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Sample records for advanced high strength

  1. Advanced high strength steels for automotive industry

    Directory of Open Access Journals (Sweden)

    Galán, J.

    2012-04-01

    Full Text Available The car industry is facing pressure because of the growing demand for more fuel-efficient passenger cars. In order to limit energy consumption and air pollution the weight of the carbody has to be reduced. At the same time, high levels of safety have to be guaranteed. In this situation, the choice of material becomes a key decision in car design. As a response to the requirements of the automotive sector, high strength steels and advanced high strength steels have been developed by the steel industry. These modern steel grades offer an excellent balance of low cost, light weight and mechanical properties.

    La industria del automóvil se enfrenta a una creciente demanda de vehículos de pasajeros más eficientes. Con el fin de disminuir el consumo de energía y la contaminación ambiental, el peso del vehículo tiene que ser reducido, al mismo tiempo que se garantizan altos niveles de seguridad. Ante esta situación, la elección de material se convierte en una decisión crucial en el diseño del vehículo. Como respuesta a las necesidades del sector automovilístico, nuevos aceros avanzados y de alta resistencia, han sido desarrollados por la industria siderúrgica. Dichos tipos de acero ofrecen un excelente equilibrio de precio, peso y propiedades mecánicas.

  2. Friction Stir Spot Welding of Advanced High Strength Steels

    Energy Technology Data Exchange (ETDEWEB)

    Hovanski, Yuri; Grant, Glenn J.; Santella, M. L.

    2009-11-13

    Friction stir spot welding techniques were developed to successfully join several advanced high strength steels. Two distinct tool materials were evaluated to determine the effect of tool materials on the process parameters and joint properties. Welds were characterized primarily via lap shear, microhardness, and optical microscopy. Friction stir spot welds were compared to the resistance spot welds in similar strength alloys by using the AWS standard for resistance spot welding high strength steels. As further comparison, a primitive cost comparison between the two joining processes was developed, which included an evaluation of the future cost prospects of friction stir spot welding in advanced high strength steels.

  3. Friction Stir Spot Welding of Advanced High Strength Steels

    Energy Technology Data Exchange (ETDEWEB)

    Santella, M. L.; Hovanski, Yuri; Grant, Glenn J.; Carpenter, Joseph A.; Warren, C. D.; Smith, Mark T.

    2008-12-28

    Experiments are continuing to evaluate the feasibility of friction stir spot welding advanced high-strength steels including, DP780, martensitic hot-stamp boron steel, and TRIP steels. Spot weld lap-shear strengths can exceed those required by industry standards such as AWS D8.1.

  4. Development of high strength high toughness third generation advanced high strength steels

    Science.gov (United States)

    Martis, Codrick John

    Third generation advanced high strength steels (AHSS's) are emerging as very important engineering materials for structural applications. These steels have high specific strength and thus will contribute significantly to weight reduction in automotive and other structural component. In this investigation two such low carbon low alloy steels (LCLA) with high silicon content (1.6-2wt %) has been developed. These two steel alloys were subjected to single step and two step austempering in the temperature range of 260-399°C to obtain desired microstructures and mechanical properties. Austempering heat treatment was carried out for 2 hours in a molten salt bath. The microstructures were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and optical metallography. Quantitative analysis was carried out by image analysis technique. The effect of austempering temperature on the mechanical properties of these two alloys was examined. The influence of microstructures on the mechanical properties of alloys was also studied. Austempering heat treatment resulted in fine carbide free bainitic ferrite and high carbon austenite microstructure in the samples austempered above Ms temperature, whereas tempered martensite and austenite microstructure was obtained in samples austempered below Ms temperature. Yield strength, tensile strength and fracture toughness were found to increase as the austempering temperature decreases, whereas ductility increases as the austempering temperature increases. Tensile strength in the range of 1276MPa -1658 MPa and the fracture toughness in the range of 80-141MPa√m were obtained in these two steels. Volume fractions of different phases present and their lath sizes are related to the mechanical properties. Austempered samples consisting of mixed microstructure of bainitic ferrite and tempered martensite phases resulted in the exceptional combination of strength and toughness.

  5. Advanced High Strength Steel in Auto Industry: an Overview

    OpenAIRE

    2014-01-01

    The world’s most common alloy, steel, is the material of choice when it comes to making products as diverse as oil rigs to cars and planes to skyscrapers, simply because of its functionality, adaptability, machine-ability and strength. Newly developed grades of Advanced High Strength Steel (AHSS) significantly outperform competing materials for current and future automotive applications. This is a direct result of steel’s performance flexibility, as well as of its many benefits in...

  6. Friction Stir Spot Welding of Advanced High Strength Steels

    Energy Technology Data Exchange (ETDEWEB)

    Hovanski, Yuri; Santella, M. L.; Grant, Glenn J.

    2009-12-28

    Friction stir spot welding was used to join two advanced high-strength steels using polycrystalline cubic boron nitride tooling. Numerous tool designs were employed to study the influence of tool geometry on weld joints produced in both DP780 and a hot-stamp boron steel. Tool designs included conventional, concave shouldered pin tools with several pin configurations; a number of shoulderless designs; and a convex, scrolled shoulder tool. Weld quality was assessed based on lap shear strength, microstructure, microhardness, and bonded area. Mechanical properties were functionally related to bonded area and joint microstructure, demonstrating the necessity to characterize processing windows based on tool geometry.

  7. Resistance spot welding and weldbonding of advanced high strength steels

    Energy Technology Data Exchange (ETDEWEB)

    Weber, G.; Gaul, H.; Rethmeier, M. [BAM Federal Institute for Materials Research and Testing, Berlin (Germany). Div. V.5 ' ' Safety of Joined Components' ' ; Thommes, H.; Hahn, O. [Paderborn Univ. (Germany). Fakultaet fuer Maschinenbau

    2010-11-15

    The resistance spot welding procedure is one of the most important joining techniques in lightweight car body shell mass production. Especially for newly developed high strength multiphase steels, also called advanced high strength steels (AHSS), and ultra high strength steels (UHSS), this joining technique has more advantages than other thermal and mechanical joining procedures for thin steel sheets. Additionally, the technique of adhesive bonding and its combination with the technique of resistance spot welding called weldbonding becomes more and more important. One of the targets of the contribution is to show the influence of joined advanced high strength steels on the process reliability for both the resistance spot welding process and the weldbonding process. Based on welding current ranges and on results of electrode wear tests, statements concerning the resistance spot weldability of some special AHSS will be given. The mechanical behaviour of spot welded and weldbonded joints for different AHSS will be studied. Furthermore, some statements regarding the fracture behaviour, the hardness and the fatigue behaviour of both spot welded and weldbonded joints for different AHSS will be given. Finally, some results on the mechanical properties of spot welded and weldbounded joints under corrosive attacks with be discussed. (orig.)

  8. Development of third generation advanced high strength steels

    Science.gov (United States)

    McGrath, Meghan Colleen

    Lightweight duplex steels with combinations of either bainite, acicular ferrite, and austenite or martensite and austenite were investigated as third generation advanced high strength steels targeted for automotive applications. Large additions of manganese (> 13 wt%) and carbon (Strength and ductility were increased while density was decreased with aluminum additions between 2.4 and 5.5 wt% to the steel. This research addressed the dependence of alloying on microstructures and mechanical behavior for high manganese and aluminum duplex steels that were cast and subsequently hot rolled. Duplex steels with different volume fractions of primary delta-ferrite were used to study the crystallography of austenite fanned during the peritectic reaction. Solute profiles across the peritectic interface showed aluminum segregated near the interface which promoted bainitic ferrite formation. Thermal treatments were used to manipulate the concentration and type of oxides and the ferrite plate density was found to correlate with inclusions of low misfit in steels with austenite grain size of 16.5 microm. A steel with bainite and acicular ferrite produced an ultimate tensile strength of 970 MPa and elongation of 40%. The mechanical prope1iies depended on the strengths and size of the microstructural constituents. Work hardening behavior was examined in a steel exhibiting multiple martensitic transformation induced plasticity (gamma-austenite→epsilon-smartensite→alpha-martensite). A strain hardening exponent as high as 1.4 was observed with ultimate tensile strength and elongation as high as 1,165 MPa and 34%.

  9. Hydrogen Embrittlement of Automotive Advanced High-Strength Steels

    Science.gov (United States)

    Lovicu, Gianfranco; Bottazzi, Mauro; D'Aiuto, Fabio; De Sanctis, Massimo; Dimatteo, Antonella; Santus, Ciro; Valentini, Renzo

    2012-11-01

    Advanced high-strength steels (AHSS) have a better combination between strength and ductility than conventional HSS, and higher crash resistances are obtained in concomitance with weight reduction of car structural components. These steels have been developed in the last few decades, and their use is rapidly increasing. Notwithstanding, some of their important features have to be still understood and studied in order to completely characterize their service behavior. In particular, the high mechanical resistance of AHSS makes hydrogen-related problems a great concern for this steel grade. This article investigates the hydrogen embrittlement (HE) of four AHSS steels. The behavior of one transformation induced plasticity (TRIP), two martensitic with different strength levels, and one hot-stamping steels has been studied using slow strain rate tensile (SSRT) tests on electrochemically hydrogenated notched samples. The embrittlement susceptibility of these AHSS steels has been correlated mainly to their strength level and to their microstructural features. Finally, the hydrogen critical concentrations for HE, established by SSRT tests, have been compared to hydrogen contents absorbed during the painting process of a body in white (BIW) structure, experimentally determined during a real cycle in an industrial plant.

  10. Guidelines for Stretch Flanging Advanced High Strength Steels

    Science.gov (United States)

    Sriram, S.; Chintamani, J.

    2005-08-01

    Advanced High Strength Steels (AHSS) are currently being considered for use in closure and structural panels in the automotive industry because of their high potential for affordable weight reduction and improved performance. AHSS such as dual phase steels are currently being used in some vehicle platforms. From a manufacturing perspective, stretch flanging during stamping is an important deformation mode requiring careful consideration of geometry and the die process. This paper presents some geometric and process guidelines for stretch flanging AHSS. Hole expansion experiments were conducted to determine the failure limit for a sheared edge condition. Effects of punching clearance, prestrain and prior strain path on hole expansion were explored in these experiments. In addition, dynamic explicit FE calculations using LS-DYNA were also conducted for a typical stretch flange by varying some key geometric parameters. The experimental and FEA results were then analyzed to yield process and geometric guidelines to enable successful stretch flanging of AHSS.

  11. Advanced High Strength Steel in Auto Industry: an Overview

    Directory of Open Access Journals (Sweden)

    N. Baluch

    2014-08-01

    Full Text Available The world’s most common alloy, steel, is the material of choice when it comes to making products as diverse as oil rigs to cars and planes to skyscrapers, simply because of its functionality, adaptability, machine-ability and strength. Newly developed grades of Advanced High Strength Steel (AHSS significantly outperform competing materials for current and future automotive applications. This is a direct result of steel’s performance flexibility, as well as of its many benefits including low cost, weight reduction capability, safety attributes, reduced greenhouse gas emissions and superior recyclability. To improve crash worthiness and fuel economy, the automotive industry is, increasingly, using AHSS. Today, and in the future, automotive manufacturers must reduce the overall weight of their cars. The most cost-efficient way to do this is with AHSS. However, there are several parameters that decide which of the AHSS types to be used; the most important parameters are derived from the geometrical form of the component and the selection of forming and blanking methods. This paper describes the different types of AHSS, highlights their advantages for use in auto metal stampings, and discusses about the new challenges faced by stampers, particularly those serving the automotive industry.

  12. Characteristics in Paintability of Advanced High Strength Steels

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ha Sun [POSLAB, POSCO, Gwangyang (Korea, Republic of)

    2007-06-15

    It is expected that advanced high strength steels (AHSS) would be widely used for vehicles with better performance in automotive industries. One of distinctive features of AHSS is the high value of carbon equivalent (Ceq), which results in the different properties in formability, weldability and paintability from those of common grade of steel sheets. There is an exponential relation between Ceq and electric resistance, which seems also to have correlation with the thickness of electric deposition (ED) coat. higher value of Ceq of AHSS lower the thickness of ED coat of AHSS. Some elements of AHSS such as silicon, if it is concentrated on the surface, affect negatively the formation of phosphates. In this case, silicon itself doesn't affect the phosphate, but its oxide does. This phenomenon is shown dramatically in the welding area. Arc welding or laser welding melts the base material. In the process of cooling of AHSS melt, the oxides of Si and Mn are easily concentrated on the surface of boundary between welded and non welded area because Si and Mn cold be oxidized easier than Fe. More oxide on surface results in poor phosphating and ED coating. This is more distinctive in AHSS than in mild steel. General results on paintability of AHSS would be reported, being compared to those of mild steel

  13. Numerical Design of Drawbeads for Advanced High Strength Steel Sheets

    Science.gov (United States)

    Keum, Y. T.; Kim, D. J.; Kim, G. S.

    2010-06-01

    The map for designing the drawbeads used in the stamping dies for advanced high strength steel (AHSS) sheets is numerically investigated and its application is introduced. The bending limit of AHSS sheet is determined from the extreme R/t's obtained simulating numerically the plane-strain process formed by the cylindrical punches and dies with various radii. In addition, the forming allowance defined by the difference between FLC0 and the strain after passing the drawbead, which is observed by the numerical simulation of drawbead pulling test, is computed. Based on the bending limit and forming allowance, the design map for determining the height, width, and shoulder radius of the drawbead which are key parameters in the drawbead design and depend on the restraining force is constructed by aid of the equivalent drawbead model. A drawbead of the stamping die for forming a channel-typed panel is designed by using the design map, and the formability and springback of the panel to be formed are numerically evaluated, from which the availability of the design map is demonstrated.

  14. Advanced Gear Alloys for Ultra High Strength Applications

    Science.gov (United States)

    Shen, Tony; Krantz, Timothy; Sebastian, Jason

    2011-01-01

    Single tooth bending fatigue (STBF) test data of UHS Ferrium C61 and C64 alloys are presented in comparison with historical test data of conventional gear steels (9310 and Pyrowear 53) with comparable statistical analysis methods. Pitting and scoring tests of C61 and C64 are works in progress. Boeing statistical analysis of STBF test data for the four gear steels (C61, C64, 9310 and Pyrowear 53) indicates that the UHS grades exhibit increases in fatigue strength in the low cycle fatigue (LCF) regime. In the high cycle fatigue (HCF) regime, the UHS steels exhibit better mean fatigue strength endurance limit behavior (particularly as compared to Pyrowear 53). However, due to considerable scatter in the UHS test data, the anticipated overall benefits of the UHS grades in bending fatigue have not been fully demonstrated. Based on all the test data and on Boeing s analysis, C61 has been selected by Boeing as the gear steel for the final ERDS demonstrator test gearboxes. In terms of potential follow-up work, detailed physics-based, micromechanical analysis and modeling of the fatigue data would allow for a better understanding of the causes of the experimental scatter, and of the transition from high-stress LCF (surface-dominated) to low-stress HCF (subsurface-dominated) fatigue failure. Additional STBF test data and failure analysis work, particularly in the HCF regime and around the endurance limit stress, could allow for better statistical confidence and could reduce the observed effects of experimental test scatter. Finally, the need for further optimization of the residual compressive stress profiles of the UHS steels (resulting from carburization and peening) is noted, particularly for the case of the higher hardness C64 material.

  15. Internal and External Oxidation of Manganese in Advanced High Strength Steels

    NARCIS (Netherlands)

    Aghaei Lashgari, V.

    2014-01-01

    Advanced high strength steels (AHSS) have been used extensively in the automotive industries. The main characteristic of these steels is combination of high strength and enhanced formability that makes them very attractive for automotive application. However, the major drawback of these steels is th

  16. A constitutive model for the anelastic behavior of Advanced High Strength Steels

    NARCIS (Netherlands)

    Torkabadi, A.; Liempt, van P.; Meinders, V.T.; Boogaard, van den A.H.

    2015-01-01

    In this work a physically based model describing the anelastic behaviour and nonlinear unloading in Advanced High Strength Steels (AHSS) is proposed. The model is fitted to the experimental data obtained from uni-axial tests on a dual-phase high strength steel grade (HCT780). The results show a good

  17. Investigation of the Failure of Advanced High Strength Steels Heterogeneous Spot Welds

    OpenAIRE

    Thibaut Huin; Sylvain Dancette; Damien Fabrègue; Thomas Dupuy

    2016-01-01

    Nowadays, environmental regulation encourages carmakers to reduce the global vehicle weight. Steelmakers develop grades with high performance (Advanced High Strength Steels, AHSS) and fine steel sheet assemblies are used in car body structures, with an optimized thickness in each part. However, unusual fracture modes are sometimes observed during the mechanical tests of heterogeneous AHSS welds, made of dissimilar steel grades and sheet thicknesses. Weld fractures can occur with a strength lo...

  18. Tensile and Spring-Back Behavior of DP600 Advanced High Strength Steel at Warm Temperatures

    Institute of Scientific and Technical Information of China (English)

    F Ozturk; S Toros; S Kilic

    2009-01-01

    In recent years, the use of advanced high strength steels in automotive industry has been increased remark-ably. Among advanced high strength steels, dual phase (DP)steels have gained a great attention owing to a combi-nation of high strength and good formability. However, high strength usually increases the spring-back behavior of the material, which creates problems for the parts during the assembly. Thus, the uniaxial tensile deformation and spring-back behaviors of DP600 advanced high strength steel were investigated in rolling (0°), diagonal (45°), and transverse (90°)directions in the temperature range from room temperature (RT)to 300 ℃. All tests were per-formed at a deformation speed of 25 mm/min. A V-shaped die (60°)was used for the spring-back measurements. The results indicated that the formability and spring-back of the material were decreased with increasing the tempera-tures. The material showed complex behaviors in different directions and at different temperatures.

  19. Formability Analysis of Diode-Laser-Welded Tailored Blanks of Advanced High-Strength Steel Sheets

    Science.gov (United States)

    Panda, S. K.; Baltazar Hernandez, V. H.; Kuntz, M. L.; Zhou, Y.

    2009-08-01

    Currently, advances due to tailored blanking can be enhanced by the development of new grades of advanced high-strength steels (HSSs), for the further weight reduction and structural improvement of automotive components. In the present work, diode laser welds of three different grades of advanced high-strength dual-phase (DP) steel sheets (with tensile strengths of 980, 800, and 450 MPa) to high-strength low-alloy (HSLA) material were fabricated by applying the proper welding parameters. Formability in terms of Hecker’s limiting dome height (LDH), the strain distribution on the hemispherical dome surface, the weld line movement during deformation, and the load-bearing capacity during the stretch forming of these different laser-welded blanks were compared. Finite element (FE) analysis of the LDH tests of both the parent metals and laser-welded blanks was done using the commercially available software package LS-DYNA (Livermore Software Technology Corporation, Livermore, CA); the results compared well with the experimental data. It was also found that the LDH was not affected by the soft zone or weld zone properties; it decreased, however, with an increase in a nondimensional parameter, the “strength ratio” (SR). The weld line movement during stretch forming is an indication of nonuniform deformation resulting in a decrease in the LDH. In all the dissimilar weldments, fracture took place on the HSLA side, but the fracture location shifted to near the weld line (at the pole) in tailor-welded blanks (TWBs) of a higher strength ratio.

  20. Properties of Galvanized and Galvannealed Advanced High Strength Hot Rolled Steels

    Energy Technology Data Exchange (ETDEWEB)

    V.Y. Guertsman; E. Essadiqi; S. Dionne; O. Dremmailova; R. Bouchard; B. Voyzelle; J. McDermid; R. Fourmentin

    2008-04-01

    The objectives of the project were (i) to develop the coating process information to achieve good quality coatings on 3 advanced high strength hot rolled steels while retaining target mechanical properties, (ii) to obtain precise knowledge of the behavior of these steels in the various forming operations and (iii) to establish accurate user property data in the coated conditions. Three steel substrates (HSLA, DP, TRIP) with compositions providing yield strengths in the range of 400-620 MPa were selected. Only HSLA steel was found to be suitable for galnaizing and galvannealing in the hot rolled condition.

  1. Microstructural effects on the springback of advanced high-strength steel

    Science.gov (United States)

    Gan, Wei; Babu, S. S.; Kapustka, Nick; Wagoner, Robert H.

    2006-11-01

    The application of advanced high-strength steels (AHSS) has been growing rapidly in the automotive industry. Because of their high-strength, thinner sheet metals can be used for body components to achieve both weight savings and increased safety. However, this will lead to greater springback deviation from design after the forming operation. Fundamental understanding and prediction of springback are required for springback compensation and tooling design. While various types of continuum mechanics based models have been proposed to simulate the mechanical behavior of advanced high-strength steels, few of them consider microstructural effects such as material heterogeneity. In this study, through sheet thickness strength variation has been observed in DP 780 and TRIP 780 steels. Finite-element simulation indicates that the through thickness effect (TTE) can have a significant impact on the springback behavior of these sheet metals. This is verified through our experimental work using draw-bend testing. The results suggest that microstructural effects should be considered to accurately simulate springback of AHSS. Based on these results, implications of different microstructural designs will be discussed.

  2. Measurements of Bauschinger effect and transient behavior of a quenched and partitioned advanced high strength steel

    Energy Technology Data Exchange (ETDEWEB)

    Zang, Shun-lai, E-mail: shawn@mail.xjtu.edu.cn [School of Mechanical Engineering, Xi' an Jiaotong University, No. 28, Xianning Road, Xi' an, Shaanxi (China); Sun, Li [Manufacturing Process Research, General Motors China Science Lab, No. 56, Jinwan Road, Shanghai (China); Niu, Chao [School of Mechanical Engineering, Xi' an Jiaotong University, No. 28, Xianning Road, Xi' an, Shaanxi (China)

    2013-12-01

    In recent decades, the needs for new advanced high strength steels (AHSS) with high ductility and strength have rapidly increased to achieve the targets of more fuel-efficient and safer vehicles in automotive industry. However, several undesirable phenomena are experimentally observed during the forming of such materials, particularly with complex loading and large plastic deformation. Springback is one of the most important problems that should be compensated in sheet metal forming process. In this paper, we investigated the hardening behavior of a Q and P (quench and partitioning) steel designated by QP980CR, which is a new third generation advance high strength steel, from the Baosteel Group Corp. in Shanghai, China. The uni-axial tensile and cyclic simple shear tests were conducted. The uni-axial tensile tests were performed on the specimens at 0°, 45° and 90° to rolling direction (RD). The flow stress and transverse strain evolution were obtained in view of the digital image correlation (DIC) measurement. The plastic anisotropy was optimized from the uni-axial tensile tests and thereafter incorporated into the simulations of cyclic simple shear tests. The cyclic simple shear tests were conducted with three prestrains to measure the Bauschinger effect, transient behavior and permanent softening, and to determine the material parameters of the combined isotropic-kinematic hardening model.

  3. Investigation on dissimilar laser welding of advanced high strength steel sheets for the automotive industry

    Energy Technology Data Exchange (ETDEWEB)

    Rossini, M., E-mail: matteo.rossini@unibz.it [Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, 39100 Bolzano (Italy); Spena, P. Russo, E-mail: pasquale.russospena@unibz.it [Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, 39100 Bolzano (Italy); Cortese, L., E-mail: luca.cortese@unibz.it [Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, 39100 Bolzano (Italy); Matteis, P., E-mail: paolo.matteis@polito.it [Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Firrao, D., E-mail: donato.firrao@polito.it [Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

    2015-03-25

    To support the use of advanced high strength steels in car body design and fabrication, an investigation was carried out on dissimilar butt laser welding between TWinning Induced Plasticity (TWIP) steels, Dual Phase (DP) steels, hot stamping boron (22MnB5) steels, and TRansformation Induced Plasticity (TRIP) steels. The base materials and the weldments were fully characterized by means of metallography, microhardness, and tensile tests. Digital image analysis was also used to provide additional information on the local strain field in the joint during the tensile tests. Fractographic examination was finally performed on the fracture surfaces of the tensile samples. The dissimilar joints between the DP, 22MnB5, and TRIP steels exhibit good resistance properties. On the contrary, the dissimilar joints encompassing the TWIP steel exhibit poor mechanical strength and fail along the weld seam by intergranular fracture, probably due to presence of Mn segregations. Therefore, the laser welding of TWIP steel with other advanced high strength steels is not recommended without the use of proper metal fillers. Dissimilar laser welding of DP, TRIP and 22MnB5 combinations, on the contrary, can be a solution to assemble car body parts made of these steel grades.

  4. Friction Stir Spot Welding (FSSW) of Advanced High Strength Steel (AHSS)

    Energy Technology Data Exchange (ETDEWEB)

    Santella, M. L.; Hovanski, Yuri; Pan, Tsung-Yu

    2012-04-16

    Friction stir spot welding (FSSW) is applied to join advanced high strength steels (AHSS): galvannealed dual phase 780 MPa steel (DP780GA), transformation induced plasticity 780 MPa steel (TRIP780), and hot-stamped boron steel (HSBS). A low-cost Si3N4 ceramic tool was developed and used for making welds in this study instead of polycrystalline cubic boron nitride (PCBN) material used in earlier studies. FSSW has the advantages of solid-state, low-temperature process, and the ability of joining dissimilar grade of steels and thicknesses. Two different tool shoulder geometries, concave with smooth surface and convex with spiral pattern, were used in the study. Welds were made by a 2-step displacement control process with weld time of 4, 6, and 10 seconds. Static tensile lap-shear strength achieved 16.4 kN for DP780GA-HSBS and 13.2kN for TRIP780-HSBS, above the spot weld strength requirements by AWS. Nugget pull-out was the failure mode of the joint. The joining mechanism was illustrated from the cross-section micrographs. Microhardness measurement showed hardening in the upper sheet steel (DP780GA or TRIP780) in the weld, but softening of HSBS in the heat-affect zone (HAZ). The study demonstrated the feasibility of making high-strength AHSS spot welds with low-cost tools.

  5. On Simulation of Edge Stretchability of an 800MPa Advanced High Strength Steel

    Science.gov (United States)

    Pathak, Nikky; Butcher, Cliff; Worswick, Michael

    2016-08-01

    In the present work, the edge stretchability of advanced high strength steel (AHSS) was investigated experimentally and numerically using both a hole expansion test and a tensile specimen with a central hole. The experimental fracture strains obtained using the hole expansion and hole tension test in both reamed and sheared edge conditions were in very good agreement, suggesting the tests are equivalent for fracture characterization. Isotropic finite-element simulations of both tests were performed to compare the stress-state near the hole edge.

  6. Strain Rate and Temperature Effects on the Formability and Damage of Advanced High-Strength Steels

    Science.gov (United States)

    Winkler, S.; Thompson, A.; Salisbury, C.; Worswick, M.; van Riemsdijk, I.; Mayer, R.

    2008-06-01

    In order to understand the crashworthiness and formability of advance high-strength steels, the effects of strain rate and temperature on the constitutive response of DP 600 and DP 780 steel tubes were investigated and compared with commercial drawing quality (DQ) and high strength low alloy (HSLA) 350 steel tubes. Uniaxial tensile tests were conducted at quasi-static (QS) (0.003 and 0.1 s-1), intermediate (30 and 100 s-1), and high (500, 1000, and 1500 s-1) strain rates using an Instron, instrumented falling weight impact tester and tensile split Hopkinson bar (TSHB) apparatus, respectively. Elevated temperature tests at 150 °C and 300 °C were also conducted at high strain rates. Following testing, metallography and microscopy techniques were used for material and damage characterization. The results obtained show that the steels studied exhibit a positive strain rate sensitivity. Compared to DQ and HSLA 350, the DP steels were found to have less formability at QS rates but enhanced formability at higher strain rates. A decrease in strength and ductility was measured with increasing temperature for the DP steels, indicating a reduction in energy adsorption due to adiabatic heating during a crash event.

  7. Application of advanced high strength hot-rolled steels to automotive chassis parts

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Y.R.; Kim, H.G.; Chin, K.G. [Technical Research Lab., POSCO (Korea); Lee, W.S. [Advanced Technology Dept., Hyundai MOBIS, Yongin (Korea); Kwon, T.W. [Hwashin Co. Ltd., Yeongcheon (Korea)

    2005-07-01

    With social demand of automobiles that provide higher fuel efficiency, safety in collisions, the steel makers are tackling the needs of the auto industry by developing higher performance materials such as AHSS (advanced high strength steels). From this point of view, DP and FB (ferrite-bainite) steels have received considerable attention because of their good strength and formability relationship. The results of application with the AHSS on chassis parts were compared with the conventional steels of 370 or 440MPa grade steels. 590DP steel has good press formability due to higher n value and lower yield strength. Fatigue durability of chassis assembly was increased due to the strength and bake hardening effects in spite of thickness reduction. The damping capacity of chassis components increased more than 2 times comparing with conventional steels. With 540 and 590FB steels which have excellent stretch flangeability, the validity were proved by successful press forming and weight reduction of arms as well as increased fatigue durability. (orig.)

  8. A New Perspective on Fatigue Performance of Advanced High- Strength Steels (AHSS) GMAW Joints

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhili [ORNL; Chiang, Dr. John [Ford Motor Company; Kuo, Dr. Min [MIttal Steel; Jiang, Cindy [AET Integration, Inc; Sang, Yan [AET Integration, Inc

    2008-01-01

    Weld fatigue performance is a critical aspect for application of advanced high-strength steels (AHSS) in automotive body structures. A comparative study has been conducted to evaluate the fatigue life of AHSS welds. The material studied included seven AHSS of various strength levels - DP 600, DP 780, DP 980, M130, M220, solution annealed boron and fully hardened boron steels. Two conventional steels, HSLA 590 and DR 210, were also included for baseline comparison. Lap fillet welds were made on 2-mm nominal thick sheets by the gas metal arc welding process (GMAW). Fatigue test was conducted under a number of stress levels to obtain the S/N curves of the weld joints. It was found that, unlike in the static and impact loading conditions, the fatigue performance of AHSS is not influenced by the HAZ softening in AHSS. There are appreciable differences in the fatigue lives among different AHSS. Changes in weld parameters can influence the fatigue life of the weld joints, particularly of these of higher strength AHSS. A model is developed to predict the fatigue performance of AHSS welds. The validity of the model is benchmarked with the experimental results. This model is capable to capture the effects of weld geometry and weld microstructure and strength on the fatigue performance experimentally observed. The theoretical basis and application of the newly developed fatigue modeling methodology will be discussed.

  9. Analysis of particle size and interface effects on the strength and ductility of advanced high strength steels

    Science.gov (United States)

    Ettehad, Mahmood

    This thesis is devoted to the numerical investigation of mechanical behavior of Dual phase (DP) steels. Such grade of advanced high strength steels (AHSS) is favorable to the automotive industry due the unique properties such as high strength and ductility with low finished cost. Many experimental and numerical studies have been done to achieve the optimized behavior of DP steels by controlling their microstructure. Experiments are costly and time consuming so in recent years numerical tools are utilized to help the metallurgist before doing experiments. Most of the numerical studies are based on classical (local) constitutive models where no material length scale parameters are incorporated in the model. Although these models are proved to be very effective in modeling the material behavior in the large scales but they fail to address some critical phenomena which are important for our goals. First, they fail to address the size effect phenomena which materials show at microstructural scale. This means that materials show stronger behavior at small scales compared to large scales. Another issue with classical models is the mesh size dependency in modeling the softening behavior of materials. This means that in the finite element context (FEM) the results will be mesh size dependent and no converged solution exist upon mesh refinement. Thereby by applying the classical (local) models one my loose the accuracy on measuring the strength and ductility of DP steels. Among the non-classical (nonlocal) models, gradient-enhanced plasticity models which consider the effect of neighboring point on the behavior of one specific point are proved to be numerically effective and versatile tools to accomplish the two concerns mentioned above. So in this thesis a gradient-enhanced plasticity model which incorporates both the energetic and dissipative material length scales is derived based on the laws of thermodynamics. This model also has a consistent yield-like function for the

  10. Influence of Manufacturing Processes and Microstructures on the Performance and Manufacturability of Advanced High Strength Steels

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoo Sil; Liu, Wenning N.; Sun, Xin; Khaleel, Mohammad A.

    2009-10-01

    Advanced high strength steels (AHSS) are performance-based steel grades and their global material properties can be achieved with various steel chemistries and manufacturing processes, leading to various microstructures. In this paper, we investigate the influence of supplier variation and resulting microstructure difference on the overall mechanical properties as well as local formability behaviors of advanced high strength steels (AHSS). For this purpose, we first examined the basic material properties and the transformation kinetics of TRansformation Induced Plasticity (TRIP) 800 steels from three different suppliers under different testing temperatures. The experimental results show that there is a significant supplier (i.e., manufacturing process) dependency of the TRIP 800 steel mechanical and microstructure properties. Next, we examined the local formability of two commercial Dual Phase (DP) 980 steels during stamping process. The two commercial DP 980 steels also exhibit noticeably different formability during stamping process in the sense that one of them shows severe tendency for shear fracture. Microstructure-based finite element analyses are carried out next to simulate the localized deformation process with the two DP 980 microstructures, and the results suggest that the possible reason for the difference in formability lies in the morphology of the hard martensite phase in the DP microstructure.

  11. Correlation of microstructure, tensile properties and hole expansion ratio in cold rolled advanced high strength steels

    Science.gov (United States)

    Terrazas, Oscar R.

    The demand for advanced high strength steels (AHSS) with higher strengths is increasing in the automotive industry. While there have been major improvements recently in the trade-off between ductility and strength, sheared-edge formability of AHSS remains a critical issue. AHSS sheets exhibit cracking during stamping and forming operations below the predictions of forming limits. It has become important to understand the correlation between microstructure and sheared edge formability. The present work investigates the effects of shearing conditions, microstructure, and tensile properties on sheared edge formability. Seven commercially produced steels with tensile strengths of 1000 +/- 100 MPa were evaluated: five dual-phase (DP) steels with different compositions and varying microstructural features, one trip aided bainitic ferrite (TBF) steel, and one press-hardened steel tempered to a tensile strength within the desired range. It was found that sheared edge formability is influenced by the martensite in DP steels. Quantitative stereology measurements provided results that showed martensite size and distribution affect hole expansion ratio (HER). The overall trend is that HER increases with more evenly dispersed martensite throughout the microstructure. This microstructure involves a combination of martensite size, contiguity, mean free distance, and number of colonies per unit area. Additionally, shear face characterization showed that the fracture and burr region affect HER. The HER decreases with increasing size of fracture and burr region. With a larger fracture and burr region more defects and/or micro-cracks will be present on the shear surface. This larger fracture region on the shear face facilitates cracking in sheared edge formability. Finally, the sheared edge formability is directly correlated to true fracture strain (TFS). The true fracture strain from tensile samples correlates to the HER values. HER increases with increasing true fracture strain.

  12. Creep Strength of Dissimilar Welded Joints Using High B-9Cr Steel for Advanced USC Boiler

    Science.gov (United States)

    Tabuchi, Masaaki; Hongo, Hiromichi; Abe, Fujio

    2014-10-01

    The commercialization of a 973 K (700 °C) class pulverized coal power system, advanced ultra-supercritical (A-USC) pressure power generation, is the target of an ongoing research project initiated in Japan in 2008. In the A-USC boiler, Ni or Ni-Fe base alloys are used for high-temperature parts at 923 K to 973 K (650 °C to 700 °C), and advanced high-Cr ferritic steels are planned to be used at temperatures lower than 923 K (650 °C). In the dissimilar welds between Ni base alloys and high-Cr ferritic steels, Type IV failure in the heat-affected zone (HAZ) is a concern. Thus, the high B-9Cr steel developed at the National Institute for Materials Science, which has improved creep strength in weldments, is a candidate material for the Japanese A-USC boiler. In the present study, creep tests were conducted on the dissimilar welded joints between Ni base alloys and high B-9Cr steels. Microstructures and creep damage in the dissimilar welded joints were investigated. In the HAZ of the high B-9Cr steels, fine-grained microstructures were not formed and the grain size of the base metal was retained. Consequently, the creep rupture life of the dissimilar welded joints using high B-9Cr steel was 5 to 10 times longer than that of the conventional 9Cr steel welded joints at 923 K (650 °C).

  13. New tribo-systems for sheet metal forming of advanced high strength steels and stainless steels

    DEFF Research Database (Denmark)

    Ceron, Ermanno

    the reluctance of industry in the application of new solutions, due to the high trial costs. This project presents a new methodology for testing new environmentally friendly tribo-systems for sheet metal forming of advanced high strength steels and stainless steels. For the purpose, a new Universal Sheet......The environmental issue, concerning the lubrication in sheet metal forming, has become considerably important in the past 10 years. Besides the fact that legislation is becoming more restrictive on the type of lubricant industry is allowed to use, many companies are embracing the path of social...... responsibility and sustainability, which implies a careful application of environmentally friendly technology. On the other hand the global market requires more and more complex products, which ignites a chain reaction that affects the whole life cycle of the product. Regarding sheet metal forming, this means...

  14. Hot ductility behavior of a low carbon advanced high strength steel (AHSS) microalloyed with boron

    Energy Technology Data Exchange (ETDEWEB)

    Mejia, I., E-mail: imejia@umich.mx [Instituto de Investigaciones Metalurgicas, Universidad Michoacana de San Nicolas de Hidalgo, Edificio ' U' , Ciudad Universitaria, 58066 Morelia, Michoacan (Mexico); Bedolla-Jacuinde, A.; Maldonado, C. [Instituto de Investigaciones Metalurgicas, Universidad Michoacana de San Nicolas de Hidalgo, Edificio ' U' , Ciudad Universitaria, 58066 Morelia, Michoacan (Mexico); Cabrera, J.M. [Departament de Ciencia dels Materials i Enginyeria Metal.lurgica, ETSEIB - Universitat Politecnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Fundacio CTM Centre Tecnologic, Av. de las Bases de Manresa 1, 08240 Manresa (Spain)

    2011-05-25

    Research highlights: {yields} Effect of boron on the hot ductility behavior of a low carbon NiCrVCu AHSS. {yields} Boron addition of 117 ppm improves hot ductility over 100% in terms of RA. {yields} Hot ductility improvement is associated with segregation/precipitation of boron. {yields} Typical hot ductility recovery at lower temperatures does not appear in this steel. {yields} Hot ductility loss is associated with precipitates/inclusions coupled with voids. - Abstract: The current study analyses the influence of boron addition on the hot ductility of a low carbon advanced high strength NiCrVCu steel. For this purpose hot tensile tests were carried out at different temperatures (650, 750, 800, 900 and 1000 deg. C) at a constant true strain rate of 0.001 s{sup -1}. Experimental results showed a substantial improvement in hot ductility for the low carbon advanced high strength steel when microalloyed with boron compared with that without boron addition. Nevertheless, both steels showed poor ductility when tested at the lowest temperatures (650, 750 and 800 deg. C), and such behavior is associated to the precipitation of vanadium carbides/nitrides and inclusions, particularly MnS and CuS particles. The fracture mode of the low carbon advanced high strength steel microalloyed with boron seems to be more ductile than the steel without boron addition. Furthermore, the fracture surfaces of specimens tested at temperatures showing the highest ductility (900 and 1000 deg. C) indicate that the fracture mode is a result of ductile failure, while in the region of poor ductility the fracture mode is of the ductile-brittle type failure. It was shown that precipitates and/or inclusions coupled with voids play a meaningful role on the crack nucleation mechanism which in turn causes a hot ductility loss. Likewise, dynamic recrystallization (DRX) which always results in restoration of ductility only occurs in the range from 900 to 1000 deg. C. Results are discussed in terms of

  15. Investigation of the Failure of Advanced High Strength Steels Heterogeneous Spot Welds

    Directory of Open Access Journals (Sweden)

    Thibaut Huin

    2016-05-01

    Full Text Available Nowadays, environmental regulation encourages carmakers to reduce the global vehicle weight. Steelmakers develop grades with high performance (Advanced High Strength Steels, AHSS and fine steel sheet assemblies are used in car body structures, with an optimized thickness in each part. However, unusual fracture modes are sometimes observed during the mechanical tests of heterogeneous AHSS welds, made of dissimilar steel grades and sheet thicknesses. Weld fractures can occur with a strength lower than expected. This study aims at understanding these fracture mechanisms and focuses on two common steel grades joined by Resistance Spot Welding (RSW: DP600 (a dual phase steel and Usibor®1500 (a martensitic steel. The parameters affecting the failure modes and load bearing capacity are investigated during two common types of tests: the Cross Tension and Tensile Shear tests. The positive effects of heterogeneous welding with respect to the corresponding homogeneous configurations are discussed, as well as the consequences of a so-called Dome failure occurring at the weld nugget boundary.

  16. CO{sub 2} laser cutting of advanced high strength steels (AHSS)

    Energy Technology Data Exchange (ETDEWEB)

    Lamikiz, A. [Department of Mechanical Engineering, University of the Basque Country, ETSII-UPV, c/Alameda de Urquijo s/n, 48013 Bilbao (Spain)]. E-mail: implamea@bi.ehu.es; Lacalle, L.N. Lopez de [Department of Mechanical Engineering, University of the Basque Country, ETSII-UPV, c/Alameda de Urquijo s/n, 48013 Bilbao (Spain); Sanchez, J.A. [Department of Mechanical Engineering, University of the Basque Country, ETSII-UPV, c/Alameda de Urquijo s/n, 48013 Bilbao (Spain); Pozo, D. del [ROBOTIKER Technology Centre, Parque Tecnologico, Edif. 202, 48170 Zamudio (Spain); Etayo, J.M. [Department of Mechanical Engineering, University of the Basque Country, ETSII-UPV, c/Alameda de Urquijo s/n, 48013 Bilbao (Spain); ROBOTIKER Technology Centre, Parque Tecnologico, Edif. 202, 48170 Zamudio (Spain); Lopez, J.M. [Department of Mechanical Engineering, University of the Basque Country, ETSII-UPV, c/Alameda de Urquijo s/n, 48013 Bilbao (Spain); ROBOTIKER Technology Centre, Parque Tecnologico, Edif. 202, 48170 Zamudio (Spain)

    2005-04-15

    This article demonstrates the optimum working areas and cutting conditions for the laser cutting of a series of advanced high strength steels (AHSS). The parameters that most influence the cutting of sheet metal have been studied and the results have been divided into two large groups with thickness of more and less than 1 mm. The influence of the material and, more important, the effect of coating have been taken into account. The results, have demonstrate very different behaviours between the thinnest and thickest sheets, whilst the variation of the cutting parameters due to the influence of the material is less relevant. The optimum cutting areas and the quality of the cut evaluated with different criteria are presented. Finally, the best position for the laser beam has been observed to be underneath the sheet.

  17. Segregation Behaviour of Third Generation Advanced High-Strength Mn-Al Steels

    Directory of Open Access Journals (Sweden)

    A. Grajcar

    2012-04-01

    Full Text Available The paper addresses the macro- and microsegregation of alloying elements in the new-developed Mn-Al TRIP steels, which belong to the third generation of advanced high-strength steels (AHSS used in the automotive industry. The segregation behaviour both in the as-cast state and after hot forging was assessed in the macro scale by OES and by EDS measurements in different structural constituents. The structural investigations were carried out using light and scanning electron microscopy. A special attention was paid to the effect of Nb microaddition on the structure and the segregation of alloying elements. The tendency of Mn and Al to macrosegregation was found. It is difficult to remove in Nb-free steels. Microsegregation of Mn and Al between austenite and ferritic structural constituents can be removed.

  18. Integrated Computational Materials Engineering (ICME) for Third Generation Advanced High-Strength Steel Development

    Energy Technology Data Exchange (ETDEWEB)

    Savic, Vesna; Hector, Louis G.; Ezzat, Hesham; Sachdev, Anil K.; Quinn, James; Krupitzer, Ronald; Sun, Xin

    2015-06-01

    This paper presents an overview of a four-year project focused on development of an integrated computational materials engineering (ICME) toolset for third generation advanced high-strength steels (3GAHSS). Following a brief look at ICME as an emerging discipline within the Materials Genome Initiative, technical tasks in the ICME project will be discussed. Specific aims of the individual tasks are multi-scale, microstructure-based material model development using state-of-the-art computational and experimental techniques, forming, toolset assembly, design optimization, integration and technical cost modeling. The integrated approach is initially illustrated using a 980 grade transformation induced plasticity (TRIP) steel, subject to a two-step quenching and partitioning (Q&P) heat treatment, as an example.

  19. Nanoscale surface analysis on second generation advanced high strength steel after hot dip galvanizing.

    Science.gov (United States)

    Arndt, M; Duchoslav, J; Preis, K; Samek, L; Stifter, D

    2013-09-01

    Second generation advanced high strength steel is one promising material of choice for modern automotive structural parts because of its outstanding maximal elongation and tensile strength. Nonetheless there is still a lack of corrosion protection for this material due to the fact that cost efficient hot dip galvanizing cannot be applied. The reason for the insufficient coatability with zinc is found in the segregation of manganese to the surface during annealing and the formation of manganese oxides prior coating. This work analyses the structure and chemical composition of the surface oxides on so called nano-TWIP (twinning induced plasticity) steel on the nanoscopic scale after hot dip galvanizing in a simulator with employed analytical methods comprising scanning Auger electron spectroscopy (SAES), energy dispersive X-ray spectroscopy (EDX), and focused ion beam (FIB) for cross section preparation. By the combination of these methods, it was possible to obtain detailed chemical images serving a better understanding which processes exactly occur on the surface of this novel kind of steel and how to promote in the future for this material system galvanic protection.

  20. Fatigue Performance of Advanced High-Strength Steels (AHSS) GMAW Joints

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhili [ORNL; Sang, Yan [AET Integration, Inc; Jiang, Cindy [AET Integration, Inc; Chiang, Dr. John [Ford Motor Company; Kuo, Dr. Min [MIttal Steel

    2009-01-01

    The fatigue performance of gas metal arc welding (GMAW) joints of advanced high strength steels (AHSS) are compared and analyzed. The steel studied included a number of different grades of AHSS and baseline mild steels: DP600, DP780, DP980, M130, M220, solution annealed boron steel, fully hardened boron steels, HSLA690 and DR210 (a mild steel). Fatigue testing was conducted under a number of nominal stress ranges to obtain the S/N curves of the weld joints. A two-phase analytical model is developed to predict the fatigue performance of AHSS welds. It was found that there are appreciable differences in the fatigue S/N curves among different AHSS joints made using the same welding practices, suggesting that the local microstructure in the weld toe and root region plays non-negligible role in the fatigue performance of AHSS welds. Changes in weld parameters can influence the joint characteristics which in turn influence fatigue life of the weld joints, particularly of those of higher strength AHSS. The analytical model is capable of reasonably predicting the fatigue performance of welds made with various steel grades in this study.

  1. Optimization of Process Parameters for High Efficiency Laser Forming of Advanced High Strength Steels within Metallurgical Constraints

    Science.gov (United States)

    Sheikholeslami, Ghazal; Griffiths, Jonathan; Dearden, Geoff; Edwardson, Stuart P.

    Laser forming (LF) has been shown to be a viable alternative to form automotive grade advanced high strength steels (AHSS). Due to their high strength, heat sensitivity and low conventional formability show early fractures, larger springback, batch-to-batch inconsistency and high tool wear. In this paper, optimisation of the LF process parameters has been conducted to further understand the impact of a surface heat treatment on DP1000. A FE numerical simulation has been developed to analyse the dynamic thermo-mechanical effects. This has been verified against empirical data. The goal of the optimisation has been to develop a usable process window for the LF of AHSS within strict metallurgical constraints. Results indicate it is possible to LF this material, however a complex relationship has been found between the generation and maintenance of hardness values in the heated zone. A laser surface hardening effect has been observed that could be beneficial to the efficiency of the process.

  2. Galvanizability of Advanced High-Strength Steels 1180TRIP and 1180CP

    Science.gov (United States)

    Kim, M. S.; Kwak, J. H.; Kim, J. S.; Liu, Y. H.; Gao, N.; Tang, N.-Y.

    2009-08-01

    In general, Si-bearing advanced high-strength steels (AHSS) possess excellent mechanical properties but poor galvanizability. The galvanizability of a transformation-induced plasticity (TRIP) steel 1180TRIP containing 2.2 pct Mn and 1.7 pct Si and a complex phase steel 1180CP containing 2.7 pct Mn and 0.2 pct Si was extensively studied using a galvanizing simulator. The steel coupons were annealed at fixed dew points in the simulator. The surface features of the as-annealed steel coupons, together with galvanized and galvannealed coatings, were carefully examined using a variety of advanced analysis techniques. It was found that various oxides formed on the surface of these steels, depending on the steel composition and on the dew point control. Coating quality was good at 0 °C dew point but deteriorated as the dew point decreased to -35 °C and -65 °C. Based on the findings, guidance was provided for improving galvanizability by adjusting the Mn:Si ratio in steel compositions according to the dew point.

  3. Three-Sheet Spot Welding of Advanced High-Strength Steels

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Friis, Kasper Storgaard; Zhang, W.

    2011-01-01

    The automotive industry has introduced the three-layer weld configuration, which represents new challenges compared to normal two-sheet lap welds. The process is further complicated by introducing high-strength steels in the joint. The present article investigates the weldability of thin, low....... The weld mechanisms are analyzed numerically and compared with metallographic analyses showing how the primary bonding mechanism between the thin, low-carbon steel sheet and the thicker sheet of high-strength steel is solid-state bonding, whereas the two high-strength steels are joined by melting, forming...... a weld nugget at their mutual interface. Despite the absence of the typical fusion nugget through the interface between the low-carbon steel and high-strength steel, the weld strengths obtained are acceptable. The failure mechanism in destructive testing is ductile fracture with plug failure....

  4. The plane strain shear fracture of the advanced high strength steels

    Science.gov (United States)

    Sun, Li

    2013-12-01

    The "shear fracture" which occurs at the high-curvature die radii in the sheet metal forming has been reported to remarkably limit the application of the advanced high strength steels (AHSS) in the automobile industry. However, this unusual fracture behavior generally cannot be predicted by the traditional forming limit diagram (FLD). In this research, a new experimental system was developed in order to simulate the shear fracture, especially at the plane strain state which is the most common state in the auto-industry and difficult to achieve in the lab due to sample size. Furthermore, the system has the capability to operate in a strain rate range from quasi-static state to the industrial forming state. One kinds of AHSS, Quenching-Partitioning (QP) steels have been performed in this test and the results show that the limiting fracture strain is related to the bending ratio and strain rate. The experimental data support that deformation-induced heating is an important cause of "shear fracture" phenomena for AHSS: a deformation-induced quasi-heating caused by smaller bending ratio and high strain rate produce a smaller limiting plane strain and lead a "shear fracture" in the component.

  5. The plane strain shear fracture of the advanced high strength steels

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Li, E-mail: li.sun@gm.com [General Motors China Science Lab, No.56 Jinwan Road, Shanghai, 201206 (China)

    2013-12-16

    The “shear fracture” which occurs at the high-curvature die radii in the sheet metal forming has been reported to remarkably limit the application of the advanced high strength steels (AHSS) in the automobile industry. However, this unusual fracture behavior generally cannot be predicted by the traditional forming limit diagram (FLD). In this research, a new experimental system was developed in order to simulate the shear fracture, especially at the plane strain state which is the most common state in the auto-industry and difficult to achieve in the lab due to sample size. Furthermore, the system has the capability to operate in a strain rate range from quasi-static state to the industrial forming state. One kinds of AHSS, Quenching-Partitioning (QP) steels have been performed in this test and the results show that the limiting fracture strain is related to the bending ratio and strain rate. The experimental data support that deformation-induced heating is an important cause of “shear fracture” phenomena for AHSS: a deformation-induced quasi-heating caused by smaller bending ratio and high strain rate produce a smaller limiting plane strain and lead a “shear fracture” in the component.

  6. Residual formability of preformed and subsequently welded advanced high strength steels (Reform): Final Report

    OpenAIRE

    Standfuß, Jens; Jahn, Axel; Weber, P; Neges, J.; Wischmann, S.; Höfemann, M.; Sierlinger, R.; Cretteur, L.; Veldt, T. van der; Veit, R.; Trattnig, G.; Pickett, A.; D Aiuto, F.

    2014-01-01

    The research project Reform was situated within the scope of research and technological development of steel and its utilisation. The central point of investigation was the determination of the load capability of preformed and subsequently welded parts made of high-strength steels. In order to cover a wide spectrum of automotive steel applications and with respect to the current development of modern high-strength steels, - two dual phase steels (HCT780X, HCT980X), - one trip steel (HCT690T),...

  7. Quasi-static and dynamic responses of advanced high strength steels: Experiments and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Akhtar; Baig, Muneer; Choi, Shi Hoon; Yang, Hoe Seok; Sun, Xin

    2012-03-01

    Measured responses of advanced high strength steels (AHSS) and their tailor welded blanks (TWBs), over a wide range of strain-rates (10*4 to 103 s*1) are presented. The steels investigated include transformation induced plasticity (TRIP), dual phase (DP), and drawing quality (DQ) steels. The TWBs include DQ-DQ and DP-DP laser welds. A tensile split Hopkinson pressure bar (SHPB) was used for the dynamic experiments. AHSS and their TWB's were found to exhibit positive strain-rate sensitivity. The Khan-Huang-Liang (KHL) constitutive model is shown to correlate and predict the observed responses reasonably well. Micro-texture characterization of DQ steels, DQ-DQ and DP-DP laser welds were performed to investigate the effect of strain-rate on texture evolution of these materials. Electron backscatter diffraction (EBSD) technique was used to analyze the micro-texture evolution and kernel average misorientation (KAM) map. Measurement of micro-hardness profile across the cross section of tensile samples was conducted to understand the effect of initial microstructure on ductility of laser weld samples.

  8. Formability Prediction of Advanced High Strength Steel with a New Ductile Fracture Criterion

    Science.gov (United States)

    Lou, Yanshan; Lim, Sungjun; Huh, Jeehyang; Huh, Hoon

    2011-08-01

    A ductile fracture criterion is newly proposed to accurately predict forming limit diagrams (FLD) of sheet metals. The new ductile fracture criterion is based on the effect of the non-dimensional stress triaxiality, the stress concentration factor and the effective plastic strain on the nucleation, growth and coalescence of voids. The new ductile fracture criterion has been applied to estimate the formability of four kind advanced high strength steels (AHSS): DP780, DP980, TRIP590, and TWIP980. FLDs predicted are compared with experimental results and those predicted by other ductile fracture criteria. The comparison demonstrates that FLDs predicted by the new ductile fracture criterion are in better agreement with experimental FLDs than those predicted by other ductile fracture criteria. The better agreement of FLDs predicted by the new ductile fracture criterion is because conventional ductile fracture criteria were proposed for fracture prediction in bulk metal forming while the new one is proposed to predict the onset of fracture in sheet metal forming processes.

