Sample records for hardening knowckdown resistance

  1. QTL for the thermotolerance effect of heat hardening, knowckdown resistance to heat and chill-coma recovery in an intercontinental set of recombinant inbred lines of Drosophila melanogaster

    Norry, Fabian M.; Scannapieco, Alejandra C.; Sambucetti, Pablo;


    The thermotolerance effect of heat hardening (also called short-term acclimation), knockdown resistance to high temperature (KRHT) with and without heat hardening and chill-coma recovery (CCR) are important phenotypes of thermal adaptation in insects and other organisms. Drosophila melanogaster......-hardened and nonhardened RIL. Composite interval mapping revealed a more complex genetic architecture for KRHT without heat-hardening than for KRHT in heat-hardened insects. Five quantitative trait loci (QTL) were found for KRHT, but only two of them were significant after heat hardening. KRHT and CCR showed trade...... decreased by heat hardening. We discuss candidate loci for each QTL. One HHE-QTL was found in the region of small heat-shock protein genes. However, HHE-QTL explained only a small fraction of the phenotypic variance. Most heat-resistance QTL did not colocalize with CCR-QTL. Large-effect QTL for CCR and KRHT...

  2. Surface Fatigue Resistance with Induction Hardening

    Townsend, Dennis; Turza, Alan; Chapman, Mike


    Induction hardening has been used for some years to harden the surface and improve the strength and service life of gears and other components. Many applications that employ induction hardening require a relatively long time to finish the hardening process and controlling the hardness of the surface layer and its depth often was a problem. Other surface hardening methods, ie., carbonizing, take a very long time and tend to cause deformations of the toothing, whose elimination requires supplementary finishing work. In double-frequency induction hardening, one uses a low frequency for the preheating of the toothed wheel and a much higher frequency for the purpose of rapidly heating the surface by way of surface hardening.

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

    Erwin H Beck; Richard Heim; Jens Hansen


    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. Raising the heat and wear resistances of hardened carbon steels by friction strengthening treatment

    Makarov, A. V.; Korshunov, L. G.; Malygina, I. Yu.; Solodova, I. L.


    The effect of friction treatment by a hard-alloy indenter on the microhardness and resistance to the heat-induced softening upon tempering of hardened medium-and high-carbon steels at 100-600°C is studied. The x-ray and electron microscopy methods are used to determine the causes of the increase in the heat resistance of the friction-strained steel surfaces. A comparative analysis of the effect of the hardening treatment by a hard-alloy indenter and by abrasive particles on the friction-induced heat resistance is performed for the case of high-speed friction treatment of a high-carbon laser-hardened steel.

  5. Development of Press Hardening Steel with High Resistance to Hydrogen Embrittlement

    Bian, Jian; Mohrbacher, Hardy; Lu, Hongzhou; Wang, Wenjun

    Press hardening has become the state-of-art technology in the car body manufacturing to enhance safety standard and to reduce CO2 emission of new vehicles. However the delayed cracking due to hydrogen embrittlement remains to be a critical issue. Generally press hardening steel is susceptible to hydrogen embrittlement due to ultra-high strength and martensitic microstructure. The hydrogen charging tests clearly demonstrate that only a few ppm of diffusible hydrogen is sufficient to cause such embrittlement. Currently the hydrogen embrittlement cannot be detected in the press hardened components and the embitteled components could collapse in the crash situation with fatal consequences arisen through dramatic loss in both strength and ductility. This paper introduces a new metallurgical solution to increase the resistance to hydrogen embrittlement of conventional press hardening steel based on 22MnB5 by Nb microalloying. In the hydrogen embrittlement and permeation tests the impact of Nb microalloying on the hydrogen embrittlement behavior was investigated under different hydrogen charging conditions and constant load. The test results revealed that Nb addition increases the resistance to hydrogen embrittlement due to reduced hydrogen diffusivity. The focus of this paper is to investigate the precipitation behavior of microalloying elements by using TEM and STEM and to find out the mechanisms leading to higher performance against hydrogen embrittlement of Nb alloyed steels.

  6. Effect of hardening temperature on the phase composition and wear resistance of roll steels with 5% Cr

    Gervas'ev, M. A.; Khudorozhkova, Yu. V.; Filippov, M. A.


    The effect of a wide range of hardening temperatures on the capacity of cold-rolling roll steels with 5% Cr (65Kh5SMF and 9Kh5SMF) for strain-induced martensitic transformation and hardening is determined. The abrasive wear resistance of the steels is studied.

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

    V.Soundararajan; N.Alagurmurthi; K.Palaniradja


    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)

  8. Genotypic variation in morphology and freezing resistance of Eucalyptus globulus seedlings subjected to drought hardening in nursery

    Coopman, Rafael E.; Jara,Jorge C; Escobar,Rene; Luis J Corcuera; Bravo,Leon A


    Eucalyptus globulus Labill is one of the most planted species in Chile, because of its fast growth and superior pulp qualities. Nevertheless, the incidence of drought and frost damage immediately after planting is frequent. The purpose of this work was to study the effect of drought hardening on frost resistance and on variations in morphological traits that may increase drought resistance at nursery phase in four genotypes of E. globulus Labill. Drought hardening treatments consisted in indu...

  9. Effect Of Laser Hardening On Microstructure And Wear Resistance In Medium. Carbon/Chromium Steels

    Kusinski, Jan; Thomas, Gareth


    Metallographical (optical, TEM, SEM), spectroscopic, abrasive wear resistance and microhardness investiga-tions of Fe/Cr/Mn/C steels heat-treated by a continuous CO2 laser are described. Laser hardening resulted in wear resistance of 1.4 - 1.6 times better than that of conventionally hardened steels. Laser melting followed by rapid solidification allows formation of a solidified layer with high wear resistance only when the scanning velocity and mass of the samples were sufficient to realize high cooling rates. The variations in the wear resistance and microhardness with distance from the heated surface were similar. The grain refinement caused by rapid laser-heating and high stresses induced during cooling create essentially fine, highly dislocated lath and internally twinned martensites with some amount of stable, interlath retained austenite. This structure has in turn beneficial effects on wear resistance, and toughness. Laser-heat treatment for deep melting of the surface layers of the steels shows only a small improvement in wear resistance. Such heat-treatment results in delta ferrite retention (10Cr steel) and chromium segregation to cell-boundaries.

  10. Characteristics of high wear resistant Ni-base materials strengthened by precipitation hardening of wolfram silicide

    Kiuchi, Kiyoshi; Ide, Hisayuki; Ishiyama, Takashi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment


    The practical application of Co-base Stellite and Ni base Inconel for reactor core components with high allowable stress levels is considered to be limited by the formation of radioactive cruds and the susceptibility to IASCC respectively. For this view-point, W-silicide strengthened Cr-W-Si Ni-base high wear resistant alloy so-called HWI alloy was newly developed as an alternative material. The chemical composition and the alloy making process were optimized by applying the electron beam purification process and the thermo-mechanical treatment. The mechanical strength higher than it of above commercial alloys was easily obtained by both solid solution hardening and precipitation hardening, because this alloy has the excellent cold and hot workabilities. The irradiation resistance and the corrosion resistance superior than these of above commercial alloys were verified by several laboratory tests of HWI heats. To maintain austenite phase stability at the practical temperature and to enrich oxide former alloying elements were clarified to be the most important means for this alloy development. (author)

  11. Modeling spray/puddle dissolution processes for deep-ultraviolet acid-hardened resists

    Hutchinson, John M.; Das, Siddhartha; Qian, Qi-De; Gaw, Henry T.


    A study of the dissolution behavior of acid-hardened resists (AHR) was undertaken for spray and spray/puddle development processes. The Site Services DSM-100 end-point detection system is used to measure both spray and puddle dissolution data for a commercially available deep-ultraviolet AHR resist, Shipley SNR-248. The DSM allows in situ measurement of dissolution rate on the wafer chuck and hence allows parameter extraction for modeling spray and puddle processes. The dissolution data for spray and puddle processes was collected across a range of exposure dose and postexposure bake temperature. The development recipe was varied to decouple the contribution of the spray and puddle modes to the overall dissolution characteristics. The mechanisms involved in spray versus puddle dissolution and the impact of spray versus puddle dissolution on process performance metrics has been investigated. We used the effective-dose-modeling approach and the measurement capability of the DSM-100 and developed a lumped parameter model for acid-hardened resists that incorporates the effects of exposure, postexposure bake temperature and time, and development condition. The PARMEX photoresist-modeling program is used to determine parameters for the spray and for the puddle process. The lumped parameter AHR model developed showed good agreement with experimental data.

  12. Influence of Heat Treatment on Mercury Cavitation Resistance of Surface Hardened 316LN Stainless Steel

    Pawel, Steven J [ORNL; Hsu, Julia [Massachusetts Institute of Technology (MIT)


    The cavitation-erosion resistance of carburized 316LN stainless steel was significantly degraded but not destroyed by heat treatment in the temperature range 500-800 C. The heat treatments caused rejection of some carbon from the carburized layer into an amorphous film that formed on each specimen surface. Further, the heat treatments encouraged carbide precipitation and reduced hardness within the carburized layer, but the overall change did not reduce surface hardness fully to the level of untreated material. Heat treatments as short as 10 min at 650 C substantially reduced cavitation-erosion resistance in mercury, while heat treatments at 500 and 800 C were found to be somewhat less detrimental. Overall, the results suggest that modest thermal excursions perhaps the result of a weld made at some distance to the carburized material or a brief stress relief treatment will not render the hardened layer completely ineffective but should be avoided to the greatest extent possible.

  13. Plasma nitriding of a precipitation hardening stainless steel to improve erosion and corrosion resistance

    Cabo, Amado, E-mail: [IONAR S.A., Buenos Aires (Argentina); Bruhl, Sonia P.; Vaca, Laura S.; Charadia, Raul Charadia, E-mail:, E-mail:, E-mail:, E-mail: [Surface Engineering Group (GIS), Universidad Tecnologica Nacional, Facultad Regional Concepcion del Uruguay (Argentina)


    Precipitation hardening stainless steels are used as structural materials in the aircraft and the chemical industry because of their good combination of mechanical and corrosion properties. The aim of this work is to analyze the structural changes produced by plasma nitriding in the near surface of Thyroplast PH X Supra®, a PH stainless steel from ThyssenKrupp, and to study the effect of nitriding parameters in wear and corrosion resistance. Samples were first aged and then nitriding was carried out in an industrial facility at two temperatures, with two different nitrogen partial pressures in the gas mixture. After nitriding, samples were cut, polished, mounted in resin and etched with Vilella reagent to reveal the nitrided case. Nitrided structure was also analyzed with XRD. Erosion/Corrosion was tested against sea water and sand flux, and corrosion in a salt spray fog (ASTM B117). All nitrided samples presented high hardness. Samples nitrided at 390 deg C with different nitrogen partial pressure showed similar erosion resistance against water and sand flux. The erosion resistance of the nitrided samples at 500 deg C was the highest and XRD revealed nitrides. Corrosion resistance, on the contrary, was diminished; the samples suffered of general corrosion during the salt spray fog test. (author)

  14. Influence of hardening and surface modification of endourological wires on corrosion resistance.

    Walke, Witold; Przondziono, Joanna


    Guide wires with suitable functional characteristics are of crucial importance for proper urological treatment. This study presents an analysis of the effect of work hardening taking place in the process of wire cold drawing and the effect of surface modification by means of electrochemical polishing and chemical passivation on the resistance of wires made of X10CrNi18-8 steel used in urology. Corrosion resistance was evaluated on the grounds of the registered anodic polarisation curves by means of potentiodynamic method. The tests were made in solution simulating human urine. Anodic polarisation curves were presented for selected wire diameters. Mechanical properties were tested in a static uniaxial tensile test. The course of flow curve as well as mathematical form of flow stress function were determined. Curves presenting the relation of polarisation resistance as a function of strain applied in the drawing process are given. The tests carried out show that surface modification by means of electrochemical polishing and then chemical passivation of wires used in endourological treatment is fundamental.

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

    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

  16. The effect of strain hardening on resistance to electrochemical corrosion of wires for orthopaedics

    Przondziono, J.; Walke, W.; Hadasik, E.; Szymszal, J.


    The purpose of this research is to evaluate electrochemical corrosion resistance of wire with modified surface, made of stainless steel of Cr-Ni-Mo type, widely used in implants for orthopaedics, depending on hardening created in the process of drawing. Tests have been carried out in the environment imitating human osseous tissue. Pitting corrosion was determined on the ground of registered anodic polarisation curves by means of potentiodynamic method with application of electrochemical testing system VoltaLab® PGP 201. Wire corrosion tests were carried out in Tyrode solution on samples that were electrochemically polished as well as electrochemically polished and finally chemically passivated. Initial material for tests was wire rod made of X2CrNiMo17-12-2 steel with diameter of 5.5 mm in supersaturated condition. Wire rod was drawn up to diameter of 1.35 mm. This work shows the course of flow curve of wire made of this grade of steel and mathematical form of yield stress function. The study also presents exemplary curves showing the dependence of polarisation resistance in strain function in the drawing process of electrochemically passivated and electrochemically polished and then chemically passivated wire.

  17. Nitrogen hardening of creep-resistant G-NiCr28W alloy

    Z. Pirowski


    Full Text Available In the group of creep-resistant materials, most important are heat-resistant nickel-based alloys. The G-NiCr28W alloy subject to detailed examinations was observed to have two different austenite-like phases. In the interdendritic spaces of alloy matrix, the presence of another phase, also characterised by paramagnetic properties, was detected. Inside this interdendritic phase, local areas of a lamellar structure, composed of both of the above mentioned phases, were present. Nitrogen treatment was observed to raise the microhardness of both these phases.The presence of nitrogen made the regions of a lamellar structure disappear completely. Their place was occupied by precipitates dispersed in the matrix, and occasionally forming large clusters.It has been observed that cold work can harden the G-NiCr28W alloy to a very small degree only, in spite of the fact that hardness isincreasing systematically with the increasing degree of cold work. The said alloy, when enriched with nitrogen added as an alloyingelement, is characterised by hardness higher than the hardness of its nitrogen-free counterpart. The value of hardness is increasing evenmore under the effect of low-degree cold work, although increasing further the degree of cold work seems to have no effect on hardnessincrease. The problem faced in nickel-based materials is the possibility of making defect-free castings from alloys with high nitrogen content. Alloys investigated in the present study were remelted, cast and subject to solidification under high nitrogen pressure in the furnace chamber. However, melting carried out under these conditions could not prevent the occurrence of non-metallic inclusions which, while being unable to pass to a riser, formed local clusters or even thin films, resulting in numerous microcracks or discontinuities encompassing large regions of the casting. This problem seems to be of major concern and is the first one to require prompt solution in the currently

  18. [Hardening of dental instruments].

    Gerasev, G P


    The possibility of prolonging the service life of stomatological instruments by the local hardening of their working parts is discussed. Such hardening should be achieved by using hard and wear-resistant materials. The examples of hardening dental elevators and hard-alloy dental drills are given. New trends in the local hardening of instruments are the treatment of their working parts with laser beams, the application of coating on their surface by the gas-detonation method. The results of research work and trials are presented.

  19. Impact of Sterilisation and Strain Hardening in Drawing Process on Resistance to Electrochemical Corrosion of Wires Intended in Cardiology

    Przondziono J.


    Full Text Available The study presents results of tests of impact of work hardening in cold drawing process, surface treatment and sterilisation on resistance to electrochemical corrosion of wires made of stainless steel X2CrNiMo 17-12-2 intended for cardiology. Potentiodynamic tests were performed on the ground of registered anodic polarisation curves in artificial plasma solution. Static uniaxial tension test made the ground for determination of strength characteristics of wires and the flow curve. Functions presenting the change of polarisation resistance according to strain applied in drawing process were selected.

  20. Influence of Induction Hardening on Wear Resistance in Case of Rolling Contact

    Šofer Michal


    Full Text Available The main aim of the presented paper is to show how heat treatment, in our case the induction hardening, will affect the wear rates as well as the ratcheting evolution process beneath the contact surface in the field of line rolling contact. Used wear model is based on shear band cracking mechanism [1] and non-linear kinematic and isotropic hardening rule of Chaboche and Lemaitre. The entire numerical simulations have been realized in the C# programming language. Results from numerical simulations are subsequently compared with experimental data.

  1. Computation-Based Analysis of the Methods of Hardening of Gears from Heat-Resistant Steels

    Semenov, M. Yu.; Gavrilin, I. N.; Ryzhova, M. Yu.


    A mathematical model is developed for estimating the contact fatigue of gears subjected to various kinds of thermochemical treatment. The model includes design of the contact stress state and of the loading capacity of the diffusion layer. The ranges of application of vacuum carburizing, vacuum carbonitriding, and ion nitriding for hardening gears with various geometrical parameters are determined.

  2. Conservation Research and Development/ New Ultra-Low Carbon High Strength Steels with Improved Bake Hardenability for Enhanced Stretch Formability and Dent Resistance

    Anthony J. DeArdo; C. Isaac Garcia


    Conservation Research and Development/New Ultra-Low Carbon High Strength Steels with Improved Bake Hardenability for Enhanced Stretch Formability and Dent Resistance. The experimental work can be divided into four phases. In each phase, the materials were received or designed, processed and tested, to evaluate the BH increment or response, as a function of compositions and processing conditions. Microstructural characterization by various techniques was performed in order to gain insights into the mechanisms of flow stress increment by bake hardening.

  3. Evaluation of Cracking Resistance of Copper-Bearing Age Hardening Steel Weldment

    CHAI Feng; YANG Cai-fu; SU Hang; ZHANG Yong-quan; XU Zhou


    The weldability of a low-carbon copper-bearing age hardening steel was evaluated using cracking susceptibility calculation, HAZ maximum hardness measurement, and Y-groove cracking evaluation test. The results show that the hardenability characteristics and cold cracking susceptibility of the steel are very low. The results also indicate that a crack-free weldment can be obtained during the welding of this type of steel even at an ambient temperature as low as -5 ℃ as well as in an absolute humidity lower than 4 000 Pa without any preheat treatment. A slight preheat treatment can prevent the joint from cracking when welding is carried out at lower ambient temperature or higher absolute humidity.

  4. Effect of Age-Hardening Treatment on Microstructure and Sliding Wear-Resistance Performance of WC/Cu-Ni-Mn Composite Coatings

    Liu, Jun; Yang, Shuai; Liu, Kai; Gui, Chibin; Xia, Weisheng


    The Cu-Ni-Mn alloy-based hardfacing coatings reinforced by WC particles (WC/Cu-Ni-Mn) were deposited on a steel substrate by a manual oxy-acetylene weld hardfacing method. A sound interfacial junction was formed between the WC particles and the Cu-Ni-Mn alloy metal matrix binder even after the age-hardening treatment. The friction and wear behavior of the hardfacing coatings was investigated. With the introduction of WC particles, the sliding wear resistance of the WC/Cu-Ni-Mn hardfacing coatings was sharply improved: more than 200 times better than that of the age-hardening-treated Cu-Ni-Mn alloy coating. The sliding wear resistances of the as-deposited and the age-hardening-treated WC/Cu-Ni-Mn hardfacing coatings were 1.83 and 2.26 times higher than that of the commercial Fe-Cr-C hardfacing coating, which is mainly ascribed to the higher volume fraction of carbide reinforcement. Owing to the precipitation of the NiMn secondary phase in the Cu-Ni-Mn metal matrix, the age-hardening-treated coating had better wear resistance than that of the as-deposited coating. The main sliding wear mechanisms of the age-hardening-treated coatings are adhesion and abrasion.



    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.


    O. S. Kobjakov


    Full Text Available Problems concerning wear resistance improvement of «Belarus» tractor brake mechanism parts are considered in the paper. Properties of ВЧ-50-pig iron are investigated as a result of laser thermal hardening by various technological methods.

  7. Determination and Analysis of Hardenability for Hot-Forging Die Steels with Deep-Hardening


    ERH end-quenching method was us ed to determine the hardenability of four kinds hot-forging die steels with dee p-hardening and hence the order of their hardenability was given. The tempering hardness of the steels was measured and the tempering resistance was studied. It was approved that ERH method is effective for the determination of hardenability of deep-hardening steel and the beginning of hardness drop in the ERH specimen is caused by bainite occurring.

  8. AISI/DOE Technology Roadmap Program: Development of Appropriate Resistance Spot Welding Practice for Transformation-Hardened Steels

    Wayne Chuko; Jerry Gould


    This report describes work accomplished in the project, titled ''Development of Appropriate Resistance Spot Welding Practice for Transformation-Hardened Steels.'' The Phase 1 of the program involved development of in-situ temper diagrams for two gauges of representative dual-phase and martensitic grades of steels. The results showed that tempering is an effective way of reducing hold-time sensitivity (HTS) in hardenable high-strength sheet steels. In Phase 2, post-weld cooling rate techniques, incorporating tempering, were evaluated to reduce HTS for the same four steels. Three alternative methods, viz., post-heating, downsloping, and spike tempering, for HTS reduction were investigated. Downsloping was selected for detailed additional study, as it appeared to be the most promising of the cooling rate control methods. The downsloping maps for each of the candidate steels were used to locate the conditions necessary for the peak response. Three specific downslope conditions (at a fix ed final current for each material, timed for a zero-, medium-, and full-softening response) were chosen for further metallurgical and mechanical testing. Representative samples, were inspected metallographically, examining both local hardness variations and microstructures. The resulting downslope diagrams were found to consist largely of a C-curve. The softening observed in these curves, however, was not supported by subsequent metallography, which showed that all welds made, regardless of material and downslope condition, were essentially martensitic. CCT/TTT diagrams, generated based on microstructural modeling done at Oak Ridge National Laboratories, showed that minimum downslope times of 2 and 10 s for the martensitic and dual-phase grades of steels, respectively, were required to avoid martensite formation. These times, however, were beyond those examined in this study. These results show that downsloping is not an effective means of reducing HTS for

  9. Effect of high-manganese cast steel strain hardening on the abrasion wear resistance in a mixture of SiC and water

    Kalandyk B.


    Full Text Available The study attempts to determine the impact of the high-manganese cast steel strain hardening on its abrasion wear resistance in a mixture of SiC and water prepared in accordance with ASTM G75. For tests, the high-manganese cast steel containing 10.7, 17.9 and 20.02% Mn was selected. The results of microstructure examinations and abrasion wear resistance tests carried out on the material in non-hardened condition and after strain hardening with a force of 539.55kN were disclosed. Additionally, the surface of samples after a 16-hour cycle of abrasion tests was examined. Moreover, based on the obtained results, the effect of different contents of Mn in cast steel was studied, mainly in terms of its impact on the abrasion wear resistance. The results obtained on the tested materials were compared with the results obtained on the low-alloyed abrasion wear-resistant cast steel L35GSM.

  10. Effect of thermal aging on pitting corrosion resistance of 16Cr - 5Ni - 1Mo precipitation hardening stainless steel

    Abdel-Karim, R.; Dawood, M.M.A.L.; Mahallawi, I.S.E.L.; Koussy, M.R.E.L. [Cairo University (Egypt). Dept. of Mining, Petroleum and Metallurgy


    Specimens of precipitation hardening 16-5-1 stainless steel were solution treated at 1050{sup o}C for 1 h followed by aging at temperatures in the range 400 - 750{sup o}C for various holding times (1 - 16 h). After heat treatment, two types of corrosion test (accelerated and immersion testing) were conducted in 6% ferric chloride solution. The results showed that the pitting corrosion resistance was affected by austenite content, {delta} ferrite and precipitation of molybdenum and chromium carbides. Three critical temperature ranges were identified, which were related to the phases formed: (a) high corrosion rate at 475{sup o}C ({delta} ferrite and M{sub o}2 C); (b) low corrosion rate at 550 - 625{sup o}C (reversed austenite and Laves phase); (c) intermediate corrosion rate at 750{sup o}C (Cr{sub 23} C{sub 6} and TiC). The morphology of the pitting was dependent on the form of the {delta} ferrite and carbides. (author)


    Experiments were made to determine the most efficient method of strain hardening railroad frog points in order to increase their fatigue resistance...Mechanical strain hardening with rolls 40 mm in diameter under a load of 8 tons produced in standard frogs cast from G13L high-manganese steel (AISI...Hadfield steel) a work-hardened surface layer 3-5 mm thick with a hardness of 340 HB. In other experiments, the frogs were hardened by exploding a

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

    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....

  13. Properties and Commercial Application of Manual Plasma Hardening

    Korotkov, V. A.


    A new method and a device for plasma hardening of various parts are considered. Installation of the new device does not require too much investment (the active mechanical productions are appropriate for its accommodation) and special choice of personnel (welders train to use it without difficulty). Plasma hardening does not deform and worsen the smoothness of the surface, which makes it possible to employ many hardened parts without finishing mechanical treatment required after bulk or induction hardening. The hardened layer (about 1 mm) produced by plasma hardening exhibits better wear resistance than after bulk hardening with tempering, which prolongs the service life of the parts.

  14. Process for hardening the surface of polymers

    Mansur, Louis K.; Lee, Eal H.


    Hard surfaced polymers and the method for making them is generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface and improved wear resistance.

  15. A hardenability test proposal

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


    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.

  16. Reinforcement of the bulk crowns excavator technology by dispersion hardening of titanium carbide to increase wear resistance

    Chumanov, I.; Anikeev, A.; Chumanov, V.


    Dispersed particles embedded in the metal, improve the mechanical properties, particularly wear resistance. Introduction of the metal particles in a controlled and their distribution is difficult because of the density difference and the metal particles introduced. This article provides a method for the introduction of particles in the volume of metal, it contains a proposed strengthening technique described experiment course. During the experiment, the volume-reinforced castings from wear-resistant steel, the results of studies of the microstructure by optical and scanning electron microscopy, and mechanical tests of prototypes have been obtained.

  17. Study on local subsidence resistance of strain-hardening municipal solid wastes%应变硬化垃圾堆体抗局部沉陷研究

    连宝琴; 朱斌; 高登; 陈云敏


    通过三种不同材料堆体的局部沉陷模型试验发现局部沉陷条件下应变硬化材料可能产生“自支撑”现象。利用模型试验和退化情况下的解析解验证了数值分析模型模拟应变硬化材料堆体局部沉陷问题的有效性。在此基础上比较了采用不同垃圾应力应变模型的分析结果,考虑堆体材料应变硬化的复合指数模型和线弹性模型计算得到的沉陷区土压力明显小于与之对应的摩尔一库伦模型计算结果,采用传统摩尔一库伦模型计算得到的沉陷区衬垫系统挠曲变形和应变值偏大,因而针对砂土材料的Giroud(1990)Trapdoor土拱效应理论应用于垃圾堆体局部沉陷分析时存在一定的局限性。进一步分析了各种参数对衬垫系统表面土压力和变形的影响,发现沉陷区衬垫系统最大挠度和最大应变随垃圾堆体高度的增加而增加,随垃圾堆体模量和加筋体刚度的增加而减小。最后提出应变硬化垃圾堆体在局部沉陷条件下衬垫系统土工膜的应变计算和加筋层的设计方法,对于垃圾填埋场衬垫系统抗局部沉陷设计具有一定的指导意义。%The fact that the strain-hardening fill under local subsidence conditions may self-support was found by using trapdoor model tests for three different filling materials. The effectiveness of the numerical analysis model to simulate the strain-hardening fills under local subsidence conditions was verified by model test results and Finn (1963) analytic solutions. Analysis results using different Municipal Solid Waste (MSW) strain-stress models were compared. The calculated soil pressures on the subsidence area using the strain-hardening models such as the composite exponential model and the linear elastic model are significantly less than the corresponding results using the Mohr-Coulomb model, deflection and strain of the liner system on the subsidence area calculated by the

  18. The Tebuconazole-based Protectant of Seeds “Bunker” Induces the Synthesis of Dehydrins During Cold Hardening and Increases the Frost Resistance of Wheat Seedlings

    A.V. Korsukova


    Full Text Available Triazole derivatives are widely used in agriculture for seed protectant of cereals against seed and soil infection. Triazole derivatives can have an effect on the biochemical and physiological functions of plants. The tebuconazole-based protectant of seeds «Bunker» (content of tebuconazole 60 grams per liter, g/L is a systemic fungicide of preventive and therapeutic action. The effect of the seed treatment by «Bunker» preparation on the shoot growth and cell viability coleoptile, synthesis of dehydrins in shoots and frost resistance etiolated winter and spring wheat seedlings has been studied. It has been shown that treatment of winter and spring wheat seed by «Bunker» preparation induces similar concentration-dependent inhibition of the coleoptiles length. At the recommended dose (0,5 liter per tonne of seeds, L/t growth inhibition was 28 - 30%, at a concentration of 1 L/t – 33 - 36%, at a concentration of 1,5 L/t – 40 - 42%, at a concentration of 3 L/t – 43 - 47%, at a concentration of 4 L/t – 48 - 51% and at 5 L/t – 53 - 56%. The treatment of wheat seed by «Bunker» preparation had no phytotoxic effect on coleoptile cells in any of the studied concentrations, on the contrary, with increasing concentration of preparation observed the increase in cell viability, as measured by recovery of 2,3,5-triphenyltetrazolium chloride. We can assume that having retardant properties, tebuconazole not only inhibits the growth of plants, but also delays their aging. The treatment of seed protectant at a concentration of 1.5 L/t induced synthesis of the dehydrins with molecular masses about 19, 21, 22, 25 and 27 kD in winter wheat shoots and 18,6, 27 and 28,5 kD in spring wheat shoots during cold hardening. Among identified dehydrins the dehydrin of 27 kD is most significantly induced both in winter and spring wheat. The treatment of seed protectant «Bunker» in the same concentration increased the frost resistance of winter and spring wheat

  19. 45钢表面激光相变硬化改性组织及耐蚀性能%Microstructure and Corrosion Resistance of Laser Transformation Hardening Modified on 45 Steel Surface



    目的:为了改善45钢表面状态,提高其表面性能,采用CO2激光器对其表面进行激光相变硬化处理。方法利用带有能谱的扫描电子显微镜( SEM/EDS )、盐雾试验机等,对激光相变硬化层组织及耐蚀性能进行了观察和分析。结果激光相变硬化层由熔化区、相变硬化区和热影响区三部分组成,其组织依次为:混合马氏体+未溶碳化物、针状马氏体、残余奥氏体。随扫描速度增加,耐蚀性先变好而后变差。结论激光相变硬化处理可改善45钢的表面性能,显著提高其耐蚀性能。%In order to improve the surface properties of 45 steel, the laser transformation hardening treatment was car-ried out by CO2 laser on its surface. The microstructure and properties of alloying layer were analyzed by scanning electron microscope with energy spectrum ( SEM/EDS) , salt spray tester, etc. The laser transformation hardening layer was consti-tuted by melting zone, transformation hardened zone and heat affected zone. The microstructure included the mixed mar-tensite plus undissolved carbides, acicular martensite, and retained austenite. With the increase of the scanning speed, the corrosion resistance increased first and then decreased. After laser transformation hardening treatment, the surface proper-ties of 45 steel were improved, which significantly increased the corrosion resistance.

  20. Laser Surface Hardening of 9CrSi Steel


    The effects of laser hardening parameters such as beam power, beam diameter and scanning rate on microstructureand hardness of 9CrSi steel were investigated. The microstructure of the surface layer of 9CrSi steel was changed frompearlite to martensite, retained austenite and carbide by laser hardening. The depth of the hardened layer increasedwith increasing laser energy density and the surface hardeness increased by 3~5 times as high as the untreated steel.The laser hardened surface had good wear resistance due to martensite and carbide in the surface layer. The wearmode at Iow speed was abrasive, while the wear mode at high speed was adhesive.

  1. Laser Hardening of Metals

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


    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.

  2. Study on Fatigue Resistance of 17-4PH Stainless Steel After Laser Transformation Hardened%17-4PH不锈钢激光淬火疲劳性能研究

    李志强; 陈昭运


    Laser surface hardening was conducted on the 17-4PH stainless steel surface, the microstructure, hardness, distribution of surface residual stress as well as fatigue life were analyzed. The results show that the cross-section of 17-4PH after laser hardening consists of hardened layer, transition layer and base metal layer. The thickness and the average micro-hardness of the hardened layer is 1.2 mm and 440 HV respectively, the hardness is higher 60-90 HV than base metal. The surface residual stress is compressive stress whose extension is over than lmm. The fatigue life is enhanced especially at the low stress situation, the crack propagation area increases, the resistance of crack propagation is improved.%对17-4PH不锈钢进行表面激光淬火,分析了激光淬火后的组织、硬度、残余应力和疲劳寿命.结果表明:激光淬火后,17-4PH不锈钢组织分为淬硬区、过渡区和基体,淬硬层深1.2mm,平均显微硬度440HV,较基体提高60~90HV,表面残余应力为压应力,压应力的范围超过1mm.17-4PH钢激光淬火后疲劳寿命提高,且在低应力下提高效果明显,裂纹源位于次表面,裂纹扩展区增大,抵抗裂纹扩展的能力增强.

  3. Plasma Arc Surface Hardening Robot Technology


    In national economy and national defense, a lot of ma chine components become worthless early because of wear and tear and corrode. It leads to huge loss of resource and material. Surface hardening of the steel cou ld form a hard, wearable, corrode-resisting layer on the surface to enhance the mechanical property of the machine component. From 1980s, there is a new method of surface hardening that is heating with plasma arc. It overcomes the shortage of old methods and is adopted in automotive product ...

  4. Hardening Azure applications

    Gaurav, Suraj


    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

  5. Concrete, hardened: Self desiccation

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


    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...

  6. RHOBOT: Radiation hardened robotics

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


    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.

  7. Grind hardening process

    Salonitis, Konstantinos


    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.

  8. Nuclear effects hardened shelters

    Lindke, Paul


    The Houston Fearless 76 Government Projects Group 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' x 8' x 22' 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 Corrpartmented 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. The specific levels of hardening to which the shelters were designed are classified and will not be mentioned during this presentation.

  9. Nickel Alloy, Corrosion and Heat-Resistant, Sheet, Strip, and Plate 72Ni - 15.5Cr - 0.95 (Cb (Nb) + Ta) - 2.5Ti - 0.70Al - 7.0Fe Consumable Electrode, Remelted or Vacuum Induction Melted, Solution Heat Treated, Precipitation-Hardenable

    SAE Aerospace Standards. London


    Nickel Alloy, Corrosion and Heat-Resistant, Sheet, Strip, and Plate 72Ni - 15.5Cr - 0.95 (Cb (Nb) + Ta) - 2.5Ti - 0.70Al - 7.0Fe Consumable Electrode, Remelted or Vacuum Induction Melted, Solution Heat Treated, Precipitation-Hardenable

  10. Industrial Hardening Demonstration.


    less severe conditions than thermal cracking (850’ - 950°F and 10 to 20 psi). Zeolitic or molecular sieve- base catalysts are used. Catalytic reforming...with Potential Industrial Hardening A-1 Participants B Post-Attack Petroleum Refining (and Production) B-1 from Crude Oil V List of Figures Number Page...the Key Worker Shelter 116 viii B-1 Proportions of the Products Obtained by Distillation B-2 of Six Crude Oils B-2 Generalized Flow Chart of the

  11. Cosmic Ray Helium Hardening

    Ohira, Yutaka


    Recent observations by CREAM, ATIC-2 and PAMELA experiments suggest that (1) the spectrum of cosmic ray (CR) helium is harder than that of CR proton below the knee $10^15 eV$ and (2) all CR spectra become hard at $\\gtrsim 10^{11} eV/n$. We propose a new picture that higher energy CRs are generated in more helium-rich region to explain the hardening (1) without introducing different sources for CR helium. The helium to proton ratio at $\\sim 100$ TeV exceeds the Big Bang abundance $Y=0.25$ by several times, and the different spectrum is not reproduced within the diffusive shock acceleration theory. We argue that CRs are produced in the chemically enriched region, such as a superbubble, and the outward-decreasing abundance naturally leads to the hard spectrum of CR helium when escaping from the supernova remnant (SNR) shock. We provide a simple analytical spectrum that also fits well the hardening (2) because of the decreasing Mach number in the hot superbubble with $\\sim 10^6$ K. Our model predicts hard and con...

  12. Evaluation of Strain Hardening Parameters

    DING Zong-hai; Pavel Huml; YANG Wei


    The plane-strain compression test for three kinds of materials was carried out in a temperature range between room temperature and 400 ℃. The σ - ε curves and strain-hardening rate at different temperatures were simulated and a reasonable fit to the experimental data was obtained. A modified model created by data inference and computer simulation was developed to describe the strain hardening at a large deformation, and the predicted strain hardening are in a good agreement with that observed in a large range of stress. The influences of different parameters on strain hardening behaviour under large deformation were analysed. The temperature increase within the test temperatures for stainless steel 18/8 Ti results in dropping of flow stress and strain-hardening rate. For favourable γ-fibre texture to obtain high r, the cold rolling was applied at large reduction. In the experimental procedure, the X-ray diffraction test was carried out to compare the strain hardening and microstructure under large deformation for a bcc steel (low carbon steel SS-1142). The results indicate that the high strain-hardening rate possibly occurs when the primary slip plane {110} is parallel to the rolling plane and the strain-hardening rate decreases when lots of {110} plane rotate out from the orientation {110}∥RP.

  13. Laser hardening processing on tool steel SKD61



    This paper is aimed at overcoming different degree defects of crystalline structure in SKD61 carbide tool steel under quenching in solid phase and liquid phase. The paper studies the micro-structure and properties of laser strengthening SKD61 by using the method of laser hardening on the rein-forcement to improve the wear resistance of SKD61 . The results showed that the laser strengthening meth-od can improve the wear resistance of SKD61 . The study can provide reference for laser hardening metal materials.

  14. Effect of size discrepancy of. gamma. - and. gamma. '-phases crystal lattice parameters on heat resisting dispersion hardening nickel alloys

    Petrushin, N.V.; Ignatova, I.A.; Logunov, A.V.; Samojlov, A.I.; Razumovskij, I.M.

    Effect of Cr, Co, Nb and W alloying elements on crystal lattice parameters of ..gamma.. ahd ..gamma..' phases in Ni-Cr-Co-W-Al-Ti- Nb-Hf alloys and on their dimensional misfit at 293 and 1173 K is studied. Alloying at which alloys have the parameter of ..gamma..-solid solution lattice less than that of ..gamma..'-phase results in low heat-resistant properties and in considerable difference of coefficients of thermal expansion of the phases. Definite positive misfit of ..gamma..- and ..gamma..'-phase lattices and a low temperature gradient are the conditions of high heat resistance of complex-alloyed nickel alloys. Possible mechanisms of lattice misfit effect on strength and coalescence kinetics of the second phase in heterogeneous alloys at high temperatures are discussed.

  15. Electron beam surface hardening of 42CrMo4 steel

    Jokinen, T.; Meuronen, I. [Valmet Aviation Industries, Linnavuori (Finland). Engine Maintenance


    A study is reported in this paper which aims to find the proper parameters of an electron beam machine for using electron beam (EB) hardening on 42CrMo4 steel. Extended service life for engineering components depends on hard, wear resistant surfaces combined with tough base materials. EB hardening is particularly suitable to local treatment of complex components. Although surface hardening of 42CrMo4 steel was successful, careful optimization of process parameters and the hardened layer are required. (UK).

  16. An Evaluation of the Corrosion and Mechanical Performance of Interstitially Surface Hardened Stainless Steel


    metallography and microhardness profiling. The corrosion performance of the hardened surface is assessed using electrochemical potentiodynamic testing to...cracking resistance, and galling performance. Metallurgical Evaluation: Microhardness testing was conducted for Processes B1 and B2, which represent...incorporated experimental testing conducted on 316L stainless steel that has been surface hardened using available commercial techniques, using both

  17. An Evaluation of the Corrosion and Mechanical Performance of Interstitially Surface-Hardened Stainless Steel

    Jones, Jennifer L.; Koul, Michelle G.; Schubbe, Joel J.


