.2 mm/min at room temperature. Micro-Vickers hardness tests, positron annihilation spectroscopy (PAS) measurements and electrical resistivity measurements using a conventional four probes method were carried out at room temperature. Post-irradiation annealing behavior of the hardening and microstructure changes were also investigated by these experimental methods. The amount of irradiation hardening of iron-copper alloys is significantly larger than those of pure Fe, indicating that copper clusters are an important factor of irradiation hardening. The contribution of copper clusters to the hardening is rather large but almost similar to the hardening caused by I-loops in copper alloys. Microvoids are not a high potential hardener. Another high potential hardener is manganese. The iron-manganese model alloy suffers

  12. Radiation hardening of unsaturated polyesters in the presence of oxygen

    International Nuclear Information System (INIS)

    The review is devoted to methods of removing the sticky layer of unhardened resin formed in hardening of polyester lacquer films in air due to co-polymerization inhibition in the surface oxygen layer. Specific features of radiation hardening of oligomers in films, avoiding the inhibition by choosing hardening conditions and composition, combined methods of reducing stickiness are considered. The data available indicate a difference between causes of sticky surface formation in radiation and thermal hardening and methods of avoiding this unwanted effect. Successful solutions of the problem are associated with using monomers active in oxidative polymerization reactions or monomers active in the chain transfer reaction

  13. Hardness variability in commercial and hardened technologies

    International Nuclear Information System (INIS)

    Over the past 10 years, there have been a number of advances in methods to assess and assure the radiation hardness of microelectronics in military and space applications. At the forefront of these is the Qualified Manufacturers List (QML) methodology, in which the hardness of product is ''built-in'' through statistical process control (SPC) of technology parameters relevant to the radiation response, test structure to integrated circuit (IC) correlations, and techniques for extrapolating laboratory test results to varying radiation scenarios. At the same time, there has been renewed interest in the use of commercial technology -- with its enhanced performance, reduced cost, and higher reliability -- in military and space systems. In this paper, we initially demonstrate the application of QML techniques to assure and control the radiation response of hardened technologies. Through several examples, we demonstrate intra-die, wafer-to-wafer, and lot-to-lot variations in a hardened technology. We observe 10 to 30% variations in key technology parameters that result from variability in geometry, process, and design layout. Radiation-induced degradation is seen to mirror preirradiation characteristics. We then evaluate commercial technologies and report considerably higher variability in radiation hardness, i.e., variations by a factor of two to five. This variability is shown to arise from a lack of control of technology parameters relevant to the radiation response, which a commercial manufacturer has no interest in controlling in a normal process flow

  14. Hardened Client Platforms for Secure Internet Banking

    Science.gov (United States)

    Ronchi, C.; Zakhidov, S.

    We review the security of e-banking platforms with particular attention to the exploitable attack vectors of three main attack categories: Man-in-the-Middle, Man-in-the-PC and Man-in-the-Browser. It will be shown that the most serious threats come from combination attacks capable of hacking any transaction without the need to control the authentication process. Using this approach, the security of any authentication system can be bypassed, including those using SecureID Tokens, OTP Tokens, Biometric Sensors and Smart Cards. We will describe and compare two recently proposed e-banking platforms, the ZTIC and the USPD, both of which are based on the use of dedicated client devices, but with diverging approaches with respect to the need of hardening the Web client application. It will be shown that the use of a Hardened Browser (or H-Browser) component is critical to force attackers to employ complex and expensive techniques and to reduce the strength and variety of social engineering attacks down to physiological fraud levels.

  15. Radiation-hardened microelectronics for space applications

    International Nuclear Information System (INIS)

    Radiation-hardened technology for space applications will be evaluated in light of its survivability in the total-dose, cosmic-ray, and solar flare environments normally encountered in space. Several examples of technology development programs will be summarized. Techniques for optimizing the radiation hardness of complementary metal oxide silicon (CMOS) technologies for space will be discussed. For total-dose hardness, these techniques provide important information about the number of radiation-induced defects and their microscopic nature, and are used to identify manufacturing processes that play an important role in the fabrication of radiation-hardened integrated circuits (ICs). For example, the roles of high-temperature anneals, hydrogen and interfacial strain in the buildup of radiation-induced defects have received a great deal of attention, and many CMOS process flows have been designed to minimize hydrogen incorporation and reduce interfacial stress. Techniques for ensuring the tolerance of ICs to single-event phenomena (SEP) will be addressed, including the manufacture and control of high-resistivity polysilicon feedback resistors. Finally, some future trends in hardness assurance and testing that support more cost-effective qualification of ICs used in space will be covered. For total-dose, trends include wafer-level testing and X-ray irradiations; while for SEP, trends include Cf-252 and laser testing. (author)

  16. Influence of temperature on autogenous deformation and relative humidity change in hardening cement paste

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben

    1999-01-01

    This paper deals with autogenous deformation and autogenous relative humidity change (RH change) in hardening cement paste. Theoretical considerations and experimental data are presented, which elucidate the influence of temperature on these properties. This is an important subject in the control...... of early age cracking of concrete. It is demonstrated that the traditional maturity concept generally is not applicable to autogenous deformation and autogenous RH change. (C) 1999 Elsevier Science Ltd. All rights reserved....

  17. The variation of work hardening characteristics of Al-5 wt% Mg alloy during phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud, M.A., E-mail: moustafa_a_mahmoud@hotmail.co [Physics Department, Faculty of Education, Ain Shams University, P.O. Box 5101, Heliopolis 11771, Roxy, Cairo (Egypt); Sobhy, M. [Physics Department, Faculty of Education, Ain Shams University, P.O. Box 5101, Heliopolis 11771, Roxy, Cairo (Egypt); Abd El-Rehim, A.F., E-mail: afabdelrehim@yahoo.co [Physics Department, Faculty of Education, Ain Shams University, P.O. Box 5101, Heliopolis 11771, Roxy, Cairo (Egypt); Abdel Rahman, R.M. [Modern Academy for Engineering and Technology in Maadi, Basic Science Department, Physics Section, Cairo (Egypt)

    2010-09-01

    The aim of this study is to investigate the effect of aging conditions on the stress-strain behavior along with microstructure changes of the Al-5 wt% Mg alloy. Following solid solution treatment and aging of specimens at temperatures ranging from 373 to 573 K for various aging times (1/4 to 4 h), stress-strain tests were performed at different testing temperatures (313-343 K). The work hardening parameters ({sigma}{sub y}, {sigma}{sub f}, {chi}{sub p} and Y) were found to decrease continuously with pre-aging times at all aging and testing temperatures, where the softening parameters ({epsilon}{sub f} and L) oppose this behavior. The variation in stress-strain parameters with increasing aging temperatures and aging times was explained on the basis of structural transformations taking place in the Al-Mg alloy. A precipitate-dislocation intersections mechanism was assumed as the rate-controlling mechanism for alloy.

  18. Hardening treatment of friction surfaces of ball journal bearings

    Science.gov (United States)

    Gorlenko, A. O.; Davidov, S. V.

    2016-04-01

    The article presents the technology of finishing plasma hardening by the application of the multi-layer nanocoating Si-O-C-N system to harden the friction surfaces of the ball journal bearings. The authors of the paper have studied the applied wear-resistant anti-friction coating tribological characteristics, which determine the increase in wear resistance of the ball journal bearings.

  19. Analysis of the work-hardening process in spheroidized steels

    International Nuclear Information System (INIS)

    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)

  20. Calculation of distortion of tool steel dies during hardening

    Energy Technology Data Exchange (ETDEWEB)

    Thuvander, A. [Swedish Institute for Metals Research, Stockholm (Sweden)

    1996-12-31

    Distortion from hardening was studied for tool steel specimens of geometries typical of tools. Experiments and computer simulations were performed and the results were compared. The experiments were performed for box-shaped specimens of two different sizes and rings with radial grooves on one side. All specimens were made in a tool steel K326. They were hardened in a fluidized bed. The temperature history was measured with thermocouples during quenching. Distortion was measured from quenching only and from hardening including tempering. The distortion modes of the ring which had been hardened in the fluidized bed included bore diameter reduction, clonicity, height variations and out of roundness distortion. Some of the faces of the box-shaped specimens were convex and the dimensions of the cavities were reduced after hardening in fluidized bed. Most of the above distortion modes could be reproduced by the numerical simulations but some of the calculated measures were not as well in agreement with measurements.

  1. Modeling of state parameter and hardening function for granular materials

    Institute of Scientific and Technical Information of China (English)

    彭芳乐; 李建中

    2004-01-01

    A modified plastic strain energy as hardening state parameter for dense sand was proposed, based on the results from a series of drained plane strain tests on saturated dense Japanese Toyoura sand with precise stress and strain measurements along many stress paths. In addition, a unique hardening function between the plastic strain energy and the instantaneous stress path was also presented, which was independent of stress history. The proposed state parameter and hardening function was directly verified by the simple numerical integration method. It is shown that the proposed hardening function is independent of stress history and stress path and is appropriate to be used as the hardening rule in constitutive modeling for dense sand, and it is also capable of simulating the effects on the deformation characteristics of stress history and stress path for dense sand.

  2. New analytical approach for neutron beam-hardening correction.

    Science.gov (United States)

    Hachouf, N; Kharfi, F; Hachouf, M; Boucenna, A

    2016-01-01

    In neutron imaging, the beam-hardening effect has a significant effect on quantitative and qualitative image interpretation. This study aims to propose a linearization method for beam-hardening correction. The proposed method is based on a new analytical approach establishing the attenuation coefficient as a function of neutron energy. Spectrum energy shift due to beam hardening is studied on the basis of Monte Carlo N-Particle (MCNP) simulated data and the analytical data. Good agreement between MCNP and analytical values has been found. Indeed, the beam-hardening effect is well supported in the proposed method. A correction procedure is developed to correct the errors of beam-hardening effect in neutron transmission, and therefore for projection data correction. The effectiveness of this procedure is determined by its application in correcting reconstructed images. PMID:26609685

  3. Probabilistic Analysis of Fatigue Behavior of Induction Hardened Steel

    International Nuclear Information System (INIS)

    This study considers how the fatigue behavior and probabilistic properties of S.a.e. steel are related to its hardness level. S.a.e. steel was heat-treated using induction hardening. Five types of specimens were prepared (A: base material, B: through hardened material with HIV, C: through hardened material with HIV, D: through hardened material with HIV, and E: surface hardened material with HIV). Fatigue tests were performed under a stress ratio of R = -1 using a 4-point rotary bending fatigue tester. The fatigue behaviors were greatly influenced by the hardness, but the fatigue limit did not increase over a hardness of HIV. In addition, the effect of the hardness level on the failure mechanism was evaluated using a scanning electron microscope. The probabilistic properties of the fatigue life were investigated using a probabilistic S-N approach, and the effect of the hardness level on these properties was evaluated using a residue analysis

  4. Keystroke Dynamics-Based Credential Hardening Systems

    Science.gov (United States)

    Bartlow, Nick; Cukic, Bojan

    abstract Keystroke dynamics are becoming a well-known method for strengthening username- and password-based credential sets. The familiarity and ease of use of these traditional authentication schemes combined with the increased trustworthiness associated with biometrics makes them prime candidates for application in many web-based scenarios. Our keystroke dynamics system uses Breiman’s random forests algorithm to classify keystroke input sequences as genuine or imposter. The system is capable of operating at various points on a traditional ROC curve depending on application-specific security needs. As a username/password authentication scheme, our approach decreases the system penetration rate associated with compromised passwords up to 99.15%. Beyond presenting results demonstrating the credential hardening effect of our scheme, we look into the notion that a user’s familiarity to components of a credential set can non-trivially impact error rates.

  5. Transformation hardening of steel by laser beam

    International Nuclear Information System (INIS)

    A locally fabricated 250 Watts Co/sub 2/ laser has been used to study the surface hardening of steel with different carbon concentrations ranging from 0.17 to 0.6%. The laser beam was defocused to a spot size of 2mm. Preliminary results indicate a more than 2.5 times increases in hardness for the 0.17%, 0.45% and 0.6% carbon steel. The microhardness was found to increase exponentially with increasing concentrations of carbon in steel. The microstructure shows that maximum hardness appears in the region that is transformed to martensite. The results were found to be in excellent agreement with similar works carried out elsewhere. (author)

  6. Dilatant hardening of fluid-saturated sandstone

    Science.gov (United States)

    Makhnenko, Roman Y.; Labuz, Joseph F.

    2015-02-01

    The presence of pore fluid in rock affects both the elastic and inelastic deformation processes, yet laboratory testing is typically performed on dry material even though in situ the rock is often saturated. Techniques were developed for testing fluid-saturated porous rock under the limiting conditions of drained, undrained, and unjacketed response. Confined compression experiments, both conventional triaxial and plane strain, were performed on water-saturated Berea sandstone to investigate poroelastic and inelastic behavior. Measured drained response was used to calibrate an elasto-plastic constitutive model that predicts undrained inelastic deformation. The experimental data show good agreement with the model: dilatant hardening in undrained triaxial and plane strain compression tests under constant mean stress was predicted and observed.

  7. Surface modification on PMMA : PVDF polyblend: hardening under chemical environment

    Indian Academy of Sciences (India)

    R Bajpai; V Mishra; Pragyesh Agrawal; S C Datt

    2002-02-01

    The influence of chemical environment on polymers include the surface alteration as well as other deep modifications in surface layers. The surface hardening, as an effect of organic liquids on poly(methyl methacrylate): poly(vinylidene fluoride) (PMMA: PVDF), which is one of the few known miscible blends, has been detected using microhardness testing. Organic liquids like acetone, toluene, xylene and benzene were introduced on the surface of blend specimens for different durations. Vickers microhardness (v) was measured for treated and untreated specimens. The study reveals both hardening and plasticization of specimens at different exposure times. The degree of surface hardening is maximum under acetone treatment. All the specimens exhibit surface hardening at an exposure time of 1 h with all the four liquids. This feature is prominent with longer exposures for specimens with increasing content of PVDF. However, the degree of hardening decreases with the time of exposure in the respective environments. In general, acetone and toluene impart surface hardening, whereas, xylene and benzene soften the specimen. PMMA: PVDF (83 : 17) blend exhibits surface hardening under all the four treatments when compared with the respective untreated specimens.

  8. Utilisation of sinter-hardening treatment for various sintered steels

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2007-10-01

    Full Text Available Purpose: Purpose of this paper was to present the benefits of powder metallurgy technology and development of sinter-hardening process applied to different steels including pre-alloyed Ni-Mo steels with W addition, Astaloy CrM and experimental sintered duplex stainless steels. The mechanical properties, focusing in particular on hardness and wear resistance, of two different sinter-hardened steels were described. Microstructure characteristic of produced sinter-hardened steels was taken under consideration.Design/methodology/approach: Different compositions have been tested in order to investigate the influence of sinter-hardening of steels under different cooling rates on microstructure and properties. As a first group of materials Ni-Mo pre-alloyed steel powders were used, differing with the addition of tungsten and amount of carbon. Green compacts were sintered at the temperature 1120ºC for 1 hour. The next set of investigated materials was produced by mixing the Astaloy CrM powder with carbon amount of 0.6% and then compacted and sintered in the same conditions. Under sinter-hardened conditions, experimental sintered duplex stainless steels were also evaluated. After sintering, different cooling rates were applied.Findings: The applied sinter-hardening process resulted with achievement of material characterized by proper microstructure. The investigation of sinter-hardened steels proved that applied process of sintering under vacuum and rapid cooling brought expected outcome.Research limitations/implications: Considering the achieved outcome, it was revealed that chemical composition and applied process of steels preparation, sinter-hardening with rapid cooling, results in achievement of materials with relatively high apparent hardness and significant resistance to abrasion. Anyhow, further researches should be performed.Originality/value: The paper contributes to better understanding advantages of sinter-hardening process applicable to

  9. Properties of modified anhydride hardener and its cured resin

    Science.gov (United States)

    Qiang, Chen; Bingjun, Gao; Jinglin, Chen; Tongzhao, Xu

    2000-01-01

    Methyl-nadic-tetrahydric-methylanhydride (MNA), nadic-tetrahydric-methylanhydride (NA), anhydride hardener was modified by solid diol molecule to improve the impregnation resin fracture toughness in cryogenic temperature. The lap-shear strength, transverse tension as well as the thermal shock test showed that the resin cured by the modified anhydride hardener had higher bond strength and more toughness at 77 K. After the experiment of vacuum pressure impregnation (VPI) processing, it was found that this resin had a longer usable life, better impregnating properties, but higher initial viscosity than the resin hybrid HY925 as hardener.

  10. Strain hardening of metal parts with use of impulse wave

    Science.gov (United States)

    Kirichek, A. V.; Soloviev, D. L.

    2016-04-01

    This work describes a strain hardening method with the use of impulse waves. This method increases energy transfer to the strained material extending its technological capabilities with development of a deep strengthened layer and allowing formation of a heterogeneous hardened structure using plastic deformation. This structure has specified distribution of the hard and soft (visco-plastic) areas. Due to development of the heterogeneous structure in the surface layer created by strain hardening with impulse wave, durability of parts that suffer contact fatigue loading is significantly increased.

  11. Processing, Microstructures and Properties of a Dual Phase Precipitation-Hardening PM Stainless Steel

    Science.gov (United States)

    Schade, Christopher

    To improve the mechanical properties of PM stainless steels in comparison with their wrought counterparts, a PM stainless steel alloy was developed which combines a dual-phase microstructure with precipitation-hardening. The use of a mixed microstructure of martensite and ferrite results in an alloy with a combination of the optimum properties of each phase, namely strength and ductility. The use of precipitation hardening via the addition of copper results in additional strength and hardness. A range of compositions was studied in combination with various sintering conditions to determine the optimal thermal processing to achieve the desired microstructure. The microstructure could be varied from predominately ferrite to one containing a high percentage of martensite by additions of copper and a variation of the sintering temperature before rapid cooling. Mechanical properties (transverse rupture strength (TRS), yield strength, tensile strength, ductility and impact toughness) were measured as a function of the v/o ferrite in the microstructure. A dual phase alloy with the optimal combination of properties served as the base for introducing precipitation hardening. Copper was added to the base alloy at various levels and its effect on the microstructure and mechanical properties was quantified. Processing at various sintering temperatures led to a range of microstructures; dilatometry was used utilized to monitor and understand the transformations and the formation of the two phases. The aging process was studied as a function of temperature and time by measuring TRS, yield strength, tensile strength, ductility, impact toughness and apparent hardness. It was determined that optimum aging was achieved at 538°C for 1h. Aging at slightly lower temperatures led to the formation of carbides, which contributed to reduced hardness and tensile strength. As expected, at the peak aging temperature, an increase in yield strength and ultimate tensile strength as well as

  12. Novel SEU hardened PD SOI SRAM cell

    Institute of Scientific and Technical Information of China (English)

    Xie Chengmin; Wang Zhongfang; Wang Xihu; Wu Longsheng; Liu Youbao

    2011-01-01

    A novel SEU hardened 10T PD SOI SRAM cell is proposed.By dividing each pull-up and pull-down transistor in the cross-coupled inverters into two cascaded transistors,this cell suppresses the parasitic BJT and source-drain penetration charge collection effect in PD SOl transistor which causes the SEU in PD SOI SRAM.Mixed-mode simulation shows that this novel cell completely solves the SEU,where the ion affects the single transistor.Through analysis of the upset mechanism of this novel cell,SEU performance is roughly equal to the multiple-cell upset performance of a normal 6T SOI SRAM and it is thought that the SEU performance is 17 times greater than traditional 6T SRAM in 45nm PD SOI technology node based on the tested data of the references.To achieve this,the new cell adds four transistors and has a 43.4% area overhead and performance penalty.

  13. Durability of High Performance Color Hardener

    Institute of Scientific and Technical Information of China (English)

    MA Bao-guo; DONG Rong-zhen; ZHU Hong-bo; ZHANG Li; JIAN Shou-wei

    2004-01-01

    The properties of high performance color hardener (HPCH) and the mechanism were studied.HPCH is a composite system, which is composed of cementitious and auxiliary cementing materials, composite additives, abrasion resistance component (aggregate) and pigment. The porosity and pore structure of the material are obviously improved due to the activation, filling and adsorption of auxiliary cementing materials, thus resulting in a great increase of binding capacity for ions in HPCH and the obstacles of ion migrating.The density of material structure, bonding capacity of cementitious material to the abrasion-resisting component and the corrosion resistance are greatly and effectively improved by adding the auxiliary cementing materials and compound additives. According to the tests of dry shrinkage, sulphate resistance, chloride permeability and Ca(OH)2 content distribution, the property superiority of HPCH is analyzed.The mechanism of materials modification of HPCH is explained from the microscopic point of view by testing the pore structure and pore distribution via the mercury intrusion pressure method.

  14. Radiation-hardened microwave communications system

    International Nuclear Information System (INIS)

    The consolidated fuel reprocessing program (CFRP) at the Oak Ridge National Laboratory (ORNL) has been developing signal transmission techniques and equipment to improve the efficiency of remote handling operations for nuclear applications. These efforts have been largely directed toward the goals of (a) remotely controlling bilateral force-reflecting servomanipulators for dexterous manipulation-based operations in remote maintenance tasks and (b) providing television viewing of the work site. In September 1987, developmental microwave transceiving hardware operating with dish antennas was demonstrated in the advanced integrated maintenance system (AIMS) facility at ORNL, successfully implementing both high-quality one-way television transmissions and simultaneous bidirectional digital control data transmissions with very low error rates. Initial test results based on digital transmission at a 1.0-Mbaud data rate indicated that the error rates of the microwave system were comparable to those of a hardwired system. During these test intervals, complex manipulator operations were performed, and the AIMS transporter was moved repeatedly without adverse effects on data integrity. Results of these tests have been factored into subsequent phases of the development program, with an ultimate goal of designing a fully radiation-hardened microwave signal transmission system for use in nuclear facilities

  15. Hardening in Two-Phase Materials. II. Plastic Strain and Mean Stress Hardening Rate

    DEFF Research Database (Denmark)

    Lilholt, Hans

    1977-01-01

    The strain parameters which are relevant in a tensile experiment, are analysed and related to the geometry of deformation and to the mean stress of two-phase materials. The hardening rate of the mean stress with respect to plastic strain is found to be useful in comparison between experiments and...... theories, and it allows theories to be probed over a range of strains. Previous experiments on the fibre-reinforced material of copper-tungsten are analysed in relation to the geometry of deformation....

  16. Radiation-chemical hardening of phenol-formaldehyde oligomers

    International Nuclear Information System (INIS)

    Radiation-chemical hardening of phenol formaldehyde oligomers of the resol type has been studied in the presence of furfural and diallylphthalate diluents. The samples have been hardened on an electron accelerator at an electron energy of 1.0-1.1 MeV and a dose rate of 2-3 Mrad/s. The kinetics of hardening has been studied on the yield of gel fraction within the range of absorbed doses from 7 to 400 Mrad. Radiation-chemical hardening of the studied compositions is activated with sensitizers, namely, amines, metal chlorides, and heterocyclic derivatives of metals. Furfural and diallylphthalate compositions are suitable for forming glass-fibre plastic items by the wet method and coatings under the action of ionizing radiations

  17. Properties of sodium silicate bonded sand hardened by microwave heating

    Institute of Scientific and Technical Information of China (English)

    Wang Jina; Fan Zitian; Zan Xiaolei; Pan Di

    2009-01-01

    The sodium silicate bonded sand hardened by microwave heating has many advantages,such as low sodium silicate adding quantity,fast hardening speed,high room temperature strength,good collapsibility and certain surface stability. However,it has big moisture absorbability in the air,which would lead to the compression strength and the surface stability of the sand molds being sharply reduced. In this study,the moisture absorbability of the sodium silicate bonded sand hardened by microwave heating in different humidity conditions and the effect factors were investigated. Meanwhile,the reasons for the big moisture absorbability of the sand were analyzed.Some measures to overcome the problems of high moisture absorbability,bad surface stability and sharply reducing strength in the air were discussed. The results of this study establish the foundation of green and clean foundry technology based on the microwave heating hardening sodium silicate sand process.

  18. Continual Induction Hardening of 3DSteel Bodies of Specific Geometries

    Czech Academy of Sciences Publication Activity Database

    Barglik, J.; Doležel, Ivo; Karban, P.

    2007-01-01

    Roč. 83, č. 3 (2007), s. 75-77. ISSN 0033-2097 Institutional research plan: CEZ:AV0Z20570509 Keywords : continual induction hardening * electromagnetic field * temperature field Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  19. Ultimate Bending Capacity of Strain Hardening Steel Pipes

    Institute of Scientific and Technical Information of China (English)

    陈严飞; 张娟; 张宏; 李昕; 周晶; 曹静

    2016-01-01

    Based on Hencky’s total strain theory of plasticity, ultimate bending capacity of steel pipes can be determined analytically assuming an elastic-linear strain hardening material, the simplified analytical solution is proposed as well. Good agreement is observed when ultimate bending capacities obtained from analytical solutions are compared with experimental results from full-size tests of steel pipes. Parametric study conducted as part of this paper indicates that the strain hardening effect has significant influence on the ultimate bending capacity of steel pipes. It is shown that pipe considering strain hardening yields higher bending capacity than that of pipe assumed as elastic-perfectly plastic material. Thus, the ignorance of strain hardening effect, as commonly assumed in current codes, may underestimate the ultimate bending capacity of steel pipes. The solutions proposed in this paper are applicable in the design of offshore/onshore steel pipes, supports of offshore platforms and other tubular structural steel members.

  20. Space Qualified, Radiation Hardened, Dense Monolithic Flash Memory Project

    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...

  1. Technologies Enabling Custom Radiation-Hardened Component Development Project

    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....

  2. Radiation Hardened Ethernet PHY and Switch Fabric Project

    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...

  3. General Friction Model Extended by the Effect of Strain Hardening

    DEFF Research Database (Denmark)

    Nielsen, Chris V.; Martins, Paulo A.F.; Bay, Niels

    2016-01-01

    An extension to the general friction model proposed by Wanheim and Bay [1] to include the effect of strain hardening is proposed. The friction model relates the friction stress to the fraction of real contact area by a friction factor under steady state sliding. The original model for the real......-ideally plastic material, and secondly, to extend the solution by the influence of material strain hardening. This corresponds to adding a new variable and, therefore, a new axis to the general friction model. The resulting model is presented in a combined function suitable for e.g. finite element modeling of...... friction in metal forming, where the material generally strain hardens. The extension of the model to cover strain hardening materials is validated by comparison to previously published experimental data....

  4. Space Qualified, Radiation Hardened, Dense Monolithic Flash Memory Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Space Micro proposes to build a radiation hardened by design (RHBD) flash memory, using a modified version of our RH-eDRAM Memory Controller to solve all the single...

  5. Investigation of fresh and hardened properties of Calcium sulfoaluminate (CSA cement blends

    Directory of Open Access Journals (Sweden)

    P. Herrmann

    2014-05-01

    Full Text Available Calcium sulfoaluminate (CSA is a comparatively new cementitious material that is mainly established in China where it is produced in a large scale. CSA cement is not covered by European standards. However, it provides different beneficial properties such as rapid hardening and high early strength development. Furthermore, the usage of CSA cement can save energy during production process in comparison to established cementitious materials. Therefore it is also more environmental friendly. Insufficient knowledge of this material behaviour restricts the possibilities and makes further research necessary. The research project applied a laboratory test program to elaborate the characterization of the materials. The obtained knowledge from these tests was then applied to further tests to determine application relevant key properties of CSA based pastes and mortars.The properties of pure CSA cement had been compared with the properties of CSA blends. The additions were PC, HAC, FA and GGBS with quantities of 10, 20 and 30%. The water to cement ratio was varying between 0.4, 0.5 and 0.6. General tests like fineness, XRD and XRF were used to define the present non-standardized material. Investigation of fresh pastes included measurement of setting time and calorimetry. Hardened mortar specimens of different ages were examined for compressive strength. The results showed that CSA itself hardens very rapidly and gives an early strength development. Possible ways of utilization of CSA based mortars and concretes were also emphasized in the paper.

  6. Deformation hardening of type 304 stainless steel at elevated temperature

    International Nuclear Information System (INIS)

    Samples of Type 304 SS were hardened by various deformation paths. The mechanical behavior of these predeformed samples was characterized by their behavior in tensile tests. Dislocation structure was examined by TEM. Behavior during the prior deformation hardening path was analyzed for indications that the state of the material was changing. Results support the conclusion that more than one state parameter is required to characterize the material

  7. Micromilling of hardened tool steel for mould making applications

    DEFF Research Database (Denmark)

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

    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....

  8. Prediction Of Mechanical Properties Of Quench Hardening Steel*

    OpenAIRE

    Chotěborský R.; Linda M.

    2015-01-01

    The present study investigated the application of finite element method for prediction of mechanical properties of quench hardening steel. Based on the experimental results obtained, a numerical model for simulation of continuous cooling of quench hardening steel was developed. For the simulation of the kinetics of diffusion phase transformations, the Avrami equation and additive rule were applied. A new model was also developed for martensitic transformation which was validated using metallo...

  9. Iterative Beam Hardening Correction for Multi-Material Objects

    OpenAIRE

    Zhao, Yunsong; Li, MengFei

    2015-01-01

    In this paper, we propose an iterative beam hardening correction method that is applicable for the case with multiple materials. By assuming that the materials composing scanned object are known and that they are distinguishable by their linear attenuation coefficients at some given energy, the beam hardening correction problem is converted into a nonlinear system problem, which is then solved iteratively. The reconstructed image is the distribution of linear attenuation coefficient of the sc...

  10. Aided Design Elements of Induction Heating Process for Hardening

    OpenAIRE

    BURCA Adrian; Stanciu, Bogdan; MICH-VANCEA Claudiu

    2012-01-01

    The context of sustainable economic development, with high efficiency and low consumption of materials and energy, respectively the need for automatic control, determines the intense use of inductive heating devices in hardening processes. This paper presents a simulation of an installation of superficial heating treatment (hardening), performed with the help of the commercial software ELTA 1D, produced for inductive heating process. It highlights the links between different feeding electric ...