  9. Analysis of hot forming of a sheet metal component made of advanced high strength steel

    Science.gov (United States)

    Demirkaya, Sinem; Darendeliler, Haluk; Gökler, Mustafa İlhan; Ayhaner, Murat

    2013-05-01

    To provide reduction in weight while maintaining crashworthiness and to decrease the fuel consumption of vehicles, thinner components made of Advanced High Strength Steels (AHSS) are being increasingly used in automotive industry. However, AHSS cannot be formed easily at the room temperature (i.e. cold forming). The alternative process involves heating, hot forming and subsequent quenching. A-pillar upper reinforcement of a vehicle is currently being produced by cold forming of DP600 steel sheet with a thickness of 1.8 mm. In this study, the possible decrease in the thickness of this particular part by using 22MnB5 as appropriate AHSS material and applying this alternative process has been studied. The proposed process involves deep drawing, trimming, heating, sizing, cooling and piercing operations. Both the current production process and the proposed process are analyzed by the finite element method. The die geometry, blank holding forces and the design of the cooling channels for the cooling process are determined numerically. It is shown that the particular part made of 22MnB5 steel sheet with a thickness of 1.2 mm can be successfully produced by applying the proposed process sequence and can be used without sacrificing the crashworthiness. With the use of the 22MnB5 steel with a thickness of 1.2 mm instead of DP600 sheet metal with a thickness of 1.8 mm, the weight is reduced by approximately 33%.

  10. Experimental study of Electro-Plastic Effect on Advanced High Strength Steels

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xun; Lan, Shuhuai; Ni, Jun, E-mail: junni@umich.edu

    2013-10-10

    Application of Advanced High Strength Steels (AHSS) into vehicle structures calls for innovative manufacturing processes. In terms of reducing deformation resistance through external energy, Electro-Plastic Effect (EPE) provides a potential alternative to traditional thermal softening phenomenon. In this work, effectiveness of EPE on one group of AHSS, Transformation Induced Plasticity (TRIP) Steel, was evaluated. It was found that EPE cannot be effectively initiated until the current density reaches a threshold value between 7.4 A/mm{sup 2} and 11.4 A/mm{sup 2}. Besides, the softening phenomenon is more distinct at larger strains. Underlying mechanisms are explained from perspectives of dislocation multiplication, gliding and mechanical twinning. The inevitable Joule heating phenomenon associated with current was suppressed with forced air cooling and the temperature distribution inside the tensile specimen was numerically calculated with a coupled Finite Element Model. Effectiveness of EPE rather than thermal softening or expansion was further proved with the larger flow stress reduction under higher current density and shorter pulses at same temperature increase. Hollomon equation was adopted to model the observed stress strain relationships. Since material properties of TRIP steels are directly related to the phase transformation from retained austenite into martensite, volume fraction of retained austenite was quantitatively measured by X-ray Diffraction (XRD). It was found that the applied current retarded martensitic transformation process. Metallographic analysis was further performed and phenomena of change of grain structures and phase distribution were hardly observable.

  11. Experimental investigation on electroplastic effect of DP980 advanced high strength steel

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Huanyang [School of Materials Science and Engineering, Shanghai Jiao Tong University, 1954 Huashan Road, 200030 Shanghai (China); Dong, Xianghuai, E-mail: dongxh@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, 1954 Huashan Road, 200030 Shanghai (China); Liu, Kai; Ai, Zhenqiu; Peng, Fang; Wang, Qian [School of Materials Science and Engineering, Shanghai Jiao Tong University, 1954 Huashan Road, 200030 Shanghai (China); Chen, Fei [Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, NG7 2RD Nottingham (United Kingdom); Wang, Jianfeng [General Motor China Science Lab, No. 56 Jinwan Road, 201206 Shanghai (China)

    2015-06-18

    This paper investigated the influence of the electric pulses on the flow behavior and plasticity of the advanced high strength steel (AHSS) Dual Phase, DP980. In order to isolate the thermal effect of the electric pulses, two kinds of uniaxial tensile tests at the same testing temperature were carried out: (1) isothermal tensile test carried out in an environment cabinet and (2) electrically-assisted isothermal tensile test. The stress–strain curves were recorded and compared. The results indicate that at the same testing temperature, the stress–strain curves obtained by test (1) are generally lower than curves deserved by test (2). It demonstrates that electric pulses can not reduce the flow stress when compared with the case that without electric pulse which is contrary to the traditional electroplastic effect. Another result is that when the testing temperature is not more than 573 K, the stress–strain curves obtained by both tests are higher than the tension curve in room temperature and the cases are opposite when testing temperature is more than 573 K. In addition, the elongation improvement is not observed as well in the stress–strain curves. The difference between the two tests when compared the cross section shrinkage rate and the fracture elongation rate is not obvious. From another aspect to study the athermal effect of the electric pulse, tests with only varying the peak current density or pulse frequency at the same testing temperature were conducted. The results once again show that no evident difference between the stress–strain curves. It confirms that no athermal effect exists in DP980. However, with temperature elevated to 473 K, the material is strengthened and then weakened as temperature exceeds 473 K. Scanning electron microscope (SEM) analysis was adopted to better understand the observed phenomena. The results show that the decomposion of the martensite and the thermal effect are the main reason that attributes to the strength

  12. Effect of microstructure on the fracture response of advanced high strength steels

    Science.gov (United States)

    Taylor, Mark D.

    2013-01-01

    The materials selected to observe microstructural effects on formability included four 780 MPa strength, and four 980 MPa strength AHSS grades produced with varying processing conditions. The grades were an uncoated DP780, a high yield DP780, a galvanized DP780, a TRIP780, a galvannealed DP980, a galvanized DP980, an uncoated DP980, and a fine grained DP980. All AHSS grades were tensile tested to obtain values for ultimate tensile strength, yield strength, percent uniform and total elongation. An analysis was performed to quantify the average grain size of the primary and second phase constituents, as well as the second phase volume fraction present in each AHSS grade. Nanoindentation was performed for each AHSS grade to determine the average hardness of the primary and second phase constituents present. Evolution of microstructural damage in response to deformation was analyzed using a plane strain tensile method developed to impose a localized through-thickness shear fracture. Samples of each AHSS grade were strained to progressively higher percentages of their failure displacement, and microstructural damage was observed using a scanning electron microscope on a metallographic section removed from the localized shear deformation region. Micrographs were analyzed using ImageJ®, and the resulting void percent and number of voids were determined for each test performed. A direct correlation was observed between the number of voids and hardness ratio. The strength of the microstructural constituents affected mechanical properties, suggesting that constituent strength values should be considered when predicting formability limits for higher strength AHSS grades. Since all AHSS grades experienced some critical number of voids before fracture, it was concluded that suppression of void formation can extend the formability limits to higher strains. After observing a percent failure displacement value of 95%, it was determined that the final stage of fracture (void

  13. A 3rd Generation Advanced High-Strength Steel (AHSS) Produced by Dual Stabilization Heat Treatment (DSHT)

    Science.gov (United States)

    Qu, Hao; Michal, Gary M.; Heuer, Arthur H.

    2013-10-01

    A 3rd generation advanced high-strength steel containing, in wt pct, 0.3 C, 4.0 Mn, 1.5 Al, 2.1 Si, and 0.5 Cr has been produced using a dual stabilization heat treatment—a five stage thermal processing schedule compatible with continuous galvanized steel production. In excess of 30 vol pct retained austenite containing at least 0.80 wt pct C was achieved with this alloy, which had tensile strengths up to 1650 MPa and tensile elongations around 20 pct.

  14. Advanced high strength steel (AHSS) TWIP: A door to the future in metal forming

    OpenAIRE

    2012-01-01

    The last decades have been characterized by a fast evolution of cars. This work shows the evolution of vehicle weight. It shows the response of car manufacturers using new materials and production methods that allow lighter vehicles with lower consumption, cheaper and with lower influence on the greenhouse effect. One of the materials which means a most interesting change is the TWIP steel. This material is characterized by its high strength, his exceptional strain and excellent formability a...

  15. Development of Appropriate Spot Welding Practice for Advanced High Strength Steels (TRP 0114)

    Energy Technology Data Exchange (ETDEWEB)

    Brian Girvin; Warren Peterson; Jerry Gould

    2004-09-17

    This program evaluated the effects of common manufacturing variables on spike-tempering effectiveness. The investigation used design-of-experiment (DOE) techniques, and examined both dual-phase and martensitic grades of high-strength steels (HSS). The specific grades chosen for this project were: Dual-phase (DP) 600, galvannealed (GA), 1.55 mm (DP) 600; Dual-phase (DP) 980 (uncoated), 1.55 mm (DP) 980; and Martensitic (M) 1300, 1.55 mm (M) 1300. Common manufacturing conditions of interest included tempering practice (quench and temper time), button size, simulated part fitup (sheet angular misalignment and fitup), and electrode wear (increased electrode face diameter). All of these conditions were evaluated against mechanical performance (static and dynamic tensile shear). Weld hardness data was also used to examine correlations between mechanical performance and the degree of tempering. Mechanical performance data was used to develop empirical models. The models were used to examine the robustness of weld strength and toughness to the selected processing conditions. This was done using standard EWI techniques. Graphical representations of robustness were then coupled with metallographic data to relate mechanical properties to the effectiveness of spike tempering. Mechanical properties for all three materials were relatively robust to variation in tempering. Major deviations in mechanical properties were caused by degradation of the weld itself. This was supported by a lack of correlation between hardness data and mechanical results. Small button sizes and large electrode face diameters (worn electrodes) produced large reductions in both static and dynamic strength levels when compared to standard production setups. Dynamic strength was further degraded by edge-located welds.

  16. Advanced high strength steel (AHSS) TWIP: A door to the future in metal forming

    Science.gov (United States)

    Pla-Ferrando, R.; Sánchez-Caballero, S.; Reig, M. J.; Pla, R.; Sellés, M. A.; Seguí, V. J.

    2012-04-01

    The last decades have been characterized by a fast evolution of cars. This work shows the evolution of vehicle weight. It shows the response of car manufacturers using new materials and production methods that allow lighter vehicles with lower consumption, cheaper and with lower influence on the greenhouse effect. One of the materials which means a most interesting change is the TWIP steel. This material is characterized by its high strength, his exceptional strain and excellent formability as well as lower energy consumption in their manufacture. TWIP steel are changing towards cheaper compositions and higher performance, and it's going to be great influence in the vehicle weight reduction in the next years.

  17. Dissimilar Arc Welding of Advanced High-Strength Car-Body Steel Sheets

    Science.gov (United States)

    Russo Spena, P.; D'Aiuto, F.; Matteis, P.; Scavino, G.

    2014-11-01

    A widespread usage of new advanced TWIP steel grades for the fabrication of car-body parts is conditional on the employment of appropriate welding methods, especially if dissimilar welding must be performed with other automotive steel grades. Therefore, the microstructural features and the mechanical response of dissimilar butt weld seams of TWIP and 22MnB5 steel sheets after metal-active-gas arc welding are examined. The microstructural and mechanical characterization of the welded joints was carried out by optical metallography, microhardness and tensile testing, and fractographic examination. The heat-affected zone on the TWIP side was fully austenitic and the only detectable effect was grain coarsening, while on the 22MnB5 side it exhibited newly formed martensite and tempered martensite. The welded tensile specimens exhibited a much larger deformation on the TWIP steel side than on the 22MnB5. The fracture generally occurred at the interface between the fusion zone and the heat-affected zones, with the fractures surfaces being predominantly ductile. The ultimate tensile strength of the butt joints was about 25% lower than that of the TWIP steel.

  18. New techniques of the mechanical properties assessment for Advanced High Strength Steel (AHSS) in automobile

    Energy Technology Data Exchange (ETDEWEB)

    Fang Jian [Baoshan Iron and Steel Co., Ltd., Shanghai (China)

    2005-07-01

    Based on the mathematical polynomial and differentiate processing onto tensile stress-strain curve, the experimental technique to monitor the trace of working hardening exponent against strain was established, with the hope of linking the characterization of the mechanical properties to the insight into the microstructure behavior of AHSS. The features of a significant strain hardening peak with slow decaying followed was obtained existing on the n value trace of strain during uniform deformation, which may be the predominant contribution to the outstanding combination of strength and plasticity of AHSS. In comparison, for conventional high strength steel as quench and temper prepared, the form of n value trace was changed into the monotonous decreasing tendency within overall uniform extension. As regards the dynamic loading response of AHSS, the recorded impact force-displacement curve by instrumented impact testing with characteristic force points subdivided the absorbed impact energy into distinct components, corresponding to the crack initiation and propagation. Combined with the quasi static tensile, the concept of toughness parameters including J{sub d}, J-{delta}a and so-called ''local strain toughness, LST'' were proposed, which implies that the stable plastic deformation and pronounced energy consumption may lead to the excellent material response against cracking and rupture under various loading conditions. (orig.)

  19. Development of Advanced High Strength Steel for Improved Vehicle Safety, Fuel Efficiency and CO2 Emission

    Science.gov (United States)

    Kumar, Satendra; Singhai, Mrigandra; Desai, Rahul; Sam, Srimanta; Patra, Pradip Kumar

    2016-10-01

    Global warming and green house gas emissions are the major issues worldwide and their impacts are clearly visible as a record high temperatures, rising sea, and severe `flooding and droughts'. Motor vehicles considered as a major contributor on global warming due to its green house gas emissions. Hence, the automobile industries are under tremendous pressure from government and society to reduce green house gas emission to maximum possible extent. In present work, Dual Phase steel with boron as microalloying is manufactured using thermo-mechanical treatment during hot rolling. Dual phase steel with boron microalloying improved strength by near about 200 MPa than dual phase steel without boron. The boron added dual phase steel can be used for manufacturing stronger and a lighter vehicle which is expected to perform positively on green house gas emissions. The corrosion resistance behavior is also improved with boron addition which would further increase the life cycle of the vehicle even under corrosive atmosphere.

  20. Microstructure and Hardness Distribution of Resistance Welded Advanced High Strength Steels

    DEFF Research Database (Denmark)

    Pedersen, Kim Richardt; Harthøj, Anders; Friis, Kasper Leth;

    2008-01-01

    In this work a low carbon steel and two high strength steels (DP600 and TRIP700) have been resistance lap welded and the hardness profiles were measured by micro hardness indentation of cross sections of the joint. The resulting microstructure of the weld zone of the DP-DP and TRIP-TRIP joints were...... found to consist of a martensitic structure with a significant increase in hardness. Joints of dissimilar materials mixed completely in the melted region forming a new alloy with a hardness profile lying in between the hardness measured in joints of the similar materials. Furthermore the joints were...... simulated numerically and together with the material carbon equivalent, austenization temperatures and the thermal history the simulations were used to estimate the resulting post weld hardness using the commercial FE code SORPAS. The hardness of the welds of dissimilar materials was estimated...

  1. Development of Advanced High Strength Steel for Improved Vehicle Safety, Fuel Efficiency and CO2 Emission

    Science.gov (United States)

    Kumar, Satendra; Singhai, Mrigandra; Desai, Rahul; Sam, Srimanta; Patra, Pradip Kumar

    2015-12-01

    Global warming and green house gas emissions are the major issues worldwide and their impacts are clearly visible as a record high temperatures, rising sea, and severe `flooding and droughts'. Motor vehicles considered as a major contributor on global warming due to its green house gas emissions. Hence, the automobile industries are under tremendous pressure from government and society to reduce green house gas emission to maximum possible extent. In present work, Dual Phase steel with boron as microalloying is manufactured using thermo-mechanical treatment during hot rolling. Dual phase steel with boron microalloying improved strength by near about 200 MPa than dual phase steel without boron. The boron added dual phase steel can be used for manufacturing stronger and a lighter vehicle which is expected to perform positively on green house gas emissions. The corrosion resistance behavior is also improved with boron addition which would further increase the life cycle of the vehicle even under corrosive atmosphere.

  2. Microstructural Developments Leading to New Advanced High Strength Sheet Steels: A Historical Assessment of Critical Metallographic Observations

    Energy Technology Data Exchange (ETDEWEB)

    Matlock, David K [CSM/ASPPRC; Thomas, Larrin S [CSM/ASPPRC; Taylor, Mark D [CSM/ASPPRC; De Moor, Emmanuel [CSM/ASPPRC; Speer, John G [CSM/ASPPRC

    2015-08-03

    In the past 30+ years significant advancements have been made in the development of higher strength sheet steels with improved combinations of strength and ductility that have enabled important product improvements leading to safer, lighter weight, and more fuel efficient automobiles and in other applications. Properties of the primarily low carbon, low alloy steels are derived through careful control of time-temperature processing histories designed to produce multiphase ferritic based microstructures that include martensite and other constituents including retained austenite. The basis for these developments stems from the early work on dual-phase steels which was the subject of much interest. In response to industry needs, dual-phase steels have evolved as a unique class of advanced high strength sheet steels (AHSS) in which the thermal and mechanical processing histories have been specifically designed to produce constituent combinations for the purpose of simultaneously controlling strength and deformation behavior, i.e. stress-strain curve shapes. Improvements continue as enhanced dual-phase steels have recently been produced with finer microstructures, higher strengths, and better overall formability. Today, dual phase steels are the primary AHSS products used in vehicle manufacture, and several companies have indicated that the steels will remain as important design materials well into the future. In this presentation, fundamental results from the early work on dual-phase steels will be reviewed and assessed in light of recent steel developments. Specific contributions from industry/university cooperative research leading to product improvements will be highlighted. The historical perspective provided in the evolution of dual-phase steels represents a case-study that provides important framework and lessons to be incorporated in next generation AHSS products.

  3. Testing new tribo-systems for sheet metal forming of advanced high strength steels and stainless steels

    DEFF Research Database (Denmark)

    Bay, Niels; Ceron, Ermanno

    2014-01-01

    Testing of new tribo-systems in sheet metal forming has become an important issue due to new legislation, which forces industry to replace current, hazardous lubricants. The present paper summarizes the work done in a recent PhD project at the Technical University of Denmark on the development...... of a methodology for off-line testing of new tribo-systems for advanced high strength steels and stainless steels. The methodology is presented and applied to an industrial case, where different tribo-systems are tested. A universal sheet tribotester has been developed, which can run automatically repetitive...

  4. Effect of microstructure on the fracture response of advanced high strength steels

    Science.gov (United States)

    Taylor, Mark David

    The effect of constituent hardness on formability performance for higher-strength dual phase (DP) steels was evaluated. A commercially-produced DP steel with 1080 MPa ultimate tensile strength (UTS) was processed to create eight additional constituent hardness conditions by tempering and cold-rolling, processes that primarily affected constituent hardness properties. Using nanoindentation, ferrite and martensite hardness values for the nine conditions of the DP steel (as-received, four as-tempered, four temper cold-rolled) provided a range of hardness values to evaluate formability performance. Formability performance for the nine steel conditions was evaluated using tensile and hole expansion testing. A decrease in martensite/ferrite hardness ratio corresponded to an increase in hole expansion ratio (HER), and an increase in yield strength (YS). A lower hardness ratio (increased similarity of ferrite and martensite hardness) was interpreted to increase strain-sharing between ferrite and martensite, which suppressed plastic strain localization to higher stresses for the case of YS, and to higher formability limits for the case of HER. A lower hardness ratio corresponded to a decrease in work-hardening, and was interpreted to be caused by the suppression of strain localization in ferrite. Multiple studies from literature correlated HER to tensile properties, and the nine steel conditions produced consistent trends with the data reported in each study, confirming the experimental HER and tensile properties obtained in the current study are consistent with literature. The microstructural response to plastic deformation was evaluated using two DP steels with equivalent UTS and different hardness ratios. Nanoindentation analyses on tensile specimens deformed to the UTS revealed a greater increase in ferrite hardness for the higher hardness ratio steel, interpreted to be caused by the greater amount of work hardening. EBSD crystallographic orientation maps for the two DP

  5. Evaluation of common tests for fracture characterisation of advanced high-strength sheet steels with the help of the FEA

    Science.gov (United States)

    Peshekhodov, I.; Dykiert, M.; Vucetic, M.; Behrens, B.-A.

    2016-11-01

    The paper presents results of evaluation of common tests for fracture characterization of advanced high-strength sheet steels with the help of the FEA. The tests include three in-plane shear tests, two uniaxial tension tests, two plane strain tension tests and two equibiaxial tension tests. Three high-strength steels with different yield loci, strain hardening rates and strengths in three different thicknesses each were used. The evaluation was performed based on the spatial distribution of the equivalent plastic strain and damage variable in the specimen at the moment of crack initiation as well as on the time variation of the stress state at the crack initiation location. For in-plane shear, uniaxial tension and plane strain tension, no test can be unconditionally recommended as disadvantages of all studied tests in these groups cannot be neglected. However, in each of these groups, a test can be chosen, which represents an acceptable compromise between its advantages and disadvantages: the shear test on an IFUM butterfly specimen for in-plane shear, the tensile test on a holed specimen for uniaxial tension and the tensile test on a waisted specimen for plane strain tension. On the contrary, the bulge test on a circular specimen with a punch of Ø 100 mm can be unconditionally recommended for equibiaxial tension. In the future, optimisation of the studied tests for in-plane shear, uniaxial tension and plane strain tension appears to be necessary.

  6. Issues associated with the use of Yoshida nonlinear isotropic/kinematic hardening material model in Advanced High Strength Steels

    Science.gov (United States)

    Shi, Ming F.; Zhang, Li; Zhu, Xinhai

    2016-08-01

    The Yoshida nonlinear isotropic/kinematic hardening material model is often selected in forming simulations where an accurate springback prediction is required. Many successful application cases in the industrial scale automotive components using advanced high strength steels (AHSS) have been reported to give better springback predictions. Several issues have been raised recently in the use of the model for higher strength AHSS including the use of two C vs. one C material parameters in the Armstrong and Frederick model (AF model), the original Yoshida model vs. Original Yoshida model with modified hardening law, and constant Young's Modulus vs. decayed Young's Modulus as a function of plastic strain. In this paper, an industrial scale automotive component using 980 MPa strength materials is selected to study the effect of two C and one C material parameters in the AF model on both forming and springback prediction using the Yoshida model with and without the modified hardening law. The effect of decayed Young's Modulus on the springback prediction for AHSS is also evaluated. In addition, the limitations of the material parameters determined from tension and compression tests without multiple cycle tests are also discussed for components undergoing several bending and unbending deformations.

  7. Effects of Fusion Zone Size on Failure Modes and Performance of Advanced High Strength Steel Spot Welds

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2006-04-28

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS). DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. The critical fusion zone sizes to ensure nugget pull-out failure mode are developed for both DP800 and TRIP800 using the limit load based analytical model and the micro-hardness measurements of the weld cross sections. Static weld strength tests using cross tension samples were performed on the joint populations with controlled fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied using statistical data analysis tools. The results in this study show that the conventional weld size of 4 t can not produce nugget pullout mode for both the DP800 and TRIP800 materials. The results also suggest that performance based spot weld acceptance criteria should be developed for different AHSS spot welds.

  8. Numerical and experimental evaluation of the impact performance of advanced high-strength steel sheets based on a damage model

    Science.gov (United States)

    Ma, Ning; Park, Taejoon; Kim, Dongun; Kim, Chongmin; Chung, Kwansoo

    2010-06-01

    The impact performance in a Charpy impact test was experimentally and numerically studied for the advanced high-strength steel sheets (AHSS) TWIP940 and TRIP590 as well as the high-strength grade known as 340R. To characterize the mechanical properties, uni-axial simple tension tests were conducted to determine the anisotropic properties and strain rate sensitivities of these materials. In particular, the high-speed strain-rate sensitivity of TRIP590 and 340R (rate sensitive) was also characterized to account for the high strain rates involved in the Charpy impact test. To evaluate fracture behavior in the Charpy impact test, a new damage model including a triaxiality-dependent fracture criterion and hardening behavior with stiffness deterioration was introduced. The model was calibrated via numerical simulations and experiments involving simple tension and V-notch tests. The new damage model along with the anisotropic yield function Hill 1948 was incorporated into the ABAQUS/Explicit FEM code, which performed reasonably well to predict the impact energy absorbed during the Charpy impact test.

  9. Cyclic Deformation of Advanced High-Strength Steels: Mechanical Behavior and Microstructural Analysis

    Science.gov (United States)

    Hilditch, Timothy B.; Timokhina, Ilana B.; Robertson, Leigh T.; Pereloma, Elena V.; Hodgson, Peter D.

    2009-02-01

    The fatigue properties of multiphase steels are an important consideration in the automotive industry. The different microstructural phases present in these steels can influence the strain life and cyclic stabilized strength of the material due to the way in which these phases accommodate the applied cyclic strain. Fully reversed strain-controlled low-cycle fatigue tests have been used to determine the mechanical fatigue performance of a dual-phase (DP) 590 and transformation-induced plasticity (TRIP) 780 steel, with transmission electron microscopy (TEM) used to examine the deformed microstructures. It is shown that the higher strain life and cyclic stabilized strength of the TRIP steel can be attributed to an increased yield strength. Despite the presence of significant levels of retained austenite in the TRIP steel, both steels exhibited similar cyclic softening behavior at a range of strain amplitudes due to comparable ferrite volume fractions and yielding characteristics. Both steels formed low-energy dislocation structures in the ferrite during cyclic straining.

  10. Lightweight, High Strength Metals With Enhanced Radiation Shielding - Technology Advancing Partnerships Challenge Project

    Science.gov (United States)

    Wright, Maria Clara (Compiler)

    2015-01-01

    The Technology Advancing Partnership (TAP) Challenge will seek to foster innovation throughout the Center by allowing the KSC workforce to identify a specific technology idea that needs improvement and to then work with an external partner to develop that technology. This Challenge will enable competitive partnerships with outside entities that will increase the value by bringing leveraged resources. The selected proposal from the University of Florida will develop new lightweight technologies with radiation mitigation for spacecraft.

  11. A Modified Johnson-Cook Model for Advanced High-Strength Steels Over a Wide Range of Temperatures

    Science.gov (United States)

    Qingdong, Zhang; Qiang, Cao; Xiaofeng, Zhang

    2014-12-01

    Advanced high-strength steel (AHSS) is widely used in automotive industry. In order to investigate the mechanical behaviors of AHSS over a wide range of temperatures, quasi-static tensile experiments were conducted at the temperatures from 298 to 1073 K on a Gleeble-3500 thermo-simulation machine. The results show that flow behaviors are affected by testing temperature significantly. In order to describe the flow features of AHSS, the Johnson-Cook (JC) model is employed. By introducing polynomial functions to consider the effects of temperature on hardening behavior, the JC model is modified and used to predict flow behavior of AHSS at different experimental conditions. The accuracy of the modified JC model is verified and the predicted flow stress is in good agreement with experimental results, which confirms that the modified JC model can give an accurate and precise estimate over a wide range of temperatures.

  12. Crystal Plasticity Constitutive Model for Multiphase Advanced High Strength Steels to Account for Phase Transformation and Yield Point Elongation

    Science.gov (United States)

    Park, Taejoon; Pourboghrat, Farhang

    2016-08-01

    A constitutive law was developed based on a rate-independent crystal plasticity to account for the mechanical behavior of multiphase advanced high strength steels. Martensitic phase transformation induced by the plastic deformation of the retained austenite was represented by considering the lattice invariant shear deformation and the orientation relationship between parent austenite and transformed martensite. The stress dependent transformation kinetics were represented by adopting the stress state dependent volume fraction evolution law. The plastic deformation of the austenite was determined to have the minimum- energy associated with the work during the phase transformation. In addition to the martensitic phase transformation, yield point elongation and subsequent hardening along with inhomogeneous plastic deformation were also represented by developing a hardening stagnation model induced by the delayed dislocation density evolution.

  13. Assessment of the Critical Parameters Influencing the Edge Stretchability of Advanced High-Strength Steel Sheet

    Science.gov (United States)

    Pathak, N.; Butcher, C.; Worswick, M.

    2016-11-01

    The edge formability of ferritic-martensitic DP (dual-phase) and ferritic-bainitic CP (complex-phase) steels was evaluated using a hole expansion test for different edge conditions. Hole expansion tests involving the standard conical punch as well as a custom flat punch were performed to investigate formability when the hole is expanded out-of-plane (conical punch) and in-plane using the flat punch. A range of edge conditions were considered, in order to isolate the influence of a range of factors thought to influence edge formability. The results demonstrate that work hardening and void damage at the sheared edge govern formability, while the sheared surface quality plays a minor or secondary role. A comparison of the edge stretching limits of DP and CP steels demonstrates the advantages of a ferritic-bainitic microstructure for forming operations with severe local deformation as in a stretch-flanging operation. A comparison of a traditional DP780 steel with a CP steel of similar strength showed that the edge stretching limit of the CP steel was three times larger than that of the DP780.

  14. Hardening characteristics of CO2 laser welds in advanced high strength steel

    Science.gov (United States)

    Han, Tae-Kyo; Park, Bong-Gyu; Kang, Chung-Yun

    2012-06-01

    When the CO2 laser welder with 6 kW output was used to weld 4 TRIP steels, 2 DP steels and a precipitation-hardened steel, which have the tensile strength in the range of 600-1000 MPa, the effect of welding speed on hardening characteristics was investigated. In the weld of TRIP steels and DP steels, the maximum hardness was shown in the fusion zone and the HAZ near the bond line, and the hardness was decreased from the HAZ to the base metal. Only in the PH600 steel, the maximum hardness was shown in the fusion zone and the hardness was decreased from bond line to the base metal. The maximum hardness value was not changed due to the variation of the welding speed within a given range of the welding speed. When the correlation with maximum hardness value using 6 known carbon equivalents was examined, those of CEL (=C+Si/50+Mn/25+P/2+Cr/25) and PL (=C+Mn/22+14B) were 0.96 and 0.95 respectively, and CEL was better because it could reflect the contribution of Si and Cr added to AHSS. The maximum hardness value could be calculated by the equation "Hmax=701CEL+281". The phase transformation analysis indicated that only martensitic transformation was expected in the given range of the welding conditions. Therefore, the maximum hardness of the weld was the same as that of water cooled steel and not changed with the variation of the welding speed

  15. Multiscale Modeling of Inclusions and Precipitation Hardening in Metal Matrix Composites: Application to Advanced High-Strength Steels

    Energy Technology Data Exchange (ETDEWEB)

    Askari, Hesam; Zbib, Hussein M.; Sun, Xin

    2013-06-01

    In this study, the strengthening effect of inclusions and precipitates in metals is investigated within a multiscale approach that utilizes models at various length scales, namely, Molecular Mechanics (MM), discrete Dislocation Dynamics (DD), and an Eigenstrain Inclusion Method (EIM). Particularly, precipitates are modeled as hardsoft particles whose stress fields interact with dislocations. The stress field resulting from the elastic mismatch between the particles and the matrix is accounted for through the EIM. While the MM method is employed for the purpose of developing rules for DD for short range interaction between a single dislocation and an inclusion, the DD method is used to predict the strength of the composite resulting from the interaction between ensembles of dislocations and particles. As an application to this method, the mechanical behavior of Advanced High Strength Steel (AHSS) is investigated and the results are then compared to the experimental data. The results show that the finely dispersive precipitates can strengthen the material by pinning the dislocations up to a certain shear stress and retarding the recovery, as well as annihilation of dislocations. The DD results show that strengthening due to nano sized particles is a function of the density and size of the precipitates. This size effect is then explained using a mechanistic model developed based on dislocation-particle interaction.

  16. Ductility of Advanced High-Strength Steel in the Presence of a Sheared Edge

    Science.gov (United States)

    Ruggles, Tim; Cluff, Stephen; Miles, Michael; Fullwood, David; Daniels, Craig; Avila, Alex; Chen, Ming

    2016-07-01

    The ductility of dual-phase (DP) 980 and transformation-induced plasticity (TRIP) assisted bainitic ferritic (TBF) 980 steels was studied in the presence of a sheared edge. Specimens were tested in uniaxial tension in a standard test frame as well as in situ in the scanning electron microscope (SEM). Incremental tensile straining was done in the SEM with images taken at each strain increment. Then digital image correlation (DIC) was used to compute the effective strain at the level of the individual phases in the microstructure. Shear banding across multiple phases was seen in strained TBF specimens, while the DP specimens exhibited more of a patchwork strain pattern, with high strains concentrated in ferrite and low strains observed in the martensite. Two-point statistics were applied to the strain data from the DIC work and the corresponding microstructure images to evaluate the effect of phase hardness on localization and fracture. It was observed that the DP 980 material had a greater tendency for localization around hard phases compared to the TBF 980. This at least partially explains the greater ductility of the TBF material, especially in specimens where a sheared edge was present.

  17. Three Important Advances in Engineering Strength Theories

    Institute of Scientific and Technical Information of China (English)

    YuMaohong; FanWen; MitustoshiYoshimine

    2003-01-01

    There are there great advances in the research on engineering strength theories in the latter half of the 20th Century. The first advance was the devel-opment of strength theory from the single-shear strength theory including the Tresca yield criterion and Mohr-Coulomb failure criterion to theoctahe-dral-shear strength theory; the second one was that from the octahedral-shear strength theory to the twin-shear strength theory; and the third wasthe theories from the single criteria to the unifiedstrength theory. These three advances are summa-rized in this paper. It is interesting and useful for re-searchers to choose an appropriate failure criterion in studying the strength of materials and struc-tures, for engineers to correctly use it and for stu-dents to understand strength theory.

  18. Improving the crash behavior of structural components made of advanced high strength steel by local heat treatment

    Science.gov (United States)

    Conrads, L.; Daamen, M.; Hirt, G.; Bambach, M.

    2016-11-01

    High manganese TWIP steel belongs to the second generation of advanced high strength steels. During the production of strip material, the microstructure and hence the mechanical properties of TWIP steel can be adapted to the specific needs of crash relevant structures. Whereas typically the whole steel strip is heat-treated after cold rolling, a local heat treatment can be applied to tailor the properties accordingly. In this work, a method is presented to identify a suitable process window for the local laser heat treatment of TWIP steel. The material is strain hardened and afterwards heat-treated at various temperatures for a short time. The influence of the respective heat treatment on microstructure and mechanical properties is evaluated and the most appropriate heat treatment is then reproduced using laser heating. To verify the effect of a local laser heat treatment at a structural component, crash boxes with different heat treatment patterns were produced and tested. The dynamic crash tests show that the local heat treatment can be used to improve the crash behavior of structural components. In addition, their deformation path can be influenced by using adapted heat treatment patterns and the crash behavior can be controlled.

  19. Investigation of the Hot-Stamping Process for Advanced High-Strength Steel Sheet by Numerical Simulation

    Science.gov (United States)

    Liu, H. S.; Xing, Z. W.; Bao, J.; Song, B. Y.

    2010-04-01

    Hot forming is a new way to manufacture complex-shaped components of advanced high-strength steel (AHSS) sheet with a minimum of spring-back. Numerical simulation is an effective way to examine the hot-forming process, particularly to determine thermal and thermo-mechanical characteristics and their dependencies on temperature, strain and strain rate. The flow behavior of the 22MnB5 AHSS is investigated through hot tensile tests. A 3D finite element (FE) model of hot-stamping process for the [InlineMediaObject not available: see fulltext.] shaped part is built under the ABAQUS/Explicit environment based on the solutions of several key problems, such as treatment of contact between blank and tools, determination of material characteristics and meshing, etc. Numerical simulation is carried out to investigate the influence of blank holder force (BHF) and die gap on the hot-forming process for the [InlineMediaObject not available: see fulltext.] shaped part. Numerical results show the FE model is effective in simulation of hot-forming process. Large BHF reduces the amount of spring-back and improves the contact of flange with tools while avoiding cracking of stamped part. Die gap has a considerable influence on the distribution of temperature on side walls; the larger the die gap, higher is the temperature on the sidewall of [InlineMediaObject not available: see fulltext.] shaped part.

  20. Stamping failure analysis of advanced high strength steel sheet based on non-uniform local deformation through thickness

    Science.gov (United States)

    Huang, Sheng; Zhao, Yixi; He, Chunfeng

    2013-12-01

    The phenomenon "Shear fracture" is often observed in the stretch-bending process of stamping over small radius with advanced high strength steels (AHSS). It occurs parallel to and near the die radius in the stretch-bending test. Since traditional Forming Limit Diagram (FLD) is unable to describe this type of failure, experimental and simulation works were constructed in this paper to investigate and predict the shear fracture. Fracture experiments were carried out through a stretch-bending test system, and failure mode was observed. There is no obviously thinning at the shear fracture surface. Further research shows that the initial crack of shear fracture occurs at the outer layer of specimen at die radius position. Finite element (FE) models were built for stretch-bending test with 3D element. The non-uniform local deformation through thickness corresponding to bending position was obtained and analyzed. Cockcroft & Latham fracture criterion is used. The outer layer of specimen at bending position reaches the critical fracture state firstly, which agrees well with experiments. Different fracture criteria are also compared and selected to determine this fracture. Results show that based on the non-uniform local deformation, the initial crack location of shear fracture at small radius can be effectively predicted by fracture criteria related to the maximum principle stress.

  1. Two-surface plasticity Model and Its Application to Spring-back Simulation of Automotive Advanced High Strength Steel Sheets

    Science.gov (United States)

    Park, Taejoon; Seok, Dong-Yoon; Lee, Chul-Hwan; Noma, Nobuyasu; Kuwabara, Toshihiko; Stoughton, Thomas B.; Chung, Kwansoo

    2011-08-01

    A two-surface isotropic-kinematic hardening law was developed based on a two-surface plasticity model previously proposed by Lee et al., (2007, Int. J. Plast. 23, 1189-1212). In order to properly represent the Bauschinger and transient behaviors as well as permanent softening during reverse loading with various pre-strains, both the inner yield surface and the outer bounding surface expand (isotropic hardening) and translate (kinematic hardening) in this two-surface model. As for the permanent softening, both the isotropic hardening and the kinematic hardening evolution of the outer bounding surface were modified by introducing softening parameters. The numerical formulation was also developed based on the incremental plasticity theory and the developed constitutive law was implemented into the commercial finite element program, ABAQUS/Explicit and ABAQUS/Standard using the user-defined material subroutines. In this work, a dual phase (DP) steel was considered as an advanced high strength steel sheet and uni-axial tension tests and uni-axial tension-compression-tension tests were performed for the characterization of the material property. For a validation purpose, the developed two-surface plasticity model was applied to the 2-D draw bending test proposed as a benchmark problem of the NUMISHEET 2011 conference and successfully validated with experiments.

  2. Temperature and Material Flow Prediction in Friction-Stir Spot Welding of Advanced High-Strength Steel

    Energy Technology Data Exchange (ETDEWEB)

    Miles, Michael; Karki, U.; Hovanski, Yuri

    2014-10-01

    Friction-stir spot welding (FSSW) has been shown to be capable of joining advanced high-strength steel, with its flexibility in controlling the heat of welding and the resulting microstructure of the joint. This makes FSSW a potential alternative to resistance spot welding if tool life is sufficiently high, and if machine spindle loads are sufficiently low that the process can be implemented on an industrial robot. Robots for spot welding can typically sustain vertical loads of about 8 kN, but FSSW at tool speeds of less than 3000 rpm cause loads that are too high, in the range of 11–14 kN. Therefore, in the current work, tool speeds of 5000 rpm were employed to generate heat more quickly and to reduce welding loads to acceptable levels. Si3N4 tools were used for the welding experiments on 1.2-mm DP 980 steel. The FSSW process was modeled with a finite element approach using the Forge* software. An updated Lagrangian scheme with explicit time integration was employed to predict the flow of the sheet material, subjected to boundary conditions of a rotating tool and a fixed backing plate. Material flow was calculated from a velocity field that is two-dimensional, but heat generated by friction was computed by a novel approach, where the rotational velocity component imparted to the sheet by the tool surface was included in the thermal boundary conditions. An isotropic, viscoplastic Norton-Hoff law was used to compute the material flow stress as a function of strain, strain rate, and temperature. The model predicted welding temperatures to within percent, and the position of the joint interface to within 10 percent, of the experimental results.

  3. Temperature and Material Flow Prediction in Friction-Stir Spot Welding of Advanced High-Strength Steel

    Science.gov (United States)

    Miles, M.; Karki, U.; Hovanski, Y.

    2014-10-01

    Friction-stir spot welding (FSSW) has been shown to be capable of joining advanced high-strength steel, with its flexibility in controlling the heat of welding and the resulting microstructure of the joint. This makes FSSW a potential alternative to resistance spot welding if tool life is sufficiently high, and if machine spindle loads are sufficiently low that the process can be implemented on an industrial robot. Robots for spot welding can typically sustain vertical loads of about 8 kN, but FSSW at tool speeds of less than 3000 rpm cause loads that are too high, in the range of 11-14 kN. Therefore, in the current work, tool speeds of 5000 rpm were employed to generate heat more quickly and to reduce welding loads to acceptable levels. Si3N4 tools were used for the welding experiments on 1.2-mm DP 980 steel. The FSSW process was modeled with a finite element approach using the Forge® software. An updated Lagrangian scheme with explicit time integration was employed to predict the flow of the sheet material, subjected to boundary conditions of a rotating tool and a fixed backing plate. Material flow was calculated from a velocity field that is two-dimensional, but heat generated by friction was computed by a novel approach, where the rotational velocity component imparted to the sheet by the tool surface was included in the thermal boundary conditions. An isotropic, viscoplastic Norton-Hoff law was used to compute the material flow stress as a function of strain, strain rate, and temperature. The model predicted welding temperatures to within 4%, and the position of the joint interface to within 10%, of the experimental results.

  4. High strength alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  5. High strength alloys

    Science.gov (United States)

    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J.; John, Randy Carl; Kim, Dong Sub

    2012-06-05

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tublar that is at least partially made from a material containing at least one of the metal alloys.

  6. A review of the physical metallurgy related to the hot press forming of advanced high strength steel

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Dong W.; Kim, Han S.; De Cooman, C. [Pohang Univ. of Science and Technology, Pohang (Korea). Graduate Inst. of Ferrous Technology

    2009-03-15

    The automotive industry requirements for vehicle weight reduction, weight containment, improved part functionality and passenger safety have resulted in the increased use of steel grades with a fully martensitic microstructure. These steel grades are essential to improve the anti-intrusion resistance of automotive body parts and the related passenger safety during car collisions. Standard advanced high strength steel (AHSS) grades are notoriously difficult to be press formed; they are characterized by elastic springback, poor stretch flangeability and low hole expansion ratios. Hot press forming has therefore received much attention recently as an alternative technology to produce AHSS automotive parts. In this contribution, the physical metallurgy principles of the hot press forming process are reviewed. The effect of composition on CCT curves of standard CMnB hot press forming steels is discussed taking the deformation during press forming into account. Furthermore, the effect of the static strain ageing processes occurring during the paint baking cycle on the in-service mechanical properties of press hardened steel will be presented. The influence of temperate and strain rate on the flow stress during press forming and the final room temperature mechanical properties will be discussed. Moreover, the issues related to coatings on B-alloyed CMn hot press forming steel will be critically reviewed. In particular the combined effects of thermal cycle and deformation on the degradation of the Al-10%Si coating will be discussed in detail. Finally, the properties of both Al-based and Zn-based coating systems are compared, and the possibility of the formation of a diffusion barrier during press forming is discussed. (orig.)

  7. Modeling of the hot flow behavior of advanced ultra-high strength steels (A-UHSS) microalloyed with boron

    Energy Technology Data Exchange (ETDEWEB)

    Mejía, I., E-mail: imejia@umich.mx [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio “U”, Ciudad Universitaria, 58066 Morelia, Michoacán (Mexico); Altamirano, G.; Bedolla-Jacuinde, A. [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio “U”, Ciudad Universitaria, 58066 Morelia, Michoacán (Mexico); Cabrera, J.M. [Departament de Ciència dels Materials i Enginyeria Metallúrgica, ETSEIB – Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Fundació CTM Centre Tecnològic, Av. de las Bases de Manresa, 1, 08240 Manresa (Spain)

    2014-07-29

    In this research work, modeling of the hot flow behavior was carried out in a low carbon advanced ultra-high strength steels (A-UHSS) microalloyed with different amounts of boron (14, 33, 82, 126 and 214 ppm). For this purpose, experimental stress–strain data of uniaxial hot-compression tests over a wide range of temperatures (1223, 1273, 1323 and 1373 K (950, 1000, 1050 and 1100 °C)) and strain rates (10{sup −3}, 10{sup −2} and 10{sup −1} s{sup −1}) were used. The stress–strain relationships as a function of temperature and strain rate were successfully described on the basis of the approach proposed by Estrin, Mecking, and Bergström, together with the classical Avrami equation and the conventional hyperbolic sine function. The analysis of the modeling parameters of the hot flow curves shows that boron additions to A-UHSS play a major role in softening mechanisms rather than on hardening. The peak stress (σ{sub p}) and steady-state stress (σ{sub ss}) values show a decreasing trend with increasing boron content, which indicates that boron additions promote a solid solution softening effect additional to that produced by DRX. The time for 50% recrystallization (t{sub 50%}) tends to increase with boron additions, revealing that boron additions cause a delay of the DRX kinetics during hot deformation. Similarly, the presence of boron in the steel decreases the apparent activation energy for recrystallization (Q{sub t}), indicating that boron additions accelerate the onset of DRX. The constitutive equations developed in this way provided an excellent description of the experimental hot flow curves.

  8. A New Method to Calculate Threshold Values of Ductile Fracture Criteria for Advanced High-Strength Sheet Blanking

    Science.gov (United States)

    Wang, Changsheng; Chen, Jun; Xia, Cedric; Ren, Feng; Chen, Jieshi

    2014-04-01

    A new approach is presented in this paper to calculate the critical threshold value of fracture initiation. It is based on the experimental data for forming limit curves and fracture forming limit curves. The deformation path for finally a fractured material point is assumed as two-stage proportional loading: biaxial loading from the beginning to the onset of incipient necking, followed plane strain deformation within the incipient neck until the final fracture. The fracture threshold value is determined by analytical integration and validated by numerical simulation. Four phenomenological models for ductile fracture are selected in this study, i.e., Brozzo, McClintock, Rice-Tracey, and Oyane models. The threshold value for each model is obtained through best-fitting of experimental data. The results are compared with each other and test data. These fracture criteria are implemented in ABAQUS/EXPLICIT through user subroutine VUMAT to simulate the blanking process of advanced high-strength steels. The simulated fracture surfaces are examined to determine the initiation of ductile fracture during the process, and compared with experimental results for DP780 sheet steel blanking. The comparisons between FE simulated results coupled with different fracture models and experimental one show good agreements on punching edge quality. The study demonstrates that the proposed approach to calculate threshold values of fracture models is efficient and reliable. The results also suggest that the McClintock and Oyane fracture models are more accurate than the Rice-Tracey or Brozzo models in predicting load-stroke curves. However, the predicted blanking edge quality does not have appreciable differences.

  9. Weldability of Advanced High Strength Steels using Ytterbium:Yttrium Aluminium Garnet high power laser for Tailor-Welded Blank applications

    Science.gov (United States)

    Sharma, Rajashekhar Shivaram

    Use of a high power Yb:YAG laser is investigated for joining advanced high strength steel materials for use in tailor-welded blank (TWB) applications. TWB's are materials of different chemistry, coating or thicknesses that are joined before metal forming and other operations such as trimming, assembly and painting are carried out. TWB is becoming an important design tool in the automotive industry for reducing weight, improving fuel economy and passenger safety, while reducing the overall costs for the customer. Three advanced high strength steels, TRIP780, DP980 and USIBOR, which have many unique properties that are conducive to achieving these objectives, along with mild steel, are used in this work. The objective of this work is to ensure that high quality welds can be obtained using Yb:YAG lasers which are also becoming popular for metal joining operations, since they produce high quality laser beams that suffer minimal distortion when transported via fiber optic cables. Various power levels and speeds for the laser beam were used during the investigation. Argon gas was consistently used for shielding purposes during the welding process. After the samples were welded, metallographic examination of the fusion and heat-affected zones using optical and scanning electron microscopes were carried out to determine the microstructures as well as weld defects. Optical and scanning electron microscopes were also used to examine the top of welds as well as fracture surfaces. Additionally, cross-weld microhardness evaluations, tensile tests using Instron tester, limited fatigue tests as well as formability evaluations using OSU plane strain evaluation were carried out. The examinations included a 2-factor full factorial design of experiments to determine the impact of coatings on the surface roughness on the top of the welds. Tensile strengths of DP980, TRIP780 and mild steel materials as well as DP980 welded to TRIP780 and mild steel in the rolling direction as well as

  10. FATIGUE STRENGTH OF HIGH-STRENGTH STEEL,

    Science.gov (United States)

    coldhardened by deforming to 83%. It was found that it has low static notch sensitivity (lower than that of heat-treated steels), that static strength ...is raised appreciably by increased cold plastic deformation, and that its fatigue strength is raised substantially by mechanical polishing. (Author)

  11. Effects of Fusion Zone Size and Failure Mode on Peak Load and Energy Absorption of Advanced High Strength Steel Spot Welds

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2007-01-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS). DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. The critical fusion zone sizes to ensure nugget pull-out failure mode are developed for both DP800 and TRIP800 using limit load based analytical model and micro-hardness measurements of the weld cross sections. Static weld strength tests using cross tension samples were performed on the joint populations with controlled fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied for all the weld populations using statistical data analysis tools. The results in this study show that AHSS spot welds with fusion zone size of can not produce nugget pullout mode for both the DP800 and TRIP800 materials examined. The critical fusion zone size for nugget pullout shall be derived for individual materials based on different base metal properties as well as different heat affected zone (HAZ) and weld properties resulted from different welding parameters.

  12. Effects of Fusion Zone Size on Failure Modes and Performance of Advanced High Strength Steel Spot Welds (2006-01-0531)

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2007-03-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS). DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. The critical fusion zone sizes to ensure nugget pull-out failure mode are developed for both DP800 and TRIP800 using the limit load based analytical model and the micro-hardness measurements of the weld cross sections. Static weld strength tests using cross tension samples were performed on the joint populations with controlled fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied using statistical data analysis tools. The results in this study show that the conventional weld size of 4 t1/2 can not produce nugget pullout mode for both the DP800 and TRIP800 materials. The results also suggest that performance based spot weld acceptance criteria should be developed for different AHSS spot welds.

  13. Effects of Fusion Zone Size and Failure Mode on Peak Load and Energy Absorption of Advanced High Strength Steel Spot Welds under Lap Shear Loading Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2008-06-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS) under lap shear loading condition. DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. Static weld strength tests using lap shear samples were performed on the joint populations with various fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied for all the weld populations using statistical data analysis tools. The results in this study show that AHSS spot welds with conventionally required fusion zone size of can not produce nugget pullout mode for both the DP800 and TRIP800 welds under lap shear loading. Moreover, failure mode has strong influence on weld peak load and energy absorption for all the DP800 welds and the TRIP800 small welds: welds failed in pullout mode have statistically higher strength and energy absorption than those failed in interfacial fracture mode. For TRIP800 welds above the critical fusion zone level, the influence of weld failure modes on peak load and energy absorption diminishes. Scatter plots of peak load and energy absorption versus weld fusion zone size were then constructed, and the results indicate that fusion zone size is the most critical factor in weld quality in terms of peak load and energy absorption for both DP800 and TRIP800 spot welds.

  14. Micromechanics of plastic deformation and phase transformation in a three-phase TRIP-assisted advanced high strength steel: Experiments and modeling

    Science.gov (United States)

    Srivastava, Ankit; Ghassemi-Armaki, Hassan; Sung, Hyokyung; Chen, Peng; Kumar, Sharvan; Bower, Allan F.

    2015-05-01

    The micromechanics of plastic deformation and phase transformation in a three-phase advanced high strength steel are analyzed both experimentally and by microstructure-based simulations. The steel examined is a three-phase (ferrite, martensite and retained austenite) quenched and partitioned sheet steel with a tensile strength of ~980 MPa. The macroscopic flow behavior and the volume fraction of martensite resulting from the austenite-martensite transformation during deformation were measured. In addition, micropillar compression specimens were extracted from the individual ferrite grains and the martensite particles, and using a flat-punch nanoindenter, stress-strain curves were obtained. Finite element simulations idealize the microstructure as a composite that contains ferrite, martensite and retained austenite. All three phases are discretely modeled using appropriate crystal plasticity based constitutive relations. Material parameters for ferrite and martensite are determined by fitting numerical predictions to the micropillar data. The constitutive relation for retained austenite takes into account contributions to the strain rate from the austenite-martensite transformation, as well as slip in both the untransformed austenite and product martensite. Parameters for the retained austenite are then determined by fitting the predicted flow stress and transformed austenite volume fraction in a 3D microstructure to experimental measurements. Simulations are used to probe the role of the retained austenite in controlling the strain hardening behavior as well as internal stress and strain distributions in the microstructure.

  15. 先进高强度钢的断裂失效准则研究%STUDY OF FAILURE CRITERION OF ADVANCED HIGH STRENGTH STEEL

    Institute of Scientific and Technical Information of China (English)

    桂良进; 高付海; 范子杰

    2012-01-01

    The advanced high strength steel (AHSS) realizes the outstanding advantage of strength by transforming its internal different phases. It has become one of the hottest materials for current automotive lightweight researches. However, compared with traditional deep-drawing steels, the widespread use of AHSS in auto-industry is hampered due to its poor ductility,which leads to frequent occurrences of failure in the mode of fracture during the process of stamping. Therefore,the fracture prediction of AHSS becomes one of the focuses of current researchers. The dual phase (DP) steel can be seen as the representative of AHSS. In this paper,the fracture criteria of DP steel under different stress states are investigated by combining experimental and numerical analysis and an appropriate failure criterion is attempted to be established for predicting its fracture behavior.%先进高强度钢(AHSS)是通过相变获得高强度的应用前景最好的汽车轻量化材料.与传统深拉钢相比,AHSS韧性相对较低,在冲压成形过程中容易发生断裂,阻碍了它在汽车上的广泛应用,因而AHSS的断裂失效研究成为当前国内外研究的热点.论文以AHSS的代表钢种双相钢(DP)为研究对象,通过试验与数值计算相结合的方法研究其在不同三轴应力状态下的失效特性,尝试寻找一个适用于它的失效准则,用于其断裂失效的预测.

  16. 汽车用先进高强钢的发展及应用%Development and Application of Advanced High Strength Steel for Car

    Institute of Scientific and Technical Information of China (English)

    黄建国

    2015-01-01

    近年来,先进高强钢(Advanced High Strength Steel,AHSS)的研发已进入一个新的阶段.按照强塑积数值的不同,人们将AHSS分为第1代AHSS、第2代AHSS和第3代AHSS.第1代AHSS已经广泛应用于汽车制造领域,第2代AHSS也已应用到汽车的车身设计中.中国钢铁研究总院提出M3组织调控思路,即亚稳(Meta-stable)、多相(Multi-phase)和多尺度(Multi-scale),并率先研发出强塑积在30Gpa%的第3代AHSS.本文介绍了AHSS(如:DP钢、TRIP钢、TWIP钢和Q&P钢等)的工业化生产、汽车制造中的应用和研发进展.

  17. Springback analysis of ultra high strength steel

    Science.gov (United States)

    Tenma, Kenji; Kina, Futoshi; Suzuki, Wataru

    2013-12-01

    It is an inevitable trend in the automotive industry to apply more and more high strength steels and even ultra-high strength steels. Even though these materials are more difficult to process the development time of forming tools must be reduced. In order to keep the development time under control, simulation tools are used to verify the forming process in advance. At Aoi Machine Industry a project has been executed to accurately simulate springback of ultra-high strength steels in order to reduce the tool tryout time. In the first phase of the project the simulation settings were optimized based on B-Pillar model A made of Dual Phase 980. In the second phase, it was verified with B-Pillar model B whether these simulation settings were usable as general setting. Results showed that with the right settings it is very well possible to accurately simulate springback of ultra-high strength steels. In the third phase the project the stamping of a B-Pillar of Dual Phase 1180 was studied.