    A surface hardening technique called "interstitial hardening" is commercially available, whereby interstitial carbon atoms are introduced into stainless steel surfaces without the formation of carbides. Surface hardening of machine elements such as impellors or fasteners would improve performance regarding cavitation and galling resistance, and has intensified interest in this process. However, there remains a need to characterize and validate the specific performance characteristics of the hardened materials. This paper describes experimental testing conducted on 316L stainless steel that has been surface hardened using available commercial techniques, using carbon as the interstitial atom. The corrosion performance of the hardened surface is assessed using electrochemical potentiodynamic testing to determine the breakdown potential in 3.5 wt.% NaCl solution to identify the most promising method. The hardness and thickness of the surface-hardened layer is characterized and compared using metallography and microhardness profiling. Corrosion fatigue and slow strain rate testing of untreated, hardened, and damaged, hardened surfaces exposed to ASTM seawater is conducted. Finally, critical galling stresses are determined and compared. Post-test examination of damage attempts to identify mechanisms of material failure and characterize how corrosion-assisted cracks initiate and grow in surface-hardened materials.

  18. System-Level Radiation Hardening

    Ladbury, Ray


    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.

  19. Contact allergy to epoxy hardeners.

    Aalto-Korte, Kristiina; Suuronen, Katri; Kuuliala, Outi; Henriks-Eckerman, Maj-Len; Jolanki, Riitta


    Diglycidylether of bisphenol A resin is the most important sensitizer in epoxy systems, but a minority of patients develop concomitant or solitary contact allergy to epoxy hardeners. At the Finnish Institute of Occupational Health, several in-house test substances of epoxy hardeners have been tested in a special epoxy compound patch test series. To analyse the frequency and clinical relevance of allergic reactions to different epoxy hardeners. Test files (January 1991 to March 2013) were screened for contact allergy to different epoxy hardeners, and the clinical records of patients with allergic reactions were analysed for occupation, concomitant allergic reactions, and exposure. The most commonly positive epoxy hardeners were m-xylylenediamine (n = 24), 2,4,6-tris-(dimethylaminomethyl)phenol (tris-DMP; n = 14), isophorone-diamine (n = 12), and diethylenetriamine (n = 9). Trimethylhexamethylenediamine (n = 7), tetraethylenepentamine (n = 4), and triethylenetetramine (n = 2) elicited some reactions, although most patients were found to have no specific exposure. Allergic reactions to hexamethylenetetramine, dimethylaminopropylamine and ethylenediamine dihydrochloride were not related to epoxy products. Tris-DMP is an important sensitizer in epoxy hardeners, and should be included in the patch test series of epoxy chemicals. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Influence of Laser Power on the Hardening of Ti6Al4V Low-Pressure Steam Turbine Blade Material for Enhancing Water Droplet Erosion Resistance

    Mann, B. S.; Arya, Vivek; Pant, B. K.


    To overcome water droplet erosion of Ti6Al4V alloy blade material used in low-pressure steam turbine (LPST) of high-rating nuclear and super critical thermal power plants, high-power diode laser (HPDL) surface treatment at two temperatures corresponding to two different power levels was carried out. During incubation as well as under prolonged erosion testing, the HPDL surface treatment of this alloy has enhanced its resistance significantly. This is due to the formation of fine-grained martensitic (ά) phase due to rapid heating and cooling associated with laser treatment. The droplet erosion test results after HPDL surface treatment on this alloy, SEM, XRD analysis, and residual stresses developed due to HPDL surface treatment are given in this paper.

  1. Microstructure and properties of cast iron after laser surface hardening



    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.

  2. Onycholysis induced by nail hardener.

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


    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.

  3. Changes in morpho-physiological attributes of Eucalyptus globulus plants in response to different drought hardening treatments

    Coopman, Rafael E.; Jara,Jorge C; Bravo,Leon A; Sáez,Katia L; Mella,Gloria R; Escobar,Rene


    Morpho-physiological attributes exhibited in response to drought hardening at the end of the growing season of Eucalyptus globulus Labill under nursery conditions were studied to evaluate the effect of three drought hardening treatments in morpho-physiological traits used as suitable indicators of drought hardiness, such as, plant growth, root growth potential, plant water relationships and survival. Freezing resistance of drought hardened plants was also studied in order to evaluate cross ha...

  4. Durability of High Performance Color Hardener

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


    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.

  5. Microstructures and Wear Resistance of the TiC-TiB2 Composite Coating Deposited by Electrical Discharge Hardening%TiC-TiB2电火花复合强化层组织与耐磨性



    TiC-TiB2 composite coating was deposited by electrical discharge hardening onto the surface of 40Cr steel with using TiC and TiB2 composite rod as electrode. The composite coating structure and phase compositions were characterized by SEM and XRD, the hardness and its distribution along coating were measured on micro-hardness machine. Wear resistance of strengthen layer was evaluated on MM-200 wear experiment machine. The microstruc-tures.mechanical property and wear resistance of the TiC-TiB2 composite coating were analyzed, and the wear mechanism of strengthened layer was studied The results suggest that the major phases of the composite coating are TiB2, TiC and Fe3C, the fine crystalline structure and non-crystalline make the diffracting peak widening. The micro hardness distribution along depth of composite coating is unhomogeneous; the micro hardness value of the composite coating is about 4 times the size of the substrate. The wear mechanism of 40Cr steel is mainly attributed to micro-cutting and adhesive wear,but the wear mechanism of composite coating is mainly attributed to micro-cutting, scratch and fatigue abrasion. The results show that the change of wear mechanism between the samples induces to the hard particles and higher hardness of composite coating. Compared with the substrate, wear resistance of composite coating is 5 times higher, wear coefficient of the coating decreased by 0.12 to 0. 17 under the same wear environment.%以TiC-TiB2复合材料为电极,采用电火花表面强化技术,在40Cr钢表面制备出TiC-TiB2复合强化层.利用SEM和XRD分析了强化层的微观结构和物相,测试了强化层的硬度和耐磨性,并探讨了其磨损机理.结果表明:强化层物相主要为TiB2、TiC和Fe3C等,非晶组织和组织细化使其衍射峰宽化;强化层的显微硬度分布呈梯度变化,最高硬度值是基体硬度值的4倍多;强化层中的硬质相和较高的显微硬度改变了试样间的磨损机制,强化层


    S. S. Samotugin


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

  7. Energetic model of metal hardening

    Ignatova O.N.


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

  8. Scintillation-Hardened GPS Receiver

    Stephens, Donald R.


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

  9. Interaction between alloying and hardening of cast iron surface

    刘政军; 郝雪枫; 傅迎庆; 牟力军


    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.

  10. Optimizing hardenability of high chromium white cast iron

    SU Ying-long; LI Dan; ZHANG Xue-kun


    The formulas proposed by J. Dodd and J. L. Parks for calculating the hardenability of high-Cr white cast iron under continuous cooling condition was recommended. For broader application, some supplements were made to the formula. Through tests on the half-cooling time of typical castings, the compositions of ideal alloys were precisely designed using the Dodd's formula. Hardness testing of heat-treated castings showed that the designed compositions were correct. The application of castings demonstrated excellent abrasion resistance.

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

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


    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.

  12. Radiation Hardened Electronics for Extreme Environments

    Keys, Andrew S.; Watson, Michael D.


    The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation hardening, low temperature extremes are addressed with a focus on material and design approaches.

  13. Simultaneous surface engineering and bulk hardening of precipitation hardening stainless steel

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


    This article addresses simultaneous bulk precipitation hardening and low temperature surface engineering of two commercial precipitation hardening stainless steels: Sandvik Nanoflex® and Uddeholm Corrax®. Surface engineering comprised gaseous nitriding or gaseous carburising. Microstructural....... The duration and temperature of the nitriding/carburising surface hardening treatment can be chosen in agreement with the thermal treatment for obtaining optimal bulk hardness in the precipitation hardening stainless steel....

  14. Tribotechnical and Energy Assessment of Parts of Working Members of Cultivating Machines After Carburizing and Laser Hardening

    Pyndak, V. I.; Novikov, A. E.


    Results of experimental studies of low-carbon steel 20 and high-carbon steels of types 70 and 65G after carburizing, heat treatment and laser hardening are presented. The variation of the microhardness of the surface layers of the steels and of their wear resistance due to different variants of hardening is determined. Optimum modes of treatment aimed at raising the strength and wear resistance are suggested for the steels used for working members of cultivating machines.


    Ms. Irina L. Polyanskaya


    Full Text Available The article presents the research results of carbon steel electrical resistance changes at low tem-pering and determines the effect of temperature on the electrical resistance. The analysis of the results showed that the influence of carbon on the value of the electrical resistance is higher than the influence of the crystal structure defects. The changes of the hardened steel electrical resistance are due to the redistri-bution of carbon.

  16. Challenges in hardening technologies using shallow-trench isolation

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


    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.

  17. Deformation Wave Hardening of Metallic Materials

    A.V. Kirichek


    Full Text Available The article deals with the machine parts hardening by means of deformation waves generated by the impact system with a waveguide as an intermediary member. The conditions for the efficient use of impact energy for elastoplastic deformation of the processed material and creation of the deep hardened surface layer.

  18. Investigation of a Hardened Cement Paste Grout

    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....

  19. Method of hardening a fluid mass

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


    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

  20. Method of hardening a fluid mass

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


    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

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

    Kim, Junehyung; Cheon, Jinsik; Lee, Byoungoon; Lee, Chanbock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    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.

  2. Effect of laser surface hardening on the microstructure, hardness and residual stresses of austempered ductile iron grades

    Soriano, C., E-mail: [Tekniker-IK4, Manufacturing Processes Department, Avda. Otaola 20, CP-20600, Eibar (Gipuzkoa) (Spain); Leunda, J.; Lambarri, J.; Garcia Navas, V.; Sanz, C. [Tekniker-IK4, Manufacturing Processes Department, Avda. Otaola 20, CP-20600, Eibar (Gipuzkoa) (Spain)


    A study of the laser surface hardening process of two austempered ductile iron grades, with different austempering treatments has been carried out. Hardening was performed with an infrared continuous wave Nd:YAG laser in cylindrical specimens. The microstructure of the laser hardened samples was investigated using an optical microscope, microhardness profiles were measured and surface and radial residual stresses were studied by an X-ray diffractometer. Similar results were achieved for both materials. A coarse martensite with retained austenite structure was found in the treated area, resulting in a wear resistant effective layer of 0.6 mm to 1 mm with a microhardness between 650 HV and 800 HV. Compressive residual stresses have been found at the hardened area being in agreement with the microhardness and microstructural variations observed. The achieved results point out that the laser surface hardening is a suitable method for improving the mechanical properties of austempered ductile irons.

  3. Open Source Radiation Hardened by Design Technology

    Shuler, Robert


    The proposed technology allows use of the latest microcircuit technology with lowest power and fastest speed, with minimal delay and engineering costs, through new Radiation Hardened by Design (RHBD) techniques that do not require extensive process characterization, technique evaluation and re-design at each Moore's Law generation. The separation of critical node groups is explicitly parameterized so it can be increased as microcircuit technologies shrink. The technology will be open access to radiation tolerant circuit vendors. INNOVATION: This technology would enhance computation intensive applications such as autonomy, robotics, advanced sensor and tracking processes, as well as low power applications such as wireless sensor networks. OUTCOME / RESULTS: 1) Simulation analysis indicates feasibility. 2)Compact voting latch 65 nanometer test chip designed and submitted for fabrication -7/2016. INFUSION FOR SPACE / EARTH: This technology may be used in any digital integrated circuit in which a high level of resistance to Single Event Upsets is desired, and has the greatest benefit outside low earth orbit where cosmic rays are numerous.

  4. The influence of Glassex additive on properties of microwave-hardened and self- hardened moulding sands with water glass

    K. Major-Gabryś


    Full Text Available The article takes into consideration the researches concerning inserting the Glassex additive to the microwaved-hardened and self- hardened moulding sands with water glass. In the research different types of ester hardeners to self-hardened moulding sands with water glass were used. The influence of Glassex additive on retained strength of moulding sands with different hardeners and prepared by different technologies of hardening were tested. The influence of different hardeners and the technology of hardening on retained strength of moulding sand with water glass and the Glassex additive were also estimated.

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

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


    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.

  6. Thermomechanical hardening of stable and metastable austenitic steels

    Baraz, V. R.; Gladkovskii, S. V.; Ishina, E. A.


    Phase composition, mechanical properties, and variation of the density of cold-deformed Fe-Cr-Ni-Mn steels differing in the stability of austenite are studied. A comparative analysis of formation of phase composition and accumulation of discontinuities in the process of drawing of stable and metastable austenitic steels is performed. The effect of post-deformation annealing on the variation of the density and mechanical properties is considered. The capacity for recovery of the density is shown to be correlated with the resistance of the studied thermomechanically hardened steels to fatigue fracture. The determined dependences are explained.


    A. V. Kovalchuk


    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.

  8. An Oxygen-Permeation Treatment for Hardening Titanium Alloys

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


    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.

  9. Infrared Camera Analysis of Laser Hardening

    J. Tesar


    Full Text Available The improvement of surface properties such as laser hardening becomes very important in present manufacturing. Resulting laser hardening depth and surface hardness can be affected by changes in optical properties of material surface, that is, by absorptivity that gives the ratio between absorbed energy and incident laser energy. The surface changes on tested sample of steel block were made by engraving laser with different scanning velocity and repetition frequency. During the laser hardening the process was observed by infrared (IR camera system that measures infrared radiation from the heated sample and depicts it in a form of temperature field. The images from the IR camera of the sample are shown, and maximal temperatures of all engraved areas are evaluated and compared. The surface hardness was measured, and the hardening depth was estimated from the measured hardness profile in the sample cross-section. The correlation between reached temperature, surface hardness, and hardening depth is shown. The highest and the lowest temperatures correspond to the lowest/highest hardness and the highest/lowest hardening depth.


    O. S. Kobjakov


    Full Text Available The paper considers pertaining to higher wear resistance of «Belarus» tractor brake mechanisms details are considered. Properties of ВЧ-50-cast iron are investigated due to laser hardening while using various technological methods.

  11. Sinter-hardening of Ni-Mo pre-alloyed powders with tungsten addition

    L.A. Dobrzański


    Full Text Available Purpose: Purpose of this paper was to present the benefits of powder metallurgy technology and development ofsinter-hardening process. The mechanical properties, focusing in particular on hardness and wear resistance, oftwo different carbon levels pre-alloyed steel powders processed with sinter-hardening method, were described.Microstructure characteristic of produced sinter-hardened Ni-Mo steels with increasing amount of tungsten(from 0 to 0.3% wt. was taken under consideration.Design/methodology/approach: Different compositions have been tested in order to investigate the influenceof various tungsten additions into low (0.4% and high (0.6% carbon content of pre-alloyed steel powders.Powders, with addition of 0.7% lubricant, were pressed in a 2000kN hydraulic press. De-waxing process at550ºC for 60 minutes in a fully nitrogen atmosphere was performed before the sintering. Sintering was carriedout in vacuum furnace with argon backfilling. The furnace was equipped with a cooling zone to provideaccelerated cooling from the sintering temperature. Green compacts were sintered at the temperature 1120ºC for1 hour and rapidly cooled with a rate 2.5ºC/s.Findings: The applied sinter-hardening process resulted with achievement of material characterized by goodwear resistance. The investigation of Ni-Mo and Ni-Mo-W sinter-hardened steels with low and high carboncontent 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 compositionand applied process of steels preparation, sinter-hardening with the cooling rate 2.5ºC/s, results in achieving materialswith relatively high hardness and significant resistance to abrasion. Anyhow, further research should be performed.Originality/value: Sinter-hardening of Ni-Mo pre-alloyed powders with the addition of different additions oftungsten, especially in terms of

  12. On Analytical Solutions to Beam-Hardening

    Rigaud, G.


    When polychromatic X-rays propagate through a material, for instance in computerized tomography (CT), low energy photons are more attenuated resulting in a "harder" beam. The beam-hardening phenomenon breaks the monochromatic radiation model based on the Radon transform giving rise to artifacts in CT reconstructions to the detriment of visual inspection and automated segmentation algorithms. We propose first a simplified analytic representation for the beam-hardening. Besides providing a general understanding of the phenomenon, this model proposes to invert the beam-hardening effect for homogeneous objects leading to classical monochromatic data. For heterogeneous objects, no analytical reconstruction of the density can be derived without more prior information. However, the beam-hardening is shown to be a smooth operation on the data and thus to preserve the encoding of the singularities of the attenuation map within the data. A microlocal analysis encourages the use of contour extraction methods to solve partially the beam-hardening effect even for heterogeneous objects. The application of both methods, exact analytical solution for homogeneous objects and feature extraction for heterogeneous ones, on real data demonstrates their relevancy and efficiency.

  13. Determination of Constant Parameters of Copper as Power-Law Hardening Material at Different Test Conditions

    Kowser Md. A.


    Full Text Available In this paper a technique has been developed to determine constant parameters of copper as a power-law hardening material by tensile test approach. A work-hardening process is used to describe the increase of the stress level necessary to continue plastic deformation. A computer program is used to show the variation of the stress-strain relation for different values of stress hardening exponent, n and power-law hardening constant, α . Due to its close tolerances, excellent corrosion resistance and high material strength, in this analysis copper (Cu has been selected as the material. As a power-law hardening material, Cu has been used to compute stress hardening exponent, n and power-law hardening constant, α from tensile test experiment without heat treatment and after heat treatment. A wealth of information about mechanical behavior of a material can be determined by conducting a simple tensile test in which a cylindrical specimen of a uniform cross-section is pulled until it ruptures or fractures into separate pieces. The original cross sectional area and gauge length are measured prior to conducting the test and the applied load and gauge deformation are continuously measured throughout the test. Based on the initial geometry of the sample, the engineering stress-strain behavior (stress-strain curve can be easily generated from which numerous mechanical properties, such as the yield strength and elastic modulus, can be determined. A universal testing machine is utilized to apply the load in a continuously increasing (ramp manner according to ASTM specifications. Finally, theoretical results are compared with these obtained from experiments where the nature of curves is found similar to each other. It is observed that there is a significant change of the value of n obtained with and without heat treatment it means the value of n should be determined for the heat treated condition of copper material for their applications in engineering

  14. Secondary Hardening, Austenite Grain Coarsening and Surface Decarburization Phenomenon in Nb-Bearing Spring Steel


    The secondary hardening, the austenite grain coarsening and the surface decarburization phenomenon of Nb-bearing spring steel were investigated, and the effects of niobium on tempered microstructure was studied using scanning electron microscope. The results show that the micro-addition of niobium increases the tempering resistance and produces secondary hardening. The effect of niobium on the size and distribution of cementite particles is one of the primary reasons to increase the hardness after tempering. The grain-coarsening temperature of the spring steel is raised 150 ~C due to Nb-addition. Furthermore, both the secondary hardening and the austenite grain coarsening phenomenon congruously demonstrate niobium begins observably dissolving above 1 100 ℃ in the spring steel. Be- sides, niobium microalloying is an effective and economy means to decrease the decarburization sensitivity of the spring steels.

  15. Modeling of Irradiation Hardening of Polycrystalline Materials

    Li, Dongsheng; Zbib, Hussein M.; Garmestani, Hamid; Sun, Xin; Khaleel, Mohammad A.


    High energy particle irradiation of structural polycrystalline materials usually produces irradiation hardening and embrittlement. The development of predict capability for the influence of irradiation on mechanical behavior is very important in materials design for next generation reactors. In this work a multiscale approach was implemented to predict irradiation hardening of body centered cubic (bcc) alpha-iron. The effect of defect density, texture and grain boundary was investigated. In the microscale, dislocation dynamics models were used to predict the critical resolved shear stress from the evolution of local dislocation and defects. In the macroscale, a viscoplastic self-consistent model was applied to predict the irradiation hardening in samples with changes in texture and grain boundary. This multiscale modeling can guide performance evaluation of structural materials used in next generation nuclear reactors.

  16. An Anisotropic Hardening Model for Springback Prediction

    Zeng, Danielle; Xia, Z. Cedric


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

  17. Induction surface hardening of hard coated steels

    Pantleon, Karen; Kessler, Olaf; Hoffmann, Franz


    -process is the high deposition temperature, consequently the properties of steel substrates are negatively influenced. Therefore, a subsequent heat treatment of the coated steels is necessary to restore the properties of steels ready for operation. Induction surface hardening is used as a method of heat treatment....... The effect of induction surface hardening on the properties of the coating-substrate-systems is mainly characterized using investigations of microstructure and chemical composition as well as measurements of hardness and residual stresses in dependence on the distance from the surface. Furthermore......, 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....

  18. Investigation on hardening behavior of metallic glass under cyclic indentation loading via molecular dynamics simulation

    Zhao, Dan; Zhao, Hongwei; Zhu, Bo; Wang, Shunbo


    Mechanical behavior of a Cu-Zr metallic glass (MG) under cyclic indentation loading is investigated via molecular dynamics simulation. A large-depth indentation after cycling is conducted, and the indentation curves show that hardening behavior occurs with cyclic indentation amplitudes exceeding elastic range. The atomic Von Mises shear strain distributions during the large-depth indentation are investigated, and the pre-existing plastic deformation induced by cyclic indentation is found to be the main contributor to the hardening behavior. By monitoring the atom trajectories and Voronoi atom volume, structure densification and free volume reduction phenomenon are found in the area beneath indenter after cycles. The accumulations of irreversible shear strain during cycling induce the area beneath indenter experience atom structure transition and become densified, thus the sample becomes more resistant to further deformation. In addition, the effects of temperatures and loading rates on the hardening behavior are studied. With higher temperature, more homogenous deformation and plasticity are produced, and then inducing more severe hardening in the MG. While with lower loading rate, the hardening phenomenon is found to be less severe because of the localization of shear strain during cycling.

  19. A novel radiation hardened by design latch

    Huang Zhengfeng; Liang Huaguo


    Due to aggressive technology scaling, radiation-induced soft errors have become a serious reliability concern in VLSI chip design. This paper presents a novel radiation hardened by design latch with high single-event-upset (SEU) immunity. The proposed latch can effectively mitigate SEU by internal dual interlocked scheme. The propagation delay, power dissipation and power delay product of the presented latch are evaluated by detailed SPICE simulations. Compared with previous SEU-hardening solutions such as TMR-Latch, the presented latch is more area efficient, delay and power efficient. Fault injection simulations also demonstrate the robustness of the presented latch even under high energy particle strikes.

  20. "Work-Hardenable" ductile bulk metallic glass.

    Das, Jayanta; Tang, Mei Bo; Kim, Ki Buem; Theissmann, Ralf; Baier, Falko; Wang, Wei Hua; Eckert, Jürgen


    Usually, monolithic bulk metallic glasses undergo inhomogeneous plastic deformation and exhibit poor ductility (< 1%) at room temperature. We present a new class of bulk metallic glass, which exhibits high strength of up to 2265 MPa together with extensive "work hardening" and large ductility of 18%. Significant increase in the flow stress was observed during deformation. The "work-hardening" capability and ductility of this class of metallic glass is attributed to a unique structure correlated with atomic-scale inhomogeneity, leading to an inherent capability of extensive shear band formation, interactions, and multiplication of shear bands.

  1. Radiation hardening revisited: Role of intracascade clustering

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


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

  2. Investigation of Hardened Filling Grout Samples

    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....

  3. Induction surface hardening of hard coated steels

    Pantleon, Karen; Kessler, Olaf; Hoffmann, Franz


    . The effect of induction surface hardening on the properties of the coating-substrate-systems is mainly characterized using investigations of microstructure and chemical composition as well as measurements of hardness and residual stresses in dependence on the distance from the surface. Furthermore......, 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....

  4. Self hardening property of Botswana fly ash | Sahu | Botswana ...

    Self hardening property of Botswana fly ash. ... In the present investigation, an effort has been made to study the self hardening property of Botswana fly ash by ... This will encourage the use of fly ash economically as a construction material.

  5. Feasibility Studies on Underwater Laser Surface Hardening Process

    Biao Jin


    Full Text Available 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 Gaussian distribution of energy in the beam. For the surface hardening, single-track melting experiment which sequentially scans elongated path of single line has been performed. As the hardened depth depends on the thermal conductivity of the material, the surface temperature and the penetration depth may be varied by underwater laser processing. The feasibility of underwater laser surface hardening process is discussed on the basis of average hardness level and hardened bead shape.

  6. Microstructural aspects and wear behavior of sinter hardened distaloy HP

    Sheikhi Moghaddam, K.; Ghambari, M.; Farhangi, H. [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran (Iran, Islamic Republic of); Solimanjad, N.; Bergmark, A. [Hoeganaes AB, Bruksgatan, Hoeganaes (Sweden); Khorsand, H. [K.N. Toosi University, Tehran (Iran, Islamic Republic of)


    Effect of cooling rate during sinter hardening on the microstructure and wear behavior of sintered steel grade Distaloy HP has been studied. Wear performances are closely related to macro and micro hardness of the materials. Dry sliding wear tests have been conducted using a reciprocating pin on flat wear testing machine under normal loads of 25, 35 and 45N and at a constant speed of 0.3 m/s. The samples were sinter hardened at different cooling rates 0.5-3 C/s in order to investigate the influence of microstructure and hardness on wear behavior. It has been shown that, sintering process and cooling rate change the microstructure and hence the hardness and wear behavior of the material. The best wear resistance was detected at a cooling rate of 3 C/s. At this cooling rate the material had an almost martensitic microstructure and the wear rate was some how independent of the applied load. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Feasibility Studies on Underwater Laser Surface Hardening Process

    Biao Jin; Min Li; TaeWoo Hwang; YoungHoon Moon


    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 ...



    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...

  9. Instabilities in power law gradient hardening materials

    Niordson, Christian Frithiof; Tvergaard, Viggo


    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...

  10. A New Method of Hardening Inner Wall of Long Pipe


    A new laser inner wall hardening method for long pipe mas introduced. The system combines laser surface hardening with robot moving in pipeline. Some craft experiments have been done with this system and optimum parameters of laser hardening have been found.

  11. Origin of the Cosmic Ray Spectral Hardening

    Tomassetti, N


    Recent data from ATIC, CREAM and PAMELA indicate that the cosmic ray energy spectra of protons and nuclei exhibit a remarkable hardening at energies above 100 GeV per nucleon. We propose that the hardening is an interstellar propagation effect that originates from a spatial change of the cosmic ray transport properties in different regions of the Galaxy. The key hypothesis is that the diffusion coefficient is not separable into energy and space variables as usually assumed. Under this scenario, we can reproduce well the observational data. Our model has several implications for the cosmic ray acceleration/propagation physics and can be tested by ongoing experiments such as AMS or Fermi/LAT.

  12. Construction procedures using self hardening fly ash

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


    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.

  13. Radiation-hardened transistor and integrated circuit

    Ma, Kwok K.


    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.

  14. Hardening of ODS ferritic steels under irradiation with high-energy heavy ions

    Ding, Z. N.; Zhang, C. H.; Yang, Y. T.; Song, Y.; Kimura, A.; Jang, J.


    Influence of the nanoscale oxide particles on mechanical properties and irradiation resistance of oxide-dispersion-strengthened (ODS) ferritic steels is of critical importance for the use of the material in fuel cladding or blanket components in advanced nuclear reactors. In the present work, impact of structures of oxide dispersoids on the irradiation hardening of ODS ferritic steels was studied. Specimens of three high-Cr ODS ferritic steels containing oxide dispersoids with different number density and average size were irradiated with high-energy Ni ions at about -50 °C. The energy of the incident Ni ions was varied from 12.73 MeV to 357.86 MeV by using an energy degrader at the terminal so that a plateau of atomic displacement damage (∼0.8 dpa) was produced from the near surface to a depth of 24 μm in the specimens. A nanoindentor (in constant stiffness mode with a diamond Berkovich indenter) and a Vickers micro-hardness tester were used to measure the hardeness of the specimens. The Nix-Gao model taking account of the indentation size effect (ISE) was used to fit the hardness data. It is observed that the soft substrate effect (SSE) can be diminished substantially in the irradiated specimens due to the thick damaged regions produced by the Ni ions. A linear correlation between the nano-hardeness and the micro-hardness was found. It is observed that a higher number density of oxide dispersoids with a smaller average diameter corresponds to an increased resistance to irradiation hardening, which can be ascribed to the increased sink strength of oxides/matrix interfaces to point defects. The rate equation approach and the conventional hardening model were used to analyze the influence of defect clusters on irradiation hardening in ODS ferritic steels. The numerical estimates show that the hardening caused by the interstitial type dislocation loops follows a similar trend with the experiment data.


    O. V. Dvornikov


    Full Text Available Problems of specialized analog integrated circuit design for sensor equipments are considered. It is offered to produce of radiation hardened analog IC on structured chips for economic efficiency at small production volume. The approach to analog IC design is described, including recommendations for choice of: types and quantities of structured chip analogue components; active and passive components; schematic decisions of analogue components with programmed parameters and small sensitivity to radiation. 

  16. Dislocation Multi-junctions and Strain Hardening

    Bulatov, V; Hsiung, L; Tang, M; Arsenlis, A; Bartelt, M; Cai, W; Florando, J; Hiratani, M; Rhee, M; Hommes, G; Pierce, T; Diaz de la Rubia, T


    At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects--dislocations. First theorized in 1934 to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed only two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain hardening: a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain hardening to pair-wise dislocation reactions in which two intersecting dislocations form junctions tying dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed hereafter multi-junctions. The existence of multi-junctions is first predicted by Dislocation Dynamics (DD) and atomistic simulations and then confirmed by the transmission electron microscopy (TEM) experiments in single crystal molybdenum. In large-scale Dislocation Dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain hardening in BCC crystals.

  17. Beam hardening correction algorithm in microtomography images

    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


    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)

  18. Improved manufacturing techniques for rf and laser hardening of missile domes, phase 1

    Pawlewicz, W. T.; Mann, I. B.; Martin, P. M.; Hays, D. D.; Graybeal, A. G.


    The adaptation of an existing Pacific Northwest Laboratory (PNL) optical coating capability developed for high power fusion laser applications to the case of RF and laser hardening of plastic missile domes used by US Army (MICOM) is reported. RF hardening of Hellfire and Copperhead 1.06 micron missile domes by use of transparent conductive Indium Tin Oxide (ITO) coatings is demonstrated. The project involved adaptation of a coating material and process developed for flat glass components used in fusion lasers to the case of hemispherical or conical heat sensitive plastic domes used on laser guided missiles. Specific ITO coating property goals are an electrical sheet resistance of 10 ohms/square, a coated dome transmission of 80% or more at 1.06 micron wavelength (compared to 90% for a bare dome), and good adhesion. The sheet resistance goal of 10 ohms/square was expected to result in an RF attenuation of 30 dB at the frequencies of importance.

  19. Industrial Experience with Case Hardening of Stainless Steels by Solution Nitriding

    Hans Berns; Bernd Edenhofer; Roland Zaugg


    SolNit(R) is a novel heat treatment to case harden stainless steels with nitrogen instead of carbon. The calculated equilibrium pressure of N2 corresponds well with the nitrogen content in the steel surface. The process is carried out in vacuum furnaces with pressurized gas quenching. Numerous parts of different stainless steels have been successfully SolNit(R) treated in industry leading to superior properties in respect to hardness/strength and corrosion resistance

  20. Empirical beam hardening correction (EBHC) for CT

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


    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. The influence of laser line hardening of carbon steel AISI 1045 on the lubricated wear against steel AISI 52100

    Visscher, H.; Rooij, de M.B.; Vroegop, P.H.; Schipper, D.J.


    To diminish wear in tribological systems it is not always necessary to provide the entire surface with a wear resistant layer. Depending on the application it is sufficient to harden locally the load carrying areas which are subjected to wear. Such areas can be treated properly by a laser, either to

  2. [Hardened anodized aluminum as a replacement material for bracket manufacture].

    Fischer-Brandies, H; Bönhoff, M


    Attention has been repeatedly drawn to the problem of corrosion and the risk of allergic reaction to nickel resulting from the use of stainless steel brackets. In the search for a suitable alternative, manufacturers have turned to thin coating technology using hardened anodized aluminium. Applying resistance to corrosion and abrasion as the criteria to be met, they have selected aluminium alloy type 6082 as the material of choice. Purpose of this study is to examine the physical suitability of this material. Using the above noted alloy, 60 prototype brackets were made with a hardened anodized surface. They were then subjected to the following 3 stress tests: first an abrasion test using a tooth polishing machine, second, a deformation test using a device designed to simulate torque movement, and, third, a corrosion test. The effects on the brackets resulting from the three types of stress were evaluated by light microscopy. A quantitative analysis of the corrosion test was performed by ICP spectrometry. The control group consisted of conventional stainless steel brackets. The light microscopic analysis revealed no evidence of surface damage or signs of deformation in the prototype brackets. The steel brackets, on the other hand, showed clear signs of wear and corrosion. The quantitative analysis of the corrosion solution revealed metallic ion wear of 1.75 ng x mm-2 x h-1 for the prototypes subjected to abrasion. The steel brackets showed at a factor of around 104.6 metallic ion wear of 183 ng x mm-2 x h-1. In addition to this, no Ni ions were found in the corrosion solution of the prototype brackets.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. 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

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


    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.

  4. Configurable Radiation Hardened High Speed Isolated Interface ASIC Project

    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...




    Full Text Available This paper deals with the study of the performance of coated tools in machining hardening steel under dry conditions. This paper involves of machining AISI 4340 hardened steel using coated carbide tools is studied using full factorial experiments. Many parameters influence the quality of the products in hard turning process. The objective of this study is on the effect of the cutting conditions such as cutting velocity, feed, and depth of cut on the surface finish in machining AISI 4340 hardened steel. Machining of hardened steels has become an important manufacturing process, particularly in the automotive and bearing industries.

  6. Additive strengthening mechanisms in dispersion hardened polycrystals

    Hansen, Niels; Ralph, B.


    Tensile data from polycrystalline samples of copper dispersion strengthened by alumina are analysed. The basis of this analysis is to look at the strain range from 0.05 to 0.20 where the stress-strain curves show a parabolic hardening behaviour and are parallel to one another. The means by which...... the dislocation density contributions from each of these three sources. The type of additivity suggested here not only gives very good agreement with the stress-strain data but it also uses and is in accord with the experimental measurements of dislocation densities made using transmission electron microscopy....


    V. I. Serebrovskii


    Full Text Available Summary. Currently in the repair and manufacture at the stage of recovery of steel parts, widely used special coatings formed by electrolytic effects on ferrous ions. This technique offers high performance, ease of implementation, low cost of technological equipment and materials used, as well as easy automation of the process. However, this method has several disadvantages: low fatigue strength of reconditioned parts, insufficiently strong grip of the iron coating to the substrate, particularly in alloy steels, insufficient wear resistance. For the purpose of increasing durability and wear resistance of parts, restored through electrochemical action, it is proposed to use chemical-heat treatment, consisting in the application of carbonitriding. Investigated the efficacy of different modes of carbonitriding in the highly carburizing paste-and their influence on the structure and properties of iron plating. It is established that the nitrocarburizing both low and high temperatures repeatedly (6-7.5 times increases the microhardness of the coatings. The highest hardness is obtained by low-temperature carbonitriding with direct quenching in water. Conducting the carbonitriding process at low temperatures (650 °C, significantly increases the hardness of the iron coatings, increasing the limit of its fluidity, a and also greatly increases its endurance limit. Nitrocarburized fatigue strength of samples with iron precipitation on the surface, as shown by our studies, not only higher strength of the same samples without carbonitriding (more than 2 times, but higher than the fatigue strength of the base metal without coatings. Raising the temperature of the carbonitriding did not increase the hardness of electrolytic iron. Developed a rational technology of hardening of steel parts, re-chain iron fortification. Selected optimum conditions for carbonitriding hardening restored iron fortification, with the purpose of increasing durability of machine

  8. Impact of mild temperature hardening on thermotolerance, fecundity, and Hsp gene expression in Liriomyza huidobrensis.

    Huang, Li-Hua; Chen, Bing; Kang, Le


    The pea leafminer, Liriomyza huidobrensis, is one of the most important economic insect pests around the world. Its population fluctuates greatly with seasonal change in China, and temperature was thought to be one of the important reasons. In attempt to further explore the impact of disadvantageous temperature on L. huidobrensis, 1-day-old adults were shocked at various temperatures (10, 25, 32, and 35 degrees C, respectively) for 4h, and the effects on thermotolerance, feeding, and fecundity were studied. Meanwhile the expression of five heat shock genes (hsp90, 70, 60, 40, and 20) was examined by real-time quantitative PCR. Our results showed that both 32 and 35 degrees C hardenings remarkably increased adult heat resistance, whereas cold tolerance was not improved accordingly. No cross resistance in response to cold and heat stresses was observed. Both adult feeding and fecundity were dramatically reduced, but no effect was observed on egg hatching, larval survival, pupal eclosion, or sex ratio. The results indicate that the deleterious effect on fecundity is the result of direct cessation of oviposition during the period of stress. Simultaneously, the mRNA levels of hsp70 and hsp20 significantly increased upon thermal hardening. Taken together, our results suggest that mild heat hardening improves thermotolerance of L. huidobrensis at the cost of impairment on fecundity, and the induced expression of hsp70 and hsp20 may play an important role in balancing the functional tradeoff.

  9. Hardened Client Platforms for Secure Internet Banking

    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.

  10. Hardness variability in commercial and hardened technologies

    Shaneyfelt, M.R.; Winokur, P.S.; Meisenheimer, T.L.; Sexton, F.W.; Roeske, S.B.; Knoll, M.G.


    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.

  11. A procedure for hardening steel 45 by plastic deformation using a simple roller

    Tomás Fernández Columbíe


    Full Text Available This work presents the techniques used in an experimental design leading to evaluating the behaviour of an indepen-dent variable force (P, ranging from 500 up to 2500 N, 27 minimum revolution number (n, average 54 and maxi-mum 110 rev/min and 0.075, 0, 125 and 0.25 mm/rev advance for determining the dependent hardness (H pa-ttern when AISI 1045 steel test tubes were subjected to surface rolling for creating a compressive state deforming and increasing its resistance to abrasive wear and fatigue. The variables involved in the process were statistically a-nalysed, revealing increased hardness ranging from 220 up to 262 HV. Optical microscopy was used for analysing the effect of hardening caused by deformation, establishing a mechanism for hardening steel by the elements in the crystalline network sliding due to burnishing.

  12. Optimization of Laser Beam Transformation Hardening by One Single Parameter

    Meijer, J.; Sprang, van I.


    The process of laser beam transformation hardening is principally controlled by two independent parameters, the absorbed laser power on a given area and the interaction time. These parameters can be transformed into two functional parameters: the maximum surface temperature and the hardening depth.

  13. [Hardening of dental tissue by CO2 laser radiation].

    Aboites, V; Díaz, O; Cuevas, F


    A study was conducted to test the effects of CO2 laser irradiation on dental tissue. It was found that hardening of the dental tissue occurs. This was observed qualitatively by direct observation and by X-ray radiography. The hardening produced was also quantitatively measured using a hardness-meter on Rockwell scale.

  14. Design and characterization of cellulose nanocrystal-enhanced epoxy hardeners

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


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


    HESS, F


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

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

    彭芳乐; 李建中


    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.

  17. Precipitation hardening in 350 grade maraging steel

    Viswanathan, U.K. (Bhabha Atomic Research Centre, Bombay, (India). Radiometallurgy Div.); Dey, G.K. (Bhabha Atomic Research Centre, Bombay, (India). Metallurgy Division); Asundi, M.K. (Government Colony, Bombay, (India))


    Evolution of microstructure in 350 grade commercial maraging steel has been examined. In the earlier stages of aging, the strengthening phases are formed by the heterogeneous precipitation, and these phases have been identified as intermetallic compounds of the Ni[sub 3] (Ti, Mo) and Fe[sub 2]Mo types. The kinetics of precipitation are studied in terms of the activation energy by carrying out isothermal hardness measurements of aged material. The mechanical properties in the peak-aged and overaged conditions were evaluated and the flow behavior examined. The overaging behavior of the steel has been studied and the formation of austenite of different morphologies identified. The crystallography of the austenite has been examined in detail. From the microstructural examination of peak-aged and deformed samples, it could be inferred that the dislocation-precipitate interaction is by precipitate shearing. Increased work hardening of the material in the overaged condition was suggestive of looping of precipitates by dislocations.