  11. DMILL circuits. The hardened electronics decuples its performances

    International Nuclear Information System (INIS)

    Thanks to the DMILL (mixed logic-linear hardening) technology under development at the CEA, MHS, a French company specialized in the fabrication of integrated circuits now produces hardened electronic circuits ten times more resistant to radiations than its competitors. Outside the initial market (several thousands of circuits for the LHC particle accelerator of Geneva), a broad choice of applications is opened to this technology: national defense, space, civil nuclear and medical engineering, and high temperature applications. Short paper. (J.S.)

  12. Reappraisal of the work hardening behavior of bulk amorphous matrix composites

    International Nuclear Information System (INIS)

    This paper investigates the origin of work hardening in amorphous composites by directly measuring the hardness variations of crystalline particles and amorphous matrices at various strains. The work hardening of the amorphous composites was caused predominantly by hardening of the amorphous matrices, rather than of the crystalline particles. The hardening mechanism was explained based on the kinetics and thermodynamics.

  13. Radiation-hardened bulk Si-gate CMOS microprocessor family

    International Nuclear Information System (INIS)

    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 106 rads (Si) and transient upset hardness of 5 x 108 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 C2L 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

  14. Zinc coated sheet steel for press hardening

    Science.gov (United States)

    Ghanbari, Zahra N.

    Galvanized steels are of interest to enhance corrosion resistance of press-hardened steels, but concerns related to liquid metal embrittlement have been raised. The objective of this study was to assess the soak time and temperature conditions relevant to the hot-stamping process during which Zn penetration did or did not occur in galvanized 22MnB5 press-hardening steel. A GleebleRTM 3500 was used to heat treat samples using hold times and temperatures similar to those used in industrial hot-stamping. Deformation at both elevated temperature and room temperature were conducted to assess the coating and substrate behavior related to forming (at high temperature) and service (at room temperature). The extent of alloying between the coating and substrate was assessed on undeformed samples heat treated under similar conditions to the deformed samples. The coating transitioned from an α + Gamma1 composition to an α (bcc Fe-Zn) phase with increased soak time. This transition likely corresponded to a decrease in availability of Zn-rich liquid in the coating during elevated temperature deformation. Penetration of Zn into the substrate sheet in the undeformed condition was not observed for any of the processing conditions examined. The number and depth of cracks in the coating and substrate steel was also measured in the hot-ductility samples. The number of cracks appeared to increase, while the depth of cracks appeared to decrease, with increasing soak time and increasing soak temperature. The crack depth appeared to be minimized in the sample soaked at the highest soak temperature (900 °C) for intermediate and extended soak times (300 s or 600 s). Zn penetration into the substrate steel was observed in the hot-ductility samples soaked at each hold temperature for the shortest soak time (10 s) before being deformed at elevated temperature. Reduction of area and elongation measurements showed that the coated sample soaked at the highest temperature and longest soak time

  15. Intrinsic surface hardening and precipitation kinetics of Al0.3CrFe1.5MnNi0.5 multi-component alloy

    International Nuclear Information System (INIS)

    Highlights: ► Al0.3CrFe1.5MnNi0.5 multi-component alloy with surface hardening was developed. ► By simple aging treatments, the surface hardness was markedly enhanced. ► Wear resistance was efficiently improved, and fracture toughness retained. ► The intrinsic surface hardening behaves similar to short-range decomposition. ► The intrinsic surface hardening has relatively low heterogeneous nucleation energy. - Abstract: An Al0.3CrFe1.5MnNi0.5 multi-component alloy with a very effective surface hardening ability attributed to intrinsic ρ phase precipitation and applicable to complex tool components was developed. Under a conventional aging treatment in a normal atmosphere at 550 °C for 2 h, the alloy with the surface precipitation hardening layer of 74 μm thick exhibited markedly enhanced surface hardness from HV 338 to HV 840 and efficiently improved wear resistance to 1.4 times the values of SUJ2 and SKD61 steels, while high fracture toughness close to that of ductile SKD61 steel was effectively retained. Precipitation thermodynamics and growth kinetics of the surface hardening layer were also investigated. The growth of the surface hardening layer was much faster than that of the precipitation in the bulk matrix; it did not follow typical long-distance diffusion kinetics but behaves more similar to a self-induced or reaction-accelerated short-range decomposition with a thickness increase proportional to the cube of aging time. On the surface, a lower heterogeneous nucleation energy and a reduced strain energy (total 55 kJ/mol) than the regular nucleation energy in the bulk matrix (78 kJ/mol) dominated the rapid formation and growth of the intrinsic surface precipitation with significant strain relaxations.

  16. Comparison of different techniques of laser surface hardening

    Directory of Open Access Journals (Sweden)

    J. Grum

    2007-09-01

    Full Text Available Purpose: The paper gives a comparison of various techniques of laser surface hardening for various kinds of structural and tool steels, and special maraging steel and hardening of nodular graphite and gray cast irons.Design/methodology/approach: Experimental investigations of laser surface transformation hardening, laser remelting and laser shock processing were performed. Trials of laser hardening were carried out under different conditions, with different modes of laser guidance over the specimen surfaces, and with different degrees of path overlapping. Different kinds of absorbents, were tested, the depths of hardened paths or layers were measured, profiles of hardness and residual stresses were measured, the microstructures formed were analysed, and a micro-chemical analysis was made.Findings: The investigations showed that under different laser-hardening conditions quite different surface-layer properties are obtained. A very strong connection of the chosen energy input, the type of absorbent used, the degree of overlapping, and the mode of laser-beam guidance with the depth of the hardened path or layer, and the through-depth profiles of microhardness and residual stresses of the hardened path or layer was found.Research limitations/implications: He industrial requirements for the achievement of appropriate properties of surface layers, with special regard to the hardened-layer depth, and appropriate variations of microhardness and residual stresses are more and more frequent. The residual-stress profiles should have high compressive stresses at the surface and a small gradient of the residual stresses in the subsurface of the hardened layer. In this way high fatigue resistance of a material can be ensured and occurrence and propagation of cracks prevented. These findings offer engineers new concepts in the improvement of surfaces of machine and tool parts.Practical implications: With the present findings constructors and experts in laser

  17. Process design of press hardening with gradient material property influence

    Science.gov (United States)

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

    2011-05-01

    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.

  18. Process design of press hardening with gradient material property influence

    International Nuclear Information System (INIS)

    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.

  19. Reverse-Martensitic Hardening of Austenitic Stainless Steel upon Up-quenching

    Science.gov (United States)

    Sato, Kiminori; Guo, Defeng; Li, Xiaohong; Zhang, Xiangyi

    2016-08-01

    Reverse-martensitic transformation utilizing up-quenching was demonstrated for austenitic stainless steel. Up-quenching was done following the stress-induced phase modification to martensite and then enrichment of the body-centered-cubic ferrite. Transmission-electron-microscopy observation and Vickers hardness test revealed that the reverse-martensitic transformation yields quench hardening owing to an introduction of highly-concentrated dislocation. It is furthermore found that Cr precipitation on grain boundaries caused by isothermal aging is largely suppressed in the present approach.

  20. Precipitation mechanisms and subsequent hardening kinetics in the β-CEZ alloy

    OpenAIRE

    Combres, Y.; Bechet, J.; Vassel, A.

    1993-01-01

    The β-CEZ alloy : Ti-5%Al-2%Sn-4%Zr-4%Mo-2%Cr-l%Fe is a near β titanium alloy. Since its processing routes include heat treatment (consisting of solution treatment and ageing), it has been decided to study the influence of the β phase stability on α phase precipitation and hardening kinetics. Small sized specimens, coming from industrial heats, have been heat treated above and below the β transus, and then water quenched. Therefore, several degree of β stability are obtained. When it is incre...

  1. Influence of Precipitation Hardening in Mg-Y-Nd on Mechanical and Corrosion Properties

    Science.gov (United States)

    Maier, P.; Peters, R.; Mendis, C. L.; Müller, S.; Hort, N.

    2016-04-01

    Precipitation hardening is an effective strengthening mechanism to achieve high strength at moderate ductility in Mg-RE alloys. However, improved mechanical properties by precipitates that strengthen the alloy can affect corrosion rates as the finely dispersed particles are often more noble than the matrix. Biodegradable implant material should show a certain corrosion rate, but should be free of pitting, because wide and deep pits are notches that can cause higher stress concentration. WE43 has generally shown an acceptable biological response. In this study, a Mg-Y-Nd-Gd-Dy (WE32) alloy in extruded, solution and precipitation heat-treated conditions has been investigated. Solution heat treatment causes grain growth and strength loss. A rather short ageing response to peak hardness was observed, where peak hardening causes hardness values to exceed that of the initial extruded condition. Grain growth during ageing is not significant. Corrosion was evaluated with potentiodynamic polarization in Ringer Acetate solution. The highest corrosion rate was observed in the T4 condition. The peak aged alloy showed the most homogenous form of corrosion.

  2. Influence of Hardening Model on Weld Residual Stress Distribution

    International Nuclear Information System (INIS)

    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

  3. Cryptographic Path Hardening: Hiding Vulnerabilities in Software through Cryptography

    CERN Document Server

    Ganesh, Vijay; Rinard, Martin

    2012-01-01

    We propose a novel approach to improving software security called Cryptographic Path Hardening, which is aimed at hiding security vulnerabilities in software from attackers through the use of provably secure and obfuscated cryptographic devices to harden paths in programs. By "harden" we mean that certain error-checking if-conditionals in a given program P are replaced by equivalent" we mean that adversaries cannot use semi-automatic program analysis techniques to reason about the hardened program paths and thus cannot discover as-yet-unknown errors along those paths, except perhaps through black-box dictionary attacks or random testing (which we can never prevent). Other than these unpreventable attack methods, we can make program analysis aimed at error-finding "provably hard" for a resource-bounded attacker, in the same sense that cryptographic schemes are hard to break. Unlike security-through-obscurity, in Cryptographic Path Hardening we use provably-secure crypto devices to hide errors and our mathemati...

  4. General analytical shakedown solution for structures with kinematic hardening materials

    Science.gov (United States)

    Guo, Baofeng; Zou, Zongyuan; Jin, Miao

    2016-04-01

    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.

  5. Irradiation-induced creep and microstructural development in precipitation-hardened nickel-aluminium alloys

    International Nuclear Information System (INIS)

    Irradiation-induced creep in solid-solution Ni-8.5 at% AL and precipitation-hardened Ni-13.1 at% Al alloys was studied by bombarding miniaturized specimens with 6.2 MeV protons at 3000C under different tensile stresses. After irradiation transmission electron microscopic (TEM) investigations were made to observe the precipitate structure under irradiation for different experimental parameters. Moreover, the irradiation-induced changes in precipitate structure and changes of Al-concentrations in the matrix in Ni-13.1 at% Al alloys were studied by electrical resistivity measurements during irradiation. For comparison, the electrical resistivity of unirradiated specimens was also measured after thermal aging for different times. For correlation, TEM analysis was performed on irradiated and unirradiated aged specimens. Tensile tests on annealed and aged Ni-Al alloys were also done at various temperatures. (orig./RK)

  6. Stress field near an interface edge of linear hardening materials

    Institute of Scientific and Technical Information of China (English)

    许金泉; 付列东

    2002-01-01

    The elastic-plastic singular stress field near an interface edge of bounded linear hardening material is substantially as same as that of bonded elastic materials whose Young' s modulus and Poisson ratio are substituted by equivalent values, respectively. Further investigation by the elasto-plastic boundary element method (BEM) on the stress field near the interface edge showed that the stress field there can be divided into three regions: the domain region of the elastic-plastic singular stress field, the transitional region and the elastic region. The domain region of the elastic-plastic singular stress becomes larger with the increasing of the linear hardening coefficient. When the linear hardening coefficient decreases to a certain value, the effective stress in most of the yield zone equals approximately the yield stress. The stress distribution in the elastic region under small-scale yielding condition was also investigated.

  7. Stress field near an interface edge of linear hardening materials

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The elastic-plastic singular stress field near an interface edge of bounded linear hardening material is substantially as same as that of bonded elastic materials whose Young's modulus and Poisson ratio are substituted by equivalent values, respectively. Further investigation by the elasto-plastic boundary element method (BEM) on the stress field near the interface edge showed that the stress field there can be divided into three regions: the domain region of the elastic-plastic singular stress field, the transitional region and the elastic region. The domain region of the elastic-plastic singular stress becomes larger with the increasing of the linear hardening coefficient. When the linear hardening coefficient decreases to a certain value, the effective stress in most of the yield zone equals approximately the yield stress. The stress distribution in the elastic region under small-scale yielding condition was also investigated.

  8. 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.

  9. Engineering design guidelines for electromagnetic pulse hardening of naval equipment

    Science.gov (United States)

    Rogers, S. R.; Perala, R. A.; Rosich, R. K.; Cook, R. B.; Rudolph, T. H.

    1981-07-01

    This document is intended to be used by engineers who design and manufacture shipboard equipment. It is complete in the sense that both the EMP hazard and the means of mitigating the hazard (hardening) are presented. The hazard is described, which not only discusses EMP generation in a general sense, but it also presents specific threat levels for EMP fields and transient currents and voltages included on cables and antennas which are connected to electronic equipment. This specific threat constitutes an EMP survivability criteria which must be met by the mission critical equipment. The necessary hardening technology areas include volume shielding, cable shielding and connectors, interface susceptibility analysis, terminal protective devices, upset and upset hardening, common mode rejection techniques, optical isolation, and grounding/bonding techniques. Test techniques which can verify equipment hardness are presented along with methods to observe the equipment's hardness and maintain the hardness.

  10. 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

  11. Temperature influence on water transport in hardened cement pastes

    International Nuclear Information System (INIS)

    Describing water transport in concrete is an important issue for the durability assessment of radioactive waste management reinforced concrete structures. Due to the waste thermal output such structures would be submitted to moderate temperatures (up to 80 °C). We have then studied the influence of temperature on water transport within hardened cement pastes of four different formulations. Using a simplified approach (describing only the permeation of liquid water) we characterized the properties needed to describe water transport (up to 80 °C) using dedicated experiments. For each hardened cement paste the results are presented and discussed

  12. Impact of Scaled Technology on Radiation Testing and Hardening

    Science.gov (United States)

    LaBel, Kenneth A.; Cohn, Lewis M.

    2005-01-01

    This presentation gives a brief overview of some of the radiation challenges facing emerging scaled digital technologies with implications on using consumer grade electronics and next generation hardening schemes. Commercial semiconductor manufacturers are recognizing some of these issues as issues for terrestrial performance. Looking at means of dealing with soft errors. The thinned oxide has indicated improved TID tolerance of commercial products hardened by "serendipity" which does not guarantee hardness or say if the trend will continue. This presentation also focuses one reliability implications of thinned oxides.

  13. Temperature influence on water transport in hardened cement pastes

    Energy Technology Data Exchange (ETDEWEB)

    Drouet, Emeline [CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, F-91191 Gif sur Yvette Cedex (France); Poyet, Stéphane, E-mail: stephane.poyet@cea.fr [CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, F-91191 Gif sur Yvette Cedex (France); Torrenti, Jean-Michel [Université Paris-Est, IFSTTAR, Département Matériaux & Structures, 14-52 boulevard Newton, F-77447 Marne la Vallée cedex 2 (France)

    2015-10-15

    Describing water transport in concrete is an important issue for the durability assessment of radioactive waste management reinforced concrete structures. Due to the waste thermal output such structures would be submitted to moderate temperatures (up to 80 °C). We have then studied the influence of temperature on water transport within hardened cement pastes of four different formulations. Using a simplified approach (describing only the permeation of liquid water) we characterized the properties needed to describe water transport (up to 80 °C) using dedicated experiments. For each hardened cement paste the results are presented and discussed.

  14. 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.

  15. Why semiconductors must be hardened when used in space

    International Nuclear Information System (INIS)

    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

  16. Ballistic Perforation of Surface Hardened Mild Steel Plates

    OpenAIRE

    Thorsen, Henrik; Orthe, Erlend

    2014-01-01

    The main objective with this thesis was to investigate experimentally and numerically the effect surface hardening has on the ballistic properties of monolithic and laminated mild steel plates. 300x300 mm^2 plates of thicknesses 12 mm, 6 mm, and 4 mm were made from a low carbon structural steel (NVE36) and combined in such a way that the total thickness always was 12 mm. Some of the plates were then surface hardened by the Kverneland Group to obtain different hardness profiles; (1) as-receive...

  17. Influence of yttrium content on phase formation and strain hardening behavior of Mg–Zn–Mn magnesium alloy

    International Nuclear Information System (INIS)

    Highlights: • Addition of Y element significantly refines the grains of ZM31 magnesium alloy. • I- and W-phases are present in the extruded alloy ZM31 with low Y additions. • X-phase and Mg24Y5 are observed in the extruded alloy ZM31 with a 6% Y addition. • While I- and W-phases are dissolved after heat treatment, LPSO X-phase remains. • I- and X-phases increase compressive yield strength and hardness of the alloy. - Abstract: The aim of this study was to identify the effect of yttrium (Y) addition on the phase development and strain hardening behavior of an extruded Mg–Zn–Mn (ZM31) magnesium alloy. The addition of a small amount (0.3 wt.%) of Y in the alloy led to the formation of icosahedral quasicrystalline I (Mg3YZn6) phase. Both I-phase and W-phase (Mg3Y2Zn3) were present in the extruded ZM31+3.2Y alloy, while long period stacking ordered (LPSO) X-phase (Mg12YZn) and Mg24Y5 were observed in the extruded ZM31+6Y alloy. The Y addition significantly refined grains in the extruded state. The presence of I-phase in the extruded ZM31+0.3Y alloy increased hardness, compressive yield strength, and Stage B strain hardening rate. The extruded ZM31+3.2Y alloy exhibited a lower hardness and Stage B hardening rate due to the formation of W-phase. Both extruded ZM31+0.3Y and ZM31+3.2Y alloys showed a yield point phenomenon with an initial negative strain hardening rate. The extruded ZM31+6Y alloy had a high hardness and compressive yield strength without Stage B hardening, suggesting a change of major deformation mode from twinning to slip mainly due to the role of LPSO X-phase. After solution treatment and aging, the hardness and compressive yield strength gradually increased with increasing Y content, while the strain hardening exponent and the extent of Stage B strain hardening decreased due to the dissolution of I- and W-phases and the presence of LPSO X-phase

  18. The effects of Si on the mechanical twinning and strain hardening of Fe–18Mn–0.6C twinning-induced plasticity steel

    International Nuclear Information System (INIS)

    The stacking-fault energy (SFE), dislocation slip, mechanical twinning, strain hardening, and yield and tensile strengths were systemically investigated in Fe–18Mn–0.6C–1.5Si twinning-induced plasticity (TWIP) steel. The results were also compared with those for Fe–18Mn–0.6C and Fe–18Mn–0.6C–1.5Al TWIP steels. The SFE decreased by 4 mJ m−2 per 1 wt.% Si. The addition of Si increased both the yield strength, due mainly to solid solution hardening, and the tensile strength, owing to the high strain hardening that occurred while maintaining a large elongation of over 60%. To examine this high strain hardening, especially at low strains, the volume fractions of the primary and secondary mechanical twins were quantitatively evaluated by combining the merits of electron backscattered diffractometry and transmission electron microscopy. The volume fractions of both the primary and secondary twins were the highest in the Fe–18Mn–0.6C–1.5Si TWIP steel, which had the lowest SFE of the three TWIP steels. In particular, the volume fraction of the secondary mechanical twins increased rapidly with the addition of Si. The contributions of dislocation storage, mechanical twinning and dynamic strain aging (DSA) to the strain hardening were also quantitatively evaluated in the three TWIP steels. The Si-added TWIP steel had the highest strain hardening, due mainly to the active primary and secondary twinning, and experienced negligible DSA. In contrast, the Al-added TWIP steel exhibited the lowest strain hardening due to the reductions in both the mechanical twinning and DSA

  19. Hardening digital systems with distributed functionality: robust networks

    Science.gov (United States)

    Vaskova, Anna; Portela-Garcia, Marta; Garcia-Valderas, Mario; López-Ongil, Celia; Portilla, Jorge; Valverde, Juan; de la Torre, Eduardo; Riesgo, Teresa

    2013-05-01

    Collaborative hardening and hardware redundancy are nowadays the most interesting solutions in terms of fault tolerance achieved and low extra cost imposed to the project budget. Thanks to the powerful and cheap digital devices that are available in the market, extra processing capabilities can be used for redundant tasks, not only in early data processing (sensed data) but also in routing and interfacing1

  20. Continual Induction Hardening of Axi-Symmetric Bodies

    Czech Academy of Sciences Publication Activity Database

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

    2005-01-01

    Roč. 161, - (2005), s. 269-275. ISSN 0924-0136 R&D Projects: GA MŠk(CZ) LN00B084 Institutional research plan: CEZ:AV0Z20570509 Keywords : continual induction hardening * induction heating * electromagnetic field Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.592, year: 2005

  1. Deformation hardening of Type 304 stainless steel at elevated temperature

    International Nuclear Information System (INIS)

    The dislocation hardening produced in Type 304 stainless steel by various combinations of cyclic and monotonic straining at elevated temperatures has been studied by mechanical testing and microscopic examination. Cycling between symmetric stress limits such that no net strain accumulation occurs, produces a well defined cellular dislocation structure. However, tensile tests on cyclically hardened samples show that their stress-strain behavior is negligibly different from that of samples subjected to simple monotonic prestrain and which contain only a loosely tangled dislocation structure. Cycling between asymmetric stress limits such that there is a small tensile mean stress, causes the sample to elongate slightly on each cycle. The net strain accumulated on each cycle of such a test is of the order of 0.1 to 1% of the plastic strain amplitude, and net tensile strains as large as 40% can be achieved after several thousand cycles. Tensile tests on such cyclically crept samples show that the strain accumulated during the cyclic stressing, has produced very little work hardening as measured by the initial flow stress, but that the work-hardening rate throughout a subsequent tensile test at a given flow stress is greater than would be expected in a sample deformed only monotonically. (author)

  2. Radiogram enhancement and linearization using the beam hardening correction method

    Czech Academy of Sciences Publication Activity Database

    Vavřík, Daniel; Jakůbek, J.

    2009-01-01

    Roč. 607, - (2009), s. 212-214. ISSN 0168-9002. [International Workshop on Radiation Imaging Detectors. Helsinky, 29.06.2008-03.07.2008] Institutional research plan: CEZ:AV0Z20710524 Keywords : beam hardening correction * flat-field correction * digital radiography Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 1.317, year: 2009

  3. Increasing the hardness of tool steels by plasma hardening

    International Nuclear Information System (INIS)

    In this work, investigations were carried out into the structure, hardness, cracking resistance parameters (impact toughness, dynamic stress intensity factor Kld) and the nature of failure in dynamic loading 75Kh2MF steel in combined induction-plasma hardening and the results were compared with HF quenching and plasma treatment in the initial (normalised) condition

  4. Case Depth Measurement of Induction Hardening Using Image Processing

    Institute of Scientific and Technical Information of China (English)

    Kitti Pongsathaporn; Pramuk Jenkittiyon; Siriporn Daopiset; Somnuk Watanasriyakul

    2004-01-01

    Case depth measurement of the induction hardened steel parts is necessary for quality control. Vickers microhardness test is the most industrially accepted method to identify the case depth. But this method is a time consuming one and it requires expensive equipment. The aim of this study is to develop a different method to determine the case depth using image processing. The surface hardened steel samples were cross cut, ground and etched with Nital. The etched macrosectioned specimens were scanned by a scanner. The scanned images were evaluated by the developed software. The principle of the software is to identify the gray level difference. The effective case depths of the surface hardened specimens obtained by Vickers microhardness test and the developed method were compared. It was found that the deviation of the developed method was ±0.12 mm at the case depth range of 0.6 - 2.0 mm and ±0.14 mm at the case depth range of 2.1 - 4.3 mm. The measuring time was only 20% of Vickers microhardness test. The deviation range is much lower than the tolerance case depth specification for induction hardening in general.

  5. Iterative Beam Hardening Correction for Multi-Material Objects.

    Science.gov (United States)

    Zhao, Yunsong; Li, Mengfei

    2015-01-01

    In this paper, we propose an iterative beam hardening correction method that is applicable for the case with multiple materials. By assuming that the materials composing scanned object are known and that they are distinguishable by their linear attenuation coefficients at some given energy, the beam hardening correction problem is converted into a nonlinear system problem, which is then solved iteratively. The reconstructed image is the distribution of linear attenuation coefficient of the scanned object at a given energy. So there are no beam hardening artifacts in the image theoretically. The proposed iterative scheme combines an accurate polychromatic forward projection with a linearized backprojection. Both forward projection and backprojection have high degree of parallelism, and are suitable for acceleration on parallel systems. Numerical experiments with both simulated data and real data verifies the validity of the proposed method. The beam hardening artifacts are alleviated effectively. In addition, the proposed method has a good tolerance on the error of the estimated x-ray spectrum. PMID:26659554

  6. Beam hardening correction for sparse-view CT reconstruction

    Science.gov (United States)

    Liu, Wenlei; Rong, Junyan; Gao, Peng; Liao, Qimei; Lu, HongBing

    2015-03-01

    Beam hardening, which is caused by spectrum polychromatism of the X-ray beam, may result in various artifacts in the reconstructed image and degrade image quality. The artifacts would be further aggravated for the sparse-view reconstruction due to insufficient sampling data. Considering the advantages of the total-variation (TV) minimization in CT reconstruction with sparse-view data, in this paper, we propose a beam hardening correction method for sparse-view CT reconstruction based on Brabant's modeling. In this correction model for beam hardening, the attenuation coefficient of each voxel at the effective energy is modeled and estimated linearly, and can be applied in an iterative framework, such as simultaneous algebraic reconstruction technique (SART). By integrating the correction model into the forward projector of the algebraic reconstruction technique (ART), the TV minimization can recover images when only a limited number of projections are available. The proposed method does not need prior information about the beam spectrum. Preliminary validation using Monte Carlo simulations indicates that the proposed method can provide better reconstructed images from sparse-view projection data, with effective suppression of artifacts caused by beam hardening. With appropriate modeling of other degrading effects such as photon scattering, the proposed framework may provide a new way for low-dose CT imaging.

  7. Copper-based dispersion hardened materials obtained by extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Agbalyan, S.A.; Martirosyan, N.S.; Arutyunyan, A.S. [and others

    1994-07-01

    Using the results of differential thermal analysis, the sintering parameters and extrusion temperatures for the fabrication of Cu-Cr-Zn-TiC powder alloys were determined. The optimal compositions, and techniques for their production were identified. Industrial tests of electrodes prepared by extrusion of the dispersion hardened materials showed that their durability is 3-5 times greater than that of standard electrodes.

  8. 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 ostatní: -(PL) 7T08603716 Keywords : induction heating * induction hardening * numerical solution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  9. Selection method of steel grade with required hardenability

    Directory of Open Access Journals (Sweden)

    J. Trzaska

    2006-04-01

    Full Text Available Purpose: The purpose of this paper is to work out the computer aided method for selecting grades of steel with a required hardenability.Design/methodology/approach: The purpose has been achieved in two stages. In the first stage a neural network model for calculating the Jominy curve on the basis of the chemical composition has been worked out. This model made possible to prepare, in the second stage, a representative set of data and to work out the neural classifier that would aid the selection of steel grade with the required hardenability.Findings: The calculations made in the paper have confirmed the purposefulness of applying artificial neural networks for aiding the selection of steel with the required hardenability.Research limitations/implications: The presented system may be used in the range of the accepted in the paper mass concentrations of elements. The methodology demonstrated in the paper makes it possible to add new grades of steel to the system.Practical implications: The worked out model may be used in computer systems of steel selection for the parts of machines exposed to the heat treatment.Originality/value: The use of the artificial neural networks as an aiding tool for selecting the steel with the required hardenability.

  10. Influence of impact energy on work hardening ability of austenitic manganese steel and its mechanism

    Directory of Open Access Journals (Sweden)

    Li Xiaoyun

    2012-08-01

    Full Text Available To further understand the hardening mechanism of austenitic manganese steel under actual working conditions, the work hardening ability was studied and the microstructures of austenitic manganese steel were observed under different impact energies. The work hardening mechanism was also analyzed. The results show that the best strain hardening effect could be received only when the impact energy reaches or exceeds the critical impact energy. The microstructural observations reveal that dislocations, stacking faults and twins increase with raising impact energy of the tested specimens. The hardening mechanism changes at different hardening degrees. It is mainly dislocation and slip hardening below the critical impact energy, but it changes to the twinning hardening mechanism when the impact energy is above the critical impact energy.

  11. Corroding and Protecting of Surface Residual Stress With the Surface Hardening of Steel

    Institute of Scientific and Technical Information of China (English)

    ZOU Qing-hua

    2004-01-01

    The states of the stress with the surface hardening are analyzed, the related experiential formula of the stress -temperature and stress-depth hardened curves are set up, the protecting measures against hydrogen stress corrosion are discussed.

  12. Differential hardening in IF steel - Experimental results and a crystal plasticity based model

    NARCIS (Netherlands)

    Mulder, J.; Eyckens, P.; Boogaard, van den A.H.; Hora, P.