  18. High strength, tough alloy steel

    Science.gov (United States)

    Thomas, Gareth; Rao, Bangaru V. N.

    1979-01-01

    A high strength, tough alloy steel is formed by heating the steel to a temperature in the austenite range (1000.degree.-1100.degree. C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other substitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300.degree. C.) and reforms to a stable film after austenite grain refinement.

  19. STRENGTH OF NANOMODIFIED HIGH-STRENGTH LIGHTWEIGHT CONCRETES

    Directory of Open Access Journals (Sweden)

    NOZEMTСEV Alexandr Sergeevich

    2013-02-01

    Full Text Available The paper presents the results of research aimed at development of nanomodified high-strength lightweight concrete for construction. The developed concretes are of low average density and high ultimate compressive strength. It is shown that to produce this type of concrete one need to use hollow glass and aluminosilicate microspheres. To increase the durability of adhesion between cement stone and fine filler the authors offer to use complex nanodimensinal modifier based on iron hydroxide sol and silica sol as a surface nanomodifier for hollow microspheres. It is hypothesized that the proposed modifier has complex effect on the activity of the cement hydration and, at the same time increases bond strength between filler and cement-mineral matrix. The compositions for energy-efficient nanomodified high-strength lightweight concrete which density is 1300…1500 kg/m³ and compressive strength is 40…65 MPa have been developed. The approaches to the design of high-strength lightweight concrete with density of less than 2000 kg/m³ are formulated. It is noted that the proposed concretes possess dense homogeneous structure and moderate mobility. Thus, they allow processing by vibration during production. The economic and practical implications for realization of high-strength lightweight concrete in industrial production have been justified.

  20. Progress on Research of Advanced High-Strength Steel for Automobile%先进高强度汽车用钢的研究进展

    Institute of Scientific and Technical Information of China (English)

    郑花

    2016-01-01

    随着全社会对节约能源,保护环境意识的不断提高,轻量化已成为当今汽车工业的一个重要课题。钢铁材料是目前乃至今后很长一段时间内最适合汽车制造的材料,为了满足汽车工业发展的需求,各汽车制造商和钢铁公司都加快了向高强度钢方向的发展。文中对国内外各种高强度钢的研究以及应用现状进行了简述,并对未来汽车用高强度钢的研究方向进行了预测。%With the continuous improvement of the energy and environmental requirements, lightweight has become an important topic for today's automotive industry. Steel is the most suitable material for the manufacture of automobile in the present and future. In order to meet the needs of the developing automobile industry, car manufacturers and steel companies are accelerating to develop high-strength steel. This article introduces the application of all kinds of high-strength steel at home and abroad, and points out the direction of the future high-strength steel for automobile.

  1. High-Strength, Superelastic Compounds

    Science.gov (United States)

    Stanford, Malcolm; Noebe, Ronald; Dellacorte, Christopher; Bigelow, Glen; Thomas, Fransua

    2013-01-01

    can be used in the heat treatment process, less energy will be consumed, and there will be less dimensional distortion and quench cracking. This results in fewer scrap parts, less material waste from large amounts of material removal, and fewer machining steps to rework parts that are out of specification. This material has a combination of properties that have been previously unobtainable. The material has a Young s modulus of approximately 95 GPa (about half that of conventional steels), moderate density (10 to 15% lower than conventional steels), excellent corrosion resistance, and high hardness (58 to 62 HRC). These properties make this material uniquely suited for advanced bearings.

  2. Effect of microstructure on fatigue behavior of advanced high strength steels produced by quenching and partitioning and the role of retained austenite

    Energy Technology Data Exchange (ETDEWEB)

    Diego-Calderón, I. de, E-mail: irenedediego.calderon@imdea.org [IMDEA Materials Institute, Calle Eric Kandel 2, 28906 Getafe, Madrid (Spain); Rodriguez-Calvillo, P. [Fundació CTM Centre Tecnològic, Plaza de la Ciencia 2, 08243 Manresa (Spain); Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica, Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Lara, A. [Fundació CTM Centre Tecnològic, Plaza de la Ciencia 2, 08243 Manresa (Spain); Molina-Aldareguia, J.M. [IMDEA Materials Institute, Calle Eric Kandel 2, 28906 Getafe, Madrid (Spain); Petrov, R.H. [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, B-9052 Zwijnaarde (Ghent) (Belgium); Department of Materials Science and Engineering, Delft University of Technology, 2628 CD Delft (Netherlands); De Knijf, D. [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, B-9052 Zwijnaarde (Ghent) (Belgium); Sabirov, I. [IMDEA Materials Institute, Calle Eric Kandel 2, 28906 Getafe, Madrid (Spain)

    2015-08-12

    Despite the significant body of research on mechanical properties of quenched and partitioned (Q&P) steels, their fatigue behavior has not been investigated. This work focuses on the effect of microstructure on high cycle fatigue of Q&P steels and microstructural evolution during cyclic loading. It is demonstrated that increased content of retained austenite (RA) improves fatigue limit of Q&P steels that is related to delay of crack propagation due to austenite–martensite phase transformation. Increasing stress amplitude promotes austenite–martensite phase transformation during cycling loading. It is shown that size and crystallographic orientation of RA are the main factors determining its stability, whereas its shape and spatial distribution do not seem to affect it significantly. Fatigue crack initiation during fatigue testing with high stress amplitudes occurs by intergranular cracking, whereas transgranular cracking controls fatigue crack initiation during cycling loading with lower stress amplitudes. Transgranular crack propagation dominates in the second stage of fatigue at all stress amplitudes. The final stage of fatigue is also not affected by the stress amplitude. It is suggested that fatigue life of Q&P steels can be enhanced via improvement of strength of grain/interphase boundaries.

  3. Formability Characterization of a New Generation High Strength Steels

    Energy Technology Data Exchange (ETDEWEB)

    Sriram Sadagopan; Dennis Urban; Chris Wong; Mai Huang; Benda Yan

    2003-05-16

    Advanced high strength steels (AHSS) are being progressively explored by the automotive industry all around the world for cost-effective solutions to accomplish vehicle lightweighting, improve fuel economy, and consequently reduce greenhouse emissions. Because of their inherent high strength, attractive crash energy management properties, and good formability, the effective use of AHSS such as Duel Phase and TRIP (Transformation Induced Plasticity) steels, will significantly contribute to vehicle lightweighting and fuel economy. To further the application of these steels in automotive body and structural parts, a good knowledge and experience base must be developed regarding the press formability of these materials. This project provides data on relevant intrinsic mechanical behavior, splitting limits, and springback behavior of several lots of mild steel, conventional high strength steel (HSS), advanced high strength steel (AHSS) and ultra-high strength steel (UHSS), supplied by the member companies of the Automotive Applications Committee (AAC) of the American Iron and Steel Institute (AISI). Two lots of TRIP600, which were supplied by ThyssenKrupp Stahl, were also included in the study. Since sheet metal forming encompasses a very diverse range of forming processes and deformation modes, a number of simulative tests were used to characterize the forming behavior of these steel grades. In general, it was found that formability, as determined by the different tests, decreased with increased tensile strength. Consistant with previous findings, the formability of TRIP600 was found to be exceptionally good for its tensile strength.

  4. 高强钢先进成型技术和本构模型研究现状与发展趋势%Advanced Forming Process for High Strength Steel and Research Status and Development Tendency of Constitutive Model

    Institute of Scientific and Technical Information of China (English)

    孙蓟泉; 李双娇; 尹衍军

    2014-01-01

    High strength steel, the best choice for application in the lightweight technology of automotive body is limited to be used due to the forming technique. The principle, characteristics and present research developments of the advanced forming processes such as hydroforming tech-nology, laser butt welding technology and hot stamping technology are discussed. And also the constitutive model of the advanced high strength steel is explained in order to provide the basis for improving the forming property of the steel.%高强钢是汽车车身轻量化的首选材料,但其成型问题一直是限制其推广应用的重要因素。对高强钢的先进成型技术,如液压成型、激光拼焊、热冲压成型等的原理、特点及最新研究进展进行了论述。同时,对先进高强钢的本构模型进行了阐述,以期对改进高强钢成型性能提供依据。

  5. MECHANICAL STRENGTH OF HIGHLY POROUS CERAMICS

    NARCIS (Netherlands)

    VANDENBORN, IC; SANTEN, A; HOEKSTRA, HD; DEHOSSON, JTM; Born, I.C. van den

    1991-01-01

    This paper reports on the mechanical strength of highly porous ceramics in terms of the Weibull and Duxbury-Leath distributions. More than 1000 side-crushing strength tests on silica-catalyst carriers of various particle sizes have been performed in series. Within a series, preparation conditions we

  6. High-Hot-Strength Ceramic Fibers

    Science.gov (United States)

    Sayir, Ali; Matson, Lawrence E.

    1994-01-01

    Continuous fibers consisting of laminae of alumina and yttrium aluminum garnet offer exceptionally high strength, resistance to creep, and chemical stability at high temperatures. These fibers exceed tensile strength of sapphire fibers. Leading candidates for reinforcement of intermetallic-matrix composites in exhaust nozzles of developmental high-speed civil transport aircraft engines. Other applications are in aerospace, automotive, chemical-process, and power-generation industries.

  7. Cadmium Alternatives for High-Strength Steel

    Science.gov (United States)

    2011-09-22

    191 19b. TELEPHONE NUMBER (include area code) 301 -342-8101 iii Table of Contents Note that original JTP section numbers are preceded by...specified. The focus of this JTP is on high-strength structural alloy steels used for various applications. Alloy AISI 4130 was used for adhesion and...NaCl) solution under constant amplitude loading to determine fatigue life using hourglass specimens prepared from high strength AISI 4340 steel. The

  8. Hydrogen degradation of high strength weldable steels

    OpenAIRE

    J. Ćwiek

    2007-01-01

    Purpose: Purpose of this paper is presentation of hydrogen degradation issue of high strength steels andespecially their welded joints. Establishing of applicable mechanisms of hydrogen-enhanced cracking was theaim of performed research.Design/methodology/approach: High strength quenched and tempered steels grade S690Q were used. Weldedjoints were prepared with typical technology used in shipyards. Susceptibility to hydrogen degradation in seawater under cathodic polarization was evaluated wi...

  9. High toughness-high strength iron alloy

    Science.gov (United States)

    Stephens, J. R.; Witzke, W. R. (Inventor)

    1980-01-01

    An iron alloy is provided which exhibits strength and toughness characteristics at cryogenic temperatures. The alloy consists essentially of about 10 to 16 percent by weight nickel, about 0.1 to 1.0 percent by weight aluminum, and 0 to about 3 percent by weight copper, with the balance being essentially iron. The iron alloy is produced by a process which includes cold rolling at room temperature and subsequent heat treatment.

  10. Development of High Specific Strength Envelope Materials

    Science.gov (United States)

    Komatsu, Keiji; Sano, Masa-Aki; Kakuta, Yoshiaki

    Progress in materials technology has produced a much more durable synthetic fabric envelope for the non-rigid airship. Flexible materials are required to form airship envelopes, ballonets, load curtains, gas bags and covering rigid structures. Polybenzoxazole fiber (Zylon) and polyalirate fiber (Vectran) show high specific tensile strength, so that we developed membrane using these high specific tensile strength fibers as a load carrier. The main material developed is a Zylon or Vectran load carrier sealed internally with a polyurethane bonded inner gas retention film (EVOH). The external surface provides weather protecting with, for instance, a titanium oxide integrated polyurethane or Tedlar film. The mechanical test results show that tensile strength 1,000 N/cm is attained with weight less than 230g/m2. In addition to the mechanical properties, temperature dependence of the joint strength and solar absorptivity and emissivity of the surface are measured. 

  11. 面向汽车轻量化的先进高强度钢成型技术%Molding Technology of Advanced High Strength Steel for Automobile Lightweight

    Institute of Scientific and Technical Information of China (English)

    李琦; 阳林; 贺绍华

    2012-01-01

    Automobile lightweight is an important direction for energy saving and emission reduction to the modern automobile.Now the use of advanced high strength steel(AHSS) is a main way.However,its molding difficult is the main technical problem.In this paper,the authors analyze the mechanisms and characteristics,the molding technology and their application of the five types of AHSS in detail.%汽车轻量化是现代汽车节能减排的重要方向,采用先进高强度钢是其主要途径,当前的技术难点在于先进高强度钢成型困难。本文详细分析五种先进高强度钢的机理特性、成型技术及其应用。

  12. Mechanical properties of high-strength concrete

    Science.gov (United States)

    Mokhtarzadeh, Alireza

    This report summarizes an experimental program conducted to investigate production techniques and mechanical properties of high strength concrete in general and to provide recommendations for using these concretes in manufacturing precast/prestressed bridge girders. Test variables included total amount and composition of cementitious material (portland cement, fly ash, and silica fume), type and brand of cement, type of silica fume (dry densified and slurry), type and brand of high-range water-reducing admixture, type of aggregate, aggregate gradation, maximum aggregate size, and curing. Tests were conducted to determine the effects of these variables on changes in compressive strength and modulus of elasticity over time, splitting tensile strength, modulus of rupture, creep, shrinkage, and absorption potential (as an indirect indicator of permeability). Also investigated were the effects of test parameters such as mold size, mold material, and end condition. Over 6,300 specimens were cast from approximately 140 mixes over a period of 3 years.

  13. Recent Progress in High Strength Low Carbon Steels

    Directory of Open Access Journals (Sweden)

    Zrník J.

    2006-01-01

    Full Text Available Advanced High Strength (AHS steels, among them especially Dual Phase (DP steels, Transformation Induced Plasticity (TRIP steels, Complex Phase (CP steels, Partially Martensite (PM steels, feature promising results in the field. Their extraordinary mechanical properties can be tailored and adjusted by alloying and processing. The introduction of steels with a microstructure consisting at least of two different components has led to the enlargement of the strength level without a deterioration of ductility. Furthermore, the development of ultra fine-grained AHS steels and their service performance are reviewed and new techniques are introduced. Various projects have been devoted to develop new materials for flat and long steel products for structural applications. The main stream line is High Strength, in order to match the weight lightening requirements that concern the whole class of load bearing structures and/or steel components and one of the most investigated topics is grain refinement.

  14. Strength Regularity and Failure Criterion of High-Strength High-Performance Concrete under Multiaxial Compression

    Institute of Scientific and Technical Information of China (English)

    HE Zhen-jun; SONG Yu-pu

    2008-01-01

    Multiaxial compression tests were performed on 100 mm × 100 mm × 100 nun high-strength high-performance concrete (HSHPC) cubes and normal strength concrete (NSC) cubes. The failure modes of specimens were presented, the static compressive strengths in principal directions were measured, the influence of the stress ratios was analyzed. The experimental results show that the ultimate strengths for HSHPC and NSC under multiaxial compression are greater than the uniaxial compressive strengths at all stress ratios, and the multiaxial strength is dependent on the brittleness and stiffness of concrete, the stress state and the stress ratios. In addition, the Kupfer-Gerstle and Ottosen's failure criteria for plain HSHPC and NSC under multiaxial compressive loading were modified.

  15. 先进高强度双相钢汽车板剪切断裂实验%Experimental Study of Shear Fracture on Advanced High Strength Dual-Phase Steels

    Institute of Scientific and Technical Information of China (English)

    李梅; 赵亦希; 胡星; 黄胜

    2011-01-01

    Fracture characteristics of advanced high strength DP(dual-phase) sheets in stretch-bending over a tight die radius were investigated through flanging and groove-shape dies.Flanging result shows the higher the strength grade of DP sheet is,the more chance shear fracture occurs.The groove-shape tests and simulations suggest the shear fracture around the tight radius only occurs under high BHF,and necking on the wall happens when BHF is low.The eventual failure mode during sheet metal forming operations of AHSS is viewed as the competition between necking and shear fracture,whichever criterion is satisfied first.%通过翻边实验和槽型件实验,研究了先进高强度双相(DP)钢在小半径拉弯成形中的断裂特性.翻边实验表明,高强度DP钢强度级别越高越容易发生剪切断裂.槽型件实验与仿真表明,高强度DP钢的断裂特性与压边力大小关系密切,压边力大则弯曲圆角处容易发生剪切断裂;压边力小则易在侧壁上发生颈缩断裂.先进高强度DP钢最终的断裂模式是剪切断裂和颈缩断裂相互竞争的结果,任一断裂条件先达到则板料发生该种断裂.

  16. High-strength mineralized collagen artificial bone

    Science.gov (United States)

    Qiu, Zhi-Ye; Tao, Chun-Sheng; Cui, Helen; Wang, Chang-Ming; Cui, Fu-Zhai

    2014-03-01

    Mineralized collagen (MC) is a biomimetic material that mimics natural bone matrix in terms of both chemical composition and microstructure. The biomimetic MC possesses good biocompatibility and osteogenic activity, and is capable of guiding bone regeneration as being used for bone defect repair. However, mechanical strength of existing MC artificial bone is too low to provide effective support at human load-bearing sites, so it can only be used for the repair at non-load-bearing sites, such as bone defect filling, bone graft augmentation, and so on. In the present study, a high strength MC artificial bone material was developed by using collagen as the template for the biomimetic mineralization of the calcium phosphate, and then followed by a cold compression molding process with a certain pressure. The appearance and density of the dense MC were similar to those of natural cortical bone, and the phase composition was in conformity with that of animal's cortical bone demonstrated by XRD. Mechanical properties were tested and results showed that the compressive strength was comparable to human cortical bone, while the compressive modulus was as low as human cancellous bone. Such high strength was able to provide effective mechanical support for bone defect repair at human load-bearing sites, and the low compressive modulus can help avoid stress shielding in the application of bone regeneration. Both in vitro cell experiments and in vivo implantation assay demonstrated good biocompatibility of the material, and in vivo stability evaluation indicated that this high-strength MC artificial bone could provide long-term effective mechanical support at human load-bearing sites.

  17. Making High-Tensile-Strength Amalgam Components

    Science.gov (United States)

    Grugel, Richard

    2008-01-01

    Structural components made of amalgams can be made to have tensile strengths much greater than previously known to be possible. Amalgams, perhaps best known for their use in dental fillings, have several useful attributes, including room-temperature fabrication, corrosion resistance, dimensional stability, and high compressive strength. However, the range of applications of amalgams has been limited by their very small tensile strengths. Now, it has been discovered that the tensile strength of an amalgam depends critically on the sizes and shapes of the particles from which it is made and, consequently, the tensile strength can be greatly increased through suitable choice of the particles. Heretofore, the powder particles used to make amalgams have been, variously, in the form of micron-sized spheroids or flakes. The tensile reinforcement contributed by the spheroids and flakes is minimal because fracture paths simply go around these particles. However, if spheroids or flakes are replaced by strands having greater lengths, then tensile reinforcement can be increased significantly. The feasibility of this concept was shown in an experiment in which electrical copper wires, serving as demonstration substitutes for copper powder particles, were triturated with gallium by use of a mortar and pestle and the resulting amalgam was compressed into a mold. The tensile strength of the amalgam specimen was then measured and found to be greater than 10(exp 4) psi (greater than about 69 MPa). Much remains to be done to optimize the properties of amalgams for various applications through suitable choice of starting constituents and modification of the trituration and molding processes. The choice of wire size and composition are expected to be especially important. Perusal of phase diagrams of metal mixtures could give insight that would enable choices of solid and liquid metal constituents. Finally, whereas heretofore, only binary alloys have been considered for amalgams

  18. The Bendability of Ultra High strength Steels

    Science.gov (United States)

    Hazra, S. K.; Efthymiadis, P.; Alamoudi, A.; Kumar, R. L. V.; Shollock, B.; Dashwood, R.

    2016-08-01

    Automotive manufacturers have been reducing the weight of their vehicles to meet increasingly stringent environmental legislation that reflects public demand. A strategy is to use higher strength materials for parts with reduced cross-sections. However, such materials are less formable than traditional grades. The frequent result is increased processing and piece costs. 3D roll forming is a novel and flexible process: it is estimated that a quarter of the structure of a vehicle can be made with a single set of tooling. Unlike stamping, this process requires material with low work hardening rates. In this paper, we present results of ultra high strength steels that have low elongation in a tension but display high formability in bending through the suppression of the necking response.

  19. High-strength iron aluminide alloys

    Energy Technology Data Exchange (ETDEWEB)

    McKamey, C.G.; Maziasz, P.J.

    1996-06-01

    Past studies have shown that binary Fe{sub 3}Al possesses low creep-rupture strength compared to many other alloys, with creep-rupture lives of less than 5 h being reported for tests conducted at 593{degrees}C and 207 MPa. The combination of poor creep resistance and low room-temperature tensile ductility due to a susceptibility to environmentally-induced dynamic hydrogen embrittlement has limited use of these alloys for structural applications despite their excellent corrosion properties. With regard to the ductility problem, alloy development efforts have produced significant improvements, with ductilities of 10-20% and tensile yield strengths as high as 500 MPa being reported. Likewise, initial improvements in creep resistance have been realized through small additions of Mo, Nb, and Zr.

  20. HIGH STRENGTH CONTROL RODS FOR NEUTRONIC REACTORS

    Science.gov (United States)

    Lustman, B.; Losco, E.F.; Cohen, I.

    1961-07-11

    Nuclear reactor control rods comprised of highly compressed and sintered finely divided metal alloy panticles and fine metal oxide panticles substantially uniformly distributed theretbrough are described. The metal alloy consists essentially of silver, indium, cadmium, tin, and aluminum, the amount of each being present in centain percentages by weight. The oxide particles are metal oxides of the metal alloy composition, the amount of oxygen being present in certain percentages by weight and all the oxygen present being substantially in the form of metal oxide. This control rod is characterized by its high strength and resistance to creep at elevated temperatures.

  1. High-strength iron aluminide alloys

    Energy Technology Data Exchange (ETDEWEB)

    McKamey, C.G.; Marrero-Santos, Y.; Maziasz, P.J.

    1995-06-01

    Past studies have shown that binary Fe{sub 3}Al possesses low creep-rupture strength compared to many other alloys, with creep-rupture lives of less than 5 h being reported for tests conducted at 593{degrees}C and 207 MPa. The combination of poor creep resistance and low room-temperature tensile density due to a susceptibility to environmentally-induced dynamic hydrogen embrittlement has limited use of these alloys for structural applications, despite their excellent corrosion properties. Improvements in room temperature tensile ductility have been realized mainly through alloying effects, changes in thermomechanical processing to control microstructure, and by control of the specimen`s surface condition. Ductilities of 10-20% and tensile yield strengths as high as 500 MPa have been reported. In terms of creep-rupture strength, small additions of Mo, Nb, and Zr have produced significant improvements, but at the expense of weldability and room-temperature tensile ductility. Recently an alloy containing these additions, designated FA-180, was shown to exhibit a creep-rupture life of over 2000 h after a heat treatment of 1 h at 1150{degrees}C. This study presents the results of creep-rupture tests at various test temperatures and stresses and discusses the results as part of our effort to understand the strengthening mechanisms involved with heat treatment at 1150{degrees}C.

  2. Mechanical Properties of Heat Affected Zone of High Strength Steels

    Science.gov (United States)

    Sefcikova, K.; Brtnik, T.; Dolejs, J.; Keltamaki, K.; Topilla, R.

    2015-11-01

    High Strength Steels became more popular as a construction material during last decade because of their increased availability and affordability. On the other hand, even though general use of Advanced High Strength Steels (AHSS) is expanding, the wide utilization is limited because of insufficient information about their behaviour in structures. The most widely used technique for joining steels is fusion welding. The welding process has an influence not only on the welded connection but on the area near this connection, the so-called heat affected zone, as well. For that reason it is very important to be able to determine the properties in the heat affected zone (HAZ). This area of investigation is being continuously developed in dependence on significant progress in material production, especially regarding new types of steels available. There are currently several types of AHSS on the world market. Two most widely used processes for AHSS production are Thermo-Mechanically Controlled Processing (TMCP) and Quenching in connection with Tempering. In the presented study, TMCP and QC steels grade S960 were investigated. The study is focused on the changes of strength, ductility, hardness and impact strength in heat affected zone based on the used amount of heat input.

  3. TRP 9904 - Constitutive Behavior of High Strength Multiphase Sheel Steel Under High Strain Rate Deformation

    Energy Technology Data Exchange (ETDEWEB)

    David Matlock; John Speer

    2005-03-31

    The focus of the research project was to systematically assess the strain rate dependence of strengthening mechanisms in new advanced high strength sheet steels. Data were obtained on specially designed and produced Duel Phase and TRIP steels and compared to the properties of automotive steels currently in use.

  4. Corner strength enhancement of high strength cold-formed steel at normal room and elevated temperatures

    Institute of Scientific and Technical Information of China (English)

    Ju CHEN; Wei-liang JIN

    2008-01-01

    In this study,the suitability of current design methods for the 0.2% proof yield strength of the comer regions for high strength cold-formed steel at norrnal room temperature was investigated.The current standard predictions are generally accurate for outer comer specimen but conservative for inner comer specimen.Based on the experimental results,an analytical model to predict the comer strength of high strength cold-formed steel at normal room temperature was also proposed.The comparison indicated that the proposed model predicted well the comer strength of high strength cold-formed steel not only at normal room temperature but also at elevated temperatures.It is shown that the predictions obtained from the proposed model agree well with the test results.Generally the comer strength enhancement of high strength cold-formed steel decreases when the temperature increases.

  5. 汽车用第3代先进高强度钢的研发进展%Progress on Research and Development of 3rd Generation of Advanced High-Strength Steel for Car

    Institute of Scientific and Technical Information of China (English)

    张志勤; 黄维; 高真凤

    2013-01-01

    近几十年来,汽车用先进高强度钢(AHSS-Advanced High Strength Steel)是材料的研发重点.第1代以铁素体为基的AHSS钢的强塑积为15 GPa·%,第2代以奥氏体为基的AHSS钢的强塑积为50 GPa·%,其合金含量高和生产工艺控制困难导致成本高,因此正研发第3代多相AHSS钢,通过多相、亚稳和多尺度的组织精细调控,其强塑积为30 GPa·%.第3代AHSS钢以提高第1代AHSS钢强度、塑性和降低第2代AHSS合金含量、生产成本两方面进行研发.本文介绍了超细DP(双相)钢,改进型TRIP(相变诱发塑性)钢,淬火-碳分配(Q&P)钢,超细晶贝氏体钢,超快加热和冷却的贝氏体-铁素体-马氏体钢,高锰铁素体-奥氏体钢和中锰亚稳奥氏体-超细晶基体钢等第3代AHSS钢的研究进展.

  6. High strength air-dried aerogels

    Science.gov (United States)

    Coronado, Paul R.; Satcher, Jr., Joe H.

    2012-11-06

    A method for the preparation of high strength air-dried organic aerogels. The method involves the sol-gel polymerization of organic gel precursors, such as resorcinol with formaldehyde (RF) in aqueous solvents with R/C ratios greater than about 1000 and R/F ratios less than about 1:2.1. Using a procedure analogous to the preparation of resorcinol-formaldehyde (RF) aerogels, this approach generates wet gels that can be air dried at ambient temperatures and pressures. The method significantly reduces the time and/or energy required to produce a dried aerogel compared to conventional methods using either supercritical solvent extraction. The air dried gel exhibits typically less than 5% shrinkage.

  7. Advances in high temperature chemistry

    CERN Document Server

    Eyring, Leroy

    1969-01-01

    Advances in High Temperature Chemistry, Volume 2 covers the advances in the knowledge of the high temperature behavior of materials and the complex and unfamiliar characteristics of matter at high temperature. The book discusses the dissociation energies and free energy functions of gaseous monoxides; the matrix-isolation technique applied to high temperature molecules; and the main features, the techniques for the production, detection, and diagnosis, and the applications of molecular beams in high temperatures. The text also describes the chemical research in streaming thermal plasmas, as w

  8. Fatigue strength of welded connections made of very high strength cast and rolled steels

    NARCIS (Netherlands)

    Pijpers, R.J.M.

    2011-01-01

    Although Very High Strength Steels (VHSS) with nominal strengths up to 1100 MPa have been available on the market for many years, the use of these steels in the civil engineering industry is still uncommon. The main objective of the research is the determination of the fatigue strength of welded con

  9. Strength analysis of laser welded lap joint for ultra high strength steel

    Science.gov (United States)

    Jeong, Young Cheol; Kim, Cheol Hee; Cho, Young Tae; Jung, Yoon Gyo

    2013-12-01

    Several industries including the automotive industry have recently applied the process of welding high strength steel. High strength steel is steel that is harder than normal high strength steel, making it much stronger and stiffer. HSS can be formed in pieces that can be up to 10 to 15 percent thinner than normal steel without sacrificing strength, which enables weight reduction and improved fuel economy. Furthermore, HSS can be formed into complex shapes that can be welded into structural areas. This study is based on previous experiments and is aimed at establishing the stress distribution for laser welded high strength steel. Research on the stress distribution for laser welded high strength steel is conducted by using Solid Works, a program that analyzes the stress of a virtual model. In conclusion, we found that the stress distribution is changed depending on the shape of welded lap joint. In addition, the Influence of the stress distribution on welded high strength steel can be used to standard for high energy welding of high strength steel, and we can also predict the region in welded high strength steel that may cracked.

  10. Aluminum/steel wire composite plates exhibit high tensile strength

    Science.gov (United States)

    1966-01-01

    Composite plate of fine steel wires imbedded in an aluminum alloy matrix results in a lightweight material with high tensile strength. Plates have been prepared having the strength of titanium with only 85 percent of its density.

  11. High Strength, Weldable Precipitation Aged Steels

    Science.gov (United States)

    Wilson, Alexander D.

    1987-03-01

    The family of plate steels represented by ASTM Specification A7101 is finding increasing applications. These low carbon, Cu-Ni-Cr-Mo-Cb, copper precipitation hardened steels have been identified by a number of designations over the years. During early development in the late 1960's and first commercial production in 1970, the steels were known as IN-787 (trademark of International Nickel Company).2 ASTM specifications were subsequently developed for structural (A710) and pressure vessel (A736) applications over ten years ago. More recent interest and application of this family of steels by the U.S. Navy has lead to development of a military specification MIL-S-24645 (SH),3 also initially known as "HSLA-80." Significant tonnage is being produced for the U.S. Navy as a replacement for HY80 (MIL-S-16216) in cruiser deck, bulkhead and hull applications.4 In these applications, the enhanced weldability and requirement of no preheat at this high strength and toughness level has been the main motivation for its use. Over the past 15 years, A710 type steels have also been used in a variety of applications, including off-shore platforms, pressure vessels, arctic linepipe valves and off-highway mining truck frames.

  12. Strength Modeling of High-Strength Concrete with Hybrid Fibre Reinforcement

    Directory of Open Access Journals (Sweden)

    A. Ravichandran

    2009-01-01

    Full Text Available The low tensile strength and limited ductility, the unavoidable deficiency, of concrete can be overcome by the addition of fibres. High strength concrete (HSC of 60 MPa containing hybrid fibres, combination of steel and polyolefin fibres, at different volume fraction of 0.5, 1.0, 1.5 and 2.0% were compared in terms of compressive, splitting tensile strength and flexural properties with HSC containing no fibres. Test results showed that the fibres when used in hybrid form could result in enhanced flexural toughness compared to steel fibre reinforced concrete [HSFRC]. The compressive strength of the fibre-reinforced concrete reached maximum at 1.5% volume fractions and the splitting tensile strength and modulus of rupture improved with increasing volume fraction. Strength models were established to predict the compressive and splitting tensile strength and modulus of rupture of the fibre-reinforced concrete. The models give prediction matching the measurements.

  13. Gaseous hydrogen embrittlement of high strength steels

    Science.gov (United States)

    Gangloff, R. P.; Wei, R. P.

    1977-01-01

    The effects of temperature, hydrogen pressure, stress intensity, and yield strength on the kinetics of gaseous hydrogen assisted crack propagation in 18Ni maraging steels were investigated experimentally. It was found that crack growth rate as a function of stress intensity was characterized by an apparent threshold for crack growth, a stage where the growth rate increased sharply, and a stage where the growth rate was unchanged over a significant range of stress intensity. Cracking proceeded on load application with little or no detectable incubation period. Gaseous hydrogen embrittlement susceptibility increased with increasing yield strength.

  14. Development of K-Basin High-Strength Homogeneous Sludge Simulants and Correlations Between Unconfined Compressive Strength and Shear Strength

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Yasuo; Baer, Ellen BK; Chun, Jaehun; Yokuda, Satoru T.; Schmidt, Andrew J.; Sande, Susan; Buchmiller, William C.

    2011-02-20

    K-Basin sludge will be stored in the Sludge Transport and Storage Containers (STSCs) at an interim storage location on Central Plateau before being treated and packaged for disposal. During the storage period, sludge in the STSCs may consolidate/agglomerate, potentially resulting in high-shear-strength material. The Sludge Treatment Project (STP) plans to use water jets to retrieve K-Basin sludge after the interim storage. STP has identified shear strength to be a key parameter that should be bounded to verify the operability and performance of sludge retrieval systems. Determining the range of sludge shear strength is important to gain high confidence that a water-jet retrieval system can mobilize stored K-Basin sludge from the STSCs. The shear strength measurements will provide a basis for bounding sludge properties for mobilization and erosion. Thus, it is also important to develop potential simulants to investigate these phenomena. Long-term sludge storage tests conducted by Pacific Northwest National Laboratory (PNNL) show that high-uranium-content K-Basin sludge can self-cement and form a strong sludge with a bulk shear strength of up to 65 kPa. Some of this sludge has 'paste' and 'chunks' with shear strengths of approximately 3-5 kPa and 380-770 kPa, respectively. High-uranium-content sludge samples subjected to hydrothermal testing (e.g., 185 C, 10 hours) have been observed to form agglomerates with a shear strength up to 170 kPa. These high values were estimated by measured unconfined compressive strength (UCS) obtained with a pocket penetrometer. Due to its ease of use, it is anticipated that a pocket penetrometer will be used to acquire additional shear strength data from archived K-Basin sludge samples stored at the PNNL Radiochemical Processing Laboratory (RPL) hot cells. It is uncertain whether the pocket penetrometer provides accurate shear strength measurements of the material. To assess the bounding material strength and

  15. Development of a high strength high toughness ausferritic steel

    Energy Technology Data Exchange (ETDEWEB)

    Putatunda, Susil K., E-mail: sputa@eng.wayne.edu [Department of Chemical Engineering and Material Science, Wayne State University, 5050 Anthony Wayne Dr., Detroit, MI 48202 (United States); Singar, Arjun V. [Department of Chemical Engineering and Material Science, Wayne State University, 5050 Anthony Wayne Dr., Detroit, MI 48202 (United States); Tackett, Ronald; Lawes, Gavin [Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201 (United States)

    2009-07-15

    A new ausferritic steel with high strength and exceptionally high fracture toughness has been developed. This steel has been synthesized integrating concepts from Austempered Ductile Cast Iron (ADI) technology. The influence of the austempering temperature on the microstructure and mechanical properties of this steel at room temperature and ambient atmosphere has been examined. The effect of microstructure on the plane strain fracture toughness and on the magnetic, electrical, and thermal properties was also investigated. Compact tension and cylindrical tensile specimens prepared from the low alloy medium carbon steel with high silicon content were initially austenitized at 927 deg. C for 2 h and then subsequently austempered at several temperatures between 260 deg. C (500 F) and 400 deg. C (750 F) to produce different microstructures. The microstructures were characterized by X-ray diffraction, scanning electron microscopy and optical metallography. A combination of exceptionally high yield strength (1336 MPa) and a high fracture of toughness of 116 MPa{radical}m (a value comparable to maraging steel) was obtained in this steel after austempering at 316 deg. C (600 F) for 2 h. Potential applications of this steel include the inexpensive fabrication of armored plates and components requiring high reliability and durability.

  16. 信息动态%Size Effect on Strength of Ultra-high Strength Concrete RPC

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Reactive Powder Concrete (RPC)is a new kind of ultra-high strength cement based composite with excellent mechanics performance and durability. In order to make RPC used in structural engineering effectively,size effect on strength of the ultra high strength concrete RPC specimen is experimental studied and the mechanism is analyzed in this paper. Test results show that if the 4 cm cube compressive strength is the control strength,conversion coefficients of 10 em cube compressive strength at 150 MPa and 200 MPa grade are 0.81 and 0.76 respectively; conversion coefficients of 10 cm× 10 cm× 30 cm prism compressive strength at 150 MPa and 200 MPa grade are 0.71 and 0. 63 respectively; the size effect conversion coefficient tends to decrease with the increase of control strength, the larger the specimen size, the lower the compressive strength. RPC is a typical brittle material. It extends instability quickly after cracking;damage concentrated in the local area,and therefore appears higher size effect.

  17. Weldability and Strength Recovery of NUCu-140 Advanced Naval Steel

    Science.gov (United States)

    Bono, Jason T.

    NUCu-140 is a ferritic copper-precipitation strengthened steel that is a candidate material for use in many naval and structural applications. Previous work has shown that the heat-affected zone (HAZ) and fusion zone (FZ) of NUCu-140 exhibit softening that is due to dissolution of the copper-rich precipitates. This study aims to recover the FZ and HAZ strength by re-precipitation of the copper-rich precipitates through either multiple weld passes or an isothermal post-weld heat treatment (PWHT). The potential use of multiple thermal cycles was investigated with HAZ simulations using a Gleeble thermomechanical simulator. The HAZ simulations represented two weld thermal cycles with different combinations of peak temperatures during the initial and secondary weld passes. To investigate the potential for a PWHT for strength recovery, gas tungsten arc weld (GTAW) samples were isothermally heated for various times and temperatures. Microhardness measurements revealed no strength recovery in the multipass HAZ samples. The time dependent precipitate characteristics were modeled under the HAZ thermal cycle conditions, and the results showed that the lack of strength recovery could be attributed to insufficient time for re-precipitation during the secondary weld pass. Conversely, full strength recovery in the HAZ was observed in the isothermally heat treated samples. Atom-probe tomography (APT) analysis correlated this strength recovery to re-precipitation of the copper-rich precipitates during the isothermal PWHT. The experimental naval steel known as NUCu-140 and an established naval steel HSLA-100 were subjected to stress-relief cracking (SRC) and hot-ductility testing to assess their relative cracking susceptibilities during the welding process and post weld heat treatment. NUCu-140 exhibited a longer time-to-failure (TTF) and a lower temperature of minimum TTF during SRC testing when compared to HSLA-100, indicating better resistance to SRC for the NUCu-140 steel. The

  18. Mechanical behavior of high strength ceramic fibers at high temperatures

    Science.gov (United States)

    Tressler, R. E.; Pysher, D. J.

    1991-01-01

    The mechanical behavior of commercially available and developmental ceramic fibers, both oxide and nonoxide, has been experimentally studied at expected use temperatures. In addition, these properties have been compared to results from the literature. Tensile strengths were measured for three SiC-based and three oxide ceramic fibers for temperatures from 25 C to 1400 C. The SiC-based fibers were stronger but less stiff than the oxide fibers at room temperature and retained more of both strength and stiffness to high temperatures. Extensive creep and creep-rupture experiments have been performed on those fibers from this group which had the best strengths above 1200 C in both single filament tests and tests of fiber bundles. The creep rates for the oxides are on the order of two orders of magnitude faster than the polymer derived nonoxide fibers. The most creep resistant filaments available are single crystal c-axis sapphire filaments. Large diameter CVD fabricated SiC fibers are the most creep and rupture resistant nonoxide polycrystalline fibers tested to date.

  19. High-strength concrete for Peacekeeper facilities

    Science.gov (United States)

    Saucier, K. L.

    1984-03-01

    An investigation is described which was conducted to determine the processes and techniques required to produce portland-cement concrete with a compressive strength of 15,000 psi or greater using conventional concreting methods and equipment, and to develop physical property data on the mixtures. It was permitted that special materials and admixtures be used, but a requirement was set that the aggregates and cements be selected from those available in the Cheyenne, Wyoming, area. Results indicated that it is feasible to achieve the 15,000-psi compressive strengths but that workability may decrease over a 2-hour period, and this latter development should be studied under job conditions. It is recommended that: (1) all materials and procedures to be used on a specific project be tested in the laboratory for basic property information, and (2) selected mixtures be tested in the field under expected environmental conditions prior to actual job use.

  20. Performance of High-Strength Concrete Using Palm Oil Fuel Ash as Partial Cement Replacement

    Directory of Open Access Journals (Sweden)

    Dr. M. Swaroopa Rani

    2015-04-01

    Full Text Available The advancement in material technology has led to development of concrete with higher strengths. Presence of high cementitious materials contents in high strength concrete mixes increases heat of hydration that causes higher shrinkage and leading it to potential of cracking. However, use of supplementary cementitious materials leads to control in heat of hydration which further avoids higher shrinkage. Materials such as fly ash, silica fume, metakaolin and ground granulated blast furnace slag are largely been used as supplementary cementitious materials in High strength concrete mixes. In the present study use of palm oil fuel ash (POFA as partial cement replacement in high strength concrete mixes is evaluated with an experimental study. High strength concrete mix of M60 grade is taken as a reference and the compressive strength, split tensile strength and flexural strength where performed for 7, 28 and 56 days and analyzed it with results for partial replacement mixes of POFA 5%, 10%, 15%, 20% & 25%. It has been observed that concrete with 15% replacement of POFA gave the highest strength.

  1. Fatigue-induced damage of high-strength steels

    Science.gov (United States)

    Shetulov, D. I.; Myl'nikov, V. V.

    2014-03-01

    The issues on the estimation of the surface damage of the products produced from high-strength alloys are considered. Mathematical relationships for a numerical calculation of the surface damage are given. The peculiarities of the evaluation of the surface damage are investigated, as applied to high-strength alloys.

  2. Relationship between tensile strength and porosity for high porosity metals

    Institute of Scientific and Technical Information of China (English)

    刘培生; 付超; 李铁藩; 师昌绪

    1999-01-01

    An analysis model has been established according to the structure feature of high porosity metals, and the mathematical relationship between the tensile strength and porosity for this material has been derived from the model. Moreover, the corresponding theoretical formula has been proved good to reflect the variation law of tensile strength with porosity for high porosity metals by the example experiment on nickel foam.

  3. Strength of precast concrete shear joints reinforced with high-strength wire ropes

    DEFF Research Database (Denmark)

    Joergensen, Henrik B.; Hoang, Linh Cao; Hagsten, Lars German

    2017-01-01

    This paper concerns the in-plane shear strength of connections between precast concrete wall elements reinforced with looped high-strength wire ropes. The looped wire ropes are pre-installed in so-called ‘wire boxes’ which function as shear keys. Although only a small amount of research...... on the shear strength of such connections can be found in the literature, this type of connection is increasingly being used because wire ropes are much more construction-friendly than traditional U-bars. A rigid plastic upper bound model for the shear strength of wall connections reinforced with looped wire...... ropes that are pre-installed in wire boxes is presented along with test results on the shear strength of connections with double-wire boxes. It is shown that the plastic solution agrees well with both the obtained test results and results from previously conducted tests....

  4. Double network hydrogel with high mechanical strength:Performance, progress and future perspective

    Institute of Scientific and Technical Information of China (English)

    CHEN YongMei; DONG Kun; LIU ZhenQi; XU Feng

    2012-01-01

    With high water content (~90 wt%) and significantly improved mechanical strength (~MPa),double network (DN) hydrogels have emerged as promising biomaterials with widespread applications in biomedicine.In recent years,DN hydrogels with extremely high mechanical strength have achieved great advance,and scientists have designed a series of natural and biomimetic DN hydrogels with novel functions including low friction,low wear,mechanical anisotropy and cell compatibility.These advances have also led to new design of biocompatible DN hydrogels for regeneration of tissues such as cartilage.In this paper,we reviewed the strategies of designing high-strength DN hydrogel and analyzed the factors that affect DN hydrogel properties.We also discussed the challenges and future development of the DN hydrogel in view of its potential as biomaterials for their biomedical applications.

  5. Investigation of the plastic fracture of high strength steels

    Science.gov (United States)

    Cox, T. B.; Low, J. R., Jr.

    1972-01-01

    This investigation deals in detail with the three recognized stages of plastic fracture in high strength steels, namely, void initiation, void growth, and void coalescence. The particular steels under investigation include plates from both commercial purity and high purity heats of AISI 4340 and 18 Ni, 200 grade maraging steels. A scanning electron microscope equipped with an X-ray energy dispersive analyzer, together with observations made using light microscopy, revealed methods of improving the resistance of high strength steels to plastic fracture.

  6. Confined High Strength Concrete Columns: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Jagannathan Saravanan

    2010-01-01

    Full Text Available Problem statement: An experimental study on GFRP confined high strength concrete columns has been carried out with a view to evaluate its performances under uni-axial compression in terms of load and deformation capacity. Approach: High strength concrete columns strengthened with different configuration and stiffness of GFRP wraps were tested under axial compression until failure. Their response evaluated at different load levels. Results: The test results clearly indicated GFRP wrapped high strength concrete columns exhibit enhances performance. Conclusion: The study concluded that the three GFRP materials attempted UDC GFRP provided the maximum benefit with respect to load and deformation.

  7. Autogenous Shrinkage of High Strength Lightweight Aggregate Concrete

    Institute of Scientific and Technical Information of China (English)

    DING Qingjun; TIAN Yaogang; WANG Fazhou; ZHANG Feng; HU Shuguang

    2005-01-01

    The characteristic of autogenous shrinkage ( AS ) and its effect on high strength lightweight aggregate concrete (HSLAC) were studied. The experimental results show that the main shrinkage of high strength concrete is AS and the amount of cement can affect the AS of HSLAC remarkably. At the early stage the AS of HSLAC is lower than that of high strength normal concrete, but it has a large growth at the later stage. The AS of high strength normal concrete becomes stable at 90d age, but HSLAC still has a high AS growth. It is found that adjusting the volume rate of lightweight aggregate, mixing with a proper dosage of fly ash and raising the water saturation degree of lightweight aggregate can markedly reduce the AS rate of HSLAC.

  8. Fatigue strength of truss girders made of very high strength steel

    NARCIS (Netherlands)

    Pijpers, R.J.M.; Kolstein, M.H.

    2010-01-01

    An effective application of Very High Strength Steel (VHSS) in civil engineering structures is expected in stiff, truss like structures, typically made of Circular Hollow Sections (CHS). Use of castings in combination with CHS could be promising for the design of highly fatigue resistant joints. Cas

  9. Survey of Processing Methods for High Strength High Conductivity Wires for High Field Magnet Applications

    Energy Technology Data Exchange (ETDEWEB)

    Han, K.; Embury, J.D.

    1998-10-01

    This paper will deal with the basic concepts of attaining combination of high strength and high conductivity in pure materials, in-situ composites and macrocomposites. It will survey current attainments, and outline where some future developments may lie in developing wire products that are close to the theoretical strength of future magnet applications.

  10. Behaviour of high strength steel moment joints

    NARCIS (Netherlands)

    Girão Coelho, A.M.; Bijlaard, F.S.K.

    2010-01-01

    The design of joints to European standard EN 1993 within the semi-continuous/partially restrained philosophy is restricted to steel grades up to S460. With the recent development of high performance steels, the need for these restrictions should be revisited. The semicontinuous joint modelling can b

  11. High-strength braze joints between copper and steel

    Science.gov (United States)

    Kuhn, R. F.

    1967-01-01

    High-strength braze joints between copper and steel are produced by plating the faying surface of the copper with a layer of gold. This reduces porosity in the braze area and strengthens the resultant joint.

  12. Retention of ductility in high-strength steels

    Science.gov (United States)

    Parker, E. R.; Zackay, V. F.

    1969-01-01

    To produce high strength alloy steel with retention of ductility, include tempering, cooling and subsequent tempering. Five parameters for optimum results are pretempering temperature, amount of strain, strain rate, temperature during strain, and retempering temperature.

  13. A room temperature cured low dielectric hyperbranched epoxy adhesive with high mechanical strength

    Indian Academy of Sciences (India)

    Bibekananda De; Niranjan Karak

    2014-05-01

    A low dielectric constant hyperbranched epoxy thermoset with excellent adhesive and mechanical strength is the demand for advanced electronics and engineering applications. The present investigation provided a room temperature, curable hyperbranched epoxy, obtained by an A2 + B3 polycondensation reaction. The synthesized hyperbranched epoxy was cured by a combined hardener system consisting of a commercial poly(amido-amine) and a first generation aliphatic poly(amido-amine) dendrimer (PAD) prepared by Michael addition reaction of methyl acrylate and aliphatic amines. The thermoset exhibited high mechanical strength, excellent adhesive strength, low dielectric constant, good thermal stability and excellent weather resistance along with very good moisture resistance. The results showed the influence of the amount of PAD on the performance of the thermoset. Thus, the study revealed that the combined poly(amido-amine) cured hyperbranched epoxy has high potential in advanced electrical packaging and microelectronic devices.

  14. Localized bending fatigue behavior of high-strength steel monostrands

    DEFF Research Database (Denmark)

    Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.

    2012-01-01

    In this paper, the localized bending fatigue behavior of pretensioned high strength steel monostrands is investigated. Furthermore, a new methodology using an optical photogrammetry system, which can quantify surface deformations on the strand is presented. The system allows measurement of the st......In this paper, the localized bending fatigue behavior of pretensioned high strength steel monostrands is investigated. Furthermore, a new methodology using an optical photogrammetry system, which can quantify surface deformations on the strand is presented. The system allows measurement...

  15. Titanium cholla : lightweight, high-strength structures for aerospace applications.

    Energy Technology Data Exchange (ETDEWEB)

    Atwood, Clinton J.; Voth, Thomas Eugene; Taggart, David G. (University of Rhode Island, Kingston, RI); Gill, David Dennis; Robbins, Joshua H.; Dewhurst, Peter (University of Rhode Island, Kingston, RI)

    2007-10-01

    Aerospace designers seek lightweight, high-strength structures to lower launch weight while creating structures that are capable of withstanding launch loadings. Most 'light-weighting' is done through an expensive, time-consuming, iterative method requiring experience and a repeated design/test/redesign sequence until an adequate solution is obtained. Little successful work has been done in the application of generalized 3D optimization due to the difficulty of analytical solutions, the large computational requirements of computerized solutions, and the inability to manufacture many optimized structures with conventional machining processes. The Titanium Cholla LDRD team set out to create generalized 3D optimization routines, a set of analytically optimized 3D structures for testing the solutions, and a method of manufacturing these complex optimized structures. The team developed two new computer optimization solutions: Advanced Topological Optimization (ATO) and FlexFEM, an optimization package utilizing the eXtended Finite Element Method (XFEM) software for stress analysis. The team also developed several new analytically defined classes of optimized structures. Finally, the team developed a 3D capability for the Laser Engineered Net Shaping{trademark} (LENS{reg_sign}) additive manufacturing process including process planning for 3D optimized structures. This report gives individual examples as well as one generalized example showing the optimized solutions and an optimized metal part.

  16. TRIAXIAL COMPRESSIVE STRENGTH OF ULTRA HIGH PERFORMANCE CONCRETE

    Directory of Open Access Journals (Sweden)

    Radoslav Sovják

    2013-12-01

    Full Text Available The aim of this work is to describe the strength of Ultra High Performance Concrete (UHPC under triaxial compression. The main goal is to find a trend in the triaxial compressive strength development under various values of confinement pressure. The importance of triaxial tests lies in the spatial loading of the sample, which simulates the real loading of the material in the structure better than conventional uniaxial strength tests. In addition, the authors describe a formulation process for UHPC that has been developed without using heat treatment, pressure or a special mixer. Only ordinary materials available commercially in the Czech Republic were utilized throughout the material design process.

  17. Microchip electrophoresis at elevated temperatures and high separation field strengths.

    Science.gov (United States)

    Mitra, Indranil; Marczak, Steven P; Jacobson, Stephen C

    2014-02-01

    We report free-solution microchip electrophoresis performed at elevated temperatures and high separation field strengths. We used microfluidic devices with 11 cm long separation channels to conduct separations at temperatures between 22 (ambient) and 45°C and field strengths from 100 to 1000 V/cm. To evaluate separation performance, N-glycans were used as a model system and labeled with 8-aminopyrene-1,3,6-trisulfonic acid to impart charge for electrophoresis and render them fluorescent. Typically, increased diffusivity at higher temperatures leads to increased axial dispersion and poor separation performance; however, we demonstrate that sufficiently high separation field strengths offset the impact of increased diffusivity in order to maintain separation efficiency. Efficiencies for these free-solution separations are the same at temperatures of 25, 35, and 45°C with separation field strengths ≥ 500 V/cm.

  18. Spontaneous Radiation Emission from Short, High Field Strength Insertion Devices

    Energy Technology Data Exchange (ETDEWEB)

    Geoffrey Krafft

    2005-09-15

    Since the earliest papers on undulaters were published, it has been known how to calculate the spontaneous emission spectrum from ''short'' undulaters when the magnetic field strength parameter is small compared to unity, or in ''single'' frequency sinusoidal undulaters where the magnetic field strength parameter is comparable to or larger than unity, but where the magnetic field amplitude is constant throughout the undulater. Fewer general results have been obtained in the case where the insertion device is both short, i.e., the magnetic field strength parameter changes appreciably throughout the insertion device, and the magnetic field strength is high enough that ponderomotive effects, radiation retardation, and harmonic generation are important physical phenomena. In this paper a general method is presented for calculating the radiation spectrum for short, high-field insertion devices. It is used to calculate the emission from some insertion device designs of recent interest.

  19. Effect of Curing Temperature Histories on the Compressive Strength Development of High-Strength Concrete

    Directory of Open Access Journals (Sweden)

    Keun-Hyeok Yang

    2015-01-01

    Full Text Available This study examined the relative strength-maturity relationship of high-strength concrete (HSC specifically developed for nuclear facility structures while considering the economic efficiency and durability of the concrete. Two types of mixture proportions with water-to-binder ratios of 0.4 and 0.28 were tested under different temperature histories including (1 isothermal curing conditions of 5°C, 20°C, and 40°C and (2 terraced temperature histories of 20°C for an initial age of individual 1, 3, or 7 days and a constant temperature of 5°C for the subsequent ages. On the basis of the test results, the traditional maturity function of an equivalent age was modified to consider the offset maturity and the insignificance of subsequent curing temperature after an age of 3 days on later strength of concrete. To determine the key parameters in the maturity function, the setting behavior, apparent activation energy, and rate constant of the prepared mixtures were also measured. This study reveals that the compressive strength development of HSC cured at the reference temperature for an early age of 3 days is insignificantly affected by the subsequent curing temperature histories. The proposed maturity approach with the modified equivalent age accurately predicts the strength development of HSC.