  18. Precipitation hardening in 350 grade maraging steel

    Viswanathan, U. K.; Dey, G. K.; Asundi, M. K.


    Evolution of microstructure in a 350 grade commercial maraging steel has been examined. In the earlier stages of aging, the strengthening phases are formed by the heterogeneous precipitation, and these phases have been identified as intermetallic compounds of the Ni3 (Ti, Mo) and Fe2Mo types. The kinetics of precipitation are studied in terms of the activation energy by carrying out isothermal hardness measurements of aged material. The mechanical properties in the peak-aged and overaged conditions were evaluated and the flow behavior examined. The overaging behavior of the steel has been studied and the formation of austenite of different morphologies identified. The crystallography of the austenite has been examined in detail. From the microstructural examination of peak-aged and deformed samples, it could be inferred that the dislocation-precipitate interaction is by precipitate shearing. Increased work hardening of the material in the overaged condition was suggestive of looping of precipitates by dislocations.

  19. Jerky loads on surface-hardened gears

    Rettig, H.; Wirth, X.


    Damage occurs again and again in practice in the form of transmissions with surface hardened gears which break after a very long operating time (explained by seldom occurring jerky loads). Gear drives are frequently exposed to jerky stresses which are greater than their fatigue limit. These stresses are considered in gear calculations, first, by shock factors when the transmission is to be designed as high endurance with regard to overloads and, second, in the form of operating ratios when the design is to be time enduring with regard to overloads. The size of the operating ratio depends not only on torque characteristics, drive and processing machine, but also on the material and heat treatment.

  20. Keystroke Dynamics-Based Credential Hardening Systems

    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.

  1. Dilatant hardening of fluid-saturated sandstone

    Makhnenko, Roman Y.; Labuz, Joseph F.


    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.

  2. Spectral Hardening and Geoeffectiveness of Solar Flares

    Jain, R.; Kumar, S.; Dave, H.; Deshpande, M. R.

    We present the results of a few typical flares that observed by the first space borne solar astronomy experiment of India namely "Solar X-ray Spectrometer (SOXS)" mission, which has completed one year of its successful operation in geostationary orbit. The SOXS mission onboard GSAT-2 Indian spacecraft was launched successfully by GSLV-D2 rocket on 08 May 2003 to study the energy release and particle acceleration in solar flares. The SOXS is composed of two independent payloads viz. SOXS Low Energy Detector (SLD) payload, and SOXS High Energy Detector (SHD) payload. We restrict our presentation to SLD payload that designed, developed and fabricated by Physical Research Laboratory (PRL) in collaboration with Space Application Centre (SAC), Ahmedabad and ISRO Satellite Centre (ISAC), Bangalore of Indian Space Research Organization (ISRO). We briefly present the scientific objectives and instrumentation of the SLD payload. The SLD payload employs the state-of-art solid state detectors viz. Si PIN and CZT detectors, which reveal sub-keV spectral and 100ms temporal resolution characteristics that are necessary to study the spectral response of the flare components. The dynamic range of Si and CZT detectors is 4-25 and 4-56 keV respectively. The SLD has observed more than 140 flares of C and M class since its commissioning in the orbit. We present the X-ray emission characteristics of a few typical flares in view of their spectral hardening and geo-effectiveness. We extend our study of these flares to optical and radio waveband observations in order to improve the relationship of X-ray spectral hardening and geo-effectiveness. The flares with harder spectra and associated with small or large CME, and radio emission at frequencies above 10 GHz are found geo-effective.

  3. Method of Electrolyte-Plasma Surface Hardening of 65G and 20GL Low-Alloy Steels Samples

    Rakhadilov, Bauyrzhan; Zhurerova, Laila; Pavlov, Alexander


    This work is devoted to formation of modified surface layers in 65G and 20GL steels which using for the manufacture of railway transport parts, as well as the study of influence of the parametersof electrolyte-plasma surface hardening methodon the changes in structural-phase states, improving of wear-resistance. The process of electrolyte-plasma surface hardening of 65G and 20GL steels samples conducted in the electrolyte from water solution of 20% sodium carbonate, in the mode ~850°C - 2 seconds, ∼⃒1200°C - 3 seconds. It is established that in the initial state 20GL steel has ferrite-pearlite structure, and the 60G steel consists of pearlite and cement structure. After application of electrolyte-plasma surface hardening is observed the formation of carbides particles and martensite phase components in the structure of 20GL and 60G steels. It is determined that after electrolyte-plasma surface hardening with heating time - 2 seconds, the abrasive wear-resistance of 65G and 20GL steels increased to 1.3 times and 1.2 times, respectively, and the microhardness is increased to 1.6 times and 1.3 times, respectively.

  4. Porosity and mechanically optimized PLGA based in situ hardening systems.

    Schloegl, W; Marschall, V; Witting, M Y; Volkmer, E; Drosse, I; Leicht, U; Schieker, M; Wiggenhorn, M; Schaubhut, F; Zahler, S; Friess, W


    Goal of the present study was to develop and to characterize in situ-hardening, porous PLGA-based systems for their future application as bone grafting materials. Therefore, we investigated the precipitation behavior of formulations containing PLGA and a water-miscible solvent, DMSO, PEG 400, and NMP. To increase porosity, a pore forming agent (NaCMC) was added and to enhance mechanical properties of the system, an inorganic filler (α-TCP) was incorporated. The behavior upon contact with water and the influence of the prior addition of aqueous media on the morphology of the corresponding hardened implants were investigated. We proved cell-compatibility by live/dead assays for the hardened porous polymer/ceramic-composite scaffolds. The IsHS formulations can therefore be used to manufacture hardened scaffolds ex vivo by using molds with the desired shape and size. Cells were further successfully incorporated into the IsHS by precultivating the cells on the α-TCP-powder prior to their admixing to the formulation. However, cell viability could not be maintained due to toxicity of the tested solvents. But, the results demonstrate that in vivo cells should well penetrate, adhere, and proliferate in the hardened scaffolds. Consequently, we consider the in situ hardening system being an excellent candidate as a filling material for non-weight-bearing orthopedic indications, as the resulting properties of the hardened implant fulfill indication-specific needs like mechanical stability, elasticity, and porosity.

  5. Tailored work hardening descriptions in simulation of sheet metal forming

    Vegter, Henk; Mulder, Hans.; van Liempt, Peter; Heijne, Jan


    In the previous decades much attention has been given on an accurate material description, especially for simulations at the design stage of new models in the automotive industry. Improvements lead to shorter design times and a better tailored use of material. It also contributed to the design and optimization of new materials. The current description of plastic material behaviour in simulation models of sheet metal forming is covered by a hardening curve and a yield surface. In this paper the focus will be on modelling of work hardening for advanced high strength steels considering the requirements of present applications. Nowadays work hardening models need to include the effect of hard phases in a soft matrix and the effect of strain rate and temperature on work hardening. Most material tests to characterize work hardening are only applicable to low strains whereas many practical applications require hardening data at relatively high strains. Therefore, physically based hardening descriptions are needed allowing reliable extensions to high strain values.

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

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


    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.

  7. Ovarian dual oxidase (Duox) activity is essential for insect eggshell hardening and waterproofing.

    Dias, Felipe A; Gandara, Ana Caroline P; Queiroz-Barros, Fernanda G; Oliveira, Raquel L L; Sorgine, Marcos H F; Braz, Glória R C; Oliveira, Pedro L


    In insects, eggshell hardening involves cross-linking of chorion proteins via their tyrosine residues. This process is catalyzed by peroxidases at the expense of H2O2 and confers physical and biological protection to the developing embryo. Here, working with Rhodnius prolixus, the insect vector of Chagas disease, we show that an ovary dual oxidase (Duox), a NADPH oxidase, is the source of the H2O2 that supports dityrosine-mediated protein cross-linking and eggshell hardening. RNAi silencing of Duox activity decreased H2O2 generation followed by a failure in embryo development caused by a reduced resistance to water loss, which, in turn, caused embryos to dry out following oviposition. Phenotypes of Duox-silenced eggs were reversed by incubation in a water-saturated atmosphere, simultaneous silencing of the Duox and catalase genes, or H2O2 injection into the female hemocoel. Taken together, our results show that Duox-generated H2O2 fuels egg chorion hardening and that this process plays an essential role during eggshell waterproofing.

  8. Advantages of dry hardened cask storage over wet storage for spent nuclear fuel

    Romanato, Luiz Sergio, E-mail: [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), Sao Paulo, SP (Brazil). Dept. da Qualidade


    Pools are generally used to store and maintain spent nuclear fuel assemblies for cooling, after removed from reactors. After three to five years stored in the pools, spent fuel can be reprocessed or sent to a final disposition in a geological repository and handled as radioactive waste or sent to another site waiting for future solution. Spent fuel can be stored in dry or wet installations, depending on the method adopted by the nuclear plant. If this storage were exclusively wet, at the installation decommissioning in the future, another solution for storage will need to be found. Today, after a preliminary cooling, the spent fuel assemblies can be removed from the pool and sent to dry hardened storage installations. This kind of storage does not need complex radiation monitoring and it is safer than wet storage. Brazil has two nuclear reactors in operation, a third reactor is under construction and they use wet spent fuel storage . Dry hardened casks use metal or both metal and concrete for radiation shielding and they are safe, especially during an earthquake. An earthquake struck Japan on March 11, 2011 damaging Fukushima Daiichi nuclear power plant. The occurrence of earthquakes in Brazil is very small but dry casks can resist to other events, including terrorist acts, better than pools. This paper shows the advantages of dry hardened cask storage in comparison with the wet storage (water pools) for spent nuclear fuel. (author)

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

    Nakai, Ryosuke; Yabuuchi, Kiyohiro; Nogami, Shuhei; Hasegawa, Akira


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


    LIUTeng-xi; HUANGShi-qing; FUYi-ming


    A dimensionless stress yield criterion is proposed to describe the mixed hardening of orthortropic material ,including kinematic hardening and proportional hardening,and the associated plastic flow law is derived.The generalized effective stress-strain formulae can be obtained correspondingly based on the experimental stress-strain curves in various simple stress states.The initial plastic anisotropy is influenced by the elastic anisotropy.The yield criterion can be reduced to Huber-Mises Criterion for isotropic materials and associated constitutive equations can be degenerated into Prandtl-Reuss equations.


    刘腾喜; 黄世清; 傅衣铭


    A dimensionless stress yield criterion is proposed to describe the mixed hardening of orthotropic material, including kinematic hardening and proportional hardening, and the associated plastic flow law is derived. The generalized effective stress-strain formulae can be obtained correspondingly based on the experimental stress-strain curves in various simple stress states. The initial plastic anisotropy is influenced by the elastic anisotropy. The yield criterion can be reduced to Huber-Mises Criterion for isotropic materials and associated constitutive equations can be degenerated into Prandtl-Reuss equations.

  12. Variations in the Bainite Hardenability of ASTM A723 Steel


    8217, ,- -’ . . • • . . . . -. . " . ,~ .. -- --. x n~ I]AD TECHNICAL REPORT ARCCB-TR-87012 VARIATIONS IN THE BAINITE U) HARDENABILITY OF ASTM A723 STEEL 0’) 00 PAUL J. COTE LAWRENCE V...rod ,SuDfll|m) S. ?YPl[ Off REPOR.r & Pl[RIOO COVER•O VARIATIONS IN THE; BAINITE HARDENABILITY OF Final ASTH A723 STEEL I. Pl[RFORMINQ ORO. REPORT...0.1%) and copper (0.1%) in A723. A key transformation characteristic for this alloy is the bainite hardenability. It is important to know the extent to

  13. Study on Heat Hardening Mechanism of Starch Composite Binder for Sand Mold (Core) by IR Spectra

    Xia ZHOU; Jinzong YANG; Qin GAO; Guohui QU


    The heat hardening mechanism of starch composite binder for sand mold (core) was studied by way of IR spectra. It is thought that the bonding strength of molding sand is mainly depended on the strength of the adhesive membrane itself. During heating the binder at certain temperature between 160~200℃ for one hour, a special composite structure is formed because of the interactions between different components, thus, it has higher low-temperature drying strength,better humidity resistance and higher high-temperature strength.

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

    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...

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

    Wang Jina; Fan Zitian; Zan Xiaolei; Pan Di


    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.

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

    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...

  17. Tensile Strain Hardening Behavior and Fractography of Superalloy GH39

    WANG Hui


    Full Text Available The strain hardening behaviour and fractography of superalloy GH39 was investigated by tensile test at different strain rates. Results indicate that strain hardening behaviours are different during the deformation process. True stress-strain curve obeys the Hollomon relationship partly. The strain hardening exponentn in this stage is constant in the initial plastic stage. However, the value of n increased with true strain ε increasing when true strain is between 0.014 and 0.13. A lot of deformation twinning can be found, the twins and dislocations worked together to increase the value of n. The strain hardening exponent is increased lightly with the strain rate increasing, SEM observations show that in the case of low strain rate, the fracture mode is typical ductile, but there is a tendency from ductile to brittle fracture with increasing the strain rate.

  18. Radiation Hardened Ethernet PHY and Switch Fabric Project

    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...

  19. Technologies Enabling Custom Radiation-Hardened Component Development Project

    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....

  20. Novel SEU hardened PD SOI SRAM cell

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


    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.

  1. Cylindrical shell buckling through strain hardening

    Bandyopadhyay, K.; Xu, J.; Shteyngart, S. [Brookhaven National Lab., Upton, NY (United States); Gupta, D. [USDOE, Germantown, MD (United States)


    Recently, the authors published results of plastic buckling analysis of cylindrical shells. Ideal elastic-plastic material behavior was used for the analysis. Subsequently, the buckling analysis program was continued with the realistic stress-strain relationship of a stainless steel alloy which does not exhibit a clear yield point. The plastic buckling analysis was carried out through the initial stages of strain hardening for various internal pressure values. The computer program BOSOR5 was used for this purpose. Results were compared with those obtained from the idealized elastic-plastic relationship using the offset stress level at 0.2% strain as the yield stress. For moderate hoop stress values, the realistic stress-grain case shows a slight reduction of the buckling strength. But, a substantial gain in the buckling strength is observed as the hoop stress approaches the yield strength. Most importantly, the shell retains a residual strength to carry a small amount of axial compressive load even when the hoop stress has exceeded the offset yield strength.

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

    Lilholt, Hans


    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...... 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....

  3. Strain Hardening of Polymer Glasses: Entanglements, Energetics, and Plasticity

    Hoy, Robert S.; Robbins, Mark O.


    Simulations are used to examine the microscopic origins of strain hardening in polymer glasses. While stress-strain curves for a wide range of temperature can be fit to the functional form predicted by entropic network models, many other results are fundamentally inconsistent with the physical picture underlying these models. Stresses are too large to be entropic and have the wrong trend with temperature. The most dramatic hardening at large strains reflects increases in energy as chains are ...

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

    L. V. Tarasenko


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

  5. High-Performance, Radiation-Hardened Electronics for Space Environments

    Keys, Andrew S.; Watson, Michael D.; Frazier, Donald O.; Adams, James H.; Johnson, Michael A.; Kolawa, Elizabeth A.


    The Radiation Hardened Electronics for Space Environments (RHESE) project endeavors to advance the current state-of-the-art in high-performance, radiation-hardened electronics and processors, ensuring successful performance of space systems required to operate within extreme radiation and temperature environments. Because RHESE is a project within the Exploration Technology Development Program (ETDP), RHESE's primary customers will be the human and robotic missions being developed by NASA's Exploration Systems Mission Directorate (ESMD) in partial fulfillment of the Vision for Space Exploration. Benefits are also anticipated for NASA's science missions to planetary and deep-space destinations. As a technology development effort, RHESE provides a broad-scoped, full spectrum of approaches to environmentally harden space electronics, including new materials, advanced design processes, reconfigurable hardware techniques, and software modeling of the radiation environment. The RHESE sub-project tasks are: SelfReconfigurable Electronics for Extreme Environments, Radiation Effects Predictive Modeling, Radiation Hardened Memory, Single Event Effects (SEE) Immune Reconfigurable Field Programmable Gate Array (FPGA) (SIRF), Radiation Hardening by Software, Radiation Hardened High Performance Processors (HPP), Reconfigurable Computing, Low Temperature Tolerant MEMS by Design, and Silicon-Germanium (SiGe) Integrated Electronics for Extreme Environments. These nine sub-project tasks are managed by technical leads as located across five different NASA field centers, including Ames Research Center, Goddard Space Flight Center, the Jet Propulsion Laboratory, Langley Research Center, and Marshall Space Flight Center. The overall RHESE integrated project management responsibility resides with NASA's Marshall Space Flight Center (MSFC). Initial technology development emphasis within RHESE focuses on the hardening of Field Programmable Gate Arrays (FPGA)s and Field Programmable Analog

  6. Improved manufacturing techniques for RF and laser hardening of missile domes. Phase I. Technical report

    Pawlewicz, W.T.; Mann, I.B.; Martin, P.M.; Hays, D.D.; Graybeal, A.G.


    This report summarizes key results and accomplishements during the first year of a Manufacturing Methods and Technology project to adapt an existing Pacific Northwest Laboratory (PNL) optical coating capability developed for high-power fusion-laser applications to the case of rf and laser hardening of plastic missile domes used by the US Army (MICOM). The primary objective of the first year's work was to demonstrate rf hardening of Hellfire and Copperhead 1.06-micron missile domes by use of transparent conductive Indium Tin Oxide (ITO) coatings. The project thus involved adaptation of a coating material and process developed for flat glass components used in fusion lasers to the case of hemispherical or conical heat-sensitive plastic domes used on laser-guided missiles. Specific ITO coating property goals were an electrical sheet resistance of 10 Ohms/square, a coated-dome transmission of 80% or more at 1.06 micron wavelength (compared to 90% for a bare dome), and good adhesion. The sheet resistance goal of 10 Ohms/square was expected to result in an rf attenuation of 30 dB at the frequencies of importance.

  7. The Tribological Properties of Laser Hardened Steel 42CrMo4 / Właściwości Tribologiczne Stali 42Crmo4 Hartowanej Laserowo

    Tarasiuk W.


    Full Text Available The paper presents results of research tribological properties laser hardened steel 42CrMo4. Parameter influencing on the quality of the hardened surface was laser head speed. The study was conducted on friction tester pin-on-disc type T-11, and a counter sample disc was silicate. Parameter determining the quality of the surface layer is the intensity of wear. Based on the results we obtain information about the laser head speed to temper steel 42CrMo4 so as to maintain a high resistance to wear.

  8. Influence of Hardening Model on Weld Residual Stress Distribution

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


    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

  9. Reduction of work hardening rate in low-carbon steels

    Yalamanchili, Bhaskar Rao

    Low carbon grades of steel rods are used to produce finished products such as fine wire, coat hangers, staples, and roofing nails. These products are subject to ductility failures during production due to excessively high work hardening rates during wire drawing. The high work hardening rates are attributed to the presence of residuals, free nitrogen, or combinations thereof. This research concludes that the most cost-effective way to reduce the work hardening rate during wire drawing is to combine boron with nitrogen to form boron nitride, and thus reducing its work hardening contribution. The results of this study also conclude the following: (1) Boron/Nitrogen ratio is the more significant factor than rod tensile strength, which affects work hardening rate. Higher ratio is better in the 0.79 to 1.19 range. (2) Maintaining this narrow B/N range requires precise process control. (3) Process conditions such as dissolved oxygen (Steel Texas (North Star) benefited from this research by being able to provide a competitive edge in both quality and cost of its low carbon boron grades thus making North Star a preferred supplier of wire rod for these products.

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

    Ganesh, Vijay; Rinard, Martin


    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...

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

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


    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 co...... 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.......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...

  12. Ion implantation method for preparing polymers having oxygen erosion resistant surfaces

    Lee, Eal H.; Mansur, Louis K.; Heatherly, Jr., Lee


    Hard surfaced polymers and the method for making them are generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface, improved wear resistance, and improved oxygen erosion resistance.

  13. Simultaneous Inhibition of Linolenic Acid Synthesis in Winter Wheat Roots and Frost Hardening by BASF 13-338, a Derivative of Pyridazinone.

    Willemot, C


    Treatment of 12-day-old winter wheat (Triticum aestivum) plants with BASF 13-338 {4-chloro-5 (dimethylamino)-2-phenyl-3(2H)-pyridazinone} 36 hours before frost hardening simultaneously and completely inhibits accumulation of linolenic acid in the roots during the hardening period and the acquisition of frost resistance. Increased unsaturation of fatty acids is therefore probably an important part of the mechanism of cold adaptation in winter wheat.BASF 13-338 also prevents the increase in per cent dry weight in roots and shoots during hardening and causes a decrease in root lipid phosphorus and total fatty acids.The concurrent increase in linoleic acid and decrease in linolenic acid in the treated plants, while the level of the other fatty acids is but little affected, suggest that BASF 13-338 specifically inhibits linoleic acid desaturase.

  14. 压射头的激光表面硬化工艺%Surface laser hardening of punch head

    梁荣; 常晓惠; 谢伟; 董凤丹


    Experiments of laser remelting and phase transformation hardening were carried out on punch head made of QT 600-3 nodular cast iron.The hardened layer microstructure and wear-resistance were investigated , and service life of the punch heads treated by different laser hardening process was compared .Result shows that a fine ledeburite on surface layer obtained by laser remelting has excellent wear -resistance, this makes the maximum service life of punch heads raise to 4.8 times.%对QT600-3球墨铸铁压射头表面分别进行激光相变硬化处理和激光熔凝处理,研究了两种激光强化工艺的硬化层组织和耐磨性,比较了这两种激光处理压射头的使用寿命。结果表明,经激光熔凝处理得到的表层细小莱氏体具有最好的耐磨性,使得压射头的使用寿命最高提高到4.8倍。


    Wei-Dan Ding,


    Full Text Available This study examines the dimensional stability of fast-growing poplar clones wood after treatment by impregnation with methyl methacrylate (MMA. Six hybrid poplar clones from one plantation in Quebec were sampled. The effects of hardening with MMA on density as well as longitudinal, radial, tangential, and volumetric swelling properties (S, water uptake capacity (D, anti-swelling efficiency (ASE, and water repellent efficiency (WRE after soaking were investigated. Hardening treatment increased the density of all poplar woods by 1.2 to 1.6 and decreased the inner water migration rate during soaking. S and D values of hardened woods were significantly lower than those of controls, depending on the clone type. ASE and WRE values suggested that incorporating MMA effectively improved the dimensional stability of poplar wood at the early soaking stage, but was less effective in the long term.

  16. Ion-irradiation-induced hardening in Inconel 718

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


    Inconel 718 is a material under consideration for areas in the target region of the spallation neutron source (SNS), now under construction at Oak Ridge National Laboratory (ORNL) in the US. In these positions, displacement damage from protons and neutrons will affect the mechanical properties. In addition, significant amounts of helium and hydrogen will build up in the material due to transmutation reactions. Nanoindentation measurements of solution-annealed (SA) Inconel 718 specimens, implanted with Fe-, He-, and H-ions to simulate SNS target radiation conditions, have shown that hardening occurs due to ion-induced displacement damage as well as due to the build-up of helium bubbles in the irradiated layer. Precipitation-hardened (PH) Inconel 718 also exhibited hardening by helium build-up but showed softening as a function of displacement damage due to dissolution of the γ ' and γ″ precipitates.

  17. Surface hardening of steel in a solar furnace

    Rodriguez, G.P. [UCLM, ETSII, Ciudad Real (Spain); Damborenea, J.J. de [CENIM-CSIC, Madrid (Spain); Vazquez, A.J. [CENIM-CSIC, Madrid (Spain)


    The concentration of solar energy provides the possibility to get power densities high enough to produce surface modifications of materials, with low environmental impact. The present paper discusses the possibilities of surface hardening steel by means of concentrated solar energy. Surface treatments have been made by using the solar furnace of the Platafoma Solar in Almeria (Spain), which consists of a group of heliostats and a parabolic mirror. The surface transformation hardening treatment was performed on a 40CrMo4 steel. The paper presents the microstructural changes and the hardness values obtained after the solar treatment in a superficial zone. According to the power density applied on the sample, the hardened zone varied between 1 and 10 mm deep and the treatment time was less than 30 s. (orig.)

  18. Influence of coolant motion on structure of hardened steel element

    A. Kulawik


    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.


    Yusuf ŞAHİN


    Full Text Available The investigation of machining AISI 1050 carbon steels hardened to the 60 HRC hardness was carried out to determine the tool life and wear behaviour of the various cutting tools under different conditions. These experiments were conducted at using coated ceramic cutting tools and carbide cutting tools. The experimental results showed that the coated ceramic tools exhibited better performance than those of the coated carbide tools when machining the hardened steels. Moreover, wear behaviour of cutting tools were investigated in a scanning electron microscope. Electron microscopic examination also indicated that flank wear, thermal cracks on the tool nose combined with the nose deformation on the tools were responsible for the wear behaviour of the ceramic tools. For the carbide tools, however, removal of coated material from the substrate tool and combined with the crater wear were effective for the machining the hardened steel.

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

    许金泉; 付列东


    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.

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


    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.

  2. Sulfate and acid resistant concrete and mortar

    Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.


    The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications, which hardenable mixtures demonstrate significant levels of acid and sulfate resistance while maintaining acceptable compressive strength properties. The acid and sulfate hardenable mixtures of the invention containing fly ash comprise cementitious materials and a fine aggregate. The cementitous materials may comprise fly ash as well as cement. The fine aggregate may comprise fly ash as well as sand. The total amount of fly ash in the hardenable mixture ranges from about 60% to about 120% of the total amount of cement, by weight, whether the fly ash is included as a cementious material, fine aggregate, or an additive, or any combination of the foregoing. In specific examples, mortar containing 50% fly ash and 50% cement in cementitious materials demonstrated superior properties of corrosion resistance.

  3. Securing Revocable Iris and Retinal Templates using Combined User and Soft Biometric based Password Hardened Multimodal Fuzzy Vault

    V. S. Meenakshi


    Full Text Available Biometric systems are subjected to a variety of attacks. Stored biometric template attack is very severe compared to all other attacks. Providing security to biometric templates is an important issue in building a reliable personal identification system. Multi biometric systems are more resistive towards spoof attacks compared to unibiometric counterpart. Soft biometric are ancillary information about a person. This work provides security and revocability to iris and retinal templates using combined user and soft biometric based password hardened multimodal biometric fuzzy vault. Password hardening provides security and revocability to biometric templates. Eye biometrics namely iris and retina have certain merits compared to fingerprint. Iris and retina capturing cameras can be mounted on a single device to improve user convenience. Security of the vault is measured in terms of min-entropy.


    E. P. Baradyntseva


    Full Text Available The research conducted in laboratory of metallurgical science by which the factors exerting impact on hardenability of steel microalloyed by boron were analysed. The research was made because the implementation of this process in mass production is connected with the certain difficulties. The conducted researches have allowed to draw a conclusion that changing content of various chemical elements, such as nitrogen, boron, the titan and aluminum in steel containing boron, produced by JSC «BSW – Management Company of Holding «BMC» at the stage of preparation of chart flowsheet make it possible to predict terms of hardenability of the final product.

  5. Aspect-oriented security hardening of UML design models

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


    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

  6. Diffusive Origin of the Cosmic-Ray Spectral Hardening

    Tomassetti, N


    Recent data from ATIC, CREAM and PAMELA revealed that the energy spectra of cosmic ray (CR) nuclei above 100 GeV/nucleon experience a remarkable hardening with increasing energy. This effect cannot be recovered by the conventional descriptions of CR acceleration and diffusive propagation processes. Using analytical calculations, I show that the hardening effect can be consequence of a spatial change of the CR diffusion properties in different regions of the Galaxy. I discuss the implications of this scenario for the main CR observables and its connections with the open issues of the CR physics.


    P. V. Voronov


    Full Text Available Problem statement. Kinetic processes are of huge importance when producing building units and operating them as well. However, both technological and operation parameters are determined by the structure of a material under study.Results and conclusions. Kinetics with asymptotic approximation at hardening of building materials is analyzed. The validity of use of new kinetic equation is proved, characterizing harden composite systems and taking into consideration structural and topological peculiarities of new solid-like phase formation directly effecting the evolution of the processes. Results of research of change of strength at solidification a cement-sandy solution with various additives are submitted.

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

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


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

  9. Effect on Hydration and Hardening of Tricalcium Phosphate Bone Cement


    The bioactive α-Ca3 (PO4)2 bone cement was studied by XRD , SEM and isothermal calorimetric measurements. The results showed that a mixed pattern of TCP and hydroxylapatite were obtained after hydration and hardening. The mechanism of hydration and hardening of the α-Ca3 ( PO4 )2 was dissolution-precipitation,(NH4) H2 PO4 was the best set accelerator to the α-Ca3 ( PO4 )2 cement, and the HAP powers and the(NH4) H2 PO4 concentration had a great effect on the hydration rate of α-Ca3 ( PO4 )2.

  10. Temperature Development during Hardening of Large Concrete Cubes

    Sørensen, Eigil V.; Burcharth, Hans Falk

    The purpose ofthe project is to verify ifthermal cracking will occur in large unreinforced concrete cubes due to large temperature differences during hardening o f the concrete. The first part o f the project is to numerically simulate the temperature development during hardening, evaluate the risk...... of thermally induced crackingunder varying execution conditions, and verify the temperature calculations by caJTying out measurements in situ. The cubes are cast and cured under marine environmental conditions in the north western part of Spain and are to serve as coastal proteetion in a harbour under...

  11. Temperature Development during Hardening of Large Concrete Cubes

    Sørensen, Eigil V.; Burcharth, Hans Falk

    The purpose ofthe project is to verify ifthermal cracking will occur in large unreinforced concrete cubes due to large temperature differences during hardening o f the concrete. The first part o f the project is to numerically simulate the temperature development during hardening, evaluate the risk...... of thermally induced cracking under varying execution conditions, and verify the temperature calculations by carrying out measurements in situ. The cubes are cast and cured under marine environmental conditions in the north western part of Spain and are to serve as coastal proteetion in a harbour under...

  12. Impact of Scaled Technology on Radiation Testing and Hardening

    LaBel, Kenneth A.; Cohn, Lewis M.


    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

    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: [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)


    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. A rapid cold-hardening process in insects.

    Lee, R E; Chen, C P; Denlinger, D L


    Traditionally studies of cold tolerance in insects have focused on seasonal adaptations related to overwintering that are observed after weeks or months of exposure to low temperature. In contrast, an extremely rapid cold-hardening response was observed in nonoverwintering stages that confers protection against injury due to cold shock at temperatures above the supercooling point. This response was observed in nondiapausing larvae and pharate adults of the flesh fly, Sarcophaga crassipalpis, nondiapausing adults of the elm leaf beetle, Xanthogaleruca luteola, and the milkweed bug, Oncopeltus fasciatus. The rapid hardening response is correlated with the accumulation of glycerol.

  15. Research into Grinding Hardening of Microalloyed Non-quenched and Tempered Steel

    HAN Zheng-tong; ZHANG Ning-ju; GAO Ding; YANG Gang


    Grinding hardening is a new technology of hardening steel piece surfaces with grinding heat generated in the grinding process instead of with a high or medium frequency induction heating method, which can effectively integrate grinding and surface hardening. Experimental studies were carried out on grinding hardening of non-quenched and tempered steel. Through grinding experiments with variable depths of cut and feeding rate, the variation in the depth of the hardening layer was studied and the microstructure of the hardening zone of the test pieces was subsequently analyzed. In the end, the hardening effect of non-quenched and tempered steel was compared with that of 40Cr steel, which revealed the superiority of non-quenched and tempered steel in grinding hardening technology.

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

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


    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,

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

    WANG Xianhui; QI Xianlei; KANG Le


    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.

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

    M. Stachowicz


    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.

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

    ZOU Qing-hua


    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.

  20. Plasma methods of obtainment of multifunctional composite materials, dispersion-hardened by nanoparticles

    Sizonenko, O. N.; Grigoryev, E. G.; Zaichenko, A. D.; Pristash, N. S.; Torpakov, A. S.; Lipyan, Ye V.; Tregub, V. A.; Zholnin, A. G.; Yudin, A. V.; Kovalenko, A. A.


    The new approach in developed plasma methods consists in that dispersionhardening additives (TiC, TiB2 in particular) are not mechanically added to powder mixture as additional component, as in conventional methods, but are instead synthesized during high voltage electric discharges (HVED) in disperse system “hydrocarbon liquid - powder” preservation of ultrafine structure is ensured due to use of spark plasma sintering (SPS) as a consolidation method. HVED in disperse system “hydrocarbon liquid - powder” due to impact of plasma discharge channel, electromagnetic fields, shock waves mechanical impact, hydro flows and volume microcavitation leads to synthesis of nanocarbon, metal powders dispersion and synthesis of micro- (from 10-6 to 10-7 m) and nanosized (from 10-7 to 10-9 m) composite powders of hardening phases. SPS is the passage of pulsed current (superposition of direct and alternating current) through powder with the simultaneous mechanical compressing. The formation of plasma is initiated in gaseous phase that fills gaps between particles. SPS allows targeted control of grain growth rate and thus allows obtainment of multifunctional composite materials dispersion hardened by nanoparticles. Processes of HVED synthesis of micro- and nanosized powders of new compositions from elemental metal powders and their mixtures with the subsequent application of high-speed SPS of obtained powders create conditions for increase of strength (by 10 - 20%), hardness and wear-resistance (by 30 - 60%) of obtained materials.


    Ahmet Çetin CAN


    Full Text Available Machine parts are surface hardened to increase fatigue strength and wear resistance. Carburization is the most common surface hardening process in practice. In order to have optimum properties, a machine part must have certain hardness depth. To obtain required hardness depth, the parts must be kept in a carburizing medium at certain temperature for certain time. As the time and temperature is increased hardness depth increases. In practice, carburization temperature is about 930 °C. Machine parts are kept at this temperature for required time depending on required hardness depth. The increase of temperature reduces treatment time, considerably. But, heat treaters do not tend to use high temperatures due to the concern of distortion of parts, and deterioration of mechanical properties. In this study, the increase of temperature for reducing carburization time in salt bath, and consequently change of mechanical properties have been investigated using DIN C20 case carburization steel. As a result of experiments, it was found that mechanical properties were not effected negatively.

  2. Analysis of Laser Surface Hardened Layers of Automobile Engine Cylinder Liner

    LIU Xiu-bo; YU Gang; GUO Jian; SHANG Quan-yi; ZHANG Zhen-guo; GU Yi-jie


    Gray cast iron that is used for automobile engine cylinder liners was laser surface hardened using Nd∶YAG quasi-continuous and CO2 continuous wave laser, respectively. The macromorphology and microstructure of the laser surface hardened layers were investigated using an optical microscope. Geometric dimensions including depth and width and microhardness distribution of the hardened layers were also examined in order to evaluate the quality of the hardened layers.

  3. Strain hardening of polymer glasses: Entanglements, energetics, and plasticity

    Hoy, Robert S.; Robbins, Mark O.


    Simulations are used to examine the microscopic origins of strain hardening in polymer glasses. While stress-strain curves for a wide range of temperature can be fit to the functional form predicted by entropic network models, many other results are fundamentally inconsistent with the physical picture underlying these models. Stresses are too large to be entropic and have the wrong trend with temperature. The most dramatic hardening at large strains reflects increases in energy as chains are pulled taut between entanglements rather than a change in entropy. A weak entropic stress is only observed in shape recovery of deformed samples when heated above the glass transition. While short chains do not form an entangled network, they exhibit partial shape recovery, orientation, and strain hardening. Stresses for all chain lengths collapse when plotted against a microscopic measure of chain stretching rather than the macroscopic stretch. The thermal contribution to the stress is directly proportional to the rate of plasticity as measured by breaking and reforming of interchain bonds. These observations suggest that the correct microscopic theory of strain hardening should be based on glassy state physics rather than rubber elasticity.

  4. Hardening digital systems with distributed functionality: robust networks

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


    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

  5. Hardening by twin boundary during nanoindentation in nanocrystals.

    Qu, Shaoxing; Zhou, Haofei


    The atomistic deformation processes of nanocrystals embedded with nanoscale twin boundaries during nanoindentation are studied by molecular dynamics simulations. Load-displacement curves are obtained and the hardening mechanisms associated with the nanoscale twin boundaries are revealed. Johnson's theoretical indentation model is adopted to estimate the elastic stage of the nanoindentation. In addition, twin boundary-mediated dislocation nucleation is observed and analyzed.

  6. Preparation of Dispersion-Hardened Copper by Internal Oxidation

    Brøndsted, Povl; Sørensen, Ole Toft


    Internal oxidation experiments in CO2/CO atmospheres on Cu-Al alloys for preparation of dispersion-hardened Cu are described. The oxygen pressures of the atmospheres used in the experiments were controlled with a solid electrolyte oxygen cell based on ZrO2 (CaO). The particle size distributions...

  7. Coefficient of work-hardening in stage-IV

    Nabarro, FRN


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

  8. Decorative application of strain-hardening cementitious composites

    Ibrovic, V.; Lukovic, M.; Schlangen, E.


    Strain hardening cementitious composites (SHCC) have been used in variety of structural applications. Apart from this, they are also suitable for non-structural applications. In this work, the application of SHCC for producing cover plates for light switches and power sockets is presented. For desig

  9. Case Depth Measurement of Induction Hardening Using Image Processing

    Kitti Pongsathaporn; Pramuk Jenkittiyon; Siriporn Daopiset; Somnuk Watanasriyakul


    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.

  10. Decorative application of strain-hardening cementitious composites

    Ibrovic, V.; Lukovic, M.; Schlangen, E.


    Strain hardening cementitious composites (SHCC) have been used in variety of structural applications. Apart from this, they are also suitable for non-structural applications. In this work, the application of SHCC for producing cover plates for light switches and power sockets is presented. For

  11. Theoretical Studies of Laws Nanostructuring and Heterogeneous Hardening of Steel Samples by Wave Intensive Plastic Deformation

    A.V. Kirichek


    Full Text Available Theoretical studies and calculations, allowing to define the required parameters of the wave deformation hardening, are performed in order to obtain heterogeneous hardened surface layer in steel samples. The conditions for the effective use of impact energy for elastic-plastic deformation of the processed material and the establishment of a deep hardened surface layer are revealed.

  12. Application of Artificial Neural Network to Predicting Hardenability of Gear Steel

    GAO Xiu-hua; QI Ke-min; DENG Tian-yong; QIU Chun-lin; ZHOU Ping; DU Xian-bin


    The prediction of the hardenability and chemical composition of gear steel was studied using artificial neural networks. A software was used to quantitatively forecast the hardenability by its chemical composition or the chemical composition by its hardenability. The prediction result is more precise than that obtained from the traditional method based on the simple mathematical regression model.

  13. The prediction of differential hardening behaviour of steels by multi-scale crystal plasticity modelling

    Eyckens, P.; Mulder, J.; Gawad, J.; Vegter, H.; Roose, D.; Boogaard, van den A.H.; Van Bael, A.; Van Houtte, P.


    An essential aspect of materials modelling in the field of metal plasticity is hardening. The classical assumption of isotropic hardening in metal plasticity models is often too simplified to describe actual material behaviour. This paper focuses on the non-isotropic hardening termed differential ha

  14. A Novel Design Flow for a Security-Driven Synthesis of Side-Channel Hardened Cryptographic Modules

    Sorin A. Huss


    Full Text Available Over the last few decades, computer-aided engineering (CAE tools have been developed and improved in order to ensure a short time-to-market in the chip design business. Up to now, these design tools do not yet support an integrated design strategy for the development of side-channel-resistant hardware implementations. In order to close this gap, a novel framework named AMASIVE (Adaptable Modular Autonomous SIde-Channel Vulnerability Evaluator was developed. It supports the designer in implementing devices hardened against power attacks by exploiting novel security-driven synthesis methods. The article at hand can be seen as the second of the two contributions that address the AMASIVE framework. While the first one describes how the framework automatically detects vulnerabilities against power attacks, the second one explains how a design can be hardened in an automatic way by means of appropriate countermeasures, which are tailored to the identified weaknesses. In addition to the theoretical introduction of the fundamental concepts, we demonstrate an application to the hardening of a complete hardware implementation of the block cipher PRESENT.