    2015-01-01

    Work hardening in metals is commonly described by isotropic hardening, especially for monotonically increasing proportional loading. The relation between different stress states in this case is determined by equivalent stress and strain definitions, based on equal plastic dissipation. However, exper

  13. Rapid cold hardening process of insects and its ecologically adaptive significance

    Institute of Scientific and Technical Information of China (English)

    WANG Xianhui; QI Xianlei; KANG Le

    2003-01-01

    In contrast to overwintering cold hardening, a rapid cold hardening process has recently been described in insects. This process can rapidly enhance cold tolerance of insects in several hours or even minutes. The characteristics of rapid cold hardening include inducing conditions, cold hardening effects, and fitness costs. Physiological and biochemical mechanisms of rapid cold hardening include rapid changes in the phospholipid composition and the increase in hemolymph osmolalities, polyols production, proline and cold-induced proteins. Moreover, there are different views about the ecologically adaptive significance of rapid cold hardening in insects. This paper reviews research results about rapid cold hardening of insects since 1987, focusing on forms of cold injury, strategies of cold tolerance, and definitions, characteristics, physiological and biochemical mechanisms and adaptive significance of rapid cold hardening.

  14. 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.

  15. Influence of impact energy on work hardening ability of austenitic manganese steel and its mechanism

    OpenAIRE

    Li Xiaoyun; Wu Wei; Zu Fangqiu

    2012-01-01

    To further understand the hardening mechanism of austenitic manganese steel under actual working conditions, the work hardening ability was studied and the microstructures of austenitic manganese steel were observed under different impact energies. The work hardening mechanism was also analyzed. The results show that the best strain hardening effect could be received only when the impact energy reaches or exceeds the critical impact energy. The microstructural observations reveal that disloca...

  16. Production and Precipitation Hardening of Beta-Type Ti-35Nb-10Cu Alloy Foam for Implant Applications

    Science.gov (United States)

    Mutlu, Ilven; Yeniyol, Sinem; Oktay, Enver

    2016-04-01

    In this study, beta-type Ti-35Nb-10Cu alloy foams were produced by powder metallurgy method for dental implant applications. 35% Nb was added to stabilize the beta-Ti phase with low Young's modulus. Cu addition enhanced sinterability and gave precipitation hardening capacity to the alloy. Sintered specimens were precipitation hardened in order to enhance the mechanical properties. Electrochemical corrosion behavior of the specimens was examined by electrochemical impedance spectroscopy in artificial saliva. Electrochemical impedance spectroscopy results indicated that the oxide film on the surface of foam is a bi-layer structure consisting of outer porous layer and inner barrier layer. Impedance values of barrier layer were higher than porous layer. Corrosion resistance of specimens decreased at high fluoride concentrations and at low pH of artificial saliva. Corrosion resistance of alloys was slightly decreased with aging. Mechanical properties, microstructure, and surface roughness of the specimens were also examined.

  17. Effect of Slag Content and Hardening Accelerator Dosage on the Physico Mechanical Properties of Cement and Concrete

    International Nuclear Information System (INIS)

    Our contribution consists at the study of the effect of (0 %, 0.2 % and 0.34 %) dosage of an hardening accelerating plasticizer (Plastocrete 160, produced by Sika Aldjazair) on the properties of normal mortar and concretes prepared with portland cement artificial of Hadjar Soud cement factory (Skikda - Algeria) with addition of (10 % and 20 %) of granulated blast furnace slag finely crushed of the El Hadjar blast furnace (Annaba - Algeria). The tests are focused to the physical and mechanical characteristics of elaborated materials to knowing: setting time, porosity, water absorption capacity and the test of compressive strength at 2, 7 and 28 days. The results obtained show clearly the reliability of the additive used to accelerate the hardening and to obtain high strengths at early age, which increase by increasing of the additive dosage. For the slag, its low hydraulic capacity does not make it profitable than at the long term (beyond 28 days). (author)

  18. Innovative Structural Materials and Sections with Strain Hardening Cementitious Composites

    Science.gov (United States)

    Dey, Vikram

    The motivation of this work is based on development of new construction products with strain hardening cementitious composites (SHCC) geared towards sustainable residential applications. The proposed research has three main objectives: automation of existing manufacturing systems for SHCC laminates; multi-level characterization of mechanical properties of fiber, matrix, interface and composites phases using servo-hydraulic and digital image correlation techniques. Structural behavior of these systems were predicted using ductility based design procedures using classical laminate theory and structural mechanics. SHCC sections are made up of thin sections of matrix with Portland cement based binder and fine aggregates impregnating continuous one-dimensional fibers in individual or bundle form or two/three dimensional woven, bonded or knitted textiles. Traditional fiber reinforced concrete (FRC) use random dispersed chopped fibers in the matrix at a low volume fractions, typically 1-2% to avoid to avoid fiber agglomeration and balling. In conventional FRC, fracture localization occurs immediately after the first crack, resulting in only minor improvement in toughness and tensile strength. However in SHCC systems, distribution of cracking throughout the specimen is facilitated by the fiber bridging mechanism. Influence of material properties of yarn, composition, geometry and weave patterns of textile in the behavior of laminated SHCC skin composites were investigated. Contribution of the cementitious matrix in the early age and long-term performance of laminated composites was studied with supplementary cementitious materials such as fly ash, silica fume, and wollastonite. A closed form model with classical laminate theory and ply discount method, coupled with a damage evolution model was utilized to simulate the non-linear tensile response of these composite materials. A constitutive material model developed earlier in the group was utilized to characterize and

  19. A study on the anneal hardening of the cold worked Al-Zr alloys

    International Nuclear Information System (INIS)

    Anneal hardening of the cold worked Al-Zr alloys have been studied in respect to its possible mechanisms. The hardening effects were due to the rearrangements of Zr atoms in solid solution to cause Cottrell effect or to form fine precipitates. The process variables of heat treatments, micro-structures and stacking fault density are examined to analyze the possible hardening mechanism. (author)

  20. On steel superficial hardening by concentrated electron beam in the air

    International Nuclear Information System (INIS)

    Possibilities of steel superficial hardening by a concentrated electron beam are studied. Experiments have been conducted since 1985 using the EhLV-6 accelerator with concentrated emission of the beam into atmosphere. Regimes ensuring the hardening and certain characteristic properties of the hardened layer are described

  1. The development of high strength corrosion resistant precipitation hardening cast steels

    Science.gov (United States)

    Abrahams, Rachel A.

    Precipitation Hardened Cast Stainless Steels (PHCSS) are a corrosion resistant class of materials which derive their properties from secondary aging after a normalizing heat treatment step. While PHCSS materials are available in austenitic and semi-austenitic forms, the martensitic PHCSS are most widely used due to a combination of high strength, good toughness, and corrosion resistance. If higher strength levels can be achieved in these alloys, these materials can be used as a lower-cost alternative to titanium for high specific strength applications where corrosion resistance is a factor. Although wrought precipitation hardened materials have been in use and specified for more than half a century, the specification and use of PHCSS has only been recent. The effects of composition and processing on performance have received little attention in the cast steel literature. The work presented in these investigations is concerned with the experimental study and modeling of microstructural development in cast martensitic precipitation hardened steels at high strength levels. Particular attention is focused on improving the performance of the high strength CB7Cu alloy by control of detrimental secondary phases, notably delta ferrite and retained austenite, which is detrimental to strength, but potentially beneficial in terms of fracture and impact toughness. The relationship between age processing and mechanical properties is also investigated, and a new age hardening model based on simultaneous precipitation hardening and tempering has been modified for use with these steels. Because the CB7Cu system has limited strength even with improved processing, a higher strength prototype Fe-Ni-Cr-Mo-Ti system has been designed and adapted for use in casting. This prototype is expected to develop high strengths matching or exceed that of cast Ti-6Al-4V alloys. Traditional multicomponent constitution phase diagrams widely used for phase estimation in conventional stainless steels

  2. Mechanical characteristics of hardened concrete with different mineral admixtures: a review.

    Science.gov (United States)

    Ayub, Tehmina; Khan, Sadaqat Ullah; Memon, Fareed Ahmed

    2014-01-01

    The available literature identifies that the addition of mineral admixture as partial replacement of cement improves the microstructure of the concrete (i.e., porosity and pore size distribution) as well as increasing the mechanical characteristics such as drying shrinkage and creep, compressive strength, tensile strength, flexural strength, and modulus of elasticity; however, no single document is available in which review and comparison of the influence of the addition of these mineral admixtures on the mechanical characteristics of the hardened pozzolanic concretes are presented. In this paper, based on the reported results in the literature, mechanical characteristics of hardened concrete partially containing mineral admixtures including fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBS), metakaolin (MK), and rice husk ash (RHA) are discussed and it is concluded that the content and particle size of mineral admixture are the parameters which significantly influence the mechanical properties of concrete. All mineral admixtures enhance the mechanical properties of concrete except FA and GGBS which do not show a significant effect on the strength of concrete at 28 days; however, gain in strength at later ages is considerable. Moreover, the comparison of the mechanical characteristics of different pozzolanic concretes suggests that RHA and SF are competitive. PMID:24688443

  3. 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.

  4. Microstructural variation of hardened cement-fly ash pastes leached by soft water

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The microstructural variations of hardened cement-fly ash pastes leached by soft water were investigated by MIP, XRD, TG and SEM. The results show that the mass of hardened cement-fly ash paste reduces and its microstructure deteriorates partly after leaching of soft water. At the leaching duration of 180 days, the hardened paste containing fly ash deteriorated a little more serious than the plain cement paste, but the incorporation of fly ash in a proper ratio was helpful to defer the trend of deterioration of the hardened paste microstructure. The microstructural stability of hardened cement-fly ash paste wasn’t damaged severely during the 180 days leaching duration.

  5. Aging Behavior of Al 6061 Alloy Processed by High-Pressure Torsion and Subsequent Aging

    Science.gov (United States)

    Mohamed, Intan Fadhlina; Lee, Seungwon; Edalati, Kaveh; Horita, Zenji; Hirosawa, Shoichi; Matsuda, Kenji; Terada, Daisuke

    2015-06-01

    A process to achieve strengthening in an Al 6061 alloy by grain refinement to ~200 nm using high-pressure torsion (HPT) and fine precipitation using aging treatment is studied. It is shown that although aging of the HPT-processed sample is effective for extra strengthening of the alloy, the imposed shear strain and the aging temperature should be selected carefully. The HPT processing after 5 turns leads high saturation hardness and tensile strength of 163 Hv and 470 MPa, respectively. The hardness at the saturation level remains the same during aging at 373 K (100 °C), while the hardness decreases by aging at 423 K (150 °C). When the disks are processed for 0.75 turns (lower shear strains) and aged at 373 K (100 °C), the hardness increases above the hardness level at the saturation because of the formation of B' and β' precipitates. Quantitative analyses indicate that three major hardening mechanisms contribute to the total hardening: grain boundary hardening through the Hall-Petch relationship, dislocation hardening through the Bailey-Hirsch relationship and precipitation hardening through the Orowan relationship. This study shows that the contribution of different strengthening mechanisms can be estimated using a linear additive relationship in ultrafine-grained aluminum alloys.

  6. CMOS inverter design-hardened to the total dose effect

    International Nuclear Information System (INIS)

    This paper reports and discusses the experimental behavior of two inverter structures Rad-Hardened by Design to 60Co irradiation. The authors use the results on a set of basic circuits and transistors exposed to the same total doses as these structures to establish the effective formation conditions of the parasitic channel. Then this leakage evolution is related to the gate voltage history under irradiation. Finally, they take advantage of this intrinsic degradation property to propose a new Design Rad Hardened (DRH) cell. This structure considerably limits the Low Noise Margin degradation, helps to maintain the logic functionality with a High Output level and improves both the rad-tolerance and the static power consumption

  7. Poromechanical behaviour of hardened cement paste under isotropic loading

    CERN Document Server

    Ghabezloo, Siavash; Guédon, Sylvine; Martineau, Francçois; Saint-Marc, Jérémie

    2008-01-01

    The poromechanical behaviour of hardened cement paste under isotropic loading is studied on the basis of an experimental testing program of drained, undrained and unjacketed compression tests. The macroscopic behaviour of the material is described in the framework of the mechanics of porous media. The poroelastic parameters of the material are determined and the effect of stress and pore pressure on them is evaluated. Appropriate effective stress laws which control the evolution of total volume, pore volume, solid volume, porosity and drained bulk modulus are discussed. A phenomenon of degradation of elastic properties is observed in the test results. The microscopic observations showed that this degradation is caused by the microcracking of the material under isotropic loading. The good compatibility and the consistency of the obtained poromechanical parameters demonstrate that the behaviour of the hardened cement paste can be indeed described within the framework of the theory of porous media.

  8. A Brief Discussion of Radiation Hardening of CMOS Microelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Myers, D.R.

    1998-12-18

    Commercial microchips work well in their intended environments. However, generic microchips will not fimction correctly if exposed to sufficient amounts of ionizing radiation, the kind that satellites encounter in outer space. Modern CMOS circuits must overcome three specific concerns from ionizing radiation: total-dose, single-event, and dose-rate effects. Minority-carrier devices such as bipolar transistors, optical receivers, and solar cells must also deal with recombination-generation centers caused by displacement damage, which are not major concerns for majority-carrier CMOS devices. There are ways to make the chips themselves more resistant to radiation. This extra protection, called radiation hardening, has been called both a science and an art. Radiation hardening requires both changing the designs of the chips and altering the ways that the chips are manufactured.

  9. Radiation effects in semiconductors: technologies for hardened integrated circuits

    International Nuclear Information System (INIS)

    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

  10. On use of radial evanescence remain term in kinematic hardening

    International Nuclear Information System (INIS)

    This paper presents the interest which lies in non-linear kinematic hardening rule with radial evanescence remain term as proposed for modelling multiaxial ratchetting. From analytical calculations in the case of the tension/torsion test, this ratchetting is compared with that proposed by Armstrong and Frederick. A modification is then proposed for Chaboche's elastoplastic model with two non-linear kinematic variables, by coupling the two types of hardening by means of two scalar parameters. Identification of these two parameters returns to speculate on the directions of strain in order to adjust the ratchetting to experimental observations. Using biaxial ratchetting tests on stainless steel 316 L specimens at ambient temperature, it is shown that satisfactory modelling of multiaxial ratchetting is obtained. (author). 4 refs., 5 figs

  11. Segmentation-free empirical beam hardening correction for CT

    International Nuclear Information System (INIS)

    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

  12. Prediction Of Mechanical Properties Of Quench Hardening Steel*

    Directory of Open Access Journals (Sweden)

    Chotěborský R.

    2015-03-01

    Full Text Available The present study investigated the application of finite element method for prediction of mechanical properties of quench hardening steel. Based on the experimental results obtained, a numerical model for simulation of continuous cooling of quench hardening steel was developed. For the simulation of the kinetics of diffusion phase transformations, the Avrami equation and additive rule were applied. A new model was also developed for martensitic transformation which was validated using metallographic analysis and hardness tests. Experimental and simulation results indicated a good agreement. The developed model information provided here could be used for simulation of continuous cooling and kinetics phase transformation as well as for prediction of final distribution of microstructures and hardness of alloy steels.

  13. Friction and source hardening in irradiated mild steel

    International Nuclear Information System (INIS)

    The effect of neutron fluence on stress-strain behavior of mild steel at ambient temperature revealed that Luders strain increases with fluence and at the highest fluence employed here namely 1.4x1019n/cm2 fracture occurred during Luders propagation. The lower yield stress increased as cube root of fluence and friction stress increased as square root of fluence. The interstitial impurity atoms (C and N) combine with irradiation induced defects thereby resulting in reduced net concentration of free C and N in solution and thus the source pinning effect decreases in irradiated steels as observed here. The increase in Luders strain with the corresponding decrease in source hardening resulted in reduced work-hardening in irradiated steels as expected

  14. Radiation Hardening of LED Luminaires for Accelerator Tunnels

    CERN Document Server

    Devine, James D

    2016-01-01

    This paper summarises progress made towards the radiation hardening of LED emergency luminaires for evacuation and emergency response within the underground areas of the CERN accelerator complex. The objective has been to radiation harden existing Commercial Off-The-Shelf (COTS) emergency luminaires to maximise lighting performance, without compromising IEC 60598-2-22 compliance. A systems level approach has been adopted, leading to the development of a diode bridge based AC/DC power converter. Modified COTS luminaires including this converter design have been irradiated (to 100 kGy TID using a Cobalt-60 source), with results of a subsequent photometric analysis presented. Following encouraging tests results, a reference design for the power converter has been released under the CERN Open Hardware License to encourage manufacturer adoption. The paper concludes with areas of interest for future research in further improving the radiation hardness of LED emergency lighting for accelerators with detailed studies...

  15. An energy-based beam hardening model in tomography

    Energy Technology Data Exchange (ETDEWEB)

    Casteele, E van de; Dyck, D van; Sijbers, J; Raman, E [Vision Lab, Physics Departement, University of Antwerp (RUCA) (Belgium)

    2002-12-07

    As a consequence of the polychromatic x-ray source, used in micro-computer tomography ({mu}CT) 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.

  16. 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

  17. INVESTIGATION ON HARDENED STEEL MILLING WITH MICRO-END MILL

    Institute of Scientific and Technical Information of China (English)

    HUYing-ning; WANGCheng-yong; WUXue-qi; QINZhe; ZENGBao-ping

    2004-01-01

    Tool wear and breakage of the micro-milling tool is an important problem for high speed machining of hardened steel die and mould. Dry milling of S136 hardened steel is carried out using TiA1N coated carbide micro-end mill (Ф2 mm). The effect of cutting speed, feed per tooth and radial depth of cut on cutting force is analyzed. Cutting parameters adapting to dry machining and strategy optimized for higher rate of material removal with lower cutting force are attained. Results of SEM observation show that the main failure patterns of micro-end mill are breakage of tool tip, wear and drop-off of surface coating, micro-chipping, and breakage of flank.

  18. Sequential circuit design for radiation hardened multiple voltage integrated circuits

    Science.gov (United States)

    Clark, Lawrence T.; McIver, III, John K.

    2009-11-24

    The present invention includes a radiation hardened sequential circuit, such as a bistable circuit, flip-flop or other suitable design that presents substantial immunity to ionizing radiation while simultaneously maintaining a low operating voltage. In one embodiment, the circuit includes a plurality of logic elements that operate on relatively low voltage, and a master and slave latches each having storage elements that operate on a relatively high voltage.

  19. Numerical implementation of a model with directional distortional hardening

    Czech Academy of Sciences Publication Activity Database

    Marek, René; Plešek, Jiří; Hrubý, Zbyněk; Parma, Slavomír; Feigenbaum, H. P.; Dafalias, Y.F.

    2015-01-01

    Roč. 141, č. 12 (2015), 04015048-04015048. ISSN 0733-9399 R&D Projects: GA MŠk LH14018; GA ČR(CZ) GA15-20666S Institutional support: RVO:61388998 Keywords : plasticity * directional distortional hardening * finite-element procedures Subject RIV: JG - Metallurgy Impact factor: 1.294, year: 2014 http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000954

  20. Hardening by annealing and softening by deformation in nanostructured metals

    DEFF Research Database (Denmark)

    Huang, X.; Hansen, N.; Tsuji, N.

    2006-01-01

    We observe that a nanostructured metal can be hardened by annealing and softened when subsequently deformed, which is in contrast to the typical behavior of a metal. Microstructural investigation points to an effect of the structural scale on fundamental mechanisms of dislocation-dislocation and....... As a consequence, the strength decreases and the ductility increases. These observations suggest that for materials such as the nanostructured aluminum studied here, deformation should be used as an optimizing procedure instead of annealing....

  1. Biochemical studies of enzymes in insect cuticle hardening

    OpenAIRE

    Liu, Pingyang

    2013-01-01

    In insects, the cuticle provides protection against physical injury and water loss, rigidness for muscle attachment and mechanical support, and flexibility in inter-segmental and joint areas for mobility. As most insects undergo metamorphosis, they need to shred off old cuticle and synthesize new cuticle to fit the body shape and size throughout their life cycles. The newly formed cuticle, mainly composed of cuticular proteins, chitin, and sclerotizing reagents, needs to be hardened through t...

  2. Monolithic model of continuous induction hardening of a steel mandrel

    Czech Academy of Sciences Publication Activity Database

    Karban, P.; Doležel, Ivo; Ulrych, B.; Barglik, J.

    Stevenage: Institution of Engineering and Technology (IET), 2011, s. 122-123. ISBN 978-1-84919-468-6. [International Conference on Computation in Electromagnetics CEM 2001 /8./. Wroclaw (PL), 11.04.2011-14.04.2011] R&D Projects: GA ČR(CZ) GAP102/11/0498 Institutional research plan: CEZ:AV0Z20570509 Keywords : induction hardening * coupled problem * monolithic formulation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  3. Work Hardening and Mechanical Anisotropy of Aluminium Sheets and Profiles

    OpenAIRE

    Ryen, Øyvind

    2003-01-01

    The processing of aluminium alloys from casting to end product is associated with a large number of metallurgical phenomena. In order to further improve and optimise process routes and alloys, a thorough understanding of the thermomechanical treatments by experimental observations and physically based modelling is necessary.In part A of this thesis the work hardening behaviour of non-heat treatable alloys is followed up to large strains. The evolution in strength, microstructure and texture d...

  4. Hardening of concrete with a planned delayed ettringite formation

    OpenAIRE

    Lubej, Samo; Ivanič, Andrej; Radosavljević, Milan

    2012-01-01

    Delayed ettringite formation (DEF) in cementitious materials is widely considered as a harmful chemical reaction that causes extensive damages in hardened concrete. However, preventative measures and possible improvements in general are not extensively studied and require further attention. In this study was presented an investigation into a type of controlled DEF in places of finely dispersed crystallisation nuclei and provide evidence that the process may improve compressive strength of cem...

  5. Sinter-hardening process applicable to stainless steels

    OpenAIRE

    M. Rosso; Z. Brytan; L.A. Dobrzański

    2007-01-01

    Purpose: of this paper was to describe sintered duplex stainless steels manufactured in sinter-hardening process and its usability in field of stainless steels.Design/methodology/approach: In presented study duplex stainless steels were obtained through powder metallurgy starting from austenitic, ferritic base powders by controlled addition of alloying elements, such as Cr, Ni, Mo and Cu. In the studies apart from the preparation of mixes, Schaeffler’s diagram was taken into consideration. Pr...

  6. Control technology for surface treatment of materials using induction hardening

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, J.B.; Skocypec, R.D. [Sandia National Labs., NM (United States)

    1997-04-01

    In the industrial and automotive industries, induction case hardening is widely used to provide enhanced strength, wear resistance, and toughness in components made from medium and high carbon steels. The process uses significantly less energy than competing batch process, is environmentally benign, and is a very flexible in-line manufacturing process. As such, it can directly contribute to improved component reliability, and the manufacture of high-performance lightweight parts. However, induction hardening is not as widely used as it could be. Input material and unexplained process variations produce significant variation in product case depth and quality. This necessitates frequent inspection of product quality by destructive examination, creates higher than desired scrap rates, and causes de-rating of load stress sensitive components. In addition, process and tooling development are experience-based activities, accomplished by trial and error. This inhibits the use of induction hardening for new applications, and the resultant increase in energy efficiency in the industrial sectors. In FY96, a Cooperative Research and Development Agreement under the auspices of the Technology Transfer Initiative and the Partnership for a New Generation of Vehicles was completed. A multidisciplinary team from Sandia National Labs and Delphi Saginaw Steering Systems investigated the induction hardening by conducting research in the areas of process characterization, computational modeling, materials characterization, and high speed data acquisition and controller development. The goal was to demonstrate the feasibility of closed-loop control for a specific material, geometry, and process. Delphi Steering estimated annual savings of $2-3 million per year due to reduced scrap losses, inspection costs, and machine down time if reliable closed-loop control could be achieved. A factor of five improvement in process precision was demonstrated and is now operational on the factory floor.

  7. Coating substance hardened by high-energy radiation

    International Nuclear Information System (INIS)

    A coating material hardening under high-energy radiation is described which contains unsaturated polyesters and -apart from other additives- vinyl monomers as binders. Industrial unsaturated polyesters with unsaturated groups in α,β position with regard to a carbonyl group may be used. 100% of the binder consist of 40-90% polyester, 60-10% monomers (in particular, alkoxyl alkyl esters of acrylic or mettiacrylic acid), and 0-20% other polymerizing monomers. (UWI)

  8. Single cell mechanics: stress stiffening and kinematic hardening

    CERN Document Server

    Fernández, Pablo

    2007-01-01

    Cell mechanical properties are fundamental to the organism but remain poorly understood. We report a comprehensive phenomenological framework for the nonlinear rheology of single fibroblast cells: a superposition of elastic stiffening and viscoplastic kinematic hardening. Our results show, that in spite of cell complexity its mechanical properties can be cast into simple, well-defined rules, which provide mechanical cell strength and robustness via control of crosslink slippage.

  9. Single cell mechanics: stress stiffening and kinematic hardening.

    Science.gov (United States)

    Fernández, Pablo; Ott, Albrecht

    2008-06-13

    Cell mechanical properties are fundamental to the organism but remain poorly understood. We report a comprehensive phenomenological framework for the complex rheology of single fibroblast cells: a superposition of elastic stiffening and viscoplastic kinematic hardening. Despite the complexity of the living cell, its mechanical properties can be cast into simple, well-defined rules. Our results reveal the key role of crosslink slippage in determining mechanical cell strength and robustness. PMID:18643547

  10. Case Hardening of Hardox 450 Steel for Increased Ballistic Strength

    OpenAIRE

    Buberg, Tor Arne

    2011-01-01

    AbstractSteel alloys are the material that is most used in protective constructions today. The reason is the overall good properties of steels, with its high strength and hardness, high ductility, high formability and relatively low cost compared to other materials. Even though armour steels are affordable, work is done to limit expenses from production or come up with new and less expensive alloys.Case hardening is a technique for production of steel with a very hard and durable surface whil...

  11. SEU hardened memory cells for a CCSDS Reed Solomon encoder

    International Nuclear Information System (INIS)

    This paper reports on design technique to harden CMOS memory circuits against Single Event Upset (SEU) in the space environment. The design technique provides a recovery mechanism which is independent of the shape of the upsetting event. A RAM cell and Flip Flop design are presented to demonstrate the method. The Flip Flop was used in the control circuitry for a Reed Solomon encoder designed for the Space Station and Explorer platforms

  12. 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.

  13. Identification of parameters of a directional distortional hardening model

    Czech Academy of Sciences Publication Activity Database

    Parma, Slavomír; Hrubý, Zbyněk; Marek, René; Plešek, Jiří; Feigenbaum, H. P.; Dafalias, Y.F.

    Berkeley, 2015. [International Conference on Material Modeling /4./. 27.05.2015-29.05.2015, Berkeley, California] R&D Projects: GA MŠk LH14018; GA ČR(CZ) GA15-20666S Institutional support: RVO:61388998 Keywords : plasticity * directional distortional hardening * cyclic loading Subject RIV: JG - Metallurgy http://icmm4.usacm.org/sites/default/files/ICMM4-BookofAbstracts-FINAL.pdf

  14. Critical role of zinc in hardening of Nereis jaws

    OpenAIRE

    Broomell, Chris C.; Mattoni, Mike A.; Zok, Frank W.; Waite, J. Herbert

    2006-01-01

    Hardening of invertebrate jaws and mandibles has been previously correlated to diverse, potentially complex modifications. Here we demonstrate directly, for the first time, that Zn plays a critical role in the mechanical properties of histidine-rich Nereis jaws. Using nanoindentation, we show that removal of Zn by chelation decreases both hardness and modulus by over 65%. Moreover, reconstitution of Zn yields a substantial recovery of initial properties. Modulus and hardness of Zn-replete jaw...

  15. Study on the hardening mechanism of cement asphalt binder

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The hydration and hardening mechanism of cement asphalt binder(CAB) was studied.The early hydration process,hydration products and paste microstructure of CAB made by Portland cement and anionic asphalt emulsion were investigated by calorimetry,X-ray diffraction,and environmental scanning electron microscopy.The early hydration process of CAB can be characterized as 5 stages similar to those of Portland cement.There is no chemical reaction detected between cement and asphalt,hence no new hydration products other than those of Portland cement are produced.The hardening of CAB begins with the hydration of cement.When the hydration of cement comes into the acceleration period and its exothermic rate comes to the maximum,the coalescence of asphalt particles in asphalt emulsion is triggered.In the hardened system of CAB,it was found that the hydration products of cement form the skeleton and are covered by the continuous asphalt film.They formed an interpenetrating network system.The emulsifiers in the asphalt emulsion may retard the hydration process of cement.

  16. Helium and hydrogen induced hardening in 316LN stainless steel

    Science.gov (United States)

    Hunn, J. D.; Lee, E. H.; Byun, T. S.; Mansur, L. K.

    2000-12-01

    In certain radiation environments, such as the spallation neutron source (SNS) presently in design and construction, the high transmutation production rate for helium and hydrogen, concomitant with displacement damage, may affect the mechanical properties of structural materials. To better understand this effect, we have studied type 316LN stainless steel specimens implanted with medium energy Fe-, He-, and H-ions, alone and in combination. In this report, we present nanoindentation measurements of the incremental increase in hardness caused by 360 keV He-ions implanted at 200°C to concentrations from 2 to 200 000 appm. The He-induced hardening was found to saturate at twice the level measured for Fe-induced displacement damage alone. The additional hardening at high helium concentrations was associated with the presence of helium filled cavities (bubbles), observed by transmission electron microscopy (TEM). We also found that co-injection of helium and hydrogen resulted in more hardening than was observed for He-implantation alone.

  17. 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)

  18. Hardening of smooth pulsed laser deposited PMMA films by heating

    Science.gov (United States)

    Fuchs, Britta; Schlenkrich, Felix; Seyffarth, Susanne; Meschede, Andreas; Rotzoll, Robert; Vana, Philipp; Großmann, Peter; Mann, Klaus; Krebs, Hans-Ulrich

    2010-03-01

    Smooth poly(methyl methacrylate) (PMMA) films without any droplets were pulsed laser deposited at a wavelength of 248 nm and a laser fluence of 125 mJ/cm2. After deposition at room temperature, the films possess low universal hardness of only 3 N/mm2. Thermal treatments up to 200°C, either during deposition or afterwards, lead to film hardening up to values of 200 N/mm2. Using a combination of complementary methods, two main mechanisms could be made responsible for this temperature induced hardening effect well above the glass transition temperature of 102°C. The first process is induced by the evaporation of chain fragments and low molecular mass material, which are present in the film due to the ablation process, leading to an increase of the average molecular mass and thus to hardening. The second mechanism can be seen in partial cross-linking of the polymer film as soon as chain scission occurs at higher temperatures and the mobility and reactivity of the polymer material is high enough.