  20. Fatigue Life of High-Strength Steel Offshore Tubular Joints

    DEFF Research Database (Denmark)

    Petersen, Rasmus Ingomar; Agerskov, Henning; Lopez Martinez, Luis

    1996-01-01

    In the present investigation, the fatigue life of tubular joints in offshore steel structures is studied. Two test series on full-scale tubular joints have been carried through. One series was on joints in conventional offshore structural steel, and the other series was on joints in high-strength...... steel with a yield stress of 820-830 MPa and with high weldability and toughness properties. The test specimens of both series had the same geometry. The present report concentrates on the results obtained in the investigation on the high-strength steel tubular joints.The test specimens were fabricated...... amplitude fatigue test results showed shorter fatigue lives in variable amplitude loading than should be expected from the linear fatigue damage accumulation formula. Furthermore, the fatigue tests on high-strength steel tubular joints showed slightly longer fatigue lives than those obtained...

  1. Development of a New Kind of High Strength Spring Steel

    Institute of Scientific and Technical Information of China (English)

    Dexiang XU; Zhongda YIN; Defu LIU

    2004-01-01

    A new kind of high strength, high toughness and high plasticity spring steel has been developed. The strength, the reduction of area and the elongation of the steel are all higher than those of the steel 60Si2CrVA. The decarburization resistance and the sag resistance are also higher than those of the steel 60Si2CrVA. It has good hardenability, and is suitable for making springs with big cross section. The bogie springs made of this kind of steel have passed 2×106 cycles without broken under the conditions of maximum stress of 906 MPa and the minimum stress of 388 MPa.

  2. Modeling and experimental analysis of magnetostriction in high strength steels

    Directory of Open Access Journals (Sweden)

    Della Torre E.

    2013-01-01

    Full Text Available Previous studies on the magnetostriction in high strength steels have ignored the internal anisotropies due to previous material handling. Cold-rolling an iron alloy will stretch and distort the magnetic domains in the direction of rolling. These altered domain shapes impact the magnetic characteristics of the alloy; adding an additional preferred direction of magnetization to the easy or hard axes within the crystalline structure. This paper presents data taken on rods of a high strength steel that have been machined parallel to the rolling direction; as well as simulated results using a Preisach-type magnetostriction model. The model, whose formulation is based on the DOK magnetization-based model, aims specifically to simulate the Villari reversal phenomenon observed in the magnetostriction measurements of high strength steels and some Terfenol-D alloys.

  3. Optimal welding technology of high strength steel S690QL

    Directory of Open Access Journals (Sweden)

    Dusan Arsic

    2015-02-01

    Full Text Available In this paper is presented the detailed procedure for defining the optimal technology for welding the structures made of the high strength steel S690QL. That steel belongs into a group of steels with exceptional mechanical properties. The most prominent properties are the high tensile strength and impact toughness, at room and at elevated temperatures, as well. However, this steel has a negative characteristic - proneness to appearance of cold cracks.  That impedes welding and makes as an imperative to study different aspects of this steel's properties as well as those of eventual filler metal. Selection and defining of the optimal welding technology of this high strength steel is done for the purpose of preserving the favorable mechanical properties once the welded joint is realized; properties of the welded metal and the melting zone, as well as in the heat affected zone, which is the most critical zone of the welded joint.

  4. Optimum high temperature strength of two-dimensional nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Monclús, M. A.; Molina-Aldareguía, J. M., E-mail: jon.molina@imdea.org [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Zheng, S. J.; Mayeur, J. R.; Beyerlein, I. J.; Mara, N. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Polcar, T. [Czech Technical University in Prague, Technická 2, Prague 6 (Czech Republic); Llorca, J. [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Department of Materials Science, Polytechnic University of Madrid, E. T. S. de Ingenieros de Caminos, 28040 Madrid (Spain)

    2013-11-01

    High-temperature nanoindentation was used to reveal nano-layer size effects on the hardness of two-dimensional metallic nanocomposites. We report the existence of a critical layer thickness at which strength achieves optimal thermal stability. Transmission electron microscopy and theoretical bicrystal calculations show that this optimum arises due to a transition from thermally activated glide within the layers to dislocation transmission across the layers. We demonstrate experimentally that the atomic-scale properties of the interfaces profoundly affect this critical transition. The strong implications are that interfaces can be tuned to achieve an optimum in high temperature strength in layered nanocomposite structures.

  5. Optimum high temperature strength of two-dimensional nanocomposites

    Directory of Open Access Journals (Sweden)

    M. A. Monclús

    2013-11-01

    Full Text Available High-temperature nanoindentation was used to reveal nano-layer size effects on the hardness of two-dimensional metallic nanocomposites. We report the existence of a critical layer thickness at which strength achieves optimal thermal stability. Transmission electron microscopy and theoretical bicrystal calculations show that this optimum arises due to a transition from thermally activated glide within the layers to dislocation transmission across the layers. We demonstrate experimentally that the atomic-scale properties of the interfaces profoundly affect this critical transition. The strong implications are that interfaces can be tuned to achieve an optimum in high temperature strength in layered nanocomposite structures.

  6. High strength beta titanium alloys: New design approach

    Energy Technology Data Exchange (ETDEWEB)

    Okulov, I.V., E-mail: okulovilya@yandex.ru [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); TU Dresden, Institut für Werkstoffwissenschaft, D-01062 Dresden (Germany); Wendrock, H. [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Volegov, A.S. [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Attar, H. [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); School of Engineering, Edith Cowan University, 270 Joondalup Drive, Joondalup, Perth, WA 6027 (Australia); Kühn, U. [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Skrotzki, W. [TU Dresden, Institut für Strukturphysik, D-01062 Dresden (Germany); Eckert, J. [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); TU Dresden, Institut für Werkstoffwissenschaft, D-01062 Dresden (Germany)

    2015-03-25

    A novel approach for development of high strength and ductile beta titanium alloys was proposed and successfully applied. The microstructure of the designed alloys is fully composed of a bcc β-Ti phase exhibiting dendritic morphology. The new Ti{sub 68.8}Nb{sub 13.6}Cr{sub 5.1}Co{sub 6}Al{sub 6.5} (at%) alloy (BETA{sup tough} alloy) exhibits a maximum tensile strength of 1290±50 MPa along with 21±3% of fracture strain. The specific energy absorption value upon mechanical deformation of the BETA{sup tough} alloy exceeds that of Ti-based metallic glass composites and commercial high strength Ti-based alloys. The deformation behavior of the new alloys was correlated with their microstructure by means of in-situ studies of the microstructure evolution upon tensile loading in a scanning electron microscope.

  7. Fatigue life of high strength steel for cold forming

    Directory of Open Access Journals (Sweden)

    R. Ulewicz

    2017-01-01

    Full Text Available The article presents the results of fatigue tests carried out on STRENX-type high-strength cold forming steel. For high-cycle fatigue tests carried out using low cycle loading frequencies of around 30 Hz, a ROTOFLEX machine was used. For ultra high-cycle tests, a KAUP-ZU testing machine was employed, which enables fatigue tests to be performed with symetric specimen loading (R = -1 and at a frequency of f ≈ 20 kHz. The relationships σa = f(N were determined experimentally in the high and ultra high-cycle region for STRENX high-strength steel. To determine the fatigue crack initiation mechanism, the fractographic analysis of fatigue fractures was made.

  8. Average density and porosity of high-strength lightweight concrete

    Directory of Open Access Journals (Sweden)

    A.S. Inozemtcev

    2014-11-01

    Full Text Available The analysis results of high-strength lightweight concrete (HSLWC structure are presented in this paper. The X-ray tomography, optical microscopy and other methods are used for researching of average density and porosity. It has been revealed that mixtures of HSLWC with density 1300…1500 kg/m3 have a homogeneous structure. The developed concrete has a uniform distribution of the hollow filler and a uniform layer of cement-mineral matrix. The highly saturated gas phase which is divided by denser large particles of quartz sand and products of cement hydration in the contact area allow forming a composite material with low average density, big porosity (up to 40% and high strength (compressive strength is more than 40 MPa. Special modifiers increase adhesion, compacts structure in the contact area, decrease water absorption of high-strength lightweight concrete (up to 1 % and ensure its high water resistance (water resistance coefficient is more than 0.95.

  9. The Tensile Behavior of High-Strength Carbon Fibers.

    Science.gov (United States)

    Langston, Tye

    2016-08-01

    Carbon fibers exhibit exceptional properties such as high stiffness and specific strength, making them excellent reinforcements for composite materials. However, it is difficult to directly measure their tensile properties and estimates are often obtained by tensioning fiber bundles or composites. While these macro scale tests are informative for composite design, their results differ from that of direct testing of individual fibers. Furthermore, carbon filament strength also depends on other variables, including the test length, actual fiber diameter, and material flaw distribution. Single fiber tensile testing was performed on high-strength carbon fibers to determine the load and strain at failure. Scanning electron microscopy was also conducted to evaluate the fiber surface morphology and precisely measure each fiber's diameter. Fiber strength was found to depend on the test gage length and in an effort to better understand the overall expected performance of these fibers at various lengths, statistical weak link scaling was performed. In addition, the true Young's modulus was also determined by taking the system compliance into account. It was found that all properties (tensile strength, strain to failure, and Young's modulus) matched very well with the manufacturers' reported values at 20 mm gage lengths, but deviated significantly at other lengths.

  10. HIGH TEMPERATURE MATERIALS AND STRENGTH STUDY IN CHINA

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In the past half century China has developed and formed her own system of high temperature materials for power, automobile and aero-engine industries in the temperature range from 550 ℃ to 1 100 ℃. These high temperature materials include heat-resisting steels, iron-base, nickel-iron-base and nickel-base superalloys. Some achievements in high temperature strength study, new technologies and new alloy development are also discussed.

  11. Strength Development of High-Strength Ductile Concrete Incorporating Metakaolin and PVA Fibers

    Science.gov (United States)

    Nuruddin, Muhammad Fadhil; Shafiq, Nasir

    2014-01-01

    The mechanical properties of high-strength ductile concrete (HSDC) have been investigated using Metakaolin (MK) as the cement replacing material and PVA fibers. Total twenty-seven (27) mixes of concrete have been examined with varying content of MK and PVA fibers. It has been found that the coarser type PVA fibers provide strengths competitive to control or higher than control. Concrete with coarser type PVA fibers has also refined microstructure, but the microstructure has been undergone with the increase in aspect ratio of fibers. The microstructure of concrete with MK has also more refined and packing of material is much better with MK. PVA fibers not only give higher stiffness but also showed the deflection hardening response. Toughness Index of HSDC reflects the improvement in flexural toughness over the plain concrete and the maximum toughness indices have been observed with 10% MK and 2% volume fraction of PVA fibers. PMID:24707202

  12. Strength Development of High-Strength Ductile Concrete Incorporating Metakaolin and PVA Fibers

    Directory of Open Access Journals (Sweden)

    Muhammad Fadhil Nuruddin

    2014-01-01

    Full Text Available The mechanical properties of high-strength ductile concrete (HSDC have been investigated using Metakaolin (MK as the cement replacing material and PVA fibers. Total twenty-seven (27 mixes of concrete have been examined with varying content of MK and PVA fibers. It has been found that the coarser type PVA fibers provide strengths competitive to control or higher than control. Concrete with coarser type PVA fibers has also refined microstructure, but the microstructure has been undergone with the increase in aspect ratio of fibers. The microstructure of concrete with MK has also more refined and packing of material is much better with MK. PVA fibers not only give higher stiffness but also showed the deflection hardening response. Toughness Index of HSDC reflects the improvement in flexural toughness over the plain concrete and the maximum toughness indices have been observed with 10% MK and 2% volume fraction of PVA fibers.

  13. Strength development of high-strength ductile concrete incorporating Metakaolin and PVA fibers.

    Science.gov (United States)

    Nuruddin, Muhammad Fadhil; Khan, Sadaqat Ullah; Shafiq, Nasir; Ayub, Tehmina

    2014-01-01

    The mechanical properties of high-strength ductile concrete (HSDC) have been investigated using Metakaolin (MK) as the cement replacing material and PVA fibers. Total twenty-seven (27) mixes of concrete have been examined with varying content of MK and PVA fibers. It has been found that the coarser type PVA fibers provide strengths competitive to control or higher than control. Concrete with coarser type PVA fibers has also refined microstructure, but the microstructure has been undergone with the increase in aspect ratio of fibers. The microstructure of concrete with MK has also more refined and packing of material is much better with MK. PVA fibers not only give higher stiffness but also showed the deflection hardening response. Toughness Index of HSDC reflects the improvement in flexural toughness over the plain concrete and the maximum toughness indices have been observed with 10% MK and 2% volume fraction of PVA fibers.

  14. Determinants of High Schools' Advanced Course Offerings

    Science.gov (United States)

    Iatarola, Patrice; Conger, Dylan; Long, Mark C.

    2011-01-01

    This article examines the factors that determine a high school's probability of offering Advanced Placement (AP) and International Baccalaureate (IB) courses. The likelihood that a school offers advanced courses, and the number of sections that it offers, is largely driven by having a critical mass of students who enter high school with…

  15. Mobility and trapping of hydrogen in high-strength steel

    OpenAIRE

    2013-01-01

    6 pages; International audience; Electrochemical permeation and thermo-desorption tests are performed to evaluate hydrogen mobility in high strength steel. Experimental parameters are used in a Krom like phenomenological diffusion model. This model is developed to simulate hydrogen diffusion and trapping in processing zones of specimens subjected to fatigue loadings.

  16. Fatigue experiments on connections made of very high strength steels

    NARCIS (Netherlands)

    Pijpers, R.; Kolstein, H.; Bijlaard, F.

    2013-01-01

    An effective application of Very High Strength Steels (VHSS) can be expected in truss-like structures, typically made of hollow sections. Improved design of VHSS truss structures could incorporate the application of cast joints, since an appropriate design of cast joints limits the stress concentrat

  17. High-strength porous carbon and its multifunctional applications

    Science.gov (United States)

    Wojtowicz, Marek A; Rubenstein, Eric P; Serio, Michael A; Cosgrove, Joseph E

    2013-12-31

    High-strength porous carbon and a method of its manufacture are described for multifunctional applications, such as ballistic protection, structural components, ultracapacitor electrodes, gas storage, and radiation shielding. The carbon is produced from a polymer precursor via carbonization, and optionally by surface activation and post-treatment.

  18. High strength hot rolled and aged microalloyed 5%Ni steel

    Directory of Open Access Journals (Sweden)

    A.K. Lis

    2006-08-01

    Full Text Available Purpose: Purpose of this paper was to give information about low temperature strength and impact CharpyVtoughness of low carbon microalloyed 5%Ni bainitic steel after thermomechanical rolling (TMR orthermomechanical controlled processing (TMCP and ageing at different temperatures: 580°C/2 h, 640°C/1hand 680°C/1h.Design/methodology/approach: The tensile strength tests were performed at -196, -60 and 20°C and Charpy Vsamples were broken at -100, -80, -60, -40, -20 and 20°C temperatures. The tensile strength TS, yield strengthYS, elongation A5 and reduction of area RA were established from tensile experiments. After TMCP 16 mm steelplate had YS = 730MPa, TS = 950 MPa, A5 = 22,5% and RA = 61% and impact energy > 50 J at -196°C.Findings: The best combination of mechanical properties; yield strength and Charpy V toughness was achieved forsteel after TMR and ageing 580°C/ 2h; YS = 800MPa, TS = 900 MPa, A5 = 22.5%, at -1000C KVmin.= 110 J.Research limitations/implications: The precise methodology for retained austenite identification and itsamount content determination in the investigated microstructures is still metallographic problem which needsto be resolved.Practical implications: The best combination of yield strength and Charpy V toughness was achieved for steelafter TMR and ageing 580°C/ 2h. At liquid nitrogen temperature ultrahigh strength properties were: YS = 1140MPa, TS = 1280 MPa, A5 = 26%, RA = 55% and KV 122 J at -100°C.Originality/value: The detailed microstructure examination of the steel with optical and mainly scanningtransmission electron microscopy was needed to explain its good properties at very low temperature. TRIP effectwas observed due to the presence of highly alloyed retained austenite in the microstructure. That type of steelmay be used for contemporary military and structural applications working at low temperatures.

  19. REVIEW AND PROSPECT OF HIGH STRENGTH LOW ALLOY TRIP STEEL

    Institute of Scientific and Technical Information of China (English)

    L. Li; P. Wollants; Y.L. He; B.C. De Cooman; X.C. Wei; Z.Y. Xu

    2003-01-01

    Research status of high strength low alloy TRIP (transformation induced plasticity)steels for automobile structural parts is briefly described. Composition and microstructure factors especially the morphology, size and volume fraction of retained austenite,which largely influence the strength and ductility of the steel, are reviewed and discussed one after another. Modelling of the inter-critical annealing and martempering processes as well as the designing of the TRIP steel aided by commercial software are introduced. Some special aspects of the dynamic mechanical properties of TRIP steel are firstly reported.

  20. APPROXIMATE MEANS FOR EVALUATING TENSILE STRENGTH OF HIGH POROSITY MATERIALS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Based on the simplified structure model of high porosity materials, the formulas for approximately evaluating the tensile strength of these materials have been derived from the corresponding deductions taken by means of the relative theories about geometry and mechanics. The results show that, the tensile strength of these materials not only associates with the material sort and production method, but do further have a direct value relationship with the porosity, θ. This value relationship can be specifically expressed by the power of the item (1-θ), and it makes the tensile strength variation display a complicated nonlinear law with the porosity. In addition, the application of those formulas has been investigated with the corresponding experiment on a nickel foam.

  1. High Strength Silicon Carbide Foams and Their Deformation Behavior

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Silicon carbide (SiC) foams with a continuously connected open-cell structure were prepared and characterized for their mechanical performance. The apparent densities of SiC foams were controlled between about 0.4 and 1.3 g/cm3, with corresponding compressive strengths ranging from about 13 to 60 MPa and flexural strengths from about 8 to 30 MPa. Compressive testing of the SiC foams yielded stress-strain curves with only one linear-elastic region, which is different from those reported on ceramic foams in literature. This can possibly be attributed to the existence of filaments with fine, dense and high strength microstructures. The SiC and the filaments respond homogeneously to applied loading.

  2. Ultra-high Burst Strength of CVD Graphene Membranes

    Science.gov (United States)

    Wang, Luda; Boutilier, Michael; Kidambi, Piran; Karnik, Rohit; Microfluidics; Nanofluidics Research Lab Team

    2015-11-01

    Porous graphene membranes have significant potential in gas separation, water desalination and nanofiltration. Understanding the mechanical strength of porous graphene is crucial because membrane separations can involve high pressures. We studied the burst strength of CVD graphene membrane placed on porous support at applied pressures up to 100 bar by monitoring the gas flow rate across the membrane as a function of pressure. Increase of gas flow rate with pressure allowed for extraction of the burst fraction of graphene as it failed under increasing pressure. We also studied the effect of sub-nanometer pores on the ability of graphene to withstand pressure. The results showed that porous graphene membranes can withstand pressures comparable to or even higher than the >50 bar pressures encountered in water desalination, with non-porous CVD graphene exhibiting even higher mechanical strength. Our study shows that porous polycrystalline CVD graphene has ultra-high burst strength under applied pressure, suggesting the possibility for its use in high-pressure membrane separations. Principal Investigator

  3. NEW HIGH STRENGTH AND FASTER DRILLING TSP DIAMOND CUTTERS

    Energy Technology Data Exchange (ETDEWEB)

    Robert Radtke

    2006-01-31

    The manufacture of thermally stable diamond (TSP) cutters for drill bits used in petroleum drilling requires the brazing of two dissimilar materials--TSP diamond and tungsten carbide. The ENDURUS{trademark} thermally stable diamond cutter developed by Technology International, Inc. exhibits (1) high attachment (shear) strength, exceeding 345 MPa (50,000 psi), (2) TSP diamond impact strength increased by 36%, (3) prevents TSP fracture when drilling hard rock, and (4) maintains a sharp edge when drilling hard and abrasive rock. A novel microwave brazing (MWB) method for joining dissimilar materials has been developed. A conventional braze filler metal is combined with microwave heating which minimizes thermal residual stress between materials with dissimilar coefficients of thermal expansion. The process results in preferential heating of the lower thermal expansion diamond material, thus providing the ability to match the thermal expansion of the dissimilar material pair. Methods for brazing with both conventional and exothermic braze filler metals have been developed. Finite element modeling (FEM) assisted in the fabrication of TSP cutters controllable thermal residual stress and high shear attachment strength. Further, a unique cutter design for absorbing shock, the densification of otherwise porous TSP diamond for increased mechanical strength, and diamond ion implantation for increased diamond fracture resistance resulted in successful drill bit tests.

  4. Oxidation resistant high creep strength austenitic stainless steel

    Science.gov (United States)

    Brady, Michael P.; Pint, Bruce A.; Liu, Chain-Tsuan; Maziasz, Philip J.; Yamamoto, Yukinori; Lu, Zhao P.

    2010-06-29

    An austenitic stainless steel displaying high temperature oxidation and creep resistance has a composition that includes in weight percent 15 to 21 Ni, 10 to 15 Cr, 2 to 3.5 Al, 0.1 to 1 Nb, and 0.05 to 0.15 C, and that is free of or has very low levels of N, Ti and V. The alloy forms an external continuous alumina protective scale to provide a high oxidation resistance at temperatures of 700 to 800.degree. C. and forms NbC nanocarbides and a stable essentially single phase fcc austenitic matrix microstructure to give high strength and high creep resistance at these temperatures.

  5. Effect of Boron Addition on Microstructural Evolution and Room-Temperature Mechanical Properties of Novel Fe66- x CrNiB x Si ( x = 0, 0.25, 0.50 and 0.75 Wt Pct) Advanced High-Strength Steels

    Science.gov (United States)

    Askari-Paykani, Mohsen; Shahverdi, Hamid Reza; Miresmaeili, Reza

    2016-11-01

    In this study, the Vickers hardnesses and room-temperature uniaxial tensile behaviors of four Fe66- x CrNiB x Si ( x = 0 (0B), 0.25 (25B), 0.50 (50B), and 0.75 (75B) wt pct) advanced high-strength steels (AHSSs) in the as-hot-rolled and heat-treated (1373 K (1100 °C)/2 h + 973 K (700 °C)/20 min) conditions were investigated. Microstructural evolution after solidification, hot rolling, heat treatment, and uniaxial tensile tests of 0B, 25B, 50B, and 75B AHSSs was also characterized using field emission gun scanning electron microscopy and X-ray diffraction. The tensile behaviors of the 0B, 25B, 50B, and 75B AHSSs were manifested by an excellent combination of strength and ductility over 34.7 and 47.1 GPa pct, 36.9 and 42.3 GPa pct, 45.9 and 46.4 GPa pct, and 11.9 and 47.8 GPa pct, respectively, arising from microband-induced plasticity in the 0B, 50B, and 75B AHSSs and transformation-induced plasticity in the 25B specimens. All specimens in the as-hot-rolled and heat-treated states showed an austenitic matrix grain. Adding boron to the base alloy (0B) resulted in grain refinement, M2B dispersion, precipitation hardening, and solid solution strengthening, which led to an increase in strength. The results of the present work show promise for automotive applications that require excellent properties and reduced specific weight.

  6. Degradation of permeability resistance of high strength concrete after combustion

    Institute of Scientific and Technical Information of China (English)

    Min LI; Hongtao KAO; Chunxiang QIAN

    2008-01-01

    To evaluate the remaining durability of con-crete materials after combustion, the permeability of high strength concrete (HSC) after combustion was studied. The transport behavior of chloride ion, water and air in concrete after combustion and the effect of temperature, strength grade, and aggregation on the permeability of HSC after combustion are investigated by chloride ion permeability coefficient (Dc), water permeability coef-ficient (Dw) and air permeability coefficient (Da). The experiment results show that all three permeability coeffi-cients commendably reflect changes of permeability. The permeability coefficient increases with the evaluation tem-perature. After the same temperature, the permeability coefficient of HSC is lower than that of normal strength concrete (NSC). However, the degree of degradation of permeability coefficient of HSC is greater than that of NSC. The permeability resistance of HSC containing limestone is better than that of HSC containing basalt. Combining changes of compressive strength and per-meability, the remaining durability of concrete materials after combustion is appropriately evaluated.

  7. Grain refinement of high strength steels to improve cryogenic toughness

    Science.gov (United States)

    Rush, H. F.

    1985-01-01

    Grain-refining techniques using multistep heat treatments to reduce the grain size of five commercial high-strength steels were investigated. The goal of this investigation was to improve the low-temperature toughness as measured by Charpy V-notch impact test without a significant loss in tensile strength. The grain size of four of five alloys investigated was successfully reduced up to 1/10 of original size or smaller with increases in Charpy impact energy of 50 to 180 percent at -320 F. Tensile properties were reduced from 0 to 25 percent for the various alloys tested. An unexpected but highly beneficial side effect from grain refining was improved machinability.

  8. Seismic Performance of High Strength Steel Building Frames

    OpenAIRE

    2014-01-01

    Tese de doutoramento em Engenharia Civil, no ramo de Construção Metálica e Mista, apresentada ao Departamento de Engenharia Civil da Faculdade de Ciências e Tecnologia da Universidade de Coimbra In steel building frames under seismic action, the members designed to remain elastic during an earthquake are responsible for the robustness of the structure and prevention of collapse, being characterised by high strength demands. On the other hand, seismic resistant building frames designed as ...

  9. High Performance Grinding and Advanced Cutting Tools

    CERN Document Server

    Jackson, Mark J

    2013-01-01

    High Performance Grinding and Advanced Cutting Tools discusses the fundamentals and advances in high performance grinding processes, and provides a complete overview of newly-developing areas in the field. Topics covered are grinding tool formulation and structure, grinding wheel design and conditioning and applications using high performance grinding wheels. Also included are heat treatment strategies for grinding tools, using grinding tools for high speed applications, laser-based and diamond dressing techniques, high-efficiency deep grinding, VIPER grinding, and new grinding wheels.

  10. High Strength Discontinuously Reinforced Aluminum For Rocket Applications

    Science.gov (United States)

    Pandey, A. B.; Shah, S. R.; Shadoan, M.

    2003-01-01

    This study presents results on the development of a new aluminum alloy with very high strength and ductility. Five compositions of Al-Mg-Sc-Gd-Zr alloy were selected for this purpose. These alloys were also reinforced with 15 volume percent silicon-carbide and boron-carbide particles to produce Discontinuously Reinforced Aluminum (DRA) materials. Matrix alloys and DRA were processed using a powder metallurgy process. The helium gas atomization produced very fine powder with cellular-dentritic microstructure. The microstructure of matrix alloys showed fine Al3Sc based precipitate which provides significant strengthening in these alloys. DRA showed uniform distribution of reinforcement in aluminum matrix. DRA materials were tested at -320 F, 75 F in air and 7S F in gaseous hydrogen environments and matrix alloys were tested at 75 F in air. DRA showed high strengths in the range of 89-111 ksi (614-697 MPa) depending on alloy compositions and test environments. Matrix alloys had a good combination of strength, 84-89 ksi (579-621 MPa) and ductility, 4.5-6.5%. The properties of these materials can further be improved by proper control of processing parameters.

  11. Metastable high-entropy dual-phase alloys overcome the strength-ductility trade-off

    Science.gov (United States)

    Li, Zhiming; Pradeep, Konda Gokuldoss; Deng, Yun; Raabe, Dierk; Tasan, Cemal Cem

    2016-06-01

    Metals have been mankind’s most essential materials for thousands of years; however, their use is affected by ecological and economical concerns. Alloys with higher strength and ductility could alleviate some of these concerns by reducing weight and improving energy efficiency. However, most metallurgical mechanisms for increasing strength lead to ductility loss, an effect referred to as the strength-ductility trade-off. Here we present a metastability-engineering strategy in which we design nanostructured, bulk high-entropy alloys with multiple compositionally equivalent high-entropy phases. High-entropy alloys were originally proposed to benefit from phase stabilization through entropy maximization. Yet here, motivated by recent work that relaxes the strict restrictions on high-entropy alloy compositions by demonstrating the weakness of this connection, the concept is overturned. We decrease phase stability to achieve two key benefits: interface hardening due to a dual-phase microstructure (resulting from reduced thermal stability of the high-temperature phase); and transformation-induced hardening (resulting from the reduced mechanical stability of the room-temperature phase). This combines the best of two worlds: extensive hardening due to the decreased phase stability known from advanced steels and massive solid-solution strengthening of high-entropy alloys. In our transformation-induced plasticity-assisted, dual-phase high-entropy alloy (TRIP-DP-HEA), these two contributions lead respectively to enhanced trans-grain and inter-grain slip resistance, and hence, increased strength. Moreover, the increased strain hardening capacity that is enabled by dislocation hardening of the stable phase and transformation-induced hardening of the metastable phase produces increased ductility. This combined increase in strength and ductility distinguishes the TRIP-DP-HEA alloy from other recently developed structural materials. This metastability-engineering strategy should

  12. Freezing and Thawing Durability of Very High Strength Concrete

    Directory of Open Access Journals (Sweden)

    Sameer Hamoush

    2011-01-01

    Full Text Available Problem statement: The newly developed Very High Strength Concrete (VHSC, having compressive strengths of 29 ksi and flexural strengths of 6 ksi, represents a breakthrough in concrete technology. Study to further enhance the properties of this new concrete is continuing. Approach: The objective of this study is to investigate the effect of exposing Very High Strength Concrete (VHSC specimens to rapid freeze/thaw cycles. Twenty one specimens were tested according to the Standards of the American Society for Testing and Materials ASTM C215, ASTM C666 and ASTM C78. Results: One hundred freeze/thaw cycles were performed on the VHSC specimens. Change in specimen’s dimensions and material’s properties were recorded at zero, forty, seventy and one hundred cycles. Dimensions and properties considered were: dimension of cross section, length, weight, Dynamic Moduli, Poisson’s Ratio, durability factor and Modulus of Rupture. Conclusion/Recommendations: The test results indicated that VHSC is good freeze-thaw resistance (durability factor > 85% and can avoid freeze/thaw damage. Freeze- thaw cycling did not significantly affect VHSC specimens’ cross sectional dimensions, length, or Poisson’s Ratio. However, there was a decrease in the specimens’ weight with the increase in number of freeze/thaw cycles, but the decrease was very slim indicating little or no deterioration has occur. Moreover, the fine voids exist in VHSC greatly lower the freezing point of any trapped water, making the material less susceptible to Freeze- Thaw damage.

  13. Advances in high voltage engineering

    CERN Document Server

    Haddad, A

    2005-01-01

    This book addresses the very latest research and development issues in high voltage technology and is intended as a reference source for researchers and students in the field, specifically covering developments throughout the past decade. This unique blend of expert authors and comprehensive subject coverage means that this book is ideally suited as a reference source for engineers and academics in the field for years to come.

  14. Impact strength and abrasion resistance of high strength concrete with rice husk ash and rubber tires

    Directory of Open Access Journals (Sweden)

    M. B. Barbosa

    Full Text Available The paper discusses the application of High Strength Concrete (HSC technology for concrete production with the incorporation of Rice Husk Ash (RHA residues by replacing a bulk of the material caking and rubber tires with partial aggregate volume, assessing their influence on the mechanical properties and durability. For concrete with RHA and rubber, it was possible to reduce the brittleness by increasing the energy absorbing capacity. With respect to abrasion, the RHA and rubber concretes showed lower mass loss than the concrete without residues, indicating that this material is attractive to be used in paving. It is thus hoped that these residues may represent a technological and ecological alternative for the production of concrete in construction works.

  15. Advances in high temperature chemistry 1

    CERN Document Server

    Eyring, Leroy

    2013-01-01

    Advances in High Temperature Chemistry, Volume 1 describes the complexities and special and changing characteristics of high temperature chemistry. After providing a brief definition of high temperature chemistry, this nine-chapter book goes on describing the experiments and calculations of diatomic transition metal molecules, as well as the advances in applied wave mechanics that may contribute to an understanding of the bonding, structure, and spectra of the molecules of high temperature interest. The next chapter provides a summary of gaseous ternary compounds of the alkali metals used in

  16. Boron effects on creep rupture strength of W containing advanced ferritic creep resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Mito, N.; Hasegawa, Y. [Tohoku Univ., Sendai (Japan)

    2010-07-01

    The creep strength in ferritic creep resistant steels is increased by boron addition. However, the strengthening mechanisms have not yet been studied. This study clarifies the strengthening mechanism of 9% chromium steels with 10{proportional_to}100ppm boron and 0.5{proportional_to}2.0mass% tungsten in the laboratory. The strengthening effect of simultaneous addition of boron and tungsten was analyzed by hardenability, room-temperature strength and creep tests at 650 C. Changes in the microstructure as a result of the addition of boron and tungsten were also examined by optical microscope and transmission electron microscope (TEM). In addition, Alpha-ray Track Etching (ATE) method was used to detect the boron distribution and analyze the mechanisms change in the mechanical properties. Boron addition did not affect room-temperature strength, however, simultaneous addition of boron and tungsten increased room-temperature and high-temperature strength. According to ATE analysis, boron exists at the grain boundary. Therefore, synergistic effects of boron and tungsten on the creep strength suggest the tungsten precipitates stabilization by boron at the grain boundary. (orig.)

  17. Microstructure control for high strength 9Cr ferritic-martensitic steels

    Science.gov (United States)

    Tan, L.; Hoelzer, D. T.; Busby, J. T.; Sokolov, M. A.; Klueh, R. L.

    2012-03-01

    Ferritic-martensitic (F-M) steels with 9 wt.%Cr are important structural materials for use in advanced nuclear reactors. Alloying composition adjustment, guided by computational thermodynamics, and thermomechanical treatment (TMT) were employed to develop high strength 9Cr F-M steels. Samples of four heats with controlled compositions were subjected to normalization and tempering (N&T) and TMT, respectively. Their mechanical properties were assessed by Vickers hardness and tensile testing. Ta-alloying showed significant strengthening effect. The TMT samples showed strength superior to the N&T samples with similar ductility. All the samples showed greater strength than NF616, which was either comparable to or greater than the literature data of the PM2000 oxide-dispersion-strengthened (ODS) steel at temperatures up to 650 °C without noticeable reduction in ductility. A variety of microstructural analyses together with computational thermodynamics provided rational interpretations on the strength enhancement. Creep tests are being initiated because the increased yield strength of the TMT samples is not able to deduce their long-term creep behavior.

  18. Scratch-resistant, highly conductive, and high-strength carbon nanotube-based composite yarns.

    Science.gov (United States)

    Liu, Kai; Sun, Yinghui; Lin, Xiaoyang; Zhou, Ruifeng; Wang, Jiaping; Fan, Shoushan; Jiang, Kaili

    2010-10-26

    High-strength and conductive carbon nanotube (CNT) yarns are very attractive in many potential applications. However, there is a difficulty when simultaneously enhancing the strength and conductivity of CNT yarns. Adding some polymers into CNT yarns to enhance their strength will decrease their conductivity, while treating them in acid or coating them with metal nanoparticles to enhance their conductivity will reduce their strength. To overcome this difficulty, here we report a method to make high-strength and highly conductive CNT-based composite yarns by using a continuous superaligned CNT (SACNT) yarn as a conductive framework and then inserting polyvinyl alcohol (PVA) into the intertube spaces of the framework through PVA/dimethyl sulphoxide solution to enhance the strength of yarns. The as-produced CNT/PVA composite yarns possess very high tensile strengths up to 2.0 GPa and Young's moduli more than 120 GPa, much higher than those of the CNT/PVA yarns reported. The electric conductivity of as-produced composite yarns is as high as 9.2 × 10(4) S/m, comparable to HNO(3)-treated or Au nanoparticle-coated CNT yarns. These composite yarns are flexible, lightweight, scratch-resistant, very stable in the lab environment, and resistant to extremely humid ambient and as a result can be woven into high-strength and heatable fabrics, showing potential applications in flexible heaters, bullet-proof vests, radiation protection suits, and spacesuits.

  19. Design aspects of high strength steel welded structures improved by high frequency mechanical impact (HFMI) treatment

    OpenAIRE

    Yildirim, Halid Can

    2013-01-01

    This doctoral study is concerned with the fatigue strength of welded steel structures which are improved by high frequency mechanical impact (HFMI) treatment. A comprehensive evaluation of 417 HFMI test data obtained from the literature and 24 HFMI fatigue data tested as a part of this work are studied. According to the statistical analyses an S-N slope of five (5) is proposed. A yield strength correction procedure which relates the material yield strength (fy) to fatigue is presented and ver...

  20. Production of high melt strength polypropylene by gamma irradiation

    Science.gov (United States)

    Lugão, A. B.; Artel, B. W. H.; Yoshiga, A.; Lima, L. F. C. P.; Parra, D. F.; Bueno, J. R.; Liberman, S.; Farrah, M.; Terçariol, W. R.; Otaguro, H.

    2007-11-01

    High melt strength polypropylene (HMS-PP) has been recently developed and introduced in the market by the major international producers of polypropylene. Therefore, BRASKEM, the leading Brazilian PP producer, together with EMBRARAD, the leading Brazilian gamma irradiator, and the IPEN (Institute of Nuclear Energy and Research) worked to develop a national technology for the production of HMS-PP. One of the effective approaches to improve melt strength and extensibility is to add chain branches onto polypropylene backbone using gamma radiation. Branching and grafting result from the radical combinations during irradiation process. Crosslinking and main chain scission in the polymer structure are also obtained during this process. In this work, gamma irradiation technique was used to induce chemical changes in commercial polypropylene with two different monomers, Tri-allyl-isocyanurate (TAIC) and Tri-methylolpropane-trimethacrylate (TMPTMA), with concentration ranging from 1.5 to 5.0 mmol/100 g of polypropylene. These samples were irradiated with a 60Co source at dose of 20 kGy. It used two different methods of HMS-PP processing. The crosslinking of modified polymers was studied by measuring gel content melt flow rate and rheological properties like melt strength and drawability. It was observed that the reaction method and the monomer type have influenced the properties. However, the concentration variation of monomer has no effect.

  1. Overheating temperature of 7B04 high strength aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    GAO Feng-hua; LI Nian-kui; TIAN Ni; SUN Qiang; LIU Xian-dong; ZHAO Gang

    2008-01-01

    The microstructure and overheating characteristics of the direct chill semicontinuous casting ingot of 7B04 high strength aluminum alloy, and those after industrial homogenization treatment and multi-stage homogenization treatments, were studied by differential scanning calorimetry(DSC), optical microscopy(OM) and scanning electron microscopy with energy dispersive X-ray spectroscopy(SEM-EDX). The results show that the microstructure of direct chill semicontinuous casting ingot of the 7B04 alloy contains a large number of constituents in the form of dendritic networks that consist of nonequilibrium eutectic and Fe-containing phases. The nonequilibrium eutectic contains Al, Zn, Mg and Cu, and the Fe-containing phases include two kinds of phases, one containing Al, Fe, Mn and Cu, and the other having Al, Fe, Mn, Cr, Si and Cu. The melting point of the nonequilibrium eutectic is 478 ℃ for the casting ingot of the 7B04 alloy which is usually considered as its overheating temperature. During industrial homogenization treatment processing at 470 ℃, the nonequilibrium eutectic dissolves into the matrix of this alloy partly, and the remainder transforms into Al2CuMg phase that cannot be dissolved into the matrix at that temperature completely. The melting point of the Al2CuMg phase which can dissolve into the matrix completely by slow heating is about 490 ℃. The overheating temperature of this high strength aluminum alloy can rise to 500-520 ℃. By means of special multi-stage homogenization, the temperature of the homogenization treatment of the ingot of the 7B04 high strength aluminum alloy can reach 500 ℃ without overheating.

  2. Method for providing a low density high strength polyurethane foam

    Science.gov (United States)

    Whinnery, Jr., Leroy L.; Goods, Steven H.; Skala, Dawn M.; Henderson, Craig C.; Keifer, Patrick N.

    2013-06-18

    Disclosed is a method for making a polyurethane closed-cell foam material exhibiting a bulk density below 4 lbs/ft.sup.3 and high strength. The present embodiment uses the reaction product of a modified MDI and a sucrose/glycerine based polyether polyol resin wherein a small measured quantity of the polyol resin is "pre-reacted" with a larger quantity of the isocyanate in a defined ratio such that when the necessary remaining quantity of the polyol resin is added to the "pre-reacted" resin together with a tertiary amine catalyst and water as a blowing agent, the polymerization proceeds slowly enough to provide a stable foam body.

  3. Performances of the High Strength Low Heat Pump Concrete (HLPC)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The effects of mineral admixtures on fluidity,mechanical and hydrational exothermic behavior were studied.The results show that,double-adding ways,i e,fly ash and slag were added at the same time,not only improves the fluidity of fresh concrete with low W/B and compensates the lower early compressive strength of harden concrete caused by high adding amount of fly ash, but also greatly reduces the highest temperature rise, exothermic rate and total heat liberation of 3 day of binder pastes in HLPC, and postponed the arrival time of the highest temperature rise. HLPC was prepared and applied to project practice successfully.

  4. High Pressure Strength Study on NaCl

    Science.gov (United States)

    Mi, Z.; Shieh, S. R.; High Pressure Mineral Physics Group

    2010-12-01

    Yield strength is regarded as one important property related to rheological characteristics of minerals in the Earth’s interior. The strength study of NaCl, a popular pressure medium in static high pressure experiments, has been carried out under non-hydrostatic conditions in a diamond anvil cell up to 43 GPa at room temperature using radial energy dispersive X-ray diffraction technique. Phase transformation from B1 (rock salt structure) to B2 (CsCl structure) starts at 29.4 GPa, and is complete at 32.1 GPa. Bulk modulus obtained by third order Birch-Manurgham equation of state is 25.5 GPa with pressure derivative 4.6 for B1 phase, and 30.78 GPa with pressure derivative 4.32 GPa for B2 phase, which are in a good agreement with previous studies. The differential stress of NaCl B1 phase shows very gentle increase with pressure, which indicates that NaCl is a very good pressure-transmitting medium at pressure below 30 GPa. However, the differential stress increases more abruptly for B2 phase and this may imply that NaCl can no longer be regarded as a “soft” pressure medium at very high pressures. For B1 phase, (111) is the strongest plane and (200) is the weakest plane, while (200) becomes the strongest plane in B2 phase. Pure NaCl is weaker than mixture MgO and NaCl, which indicates that soft material become stronger when mixed with hard material. The yield strength of B2 obtained through energy dispersive X-ray diffraction technique increase linearly, while the value derived by pressure gradient method shows jagged trend.

  5. High-Strength and High-Plasticity TWIP Steel for Modern Vehicle

    Institute of Scientific and Technical Information of China (English)

    Zhenli MI; Di TANG; Ling YAN; Jin GUO

    2005-01-01

    In this paper new high-strength and high-plasticity twinning induced plasticity (TWIP) steel for modern automobile body was investigated. Some basic experimental results were given. The results indicate the TWlP steel has excellent properties. It exhibits high ultimate tensile strength (600~1100 MPa) and extremely large elongation of 60% to 90%. In the future it would be capable of satisfying the requirements of new generation of vehicle.

  6. Experimental investigation of bond strength under high loading rates

    Directory of Open Access Journals (Sweden)

    Michal Mathias

    2015-01-01

    Full Text Available The structural behaviour of reinforced concrete is governed significantly by the transmission of forces between steel and concrete. The bond is of special importance for the overlapping joint and anchoring of the reinforcement, where rigid bond is required. It also plays an important role in the rotational capacity of plastic hinges, where a ductile bond behaviour is preferable. Similar to the mechanical properties of concrete and steel also the characteristics of their interaction changes with the velocity of the applied loading. For smooth steel bars with its main bond mechanisms of adhesion and friction, nearly no influence of loading rate is reported in literature. In contrast, a high rate dependence can be found for the nowadays mainly used deformed bars. For mechanical interlock, where ribs of the reinforcing steel are bracing concrete material surrounding the bar, one reason can be assumed to be in direct connection with the increase of concrete compressive strength. For splitting failure of bond, characterized by the concrete tensile strength, an even higher dynamic increase is observed. For the design of Structures exposed to blast or impact loading the knowledge of a rate dependent bond stress-slip relationship is required to consider safety and economical aspects at the same time. The bond behaviour of reinforced concrete has been investigated with different experimental methods at the University of the Bundeswehr Munich (UniBw and the Joint Research Centre (JRC in Ispra. Both static and dynamic tests have been carried out, where innovative experimental apparatuses have been used. The bond stress-slip relationship and maximum pull-out-forces for varying diameter of the bar, concrete compressive strength and loading rates have been obtained. It is expected that these experimental results will contribute to a better understanding of the rate dependent bond behaviour and will serve for calibration of numerical models.

  7. Experimental investigation of bond strength under high loading rates

    Science.gov (United States)

    Michal, Mathias; Keuser, Manfred; Solomos, George; Peroni, Marco; Larcher, Martin; Esteban, Beatriz

    2015-09-01

    The structural behaviour of reinforced concrete is governed significantly by the transmission of forces between steel and concrete. The bond is of special importance for the overlapping joint and anchoring of the reinforcement, where rigid bond is required. It also plays an important role in the rotational capacity of plastic hinges, where a ductile bond behaviour is preferable. Similar to the mechanical properties of concrete and steel also the characteristics of their interaction changes with the velocity of the applied loading. For smooth steel bars with its main bond mechanisms of adhesion and friction, nearly no influence of loading rate is reported in literature. In contrast, a high rate dependence can be found for the nowadays mainly used deformed bars. For mechanical interlock, where ribs of the reinforcing steel are bracing concrete material surrounding the bar, one reason can be assumed to be in direct connection with the increase of concrete compressive strength. For splitting failure of bond, characterized by the concrete tensile strength, an even higher dynamic increase is observed. For the design of Structures exposed to blast or impact loading the knowledge of a rate dependent bond stress-slip relationship is required to consider safety and economical aspects at the same time. The bond behaviour of reinforced concrete has been investigated with different experimental methods at the University of the Bundeswehr Munich (UniBw) and the Joint Research Centre (JRC) in Ispra. Both static and dynamic tests have been carried out, where innovative experimental apparatuses have been used. The bond stress-slip relationship and maximum pull-out-forces for varying diameter of the bar, concrete compressive strength and loading rates have been obtained. It is expected that these experimental results will contribute to a better understanding of the rate dependent bond behaviour and will serve for calibration of numerical models.

  8. High Temperature Strength of Oxide Dispersion Strengthened Aluminium

    DEFF Research Database (Denmark)

    Clauer, A.H.; Hansen, Niels

    1984-01-01

    is proportional to the Orowan stress and it does not fall below about 0.5-0.7 of the Orowan stress. During creep even at stresses near the threshold stress a dislocation substructure develops consisting of dense tangles surrounding the larger particles and the particle clusters in addition to a coarse dislocation......The tensile flow stress of coarse-grained dispersion strengthened Al-Al2O3 materials were measured as a function of temperature (77–873 K) and volume fraction (0.19-0.92 vol.%) of aluminium oxide. For the same material, the creep strength was determined as a function of temperature in the range 573...... constant (except for the material with the lowest oxide content). The high temperature values of the modulus-corrected yield stresses are approximately two-thirds of the low temperature value. During high temperature creep, there is a definite indication of a threshold stress. This threshold stress...

  9. Research on Stress and Strength of High Strength Reinforced Concrete Drilling Shaft Lining in Thick Top Soils

    Institute of Scientific and Technical Information of China (English)

    YAO Zhi-shu; CHANG Hua; RONG Chuan-xin

    2007-01-01

    High strength reinforced concrete drilling shaft linings have been adopted to solve the difficult problem of supporting coal drilling shafts penetrating through thick top soils. Through model experiments the stress and strength of such shaft linings are studied. The test results indicate that the load bearing capacity of the shaft lining is very high and that the main factors affecting the load bearing capacity are the concrete strength, the ratio of lining thickness to inner radius and the reinforcement ratio. Based on the limit equilibrium conditions and the strength theory of concrete under multi-axial compressive stressed state, a formula for calculating the load-bearing capacity of a high strength reinforced concrete shaft lining was obtained. Because the concrete in a shaft lining is in a multi-axial compressive stress state the compressive strength increases to a great extent compared to uni-axial loading. Based on experiment a formula for the gain factor in compressive strength was obtained: it can be used in the structural design of the shaft lining. These results have provided a basis for sound engineering practice when designing this kind of shaft lining structure.

  10. Cryogenic ultrahigh strain rate deformation induced hybrid nanotwinned microstructure for high strength and high ductility

    Science.gov (United States)

    Ye, Chang; Suslov, Sergey; Lin, Dong; Liao, Yiliang; Cheng, Gary J.

    2014-06-01

    Nanocrystalline metallic materials prepared by severe plastic deformation often possess high strength but low ductility due to the low dislocation accumulation capacity of the nanograins. Here, we report a unique process, namely, cryogenic laser shock peening (CLSP), to generate gradient nanotwinned microstructure that leads to high strength while preserving the ductility. It was observed that gradient structure was generated in copper. Near the top surface, nanocrystalline with high dense nanotwins have been observed; with the depth increasing, the fraction of the twin boundaries reduces and more heavily dislocated subgrains are observed. It has been demonstrated that CLSP can significantly improve material strength while preserving the ductility. The mechanism of the formation of gradient microstructure and high dense nanotwins near the surface was discussed. The reason behind the improvement in strength and ductility was investigated.

  11. Thermal Stir Welding of High Strength and High Temperature Alloys for Aerospace Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Keystone and MSU team propose to demonstrate the feasibility of solid-state joining high strength and temperature alloys utilizing the Thermal Stir Welding...

  12. Accelerated Creep Testing of High Strength Aramid Webbing

    Science.gov (United States)

    Jones, Thomas C.; Doggett, William R.; Stnfield, Clarence E.; Valverde, Omar

    2012-01-01

    A series of preliminary accelerated creep tests were performed on four variants of 12K and 24K lbf rated Vectran webbing to help develop an accelerated creep test methodology and analysis capability for high strength aramid webbings. The variants included pristine, aged, folded and stitched samples. This class of webbings is used in the restraint layer of habitable, inflatable space structures, for which the lifetime properties are currently not well characterized. The Stepped Isothermal Method was used to accelerate the creep life of the webbings and a novel stereo photogrammetry system was used to measure the full-field strains. A custom MATLAB code is described, and used to reduce the strain data to produce master creep curves for the test samples. Initial results show good correlation between replicates; however, it is clear that a larger number of samples are needed to build confidence in the consistency of the results. It is noted that local fiber breaks affect the creep response in a similar manner to increasing the load, thus raising the creep rate and reducing the time to creep failure. The stitched webbings produced the highest variance between replicates, due to the combination of higher local stresses and thread-on-fiber damage. Large variability in the strength of the webbings is also shown to have an impact on the range of predicted creep life.

  13. Hydrogen influence on the mechanical behaviour of high strength steel

    Energy Technology Data Exchange (ETDEWEB)

    Herenu, Silvina [National Technology Univ. of San Nicolas (Argentina).; National Council of Scientific Research and Technology (Argentina); Armas, Alberto [National Univ. of Rosario (Argentina); Brandaleze, Elena [National Technology Univ. of San Nicolas (Argentina). Metallurgical Dept.; Mansilla, Graciela [National Technology Univ. of San Nicolas (Argentina).

    2010-07-01

    Though numerous studies have been devoted to hydrogen embrittlement in steels, up to date there is not a general agreement about the effect of hydrogen on the mechanical behaviour. The purpose of this paper is to analyze the influence of hydrogen on the mechanical response of high strength steels. Samples were cathodically charged with hydrogen, previous to low cyclic fatigue and tensile tests at room temperature. The presence of hydrogen produces softening effects on the cyclic behaviour and improvements in the fatigue life for low hydrogen contents. The stress-strain curves of tensile tests on pre-charged samples depend on the strain rate imposed. Both tensile and fatigue response could be explained by the hydrogen enhancement of dislocation mobility mechanism. (orig.)

  14. Method of making high strength, tough alloy steel

    Science.gov (United States)

    Thomas, Gareth; Rao, Bangaru V. N.

    1979-01-01

    A high strength, tough alloy steel, particularly suitable for the mining industry, is formed by heating the steel to a temperature in the austenite range (1000.degree.-1100.degree. C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other subsitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300.degree. C.) and reforms to a stable film after austenite grain refinement.

  15. Fatigue behaviour of high strength AA 7012 aluminium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Di Russo, E.; Ragazzini, R.; Buratti, M.; Ferrarin, C. (Aluminia-ISML, Novara (Italy) Caproni Vizzola costruzioni aeronautiche, Somma Lombarda (Italy))

    1990-02-01

    The alloy 7012 (Al, 6.2% Zn, 2% Mg, 1% Cn, 0.13% Mn, 0.14% Zn, 0.04% Ti) belongs to the 7XXX family of high mechanical resistance alloys containing Zr as the principal additive. Produced in the form of extrusions, sheets and forgings, the alloy finds application in the defense, transportation and power industry fields. This paper presents the results of experimental fatigue tests (10/sup 7/ cycles) on 7020 in the T6 and T73 temper conditions and draws comparisons with corresponding test results on 7075 and 2024 type alloys. A comparative analysis of S-N curves obtained from plane bending and axial fatigue tests on smooth and notched specimens evidences the superior performance of 7020 in terms of higher strength and corrosion cracking resistance.

  16. Low velocity impact behaviour of ultra high strength concrete panels

    Indian Academy of Sciences (India)

    Smitha Gopinath; R Ayashwarya; V Ramesh Kumar; Prabhat Ranjan Prem; A Rama Chandra Murthy; C K Madheswaran; R Nagesh Iyer

    2014-12-01

    This paper presents the results of an investigation carried out on Ultra High Strength Concrete (UHSC) panels subjected to low velocity projectile impact to assess impact resistance. UHSC panel of size 350 × 350 mm and thickness 15 mm is studied under drop weight impact loading for three different pre-determined drop heights ranging from 100 mm to 300 mm. The response of UHSC panel in terms of acceleration vs time is obtained experimentally. Numerical model has been developed to simulate the impact behaviour of UHSC panel. The Brittle cracking model is used to simulate the behaviour of UHSC panel under impact loading and to perform parametric studies by varying the volume fraction of steel fibres.

  17. Modelling of tension stiffening for normal and high strength concrete

    DEFF Research Database (Denmark)

    Christiansen, Morten Bo; Nielsen, Mogens Peter

    1998-01-01

    Accurate calculations of the stiffness of concrete members are rare. Only in the uncracked state and the fully cracked state, where the reinforcement is near yielding, the stiffness calculations are relatively easy. The difficulties are due to the fact that concrete between cracks may give...... a substantial contribution to the stiffness, a phenomenon which is generally referred to as tension stiffening. The present paper describes a new theory of tension stiffening. It is based on a simple physical model for pure tension, which works with three different stages of crack generation. In a simplified...... form the model is extended to apply to biaxial stress fields as well. To determine the biaxial stress field, the theorem of minimum complementary elastic energy is used. The theory has been compared with tests on rods, disks, and beams of both normal and high strength concrete, and very good results...