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

    Markus Bambach


    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.

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


    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.

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

    Stachowicz, M.; K. Granat; Nowak, D.


    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...

  18. Design Features of Hardening Turners with Outstripping Plastic Deformation

    V. M. Yaroslavtsev


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

  19. Strain Hardening and Size Effect in Five-fold Twinned Ag Nanowires.

    Narayanan, Sankar; Cheng, Guangming; Zeng, Zhi; Zhu, Yong; Zhu, Ting


    Metallic nanowires usually exhibit ultrahigh strength but low tensile ductility owing to their limited strain hardening capability. Here we study the unique strain hardening behavior of the five-fold twinned Ag nanowires by nanomechanical testing and atomistic modeling. In situ tensile tests within a scanning electron microscope revealed strong strain hardening behavior of the five-fold twinned Ag nanowires. Molecular dynamics simulations showed that such strain hardening was critically controlled by twin boundaries and pre-existing defects. Strain hardening was size dependent; thinner nanowires achieved more hardening and higher ductility. The size-dependent strain hardening was found to be caused by the obstruction of surface-nucleated dislocations by twin boundaries. Our work provides mechanistic insights into enhancing the tensile ductility of metallic nanostructures by engineering the internal interfaces and defects.

  20. Radiation Hardening of LED Luminaires for Accelerator Tunnels

    Devine, James D


    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...

  1. Segmentation-free empirical beam hardening correction for CT

    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: [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)


    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

  2. Age-hardening in a commercial Mg-based alloy

    Macchi, C.E. [IFIMAT, UNCentro and CONICET, Pinto 399, B7000GHG Tandil (Argentina); Somoza, A. [IFIMAT, UNCentro and CICPBA, Pinto 399, B7000GHG Tandil (Argentina); Nie, J.F. [School of Physics and Materials Engineering, PO Box 69M, Monash University, Victoria 3800 (Australia)


    Age-hardening phenomena induced by thermal and thermo-mechanical treatments in the commercial Mg-based alloy WE54 were studied by positron annihilation lifetime spectroscopy and Vickers microhardness. To this aim, samples were plastically deformed and subsequently aged at 250 C for times ranging from 0 to 1000 hours. The results obtained are discussed in terms of the role of vacancies in the solute transport and therefore they contribute to the discussion on the vacancy-solute clusters (and/or intermediate precipitates) interactions during the precipitation sequence of the WE54. Besides, we show that cold work previous aging not only accelerates but increases the hardening response of the alloy. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Hardening electronic devices against very high total dose radiation environments

    Buchanan, B.; Shedd, W.; Roosild, S.; Dolan, R.


    The possibilities and limitations of hardening silicon semiconductor devices to the high neutron and gamma radiation levels and greater than 10 to the eighth power rads required for the NERVA nuclear engine development are discussed. A comparison is made of the high dose neutron and gamma hardening potential of bipolar, metal insulator semiconductors and junction field effect transistors. Experimental data is presented on device degradation for the high neutron and gamma doses. Previous data and comparisons indicate that the JFET is much more immune to the combined neutron displacement and gamma ionizing effects than other transistor types. Experimental evidence is also presented which indicates that p channel MOS devices may be able to meet the requirements.

  4. Poromechanical behaviour of hardened cement paste under isotropic loading

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


    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.

  5. Laser surface hardening of AISI H13 tool steel

    Jae-Ho LEE; Jeong-Hwan JANG; Byeong-Don JOO; Young-Myung SON; Young-Hoon MOON


    An attempt was made to improve the surface hardness and wear properties of AISI H13 tool steel through solid solution hardening and refinement of microstructures using a 200 W fiber laser as a heat generating source. The hardness of laser melted zone was investigated. In order to identify the effect of heat input on the laser melting zone, scanning conditions were controlled. The results show that, the hardness of as-received AISI H13 tool steel is approximately Hv 240, and the hardness after laser surface heat treatment is around Hv 480-510. The hardening depth and width are increased with the increase in the heat input applied. Application of experimental results will be considered in tooling industry.


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


    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.

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

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


    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.

  8. Reduction of metal artifacts: beam hardening and photon starvation effects

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


    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.

  9. Elastic constant versus temperature behavior of three hardened maraging steels

    Ledbetter, H. M.; Austin, M. W.


    Elastic constants of three maraging steels were determined by measuring ultrasonic velocities. Annealed steels show slightly lower bulk moduli and considerably lower shear moduli than hardened steels. All the elastic constants (Young's modulus, shear modulus, bulk modulus and Poisson's ratio) show regular temperature behavior between 76 and 400 K. Young's modulus and the shear modulus increase with increasing yield strength, but the bulk modulus and Poisson's ratio are relatively unchanged. Elastic anisotropy is quite small.

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

    Moszner, F. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Sologubenko, A.S. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Schinhammer, M. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Lerchbacher, C. [Christian Doppler Laboratory for Early Stages of Precipitation, University of Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Haenzi, A.C. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Leitner, H. [Christian Doppler Laboratory for Early Stages of Precipitation, University of Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Uggowitzer, P.J. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Loeffler, J.F., E-mail: [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland)


    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 {l_brace}1 0 0{r_brace} 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.

  11. Multi-material linearization beam hardening correction for computed tomography.

    Lifton, J J


    Since beam hardening causes cupping and streaking artifacts in computed tomographic images, the presence of such artifacts can impair both qualitative and quantitative analysis of the reconstructed data. When the scanned object is composed of a single material, it is possible to correct beam hardening artifacts using the linearization method. However, for multi-material objects, an iterative segmentation-based correction algorithm is needed, which is not only computationally expensive, but may also fail if the initial segmentation result is poor. In this study, a new multi-material linearization beam hardening correction method was proposed and evaluated. The new method is fast and implemented in the same manner as a mono-material linearization. The correction takes approximately 0.02 seconds per projection. Although facing a potential disadvantage of requiring attenuation measurements of one of the object's constituent materials, applying the new method has demonstrated its capability for a multi-material workpiece with substantial reduction in both cupping and streaking artifacts. For example, the study showed that the absolute cupping artefacts in steel, titanium and aluminum spheres were reduced from 22%, 20% and 20% to 5%, 1% and 0%, respectively.

  12. Residual stress analysis of drive shafts after induction hardening

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


    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)

  13. Use of rapidly hardening hydroxyapatite cement for facial contouring surgery.

    Lee, Dong Won; Kim, Ji Ye; Lew, Dae Hyun


    Hydroxyapatite cement is an ideal alloplastic material to replace the autogenous bone grafts in craniofacial surgery. Hydroxyapatite cement is advantageous because it can be easily molded by hand unlike other alloplastic materials such as silicone and high-density polyethylene. For aesthetic applications of hydroxyapatite cement, we evaluated the efficacy and safety of the rapidly hardening hydroxyapatite cement used in facial contour augmentation, especially for the forehead and the malar area. A total of 18 cases of facial skeleton augmentation or contouring surgery using rapidly hardening hydroxyapatite cement (Mimix; Biomet, Warsaw, IN) were examined, and the long-term cosmetic results and any complications were also analyzed. The aims of facial contouring surgeries were to correct the following conditions: hemifacial microsomia, craniosynostosis, posttraumatic facial deformity, deformity after tumor resection, dentofacial deformity, and Romberg disease. The application sites of hydroxyapatite cement were the forehead, malar area, chin, and paranasal area. A mean of 16 g (range, 5-50 g) of the hydroxyapatite cement was used. Postoperative infection, seroma, and migration of the implant were not observed during the follow-up period of 23 months. Rapidly hardening hydroxyapatite cement, Mimix, is easy to manipulate, promptly sclerotized, and can be replaced by living bone tissue, with a low complication rate. Therefore, it can be an optimal treatment that can be used instead of other conventional types of alloplastic materials used in facial contouring surgery.

  14. Study on the hardening mechanism of cement asphalt binder


    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.

  15. Free Vibration and Hardening Behavior of Truss Core Sandwich Beam

    J. E. Chen


    Full Text Available The dynamic characteristics of simply supported pyramidal truss core sandwich beam are investigated. The nonlinear governing equation of motion for the beam is obtained by using a Zig-Zag theory. The averaged equations of the beam with primary, subharmonic, and superharmonic resonances are derived by using the method of multiple scales and then the corresponding frequency response equations are obtained. The influences of strut radius and core height on the linear natural frequencies and hardening behaviors of the beam are studied. It is illustrated that the first-order natural frequency decreases continuously and the second-order and third-order natural frequencies initially increase and then decrease with the increase of strut radius, and the first three natural frequencies all increase with the rise of the core height. Furthermore, the results indicate that the hardening behaviors of the beam become weaker with the increase of the rise of strut radius and core height. The mechanisms of variations in hardening behavior of the sandwich beam with the three types of resonances are detailed and discussed.

  16. Press Hardening Steel (PHS): a new coating and process technology

    Faderl, J. [voestalpine Stahl Linz GmbH (Austria); Vehof, R. [Polynorm N.V., Bundschoten (Netherlands)


    Press hardening technology has been known for many years. Increased requirements with respect to safety and light weight construction of the steel body for cars and trucks force the automotive industry to use high strength steels more and more. Strength levels up to 1000 MPa can be provided with AHSS grades. Above 1000 MPa, these steel grades are coming to their limit with respect to strength vs. formability balance. PHS is a very attractive alternative concept. Hardenable 22MnB5 has been supplied - uncoated - for a long time. To avoid decarburization during heat treatment and to improve corrosion behaviour hot dip aluminized 22MnB5 was introduced to the market. Both materials, uncoated and hot dip aluminized, do not provide cathodic corrosion protection without postcoating (sheradizing..). In the last two years an improved press hardening technology and a zinc based coating providing cathodic protection was developed by voestalpine. Some results about strength homogeneity, formability, corrosion behaviour of this voestalpine-PHS technology will be presented in the paper. (orig.)

  17. Recent developments in turning hardened steels - A review

    Sivaraman, V.; Prakash, S.


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

  18. Tensile properties and conductivities of a precipitation hardened and cold-rolled Cu-0.3Cr-0.1Zr alloy at cryogenic temperature

    Umezawa, O.


    Cu-0.3Cr-0.1Zr alloy (in mass%) is one of typical precipitation hardened copper- based alloys, and exhibited an excellent combination of high strength and high conductivities at the temperature range of 4 K to 300 K. The tensile properties, electrical resistivity, thermal conductivity and magnetization of precipitation hardened and cold-rolled Cu-0.3Cr-0.1Zr alloy were measures in comparison with oxygen free copper at cryogenic temperatures. The Cu- 0.3Cr-0.1Zr showed higher yield ratio (yield strength / tensile strength) and lower the ratio of yield strength to electrical resistivity at cryogenic temperature than oxygen free copper. It exhibited high electrical and thermal conductivities, excellent non-magnetic stability and very low magnetic permeability at 4.2 K.

  19. Suppressing the hot carrier injection degradation rate in total ionizing dose effect hardened nMOSFETs

    Chen Jian-Jun; Chen Shu-Ming; Liang Bin; He Yi-Bai; Chi Ya-Qing; Deng Ke-Feng


    Annular gate nMOSFETs are frequently used in spaceborne integrated circuits due to their intrinsic good capability of resisting total ionizing dose (TID) effect.However,their capability of resisting the hot carrier effect (HCE) has also been proven to be very weak.In this paper,the reason why the annular gate nMOSFETs have good TID but bad HCE resistance is discussed in detail,and an improved design to locate the source contacts only along one side of the annular gate is used to weaken the HCE degradation.The good TID and HCE hardened capability of the design are verified by the experiments for I/O and core nMOSFETs in a 0.18 μm bulk CMOS technology.In addition,the shortcoming of this design is also discussed and the TID and the HCE characteristics of the replacers (the annular source nMOSFETs) are also studied to provide a possible alternative for the designers.

  20. Endurecimiento combinado en engranajes cilíndricos de dientes rectos. // Combined hardening in cylindrical gears of right teeth.

    O. González Quintero


    Full Text Available Las ruedas dentadas son componentes de los mecanismos y máquinas muy comunes, siendo las cilíndricas de dientes rectosuna de los tipos más importantes, es por ello que a su proceso de fabricación se le presta gran atención, existiendo múltiplestecnologías que garantizan su trabajo sin fallas y duradero, pero la mayoría con un alto costo de producción. Resultado deeste interés en la actualidad se vienen aplicando cada vez más algunas formas alternativas de mejorar la resistencia de losmetales, entre ellas el tratamientos mecánico-térmico aplicado en este trabajo: el endurecimiento combinado, combinacióndel endurecimiento por deformación plástica y el endurecimiento por envejecimiento artificial.El objetivo de este estudio es determinar la influencia de las fuerzas de engranaje y del tiempo de tratamiento mecánicotérmicoen las propiedades mecánicas: microdureza y profundidad de acritud de las capas superficiales de ruedas dentadascilíndricas de dientes rectos, obteniendo un modelo estadístico matemático que relaciona las variables antes citadas con ladureza de las capas superficiales en engranajes cilíndricos de dientes rectos de acero de mediano contenido de carbono cuyacomposición química se corresponda con las establecidas en el presente trabajo.Palabras claves: Engranajes, endurecimiento combinado, microdureza, deformación plástica, envejecimiento.______________________________________________________________________________Abstract.Gears are an extremely common mechanism component used in many machines, being the spur gear one of the mostfundamental types, because of is paid great attention to their process of production, multiple technologies that guaranteetheir work without failures and durable exist, but most with a high production cost. Result of this interest at the present timeone comes applying more and more, some alternative forms of improving the resistance of the metals, among them the

  1. Extrinsic Hardening of Superhard Tungsten Tetraboride Alloys with Group 4 Transition Metals.

    Akopov, Georgiy; Yeung, Michael T; Turner, Christopher L; Mohammadi, Reza; Kaner, Richard B


    Alloys of tungsten tetraboride (WB4) with the group 4 transition metals, titanium (Ti), zirconium (Zr), and hafnium (Hf), of different concentrations (0-50 at. % on a metals basis) were synthesized by arc-melting in order to study their mechanical properties. The phase composition and purity of the as-synthesized samples were confirmed using powder X-ray diffraction (PXRD) and energy dispersive X-ray spectroscopy (EDS). The solubility limit as determined by PXRD is 20 at. % for Ti, 10 at. % for Zr, and 8 at. % for Hf. Vickers indentation measurements of WB4 alloys with 8 at. % Ti, 8 at. % Zr, and 6 at. % Hf gave hardness values, Hv, of 50.9 ± 2.2, 55.9 ± 2.7 and 51.6 ± 2.8 GPa, respectively, compared to 43.3 GPa for pure WB4 under an applied load of 0.49 N. Each of the aforementioned compositions are considered superhard (Hv > 40 GPa), likely due to extrinsic hardening that plays a key role in these superhard metal borides. Furthermore, these materials exhibit a significantly reduced indentation size effect, which can be seen in the plateauing hardness values for the W1-xZrxB4 alloy. In addition, W0.92Zr0.08B4, a product of spinoidal decomposition, possesses nanostructured grains and enhanced grain hardening. The hardness of W0.92Zr0.08B4 is 34.7 ± 0.65 GPa under an applied load of 4.9 N, the highest value obtained for any superhard metal at this relatively high loading. In addition, the WB4 alloys with Ti, Zr, and Hf showed a substantially increased oxidation resistance up to ∼460 °C, ∼510 °C, and ∼490 °C, respectively, compared to ∼400 °C for pure WB4.

  2. Improved impact toughness of 13Cr martensitic stainless steel hardened by laser

    Tsay, L. W.; Chang, Y. M.; Torng, S.; Wu, H. C.


    The impact toughness of AISI 403 martensitic stainless steel plate and laser-hardened specimens tempered at various temperatures were examined. Phosphorus was the primary residual impurity responsible for tempered embrittlement of this alloy. The experimental result also indicated that AISI 403 stainless steel was very sensitive to reverse-temper embrittlement. The improved impact toughness of the laser-hardened specimen was attributed to the refined microstructure in the laser-hardened zone.

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

    Allen Phillip A.; Wilson, Christopher D.


    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.

  4. The hardening compositions from the burnt rocks for using in the mining conditions

    Galpern, E.I. [Inst. of Industrial Construction and Building, Donetsk, (Ukraine); Pashchenko, L.V.; Saranchuk, V.I. [Inst. of Physical, Organic and Coal Chemistry NAS, Donetsk (Ukraine)


    The complex investigation of burnt coal rocks as raw material for hardening alkaline cements reception have been carried out. The hardening composition on the base of pit heap burnt rocks for the grouting of worked-out space in mining conditions have been obtained. It has been shown that burnt rocks activation by blast granulated slag and water glass allowed to obtain the cements of needed strength. The influence of main technological factors on obtained hardening composition properties have been studied. (orig.)

  5. Electrolytic surface hardening of steel,cast iron and aluminium-bronze

    Suhas Keshav Paknikar


    Electrolytic hardening process was developed in USSR in the 1950s. The process was developed but was not commercially exploited. There is no evidence of work done on this process in India. The author has done this original work applied to different materials like steel,cast iron and aluminum-bronze. This paper gives details of microstructural transformations along with hardness value achieved. There is vital scope for this process to become viable for surface hardening and selective hardening of small components.

  6. Multi-MGy Radiation Hardened Camera for Nuclear Facilities

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


    There is an increasing interest in developing cameras for surveillance systems to monitor nuclear facilities or nuclear waste storages. Particularly, for today's and the next generation of nuclear facilities increasing safety requirements consecutive to Fukushima Daiichi's disaster have to be considered. For some applications, radiation tolerance needs to overcome doses in the MGy(SiO{sub 2}) range whereas the most tolerant commercial or prototypes products based on solid state image sensors withstand doses up to few kGy. The objective of this work is to present the radiation hardening strategy developed by our research groups to enhance the tolerance to ionizing radiations of the various subparts of these imaging systems by working simultaneously at the component and system design levels. Developing radiation-hardened camera implies to combine several radiation-hardening strategies. In our case, we decided not to use the simplest one, the shielding approach. This approach is efficient but limits the camera miniaturization and is not compatible with its future integration in remote-handling or robotic systems. Then, the hardening-by-component strategy appears mandatory to avoid the failure of one of the camera subparts at doses lower than the MGy. Concerning the image sensor itself, the used technology is a CMOS Image Sensor (CIS) designed by ISAE team with custom pixel designs used to mitigate the total ionizing dose (TID) effects that occur well below the MGy range in classical image sensors (e.g. Charge Coupled Devices (CCD), Charge Injection Devices (CID) and classical Active Pixel Sensors (APS)), such as the complete loss of functionality, the dark current increase and the gain drop. We'll present at the conference a comparative study between these radiation-hardened pixel radiation responses with respect to conventional ones, demonstrating the efficiency of the choices made. The targeted strategy to develop the complete radiation hard camera

  7. Organoapatites: materials for artificial bone. II. Hardening reactions and properties.

    Stupp, S I; Mejicano, G C; Hanson, J A


    This article reports on chemical reactions and the properties they generated in artificial bone materials termed "organoapatites." These materials are synthesized using methodology we reported in the previous article of this series. Two different processes were studied here for the transition from organoapatite particles to implants suitable for the restoration of the skeletal system. One process involved the hardening of powder compacts by beams of blue light derived from a lamp or a laser and the other involved pressure-induced interdiffusion of polymers. In both cases, the hardening reaction involved the formation of a polyion complex between two polyelectrolytes. In the photo-induced reaction an anionic electrolyte polymerizes to form the coulombic network and in the pressure-induced one, pressure forms the complex by interdiffusion of two polyions. Model reactions were studied using various polycations. Based on these results the organoapatite selected for the study was that containing dispersed poly(L-lysine) and sodium acrylate as the anionic monomer. The organomineral particles can be pressed at room temperature into objects of great physical integrity and hydrolytic stability relative to anorganic controls. The remarkable fact about these objects is that intimate molecular dispersion of only 2-3% by weight organic material provides integrity to the mineral network in an aqueous medium and also doubles its tensile strength. This integrity is essentially nonexistent in "anorganic" samples prepared by the same methodology used in organoapatite synthesis. The improvement in properties was most effectively produced by molecular bridges formed by photopolymerization. The photopolymerization leads to the "hardening" of pellets prepared by pressing of organoapatite powders. The reaction was found to be more facile in the microstructure of the organomineral, and it is potentially useful in the surgical application of organoapatites as artificial bone.

  8. Precipitation hardening in Fe--Ni base austenitic alloys

    Chang, K.M.


    The precipitation of metastable Ni/sub 3/X phases in the austenitic Fe--Ni-base alloys has been investigated by using various combinations of hardening elements, including Ti, Ta, Al, and Nb. The theoretical background on the formation of transition precipitates has been summarized based on: atomic size, compressibility, and electron/atom ratio. A model is proposed from an analysis of static concentration waves ordering the fcc lattice. Ordered structure of metastable precipitates will change from the triangularly ordered ..gamma..', to the rectangularly ordered ..gamma..'', as the atomic ratio (Ti + Al)/(Ta + Nb) decreases. The concurrent precipitation of ..gamma..' and ..gamma..'' occurs at 750/sup 0/C when the ratio is between 1.5 and 1.9. Aging behavior was studied over the temperature range of 500/sup 0/C to 900/sup 0/C. Typical hardness curves show a substantial hardening effect due to precipitation. A combination of strength and fracture toughness can be developed by employing double aging techniques. The growth of these coherent intermediate precipitates follows the power law with the aging time t : t/sup 1/3/ for the spherical ..gamma..' particles; and t/sup 1/2/ for the disc-shaped ..gamma..''. The equilibrium ..beta.. phase is observed to be able to nucleate on the surface of imbedded carbides. The addition of 5 wt % Cr to the age-hardened alloys provides a non-magnetic austenite which is stable against the formation of mechanically induced martensite.Cr addition retards aging kinetics of the precipitation reactions, and suppresses intergranular embrittlement caused by the high temperature solution anneal. The aging kinetics are also found to be influenced by solution annealing treatments.

  9. Effect of hardening method and structure of linking bridges on strength of water glass moulding sands

    Stachowicz, M.; K. Granat


    The paper presents examination results of the effect of four hardening methods on structure of linking bridges in sandmixes containing hydrated sodium silicate. Test pieces prepared of the moulding sands containing 2.5 % of a binder with molar module between 2.4 and 2.6 were hardened with carbon dioxide, dried traditionally in an oven and hardened with microwaves at 2.54 GHz or using a combination of the CO2 process and microwave heating. It was revealed that the hardening method influences s...

  10. Optimizing the Thermal Regime During the Acceleration of Concrete’s Hardening

    Vladimir Corobceanu


    Full Text Available Researches conducted at the Faculty of Construction in Jassy showed several factors that may help finding technical solutions which will make possible to economically apply acceleration procedures of concrete hardening by thermal treatment with solar energy. It has to be mentioned the fact that the thermal treatment do not exclude, but it is based on the acceleration methods of concrete hardening through composition with or without the usage of different additives -- plasticizer type (to reduce the quantity of water from the concrete and accelerators for cement binding or hardening. These methods also take into account the climate where the process of hardening takes place.

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

    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...

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

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


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

  13. Hardening mechanisms in a dynamic strain aging alloy, Hastelloy X, during isothermal and thermomechanical cyclic deformation

    Miner, R. V.; Castelli, M. G.


    The relative contributions of the hardening mechanisms in Hastelloy X during cyclic deformation were investigated by conducting isothermal cyclic deformation tests within a total strain range of +/-0.3 pct and at several temperatures and strain rates, and thermomechanical tests within several different temperature limits. The results of the TEM examinations and special constant structure tests showed that the precipitation on dislocations of Cr23C6 contributed to hardening, but only after sufficient time above 500 C. Solute drag alone produced very considerable cyclic hardening. Heat dislocation densities, peaking around 10 exp 11 per sq cm, were found to develop at temperatures producing the greatest cyclic hardening.

  14. A new ester hardener for moulding sands with water glass having slower activity

    K. Major-Gabryś


    Full Text Available The article takes into consideration the researches concerning inputting the new hardener to moulding sands with water glass, carried out in ester technology. Investigations are continuation of works connected to hardener based on carbonic acid’s esters, that significantly upgrades the ability of these moulding sands to mechanical reclamation. Its’ nuisance is short vitality. This is why, new investigations were taken to elaborate another hardener keeping the positive characteristics of the previous one and allowing the wider usage of technologies of loose self-hardened moulding sands with water glass.

  15. Development of a Flexible Laser Hardening & Machining Center and Proof of Concept on C-45 Steel

    Bouquet, Jan; Van Camp, Dries; Vanhove, Hans; Clijsters, Stijn; Amirahmad, Mohammadi; Lauwers, Bert

    The production of hardened precision parts is conventionally done in 3 steps. Rough machining of a workpiece in soft stage is followed by a hardening step, usually a batch process, and finalized by a hard machining finishing step. To omit the inevitable time delay and loss of accuracy because of part re-clamping, these steps should be incorporated within one flexible machining center. This paper describes the development of this machining center which allowsmachining and laser hardening in one setup, followed by a proof of concept for hardening C45 steel on this setup.

  16. Rationale simplified hardening training and recreational complexes future teachers

    Verbludov I.B.


    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.

  17. Bake hardening behavior of TRIP and DP steels

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


    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.

  18. The development of radiation hardened robot for nuclear facility

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


    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.

  19. New Stainless Steel Alloys for Low Temperature Surface Hardening?

    Christiansen, Thomas Lundin; Dahl, Kristian Vinter; Somers, Marcel A. J.


    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 selection...

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

    Chen, D. Z., E-mail: [Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, California 91125 (United States); Gu, X. W. [Department of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125 (United States); An, Q.; Goddard, W. A. [Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125 (United States); Greer, J. R. [Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, California 91125 (United States); The Kavli Nanoscience Institute, California Institute of Technology, Pasadena, California 91125 (United States)


    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.

  1. Fatigue Hardening and Nucleation of Persistent Slip Bands in Copper

    Pedersen, Ole Bøcker; Winter, A. T.


    that there is a large volume fraction of obstacles to plastic flow which are essentially non-deformable and give rise to inclusion stresses of considerable magnitude. The much lower hardening rates in cycles after saturation when persistent slip bands have formed suggest a lower volume fraction of obstacles......, as is observed by transmission electron microscopy. A simple composite model involving an inclusion stress, a bowing stress and a passing, stress accounts for the workhardening rates semi-quantitatively in terms of observed dislocation microstructures. Possible implications for polycrystals are considered....

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

    Messenger, G.C.; Coppage, F.N.


    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.

  3. Rapid desiccation hardening changes the cuticular hydrocarbon profile of Drosophila melanogaster.

    Stinziano, Joseph R; Sové, Richard J; Rundle, Howard D; Sinclair, Brent J


    The success of insects in terrestrial environments is due in large part to their ability to resist desiccation stress. Since the majority of water is lost across the cuticle, a relatively water-impermeable cuticle is a major component of insect desiccation resistance. Cuticular permeability is affected by the properties and mixing effects of component hydrocarbons, and changes in cuticular hydrocarbons can affect desiccation tolerance. A pre-exposure to a mild desiccation stress increases duration of desiccation survival in adult female Drosophila melanogaster, via a decrease in cuticular permeability. To test whether this acute response to desiccation stress is due to a change in cuticular hydrocarbons, we treated male and female D. melanogaster to a rapid desiccation hardening (RDH) treatment and used gas chromatography to examine the effects on cuticular hydrocarbon composition. RDH led to reduced proportions of unsaturated and methylated hydrocarbons compared to controls in females, but although RDH modified the cuticular hydrocarbon profile in males, there was no coordinated pattern. These data suggest that the phenomenon of RDH leading to reduced cuticular water loss occurs via an acute change in cuticular hydrocarbons that enhances desiccation tolerance in female, but not male, D. melanogaster. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Influence of niobium on the hardening phenomenon and wear in the manganese steel (12% Mn destined for the railway

    Maouche Hichem


    Full Text Available This study relates to the manufacture of austenitic manganese steel for the heart switching crossings of railways in all industrial countries where heavy loads are moved by rail. This steel is characterized by a high surface hardness service yard caused by the phenomenon of hardening. According to the microstructure formed after quenching, the transformation of austenite into martensite during working, determine the operating life. The rate of transformation of austenite into martensite can force a compromise between ductility and wear resistance of the steel in order to withstand large forces without breaking. The objective of this study is to improve the resistance to abrasion and friction to cast state and after heat treatment by the addition of niobium. This study permitted to develop a new shade of manganese steel can be integrated into the production of heart of railway switches with better lifecycle.

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

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


    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...... plastically deformed to different equivalent strains by uniaxial tension. Gaseous nitriding of the strained material was performed in ammonia gas at atmospheric pressure at 703 K (430 °C) and 693 K (420 °C) depending on the material. Microstructural characterization of the as-deformed states and the nitrided...

  6. Implicit numerical integration for a kinematic hardening soil plasticity model

    Rouainia, M.; Muir Wood, D.


    Soil models based on kinematic hardening together with elements of bounding surface plasticity, provide a means of introducing some memory of recent history and stiffness variation in the predicted response of soils. Such models provide an improvement on simple elasto-plastic models in describing soil behaviour under non-monotonic loading. Routine use of such models requires robust numerical integration schemes. Explicit integration of highly non-linear models requires extremely small steps in order to guarantee convergence. Here, a fully implicit scheme is presented for a simple kinematic hardening extension of the Cam clay soil model. The algorithm is based on the operator split methodology and the implicit Euler backward integration scheme is proposed to integrate the rate form of the constitutive relations. This algorithm maintains a quadratic rate of asymptotic convergence when used with a Newton-Raphson iterative procedure. Various strain-driven axisymmetric triaxial paths are simulated in order to demonstrate the efficiency and good performance of the proposed algorithm.

  7. Phase transformations in titanium alloys hardened by rapid heating

    Gridnev, V.N.; Ivasishin, O.M.; Oshkaderov, S.P.; Smirnov, A.M. (AN Ukrainskoj SSR, Kiev. Inst. Metallofiziki)

    Features of phase transformations in titanium alloys, which subjected to hardening by rapid heating, are studied. The model for mathematical description of ..cap alpha..+..beta.. ..-->.. ..beta..- transformation under the conditions of continuous heating with different rate, is proposed. The increase of the polymorphic transformation temperature with the heating rate, is predicted and confirmed experimentally. Under certain conditions this fact can result in a two-stage process, of ..cap alpha..+..beta.. ..-->.. ..beta..-transformation, which begins according to difussion mechanism, and completes according to the non-diffusion one. It is shown, that ..cap alpha..+..beta.. ..-->.. ..beta..-transformation under non-equilibrium conditions is followed by appearing of concentration non-uniformity in reacting phases, that essentially affects the grain and intragranular structure of hardened alloys, and their phase composition. Variants of phase composition of the alloys of different classes quenched after rapid heating in the ..beta..-field, are analyzed. Possible aspects of the effect of increased heating rates on the ageing process are considered.

  8. Folding and faulting of strain-hardening sedimentary rocks

    Johnson, A.M.


    The question of whether single- or multi-layers of sedimentary rocks will fault or fold when subjected to layer-parallel shortening is investigated by means of the theory of elastic-plastic, strain-hardening materials, which should closely describe the properties of sedimentary rocks at high levels in the Earth's crust. The most attractive feature of the theory is that folding and faulting, intimately related in nature, are different responses of the same idealized material to different conditions. When single-layers of sedimentary rock behave much as strain-hardening materials they are unlikely to fold, rather they tend to fault, because contrasts in elasticity and strength properties of sedimentary rocks are low. Amplifications of folds in such materials are negligible whether contacts between layer and media are bonded or free to slip for single layers of dolomite, limestone, sandstone, or siltstone in media of shale. Multilayers of these same rocks fault rather than fold if contacts are bonded, but they fold readily if contacts between layers are frictionless, or have low yield strengths, for example due to high pore-water pressure. Faults may accompany the folds, occurring where compression is increased in cores of folds. Where there is predominant reverse faulting in sedimentary sequences, there probably were few structural units. ?? 1980.

  9. Discrepant hardening observed in cosmic-ray elemental spectra

    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


    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 ...

  10. Dislocation Starvation and Exhaustion Hardening in Mo-alloy Nanofibers

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


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

  11. Atomistic interpretation of solid solution hardening from spectral analysis.

    Plendl, J N


    From analysis of a series of vibrational spectra of ir energy absorption and laser Raman, an attempt is made to interpret solid solution hardening from an atomistic point of view for the system CaF(2)/SrF(2). It is shown to be caused by the combined action of three atomic characteristics, i.e., their changes as a function of composition. They are deformation of the atomic coordination polyhedrons, overlap of the outer electron shells of the atom pairs, and the ratio of the ionic to covalent share of binding. A striking nonlinear behavior of the three characteristics, as a function of composition, gives maximum atomic bond strength to the 55/45 position of the system CaF(2)/SrF(2), in agreement with the measured data of the solid solution hardening. The curve for atomic bond strength, derived from the three characteristics, is almost identical to the curve for measured microhardness data. This result suggests that the atomistic interpretation, put forward in this paper, is correct.


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


    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.

  13. Applied Research of Laser Surface Hardening of Cast Iron Hot Roll%铸铁热轧辊激光表面强化应用研究



    运用激光表面强化理论和技术,对NiCrMo半冷硬铸铁热轧辊材料进行激光相变硬化和熔凝处理后,表层分别得到针状马氏体和莱氏体白口组织,硬度由原来的51 HRC提高到70 HRC左右,材料的耐磨性提高.%Applying the theory and technology of laser surface hardening, NiCrMo chilled cast iron hot roll material was processed by laser transformation hardening and surface melting. The results show that the white organizations of acicular martensite and ledeburite are obtained in the surface layer, the hardness is increased from 51 HRC to about 70 HRC, and the wear resistance and other performance of the materials are also improved.

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

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


    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.

  15. Strain hardening as an indicator of bread-making performance: A review with discussion

    Vliet, van T.


    Since strain hardening has been proposed as an important quality indicator of dough with respect to bread-making performance, a large body of experimental support for this concept has been published. Nevertheless, some questions remain with respect to the use of the concept of strain hardening. This

  16. Numerical Simulation of Stresses due to Solid State Transformations : The Simulation of Laser Hardening

    Geijselaers, H.J.M.


    The properties of many engineeringmaterialsmay be favourablymodified by application of a suitable heat treatment. Examples are precipitation hardening, tempering and annealing. One of the most important treatments is the transformation hardening of steel. Steel is an alloy of iron and carbon. At roo

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

    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....

  18. Optimization of tensile strain-hardening cementhious composites for tensile strain capacity

    Shionaga, R.; Pansuk, W.; Grunewald, S.; den Uijl, J.A.; Walraven, J.C.


    The synergistic action of a cementitious matrix and fibres can result in strain hardening in tension. The accompanied tensile strain capacity can be an important design parameter for strain-hardening cementitious composites in order to prevent the localization in a single crack and to assure that th

  19. [Optimal coefficient of overlap of light spots during laser hardening of medical instruments].

    Stepanova, G A; Pogibenko, A V; Gerasev, G P


    The optimum coefficient of light spot intercepts in the course of laser hardening medical instruments is determined for the case when there are no unirradiated sites on the surface under treatment. The increase in the light spot diameter during irradiation has been shown to be followed by more rapid expansion of the hardened area in comparison with the one of the tempered zone.

  20. Strain hardening as an indicator of bread-making performance: A review with discussion

    Vliet, van T.


    Since strain hardening has been proposed as an important quality indicator of dough with respect to bread-making performance, a large body of experimental support for this concept has been published. Nevertheless, some questions remain with respect to the use of the concept of strain hardening. This

  1. The effects of x-ray beam hardening on detective quantum efficiency and radiation dose.

    Wong, Molly Donovan; Wu, Xizeng; Liu, Hong


    The goal of this preliminary study was to investigate the effects of x-ray beam hardening on the detective quantum efficiency (DQE) and the radiation dose of an inline x-ray imaging system. The ability to decrease the risk of harmful radiation to the patient without compromising the detection capability would more effectively balance the tradeoff between image quality and radiation dose, and therefore benefit the fields of diagnostic x-ray imaging, especially mammography. The DQE and the average glandular dose were both calculated under the same experimental conditions for a range of beam hardening levels, corresponding to no added beam hardening and two thicknesses each of Rhodium (Rh) and Molybdenum (Mo) filters. The dose calculation results demonstrate a reduction of 15% to 24% for the range of beam hardening levels. The comparison of all quantities comprising the DQE exhibit very close correlation between the results obtained without added beam hardening to the results corresponding to the range of beam hardening levels. For the specific experimental conditions utilized in this preliminary study, the results are an indication that the use of beam hardening holds the potential to reduce the radiation dose without decreasing the performance of the system. Future studies will seek to apply this method in a clinical environment and perform a comprehensive image quality evaluation, in an effort to further evaluate the potential of beam hardening to balance the tradeoff between dose and image quality.

  2. Effect of hardening method and structure of linking bridges on strength of water glass moulding sands

    M. Stachowicz


    Full Text Available The paper presents examination results of the effect of four hardening methods on structure of linking bridges in sandmixes containing hydrated sodium silicate. Test pieces prepared of the moulding sands containing 2.5 % of a binder with molar module between 2.4 and 2.6 were hardened with carbon dioxide, dried traditionally in an oven and hardened with microwaves at 2.54 GHz or using a combination of the CO2 process and microwave heating. It was revealed that the hardening method influences structure of linking bridges and is correlated with mechanical properties of the hardened moulding sands. It was found that strength of the moulding sands microwave-heated for 240 s is approximate to that measured after traditional drying for 120 min at 110 °C. So, the microwave hardening permits significant reduction of the process time, comparable to the CO2 hardening, at the same time guaranteeing over 10 times higher mechanical properties. Analysis of SEM photographs of the moulding sands hardened with the mentioned methods allow explaining differences in qualitative parameters of the moulding sands and their relation to structures of the created linking bridges.

  3. A MGy Radiation-Hardened Sensor Instrumentation SoC in 65nm CMOS Technology

    Verbeeck, Jens; Cao, Ying; Van Uffelen, Marco; Mont Casellas, Laura; Damiani, Carlo; Meek, Richard; Haist, Bernhard; Steyaert, Michiel; Leroux, Paul


    A radiation-hardened sensor instrumentation SoC is presented in this paper. The SoC is implemented in a standard 65nm CMOS technology, and achieves MGy-level TID radiation hardness through radiation-hardening-by-design.

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

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


    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.

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

    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

  6. Hot Machining of Hardened Steels with Coated Carbide Inserts

    M. A. Lajis


    Full Text Available Problem statement: The benefits of easier manufacture of hardened steel components can be substantial in terms of reduced machining costs and lead times compared to the traditional route involving machining of the annealed state followed by heat treatment, grinding/EDM and manual finishing. But machinability of hard material through conventional machining is hindered due to excessive wear of the cutting tools and differently in achieving desired quality of the machined surface. In end milling the cutting tool is not in constant operation and so undergoes a heat cycle during the intermittent cutting. This alternate heating and cooling of the inserts lead to the thermal cracks and subsequently failure of the tool. Approach: This study was conducted to investigate the effect of preheating through inductive heating mechanism in end milling (vertical milling center of AISI D2 hardened steel (56-62 HRC by using coated carbide tool inserts. Apart from preheating, two other machining parameters such as cutting speed and feed were varied while the depth of cut was kept constant. Results: Tool wear phenomenon and machined surface finish were found to be significantly affected by preheating temperature and other two variables. Preheating temperature of 335°C coupled with cutting speed of 40 m min-1, depth of cut of 1.0 mm and feed of 0.02 mm/tooth resulted in a noticeable reduction in tool wear rate leading to a maximum tool life 188.55 min. In addition, cutting speed of 56.57 m min-1 together with feed of 0.044 mm/tooth and depth of cut 1.0 mm at which maximum VMR (9500 mm3 was secured provides a better surface finish with minimum surface roughness 0.25µm leaving a possibility of skipping the grinding and polishing operations for certain applications. Conclusion/Recommendation: Through the end milling of preheated AISI D2 hardened steel by using TiAlN coated carbide cutting tool it can be concluded that an overall enhanced machinability is achievable by

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

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


    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.