  19. Helium and hydrogen induced hardening in 316LN stainless steel

    International Nuclear Information System (INIS)

    In certain radiation environments, such as the spallation neutron source (SNS) presently in design and construction, the high transmutation production rate for helium and hydrogen, concomitant with displacement damage, may affect the mechanical properties of structural materials. To better understand this effect, we have studied type 316LN stainless steel specimens implanted with medium energy Fe-, He-, and H-ions, alone and in combination. In this report, we present nanoindentation measurements of the incremental increase in hardness caused by 360 keV He-ions implanted at 200 deg. C to concentrations from 2 to 200,000 appm. The He-induced hardening was found to saturate at twice the level measured for Fe-induced displacement damage alone. The additional hardening at high helium concentrations was associated with the presence of helium filled cavities (bubbles), observed by transmission electron microscopy (TEM). We also found that co-injection of helium and hydrogen resulted in more hardening than was observed for He-implantation alone

  20. Effect of silica fume on the fresh and hardened properties of fly ash-based self-compacting geopolymer concrete

    Science.gov (United States)

    Memon, Fareed Ahmed; Nuruddin, Muhd Fadhil; Shafiq, Nasir

    2013-02-01

    The effect of silica fume on the fresh and hardened properties of fly ash-based self-compacting geopolymer concrete (SCGC) was investigated in this paper. The work focused on the concrete mixes with a fixed water-to-geopolymer solid (W/Gs) ratio of 0.33 by mass and a constant total binder content of 400 kg/m3. The mass fractions of silica fume that replaced fly ash in this research were 0wt%, 5wt%, 10wt%, and 15wt%. The workability-related fresh properties of SCGC were assessed through slump flow, V-funnel, and L-box test methods. Hardened concrete tests were limited to compressive, splitting tensile and flexural strengths, all of which were measured at the age of 1, 7, and 28 d after 48-h oven curing. The results indicate that the addition of silica fume as a partial replacement of fly ash results in the loss of workability; nevertheless, the mechanical properties of hardened SCGC are significantly improved by incorporating silica fume, especially up to 10wt%. Applying this percentage of silica fume results in 4.3% reduction in the slump flow; however, it increases the compressive strength by 6.9%, tensile strength by 12.8% and flexural strength by 11.5%.

  1. Influence of Plastic Deformation on Low Temperature Surface Hardening of Austenitic and Precipitation Hardening Stainless Steels by Gaseous Nitriding

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas Lundin;

    2015-01-01

    This article addresses an investigation of the influence of plastic deformation on low temperature surface hardening by gaseous nitriding of three commercial austenitic stainless steels: AISI 304, EN 1.4369 and Sandvik Nanoflex® with various degrees of austenite stability. The materials were...... case included X-ray diffraction analysis, reflected light microscopy and microhardness. The results demonstrate that a case of expanded austenite develops and that, in particular, strain-induced martensite has a large influence on the nitrided zone....

  2. Image space beam hardening corrections. Considerations for quantitative myocardial imaging

    International Nuclear Information System (INIS)

    The case of quantitative myocardial imaging presents unique challenges with respective to beam hardening artifacts. There is a desire to make quantitative assessments of the attenuation in the myocardium in order to assess pathology such as non-perfused regions. The area of interest in this case is directly adjacent to a region of high contrast (i.e. the opacified left ventricle). There are other iodinated objects such as the great vessels in close proximity. Additionally, there are bones within the scanning field of view such as the spine, which is adjacent to the heart. There have been a variety of techniques proposed over the years to correct for beam hardening. These techniques include iterative techniques which require full knowledge of the spectrum. A more pragmatic approach can be achieved strictly with image data by segmenting the image into multiple materials and correcting for non-linearity by adding correction images of higher order contributions from different materials. Recently, an automated empirical procedure for determining the weights of the higher order contributions and cross terms was proposed by Kyriakou et al. In this method the corrected image is achieved by combining the individual basis images such that the final image has the maximum flatness. The image with maximum flatness is achieved by minimizing the total variation of the combined image. In the presented work by Kyriakou et al. the image was segmented into water and bone using a soft thresholding procedure. In this work we have implemented an extended version of the correction scheme which includes separate components for water, iodine and bone. The performance of the method has been assessed in phantom data where quantitative metrics are improved by including iodine as a third material. Additionally, the technique has been demonstrated using clinical projection data. These results demonstrate a reduction of the beam hardening artifacts typically present between the aorta and the

  3. Sinter-hardening process applicable to stainless steels

    Directory of Open Access Journals (Sweden)

    M. Rosso

    2007-10-01

    Full Text Available Purpose: of this paper was to describe sintered duplex stainless steels manufactured in sinter-hardening process and its usability in field of stainless steels.Design/methodology/approach: In presented study duplex stainless steels were obtained through powder metallurgy starting from austenitic, ferritic base powders by controlled addition of alloying elements, such as Cr, Ni, Mo and Cu. In the studies apart from the preparation of mixes, Schaeffler’s diagram was taken into consideration. Prepared mixes have been compacted at 800 MPa and sintered in a vacuum furnace with argon backfilling at temperatures from 1200°C to 1285°C for 0.5, 1 and 2 h. After sintering different cooling cycles were applied using nitrogen under pressure from 0.6 MPa to 0.002 MPa in argon atmosphere. Produced duplex stainless steels have been studied by scanning and optical microscopy and EDS chemical analysis of microstructure components.Findings: Obtained microstructure and mechanical properties of sintered duplex stainless steel strictly depend on the density and the pore morphology present in the microstructure and especially on cooling rate directly from sintering temperature in sinter-hardening process. The lowest cooling rate - applied gas pressure, the mechanical properties and corrosion resistance decrease due to precipitation of sigma phase. Proper bi-physic microstructure was obtained using nitrogen under pressure of 0.6 and 0.2 MPa.Research limitations/implications: Applied fast cooling rate seems to be a good compromise for mechanical properties and obtained microstructures, nevertheless further tests should be carried out in order to examine its influence on corrosion properties.Originality/value: The utilization of sinter-hardening process combined with use of elemental powders added to a stainless steel base powder shows its potentialities in terms of good microstructural homogeneity and especially working with cycles possible to introduce in

  4. Radiation-Hardened Software for Space Flight Science Applications

    Science.gov (United States)

    Mehlitz, P. C.; Penix, J. J.; Markosian, L. Z.

    2005-12-01

    Hardware faults caused by radiation-induced Single Event Effects (SEEs) are a serious issue in space flight, especially affecting scientific missions in earth orbits crossing the poles or the South Atlantic Anomaly. Traditionally, SEEs are treated as a hardware problem, for example mitigated by radiation-hardened processors and shielding. Rad-hardened processors are expensive, exhibit a decade performance gap compared to COTS technology, have a larger form factor and require more power. Shielding is ineffective for high energy particles and increases launch weight. Hardware approaches cannot dynamically adapt protection levels for different radiation scenarios depending on solar activity and flight phase. Future hardware will exacerbate the problem due to higher chip densities and lower power levels. An alternative approach is to use software to mitigate SEEs. This "Radiation Hardened Software" (RHS) approach has two components: (1) RHS library and application design guidelines To increase robustness, we combine SEE countermeasures in three areas: prevention and detection; recovery; and reconfiguration. Prevention and detection includes an application- and heap-aware memory scanner, and dynamically adapted software Error Correction Codes to handle cache and multi-bit errors. Recovery mechanisms include exception firewalls and transaction-based software design patterns, to minimize data loss. Reconfiguration includes a heap manager to avoid damaged memory areas. (2) Software-based SEE Simulation Probabilistic effects require extensive simulation, with test environments that do not require original flight hardware and can simulate various SEE profiles. We use processor emulation software, interfaced to a debugger, to analyze SEE propagation and optimize RHS mechanisms. The simulator runs unmodified binary flight code, enables injecting randomized transient and permanent memory errors, providing execution traces and precise failure reproduction. The goal of RHS is to

  5. Case depth verification of hardened samples with Barkhausen noise sweeps

    International Nuclear Information System (INIS)

    An interesting topic of recent Barkhausen noise (BN) method studies is the application of the method to case depth evaluation of hardened components. The utilization of BN method for this purpose is based on the difference in the magnetic properties between the hardened case and the soft core. Thus, the detection of case depth with BN can be achieved. The measurements typically have been carried out by using low magnetizing frequencies which have deeper penetration to the ferromagnetic samples than the conventional BN measurement. However, the penetration depth is limited due to eddy current damping of the signal. We introduce here a newly found sweep measurement concept for the case depth evaluation. In this study sweep measurements were carried out with various magnetizing frequencies and magnetizing voltages to detect the effect of different frequency and voltage and their correspondence to the actual case depth values verified from destructive characterization. Also a BN measurement device that has an implemented sweep analysis option was utilised. The samples were either induction or case-hardened samples and sample geometry contained both rod samples and gear axle samples with different case depth values. Samples were also further characterized with Xray diffraction to study the residual stress state of the surface. The detailed data processing revealed that also other calculated features than the maximum slope division of the 1st derivative of the BN signal could hold the information about the case depth value of the samples. The sweep method was able to arrange the axles into correct order according to the case depth value even though the axles were used

  6. Bake hardening behavior of TRIP and DP steels

    Institute of Scientific and Technical Information of China (English)

    Jicheng Zhang; Renyu Fu; Mei Zhang; Rendong Liu; Xicheng Wei; Lin Li

    2008-01-01

    The bake hardening (BH) behavior of transformation-induced plasticity (TRIP) and dual-phase (DP) steels after different prestrains was studied. The experimental results indicate that TRIP steel exhibits good BH ability while DP steel does not, and prestrain displays a strong effect on the BH values of both steels. The comparison of microstructures of the two steels showed that the hard second phase in the matrix might be harmful to the BH ability. For deformed specimens, baking resulted in a loss of uniform elongation, but there was no obvious decrease in uniform elongation for unprestrained specimens.

  7. Rationale simplified hardening training and recreational complexes future teachers

    Directory of Open Access Journals (Sweden)

    Verbludov I.B.

    2010-02-01

    Full Text Available Distribution in the modern world epidemiological diseases are influenza and acute respiratory viral infections requires a search for simplified, effective preventive means. The main direction of prevention of these diseases is to strengthen and enhance the activities of the immune system. Strengthening the protective systems of the body is directly related to the constant holding of different types of hardening. This study illustrates the possibility of using quenching air and water in the independent exercise training and recreational facilities in all conditions of students.

  8. Selection method of steel grade with required hardenability

    OpenAIRE

    J. Trzaska; W. Sitek; L.A. Dobrzański

    2006-01-01

    Purpose: The purpose of this paper is to work out the computer aided method for selecting grades of steel with a required hardenability.Design/methodology/approach: The purpose has been achieved in two stages. In the first stage a neural network model for calculating the Jominy curve on the basis of the chemical composition has been worked out. This model made possible to prepare, in the second stage, a representative set of data and to work out the neural classifier that would aid the select...

  9. Modeling of simultaneous induction hardening in monolithic formulation

    Czech Academy of Sciences Publication Activity Database

    Karban, P.; Doležel, Ivo; Ulrych, B.

    Barcelona : International Center for Numerical Methods in Engineering (CIMNE),, 2011 - (Papadrakakis, M.; Onate, E.; Schrefler, B.), s. 1167-1175 ISBN 978-84-89925-78-6. [International Conference on Computational Methods for Coupled Problems in Science and Engineering, COUPLED PROBLEMS 2011 /4./. Kos (GR), 20.06.2011-22.06.2011] R&D Projects: GA ČR(CZ) GAP102/11/0498 Institutional research plan: CEZ:AV0Z20570509 Keywords : induction hardening * nonlinear coupled problem * monolithic formulation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  10. Ferroelectric memories: A possible answer to the hardened nonvolatile question

    International Nuclear Information System (INIS)

    Ferroelectric memory cells have been fabricated using a process compatible with semiconductor VLSI (Very Large-Scale Integration) manufacturing techniques which are basically nonvolatile and radiation hard. The memory can be made NDRO (Nondestructive Readout) for strategic systems using several techniques; the most practical is probably a rapid read/restore in combination with EDAC software. This memory can replace plated wire and will have substantial advantages in cost, weight, size, power and speed. It provides a practical cost-competitive solution to the need for nonvolatile RAM in all hardened tactical, avionic, and space systems

  11. Influence of particles on work hardening strain and recovery strain

    Czech Academy of Sciences Publication Activity Database

    Blum, W.; Dvořák, Jiří; Král, Petr; Sklenička, Václav

    Brno: Ústav fyziky materiálů AV ČR, v. v. i., 2015 - (Dlouhý, A.; Kunz, L.). s. 137-137 ISBN 978-80-87434-07-9. [ICSMA-17 International Conference on the Strength of Materials /17./. 09.08.2015-14.08.2015, Brno] R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : recovery strain * CuZr particles * crystallite boundaries * work hardening Subject RIV: JG - Metallurgy

  12. Interaction between alloying and hardening of cast iron surface

    Institute of Scientific and Technical Information of China (English)

    刘政军; 郝雪枫; 傅迎庆; 牟力军

    2002-01-01

    To improve wear resistance of surface will increase the service life of gray cast iron directly. This paper presents that gray cast iron surface coated with alloy powder is locally remelted by TIG arc to increase the wear resistance. The influences of arc current and scanning rate etc on surface properties are found. Under different conditions, the microstructure, hardness and wear resistance of remelted layer are analyzed and measured. The results indicate that the gray cast iron surface can be strengthened by TIG arc local remelting treatment. Especially, surface alloying hardening effect is best and surface properties are improved remarkably.

  13. 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 present...... in the stainless steel alloys. The presented computational approach for alloy design enables “screening” of hundreds of thousands hypothetical alloy systems by use of Thermo-Calc. Promising compositions for new stainless steel alloys can be selected based on imposed criteria, i.e. facilitating easy...

  14. The development of radiation hardened robot for nuclear facility

    International Nuclear Information System (INIS)

    The work conducted in this stage covers development of core technology of tele-robot system including monitoring technique in high-level radioactive area, tele-sensing technology and radiation-hardened technology for the non-destructive tele-inspection system which monitors the primary coolant system during the normal operations of PHWR(Pressurized Heavy Water Reactor) NPPs and measures the decrease of bending part of feeder pipe during overall. Based on the developed core technology, the monitoring mobile robot system of the primary coolant system and the feeder pipe inspecting robot system are developed

  15. The development of radiation hardened robot for nuclear facility

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Ho; Jung, Seung Ho; Kim, Byung Soo and others

    2000-04-01

    The work conducted in this stage covers development of core technology of tele-robot system including monitoring technique in high-level radioactive area, tele-sensing technology and radiation-hardened technology for the non-destructive tele-inspection system which monitors the primary coolant system during the normal operations of PHWR(Pressurized Heavy Water Reactor) NPPs and measures the decrease of bending part of feeder pipe during overall. Based on the developed core technology, the monitoring mobile robot system of the primary coolant system and the feeder pipe inspecting robot system are developed.

  16. Hardening of WC-Co alloys by ion implantation

    International Nuclear Information System (INIS)

    The hardening effect on the surface layers of WC-Co alloys after Ar+- and N+-ion implantation with the fluence in the range 1 divided by 8.7 x 1017 cm-2 has been investigated at room temperature and under heating with an ion beam. The depth of the Auger distribution profiles and the microhardness of implanted samples were measured. The radiation-stimulated diffusion of nitrogen atoms and the microhardness enhancement were observed. The contribution of the polymorphic Co-phase transformation and the production of Co-N compounds is discussed. (author)

  17. Ductility and work hardening in nano-sized metallic glasses

    International Nuclear Information System (INIS)

    In-situ nano-tensile experiments on 70 nm-diameter free-standing electroplated NiP metallic glass nanostructures reveal tensile true strains of ∼18%, an amount comparable to compositionally identical 100 nm-diameter focused ion beam samples and ∼3 times greater than 100 nm-diameter electroplated samples. Simultaneous in-situ observations and stress-strain data during post-elastic deformation reveal necking and work hardening, features uncharacteristic for metallic glasses. The evolution of free volume within molecular dynamics-simulated samples suggests a free surface-mediated relaxation mechanism in nano-sized metallic glasses

  18. A project of X-ray hardening correction in large ICT

    International Nuclear Information System (INIS)

    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)

  19. Effect of alkohols as hardening-accelerating admixtures on the cement properties

    OpenAIRE

    Флейшер, Ганна Юріївна; Токарчук, Володимир Володимирович; Василькевич, Олександр Іванович; Свідерський, Валентин Анатолійович

    2014-01-01

    The effect of alcohols as hardening-accelerating admixtures on physicomechanical properties of cement, particularly strength indexes in early hardening period is investigated. Alcohols can be used as an effective hardening accelerators of cement. The effectiveness of the influence of alcohols on the cement properties depends on their spatial structure and the number of hydroxyl groups. It was found that the largest increase in the cement strength is promoted by individual admixtures of alcoho...

  20. The method of modelling of relationships between hardenability and chemical composition of the constructional alloy steels

    International Nuclear Information System (INIS)

    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)

  1. Experimental research and computer simulation of face grind-hardening technology

    OpenAIRE

    Li, Jianping; Liu, Songyong; Du, Changlong

    2015-01-01

    The influence of technical parameters on face grind-hardening surface hardness and hardened layer depth were determined by systematic experimental studies on technological parameters, such as grinding methods and grinding parameters, which provides a reference for choosing reasonable parameters in face grind-hardening processing. By FEA simulation of the grinding temperature field using ANSYS software, the variation in temperature at different points on the workpiece surface and the temperatu...

  2. Development of a Pressure-Dependent Constitutive Model with Combined Multilinear Kinematic and Isotropic Hardening

    Science.gov (United States)

    Allen Phillip A.; Wilson, Christopher D.

    2003-01-01

    The development of a pressure-dependent constitutive model with combined multilinear kinematic and isotropic hardening is presented. The constitutive model is developed using the ABAQUS user material subroutine (UMAT). First the pressure-dependent plasticity model is derived. Following this, the combined bilinear and combined multilinear hardening equations are developed for von Mises plasticity theory. The hardening rule equations are then modified to include pressure dependency. The method for implementing the new constitutive model into ABAQUS is given.

  3. Development of Bake Hardening Effect by Plastic Deformation and Annealing Conditions

    OpenAIRE

    T. Kvačkaj; Mamuzić, I.

    2005-01-01

    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 (ba...

  4. Radiation-Hardened Memristor-based Memory for Extreme Environments Project

    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...

  5. 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....

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

    International Nuclear Information System (INIS)

    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)

  7. Property of laser welded bake-hardening steel in tailored blanks for automobile

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, F.; Shibao, M.; Yoshida, N.; Hirose, A.; Kobayashi, K.F. [Dept. of Mfg. Science, Graduate School of Engineering, Osaka Univ., Osaka (Japan); Shibata, K.; Sakamoto, H.; Sakurai, H. [Material Research Lab. Nissan Research Center, Nissan Motor Co., Ltd. 1, Yokosuka, Kanagawa (Japan)

    2004-07-01

    The behavior of bake-hardening of the laser weldment was investigated. The bake-hardening steel(BH steel) was welded with Nd:YAG laser followed by plastic deformation and subsequent heat-treatment. Then the influence of laser welding on the behavior of bake-hardening was investigated. The hardness of the laser weld metal significantly increased after welding. After the plastic deformation, both the base metal and weld metal became harder by work-hardening. The heat treatment resulted in more increment of hardness in both the base metal and weld metal by bake-hardening. The amount of bake-hardening reached a maximum value at the plastic strain of 5% or more. We modified a kinetic equation proposed for predicting the strength of a low-carbon bake-hardening steel and applied to the estimation of hardness of the base metal and weld metal. The calculated hardness values agree with the experimental data. The calculated activation energy for bake-hardening was that for diffusion of carbon and nitrogen atoms in {alpha}-Fe. Thus the hardening is thought to be governed by diffusion of these solute atoms. (orig.)

  8. Comparative evolution of various CCD image sensors hardening techniques with ionizing radiation

    International Nuclear Information System (INIS)

    This paper reviews various techniques to harden Charged Coupled Device (CCD) sensors and the results after irradiation of three Thomson n buried channel CCDs having a different degree of hardening. It describes the major irradiation effects on CCD performances and it makes a comparison of the results between the different hardening levels. It shows good results on dark voltage after ionizing radiation for TH 7863M device hardened both by design and by operating conditions (MPP mode) with respect to the standard device TH 7863A. The irradiations were performed with 60Co or X-ray (10 keV) sources on devices in operating mode. (author). 3 refs., 8 figs

  9. Surface hardening of poly(methyl methacrylate) by electron irradiation

    International Nuclear Information System (INIS)

    Poly(methyl methacrylate) (PMMA), known as a radiation-degrading polymer, showed mechanically hardening behavior under a high-fluence electron irradiation. When the electron fluence was less than 1 x 1015 cm-2, PMMA showed normal degrading behavior. However, at electron fluence higher than 1 x 1017 cm-2, the mechanical properties of the irradiated PMMA were tremendously improved. Bulk plate PMMA samples and an electron energy of 60 keV were employed in the irradiation experiments. The surface hardness of the irradiated PMMA increased from a pristine value of 0.29 GPa up to 2.8 GPa and the elastic modulus increased from 5.6 GPa to 22.9 GPa at an electron fluence of 7.5 x 1017 cm-2. Both Raman spectra and XPS spectra showed that the surface hardening was attributed to the transformation of polymeric materials into hydrogenated amorphous carbon under the electron irradiation. Confocal Raman spectra showed that the transformation occurred from the surface to the depth of electron range

  10. Electron beam hardening type copper plate printing ink

    International Nuclear Information System (INIS)

    Copper plate printing is the printing method of filling ink in the parts of concave printing elements on a type area, and transferring the ink to a base, and it is the feature that the ink in the printing element parts of a print rises. Copper plate prints show profound feeling, in addition, its effect of preventing forgery is high. This method is generally called engraving printing, and is used frequently for printing various bills and artistic prints. The electron beam irradiation apparatus installed in the laboratory of the Printing Bureau, Ministry of Finance, is an experimental machine of area beam type, and is so constructed as to do batch conveyance and web conveyance. As the ink in printing element parts rises, the offset at the delivery part of a printing machine becomes a problem. Electron beam is superior in its transparency, and can dry instantaneously to the inside of opaque ink. At 200 kV of acceleration voltage, the ink of copper plate prints can be hardened by electron beam irradiation. The dilution monomers as the vehicle for ink were tested for their dilution capability and the effect of electron beam hardening. The problem in the utilization of electron beam is the deterioration of papers, and the counter-measures were tested. (K.I.)

  11. idRHa+ProMod - Rail Hardening Control System

    Science.gov (United States)

    Ferro, L.

    2016-03-01

    idRHa+ProMod is the process control system developed by Primetals Technologies to foresee the thermo-mechanical evolution and micro-structural composition of rail steels subjected to slack quenching into idRHa+ Rail Hardening equipments in a simulation environment. This tool can be used both off-line or in-line, giving the user the chance to test and study the best cooling strategies or letting the automatic control system free to adjust the proper cooling recipe. Optimization criteria have been tailored in order to determine the best cooling conditions according to the metallurgical requirements imposed by the main rail standards and also taking into account the elastoplastic bending phenomena occurring during all stages of the head hardening process. The computational core of idRHa+ProMod is a thermal finite element procedure coupled with special algorithms developed to work out the main thermo-physical properties of steel, to predict the non-isothermal austenite decomposition into all the relevant phases and subsequently to evaluate the amount of latent heat of transformation released, the compound thermal expansion coefficient and the amount of plastic deformation in the material. Air mist and air blades boundary conditions have been carefully investigated by means of pilot plant tests aimed to study the jet impingement on rail surfaces and the cooling efficiency at all working conditions. Heat transfer coefficients have been further checked and adjusted directly on field during commissioning. idRHa+ is a trademark of Primetals Technologies Italy Srl

  12. Latent hardening size effect in small-scale plasticity

    International Nuclear Information System (INIS)

    We aim at understanding the multislip behaviour of metals subject to irreversible deformations at small-scales. By focusing on the simple shear of a constrained single-crystal strip, we show that discrete Dislocation Dynamics (DD) simulations predict a strong latent hardening size effect, with smaller being stronger in the range [1.5 µm, 6 µm] for the strip height. We attempt to represent the DD pseudo-experimental results by developing a flow theory of Strain Gradient Crystal Plasticity (SGCP), involving both energetic and dissipative higher-order terms and, as a main novelty, a strain gradient extension of the conventional latent hardening. In order to discuss the capability of the SGCP theory proposed, we implement it into a Finite Element (FE) code and set its material parameters on the basis of the DD results. The SGCP FE code is specifically developed for the boundary value problem under study so that we can implement a fully implicit (Backward Euler) consistent algorithm. Special emphasis is placed on the discussion of the role of the material length scales involved in the SGCP model, from both the mechanical and numerical points of view. (paper)

  13. Discrepant hardening observed in cosmic-ray elemental spectra

    CERN Document Server

    Ahn, H S; Bagliesi, M G; Beatty, J J; Bigongiari, G; Childers, J T; Conklin, N B; Coutu, S; DuVernois, M A; Ganel, O; Han, J H; Jeon, J A; Kim, K C; Lee, M H; Lutz, L; Maestro, P; Malinin, A; Marrocchesi, P S; Minnick, S; Mognet, S I; Nam, J; Nam, S; Nutter, S L; Park, I H; Park, N H; Seo, E S; Sina, R; Wu, J; Yang, J; Yoon, Y S; Zei, R; Zinn, S Y; 10.1088/2041-8205/714/1/L89

    2010-01-01

    The balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment launched five times from Antarctica has achieved a cumulative flight duration of about 156 days above 99.5% of the atmosphere. The instrument is configured with complementary and redundant particle detectors designed to extend direct measurements of cosmic-ray composition to the highest energies practical with balloon flights. All elements from protons to iron nuclei are separated with excellent charge resolution. Here we report results from the first two flights of ~70 days, which indicate hardening of the elemental spectra above ~200 GeV/nucleon and a spectral difference between the two most abundant species, protons and helium nuclei. These results challenge the view that cosmic-ray spectra are simple power laws below the so-called knee at ~1015 eV. This discrepant hardening may result from a relatively nearby source, or it could represent spectral concavity caused by interactions of cosmic rays with the accelerating shock. Other possible ...

  14. Nuclear EMP: key suppression device parameters for EMP hardening

    International Nuclear Information System (INIS)

    The electrical transients induced by EMP exhibit unique characteristics which differ considerably from transients associated with other phenomena such as lightning, switching, and circuit malfunctions. The suppression techniques developed to handle more common transients, though not necessarily the same devices, can be used for EMP damage protection. The suppression devices used for circuit level EMP protection are referred to as Terminal Protection Devices (TPD). Little detailed data describing the response of TPD's to EMP-related transients have been published. While most vendors publish specifications for TPD performance, there is little standardization of parameters and TPD response models are not available. This lack of parameter standardization has resulted in a proliferation of test data that is sometimes conflicting and often not directly comparable. This paper derives and/or defines a consistent set of parameters based on EMP circuit hardening requirements and on measurable component parameters and is concerned only with use of TPD's to prevent permanent damage. Three sets of parameters pertaining to pertinent TPD functional characteristics were defined as follows: standby parameters, protection parameters, and failure parameters. These parameters are used to evaluate a representative sample of TPD's and the results are presented in matrix form to facilitate the selection of devices for specific hardening problems

  15. FATIGUE LIVES FOR INDUCTION HARDENED SHAFTS MATERIALS ACCORDING TO THE ENVIRONMENTAL TEMPERATURES

    Institute of Scientific and Technical Information of China (English)

    D.G. Lee; K.C.Jang; J.M. Kuk; I.S. Kim

    2005-01-01

    Rotary bending fatigue tests were carried out with two kinds of materials, S43C and S50C, using the front engine and front drive shaft (FF shaft) of vehicle. The specimens were induction hardened about 1.0mm depth from the specimen surface, and the hardness value on the surface was about HRC56-60. The tested environment temperatures were -30, 25 and 80℃ in order to look over effect of the induction hardening and the environmental temperatures on the fatigue characteristics. The fatigue limit of induction hardened specimens increased more about 45%than non-hardened specimens showing that the endurances of S43C and S50C were 98.1 and 107.9MPa in non-hardened samples, 147.1 and 156.9MPa in hardened samplesrespectably. The maximum tensile and compressive stress on the small circular defect was about +250 and -450MPa respectively when circular defect is situated on top and bottom. The fatigue life increased 80, 25and -30℃ in order regardless of hardening. In comparison of the fatigue lives on the basis of tested result at 25℃, the fatigue lives of non-hardened specimens decreased about 35%, but that of hardened specimens decreased about only 5% at 80℃ more than at 25℃. And fatigue life of non-hardened and hardened specimens were about 110% and 120% higher at -30℃ than that of 25℃. Based on the result of stress distribution near the defect, the tensile and compressive stress repeatedly generated by load direction were the largest on the small circular defect due to the stress concentration.