  18. Low cycle fatigue behavior of high strength gun steels

    Institute of Scientific and Technical Information of China (English)

    Maoqiu Wang; Han Dong; Qi Wang; Changgang Fan

    2004-01-01

    The low cycle fatigue (LCF) behavior of two high strength steels, with nominal chemical compositions (mass fraction, %)of 0.40C-1.5Cr-3Ni-0.4Mo-0.2V (PCrNi3MoV) and 0.25C-3Cr-3Mo-0.8Ni-0.1Nb (25Cr3Mo3NiNb), was investigated by using the smooth bar specimens subjected to strained-controlled push-pull loading. It is found that both steels show cyclic softening, but 25Cr3Mo3NiNb steel has a lower tendency to cyclic softening. 25Cr3Mo3NiNb steel has higher fatigue ductility, and its transition fatigue life is almost three times that of PCrNi3MoV. 25Cr3Mo3NiNb steel also shows higher LCF life either at a given total strain amplitude above 0.5% or at any given plastic strain amplitude, despite its lower monotonic tensile strength than that of PCrNi3MoV.It also means that 25Cr3Mo3NiNb steel can endure higher total strain amplitude and plastic strain amplitude at a given number of reversals to failure within 104. 25Cr3Mo3NiNb steel is expected to be a good gun steel with high LCF properties because only several thousand firings are required for gun barrel in most cases.

  19. Experimental Study on Elastic-Plastic Behavior of SRC Columns with High Strength Steel

    OpenAIRE

    2006-01-01

    The demand to use high strength and high performance material because of large span and high rise of building in recent years. As to use of high-strength steel in composite steel and reinforced concrete structures, it remains to be clarified whether the ductile behavior can be ensured, especially when the high-strength steel is used in combination with High-strength concrete. This paper describes the test results on the elasto-plastic behavior of SRC column using high strength steel, and disc...

  20. Behaviour of High Strength Steel Endplate Connections in Fire and after Fire

    NARCIS (Netherlands)

    Qiang, X.

    2013-01-01

    The aim of this research is to reveal more information and understanding on behaviour and failure mechanisms of high strength steel endplate connections (combining high strength steel endplates with either mild steel or high strength steel beams and columns in endplate connections) in fire and after

  1. A Novel TiNi/AlSi Composite with High Strength and High Damping Capacity

    Institute of Scientific and Technical Information of China (English)

    Shuwei LIU; Xiuyan LI; Desheng YAN; Haichang JIANG; Lijian RONG

    2008-01-01

    A novel TiNi/AlSi composite with high compressive strength and high damping capacity was obtained by infiltrating Al-12%Si alloy into porous TiNi alloy.It had been found that the high compressive strength (440 MPa) of TiNi/AlSi composite is due to the increase of effective carrying area after infiltrating Al-12%Si alloy,while the high damping capacity is contributed to TiNi carcass,Al-12%Si filling material and micro-slipping at the interface.

  2. Damage characterization of high-strength multiphase steels

    Science.gov (United States)

    Heibel, S.; Nester, W.; Clausmeyer, T.; Tekkaya, A. E.

    2016-11-01

    High-strength steels show an entirely different material behavior than conventional deep-drawing steels. This fact is caused among others by the multiphase nature of their structure. The Forming Limit Diagram as the classic failure criterion in forming simulation is only partially suitable for this class of steels. An improvement of the failure prediction can be obtained by using damage mechanics. Therefore, an exact knowledge of the material-specific damage is essential for the application of various damage models. In this paper the results of microstructure analysis of a dual-phase steel and a complex-phase steel with a tensile strength of 1000 MPa are shown comparatively at various stress conditions. The objective is to characterize the basic damage mechanisms and based on this to assess the crack sensitivity of both steels. First a structural analysis with regard to non-metallic inclusions, the microstructural morphology, phase identification and the difference in microhardness between the structural phases is carried out. Subsequently, the development of the microstructure at different stress states between uniaxial and biaxial tension is examined. The damage behavior is characterized and quantified by the increase in void density, void size and the quantity of voids. The dominant damage mechanism of the dual-phase steel is the void initiation at phase boundaries, within harder structural phases and at inclusions. In contrast the complex-phase steel shows a significant growth of a smaller amount of voids which initiate only at inclusions. To quantify the damage tolerance and the susceptibility of cracking the criterion of the fracture forming limit line (FFL) is used. The respective statements are supported by results of investigations regarding the edge-crack sensitivity.

  3. 车用热成形先进高强度钢板样件的热胀形特征及成形性分析%Thermal Expansion Analysis Based on Forming Limit Diagram for Improving the Formability of Automotive Hot-forming Advanced High Strength Steel Parts

    Institute of Scientific and Technical Information of China (English)

    常颖; 靳菲; 李晓东; 史栋勇; 王存宇; 赵坤民

    2014-01-01

    通过高温热胀形特征分析,研究热冲压22MnB5合金在不同温度下的成形性,并利用Dynaform软件仿真验证。比较成形温度在800℃和700℃时样件的热胀形特征,结果表明,在800℃时成形,样件由于平面应变方向主应变过大,拉压应变区次应力为负值,造成拉伸破裂;在700℃下冲压成形的试件,各部分应变都处于安全区域,双向拉伸区域和拉伸-压缩复合区域的变形均匀,较前者成形性良好。另外,提出关于热成形先进高强度钢(Advanced high strength steel, AHSS)样件,其最佳成形温度不是现有文献报道的800~850℃的范围内,该结论为深入探索最佳成形温度、提高成形性提供了方向;建立成形前的快冷法(冷速不低于27℃/s),降温到目标温度700℃左右冲压成形。试验证明:通过该方法,样件的成形性明显改善,微观结构更为致密。%Based on the high-temperature thermal expansion analysis, the formability at different temperature of hot-forming 22MnB5 is studied and also verified by Dynaform simulation. Comparing the thermal expansion characteristics at forming temperature 800℃ and 700℃, the results suggest that:Forming at 800℃, the sample results in a tensile rupture since the principal strain in plane strain direction is too large, while the secondary strain in tensile-compressive zone is negative; forming at 700℃, the formability is significantly improved since the strain of all parts remain in a safety area and sample has a uniform deformation in biaxial stretching region and tensile-compressive zone. In addition, this work puts forward that the optimized forming temperature of hot-forming advanced high strength steel(AHSS) sample is not in the range of 800℃ to 850℃ reported in present literatures. This conclusion provides directions for deep exploration of optimized forming temperature and improvement of formability. A rapid cooling method is

  4. Nanocrystalline High-Entropy Alloys: A New Paradigm in High-Temperature Strength and Stability.

    Science.gov (United States)

    Zou, Yu; Wheeler, Jeffrey M; Ma, Huan; Okle, Philipp; Spolenak, Ralph

    2017-03-08

    Metals with nanometer-scale grains or nanocrystalline metals exhibit high strengths at ambient conditions, yet their strengths substantially decrease with increasing temperature, rendering them unsuitable for usage at high temperatures. Here, we show that a nanocrystalline high-entropy alloy (HEA) retains an extraordinarily high yield strength over 5 GPa up to 600 °C, 1 order of magnitude higher than that of its coarse-grained form and 5 times higher than that of its single-crystalline equivalent. As a result, such nanostructured HEAs reveal strengthening figures of merit-normalized strength by the shear modulus above 1/50 and strength-to-density ratios above 0.4 MJ/kg, which are substantially higher than any previously reported values for nanocrystalline metals in the same homologous temperature range, as well as low strain-rate sensitivity of ∼0.005. Nanocrystalline HEAs with these properties represent a new class of nanomaterials for high-stress and high-temperature applications in aerospace, civilian infrastructure, and energy sectors.

  5. Effects of GFF Bands on Normal and High Strength Concrete Cylinders

    OpenAIRE

    Jayaprakash, J; Abdul Aziz Abdul Samad; Noridah Mohamad; K.K. Choong; M.J. Megat Azmi; H.A.B. Badorul

    2010-01-01

    This paper exemplifies the effects of externally confined Glass Fibre Fabric (GFF) bands on normal and high strength concrete cylinders. Twelve normal and high strength concrete cylinders were cast and tested in the laboratory environment under axial compression to failure. The experimental results show that the degree of confinement of discrete GFF confined high strength concrete cylinders was significantly better than normal strength concrete cylinders with GFF bands, however...

  6. Technical Note: Filler and superplasticizer usage on high strength concrete

    Directory of Open Access Journals (Sweden)

    Sümer, M.

    2007-08-01

    Full Text Available In this research, the effects of filler (rock-dust usage on high strength concrete have been investigated through lab experiments and some results have been obtained. The experiments involved three series of concrete with different cement proportions of 375 kg/m3, 400 kg/m3, and 425 kg/m3. For each series of concrete, three different groups of samples have been prepared, the first one being the reference concrete which contained 0% chemical admixture and 0% filler, the second one contained 1.5% chemical admixture and 0% filler and finally the last group contained 1.5% chemical admixture and 5% filler to the weight of cement used. The chemical admixture used was a type of Super plasticizer with a brand name of “DARACEM 190”, and the cement used was Ordinary Portland Cement of target compressive strength 42.5 N/mm2, obtained from Nuh Cement Plant. For each batch, Slump Tests and Unit Weight Tests were performed. For each stage and group, two 15 cm cubic samples have been tested for Compressive Strength after being cured in water at 20 ± 2 °C for ages of 3 days, 7 days, 28 and 60 days. The total number of samples was 72. As a result, filler usage was found to reduce the porosity of Concrete, increase the Unit Weight of Concrete, increase the need for water and improve the Compressive Strength Properties of Concrete.En el presente trabajo se estudia la influencia de la utilización de un “filler” (polvo mineral en el comportamiento del hormigón de altas prestaciones. Para ello, se realizan ensayos de laboratorio en los que se emplean tres series de hormigón, cada una con una dosificación de cemento distinta, de 375, 400 y 425 kg/m3. Se preparan tres grupos de probetas de cada serie, el primero o de referencia con 0% de aditivo químico y 0% de “filler”, el segundo con un 1,5% del aditivo químico y 0% de “filler” y el tercero con un 1,5% del aditivo químico y un 5% de “filler” en peso del cemento. Como aditivo se

  7. High strength alumina produced by direct coagulation casting

    Energy Technology Data Exchange (ETDEWEB)

    Baader, F.H.; Will, J.; Tieche, D. [Swiss Federal Institute of Technology, Zuerich (Switzerland)

    1995-09-01

    Direct Coagulation Casting is a new colloidal forming technique. Double layer stabilized, concentrated alumina suspensions are solidified by shifting the suspensions pH from 4 towards the isoelectric point at 9 using the in situ enzyme-catalyzed decomposition of urea. This reaction minimizes the repulsive forces between the suspended particles. The remaining, attractive Van der Waals forces form a stiff particle network. Suspensions with low viscosities (0.3 Pa*s, 59 vol%) were prepared at pH 4. Deagglomeration of the suspensions by ball milling reduced the agglomerate size below 5 pm. The coagulation kinetics could be influenced either by the urease concentration or by the suspension temperature. Process variables were established, providing long idle times, which allowed additional filtration and degassing steps. Coagulation was followed by drying and sintering, whereby densities of more than 3.97 g/cm{sup 3}, a 4-point bending strength of 685 MPa (HIPed) and a high reliablility (m = 40) for high purity alumina were achieved. DCC has the potential to improve the reliability of alumina components of complex shape, as well as to avoid expensive molding.

  8. 1200MPa级超高强度钢板冲压成形性能及其断裂机理的实验研究%Experimental Study of Instability Mechanism on 1 200 MPa Advanced High Strength Steel Sheets in the Process of Stamping

    Institute of Scientific and Technical Information of China (English)

    何昌炜; 郭必檬; 王武荣; 韦习成

    2012-01-01

    The limit drawing formability of two advanced high strength steel sheets (AHSS) of tensile strength 1 200 MPa with the cup drawing test was studied. Their instability and failure mechanisms were also discussed from the standpoint of the microstructure. The results show that the limiting drawing ratio (I.DR) of theDP1200 and the M1200 are 2. 03 and 1.99, respectively. Their uniaxial tensile properties are difficult to accurately reflect the forming performance of material under the complex stress state. A large number of dimples on the fracture surfaces can be seen, which testifies the ductile fracture mode, but the crack propagation mechanism is not the same. For DP1200 steel, the failure mode is the crack propagation along the ferrite/martensite interfaces as well as through the martensitic grains. In M1200 steel, the crack propagates along the martensite interfaces.%通过圆筒拉深试验研究了1200MPa级超高强度双相钢板(DP1200)和纯马氏体铜板(M1200)的极限拉深成形性能,采用扫描电子显微镜观察分析了铜板的微观组织形貌与结构,探讨了其微观组织结构与断裂机理的关系.结果表明:DP1200和M1200的极限拉延比分别为2.03和1.99,其单向拉伸性能不能准确地反映铜板材料在复杂应力状态下的成形性能;2种钢板的断裂模式均为断口分布着大量韧窝的韧性断裂,但其裂纹扩展机理不同.DPl200中的裂纹是以沿铁素体/马氏体相界为主,兼有穿过马氏体相并扩展的失效模式;而M1200铜中的裂纹是沿马氏体晶界扩展的失效模式.

  9. Core-shell structured titanium-nitrogen alloys with high strength, high thermal stability and good plasticity

    Science.gov (United States)

    Zhang, Y. S.; Zhao, Y. H.; Zhang, W.; Lu, J. W.; Hu, J. J.; Huo, W. T.; Zhang, P. X.

    2017-01-01

    Multifunctional materials with more than two good properties are widely required in modern industries. However, some properties are often trade-off with each other by single microstructural designation. For example, nanostructured materials have high strength, but low ductility and thermal stability. Here by means of spark plasma sintering (SPS) of nitrided Ti particles, we synthesized bulk core-shell structured Ti alloys with isolated soft coarse-grained Ti cores and hard Ti-N solid solution shells. The core-shell Ti alloys exhibit a high yield strength (~1.4 GPa) comparable to that of nanostructured states and high thermal stability (over 1100 °C, 0.71 of melting temperature), contributed by the hard Ti-N shells, as well as a good plasticity (fracture plasticity of 12%) due to the soft Ti cores. Our results demonstrate that this core-shell structure offers a design pathway towards an advanced material with enhancing strength-plasticity-thermal stability synergy.

  10. RESEARCH ON CHEMICAL COMPOSITION AND MICROSTRUCTURE OF NEWLY-DEVELOPED HIGH STRENGTH AND HIGH ELONGATION STEELS

    Institute of Scientific and Technical Information of China (English)

    Y. Chen; X. Chen; A.M. Guo; D.X. Luo; B.F. Xu; Z.X. Yuan; P.H. Li; S.K. Pu; S.B. Zhou

    2003-01-01

    The different chemical composition of silicon and manganese as well as different re-tained austenite fraction ranged from 4% to 10% of the high strength and high elon-gation steels were studied in the paper. The dislocations and carbon concentrationin retained austenite were observed by a transmission electron microscope and anelectric probe analyzer, respectively. The experimental results showed that silicon andmanganese are two fundamental alloying elements to stabilize austenite effectively butretaining austenite in different mechanisms. Meanwhile, the cooling processing playedan important role in controlling the fraction of retained austenite of the hot-rolledhigh strength and high plasticity steels.

  11. Anomolous Fatigue Crack Growth Phenomena in High-Strength Steel

    Science.gov (United States)

    Forth, Scott C.; James, Mark A.; Johnston, William M., Jr.; Newman, James C., Jr.

    2004-01-01

    The growth of a fatigue crack through a material is the result of a complex interaction between the applied loading, component geometry, three-dimensional constraint, load history, environment, material microstructure and several other factors. Previous studies have developed experimental and computational methods to relate the fatigue crack growth rate to many of the above conditions, with the intent of discovering some fundamental material response, i.e. crack growth rate as a function of something. Currently, the technical community uses the stress intensity factor solution as a simplistic means to relate fatigue crack growth rate to loading, geometry and all other variables. The stress intensity factor solution is a very simple linear-elastic representation of the continuum mechanics portion of crack growth. In this paper, the authors present fatigue crack growth rate data for two different high strength steel alloys generated using standard methods. The steels exhibit behaviour that appears unexplainable, compared to an aluminium alloy presented as a baseline for comparison, using the stress intensity factor solution.

  12. Dynamic recrystallization behavior and kinetics of high strength steel

    Institute of Scientific and Technical Information of China (English)

    吴光亮; 周超洋; 刘新彬

    2016-01-01

    The dynamic recrystallization behavior of high strength steel during hot deformation was investigated. The hot compression test was conducted in the temperature range of 950−1150 °C under strain rates of 0.1, 1 and 5 s−1. It is observed that dynamic recrystallization (DRX) is the main flow softening mechanism and the flow stress increases with decreasing temperature and increasing strain rate. The relationship between material constants (Q, n, α and lnA) and strain is identified by the sixth order polynomial fit. The constitutive model is developed to predict the flow stress of the material incorporating the strain softening effect and verified. Moreover, the critical characteristics of DRX are extracted from the stress−strain curves under different deformation conditions by linear regression. The dynamic recrystallization volume fraction decreases with increasing strain rate at a constant temperature or decreasing deformation temperature under a constant strain rate. The kinetics of DRX increases with increasing deformation temperature or strain rate.

  13. High strength bioactive glass-ceramic scaffolds for bone regeneration.

    Science.gov (United States)

    Vitale-Brovarone, Chiara; Baino, Francesco; Verné, Enrica

    2009-02-01

    This research work is focused on the preparation of macroporous glass-ceramic scaffolds with high mechanical strength, equivalent with cancellous bone. The scaffolds were prepared using an open-cells polyurethane sponge as a template and glass powders belonging to the system SiO(2)-P(2)O(5)-CaO-MgO-Na(2)O-K(2)O. The glass, named as CEL2, was synthesized by a conventional melting-quenching route, ground and sieved to obtain powders of specific size. A slurry of CEL2 powders, polyvinyl alcohol (PVA) as a binder and water was prepared in order to coat, by a process of impregnation, the polymeric template. A thermal treatment was then used to remove the sponge and to sinter the glass powders, in order to obtain a replica of the template structure. The scaffolds were characterized by means of X-ray diffraction analysis, morphological observations, density measurements, volumetric shrinkage, image analysis, capillarity tests, mechanical tests and in vitro bioactivity evaluation.

  14. Performance of High Strength POFA Concrete in Acidic Environment

    Directory of Open Access Journals (Sweden)

    Mohamed Ismail

    2010-03-01

    disposing palm oil fuel ash, a by-product of palm oil mill since many years ago. The discovery made by researchers of Universiti Teknologi Malaysia last century in revealing the potential of this finely ground waste as a partial cement replacement in normal concrete has stem efforts towards studying the possibility of using it in high strength concrete production. This paper illustrates the durability aspect of high strength concrete produced using POFA of different fineness when exposed to acidic environment. Two POFA concrete mixes with different fineness termed (POFA 45 and POFA 10 at 20% replacement level by weight of cement and an OPC concrete mix functioning as control specimen termed Po was considered in this study. All the specimens were subjected to water curing for 28 days before immersed in the hydrochloric solution having pH 2 for 1800 hours. The progressive deterioration was evaluated through mass changing of the specimens, visual inspection and relative compressive strength determinations. Conclusively, the study found that increase in the POFA fineness enhances the resistance of high strength POFA concrete towards acid attack.

  15. Springback Prediction and Compensation for a High Strength Steel Side Impact Beam

    Science.gov (United States)

    Dutton, Trevor; Edwards, Richard; Blowey, Andrew

    2005-08-01

    Prediction of formability for sheet metal pressings has advanced to a high state of confidence in recent years. The major challenge is now to predict springback and, moreover, to assist in the design of tooling to correctly compensate for springback. This is particularly the case for materials now being routinely considered for automotive production, such as aluminium and ultra high strength steels, which are prone to greater degrees of springback than traditional mild steels. This paper presents a case study based on the tool design for an ultra high strength steel side impact beam. The forming and springback simulations, carried out using eta/DYNAFORM (based on the LS-DYNA solver), are reported and compared to measurements from the prototype panels. The analysis parameters used in the simulation are presented, and the sensitivity of the results to variation in physical properties is also reviewed. The process of compensating the tools based on the analysis prediction is described; finally, an automated springback compensation method is also applied and the results compared with the final tool design.

  16. Silicone elastomers with high dielectric permittivity and high dielectric breakdown strength based on dipolar copolymers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Yu, Liyun; Daugaard, Anders Egede;

    2014-01-01

    Dielectric elastomers (DES) are a promising new transducer technology, but high driving voltages limit their current commercial potential. One method used to lower driving voltage is to increase dielectric permittivity of the elastomer. A novel silicone elastomer system with high dielectric permi......-4-nitrobenzene. Here, a high increase in dielectric permittivity (similar to 70%) was obtained without compromising other favourable DE properties such as elastic modulus, gel fraction, dielectric loss and electrical breakdown strength. © 2014 Elsevier Ltd. All rights reserved....

  17. EFFECT OF CARBON CONTENT ON MICROSTRUCTURE AND PROPERTIES OF HIGH STRENGTH AND HIGH ELONGATION STEELS

    Institute of Scientific and Technical Information of China (English)

    Y.Chen; X.Chen; 等

    2003-01-01

    The microstructure and mechanical properties of new kind of hot-rolled high strength and high elongation steels with retained austenite were studied by discussing the in-fluence of different carbon content.The research results indicate that carbon content has a significant effect on retaining austenite and consequently resulting in high elon-gation.Besides,new findings about relationship between carbon content and retained austenite as well as properties were discussed in the paper.

  18. Contraction of high strength invar steel during creep test

    Energy Technology Data Exchange (ETDEWEB)

    Myslowicki, T.; Bleck, W. [Dept. of Ferrous Metallurgy, Aachen Univ., Aachen (Germany); Weirich, T.E. [Central Facility for Electron Microscopy, Aachen Univ., Aachen (Germany)

    2003-06-01

    Modern large size Cathode Ray Tubes are equipped with so called ''true flat'' shadowmasks made of Invar steel. The mask is stretched onto a solid frame and both are submitted to a final heat treatment (blackening treatment). Elevated temperatures and pretension make the mask material prone to creep, resulting in disutility of the unit for the application. In order to reduce creep elongation of the mask material to a minimum, Mo added high strength Invar steels have been considered to provide the required specifications. Depending on prior processing this type of Invar steel shows an inexplicable contraction during the creep test. Even though this effect can be perfectly used to fulfil the creep requirements, the mechanisms involved were not understood. Focus of the present work was the examination of the effect of precipitations on the ''negative creep'' behaviour of the investigated Invar steel using carbon extraction replicae, transmission electron microscopy as well as SAED. Information about the chemical composition, morphology, size and number of the precipitations in the different states could be gained. The observations revealed that during the creep test, depending on the prior annealing temperature, the chemical composition of the precipitates changed. The Nb content decreased while simultaneously the Mo content increased. Due to the volume difference caused by Mo in solid solution and in precipitated form respectively, the precipitation of Mo during the creep test is supposed to cause the observed sample contraction. The results can be confirmed by calculating the effect of Mo on the distortion of the FeNi lattice. (orig.)

  19. High-cycle Fatigue Fracture Behavior of Ultrahigh Strength Steels

    Institute of Scientific and Technical Information of China (English)

    Weijun HUI; Yihong NIE; Han DONG; Yuqing WENG; Chunxu WANG

    2008-01-01

    The fatigue fracture behavior of four ultrahigh strength steels with different melting processes and therefore different inclusion sizes were studied by using a rotating bar two-point bending fatigue machine in the high-cycle regime up to 107 cycles of loading. The fracture surfaces were observed by field emission scanning electron microscopy (FESEM). It was found that the size of inclusion has significant effect on the fatigue behavior.For AISI 4340 steel in which the inclusion size is smaller than 5.5 μm, all the fatigue cracks except one did not initiated from inclusion but from specimen surface and conventional S-N curve exists. For 65Si2MnWE and Aermet 100 steels in which the average inclusion sizes are 12.2 and 14.9 μm, respectively, fatigue cracks initiated from inclusions at lower stress amplitudes and stepwise S-N curves were observed. The S-N curvedisplays a continuous decline and fatigue failures originated from large oxide inclusion for 60Si2CrVA steel in which the average inclusion size is 44.4 μm. In the case of internal inclusion-induced fractures at cycles beyond about 1×106 for 65Si2MnWE and 60Si2CrVA steels, inclusion was always found inside the fish-eye and a granular bright facet (GBF) was observed in the vicinity around the inclusion. The GBF sizes increasewith increasing the number of cycles to failure Nf in the long-life regime. The values of stress intensity factor range at crack initiation site for the GBF are almost constant with Nf, and are almost equal to that for the surface inclusion and the internal inclusion at cycles lower than about 1×106. Neither fish-eye nor GBF was observed for Aermet 100 steel in the present study.

  20. Advances in Very High Frequency Power Conversion

    DEFF Research Database (Denmark)

    Kovacevic, Milovan

    . Excellent performance and small size of magnetic components and capacitors at very high frequencies, along with constant advances in performance of power semiconductor devices, suggests a sizable shift in consumer power supplies market into this area in the near future. To operate dc-dc converter power...... to be applied, especially at low power levels where gating loss becomes a significant percentage of the total loss budget. Various resonant gate drive methods have been proposed to address this design challenge, with varying size, cost, and complexity. This dissertation presents a self-oscillating resonant gate...

  1. Advanced High Voltage Power Device Concepts

    CERN Document Server

    Baliga, B Jayant

    2012-01-01

    Advanced High Voltage Power Device Concepts describes devices utilized in power transmission and distribution equipment, and for very high power motor control in electric trains and steel-mills. Since these devices must be capable of supporting more than 5000-volts in the blocking mode, this books covers operation of devices rated at 5,000-V, 10,000-V and 20,000-V. Advanced concepts (the MCT, the BRT, and the EST) that enable MOS-gated control of power thyristor structures are described and analyzed in detail. In addition, detailed analyses of the silicon IGBT, as well as the silicon carbide MOSFET and IGBT, are provided for comparison purposes. Throughout the book, analytical models are generated to give a better understanding of the physics of operation for all the structures. This book provides readers with: The first comprehensive treatment of high voltage (over 5000-volts) power devices suitable for the power distribution, traction, and motor-control markets;  Analytical formulations for all the device ...

  2. High strength and high ductility in as-deposited nanocrystalline Ni

    Energy Technology Data Exchange (ETDEWEB)

    Dai Pinqiang; Xu Weichang; Tang Dian, E-mail: pqdai@126.co [School of Materials Science and Engineering, Fuzhou University, Fuzhou 350108 (China)

    2010-07-01

    In the present study, an electrodeposited nanocrystalline (nc) Ni sample with high strength and superior ductility relative to many other electrodeposited nc-Ni was prepared. The superior ductility in the present nc-Ni sample free of defects was ascribed to mixed grains, the size of which spanned nano- and sub-micro scales at its as-deposited state with a grain size distribution ranged from 5 to 120nm. Obvious dislocation motion happening in coarse-grained polycrystalline was observed in large grains of nc-Ni matrix resulting in a remarkable enhanced ductility without a decrease in the strength. The present nc-Ni with an average grain size of 27.2nm prepared by direct current electrodeposition shows the average ultimate tensile strength of 1200MPa and the average elongation to failure of 10.4%.

  3. Springback Compensation Process for High Strength Steel Automotive Parts

    Science.gov (United States)

    Onhon, M. Fatih

    2016-08-01

    This paper is about an advanced stamping simulation methodology used in automotive industry to shorten total die manufacturing times in a new vehicle project by means of benefiting leading edge virtual try-out technology.

  4. Fatigue crack Behaviour in a High Strength Tool Steel

    DEFF Research Database (Denmark)

    Højerslev, Christian; Carstensen, Jesper V.; Brøndsted, Povl

    2002-01-01

    value of maximally 80% of the yield strength of the steel. The size of this carbide damage zone increases with increasing load amplitude, and the zone is apparently associated with crack nucleation. On fatigue crack propagation plastic deformation of the matrix occurs in a radius of approximately 4...

  5. A new high strength and high tolerance-resistance Al-Li alloy

    Institute of Scientific and Technical Information of China (English)

    YANG Shou-jie; LU Zheng; DAI Sheng-long; HAN Ya-fang; YAN Ming-gao

    2006-01-01

    In order to develop a new high strength and high tolerance-resistance Al-Li alloy which can be used in aerospace industry,the effects of microalloying elements such as Mg, Ag, Mn and Zn on the mechanical properties of Al-Cu-Li alloys were studied. The results show that the strengthening effects of Mg+Ag and Mg+Zn additions are higher than those of the individual Mg, Ag or Zn addition. The element Mn can also bring some extent strengthening effects on the alloys, but it has nothing to do with the other microalloying elements present or not. Finally, a new Al-Li alloy with Mg+Zn+Mn additions was developed, which possesses high strength and high tolerance-resistance promising properties for aerospace applications.

  6. Corrosion Resistance of High Strength Concrete Containing Palm Oil Fuel Ash as Partial Cement Replacement

    OpenAIRE

    F. Mat Yahaya; Muthusamy, K.; Sulaiman, N.

    2014-01-01

    This experimental work investigates the influence of POFA as partial cement replacement towards corrosion resistance of high strength concrete. Plain high strength concrete (P0) with 100% ordinary Portland cement (control specimen) and POFA high strength concrete containing POFA as partial cement replacement material were used. At the first stage, mix with 20% POFA (P20) has been identified as the best performing mix after cubes (150×150×150 mm) containing various content of POFA as partial c...

  7. Advances in high power semiconductor diode lasers

    Science.gov (United States)

    Ma, Xiaoyu; Zhong, Li

    2008-03-01

    High power semiconductor lasers have broad applications in the fields of military and industry. Recent advances in high power semiconductor lasers are reviewed mainly in two aspects: improvements of diode lasers performance and optimization of packaging architectures of diode laser bars. Factors which determine the performance of diode lasers, such as power conversion efficiency, temperature of operation, reliability, wavelength stabilization etc., result from a combination of new semiconductor materials, new diode structures, careful material processing of bars. The latest progress of today's high-power diode lasers at home and abroad is briefly discussed and typical data are presented. The packaging process is of decisive importance for the applicability of high-power diode laser bars, not only technically but also economically. The packaging techniques include the material choosing and the structure optimizing of heat-sinks, the bonding between the array and the heat-sink, the cooling and the fiber coupling, etc. The status of packaging techniques is stressed. There are basically three different diode package architectural options according to the integration grade. Since the package design is dominated by the cooling aspect, different effective cooling techniques are promoted by different package architectures and specific demands. The benefit and utility of each package are strongly dependent upon the fundamental optoelectronic properties of the individual diode laser bars. Factors which influence these properties are outlined and comparisons of packaging approaches for these materials are made. Modularity of package for special application requirements is an important developing tendency for high power diode lasers.

  8. Application of cold drawn lamellar microstructure for developing ultra-high strength wires

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Composite materials having lamellar structure are known to have a good combination of high strength and ductility. They are widely used in the fields of automobiles, civil engineering and construction, machines and many other industries. An application of lamellar microstructure for developing ultra-high strength steel wires was studied and discussed. Based on the experimental results,the relationships between the strength increase and microstructure development during the cold wire drawing were studied to reveal the strengthening mechanism. As cold drawing proceeds, the wire strength extremely increases, the microstructure changes from large single crystal lamellar structure to very fine polycrystalline lamellar one which has nano-sized grains, high dislocation density and amorphous regions. From the results obtained, it is concluded that heavy cold drawing technique is an effective method for lamellar composite to get high strength wires. Furthermore, formation process of the best microstructure for producing the ultra-high strength wires was also discussed.

  9. Inferring strength and deformation properties of hot mix asphalt layers from the GPR signal: recent advances

    Science.gov (United States)

    Tosti, Fabio; Benedetto, Andrea; Bianchini Ciampoli, Luca; Adabi, Saba; Pajewski, Lara

    2015-04-01

    The great flexibility of ground-penetrating radar has led to consider worldwide this instrument as an effective and efficient geophysical tool in several fields of application. As far as pavement engineering is concerned, ground-penetrating radar is employed in a wide range of applications, including physical and geometrical evaluation of road pavements. Conversely, the mechanical characterization of pavements is generally inferred through traditional (e.g., plate bearing test method) or advanced non-destructive techniques (e.g., falling weight deflectometer). Nevertheless, measurements performed using these methods, inevitably turn out to be both much more time-consuming and low-significant whether compared with ground-penetrating radar's potentials. In such a framework, a mechanical evaluation directly coming from electromagnetic inspections could represent a real breakthrough in the field of road assets management. With this purpose, a ground-penetrating radar system with 600 MHz and 1600 MHz center frequencies of investigation and ground-coupled antennas was employed to survey a 4m×30m flexible pavement test site. The test area was marked by a regular grid mesh of 836 nodes, respectively spaced by a distance of 0.40 m alongside the horizontal and vertical axes. At each node, the elastic modulus was measured using a light falling weight deflectometer. Data processing has provided to reconstruct a 3-D matrix of amplitudes for the surveyed area, considering a depth of around 300 mm, in accord to the influence domain of the light falling weight deflectometer. On the other hand, deflectometric data were employed for both calibration and validation of a semi-empirical model by relating the amplitude of signal reflections through the media along fixed depths within the depth domain considered, and the Young's modulus of the pavement at the evaluated point. This statistically-based model is aimed at continuously taking into account alongside the depth of investigation

  10. High strength and high ductility behavior of 6061-T6 alloy after laser shock processing

    Science.gov (United States)

    Gencalp Irizalp, Simge; Saklakoglu, Nursen

    2016-02-01

    The plastic deformation behavior of 6061-T6 alloy which was subjected to severe plastic deformation (SPD) at high strain rates during laser shock processing (LSP) was researched. In LSP-treated materials, the near surface microstructural change was examined by TEM and fracture surfaces after tensile testing were examined by SEM. An increase in strength of metallic materials brings about the decrease in ductility. In this study, the results showed that LSP-treated 6061-T6 alloy exhibited both high strength and high ductility. TEM observation showed that stacking fault (SF) ribbon enlarged, deformation twins formed and twin boundary increased in LSP-treated 6061-T6 alloy. This observation was an indication of stacking fault energy (SFE) decrease. Work hardening capability was recovered after LSP impacts.

  11. Durability Index Performance of High Strength Concretes Made Based on Different Standard Portland Cements

    Directory of Open Access Journals (Sweden)

    Stephen O. Ekolu

    2012-01-01

    Full Text Available A consortium of three durability index test methods consisting of oxygen permeability, sorptivity and chloride conductivity were used to evaluate the potential influence of four (4 common SANS 10197 cements on strength and durability of concrete. Twenty four (24 concrete mixtures of water-cement ratios (w/c's = 0.4, 0.5, 0.65 were cast using the cement types CEM I 42.5N, CEM II/A-M (V-L 42.5N, CEM IV/B 32.5R and CEM II/A-V 52.5N. The concretes investigated fall in the range of normal strength, medium strength and high strength concretes. It was found that the marked differences in oxygen permeability and sorptivity results observed at normal and medium strengths tended to vanish at high concrete strengths. Also, the durability effects attributed to use of different cement types appear to diminish at high strengths. Cements of low strength and/or that contained no extenders (CEM 32.5R, CEM I 42.5N showed greater sensitivity to sorptivity, relative to other cement types. Results also show that while concrete resistance to chlorides generally improves with increase in strength, adequately high chloride resistance may not be achieved based on high strength alone, and appropriate incorporation of extenders may be necessary.

  12. Chloride-Ion Penetrability and Mechanical Analysis of High Strength Concrete with Copper Slag

    Directory of Open Access Journals (Sweden)

    Savaş Erdem

    2014-05-01

    Full Text Available The use of waste materials and industrial by-products in high-strength concrete could increase the sustainability of the construction industry. In this study, the potential of using copper slag as coarse aggregate in high-strength concrete was experimentally investigated. The effects of replacing gravel coarse aggregate by copper slag particles on the compressive strength, chloride ion- migration, water permeability and impact resistance of high-strength concretes were evaluated. Incorporating copper slag coarse particles resulted in a compressive strength increase of about 14 % on average partly due to the low Ca/Si ratio through the interface area of this concrete (more homogenous internal structure as confirmed by the energy dispersive X-ray micro chemical analysis. It was also found that the copper slag high-strength concrete provided better ductility and had much greater load carrying capacity compared to gravel high-strength concrete under dynamic conditions. Finally, it was observed that in comparison to the high strength concrete with slag, the chloride migration coefficient from non-steady state migration was approximately 30 % greater in the gravel high-strength concrete.

  13. Deformation behavior of a high strength multiphase steel at macro- and micro-scales

    Energy Technology Data Exchange (ETDEWEB)

    Diego-Calderón, I. de, E-mail: irenedediego.calderon@imdea.org [IMDEA Materials Institute, Calle Eric Kandel 2, Getafe 28906, Madrid (Spain); Santofimia, M.J. [Department of Materials Science and Engineering, Delft University of Technology, 2628 CD Delft (Netherlands); Molina-Aldareguia, J.M.; Monclús, M.A.; Sabirov, I. [IMDEA Materials Institute, Calle Eric Kandel 2, Getafe 28906, Madrid (Spain)

    2014-08-12

    Advanced high strength steels via quenching and partitioning (Q and P) process are a mainstream trend in modern steel research. This work contributes to a better understanding of their local mechanical properties and local deformation behavior at the micro-scale in relation to their local microstructure. A low alloyed steel was subjected to Q and P heat treatments leading to the formation of complex multiphase microstructures. Nanoindentation tests were performed to measure nanohardness of individual phases and to generate 2D maps showing nanohardness distribution on the surface of the material. To study local in-plane plastic strain distribution during deformation, in situ tensile tests were carried out using the digital image correlation technique. Significant partitioning of plastic strain between phase microconstituents during tensile deformation is shown. The effect of the microstructure on the mechanical behavior of the Q and P processed steel is analyzed. The local plastic deformation behavior of individual phases is discussed with respect to their strength and their spatial orientation.

  14. Advanced Materials for High Temperature, High Performance, Wide Bandgap Power Modules

    Science.gov (United States)

    O'Neal, Chad B.; McGee, Brad; McPherson, Brice; Stabach, Jennifer; Lollar, Richard; Liederbach, Ross; Passmore, Brandon

    2016-01-01

    Advanced packaging materials must be utilized to take full advantage of the benefits of the superior electrical and thermal properties of wide bandgap power devices in the development of next generation power electronics systems. In this manuscript, the use of advanced materials for key packaging processes and components in multi-chip power modules will be discussed. For example, to date, there has been significant development in silver sintering paste as a high temperature die attach material replacement for conventional solder-based attach due to the improved thermal and mechanical characteristics as well as lower processing temperatures. In order to evaluate the bond quality and performance of this material, shear strength, thermal characteristics, and void quality for a number of silver sintering paste materials were analyzed as a die attach alternative to solder. In addition, as high voltage wide bandgap devices shift from engineering samples to commercial components, passivation materials become key in preventing premature breakdown in power modules. High temperature, high dielectric strength potting materials were investigated to be used to encapsulate and passivate components internal to a power module. The breakdown voltage up to 30 kV and corresponding leakage current for these materials as a function of temperature is also presented. Lastly, high temperature plastic housing materials are important for not only discrete devices but also for power modules. As the operational temperature of the device and/or ambient temperature increases, the mechanical strength and dielectric properties are dramatically reduced. Therefore, the electrical characteristics such as breakdown voltage and leakage current as a function of temperature for housing materials are presented.

  15. High performance anode for advanced Li batteries

    Energy Technology Data Exchange (ETDEWEB)

    Lake, Carla [Applied Sciences, Inc., Cedarville, OH (United States)

    2015-11-02

    The overall objective of this Phase I SBIR effort was to advance the manufacturing technology for ASI’s Si-CNF high-performance anode by creating a framework for large volume production and utilization of low-cost Si-coated carbon nanofibers (Si-CNF) for the battery industry. This project explores the use of nano-structured silicon which is deposited on a nano-scale carbon filament to achieve the benefits of high cycle life and high charge capacity without the consequent fading of, or failure in the capacity resulting from stress-induced fracturing of the Si particles and de-coupling from the electrode. ASI’s patented coating process distinguishes itself from others, in that it is highly reproducible, readily scalable and results in a Si-CNF composite structure containing 25-30% silicon, with a compositionally graded interface at the Si-CNF interface that significantly improve cycling stability and enhances adhesion of silicon to the carbon fiber support. In Phase I, the team demonstrated the production of the Si-CNF anode material can successfully be transitioned from a static bench-scale reactor into a fluidized bed reactor. In addition, ASI made significant progress in the development of low cost, quick testing methods which can be performed on silicon coated CNFs as a means of quality control. To date, weight change, density, and cycling performance were the key metrics used to validate the high performance anode material. Under this effort, ASI made strides to establish a quality control protocol for the large volume production of Si-CNFs and has identified several key technical thrusts for future work. Using the results of this Phase I effort as a foundation, ASI has defined a path forward to commercialize and deliver high volume and low-cost production of SI-CNF material for anodes in Li-ion batteries.

  16. Development of 30Cr06A, a high strength cast steel and its welding ability

    Institute of Scientific and Technical Information of China (English)

    GAO You-jin

    2008-01-01

    High performance hydraulic supports have a high requirement in strength, toughness and welding ability of socket ma- terial. Targeting this problem, we analyzed the properties of the high strength socket material 30Cr06, used in high performance hydraulic supports both at home and abroad and developed a new kind of high strength cast steel 30Cr06A, by making use of an orthogonal experiment, which provided the design conditions for its optimal composition. The result shows that the strength and toughness of the newly developed high strength cast steel 30Cr06A is much better than that of 30Cr06. Theoretical calculations, mechanical property tests and hardness distribution tests of welded joints were carried out for a study of the welding ability of the new material, which is proved to be very good. Therefore, this 30Cr06A material has been successfully used in the socket of high performance hydraulic support.

  17. High strength microstructural forms developed in titanium alloys by rapid heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ivasishin, O.M. [Institute of Metal Physics, Kiev (Ukraine)

    2001-09-01

    It is shown that rapid heat treatment of alpha+beta and beta titanium alloys, which includes rapid heating of alloys with initial equiaxed microstructure into single-phase beta field is able to produce microstructural forms in which high strength can be well balanced with other mechanical properties. Main advantage of rapid heating approach comes from the possibility to extend the level of ''useful'' strength. Desirably high strength is provided by intragranular morphology and microchemistry while beta-grain refinement permits a reliability of such high strength conditions. (orig.)

  18. Confined Tension and Triaxial Extension Tests on Eglin High-Strength Concrete

    Science.gov (United States)

    2014-10-17

    AFRL-RW-EG-TR-2014-120 Confined Tension and Triaxial Extension Tests on Eglin High-Strength Concrete Lance...EXTENSION TESTS ON EGLIN HIGH-STRENGTH CONCRETE FA8651-12-D-0309, Task 005 N/A 2502 9210 W0DT (1) Lance Besaw, Applied Research Associates, Inc. (2...models. All concretes exhibit higher strength in compression than in tension, therefore it is critical to understand the tensile properties of such

  19. Advances in High Energy Materials (Review Paper

    Directory of Open Access Journals (Sweden)

    U. R. Nair

    2010-03-01

    Full Text Available Research and development efforts for realizing higher performance levels of high energy materials (HEMs are continued unabated all over the globe. Of late, it is becoming increasingly necessary to ensure that such materials are also eco-friendly. This has provided thrust to research in the area of force multiplying HEMs and compounds free from pollution causing components. Enhancement of the performance necessitates introduction of strained structure or increase in oxygen balance to achieve near stoichiometry. The search for environment friendly molecules is focused on chlorine free propellant compositions and lead free primary explosives. Energetic polymers offer added advantage of partitioning of energy and thus not necessitating the concentration of only solid components (HEMs and metal fuels in the formulations, to achieve higher performance, thereby leading to improvement in energetics without adversely affecting the processability and mechanical properties. During recent times, research in the area of insensitive explosives has received impetus particularly with the signature of STANAG. This paper gives a review of the all-round advances in the areas of HEMs encompassing oxidizers, high-energy dense materials, insensitive high-energy materials, polymers and plasticizers. Selected formulations based on these materials are also included.Defence Science Journal, 2010, 60(2, pp.137-151, DOI:http://dx.doi.org/10.14429/dsj.60.327

  20. Advances in industrial high-power lasers

    Science.gov (United States)

    Schlueter, Holger

    2005-03-01

    Four major types of laser sources are used for material processing. Excluding Excimer lasers, this paper focuses on advances in High Power CO2 lasers, Solid State Lasers and Diode Lasers. Because of their unrivaled cost to brightness relationship the fast axial flow CO2 laser remains unrivaled for flat-sheet laser cutting. Adding approximately a kW of output power ever four years, this laser type has been propelling the entire sheet metal fabrication industry for the last two decades. Very robust, diffusion cooled annular discharge CO2 lasers with 2kW output power have enabled robot mounted lasers for 3D applications. Solid State Lasers are chosen mainly because of the option of fiber delivery. Industrial applications still rely on lamp-pumped Nd:YAG lasers with guaranteed output powers of 4.5 kW at the workpiece. The introduction of the diode pumped Thin Disc Laser 4.5 kW laser enables new applications such as the Programmable Focus Optics. Pumping the Thin Disc Laser requires highly reliable High Power Diode Lasers. The necessary reliability can only be achieved in a modern, automated semiconductor manufacturing facility. For Diode Lasers, electro-optical efficiencies above 65% are as important as the passivation of the facets to avoid Burn-In power degradation.

  1. Commercialization of NASA's High Strength Cast Aluminum Alloy for High Temperature Applications

    Science.gov (United States)

    Lee, Jonathan A.

    2003-01-01

    In this paper, the commercialization of a new high strength cast aluminum alloy, invented by NASA-Marshall Space Flight Center, for high temperature applications will be presented. Originally developed to meet U.S. automotive legislation requiring low- exhaust emission, the novel NASA aluminum alloy offers dramatic improvement in tensile and fatigue strengths at elevated temperatures (450 F-750 F), which can lead to reducing part weight and cost as well as improving performance for automotive engine applications. It is an ideal low cost material for cast components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. NASA alloy also offers greater wear resistance, dimensional stability, and lower thermal expansion compared to conventional aluminum alloys, and the new alloy can be produced economically from sand, permanent mold and investment casting. Since 2001, this technology was licensed to several companies for automotive and marine internal combustion engines applications.

  2. High Strength and Wear Resistant Aluminum Alloy for High Temperature Applications

    Science.gov (United States)

    Lee, Jonathan A.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    In this paper, a new high strength and wear resistant aluminum cast alloy invented by NASA-MSFC for high temperature applications will be presented. Developed to meet U.S. automotive legislation requiring low-exhaust emission, the novel NASA 398 aluminum-silicon alloy offers dramatic improvement in tensile and fatigue strengths at elevated temperatures (500 F-800 F), enabling new pistons to utilize less material, which can lead to reducing part weight and cost as well as improving performance. NASA 398 alloy also offers greater wear resistance, surface hardness, dimensional stability, and lower thermal expansion compared to conventional aluminum alloys for several commercial and automotive applications. The new alloy can be produced economically using permanent steel molds from conventional gravity casting or sand casting. The technology was developed to stimulate the development of commercial aluminum casting products from NASA-developed technology by offering companies the opportunity to license this technology.

  3. Microstructure and high-temperature strength of high Cr ODS tempered martensitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Ohtsuka, S., E-mail: ohtsuka.satoshi@jaea.go.jp; Kaito, T.; Tanno, T.; Yano, Y.; Koyama, S.; Tanaka, K.

    2013-11-15

    11-12Cr oxide dispersion strengthened (ODS) tempered martensitic steels underwent manufacturing tests and their ferritic–martensitic duplex structures were quantitatively evaluated by three methods: high-temperature X-ray diffraction (XRD), electron probe microanalyzer (EPMA), and metallography. It was demonstrated that excessive formation of residual-α ferrite, due to increasing Cr content, could be suppressed by appropriately controlling the concentration of the ferrite-forming and austenite-forming elements on the basis of the parameter “chemical driving force of α to γ reverse transformation. 11Cr-ODS steel containing a small portion of residual-α ferrite was successfully manufactured. In the as-received condition, this 11Cr-ODS steel was shown to have satisfactory creep strength and ductility, both as high as those of the 9Cr-ODS steel, while its 0.2% proof strength at 973 K was lower than in the 9Cr-ODS steel.

  4. Preparation for Retarding and High Early Strength Concrete

    Institute of Scientific and Technical Information of China (English)

    HU Zhijian; FENG Hao; WANG Xuefei

    2015-01-01

    The primary objective of this research was to determine optimum dosage of mixing concrete containing plasticizers and lfy ash, consistent with desirable structural grade concrete properties. Factorial tests were also conducted to investigate the four main factors: water-cementing materials ratio, water content, content of superplasticizers (SP) and fly ash content. It was found that the requirement for setting time played the dominant role in shrinkage and anti-cracking, and lfy ash played a critical role in workability and reducing heat of hydration but showed insigniifcant effects on slump, early strength and initial setting time of concrete.

  5. Strengthening Mechanism of a New 700 MPa Hot Rolled High Strength Steel

    Institute of Scientific and Technical Information of China (English)

    YI Hai-long; DU Lin-xiu; WANG Guo-dong; LIU Xiang-hua

    2008-01-01

    The microstructural evolution in a 700 MPa hot rolled high strength steel was analyzed in terms of strengthening mechanisms. The results show that the hot rolled sheet steel has yield strength of 710 MPa with good elongation and toughness. The strength of the developed 700 MPa hot rolled high strength steel is derived from the cumulative contribution of fine grain size, dislocation hardening and precipitation hardening. The fine grain strength ening and precipitation hardening are the dominant factors responsible for such high strength, and the amount of pre cipitation hardening is two or four times higher than that of conventional microalloyed hot rolled sheet steels reported in the past. Good toughness is due to refinement of ferrite grain size.

  6. Development of high toughness, high strength aluminide-bonded carbide ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Becher, P.F.; Plucknett, K.P.; Tiegs, T.N. [Oak Ridge National Lab., TN (United States)] [and others

    1997-04-01

    Cemented carbides are widely used in applications where resistance to abrasion and wear are important, particularly in combination with high strength and stiffness. In the present case, ductile aluminides have been used as a binder phase to fabricate dense carbide cermets by either sintering of mixed powders or a melt-infiltration sintering process. The choice of an aluminide binder was based on the exceptional high temperature strength and chemical stability exhibited by these alloys. For example, TiC-based composites with a Ni{sub 3}Al binder phase exhibit improved oxidation resistance, Young`s moduli > 375 GPa, high fracture strengths (> 1 GPa) that are retained to {ge} 900{degrees}C, and fracture toughness values of 10 to 15 MPa{radical}m, identical to that measured in commercial cobalt-bonded WC with the same test method. The thermal diffusivity values at 200{degrees}C for these composites are {approximately} 0.070 to 0.075 cm{sup 2}/s while the thermal expansion coefficients rise with Ni3Al content from {approximately} 8 to {approximately}11 x 10{sup {minus}6}/{degrees}C over the range of 8 to 40 vol. % Ni{sub 3}Al. The oxidation and acidic corrosion resistances are quite promising as well. Finally, these materials also exhibit good electrical conductivity allowing them to be sectioned and shaped by electrical discharge machining (EDM) processes.

  7. Effect of Hybrid Fibers on the Mechanical Properties of High Strength Concrete

    Directory of Open Access Journals (Sweden)

    Hamid H. Hussein, Saeed K. Rejeb Hayder T. Abd

    2014-04-01

    Full Text Available In this study, high strength concrete of 75 MPa compressive strength was investigated. The experimental program was designed to study the effect of fibers and hybrid fibers (steel and polypropylene fibers on the fresh (workability and wet density and hardened properties (compressive strength, splitting strength, flexural strength and dry density of high strength concrete. Results show that decreases in slump flow of all concrete mixtures containing steel, polypropylene and hybrid fibers compared with control mix (0% fiber. Hybrid high strength concrete with steel and polypropylene fibers showed superior compressive, splitting, flexural strengths over the others concrete without or with single fibers content. The test results indicate that the maximum increase in compressive and flexural strengths are obtains with the hybridization ratio (70%steel + 30% polypropylene and were equal to 14.54% and 23.34% respectively, compared with the control mix. While, the maximum increase in splitting tensile strength with (100% steel fiber + 0 polypropylene is 21.19%. 

  8. High-strength cast irons used for manufacturing parts of vaz passenger cars

    Science.gov (United States)

    Kitaigora, N. I.

    1996-10-01

    Methods for solving problems arising in the production of high-strength cast iron with stable properties and structure are considered. Results of introduction of new grades of high-strength cast iron instead of malleable cast iron and camshaft cast iron in the Volzhskii Automobile Plant are described.

  9. Manufacturing of complex high strength components out of high nitrogen steels at industrial level

    Institute of Scientific and Technical Information of China (English)

    Hannes NONEDER; Marion MERKLEIN

    2012-01-01

    High performance components,e.g.,fasteners,nowadays are usually made out of cold forged and heat treated steels like steel 1.5525 (20MnB4).To overcome the problems of heat treatment,e.g.,low surface quality,new workpiece materials for cold forging should be found to achieve the needlessness of heat treatment after cold forging.One possible material is given by high nitrogen steels like steel 1.3815 (X8CrMnN19-19).Due to the high strain hardening of these materials the process and tool design for an industrial batch process are challenging and should be conducted by FE-simulation.The numerical results show that,high strength tool materials,like PM-steels or cemented carbides,in most cases,are inevitable.Additionally to the selection of suitable tool materials,the tool layout should be developed further to achieve a high loadability of the tools.The FE-models,used for process and tool design,are validated with respect to the materials' flow and occurring forming force to assure a proper design process.Also the comparison of strength of components made out of steel 1.5525 in quenched and tempered conditions and steel 1.3815 in strain hardened condition is done.The results show that the component made of steel 1.3815 has a significantly higher strength than the component made of steel 1.5525.This shows that by the use of high nitrogen steels a high performance component can be manufactured by cold forging.

  10. Threshold Stress Intensity of Hydrogen-Induced Cracking and Stress Corrosion Cracking of High Strength Steel

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The threshold stress intensity of stress corrosion cracking (SCC) for 40CrMo steel in 3.5 % NaCl solution decreased exponentially with the increase of yield strength. The threshold stress intensity of hydrogen-induced cracking during dynamical charging for 40CrMo steel decreased linearly with the logarithm of the concentration of diffusible hydrogen. This equation was also applicable to SCC of high strength steel in aqueous solution. The critical hydrogen enrichment concentration necessary for SCC of high strength steel in water decreased exponentially with the increase of yield strength. Based on the results, the relationship between KISCC and σys could be deduced.

  11. Are anthropometric, flexibility, muscular strength, and endurance variables related to clubhead velocity in low- and high-handicap golfers?