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


    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.

  9. A fast beam hardening correction method incorporated in a filtered back-projection based MAP algorithm

    Luo, Shouhua; Wu, Huazhen; Sun, Yi; Li, Jing; Li, Guang; Gu, Ning


    The beam hardening effect can induce strong artifacts in CT images, which result in severely deteriorated image quality with incorrect intensities (CT numbers). This paper develops an effective and efficient beam hardening correction algorithm incorporated in a filtered back-projection based maximum a posteriori (BHC-FMAP). In the proposed algorithm, the beam hardening effect is modeled and incorporated into the forward-projection of the MAP to suppress beam hardening induced artifacts, and the image update process is performed by Feldkamp–Davis–Kress method based back-projection to speed up the convergence. The proposed BHC-FMAP approach does not require information about the beam spectrum or the material properties, or any additional segmentation operation. The proposed method was qualitatively and quantitatively evaluated using both phantom and animal projection data. The experimental results demonstrate that the BHC-FMAP method can efficiently provide a good correction of beam hardening induced artefacts.

  10. Effects of different tempers on precipitation hardening of 6000 series aluminium alloys

    LIU Hong; ZHAO Gang; LIU Chun-ming; ZUO Liang


    By means of Vickers hardness, mechanical property and formability tests, the effects of different tempers on precipitation hardening of 6000 series aluminium alloys for automotive body sheets were investigated. The results indicate that the short-time pre-aging at 170 ℃ makes for subsequent artificial aging precipitation hardening. With the increase of pre-aging time, the artificial aging hardenability increases. The aging hardening rate reaches the maximum when pre-aging time is up to 10 min, and then it decreases. The short-time pre-aging at 170 ℃ benefits sheets to obtain lower strength under delivery condition and consequently to improve stamping formability of automotive body sheets. The effects of different tempers on precipitation hardening are much more obvious than those of the alloying elements. It is a good treatment schedule to perform pre-aging for 5 min at 170 ℃ right after solution treatment.

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

    Li, H.; Liu, Y. H.


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

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

    Lee, Jewoong; De Cooman, Bruno C.


    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.

  13. Effect of cold work hardening on stress corrosion cracking of stainless steels in primary water of pressurized water reactors

    Raquet, O.; Herms, E. [CEA/Saclay, DEN/DPC, 91191 Gif sur Yvette Cedex (France); Vaillant, F.; Couvant, T.; Boursier, J.M. [EDF/Les Renardieres, R and D/MMC, 77250 Moret sur Loing (France)


    A R and D program is carried out in CEA and EDF laboratories to investigate separately the effects of factors which could contribute to IASCC mechanism. In the framework of this study, the influence of cold work on SCC of ASSs in primary water is studied to supply additional knowledge concerning the contribution of radiation hardening on IASCC of ASSs. Solution annealed ASSs, essentially of type AISI 304(L) and AISI 316(L), are generally considered very resistant to SCC in nominal primary water. However, Constant Extension Rate Tests (CERTs), performed on cold pressed humped specimens in nominal primary water at 360 deg. C, reveal that these materials can exhibit a high SCC susceptibility: deepest cracks reach 1 mm (mean crack growth rate about 1 {mu}m.h{sup -1}) and propagation is mainly intergranular for 304L and mainly transgranular for 316L. Indeed, work hardening in conjunction with high localized deformation can promote SCC. The influence of the nature of the cold work (shot peening, reaming, cold rolling, counter sinking, fatigue work hardening and tensile deformation) is investigated by means of screening CERTs performed with smooth specimens in 304L at 360 deg. C. For a given cold work hardening level, the susceptibility to crack initiation strongly depends on the cold working process, and no propagation is observed for a hardness level lower than 300 {+-}10 HV(0.49N). The propagation of cracks is observed only for dynamic loadings like CERT, traction/relaxation tests and crack growth rate tests performed with CT specimens under trapezoidal loading. Although crack initiation is observed for constant load and constant deformation tests, crack propagation do not seem to occur under these mechanical solicitations for 17000 hours of testing, even for hardness levels higher than 450 HV(0.49N). The mean crack growth rate increases when the hardness increases. An important R and D program is in progress to complement these results and to develop a SCC model for

  14. Grain refinement, hardening and metastable phase formation by high current pulsed electron beam (HCPEB) treatment under heating and melting modes

    Grosdidier, T., E-mail: Thierry.grosdidier@univ-metz.f [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Lab of Materials Modification by Laser, Ion and Electron Beams and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Zou, J.X. [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Bolle, B. [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), ENIM, Ile du Saulcy, 57045 Metz (France); Hao, S.Z.; Dong, C. [Lab of Materials Modification by Laser, Ion and Electron Beams and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)


    High current pulsed electron beam is a recently developed technique for surface modification. The pulsed electron irradiation introduces concentrated energy depositions in the thin surface layer of the treated materials, giving rise to an extremely fast heating and subsequent rapid cooling of the surface together with the formation of dynamic stress waves. Improved surface properties (hardness, corrosion resistance) can be obtained under the 'melting' mode when the top surface is melted and rapidly solidified (10{sup 7} K/s). In steels, this is essentially the result of nanostructures formed from the highly undercooled melt, melt surface purification, strain hardening induced by the thermal stress waves as well as metastable phase selections in the rapidly solidified melted layers. The use of the 'heating' mode is less conventional, combining effects of the heavy deformation and recrystallization/recovery mechanisms. A detailed analysis of a FeAl alloy demonstrates grain size refinement, hardening, solid-state enhanced diffusion and texture modification without modification of the surface geometry.

  15. Cooling Curve's Effect on Hardening Behavior of Steel

    Kazuto Fukuhara; Shigeru Asada; Yoshihiro Tomita; Syusaku Maeda


    Quenching Oils are comprised mostly of mineral oil as major component, but mineral oil alone result in lower cooling performance. Therefore, various additives are formulated as required for each particular case. Cooling curves of mineral oil as determined by JIS method can be divided into three stages, vapor film stage, boiling stage and convection stage. And there are many types of additives used for quenching oil, one effective to shorten vapor film stage and another to shift boiling stage toward lower temperature side. As rapid quenching required temperature range for particular steel varies pending on its shape of CCT curve(1), it is possible to provide higher quench hardening performance using quenching oil formulated of adequate additives.

  16. Water management in hardening Maytenus ilicifolia (Schrad. Planch. seedlings

    João Alexandre Lopes Dranski


    Full Text Available This study evaluated the effects of seedling height and irrigation management on M. ilicilofia seedlings. The experiment used a completely randomized design in a 2 x 3 factorial arrangement. Seedlings of two height classes (greater than or less than 18.0 cm were subjected to three irrigation regimes (daily irrigation, irrigation every other day, and gradual reduction of irrigation. After eight weeks, the morphophysiological and performance attributes of the seedlings were quantified. Gradual reduction of irrigation promoted the highest rate of net carbon assimilation. Irrigating every other day resulted in greater secondary growth rate, biomass accumulation in the shoot and root tissues, and lower electrolyte leakage rate. After planting, these treatments maintained higher leaf relative water content (RWC. RWC in seedlings smaller than 18 cm was significantly higher until the third week after planting. Therefore, larger seedlings submitted to hardening by gradually reducing irrigation improves seedling quality.


    ZHANG Taohong; YU Gang; WANG Jianlun; LIU Xiangyang


    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.

  18. Advances in positron studies of age hardening in light alloys

    Somoza, A. [IFIMAT, UNCentro and CICPBA, Pinto, Tandil (Argentina); Dupasquier, A.; Ferragut, R. [LNESS and CNISM, Politecnico di Milano, Como (Italy)


    The extensive experimental work on age hardening of Al- and Mg-based alloys, performed by the associated groups at IFIMAT (UNCentro, Argentina) and at LNESS (Politecnico di Milano, Italy) in recent years, is discussed here in a comprehensive way, with attention to experimental procedures and to results of general validity. For Al-based alloys, the established knowledge regarding the different action of Zn, Cu, Mg and Ag in the formation of vacancy-solute clusters is presented. For Mg-based alloys, the limits of positron annihilation spectroscopy are discussed on the basis of experience in progress. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Identifying Vulnerabilities and Hardening Attack Graphs for Networked Systems

    Saha, Sudip; Vullinati, Anil K.; Halappanavar, Mahantesh; Chatterjee, Samrat


    We investigate efficient security control methods for protecting against vulnerabilities in networked systems. A large number of interdependent vulnerabilities typically exist in the computing nodes of a cyber-system; as vulnerabilities get exploited, starting from low level ones, they open up the doors to more critical vulnerabilities. These cannot be understood just by a topological analysis of the network, and we use the attack graph abstraction of Dewri et al. to study these problems. In contrast to earlier approaches based on heuristics and evolutionary algorithms, we study rigorous methods for quantifying the inherent vulnerability and hardening cost for the system. We develop algorithms with provable approximation guarantees, and evaluate them for real and synthetic attack graphs.

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

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


    -dislocation and dislocation-interface reactions, such that heat treatment reduces the generation and interaction of dislocations, leading to an increase in strength and a reduction in ductility. A subsequent deformation step may restore the dislocation structure and facilitate the yielding process when the metal is stressed......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....... 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. Thermal Hardening: A New Seed Vigor Enhancement Tool in Rice

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


    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.

  2. Low-temperature tolerance and cold hardening of cacti

    Nobel, P.S.


    Reduced uptake by the chlorenchyma cells of cacti of a stain (neutral red) was used as an indicator of low-temperature damage resulting from cooling stems in the laboratory. Necrosis set in a few degrees below the temperature at which the fraction of cells accumulating stain was reduced by 50%. Coryphantha vivipara, Opuntia polyacantha, and Pediocactus simpsonii, which range to over 300 m altitude in southern Wyoming, were quite cold tolerant. Relationships among tissue cold sensitivity, morphological features which protect the stems from low temperatures, and the occurrence of species in progressively colder regions were investigated. Differences in tissue cold sensitivity accounted for the approx. = 600 m higher elevational limit of Coryphantha vivipara var. rosea compared to the morphologically similar var. deserti in southern Nevada. In contrast, morphological differences alone could adequately explain the relative northern limits of the columnar cacti Carnegiea gigantea vs Stenocereus gummosus and the barrel cacti Ferocactus acanthodes vs. F. wislizenii in the southwestern United States, as previously indicated using a computer model. Cold hardening in response to decreasing day/night air temperatures was observed for 10 species. A decrease from 50/sup 0//40/sup 0/ to 10/sup 0//0/sup 0/ lowered by 4/sup 0/ the temperature at which the fraction of the chlorenchyma cells taking up stain was reduced 50% for both D. rhodacantha and T. candicans, with a half-time for the shift of approx. = 3 d. The tolerance of subzero temperatures and the ability to cold harden allow cacti to range into regions with considerable wintertime freezing.

  3. Characterization and hardening of concrete with ultrasonic testing.

    del Río, L M; Jiménez, A; López, F; Rosa, F J; Rufo, M M; Paniagua, J M


    In this study, we describe a technique which can be used to characterize some relevant properties of 26 cylindrical samples (15 x 30 cm2) of concrete. The characterization has been performed, according to Spanish regulations in force, by some destructive and ultrasound-based techniques using frequencies of 40 kHz. Samples were manufactured using different water/cement ratios (w/c), ranging from 0.48 to 0.80, in order to simulate different values of compressive strength at each sample. We have correlated the propagation velocity v of ultrasonic waves through the samples to compressive strength R values. As some other authors remark, there exists an exponential relationship between the two above parameters. We have found that a highly linear relationship is present between R and w/c concentration at the samples. Nevertheless, when the same linear model is adopted to describe the relationship between v and w/c, the value of r decreases significantly. Thus, we have performed a multiple regression analysis which takes into account the impact of different concrete constituents (water, cement, sand, etc.) on ultrasound propagation speed. One of the most relevant practical issues addressed in our study is the estimation of the hardening curve of concrete, which can be used to quantify the viability of applying the proposed method in a real scenario. Subsequently, we also show a detailed analysis of the temporal evolution of v and R through 61 days, beginning at the date where the samples were manufactured. After analyzing both parameters separately, a double reciprocal relationship is deduced. Using the above parameters, we develop an NDE-based model which can be used to estimate hardening time of concrete samples.


    A. I. Mihluk


    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.

  5. Hygroscopicity -resistant mechanism of an α -starch based composite binder for dry sand molds and cores

    Xia ZHOU


    Full Text Available Hygroscopicity-resistance of an α-starch based composite binder for dry sand molds (cores has been studied experimentally and theoretically. Focus is placed on the relationship between the hardening structure and humidity-resistance of the composite binder. The results show that the α-starch composite binder has good humidity-resistance due to its special complex structure. SEM observations illustrate that the composite binder consists of reticular matrix and a ball- or lump-shaped reinforcement phase, and the specific property of the binding membrane with heterogeneous structure is affected by humidity to a small extent. Based on the analyses on the interplays of different ingredients in the binder at hardening, the structure model and hygroscopicity-resistant mechanisms of the hardening composite binder were further proposed. Moreover, the reasons for good humidity-resistance of the composite binder bonded sand are well explained by the humidity-resistant mechanisms.

  6. Finite Element Analysis of Composite Hardened Walls Subjected to Blast Loads

    Girum S. Urgessa


    Full Text Available Problem statement: There is currently no standard design guideline to determine the number of composites needed to retrofit masonry walls in order to withstand a given explosion. Past design approaches were mainly based on simplified single-degree-of-freedom analysis. A finite element analysis was conducted for concrete masonry walls hardened with composites and subjected to short duration blast loads. Approach: The analysis focused on displacement time history responses which form the basis for retrofit design guidelines against blast loadings. The blast was determined from 0.5 kg equivalent TNT explosive at 1.83 m stand-off distance to simulate small mailroom bombs. Two and four layered retrofitted walls were investigated. Uncertainties in the finite model analysis of walls such as pressure distributions, effect of mid height explosive bursts versus near the ground explosive bursts and variations in modulus of elasticity of the wall were presented. Results: Uniformly distributed blast loads over the retrofitted wall height produced a small difference in peak displacement results when compared to the non-uniform pressure distribution. Ground explosive burst was shown to produce a 62.7% increase in energy and a higher peak displacement response when compared to mid-height explosive burst. Conclusion: The parametric study on the variation of modulus of elasticity of concrete masonry showed no significant effect on peak displacement affirming the use of the resistance deflection contribution of the composite in retrofit designs.

  7. Formation quality optimization of laser hot wire cladding for repairing martensite precipitation hardening stainless steel

    Wen, Peng; Feng, Zhenhua; Zheng, Shiqing


    Laser cladding is an advantaged repairing technology due to its low heat input and high flexibility. With preheating wire by resistance heat, laser hot wire cladding shows better process stability and higher deposition efficiency compared to laser cold wire/powder cladding. Multi-pass layer were cladded on the surface of martensite precipitation hardening stainless steel FV520B by fiber laser with ER410NiMo wire. Wire feed rate and preheat current were optimized to obtain stable wire transfer, which guaranteed good formation quality of single pass cladding. Response surface methodology (RSM) was used to optimize processing parameters and predict formation quality of multi-pass cladding. Laser power P, scanning speed Vs, wire feed rate Vf and overlap ratio η were selected as the input variables, while flatness ratio, dilution and incomplete fusion value as the responses. Optimal clad layer with flat surface, low dilution and no incomplete fusion was obtained by appropriately reducing Vf, and increasing P, Vs and η. No defect like pore or crack was found. The tensile strength and impact toughness of the clad layer is respectively 96% and 86% of those of the substrate. The clad layer showed nonuniform microstructure and was divided into quenched areas with coarse lath martensite and tempered areas with tempered martensite due to different thermal cycles in adjacent areas. The tempered areas showed similar hardness to the substrate.

  8. In-situ surface hardening of cast iron by surface layer metallurgy

    Fischer, Sebastian F., E-mail: [Foundry Institute, RWTH Aachen University, Intzestraße 5, 52072 Aachen (Germany); Muschna, Stefan, E-mail: [Foundry Institute, RWTH Aachen University, Intzestraße 5, 52072 Aachen (Germany); Bührig-Polaczek, Andreas, E-mail: [Foundry Institute, RWTH Aachen University, Intzestraße 5, 52072 Aachen (Germany); Bünck, Matthias, E-mail: [Access e.V., Intzestraße 5, 52072 Aachen (Germany)


    Abrasive wear is a serious problem in many cast iron castings used in industry. To minimize failure and repair of these components, different strategies exist to improve their surface microhardness thus enhancing their wear resistance. However, most of these methods lead to very brittle and/or expensive castings. In the current work a new method for surface hardening is presented which utilizes surface layer metallurgy to generate in-situ a boron-enriched white cast iron surface layer with a high microhardness on a gray cast iron casting. To do this, sand molds are coated with a ferroboron suspension and cast with a cast iron melt. After solidification, a 100–900 µm thick layer of boron-enriched ledeburite is formed on the surface of the casting which produces an increase in the average microhardness from 284 HV{sub 0.1}±52 HV{sub 0.1} to 505 HV{sub 0.1}±87 HV{sub 0.1}. Analyses of the samples' core reveal a typical cast iron microstructure which leads to the conclusion that the coating mainly affects the castings' surface. By varying the grain size of the ferroboron powder in the coatings, it is shown that a powder size ≤100 µm is most suitable to create a boron-enriched ledeburite surface layer possessing high hardness values.

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

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


    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. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Radiation hardening of low-noise readout integrated circuit for infrared focal plane arrays

    Lee, Min Su; Lee, Yong Soo; Lee, Hee Chul


    A radiation-resistant readout integrated circuit for focal plane arrays was studied to improve the reliability of infrared image systems operating in a radioactive environment, such as in space or in the surroundings of a nuclear reactor. First, as radiation-hardened NMOSFET structure, which includes a layout modification technique, was proposed. The readout integrated circuit for infrared focal plane arrays was then designed on basis of the proposed NMOSFET layout. Commercial 0.35 um process technology was used to fabricate the proposed unit NMOSFET and the designed readout integrated circuit which is based on the proposed NMOSFET. The measured electrical characteristics of the fabricated unit NMOSFET and readout integrated circuit are in good agreement with the simulated results. For verification of the radiation tolerance, the fabricated chip was exposed to 1 Mrad (Si) of gamma radiation, which is high enough to guarantee reliable usage in space or in a very harsh radiation environment. While exposed to gamma radiation, the fabricated chip was connected to a power supply (3.3 V) for testing under the worst conditions. After being exposed to 1 Mrad of gamma radiation, the unit NMOSFET showed only a slight increment of a few picoamperes in the leakage current, and the designed readout integrated circuit showed little change at an output voltage of less than 10% of a proper output voltage. The changes in the characteristics of the unit NMOSFET and the designed readout infrared integrated circuit are at an allowable level in relation to process variation.

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

    Kvačkaj, T.


    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.

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

    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: [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)


    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.

  13. Effect of Pre-strain on the Solute Clustering, Mechanical Properties, and Work-Hardening of a Naturally Aged Al-Cu-Mg Alloy

    Shao, D.; Zhang, P.; Zhang, J. Y.; Liu, G.; Wang, R. H.; Liu, W. Q.; Sha, G.; Sun, J.


    The effect of pre-strain on the solute clustering, mechanical properties, and work-hardening of a naturally aged Al-Cu-Mg alloy was comprehensively investigated using a three-dimensional atom probe, electrical resistivity, and hardness measurements. The pre-strain promoted the rapid formation of solute clusters but suppressed the growth of solute clusters during prolonged aging. An increase in pre-strain caused a decrease in the saturated number density of solute clusters, leading to a reduction in cluster strengthening. By taking into account the coupling effect of solute clusters and pre-existing dislocations, models were proposed to address the yield strength and work-hardening behaviors of the Al-Cu-Mg alloy, respectively. It reveals that the solute-cluster strengthening is comparable to dislocation strengthening in the naturally aged alloy. However, the work hardening is not significantly affected by the presence of the solute clusters. The findings reported in this paper will be helpful for the development of a naturally aged Al-Cu-Mg alloy with improved performance by controlling the pre-strain.

  14. Work Hardening Behavior of 1020 Steel During Cold-Beating Simulation

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


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

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

    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


    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.

  16. Local hardening evaluation of carbon steels by using frequency sweeping excitation and spectrogram method

    Tsuchida, Yuji; Kudo, Yuki; Enokizono, Masato


    This paper presents our proposed frequency sweeping excitation and spectrogram method (FSES method) by a magnetic sensor for non-destructive testing of hardened low carbon steels. This method can evaluate the magnetic properties of low carbon steels which were changed after induction heating treatment. It was examined by our proposed method that the degrees of yield strength of low carbon steels were varied depending on hardened conditions. Moreover, it was made clear that the maximum magnetic field strength, Hmax, derived from the measured B-H loops was very sensitive to the hardening if the surface of the samples were flat.


    V. A. Tomilo


    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.

  18. Optimization of machining and vibration parameters for residual stresses minimization in ultrasonic assisted turning of 4340 hardened steel.

    Sharma, Varun; Pandey, Pulak M


    The residual stresses generated in the machined work piece have detrimental effect on fatigue life, corrosion resistance and tribological properties. However, the effect of cutting and vibration parameters on residual stresses in Ultrasonic Assisted Turning (UAT) has not been dealt with. The present paper highlights the effect of feed rate, depth of cut, cutting velocity and percentage intensity of ultrasonic power on residual stress generation. XRD analysis has been carried out to measure the residual stress while turning 4340 hardened steel using UAT. The experiments were performed based on response surface methodology to develop statistical model for residual stress. The outcome of ANOVA revealed that percentage intensity and feed rate significantly affect the residual stress generation. The significant interactions between process parameters have also been presented tin order to understand the thermo-mechanical mechanism responsible for residual stress generation.

  19. Tribological behaviour of line hardening of steel U13A with Nd: YAG laser

    Sagaro, R.


    Full Text Available To diminish wear in tribological systems is frequently to harden locally the load carrying areas, which are subjected to wear. A Nd:YAG laser was used for the improvement of hardness and wear resistance of steel U13A. The friction and wear characteristics of steel U13A in sliding contact against steel 65MN4 under unlubricated conditions were evaluated for conventional treatments and after laser irradiation. In addition the transformations occurring during laser treatments and the influence of laser parameters for quenching on tribological characteristics are presented. The experimental work indicates that wear resistance of steel U13A (AISI Wl 12 is several times higher then that for conventional heat treatments.

    Para disminuir el desgaste en los sistemas tribológicos frecuentemente se llevan a cabo endurecimientos localizados en aquellas áreas sometidas a esfuerzos y que están sujetas a desgaste. En el trabajo se presenta el endurecimiento y el incremento de la resistencia al desgaste del acero U13A, empleando un láser de Nd: YAG. Se evalúan las características de fricción y desgaste del acero U13A en contacto deslizante con el acero 65MN4 bajo condiciones de fricción seca para muestras con tratamientos térmicos convencionales y luego del tratamiento con láser. Se presentan además las transformaciones estructurales que tienen lugar durante el tratamiento con láser, así como la influencia de los parámetros operacionales del láser en las características tribológicas. Todo el trabajo experimental muestra un incremento de la resistencia al desgaste del acero U13A (AISI W112 con tratamiento térmico superficial con láser comparativamente con los tratamientos térmicos convencionales.

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

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


    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

  1. NINJA: a noninvasive framework for internal computer security hardening

    Allen, Thomas G.; Thomson, Steve


    Vulnerabilities are a growing problem in both the commercial and government sector. The latest vulnerability information compiled by CERT/CC, for the year ending Dec. 31, 2002 reported 4129 vulnerabilities representing a 100% increase over the 2001 [1] (the 2003 report has not been published at the time of this writing). It doesn"t take long to realize that the growth rate of vulnerabilities greatly exceeds the rate at which the vulnerabilities can be fixed. It also doesn"t take long to realize that our nation"s networks are growing less secure at an accelerating rate. As organizations become aware of vulnerabilities they may initiate efforts to resolve them, but quickly realize that the size of the remediation project is greater than their current resources can handle. In addition, many IT tools that suggest solutions to the problems in reality only address "some" of the vulnerabilities leaving the organization unsecured and back to square one in searching for solutions. This paper proposes an auditing framework called NINJA (acronym for Network Investigation Notification Joint Architecture) for noninvasive daily scanning/auditing based on common security vulnerabilities that repeatedly occur in a network environment. This framework is used for performing regular audits in order to harden an organizations security infrastructure. The framework is based on the results obtained by the Network Security Assessment Team (NSAT) which emulates adversarial computer network operations for US Air Force organizations. Auditing is the most time consuming factor involved in securing an organization's network infrastructure. The framework discussed in this paper uses existing scripting technologies to maintain a security hardened system at a defined level of performance as specified by the computer security audit team. Mobile agents which were under development at the time of this writing are used at a minimum to improve the noninvasiveness of our scans. In general, noninvasive

  2. A comprehensive assessment of geographic variation in heat tolerance and hardening capacity in populations of Drosophila melanogaster from eastern Australia

    Sgrò, C M; Overgaard, J; Kristensen, T N;


    We examined latitudinal variation in adult and larval heat tolerance in Drosophila melanogaster from eastern Australia. Adults were assessed using static and ramping assays. Basal and hardened static heat knockdown time showed significant linear clines; heat tolerance increased towards the tropics...... knockdown temperature increased towards temperate latitudes, probably reflecting a greater capacity of temperate flies to withstand sudden temperature increases during summer in temperate Australia. Larval viability showed a quadratic association with latitude under heat stress. Thus, patterns of heat...... resistance depend on assay methods. Genetic correlations in thermotolerance across life stages and evolutionary potential for critical thermal limits should be the focus of future studies....

  3. An Experimental Investigation for Wear Rate Optimization on Different Gear Materials Using Hardening

    Abhijeet sing v Makwana


    Full Text Available An Experimental Investigation for Wear Rate Optimization on Different Gear Materials (EN8, 8620 & MILD STEEL Using Hardening.” mainly focuses on the mechanical design and analysis of gearbox as transmit the power and live long life. Gears play an essential role in the performance of many products that we rely on in our everyday lives. Gears are mainly used in lathes machines, automobiles and all torque transmitting units. The improved mechanical properties achieved by hardening process. This research focuses on optimizing wear rate of different gear materials using hardening process. The main Objective of this research is to find out the best material for manufacturing gear by hardening process.

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

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


    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...

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

    A. Bokota


    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.

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

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


    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. A 45 nm Low Cost, Radiation Hardened, Platform Based Structured ASIC Project

    National Aeronautics and Space Administration — The proposed 45 nm radiation hardened platform based structured ASIC architecture offers the performance and density expected of a custom ASIC with the low...


    L. A. Glazkov


    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.

  9. Influence of the Hardener Proportion on Mechanical Properties of Adhesive Bonds Used in Agriculture

    Valášek P.


    Full Text Available Joining materials by adhesive bonding is used across all industrial branches. The occurrence of adhesive bonds in machine constructions is still more frequent because of the development of adhesives which are able to meet various requirements of designers. This trend is observable also in agriculture - in the construction of agricultural machines. There even exists a cooperation between the companies developing the adhesives and the agricultural machines producers. The production process of machines and equipment must consider a required production tact. Adhesives and the process of their hardening have to meet these requirements. In the sphere of agriculture, epoxy resins hardening based either on hardeners or heating are used. Mechanical properties of two-component epoxy resins depending on variable amount of the hardener starting crosslinking of these reactoplastics are described.

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

    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...

  11. Work-hardening behavior of mild steel under cyclic deformation at finite strains

    Hu, Z. (Univ. Paris-Nord, Villetaneuse (France))


    The work-hardening behavior of mild steel under monotonic deformation at large shears and cyclic deformation under a wide range of shear amplitudes (from 3 to 34%) has been experimentally investigated and modeled. The influence of shear amplitude, the effect of the amount of pre-shear and that of pre-cyclic deformation have been studied. Considering the evolution of both polarized persistent dislocation structures and no-polarized low-energy dislocation configurations, a physically-based phenomenological model with four internal variables has been proposed. The model explains the cyclic hardening behavior at large strains, the work-hardening stagnation followed by a resumption of work-hardening under Bauschinger deformation with large pre-strains and under cyclic deformation with moderate strain amplitudes. A good qualitative and quantitative agreement has been achieved between experimental results and model predictions.

  12. The Use of Fuzzy Systems for Forecasting the Hardenability of Steel

    Sitek W.


    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.

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

    Xianhua Cheng; Qianqian Shangguan


    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.

  14. The sub-zero Celsius treatment of precipitation hardenable semi-austenitic stainless steel

    Villa, Matteo; Hansen, Mikkel Fougt; Somers, Marcel A. J.


    A precipitation hardenable semi-austenitic stainless steel AISI 632 grade was austenitized according to industrial specifications and thereafter subjected to isothermal treatment at sub-zero Celsius temperatures. During treatment, austenite transformed to martensite. The isothermal austenite...

  15. Induction hardening of tool steel for heavily loaded aircraft engine components

    Rokicki P.


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

  16. Observation of a New Mechanism Balancing Hardening and Softening in Metals

    Yu, Tianbo; Hansen, Niels; Huang, Xiaoxu


    Plastic deformation of metals refines the microstructure and increases the strength through work hardening, but this effect of deformation is counterbalanced by dynamic recovery. After large strain, the microstructure typically shows a lamellar morphology, with finely spaced lamellar boundaries c...

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

    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...

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

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


    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.

  19. Flywheel starter ring gear failures and hardness variation reduction in surface hardening process

    Selçuk Can Yücel


    This technical paper summarizes the case study conducted for truck flywheel starter ring gears with diameter of 470 mm in order to reduce hardness variation by optimization of induction hardening and tempering processes.

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

    Alexandre da Silva Rocha


    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.

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

    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...

  2. Waste tyre rubberized concrete: properties at fresh and hardened state.

    Aiello, M A; Leuzzi, F


    The main objective of this paper is to investigate the properties of various concrete mixtures at fresh and hardened state, obtained by a partial substitution of coarse and fine aggregate with different volume percentages of waste tyres rubber particles, having the same dimensions of the replaced aggregate. Workability, unit weight, compressive and flexural strength and post-cracking behaviour were evaluated and a comparison of the results for the different rubcrete mixtures were proposed in order to define the better mix proportions in terms of mechanical properties of the rubberized concrete. Results showed in this paper were also compared to data reported in literature. Moreover, a preliminary geometrical, physical and mechanical characterization on scrap tyre rubber shreds was made. The rubberized concrete mixtures showed lower unit weight compared to plain concrete and good workability. The results of compressive and flexural tests indicated a larger reduction of mechanical properties of rubcrete when replacing coarse aggregate rather than fine aggregate. On the other hand, the post-cracking behaviour of rubberized concrete was positively affected by the substitution of coarse aggregate with rubber shreds, showing a good energy absorption and ductility indexes in the range observed for fibrous concrete, as suggested by standard (ASTM C1018-97, 1997).

  3. Selection of material for cores hardened with carbon dioxide

    M. S. Soiński


    Full Text Available The work presents the investigation results concerning the bending and the tensile strength of specimens made of various types of core sands. The investigated core sands for bending tests have been prepared of silica sand from Nowogród Dobrzański and, alternatively, of H33 German sand, both containing a variety of binders, namely Carbophen 5692, Carbophen 7170, Carbophen 8178, Novatec 1000, or SuperEko 2000 phenolic resins, as well as water glass. The tensile strength has been investigated for specimens made of silica sand from Nowogród Dobrzański and the sand supplied by Hüttenes-Albertus Polska, both types bond with Carbophen 5692, Novatec 1000, or SuperEko 2000 resins. All specimens have been tested immediately after the CO2 hardening process, then after 1 hour and after 24 hours. It has been found that the type of sand grains significantly affects both the bending and the tensile strength. Furthermore, for each type of sand the best bending strength has been achieved for Carbophen 7170, Carbophen 8178, and Novatec 1000 resins, whereas the best tensile strength has been offered by specimens bond with Carbophen 5692 resin.

  4. A radiation-hardened SOI-based FPGA

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


    A radiation-hardened SRAM-based field programmable gate array VS 1000 is designed and fabricated with a 0.5 μm partial-depletion silicon-on-insulator logic process at the CETC 58th Institute.The new logic cell (LC),with a multi-mode based on 3-input look-up-table (LUT),increases logic density about 12% compared to a traditional 4-input LUT.The logic block (LB),consisting of 2 LCs,can be used in two functional modes:LUT mode and distributed read access memory mode.The hierarchical routing channel block and switch block can significantly improve the flexibility and routability of the routing resource.The VS1000 uses a CQFP208 package and contains 392 reconfigurable LCs,112 reconfigurable user I/Os and IEEE 1149.1 compatible with boundaryscan logic for testing and programming.The function test results indicate that the hardware and software cooperate successfully and the VS 1000 works correctly.Moreover,the radiation test results indicate that the VS 1000 chip has total dose tolerance of 100 krad(Si),a dose rate survivability of 1.5 × 1011 rad(Si)/s and a neutron fluence immunity of 1 × 1014 n/cm2.

  5. Radiation Hardened, Modulator ASIC for High Data Rate Communications

    McCallister, Ron; Putnam, Robert; Andro, Monty; Fujikawa, Gene


    Satellite-based telecommunication services are challenged by the need to generate down-link power levels adequate to support high quality (BER approx. equals 10(exp 12)) links required for modem broadband data services. Bandwidth-efficient Nyquist signaling, using low values of excess bandwidth (alpha), can exhibit large peak-to-average-power ratio (PAPR) values. High PAPR values necessitate high-power amplifier (HPA) backoff greater than the PAPR, resulting in unacceptably low HPA efficiency. Given the high cost of on-board prime power, this inefficiency represents both an economical burden, and a constraint on the rates and quality of data services supportable from satellite platforms. Constant-envelope signals offer improved power-efficiency, but only by imposing a severe bandwidth-efficiency penalty. This paper describes a radiation- hardened modulator which can improve satellite-based broadband data services by combining the bandwidth-efficiency of low-alpha Nyquist signals with high power-efficiency (negligible HPA backoff).

  6. The structural dependence of work hardening in low carbon steels

    Johnson, P.E.


    The influence of the dislocation cell structure on the work hardening behavior of low carbon steel sheets was investigated. Specimens were prestrained at low temperature to suppress cell formation and their subsequent behavior was compared with results of isothermal reference tests. It was found that the extent of cell development has little or no influence on the plastic behavior at room temperature and below. Interrupted temperature, tensile-shear tests demonstrated further that the transient behavior induced by loading path changes is also not strongly associated with the cell walls. In-situ straining studies indicate that the factor controlling the flow stress at room temperature is the limited mobility of screw dislocations moving the cell interiors, and not dislocation interactions with the cell walls. The unique properties of a/2<111> screw dislocations are known to dominate low temperature deformation behavior in bcc metals. The current work indicates that these dislocations may still control the flow stress at intermediate temperatures, even in the presence of a developed cell structure.

  7. A Radiation Hardened by Design CMOS ASIC for Thermopile Readouts

    Quilligan, G.; Aslam, S.; DuMonthier, J.


    A radiation hardened by design (RHBD) mixed-signal application specific integrated circuit (ASIC) has been designed for a thermopile readout for operation in the harsh Jovian orbital environment. The multi-channel digitizer (MCD) ASIC includes 18 low noise amplifier channels which have tunable gain/filtering coefficients, a 16-bit sigma-delta analog-digital converter (SDADC) and an on-chip controller. The 18 channels, SDADC and controller were designed to operate with immunity to single event latchup (SEL) and to at least 10 Mrad total ionizing dose (TID). The ASIC also contains a radiation tolerant 16-bit 20 MHz Nyquist ADC for general purpose instrumentation digitizer needs. The ASIC is currently undergoing fabrication in a commercial 180 nm CMOS process. Although this ASIC was designed specifically for the harsh radiation environment of the NASA led JEO mission it is suitable for integration into instrumentation payloads 011 the ESA JUICE mission where the radiation hardness requirements are slightly less stringent.

  8. Yield Hardening of Electrorheological Fluids in Channel Flow

    Helal, Ahmed; Qian, Bian; McKinley, Gareth H.; Hosoi, A. E.


    Electrorheological fluids offer potential for developing rapidly actuated hydraulic devices where shear forces or pressure-driven flow are present. In this study, the Bingham yield stress of electrorheological fluids with different particle volume fractions is investigated experimentally in wall-driven and pressure-driven flow modes using measurements in a parallel-plate rheometer and a microfluidic channel, respectively. A modified Krieger-Dougherty model can be used to describe the effects of the particle volume fraction on the yield stress and is in good agreement with the viscometric data. However, significant yield hardening in pressure-driven channel flow is observed and attributed to an increase and eventual saturation of the particle volume fraction in the channel. A phenomenological physical model linking the densification and consequent microstructure to the ratio of the particle aggregation time scale compared to the convective time scale is presented and used to predict the enhancement in yield stress in channel flow, enabling us to reconcile discrepancies in the literature between wall-driven and pressure-driven flows.

  9. A radiation-hardened SOI-based FPGA

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


    A radiation-hardened SRAM-based field programmable gate array VS1000 is designed and fabricated with a 0.5 μm partial-depletion silicon-on-insulator logic process at the CETC 58th Institute. The new logic cell (LC), with a multi-mode based on 3-input look-up-table (LUT), increases logic density about 12% compared to a traditional 4-input LUT The logic block (LB), consisting of 2 LCs, can be used in two functional modes: LUT mode and distributed read access memory mode. The hierarchical routing channel block and switch block can significantly improve the flexibility and routability of the routing resource. The VS1000 uses a CQFP208 package and contains 392 reconfigurable LCs, 112 reconfigurable user I/Os and IEEE 1149.1 compatible with boundary-scan logic for testing and programming. The function test results indicate that the hardware and software cooperate successfully and the VS1000 works correctly. Moreover, the radiation test results indicate that the VS1000 chip has total dose tolerance of 100 krad(Si), a dose rate survivability of 1.5 × 1011 rad(Si)/s and a neutron fluence immunity of 1 × 1014 n/cm2.

  10. Environmental hardening of robots for nuclear maintenance and surveillance tasks

    Hintenlang, D.E.; Tulenko, J.S.; Wheeler, R.; Roy, T. (Univ. of Florida, Gainesville (USA))


    The University of Florida, in cooperation with the Universities of Texas, Tennessee, and Michigan and Oak Ridge National Laboratory, is developing an advanced robotic system for the US Department of Energy under the University Program for Robotics for Advanced Reactors. As part of this program, the University of Florida has been pursuing the development of environmentally hardened components so that autonomous robotic systems can successfully carry out their tasks under the most extreme expected environmental conditions. This requirement means that the designed robotic system with its onboard computer-based intelligence must be able to successfully complete tasks in toxic, radioactive, wet, temperature extremes, and other physically impairing environments. As part of this program, a study was carried out to determine the environmental conditions that should be set as the design criteria for robotic systems to maintain reasonable operations for nuclear plants in the course of maintenance, testing, and surveillance under all conditions, including plant upset. It was decided that Florida would build a combined environmental testing facility to test specific devices in high-radiation/high-temperature combined environments. This environmental test chamber has been built and successfully tested to over 250{degree}F. This facility will provide some of the first combined temperatures/radiation data for many large-scale integrated components.