  16. Indigenous development and airworthiness certification of 15–5 PH precipitation hardenable stainless steel for aircraft applications

    Indian Academy of Sciences (India)

    Ashok Kumar; Y Balaji; N Eswara Prasad; G Gouda; K Tamilmani

    2013-02-01

    In this paper, we discuss the optimization of chemical composition, processing (forging and rolling) and heat treatment parameters to obtain the best combination of mechanical properties in case of a Fe–15Cr–5Ni–4Cu precipitation hardenable stainless steel. The -copper precipitates that form during aging are spherical in shape and coherent with the matrix and principally provide strengthening in this alloy. The orientation relationship is found to be Kurdjumov–Sachs (K–S), which is common in fcc–bcc systems. Results obtained from metallurgical evaluation (mechanical property and metallography) on 15–5 PH alloy during type certification on 3 different melts were used for the optimization, attempted in this study. The mechanical properties following strain deformation has been carried out using optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). In the aged conditions, the 15–5 PH alloy exhibited brittle failure with extensive cleavage and/or quasicleavage fracture. This paper reports all results and also factually shows that indigenously developed and produced 15–5 PH stainless steel matches in its properties with the equivalent aeronautical grade precipitation hardening stainless steels globally produced by internationally renowned manufactures.

  17. Experimental study of self-compacted concrete in hardened state

    Science.gov (United States)

    Parra Costa, Carlos Jose

    The main aim of this work is to investigate the hardened behaviour of Self-Compacting Concrete (SCC). Self compacting Concrete is a special concrete that can flow in its gravity and fill in the formwork alone to its self-weight, passing through the bars and congested sections without the need of any internal or external vibration, while maintaining adequate homogeneity. SCC avoids most of the materials defects due to bleeding or segregation. With regard to its composition, SCC consists of the same components as traditional vibrated concrete (TC), but in different proportions. Thus, the high amount of superplasticizer and high powder content have to taken into account. The high workability of SCC does not allow to use traditional methods for measuring the fresh state properties, so new tests has developed (slump-flow, V-funnel, L-box, and others). The properties of the hardened SCC, which depend on the mix design, should be different from traditional concrete. In order to study the possible modifications of SCC hardened state properties, a review of the bibliography was done. The state of art was focused on the mechanical behaviour (compressive strength, tension strength and elastic modulus), on bond strength of reinforcement steel, and on material durability. The experimental program consisted in the production of two types of concretes: Self-Compacting Concrete and Traditional Concrete. Four different dosages was made with three different water/cement ratio and two strength types of Portland cement, in order to cover the ordinary strength used in construction. Based on this study it can be concluded that compressive strength of SCC and TC are similar (the differences are lesser than 10%), whereas the tensile strength of TC are up to 18% higher. The values of elastic modulus of both concrete are similar. On the other hand, in the ultimate state the bond strength of SCC and TC is similar, although SCC shows higher bond stiffness in the serviceability state (initial

  18. Mechanism of unique hardening of dental Ag–Pd–Au–Cu alloys in relation with constitutional phases

    International Nuclear Information System (INIS)

    Highlights: ► The unique hardening behavior on Ag–Pd–Au–Cu alloys by solution treatment was investigated. ► The Cu-rich α1 phase and Ag-rich α2 phase decomposed by solution treatment contributed weakly to the change of hardness. ► The fine β phases precipitated by aging treatment caused great increase in hardness. ► The fine L10-type ordered β′ phase precipitated by solution treatment may contribute to the unique hardening behavior. - Abstract: The objective of this research was to investigate the effect of constitutional phases on the unique hardening behavior of as-solutionized dental Ag–Pd–Au–Cu alloy fabricated by cold rolling. The commercial dental Ag–Pd–Au–Cu alloy fabricated by cold rolling consists of Cu-rich α1, Ag-rich α2, and β phases. On the other hand, the Ag–Pd–Au–Cu alloy fabricated by the liquid rapid solidification (LRS) method consists of single α phase. They were subjected to various heat treatments, respectively. The microstructures were observed by scanning electron microscope, transmission electron microscope and X-ray diffraction. The hardness was evaluated by a Vickers micro-hardness tester. In the Ag–Pd–Au–Cu alloy fabricated by cold rolling, the fine L10-type-ordered β′ phase is precipitated and the coarse β phase is remained after solution treatment at 1123 K. The hardness increases drastically. On the other hand, in the Ag Pd–Au–Cu alloy fabricated by LRS method, the single α phase was decomposed into the α1 phase and the α2 phase after solution treatment at 1023 K and its hardness change was small. However, after aging treatment at 673 K, the fine β phase is precipitated in the α phase and the hardness increases greatly even in the Ag–Pd–Au–Cu alloy fabricated by LRS method. It is considered that the precipitation of the fine L10-type-ordered β′ phase may contribute strongly to the unique hardening in the as-solutionized dental Ag–Pd–Au–Cu alloy fabricated by

  19. Parameters Optimization of Plasma Hardening Process Using Genetic Algorithm and Neural Network

    Institute of Scientific and Technical Information of China (English)

    LIU Gu; WANG Liu-ying; CHEN Gui-ming; HUA Shao-chun

    2011-01-01

    Plasma surface hardening process was performed to improve the performance of the AISI 1045 carbon steel.Experiments were carried out to characterize the hardening qualities.A predicting and optimizing model using genetic algorithm-back propagation neural network(GA-BP) was developed based on the experimental results.The non-linear relationship between properties of hardening layers and process parameters was established.The results show that the GA-BP predicting model is reliable since prediction results are in rather good agreement with measured results.The optimal properties of the hardened layer were deduced from GA.And through multi optimizations,the optimum comprehensive performances of the hardened layer were as follows:plasma arc current is 90 A,hardening speed is 2.2 m/min,plasma gas flow rate is 6.0 L/min and hardening distance is 4.3 mm.It concludes that GA-BP mode developed in this study provides a promising method for plasma hardening parameters prediction and optimization.

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

    International Nuclear Information System (INIS)

    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)

  1. Microstructure in hardened cement pastes measured by mercury intrusion porosimetry and low temperature microcalorimetry

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Baroghel, V.B.; Künzel, H.M.

    1996-01-01

    Cumulated pore size distributions for hardened cement pastes measured by mercury intrusion porosimetry from two laboratories and low temperature microcalorimetry from one laboratory are presented.......Cumulated pore size distributions for hardened cement pastes measured by mercury intrusion porosimetry from two laboratories and low temperature microcalorimetry from one laboratory are presented....

  2. Simulation aided hardening of N-channel power MOSFETs to prevent single event burnout

    International Nuclear Information System (INIS)

    2D MEDICI simulator is used to investigate hardening solutions to single-event burnout (SEB). SEB parametric dependencies such as carrier lifetime reduction, base enlargement, and emitter doping decrease have been verified and a p+ plug modification approach for SEB hardening of power MOSFETs is validated with simulations on actual device structures

  3. Plant resistance to cold stress: Mechanisms and environmental signals triggering frost hardening and dehardening

    Indian Academy of Sciences (India)

    Erwin H Beck; Richard Heim; Jens Hansen

    2004-12-01

    This introductory overview shows that cold, in particular frost, stresses a plant in manifold ways and that the plant’s response, being injurious or adaptive, must be considered a syndrome rather than a single reaction. In the course of the year perennial plants of the temperate climate zones undergo frost hardening in autumn and dehardening in spring. Using Scots pine (Pinus sylvestris L.) as a model plant the environmental signals inducing frost hardening and dehardening, respectively, were investigated. Over 2 years the changes in frost resistance of Scots pine needles were recorded together with the annual courses of day-length and ambient temperature. Both act as environmental signals for frost hardening and dehardening. Climate chamber experiments showed that short day-length as a signal triggering frost hardening could be replaced by irradiation with far red light, while red light inhibited hardening. The involvement of phytochrome as a signal receptor could be corroborated by respective night-break experiments. More rapid frost hardening than by short day or far red treatment was achieved by applying a short period (6 h) of mild frost which did not exceed the plant’s cold resistance. Both types of signals were independently effective but the rates of frost hardening were not additive. The maximal rate of hardening was – 0.93°C per day and frost tolerance of < – 72°C was achieved. For dehardening, temperature was an even more effective signal than day-length.

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

    DEFF Research Database (Denmark)

    Pantleon, W.

    2005-01-01

    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...

  5. An experimental study on the estimation of the strength of hardened concrete

    International Nuclear Information System (INIS)

    The need to asses the strength of hardened concrete in an existing structure can arise from a variety of reasons, especially such as doubt of non-destructive test methods. According the study aims at suggesting the practical basic material through sampling the concrete conveyed to the construction site by mixer truck shortly before its placing, employing the non-destructive test methods and the location surveying compressive strength test methods with regard to the compressive strength of the concrete after 28 days of age passed after the placing of concrete, securing the uniformity of concrete structure, and comparing and analyzing the difference between the non-destructive test methods and the location surveying compressive strength. The test was conducted in the following methods at the concrete placing work on the real site, as the test able among several factors which execute on effect on compressive strength in this study. Used concrete was the Remicon product of A company, and cured until 28 days of aging by water curing, drawing up the standard cylinder specimen on The construction site. The estimated formula of the compressive strength, in accordance with the results of the experiments conducted by the Schmidt Hammer test method and the ultrasonics pulse velocity test method, Air Exclusion Test method are as follows : (1) Schmidt Hammer Test Method Fc = 16.75R - 325.5 (2) Ultra Sonic Test Method Fc = 277.22VP - 846.78 (3) Concrete Air Exclusion Rating Table.

  6. Hardening cookies in web-based systems for better system integrity

    International Nuclear Information System (INIS)

    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)

  7. 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. Disorie...... 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.......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...

  8. Microstructure and Properties of Ti and Ti+Nb Ultra-Low-Carbon Bake Hardened Steels

    Institute of Scientific and Technical Information of China (English)

    CHEN Ji-ping; KANG Yong-lin; HAO Ying-min; LIU Guang-ming; XIONG Ai-ming

    2009-01-01

    Hot rolling, cold rolling and continuous annealing processes of Ti bearing and Ti+ Nb stabilized ultra-low-carbon bake hardened steels were experimentally studied. The microstrueture and texture evolution, as well as the morphology, size and distribution of second phase precipitates during hot roiling, cold rolling and continuous annea-ling were also analyzed. The results showed that the size of NbC precipitates in Ti+ Nb stabilized ultra-low-carbon bake hardened steel was smaller than that of TiC precipitates in Ti bearing ultra-low-carbon bake hardened steel, which made the average grain size of Ti+ Nb stabilized ultra-low-carbon bake hardened steel finer than that of Ti bearing ultra-low-carbon bake hardened steel; for the yield strength, the former was higher than the latter; but for the γ value which reflects the deep-drawing performance, the former was lower than the latter.

  9. 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.

  10. Evaluation of Springback for DP980 S Rail Using Anisotropic Hardening Models

    Science.gov (United States)

    Choi, Jisik; Lee, Jinwoo; Bae, Gihyun; Barlat, Frederic; Lee, Myoung-Gyu

    2016-07-01

    The effect of anisotropic hardening models on springback of an S-rail part was investigated. Two advanced constitutive models based on distortional and kinematic hardening, which captured the Bauschinger effect, transient hardening, and permanent softening during strain path change, were implemented in a finite element (FE) code. In-plane compression-tension tests were performed to identify the model parameters. The springback of the S-rail after forming a 980 MPa dual-phase steel sheet sample was measured and analyzed using different hardening models. The comparison between experimental and FE results demonstrated that the advanced anisotropic hardening models, which are particularly suitable for non-proportional loading, significantly improved the springback prediction capability of an advanced high strength steel.

  11. The effect of cyclic hardening on fatigue properties of modified asphalt

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The phenomenon of cyclic hardening is observed in fatigue tests of modified asphalt controlled by low strain/stress level and it is not clear how the phenomenon affects the fatigue properties of binders. The special time weep tests were performed to investigate the point. Tests results indicate that the cyclic hardening is caused by the rearrangement of molecules in binders, and it can make the inner structure of binders getting stable and increase the fatigue properties of asphalt binders. But fatigue damage occurs when fatigue tests start, no matter the phenomenon of cyclic hardening happens or not. If the controlled load is low, the effect of rearrangement of molecules on material is beyond the effect of fatigue damage so that the cyclic hardening can be observed. When the load conditions get worse, the effect of slight fatigue damages produced in hardening stage will show.

  12. Laser transformation hardening on rod-shaped carbon steel byGaussian beam

    Institute of Scientific and Technical Information of China (English)

    Jong-Do KIM; Myeong-Hoon LEE; Su-Jin LEE; Woon-Ju KANG

    2009-01-01

    Laser transformation hardening(LTH) is one of the laser surface modification processes. The surface hardening of rod-shaped carbon steel (SM45C) was performed by lathe-based laser composite processor with Gaussian-beam optical head. The LTH characteristics by dominant processes, longitudinal and depth directional hardness distributions and behaviors of phase transformation in hardened zones were examined. Especially, two concepts of circumferential speed and theoretical overlap rate were applied. When laser power increased or circumferential speed decreased, the surface hardening depth gradually increases due to the increased heat input. Moreover, the longitudinal hardness distribution particularly shows periodicity of repetitive increase and decrease, which results from tempering effect by overlap. Finally, the feasibility of laser transformation hardening is verified by using the beam with Gaussian intensity distribution.

  13. Quenching and hardening in the transverse quasi-elastic peak

    International Nuclear Information System (INIS)

    We study in the RPA framework the response of symmetric, infinite nuclear matter to a spin-isospin sensitive probe with both σ.q and σ.xq couplings. The two responses, similar in the low-q region, differ markedly for moderate momenta (>=1fm-1). Indeed, whereas the longitudinal one displays a softening and an enhancement (due to the attractive character of the associated particle-hole force), the transverse response is quenched and hardened with respect to the free Fermi gas. The existing experimental data, which we analyze, are compatible with our results. We also explore the total strengths and find that for repulsive forces they are appreciably reduced by the RPA correlations. Large part of this quenching comes from the Δ excitation (LLEE effect), but some reduction is still present even when the nucleonic degrees of freedom are neglected. This illustrates a violation of strength conservation brougth about by the RPA correlations in the spin-isospin channel

  14. Radiation Hardened NULL Convention Logic Asynchronous Circuit Design

    Directory of Open Access Journals (Sweden)

    Liang Zhou

    2015-10-01

    Full Text Available This paper proposes a radiation hardened NULL Convention Logic (NCL architecture that can recover from a single event latchup (SEL or single event upset (SEU fault without deadlock or any data loss. The proposed architecture is analytically proved to be SEL resistant, and by extension, proved to be SEU resistant. The SEL/SEU resistant version of a 3-stage full-word pipelined NCL 4 × 4 unsigned multiplier was implemented using the IBM cmrf8sf 130 nm 1.2 V process at the transistor level and simulated exhaustively with SEL fault injection to validate the proposed architectures. Compared with the original version, the SEL/SEU resilient version has 1.31× speed overhead, 2.74× area overhead, and 2.79× energy per operation overhead.

  15. VIRTUAL PROCESSING OF LASER SURFACE HARDENING ON AUTOBODY DIES

    Institute of Scientific and Technical Information of China (English)

    ZHANG Taohong; YU Gang; WANG Jianlun; LIU Xiangyang

    2006-01-01

    A new method of collision-free path plan integrated in virtual processing is developed to improve the efficiency of laser surface hardening on dies. The path plan is based on the premise of no collision and the optimization object is the shortest path. The optimization model of collision-free path is built from traveling salesman problem (TSP). Collision-free path between two machining points is calculated in configuration space (C-Space). Ant colony optimization (ACO) algorithm is applied to TSP of all the machining points to find the shortest path, which is simulated in virtual environment set up by IGRIP software. Virtual machining time, no-collision report, etc, are put out after the simulation. An example on autobody die is processed in the virtual platform, the simulation results display that ACO has perfect optimization effect, and the method of virtual processing with integration of collision-free optimal path is practical.

  16. A plastic damage model with stress triaxiality-dependent hardening

    International Nuclear Information System (INIS)

    Emphases of this study were placed on the modelling of plastic damage behaviour of prestressed structural concrete, with special attention being paid to the stress-triaxiality dependent plastic hardening law and the corresponding damage evolution law. A definition of stress triaxiality was proposed and introduced in the model presented here. Drucker-Prager -type plasticity was adopted in the formulation of the plastic damage constitutive equations. Numerical validations were performed for the proposed plasticity-based damage model with a driver subroutine developed in this study. The predicted stress-strain behaviour seems reasonably accurate for the uniaxial tension and uniaxial compression compared with the experimental data reported in references. Numerical calculations of compressions under various hydrostatic stress confinements were carried out in order to validate the stress triaxiality dependent properties of the model. (authors)

  17. An Oxygen-Permeation Treatment for Hardening Titanium Alloys

    Institute of Scientific and Technical Information of China (English)

    MA Hong-yan; WANG Mao-cai; WEI Zheng; XIN Gong-chun

    2004-01-01

    In this paper, the characterization of oxygen permeation (OP) in titanium alloy TC11 at high temperature and the influence of oxygen solution layer on performances of substrate were characterized with the help of apparatus, such as TGA,SEM/EDAX, XRD, EPMA, Micro-hardness Tester, Two-body Abrasion Tester, Amsler Wear Test Machine, Potentiostat/Galvanostat Model 273 system. The results showed that there was a little shift in X-ray diffraction peaks of α and β phase during the OPT process as a result of oxygen solution. The OP treatment can significantly increase the surface hardness of titanium alloys and, accordingly, the abrasive wear resistance was improved. Titanium alloys with oxygen solution layer exhibited improved corrosion resistance both in 3.5 % NaCl and in 5 % HCl solution. Oxidation resistance of TC11 with oxygen solution layer at high temperature was also enhanced. The solution and hardening mechanisms were discussed based on the experimental results.

  18. Analysis of fracture toughness of explosion-hardened martensitic steel

    Science.gov (United States)

    Moskvitina, L. V.

    2015-10-01

    In this work we study a shift of the following nonlinear states: tempering + abatement + 10 GPa shock loading + welding thermocycle. As a result the self-organized HAZ metal structure with elements of self-similarity on different scales is found. The fractal analysis shows how formed defects affect the HAZ metal hardness of 14H2GMR steel with the martensitic structure of static fracture. The statistical analysis of stereometric parameters of fracture shows a higher energy intensity of static fracture in specimens treated by explosion. The multifractal analysis reveals hardness of the grid dislocation structure induced by explosion in the air-hardening zone. The homogeneity of the dislocation structure related to carbides increases the resistance of HAZ metal of static fracture.

  19. Thermal Hardening: A New Seed Vigor Enhancement Tool in Rice

    Institute of Scientific and Technical Information of China (English)

    Muhammad FAROOQ; S. M. A. BASRA; Nazir AHMAD; K. HAFEEZ

    2005-01-01

    In a laboratory study, indica and japonica rice (Oryza sativa L.) seeds were exposed to thermal hardening (heating followed by chilling followed by heating; chilling followed by heating followed by chilling; heating followed by chilling or chilling followed by heating). In indica rice, heating followed by chilling followed by heating resulted in decreased mean germination time, time to start germination, electrical conductivity of seed leachates, and time to 50% germination, as well as increased germination index, energy of germination, radicle and plumule length, root length, root/shoot ratio, root fresh and dry weight, radicle and plumule growth rate, and shoot fresh weight. In japonica rice, chilling followed by heating followed by chilling performed better than all other treatments, including control.

  20. The influence of limited kinematic hardening in shakedown analysis

    International Nuclear Information System (INIS)

    The use of the Design by Analysis concept is a trend in modern pressure vessel and piping calculations. DBA flexibility allow us to deal with unexpected configurations detected at in-service inspections. It is also important, in life extension calculations, when deviations of the original standard hypothesis adopted initially in Design by Formula, can happen. To apply the DBA to structures under variable mechanic and thermal loads, it is necessary that, alternate plasticity and incremental collapse (with instantaneous plastic collapse as a particular case), be precluded. These are two basic failure modes considered by ASME or European Standards in DBA. The shakedown theory is the tool available to achieve this goal. In order to apply it, is necessary only the range of the variable loads and the material properties. Precise, robust and efficient algorithms to solve the very large nonlinear optimization problems generated in numerical applications of the shakedown theory is a recent achievement. Zouain and co-workers developed one of these algorithms for elastic ideally-plastic materials. But, it is necessary to consider more realistic material properties in real practical applications. This paper shows an enhancement of this algorithm to dealing with limited kinematic hardening, a typical property of the usual steels. This is done using internal thermodynamic variables. A discrete algorithm is obtained using a plane stress, mixed finite element, with internal variable. An example, a beam encased in an end, under constant axial force and variable moment is presented to show the importance of considering the limited kinematic hardening in a shakedown analysis. (author)

  1. How to monitor the modulus of elasticity of concrete, automatically since the earliest age?

    OpenAIRE

    Boulay, Claude; Staquet, Stéphanie; DELSAUTE, Brice; CARETTE, Jérôme; Crespini, Michela; YAZOGHLI MARZOUK, O; MERLIOT, Érick; RAMANICH, Sandrine

    2014-01-01

    Monitoring the evolution of an early age set of parameters on concrete is necessary to predict the early age behaviour of structures. The difficulty lies in the fact that this monitoring must be automatic because the concrete hardening process takes place over a long period after the casting. This paper presents a new methodology and an apparatus, specifically designed at IFSTTAR, to monitor the hardening process of a concrete. Mainly, the Young's modulus can be monitored in compression. M...

  2. Development of a Press-Hardened Steel Suitable for Thin Slab Direct Rolling Processing

    Science.gov (United States)

    Lee, Jewoong; De Cooman, Bruno C.

    2015-01-01

    The thin slab casting and direct rolling process is a hot-rolled strip production method which has maintained commercial quality steel grades as a major material in many industrial applications due to its low processing cost. Few innovative products have however been developed specifically for production by thin slab direct rolling. Press hardening or hot press forming steel grades which are now widely used to produce structural automotive steel parts requiring ultra-high strength and formability may however offer an opportunity for thin slab direct rolling-specific ultra-high strength products. In this work, a newly designed press hardening steel grade developed specifically for thin slab direct rolling processing is presented. The press hardening steel has a high nitrogen content compared with press hardening steel grades produced by conventional steelmaking routes. Boron and titanium which are key alloying additions in conventional press hardening steel such as the 22MnB5 press hardening steel grade are not utilized. Cr is added in the press hardening steel to obtain the required hardenability. The properties of the new thin slab direct rolling-specific 22MnCrN5 press hardening steel grade are reviewed. The evolution of the microstructure and mechanical properties with increasing amounts of Cr additions from 0.6 to 1.4 wt pct and the effect of the cooling rate during die-quenching were studied by means of laboratory simulations. The selection of the optimum chemical composition range for the thin slab direct rolling-specific 22MnCrN5 steel in press hardening heat treatment conditions is discussed.

  3. The effect of Ca and RE elements on the precipitation kinetics of Mg17Al12 phase during artificial aging of magnesium alloy AZ91

    International Nuclear Information System (INIS)

    Highlights: → Ca and RE elements decrease the precipitation rate during aging of AZ91 alloy. → Precipitation kinetics and mechanism during aging of the alloys were studied. → Effect of Ca and RE on creep properties of age hardened AZ91 alloy was studied. - Abstract: The effect of simultaneous alloying with Ca and rare earth (RE) elements on the age hardening kinetics of AZ91 was studied through the fitting of the Johnson-Mehl-Avrami (JMA) equation. The results showed that the addition of both Ca and RE elements not only suppress discontinuous precipitation of the Mg17Al12 phase during the age hardening process, but also decrease the alloy hardness. Fitting the JMA equation to the experimental data indicated that the phase transformation during age hardening of an alloy variant containing both Ca and RE (at 170 deg. C and 190 deg. C) and standard AZ91 (at 170 deg. C) takes place by the nucleation of precipitates on dislocations. In contrast, the precipitation during age hardening of AZ91 at 190 deg. C occurs via nucleation at grain boundaries. Although it was observed that the creep strength of age hardened specimens are lower than that of the as cast specimens, but age hardening treatment has lower deleterious influence on the creep resistance of the alloy containing Ca and RE in comparison with conventional AZ91. This may be ascribed to the decreased precipitation rate resulting from the addition of both Ca and RE elements.

  4. On the nature of hardening of high nitrogen steels on the basis of iron-chromium-manganese austenite

    International Nuclear Information System (INIS)

    A study is made into the efficiency of hardening in steels Kh17AG18 and Kh17AG18F with evaluating the contribution of solid solution, precipitation or strain hardening mechanisms. It is shown, that cold deformation makes the highest contribution to the hardening of high nitrogen steels

  5. 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.

  6. Surface hardening characteristics of aluminium bronze for marine propeller; Senpaku propeller yo aluminium seido no hyomen koka tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Kawazoe, T. [Nagasaki University, Nagasaki (Japan). Faculty of Engineering; Furukawa, T.; Kanda, K.; Nishikido, S. [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)

    1997-05-25

    With a marine propeller material AlBC3 as the object of discussion, three kinds of surface hardening tests and a cavitation erosion test were carried out to investigate the relationship among hardenability, microstructures and erosion resistance. Surface hardness of each hardened material was found about 1.5 times greater for water-sprayed flame hardening, about 1.6 times greater for laser hardening, and about 1.3 times greater for high-frequency hardening than that of as-cast materials. The hardness is closely related with the microstructures. In the flame hardening, a hard ({beta}+{beta}prime) phase is distributed in a great quantity on the surface, and the occupying ratio of a soft {alpha} phase increases as the depth increases. In the laser hardening, a micronized {beta} phase is distributed all over the surface, contributing to increase in the surface hardness. Weight loss in the flame-hardened materials due to erosion has stayed at about 35% of that for as-cast materials, showing improvement in the erosion resistance. If the surface hardening process verified by the present test is applied to production propellers, the water-sprayed flame hardening process is thought most suitable when the surface hardness, hardened layer thickness and workability are considered. 8 refs., 17 figs., 4 tabs.

  7. Microstructural evolution and mechanical behaviour of surface hardened low carbon hot rolled steel

    Energy Technology Data Exchange (ETDEWEB)

    Tewary, N.K. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Syed, B. [R and D Division, Tata Steel Limited, Jamshedpur 831007 (India); Ghosh, S.K., E-mail: skghosh@metal.becs.ac.in [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Kundu, S. [R and D Division, Tata Steel Limited, Jamshedpur 831007 (India); Shariff, S.M.; Padmanabham, G. [Centre for Laser Processing, ARCI-Hyderabad, Balapur PO, AP 500005 (India)

    2014-06-01

    Surface hardening of low carbon hot rolled C–Mn steel has been successfully performed by high power diode laser with an achievable case depth of about 300 μm. The laser treated samples have been characterised using optical microscope, scanning electron microscope, transmission electron microscope, and X-ray diffraction techniques. Higher hardness level is achieved in laser surface hardened zone (≈300 HV) than in the base alloy region (≈140 HV). The variation in hardness as a function of distance across the laser tracks is observed during multi-track laser hardening. Laser hardened steel sheets show enhanced mechanical strength (YS: 383–443 MPa, UTS: 476–506 MPa) with the lowering of percentage total elongation (23–28%) compared to the base alloy (YS: 351 MPa, UTS: 450 MPa and total elongation is 32%). Strain hardening exponent (‘n’) has been evaluated from true tensile stress–strain diagram and it shows a similar nature for both base alloy and laser treated steels. The microstructure in the base alloy region consists of a mixture of ferrite and pearlite, whereas predominantly lath martensite is present in the laser hardened surface layer. The improvement of mechanical strength is discussed in terms of the formation of this hardened layer on the surface.

  8. 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.

  9. Microstructural evolution and mechanical behaviour of surface hardened low carbon hot rolled steel

    International Nuclear Information System (INIS)

    Surface hardening of low carbon hot rolled C–Mn steel has been successfully performed by high power diode laser with an achievable case depth of about 300 μm. The laser treated samples have been characterised using optical microscope, scanning electron microscope, transmission electron microscope, and X-ray diffraction techniques. Higher hardness level is achieved in laser surface hardened zone (≈300 HV) than in the base alloy region (≈140 HV). The variation in hardness as a function of distance across the laser tracks is observed during multi-track laser hardening. Laser hardened steel sheets show enhanced mechanical strength (YS: 383–443 MPa, UTS: 476–506 MPa) with the lowering of percentage total elongation (23–28%) compared to the base alloy (YS: 351 MPa, UTS: 450 MPa and total elongation is 32%). Strain hardening exponent (‘n’) has been evaluated from true tensile stress–strain diagram and it shows a similar nature for both base alloy and laser treated steels. The microstructure in the base alloy region consists of a mixture of ferrite and pearlite, whereas predominantly lath martensite is present in the laser hardened surface layer. The improvement of mechanical strength is discussed in terms of the formation of this hardened layer on the surface

  10. Analysis of Obstacle Hardening Models Using Dislocation Dynamics: Application to Irradiation-Induced Defects

    Science.gov (United States)

    Sobie, Cameron; Bertin, Nicolas; Capolungo, Laurent

    2015-08-01

    Irradiation hardening in -iron represents a critical factor in nuclear reactor design and lifetime prediction. The dispersed barrier hardening, Friedel Kroupa Hirsch (FKH), and Bacon Kocks Scattergood (BKS) models have been proposed to predict hardening caused by dislocation obstacles in metals, but the limits of their applicability have never been investigated for varying defect types, sizes, and densities. In this work, dislocation dynamics calculations of irradiation-induced obstacle hardening in the athermal case were compared to these models for voids, self-interstitial atom (SIA) loops, and a combination of the two types. The BKS model was found to accurately predict hardening due to voids, whereas the FKH model was superior for SIA loops. For both loops and voids, the hardening from a normal distribution of defects was compared to that from the mean size, and was shown to have no statistically significant dependence on the distribution. A mean size approach was also shown to be valid for an asymmetric distribution of voids. A non-linear superposition principle was shown to predict the hardening from the simultaneous presence of voids and SIA loops.