    Science.gov (United States)

    Keogh, Justin W L; Marnewick, Michel C; Maulder, Peter S; Nortje, Jacques P; Hume, Patria A; Bradshaw, Elizabeth J

    2009-09-01

    The present study assessed the anthropometric profile (International Society for the Advancement of Kinanthropometry protocol), flexibility, muscular strength, and endurance of 20 male golfers. These data were collected in order to determine: a) the relationship between these kinanthropometric measures and clubhead velocity; and b) if these measures could distinguish low-handicap (LHG) and high-handicap (HHG) golfers. Ten LHG (handicap of 0.3 +/- 0.5) and 10 HHG (handicap of 20.3 +/- 2.4) performed 10 swings for maximum velocity and accuracy with their own 5-iron golf club at a wall-mounted target. LHG hit the target significantly more (115%) and had a 12% faster clubhead velocity than HHG (p < 0.01). The LHG also had significantly (28%) greater golf swing-specific cable woodchop (GSCWC) strength (p < 0.01) and tendencies for greater (30%) bench press strength and longer (5%) upper am and total arm (4%) length and less (24%) right hip internal rotation than HHG (0.01 < p < 0.05). GSCWC strength was significantly correlated to clubhead velocity (p < 0.01), with bench press and hack squat strength as well as upper arm and total arm length also approaching significance (0.01 < p < 0.05). Golfers with high GSCWC strength and perhaps greater bench press strength and longer arms may therefore be at a competitive advantage, as these characteristics allow the production of greater clubhead velocity and resulting ball displacement. Such results have implications for golf talent identification programs and for the prescription and monitoring of golf conditioning programs. While golf conditioning programs may have many aims, specific trunk rotation exercises need to be included if increased clubhead velocity is the goal. Muscular hypertrophy development may not need to be emphasized as it could reduce golf performance by limiting range of motion and/or increasing moment of inertia.

  12. Leg strength declines with advancing age despite habitual endurance exercise in active older adults.

    Science.gov (United States)

    Marcell, Taylor J; Hawkins, Steven A; Wiswell, Robert A

    2014-02-01

    Age-associated loss of muscle mass (sarcopenia) and strength (dynapenia) is associated with a loss of independence that contributes to falls, fractures, and nursing home admissions, whereas regular physical activity has been suggested to offset these losses. The purpose of this study was to evaluate the effect of habitual endurance exercise on muscle mass and strength in active older adults. A longitudinal analysis of muscle strength (≈4.8 years apart) was performed on 59 men (age at start of study: 58.6 ± 7.3 years) and 35 women (56.9 ± 8.2 years) who used endurance running as their primary mode of exercise. There were no changes in fat-free mass although body fat increased minimally (1.0-1.5%). Training volume (km·wk, d·wk) decreased in both the men and women. There was a significant loss of both isometric knee extension (≈5% per year) and knee flexion (≈3.6% per year) strength in both the men and women. However, there was no significant change in either isokinetic concentric or eccentric torque of the knee extensors. Our data demonstrated a significant decline in isometric knee extensor and knee flexor strength although there were no changes in body mass in this group of very active older men and women. Our data support newer exercise guidelines for older Americans suggesting resistance training be an integral component of a fitness program and that running alone was not sufficient to prevent the loss in muscle strength (dynapenia) with aging.

  13. Elevated-temperature properties of one long-life high-strength gun steel

    Institute of Scientific and Technical Information of China (English)

    Maoqiu Wang; Han Dong; Qi Wang

    2004-01-01

    The hardness, tensile strength and impact toughness of one quenched and tempered steel with nominal composition of Fe0.25C-3.0Cr-3.0Mo-0.6Ni-0.1Nb (mass fraction) both at room temperature and at elevated temperatures were investigated in order to develop high-strength steel for long-life gun barrel use. It is found that the steel has lower decrease rate of tensile strength at elevated temperature in comparison with the commonly used G4335V high-strength gun steel, which contains higher Ni and lower Cr and Mo contents. The high elevated-temperature strength of the steel is attributed to the strong secondary hardening effect and high tempering softening resistance caused by the tempering precipitation of fine Mo-rich M2C carbides in the α-Fe matrix. The experimental steel is not susceptible to secondary hardening embrittlement, meanwhile, its room-temperature impact energy is much higher than the normal requirement of impact toughness for high strength gun steels. Therefore, the steel is suitable for production of long-life high-strength gun barrels with the combination of superior elevated-temperature strength and good impact toughness.

  14. Advanced Functionalities for Highly Reliable Optical Networks

    DEFF Research Database (Denmark)

    An, Yi

    This thesis covers two research topics concerning optical solutions for networks e.g. avionic systems. One is to identify the applications for silicon photonic devices for cost-effective solutions in short-range optical networks. The other one is to realise advanced functionalities in order to in......) using two exclusive OR (XOR) gates realised by four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) is experimentally demonstrated and very low (~ 1 dB) total operation penalty is achieved....... to increase the availability of highly reliable optical networks. A cost-effective transmitter based on a directly modulated laser (DML) using a silicon micro-ring resonator (MRR) to enhance its modulation speed is proposed, analysed and experimentally demonstrated. A modulation speed enhancement from 10 Gbit...... interconnects and network-on-chips. A novel concept of all-optical protection switching scheme is proposed, where fault detection and protection trigger are all implemented in the optical domain. This scheme can provide ultra-fast establishment of the protection path resulting in a minimum loss of data...

  15. Integrating advanced facades into high performance buildings

    Energy Technology Data Exchange (ETDEWEB)

    Selkowitz, Stephen E.

    2001-05-01

    Glass is a remarkable material but its functionality is significantly enhanced when it is processed or altered to provide added intrinsic capabilities. The overall performance of glass elements in a building can be further enhanced when they are designed to be part of a complete facade system. Finally the facade system delivers the greatest performance to the building owner and occupants when it becomes an essential element of a fully integrated building design. This presentation examines the growing interest in incorporating advanced glazing elements into more comprehensive facade and building systems in a manner that increases comfort, productivity and amenity for occupants, reduces operating costs for building owners, and contributes to improving the health of the planet by reducing overall energy use and negative environmental impacts. We explore the role of glazing systems in dynamic and responsive facades that provide the following functionality: Enhanced sun protection and cooling load control while improving thermal comfort and providing most of the light needed with daylighting; Enhanced air quality and reduced cooling loads using natural ventilation schemes employing the facade as an active air control element; Reduced operating costs by minimizing lighting, cooling and heating energy use by optimizing the daylighting-thermal tradeoffs; Net positive contributions to the energy balance of the building using integrated photovoltaic systems; Improved indoor environments leading to enhanced occupant health, comfort and performance. In addressing these issues facade system solutions must, of course, respect the constraints of latitude, location, solar orientation, acoustics, earthquake and fire safety, etc. Since climate and occupant needs are dynamic variables, in a high performance building the facade solution have the capacity to respond and adapt to these variable exterior conditions and to changing occupant needs. This responsive performance capability

  16. Precision continuous high-strength Azimuth track for large telescopes

    Science.gov (United States)

    Antebi, Joseph; Kan, Frank W.

    2003-01-01

    A novel track joint was developed for the azimuth track of the 50-m diameter Large Millimeter Telescope (LMT) now under construction in Mexico at an elevation of 4,600 m. The track, which is 430 mm wide by 230 mm deep, must be flat to within +/- 0.3 mm, and the material hardness at least 290 Brinell. This design uses a partial penetration narrow gap groove weld on the top surface of the track and a splice plate welded to the underside of the track. Pre-camber of the joint compensates for weld shrinkage which is small because of the use of the narrow gap groove weld. The residual deviations from flatness are reduced to the required tolerance by adjusting anchor bolts using an optimization procedure. The feasibility of the design with respect to fabrication, strength, fatigue, and alignment was demonstrated by detailed finite element analyses, trial welding and alignment of full scale joints, and testing of the mechanical properties of the joint and adjacent metal.

  17. Interfacial (Fiber-matrix) Properties of High-strength Mortar (150 MPa) from Fiber Pullout

    DEFF Research Database (Denmark)

    Shannag, M.J.; Brincker, Rune; Hansen, Will

    1996-01-01

     The steel fiber-matrix properties of high-strength mortar (150 MPa), such as DSP (densified small particle), are obtained and compared to an ordinary strength mortar (40 MPa) using a specially designed fiber pullout apparatus. A new method for estimating the debonding energy of the interfacial...... DSP mortar has significantly improved interfacial properties compared to ordinary strength mortar. These results are important in the understanding of the role of steel fibers in improving the tensile properties of high-strength, brittle, cement-matrix composites....... zone from the experimental pullout curve is presented. The method is used to separate the areas under the pullout curve corresponding to debonding and friction. The predictions are compared to other methods in the literature. The proposed method seems to provide less variations in the results. The high-strength...

  18. Fatigue experiments on very high strength steel base material and transverse butt welds

    NARCIS (Netherlands)

    Pijpers, R.J.M.; Kolstein, M.H.; Romeijn, A.; Bijlaard, F.S.K.

    2009-01-01

    Very High Strength Steels (VHSS) with nominal strengths up to 1100 MPa have been available on the market for many years. However, the use of these steels in the civil engineering industry is still uncommon, due to lack of design and fabrication knowledge and therefore limited inclusion in codes. Mor

  19. Production of small diameter high-temperature-strength refractory metal wires

    Science.gov (United States)

    Petrasek, D. W.; Signorelli, R. A.; King, G. W.

    1973-01-01

    Special thermomechanical techniques (schedules) have been developed to produce small diameter wire from three refractory metal alloys: colombian base alloy, tantalum base alloy, and tungsten base alloy. High strengths of these wires indicate their potential for contributing increased strength to metallic composites.

  20. Effect of preseason concurrent muscular strength and high-intensity interval training in professional soccer players.

    Science.gov (United States)

    Wong, Pui-lam; Chaouachi, Anis; Chamari, Karim; Dellal, Alexandre; Wisloff, Ulrik

    2010-03-01

    This study examined the effect of concurrent muscular strength and high-intensity running interval training on professional soccer players' explosive performances and aerobic endurance. Thirty-nine players participated in the study, where both the experimental group (EG, n = 20) and control group (CG, n = 19) participated in 8 weeks of regular soccer training, with the EG receiving additional muscular strength and high-intensity interval training twice per week throughout. Muscular strength training consisted of 4 sets of 6RM (repetition maximum) of high-pull, jump squat, bench press, back half squat, and chin-up exercises. The high-intensity interval training consisted of 16 intervals each of 15-second sprints at 120% of individual maximal aerobic speed interspersed with 15 seconds of rest. EG significantly increased (p aerobic speed test, and maximal aerobic speed. High-intensity interval running can be concurrently performed with high load muscular strength training to enhance soccer players' explosive performances and aerobic endurance.

  1. Stress Corrosion Cracking of High-strength Drill Pipe in Sour Gas Well

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi; LI Jing; ZENG Dezhi; HU Junying; HOU Duo; ZHANG Liehui; SHI Taihe

    2014-01-01

    In high sour gas reservoir drilling process, it happens occasionally that high-strength drill pipe suffers brittle fracture failure due to stress corrosion cracking, and poses serious hazard to drilling safety. To solve this problem, this paper studied the stress corrosion cracking mechanism and influencing factors of high-strength drill pipe in sour environment with hydrogen permeation experiments and tensile tests. We simulated practical conditions in laboratory and evaluated the stress corrosion cracking performance of the high-strength drill pipe under conditions of high stress level. For the problems occurring in use of high-strength drill pipe on site, the paper proposed a technical measure for slower stress corrosion cracking.

  2. AISI/DOE Technology Roadmap Program: Characterization of Fatigue and Crash Performance of New Generation High Strength Steels for Automotive Applications

    Energy Technology Data Exchange (ETDEWEB)

    Brenda Yan; Dennis Urban

    2003-04-21

    A 2-year project (2001-2002) to generate fatigue and high strain data for a new generation of high strength steels (HSS) has been completed in December 2002. The project tested eleven steel grades, including Dual Phase (DP) steels, Transformation-Induced Plasticity (TRIP) steels, Bake Hardenable (BH) steels, and conventional High Strength Low Alloy (HSLA) steels. All of these steels are of great interest in automotive industry due to the potential benefit in weight reduction, improved fuel economy, enhanced crash energy management and total system cost savings. Fatigue behavior includes strain controlled fatigue data notch sensitivity for high strength steels. High strain rate behavior includes stress-strain data for strain rates from 0.001/s to 1000/s, which are considered the important strain rate ranges for crash event. The steels were tested in two phases, seven were tested in Phase 1 and the remaining steels were tested in Phase. In a addition to the fatigue data and high st rain rate data generated for the steels studied in the project, analyses of the testing results revealed that Advanced High Strength Steels (AHSS) exhibit significantly higher fatigue strength and crash energy absorption capability than conventional HSS. TRIP steels exhibit exceptionally better fatigue strength than steels of similar tensile strength but different microstructure, for conditions both with or without notches present

  3. A feasibility study of high-strength Bi-2223 conductor for high-field solenoids

    Science.gov (United States)

    Godeke, A.; Abraimov, D. V.; Arroyo, E.; Barret, N.; Bird, M. D.; Francis, A.; Jaroszynski, J.; Kurteva, D. V.; Markiewicz, W. D.; Marks, E. L.; Marshall, W. S.; McRae, D. M.; Noyes, P. D.; Pereira, R. C. P.; Viouchkov, Y. L.; Walsh, R. P.; White, J. M.

    2017-03-01

    We performed a feasibility study on a high-strength Bi{}2-xPb x Sr2Ca2Cu3O{}10-x(Bi-2223) tape conductor for high-field solenoid applications. The investigated conductor, DI-BSCCO Type HT-XX, is a pre-production version of Type HT-NX, which has recently become available from Sumitomo Electric Industries. It is based on their DI-BSCCO Type H tape, but laminated with a high-strength Ni-alloy. We used stress–strain characterizations, single- and double-bend tests, easy- and hard-way bent coil-turns at various radii, straight and helical samples in up to 31.2 T background field, and small 20-turn coils in up to 17 T background field to systematically determine the electro-mechanical limits in magnet-relevant conditions. In longitudinal tensile tests at 77 K, we found critical stress- and strain-levels of 516 MPa and 0.57%, respectively. In three decidedly different experiments we detected an amplification of the allowable strain with a combination of pure bending and Lorentz loading to ≥slant 0.92 % (calculated elastically at the outer tape edge). This significant strain level, and the fact that it is multi-filamentary conductor and available in the reacted and insulated state, makes DI-BSCCO HT-NX highly suitable for very high-field solenoids, for which high current densities and therefore high loads are required to retain manageable magnet dimensions.

  4. HIGH-STRENGTH POLY(METH)ACRYLAMIDE COPOLYMER HYDROGELS

    NARCIS (Netherlands)

    WIERSMA, JA; SOS, M; PENNINGS, AJ

    1994-01-01

    The hydrogels described here are copolymers of acrylamide and methacrylamide highly cross-linked with piperazine diacrylamide or 4,7,10-trioxa-1,13-tridecanediamine diacrylamide by radical polymerisation in highly concentrated aqueous and aqueous gelatin solutions. The hydrogels were characterised b

  5. Corrosion Fatigue of High-Strength Titanium Alloys Under Different Stress Gradients

    Science.gov (United States)

    Baragetti, Sergio; Villa, Francesco

    2015-05-01

    Ti-6Al-4V is the most widely used high strength-to-mass ratio titanium alloy for advanced engineering components. Its adoption in the aerospace, maritime, automotive, and biomedical sectors is encouraged when highly stressed components with severe fatigue loading are designed. The extents of its applications expose the alloy to several aggressive environments, which can compromise its brilliant mechanical characteristics, leading to potentially catastrophic failures. Ti-6Al-4V stress-corrosion cracking and corrosion-fatigue sensitivity has been known since the material testing for pressurized tanks for Apollo missions, although detailed investigations on the effects of harsh environment in terms of maximum stress reduction have been not carried out until recent times. In the current work, recent experimental results from the authors' research group are presented, quantifying the effects of aggressive environments on Ti-6Al-4V under fatigue loading in terms of maximum stress reduction. R = 0.1 axial fatigue results in laboratory air, 3.5 wt.% NaCl solution, and CH3OH methanol solution at different concentrations are obtained for mild notched specimens ( K t = 1.18) at 2e5 cycles. R = 0.1 tests are also conducted in laboratory air, inert environment, 3.5 wt.% NaCl solution for smooth, mild and sharp notched specimens, with K t ranging from 1 to 18.65, highlighting the environmental effects for the different load conditions induced by the specimen geometry.

  6. Lightweight, High Strength Nano-Composite Magnesium for Radiators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Phase I SBIR, Terves will develop processing routes to produce high thermal conductivity magnesium composites for use in heat transfer applications such as...

  7. STUDY ON HIGH WELD STRENGTH OF IMPACT PROPYLENE COPOLYMER/HIGH DENSITY POLYETHYLENE LAMINATES

    Institute of Scientific and Technical Information of China (English)

    Chun-hui Zhang; Rui-fen Chen; Feng Chen; Yong-gang Shangguan; Qiang Zheng; Guo-hua Hu

    2011-01-01

    The impact propylene copolymer (IPC) and isotactic polypropylene (iPP) were separately selected to prepare laminates with high density polyethylene (HDPE) by hot press. The peel forces of IPC/HDPE and iPP/HDPE laminates were examined, and it was found that the welded joint strength in IPC/HDPE laminate was dramatically higher than that of iPP/HDPE laminate. According to the special microstructure of IPC, the co-crystallization of the ethylene segments in ethylene-propylene block copolymer (EbP) component of IPC and the PE chain in HDPE was proposed to explain the highstrength welding. The DSC results indicated that there indeed existed some interaction between IPC and HDPE, and the crystallizable PE component in IPC could affect the crystallization of HDPE. The scanning electron microscope (SEM) observations of IPC/HDPE blends demonstrated that HDPE tended to stay with the PE-rich EbP chains to form the dispersed phase, indicating the good miscibility between HDPE and EbP components of IPC. According to the above results, the effect of co-crystallization of the PE components of theIPC and HDPE on the high weld strength of IPC/HDPE laminate was confirmed.

  8. Advanced Thermomechanical Processing for a High-Mn Austenitic Steel

    Science.gov (United States)

    Kusakin, Pavel; Tsuzaki, Kaneaki; Molodov, Dmitri A.; Kaibyshev, Rustam; Belyakov, Andrey

    2016-12-01

    The microstructures and mechanical properties of a warm-forged and annealed Fe-18Mn-0.6C-1.5Al TWIP steel were studied. The high dislocation density was evolved by warm forging and the ultrafine grains were developed by subsequent annealing. The dislocation strengthening and the grain refinement result in increased yield strength ranging from 500 to 1000 MPa and the product of ultimate tensile strength by total elongation as high as 70,000 MPa pct.

  9. The Spalling of Geopolymer High Strength Concrete Wall Panels and Cylinders Under Hydrocarbon Fire

    Directory of Open Access Journals (Sweden)

    Mohd Ali Ahmad Zurisman

    2016-01-01

    Full Text Available Concrete structures were designed to withstand various types of environment conditions from mild to very severe conditions. Fire represents one of the most severe environmental conditions to which concrete structures may be subjected especially in close conduct structure like tunnel. This paper focuses on the spalling of geopolymer high strength concrete exposed to hydrocarbon fire for minimum 2 hours. From the fire test, geopolymer concrete can be classified as a good fire resistance construction materials based on spalling performance of high strength concrete when exposed to hydrocarbon fire. A maximum of 1% (excluding water moisture loss of spalling recorded for high strength geopolymer concrete wall panel. No explosive spallings were observed for high strength geopolymer concrete.

  10. Poly(acrylamide-MWNTs hybrid hydrogel with extremely high mechanical strength

    Directory of Open Access Journals (Sweden)

    Feng Huanhuan

    2016-01-01

    Full Text Available Poly(acrylamide-multiwalled carbon nanotubes (PAAm-MWNTs hybrid hydrogels were prepared through the radiation-induced polymerization and crosslinking of the aqueous solution of acrylamide and well-dispersed MWNTs for the first time. The PAAm gels obtained by the radiation-induced polymerization and cosslinking showed very high mechanical strengths, and the PAAm-MWNTs hybrid hydrogels had improved mechanical properties compared with the PAAm gels, and hence the PAAm-MWNTs hybrid hydrogels showed extremely high compressive and tensile strengths. The hybrid hydrogels with water contents more than 80 wt.% usually did not fracture even at compressive strengths close to or even more than 60 MPa and strains more than 97%. And the hybrid hydrogels had very high elongations (more than 2000% in some cases, especially when the water content was high. The tensile strengths were in sub-MPa. The hybrid PAAm-MWNTs hydrogel is one of the strongest hydrogel even made.

  11. STRUCTURAL ASPECTS OF PLASTICITY LOWERING OF HIGH-STRENGTH WIRE AT BIG CUMULATIVE COMPRESSIONS

    Directory of Open Access Journals (Sweden)

    V. P. Fetisov

    2012-01-01

    Full Text Available It is shown that decrease of plasticity of high-strength wire at big total cobbings is connected with reduction of mobility of dislocations in the substructure formed at loss of perlite lamellar structure.

  12. A calculation method of cracking moment for the high strength concrete beams under pure torsion

    Indian Academy of Sciences (India)

    Metin Husem; Ertekin Oztekin; Selim Pul

    2011-02-01

    In this study, a method is given to calculate cracking moments of high strength reinforced concrete beams under the effect of pure torsion. To determine the method, both elastic and plastic theories were used. In this method, dimensions of beam cross-section were considered besides stirrup and longitudinal reinforcements. Two plain high strength concrete (without reinforcement) and eight high strength reinforced concrete beams which have two different cross-sections (150 × 250 mm and 150 × 300 mm) were produced to examine the validity of the proposed method. The predictions of the proposed approach for the calculation of the cracking moment of beams under pure torsion were compared with the experimental and the analytical results of previous studies. From these comparisons it is concluded that the predictions of the proposed equations for the cracking moment of plain and reinforced high strength concrete beams under pure torsion are closer to the experimental data compared to the analytical results of previous theories.

  13. ADX: a high field, high power density, Advanced Divertor test eXperiment

    Science.gov (United States)

    Vieira, R.; Labombard, B.; Marmar, E.; Irby, J.; Shiraiwa, S.; Terry, J.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.; ADX Team

    2014-10-01

    The MIT PSFC and collaborators are proposing an advanced divertor experiment (ADX) - a tokamak specifically designed to address critical gaps in the world fusion research program on the pathway to FNSF/DEMO. This high field (6.5 tesla, 1.5 MA), high power density (P/S ~ 1.5 MW/m2) facility would utilize Alcator magnet technology to test innovative divertor concepts for next-step DT fusion devices (FNSF, DEMO) at reactor-level boundary plasma pressures and parallel heat flux densities while producing high performance core plasma conditions. The experimental platform would also test advanced lower hybrid current drive (LHCD) and ion-cyclotron range of frequency (ICRF) actuators and wave physics at the plasma densities and magnetic field strengths of a DEMO, with the unique ability to deploy launcher structures both on the low-magnetic-field side and the high-field side - a location where energetic plasma-material interactions can be controlled and wave physics is most favorable for efficient current drive, heating and flow drive. This innovative experiment would perform plasma science and technology R&D necessary to inform the conceptual development and accelerate the readiness-for-deployment of FNSF/DEMO - in a timely manner, on a cost-effective research platform. Supported by DE-FC02-99ER54512.

  14. High Strength and Wear Resistant Aluminum Alloy for High Temperature Applications

    Science.gov (United States)

    Lee, Jonathan A.; Chen, Po Shou

    2003-01-01

    Originally developed by NASA as high performance piston alloys to meet U.S. automotive legislation requiring low exhaust emission, the novel NASA alloys now offer dramatic increase in tensile strength for many other applications at elevated temperatures from 450 F (232 C) to about 750 F (400 C). It is an ideal low cost material for cast automotive components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. It can be very economically produced from conventional permanent mold, sand casting or investment casting, with silicon content ranging from 6% to 18%. At high silicon levels, the alloy exhibits excellent thermal growth stability, surface hardness and wear resistant properties.

  15. Selection of High Strength Encapsulant for MEMS Devices Undergoing High Pressure Packaging

    CERN Document Server

    Hamzah, A A; Husaini, Y; Majlis, B Y; Ahmad, I

    2008-01-01

    Deflection behavior of several encapsulant materials under uniform pressure was studied to determine the best encapsulant for MEMS device. Encapsulation is needed to protect movable parts of MEMS devices during high pressure transfer molded packaging process. The selected encapsulant material has to have surface deflection of less than 5 ?m under 100 atm vertical loading. Deflection was simulated using CoventorWare ver.2005 software and verified with calculation results obtained using shell bending theory. Screening design was used to construct a systematic approach for selecting the best encapsulant material and thickness under uniform pressure up to 100 atm. Materials considered for this study were polyimide, parylene C and carbon based epoxy resin. It was observed that carbon based epoxy resin has deflection of less than 5 ?m for all thickness and pressure variations. Parylene C is acceptable and polyimide is unsuitable as high strength encapsulant. Carbon based epoxy resin is considered the best encapsula...

  16. Property Evaluation Method Using Spherical Indentation for High-Yield Strength Materials

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Youngsick; Marimuthu, Karuppasamy Pandian; Lee, Hyungyil [Sogang Univ., Seoul (Korea, Republic of); Lee, Jin Haeng [KAERI, Daejeon (Korea, Republic of)

    2015-11-15

    In this paper, we propose a method to evaluate the material properties of high-yield strength materials exceeding 10GPa from spherical indentation. Using a regression equation considering four indentation variables, we map the load displacement relation into a stress-strain relation. To calculate the properties of high-strength materials, we then write a program that produces material properties using the loading / unloading data from the indentation test. The errors in material properties computed by the program are within 0.3, 0.8, and 6.4 for the elastic modulus, yield strength, and hardening coefficient, respectively.

  17. Property evaluation method using spherical indentation for high-yield strength materials

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Young Sick; Marimuthu, Karuppasamy Pandian; Lee, Hyung Yil [Dept. of Mechanical Engineering, Sogang University, Seoul (Korea, Republic of); Lee, Jin Haeng [Reactor Mechanical Engineering Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-11-15

    In this paper, we propose a method to evaluate the material properties of high-yield strength materials exceeding 10 GPa from spherical indentation. Using a regression equation considering four indentation variables, we map the load displacement relation into a stress-strain relation. To calculate the properties of high-strength materials, we then write a program that produces material properties using the loading / unloading data from the indentation test. The errors in material properties computed by the program are within 0.3, 0.8, and 6.4 for the elastic modulus, yield strength, and hardening coefficient, respectively.

  18. Investigation of Phosphate Cement-based Binder with Super High Early Strength for Repair of Concrete

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Magnesium phosphate cement-based binder (MPB) for repair of concrete was prepared by proportionally mixing over burned MgO powder (M) with NHH2PO4 powder (P) and set modifying admixtures. It is characteristic by excellent properties such as rapid setting,high strength and high bond strength to old concrete.. The study is focused on the key factors influencing the setting time and strength of MPB, the bond property of MPB to old concrete and the kinetic feature of the hydration of MPB.

  19. Nanostructured Cu-Cr alloy with high strength and electrical conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Islamgaliev, R. K., E-mail: saturn@mail.rb.ru; Nesterov, K. M. [Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, Ufa 450000 (Russian Federation); Bourgon, J.; Champion, Y. [ICMPE-CNRS, Université Paris 12, 6-8 rue Henri Dunant, 94320 Thiais, cedex (France); Valiev, R. Z. [Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, Ufa 450000 (Russian Federation); Laboratory for Mechanics of Bulk Nanostructured Materials, Saint Petersburg State University, 198504 Peterhof, Saint Petersburg (Russian Federation)

    2014-05-21

    The influence of nanostructuring by high pressure torsion (HPT) on strength and electrical conductivity in the Cu-Cr alloy has been investigated. Microstructure of HPT samples was studied by transmission electron microscopy with special attention on precipitation of small chromium particles after various treatments. Effect of dynamic precipitation leading to enhancement of strength and electrical conductivity was observed. It is shown that nanostructuring leads to combination of high ultimate tensile strength of 790–840 MPa, enhanced electrical conductivity of 81%–85% IACS and thermal stability up to 500 °C. The contributions of grain refinement and precipitation to enhanced properties of nanostructured alloy are discussed.

  20. STIR: Tailored Interfaces for High Strength Composites Across Strain Rates

    Science.gov (United States)

    2013-09-02

    was requested during our kickoff meeting at ARL APG. High performance fabrics including Kevlar, Twaron, Zylon , and Dyneema are used in developing...Kevlar, and Zylon for various pullout rates. Force– displacement data was recorded, and both warp and fill yarns were pulled from the fabric. Their...results presented that the effect of pullout rate is negligible for Kevlar, whereas the effect is bigger on Spectra, and significant for Zylon

  1. Pore pressure development in hybrid fibre-reinforced high strength concrete at elevated temperatures

    OpenAIRE

    Bangi, Mugume Rodgers; HORIGUCHI, Takashi

    2011-01-01

    The present experimental work investigates the build-up of pore pressure at different depths of High Strength Concrete (HSC) and Hybrid-Fibre-Reinforced High Strength Concrete (HFRHSC) when exposed to different heating rates. First, the effect of the measurement technique on maximum pore pressures measured was evaluated. The pressure measurement technique which utilized a sintered metal and silicon oil was found to be the most effective technique for pore pressure measurement. Pore pressure m...

  2. INFLUENCE OF LASER CUTTING ON THE FATIGUE LIMIT OF TWO HIGH STRENGTH STEELS

    OpenAIRE

    Mateo García, Antonio Manuel; Fargas Ribas, Gemma; Calvo Muñoz, Jessica; Roa Rovira, Joan Josep

    2013-01-01

    Laser cutting is widely used in the metal industry, particularly when components of high strength steels sheets are produced. On the other hand, the roughness of cut - edges produced by laser differs from that obt ained by other methods, such as mechanical blank ing, and this fact influence s the fatigue performance. Moreover, thermal effects are another factor to consider. In the present investigation, specimens of two grades of high strength ...

  3. Process of friction-stir welding high-strength aluminum alloy and mechanical properties of joint

    Institute of Scientific and Technical Information of China (English)

    王大勇; 冯吉才; 郭德伦; 孙成彬; 栾国红; 郭和平

    2004-01-01

    The process of friction-stir welding 2A12CZ alloy has been studied. And strength and elongation tests have been performed, which demonstrated that the opportunity existed to manipulate friction-stir welding parameters in order to improve a range of material properties. The results showed that the joint strength and elongation arrived at their parameters changing, joint tensile strength and elongation had similar development. Hardness measurement indicated that the weld was softened. However, there was considerable difference in softening degree for different joint zone. The weld top had lower hardness and wider softening zone than other zone of the weld. And softening zone at advancing side was wider than that at retreating side.

  4. Surface characteristics and mechanical properties of high-strength steel wires in corrosive conditions

    Science.gov (United States)

    Xu, Yang; Li, Shunlong; Li, Hui; Yan, Weiming

    2013-04-01

    Cables are always a critical and vulnerable type of structural components in a long-span cable-stayed bridge in normal operation conditions. This paper presents the surface characteristics and mechanical performance of high-strength steel wires in simulated corrosive conditions. Four stress level (0MPa, 300MPa, 400MPa and 500MPa) steel wires were placed under nine different corrosive exposure periods based on the Salt Spray Test Standards ISO 9227:1990. The geometric feathers of the corroded steel wire surface were illustrated by using fractal dimension analysis. The mechanical performance index including yielding strength, ultimate strength and elastic modulus at different periods and stress levels were tested. The uniform and pitting corrosion depth prediction model, strength degradation prediction model as well as the relationship between strength degradation probability distribution and corrosion crack depth would be established in this study.

  5. Durability and Strength Properties on High Performance Self Compacting Concrete with GGBS and Silica Fumes

    Directory of Open Access Journals (Sweden)

    J. M.Srishaila

    2014-06-01

    Full Text Available This study on the experimental investigation on strength aspects like compressive strength, flexural strength and split tensile strength, and durability aspects like rapid chloride penetration test(RCPT of high performance self-compacting concrete with different mineral admixtures . Initials tests like slump test, L-box test, U-box test and T50 test will be carried out. The methodology adopted here is Ground granulated blast furnace slag (GGBS which is replaced partially by cement at 10%, 20% and 30% and silica fumes(SF by 3%, 6%, 9% in combination with Portland cement and the performance is measured and compared. The influence of mineral admixtures on the workability, mechanical strength and durability aspects of self-compacting concrete are studied. The mix proportion is obtained as per the guidelines given by European Federation of producers and contractors of special products for structure.

  6. Influences of Short Discrete Fibers in High Strength Concrete with Very Coarse Sand

    Directory of Open Access Journals (Sweden)

    Mahyuddin Ramli

    2010-01-01

    Full Text Available Problem statement: High Strength Concrete (HSC normally content high cementitous amount and low water binder ratio. However, these would cause substantial volume changes to the concrete and therefore affected the strength development. In addition, the brittleness of HSC was increased when silica fume used as partial cement replacement to achieve high strength. Approach: This study discussed the effects of incorporated short discrete Coconut Fibers (CF, Barchip Fibers (BF and Glass Fibers (GF into HSC to enhance the performance of concrete while kept the binder content at moderate level. Additional specialty to this HSC was casted with very coarse sand with fineness modulus of 3.98. A total of thirteen mixes were casted and tested for slump, density, compressive strength, flexural strength and ultrasonic pulse velocity in accordance with British Standards. Results: The slump was slightly reduced by the short discrete fibers. All of the fibrous specimens had lower density than control. However, the compressive strength of the HSC had increased from 71.8-79.0 MPa using 1.8% of BF, while flexural strength had increased from 5.21-6.50 MPa. All specimens showed that ultrasonic velocity higher than 4.28 km sec-1. Conclusion/Recommendations: In short, combination of incorporated short discrete fibers and applied very coarse sand to produce HSC showed very satisfying results and improvements. Further assessment on durability and impact resistivity will be verified in the coming research.

  7. On the performance of circular concrete-filled high strength steel columns under axial loading

    Directory of Open Access Journals (Sweden)

    Mohamed Mahmoud El-Heweity

    2012-06-01

    Full Text Available This work presents a numerical study to investigate the performance of circular high-strength steel tubes filled with concrete (CFT under monotonic axial loading. A model is developed to implement the material constitutive relationships and non-linearity. Calibration against previous experimental data shows good agreement. A parametric study is then conducted using the model and compared with codes provisions. Strength and ductility of confined concrete are of primary concern. Variables considered are yield stress of steel tube and column diameter. The assessment of column performance is based on axial load carrying capacities and enhancements of both strength and ductility due to confinement. Two parameters namely strength enhancement factor (Kf and ductility index (μ are clearly defined and introduced for assessment. Results indicate that both concrete strength and ductility of CFT columns are enhanced but to different extents. The ductile behaviors are significantly evident. The increase in yield stress of steel tube has a minimal effect on concrete strength but pronounced effect on concrete ductility. However, reduction in ductility is associated with using high-tensile steel of Grade 70. The overall findings indicate that the use of high-strength tube in CFT columns is not promising. This finding may seriously be considered in seismic design.

  8. Experimental Study on Deterioration Concrete Strength Different Sub-high Temperature Cycles

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Tests were carried out to study the strength deterioration of concrete cooled in air or by water after sub-high temperature at different level and varying with cycles. It is proved that the cross-shaped cracks turned up and extended little by little on the surface of specimen subjected to repeat sub-high temperature, the splitting failure is characterized by cross-shaped cracks after 30 cycles, the concrete strengths decrease rapidly at early stage and to be steady subsequently with the increase of the temperature cycles,the splitting-tensile strength is more sensitive to temperature cycles than the compressive strength, the decline of concrete strength is mainly controlled by the maximum temperature having reached, the ultrasonic velocity in concrete is also declined. On the basis of test results, the mechanisms of sub-high temperature to the strength deterioration of concrete are analyzed.The formulas for calculating the compressive and splitting-tensile strength of concrete relating to the variation of temperature are proposed.

  9. Case studies: low cost, high-strength, large carbon foam tooling

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, R.; Danford, H. [Touchstone Research Laboratory Ltd., Triadelphia, WV (USA)

    2009-01-15

    A new carbon foam tooling system has been developed that results in a low-cost, high-strength material that has been proving attractive for creation of tooling for composite parts. Composites are stronger; lighter and less subject to corrosion and fatigue than materials that are currently used for fabrication of advanced structures. Tools to manufacture these composite parts must be rigid, durable and able to offer a coefficient of thermal expansion (CTE) closely matching that of the composites. Current technology makes it difficult to match the CTE of a composite part in the curing cycle with anything other than a carbon composite or a nickel iron alloy such as Invar. Fabrication of metallic tooling requires many, expensive stages of long duration with a large infrastructure investment. Card ban fiber reinforced polymer resin composite tooling has a shorter lead-time but limited production use because of durability concerns. Coal-based carbon foam material has a compatible CTE and strong durability, that make it an attractive alternative for use in tooling. The use of coal-based carbon foam in tooling for carbon composites is advantageous because of its low cost, light weight, machinability , vacuum integrity and compatibility with a wide range of curing processes. Large-scale tooling case studies will be presented detailing carbon foam's potential for tooling applications.

  10. Behavior of steel fiber-reinforced high-strength concrete at medium strain rate

    Institute of Scientific and Technical Information of China (English)

    Chujie JIAO; Wei SUN; Shi HUAN; Guoping JIANG

    2009-01-01

    Impact compression experiments for the steel fiber-reinforced high-strength concrete (SFRHSC) at medium strain rate were conducted using the split Hopkinson press bar (SHPB) testing method. The volume fractions of steel fibers of SFRHSC were between 0 and 3%. The experimental results showed that, when the strain rate increased from threshold value to 90 s-1, the maximum stress of SFRHSC increased about 30%, the elastic modulus of SFRHSC increased about 50%, and the increase in the peak strain of SFRHSC was 2-3 times of that in the matrix specimen. The strength and toughness of the matrix were improved remarkably because of the superposition effect of the aggregate high-strength matrix and steel fiber high-strength matrix. As a result, under impact loading, cracks developed in the SFRHSC specimen, but the overall shape of the specimen remained virtually unchanged. However, under similar impact loading, the matrix specimens were almost broken into small pieces.

  11. THEORETICAL ASPECTS, EXPERIMENTAL INVESTIGATIONS AND EFFICIENCY IN USAGE OF HIGH-STRENGTH CONCRETE FOR BRIDGE STRUCTURES

    Directory of Open Access Journals (Sweden)

    G. D. Liakhevich

    2014-01-01

    Full Text Available In Belarus concrete with strength up to 60 MPA is used for construction. At the same time high strength concrete with compressive strength above 60 MPA is widely used in all industrially developed countries. High- strength concrete is included in regulatory documents of the European Union and that fact has laid a solid foundation for its application. High strength concrete is produced using highly dispersed silica additives, such as micro-silica and plasticizers (super-plasticizers with a water/cement (w/c ratio not greater than 0.4.Theoretical aspects of high-strength concrete for bridge structures have been studied in the paper. The paper shows a positive impact of highly dispersed additives on structure and physico-mechanical properties of cement compositions, namely: reduction of total porosity of a cement stone in concrete while increasing volumetric concentration and dispersion of a filler; binding of calcium hydroxide with the help of amorphised micro-silica; increased activity of mineral additives during their thin shredding; acceleration of the initial stage of chemical hardening of cement compositions with highly dispersed particle additives that serve as centers of crystallization; “binder-additive” cluster formation due to high surface energy of highly dispersed additive particles; hardening of surface area between a cement stone and aggregates in concrete; high-strength concretes are gaining strength much faster than conventional concretes.Technology of preparation and composition of high-strength concrete using highly dispersed mineral additives and super-plasticizer has been developed in the paper. This concrete will ensure a higher density, wa- ter-and gas tightness, increased resistance to aggressive environment, reduced consumption of concrete and reinforcement, reduced transport and installation weight, increased initial strength, early easing of shutters and preliminary compression, increased length of bridge spans

  12. Exceptional high fatigue strength in Cu-15at.%Al alloy with moderate grain size

    Science.gov (United States)

    Liu, Rui; Tian, Yanzhong; Zhang, Zhenjun; An, Xianghai; Zhang, Peng; Zhang, Zhefeng

    2016-06-01

    It is commonly proposed that the fatigue strength can be enhanced by increasing the tensile strength, but this conclusion needs to be reconsidered according to our study. Here a recrystallized α-Cu-15at.%Al alloy with moderate grain size of 0.62 μm was fabricated by cold rolling and annealing, and this alloy achieved exceptional high fatigue strength of 280 MPa at 107 cycles. This value is much higher than the fatigue strength of 200 MPa for the nano-crystalline counterpart (0.04 μm in grain size) despite its higher tensile strength. The remarkable improvement of fatigue strength should be mainly attributed to the microstructure optimization, which helps achieve the reduction of initial damage and the dispersion of accumulated damage. A new strategy of “damage reduction” was then proposed for fatigue strength improvement, to supplement the former strengthening principle. The methods and strategies summarized in this work offer a general pathway for further improvement of fatigue strength, in order to ensure the long-term safety of structural materials.

  13. Design and fabrication of a metastable β-type titanium alloy with ultralow elastic modulus and high strength

    Science.gov (United States)

    Guo, Shun; Meng, Qingkun; Zhao, Xinqing; Wei, Qiuming; Xu, Huibin

    2015-10-01

    Titanium and its alloys have become the most attractive implant materials due to their high corrosion resistance, excellent biocompatibility and relatively low elastic modulus. However, the current Ti materials used for implant applications exhibit much higher Young’s modulus (50 ~ 120 GPa) than human bone (~30 GPa). This large mismatch in the elastic modulus between implant and human bone can lead to so-called “stress shielding effect” and eventual implant failure. Therefore, the development of β-type Ti alloys with modulus comparable to that of human bone has become an ever more pressing subject in the area of advanced biomedical materials. In this study, an attempt was made to produce a bone-compatible metastable β-type Ti alloy. By alloying and thermo-mechanical treatment, a metastable β-type Ti-33Nb-4Sn (wt. %) alloy with ultralow Young’s modulus (36 GPa, versus ~30 GPa for human bone) and high ultimate strength (853 MPa) was fabricated. We believe that this method can be applied to developing advanced metastable β-type titanium alloys for implant applications. Also, this approach can shed light on design and development of novel β-type titanium alloys with large elastic limit due to their high strength and low elastic modulus.

  14. Phase Transformation in a β-Ti Alloy with Good Balance Between High Strength and High Fracture Toughness

    Institute of Scientific and Technical Information of China (English)

    Li Yang; Wei Qiang; Ma Chaoli; Zheng Lijing; Li Huanxi; Ge Peng; Zhao Yongqing

    2009-01-01

    This article studies the phase transformation of the metastable (-Ti-Al-Mo-V-Cr-Zr alloy (Ti-1300) to disclose the morphological reason for its high strength and high fracture toughness. It has been found that its ultrahigh strength (ultimate tensile strength exceeds 1 400 MPa) owes mainly to the spheroidization of the (-phase, while the high fracture toughness (exceeds 81 MPa·m~(1/2)) to the special lath-shaped (-particles. Compared to the needle-shaped second (-articles, the coarser lath-shaped ones remove the stress concentration at the lath tips and consequently benefit improvement of fracture toughness. The article also describes shape evolution of the (-particles during aging thermodynamically and kinetically, and suggests an optimized aging processing to achieve an ideal balance between high strength and high toughness for this alloy.

  15. Dualism of precipitation morphology in high strength low alloy steel

    Energy Technology Data Exchange (ETDEWEB)

    Chih-Yuan, Chen, E-mail: chen6563@gmail.com [Department of Energy Engineering, National United University, Miaoli 36003, Taiwan (China); Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chien-Chon, Chen [Department of Energy Engineering, National United University, Miaoli 36003, Taiwan (China); Jer-Ren, Yang, E-mail: jryang@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2015-02-25

    While the role of microalloying elements on precipitation strengthening in ferrite matrix during austenite/ferrite transformation is quite clear, some uncertainty still exists concerning the variability of the microhardness distribution of ferrite grains in the isothermal holding condition. The objective of the present study was to clarify the intrinsic characteristics of carbide precipitation morphology in the ferrite matrix under different processing temperatures and times and to correlate it with austenite decomposition kinetics to elucidate why a large microhardness distribution occurs at low isothermal holding temperature. Better understanding of carbide precipitation behavior can help researchers to determine the root cause of variation in microhardness distribution, which would allow metallurgists to produce high quality steels. Measurement with a Vickers hardness indenter revealed that, in specimens isothermally held at 625 °C, the range of Vickers hardness distribution was 240–420 after 5 min of isothermal holding, and 270–340 after 60 min. For specimens isothermally held at 725 °C, the range of Vickers hardness distribution was 200–330 for 5 min of isothermal holding, and 200–250 for 60 min. Therefore, the average microhardness decreased with the isothermal holding temperature and time, and a larger range of distribution occurred with short isothermal holding times. Transmission electron microscopy (TEM) images showed that interface precipitation and random precipitation can occur within the same ferrite grain. The reason is that the austenite decomposition rate varies with transformation temperature and time. An excessively fast austenite/ferrite interface movement velocity, which usually happens in small ferrite grains, would cause these ferrite grains with microalloying elements to exceed their solubility. Furthermore, these microalloying elements will be precipitated randomly after isothermal holding at longer times. Consequently, a large

  16. Grain-refining heat treatments to improve cryogenic toughness of high-strength steels

    Science.gov (United States)

    Rush, H. F.

    1984-01-01

    The development of two high Reynolds number wind tunnels at NASA Langley Research Center which operate at cryogenic temperatures with high dynamic pressures has imposed severe requirements on materials for model construction. Existing commercial high strength steels lack sufficient toughness to permit their safe use at temperatures approaching that of liquid nitrogen (-320 F). Therefore, a program to improve the cryogenic toughness of commercial high strength steels was conducted. Significant improvement in the cryogenic toughness of commercial high strength martensitic and maraging steels was demonstrated through the use of grain refining heat treatments. Charpy impact strength at -320 F was increased by 50 to 180 percent for the various alloys without significant loss in tensile strength. The grain sizes of the 9 percent Ni-Co alloys and 200 grade maraging steels were reduced to 1/10 of the original size or smaller, with the added benefit of improved machinability. This grain refining technique should permit these alloys with ultimate strengths of 220 to 270 ksi to receive consideration for cryogenic service.

  17. Development of high-strength and high-conductivity conductor materials for pulsed high-field magnets at Dresden

    Science.gov (United States)

    Grünberger, W.; Heilmaier, M.; Schultz, L.

    2001-01-01

    The work at the IFW Dresden is focused on the development of microcomposite Cu-Ag alloys and steel-copper macrocomposites with high-nitrogen steel and pearlitic steel jackets, respectively. In Cu-Ag alloys the investigation of continuously cast rods with different starting diameters suggests that the cooling rate during solidification determining the dendrite arm spacing has a minor influence on the development of the strength compared to the cooling velocity after solidification which determines the extent of the Ag-supersaturation in the Cu solid solution. Maximum strength at minimum drawing strain demands (i) a sufficient volume fraction of eutectic in order to suppress discontinuous precipitation (absence of grain boundaries) and (ii) a sufficiently rapid cooling after solidification in order to prevent pre-precipitation. With a continuously cast starting rod of 12 mm diameter a maximum tensile strength of 1.3 GPa was obtained after a drawing strain of only η=4.3. Steel-copper macrocomposites were fabricated by the ‘rod-in-tube’ technology. The experiments with austenitic high-nitrogen steels were performed with two alloys. With the commercial alloy Nicrofer 3033 a strength level of 1.2 GPa has been achieved with a 52 vol% Cu composite at a drawing strain of η=2.3. A composite with pearlitic C60-steel (0.6 wt% C) and 56 vol% Cu showed a tensile strength of 1.53 GPa after a final patenting at a diameter of 14.7 mm and a drawing strain of η=4.

  18. A Model for Determining Strength for Embedded Elliptical Crack in Ultra-high-temperature Ceramics

    Directory of Open Access Journals (Sweden)

    Ruzhuan Wang

    2015-08-01

    Full Text Available A fracture strength model applied at room temperature for embedded elliptical crack in brittle solid was obtained. With further research on the effects of various physical mechanisms on material strength, a thermo-damage strength model for ultra-high-temperature ceramics was applied to each temperature phase. Fracture strength of TiC and the changing trends with elliptical crack shape variations under different temperatures were studied. The study showed that under low temperature, the strength is sensitive to the crack shape variation; as the temperature increases, the sensitivities become smaller. The size of ellipse’s minor axes has great effect on the material strength when the ratio of ellipse’s minor and major axes is lower than 0.5, even under relatively high temperatures. The effect of the minor axes of added particle on material properties thus should be considered under this condition. As the crack area is set, the fracture strength decreases firstly and then increases with the increase of ratio of ellipse’s minor and major axes, and the turning point is 0.5. It suggests that for the added particles the ratio of ellipse’s minor and major axes should not be 0.5. All conclusions significantly coincided with the results obtained by using the finite element software ABAQUS.

  19. Study on the strength of frozen clay at high confining pressure

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An extensive test program was conducted on East China deep clay to investigate mechanical behavior in the process of axial compression and triaxial compression.In addition,the effect of negative temperature and confining pressure on the strength of frozen clay was analyzed.It is concluded that the stress-strain curves at high confining pressure belong to the strain hardening type and its strength almost corresponds to confining pressure in the range of tested confined stress.With respect to temperature,the strength increases when the temperature decreases.

  20. Structural strength analysis and fatigue life prediction of traction converter box in high-speed EMU

    Science.gov (United States)

    Tan, Qin; Li, Qiang

    2017-01-01

    The method of building the FEA model of traction converter box in high-speed EMU and analyzing the static strength and fatigue strength of traction converter box based on IEC 61373-2010 and EN 12663 standards is presented in this paper. The load-stress correlation coefficients of weak points is obtained by FEA model, applied to transfer the load history of traction converter box to stress history of each point. The fatigue damage is calculated based on Miner's rule and the fatigue life of traction converter box is predicted. According to study, the structural strength of traction converter box meets design requirements.

  1. Behaviors of harmonic signals in wavelength-modulated spectroscopy under high absorption strength

    Institute of Scientific and Technical Information of China (English)

    Yuntao Wang; Haiwen Cai; Jianxin Geng; Zhengqing Pan; Dijun Chen; Zujie Fang

    2007-01-01

    @@ Behaviors of harmonic signals in wavelength modulation spectroscopy (WMS) for gas detection with Lorentzian line under high absorption strength are investigated. Approximate analytic expressions of the second, fourth, and sixth harmonics on the strength are presented in concise forms. Simulations show that the expressions are in agreement with the Fourier expansion by numerical integration. It is expected theoretically and experimentally in a WMS system for methane detection that there are not only a maximum, but also a null point in the harmonics versus strength relations, which should be of practical importance in methane sensing applications.

  2. Process study of polycyanate resin for wet-filament wound high-strength composites

    Energy Technology Data Exchange (ETDEWEB)

    Frame, B.J.

    1997-12-31

    Polycyanate (or cyanate ester) resins offer advantages as composite matrices because of their high thermal stability, low outgassing, low water absorption and radiation resistance. This report describes the results of a processing study to develop high-strength hoop-wound composite by the wet-filament winding method using Toray T1000G carbon fiber and YLA RS-14 polycyanate resin as the constituent materials. T1000G/RS-14 composite cylinders were wet-wound and cured using different process schedules and then evaluated for hoop tensile strength and modulus, transverse flexural strength and short beam shear strength. The results of material characterization tests performed on the T1000G carbon fiber and RS-14 resin constituents used in this study are also presented.

  3. Foreword for the special issue of the 7th China-Japan bilateral symposium on high temperature strength of materials

    Institute of Scientific and Technical Information of China (English)

    Shan-Tung TU; Yukio TAKAHASHI

    2011-01-01

    @@ The 7th China-Japan Bilateral Symposium on High Temperature Strength of Materials was held at Dalian, China, during the period August 23-27, 2010.The symposium was co-organized by the High Temperature Strength and Materials Committee, the Society of Materials, Chinese Mechanical Engineering Society and the Committee on High Temperature Strength of Materials, the Society of Materials Science Japan.

  4. Variable amplitude corrosion fatigue and fracture mechanics of weldable high strength jack-up steels

    OpenAIRE

    Etube, L. S.

    1998-01-01

    The tubular welded joints used in the construction of Offshore structures can experience millions of variable amplitude wave induced stress cycles during their operational life. Fatigue has been identified as the main cause of degradation of structural integrity in these structures. As a result, fatigue is an important consideration in their design. Jack-up legs are made from a range of high strength steels with yield strengths up to 70OMPa. These steels are thought to exhib...

  5. Research, Development, and Production of V-N Microalloyed High Strength Rebars for Building in China

    Institute of Scientific and Technical Information of China (English)

    YANG Cai-fu; WANG Quan-li

    2008-01-01

    The research, production, and application of V-N microalloyed high strength rebars in China were reviewed. Enhanced nitrogen in vanadium-containing rebars promotes the precipitation of fine V(C, N) particles, and markedly improves the precipitation strengthening effectiveness of vanadium. Therefore, vanadium added to V-N microalloyed rebars can be reduced by 40% compared to the same strength level of vanadium-containing rebars.

  6. Brittleness Generation Mechanism and Failure Model of High Strength Lightweight Aggregate Concrete

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The brittleness generation mechanism of high strength lightweight aggregate concrete(HSLWAC) was presented, and it was indicated that lightweight aggregate was the vulnerable spot,initiating brittleness. Based on the analysis of the brittleness failure by the load-deflection curve, the brittleness presented by HSLWAC was more prominent compared with ordinary lightweight aggregate concrete of the same strength grade. The model of brittleness failure was also established.

  7. The Parameters Fitting in High-strength Concrete Mix Proportion Experiment

    Institute of Scientific and Technical Information of China (English)

    PAN Hao; LV Lingnu; ZHANG Luo

    2005-01-01

    Parameters that need to be fitted in High-Strength concrete mix proportion experiment and two equation models that are referenced in the experiment are discussed. The reasoning and implement of the corresponding linear fitting algorithm are demonstrated.Parmeter fitting is realized by value estimate method of mathematical statistics.This paper combines mathematical statisitics,linear equations and template thought together successfully and discussed an efficient parameter fitting method based on strength equation model and water consumption equation model.

  8. Development and Performance Evaluation of Very High Early Strength Geopolymer for Rapid Road Repair

    Directory of Open Access Journals (Sweden)

    Abideng Hawa

    2013-01-01

    Full Text Available High early strength is the most important property of pavement repair materials to allow quick reopening to traffic. With this in mind, we have experimentally investigated geopolymers using low cost raw materials available in Thailand. The geopolymer mortar was metakaolin (MK, mixed with parawood ash (PWA, rubberwood ash or oil palm ash (OPA as binder agent. Rubberwood is often used as raw material for biomass power plants in Thailand, especially at latex glove factories and seafood factories, and burning rubberwood generates PWA. Both PWA and OPA are therefore low cost residual waste, locally available in mass quantities. The geopolymer samples were characterized for compressive strength, drying shrinkage, and bond strength to Portland cement mortar with slant shear test. The experimental design varied the contents of PWA and OPA and the heat curing time (1, 2 and 4 h after hot mixture process. The hot mixture process resulted in very high early strength. In addition, we achieved high compressive strengths, low drying shrinkage, and very significant bond strength enhancement by use of the ashes.