  11. On estimating the effective diffusive properties of hardened cement pastes

    Stora, E.; Bary, B. [CEA Saclay, DEN/DANS/DPC/SCCME, Lab Etud Comportement Betons et Argiles, F-91191 Gif Sur Yvette, (France); Stora, E.; He, Qi-Chang [Univ Paris Est, Lab Paris Est, F-77454 Marne La Vallee 2, (France)


    The effective diffusion coefficients of hardened cement pastes can vary between a few orders of magnitude. The paper aims at building a homogenization model to estimate these macroscopic diffusivities and capture such strong variations. For this purpose, a three-scale description of the paste is proposed, relying mainly on the fact that the initial cement grains hydrate forming a complex microstructure with a multi-scale pore structure. In particular, porosity is found to be well connected at a fine scale. However, only a few homogenization schemes are shown to be adequate to account for such connectivity. Among them, the mixed composite spheres assemblage estimate (Stora, E., He, Q.-C., Bary, B.: J. Appl. Phys. 100(8), 084910, 2006a) seems to be the only one that always complies with rigorous bounds and is consequently employed to predict the effects of this fine porosity on the material effective diffusivities. The model proposed provides predictions in good agreement with experimental results and is consistent with the numerous measurements of critical pore diameters issued from mercury intrusion porosimetry tests. The evolution of the effective diffusivities of cement pastes subjected to leaching is also assessed by adopting a simplified scenario of the decalcification process. (authors)

  12. Analysis of the regimes in the scanner-based laser hardening process

    Martínez, S.; Lamikiz, A.; Ukar, E.; Calleja, A.; Arrizubieta, J. A.; Lopez de Lacalle, L. N.


    Laser hardening is becoming a consolidated process in different industrial sectors such as the automotive industry or in the die and mold industry. The key to ensure the success in this process is to control the surface temperature and the hardened layer thickness. Furthermore, the development of reliable scanners, based on moving optics for guiding high power lasers at extremely fast speeds allows the rapid motion of laser spots, resulting on tailored shapes of swept areas by the laser. If a scanner is used to sweep a determined area, the laser energy density distribution can be adapted by varying parameters such us the scanning speed or laser power inside this area. Despite its advantages in terms of versatility, the use of scanners for the laser hardening process has not yet been introduced in the thermal hardening industry because of the difficulty of the temperature control and possible non-homogeneous hardness thickness layers. In the present work the laser hardening process with scanning optics applied to AISI 1045 steel has been studied, with special emphasis on the influence of the scanning speed and the results derived from its variation, the evolution of the hardened layer thickness and different strategies for the control of the process temperature. For this purpose, the hardened material has been studied by measuring microhardness at different points and the shape of the hardened layer has also been evaluated. All tests have been performed using an experimental setup designed to keep a nominal temperature value using a closed-loop control. The tests results show two different regimes depending on the scanning speed and feed rate values. The experimental results conclusions have been validated by means of thermal simulations at different conditions.

  13. Upper bound limit and shakedown analysis of elastic plastic bounded linearly kinematic hardening structures


    This thesis develops a new FEM based algorithm for shakedown analysis of structures made of elastic plastic bounded linearly kinematic hardening material. Its concept can be briefly described as: Hardening law is simulated using a two-surface plastic model. One yield surface is the initial surface, defined by yield stress sigma_y, and the other one is the bounding surface, defined by ultimate strength sigma_u. The initial surface can translate inside the bounding surface without changing its ...

  14. Optimizing the Thermal Regime During the Acceleration of Concrete’s Hardening

    Vladimir Corobceanu


    Researches conducted at the Faculty of Construction in Jassy showed several factors that may help finding technical solutions which will make possible to economically apply acceleration procedures of concrete hardening by thermal treatment with solar energy. It has to be mentioned the fact that the thermal treatment do not exclude, but it is based on the acceleration methods of concrete hardening through composition with or without the usage of different additives -- plasticizer type (to redu...

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

    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)


    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.

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

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


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

  17. A Review of NASA's Radiation-Hardened Electronics for Space Environments Project

    Keys, Andrew S.; Adams, James H.; Patrick, Marshall C.; Johnson, Michael A.; Cressler, John D.


    NASA's Radiation Hardened Electronics for Space Exploration (RHESE) project develops the advanced technologies required to produce radiation hardened electronics, processors, and devices in support of the requirements of NASA's Constellation program. Over the past year, multiple advancements have been made within each of the RHESE technology development tasks that will facilitate the success of the Constellation program elements. This paper provides a brief review of these advancements, discusses their application to Constellation projects, and addresses the plans for the coming year.

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


    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 ...

  19. Stage IV work-hardening related to disorientations in dislocation structures

    Pantleon, W.


    . Disorientations evolving from purely statistical reasons — leading to a square root dependence of the average disorientation angle on strain — affect the initial work-hardening rate (and the saturation stress) of stage III only slightly. On the other hand, deterministic contributions to the development...... of disorientations, as differences in the activated slip systems across boundaries, cause a linear increase of the flow stress at large strains. Such a constant work-hardening rate is characteristic for stage IV....

  20. Microstructural analysis of ion-irradiation-induced hardening in inconel 718

    Hashimoto, N.; Hunn, J. D.; Byun, T. S.; Mansur, L. K.


    As an assessment for a possible accelerator beam line window material for the US Spallation Neutron Source (SNS) target, performance, radiation-induced hardening and microstructural evolution in Inconel 718 were investigated in both solution annealed (SA) and precipitation hardened (PH) conditions. Irradiations were carried out using 3.5 MeV Fe +, 370 keV He + and 180 keV H + either singly or simultaneously at 200 °C to simulate the damage and He/H production in the SNS target vessel wall. This resulted in systematic hardening in SA Inconel and gradual net softening in the PH material. TEM microstructural analysis showed the hardening was associated with the formation of small loop and faulted loop structures. Helium-irradiated specimens included more loops and cavities than Fe + ion-irradiated specimens. Softening of the PH material was due to dissolution of the γ '/γ ″ precipitates. High doses of helium were implanted in order to study the effect of high retention of gaseous transmutation products. Simultaneous with the hardening and/or softening due to the displacement damage cascade, helium filled cavities produced additional hardening at high concentrations.

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

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


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

  2. Analysis of Hardened Depth Variability, Process Potential, and Measurement Error in Case Carburized Components

    Rowan, Olga K.; Keil, Gary D.; Clements, Tom E.


    Hardened depth (effective case depth) measurement is one of the most commonly used methods for carburizing performance evaluation. Variation in direct hardened depth measurements is routinely assumed to represent the heat treat process variation without properly correcting for the large uncertainty frequently observed in industrial laboratory measurements. These measurement uncertainties may also invalidate application of statistical control requirements on hardened depth. Gage R&R studies were conducted at three different laboratories on shallow and deep case carburized components. The primary objectives were to understand the magnitude of the measurement uncertainty and heat treat process variability, and to evaluate practical applicability of statistical control methods to metallurgical quality assessment. It was found that ~75% of the overall hardened depth variation is attributed to the measurement error resulting from the accuracy limitation of microhardness equipment and the linear interpolation technique. The measurement error was found to be proportional to the hardened depth magnitude and may reach ~0.2 mm uncertainty at 1.3 mm nominal depth and ~0.8 mm uncertainty at 3.2mm depth. A case study was discussed to explain a methodology for analyzing a large body of hardened depth information, determination of the measurement error, and calculation of the true heat treat process variation.

  3. Time-dependent 3-D modelling of laser surface heating for the hardening of metallic materials

    Colombo, V.; Mentrelli, A.; Trombetti, T.


    A numerical code for the time-dependent three-dimensional modelling of the laser surface heating for the hardening of metallic materials has been developed by the authors. The temperature-dependence of the thermal properties of the material (stainless steel) is taken into account in the frame of a heating process that doesn’t lead to material melting or evaporation. Calculations have been carried out for various dimensions of the parallelepiped-shaped and of the square-shaped spot of the laser beam, as well as for different scanning velocity and for different levels of the laser source power. Various patterns of the laser spot path have also been studied, including a single-pass hardening pattern, a double-pass hardening pattern with and without overlapping, multiple discontinuous and continuous hardening patterns and spiral hardening patterns. The presented results show how the proposed model can be usefully employed in the prediction of the time-evolution of temperature distribution which arises in the workpiece as a consequence of the laser-workpiece interaction under operating conditions typically encountered in industrial applications of the laser hardening process.

  4. Low temperature tolerance and cold hardening of cacti

    Nobel, P.S.


    Reduced uptake by the chlorenchyma cells of cacti of a stain (neutral red) was used as an indicator of low-temperature damage resulting from cooling stems in the laboratory. Necrosis set in a few degrees below the temperature at which the fraction of cells accumulating stain was reduced by 50%. Coryphantha vivipara, Opuntia polyacantha, and Pediocactus simpsonii, which range to over 3000 m altitude in southern Wyoming, were quite cold tolerant (50% inhibition of staining occurred from -17/sup 0/ to -20/sup 0/C), while O. bigelovii and O. ramosissima, which are restricted to much warmer habitats, were not very cold tolerant (50% inhibition from -4/sup 0/ to -7/sup 0/). Relationships among tissue cold sensitivity, morphological features which protect the stems from low temperatures, and the occurrence of species in progressively colder regions were investigated. Differences in tissue cold sensitivity accounted for the =600 m higher elevational limit of Coryphantha vivipara var. rosea compared to the morphologically similar var. deserti in southern Nevada. In contrast, morphological differences alone could adequately explain the relative northern limits of the columnar cacti Carnegiea gigantea vs. Stenocereus gummosus and the barrel cacti Ferocactus acanthodes vs. F. wislizenii in the southwestern United States, as previously indicated using a computer model. Differences in both morphology and tissue cold sensitivity apparently influenced the relative northern ranges of Lophocereus schottii with respect to the other columnar cacti and F. covillei with respect to the other barrel cacti, as well as the relative elevational range of Denmoza rhodacantha with respect to Trichocereus candicans in northcentral Argentina. Cold hardening in response to decreasing day/night air temperatures was observed for 10 species.


    O. V. Fomin


    Full Text Available Purpose. The paper involves coverage of features and results of the research conducted by the authors to determine the feasibility and establishment of pre-stressed-strained state of freight cars by winding in order to improve their strength characteristics. It is also necessary to present the theoretical justification for the effectiveness of the application of this method for car designs and an appropriate example for the tank-car. Methodology. The conducted study is based on an analysis of known works on the subject, mathematical justification and computer modeling. At the calculations of rolling stock components contemporary conventional techniques were used. Findings. Authors found that the winding method for pre-stressed-strained state is effective and appropriate for use in the construction of railway rolling stock and, in particular freight cars. Freight car designs with the pre-stressed-strained state are characterized by a number of strength advantages, among which there is an improvement of the work on the perception of operational loads and resource conservation. Originality. For the first time it is proposed the improvement of bearing capacity of freight car constructions through the creation of its component in the directed stress-strained state. It is also for the first time proposed the use of distributed external surface hardening by the method of winding to create a pre-stress-strained state of structural components of freight cars. The methods for winding designs of freight cars and their implementation were considered. Practical value. The studies developed a number of technical solutions for improving the design of freight cars and tank-container, which has been patented. Corresponding solutions for the tank-car are partially presented. Practical implementation of such solutions will significantly improve the technical, economic and operational performances of car designs.

  6. Calibration free beam hardening correction for cardiac CT perfusion imaging

    Levi, Jacob; Fahmi, Rachid; Eck, Brendan L.; Fares, Anas; Wu, Hao; Vembar, Mani; Dhanantwari, Amar; Bezerra, Hiram G.; Wilson, David L.


    Myocardial perfusion imaging using CT (MPI-CT) and coronary CTA have the potential to make CT an ideal noninvasive gate-keeper for invasive coronary angiography. However, beam hardening artifacts (BHA) prevent accurate blood flow calculation in MPI-CT. BH Correction (BHC) methods require either energy-sensitive CT, not widely available, or typically a calibration-based method. We developed a calibration-free, automatic BHC (ABHC) method suitable for MPI-CT. The algorithm works with any BHC method and iteratively determines model parameters using proposed BHA-specific cost function. In this work, we use the polynomial BHC extended to three materials. The image is segmented into soft tissue, bone, and iodine images, based on mean HU and temporal enhancement. Forward projections of bone and iodine images are obtained, and in each iteration polynomial correction is applied. Corrections are then back projected and combined to obtain the current iteration's BHC image. This process is iterated until cost is minimized. We evaluate the algorithm on simulated and physical phantom images and on preclinical MPI-CT data. The scans were obtained on a prototype spectral detector CT (SDCT) scanner (Philips Healthcare). Mono-energetic reconstructed images were used as the reference. In the simulated phantom, BH streak artifacts were reduced from 12+/-2HU to 1+/-1HU and cupping was reduced by 81%. Similarly, in physical phantom, BH streak artifacts were reduced from 48+/-6HU to 1+/-5HU and cupping was reduced by 86%. In preclinical MPI-CT images, BHA was reduced from 28+/-6 HU to less than 4+/-4HU at peak enhancement. Results suggest that the algorithm can be used to reduce BHA in conventional CT and improve MPI-CT accuracy.

  7. Hardening transition in a one-dimensional model for ferrogels

    Annunziata, Mario Alberto; Menzel, Andreas M.; Löwen, Hartmut


    We introduce and investigate a coarse-grained model for quasi one-dimensional ferrogels. In our description the magnetic particles are represented by hard spheres with a magnetic dipole moment in their centers. Harmonic springs connecting these spheres mimic the presence of a cross-linked polymer matrix. A special emphasis is put on the coupling of the dipolar orientations to the elastic deformations of the matrix, where a memory effect of the orientations is included. Although the particles are displaced along one spatial direction only, the system already shows rich behavior: as a function of the magnetic dipole moment, we find a phase transition between "soft-elastic" states with finite interparticle separation and finite compressive elastic modulus on the one hand, and "hardened" states with touching particles and therefore diverging compressive elastic modulus on the other hand. Corresponding phase diagrams are derived neglecting thermal fluctuations of the magnetic particles. In addition, we consider a situation in which a spatially homogeneous magnetization is initially imprinted into the material. Depending on the strength of the magneto-mechanical coupling between the dipole orientations and the elastic deformations, the system then relaxes to a uniaxially ferromagnetic, an antiferromagnetic, or a spiral state of magnetization to minimize its energy. One purpose of our work is to provide a largely analytically solvable approach that can provide a benchmark to test future descriptions of higher complexity. From an applied point of view, our results could be exploited, for example, for the construction of novel damping devices of tunable shock absorbance.

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

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


    and times for these essentially different hardening mechanisms are compatible. The effect of the processing history of the steel on the nitrided/nitrocarburized case was investigated by varying the amounts of austenite and martensite through variation of the degree of plastic deformation by tensile strain...

  9. mechanical properties of quench-hardened, martem- pered and ...


    grain boundaries are free of carbides. Works ... steel by the addition of other alloying elements. (Rittel et al ... ganese steel that is sufficiently free of grain boundary ... angles for impact test. Similarly ..... Wear-Resistant Steel Caused by Shot.

  10. Non-vacuum electron-beam carburizing and surface hardening of mild steel

    Bataev, I. A.; Golkovskii, M. G.; Losinskaya, A. A.; Bataev, A. A.; Popelyukh, A. I.; Hassel, T.; Golovin, D. D.


    In this paper, we study the structure, microhardness, and tribological properties of surface layers of mild (0.19% C) steel, which was formed by electron-beam cladding with an iron-graphite powder mixture followed by quenching and tempering. A 1.4 MeV electron beam that was extracted into air was used. Cladding of steel with the iron-graphite mixture at a beam current of 24 and 26 mA formed a hypoeutectic cast iron layer (2.19% C) and a hypereutectoid steel (1.57% C) layer, which were 2.0 and 2.6 mm thick, respectively. The microhardness of the surface-quenched and tempered steel and cast iron layers was 7 and 8 GPa, respectively. Electron-beam quenching of the surface layers of hypoeutectic cast iron was accompanied with multiple cracking. During the quenching of the 1.57% C steel layer, crack formation was not observed. In friction tests against fixed and loose abrasive particles, the surface layers of hypereutectoid steel and hypoeutectic cast iron that were produced by electron-beam cladding and quenching had lower wear rates than mild steel after pack carburizing, quenching, and tempering. In the sliding wear tests, the cast iron clad layer, which was subjected to electron-beam quenching and tempering, exhibited the highest wear resistance. Electron-beam treatment can be used to harden local areas of large workpieces. It is reasonable to treat clad layers of high-carbon steel with electron-beam quenching and tempering. To prevent multiple cracking, white cast iron layers should not be quenched.

  11. Direct observation of Lomer-Cottrell locks during strain hardening in nanocrystalline nickel by in situ TEM.

    Lee, Joon Hwan; Holland, Troy B; Mukherjee, Amiya K; Zhang, Xinghang; Wang, Haiyan


    Strain hardening capability is critical for metallic materials to achieve high ductility during plastic deformation. A majority of nanocrystalline metals, however, have inherently low work hardening capability with few exceptions. Interpretations on work hardening mechanisms in nanocrystalline metals are still controversial due to the lack of in situ experimental evidence. Here we report, by using an in situ transmission electron microscope nanoindentation tool, the direct observation of dynamic work hardening event in nanocrystalline nickel. During strain hardening stage, abundant Lomer-Cottrell (L-C) locks formed both within nanograins and against twin boundaries. Two major mechanisms were identified during interactions between L-C locks and twin boundaries. Quantitative nanoindentation experiments recorded show an increase of yield strength from 1.64 to 2.29 GPa during multiple loading-unloading cycles. This study provides both the evidence to explain the roots of work hardening at small length scales and the insight for future design of ductile nanocrystalline metals.

  12. Influence of diffusion resistance in oxidative heat-hardening of char/tar briquetes

    Prasad, K.B.S.; Venkatesham, M.


    Char/tar briquetes can be made sufficiently strong and completely smokeless by heating in the presence of oxygen. It is recognized that tar is converted into a resinous matter during this process and the rate at which this happens seems to be controlled by oxygen diffusion into the briquete. A model has been developed, considering the tar to envelop the char particles as a thin stationary layer. Computer simulation of briquetes having a binder percentage varying linearly in a direction parallel to the cylindrical axis has shown that briquetes with the smaller amount of tar near the end of the cylinder give the better average conversion, implying that such briquetes are the strongest. This has been verified experimentally using briquetes having a linearly varying tar content. The model however is a highly simplified representation of a complicated phenomenon and may need substantial modification before firmer conclusions are drawn.

  13. Interstitial Hardening of Stainless Steel for Enhanced Corrosion Resistance for Naval Applications


    prepared: one as-machined and six polished to varying smoothness using the following final polishing media : P400, P800, P1500, and P2500 SiC grit paper; and...The nitrogen- rich case depth was strongly dependent on temperature, increasing from -1 micron to -15 microns as the nitriding temperature was...carbon- rich region below the nitrogen- rich region at the near-surface regions of these samples. Because of the heavy machining and subsequent

  14. Interstitial Hardening of Stainless Steel for Enhanced Corrosion Resistance for Naval Applications


    achieved at high chemical activities of nitrogen (achieved by using ammonia (NH3) as the nitrogen source) but this led to severe surface cracking...interstitial solutes enter the austenite lattice simultaneously. A straightforward thermodynamically based numerical model was developed that explained...34simple" carburization and nitridation depth profiles, and also explained the deeper carbon profiles, based on the effects of carbon on the chemical

  15. Mechanisms of hardening, wear and corrosion improvement of 316 L stainless steel by low energy high current pulsed electron beam surface treatment

    Zou, J.X. [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, UMR-CNRS 7078), Universite Paul Verlaine - Metz, Ile du Saulcy, 57045 Metz (France); Shanghai Engineering Research Center of Mg Materials and Applications and School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Key Laboratory of Materials Modification by Laser, Electron and Ion beams, Dalian University of Technology, Dalian 116024 (China); Zhang, K.M. [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Hao, S.Z.; Dong, C. [Key Laboratory of Materials Modification by Laser, Electron and Ion beams, Dalian University of Technology, Dalian 116024 (China); Grosdidier, T., E-mail: thierry.grosdidier@univ-metz.f [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, UMR-CNRS 7078), Universite Paul Verlaine - Metz, Ile du Saulcy, 57045 Metz (France); Key Laboratory of Materials Modification by Laser, Electron and Ion beams, Dalian University of Technology, Dalian 116024 (China)


    The mechanisms of corrosion and wear improvements by low energy high current pulsed electron beam (LEHCPEB) have been investigated for an AISI 316 L steel. Selective purification followed by epitaxial growth occurred in the top surface melted layer (2-3 {mu}m thick) that was softened by tensile stresses and, to a much lower extent, by lower efficiency of MnS precipitation hardening. Electrochemical impedance spectroscopy and potentiodynamic polarization analyses used to model the corrosion behavior revealed that, while craters initiated at MnS inclusions initially served as pitting sites, the resistance was increased by 3 orders of magnitude after sufficient number of pulses by the formation of a homogeneous covering layer. The wear resistance was effectively improved by sub-surface (over 100 {mu}m) work hardening associated with the combine effect of the quasi-static thermal stress and the thermal stress waves. The overall results demonstrate the potential of the LEHCPEB technique for improving concomitantly the corrosion and wear performances of metallic materials.

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

    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

  17. Radiation Hardened Electronics Destined For Severe Nuclear Reactor Environments

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


    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

  18. Effect of strain rate on bake hardening response of BH220 steel

    Das Anindya


    Full Text Available This study aims at understanding the bake hardening ability of ultra low carbon BH220 steel at different strain rates. The as-received material has been pre-strained to four different levels and then deformed in tension under (a as pre-strained state and (b after baking at 170 ∘C for 20 minutes, at three different strain rates of 0.001, 0.1 and 100/s. In both the conditions, yield stress increased with pre-strain and strain rate, but bake hardening ability was found to decrease when strain rate was increased. The strain rate sensitivity of the material was also found to decrease with bake hardening. Generation of dislocation forests and their subsequent immobility during baking treatment enables them to act as long range obstacles during further deformation. At higher strain rates, less amount of dislocations are produced which can interact with themselves and produce hardening, because of which bake hardening ability and the strain rate drops. A dislocation based strengthening model, as proposed by Larour et al. 2011 [7], was used to predict the yield stress values obtained at different conditions. The equation produced excellent co-relation with the experimental data.

  19. Cognitive work hardening: a return-to-work intervention for people with depression.

    Wisenthal, Adeena; Krupa, Terry


    Mental health claims in the workplace are rising, particularly those due to depression. Associated with this is an increase in disability costs for the employer and the disability insurer, but even more important is the human suffering that results. While treatments are available for the depression there is a gap in interventions that specifically target return-to-work preparation. This paper presents cognitive work hardening, a treatment intervention that can bridge this gap by addressing the unique functional issues inherent in depression with a view to increasing return-to-work success. Cognitive work hardening applies the proven principles of classical work hardening (which has typically been applied to people with physical injuries) to the mental health domain. This paper explains how the occupational therapy principle of occupation and the core competency, enablement, are utilized and applied in cognitive work hardening. Key skills of the occupational therapist are also discussed. In addition, the paper considers the relationship of cognitive work hardening to recovery and mental illness, and the role it plays among workplace-based return-to-work interventions in the current movement toward non-clinical return-to-work interventions.

  20. Dilatometric investigations of phase transformations at heating and cooling of hardened, unalloyed, high-carbon steels

    J. Pacyna


    Full Text Available Purpose: The reason for writing this paper was to describe the kinetics of phase transformations during continuous heating from hardened state and subsequent cooling of unalloyed high carbon steel.Design/methodology/approach: Dilatometric investigations were performed using a DT 1000 dilatometer of a French company Adamel. Samples after quenching and quenching and sub-quenching in liquid nitrogen (-196 °C were heated up 700 °C at the rate of 0.05 °C/s and subsequent cooled to room temperature at the rate of 0.05 °C/s.Findings: Regardless of heating the hardened high-carbon steel to 700 °C, a small fraction of the retained austenite remained in its structure, and was changing into fresh martensite only during cooling in the temperature range: 280°C-170°C.Research limitations/implications: Schematic presentation of the differential curve of tempering of the hardened high-carbon, unalloyed steel illustrating the phase transformations occurring during heating from hardened state.Practical implications: An observation, that a small fraction of the retained austenite remained in the structure of tempered high-carbon steel, indicates that even unalloyed steel should be tempered two times.Originality/value: Detailed descriptions of kinetics phase transformations during heating from hardened state of unalloyed high carbon steel.

  1. Beam hardening correction using iterative total variation (ITV)-based algorithm in CBCT reconstruction

    Seo, Chang-Woo; Cha, Bo Kyung; Jeon, Sungchae; Huh, Young [Converged Medical Device Research Center, Advanced Medical Device Research Division, KERI, Gyeonggido 426-910 (Korea, Republic of)


    Recently, beam hardening reduction is required to produce high-quality reconstructions of X-ray cone-beam computed tomography (CBCT) system for medical applications. This paper introduces the iterative total variation (ITV) for filtered-backprojection suffering from the serious beam hardening problems. Feldkamp, Davis, and Kress (FDK) reconstruction algorithm for CBCT system is widely used reconstruction technique. FDK reconstruction algorithm could be realized by generating the weighted projection data, filtering the projection images, and back-projecting the filtered projection data into the volume. However, FDK algorithm suffers from the beam hardening artifacts by X-ray attenuation coefficients. Recently, total variation (TV) method for compressed sensing (CS) has been particularly useful in exploiting the prior knowledge of minimal variation in the X-ray attenuation characteristics across object or human body. But a practical implementation of this method still remains a challenge. The main problem is the iterative nature of solving the TV-based CS formulation, which generally requires multiple iterations of forward and backward projections of a large dataset in clinically or industrially feasible time frame. In this paper, we propose ITV method after FDK reconstruction for reducing the beam hardening artifacts. The beam hardening problems are reduced by the ITV method to promote sparsity inherent in the X-ray attenuation characteristics. (authors)

  2. Microstructure, Tensile Properties and Work Hardening Behavior of GTA-Welded Dual-Phase Steels

    Ashrafi, H.; Shamanian, M.; Emadi, R.; Saeidi, N.


    In the present study, microstructure, tensile properties and work hardening behavior of a DP700 steel after gas tungsten arc welding were investigated. Formation of bainite in the fusion zone resulted in a hardness increase compared to that for the base metal (BM), whereas tempering of the pre-existing martensite in the subcritical heat-affected zone (HAZ) led to softening. The GTA-welded joint exhibited a continuous yielding behavior and a yield strength close to that for the BM, while its ultimate tensile strength and total elongation were lower than those for the BM owing to the formation of soft zone in the HAZ. A joint efficiency of about 81% was obtained for the GTA-welded joint, and it failed in the softened HAZ. Analysis of work hardening based on the Kocks-Mecking approach showed one stage of hardening behavior corresponding to the stage III for both the DP700 BM and welded sample. It was also revealed that the DP700 BM has larger values of work hardening exponent and magnitude of work hardening compared with the welded sample. Analysis of fractured surfaces showed that the dominant fracture mode for both the DP700 BM and welded joint was ductile.

  3. Effects of TEA·HCl hardening accelerator on the workability of cement-based materials

    Pan, Wenhao; Ding, Zhaoyang; Chen, Yanwen


    The aim of the test is to research the influence rules of TEA·HCl on the workability of cement paste and concrete. Based on the features of the new hardening accelerator, an experimental analysis system were established through different dosages of hardening accelerator, and the feasibility of such accelerator to satisfy the need of practical engineering was verified. The results show that adding of the hardening accelerator can accelerate the cement hydration, and what’s more, when the dosage was 0.04%, the setting time was the shortest while the initial setting time and final setting time were 130 min and 180 min, respectively. The initial fluidity of cement paste of adding accelerator was roughly equivalent compared with that of blank. After 30 min, fluidity loss would decrease with the dosage increasing, but fluidity may increase. The application of the hardening accelerator can make the early workability of concrete enhance, especially the slump loss of 30 min can improve more significantly. The bleeding rate of concrete significantly decreases after adding TEA·HCl. The conclusion is that the new hardening accelerator can meet the need of the workability of cement-based materials in the optimum dosage range.

  4. Influence of copper on effects of precipitation hardening of ductile cast iron

    T. Szykowny


    Full Text Available Ductile cast iron with different copper content was precipitation hardened. Cast iron with 0.48 % Cu content was ferritized. That operation was ended with rapid quenching, and then aged. Cast iron with 1.27 or 2.10 % Cu content was spheroid annealing. After rapid quenching cast iron was aged. Not alloy cast iron with small copper content (0.04 % had a chemical composition similar to cast iron with 0.48 % Cu content. Such copper was for tests in order to obtain an answer for the question whether only copper is responsible for precipitate hardening effects. Metalographic microscope tests (LM, SEM of mechanical properties (Rm, Rp, A5, Z, K and H and x-ray diffraction tests were performed. It has been stated, that hardening of ferretic cast iron let to obtain tensile strength above 500 MPa and elongation approx. 23 %.Precipitation hardening of ductile cast iron efficiently compensates reducing of hardening caused by partial graphitization and spheroidization of pearlitic cementite.

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

    Véronique Josette Essa’a


    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.

  6. Beam hardening correction for interior tomography based on exponential formed model and radon inversion transform

    Chen, Siyu; Zhang, Hanming; Li, Lei; Xi, Xiaoqi; Han, Yu; Yan, Bin


    X-ray computed tomography (CT) has been extensively applied in industrial non-destructive testing (NDT). However, in practical applications, the X-ray beam polychromaticity often results in beam hardening problems for image reconstruction. The beam hardening artifacts, which manifested as cupping, streaks and flares, not only debase the image quality, but also disturb the subsequent analyses. Unfortunately, conventional CT scanning requires that the scanned object is completely covered by the field of view (FOV), the state-of-art beam hardening correction methods only consider the ideal scanning configuration, and often suffer problems for interior tomography due to the projection truncation. Aiming at this problem, this paper proposed a beam hardening correction method based on radon inversion transform for interior tomography. Experimental results show that, compared to the conventional correction algorithms, the proposed approach has achieved excellent performance in both beam hardening artifacts reduction and truncation artifacts suppression. Therefore, the presented method has vitally theoretic and practicable meaning in artifacts correction of industrial CT.

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

    Li, Gang; Zank, Gary; Chen, Yao


    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...

  8. Distortion Analysis in the Manufacturing of Cold-Drawn and Induction-Hardened Components

    Hirsch, Thomas Georg Karl; da Silva Rocha, Alexandre; Menezes Nunes, Rafael


    In this investigation, a design of experiments analysis of distortion for a typical manufacturing process involving pre-straightening, cold drawing, and induction hardening of 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 batch influence, the combined drawing process itself with two different drawing angles and two different polishing and straightening (P.S.) angles, a stress relief treatment which was applied to a part of the samples, and finally induction hardening with two different surface hardening depths. Main and statistically significant effects on the distortion of the induction-hardened samples were found to be in this order: first, the interaction between the drawing angle and batch, then the interaction between drawing angles, and finally drawing angle and induction hardened layer. 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.

  9. New Inner Canalizing Technology with Vapour Hardening Material

    Ďurove Juraj


    Full Text Available The Liner is a composite sandwich construction using multiple layers of Owens Corning Advantex extra corrosion resistant fiberglass, forming a complex unidirectional reinforced structure. This construction achives an unmatched strenght permitting a thinner wall and therefore less reduction of the original diameter. The ring stiffness is very important. The unique design of the Liner gives a very high E-Moduls performance of 10.000 MPa which is unmatched by any other liner on the market. The longitudial reinforcement ensures complete stability troughout the length and prevent any elongation caused by the installation process. The Liner is constructed using extra corrosion resistant fiberglass. The inside of the liner is covered with a polyester veil rich of resin, forming a very smooth and glass-hard surface. In Combination with the unique post-curing at 110 °C, a very high resistance to abrasion and chemicals is achieved.

  10. Plastic responses to four environmental stresses and cross-resistance in a laboratory population of Drosophila melanogaster

    Bubliy, Oleg A; Kristensen, Torsten Nygård; Kellermann, Vanessa


    and desiccation hardening as well as acclimation to starvation had a cost under non-stressful conditions leading to reduced longevity. Cold acclimation did not affect longevity, although its effect was difficult to estimate precisely: during pretreatment at a low temperature, biological ageing of the flies might...... such as reduction of metabolic rate and accumulation of energy reserves might be involved. 6. The lack of cross-resistance induced by acclimation ⁄ hardening treatments suggests that in an environment with multiple stresses, evolution of shared protective systems associated with plastic responses may be constrained.......1. Acclimation or hardening to one stress in arthropods can lead to a plastic response, which confers increased resistance to other stresses. Such cross-resistance may indicate shared physiological resistance mechanisms and a possibility of joint evolution for resistance traits. 2. In this study...

  11. Design of a total-dose radiation hardened monolithic CMOS DC-DC boost converter

    Liu Zhi; Yu Hongbo; Liu Youbao [Xi' an Institute of Microelectronics Technology, Xi' an 710054 (China); Ning Hongying, E-mail: [Xi' an University of Technology, Xi' an 710048 (China)


    This paper presents the design and implementation of a monolithic CMOS DC-DC boost converter that is hardened for total dose radiation. In order to improve its radiation tolerant abilities, circuit-level and device-level RHBD (radiation-hardening by design) techniques were employed. Adaptive slope compensation was used to improve the inherent instability. The H-gate MOS transistors, annular gate MOS transistors and guard rings were applied to reduce the impact of total ionizing dose. A boost converter was fabricated by a standard commercial 0.35 {mu}m CMOS process. The hardened design converter can work properly in a wide range of total dose radiation environments, with increasing total dose radiation. The efficiency is not as strongly affected by the total dose radiation and so does the leakage performance. (semiconductor integrated circuits)

  12. Temperature Effects on the Tensile Properties of Precipitation-Hardened Al-Mg-Cu-Si Alloys

    J.B. Ferguson


    Full Text Available Because the mechanical performance of precipitation-hardened alloys can be significantly altered with temperature changes, understanding and predicting the effects of temperatures on various mechanical properties for these alloys are important. In the present work, an analytical model has been developed to predict the elastic modulus, the yield stress, the failure stress, and the failure strain taking into consideration the effect of temperatures for precipitation-hardenable Al-Mg-Cu-Si Alloys (Al-A319 alloys. In addition, other important mechanical properties of Al-A319 alloys including the strain hardening exponent, the strength coefficient, and the ductility parameter can be estimated using the current model. It is demonstrated that the prediction results based on the proposed model are in good agreement with those obtained experimentally in Al-A319 alloys in the as-cast condition and after W and T7 heat treatments.

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

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


    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.

  14. Effect of Sc on Precipitation Hardening of AlSi6Mg Alloy


    The effect of Sc on precipitation hardening of AlSi6Mg was studied. Zr was previously reported that it increased the effectiveness of Sc in wrought aluminum in many areas so Zr was also used together with Sc in this study.Different levels of Sc and Zr additions were added to AlSi6Mg before casting in the permanent mold. The samples were precipitation hardened at different aging temperatures and for various aging time before testing for tensile strength and hardness. It was found that Sc addition into Al6SiMg can change its response to age hardening. Additions of Sc and Sc with Zr increased both yield strength and hardness for both aging temperatures. In addition, Sc was found to modify eutectic Si to obtain fibrous morphology. This effect of Sc on eutectic silicon modification has never been reported before.




    Full Text Available Three types of zirconium base alloy were evaluated to study how their work hardening behavior is affected by alloy composition. Repeated-tensile tests (5% elongation at each test were performed at room temperature at a strain rate of 1.7 × 10−3 s−1 for the alloys, which were initially controlled for their microstructure and texture. After considering the yield strength and work hardening exponent (n variations, it was found that the work hardening behavior of the zirconium base alloys was affected more by the Nb content than the Sn content. The facture mode during the repeated tensile test was followed by the slip deformation of the zirconium structure from the texture and microstructural analysis.

  16. Embrittlement of irradiated F82H in the absence of irradiation hardening

    Klueh, R.L. [Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States)], E-mail:; Shiba, K. [Japan Atomic Energy Agency, Toki-Mura, Ibaraki (Japan); Sokolov, M.A. [Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States)


    Neutron irradiation of 7-12% Cr ferritic/martensitic steels below 425-450 deg. C produces microstructural defects and precipitation that cause an increase in yield stress. This irradiation hardening causes embrittlement, which is observed in a Charpy impact or fracture toughness test as an increase in the ductile-brittle transition temperature. Based on observations that show little change in strength in steels irradiated above 425-450 deg. C, the general conclusion has been that no embrittlement occurs above these temperatures. In a recent study of F82H steel, significant embrittlement was observed after irradiation at 500 deg. C, but no hardening occurred. This embrittlement is apparently due to irradiation-accelerated Laves-phase precipitation. Observations of the embrittlement of F82H in the absence of irradiation hardening have been examined and analyzed with thermal-aging studies and computational thermodynamics calculations to illuminate and understand the embrittlement during irradiation.

  17. Densification and strain hardening of a metallic glass under tension at room temperature.

    Wang, Z T; Pan, J; Li, Y; Schuh, C A


    The deformation of metallic glasses involves two competing processes: a disordering process involving dilatation, free volume accumulation, and softening, and a relaxation process involving diffusional ordering and densification. For metallic glasses at room temperature and under uniaxial loading, disordering usually dominates, and the glass can fail catastrophically as the softening process runs away in a localized mode. Here we demonstrate conditions where the opposite, unexpected, situation occurs: the densifying process dominates, resulting in stable plastic deformation and work hardening at room temperature. We report densification and hardening during deformation in a Zr-based glass under multiaxial loading, in a notched tensile geometry. The effect is driven by stress-enhanced diffusional relaxation, and is attended by a reduction in exothermic heat and hardening signatures similar to those observed in the classical thermal relaxation of glasses. The result is significant, stable, plastic, extensional flow in metallic glasses, which suggest a possibility of designing tough glasses based on their flow properties.

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

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


    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. Influence and Analysis of Concentrate Degree of Plasma Arc for Heat Process of Hardening Treatment

    WANG Shuo-gui; YAN Hong-ri


    According to the practicable model of the plasma arc surface quench, the influence law of the heat process、cooling course、 temperature field about surface quench treatment by plasma arc due to the concentrate degree of plasma arc heat source are discussed in this paper. It shows that the concentrate degree of plasma arc heat source can change the width of the hardening zone and can not change the maximum harden depth. With the increase of the concentrate degree, the area of the heat influence zone is decreased and its shape is narrowed after the heat source. Relative to cooling rate, the influence of the heat source concentrate degree for heat absorption is bigger. The correctness of the practical model are proved with experimental results for quench hardening of 45# steel by plasma arc.

  20. Influence and Analysis of Concentrate Degree of Plasma Arc for Heat Process of Hardening Treatment

    WANGShuo-gui; YANHong-ri


    According to the practicable model of the plasma arc surtace quench, the influence law ot me heat process, cooling course, temperature field about surface quench treatment by plasma arc due to the concentrate degree of plasma arc heat source are discussed in this paper. It shows that the concentrate degree of plasma arc heat source can change the width of the hardening zone and can not change the maximum harden depth. With the increase of the concentrate degree, the area of the heat influence zone is decreased and its shape is narrowed after the heat source. Relative to cooling rate, the influence of the heat source concentrate degree for heat absorption is bigger. The correctness of the practical model are proved with experimental results for quench hardening of 45# steel by plasma arc.

  1. Intense two-cycle laser pulses induce time-dependent bond hardening in a polyatomic molecule.

    Dota, K; Garg, M; Tiwari, A K; Dharmadhikari, J A; Dharmadhikari, A K; Mathur, D


    A time-dependent bond-hardening process is discovered in a polyatomic molecule (tetramethyl silane, TMS) using few-cycle pulses of intense 800 nm light. In conventional mass spectrometry, symmetrical molecules such as TMS do not exhibit a prominent molecular ion (TMS(+)) as unimolecular dissociation into [Si(CH(3))(3)](+) proceeds very fast. Under a strong field and few-cycle conditions, this dissociation channel is defeated by time-dependent bond hardening: a field-induced potential well is created in the TMS(+) potential energy curve that effectively traps a wave packet. The time dependence of this bond-hardening process is verified using longer-duration (≥100 fs) pulses; the relatively slower falloff of optical field in such pulses allows the initially trapped wave packet to leak out, thereby rendering TMS(+) unstable once again.

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

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


    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.

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

    Bashchenko, Lyudmila P., E-mail:; Gromov, Viktor E., E-mail:; Budovskikh, Evgenii A., E-mail:; Soskova, Nina A., E-mail: [Siberian State Industrial University, Novokuznetsk, 654007 (Russian Federation); Ivanov, Yurii F., E-mail: [Institute of High Current Electronics SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation)


    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.