  11. Non Radiation Hardened Microprocessors in Spaced Based Remote Sensing Systems

    Science.gov (United States)

    Decoursey, Robert J.; Estes, Robert F.; Melton, Ryan

    2006-01-01

    The CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) mission is a comprehensive suite of active and passive sensors including a 20Hz 230mj Nd:YAG lidar, a visible wavelength Earth-looking camera and an imaging infrared radiometer. CALIPSO flies in formation with the Earth Observing System Post-Meridian (EOS PM) train, provides continuous, near-simultaneous measurements and is a planned 3 year mission. CALIPSO was launched into a 98 degree sun synchronous Earth orbit in April of 2006 to study clouds and aerosols and acquires over 5 gigabytes of data every 24 hours. The ground track of one CALIPSO orbit as well as high and low intensity South Atlantic Anomaly outlines is shown. CALIPSO passes through the SAA several times each day. Spaced based remote sensing systems that include multiple instruments and/or instruments such as lidar generate large volumes of data and require robust real-time hardware and software mechanisms and high throughput processors. Due to onboard storage restrictions and telemetry downlink limitations these systems must pre-process and reduce the data before sending it to the ground. This onboard processing and realtime requirement load may mean that newer more powerful processors are needed even though acceptable radiation-hardened versions have not yet been released. CALIPSO's single board computer payload controller processor is actually a set of four (4) voting non-radiation hardened COTS Power PC 603r's built on a single width VME card by General Dynamics Advanced Information Systems (GDAIS). Significant radiation concerns for CALIPSO and other Low Earth Orbit (LEO) satellites include the South Atlantic Anomaly (SAA), the north and south poles and strong solar events. Over much of South America and extending into the South Atlantic Ocean the Van Allen radiation belts dip to just 200-800km and spacecraft entering this area are subjected to high energy protons and experience higher than normal Single Event Upset

  12. Reducing beam hardening effects and metal artefacts using Medipix3RX: With applications from biomaterial science

    CERN Document Server

    Rajendran, K; de Ruiter, N J A; Chernoglazov, A I; Panta, R K; Butler, A P H; Butler, P H; Bell, S T; Anderson, N G; Woodfield, T B F; Tredinnick, S J; Healy, J L; Bateman, C J; Aamir, R; Doesburg, R M N; Renaud, P F; Gieseg, S P; Smithies, D J; Mohr, J L; Mandalika, V B H; Opie, A M T; Cook, N J; Ronaldson, J P; Nik, S J; Atharifard, A; Clyne, M; Bones, P J; Bartneck, C; Grasset, R; Schleich, N; Billinghurst, M

    2014-01-01

    This paper discusses methods for reducing beam hardening effects using spectral data for biomaterial applications. A small-animal spectral scanner operating in the diagnostic energy range was used. We investigate the use of photon-processing features of the Medipix3RX ASIC in reducing beam hardening and associated artefacts. A fully operational charge summing mode was used during the imaging routine. We present spectral data collected for metal alloy samples, its analysis using algebraic 3D reconstruction software and volume visualisation using a custom volume rendering software. Narrow high energy acquisition using the photon-processing detector revealed substantial reduction in beam hardening effects and metal artefacts.

  13. Influence of Cultivar on the Postharvest Hardening of Trifoliate Yam (Dioscorea dumetorum) Tubers

    OpenAIRE

    Siadjeu, Christian; Akdowa Panyoo, Emmanuel; Mahbou Somo Toukam, Gabriel; Bell, Joseph Martin; Nono, Benoit; Medoua, Gabriel Nama

    2016-01-01

    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 p...

  14. 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.

  15. Strain-hardening and warm deformation behaviors of extruded Mg–Sn–Yb alloy sheet

    OpenAIRE

    Jing Jiang; Guangli Bi; Guoyong Wang; Qing Jiang; Jianshe Lian; Zhonghao Jiang

    2014-01-01

    Strain-hardening and warm deformation behaviors of extruded Mg–2Sn–0.5Yb alloy (at.%) sheet were investigated in uniaxial tensile test at temperatures of 25–250 °C and strain rates of 1 × 10−3 s−1–0.1 s−1. The data fit with the Kocks–Mecking type plots were used to show different stages of strain hardening. Besides III-stage and IV-stage, the absence of the II-stage strain hardening at room temperature should be related to the sufficient dynamic recrystallization during extrusion. The decreas...

  16. Influence on corrosion resistance of superficial strain hardening of parts made of austenitic stainless steels

    International Nuclear Information System (INIS)

    Reactivity of strain hardened stainless steel 18-10 and 18-10 Mo in oxidizing media is very different at the surface and in the metal core. Surface corrosion or protection is very sensitive to superficial strain hardening resulting of mechanical treatments. Three physical phenomena are directly strain hardening dependent and have important consequences on corrosion resistance: 1) increase of diffusion rate of the different alloy elements, especially chromium; 2) residual superficial strain influence on stress corrosion and 3) structural transformation of metastable austenite

  17. Orowan strengthening and forest hardening superposition examined by dislocation dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Queyreau, Sylvain, E-mail: sylvain.queyreau@gmail.com [EDF-R and D, Department MMC, Avenue des Renardieres, 77818 Moret-sur-loing (France)] [Laboratoire d' Etude des Microstructures, CNRS-ONERA, 29 Avenue de la Division Leclerc, BP 72, 92322 Chatillon Cedex (France); Monnet, Ghiath [EDF-R and D, Department MMC, Avenue des Renardieres, 77818 Moret-sur-loing (France); Devincre, Benoit [Laboratoire d' Etude des Microstructures, CNRS-ONERA, 29 Avenue de la Division Leclerc, BP 72, 92322 Chatillon Cedex (France)

    2010-10-15

    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.

  18. Model and numerical analysis of mechanical phenomena of tools steel hardening

    Directory of Open Access Journals (Sweden)

    A. Bokota

    2010-01-01

    Full Text Available This paper the model hardening of tool steel takes into considerations of mechanical phenomena is presented. Fields stresses and strains are obtained from solutions by FEM equilibrium equations in rate form. The stresses generated during hardening were assumed to result from thermal load, structural deformation, and plastic deformation and transformation plasticity. Thermophysical values in the constitutive relations are depended upon both the temperature and the phase composition. Condition Huber-Misses with the isotropic strengthening for the creation of plastic strains is used. However model Leblond to determined transformations plasticity applied. The analysis of stresses associated of the elements hardening made of tool steel was done.

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

    International Nuclear Information System (INIS)

    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 9500C 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)

  20. Ultrasonic testing of the hardening kinetics of epoxy resins used for foundry patterns

    OpenAIRE

    J. Zych

    2010-01-01

    The study presents the results of investigations on the hardening kinetics of modern pattern materials which, among others, include alsoepoxy resins. Tests were carried out using a new ultrasonic technique developed by the author of the present study. On the example of theEPO 999 resin, the run of the hardening process at temperatures of 10, 20 and 30oC was shown. This is the temperature range appliedduring production of foundry patterns. The time of the preliminary hardening amounted to 800 ...

  1. Measurement of irradiation effects in precipitate hardened aluminum using nonlinear ultrasonic principles (in-situ)

    Science.gov (United States)

    Reinhardt, B. T.; Parks, D. A.; Tittmann, B. R.

    2012-05-01

    Currently nuclear power plants are reaching the end of their initial design life. Yet, in order to meet the energy demands, twenty year extensions have been granted to many nuclear reactor facilities. These extensions will be ending by the year 2035, leaving a large gap in the available energy supply. In order to extend the life of these facilities it will imperative to develop techniques capable detecting damage in the aging nuclear facilities. However, the high temperature and high neutron flux environment limits the materials available for use in the nuclear reactor. Because of this limitation little NDE based inspection has been implemented in high radiation environments. Yet recent developments in the understanding of Aluminum Nitride (AlN) piezoelectric sensors high temperature and radiation dependent behavior have opened the door for in-situ experimentation. An experiment was designed to monitor the propagation of an ultrasonic wave in a precipitate hardened aluminum specimen while being subjected to radiation at the Pennsylvania State Universities Breazeale Reactor. Measurements of harmonic generation were made up to 1.85×1018 fluence with significant spectral difference between the pre-irradiated state and the post irradiated state. The connection between micro-structural material changes and harmonic measurements are addressed.

  2. Magnetic hardening of Fe30Co70 nanowires

    Science.gov (United States)

    Liébana Viñas, Sara; Salikhov, Ruslan; Bran, Cristina; Palmero, Ester M.; Vazquez, Manuel; Arvan, Behnaz; Yao, Xiang; Toson, Peter; Fidler, Josef; Spasova, Marina; Wiedwald, Ulf; Farle, Michael

    2015-10-01

    3d transition metal-based magnetic nanowires (NWs) are currently considered as potential candidates for alternative rare-earth-free alloys as novel permanent magnets. Here, we report on the magnetic hardening of Fe30Co70 nanowires in anodic aluminium oxide templates with diameters of 20 nm and 40 nm (length 6 μm and 7.5 μm, respectively) by means of magnetic pinning at the tips of the NWs. We observe that a 3-4 nm naturally formed ferrimagnetic FeCo oxide layer covering the tip of the FeCo NW increases the coercive field by 20%, indicating that domain wall nucleation starts at the tip of the magnetic NW. Ferromagnetic resonance (FMR) measurements were used to quantify the magnetic uniaxial anisotropy energy of the samples. Micromagnetic simulations support our experimental findings, showing that the increase of the coercive field can be achieved by controlling domain wall nucleation using magnetic materials with antiferromagnetic exchange coupling, i.e. antiferromagnets or ferrimagnets, as a capping layer at the nanowire tips.

  3. Surface finishing and levelling of thermomechanically hardened rolled steel

    International Nuclear Information System (INIS)

    The finishing of high-strength merchant shapes from alloy steel was tried out under industrial conditions with the equipment of metallurgical plants. After thermomechanical hardening in the production line of the rolling mill, 30KhGSN2A and 40Kh1NVA steel rounds 32 and 31 mm in diameter were straightened on a two-roller straightening machine designed by the All-Union Scientific Research Institute for Metallurgical Machinery (VNII Metmash). This made possible subsequent turning and grinding of the rods. The conditions of straightening, turning and grinding have been worked so as to obtain thermomechanically strengthened and ground rolled products approximating the gauged and ground metal in shape geometry and surface finish. It is shown that the labour-consuming operation of turning can be eliminated by reducing the machining pass of the rolled product, and this lowers the labour required for the finishing operations by 75%. After grinding with 40- and 25-grain abrasive wheels, high strength rolled shapes were obtained with a diameter of 30-0.20 mm and a surface finish of class 6-5 satisfying the technical specifications. (author)

  4. Radiation hardened high efficiency silicon space solar cell

    International Nuclear Information System (INIS)

    A silicon solar cell with AMO 19% Beginning of Life (BOL) efficiency is reported. The cell has demonstrated equal or better radiation resistance when compared to conventional silicon space solar cells. Conventional silicon space solar cell performance is generally ∼ 14% at BOL. The Radiation Hardened High Efficiency Silicon (RHHES) cell is thinned for high specific power (watts/kilogram). The RHHES space cell provides compatibility with automatic surface mounting technology. The cells can be easily combined to provide desired power levels and voltages. The RHHES space cell is more resistant to mechanical damage due to micrometeorites. Micro-meteorites which impinge upon conventional cells can crack the cell which, in turn, may cause string failure. The RHHES, operating in the same environment, can continue to function with a similar crack. The RHHES cell allows for very efficient thermal management which is essential for space cells generating higher specific power levels. The cell eliminates the need for electrical insulation layers which would otherwise increase the thermal resistance for conventional space panels. The RHHES cell can be applied to a space concentrator panel system without abandoning any of the attributes discussed. The power handling capability of the RHHES cell is approximately five times more than conventional space concentrator solar cells

  5. Surface hardening of two cast irons by friction stir processing

    International Nuclear Information System (INIS)

    The Friction Stir Processing (FSP) was applied to the surface hardening of cast irons. Flake graphite cast iron (FC300) and nodular graphite cast iron (FCD700) were used to investigate the validity of this method. The matrices of the FC300 and FC700 cast irons are pearlite. The rotary tool is a 25mm diameter cylindrical tool, and the travelling speed was varied between 50 and 150mm/min in order to control the heat input at the constant rotation speed of 900rpm. As a result, it has been clarified that a Vickers hardness of about 700HV is obtained for both cast irons. It is considered that a very fine martensite structure is formed because the FSP generates the heat very locally, and a very high cooling rate is constantly obtained. When a tool without an umbo (probe) is used, the domain in which graphite is crushed and striated is minimized. This leads to obtaining a much harder sample. The hardness change depends on the size of the martensite, which can be controlled by the process conditions, such as the tool traveling speed and the load. Based on these results, it was clarified that the FSP has many advantages for cast irons, such as a higher hardness and lower distortion. As a result, no post surface heat treatment and no post machining are required to obtain the required hardness, while these processes are generally required when using the traditional methods.

  6. Radiation-hardened field coils for FMIT quadrupoles

    International Nuclear Information System (INIS)

    Modern accelerators of the Fusion Materials Irradiation Test (FMIT) class deliver enormous power onto their targets. The high beam currents of such machines produce highly activating radiation fields from beam/target interaction and normal beam losses. The 100-mA deuteron beam from the FMIT accelerator produces a backstreaming fast-neutron flux of 1011 n/s-cm2 near the target. In addition, the neutron contribution from distributed beam spill of 3 μA/m along the rest of the machine prevents the use of epoxy resin potting materials in all magnet field coils above 10-MeV beam energies. Two special techniques for radiation-hardened field coils have been developed at Los Alamos for use on the FMIT accelerator. One technique uses vitreous enamel coatings on the conductors and appears attractive for the drift-tube quadrupoles. Another method uses a thermally efficient two-layer coil design that has solid mineral-insulated (MI) conductors with indirect cooling coils, all bonded together in a lead matrix. Test results are discussed, along with applications of the quadrupoles in the FMIT facility that reduce gamma exposures during maintenance periods

  7. Magnetic hardening of Fe30Co70 nanowires.

    Science.gov (United States)

    Viñas, Sara Liébana; Salikhov, Ruslan; Bran, Cristina; Palmero, Ester M; Vazquez, Manuel; Arvan, Behnaz; Yao, Xiang; Toson, Peter; Fidler, Josef; Spasova, Marina; Wiedwald, Ulf; Farle, Michael

    2015-10-16

    3d transition metal-based magnetic nanowires (NWs) are currently considered as potential candidates for alternative rare-earth-free alloys as novel permanent magnets. Here, we report on the magnetic hardening of Fe30Co70 nanowires in anodic aluminium oxide templates with diameters of 20 nm and 40 nm (length 6 μm and 7.5 μm, respectively) by means of magnetic pinning at the tips of the NWs. We observe that a 3-4 nm naturally formed ferrimagnetic FeCo oxide layer covering the tip of the FeCo NW increases the coercive field by 20%, indicating that domain wall nucleation starts at the tip of the magnetic NW. Ferromagnetic resonance (FMR) measurements were used to quantify the magnetic uniaxial anisotropy energy of the samples. Micromagnetic simulations support our experimental findings, showing that the increase of the coercive field can be achieved by controlling domain wall nucleation using magnetic materials with antiferromagnetic exchange coupling, i.e. antiferromagnets or ferrimagnets, as a capping layer at the nanowire tips. PMID:26404670

  8. Superconducting (radiation hardened) magnets for mirror fusion devices

    International Nuclear Information System (INIS)

    Superconducting magnets for mirror fusion have evolved considerably since the Baseball II magnet in 1970. Recently, the Mirror Fusion Test Facility (MFTF-B) yin-yang has been tested to a full field of 7.7 T with radial dimensions representative of a full scale reactor. Now the emphasis has turned to the manufacture of very high field solenoids (choke coils) that are placed between the tandem mirror central cell and the yin-yang anchor-plug set. For MFTF-B the choke coil field reaches 12 T, while in future devices like the MFTF-Upgrade, Fusion Power Demonstration and Mirror Advanced Reactor Study (MARS) reactor the fields are doubled. Besides developing high fields, the magnets must be radiation hardened. Otherwise, thick neutron shields increase the magnet size to an unacceptable weight and cost. Neutron fluences in superconducting magnets must be increased by an order of magnitude or more. Insulators must withstand 1010 to 1011 rads, while magnet stability must be retained after the copper has been exposed to fluence above 1019 neutrons/cm2

  9. Password Hardened Biometric: A Complete Solution of Online Security

    Directory of Open Access Journals (Sweden)

    Ajay Sharma

    2013-05-01

    Full Text Available In present epoch, secure online access to enterprises resources is very important for any organization. To protect valuable data become one of the big challenge for today's business as enterprise customers or clients involved in business-to-customer (B2C and business-to-business (B2B e-commerce need to feel that their transactions are secured from system hackers. Biometric technology provides a solution to this problem in enterprise network security. In this article we enhance the security of online transaction using secure and unique biometric template. The uniqueness of our process is that we store biometric template and password together in encrypted form both without the fusion of score level and decision level, which leads a successful way to combine multiple technologies, different from earlier methods. Password hardened biometric system helps to generate many different secure biometric templates for the same biometric system. It also generates unique biometric templates for multiple biometric systems from the same biometric trait.

  10. Improving the duradility of the friction pair after friction hardening

    OpenAIRE

    Hurey, I.; Hurey, T.

    2013-01-01

    Проведені дослідження показали, що фрикційне зміцнення значно підвищує зносостійкість пари тертя сталь 40Х – сталь 40Х. На зносостійкість впливають отримання зміцненого нанокристалічного шару, його товщина, твердість та розмір зерна. Frictional hardening increases the wear resistance of the friction pair steel 40X - steel 40X studies have shown. Process production nanocrystalline white layer, thickness, hardness, grain size influence for wear resistence....

  11. Analysis by design of experiments of distortion potentials in drawn and induction hardened wire

    Directory of Open Access Journals (Sweden)

    Alexandre da Silva Rocha

    2012-04-01

    Full Text Available In this investigation a DoE (Design of Experiments analysis of distortion for a typical manufacturing process of pre-straightened, cold drawn and induction hardened AISI 1045 cylindrical steel bars was carried out. A careful characterization of the material, including residual stress states and geometrical changes, was done for the different manufacturing steps. In order to identify effects and correlations on distortion behavior, the investigated variables included the drawing process itself with two different drawing angles, a stress relief treatment, which was applied to one part of the samples, and, finally, induction hardening with two different case depths. Main and statistically significant effects on the distortion of the induction hardened samples were found to be in this order, the drawing angle, the stress relief treatment and the induction hardening depth. It was also found that the distortion potentials are transmitted from the drawing process to further manufacturing steps and, consequently, from one production site to the next.

  12. Investigations of high-frequency induction hardening process for piston rod of shock absorber

    Institute of Scientific and Technical Information of China (English)

    Xianhua Cheng; Qianqian Shangguan

    2005-01-01

    The microhardness of piston rods treated with different induction hardening processes was tested. The experimental results reveal that the depth of the hardened zone is proportional to the ratio of the moving speed of the piston rod to the output power of the induction generator. This result is proved correct through the Finite Element Method (FEM) simulation of the thermal field of induction heating. From tensile and impact tests, an optimized high frequency induction hardening process for piston rods has been obtained, where the output power was 82%×80 kW and the moving speed of workpiece was 5364 mm/min. The piston rods, treated by the optimized high frequency induction hardening process, show the best comprehensive mechanical performance.

  13. INSTALLATION FOR LARGE SIZE STAMP HARDENING TRANINIG BY WATER-AIR MIXTURE

    Directory of Open Access Journals (Sweden)

    L. A. Glazkov

    2009-01-01

    Full Text Available The BNTU has developed a technological process for large-size stamp hardening by means of a water-air mixture.  The  basic  requirements  imposed on an hardening  installation using  a  water-air mixture are the following: provision of smooth cooling of a part in order to achieve the required  hardness and structure; possibility of machining parts of various sizes; change of modes for machining parts of various grades of steel according to any hardness rate.The peculiar features of the given installation are: a presence of microprocessor control of water-air mixture supply, possibility of simultaneous machining of a stamp set (2 parts and position change of parts to be hardened in the process of thermal treatment.Installation for large-sized stamp hardening has been manufactured and introduced at theMinskplant of special tools and machining attachments.

  14. Equivalent Plastic Strain Gradient Plasticity with Grain Boundary Hardening and Comparison to Discrete Dislocation Dynamics

    CERN Document Server

    Bayerschen, E; Wulfinghoff, S; Weygand, D; Böhlke, T

    2015-01-01

    The gradient crystal plasticity framework of Wulfinghoff et al. [53] incorporating an equivalent plastic strain and grain boundary yielding, is extended with additional grain boundary hardening. By comparison to averaged results from many discrete dislocation dynamics (DDD) simulations of an aluminum type tricrystal under tensile loading, the new hardening parameter in the continuum model is calibrated. It is shown that although the grain boundaries (GBs) in the discrete simulations are impenetrable, an infinite GB yield strength corresponding to microhard GB conditions, is not applicable in the continuum model. A combination of a finite GB yield strength with an isotropic bulk Voce hardening relation alone also fails to model the plastic strain profiles obtained by DDD. Instead, a finite GB yield strength in combination with GB hardening depending on the equivalent plastic strain at the GBs is shown to give a better agreement to DDD results. The differences in the plastic strain profiles obtained in DDD simu...

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

    International Nuclear Information System (INIS)

    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

  16. 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.

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

    International Nuclear Information System (INIS)

    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)

  18. 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.

  19. Radiation-Hardened, Substrate-Removed, Metamorphic InGaAs Detector Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High-performance radiation-hardened metamorphic InGaAs imaging arrays sensitive from the ultraviolet (UV) through the short-wavelength infrared (SWIR) will be...

  20. Stress integration of the Drucker-Prager material model with kinematic hardening

    Directory of Open Access Journals (Sweden)

    Rakić Dragan

    2015-01-01

    Full Text Available This paper presents a method for implicit stress integration of the Drucker-Prager material model with kinematic hardening. The stress integration of the material model is conducted using the incremental plasticity method, while the kinematic hardening of material is defined using nonlinear Armstrong-Frederick hardening. This type of granular material hardening occurs as a consequence of the cyclic loading effects, such as the seismic load. For this reason, this material model is used for the earthquake analysis in the soil mechanics. Yield surface of the material model changes its position under the cyclic loads in the stress space, whereas there is no change in the size of the yield surface in deviatoric plane. The developed algorithm of the material model has been implemented in the software package PAK. [Projekat Ministarstva nauke Republike Srbije, br. TR37013 i br. TR32036

  1. Monitoring of hardening and hygroscopic induced strains in a calcium phosphate bone cement using FBG sensor.

    Science.gov (United States)

    Bimis, A; Karalekas, D; Bouropoulos, N; Mouzakis, D; Zaoutsos, S

    2016-07-01

    This study initially deals with the investigation of the induced strains during hardening stage of a self-setting calcium phosphate bone cement using fiber-Bragg grating (FBG) optical sensors. A complementary Scanning Electron Microscopy (SEM) investigation was also conducted at different time intervals of the hardening period and its findings were related to the FBG recordings. From the obtained results, it is demonstrated that the FBG response is affected by the microstructural changes taking place when the bone cement is immersed into the hardening liquid media. Subsequently, the FBG sensor was used to monitor the absorption process and hygroscopic response of the hardened and dried biocement when exposed to a liquid/humid environment. From the FBG-based calculated hygric strains as a function of moisture concentration, the coefficient of moisture expansion (CME) of the examined bone cement was obtained, exhibiting two distinct linear regions. PMID:26807773

  2. ABOUT INFLUENCE OF CONVECTIVE MELT FLOWS ON INGOT HARDENING AT HORIZONTAL CONTINUOUS CASTING

    Directory of Open Access Journals (Sweden)

    E. Demchenko

    2014-10-01

    Full Text Available The paper proposes a methodology for evaluation of convective melt flow influence on ingot hardening at horizontal continuous casting that permits to calculate critical flow rates being sufficient for starting skin melt.Due to investigation of ingot formation process using method of hydrothermal analogy it has become possible to reveal a picture of the convective melt movement along hardening front and determine real flow rates.Comparison of calculative and real flow rates has permitted to detect zones of hardening front subjected to melting.The paper shows that application of a partitioning device in the process of horizontal casting significantly decreases an influence of convective melt flows on ingot hardening

  3. Study on radiation damage of electron and γ-rays and mechanism of nuclear hardening

    International Nuclear Information System (INIS)

    Radiation damage effects of electrons and γ-rays are presented. The damage defects are studied by experimental methods. On the basis of these studies the damage mechanism and nuclear hardening techniques are studied

  4. Ion-irradiation hardening of brazed joints of tungsten and oxide dispersion strengthened (ODS) ferritic steel

    International Nuclear Information System (INIS)

    Irradiation hardening and microstructural change of the brazed-joint of W and oxide dispersion strengthened ferritic steel (ODS-FS) was investigated by nano-indentation hardness test and transmission electron microscopy after ion irradiation with 6.4 MeV Fe3+ ions at 500°C up to 10 dpa. Dual-beam irradiation of Fe3+ ions and energy-degraded 1 MeV He+ ion was also carried out. A considerable irradiation hardening occurred in the W base metal where dislocation loops and nano-scaled voids or He-bubbles were observed. Dual-beam irradiation enhanced the hardening. No significant hardening was observed in ODS-FS. The hardness of insert material was reduced after irradiation, which is due to the recovery of dislocations generated during joining process. (author)

  5. Process-Hardened, Multi-Analyte Sensor for Characterizing Rocket Plum Constituents Under Test Environment Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This STTR project aims to develop a process-hardened, simple and low cost multi-analyte sensor for detecting components of rocket engine plumes. The sensor will be...

  6. 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.

  7. Radiation Hardened Nanobridge based Non-volatile Memory for Space Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This NASA Phase I SBIR program would develop and demonstrate radiation hardened nanobridge based non-volatile memory (NVM) for space applications. Specifically, we...

  8. Effects of Different Hardeners on the Working Properties and Bonding Strength of Urea-formaldehyde Adhesives

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The addition of a hardener is necessary for the curing of urea-formaldehyde (UF) adhesives in the production of MDF and particleboard. The most commonly used hardener, ammonium chloride, however, is suspected to cause the formation of poisonous dioxin when waste boards are combusted and hence considered as a potential source of pollution. To assess the feasibility of substituting ammonium sulphate for ammonium chloride, working properties and bonding strength were measured for UF adhesives with the two ...

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

    OpenAIRE

    A. Bokota; T. Domański; N. Szczygiol; L. Sowa

    2008-01-01

    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 ...

  10. Compatibility between a quartz surface hardener and different base concrete mixtures

    OpenAIRE

    Pinheiro-Alves, M.ª Teresa; Fernandes, André; Bettencourt Ribeiro, António

    2012-01-01

    Many cases of cracking and detachment of the concrete surface have appeared in concrete floors, namely pavements where surface hardeners were used, especially in car parks, industrial areas and warehouses. This paper studies the behaviour of ten different base concretes mixtures made with two chemical admixtures and four additions, when a quartz surface hardener is applied. The objective is to identify the relevant parameters of the concrete constituents that influence the open time. Results ...

  11. Compatibility between base concrete made with different chemical admixtures and surface hardener

    OpenAIRE

    Pinheiro-Alves, M.ª Teresa; Sequeira, Ana Rita; Bettencourt Ribeiro, António

    2012-01-01

    Many cases of cracking and detachment of the concrete surface have appeared in concrete floors where surface hardeners were used in Portugal. The main causes for cracking and delamination of trowelled concrete pavements are several and it is essential to control bleeding and the time available to perform the finishing operations. Several base concretes were made with different chemical admixtures and one type of surface hardeners. The purpose of this study was evaluating the influence of the ...

  12. Direct assessment of tensile stress-crack opening behavior of Strain Hardening Cementitious Composites (SHCC)

    OpenAIRE

    Pereira, E. N. B.; Fischer, G.; Barros, Joaquim A. O.

    2012-01-01

    The process of designing Strain Hardening Cementitious Composites (SHCC) is driven by the need to achieve certain performance parameters in tension. These are typically the pseudo-strain hardening behavior and the ability to develop multiple cracks. The assessment of the tensile load-deformation of these materials is therefore of great importance and is frequently carried out by characterizing the material tensile stress-strain behavior. In this paper an alternative approach...

  13. Technological Properties of Wheat/Trifoliate Yam (Dioscorea dumetorum) Hardened Tubers Composite Flours

    OpenAIRE

    Véronique Josette Essa’a; Roger M. Mbanga Baleba; Gabriel Nama Medoua

    2015-01-01

    The ability of trifoliate hardened-yam flours to partially substitute wheat flour in food formulations was assessed. Three varieties of hardened-yam flour were incorporated in wheat flour in proportions of 0, 10, 20, 30, 40, and 50% (w/w). Samples were evaluated for protein content, Zeleny sedimentation index, Hagberg falling number, functional properties (WAC, WSI, and OAC), and some rheological properties including dough rupture pressure (P), extensibility (L), stability (P/L), and deformat...

  14. 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.

  15. 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....

  16. Induction of a Hardening Phenomenon and Quantitative Changes of Ceramides in Stratum Corneum

    OpenAIRE

    Park, Sook Young; Kim, Jin Hye; Cho, Soo Ick; Kim, Kyeong Il; Cho, Hee Jin; Park, Chun Wook; Lee, Cheol Heon; Kim, Hye One

    2014-01-01

    Background Hardening phenomenon of human skin after repeated exposure to the irritants is well-known, but the precise mechanism remains elusive. Objective To modify the previous experimental model of hardening phenomenon by repeated applications of two different concentrations of sodium lauryl sulfate (SLS) solutions to Korean healthy volunteers and to investigate the quantitative changes of ceramides in stratum corneum before and after chronic repeated irritation. Methods Eight hundred micro...

  17. Work-Hardening and Deformation Mechanism of Cold Rolled Low Carbon Steel

    OpenAIRE

    Wang Su-Fen; Peng Yan; Li Zhi-Jie

    2013-01-01

    The study reports the mechanical property and microstructure of cold rolled low carbon steel and its work-hardening behavior in the deformation process. The tensile test in room temperature of low carbon steel was implemented for the different cold rolling deformation, the stress-strain curve was draught according to the relationship between strength and deformation and fitted for the polynomial fitting, the strain hardening exponent (n) of test steel was calculated by the Hollomon method. In...