  9. Flexural Strength Evaluation of Reinforced Concrete Members with Ultra High Performance Concrete

    Directory of Open Access Journals (Sweden)

    Baek-Il Bae

    2016-01-01

    Full Text Available Flexural strength evaluation models for steel fiber reinforced ultra high strength concrete were suggested and evaluated with test results. Suggested flexural strength models were composed of compression stress blocks and tension stress blocks. Rectangular stress block, triangular stress block, and real distribution shape of stress were used on compression side. Under tension, rectangular stress block distributed to whole area of tension side and partial area of tension side was used. The last model for tension side is realistic stress distribution. All these models were verified with test result which was carried out in this study. Test was conducted by four-point loading with 2,000 kN actuator for slender beam specimen. Additional verifications were carried out with previous researches on flexural strength of steel fiber reinforced concrete or ultra high strength concrete. Total of 21 test specimens were evaluated. As a result of comparison for flexural strength of section, neutral axis depth at ultimate state, models with triangular compression stress block, and strain-softening type tension stress block can be used as exact solution for ultra high performance concrete. For the conservative and convenient design of section, modified rectangular stress block model can be used with strain softening type tension stress block.

  10. Microstructure and Mechanical Properties in Hot-Rolled Extra High-Yield-Strength Steel Plates for Offshore Structure and Shipbuilding

    Science.gov (United States)

    Liu, Dongsheng; Li, Qingliang; Emi, Toshihiko

    2011-05-01

    Key parameters for a thermomechanically controlled processing and accelerated cooling process (TMCP-AcC) were determined for integrated mass production to produce extra high-yield-strength microalloyed low carbon SiMnCrNiCu steel plates for offshore structure and bulk shipbuilding. Confocal scanning microscopy was used to make in-situ observations on the austenite grain growth during reheating. A Gleeble 3800 thermomechanical simulator was employed to investigate the flow stress behavior, static recrystallization (SRX) of austenite, and decomposition behavior of the TMCP conditioned austenite during continuous cooling. The Kocks-Mecking model was employed to describe the constitutive behavior, while the Johnson-Mehl-Avrami-Kolmogorov (JMAK) approach was used to predict the SRX kinetics. The effects of hot rolling schedule and AcC on microstructure and properties were investigated by test-scale rolling trials. The bridging between the laboratory observations and the process parameter determination to optimize the mass production was made by integrated industrial production trials on a set of a 5-m heavy plate mill equipped with an accelerated cooling system. Successful production of 60- and 50-mm-thick plates with yield strength in excess of 460 MPa and excellent toughness at low temperature (213 K (-60 °C)) in the parent metal and the simulated coarse-grained heat affected zone (CGHAZ) provides a useful integrated database for developing advanced high-strength steel plates via TMCP-AcC.

  11. Evaluation of the stress corrosion cracking resistance of several high strength low alloy steels

    Science.gov (United States)

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

    1980-01-01

    The stress corrosion cracking resistance was studied for high strength alloy steels 4130, 4340, for H-11 at selected strength levels, and for D6AC and HY140 at a single strength. Round tensile and C-ring type specimens were stressed up to 100 percent of their yield strengths and exposed to alternate immersion in salt water, salt spray, the atmosphere at Marshall Space Flight Center, and the seacoast at Kennedy Space Center. Under the test conditions, 4130 and 4340 steels heat treated to a tensile strength of 1240 MPa (180 ksi), H-11 and D6AC heat treated to a tensile strength of 1450 MPa (210 ksi), and HY140 (1020 MPa, 148 ksi) are resistant to stress corrosion cracking because failures were not encountered at stress levels up to 75 percent of their yield strengths. A maximum exposure period of one month for alternate immersion in salt water or salt spray and three months for seacoast is indicated for alloy steel to avoid false indications of stress corrosion cracking because of failure resulting from severe pitting.

  12. Effects of Quenching Process on Mechanical Properties and Microstructure of High Strength Steel

    Institute of Scientific and Technical Information of China (English)

    DUAN Zhengtao; LI Yanmei; ZHANG Mingya; SHI Minghan; ZHU Fuxian; ZHANG Shunhu

    2012-01-01

    The effects of direct quenching and tempering (DQ-T) process and conventional reheat quenching and tempering (RQ-T) processes on mechanical properties and microstructure of high strength steel were investigated.The DQ process was found to enhance the hardenability of steel effectively.The tensile strength and yield strength of DQ specimen was 975 MPa and 925 MPa respectively,which were higher than those of RQ specimen's of 920 MPa and 871 MPa.In contrast,low temperature toughness (-40 ℃,AKV) of DQ-T specimen (124 J) was generally inferior to that of RQ-T specimen (156 J).The direct quenching temperature was one of the potential process parameters to determine strength/toughness balance of steel manufactured by DQ process.The experimental results showed that excellent strength/toughness balance was obtained when the specimens was quenched at temperature in the range of 850-910 ℃.The yield strength and impact energy (-40 ℃) of DQ steel decreased significantly with increasing of quenching temperature,although the tensile strength was nearly stable.

  13. Quantitative design of regulatory elements based on high-precision strength prediction using artificial neural network.

    Science.gov (United States)

    Meng, Hailin; Wang, Jianfeng; Xiong, Zhiqiang; Xu, Feng; Zhao, Guoping; Wang, Yong

    2013-01-01

    Accurate and controllable regulatory elements such as promoters and ribosome binding sites (RBSs) are indispensable tools to quantitatively regulate gene expression for rational pathway engineering. Therefore, de novo designing regulatory elements is brought back to the forefront of synthetic biology research. Here we developed a quantitative design method for regulatory elements based on strength prediction using artificial neural network (ANN). One hundred mutated Trc promoter & RBS sequences, which were finely characterized with a strength distribution from 0 to 3.559 (relative to the strength of the original sequence which was defined as 1), were used for model training and test. A precise strength prediction model, NET90_19_576, was finally constructed with high regression correlation coefficients of 0.98 for both model training and test. Sixteen artificial elements were in silico designed using this model. All of them were proved to have good consistency between the measured strength and our desired strength. The functional reliability of the designed elements was validated in two different genetic contexts. The designed parts were successfully utilized to improve the expression of BmK1 peptide toxin and fine-tune deoxy-xylulose phosphate pathway in Escherichia coli. Our results demonstrate that the methodology based on ANN model can de novo and quantitatively design regulatory elements with desired strengths, which are of great importance for synthetic biology applications.

  14. Fatigue in Welded High-Strength Steel Plate Elements under Stochastic Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning; Petersen, R.I.; Martinez, L. Lopez

    1999-01-01

    The present project is a part of an investigation on fatigue in offshore structures in high-strength steel. The fatigue life of plate elements with welded attachments is studied. The material used has a yield stress of ~ 810-840 MPa, and high weldability and toughness properties. Fatigue test...... series with constant amplitude loading and with various types of stochastic loading have been carried through on test specimens in high-strength steel, and - for a comparison - on test specimens in conventional offshore structural steel with a yield stress of ~ 400-410 MPa.A comparison between constant...... amplitude and variable amplitude fatigue test results shows shorter fatigue lives in variable amplitude loading than should be expected from the linear fatigue damage accumulation formula. Furthermore, in general longer fatigue lives were obtained for the test specimens in high-strength steel than those...

  15. An investigation on fatigue in high-strength steel offshore structures

    DEFF Research Database (Denmark)

    Agerskov, Henning; Petersen, R.I.; Martinez, L. Lopez

    1998-01-01

    The fatigue life of offshore steel structures in high-strength steel is studied. The material used has a yield stress of 800-1000 MPa and high weldability and toughness properties. Of special interest is the fatigue life under a realistic stochastic loading. In the experimental part...... of the investigation, fatigue test series were carried out on both full scale tubular joints and smaller welded plate test specimens in high-strength steel as well as in conventional offshore structural steel. This paper gives a summary of the main results presented in two recent research reports [15, 16], from...... specimens in high-strength steel than those obtained in corresponding tests on joints in conventional offshore structural steel....

  16. An Investigation on Fatigue in High-Strength Steel Offshore Structures

    DEFF Research Database (Denmark)

    Agerskov, Henning; Petersen, R.I.; Lopez Martinez, L.

    1997-01-01

    In the present investigation, the fatigue life of offshore steel structures in high-strength steel is studied. The material used has a yield stress of 800-1000 MPa, and high weldability and toughness properties. Of special interest is the fatigue life under a realistic stochastic loading....... In the experimental part of the investigation, fatigue test series have been carried through on both full-scale tubular joints and smaller welded plate test specimens, in high-strength steel as well as in conventional offshore structural steel. The present document gives a summary of the main results presented in two......, in general longer fatigue lives were obtained for the test specimens in high-strength steel than those obtained in corresponding tests on joints in conventional offshore structural steel....

  17. Laser beam welding of new ultra-high strength and supra-ductile steels

    Science.gov (United States)

    Dahmen, Martin

    2015-03-01

    Ultra-high strength and supra-ductile are entering fields of new applications. Those materials are excellent candidates for modern light-weight construction and functional integration. As ultra-high strength steels the stainless martensitic grade 1.4034 and the bainitic steel UNS 53835 are investigated. For the supra-ductile steels stand two high austenitic steels with 18 and 28 % manganese. As there are no processing windows an approach from the metallurgical base on is required. Adjusting the weld microstructure the Q+P and the QT steels require weld heat treatment. The HSD steel is weldable without. Due to their applications the ultra-high strength steels are welded in as-rolled and strengthened condition. Also the reaction of the weld on hot stamping is reflected for the martensitic grades. The supra-ductile steels are welded as solution annealed and work hardened by 50%. The results show the general suitability for laser beam welding.

  18. High-strength bioresorbable Fe-Ag nanocomposite scaffolds: Processing and properties

    Science.gov (United States)

    Sharipova, Aliya; Psakhie, Sergey G.; Swain, Sanjaya K.; Gutmanas, Elazar Y.; Gotman, Irena

    2015-10-01

    High strength ductile iron-silver nanocomposite scaffolds were fabricated employing high energy attrition milling of micron-submicron powders, followed by cold sintering/high pressure consolidation. Particulate leaching method with soluble Na2SO4 and K2CO3 salts as porogens was used to create scaffolds with 50, 55, 60 and 73% volume fraction of pores. Part of specimens was annealed at 600, 800 and 900°C. Specimens were characterized employing X-ray diffraction, scanning electron microscopy (SEM) with electron probe microanalysis (EDS) and high resolution SEM. Mechanical properties were measured in compression and permeability was measured in permeameter based on Darcy's law. Scaffolds with 50% and 55% porosity exhibited high compressive strength (18-22 MPa), compressive strength of 8-12 MPa was observed for scaffolds with 73% porosity. Treatments at 800 and 900°C result in increase of strength and ductility with some coarsening of microstructure. Best combination of compressive strength (15 MPa) and permeability (0.6-6 cm2) is close to the range of trabecular bone.

  19. High-strength bioresorbable Fe–Ag nanocomposite scaffolds: Processing and properties

    Energy Technology Data Exchange (ETDEWEB)

    Sharipova, Aliya [Department of Materials Science and Technology, Techion-Israel Institute of Technology, Haifa, 32000 Israel (Israel); Skolkovo Institute of Science and Technology, Skolkovo, 143025 (Russian Federation); Psakhie, Sergey G. [Skolkovo Institute of Science and Technology, Skolkovo, 143025 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Swain, Sanjaya K. [Department of Materials Science and Technology, Techion-Israel Institute of Technology, Haifa, 32000 Israel (Israel); Gutmanas, Elazar Y., E-mail: gutmanas@technion.ac.il; Gotman, Irena [Department of Materials Science and Technology, Techion-Israel Institute of Technology, Haifa, 32000 Israel (Israel); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    High strength ductile iron-silver nanocomposite scaffolds were fabricated employing high energy attrition milling of micron-submicron powders, followed by cold sintering/high pressure consolidation. Particulate leaching method with soluble Na{sub 2}SO{sub 4} and K{sub 2}CO{sub 3} salts as porogens was used to create scaffolds with 50, 55, 60 and 73% volume fraction of pores. Part of specimens was annealed at 600, 800 and 900°C. Specimens were characterized employing X-ray diffraction, scanning electron microscopy (SEM) with electron probe microanalysis (EDS) and high resolution SEM. Mechanical properties were measured in compression and permeability was measured in permeameter based on Darcy’s law. Scaffolds with 50% and 55% porosity exhibited high compressive strength (18–22 MPa), compressive strength of 8–12 MPa was observed for scaffolds with 73% porosity. Treatments at 800 and 900°C result in increase of strength and ductility with some coarsening of microstructure. Best combination of compressive strength (15 MPa) and permeability (0.6{sup −6} cm{sup 2}) is close to the range of trabecular bone.

  20. Experimental Analysis of the Feasibility of Shaving Process Applied for High-Strength Steel Sheets

    Directory of Open Access Journals (Sweden)

    Wiriyakorn Phanitwong

    2016-01-01

    Full Text Available In recent years, the engineered materials were developed to improve their mechanical properties. A high-strength steel sheet is one of them, developed to serve the requirement of reducing weight of vehicles. Therefore, as a new material, many researches have been carried out to examine the use of sheet metal forming process applied for high-strength steel sheet. However, the feasibility of shaving process applied for it has not been investigated yet. In the present study, this feasibility was revealed by using experiments on two types of high-strength steel sheets: SAPH 440 and SPFH 590Y (JIS. The relationship between shaved surface feature and shearing clearance of high-strength steel sheets corresponded well with those of their conventional metal sheets. However, due to the high ultimate strength of these materials, it was revealed in this present study that there were not any suitable conditions of shaving process that could be applied to achieve the requirements of smooth cut surface overall material thickness.

  1. Achieving high strength and high ductility in magnesium alloy using hard-plate rolling (HPR) process.

    Science.gov (United States)

    Wang, Hui-Yuan; Yu, Zhao-Peng; Zhang, Lei; Liu, Chun-Guo; Zha, Min; Wang, Cheng; Jiang, Qi-Chuan

    2015-11-25

    Magnesium alloys are highly desirable for a wide range of lightweight structural components. However, rolling Mg alloys can be difficult due to their poor plasticity, and the strong texture yielded from rolling often results in poor plate forming ability, which limits their further engineering applications. Here we report a new hard-plate rolling (HPR) route which achieves a large reduction during a single rolling pass. The Mg-9Al-1Zn (AZ91) plates processed by HPR consist of coarse grains of 30-60 μm, exhibiting a typical basal texture, fine grains of 1-5 μm and ultrafine (sub) grains of 200-500 nm, both of the latter two having a weakened texture. More importantly, the HPR was efficient in gaining a simultaneous high strength and uniform ductility, i.e., ~371 MPa and ~23%, respectively. The superior properties should be mainly attributed to the cooperation effect of the multimodal grain structure and weakened texture, where the former facilitates a strong work hardening while the latter promotes the basal slip. The HPR methodology is facile and effective, and can avoid plate cracking that is prone to occur during conventional rolling processes. This strategy is applicable to hard-to-deform materials like Mg alloys, and thus has a promising prospect for industrial application.

  2. Novel high T{sub g} high-strength poly(aryl ether)s

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, S.; Maier, G. [Technische Univ. Muenchen, Garching (Germany). Lehrstuhl fuer Makromolekulare Stoffe

    1999-08-01

    A novel 2-perfluoroalkyl-activated bisfluoro monomer has been synthesized successfully using a Pd(0)-catalyzed cross-coupling reaction of 4-fluoro-3-trifluoromethyl phenyl boronic acid with 4,4{prime}-dibromodiphenylbenzene. This monomer was converted to novel poly(aryl ether)s by nucleophilic displacement of the fluorine atoms on the benzene ring with several bisphenols. The products obtained by displacement of the fluorine atoms exhibit weight average molar masses up to 1.06 {times} 10{sup 5} g/mol in GPC. These poly(aryl ether)s showed outstanding thermooxidative stability up to 534 C for 5% weight loss in TGA under synthetic air and high glass transition temperatures (T{sub g}) even up to 300 C in DSC and DMTA. These polymers are soluble in a wide range of organic solvents, e.g., CHCl{sub 3}, THF, NMP, DMF, toluene, etc., and are insoluble in DMSO and acetone. Transparent thin films of these polymers cast from DMF exhibited tensile strengths up to 115 MPa, moduli up to 2.59 GPa, and elongations up to 120% depending on their exact repeating unit structures. These values are comparable to those of high performance thermoplastic materials such as PEEK or Ultem PEI.

  3. Novel high T[sub g] high-strength poly(aryl ether)s

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, S.; Maier, G. (Technische Univ. Muenchen, Garching (Germany). Lehrstuhl fuer Makromolekulare Stoffe)

    1999-08-01

    A novel 2-perfluoroalkyl-activated bisfluoro monomer has been synthesized successfully using a Pd(0)-catalyzed cross-coupling reaction of 4-fluoro-3-trifluoromethyl phenyl boronic acid with 4,4[prime]-dibromodiphenylbenzene. This monomer was converted to novel poly(aryl ether)s by nucleophilic displacement of the fluorine atoms on the benzene ring with several bisphenols. The products obtained by displacement of the fluorine atoms exhibit weight average molar masses up to 1.06 [times] 10[sup 5] g/mol in GPC. These poly(aryl ether)s showed outstanding thermooxidative stability up to 534 C for 5% weight loss in TGA under synthetic air and high glass transition temperatures (T[sub g]) even up to 300 C in DSC and DMTA. These polymers are soluble in a wide range of organic solvents, e.g., CHCl[sub 3], THF, NMP, DMF, toluene, etc., and are insoluble in DMSO and acetone. Transparent thin films of these polymers cast from DMF exhibited tensile strengths up to 115 MPa, moduli up to 2.59 GPa, and elongations up to 120% depending on their exact repeating unit structures. These values are comparable to those of high performance thermoplastic materials such as PEEK or Ultem PEI.

  4. Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels

    Science.gov (United States)

    Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

    2017-01-01

    Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400–450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0–1.2 GPa at room temperature, which is nearly 3–5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry. PMID:28150692

  5. High efficient preparation of carbon nanotube-grafted carbon fibers with the improved tensile strength

    Science.gov (United States)

    Fan, Wenxin; Wang, Yanxiang; Wang, Chengguo; Chen, Jiqiang; Wang, Qifen; Yuan, Yan; Niu, Fangxu

    2016-02-01

    An innovative technique has been developed to obtain the uniform catalyst coating on continuously moving carbon fibers. Carbon nanotube (CNT)-grafted carbon fibers with significantly improved tensile strength have been succeeded to produce by using chemical vapor deposition (CVD) when compared to the tensile strength of untreated carbon fibers. The critical requirements for preparation of CNT-grafted carbon fibers with high tensile strength have been found, mainly including (i) the obtainment of uniform coating of catalyst particles with small particle size, (ii) the low catalyst-induced and mechano-chemical degradation of carbon fibers, and (iii) the high catalyst activity which could facilitate the healing and strengthening of carbon fibers during the growth of CNTs. The optimum growth temperature was found to be about 500 °C, and the optimum catalyst is Ni due to its highest activity, there is a pronounced increase of 10% in tensile strength of carbon fibers after CNT growth at 500 °C by using Ni catalyst. Based on the observation from HRTEM images, a healing and crosslink model of neighboring carbon crystals by CNTs has been formulated to reveal the main reason that causes an increase in tensile strength of carbon fibers after the growth of CNTs. Such results have provided the theoretical and experimental foundation for the large-scale preparation of CNT-grafted carbon fibers with the improved tensile strength, significantly promoting the development of CNT-grafted carbon fiber reinforced polymer composites.

  6. Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels.

    Science.gov (United States)

    Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

    2017-02-02

    Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400-450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0-1.2 GPa at room temperature, which is nearly 3-5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry.

  7. Correlation of metrological surface parameters to the strength of advanced ceramics

    Science.gov (United States)

    Burra, Vishal

    Surface topography greatly influences not only the mechanical and physical properties of contacting parts, but also the optical and coating properties of contacting components. The characteristics of surface topography in amplitude, spatial distribution and pattern of surface features dominate the functional applications in the field of wear, friction, lubrication, fatigue, sealing, joining, reflecting, painting, etc. Although surface roughness data from a stylus profilometer continues to be of basic importance, it does suffer from some limitations which cannot be overlooked. Some of the major limitations of using a stylus profilometer are finite tip radius, inability to record detailed information, bouncing of stylus tip and losing contact with surface, the stylus might create scratches as it passes over the surface, and long time when acquiring data. Alternatively, optical interferometry has, for a number of decades, been used to measure surface topography successfully. As a result there are many commercial interferometric instruments based on two or multi-beam interferometerss instruments available today. The goal of this thesis is to continue to work on the development of a novel method that can obtain the topography of surfaces utilizing advanced digital moire. In the version under development a grating printed on a glass plate will be utilized to generate fringes. The HoloStrain software is utilized to process the fringe pattern information. The main objective of the thesis is to apply this methodology to measuring the surface roughness of ceramics that have been modified via laser-assisted machining. This research will enable further development of the laser-assisted machining process by making it feasible to optimize the surface profile of the ceramic through changing processing parameters.

  8. Connections in Precast Buildings using Ultra High-Strength Fibre Reinforced Concrete

    DEFF Research Database (Denmark)

    Hansen, Lars Pilegaard

    1995-01-01

    Ultra high-strength concrete adds new dimensions to the design of concrete structures. It is a brittle material but introducing fibres into the matrix changes the material into a highly ductile material. Furthermore, the fibre reinforcement increases the anchorage of traditional reinforcement bars...

  9. The behavior of high-strength unidirectional composites under tension with superposed hydrostatic pressure

    NARCIS (Netherlands)

    Zinoviev, P.A.; Tsvetkov, S.V.; Kulish, G.G.; Berg, van den R.W.; Schepdael, van L.J.M.M.

    2001-01-01

    Three types of high-strength unidirectional composite materials were studied under longitudinal tension with superposed high hydrostatic pressure. Reinforcing fibers were T1000G carbon, S2 glass and Zylon PBO fibers; the Ciba 5052 epoxy resin was used as matrix. The composites were tested under exte

  10. Corrosion Resistance of High Strength Concrete Containing Palm Oil Fuel Ash as Partial Cement Replacement

    Directory of Open Access Journals (Sweden)

    F. Mat Yahaya

    2014-06-01

    Full Text Available This experimental work investigates the influence of POFA as partial cement replacement towards corrosion resistance of high strength concrete. Plain high strength concrete (P0 with 100% ordinary Portland cement (control specimen and POFA high strength concrete containing POFA as partial cement replacement material were used. At the first stage, mix with 20% POFA (P20 has been identified as the best performing mix after cubes (150×150×150 mm containing various content of POFA as partial cement replacement were prepared, continuously water cured and subjected to compressive strength test at 28 days. At the second stage of study, control specimen (P0 and high strength concrete mix containing 20% POFA (P20 were prepared in form of cylinders with reinforcement bar buried in the middle for corrosion resistance test. Specimens were subjected to half cell potential technique following the procedures outlined in ASTM C876 (1994. Incorporation of POFA as partial cement replacement has contributed to densification of microstructure making the concrete denser thus exhibit higher resistance towards corrosion as compared to plain concrete.

  11. Internal Curing Using Water-releasing Material for High Strength Micro-expansive Concrete

    Institute of Scientific and Technical Information of China (English)

    LU Linnu; YANG Wen; HE Yongjia; WU Jing; HU Shuguang

    2009-01-01

    Due to its low water content,it is difficult for expansive agent to have an effective expansive effect on high strength concrete to compensate its extensive shrinkage and form a certain expansion.To solve this problem,water-releasing material with water storage and releasing characteristics was incorporated into high strength micro-expansive concrete to provide internal curing,and expansive effect of expansive agent was improved.Migration of water from initially saturated water-releasing material to the surrounding hydrating cement paste was investigated.Based on a given efficient diffusion distance of water stored in water-releasing material,the mass and real water-cement ratio of cured cement paste were estimated.At the same time,the effect of internal curing of water-releasing material on the volume deformation of high strength micro-expansive concrete was investigated.

  12. Structural Behavior of Continuous Prestressed Steel Fiber Reinforced High Strength Concrete Beam

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The flexural behaviors of continuous fully and partially prestressed steel fiber reinforced high strength concrete beams are studied by experiment and nonlinear finite element analysis. Three levels of partial prestress ratio (PPR) are considered, and three pairs of two-span continuous beams with box sections varying in size are designed. The major parameters involved in the study include the PPR and the fiber location. It is concluded that the prestressed high strength concrete beam exhibits satisfactory ductility; the influences of steel fiber on the crack behaviors for partially prestressed beams are not as obvious as those for fully prestressed ones; steel fibers can improve the structural stiffness after cracking for fully prestressed high strength concrete beams; the moment redistribution from mid-span to intermediate support in the first stage should be mainly considered in practical design.

  13. Crack formation and fracture energy of normal and high strength concrete

    Indian Academy of Sciences (India)

    F H Wittmann

    2002-08-01

    The crack path through composite materials such as concrete depends on the mechanical interaction of inclusions with the cement-based matrix. Fracture energy depends on the deviations of a real crack from an idealized crack plane. Fracture energy and strain softening of normal, high strength, and self-compacting concrete have been determined by means of the wedge splitting test. In applying the numerical model called “numerical concrete” crack formation in normal and high strength concrete is simulated. Characteristic differences of the fracture process can be outlined. Finally results obtained are applied to predict shrinkage cracking under different boundary conditions. Crack formation of high strength concrete has to be seriously controlled in order to achieve the necessary durability of concrete structures.

  14. Comparison of Post Weld Treatment of High Strength Steel Welded Joints in Medium Cycle Fatigue

    DEFF Research Database (Denmark)

    Pedersen, Mikkel Melters; Mouritsen, Ole Ø.; Hansen, Michael Rygaard

    2010-01-01

    the stress range can exceed the yield-strength of ordinary structural steel, especially when considering positive stress ratios (R > 0). Fatigue experiments and qualitative evaluation of the different post-weld treatments leads to the selection of TIG dressing. The process of implementing TIG dressing......This paper presents a comparison of three post-weld treatments for fatigue life improvement of welded joints. The objective is to determine the most suitable post-weld treatment for implementation in mass production of certain crane components manufactured from very high-strength steel....... The processes investigated are: burr grinding, TIG dressing and ultrasonic impact treatment. The focus of this investigation is on the so-called medium cycle area, i.e. 10 000-500 000 cycles and very high stress ranges. In this area of fatigue design, the use of very high strength steel becomes necessary, since...

  15. Design of the Advanced High Kinetic Energy Launch System

    Science.gov (United States)

    1982-08-01

    of 41,800 psi. ASTM 574 A516 steel was used for the dome because it is easy to shape and is readily weldable . ASTM A572, Grade 60 is classified as...stirrups were used at 12 or 14 inches, as required. The reinforcement used was ASTM A615 , Grade 60 except for the stirrups for which Grade 40 was used...a high strength, low alloy structural steel and was used for its availability, high strength, and weldability for the rest of the structure. The

  16. Advanced High Efficiency Durable DACS Thruster Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Systima is developing a high performance 25 lbf DACS thruster that operates with a novel non-toxic monopropellant. The monopropellant has a 30% higher...

  17. Research on spring-back behavior of high strength steel sheets

    Institute of Scientific and Technical Information of China (English)

    Zhang Junping; Fang Gang; Ma Mingtu; Jin Qingsheng

    2014-01-01

    To investigate the spring-back behavior of dual-phase (DP) steel,V-shape spring-back experiments with different bending angles,relative bending radii and blank holding forces were carried out in this paper. It is concluded that with the increase of V-shape angle or blank holding force,the spring-back of DP steel sheets de-creases;while raising fillet radius of punch,which has the most apparent effects on spring-back,advances spring-back angle. Among DP590,DP780 and DP980,higher strength yields more notable spring-back due to larger elastic deformation. The difference of spring-back among these materials is relevant with the microstruc-ture and mechanical properties. The total elastic deformation approximately equals the ratio of the strength corre-sponding to the applied load to the modulus of elasticity.

  18. Advanced Diagnostics for High Pressure Spray Combustion.

    Energy Technology Data Exchange (ETDEWEB)

    Skeen, Scott A.; Manin, Julien Luc; Pickett, Lyle M.

    2014-06-01

    The development of accurate predictive engine simulations requires experimental data to both inform and validate the models, but very limited information is presently available about the chemical structure of high pressure spray flames under engine- relevant conditions. Probing such flames for chemical information using non- intrusive optical methods or intrusive sampling techniques, however, is challenging because of the physical and optical harshness of the environment. This work details two new diagnostics that have been developed and deployed to obtain quantitative species concentrations and soot volume fractions from a high-pressure combusting spray. A high-speed, high-pressure sampling system was developed to extract gaseous species (including soot precursor species) from within the flame for offline analysis by time-of-flight mass spectrometry. A high-speed multi-wavelength optical extinction diagnostic was also developed to quantify transient and quasi-steady soot processes. High-pressure sampling and offline characterization of gas-phase species formed following the pre-burn event was accomplished as well as characterization of gas-phase species present in the lift-off region of a high-pressure n-dodecane spray flame. For the initial samples discussed in this work several species were identified, including polycyclic aromatic hydrocarbons (PAH); however, quantitative mole fractions were not determined. Nevertheless, the diagnostic developed here does have this capability. Quantitative, time-resolved measurements of soot extinction were also accomplished and the novel use of multiple incident wavelengths proved valuable toward characterizing changes in soot optical properties within different regions of the spray flame.

  19. ADX: a high field, high power density, advanced divertor and RF tokamak

    Science.gov (United States)

    LaBombard, B.; Marmar, E.; Irby, J.; Terry, J. L.; Vieira, R.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.; Baek, S.; Beck, W.; Bonoli, P.; Brunner, D.; Doody, J.; Ellis, R.; Ernst, D.; Fiore, C.; Freidberg, J. P.; Golfinopoulos, T.; Granetz, R.; Greenwald, M.; Hartwig, Z. S.; Hubbard, A.; Hughes, J. W.; Hutchinson, I. H.; Kessel, C.; Kotschenreuther, M.; Leccacorvi, R.; Lin, Y.; Lipschultz, B.; Mahajan, S.; Minervini, J.; Mumgaard, R.; Nygren, R.; Parker, R.; Poli, F.; Porkolab, M.; Reinke, M. L.; Rice, J.; Rognlien, T.; Rowan, W.; Shiraiwa, S.; Terry, D.; Theiler, C.; Titus, P.; Umansky, M.; Valanju, P.; Walk, J.; White, A.; Wilson, J. R.; Wright, G.; Zweben, S. J.

    2015-05-01

    The MIT Plasma Science and Fusion Center and collaborators are proposing a high-performance Advanced Divertor and RF tokamak eXperiment (ADX)—a tokamak specifically designed to address critical gaps in the world fusion research programme on the pathway to next-step devices: fusion nuclear science facility (FNSF), fusion pilot plant (FPP) and/or demonstration power plant (DEMO). This high-field (⩾6.5 T, 1.5 MA), high power density facility (P/S ˜ 1.5 MW m-2) will test innovative divertor ideas, including an ‘X-point target divertor’ concept, at the required performance parameters—reactor-level boundary plasma pressures, magnetic field strengths and parallel heat flux densities entering into the divertor region—while simultaneously producing high-performance core plasma conditions that are prototypical of a reactor: equilibrated and strongly coupled electrons and ions, regimes with low or no torque, and no fuelling from external heating and current drive systems. Equally important, the experimental platform will test innovative concepts for lower hybrid current drive and ion cyclotron range of frequency actuators with the unprecedented ability to deploy launch structures both on the low-magnetic-field side and the high-magnetic-field side—the latter being a location where energetic plasma-material interactions can be controlled and favourable RF wave physics leads to efficient current drive, current profile control, heating and flow drive. This triple combination—advanced divertors, advanced RF actuators, reactor-prototypical core plasma conditions—will enable ADX to explore enhanced core confinement physics, such as made possible by reversed central shear, using only the types of external drive systems that are considered viable for a fusion power plant. Such an integrated demonstration of high-performance core-divertor operation with steady-state sustainment would pave the way towards an attractive pilot plant, as envisioned in the ARC concept

  20. Synthesis and properties of hectorite/poly(AM/IA) nanocomposite hydrogels with high gel strength

    Indian Academy of Sciences (India)

    Lan Wang; Wenzhong Cheng; Tao Wan; Ziwen Hu; Min Xu; Ruixiang Li; Chuzhang Zou

    2015-01-01

    A novel hectorite/poly(AM/IA)nanocomposite hydrogel was synthesized by inverse microemulsion polymerization. The influence of hectorite amount on water absorbency rate, gel strength and shearresistance was investigated. Dynamic viscoelasticity behaviour of the nanocomposite hydrogels was also studied. The nanocomposite hydrogels showed suitable water absorbency and shear-resistance, high gel strength, solid-like behaviour in the whole oscillation frequency region and enhanced viscoelastic behaviours under high stress. TEM indicated that the as-synthesized hydrogel particles were regular and spherical in shape with an average particle size of 43 nm in the range of 30-65 nm.

  1. Thermal Activation Analyses of Dynamic Fracture Toughness of High Strength Low Alloy Steels

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A formula is derived for determining the influence of temperatureand loading rate on dynamic fracture toughness of a high strength low alloy steel (HQ785C) from thermal activation analysis of the experimental results of three-point bend specimens as well as introducing an Arrhenius formula. lt is shown that the results obtained by the given formula are in good agreement with the experimental ones in the thermal activation region. The present method is also valuable to describe the relationship between dynamic fracture toughness and temperature and loading rate of other high strength low alloy steels.

  2. The influence of cellular structures on flow stress of high strength components manufactured using SLM

    DEFF Research Database (Denmark)

    Mahshid, Rasoul; Hansen, Hans Nørgaard; Loft Højbjerre, Klaus

    2016-01-01

    Additive manufacturing has shown significant improvement in material and machines for high-quality solid freeform fabrication processes such as selective laser melting (SLM). In particular, manufacturing lattice structures using the SLM procedure is of interest. This research examines the effect...... of cellular materials on compression strength. The specimens are manufactured additively using industrial 3D printing systems from high-strength alloy. The material has the right mechanical properties for manufacturing tool components. This includes samples with solid and lattice structures. The Compression...

  3. Cold Cracking Of Underwater Wet Welded S355G10+N High Strength Steel

    Directory of Open Access Journals (Sweden)

    Fydrych D.

    2015-09-01

    Full Text Available Water as the welding environment determines some essential problems influencing steel weldability. Underwater welding of high strength steel joints causes increase susceptibility to cold cracking, which is an effect of much faster heat transfer from the weld area and presence of diffusible hydrogen causing increased metal fragility. The paper evaluates the susceptibility to cold cracking of the high strength S355G10+N steel used, among others, for ocean engineering and hydrotechnical structures, which require underwater welding. It has been found from the CTS test results that the investigated steel is susceptible to cold cracking in the wet welding process.

  4. Investigation of stress–strain models for confined high strength concrete

    Indian Academy of Sciences (India)

    Metin Husem; Selim Pul

    2007-06-01

    The effects of confinement reinforcement on the behaviour of high strength concrete columns are investigated for which prismatic experimental specimens were prepared. In the experiment specimens, four longitude reinforcement and confinement reinforcement were used. For each experiment, stress–strain relationship of concrete was obtained and compared with models proposed earlier. The results show that confinement reinforcement improved the ductility of high strength concrete. The ascending branch of stress–strain curves depended on the ratio of confinement reinforcement was similar to the modified Kent–Park model and the descending branch similar to the Nagashima model.

  5. Coseismic landslides reveal near-surface rock strength in a high-relief tectonically active setting

    Science.gov (United States)

    Gallen, Sean F; Clark, Marin K; Godt, Jonathan W.

    2014-01-01

    We present quantitative estimates of near-surface rock strength relevant to landscape evolution and landslide hazard assessment for 15 geologic map units of the Longmen Shan, China. Strength estimates are derived from a novel method that inverts earthquake peak ground acceleration models and coseismic landslide inventories to obtain material proper- ties and landslide thickness. Aggregate rock strength is determined by prescribing a friction angle of 30° and solving for effective cohesion. Effective cohesion ranges are from 70 kPa to 107 kPa for 15 geologic map units, and are approximately an order of magnitude less than typical laboratory measurements, probably because laboratory tests on hand-sized specimens do not incorporate the effects of heterogeneity and fracturing that likely control near-surface strength at the hillslope scale. We find that strength among the geologic map units studied varies by less than a factor of two. However, increased weakening of units with proximity to the range front, where precipitation and active fault density are the greatest, suggests that cli- matic and tectonic factors overwhelm lithologic differences in rock strength in this high-relief tectonically active setting.

  6. Advanced Extremely High Frequency Satellite (AEHF)

    Science.gov (United States)

    2015-12-01

    High Frequency Satellite (AEHF) is a joint service satellite communications system that provides global , survivable, secure, protected, and jam...three satellites fully integrated into the Milstar constellation. October 2014: On October 16, 2014, the program received PEO certification for the...Combined Orbital Operation, Logistics Sustainment ( COOLS ) contract, it will be completed and coordinated in CY 2016. The AEHF system being sustained

  7. Hydrogen Environment Assisted Cracking of Ultra-High Strength AetMet(Trademark) 100 Steel

    Science.gov (United States)

    2006-01-01

    strength alloys[17] and at the region of maximum crack tip hydrostatic tension for IIAC[871. Traditional UIISS such as AISI 4340 and 300M are particularly...of 1725 MNPa[21藁. Despite these advances, AerMetTM 100 is susceptible to HAC comparable to older UHSSfI 8󈧝- 301 . For example, IRAC of AerMetTM 100...older UHSSs such as AISI 4340, 18Ni Maraging and 300M show severe IG HEAC for a wide range of composition, thermal treatment and environmental

  8. Advance Mining of Temporal High Utility Itemset

    Directory of Open Access Journals (Sweden)

    Swati Soni

    2012-04-01

    Full Text Available The stock market domain is a dynamic and unpredictable environment. Traditional techniques, such as fundamental and technical analysis can provide investors with some tools for managing their stocks and predicting their prices. However, these techniques cannot discover all the possible relations between stocks and thus there is a need for a different approach that will provide a deeper kind of analysis. Data mining can be used extensively in the financial markets and help in stock-price forecasting. Therefore, we propose in this paper a portfolio management solution with business intelligence characteristics. We know that the temporal high utility itemsets are the itemsets with support larger than a pre-specified threshold in current time window of data stream. Discovery of temporal high utility itemsets is an important process for mining interesting patterns like association rules from data streams. We proposed the novel algorithm for temporal association mining with utility approach. This make us to find the temporal high utility itemset which can generate less candidate itemsets.

  9. Ductile Bulk Aluminum-Based Alloy with Good Glass-Forming Ability and High Strength

    Institute of Scientific and Technical Information of China (English)

    ZHUO Long-Chao; PANG Shu-Jie; WANG Hui; ZHANG Tao

    2009-01-01

    Based on a new approach for designing glassy alloy compositions,bulk Al-based alloys with good glass-forming ability (GFA) are synthesized.The cast Al86Si0.5Ni4.06Co2.94 Y6Sc0.5 rod with a diameter of 1 mm shows almost fully amorphous structure besides about 5% fcc-Al nucleated in the center of the rod.The bulk alloy with high Al concentration exhibits an ultrahigh yield strength of 1.18 Gpa and maximum strength of 1.27 Gpa as well as an obvious plastic strain of about 2.4% during compressive deformation.This light Al-based alloy with good GFA and mechanical properties is promising as a new high specific strength material with good deformability.

  10. Effect of microstructure on the high temperature strength of nitride bonded silicon carbide composite

    Indian Academy of Sciences (India)

    J Rakshit; P K Das

    2002-10-01

    Four compositions of nitride bonded SiC were fabricated with varying particle size of SiC of ∼ 9.67, ∼ 13.79, ∼ 60 and their mixture with Si of ∼ 4.83 particle size. The green density and hence the open porosity of the shapes were varied between 1.83 to 2.09 g/cc and 33.3 to 26.8 vol.%, respectively. The effect of these parameters on room temperature and high temperature strength of the composite up to 1300°C in ambient condition were studied. The high temperature flexural strength of the composite of all compositions increased at 1200 and 1300°C because of oxidation of Si3N4 phase and blunting crack front. Formation of Si3N4 whisker was also observed. The strength of the mixture composition was maximum.

  11. Very-high-strength (60-GPa) carbon nanotube fiber design based on molecular dynamics simulations

    Science.gov (United States)

    Cornwell, Charles F.; Welch, Charles R.

    2011-05-01

    The mechanical properties of carbon nanotubes such as low density, high stiffness, and exceptional strength make them ideal candidates for reinforcement material in a wide range of high-performance composites. Molecular dynamics simulations are used to predict the tensile response of fibers composed of aligned carbon nanotubes with intermolecular bonds of interstitial carbon atoms. The effects of bond density and carbon nanotube length distribution on fiber strength and stiffness are investigated. The interstitial carbon bonds significantly increase load transfer between the carbon nanotubes over that obtained with van der Waals forces. The simulation results indicate that fibers with tensile strengths to 60 GPa could be produced by employing interstitial cross-link atoms. The elastic modulus of the fibers is also increased by the bonds.

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

    Science.gov (United States)

    Abrahams, Rachel A.

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

  13. Recent advances in the evaluation of the strength and deformation properties of flexible pavements using GPR

    Science.gov (United States)

    Tosti, Fabio; Bianchini Ciampoli, Luca; Benedetto, Andrea; Alani, Amir M.; Loizos, Andreas; D'Amico, Fabrizio

    2016-04-01

    Even though there is plenty of literature contributions related to the non-destructive evaluation of road pavements using ground-penetrating radar (GPR), with several purposes spanning from the layer thicknesses evaluation to the detection of highly wet spots in the subsurface, there is still a lack of highly-reliable results concerning the mechanical assessment of road pavements, by using this technology. This work endeavours to face this topic and proposes a semi-empirical model for predicting the elastic modulus of a flexible pavement, by employing GPR. Data were collected over three different road sections within the districts of Madrid and Guadalajara, Spain. In particular, GPR surveys were carried out at the speed of traffic over the roads N320 and N211 in the district of Gadalajara and the road N320 in the district of Madrid, for a total of 39 kilometers, approximately. In particular, air-coupled radar systems with a 1000 MHz center frequency antenna and two different 2000 MHz center frequency antennas, mounted onto an instrumented vehicle, were here employed. The calibration of the model was then performed by exploiting ground-truth data coming from other non-destructive technologies. In more details, an instrumented lorry equipped with a curviameter, namely, a deflection tool capable to collect and process continuously and in real time the mechanical response of the flexible pavement, was used in the above road sections. Promising results are here presented, and the potential of GPR for monitoring the mechanical performances of a road network is also proved. Acknowledgement The Authors thank COST, for funding the Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar."

  14. Warm Spraying of High-Strength Ni-Al-Bronze: Cavitation Characteristics and Property Prediction

    Science.gov (United States)

    Krebs, Sebastian; Kuroda, Seiji; Katanoda, Hiroshi; Gaertner, Frank; Klassen, Thomas; Araki, Hiroshi; Frede, Simon

    2017-01-01

    Bronze materials such as Ni-Al-bronze show exceptional performances against cavitation erosion, due to their high fatigue strength and high strength. These materials are used for ship propellers, pump systems or for applications with alternating stresses. Usually, the respective parts are cast. With the aim to use resources more efficiently and to reduce costs, this study aimed to evaluate opportunities to apply bronze as a coating to critical areas of respective parts. The coatings should have least amounts of pores and non-bonded areas and any contaminations that might act as crack nuclei and contribute to material damages. Processes with low oxidation and high kinetic impacts fulfill these criteria. Especially warm spraying, a nitrogen-cooled HVOF process, with similar impact velocities as cold gas spraying but enhanced process temperature, allows for depositing high-strength Ni-Al-bronze. This study systematically simulates and evaluates the formation and performance of warm-sprayed Ni-Al-bronze coatings for different combustion pressures and nitrogen flow rates. Substrate preheating was used to improve coating adhesion for lower spray parameter sets. Furthermore, this study introduces an energy-based concept to compare spray parameter sets and to predict coating properties. Coatings with low porosities and high mechanical strengths are obtained, allowing for a cavitation resistance similar to bulk material.

  15. Advanced Polymeric Materials for High-tech Innovations

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ High technology is advancing our society and modernizing our life and advanced materials play an important role in the technological innovations. My research group has been working on the development of advanced polymeric materials and in this talk I will report our recent work on the creation of new conjugated polymers with novel molecular structures and unique materials properties.1-18 Our work include the design of molecular structures of monomeric building blocks, development of stable, effective and environmentally benign "green” polymerization catalysts, discovery of new polymerization reactions, synthesis of functional macromolecules, fabrication of nanodimensional composites, assembly and control of hierarchical structures, and construction of electrooptical devices. We have revealed the liquid crystallinity, light emission, photoconductivity, optical limiting, nano-hybridization, solvatochromism, optical activity, self-organization, and biological activity of the linear polyacetylenes and hyperbranched polyarylenes. The utilization of the advanced polymers and their interesting materials properties for high-tech innovations will be discussed.

  16. Advanced Polymeric Materials for High-tech Innovations

    Institute of Scientific and Technical Information of China (English)

    TANG; BenZhong

    2001-01-01

    High technology is advancing our society and modernizing our life and advanced materials play an important role in the technological innovations. My research group has been working on the development of advanced polymeric materials and in this talk I will report our recent work on the creation of new conjugated polymers with novel molecular structures and unique materials properties.1-18 Our work include the design of molecular structures of monomeric building blocks, development of stable, effective and environmentally benign "green” polymerization catalysts, discovery of new polymerization reactions, synthesis of functional macromolecules, fabrication of nanodimensional composites, assembly and control of hierarchical structures, and construction of electrooptical devices. We have revealed the liquid crystallinity, light emission, photoconductivity, optical limiting, nano-hybridization, solvatochromism, optical activity, self-organization, and biological activity of the linear polyacetylenes and hyperbranched polyarylenes. The utilization of the advanced polymers and their interesting materials properties for high-tech innovations will be discussed.  ……

  17. An investigation of the plastic fracture of high strength steels. Ph.D. Thesis

    Science.gov (United States)

    Cox, T. B.; Low, J. R., Jr.

    1973-01-01

    Three generally recognized stages of plastic fracture in high strength steels are considered in detail. These stages consist of void initiation, void growth, and void coalescence. A brief review of the existing literature on plastic fracture is included along with an outline of the experimental approach used in the investigation.

  18. Brazing process provides high-strength bond between aluminum and stainless steel

    Science.gov (United States)

    Huschke, E. G., Jr.; Nord, D. B.

    1966-01-01

    Brazing process uses vapor-deposited titanium and an aluminum-zirconium-silicon alloy to prevent formation of brittle intermetallic compounds in stainless steel and aluminum bonding. Joints formed by this process maintain their high strength, corrosion resistance, and hermetic sealing properties.

  19. Kic size effect study on two high-strength steels using notched bend specimens

    Science.gov (United States)

    Stonesifer, F. R.

    1974-01-01

    Five methods are used to calculate plane strain fracture toughness (K sub Q) values for bend-specimens of various sizes from two high-strength steels. None of the methods appeared to satisfactorily predict valid stress intensity factor (K sub IC) values from specimens of sizes well below that required by E399 standard tests.

  20. Application of a criterion for cold cracking to casting high strength aluminum alloys

    NARCIS (Netherlands)

    Lalpoor, M.; Eskin, D.G.; Fjaer, H.G.; Ten Cate, A.; Ontijt, N.; Katgerman, L.

    2010-01-01

    Direct chill (DC) casting of high strength 7xxx series aluminium alloys is difficult mainly due to solidification cracking (hot cracks) and solid state cracking (cold cracks). Poor thermal properties along with extreme brittleness in the as-cast condition make DC-casting of such alloys a challenging

  1. Environmentally assisted crack growth rates of high-strength aluminum alloys

    Science.gov (United States)

    Connolly, Brain J.; Deffenbaugh, Kristen L.; Moran, Angela L.; Koul, Michelle G.

    2003-01-01

    The scope of this project is to evaluate the environmentally assisted long crack growth behavior of candidate high-strength aluminum alloys/tempers, specifically AA7150-T7751 and AA7040-T7651, for consideration as viable replacements/refurbishment for stress-corrosion cracking in susceptible AA7075-T6 aircraft components found in aging aircraft systems.

  2. Fretting fatigue behavior of high-strength steel monostrands under bending load

    DEFF Research Database (Denmark)

    Winkler, Jan; Georgakis, Christos T.; Fischer, Gregor

    2015-01-01

    In this paper, the fretting fatigue behavior of pretensioned high-strength steel monostrands is investigated. To measure the local deformations on the strands, a novel method based on the digital image correlation (DIC) technique was used to quantify the relative movement between individual wires...

  3. Stress-Corrosion Cracking in High Strength Steels and in Titanium and Aluminum Alloys

    Science.gov (United States)

    1972-01-01

    importance that the newcomer might wonder why the question is not settled almost as the first order of business . The reason is that to prove the... Agricola and J. T. Snyder, "Stress Corrosion of Explosively Deformed High-Strength Alloys," Metals Eng. Quart. 7 (No. 3), 59 (1967). 138. P. N. Orava

  4. MR venography of the human brain using susceptibility weighted imaging at very high field strength

    NARCIS (Netherlands)

    Koopmans, Peter J.; Manniesing, Rashindra; Niessen, Wiro J.; Viergever, Max A.; Barth, Markus

    2008-01-01

    Objective We investigate the implications of high magnetic field strength on MR venography based on susceptibility-weighted imaging (SWI) and estimate the optimum echo time to obtain maximum contrast between blood and brain tissue. Materials and methods We measured tissue contrast and T*(2) relaxati

  5. High tensile strength fly ash based geopolymer composite using copper coated micro steel fiber

    DEFF Research Database (Denmark)

    Ranjbar, Navid; Mehrali, Mehdi; Mehrali, Mohammad

    2016-01-01

    As a ceramic-like material, geopolymers show a high quasi-brittle behavior and relatively low fracture energy. To overcome this, the addition of fibers to a brittle matrix is a well-known method to improve the flexural strength. Moreover, the success of the reinforcements is dependent on the fibe...

  6. Fatigue experiments on hybrid welded connections made of very high strength steels

    NARCIS (Netherlands)

    Pijpers, R.J.M.; Kolstein, M.H.; Romeijn, A.; Bijlaard, F.S.K.

    2009-01-01

    In a fatigue loaded structure made of Very High Strength Steels (VHSS) absolute and relative stress variations will be higher compared to those in structures made of lower grade steels. Stress concentrations in joints reduce the advantage of VHSS under cyclic loading. A hybrid connection, consisting

  7. Experimental Investigation of the Fracture Behaviour of Reinforced Ultra High Strength Concrete

    DEFF Research Database (Denmark)

    Ulfkjær, J. P.; Henriksen, M. S.; Aarup, B.

    the structural behaviour of a very high strength cement based material with and without steel fibres is investigated. A simple structural geometry has been tested, namely a beam subjected to three point bending. The results shows that the increase of ductility of the material also gives a more ductile behaviour...

  8. Fatigue properties of high-strength materials used in cold-forging tools

    DEFF Research Database (Denmark)

    Brøndsted, P.; Skov-Hansen, P.

    1998-01-01

    In the present work classical analytical models are used to describe the static stress–strain curves, low-cycle fatigue properties and fatigue crack growth behaviour of high-strength materials for use in tools for metal-forming processes such as cold forging and extrusion. The paper describes...

  9. Design of Hierarchically Cut Hinges for Highly Stretchable and Reconfigurable Metamaterials with Enhanced Strength.

    Science.gov (United States)

    Tang, Yichao; Lin, Gaojian; Han, Lin; Qiu, Songgang; Yang, Shu; Yin, Jie

    2015-11-25

    Applying hierarchical cuts to thin sheets of elastomer generates super-stretchable and reconfigurable metamaterials, exhibiting highly nonlinear stress-strain behaviors and tunable phononic bandgaps. The cut concept fails on brittle thin sheets due to severe stress concentration in the rotating hinges. By engineering the local hinge shapes and global hierarchical structure, cut-based reconfigurable metamaterials with largely enhanced strength are realized.

  10. Weldability prediction of high strength steel S960QL after weld thermal cycle simulation

    Directory of Open Access Journals (Sweden)

    M. Dunđer

    2014-10-01

    Full Text Available This paper presents weld thermal cycle simulation of high strength steel S960QL, and describes influence of cooling time t8/5 on hardness and impact toughness of weld thermal cycle simulated specimens. Furthermore, it presents analysis of characteristic fractions done by electron scanning microscope which can contribute to determination of welding parameters for S960QL steel.

  11. High power infrared QCLs: advances and applications

    Science.gov (United States)

    Patel, C. Kumar N.

    2012-01-01

    QCLs are becoming the most important sources of laser radiation in the midwave infrared (MWIR) and longwave infrared (LWIR) regions because of their size, weight, power and reliability advantages over other laser sources in the same spectral regions. The availability of multiwatt RT operation QCLs from 3.5 μm to >16 μm with wall plug efficiency of 10% or higher is hastening the replacement of traditional sources such as OPOs and OPSELs in many applications. QCLs can replace CO2 lasers in many low power applications. Of the two leading groups in improvements in QCL performance, Pranalytica is the commercial organization that has been supplying the highest performance QCLs to various customers for over four year. Using a new QCL design concept, the non-resonant extraction [1], we have achieved CW/RT power of >4.7 W and WPE of >17% in the 4.4 μm - 5.0 μm region. In the LWIR region, we have recently demonstrated QCLs with CW/RT power exceeding 1 W with WPE of nearly 10 % in the 7.0 μm-10.0 μm region. In general, the high power CW/RT operation requires use of TECs to maintain QCLs at appropriate operating temperatures. However, TECs consume additional electrical power, which is not desirable for handheld, battery-operated applications, where system power conversion efficiency is more important than just the QCL chip level power conversion efficiency. In high duty cycle pulsed (quasi-CW) mode, the QCLs can be operated without TECs and have produced nearly the same average power as that available in CW mode with TECs. Multiwatt average powers are obtained even in ambient T>70°C, with true efficiency of electrical power-to-optical power conversion being above 10%. Because of the availability of QCLs with multiwatt power outputs and wavelength range covering a spectral region from ~3.5 μm to >16 μm, the QCLs have found instantaneous acceptance for insertion into multitude of defense and homeland security applications, including laser sources for infrared

  12. Neptunium(V) Adsorption to Bacteria at Low and High Ionic Strength

    Science.gov (United States)

    Ams, D.; Swanson, J. S.; Reed, D. T.