  4. Sheet metal hardening curve determined by laminated sample and its adaptability to sheet forming processes


    The hardening curve for sheet metal can be determined from the load-displacement curve of tensilespecimen with rectangular cross-section. Therefore, uniaxial compression test on cylinder specimen made from laminated sample is put forward. Considering the influence of anisotropy on hardening properties and the stress state in popular forming process, plane strain compression test on cubic specimen made from laminated sample was advanced. Results show that the deformation range of hardening curves obtained from the presented methods is wide, which meets the need for the application in sheet metal forming processes. In view of the characteristics of methods presented in the paper and the stress strain state of various forming processes, the adaptability of the two methods presented in this paper is given.

  5. Effect of bentonite addition on residual strength of microwave-hardened waterglass-containing moulding sands

    M. Stachowicz


    Full Text Available The paper presents results of a preliminary research of the effect of bentonite addition on residual strength of microwave-hardened moulding sands, containing sodium waterglass. Strength was determined at ambient temperature, on cylindrical specimens baked in an oven. Moulding sands for examinations were based on high-silica sand with addition of 2.5 % of non-modified, domestic-made waterglass grade 145. The prepared standard cylindrical specimens were hardened using the innovative microwave heating process and next baked for 30 minutes at temperatures between 100 and 1200 °C. Strength parameters of the specimens were determined on the specimens cooled- down to ambient temperature. The obtained results were compared with literature data to evaluate the effect of the applied hardening method and of the special additive on residual strength as a function of baking temperature. A favourable effect was found of both the innovative heating process and the applied bentonite addition.

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

    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: [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)


    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.

  7. Microstructure Changes in Hardened Cement Paste after Freezing – Thawing Cycles

    Gintautas SKRIPKIŪNAS


    Full Text Available This article analyses the results of the freezing – thawing with deicing salt test where changes in the microstructure of the surface layer in contact with aggressive environment of hardened cement paste produced with and without sodium silicate (hereinafter NTS admixture were observed after freeze-thaw cycles in the presence of calcium chloride. After 56 cycles of freezing – thawing with deicing salt test micro-cracks and cavities were observed in the microstructure of the surface layer of hardened cement paste with and without NTS admixture. In the case of hardened cement paste with NTS admixture changes in the microstructure of the surface layer are less prominent: the number and size of cavities and micro-cracks are smaller. The test revealed that compressive stress, which before freezing – thawing with deicing salt test was very similar in hardened cement paste with and without NTS admixture (85.4 MPa and 82.8 MPa respectively, changed after 56 cycles of freezing – thawing with deicing salt test as follows: reduced by 39.5 % in concrete without NTS admixture and increased slightly (2.5 % in hardened cement paste with NTS admixture. Based on the test results the authors arrived at the conclusion that sodium silicate solution can be effectively used to extend the useful life of hardened cement paste exposed to freeze-thaw cycles and affected by CaCl2.DOI:

  8. Radiation and chemical crosslinking promote strain hardening behavior and molecular alignment in ultra high molecular weight polyethylene during multi-axial loading conditions.

    Kurtz, S M; Pruitt, L A; Jewett, C W; Foulds, J R; Edidin, A A


    The mechanical behavior and evolution of crystalline morphology during large deformation of eight types of virgin and crosslinked ultra high molecular weight polyethylene (UHMWPE) were studied using the small punch test and transmission electron microscopy (TEM). We investigated the hypothesis that both radiation and chemical crosslinking hinder molecular mobility at large deformations, and hence promote strain hardening and molecular alignment during the multiaxial loading of the small punch test. Chemical crosslinking of UHMWPE was performed using 0.25% dicumyl peroxide (GHR 8110, GUR 1020 and 1050), and radiation crosslinking was performed using 150 kGy of electron beam radiation (GUR 1150). Crosslinking increased the ultimate load at failure and decreased the ultimate displacement of the polyethylenes during the small punch test. Crosslinking also increased the near-ultimate hardening behavior of the polyethylenes. Transmission electron microscopy was used to characterize the crystalline morphology of the bulk material, undeformed regions of the small punch test specimens, and deformed regions of the specimens oriented perpendicular and parallel to the punch direction. In contrast with the virgin polyethylenes, which showed only subtle evidence of lamellar alignment, the crosslinked polyethylenes exhibited enhanced crystalline lamellae orientation after the small punch test, predominantly in the direction parallel to the punch direction or deformation axis. Thus, the results of this study support the hypothesis that crosslinking promotes strain hardening during multiaxial loading because of increased resistance to molecular mobility at large deformations effected by molecular alignment. The data also illustrate the sensitivity of large deformation mechanical behavior and crystalline morphology to the method of crosslinking and resin of polyethylene.

  9. Electrolytic surface hardening of steel,castiron and aluminium-bronze

    Suhas Keshav Paknik a r


    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.

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

    Svetlana Nestorovic


    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.

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

    Dou, Suguang; Jensen, Jakob Søndergaard


    /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......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...

  12. Improvement of a chain-hardening furnace by computational fluid dynamics (CFD) simulation

    Sala, J.M.; Eguia, J.J. [E.T.S. Ingenieros Industriales, Bilbao (Spain); Gonzalez, L.M. Lopez; Vicuna, J.E.; Juarez, M.C.; Domenech, J. [Universidad de La Rioja, Escuela Tecnica Superior de Ingenieria Industrial de Logrono, Logrono (La Rioja) (Spain); Miguez, J.L. [E.T.S. de Ingenieros Industriales, Lagoas-Marcosende, Vigo (Spain)


    Hardening heat-treatment is an important operation in the fabrication of large chains for both the shipping industry and anchorage of offshore oil-platforms. This paper presents the outcome of an investigation that led to the introduction of modifications in a hardening furnace resulting in a substantial improvement and largely eliminating the problem of gradual cooling of the chain before immersion in the water-quenching tank. Comparing this with the present operating conditions, it can be concluded that redirecting the gas flow increases the gas temperature in the lower part of the furnace, which changes the chain's temperature-distribution accordingly. (Author)

  13. Induction hardening treatment and simulation for a grey cast iron used in engine cylinder liners

    Castellanos-Leal, E. L.; Miranda, D. A.; Coy, A. E.; Barrero, J. G.; González, J. A.; Vesga Rueda, O. P.


    In this research, a technical study of induction hardening in a grey cast iron used in engine cylinder liners manufactured by LAVCO Ltda., a Colombian foundry company, was carried out. Metallurgical parameters such as austenitization temperature, cooling rate, and quenching severity were determined. These factors are exclusively dependent on chemical composition and initial microstructure of grey cast iron. Simulations of induction heating through finite elements method were performed and, the most appropriate experimental conditions to achieve the critical transformation temperature was evaluated to reach a proper surface hardening on the piece. Preliminary results revealed an excellent approximation between simulation and heating test performed with a full bridge inverter voltage adapted with local technology.

  14. Work Hardening Behavior and Stability of Retained Austenite for Quenched and Partitioned Steels

    Cun-yu WANG; Ying CHANG; Jie YANG; Wen-quan CAO; Han DONG; Yi-de WANG


    Both microstructure and mechanical properties of low alloy steels treated by quenching and partitioning (Q&P)process were examined.The mixed microstructure of martensite and large-fractioned retained austenite (about 27�3%)was characterized and analyzed,excellent combinations of total elongation of 1 9% and tensile strength of 1 835 MPa were obtained,and three-stage work hardening behavior was demonstrated during tensile test.The en-hanced mechanical properties and work hardening behavior were explained based on the transformation-induced plas-ticity effect of large-fractioned austenite.

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

    Juristyarini, Pramitha


    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.

  16. Re-hardening of hadron transverse mass spectra in relativistic heavy-ion collisions

    P K Sahu; N Otuka; M Isse; Y Nara; A Ohnishi


    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.

  17. Solid solution hardening of molecular crystals: tautomeric polymorphs of omeprazole.

    Mishra, Manish Kumar; Ramamurty, Upadrasta; Desiraju, Gautam R


    In the context of processing of molecular solids, especially pharmaceuticals, hardness is an important property that often determines the manufacturing steps employed. Through nanoindentation studies on a series of omeprazole polymorphs, in which the proportions of the 5- and 6-methoxy tautomers vary systematically, we demonstrate that solid-solution strengthening can be effectively employed to engineer the hardness of organic solids. High hardness can be attained by increasing lattice resistance to shear sliding of molecular layers during plastic deformation.

  18. Study on microstructures and work hardening behavior of ferrite-martensite dual-phase steels with high-content martensite

    Xiurong Zuo


    Full Text Available A kind of medium-carbon low-alloy dual-phase steels with high-content martensite produced by intercritical annealing at 785-830 ºC for 10-50 minutes were studied in aspect of microstructures and work hardening behavior using SEM and tensile testing machine. The experimental results showed that the work hardening of the studied steels obeyed the two-stage work hardening mechanism, whose work hardening exponent of the first stage was higher than that of the second stage. The work hardening exponent increased with increasing the intercritical annealing temperature and time. For series A steel intercritically annealed at 785 ºC with starting microstructure of ferrite plus pearlite, austenite nucleated at the pearlite colonies, so the holding time of only 50 minutes can increase the work hardening exponent obviously. For series B steel with starting microstructure of martensite, austenite nucleated at lath interfaces, lath colony boundaries of primary martensite and carbides, accelerating the formation of austenite, so holding time for 30 minutes made the work hardening exponent increase obviously. High work hardening rate during initial plastic deformation (<0.5% strain was observed.

  19. Application of standard end-quench test to structural steel with elevated carbon content at low hardenability

    Gliner, R. E.; Vybornov, V. V.


    Special features of the test of plain steel with elevated carbon content for hardenability, which is used in the production of gears instead carburizing alloy steel, are considered. It is shown that it is possible and effective to use computer simulation of the hardenability detectable by testing of this class of steel by the method of end quenching with allowance for the chemical composition.

  20. Effect of Carburizing and Hardening Temperature on the Endurance of Forming Dies from Steel R6M5

    Stepankin, I. N.; Ken'ko, V. M.; Boiko, A. A.


    Results of a study of the effect of carburizing of the forming surfaces of cold upset dies from high-speed steel R6M5 and of the hardening temperature on the structure and properties of the dies are presented. It is shown that the hardness and endurance of the carburized tools can be raised by hardening from lower temperatures.

  1. Non-vacuum electron-beam carburizing and surface hardening of mild steel

    Bataev, I.A., E-mail: [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation); Golkovskii, M.G., E-mail: [Budker Institute of Nuclear Physics SB RAS, Lavrentieva Prospect 11, 630090 Novosibirsk (Russian Federation); Losinskaya, A.A., E-mail: [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation); Bataev, A.A., E-mail: [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation); Popelyukh, A.I., E-mail: [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation); Hassel, T., E-mail: [Leibniz University, Welfengarten 1, 30167 Hannover (Germany); Golovin, D.D., E-mail: [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation)


    Highlights: • Steel specimens were carburized by non-vacuum electron-beam cladding. • The depth of the clad layers reached 2.6 mm. • The cladding rate was 1.8 m{sup 2}/h, the quenching rate 12.6 m{sup 2}/h. • The microhardness of the quenched and tempered layers reached 8 GPa. - Abstract: In this paper, we study the structure, microhardness, and tribological properties of surface layers of mild (0.19% C) steel, which was formed by electron-beam cladding with an iron–graphite powder mixture followed by quenching and tempering. A 1.4 MeV electron beam that was extracted into air was used. Cladding of steel with the iron–graphite mixture at a beam current of 24 and 26 mA formed a hypoeutectic cast iron layer (2.19% C) and a hypereutectoid steel (1.57% C) layer, which were 2.0 and 2.6 mm thick, respectively. The microhardness of the surface-quenched and tempered steel and cast iron layers was 7 and 8 GPa, respectively. Electron-beam quenching of the surface layers of hypoeutectic cast iron was accompanied with multiple cracking. During the quenching of the 1.57% C steel layer, crack formation was not observed. In friction tests against fixed and loose abrasive particles, the surface layers of hypereutectoid steel and hypoeutectic cast iron that were produced by electron-beam cladding and quenching had lower wear rates than mild steel after pack carburizing, quenching, and tempering. In the sliding wear tests, the cast iron clad layer, which was subjected to electron-beam quenching and tempering, exhibited the highest wear resistance. Electron-beam treatment can be used to harden local areas of large workpieces. It is reasonable to treat clad layers of high-carbon steel with electron-beam quenching and tempering. To prevent multiple cracking, white cast iron layers should not be quenched.

  2. Modeling the triaxial behavior of riverbed and blasted quarried rockfill materials using hardening soil model

    N.P. Honkanadavar


    Full Text Available Riverbed modeled rockfill material from Noa Dehing dam project, Arunachal Pradesh, India and blasted quarried modeled rockfill material from Kol dam project, Himachal Pradesh, India were considered for this research. Riverbed rockfill material is rounded to sub-rounded and quarried rockfill material is angular to sub-angular in shape. Prototype rockfill materials were modeled into maximum particle size (dmax of 4.75 mm, 10 mm, 19 mm, 25 mm, 50 mm and 80 mm for testing in the laboratory. Consolidated drained triaxial tests were conducted on modeled rockfill materials with a specimen size of 381 mm in diameter and 813 mm in height to study the stress–strain–volume change behavior for both rockfill materials. Index properties, i.e. uncompacted void content (UVC and uniaxial compressive strength (UCS, were determined for both rockfill materials in association with material parameters. An elastoplastic hardening soil (HS constitutive model was used to predict the behavior of modeled rockfill materials. Comparing the predicted and observed stress–strain–volume change behavior, it is found that both observed and predicted behaviors match closely. The procedures were developed to predict the shear strength and elastic parameters of rockfill materials using the index properties, i.e. UCS, UVC and relative density (RD, and predictions were made satisfactorily. Comparing the predicted and experimentally determined shear strengths and elastic parameters, it is observed that both values match closely. Then these procedures were used to predict the elastic and shear strength parameters of large-size prototype rockfill materials. Correlations were also developed between index properties and material strength parameters (dilatancy angle, ψ, and initial void ratio, einit, required for HS model of modeled rockfill materials and the same correlations were used to predict the strength parameters for the prototype rockfill materials. Using the

  3. Modeling the triaxial behavior of riverbed and blasted quarried rockfill materials using hardening soil model

    N.P. Honkanadavar; K.G. Sharma


    Riverbed modeled rockfill material from Noa Dehing dam project, Arunachal Pradesh, India and blasted quarried modeled rockfill material from Kol dam project, Himachal Pradesh, India were considered for this research. Riverbed rockfill material is rounded to sub-rounded and quarried rockfill material is angular to sub-angular in shape. Prototype rockfill materials were modeled into maximum particle size (dmax) of 4.75 mm, 10 mm, 19 mm, 25 mm, 50 mm and 80 mm for testing in the laboratory. Consolidated drained triaxial tests were conducted on modeled rockfill materials with a specimen size of 381 mm in diameter and 813 mm in height to study the stressestrainevolume change behavior for both rockfill materials. Index properties, i.e. uncompacted void content (UVC) and uniaxial compressive strength (UCS), were determined for both rockfill materials in association with material parameters. An elasto-plastic hardening soil (HS) constitutive model was used to predict the behavior of modeled rockfill materials. Comparing the predicted and observed stressestrainevolume change behavior, it is found that both observed and predicted behaviors match closely. The procedures were developed to predict the shear strength and elastic parameters of rockfill materials using the index properties, i.e. UCS, UVC and relative density (RD), and predictions were made satisfactorily. Comparing the predicted and experi-mentally determined shear strengths and elastic parameters, it is observed that both values match closely. Then these procedures were used to predict the elastic and shear strength parameters of large-size prototype rockfill materials. Correlations were also developed between index properties and ma-terial strength parameters (dilatancy angle, j, and initial void ratio, einit, required for HS model) of modeled rockfill materials and the same correlations were used to predict the strength parameters for the prototype rockfill materials. Using the predicted material parameters

  4. [Influence of cryogenic treatment and age-hardening heat treatment on the corrosion behavior of a dental casting Ag-Pd alloy].

    Zhao, Yao; Wu, Bin; Meng, Yukun


    The purpose of this study is to investigate the influence of cryogenic treatment and age-hardening heat treatment on the corrosion behavior of a dental casting Ag-Pd alloy. A low gold content dental casting alloy composed of Ag-Pd-Cu-Au was prepared for this study. Corrosion test was performed according to ISO 10271:2001 dental metallie-corrosion test methods. Experimental specimens were casted according to a standard dental lost-wax casting procedure, treated with solution by heating the specimens to 900 degrees C, and immediately quenched in ice water. The specimens were then divided into four groups and subjected to heat treatment, cryogenic treatment, and heat treatment combined with cryogenic treatment. The specimens after the solution treatment were taken as control. The metallographic structures of the specimens were observed. The electrochemical parameters and the quantity of non-precious metallic ions released were evaluated via electrochemical and static immersion tests. Metallographic observation revealed that all the treatments resulted in a change in the microstructure of the alloy. The treatments were effective in improving the electrochemical parameters, such as an increase in Eocp and Ecorr and a decrease in Icorr (P 0.05). After different treatments, the antierosion properties of the alloy satisfied the ISO requirements. Age-hardening heat treatment and cryogenic treatment improved the corrosion resistance of the alloy.

  5. 浅谈激光束表面相变硬化技术%On Laser Beam Surface Phase Transformation Hardening Technology



    激光束表面相变硬化技术是激光热处理中研究最早、最多、进展最快、应用最广的一种新工艺,适用于大多数材料和不同形状零件的不同部位,可提高零件的耐磨性和疲劳强度。本文简要介绍了激光束表面相变硬化技术的原理以及应用。%Laser beam surface phase transformation hardening technology is the first and most researched new laser heat treatment technique with rapid progress and the widest application. It is suitable for most materials and different parts of different shaped components. It can improve the abrasive resistance and fatigue strength of the components. This article mainly introduces the principle and application of laser beam surface phase transformation hardening technology.


    A. A. Shmatov


    Full Text Available The structure and properties of cutting diamond tools subjected to thermo-hydro-chemical treatment are examined in the paper. The process involves a chemical treatment of tools in a specially prepared aqueous suspension of oxides Ti, Mo and other ingredients and subsequent heat treatment (minimal process temperature 130 °C. Thermo-hydro-chemical method permits to increase a wear resistance of cutting diamond tools by the factor of 1.3–4.0 in comparison with traditional one.

  7. Precipitation hardening and hydrogen embrittlement of aluminum alloy AA7020

    Santosh Kumar; T K G Namboodhiri


    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.

  8. Finish machining of hardened gears wheels using cubic boron nitride (CBN inserts

    R. Talar


    Full Text Available The paper presents some results of investigation of finish machining of hardened bearing surfaces of cylindrical gear wheels. Finish machining has been performed with wedges of defined geometry made of CBN. The presented investigation results are related mainly to the wear processes of the cutting wedges. Additional results of quality examination of finish machined gear wheels have been presented, too.

  9. Improved shape hardening function for bounding surface model for cohesive soils

    Andrés Nieto-Leal


    Full Text Available A shape hardening function is developed that improves the predictive capabilities of the generalized bounding surface model for cohesive soils, especially when applied to overconsolidated specimens. This improvement is realized without any changes to the simple elliptical shape of the bounding surface, and actually reduces the number of parameters associated with the model by one.

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

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben


    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...

  11. Beam hardening: Analytical considerations of the effective attenuation coefficient of x-ray tomography

    Alles, J.; Mudde, R.F.


    Polychromatic x-ray beams traveling though material are prone to beam hardening, i.e., the high energy part of the incident spectrum gets over represented when traveling farther into the material. This study discusses the concept of a mean attenuation coefficient in a formal way. The total energy fl

  12. Influence of water hardening of the chorion on cadmium accumulation in medaka (Oryzias latipes) eggs.

    González-Doncel, Miguel; Larrea, Maite; Sánchez-Fortún, Sebastián; Hinton, David E


    This report describes a study in which in vitro fertilization methods were used to expose medaka (Oryzias latipes) eggs to cadmium (Cd(2+)). This approach was applied to address the differential sensitivity and cumulative potential of Cd(2+) when exposure was initiated early (before fertilization and water hardening of the chorion) versus later during embryo development (i.e., well after the chorion has undergone water hardening). Following range finding exposures (2.5, 10, 20, 40 or 80 mg/l) under artificially controlled experimental procedures, results from hatching success and embryo malformations showed the earlier exposure interval more sensitive than the assay involving only the embryonated egg. Subsequent accumulation studies have shown that the exposure initiated before fertilization apparently led to more Cd(2+) deposition in the chorion compared to the exposure during embryonated stages of the eggs. Similarly, values for total Cd(2+) indicated higher concentrations in those eggs exposed prior to--and during--water hardening. Results suggest an alteration of the properties of the zona radiata in the early-stage eggs, making it more permeable to the potential exit or entrance of waterborne agents even after water hardening. Ongoing studies must now address the development of more realistic exposure conditions of the gametes by using incubation media with osmolarities similar to surface waters, and by shortening duration for gamete exposure. Also, sensitive methods to localize Cd(2+) and to delineate the transfer from the chorion to the embryo are needed.

  13. Quenchants for Induction Hardening for the Automotive Industry,Choice and Maintenance

    Hartmut Beitz; Thorsten Beitz


    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.

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

    Christian Siadjeu


    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.

  15. Self-healing behavior of strain hardening cementitious composites incorporating local waste materials

    Qian, S.; Zhou, J.; Rooij, M.R. de; Schlangen, E.; Ye, G.; Breugel, K. van


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

    Tan, Ye; Kiekens, Kim; Welkenhuyzen, Frank


    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...

  17. Friction and wear behaviour of ceramic-hardened steel couples under reciprocating sliding motion

    He, Y.J.; Winnubst, A.J.A.; Schipper, D.J.; Bakker, P.M.V.; Burggraaf, A.J.; Verweij, H.


    The friction and wear behaviour of ZrO2-Y203, ZrO2-Y203-CeO2 and ZrO2-A1203 composite ceramics against hardened steel AISI-52100 were investigated using a pin on plate configuration under reciprocating motion. The reproducibility of the results was examined in this configuration. Wear characteristic

  18. Influence of Plastic Deformation on Low Temperature Surface Hardening of Austenitic Stainless Steel by Gaseous Nitriding

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


    This article addresses an investigation of the influence of plastic deformation on low temperature surface hardening by gaseous nitriding of two commercial austenitic stainless steels: AISI 304 and EN 1.4369. The materials were plastically deformed to different equivalent strains by uniaxial...

  19. The microstructural origin of strain hardening in two-dimensional open-cell metal foams

    Mangipudi, K. R.; van Buuren, S. W.; Onck, P. R.


    This paper aims at elucidating the microstructural origin of strain hardening in open-cell metal foams. We have developed a multiscale model that allows to study the development of plasticity at two length scales: (i) the development of plastic zones inside individual struts (microscopic scale) and

  20. Hardening kinetics investigation of alkali-activated binder by small amplitude oscillatory rheometry

    Rieger, D.; Kullová, L.; Čekalová, M.; Kovářík, T.


    In this study, the rheological behavior of geopolymeric inorganic binder was determined. This binder was synthesized by alkaline activation of mixture, comprising calcined claystone powder and milled blast furnace slag. As an alkaline activator of hardening process, the potassium silicate solution was used. For the investigation of hardening kinetics, the strain controlled small amplitude oscillatory rheometry was used with strain of 0.01%. The reproducibility and versatility of this method is demonstrated for determination of hardening process evolution. The changes of loss tangent shape were studied in this experiment and applied for determination of gelation time. All experiments were conducted at isothermal conditions in temperature range 27-70°C and parallel plate geometry. The results indicate that reaction kinetics is directly depending on temperature. The hardening kinetics was mathematically described and these calculations were compared with self-contained experiment conducted at 2°C. This experiment is described in details and the results of gelation time measurements confirmed calculated data.

  1. Microstructure and transport phenomena in visco-elastic modelling of hardening cementitious materials

    Van der Ham, H.W.M.


    Since the durability depends, among other things, on the quality of the concrete and presence of cracks, it is necessary to calculate the probability of cracking in hardening concrete as reliable as possible in case of durability predictions. In this thesis, it is investigated how the accuracy of st

  2. Beam hardening correction for a cone-beam CT system and its effect on spatial resolution

    ZHAO Wei; WEI Long; YU Zhong-Qiang; FU Guo-Tao; SUN Cui-Li; WANG Yan-Fang; WEI Cun-Feng; CAO Da-Quan; QUE Jie-Min; TANG Xiao; SHI Rong-Jian


    In this paper,we present a beam hardening correction (BHC) method in three-dimension space for a cone-beam computed tomography (CBCT) system in a mono-material case and investigate its effect on the spatial resolution.Due to the polychromatic character of the X-ray spectrum used,cupping and streak artifacts called beam hardening artifacts arise in the reconstructed CT images,causing reduced image quality.In addition,enhanced edges are introduced in the reconstructed CT images because of the beam hardening effect.The spatial resolution of the CBCT system is calculated from the edge response function (ERF) on different planes in space.Thus,in the CT images with beam hardening artifacts,enhanced ERFs will be extracted to calculate the modulation transfer function (MTF),obtaining a better spatial resolution that deviates from the real value.Reasonable spatial resolution can be obtained after reducing the artifacts.The 10% MTF value and the full width at half maximum (FWHM) of the point spread function with and without BHC are presented.

  3. High temperature, radiation hardened electronics for application to nuclear power plants

    Gover, J.E.


    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.

  4. Effect of Cutting Parameters on Microhardness in 2 mm Slot Milling Hardened Tool Steel

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


    This paper presents an experimental study on the dependency of surface integrity on cutting parameters in slot milling of hardened tool steel. A series of 2 mm slot milling tests have been performed with different cutting parameters. Microhardness was chosen for evaluation of subsurface integrity...

  5. Improved shape hardening function for bounding surface model for cohesive soils

    Andrés Nieto-Leal; Victor N.Kaliakin


    A shape hardening function is developed that improves the predictive capabilities of the generalized bounding surface model for cohesive soils, especially when applied to overconsolidated specimens. This improvement is realized without any changes to the simple elliptical shape of the bounding surface, and actually reduces the number of parameters associated with the model by one.

  6. Design and characterization of novel precipitation hardenable high Cr Ni-based superalloys

    Bihlet, Uffe; Dahl, Kristian Vinter; Somers, Marcel A. J.


    Among the Ni-based superalloys, Alloy 718 stands apart with the ability to be precipitation hardened after welding, by the slow formation of nano-scale γ’’ (Ni3Nb) particles. This slow formation gives it a very low crack susceptibility, which has made it widely applied since its introduction...

  7. Study on Laser Transformation Hardening of HT250 by High Speed Axis Flow CO2 Laser


    In this article, laser transformation hardening of HT250 material by high speed axis flow CO2 laser was investigated for first time in China. Appropriate laser hardening parameters, such as laser energy power P(W), laser scanning rate V(m/min),were optimized through a number of experiments. The effect of the mentioned parameters on the hardened zone, including its case depth, microhardness distributions etc., were analyzed. Through the factual experiments, it is proved that axial flow CO2 laser, which commonly outputs low mode laser beam, can also treat materials as long as the treating parameters used are rational. During the experiments, the surface qualities of some specimens treated by some parameters were found to be enhanced, which does not coincide with the former results. Furthermore in the article, the abnormal phenomenon observed in the experiments is discussed. According to the experimental results, the relationship between laser power density q and scanning rate V is shown in a curve and the corresponding formulation, which have been proved to be valuable for choosing the parameters of laser transformation hardening by axial flow CO2 lasers, was also given.

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

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


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

  9. The effects of cold-hardening on Rubisco in rice seedling leaves

    ZHAOJun; WANGYirou; LIMeiru; LIUHongxian; MIAOYougang; LILiren


    Rubisco is a key enzyme which controls the process of photosynthesis and photorespiration. It is very abundant in the leaf and is very sensitive to many environmental factors. We studied the changes, caused by cold hardening and chilling stress, in activity, protein content,

  10. Characterization of Radiation Hardened Bipolar Linear Devices for High Total Dose Missions

    McClure, Steven S.; Harris, Richard D.; Rax, Bernard G.; Thorbourn, Dennis O.


    Radiation hardened linear devices are characterized for performance in combined total dose and displacement damage environments for a mission scenario with a high radiation level. Performance at low and high dose rate for both biased and unbiased conditions is compared and the impact to hardness assurance methodology is discussed.

  11. Finite-Element Simulation of Conventional and High-Speed Peripheral Milling of Hardened Mold Steel

    Tang, D. W.; Wang, C. Y.; Hu, Y. N.; Song, Y. X.


    A finite-element model (FEM) with the flow stress and typical fracture is used to simulate a hard machining process, which before this work could not adequately represent the constitutive behavior of workpiece material that is usually heat treated to hardness levels above 50 Rockwell C hardness (HRC). Thus, a flow stress equation with a variation in hardness is used in the computer simulation of hard machining. In this article, the influence of the milling speed on the cutting force, chip morphology, effective stress, and cutting temperature in the deformation zones of both conventional and high-speed peripheral milling hardened mold steel is systematically studied by finite-element analysis (FEA). By taking into consideration the importance of material characteristics during the milling process, the similar Johnson-Cook’s constitutive equation with hardened mold steel is introduced to the FEM to investigate the peripheral milling of hardened mold steel. In comparison with the experimental data of the cutting force at various cutting speeds, the simulation result is identical with the measured data. The results indicate that the model can be used to accurately predict the behavior of hardened mold steel in both conventional and high-speed milling.

  12. Characteristics of laser beam welds of age-hardenable 6061-T6 aluminum alloy

    Hirose, Akio; Kobayashi, Kojiro F.


    Laser beam welding is attractive for joining age-hardenable aluminum alloys, because its low over-all heat input results in a narrow weld heat affected zone (HAZ), where softening caused by dissolution of age precipitates occurs. In the present work, 1mm-thick 6061-T6 aluminum alloy plates were welded using a 2.5 kW CO2 laser and it was experimentally proved that the width of the softened region in the laser beam weld was less than 1/7 that of a TIG weld. Moreover the hardness in the softened region of the laser beam weld was found to be almost fully recovered to the base metal hardness by applying a post-weld aging treatment at 443 K for 28.8 ks without solution annealing unlike the TIG weld. These results characterize the advantage of laser beam welding in joining of the age-hardenable aluminum alloy as compared with the conventional arc welding. The hardness distributions in the HAZ were theoretically evaluated based on kinetic equations describing the dissolution of hardening β' (Mg2Si) precipitates and the precipitation of non-hardening β' (Mg2Si) precipitates during the weld thermal cycles to quantitatively prove above mentioned advantageous characteristics of laser beam welding.

  13. An alternative approach to estimate the W/C ratio of hardened concrete using image analysis

    Valcke, S.; Nijland, T.G.; Larbi, J.A.


    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




    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.

  15. Hall coefficient measurement for residual stress assessment in precipitation hardened IN718 nickel-base superalloy

    Velicheti, Dheeraj; Nagy, Peter B.; Hassan, Waled


    We investigated the feasibility of residual stress assessment based on Hall coefficient measurements in precipitation hardened IN718 nickel-base superalloy. As a first step, we studied the influence of microstructural variations on the galvanomagnetic properties of IN718 nickel-base superalloy. We found that the Hall coefficient of IN718 increases from ≈ 8.0×10-11 m3/C in its fully annealed state of 15 HRC Rockwell hardness to ≈ 9.4×10-11 m3/C in its fully hardened state of 45 HRC. We also studied the influence of cold work, i.e., plastic deformation, at room temperature and found that cold work had negligible effect on the Hall coefficient of fully annealed IN718, but significantly reduced it in hardened states of the material. For example, measurements conducted on fully hardened IN718 specimens showed that the Hall coefficient decreased more or less linearly with cold work from its peak value of ≈ 9.4×10-11 m3/C in its intact state to ≈ 9.0×10-11 m3/C in its most deformed state of 22% plastic strain. We also studied the influence of applied stress and found that elastic strain significantly increases the Hall coefficient of IN718 regardless of the state of hardening. The relative sensitivity of the Hall coefficient to elastic strain was measured as a unitless gauge factor K that is defined as the ratio of the relative change of the Hall coefficient ΔRH/RH divided by the axial strain ɛ = σ/E, where σ is the applied uniaxial stress and E is the Young's modulus of the material. We determined that the galvanomagnetic gauge factor of IN718 is κ ≈ 2.6 - 2.9 depending on the hardness level. Besides the fairly high value of the gauge factor, it is important that it is positive, which means that compressive stress in surface-treated components decreases the Hall coefficient in a similar way as plastic deformation does, therefore the unfortunate cancellation that occurs in fully hardened IN718 in the case of electric conductivity measurements will not

  16. The response of mulberry trees after seedling hardening to summer drought in the hydro-fluctuation belt of Three Gorges Reservoir Areas.

    Huang, Xiaohui; Liu, Yun; Li, Jiaxing; Xiong, Xingzheng; Chen, Yang; Yin, Xiaohua; Feng, Dalan


    Interest has developed in the potential of mulberry (Morus alba), a woody perennial, for revegetating the hydro-fluctuation belt of the Three Gorges Reservoir due to its resistance to water-logging stress. To be useful, the trees must also be able to withstand dry conditions in summer when temperatures can be very high and droughts become severe quickly. Here, we report a study in which mulberry seedlings were grown in a greenhouse under a variety of simulated soil water conditions reflecting potential summer scenarios in the hydro-fluctuation belt of the Three Gorges Reservoir Area. We compared the responses of two pretreatment groups of mulberry seedlings to different levels of drought stress. The pretreatment groups differed with respect to drought hardening: the daily-managed (DM) group had relative soil moisture held constant in the range 70-80 %, while the drought-hardened (DH) group had relative soil moisture held constant at 40-50 %. Following the month-long pretreatment of seedlings, the two groups of young trees (DM and DH) were then respectively subjected to three levels of drought stress for a month: normal watering, moderate drought stress, and severe drought stress. A series of measurements comparing the physiological status of the plants in the two groups were then made, and the following results were obtained: (1) As drought stress increased, the heights, base diameters, root surface areas, photosynthetic rates (Pn), stomatal conductances (Gs), and transpiration rates (Tr) of the mulberry trees in both groups (DM and DH) decreased significantly, while the specific root area and abscisic acid (ABA) contents had increasing trends. Root activity and instantaneous water use efficiency of mulberry trees in both groups (DM and DH) were all raised under drought stress conditions than under normal watering, but the root/shoot ratio and leaf water potential were lowered. (2) At the same level of soil water content, the heights, base diameters, root

  17. Abrasive Wear of Laser Surface Hardened 9SiCr in Soils%激光硬化9SiCr表面土壤磨损研究

    陈卓君; 张祖立


    Abrasive wear tests of laser treated 9SiCr blade were conducted using three kinds of abrasives ( loam soil, sand soil and clay soil). The parameters of laser treatment (e. g. laser power 1 200 W, scanning velocity 14 mm/s, laser power 1 500 W, scanning velocity 16 mm/s) were optimized to obtain the hard and wear resistant surface on 9SiCr blade. Wear resistances of laser treated 9SiCr blade in three kinds of soils were measured and compared. The wear resistance of laser hardened 9SiCr steel blade was 5 times as high as that of quenched 9SiCr steel blade. The main wear mechanism of laser hardened 9SiCr blade in soil was abrasive wear. By improving the hardness, the wear lifetime of laser hardened 9SiCr blade was prompted.%在壤土、沙土和黏土3种土壤中对激光处理的9SiCr材料进行磨损试验,考察了激光硬化工艺参数对9SiCr旋耕刀基体显微硬度的影响,获得9SiCr旋耕刀基体激光硬化处理的最佳工艺参数.结果表明:在激光功率为1 200 W、扫描速度为14 mm/s和激光功率1 500 W、扫描速度16 mm/s的条件下,磨损率较小.激光处理表面在3种土壤条件下进行了耐磨性比较,沙土对试件的磨损率影响最小.9SiCr经过激光处理其表面耐磨性比一般淬火表面的耐磨性提高约5倍.9Sicr表面磨损形式主要是磨粒磨损.激光处理9SiCr表面提高了表面硬化层的硬度,从而提高了材料的耐磨性,增加了9SiCr的使用寿命.

  18. Saturation behavior of irradiation hardening in F82H irradiated in the HFIR

    Hirose, T. [Blanket Engineering Group, Japan Atomic Energy Agency, Naka, Ibaraki (Japan); Shiba, K.; Tanigawa, H.; Ando, M. [Japan Atomic Energy Agency, Tokai-mura, Naga-gun, Ibaraki-ken (Japan); Klueh, R.L. [Oak Ridge National Laboratory, TN (United States); Stoller, R. [ORNL - Oak Ridge National Laboratory, Materials Science and Technology Div., Oak Ridge, AK TN (United States)


    Full text of publication follows: Post irradiation tensile tests on reduced activation ferritic/martensitic steel, F82H have been conducted over the past two decades using Japan Materials Testing Reactor (JMTR) of JAEA, and Fast Flux Testing Facility (FFTF) of PNNL and High Flux Isotope Reactor (HFIR) of ORNL, USA, under Japan/US collaboration programs. According to these results, F82H does not demonstrate irradiation hardening above 673 K up to 60 dpa. The current study has been concentrated on hardening behavior at temperature around 573 K. A series of low temperature irradiation experiment has been conducted at the HFIR under the international collaborative research between JAEA/US-DOE. In this collaboration, the irradiation condition is precisely controlled by the well matured capsule designing and instrumentation. This paper summarizes recent results of the irradiation experiments focused on F82H and its modified steels compared with the irradiation properties database on F82H. Post irradiation tensile tests have been conducted on the F82H and its modified steels irradiated at 573 K and the dose level was up to 25 dpa. According to these results, irradiation hardening of F82H is saturated by 9 dpa and the as-irradiated 0.2 % proof stress is less than 1 GPa at ambient temperature. The deterioration of total elongation was also saturated by 9 dpa irradiation. The ductility of some modified steels which showed larger total elongation than that of F82H before irradiation become the same level as that of standard F82H steel after irradiation, even though its magnitude of irradiation hardening is smaller than that of F82H. This suggests that the more ductile steel demonstrates the more ductility loss at this temperature, regardless to the hardening level. The difference in ductility loss behavior between various tensile specimens will be discussed as the ductility could depend on the specimen dimension. (authors)

  19. Press-hardening of zinc coated steel - characterization of a new material for a new process

    Kurz, T.; Larour, P.; Lackner, J.; Steck, T.; Jesner, G.


    Press-hardening of zinc-coated PHS has been limited to the indirect process until a pre-cooling step was introduced before the hot forming to prevent liquid metal embrittlement. Even though that's only a minor change in the process itself it does not only eliminate LME, but increases also the demands on the base material especially in terms of hardenability or phase transformations at temperatures below 700 °C in general. This paper deals with the characterization of a modified zinc-coated material for press-hardening with pre-cooling that assures a robust process. The pre-cooling step itself and especially the transfer of the blank in the hot-forming die is more demanding than the standard 22MnB5 can stand to ensure full hardenability. Therefore the transformation behavior of the modified material is shown in CCT and TTT diagrams. Of the same importance are the changed hot forming temperature and flow curves for material at lower temperatures than typically used in direct hot forming. The resulting mechanical properties after hardening from tensile testing and bending tests are shown in detail. Finally some results from side impact crash tests and correlations of the findings with mechanical properties such as fracture elongation, tensile strength, VDA238 bending angle at maximum force as well as postuniform bending slope are given as well. Fracture elongation is shown to be of little help for damage prediction in side impact crash. Tensile strength and VDA bending properties enable however some accurate prediction of the PHS final damage behavior in bending dominated side impact load case.

  20. Theory of work-hardening applied to stages III and IV

    Kuhlmann-Wilsdorf, D.; Hansen, N.