  18. Hardening of calcium hydroxide and calcium silicate binders due to carbonation and hydration

    OpenAIRE

    Cizer, Özlem; Campforts, J; Balen, Koenraad Van; Elsen, Jan; Gemert, Dionys van

    2006-01-01

    Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RHA) and lime in different compositions were studied with mechanical strength, mercury intrusion porosimetry, thermal analysis and SEM. When cement is partially replaced with RHA and lime, hardening occurs as a result of combined hydration, pozzolanic reaction and carbonation reaction. While hydration of cement contributes to the early strength development of the mortars, carbonation is much more pr...

  19. Direct Resistance Joule Heating of Al-10 pct Si-Coated Press Hardening Steel

    Science.gov (United States)

    Lee, Chang Wook; Choi, Won Seok; Cho, Yeol Rae; De Cooman, Bruno C.

    2016-06-01

    Various rapid heating methods have been developed to increase the productivity of press hardening steel. One of these methods is direct resistance Joule heating. This heating method results in the melting of the surface coating and the formation of a persistent liquid trail as a result of the high thermal conductivity and low melting temperature of the Al-10 pct Si alloy coating. This can be addressed by an alloying preheating treatment prior to the press hardening process.

  20. 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.)

  1. Cellular Composites with Ambient and Autoclaved Type of Hardening with Application of Nanostructured Binder

    Science.gov (United States)

    Nelyubova, V.; Pavlenko, N.; Netsvet, D.

    2015-11-01

    The research presents the dimensional and structural characteristics of nonhydrational hardening binders - nanostructured binders. Rational areas of their use in composites for construction purposes are given. The paper presents the results of the development of natural hardening foam concrete and aerated autoclaved concrete for thermal insulating and construction and thermal insulating purposes. Thus nanostructured binder (NB) in the composites was used as a primary binder and a high reactive modifier.

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

    International Nuclear Information System (INIS)

    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

  3. Hardening of the surface layers of a hollow billet formed by centrifugal casting

    Science.gov (United States)

    Chumanov, V. I.; Chumanov, I. V.; Anikeev, A. N.; Garifulin, R. R.

    2010-12-01

    One of the methods to increase the mechanical properties of steel is its hardening via the introduction of a refractory fine-grained phase into a melt. A method of fabrication of a tube blank by centrifugal casting accompanied by hardening with a refractory phase is considered. The introduction of fine tungsten and silicon carbides is shown to improve the structure of grade 15 steel and to increase the wear resistance of a tube blank made of this steel.

  4. Demonstration of finite element simulations in MOOSE using crystallographic models of irradiation hardening and plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Patra, Anirban [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wen, Wei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martinez Saez, Enrique [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tome, Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-31

    This report describes the implementation of a crystal plasticity framework (VPSC) for irradiation hardening and plastic deformation in the finite element code, MOOSE. Constitutive models for irradiation hardening and the crystal plasticity framework are described in a previous report [1]. Here we describe these models briefly and then describe an algorithm for interfacing VPSC with finite elements. Example applications of tensile deformation of a dog bone specimen and a 3D pre-irradiated bar specimen performed using MOOSE are demonstrated.

  5. Transitional Thermal Creep of Early Age Concrete

    DEFF Research Database (Denmark)

    Hauggaard-Nielsen, Anders Boe; Damkilde, Lars; Freiesleben Hansen, Per

    1999-01-01

    Couplings between creep of hardened concrete and temperature/water effects are well-known. Both the level and the gradients in time of temperature or water content influence the creep properties. In early age concrete the internal drying and the heat development due to hydration increase the effect...... of these couplings. The purpose of this work is to set up a mathematical model for creep of concrete which includes the transitional thermal effect. The model govern both early age concrete and hardened concrete. The development of the material properties in the model are assumed to depend on the...... imbalance in the microstructure termed the microprestresses, which reduces the stiffness of the concrete and increase the creep rate. The aging material is modelled in an incremental way reflecting the hydration process in which new layers of cement gel solidifies in a stress free state and add stiffness to...

  6. Transitional Thermal Creep of Early Age Concrete

    DEFF Research Database (Denmark)

    Hauggaard, A. B.; Damkilde, L.; Hansen, Per Freiesleben

    1999-01-01

    Couplings between creep of hardened concrete and temperature/water effects are well-known. Both the level and the gradients in time of temperature or water content influence the creep properties. In early age concrete the internal drying and the heat development due to hydration increase the effect...... of these couplings. The purpose of this work is to set up a mathematical model for creep of concrete that includes the transitional thermal effect. The model governs both early age concrete and hardened concrete. The development of the material properties in the model is assumed to depend on the...... imbalance in the microstructure termed the microprestresses, which reduce the stiffness of the concrete and increase the creep rate. The aging material is modeled in an incremental way reflecting the hydration process in which new layers of cement gel solidify in a stress free state and add stiffness to the...

  7. Study of the precipitation and of the hardening microscopic mechanisms under irradiation in dilute ferritic alloys

    International Nuclear Information System (INIS)

    The copper precipitation plays a significant role in the embrittlement process of reactor vessel steels under neutron irradiation at 300 deg C. In order to understand the copper precipitation mechanisms, we have studied model ferritic binary FeCu and ternary alloys FeCuX (X=Mn,Ni, Cr, P). These materials have been either Irradiated with 2.5 MeV electrons In the 175-360 deg C temperature range or thermal aged at 500 deg C. The evolution of materials has been followed by resistivity measurements under irradiation, by small angle neutron scattering and by Vickers microhardness measurements. We have shown the similarity of copper precipitation under thermally ageing at 500 deg C and electron Irradiation at 300 deg C, in FeCu1,34%. This result confirms that the main effect of electronic irradiation is to accelerate precipitation. Nevertheless, we have observed that irradiation induces an additional contribution to hardening attributed to point defect clusters. Concerning the ternary alloys, we observed that at 300 deg C the addition of a third element has no significant effect on the copper precipitation kinetic under irradiation but that at lower temperature manganese slows down precipitation kinetic. In order to reproduce the experimental results obtained on FeCu1,34% by using a cluster kinetics model, we have to suppose that the precipitation is heterogeneous and controlled by interface reactions for the small size clusters. In addition, neutron or electron irradiated industrial steels have been studied by small angle neutron scattering. The results revealed the presence of nano-metric solute clusters which contain few copper atoms and which are not linked to the formation of displacement cascades. (author)

  8. Work-Hardening and Deformation Mechanism of Cold Rolled Low Carbon Steel

    Directory of Open Access Journals (Sweden)

    Wang Su-Fen

    2013-01-01

    Full Text Available The study reports the mechanical property and microstructure of cold rolled low carbon steel and its work-hardening behavior in the deformation process. The tensile test in room temperature of low carbon steel was implemented for the different cold rolling deformation, the stress-strain curve was draught according to the relationship between strength and deformation and fitted for the polynomial fitting, the strain hardening exponent (n of test steel was calculated by the Hollomon method. In the whole cold deformation process, the work-hardening of cold rolled steel is significant, work-hardening rate has different degrees decreasewith the deformation increase. The strain hardening exponent is simple and dislocation strengthening is the major cause of hardening processing. The microstructure of test steel was observed after different deformation, the room temperature organization is the ferrite and few pearlite. The original grain is equiaxial and the average grain size is about 23.5 um, and pearlite distributes in ferrite grain boundaries. It was consequently established the cold deformation energy according to dislocation model, the cold deformation energy is main concerned on the plastic deformation to resistance and the initial stress.

  9. Irradiation hardening of pressure vessel steels at 60 C: The role of thermal neutrons and boron

    International Nuclear Information System (INIS)

    Six split melt A533B-type model alloys, with different combinations of copper, nickel and boron contents, were irradiated at 60 C in a neutron spectrum with a thermal-to-fast (E > 1 MeV) ratio of about 370. The resulting yield stress increases were compared to hardening produced by irradiations at a low thermal-to-fast flux ratio. The latter data were obtained in a larger experiment on 60 C hardening that showed: (i) a negligible effect of flux; (ii) hardening increases with the square root of fluence above a low threshold; and (iii) an individually weak, but collectively significant, influence of copper, nickel, manganese, phosphorus and molybdenum. These and other observations have been interpreted to suggest that low temperature hardening is caused by features formed in displacement cascades. However, this interpretation is not consistent with the results of this study which show that yield stress increases are even larger for conditions dominated by low energy PKAs created by thermal neutrons. The thermal-to-fast dpa hardening efficiency factor was estimated to be about 1.7 ± 0.5, which is comparable to the corresponding theoretical ratio of residual defects. The data also suggest that transmutant products from the 10B(n,α) reaction may contribute a small increment to hardening

  10. Microstructural Evolution of the 55 Wt Pct Al-Zn Coating During Press Hardening

    Science.gov (United States)

    Lee, Chang Wook; De Cooman, Bruno Charles

    2014-09-01

    Press hardening is increasingly being used to produce ultra-high strength steel parts for passenger cars. Al-Si, Zn, and Zn-alloy coatings have been used to provide corrosion protection to press hardening steel grades. The use of coatings has drawbacks such as coating delamination or liquid metal-induced embrittlement. In the present work, the microstructural evolution of Al-Zn coating during press hardening was studied. The 55 wt pct Al-Zn coating can in principle provide both Al barrier protection and Zn cathodic protection to press hardened steel. During the heat treatment associated with the press hardening, the 55 wt pct Al-Zn alloy coating is converted to an intermetallic surface layer of Fe2Al5 and a FeAl intermetallic diffusion layer. The Zn is separated from both intermetallic compounds and accumulates at grain boundaries and at the surface. This Zn separation process is beneficial in terms of providing cathodic protection to Al-Zn coated press hardening steel.

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

    International Nuclear Information System (INIS)

    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)

  12. The effect of Ca and RE elements on the precipitation kinetics of Mg{sub 17}Al{sub 12} phase during artificial aging of magnesium alloy AZ91

    Energy Technology Data Exchange (ETDEWEB)

    Amir Esgandari, B.; Mehrjoo, H. [Department of Mechanical Engineering, Shahid Rajaee Teacher Training University (SRTTU), Lavizan, Tehran (Iran, Islamic Republic of); Nami, B., E-mail: bnami56@gmail.com [Department of Mechanical Engineering, Shahid Rajaee Teacher Training University (SRTTU), Lavizan, Tehran (Iran, Islamic Republic of); Miresmaeili, S.M. [Department of Mechanical Engineering, Shahid Rajaee Teacher Training University (SRTTU), Lavizan, Tehran (Iran, Islamic Republic of)

    2011-06-15

    Highlights: {yields} Ca and RE elements decrease the precipitation rate during aging of AZ91 alloy. {yields} Precipitation kinetics and mechanism during aging of the alloys were studied. {yields} Effect of Ca and RE on creep properties of age hardened AZ91 alloy was studied. - Abstract: The effect of simultaneous alloying with Ca and rare earth (RE) elements on the age hardening kinetics of AZ91 was studied through the fitting of the Johnson-Mehl-Avrami (JMA) equation. The results showed that the addition of both Ca and RE elements not only suppress discontinuous precipitation of the Mg{sub 17}Al{sub 12} phase during the age hardening process, but also decrease the alloy hardness. Fitting the JMA equation to the experimental data indicated that the phase transformation during age hardening of an alloy variant containing both Ca and RE (at 170 deg. C and 190 deg. C) and standard AZ91 (at 170 deg. C) takes place by the nucleation of precipitates on dislocations. In contrast, the precipitation during age hardening of AZ91 at 190 deg. C occurs via nucleation at grain boundaries. Although it was observed that the creep strength of age hardened specimens are lower than that of the as cast specimens, but age hardening treatment has lower deleterious influence on the creep resistance of the alloy containing Ca and RE in comparison with conventional AZ91. This may be ascribed to the decreased precipitation rate resulting from the addition of both Ca and RE elements.

  13. Hardening and microstructural reactions in high-temperature equal-channel angular pressed Mg-Nd-Gd-Zn-Zr alloy

    International Nuclear Information System (INIS)

    The use of high-temperature (330 deg. C) equal-channel angular pressing (ECAP) is demonstrated to promote precipitation of a fine and uniform dispersion of the FCC β1 phase in an Mg-Nd-Gd-Zn-Zr alloy. Significantly, this process induces a hardening reaction in the alloy, where isothermal ageing at this temperature leads only to softening. The evolution of microstructure is characterized using transmission electron microscopy and scanning electron microscopy. The nucleation and growth of precipitates during the high-temperature ECAP are discussed. This research highlights a new approach to engineer precipitate microstructures via the application of severe plastic deformation so as to extend the property space of high-temperature Mg alloys.

  14. Surface integrity of hardened steel parts in hybrid machining operations

    Directory of Open Access Journals (Sweden)

    W. Grzesik

    2006-08-01

    very beneficial machiningprocess for highly loaded hardened parts.

  15. The Age-Precipitations Structure Of Al-Mg-Ge Alloy Aged At 473K

    OpenAIRE

    Kawai A.; Watanabe K; Matsuda K.; Ikeno S.

    2015-01-01

    The Al-Mg-Ge alloy is one of the age-hardening aluminum alloy after solution heat treatment. It has been proposed that the age-precipitation behavior of Al-Mg-Ge alloy is different from that of Al-Mg-Si alloy according to our previous works about the microstructure on Al-Mg-Ge alloy over-aged at 523K. For example, The hardness of peak aged Al-1.0mass%Mg2Ge alloy is higher than that of Al-1.0mass%Mg2Si alloy. The precipitates in the over-aged samples have been classified as some metastable pha...

  16. 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

    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...

  17. Crack Formation During Hardening in Fibre Reinforced Concrete

    DEFF Research Database (Denmark)

    Olesen, John Forbes; Stang, Henrik

    1996-01-01

    The objective of this project is to establish models for the development of cracks in the early age of fibre reinforced concrete due to restrained shrinkage and temperature variations. These models will be based on measurements of age dependant material properties including the post crack respons...

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

    International Nuclear Information System (INIS)

    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 CO2 laser, and optical fiber access, the superficial hardening with Nd:YAG laser, depending on the level of

  19. The Strain-Hardening Behavior of TZAV-30 Alloy After Various Heat Treatments

    Science.gov (United States)

    Liang, S. X.; Yin, L. X.; Zheng, L. Y.; Ma, M. Z.; Liu, R. P.

    2016-02-01

    The Ti-Zr-Al-V series titanium alloys with excellent mechanical properties and low density exhibit tremendous application potential as structural materials in aviation, automotive, and navigation industries. The strain-hardening behavior of Ti-30Zr-5Al-3V (wt.%, TZAV-30) alloy with various heat treatments is investigated in this study. Experimental results show that strain-hardening behavior of the examined alloy depends on the heat treatment process. The average strain-hardening exponent, n, is approximately 0.061 for WA specimen (825 °C/0.5 h/water quenching + 600 °C/4 h/air cooling), 0.068 for FC (850 °C/0.5 h/furnace cooling), 0.121 for AC (850 °C/0.5 h/air cooling), and 0.412 for WQ (850 °C/0.5 h/water quenching). Analysis of strain-hardening rate versus true strain curves indicates that higher n of AC specimen results from the lower degradation rate of strain-hardening rate with strain, and the ultrahigh n of WQ specimen is attributed to the evident increase in strain-hardening rate at the true strain from 0.04 to 0.06. Phase constitution and microstructural analyses reveal that the n of the examined alloy with α + β phases increases with the increase in the relative content of the retained β phase but is independent of average thickness of α plates. The increase in strain-hardening rate in WQ specimen depends on metastable α″ martensite and martensitic transition induced by tensile stress.

  20. 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

  1. Simulation and research on a 4T-cell based duplication redundancy SRAM for SEU radiation hardening

    International Nuclear Information System (INIS)

    A novel 4T-cell based duplication redundancy SRAM is proposed for SEU radiation hardening applications. The memory cell is designed with a 65-nm low leakage process; the operation principle and the SEU radiation hardening mechanism are discussed in detail. The SEE characteristics and failure mechanism are also studied with a 3-D device simulator. The results show that the proposed SRAM structure exhibits high SEU hardening performance with a small cell size. (paper)

  2. Physico-chemical studies of hardened cement paste structure with micro-reinforcing fibers

    Science.gov (United States)

    Steshenko, Aleksei; Kudyakov, Aleksander; Konusheva, Viktoriya

    2016-01-01

    The results of physico-chemical studies of modified hardened cement paste with micro-reinforcing fibers are given in this article. The goal was to study the reasons of the increase of strength properties of modified hardened cement paste by the method of X-ray diffraction and electron microscopy. It is shown that the use of mineral fibers in the production of cement based material has positive effect on its properties. The study found out that the increase in the strength of the hardened cement paste with micro-reinforcing fibers is due to the increase of the rate of hydration of cement without a significant change in the phase composition in comparison with hardened cement paste without additive. The results of microstructure investigation (of control samples and samples of the reinforced hardened cement paste) have shown that introduction of mineral fibers in the amount of 0.1-2 % by weight of cement provides the structure of the homogeneous microporous material with uniform distribution of the crystalline phase provided by densely packed hydrates.

  3. Technological Properties of Wheat/Trifoliate Yam (Dioscorea dumetorum Hardened Tubers Composite Flours

    Directory of Open Access Journals (Sweden)

    Véronique Josette Essa’a

    2015-01-01

    Full Text Available The ability of trifoliate hardened-yam flours to partially substitute wheat flour in food formulations was assessed. Three varieties of hardened-yam flour were incorporated in wheat flour in proportions of 0, 10, 20, 30, 40, and 50% (w/w. Samples were evaluated for protein content, Zeleny sedimentation index, Hagberg falling number, functional properties (WAC, WSI, and OAC, and some rheological properties including dough rupture pressure (P, extensibility (L, stability (P/L, and deformation energy (W. Results showed that trifoliate hardened-yam flours do not have acceptable baking properties as pictured by the low Zeleny sedimentation index and the low Hagberg falling number. Protein quality (Zeleny index, 31 of wheat flour helped to compensate gluten deficit of yam flours, but the amylasic activity determined by the Hagberg falling number could not be adjusted, which resulted in a loss of extensibility (L of the paste at 10% substitution. Multivariate analysis of experimental data regrouped wheat flour and all wheat/hardened-yam treated with kanwa composite flours in one homogeneous cluster. Although wheat/hardened-yam treated with kanwa composite flours had physicochemical and functional properties similar to wheat, the inadequate diastasic activity makes them inappropriate for bread making, marking the strongest influence of that parameter.

  4. On the spectral hardening at ~> 300 keV in solar flares

    CERN Document Server

    Li, Gang; Zank, Gary; Chen, Yao

    2013-01-01

    It has been noted for a long time that the spectra of observed continuum emissions in many solar flares are consistent with double power laws with a hardening at energies $\\sim > $ 300 keV. It is now largely believed that at least in electron-dominated events the hardening in photon spectrum reflects an intrinsic hardening in the source electron spectrum. In this paper, we point out that a power law spectrum of electron with a hardening at high energies can be explained by 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 which are comparable with observations. One necessary condition for our proposed scenario to work is that high energy electrons resonate with th...

  5. Physico-chemical studies of hardened cement paste structure with micro-reinforcing fibers

    Energy Technology Data Exchange (ETDEWEB)

    Steshenko, Aleksei, E-mail: steshenko.alexey@gmail.com; Kudyakov, Aleksander; Konusheva, Viktoriya [Tomsk State University of Architecture and Building, 2 Solyanaya Sq., Tomsk, 634003 (Russian Federation)

    2016-01-15

    The results of physico-chemical studies of modified hardened cement paste with micro-reinforcing fibers are given in this article. The goal was to study the reasons of the increase of strength properties of modified hardened cement paste by the method of X-ray diffraction and electron microscopy. It is shown that the use of mineral fibers in the production of cement based material has positive effect on its properties. The study found out that the increase in the strength of the hardened cement paste with micro-reinforcing fibers is due to the increase of the rate of hydration of cement without a significant change in the phase composition in comparison with hardened cement paste without additive. The results of microstructure investigation (of control samples and samples of the reinforced hardened cement paste) have shown that introduction of mineral fibers in the amount of 0.1-2 % by weight of cement provides the structure of the homogeneous microporous material with uniform distribution of the crystalline phase provided by densely packed hydrates.

  6. Evaluation of radiation hardening in ion-irradiated Fe based alloys by nanoindentation

    International Nuclear Information System (INIS)

    Nanoindentation in combination with ion irradiation offers the possibility to quantify irradiation hardening due to radiation damage. Irradiation experiments for Fe–1.0wt.%Cu alloys, China A508-3 steels, and 16MND5 steels were carried out at about 100 °C by proton and Fe-ions with the energy of 240 keV, 3 MeV respectively. The constant stiffness measurement (CSM) with a diamond Berkovich indenter was used to obtain the depth profile of hardness. The results showed that under 240 keV proton irradiation (peak damage up to 0.5 dpa), Fe–1.0wt.%Cu alloys exhibited the largest hardening (∼55%), 16MND5 steels resided in medium hardening (∼46%), and China A508-3(2) steels had the least hardening (∼10%). Under 3 MeV Fe ions irradiation (peak damage up to 1.37 dpa), both China A508-3(1) and 16MND5 steels showed the same hardening (∼26%). The sequence of irradiation tolerance for these materials is China A508-3(2) > 16MND5 ≈ China A508-3(1) > Fe–1.0wt.%Cu. Based on the determination of the transition depth, the nominal hardness H0irr was also calculated by Kasada method

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

    International Nuclear Information System (INIS)

    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)

  8. Evaluation of radiation hardening in ion-irradiated Fe based alloys by nanoindentation

    Science.gov (United States)

    Liu, Xiangbing; Wang, Rongshan; Ren, Ai; Jiang, Jing; Xu, Chaoliang; Huang, Ping; Qian, Wangjie; Wu, Yichu; Zhang, Chonghong

    2014-01-01

    Nanoindentation in combination with ion irradiation offers the possibility to quantify irradiation hardening due to radiation damage. Irradiation experiments for Fe-1.0wt.%Cu alloys, China A508-3 steels, and 16MND5 steels were carried out at about 100 °C by proton and Fe-ions with the energy of 240 keV, 3 MeV respectively. The constant stiffness measurement (CSM) with a diamond Berkovich indenter was used to obtain the depth profile of hardness. The results showed that under 240 keV proton irradiation (peak damage up to 0.5 dpa), Fe-1.0wt.%Cu alloys exhibited the largest hardening (∼55%), 16MND5 steels resided in medium hardening (∼46%), and China A508-3(2) steels had the least hardening (∼10%). Under 3 MeV Fe ions irradiation (peak damage up to 1.37 dpa), both China A508-3(1) and 16MND5 steels showed the same hardening (∼26%). The sequence of irradiation tolerance for these materials is China A508-3(2) > 16MND5 ≈ China A508-3(1) > Fe-1.0wt.%Cu. Based on the determination of the transition depth, the nominal hardness H0irr was also calculated by Kasada method.

  9. Thermal stability of functional properties in dispersion and precipitation hardened selected copper alloys

    Directory of Open Access Journals (Sweden)

    J.P. Stobrawa

    2008-03-01

    Full Text Available Purpose: The objective of the study was to produce copper-based dispersion hardened materials of submicrongrain size, determination of their basic functional properties and stability in high temperature, as well as comparisonof those properties with properties of selected precipitation hardened copper alloys made by classical method ofmelting, casting and thermomechanical processing.Design/methodology/approach: The examination was conducted on copper hardened with WC, Y2O3 andCr3Si particles and on precipitation hardened copper alloys with addition of Cr and Ni, Si, Cr. The examination ofthe materials covered changes in hardness, electrical conductivity and stabilities of those properties after variousheat treatment options.Findings: Assuming the tendency to softening depending on annealing temperature to be as a criterion ofproperties stability, temperature ranges of individual alloys applications were determinedResearch limitations/implications: The study could be supplemented with information on tendencies tohigh-temperature creep in the examined alloysPractical implications: The materials are used for components operating in high-temperature conditions, suchas components of crystallizers for continuous casting of metals, electrodes for welding, in nu clear reactors, etc.Originality/value: The originality lies in examination of dispersion hardened materials (especially Cu – Cr3Siof controlled submicrometric structure obtained from initial nanocrystalline structure.

  10. Ultrasound monitoring of the influence of different accelerating admixtures and cement types for shotcrete on setting and hardening behaviour

    International Nuclear Information System (INIS)

    The possible use of ultrasound measurements for monitoring setting and hardening of mortar containing different accelerating admixtures for shotcrete was investigated. The sensitivity to accelerator type (alkaline aluminate or alkali-free) and dosage, and accelerator-cement compatibility were evaluated. Furthermore, a new automatic onset picking algorithm for ultrasound signals was tested. A stepwise increase of the accelerator dosage resulted in increasing values for the ultrasound pulse velocity at early ages. In the accelerated mortar no dormant period could be noticed before the pulse velocity started to increase sharply, indicating a quick change in solid phase connectivity. The alkaline accelerator had a larger effect than the alkali-free accelerator, especially at ages below 90 min. The effect of the alkali-free accelerator was at very early age more pronounced on mortar containing CEM I in comparison with CEM II, while the alkaline accelerator had a larger influence on mortar containing CEM II. The increase of ultrasound energy could be related to the setting phenomenon and the maximum energy was reached when the end of workability was approached. Only the alkaline accelerator caused a significant reduction in compressive strength and this for all the dosages tested

  11. Hardening of the surface layers of commercial pure titanium VT1-0 under combined treatment

    International Nuclear Information System (INIS)

    The treatment of VT1-0 titanium samples was carried out by concentrated energy fluxes. The combined treatment included surface carburizing with the joint use of powder samples of compounds with high physical and mechanical properties (namely, titanium diboride TiB2, silicon carbide SiC and zirconium oxide ZrO2) and subsequent electron beam treatment of surface layers formed in electroexplosive treatment. The combined treatment of surface layers resulted in the multifold increase in microhardness, which reduces depending on the depth of hardening zone. After electron-beam treatment, the depth of hardening zone is increased. During electron-beam treatment, the two-layer hardening zone forms

  12. An extraordinary enhancement of strain hardening in fine-grained zirconium

    International Nuclear Information System (INIS)

    Grain refinement always leads to a high strength but a low ductility that results from a reduced strain hardening. Here, we report an extraordinary enhancement of strain hardening in fine-grained (FG) Zr with an average grain size of 2–3 μm compared with its coarse-grained (CG) counterpart, which yields a uniform elongation of ∼15.5% in the same order as that (∼13.2%) of the CG Zr. The unusually enhanced strain hardening in the FG Zr is attributed to the formation of nano-scale defect structures within the fine grains. The present work provides a promising way to enhance the ductility of fine- and ultrafine-grained materials without losing their high strength, and thus is of wide interest

  13. State of the art of durability-performance evaluation of hardened cement based on phase compositions

    International Nuclear Information System (INIS)

    Upgrading durability-performance evaluation technique for concrete is urgently demanded in connection to its application to radio-active waste repository which needs ultra long-term durability. Common concrete structures also require an advanced method for minimizing the life-cycle cost. The purpose of this research is to investigate current problems and future tasks on durability-performance evaluation of hardened cement from the view point of phase composition. Although the phase composition of hardened cement has not fully been reflected to durability-performance evaluation, it influences concrete durability as well as its pore structure. This report reviews state of the art of the factors affecting phase composition, analytical and experimental evaluation techniques for phase composition, and durability-performance evaluation methods of hardened cement based on phase composition. (author)

  14. Stress corrosion cracking tests for low carbon stainless steels with work hardened layer

    International Nuclear Information System (INIS)

    To avoid introduction of Cr depletion at grain boundaries by welding process, low carbon stainless steels (SSs) were used in corrosive environment as one of countermeasures for Stress Corrosion Cracking (SCC). Recently, it is reported that SCCs were introduced at portion with work hardened layer although low carbon SSs had been used at core shrouds and primary loop recirculation piping in Boiling Water Reactors. To simulate and examine the phenomenon, mechanical working, metallographic observation, hardness test and SCC tests in chloride solutions were conducted for low carbon SSs. From the results of metallographic observation and hardness test, it was confirmed that slip bands were observed around the surface and hardened layer was introduced by mechanical working. From the results of SCC tests, it was noticed that cracks which introduced from the surface, had grown into the matrix. It is thought that low carbon SSs with work hardened layer have susceptibility to SCC from the above. (author)

  15. Hardening of the surface layers of commercial pure titanium VT1-0 under combined treatment

    Energy Technology Data Exchange (ETDEWEB)

    Bashchenko, Lyudmila P., E-mail: luda.baschenko@gmail.com; Gromov, Viktor E., E-mail: gromov@physics.sibsiu.ru; Budovskikh, Evgenii A., E-mail: budovskih-ea@physics.sibsiu.ru; Soskova, Nina A., E-mail: gromov@physics.sibsiu.ru [Siberian State Industrial University, Novokuznetsk, 654007 (Russian Federation); Ivanov, Yurii F., E-mail: yufi55@mail.ru [Institute of High Current Electronics SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    The treatment of VT1-0 titanium samples was carried out by concentrated energy fluxes. The combined treatment included surface carburizing with the joint use of powder samples of compounds with high physical and mechanical properties (namely, titanium diboride TiB{sub 2}, silicon carbide SiC and zirconium oxide ZrO{sub 2}) and subsequent electron beam treatment of surface layers formed in electroexplosive treatment. The combined treatment of surface layers resulted in the multifold increase in microhardness, which reduces depending on the depth of hardening zone. After electron-beam treatment, the depth of hardening zone is increased. During electron-beam treatment, the two-layer hardening zone forms.

  16. Hardening of the surface layers of commercial pure titanium VT1-0 under combined treatment

    Science.gov (United States)

    Bashchenko, Lyudmila P.; Gromov, Viktor E.; Budovskikh, Evgenii A.; Ivanov, Yurii F.; Soskova, Nina A.

    2015-10-01

    The treatment of VT1-0 titanium samples was carried out by concentrated energy fluxes. The combined treatment included surface carburizing with the joint use of powder samples of compounds with high physical and mechanical properties (namely, titanium diboride TiB2, silicon carbide SiC and zirconium oxide ZrO2) and subsequent electron beam treatment of surface layers formed in electroexplosive treatment. The combined treatment of surface layers resulted in the multifold increase in microhardness, which reduces depending on the depth of hardening zone. After electron-beam treatment, the depth of hardening zone is increased. During electron-beam treatment, the two-layer hardening zone forms.

  17. Elastic-plastic growth of plane stress mode II cracks in power law hardening solids

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The asymptotic analysis of near tip field of plane stress mode II cracks growing quasi-statically in steadiness in power law hardening solids has been performed. Attention was focused on the behavior of the asymptotic solutions as hardening exponent n→∞. Analytical expressions of the dominant terms of velocities and flow factor in centered fan sectors were obtained by expanding them in series of the small parameter s=2/(n-1). Results show that, as n→∞, all the expressions of dominant terms of quantities in near tip field tend to their corresponding ones for elastic-perfectly plastic materials. The effect of hardening exponent n on the angular variations of stresses in near tip field is very weak. Analysis and discussion that related to plane stress mode I crack problem is given in appendix for comparison with results for mode II.

  18. Role of work hardening characteristics of matrix alloys in the strengthening of metal matrix composites

    Indian Academy of Sciences (India)

    K T Kashyap; C Ramachandra; C Dutta; B Chatterji

    2000-02-01

    The strengthening of particulate reinforced metal–matrix composites is associated with a high dislocation density in the matrix due to the difference in coefficient of thermal expansion between the reinforcement and the matrix. While this is valid, the role of work hardening characteristics of the matrix alloys in strengthening of these composites is addressed in the present paper. It is found that commercial purity aluminium which has the lowest work hardening rate exhibits the highest strength increment. This effect is due to increased prismatic punching of dislocations. This relationship of decreasing work hardening rate associated with increasing prismatic punching of dislocations in the order 7075, 2014, 7010, 2024, 6061 and commercial purity aluminium leading to increased strength increments is noted.

  19. On The Enhancement of Wear Resistance of Hardened Carbon Tool Steel (AISI 1095) With Cryogenic Quenching

    Institute of Scientific and Technical Information of China (English)

    V.Soundararajan; N.Alagurmurthi; K.Palaniradja

    2004-01-01

    Many experimental investigations reveal that it is very difficult to have a completely martensitic structure by any hardening process. Some amount of austenite is generally present in the hardened steel. This austenite existing along with martensite is normally referred as the retained austenite. The presence of retained austenite greatly reduces the mechanical properties and such steels do not develop maximum hardness even after cooling at rates higher than the critical cooling rates.Strength can be improved in hardened steels containing retained austenite by a process known as cryogenic quenching.Untransformed austenite is converted into martensite by this treatment. This conversion of retained austenite into martensite results in increased hardness, wear resistance and dimensional stability of steel. Wear can be defined as the progressive loss of materials from the operating surface of a body occurring as a result of relative motion at the surface. Hardness, load,speed, surface roughness, temperature are the major factors which influences wear. Many studies on wear indicate that increasing hardness decreases the wear of a material. With this in mind, to study the surface wear on a surface modified(Cryogenic treated) steel material an attempt has been made in this paper. In this study as a Part -I Hardening was carried out on carbon tool steel (AISI 1095) of different L/D ratio with conventional quenchants like purified water, aqueous solution and Hot mineral oil. As a Part -Ⅱ hardening was followed by quenching was carried out as said in Part- I and the hardened specimen were quenched in liquid Nitrogen which is at sub zero condition. The specimens were tested for its microstructure, hardness and wear loss. The results were compared and analyzed. The alloying elements increases the content of retained austenite hence the material used was AISI1095 (Carbon 0.9%, Si 0.2%, Mn0.4% and the rest Iron)

  20. Precipitation hardening and hydrogen embrittlement of aluminum alloy AA7020

    Indian Academy of Sciences (India)

    Santosh Kumar; T K G Namboodhiri

    2011-04-01

    AA7020 Al–Mg–Zn, a medium strength aluminium alloy, is used in welded structures in military and aerospace applications. As it may be subjected to extremes of environmental exposures, including high pressure liquid hydrogen, it could suffer hydrogen embrittlement. Hydrogen susceptibility of alloy AA7020 was evaluated by slow strain-rate tensile testing, and delayed failure testing of hydrogen-charged specimens of air-cooled, duplexaged, and water-quenched duplex agedmaterials. The resistance to hydrogen embrittlement of the alloy was found to be in the order of air-cooled duplex aged alloy > as-received (T6 condition) > water quenched duplex aged material.

  1. Influence of alloying and secondary annealing on anneal hardening effect at sintered copper alloys

    Indian Academy of Sciences (India)

    Svetlana Nestorovic

    2005-08-01

    This paper reports results of investigation carried out on sintered copper alloys (Cu, 8 at%; Zn, Ni, Al and Cu–Au with 4 at%Au). The alloys were subjected to cold rolling (30, 50 and 70%) and annealed isochronally up to recrystallization temperature. Changes in hardness and electrical conductivity were followed in order to investigate the anneal hardening effect. This effect was observed after secondary annealing also. Au and Al have been found to be more effective in inducing anneal hardening effect.

  2. Strain Hardening in Uniaxial Elongation vs. Temperature for Random Copolymer Melts with High Comonomer Content

    Science.gov (United States)

    Mills, John E.; Jayaraman, Krishnamurthy; Patham, Bhaskar; Dong, Dinshong; Wolkowicz, Michael

    2008-07-01

    Two metallocene-catalyzed random copolymers with a polyethylene backbone and octene comonomer content of 20 wt% and 38 wt% were tested in uniaxial extensional flow at different temperatures. Sparse LCB was detected in both melts with these measurements. The strain hardening parameter at the lowest strain rate was found to be greater for EO3, the material with the smaller degree of LCB. The temperature dependence of the strain hardening parameter was also greater for EO3 than for EO1. These trends may be related to the two model parameters used by Wagner and coworkers representing branch content and the maximum tube diameter contraction.

  3. Relationship between chloride diffusivity and pore structure of hardened cement paste

    Institute of Scientific and Technical Information of China (English)

    Guo-wen SUN; Wei SUN; Yun-sheng ZHANG; Zhi-yong LIU

    2011-01-01

    Based on effective media theory, a predictive model, relating chloride diffusivity to the capillary pores, gel pores,tortuosity factor, and pore size distribution of hardened cement, is proposed. To verify the proposed model, the diffusion coefficient of chloride ions, the degree of hydration, and peak radius of capillary pores of cement paste specimens were measured. The predicted results for chloride diffusivity were compared with published data. The results showed that the predicted chloride diffusivity of hardened cement paste was in good agreement with the experimental results. The effect of the evolution of pore structures in cement paste on chloride diffusivity could be deduced simultaneously using the proposed model.

  4. Study on Using Concentrators in the Induction-Hardening Process of a Cylindrical Part

    Directory of Open Access Journals (Sweden)

    BURCA Adrian

    2013-05-01

    Full Text Available Currently the tendency in industry is to reduce the production price of the finished product. One of the most costly components of the final product is electricity. By lowering energy consumption, withoutchanging the quality of the product, production costs may become more reduced while environment will also be protected. Using the ELTA 1D commercial software, this paper has looked at the possibility to reduce energy consumption while tempering (hardening a piece byelectromagnetic induction. It will make a comparison of the electrical parameters of a surface thermal treatment (hardening installation when using a concentrator for electromagnetic field lines and in the situation when the concentrator is not used.

  5. Re-hardening of hadron transverse mass spectra in relativistic heavy-ion collisions

    Indian Academy of Sciences (India)

    P K Sahu; N Otuka; M Isse; Y Nara; A Ohnishi

    2006-05-01

    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.

  6. 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....../softening behavior of nonlinear mechanical systems. The iterative optimization procedure consists of calculation of nonlinear normal modes, solving an adjoint equation system for sensitivity analysis and an update of design variables using a mathematical programming tool. We demonstrate the method with examples...

  7. Electrolytic surface hardening of steel,castiron and aluminium-bronze

    Directory of Open Access Journals (Sweden)

    Suhas Keshav Paknik a r

    2006-08-01

    Full Text Available Electrolytic hardening process w as developed in USSR in the 1950s. The process w as developed but w as not com m ercially exploited. There is no evidence of w ork done on this process in India. The author has done this originalw ork applied to different m aterials like steel, castiron and alum inum -bronze.This paper gives details ofm icrostructuraltransform ations along w ith hardness value achieved. There is vitalscope for this process to becom e viable for surfacehardening and selective hardening ofsm allcom ponents.

  8. Paint and coating material as film-forming solution hardenable by ionizing radiation

    International Nuclear Information System (INIS)

    The invention deals with a paint and coating material hardenable by ionizing radiation which is present as a film-forming solution of an acrylic acid urethane acryl addition product (with common additions where necessary) in a solvent and/or one or several vinyl monomers. According to the method invented, hardening takes place at normal temperatures in a very short time. The acrylic acid addition product contains di-isocyanate compounds which are given in detail, its molecular weight is below 900, better under 600. 12 examples illustrate the invention. The paint and coating materials are intended for articles having wood and metal surfaces requiring decorative and wear-fast coats. (UWI)

  9. Research on total-dose irradiation effect of hardened partially-depleted NMOSFET/SIMOX

    International Nuclear Information System (INIS)

    In this work, top and back gate characteristics of partially-depleted NMOS transistors with enclosed gate fabricated on SIMOX which is hardened by silicon ions implantation were studied under X-ray total-dose irradiation of three bias conditions. It has been found experimentally that back gate threshold shift and leakage current were greatly reduced during irradiation for hardened transistors, comparing to control ones. It has been confirmed that the improvement of total-dose properties of SOI devices is attributed to the silicon nanocrystals (nanoclusters) in buried oxides introduced by ion implantation. (authors)

  10. Radiation hardening of zirconium after the bombardment by heavy ions and neutrons

    International Nuclear Information System (INIS)

    The radiation hardening of zirconium after the bombardment by Ne ions (Ei=230 MeV) and by neutrons (En>0,1 MeV) under the same conditions was investigated. The dose dependence of the yield stress change Δσ0,2 was measured. It is shown that the dose dependences are identical in both cases, but a certain effect of the hardening after neutron bombardment is achieved at a dose 10 times smaller than in the case of Ne bombardment

  11. Influence of oxygen impurity atoms on defect clusters and radiation hardening in neutron-irradiated vanadium

    International Nuclear Information System (INIS)

    Single crystal TEM samples and polycrystalline tensile samples of vanadium containing 60-640 wt ppm oxygen were irradiated at about 1000C to about 1.3 x 1019 neutrons/cm2 (E greater than 1 MeV) and post-irradiation annealed up to 8000C. The defect cluster density increased and the average size decreased with increasing oxygen concentration. Higher oxygen concentrations caused the radiation hardening and radiation-anneal hardening to increase. The observations are consistent with the nucleation of defect clusters by small oxygen or oxygen-point defect complexes and the trapping of oxygen at defect clusters upon post-irradiation annealing

  12. Influence of rolling temperature on the microstructure and mechanical properties of secondary hardening high Co-Ni steel bearing 0.28 wt% C

    International Nuclear Information System (INIS)

    Research highlights: → Precipitation behavior of M2C nucleated at dislocations was significantly influenced by rolling temperature. → Severe deformation promoted the generation of dislocations, which can operate as heterogeneous nucleation sites for the M2C precipitation. → Precipitation mode varied from continuous nucleation to site saturation due to higher density of dislocations. - Abstract: A secondary hardening high Co-Ni alloy steel with the composition of 13Co-8Ni-4Cr-1.5Mo-0.28C was heavily rolled in the temperature range of 600-1000 deg. C to study the influence of the rolling temperature. The effects of heavy rolling on the microstructure and mechanical properties were investigated in detail by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The severe deformation accelerated the aging kinetics and increased the degree of secondary hardening. These results were analyzed in terms of the dislocation-operated heterogeneous nucleation and the effective activation energy for precipitation during the early periods of aging. Based on the effective activation energy calculated from our DSC results, the M2C precipitation mode tended to change from continuous nucleation to site saturation with a decrease in rolling temperature. This phenomenon implies that the higher dislocation density within martensite due to the more severe deformation at lower temperatures plays a significant role as nucleation sites for M2C precipitation.

  13. Effects of Combined Pre-straining and Pre-aging on Natural Aging and Bakehardening Response of an Al-Mg-Si Alloy

    Institute of Scientific and Technical Information of China (English)

    Zhiqing ZHANG; Huanhuan XU; Sainan WU; Yin LIU

    2013-01-01

    For a series of Al-0.34%Mg-1.05%Si-0.08%Cu alloys,the effects of pre-treatment on natural aging,bake hardening response and plasticity were investigated using Vickers hardness test and tensile test.Differential scanning calorimetry (DSC) analysis was conducted to reveal corresponding precipitation mechanisms.The results showed that pre-straining and pre-aging alone couldn't completely suppress natural aging and improve bake hardening response simultaneously.The sensitivity of the pre-straining and pre-aging on the mechanical properties was evaluated.It was found that pre-aging was the main factor which greatly improved bake hardening response and pre-treatment had a weak influence on plasticity in pre-treated samples.DSC analysis showed that the dissolution trough of clusters disappeared in pre-treated samples,bothβ" and β' precipitation peak shifted to lower temperature and were reduced in pre-strained and pre-aged samples.It was concluded that the formation of Mg/Si clusters was replaced by the accelerated precipitation ofβ" andβ' phases,which caused the suppression of natural aging and the improvement of bake hardening response (BHR).

  14. The softened heat-affected zone in resistance spot welded tailor hardened boron steel: a material model for crash simulation

    NARCIS (Netherlands)

    Eller, T.K.; Greve, L.; Andres, M.T.; Medricky, M.; Geijselaers, H.J.M.; Meinders, V.T.; Boogaard, van den A.H.

    2016-01-01

    A hardness-based model for tailor hardened boron steel is presented that takes into account the softened heat-affected zone of resistance spot welds. The computational model is designed for crashworthiness simulation of fully and partially hardened components obtained by tailored tooling. Five diff

  15. The effect of hardening laws and thermal softening on modeling residual stresses in FSW of aluminum alloy 2024-T3

    DEFF Research Database (Denmark)

    Sonne, Mads Rostgaard; Tutum, Cem Celal; Hattel, Jesper Henri;

    2013-01-01

    and kinematic rules of hardening were used in order to study the effect of the hardening law on the residual stresses as well as on the final yield stress. This numerical model was then applied in two different cases. Firstly, a very simple 1D Satoh test was modeled. Different combinations of either isotropic...... or kinematic hardening together with the metallurgical softening model were applied in order to give a first impression of the tendencies in residual stresses in friction stir welds when choosing different hardening and softening behaviors. Secondly, real friction stir butt welding of aluminum alloy 2024-T3...... conditions toward the choice of hardening rules and especially whether including the softening model or not. --------------------------------------------------------------------------------...

  16. The production of HTR-fuel kernels by microwave hardening of aqueous metal-salt-resin droplets

    International Nuclear Information System (INIS)

    The construction and function of the microwave equipment for the hardening of free falling salt-resin-droplets, the preparation of solutions, their treatment and conditioning of the hardening process, the appearance and properties of the hardened ''green'' kernels and the transformation of ''green'' kernels of HTR-fuel kernels, i.e. sintered UO2-particles are described. With a suitable microwave equipment it is possible to harden aqueous droplets containing metal-salts (e.g. uranylnitrate), resorcinol and formaldehyde. The hardening occurs while the mentioned droplets are falling under gravity. These particles are suitable for the production of HTR-fuel kernels, e.g. high density UO2-particles. The entire process has the advantage of minimising the process specific waste. (author)

  17. Experimental Study of Ageing Behaviour of Al-Cu-Mg/Bagasse Ash Particulate Composites

    Directory of Open Access Journals (Sweden)

    R. A. Mohammed

    2011-03-01

    Full Text Available The experimental correlation of ageing behaviour for Al-Cu-Mg/Bagasse ash particulate composites with 2-10wt% bagasse ash particles produced by double stir-casting method has been investigated. Hardness values measurement and microstructural analysis were used in determining the ageing behaviour, after solution and age-hardened heat-treatment. For comparison, the ageing characteristics of the unreinforced matrix alloy with an identical processing and ageing history were also examined. The results indicate that the composite exhibits an accelerated hardening response compared to the unreinforced matrix alloy at the three selected aging temperatures of 100, 200 and 300 °C. Ageing temperature has great influence on the hardening characteristics of the Al–Cu–Mg/BAp composite. TEM observations reveal that the addition of bagasse ash particles to the Al–Cu–Mg alloy can speed up the growth rate of precipitates S’ (Cu3Al2, and Al6CuMg4 phases. The accelerated precipitation of S’ phases is proposed to be responsible for the enhanced age-hardening of the Al–Cu–Mg/BAp composites.

  18. Evaluation of aging embrittlement of low-carbon austenitic stainless steel weld metal near the BWR operating temperature

    International Nuclear Information System (INIS)

    To evaluate the rate of thermal embrittlement of type 316 low-carbon stainless steel weld metal at BWR operating temperature, aging test at 310degC, 335degC, and 400degC was carried out. Hardness of each ferrite and austenite phase of specimens was measured selectively by microhardness tester. Hardness of ferrite was increased apparently with all three aging temperatures, whereas hardness of austenite was not changed. Changes in the microstructure of ferrite aged at 310degC for 11,000h and 18,000h were analyzed by TEM. It has been revealed that hardening of ferrite with aging at 310degC was result of spinodal decomposition. Arrhenius plots for hardening rate of ferrite at each three aging temperature was plotted, and apparent activation energy was estimated. Using the apparent activation energy, hardening rate at 288degC was discussed. (author)

  19. Multi-species beam hardening calibration device for x-ray microtomography

    Science.gov (United States)

    Evershed, Anthony N. Z.; Mills, David; Davis, Graham

    2012-10-01

    Impact-source X-ray microtomography (XMT) is a widely-used benchtop alternative to synchrotron radiation microtomography. Since X-rays from a tube are polychromatic, however, greyscale `beam hardening' artefacts are produced by the preferential absorption of low-energy photons in the beam path. A multi-material `carousel' test piece was developed to offer a wider range of X-ray attenuations from well-characterised filters than single-material step wedges can produce practically, and optimization software was developed to produce a beam hardening correction by use of the Nelder-Mead optimization method, tuned for specimens composed of other materials (such as hydroxyapatite [HA] or barium for dental applications.) The carousel test piece produced calibration polynomials reliably and with a significantly smaller discrepancy between the calculated and measured attenuations than the calibration step wedge previously in use. An immersion tank was constructed and used to simplify multi-material samples in order to negate the beam hardening effect of low atomic number materials within the specimen when measuring mineral concentration of higher-Z regions. When scanned in water at an acceleration voltage of 90 kV a Scanco AG hydroxyapatite / poly(methyl methacrylate) calibration phantom closely approximates a single-material system, producing accurate hydroxyapatite concentration measurements. This system can then be corrected for beam hardening for the material of interest.

  20. Distinguishing between hydrated, partially hydrated or unhydrated clinker in hardened concrete using microscopy

    NARCIS (Netherlands)

    Valcke, S.L.A.; Rooij, M.R. de; Visser, J.H.M.; Nijland, T.G.

    2010-01-01

    Hydration of clinker particles is since long a topic of interest in both designing and optimizing cement composition and its quantity used in concrete. The interest for carefully observing and also quantifying the type or stage of clinker hydration in hardened cement paste is twofold. Firstly, the c

  1. Influence of plastic deformation on low temperature surface hardening of stainless steel by gaseous nitriding

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas Lundin;

    2015-01-01

    This article addresses an investigation of the influence of plastic deformation on low temperature surface hardening by gaseous nitriding of three commercial austenitic stainless steels: AISI 304, EN 1.4369 and Sandvik Nanoflex® with various degrees of austenite stability. The materials were plas...

  2. Laser transformation hardening of a high-purity iron-carbon-chromium alloy

    International Nuclear Information System (INIS)

    Successful laser transformation hardening of steel surfaces requires that the absorbed laser energy is sufficient to austenitize the initial microstructure to a depth of 0.5 mm or more. Hardening is accomplished when rapid cooling by conduction of heat away from the surface causes transformation of the austenite layer to martensite. Heating and cooling rates of 104 K/s or greater are typical of the laser hardening process and the entire thermal cycle may be accomplished in less than 0.1 s. In an earlier study, laser surface hardening of commercial plain carbon and chromium alloyed steels was examined. It was shown that in the alloyed steel chromium enrichment of the cementite in the initial microstructure could prevent complete transformation of pearlite to asutenite during the very rapid laser heating cycle. However, interpretation of the results was complicated somewhat by the fact that manganese was also partitioned to the cementite. The purpose of this work was to conduct selected identical laser heating experiments on a high-purity Fe-C-Cr alloy to test the effect of chromium unequivocally, i.e., in the absence of manganese and other elements normally present in commercial steels

  3. An alternative approach to estimate the W/C ratio of hardened concrete using image analysis

    NARCIS (Netherlands)

    Valcke, S.; Nijland, T.G.; Larbi, J.A.

    2009-01-01

    The water cement (w/c) ratio is a typical quality parameter for concrete. The NT Build 361 Nordtest method is a standard for estimating the w/c ratio in hardened concrete and is based on the relationship between the ilc ratio and the capillary porosity in the cement paste. The latter can be estimate

  4. 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.

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

    DEFF Research Database (Denmark)

    Tan, Ye; Kiekens, Kim; Welkenhuyzen, Frank;

    2013-01-01

    Industrial X-ray CT systems are increasingly used as dimensional measuring machines. However, micron level accuracy is not always achievable yet. The measurement accuracy is influenced by many factors, such as workpiece properties, X-ray settings, beam hardening and calibration methods [1-4]. Since...

  6. High temperature, radiation hardened electronics for application to nuclear power plants

    International Nuclear Information System (INIS)

    Electronic circuits were developed and built at Sandia for many aerospace and energy systems applications. Among recent developments were high temperature electronics for geothermal well logging and radiation hardened electronics for a variety of aerospace applications. Sandia has also been active in technology transfer to commercial industry in both of these areas

  7. Mathematical and Computer Modelling of Induction Heating and Consequent Hardening of Circular Saw

    Czech Academy of Sciences Publication Activity Database

    Barglik, J.; Doležel, Ivo; Ducki, K.; Ulrych, B.

    Amsterdam: IOS Press, 2002 - (Krawczyk, A.; Wiak, S.), s. 351-356 ISBN 1-58603-232-1 R&D Projects: GA ČR GA102/01/0184; GA MŠk ME 542 Grant ostatní: PSC(PL) 7T08C03716 Keywords : induction heating * induction hardening * electromagnetic field Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  8. State of the art of continual induction hardening: Computer modeling and experiments

    Czech Academy of Sciences Publication Activity Database

    Barglik, J.; Doležel, Ivo; Karban, P.; Ulrych, B.

    Sendai: The Iron and Steel Institute of Japan, 2006, s. 479-484. ISBN 4-930980-55-0. [ Electromagnetic Processing of Materials “EPM’2006”. Sendai (JP), 23.10.2006-27.10.2006] Institutional research plan: CEZ:AV0Z20570509 Keywords : continual induction hardening * electromagnetic field * temperature field Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  9. 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 

  10. Update on radiation-hardened microcomputers for robotics and teleoperated systems

    Energy Technology Data Exchange (ETDEWEB)

    Sias, F.R. Jr. [Clemson Univ., SC (United States). Dept. of Electrical and Computer Engineering; Tulenko, J.S. [Univ. of Florida, Gainesville, FL (United States). Dept. of Nuclear Engineering Science

    1993-12-31

    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.

  11. Quenchants for Induction Hardening for the Automotive Industry,Choice and Maintenance

    Institute of Scientific and Technical Information of China (English)

    Hartmut Beitz; Thorsten Beitz

    2004-01-01

    The different types of quenchants for induction hardening - mainly for shower quenching - but also for immersion will be described in regard to their properties, film-formation, remaining residues, how to handle these etc..Furtheron the maintenance of such quench fluids will be desribed in detail regarding concentration control, control of growth of micro-organism, contamination and maintenance.

  12. Constitutive modeling of quench-hardenable boron steel with tailored properties

    NARCIS (Netherlands)

    Eller, T.K.; Greve, L; Anders, M.T.; Medricky, M; Hatscher, A; Meinders, V.T.; Boogaard, van den A.H.; Volk, W.

    2013-01-01

    In this work, a material model is presented that predicts the crash-relevant constitutive behavior of quench-hardenable boron steel 22MnB5 as function of material hardness. Three sets of sheets of 22MnB5 are heat treated such that their as-treated microstructures are close to fully martensitic, bain

  13. Plasticity and fracture modeling of quench-hardenable boron steel with tailored properties

    NARCIS (Netherlands)

    Eller, T.K.; Greve, L.; Andres, M.T.; Medricky, M.; Hatscher, A.; Meinders, V.T.; Boogaard, van den A.H.

    2014-01-01

    In this article, a constitutive model for quench-hardenable boron steel is presented. Three sets of boron steel blanks are heat treated such that their as-treated microstructures are close to fully martensitic, bainitic and ferritic/pearlitic, respectively. Hardness measurements show that the result

  14. Goal Structured Notation in a Radiation Hardening Safety Case for COTS-Based Spacecraft

    Science.gov (United States)

    Witulski, Arthur; Austin, Rebekah; Reed, Robert; Karsai, Gabor; Mahadevan, Nag; Sierawski, Brian; Evans, John; LaBel, Ken

    2016-01-01

    A systematic approach is presented to constructing a radiation assurance case using Goal Structured Notation (GSN) for spacecraft containing COTS parts. The GSN paradigm is applied to an SRAM single-event upset experiment board designed to fly on a CubeSat November 2016. Construction of a radiation assurance case without use of hardened parts or extensive radiation testing is discussed.

  15. Self-healing behavior of strain hardening cementitious composites incorporating local waste materials

    NARCIS (Netherlands)

    Qian, S.; Zhou, J.; Rooij, M.R. de; Schlangen, E.; Ye, G.; Breugel, K. van

    2009-01-01

    The self-healing behavior of a series of pre-cracked fiber reinforced strain hardening cementitious composites incorporating blast furnace slag (BFS) and limestone powder (LP) with relatively high water/binder ratio is investigated in this paper, focusing on the recovery of its deflection capacity.

  16. Computer simulation and radiation hardening of power devices to protect against failures induced by heavy ions

    International Nuclear Information System (INIS)

    Power devices such as MOSFETSs and IGBTs, include parasitic structures that can give rise to destructive failures such as breakdown and latch-up. To determine a suitable strategy for device radiation hardening, simulation software like MEDICI-2D can be used to model the effects of technological modifications and device parameters that are difficult to measure experimentally. (authors)

  17. Method to harden coating masses made of unsaturated polyesters and partly polymerizable monomers by UV irradiation

    International Nuclear Information System (INIS)

    A method to harden mixtures of unsaturated polyesters and partly polymerizable monomeric compounds by UV irradiation is described. The material to be coated is first coated with photo sensitizers and then with the mixture of unsaturated polyesters and monomeric compounds. (HK)

  18. Method of hardening a diallyl phthalate resin by utilizing ionizing radiations

    International Nuclear Information System (INIS)

    A method for hardening a diallyl phthalate resin is disclosed to provide a resin composition which is radiation hardenable. The resin is suitable for lamination, impregnation and coating. The resin composition consists essentially of (A) 100 parts of diallyl phthalate prepolymers, (B) 30 to 100 parts of unsaturated polyesters and (C) 100 to 40 parts of monomers containing polymerizable unsaturated radicals. The prepolymers of diallyl phthalate have a linear or branched structure of a molecular weight below 25,000, generally 10,000. The unsaturated polyesters may be fumaric acid, maleic acid or glycols. The monomers may be styrene, divinyl benzen or their derivatives. The monomers, as tertiary components, make the diallyl phthalate prepolymers and the unsaturated polyesters liquid at room temperature or above to form a three dimensional structure. The radiation energy level is preferably more than 100 keV. The irradiation dose required for hardening is generally 0.5 to 6 Mrad. The irradiation can be carried out in the air by covering the material to be hardened with a film to protect it from oxygen, though a slightly larger irradiation dose is required. In one of the examples, 100 parts of diallyl phthalate prepolymer, 50 parts of unsaturated polyester resin and 50 parts of butyl acrylate constituted a resin composition. This composition was applied to the surface of veneer laminates and was exposed to electron beams, whereby a hard surface coating was produced. (Iwakiri, K.)

  19. Radiation hardenable impregnating agents for the consolidating conservation of wooden objects

    International Nuclear Information System (INIS)

    Radiation hardenable impregnating agents offer some advantages over the conventional agents. At the author's institution objects up to 110 cm length can be impregnated for conservation. More than 200 monomers and resins have been investigated. The procedure of impregnation is outlined and some kinds of wooden objects conserved in this way listed. (G.W.)

  20. Alloy hardening of a smectic A liquid crystal doped with gold nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Oswald, P.; Milette, J.; Relaix, S.; Reven, L.; Dequidt, A.; Lejček, Lubor

    2013-01-01

    Roč. 103, AUG (2013), "46004-p1"-"46004-p6". ISSN 0295-5075 Institutional support: RVO:68378271 Keywords : smectic A liquid crystals * gold nanoparticles * edge dislocation * precipitation hardening Subject RIV: BK - Fluid Dynamics Impact factor: 2.269, year: 2013