    Stage IV has become the accepted name for that work-hardening stage within which large plastic strains can occur at a very low, virtually constant work-hardening rate, as exemplified by cold rolling and wire drawing. By contrast, in the preceding stage III, the work-hardening rate decreases sharply with strain, whereas in the still earlier stage II, the work-hardening rate is also almost constant but has a high value. The classical paper by Langford and Cohen on drawn iron wire is now recognized as one of the earliest studies of stage IV. Already in 1970, a detailed theoretical analysis of that work based on the mesh length theory was presented[2] which has stood the test of time, although in it the Langford and Cohen experiments were considered to represent stage II on account of the operation of similitude and the almost constant work-hardening rate. The present paper re-examines the 1970 theoretical interpretation in terms of stage IV behavior, which necessitates reinterpretation of stage III. Included in the present interpretation are more recent insights regarding dislocation behavior in so-called LEDS, low-energy dislocation structures. It is concluded that stages II and IV differ, because in stage II, cross slip is insignificant, while in stage IV, it is unlimited. Accordingly, cross slip is gradually established in the course of stage III. However, similitude appears to operate in all three stages. By extension of the argument regarding stages III and IV, it is seen that stages V and VI could follow, including similitude, through the establishment of climb.

  1. 新型加硬离子镀金与传统离子镀金样品的性能对比%Comparison of performance between a novel ion-plated hardened gold coating and traditional ion-plated gold sample

    宋鹏涛; 王永宁; 谢逸; 孔晶; 刘海华


    The performance differences between novel hardened ion plated gold coating and traditional ion plated one were studied by apparent color determination, elemental analysis, hardness testing, scratch-resistant properties, wear resistance, adhesion strength, and corrosion resistance test. The results showed that the novel hardened gold-plated sample has a color closer to the standard color plate, higher microhardness, better wear resistance, and higher scratch resistance as compared to the traditional gold-plated sample. The adhesion strength and corrosion resistance of the novel hardened gold-plated sample are excellent. By introducing some metal elements such as copper and iridium to surface coating, the gold content of the novel hardened gold-plated sample is lowered and the production cost is reduced.%通过外观颜色测定,成分分析,硬度检测,耐擦花性能、耐磨性能、结合力和耐人工汗腐蚀测试,研究了新型加硬离子镀金与传统离子镀金样品的性能差异。结果表明,与传统镀金样品相比,新型加硬镀金样品的颜色更接近标准色板,硬度更高,耐磨和耐擦花性能更优。此外,新型加硬镀金样品的镀层结合力及耐腐蚀性能良好。新型加硬离子镀金技术通过在表面镀层中加入铜、铱等金属元素,降低了金的含量,使成本降低。

  2. Effect of laser shot peening on precipitation hardened aluminum alloy 6061-T6 using low energy laser

    Sathyajith, S.; Kalainathan, S.


    Mechanical properties of engineering material can be improved by introducing compressive residual stress on the material surface and refinement of their microstructure. Variety of mechanical process such as shot peening, water jet peening, ultrasonic peening, laser shot peening were developed in the last decades on this contrast. Among these, lasers shot peening emerged as a novel industrial treatment to improve the crack resistance of turbine blades and the stress corrosion cracking (SCC) of austenic stainless steel in power plants. In this study we successfully performed laser shot peening on precipitation hardened aluminum alloy 6061-T6 with low energy (300 mJ, 1064 nm) Nd:YAG laser using different pulse densities of 22 pulses/mm 2 and 32 pulses/mm 2. Residual stress evaluation based on X-ray diffraction sin 2 ψ method indicates a maximum of 190% percentage increase on surface compressive stress. Depth profile of micro-hardness shows the impact of laser generated shock wave up to 1.2 mm from the surface. Apart from that, the crystalline size and micro-strain on the laser shot peened surfaces have been investigated and compared with the unpeened surface using X-ray diffraction in conjunction with line broadening analysis through the Williamson-Hall plot.

  3. Influence of cold deformation and annealing on hydrogen embrittlement of cold hardening bainitic steel for high strength bolts

    Hui, Weijun, E-mail: [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Zhang, Yongjian; Zhao, Xiaoli; Shao, Chengwei [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Wang, Kaizhong; Sun, Wei; Yu, Tongren [Technical Center, Maanshan Iron & Steel Co., Ltd., Maanshan 243002, Anhui (China)


    The influence of cold drawing and annealing on hydrogen embrittlement (HE) of newly developed cold hardening bainitic steel was investigated by using slow strain rate testing (SSRT) and thermal desorption spectrometry (TDS), for ensuring safety performance of 10.9 class high strength bolts made of this kind of steel against HE under service environments. Hydrogen was introduced into the specimen by electrochemical charging. TDS analysis shows that the hydrogen-charged cold drawn specimen exhibits an additional low-temperature hydrogen desorption peak besides the original high-temperature desorption peak of the as-rolled specimen, causing remarkable increase of absorbed hydrogen content. It is found that cold drawing significantly enhances the susceptibility to HE, which is mainly attributed to remarkable increase of diffusible hydrogen absorption, the occurrence of strain-induced martensite as well as the increase of strength level. Annealing after cold deformation is an effective way to improve HE resistance and this improvement strongly depends on annealing temperature, i.e. HE susceptibility decreases slightly with increasing annealing temperature up to 200 °C and then decreases significantly with further increasing annealing temperature. This phenomenon is explained by the release of hydrogen, the recovery of cold worked microstructure and the decrease of strength with increasing annealing temperature.

  4. Formation of Structure of Wear-Resistant Steels 150KhNML and Kh12MFL Upon Quenching

    Filippov, M. A.; Gervas'ev, M. A.; Plotnikov, G. N.; Zhilin, A. S.; Nikiforova, S. M.


    The effect of the temperature of heating for quenching on the content of retained austenite and its resistance to the deformation-induced martensitic transformation, the hardening capacity, and the resistance to abrasive wear are studied for high-carbon tool steels 150KhNML and Kh12MFL of pearlitic and ledeburitic classes.

  5. High-velocity deformation of Al0.3CoCrFeNi high-entropy alloy: Remarkable resistance to shear failure

    Li, Z.; Zhao, S.; Diao, H.; Liaw, P. K.; Meyers, M. A.


    The mechanical behavior of a single phase (fcc) Al0.3CoCrFeNi high-entropy alloy (HEA) was studied in the low and high strain-rate regimes. The combination of multiple strengthening mechanisms such as solid solution hardening, forest dislocation hardening, as well as mechanical twinning leads to a high work hardening rate, which is significantly larger than that for Al and is retained in the dynamic regime. The resistance to shear localization was studied by dynamically-loading hat-shaped specimens to induce forced shear localization. However, no adiabatic shear band could be observed. It is therefore proposed that the excellent strain hardening ability gives rise to remarkable resistance to shear localization, which makes this material an excellent candidate for penetration protection applications such as armors. PMID:28210000

  6. High-velocity deformation of Al0.3CoCrFeNi high-entropy alloy: Remarkable resistance to shear failure

    Li, Z.; Zhao, S.; Diao, H.; Liaw, P. K.; Meyers, M. A.


    The mechanical behavior of a single phase (fcc) Al0.3CoCrFeNi high-entropy alloy (HEA) was studied in the low and high strain-rate regimes. The combination of multiple strengthening mechanisms such as solid solution hardening, forest dislocation hardening, as well as mechanical twinning leads to a high work hardening rate, which is significantly larger than that for Al and is retained in the dynamic regime. The resistance to shear localization was studied by dynamically-loading hat-shaped specimens to induce forced shear localization. However, no adiabatic shear band could be observed. It is therefore proposed that the excellent strain hardening ability gives rise to remarkable resistance to shear localization, which makes this material an excellent candidate for penetration protection applications such as armors.

  7. Cycling Hardening and Serration Yielding of Fe-Ni-Cr Alloy at High Temperature under Out-phase TMF

    HE Qingfu


    Behaviour of hardening and serration yield of a Fe-Ni-Cr alloy under isothermal cycling(ISC)and out-phase TMF was studied on the basis of varied hysteresis loops.Cycling hardening and serrated yielding for ISC depend on the temperature and the total strain range,stronger hardening with serrated yielding at higher strain range under ISC at 600℃,but no hardening and serrated yielding occurred under ISC at 800℃.Strongerhardening with stress serration occurred at the thermal path going to the lowest temperature,no stress serration occurred at the highest temperature under the out-phase.The hardening also depends on the total strain range,higher total strain range with lower cycling temperature resulted in a stronger hardening and remarkable serration yielding behavior.Weaker hardening without serrated yielding occurred at near 800℃may due to an obvious cycling stress drop under out-phase TMF.Change in the shape of the hysteresis loops also expresses the degree of the damage of the tested alloy under out-phase and ISC.

  8. Analysis of Tensile Stress-Strain and Work-Hardening Behavior in 9Cr-1Mo Ferritic Steel

    Choudhary, B. K.; Palaparti, D. P. Rao; Samuel, E. Isaac


    Detailed analysis on tensile true stress ( σ)-true plastic strain ( ɛ) and work-hardening behavior of 9Cr-1Mo steel have been performed in the framework of the Voce relationship and Kocks-Mecking approach for wide range of temperatures, 300 K to 873 K (27 °C to 600 °C) and strain rates (6.33 × 10-5 to 6.33 × 10-3 s-1). At all test conditions, σ- ɛ data were adequately described by the Voce equation. 9Cr-1Mo steel exhibited two-stage work-hardening behavior characterized by a rapid decrease in instantaneous work-hardening rate ( θ = dσ/ dɛ) with stress at low stresses (transient stage) followed by a gradual decrease in θ at high stresses (stage III). The variations of work-hardening parameters and θ- σ as a function of temperature and strain rate exhibited three distinct temperature regimes. Both work-hardening parameters and θ- σ displayed signatures of dynamic strain aging at intermediate temperatures and dominance of dynamic recovery at high temperatures. Excellent correlations have been obtained between work-hardening parameters evaluated using the Voce relationship and the respective tensile properties. A comparison of work-hardening parameters obtained using the Voce equation and Kocks-Mecking approach suggested an analogy between the two for the steel.

  9. Self-hardening and thermoresponsive alpha tricalcium phosphate/pluronic pastes.

    Maazouz, Yassine; Montufar, Edgar B; Malbert, Julien; Espanol, Montserrat; Ginebra, Maria-Pau


    thermoresponsive cements studied herein open up new perspectives in the surgical field, where the sequential gelling/hardening of these novel cements could allow for a better and safer clinical application. Calcium phosphate cements are attractive bone substitutes due to their similarity to the bone mineral phase. Although they can be injectable, cohesion and stability of the paste are crucial in terms of performance and safety. A common strategy is the combination with hydrogels. However, this often results in a decrease of viscosity with increasing temperature, which can lead to extravasation and particle leakage from the bone defect. The preferred evolution would be the opposite: a low viscosity would enhance mixing and injection, and an instantaneous increase of viscosity after injection would ensure washout resistance to the blood flow. Here we develop for the first time a calcium phosphate cement exhibiting reverse thermoresponsive properties using a poloxamer featuring inverse thermal gelling. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  10. Comparison of Some Mechanical and Physical Methods for Measurement of Residual Stresses in Brush-Plated Nickel Hardened Gold and Silver Coatings

    Harri LILLE


    Full Text Available Hard gold and silver are applied in coating owing to their high hardness, good wear and corrosion resistance for engineering application (e.g. on generators slip rings, sliding contacts and small machine parts and are typically plated on copper (mostly, brass and bronze. The studied nickel-hardened gold and silver coatings were brush plated on open thin-walled copper ring substrates. Residual stresses in the coatings were calculated from the curvature changes of the substrates. Biaxial intrinsic residual stresses were also determined by nanoindentation testing and by the X-ray technique. The values of the residual stresses represented tensile stresses and when determined by the techniques used they were comparable within a maximum limit of measurement uncertainty. These stresses relax; the dependence of relaxation time was approximated by a linear-fractional function.DOI:

  11. Simulation of irradiation hardening of Zircaloy within plate-type dispersion nuclear fuel elements

    Jiang, Yijie; Wang, Qiming; Cui, Yi; Huo, Yongzhong; Ding, Shurong


    Within plate-type dispersion nuclear fuel elements, the metal matrix and cladding attacked continuously by fast neutrons undergo irradiation hardening, which might have remarkable effects upon the mechanical behaviors within fuel elements. In this paper, with the irradiation hardening effect of metal materials mainly considered together with irradiation growth effect of the cladding, the three-dimensional large-deformation constitutive relations for the metal matrix and cladding are developed. The method of virtual temperature increase in the previous studies is further developed to model the irradiation swelling of fuel particles; the method of anisotropic thermal expansion is introduced to model irradiation growth of the cladding; and a method of multi-step-temperature loading is proposed to simulate the coupling features of irradiation-induced swelling of the fuel particles together with irradiation growth of the cladding. Above all, based on the developed relationship between irradiation growth at certain burnup and the loaded virtual temperatures, with considering that certain burnup corresponds to certain fast neutron fluence, the time-dependent constitutive relation due to irradiation hardening effect is replaced by the virtual-temperature-dependent one which is introduced into the commercial software to simulate the irradiation hardening effects of the matrix and cladding. Numerical simulations of the irradiation-induced mechanical behaviors are implemented with the finite element method in consideration of the micro-structure of the fuel meat. The obtained results indicate that when the irradiation hardening effects are introduced into the constitutive relations of the metal matrix and cladding: (1) higher maximum Mises stresses for certain burnup at the matrix exist with the equivalent plastic strains remaining almost the same at lower burnups; (2) the maximum Mises stresses for certain burnup at the cladding are enhanced while the maximum equivalent

  12. Deformation behavior in reactor pressure vessel steels as a clue to understanding irradiation hardening.

    DiMelfi, R. J.; Alexander, D. E.; Rehn, L. E.


    In this paper, we examine the post-yield true stress vs true strain behavior of irradiated pressure vessel steels and iron-based alloys to reveal differences in strain-hardening behavior associated with different irradiating particles (neutrons and electrons) and different alloy chernky. It is important to understand the effects on mechanical properties caused by displacement producing radiation of nuclear reactor pressure steels. Critical embrittling effects, e.g. increases in the ductile-to-brittle-transition-temperature, are associated with irradiation-induced increases in yield strength. In addition, fatigue-life and loading-rate effects on fracture can be related to the post-irradiation strain-hardening behavior of the steels. All of these properties affect the expected service life of nuclear reactor pressure vessels. We address the characteristics of two general strengthening effects that we believe are relevant to the differing defect cluster characters produced by neutrons and electrons in four different alloys: two pressure vessel steels, A212B and A350, and two binary alloys, Fe-0.28 wt%Cu and Fe-0.74 wt%Ni. Our results show that there are differences in the post-irradiation mechanical behavior for the two kinds of irradiation and that the differences are related both to differences in damage produced and alloy chemistry. We find that while electron and neutron irradiations (at T {le} 60 C) of pressure vessel steels and binary iron-based model alloys produce similar increases in yield strength for the same dose level, they do not result in the same post-yield hardening behavior. For neutron irradiation, the true stress flow curves of the irradiated material can be made to superimpose on that of the unirradiated material, when the former are shifted appropriately along the strain axis. This behavior suggests that neutron irradiation hardening has the same effect as strain hardening for all of the materials analyzed. For electron irradiated steels, the


    V.M. Sounthararajan


    Full Text Available Steel fibre addition in concrete possesses high merits in terms of achieving homogeneity and tensile strength properties. Polymeric addition in concrete has high advantages in terms of pore fillingeffect and subsequent increase in durability index. The combined addition of steel and polymeric latex additions in concrete leads to increased strength, durability, toughness, resistance to cracking and crack propagation. Studies were conducted in the present study to analyse the properties of concrete that can be further improved with the addition of polymer styrene butadiene rubber emulsion (SBR along with steel fibres. In this research analysis, styrene-butadiene rubber (SBR latex as a polymeric admixture was used in steel fibre reinforced concrete. The effect of curing conditions on the strength gain properties of composite steel fibre latex matrix on the compressive, flexural strength, and split tensile test of polymermodified steel fibre reinforced concrete (PSFC concrete was examined. Including SBR latex at a certain % of binder in the PSFC concrete improves the bonds within the cement matrix and steel fibres (SF. This is due to the SBR films formed in the matrix. By the comparison of properties of SFC and PSFC, it can be shown that a tremendous increase in compressive strength when 4% and 8% SBR is added along with 0.75% and 1.5% SF. The increase in flexural strength was noticed and post cracking ductility is imparted to concrete.

  14. Hardening of graphite surface by ion beam amorphization

    Hirvonen, J.P.; Stone, D.; Nastasi, M.; Hannula, S.P.


    Ion implantation has been shown to possess potential as a practical method for improving the mechanical properties of surfaces. So far a number of tests have been performed. In these studies, metals - most often steels or other hard materials - have been used. However, the improvement of the mechanical properties at the surface is not only important for substances that already have considerable hardness, but also for materials with other unique properties. Graphite is useful in many applications. Mechanically, it is easily machined and has good dimensional stability. It has self lubricity and under certain conditions has excellent sliding properties. Chemically, it is generally impermeable, resistant to corrosion, and compatable with mating materials. It is a good conductor of both heat and electrical current. The ion implantation of graphite has been studied elsewhere but without reference to the mechanical properties of the surface. It is expected, however, that heavy ion bombardment will cause structural changes at the graphite surface resulting in a modification of the mechanical properties. In this investigation the authors focus on these properties. The main objectives have been to study how the surface mechanical properties are changed by an ion bombardment and to find the relationship between mechanical properties and microstructure.

  15. Surface hardening of steel by pulse laser with proportional intensity distribution spots%特定强度分布脉冲激光表面强化实验

    孙培培; 虞钢; 王恒海; 何秀丽; 李少霞


    The uniformity of hardened layer is affected by dimensional intensity distribution and time of laser spots.Pulsed laser spots with 5 × 5 two dimensional array which have intensity proportions of 1∶2∶3, 3∶2∶1 and 1∶1∶1 intensity distribution by optical transformation was used to harden Q235 steel.The effects of laser treatment on surface morphology, hardened layer shape, distribution of hardness and wear resistance of the Q235 steel were studied.The results show that the dimensional intensity distribution of laser spot affects uniformity of hardened layer to a large extent.The surface morphology, uniformity of hardened layer, uniformity of hardness and wear resistance of Q235 steel laser-treated by the array with intensity proportion of 1∶2∶3 are all better than that by the array with intensity proportion of 1∶1∶1.%激光硬化层均匀性受光束空间强度分布和作用时间的影响.采用二元光学变换技术得到光束中心线强度比值为1:2:3、3:2:1和1:1:1的5×5点阵光斑,研究这三种强度分布光斑对Q235钢脉冲激光硬化后表面形貌、硬化层形状、硬度及耐磨性的影响.结果表明,激光光斑的空间强度分布对Q235钢硬化层均匀性影响很大,1:2:3强度分布光斑作用下的材料表面形貌、硬化层均匀性、硬度均匀度均优于1:1:1强度分布光斑.

  16. Strong work-hardening behavior induced by the solid solution strengthening of dendrites in TiZr-based bulk metallic glass matrix composites

    Ma, D.Q. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Jiao, W.T. [College of Education, Hebei Normal University of Science and Technology, Qinhuangdao 066004 (China); Zhang, Y.F. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Hebei Vocational and Technical College of Building Materials, Qinhuangdao 066004 (China); Wang, B.A.; Li, J.; Zhang, X.Y. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Ma, M.Z., E-mail: [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Liu, R.P. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)


    Highlights: • Hardness of dendrite of TiZr-based BMGMCs increases. • Strong work-hardening behavior is obtained after solid solution strengthening. • Lattice distortions of dendrite suffering from rapid cooling are detected. - Abstract: A series of TiZr-based bulk metallic glass matrix composites (BMGMCs) with distinguished mechanical properties are successfully fabricated by adding different volume fractions of Ta (Ti{sub 38.8}Zr{sub 28.8}Cu{sub 6.2}Be{sub 16.2}Nb{sub 10} as the basic composition, denoted as Ta{sub 0.0}–Ta{sub 8.0}). Along with the growth of precipitated phase, typical dendritic morphology is fully developed in the TiZr-based BMGMCs of Ta{sub 8.0}. Energy-dispersive spectrometry analysis of the dendrites and glass matrix indicates that the metallic elements of Nb and Ta should preferentially form solid solution into dendrites. The chaotic structure of high-temperature precipitate phase is trapped down by the rapid cooling of the copper-mould. The detected lattice distortions in the dendrites are attributed to the strong solid solution strengthening of the metallic elements of Ti, Zr, Nb, and Ta. These lattice distortions increase the resistance of the dislocation motion and pin the dislocations, thus the strength and hardness of dendrite increase. Dendrites create a strong barrier for the shear band propagation and generate multiple shear bands after solid solution strengthening, thereby providing the TiZr-based BMGMCs with greatly improved capacity to sustain plastic deformation and resistance to brittle fracture. Thus, the TiZr-based BMGMCs possess distinguished work-hardening capability. Among these TiZr-based BMGMCs, the sample Ta{sub 0.5} possesses the largest plastic strain (ε{sub p}) at 20.3% and ultimate strength (σ{sub max}) of 2613 MPa during compressive loading. In addition, the sample of Ta{sub 0.5} exhibits work-hardening up to an ultrahigh tensile strength of 1680 MPa during the tensile process, and then progressively

  17. The rapid cold hardening response of Collembola is influenced by thermal variability of the habitat

    Bahrndorff, Simon; Loeschcke, Volker; Pertoldi, Cino;


    environments, but a single species can also be found in diverse thermal habitats within its geographic distribution. 3. We compared the inherent cold shock tolerance and ability to rapidly cold-harden in three epedaphic, two near surface dwelling (hemiedaphic) and four euedaphic species of Collembola using...... a similar experimental approach for all species. Additionally we compared three populations of the epedaphic species, Orchesella cincta , sampled along a climatic gradient (Norway, Denmark, Italy). 4. Inherent cold shock tolerance was estimated as LT 50 by assaying cold shock survival following a 2 h...... exposure to a range of temperatures from 1 ° C to –12 ° C. Rapid cold-hardening (RCH) was induced by cooling individuals from 20 ° C to a temperature 7 ° C above the LT 50 during 80 min, followed by 1 h at the specific cold shock temperature, which was close to the LT 50 of the particular species. 5...

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

    Guo, M.X., E-mail: [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Sha, G., E-mail: [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)


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

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


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

  20. Influence of time of annealing on anneal hardening effect of a cast CuZn alloy

    Nestorović Svetlana


    Full Text Available Investigated cast copper alloy containing 8at%Zn of a solute. For comparison parallel specimens made from cast pure copper. Copper and copper alloy were subjected to cold rolling with different a final reduction of 30,50 and 70%. The cold rolled copper and copper alloy samples were isochronally and isothermally annealed up to recrystallization temperature. After that the values of hardness, strength and electrical conductivity were measured and X-ray analysis was performed. These investigations show that anneal hardening effect at alloys was attained under recrystallization temperature in the temperature range of 180-3000C, followed with an increase in hardness. The amount of strengthening increase with increasing degree of prior cold work. Also the X-ray analysis show the change of lattice parameter during annealing when anneal hardening effect was attained.

  1. Crystallization and hardening of poly(ethylene-co-vinyl acetate) mouthguards during routine use

    Kuwahara, Ryoko; Tomita, Ryotaro; Ogawa, Natsumi; Nakajima, Kazunori; Takeda, Tomotaka; Uehara, Hiroki; Yamanobe, Takeshi


    Mouthguards (MGs) made from poly(ethylene-co-vinyl acetate) (EVA) are widely used in contact sports to prevent injuries such as breaking teeth and lip lacerations and to reduce brain concussion. However, the changes in morphology and the molecular mobility of EVA, which can affect its physical properties during practical usage, have not been precisely examined. Therefore, we attempted to determine the main factors which lead to changes in MG performance after one season of practical use by high school rugby players. Solid-state nuclear magnetic resonance (NMR) and pulse NMR measurements showed the hardening of MGs, which was associated with an increased crystallinity of the EVA resulting from prolonged usage. Furthermore, our data indicated that the increase in the relative amount of the crystalline phase may be primarily attributed to temperature fluctuations and repeated changes in pressure, which could cause the hardening of EVA and eventually diminish the protective ability of MGs. PMID:28294184

  2. Susceptibility and hardening of electronic systems to fast transient threats: new challenges ahead

    F. Sabath


    Full Text Available The field of susceptibility and hardening of electronic systems to transient threats has experienced a significant growth during the past ten years. Driven by the development in the area of non-lethal electromagnetic weapons it has become necessary to extend the classical set of transient threats, consisting of LEMP, ESD and NEMP, by a fast transient threat with an extreme bandwidth. The investigation of the susceptibility to those UWB threats, characterized by a bandwidth of more than a quarter of the center frequency, rise times of less than 200 ps and pulse durations in the ns regime, is of special interest. This paper presents an overview of current challenges of the hardening against UWB threats. It discusses recent research trends in transient susceptibility measurements, protection concepts and methods of analysis.

  3. Strength Development and Microstructure of Hardened Cement Paste Blended with Red Mud

    PAN Zhihua; ZHANG Yanna; XU Zhongzi


    Red mud was activated to be a mineral admixture for Portland cement by means of heating at different elevated temperatures from 400 ℃ to 700 ℃. Results show that heating was ef-fective, among which thermal activation of red mud at 600 ℃ was most effective. Chemical analysis suggested that cement added with 600 ℃ thermally activated red mud yielded more calcium ion dur-ing the early stage of hydration and less at later stage in liquid phase of cement water suspension sys-tem, more combined water and less calcium hydroxide in its hardened cement paste. MIP measure-ment and SEM observation proved that the hardened cement paste had a similar total porosity and a less portion of large size pores hence a denser microstructure compared with that added with original red mud.

  4. The studies of irradiation hardening of stainless steel reactor internals under proton and xenon irradiation

    Xu, Chaoliang; Zhang, Lu; Qian, Wangjie; Mei, Jinna; Liu, Xiang Bing [Suzhou Nuclear Power Research Institute, Suzuhou (China)


    Specimens of stainless steel reactor internals were irradiated with 240 keV protons and 6 MeV Xe ions at room temperature. Nanoindentation constant stiffness measurement tests were carried out to study the hardness variations. An irradiation hardening effect was observed in proton- and Xe-irradiated specimens and more irradiation damage causes a larger hardness increment. The Nix-Gao model was used to extract the bulk-equivalent hardness of irradiation-damaged region and critical indentation depth. A different hardening level under H and Xe irradiation was obtained and the discrepancies of displacement damage rate and ion species may be the probable reasons. It was observed that the hardness of Xe-irradiated specimens saturate at about 2 displacement/atom (dpa), whereas in the case of proton irradiation, the saturation hardness may be more than 7 dpa. This discrepancy may be due to the different damage distributions.

  5. The microstructure of neutron irradiated type-348 stainless steel and its relation to creep and hardening

    Thomas, L. E.; Beeston, J. M.


    Annealed type-348 stainless steel specimens irradiated to 33 to 39 dpa at 350°C were examined by transmission electron microscopy to determine the cause of pronounced irradiation creep and hardening. The irradiation produced very high densities of 1-2 nm diameter helium bubbles, 2-20 nm diameter faulted (Frank) dislocation loops and 10 nm diameter precipitate particles. These defects account for the observed irradiation hardening but do not explain the creep strains. Too few point defects survive as faulted dislocation loops for significant creep by the stress-induced preferential absorption (SIPA) mechanism and there are not enough unfaulted dislocations for creep by climb-induced glide. Also, the irradiation-induced precipitates are face-centred cubic G-phase (a niobium nickel suicide), and cannot cause creep. It is suggested that the irradiation creep occurs by a grain-boundary movement mechanism such as diffusion accomodated grain-boundary sliding.

  6. Pengaruh Media Pendingin Pada Proses Hardening Terhadap Strukturmikro Baja Mangan Hadfield AISI 3401 PT Semen Gresik

    Mohammad Ismanhadi Syahputra


    Full Text Available Baja Mangan Hadfield termasuk dalam kategori baja mangan austenitic dengan kandungan Mn (mangan yang tinggi, antara 12-14% Mn dan 0.8-1.25% C. Baja mangan hadfield memiliki kekerasan, kekuatan, ketangguhan, serta ketahanan terhadap aus yang tinggi. Proses hardening diberikan dengan melakukan pendinginan yang relatif cepat dengan menggunakan media pendingin air, oli, polivinylalcohol 10%, dan polyvinylalcohol 40% bertujuan untuk mendapatkan nilai kekerasan yang lebih tinggi yakni dengan pendinginan air 275VHN sedangkan tanpa perlakuan 206VHN. Viskositas dari media pendingin yang berbeda-beda berpengaruh terhadap laju pendinginan pada baja mangan hadifield.. Jenis media pendingin yang bervariasi mempengaruhi perubahan austenit menjadi martensit.  Strukturmikro yang terbentuk pada baja mangan hadfield yang mengalami proses hardening tampak butir-butir kristal yang seluruhnya martensit, sedangkan pada baja mangan hadfield yang tanpa mendapatkan perlakuan tampak karbida mangan lamellar dengan matriks austenit.

  7. Optimization strategy in end milling process for high speed machining of hardened die/mold steel


    An optimization strategy for high speed machining of hardened die/mold steel based on machining feature analysis was studied. It is a further extension of the previously presented study on the thermal mechanism of end milling and constant cutting force control. An objective function concerning machining cost and associated optimization algorithm based on machining time and cutting length calculation was proposed. Constraints to satisfy specific machining strategies when high speed machining the hardened die/mold steel, trochoid tool path pattern in slot end milling to avoid over-heat and feed rate adaptation to avoid over-load, were also discussed.As a case study, the tool selection problem when machining a die part with multiple machining features was investigated.

  8. Influence of degree of deformation in rolling on anneal hardening effect of a cast copper alloy

    Svetlana Nestorovic; Desimir Markovic; Ljubica Ivanic


    This paper reports results of investigations carried out on a cast copper alloy containing 8 at.% Al. The alloy, and pure copper for the sake of comparison, were subjected to cold rolling with a final reduction of 30, 50 or 70%. The cold rolled copper and copper alloy samples were isochronally and isothermally annealed up to the recrystallization temperature. The hardness, strength and electrical conductivity were measured and X-ray and DSC analyses performed. Anneal hardening effect was observed in the alloy in the temperature range 180–300°C, followed by an increase in the electrical conductivity. The amount of strengthening increases with increasing degree of prior cold work. The X-ray analysis shows a change in the lattice parameter during annealing when anneal hardening effect was observed. The DSC analysis shows the exothermic character of this effect.

  9. Comparative Life Cycle Cost Analysis of Hardening Options for Critical Loads

    Sungmin Park


    Full Text Available In order to determine the most cost effective alternative among hardening options of power systems, the direct monetary benefits should be evaluated above all other things. Therefore, this paper presents a life-cycle cost model which describes total monetary costs experienced in annual time increments during the project with consideration for the time value of money. In addition, to minimize the risks associated with estimated cost errors due to uncertainties of input data, the stochastic input data are considered. Using the Monte Carlo method, the probabilities and cost ranges in the case studies can be predicted, in turn resulting in better decisions in the selection of hardening options which are cost effective.

  10. Manufacturing surface hardened components of 42CrMo4 by water-air spray cooling

    Gretzki, T.; Krause, C.; Frolov, I.; Hassel, T.; Nicolaus, M.; Bach, F.W. [Inst. of Materials Science, Leibniz Univ. Hannover, Garbsen (Germany); Kaestner, M.; Abo-Namous, O.; Reithmeier, E. [Inst. of Measurement and Control Engineering, Leibniz Univ. Hannover (Germany); National Metallurgical Academy of Ukraine, Dniepropetrovsk (Ukraine)


    By employing integrated heat-treatment using forging heat, a significant shortening of the process chain is attained for manufacturing precision forged components with considerable savings in time and energy. With the aid of water-air spray cooling, surface hardening and tempering can be carried out without, at the same time, reheating the component following quenching. In this work, geometric models of splines and single cylinder crankshafts (both made of 1.7225) were surface hardened and tempered using a purpose-built rotating spray unit The obtained hardness, microstructures and their distortions were investigated. To optically and spatially detect the components, fringe and shadow projection systems were employed. In a second research topic, the influence of the spray parameters on the component's distortion was investigated. For both components; the splined shaft and the crankshaft geometries, it was possible to carry out successful surface heat-treatments using these processes. (orig.)

  11. Embrittlernent of irradiated F82H in the absence of irradiation hardening

    Klueh, Ronald L [ORNL; Shiba, Kiyoyuki [ORNL; Sokolov, Mikhail A [ORNL


    Neutron irradiation of 7-12% Cr ferritic/martensitic steels below 425-450 C produces microstructural defects and precipitation that cause an increase in yield stress. This irradiation hardening causes embrittlement, which is observed in a Charpy impact or fracture toughness test as an increase in the ductile-brittle transition temperature. Based on observations that show little change in strength in steels irradiated above 425-450 C, the general conclusion has been that no embrittlement occurs above these temperatures. In a recent study of F82H steel, significant embrittlement was observed after irradiation at 500 C. This embrittlement is apparently due to irradiation-accelerated Laves-phase precipitation. Observations of the embrittlement in the absence of hardening has been examined and analyzed with thermal-aging studies and computational thermodynamics calculations to illuminate and understand the effect.

  12. Cosmic ray spectral hardening due to dispersion of source injection spectra

    Yuan, Qiang; Bi, Xiao-Jun


    The cosmic ray (CR) energy spectra measured with ATIC, CREAM and PAMELA showed that there is remarkable hardening for rigidity of several hundred GV. We propose that this hardening is due to the superposition of spectra from a population of sources, e.g., supernova remnants (SNRs), whose injection spectral indices have a dispersion. Adopting proper model parameters the observational data can be well explained. It is interesting that the injection source parameters are similar with that derived from gamma-ray observations of SNRs, which may support the SNR-origin of CRs. Furthermore this mechanism provides an alternative explanation of the "ankle-cutoff" structure of the ultra high energy CR spectra.

  13. Nearby supernova remnants and the cosmic-ray spectral hardening at high energies

    Thoudam, Satyendra


    Recent measurements of cosmic-ray spectra of several individual nuclear species by the CREAM, TRACER, and ATIC experiments indicate a change in the spectral index of the power laws at TeV energies. Possible explanations among others include non linear diffusive shock acceleration of cosmic-rays, different cosmic-ray propagation properties at higher and lower energies in the Galaxy and the presence of nearby sources. In this paper, we show that if supernova remnants are the main sources of cosmic rays in our Galaxy, the effect of the nearby remnants can be responsible for the observed spectral changes. Using a rigidity dependent escape of cosmic-rays from the supernova remnants, we explain the apparent observed property that the hardening of the helium spectrum occurs at relatively lower energies as compared to the protons and also that the spectral hardening does not persist beyond $\\sim (20-30)$ TeV energies.

  14. Application of the Single Hardening Model in the Finite Element Program ABAQUS

    Jakobsen, Kim Parsberg

    that several conceptual models, describing the non-linear and irreversible behaviour of soil, have been developed over the last three decades few of them are accessible in commercial finite element programs. In the present study the Single Hardening Model, that is a time independent elastoplastic constitutive...... or in combined deformation and flow problems. Today, many of these problems are solved using various finite element computer softwares, capable of handling both geometric and material non-linearities. The latter is especially important in soil mechanics and soil-structure interaction problems. Despite the feat...... model, developed by Lade and Kim (Kim & Lade 1988, Lade & Kim 1988a, Lade & Kim 1988b) is implemented as a user defined material module, UMAT, in the commercial finite element program, ABAQUS. The advantages of the Single Hardening Model Iie in its ability to predict elastic and plastic displacements...

  15. Mathematical modeling of localized melting around graphite nodules during laser surface hardening of austempered ductile iron

    Roy, A.; Manna, I.


    An attempt has been made to mathematically predict the optimum conditions of laser surface hardening (LSH) of austempered ductile iron (ADI) that can ensure a predominantly martensitic microstructure and preclude partial/complete dissolution of graphite nodules in the laser hardened zone during laser irradiation. The exercise involves prediction of the thermal profile (using the Ashby and Easterling model), and consequently, the carbon diffusion profile around the graphite nodules at different depths from the surface for the given conditions of LSH. Microstructural investigations have been carried out by optical and scanning electron microscopy to study the morphology, shape and width of the partially/completely melted graphite nodules as a function of the LSH parameters. Finally, the predicted maximum width of the melted zone around the graphite nodules is compared with the relevant experimental data to validate the proposed model.

  16. Critical buckling strain in high strength steel pipes using isotropic kinematic hardening

    Fathi, A.; Roger Cheng, J. J.; Adeeb, Samer [Department of Civil and Environmental Engineering, University of Alberta (Canada); Zhou, Joe [TransCanada Pipelines Ltd. (Canada)


    In the natural gas sector, the use of high strength steel pipelines (HSSP) to transport huge volumes over long distances is increasing as it yields important savings in both capital and operational expenditures. In order to design HSSP, the critical buckling strain as to be taken into consideration but the models so far developed have been for isotropic materials while important material anisotropy is observed on HSSP due to their manufacturing process. The paper presents a model to assess the critical buckling strain of HSSP. An isotropic-kinematic hardening material model was developed and isotropic and anisotropic models were used to simulate pressurized and non-pressurized HSSP and were compared to test results. Results showed that the isotropic model is not suitable for predicting the buckling strain of HSSP but that the isotropic-kinematic hardening material model is. A model to better predict the buckling strain of HSSP was developed and successfully tested herein.

  17. Influence of silica-based hybrid material on the gas permeability of hardened cement paste

    Li, R.; Hou, P.; Xie, N.; Zhou, Z.; Cheng, X.


    Surface treatment is one of the most effective ways to elongate the service life of concrete. The surface treatment agents, including organic and inorganic types, have been intensively studied. In this paper, the silica-based hybrid nanocomposite, which take advantages of both organic and inorganic treatment agents, was synthesized and used for surface treatment of hardened cement-based material. The effectiveness of organic and inorganic hybrid nanocomposite was evaluated through investigations on the gas permeability of cement-based materials. The results showed that SiO2/PMHS hybrid nanocomposite can greatly decrease the gas transport properties of hardened cement-based materials and has a great potential for surface treatment of cementitious materials.

  18. Development of production methods of volume source by the resinous solution which has hardening

    Motoki, R


    Volume sources is used for standard sources by radioactive measurement using Ge semiconductor detector of environmental sample, e.g. water, soil and etc. that require large volume. The commercial volume source used in measurement of the water sample is made of agar-agar, and that used in measurement of the soil sample is made of alumina powder. When the plastic receptacles of this two kinds of volume sources were damaged, the leakage contents cause contamination. Moreover, if hermetically sealing performance of volume source made of agar-agar fell, volume decrease due to an evaporation off moisture gives an error to radioactive measurement. Therefore, we developed the two type methods using unsaturated polyester resin, vinilester resin, their hardening agent and acrylicresin. The first type is due to dispersing the hydrochloric acid solution included the radioisotopes uniformly in each resin and hardening the resin. The second is due to dispersing the alumina powder absorbed the radioisotopes in each resin an...

  19. Strain hardening rate sensitivity and strain rate sensitivity in TWIP steels

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


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

  20. Final report on LDRD project 52722 : radiation hardened optoelectronic components for space-based applications.

    Hargett, Terry W. (L& M Technologies, Inc.); Serkland, Darwin Keith; Blansett, Ethan L.; Geib, Kent Martin; Sullivan, Charles Thomas; Hawkins, Samuel D.; Wrobel, Theodore Frank; Keeler, Gordon Arthur; Klem, John Frederick; Medrano, Melissa R.; Peake, Gregory Merwin; Karpen, Gary D.; Montano, Victoria A. (L& M Technologies, Inc.)


    This report describes the research accomplishments achieved under the LDRD Project 'Radiation Hardened Optoelectronic Components for Space-Based Applications.' The aim of this LDRD has been to investigate the radiation hardness of vertical-cavity surface-emitting lasers (VCSELs) and photodiodes by looking at both the effects of total dose and of single-event upsets on the electrical and optical characteristics of VCSELs and photodiodes. These investigations were intended to provide guidance for the eventual integration of radiation hardened VCSELs and photodiodes with rad-hard driver and receiver electronics from an external vendor for space applications. During this one-year project, we have fabricated GaAs-based VCSELs and photodiodes, investigated ionization-induced transient effects due to high-energy protons, and measured the degradation of performance from both high-energy protons and neutrons.