    2010-12-01

    Np(V) is expected to be the predominant oxidation state of neptunium in aerobic natural waters. Np(V), as the NpO2+ aquo and associated complexed species, is readily soluble, interacts weakly with geologic media, and has a high redox stability under a relatively wide range of subsurface conditions. These chemical properties, along with a long half-life make it a primary element of concern regarding long-term nuclear waste storage and subsurface containment. The fate and transport of neptunium in the environment may be influenced by adsorption onto bacterial surfaces. The adsorption of neptunium to bacterial surfaces ties the mobility of the contaminant to the mobility of the bacterium. In this study, the adsorption of the neptunyl (NpO2+) ion was evaluated at low ionic strength on a common soil bacterium and at high ionic strength on a halophilic bacterium isolated from a briny groundwater near the Waste Isolation Pilot Plant (WIPP) in southeast New Mexico. Adsorption experiments were performed in batch reactors as a function of pH, ionic strength, and bacteria/Np mass ratio. Np(V) adsorption was modeled using a surface complexation approach with the mathematical program FITEQL to determine functional group specific binding constants. The data from acid and base titrations of the bacteria used were also modeled to estimate the concentrations and deprotonation constants of discrete bacterial surface functional groups. Bacterial functional group characteristics and Np(V) adsorption behavior between the soil bacterium and the halophilic bacterium were compared. These results highlight key similarities and differences in actinide adsorption behavior in environments of significantly different ionic strength. The observed adsorption behavior may be linked to similarities and differences in the characteristics of the moieties between the cell walls of common gram-negative soil and halophilic bacteria. Moreover, differences in adsorption behavior may also reflect ionic

  13. The Effect of Bauxite Substitution on High Temperature Strength Properties of Zirconia—corundum Mullite Material

    Institute of Scientific and Technical Information of China (English)

    ZHONGWei-bin; SUNGeng-chen; 等

    1994-01-01

    Investigations on the effect of bauxite substi-tution for industrial alumina on high temperature strength and thermal shock resistance of reaction-sintered zirconia-corundum-mullite material(ZrO2 15%) have indicated that bauxite substitution would lead to increase in modulus of rupture at 1000-1400℃ as well as improvement in thermal shock resistance,Hot strength value reaches a maximum at 15% buxite addition.The mecha-nism of mechanical behavior at elevated tempera-tures is discussed in association with changes in mi-crostructural characteristics.

  14. A promising structure for fabricating high strength and high electrical conductivity copper alloys.

    Science.gov (United States)

    Li, Rengeng; Kang, Huijun; Chen, Zongning; Fan, Guohua; Zou, Cunlei; Wang, Wei; Zhang, Shaojian; Lu, Yiping; Jie, Jinchuan; Cao, Zhiqiang; Li, Tingju; Wang, Tongmin

    2016-02-09

    To address the trade-off between strength and electrical conductivity, we propose a strategy: introducing precipitated particles into a structure composed of deformation twins. A Cu-0.3%Zr alloy was designed to verify our strategy. Zirconium was dissolved into a copper matrix by solution treatment prior to cryorolling and precipitated in the form of Cu5Zr from copper matrix via a subsequent aging treatment. The microstructure evolutions of the processed samples were investigated by transmission electron microscopy and X-ray diffraction analysis, and the mechanical and physical behaviours were evaluated through tensile and electrical conductivity tests. The results demonstrated that superior tensile strength (602.04 MPa) and electrical conductivity (81.4% IACS) was achieved. This strategy provides a new route for balancing the strength and electrical conductivity of copper alloys, which can be developed for large-scale industrial application.

  15. High performance installation for drill and blast advance Mitholz, Switzerland

    Institute of Scientific and Technical Information of China (English)

    Jost Wenk

    2004-01-01

    The section Mitholz of the L tschberg Alp - Transit tunnel consists basically of 3 drill & blast advances with a cross section of 63 - 69m2 and a total length of 25 km.The high - performance back - up installation in use distinguishes itself by the following substantial innovations:The joint venture SATCO ( STRABAG AG, Rothpletz, Lienhard & Cie. , Walo Bertschinger AG, Vinci Construction,Skanska Europe AB), the c ontractor in charge, is achieving very high rates of advance, thanks to the high - performance back - up installations.- The chosen heading system has a positive effect on the entire construction program. Supplementary work can be done within the planned time schedule - Owing to the excellent performance, the joint venture SATCO is ahead on the construction program by about 700m.- The high rates of advance result for the customer in a positive return on investment - The installed equipment results in a higher safety at the workplace for the workers

  16. Structural optimization of 3D-printed synthetic spider webs for high strength

    Science.gov (United States)

    Qin, Zhao; Compton, Brett G.; Lewis, Jennifer A.; Buehler, Markus J.

    2015-05-01

    Spiders spin intricate webs that serve as sophisticated prey-trapping architectures that simultaneously exhibit high strength, elasticity and graceful failure. To determine how web mechanics are controlled by their topological design and material distribution, here we create spider-web mimics composed of elastomeric filaments. Specifically, computational modelling and microscale 3D printing are combined to investigate the mechanical response of elastomeric webs under multiple loading conditions. We find the existence of an asymptotic prey size that leads to a saturated web strength. We identify pathways to design elastomeric material structures with maximum strength, low density and adaptability. We show that the loading type dictates the optimal material distribution, that is, a homogeneous distribution is better for localized loading, while stronger radial threads with weaker spiral threads is better for distributed loading. Our observations reveal that the material distribution within spider webs is dictated by the loading condition, shedding light on their observed architectural variations.

  17. High-intensity strength training improves function of chronically painful muscles

    DEFF Research Database (Denmark)

    Andersen, Lars L; Andersen, Christoffer H; Skotte, Jørgen H

    2014-01-01

    randomized to 10 weeks of specific strength training (SST, n = 18), general fitness training (GFT, n = 16), or a reference group without physical training (REF, n = 8). Participants performed tests of 100 consecutive cycles of 2 s isometric maximal voluntary contractions (MVC) of shoulder elevation followed...... by 2 s relaxation at baseline and 10-week follow-up. RESULTS: In the case-control study, peak force, rate of force development, and rate of force relaxation as well as EMG amplitude were lower in MYA than CON throughout all 100 MVC. Muscle fiber capillarization was not significantly different between...... capacity during repetitive MVC of the trapezius muscle than healthy controls. High-intensity strength training effectively improves strength capacity during repetitive MVC of the painful trapezius muscle....

  18. A new approach to predict the strength of high energy materials.

    Science.gov (United States)

    Keshavarz, Mohammad Hossein; Ghorbanifaraz, Mohammad; Rahimi, Hadi; Rahmani, Mehdi

    2011-02-15

    This paper presents a new approach to predict the strength of energetic compounds in which there are important classes of high explosives including nitroaromatics, acyclic and cyclic nitramines, nitrate esters and nitroaliphatics. For C(a)H(b)N(c)O(d) compounds, the ratio of carbon to oxygen atoms and the predicted heat of detonation on the basis of the H(2)O-CO(2) arbitrary have been used to calculate the strength of an explosive. The new model can give good predictions for mentioned energetic compounds as determined by the Trauzl test. The novel correlation will be useful in predicting the strength or power of a new energetic compound that has significant potential in the field of explosives and propellants.

  19. A new approach to predict the strength of high energy materials

    Energy Technology Data Exchange (ETDEWEB)

    Keshavarz, Mohammad Hossein, E-mail: mhkeshavarz@mut-es.ac.ir [Department of Chemistry, Malek-ashtar University of Technology, Shahin-shahr, P.O. Box 83145/115 (Iran, Islamic Republic of); Ghorbanifaraz, Mohammad; Rahimi, Hadi; Rahmani, Mehdi [Department of Chemistry, Malek-ashtar University of Technology, Shahin-shahr, P.O. Box 83145/115 (Iran, Islamic Republic of)

    2011-02-15

    This paper presents a new approach to predict the strength of energetic compounds in which there are important classes of high explosives including nitroaromatics, acyclic and cyclic nitramines, nitrate esters and nitroaliphatics. For C{sub a}H{sub b}N{sub c}O{sub d} compounds, the ratio of carbon to oxygen atoms and the predicted heat of detonation on the basis of the H{sub 2}O-CO{sub 2} arbitrary have been used to calculate the strength of an explosive. The new model can give good predictions for mentioned energetic compounds as determined by the Trauzl test. The novel correlation will be useful in predicting the strength or power of a new energetic compound that has significant potential in the field of explosives and propellants.

  20. High-Strength Low-Alloy (HSLA) Mg-Zn-Ca Alloys with Excellent Biodegradation Performance

    Science.gov (United States)

    Hofstetter, J.; Becker, M.; Martinelli, E.; Weinberg, A. M.; Mingler, B.; Kilian, H.; Pogatscher, S.; Uggowitzer, P. J.; Löffler, J. F.

    2014-04-01

    This article deals with the development of fine-grained high-strength low-alloy (HSLA) magnesium alloys intended for use as biodegradable implant material. The alloys contain solely low amounts of Zn and Ca as alloying elements. We illustrate the development path starting from the high-Zn-containing ZX50 (MgZn5Ca0.25) alloy with conventional purity, to an ultrahigh-purity ZX50 modification, and further to the ultrahigh-purity Zn-lean alloy ZX10 (MgZn1Ca0.3). It is shown that alloys with high Zn-content are prone to biocorrosion in various environments, most probably because of the presence of the intermetallic phase Mg6Zn3Ca2. A reduction of the Zn content results in (Mg,Zn)2Ca phase formation. This phase is less noble than the Mg-matrix and therefore, in contrast to Mg6Zn3Ca2, does not act as cathodic site. A fine-grained microstructure is achieved by the controlled formation of fine and homogeneously distributed (Mg,Zn)2Ca precipitates, which influence dynamic recrystallization and grain growth during hot forming. Such design scheme is comparable to that of HSLA steels, where low amounts of alloying elements are intended to produce a very fine dispersion of particles to increase the material's strength by refining the grain size. Consequently our new, ultrapure ZX10 alloy exhibits high strength (yield strength R p = 240 MPa, ultimate tensile strength R m = 255 MPa) and simultaneously high ductility (elongation to fracture A = 27%), as well as low mechanical anisotropy. Because of the anodic nature of the (Mg,Zn)2Ca particles used in the HSLA concept, the in vivo degradation in a rat femur implantation study is very slow and homogeneous without clinically observable hydrogen evolution, making the ZX10 alloy a promising material for biodegradable implants.

  1. Metallurgical and mechanical properties of laser welded high strength low alloy steel.

    Science.gov (United States)

    Oyyaravelu, Ramachandran; Kuppan, Palaniyandi; Arivazhagan, Natarajan

    2016-05-01

    The study aimed at investigating the microstructure and mechanical properties of Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) laser welded high strength low alloy (HSLA) SA516 grade 70 boiler steel. The weld joint for a 4 mm thick plate was successfully produced using minimum laser power of 2 kW by employing a single pass without any weld preheat treatment. The micrographs revealed the presence of martensite phase in the weld fusion zone which could be due to faster cooling rate of the laser weldment. A good correlation was found between the microstructural features of the weld joints and their mechanical properties. The highest hardness was found to be in the fusion zone of cap region due to formation of martensite and also enrichment of carbon. The hardness results also showed a narrow soft zone at the heat affected zone (HAZ) adjacent to the weld interface, which has no effect on the weld tensile strength. The yield strength and ultimate tensile strength of the welded joints were 338 MPa and 549 MPa, respectively, which were higher than the candidate metal. These tensile results suggested that the laser welding process had improved the weld strength even without any weld preheat treatment and also the fractography of the tensile fractured samples showed the ductile mode of failure.

  2. Prospective high strength steel utilizing TRIP effect; Hentai yuki sosei koka wo riyoshita jisedai kokyodo usukoban

    Energy Technology Data Exchange (ETDEWEB)

    Sakuma, Y.; Kimura, N.; Itami, a.; Hiwatashi, S.; Kawano, O.; Sakata, K. [Nippon Steel Corp., Tokyo (Japan)

    1994-11-29

    The transformation induced plasticity (TRIP) means the large extension of chemically unstable austenitic {gamma} phase when it is transformed into martensite by the addition of dynamic energy. The application of TRIP effect is promising to the auto-body use steel plate because thin stainless steel plates excelling in bulging properties are producible. The present paper explained the enlarging mechanism of elongation, principle of production, examples of production on the actual line, formability, weldability and fatigue durability. Than that of the different conventional steel plates, a better combination of both strength and elongation was recorded through the actual line trial production of cold and hot rolled steel plates which were 590 to 980N/mm{sup 2} in tensile strength. Their apparent superiority in bulging properties was confirmed in the vicinity of plain strain, while their deep drawability was also known to be good through a TZP test. The presently developed steel excelled the conventional high-strength steel in strength at spot welding, while its fatigue strength was higher even than that of the dual-phase steel so far regarded as the best in it. 13 refs., 12 figs., 4 tabs.

  3. Analysis of the tribology performance of the high-strength composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Using the hoop-lump experimental machine, I have studied three kinds of high-strengthcomposites(s1,s2,s3) made in my company. They were rub against 45# steel separately under theconditions of dry-friction, water solution and 40# machine oil. The results show that under the con-dition of oil-lubrication, the wear-proof performance of the high strength composites has been ap-parently improved. Their coefficient of friction dropped one order of magnitude than under the con-dition of dry-friction or water solution friction. Their rates of wear dropped 1-2 order of magnitude.S2 is the best one. Studying the tribology performance of S2 under the condition of coal mud, wefound the coefficient of friction of S2 was below 0.2. Under the load of p=100N, its performance isbetter.The mechanical property test also shows that the high strength composites are superior All thetests show: The quantities, sizes and distribution of the strength composites have a better scope of ap-por-tion and proportion. More importantly, the results of the above test to tribology performance of thehigh strength composites will efficiently guide the production.

  4. Notch fatigue behavior: Metallic glass versus ultra-high strength steel

    Science.gov (United States)

    Wang, X. D.; Qu, R. T.; Wu, S. J.; Duan, Q. Q.; Liu, Z. Q.; Zhu, Z. W.; Zhang, H. F.; Zhang, Z. F.

    2016-01-01

    Studying the effect of notch on the fatigue behavior of structural materials is of significance for the reliability and safety designing of engineering structural components. In this work, we conducted notch fatigue experiments of two high-strength materials, i.e. a Ti32.8Zr30.2Ni5.3Cu9Be22.7 metallic glass (MG) and a 00Ni18Co15Mo8Ti ultra-high strength steel (CM400 UHSS), and compared their notch fatigue behavior. Experimental results showed that although both the strength and plasticity of the MG were much lower than those of the UHSS, the fatigue endurance limit of the notched MG approached to that of the notched UHSS, and the fatigue ratio of the notched MG was even higher. This interesting finding can be attributed to the unique shear banding mechanism of MG. It was found that during fatigue process abundant shear bands formed ahead of the notch root and in the vicinity of the crack in the notched MG, while limited plastic deformation was observed in the notched UHSS. The present results may improve the understanding on the fatigue mechanisms of high-strength materials and offer new strategies for structural design and engineering application of MG components with geometrical discontinuities. PMID:27752136

  5. Notch fatigue behavior: Metallic glass versus ultra-high strength steel

    Science.gov (United States)

    Wang, X. D.; Qu, R. T.; Wu, S. J.; Duan, Q. Q.; Liu, Z. Q.; Zhu, Z. W.; Zhang, H. F.; Zhang, Z. F.

    2016-10-01

    Studying the effect of notch on the fatigue behavior of structural materials is of significance for the reliability and safety designing of engineering structural components. In this work, we conducted notch fatigue experiments of two high-strength materials, i.e. a Ti32.8Zr30.2Ni5.3Cu9Be22.7 metallic glass (MG) and a 00Ni18Co15Mo8Ti ultra-high strength steel (CM400 UHSS), and compared their notch fatigue behavior. Experimental results showed that although both the strength and plasticity of the MG were much lower than those of the UHSS, the fatigue endurance limit of the notched MG approached to that of the notched UHSS, and the fatigue ratio of the notched MG was even higher. This interesting finding can be attributed to the unique shear banding mechanism of MG. It was found that during fatigue process abundant shear bands formed ahead of the notch root and in the vicinity of the crack in the notched MG, while limited plastic deformation was observed in the notched UHSS. The present results may improve the understanding on the fatigue mechanisms of high-strength materials and offer new strategies for structural design and engineering application of MG components with geometrical discontinuities.

  6. Effect of water absorption by the aggregate on properties of high-strength lightweight concrete

    Energy Technology Data Exchange (ETDEWEB)

    Punkki, J.

    1995-12-31

    Recently, high-strength lightweight concrete has become an interesting building material for the offshore oil industry. This doctoral thesis presents an experimental investigation of the effect of water absorption by three different types of lightweight aggregates. One type did not show any water absorption ability at all and so represented no problem to the concrete production. For the two other high-strength aggregates, which were of more conventional types, the water absorption depended not only on the properties of the aggregates, but also on the concrete mixing procedure and the properties of the fresh cement paste. When water absorbing lightweight aggregate was used in a dry condition, the workability of the concrete was significantly reduced by the water absorption of the aggregate. This effect was not present when prewetted aggregate was used. The water absorption by the lightweight aggregate also affected the early compressive strength of concrete. After one day, dry aggregate gave on the average 10 MPa higher compressive strength than did prewetted aggregate. The strength-density ratio was affected by the moisture condition of the aggregate. Dry lightweight aggregate gave 9 MPa higher compressive strength at a density of 2000 kg/m{sup 3} compared to that of prewetted aggregate. The water absorption by the lightweight also affected the microstructure of the hardened concrete. Dry lightweight aggregate gave a slightly better microstructure than normal weight aggregate. The results indicate that the use of prewetted aggregate adversely affected the transition zone between the aggregate and the cement paste. 69 refs., 58 figs., 42 tabs.

  7. Temperature Dependence of Sound Velocity in High-Strength Fiber-Reinforced Plastics

    Science.gov (United States)

    Nomura, Ryuji; Yoneyama, Keiichi; Ogasawara, Futoshi; Ueno, Masashi; Okuda, Yuichi; Yamanaka, Atsuhiko

    2003-08-01

    Longitudinal sound velocity in unidirectional hybrid composites or high-strength fiber-reinforced plastics (FRPs) was measured along the fiber axis over a wide temperature range (from 77 K to 420 K). We investigated two kinds of high-strength crystalline polymer fibers, polyethylene (Dyneema) and polybenzobisoxazole (Zylon), which are known to have negative thermal expansion coefficients and high thermal conductivities along the fiber axis. Both FRPs had very high sound velocities of about 9000 m/s at low temperatures and their temperature dependences were very strong. Sound velocity monotonically decreased with increasing temperature. The temperature dependence of sound velocity was much stronger in Dyneema-FRP than in Zylon-FRP.

  8. Performance optimization and computational design of ultra-high strength gear steels

    Science.gov (United States)

    Tiemens, Benjamin Lee

    Rising power density requirements in transmission gear applications are swiftly outpacing gear redesign alone and will ultimately depend on better materials. Ni-Co secondary hardening steels show great promise for these applications due to their optimized combination of strength and toughness. The commercially available secondary hardening alloys GearMet RTM C61 and C67 have already demonstrated promising contact fatigue resistance, however bending fatigue is anticipated to be the primary failure mode limiting high power density gear applications. Single tooth bending fatigue testing was therefore completed on C61 and C67 spur gears to both assess the optimized performance of these alloys as well as identify defect populations currently limiting further advances. The resultant best-practice C61 spur gears in a shot peened and isotropic superfinished condition outperformed the top-ranking premium gear steel, demonstrating an approximate 15% improvement in bending fatigue endurance limit. Fatigue failures limiting further bending fatigue performance were identified to primarily initiate at three defect classes: shot peening-induced surface damage, subsurface inter-granular cleavage facets and Al2O3 and La2O2S inclusions. C67 spur gears did not show increased performance despite elevated surface hardness levels due to the inability of current shot peening practices to achieve maximum compressive stress in ultra-high hardness materials. In an effort to reduce the material cost of these alloys through minimization/elimination of cobalt alloying additions, BCC Cu precipitation was incorporated to offset ensuing losses in temper resistance by providing additional heterogeneous nucleation sites for the M2C strengthening dispersion. Fifty-pound experimental heats were made of four designed compositions. Peak hardness levels achieved during tempering fell on average 200 VHN short of the 900 VHN designed surface hardness. 3-dimensional local electrode atom probe (LEAP

  9. Effect of Heat Treatment on High Temperature Stress Rupture Strength of Brazing Seam for Nickel-base Superalloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to enhance the high-temperature stress rupture strength of brazing seam by heat treatment, it was diffusion treated, then solution heat treated, and finally aging treated. The microstructure of brazing seam especially morphology of phase and boride was observed and the strength of brazing seam was measured in this process. The results show that heat treatment can enhance high-temperature stress rupture strength by improving the microstructure of brazing seam. The strength of brazing seam after solution heat treatment decreases in comparison with that only after diffusion treatment while aging treatment after solution heat treatment increases the strength of brazing seam.

  10. Recent Advances in the Synthesis of High Explosive Materials

    OpenAIRE

    Jesse J. Sabatini; Karl D. Oyler

    2015-01-01

    This review discusses the recent advances in the syntheses of high explosive energetic materials. Syntheses of some relevant modern primary explosives and secondary high explosives, and the sensitivities and properties of these molecules are provided. In addition to the synthesis of such materials, processing improvement and formulating aspects using these ingredients, where applicable, are discussed in detail.

  11. High-energy diffraction microscopy at the advanced photon source

    DEFF Research Database (Denmark)

    Lienert, U.; Li, S. F.; Hefferan, C. M.;

    2011-01-01

    The status of the High Energy Diffraction Microscopy (HEDM) program at the 1-ID beam line of the Advanced Photon Source is reported. HEDM applies high energy synchrotron radiation for the grain and sub-grain scale structural and mechanical characterization of polycrystalline bulk materials in situ...

  12. Recent Advances in the Synthesis of High Explosive Materials

    Directory of Open Access Journals (Sweden)

    Jesse J. Sabatini

    2015-12-01

    Full Text Available This review discusses the recent advances in the syntheses of high explosive energetic materials. Syntheses of some relevant modern primary explosives and secondary high explosives, and the sensitivities and properties of these molecules are provided. In addition to the synthesis of such materials, processing improvement and formulating aspects using these ingredients, where applicable, are discussed in detail.

  13. Monotonic and Cyclic Bond Behavior of Deformed CFRP Bars in High Strength Concrete

    OpenAIRE

    2016-01-01

    Composite reinforcing bars (rebars) that are used in concrete members with high performance (strength and durability) properties could have beneficial effects on the behavior of these members. This is especially vital when a building is constructed in an aggressive environment, for instance a corrosive environment. Although tension capacity/weight (or volume) ratios in composite rebars (carbon fiber reinforced polymer (CFRP), glass fiber reinforced polymer (GFRP), etc.) are very high when com...

  14. 76 FR 48169 - Advancing Regulatory Science for Highly Multiplexed Microbiology/Medical Countermeasure Devices...

    Science.gov (United States)

    2011-08-08

    ... following public meeting: ``Advancing Regulatory Science for Highly Multiplexed Microbiology/Medical... microbiology/MCM devices. The ultimate goal is to advance regulatory science for highly multiplexed devices... HUMAN SERVICES Food and Drug Administration Advancing Regulatory Science for Highly...

  15. 76 FR 71982 - Advancing Regulatory Science for Highly Multiplexed Microbiology/Medical Countermeasure Devices...

    Science.gov (United States)

    2011-11-21

    ... paper entitled ''Advancing Regulatory Science for Highly Multiplexed Microbiology/Medical Countermeasure... the ``Advancing Regulatory Science for Highly Multiplexed Microbiology/Medical Countermeasure Devices... HUMAN SERVICES Food and Drug Administration Advancing Regulatory Science for Highly...

  16. Study on technology of high-frequency pulsed magnetic field strength measurement.

    Science.gov (United States)

    Chen, Yi-Mei; Liu, Zhi-Peng; Yin, Tao

    2012-01-01

    High-frequency transient weak magnetic field is always involved in researches about biomedical engineering field while common magnetic-field sensors cannot work properly at frequencies as high as MHz. To measure the value of MHz-level weak pulsed magnetic-field strength accurately, this paper designs a measurement and calibration method for pulsed magnetic-field. In this paper, a device made of Nonferromagnetic material was independently designed and applied to pulsed magnetic field measurement. It held an accurately relative position between the magnetic field generating coil and the detecting coil. By applying a sinusoidal pulse to the generator, collecting the induced electromotive force of the detector, the final magnetic field strength was worked out through algorithms written in Matlab according to Faraday's Law. Experiments were carried out for measurement and calibration. Experiments showed that, under good stability and consistency, accurate measurement of magnetic-field strength of a sinepulse magnetic-field can be achieved, with frequency at 0.5, 1, 1.5 MHz and strength level at micro-Tesla. Calibration results carried out a measuring relative error about 2.5%.

  17. Behavior Of A Confined Tension Lap Splice In High-Strength Reinforced Concrete Beams

    Science.gov (United States)

    Abdel-Kareem, Ahmed H.; Abousafa, Hala; El-Hadidi, Omaia S.

    2015-09-01

    The results of an experimental program conducted on seventeen simply supported concrete beams to study the effect of transverse reinforcement on the behavior of the lap splice of a steel reinforcement in tension zones in high-strength concrete beams are presented. The parameters included in the experimental program were the concrete compressive strength, the lap splice length, the amount of transverse reinforcement provided within the splice region, and the shape of the transverse reinforcement around the spliced bars. The experimental results showed that the displacement ductility increased and the mode of failure changed from a splitting bond failure to a flexural failure when the amount of the transverse reinforcement in the splice region increased, and the compressive strength increased up to 100 MPa. The presence of the transverse reinforcement around the spliced bars had a pronounced effect on increasing the ultimate load, the ultimate deflection, and the displacement ductility. The prediction of maximum steel stresses for spliced bars using the ACI 318-05 building code was compared with the experimental results. The comparison showed that the effect of the transverse reinforcement around spliced bars has to be considered into the design equations for lap splice length in high-strength concrete beams.

  18. Time-Dependent Behavior of High-Strength Kevlar and Vectran Webbing

    Science.gov (United States)

    Jones, Thomas C.; Doggett, William R.

    2014-01-01

    High-strength Kevlar and Vectran webbings are currently being used by both NASA and industry as the primary load-bearing structure in inflatable space habitation modules. The time-dependent behavior of high-strength webbing architectures is a vital area of research that is providing critical material data to guide a more robust design process for this class of structures. This paper details the results of a series of time-dependent tests on 1-inch wide webbing including an initial set of comparative tests between specimens that underwent realtime and accelerated creep at 65 and 70% of their ultimate tensile strength. Variability in the ultimate tensile strength of the webbings is investigated and compared with variability in the creep life response. Additional testing studied the effects of load and displacement rate, specimen length and the time-dependent effects of preconditioning the webbings. The creep test facilities, instrumentation and test procedures are also detailed. The accelerated creep tests display consistently longer times to failure than their real-time counterparts; however, several factors were identified that may contribute to the observed disparity. Test setup and instrumentation, grip type, loading scheme, thermal environment and accelerated test postprocessing along with material variability are among these factors. Their effects are discussed and future work is detailed for the exploration and elimination of some of these factors in order to achieve a higher fidelity comparison.

  19. Prediction of compression strength of high performance concrete using artificial neural networks

    Science.gov (United States)

    Torre, A.; Garcia, F.; Moromi, I.; Espinoza, P.; Acuña, L.

    2015-01-01

    High-strength concrete is undoubtedly one of the most innovative materials in construction. Its manufacture is simple and is carried out starting from essential components (water, cement, fine and aggregates) and a number of additives. Their proportions have a high influence on the final strength of the product. This relations do not seem to follow a mathematical formula and yet their knowledge is crucial to optimize the quantities of raw materials used in the manufacture of concrete. Of all mechanical properties, concrete compressive strength at 28 days is most often used for quality control. Therefore, it would be important to have a tool to numerically model such relationships, even before processing. In this aspect, artificial neural networks have proven to be a powerful modeling tool especially when obtaining a result with higher reliability than knowledge of the relationships between the variables involved in the process. This research has designed an artificial neural network to model the compressive strength of concrete based on their manufacturing parameters, obtaining correlations of the order of 0.94.

  20. Simulation about hot stamping of ultra-high strength steel on the basis of lightweight technology

    Institute of Scientific and Technical Information of China (English)

    Liu Qiang; Ma Fangwu; Wang Xiaona; Yao Zaiqi; Song Wei; Zhao Fuquan; Ma Mingttu; Song Leifeng

    2012-01-01

    With the development of automobile lightweight, it is very necessary to apply the ultra-high strength steel parts manufactured by hot stamping, which offers the possibility to reduce the weight of automobiles and maintain the safety requirement. In order to complete hot stamping, it is important to design the structure of parts reasonably, which is related with reasonable matching of strength. The objective of this paper is to guide the design of parts manufactured by hot stamping and find the forming technical requirements of vehicle performance. Through experiments, the paper obtains the stress and strain curves at different deformation temperatures and strain rates. Based on experimental data, the constitutive relationship model is established which can reflect the deformation capacity of ultra-high strength steel during the process of hot stamping. Combined with finite element simulation results of hot stamping by commercial soft- ware AUTOFORM, transfer path of load and matching law of strength, the paper determines the design criteria and forming technical requirements of parts manufactured by hot stamping. At the same time, the impact performance of front cross member internal plate is taken into consideration.

  1. Effect of microstructure on the impact toughness of high strength steels

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, I.

    2014-07-01

    One of the major challenges in the development of new steel grades is to get increasingly high strength combined with a low ductile brittle transition temperature and a high upper shelf energy. This requires the appropriate microstructural design. Toughness in steels is controlled by different microstructural constituents. Some of them, like inclusions, are intrinsic while others happening at different microstructural scales relate to processing conditions. A series of empirical equations express the transition temperature as a sum of contributions from substitutional solutes, free nitrogen, carbides, pearlite, grain size and eventually precipitation strengthening. Aimed at developing a methodology that could be applied to high strength steels, microstructures with a selected degree of complexity were produced at laboratory in a Nb-microalloyed steel. As a result a model has been developed that consistently predicts the Charpy curves for ferrite-pearlite, bainitic and quenched and tempered microstructures using as input data microstructural parameters. This model becomes a good tool for microstructural design. (Author)

  2. Thermal poling of alkaline earth boroaluminosilicate glasses with intrinsically high dielectric breakdown strength

    Science.gov (United States)

    Smith, Nicholas J.; Lanagan, Michael T.; Pantano, Carlo G.

    2012-04-01

    Per the rectification model of thermal poling, it has been proposed that intrinsic breakdown strength plays a strong limiting role in the internal DC fields supported by the glass from the poling process. One might therefore hypothesize proportionately larger second-order nonlinearity (SON) in glasses with intrinsically high dielectric breakdown strength. We test these ideas by thermal poling of two different commercial alkali-free alkaline-earth boroaluminosilicate display glasses—one with barium only (AF45 from Schott), and the other with a mixture of alkaline-earth ions (OA-10 G from NEG). Not only are such compositions relevant from a commercial standpoint, they are also interesting in that they have been recently shown to exhibit remarkably high intrinsic dielectric breakdown strengths of 11-14 MV/cm. Quantitative Maker fringe and stack Maker-fringe measurements provide an accurate evaluation of the poling-induced SON susceptibilities, and indicate maximum χ(2) values of 0.44 and 0.26 pm/V in these glasses. These values are comparable to those reported for silica and other multicomponent glasses. Thus, the hypothesis that higher χ(2) would be observed in high intrinsic breakdown strength glasses was not validated. Based on our application of the rectification model, internal fields of the order 2-4 MV/cm were calculated, which are well below the measured intrinsic breakdown strengths at room temperature. The most plausible explanation for these observations is nonlinear electronic conduction effects taking place within the depletion region at the poling temperature, limiting internal fields to a fraction of the breakdown field.

  3. Study of the Tensile Damage of High-Strength Aluminum Alloy by Acoustic Emission

    Directory of Open Access Journals (Sweden)

    Chang Sun

    2015-11-01

    Full Text Available The key material of high-speed train gearbox shells is high-strength aluminum alloy. Material damage is inevitable in the process of servicing. It is of great importance to study material damage for in-service gearboxes of high-speed train. Structural health monitoring methods have been widely used to study material damage in recent years. This study focuses on the application of an acoustic emission (AE method to quantify tensile damage evolution of high-strength aluminum alloy. First, a characteristic parameter was developed to connect AE signals with tensile damage. Second, a tensile damage quantification model was presented based on the relationship between AE counts and tensile behavior to study elastic deformation of tensile damage. Then tensile tests with AE monitoring were employed to collect AE signals and tensile damage data of nine samples. The experimental data were used to quantify tensile damage of high-strength aluminum alloy A356 to demonstrate the effectiveness of the proposed method.

  4. Effects of high NH4+ on K+ uptake, culm mechanical strength and grain filling in wheat

    Directory of Open Access Journals (Sweden)

    Lingan eKong

    2014-12-01

    Full Text Available It is well established that a high external NH4+ concentration depresses many processes in plant development, but the underlying mechanisms are still not well understood. To determine whether the negative effects of high levels of NH4+ are related to competitive cation uptake, wheat was grown in a field with moderate (18 g N m-2 and high (30 g N m-2 supplies of NH4+ in the presence or absence of additional K+ (6 g K2O m-2 to examine culm mechanical strength, the main components of the vascular bundle, nitrogen (N remobilization and the grain-filling rate. The results indicated that an excessive supply of NH4+ significantly decreased culm mechanical strength, the cellulose and lignin contents of vascular bundles, the N remobilization efficiency (NRE and the grain-filling rate compared with a moderate level of NH4+. The additional provision of K+ considerably alleviated these negative effects of high NH4+, resulting in a 19.41%-26.95% increase in culm mechanical strength during grain filling and a 34.59% increase in the NRE. An assay using the scanning ion-selective electrode technique (SIET showed that the net rate of transmembrane K+ influx decreased by 84.62%, and measurements using flame photometry demonstrated that the K+ content decreased by 36.13% in wheat plants subjected to high NH4+. This study indicates that the effects of high NH4+ on culm mechanical strength, cellulose and lignin contents, the NRE and the grain-filling rate are probably associated with inhibition of K+ uptake in wheat.

  5. Process for making a high toughness-high strength iron alloy

    Science.gov (United States)

    Stephens, J. R.; Witzke, W. R. (Inventor)

    1979-01-01

    A steel alloy is produced by a process which includes using cold rolling at room temperature and subsequent heat treatment at temperatures ranging from 500 C to 650 C. The resulting alloys exhibits excellent strength and toughness characteristics at cryogenic temperatures. This alloy consists essentially of about 10 to 16 percent by weight nickel, to about 1.0 percent by weight aluminum, and 0 to about 3 percent by weight of at least one of the following additional elements: copper, lanthanum, niobium, tantalum, titanium, vanadium, yttrium, zirconium and the rare earth metals, with the balance being essentially iron. The improved alloy possesses a fracture toughness ranging from 200 to 230 ksi sq in. and yield strengths up to 230 ksi.

  6. Temperature and strain rate effects in high strength high conductivity copper alloys tested in air

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, D.J. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    The tensile properties of the three candidate alloys GlidCop{trademark} Al25, CuCrZr, and CuNiBe are known to be sensitive to the testing conditions such as strain rate and test temperature. This study was conducted on GlidCop Al25 (2 conditions) and Hycon 3HP (3 conditions) to ascertain the effect of test temperature and strain rate when tested in open air. The results show that the yield strength and elongation of the GlidCop Al25 alloys exhibit a strain rate dependence that increases with temperature. Both the GlidCop and the Hycon 3 HP exhibited an increase in strength as the strain rate increased, but the GlidCop alloys proved to be the most strain rate sensitive. The GlidCop failed in a ductile manner irrespective of the test conditions, however, their strength and uniform elongation decreased with increasing test temperature and the uniform elongation also decreased dramatically at the lower strain rates. The Hycon 3 HP alloys proved to be extremely sensitive to test temperature, rapidly losing their strength and ductility when the temperature increased above 250 C. As the test temperature increased and the strain rate decreased the fracture mode shifted from a ductile transgranular failure to a ductile intergranular failure with very localized ductility. This latter observation is based on the presence of dimples on the grain facets, indicating that some ductile deformation occurred near the grain boundaries. The material failed without any reduction in area at 450 C and 3.9 {times} 10{sup {minus}4} s{sup {minus}1}, and in several cases failed prematurely.

  7. Sleep monitoring of a six-day microcycle in strength and high-intensity training.

    Science.gov (United States)

    Kölling, Sarah; Wiewelhove, Thimo; Raeder, Christian; Endler, Stefan; Ferrauti, Alexander; Meyer, Tim; Kellmann, Michael

    2016-08-01

    This study examined the effect of microcycles in eccentric strength and high-intensity interval training (HIT) on sleep parameters and subjective ratings. Forty-two well-trained athletes (mean age 23.2 ± 2.4 years) were either assigned to the strength (n = 21; mean age 23.6 ± 2.1 years) or HIT (n = 21; mean age 22.8 ± 2.6 years) protocol. Sleep monitoring was conducted with multi-sensor actigraphy (SenseWear Armband™, Bodymedia, Pittsburg, PA, USA) and sleep log for 14 days. After a five-day baseline phase, participants completed either eccentric accented strength or high-intensity interval training for six days, with two training sessions per day. This training phase was divided into two halves (part 1 and 2) for statistical analyses. A three-day post phase concluded the monitoring. The Recovery-Stress Questionnaire for Athletes was applied at baseline, end of part 2, and at the last post-day. Mood ratings were decreased during training, but returned to baseline values afterwards in both groups. Sleep parameters in the strength group remained constant over the entire process. The HIT group showed trends of unfavourable sleep during the training phase (e.g., objective sleep efficiency at part 2: mean = 83.6 ± 7.8%, F3,60 = 2.57, P = 0.06, [Formula: see text] = 0.114) and subjective improvements during the post phase for awakenings (F3,60 = 2.96, P = 0.04, [Formula: see text] = 0.129) and restfulness of sleep (F3,60 = 9.21, P strength training, and sufficient sleep time should be emphasised and monitored.

  8. Evaluation of susceptibility of high strength steels to hydrogen delayed cracking

    Directory of Open Access Journals (Sweden)

    B. Świeczko-Żurek

    2006-08-01

    Full Text Available Purpose: Purpose of this paper is evaluation of susceptibility of high-strength structural steels to hydrogendelayed cracking.Design/methodology/approach: Susceptibility to hydrogen delayed cracking of high-strength alloy steels havebeen made under constant load in hydrogen generating environments. Test were carried out using round notchedspecimens subjected to axial tensile load being equivalence to 75-96% of maximum force obtained from atensile tests in air. Two constructional middle carbon steel – grades 26H2MF and 34HNM were tested in used(worn out mineral engine oil at temperature of 80°C. One low carbon weldable steel grade – 14HNMBCu wasinvestigated in sea-water under cathodic polarization at room temperature. Presence or lack of cracking within200 hours was chosen as a measure of susceptibility to hydrogen delayed cracking. Fracture modes of failedsamples were examined with the use of scanning electron microscope.Findings: All tested steels reveal high resistance to hydrogen degradation under constant load. Hydrogendelayed cracking does not occur until the load level is as high as flow stress (yield strength.Research limitations/implications: Further research should be taken to reveal the exact mechanism of crackinitiation.Practical implications: Tested steels could be safely utilized within elastic range of stress in hydrogengenerating environments.Originality/value: Under the critical load and hydrogen concentration notched samples premature failed andhydrogen-enhanced localised plasticity (HELP model is a viable degradation mechanism.

  9. [Strength and transparency of dental porcelain consisting of high refractive germanate-glass and alumina crystal].

    Science.gov (United States)

    Kon, M

    1990-07-01

    A translucent aluminous porcelain was developed for dentistry. The effects of refractive indexes and sintering behaviors on transparency and strength of the aluminous porcelains consisting of high refractive germanate-glass (Na2O-TiO2-GeO2) and alumina crystal powders were examined. The various germanate-glass specimens with a high refractive index were made by fusion at about 1,300 degrees C. The refractive indexes of fused Na2O-TiO2-GeO2 glass specimens were 1.64-1.76, heightened with an increasing TiO2 content. The sintered aluminous porcelains were made from the mixed compacts consisting of 80 wt% germanate-glass and 20 wt% alumina at the densification temperature of 580-820 degrees C. Sintered aluminous porcelains prepared with high refractive germante-glass had a high transparency compared with the other aluminous porcelains, with almost the same transparency as a commercial feldspathic porcelain (body). Aluminous porcelains had lower transparency with different refractive index due to generation of crystals following the crystallization of glass matrix than that without crystallizing property. Bending strength value was 120 MPa, which is similar to that for the glass-alumina ceramics with the same content of alumina volume as germanate-glass aluminous porcelains. Non-crystallized aluminous porcelain had a higher strength compared with the crystallized one.

  10. A low-cost hierarchical nanostructured beta-titanium alloy with high strength

    Science.gov (United States)

    Devaraj, Arun; Joshi, Vineet V.; Srivastava, Ankit; Manandhar, Sandeep; Moxson, Vladimir; Duz, Volodymyr A.; Lavender, Curt

    2016-01-01

    Lightweighting of automobiles by use of novel low-cost, high strength-to-weight ratio structural materials can reduce the consumption of fossil fuels and in turn CO2 emission. Working towards this goal we achieved high strength in a low cost β-titanium alloy, Ti–1Al–8V–5Fe (Ti185), by hierarchical nanostructure consisting of homogenous distribution of micron-scale and nanoscale α-phase precipitates within the β-phase matrix. The sequence of phase transformation leading to this hierarchical nanostructure is explored using electron microscopy and atom probe tomography. Our results suggest that the high number density of nanoscale α-phase precipitates in the β-phase matrix is due to ω assisted nucleation of α resulting in high tensile strength, greater than any current commercial titanium alloy. Thus hierarchical nanostructured Ti185 serves as an excellent candidate for replacing costlier titanium alloys and other structural alloys for cost-effective lightweighting applications. PMID:27034109

  11. MODIFICATION THE CEMENTIOUS MATERIAL OF ULTRA-HIGH-STRENGTH SLEEPER CONCRETE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper presents investigation results on the natural ultra-fine mineral flour of crystalline silica fume (CSF) and porous quartz sand stone (PQSS) which can modify cement mortar strength under hydrothermal synthesis reaction (HSR) in the autoclave-cured condition. The replacement of cement by CSF and PQSS can significantly increase the flexural and compressive strength,which reach 22MPa and 150MPa respectively ,and decrease the porosity of the cement mortar. The ratio of fine aggregation, standard sand to cementious material has significant influence on the mortar strength. The mechanisms involved in cement and natural mineral flour and the HSR are presented. CaO/SiO2 ratio ranges from 3.20 to 1.11, the main hydrate phase is C2SH and there is not Tobermorite through X-Ray diffraction qualitative analysis. The new and ultra-high strength cementious material as basic material of sleeper concrete can be used in prestressed reinforcement sleeper concrete.

  12. Ultrasonic Analysis of Cracking Propagation Morphology in the Fusion Zone of High Strength Steel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Cracking morphology in the fusion zone of HQ130 high strength steel was researched by "the y-slit test" and "three-point bend test", ultrasonic test and microscope. HQ130 and Q J63 high strength steel was welded by Ar+CO2 gasshielded arc welding under the condition without preheating. Experimental results indicated that welding cracks wereproduced in the partially melted zone of the weld root of HQ130 steel side and propagated parallel to the fusionzone. The cracks were developed alternatively between the weld and the partially melted zone, and are not strictlyruptured at W/F (weld metal/fusion zone) boundary surface. Controlling weld heat input (E) about 16 k J/cm couldmake the cracking rate lowest and satisfy the performance requirement of welded joint zone.

  13. End boundary effects on local buckling response of high strength linepipe

    Energy Technology Data Exchange (ETDEWEB)

    Fatemi, Ali [IMV Projects Atlantic and Memorial University of Newfoundland (Canada); Kenny, Shawn [Memorial University of Newfoundland (Canada); Taheri, Farid [Dalhousie University (Canada); Duan, Da-Ming; Zhou, Joe [TransCanada PipeLines (Canada)

    2010-07-01

    In the natural gas sector, when long distance transportation of large volumes is required, high strength pipelines are usually used, due to their economic benefits. These pipelines are often installed in harsh environments with high strain conditions and limit state functions need to be set up. The aim of this paper is to study the length to diameter ratio effect on the local buckling response. In order to predict the local buckling response, a model was developed with ABAQUS/Standard, a finite element software, and was adjusted with experimental data. Results showed that conventional methods might not be completely accurate when determining compressive strength limits for short pipeline segments while the model developed herein showed a good prediction. This study highlighted the limits of current methods and showed that end effects on the local buckling response must be addressed; the calibrated finite element model developed can mitigate it but needs further validation.

  14. Statistical Tensile Strength for High Strain Rate of Aramid and UHMWPE Fibers

    Institute of Scientific and Technical Information of China (English)

    YANG Bin; XIONG Tao; XIONG Jie

    2006-01-01

    Dynamic tensile impact properties of aramid (Technora(R)) and UHMWPE (DC851) fiber bundles were studied at two high strain rates by means of reflecting type Split Hopkinson Bar, and stress-strain curves of fiber yarns at different strain rates were obtained. Experimental results show that the initial elastic modulus, failure strength and unstable strain of aramid fiber yarns are strain rate insensitive, whereas the initial elastic modulus and unstable strain of UHMWPE fiber yarns are strain rate sensitive. A fiber-bundle statistical constitutive equation was used to describe the tensile behavior of aramid and UHMWPE fiber bundles at high strain rates. The good consistency between the simulated results and experimental data indicates that the modified double Weibull function can represent the tensile strength distribution of aramid and UHMWPE fibers and the method of extracting Weibull parameters from fiber bundles stress-strain data is valid.

  15. High-resolution dipole (e, e) study for optical oscillator strengths of helium

    Institute of Scientific and Technical Information of China (English)

    凤任飞; 杨炳忻; 武淑兰; 邢士林; 张芳; 钟志萍; 郭学哲; 徐克尊

    1996-01-01

    The optical oscillator strengths of helium have been studied by a high-resolution dipole (e, e) method on the recently built high-resolution fast-electron energy-loss spectrometer. The difficulties of optical measurement have been avoided and the experimental precision has been improved by using this method. The optical oscillator strength density spectrum corresponding to the 1S n’P transitions and ionization of helium has been measured in the energy loss range of 21 - 26 eV. And the same work corresponding to the autoionization resonance region has been done in energy loss ranges of 59-67 eV and 69-74 eV. The above results have also been compared with those of the previous work.

  16. Microstructural evolution of high strength 7B04 ingot during homogenization treatment

    Institute of Scientific and Technical Information of China (English)

    LI Nian-kui; CUI Jian-zhong

    2008-01-01

    The evolution of the microstructure and phases of the direct chill semicontinuous casting ingot of 7B04 super-high strength aluminum alloy during homogenization treatment was studied with metallographic analysis, scanning electron microscopy(SEM), energy spectroscopy and differential scanning calorimetry(DSC). The results show that a considerable amount of non-equilibrium eutectics containing Al, Zn, Cu and Mg exist in the direct chill semicontinuous casting ingot of 7B04 super-high strength aluminum alloy, and their melting point is 478 ℃. During homogenization treatment at 470 ℃, these eutectics dissolve into the matrix partly, coarsen and also transform into Al2CuMg phase whose equilibrium melting point is 490 ℃ in the alloy. Moreover, the homogenization treatment at 470 ℃ for 72 h results in the disappearance of the non-equilibrium eutectics though Al2CuMg phase can not dissolve completely.

  17. Forming of High-strength Steels Using a Hot-melt Dry Lubricant

    DEFF Research Database (Denmark)

    Hörnström, Sven-Erik; Karlsson, Erik; Olsson, Mikael

    2008-01-01

    steel grades and improved surface engineering treatments such as the deposition of low friction CVD and PVD coatings. In the present study the performance of a hot-melt dry lubricant in the forming of hot and cold rolled and hot-dip galvanized high strength steel has been evaluated and compared...... with a conventional rust protection oil using four different tests methods, i.e. a strip reduction test, a bending under tension test, a stretch-forming test and a pin-on disc test. In the tests, two different cold work tool steels, a conventional steel grade and a nitrogen alloyed PM steel grade were evaluated......The increasing use of high strength steels in a variety of mechanical engineering applications has illuminated problems associated with galling in sheet metal forming operations. Galling is a tribological phenomenon associated with transfer of material from the steel sheet to the tool surface...

  18. Fatigue behavior of press hardened Al-Si coated high strength steel

    Institute of Scientific and Technical Information of China (English)

    Wang Zijian; Gui Zhongxiang; Zhang Yisheng

    2014-01-01

    The fatigue behavior of press hardened Al-Si coated high strength steel has been investigated,and the fatigue strength turns out to be about 1 000 MPa. Surface morphology of fractured and non-fractured speci-men has been observed,and the coating shows significant influence on the fatigue behavior. The difference of elastic modulus between coating and substrate led to the main cracks perpendicular to the loading direction. The coating close to fracture exfoliated thinly,while the coating far away from the fracture kept integrated. Though the specimen was polished to obtain high surface quality,3 types of cracks occurred during the fatigue test. What’s more,inclusion particles were proved to play a crucial role in causing these cracks.

  19. Load carrying capacity of shear wall t-connections reinforced with high strength wire ropes

    DEFF Research Database (Denmark)

    Jørgensen, Henrik B.; Bryndom, Thor; Larsen, Michael

    2016-01-01

    Traditionally, U-bar loop connections with keyed joints have been used in vertical shear connections between precast concrete wall elements. However, in the recent years, connections with looped high strength wire ropes instead of U-bar loops have proven to be a much more construction......-friendly solution. The wire ropes have no bending stiffness and therefore allow for an easier vertical installation of the wall elements. During the last 10 – 15 years, a number of shear tests on plane wire rope connections have been carried out. However, to the best knowledge of the authors, tests on wire rope...... connections for assembly of precast elements in different planes, such as T- and L-connections, have not yet been published. This paper presents the results of a large test series recently conducted at the University of Southern Denmark to study the shear behaviour of high strength wire rope T...

  20. Load Carrying Capacity of Shear Wall T-Connections Reinforced with High Strength Wire Ropes

    DEFF Research Database (Denmark)

    Jørgensen, Henrik Brøner; Bryndum, Thor; Larsen, Michael

    2017-01-01

    Traditionally, U-bar loop connections with keyed joints have been used in vertical shear connections between precast concrete wall elements. However, in the recent years, connections with looped high strength wire ropes instead of U-bar loops have proven to be a much more construction......-friendly solution. The wire ropes have no bending stiffness and therefore allow for an easier vertical installation of the wall elements. During the last 10 – 15 years, a number of shear tests on plane wire rope connections have been carried out. However, to the best knowledge of the authors, tests on wire rope...... connections for assembly of precast elements in different planes, such as T- and L-connections, have not yet been published. This paper presents the results of a large test series recently conducted at the University of Southern Denmark to study the shear behaviour of high strength wire rope T...

  1. Finite element analysis of residual stress in the welded zone of a high strength steel

    Indian Academy of Sciences (India)

    Li Yajiang; Wang Juan; Chen Maoai; Shen Xiaoqin

    2004-04-01

    The distribution of the residual stress in the weld joint of HQ130 grade high strength steel was investigated by means of finite element method (FEM) using ANSYS software. Welding was carried out using gas shielded arc welding with a heat input of 16 kJ/cm. The FEM analysis on the weld joint reveals that there is a stress gradient around the fusion zone of weld joint. The instantaneous residual stress on the weld surface goes up to 800 ∼ 1000 MPa and it is 500 ∼ 600 MPa, below the weld. The stress gradient near the fusion zone is higher than any other location in the surrounding area. This is attributed as one of the significant reasons for the development of cold cracks at the fusion zone in the high strength steel. In order to avoid such welding cracks, the thermal stress in the weld joint has to be minimized by controlling the weld heat input.

  2. Development of Nb-V-Ti Hot-Rolled High Strength Steel With Fine Ferrite and Precipitation Strengthening

    Institute of Scientific and Technical Information of China (English)

    YI Hai-long; DU Lin-xiu; WANG Guo-dong; LIU Xiang-hua

    2009-01-01

    A hot-rolled steel with high yield strength of 700 MPa, good elongation of about 20% and low ductile-brittle transition temperature (DBTT) lower than-70℃ has been developed in laboratory. The results show that adopting finishing rolling temperature of around 800 ℃ is rational, and coiling temperature is between 400 and 500℃. The strength of developed 700 MPa hot-rolled high strength steel is derived from the cumulative contribution of fine grain size, dislocation hardening and precipitation hardening. The fine grain strengthening and precipitation hardening are the dominant factors responsible for such high strength, and good elongation and toughness are predominantly due to fine grain ferrite.

  3. Prediction of failure strain and burst pressure in high yield-to-tensile strength ratio linepipe

    Energy Technology Data Exchange (ETDEWEB)

    Law, M. [Institute of Materials and Engineering Science, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW (Australia)]. E-mail: mlx@ansto.gov.au; Bowie, G. [BlueScope Steel Ltd., Level 11, 120 Collins St, Melbourne, Victoria 3000 (Australia)

    2007-08-15

    Failure pressures and strains were predicted for a number of burst tests as part of a project to explore failure strain in high yield-to-tensile strength ratio linepipe. Twenty-three methods for predicting the burst pressure and six methods of predicting the failure strain are compared with test results. Several methods were identified which gave accurate and reliable estimates of burst pressure. No method of accurately predicting the failure strain was found, though the best was noted.

  4. Stress corrosion cracking and hydrogen embrittlement of thick section high strength low alloy steel.

    OpenAIRE

    Needham, William Donald

    1986-01-01

    An experimental study was conducted to evaluate the corrosion performance of weldments of a high strength low alloy(HSLA) steel in a simulated seawater environment. This steel, designated HSLA80, was developed by the United States Navy for use in ship structural applications. Stress corrosion CRACKING(SCC) and hydrogen embrittlement(HEM) were investigated by conducting 42 Wedge-Opening load(WOL) tests as a function of stress intensity and corrosion potential and 33 Slow Strain Rate(SSR) tests...

  5. Perceived Strengths and Weaknesses of Highly Realistic Training and Live Tissue Training for Navy Corpsmen

    Science.gov (United States)

    2015-04-08

    medical populations, such as physicians, nurses , and Navy Fleet Surgical Teams. This training could be adapted and used to help newly formed...6. Hoang T, Kang J, LaPorta A, Makler V, Chalut C: Filling in the gaps of predeployment fleet surgical team training using a team- centered ...Naval Health Research Center Perceived Strengths and Weaknesses of Highly Realistic Training and Live Tissue Training for Navy Corpsmen Stephanie

  6. Improving uv resistance of high strength fibers used in large scientific balloons

    Science.gov (United States)

    Said, M.; Gupta, A.; Seyam, A.; Mock, G.; Theyson, T.

    For the last three decades, NASA has been involved in the development of giant balloons that are capable of lifting heavy payloads of equipment (such as large telescopes and scientific instruments) to the upper atmosphere. While the use of such balloons has led to scientific discoveries, the demand for competitive science payloads and observational programs continues to rise. The NASA Balloon Program Office has entered a new phase of research to develop an Ultra Long Duration Balloon (ULDB) that will lift payloads of up to 3,600 kg to altitudes of up to 40 km. The flight duration is targeted to ranges between 30 to 100 days. Attaining these target durations requires the development of a super-pressure balloon design. The use of textile structures have already been established in these missions in the form of high strength tendons essential for the super pressure pumpkin design. Unfortunately, high strength fibers lose significant strength upon exposure to Ultra Violet (UV) radiation. Such UV degradation poses a serious challenge for the development of the ULDB. To improve the mission performance of the ULDB, new methods for protecting the tendons from the environmental effects need to be developed. NASA and NC State University College of Textiles are undertaking a research program to address these issues. Four tracks have been identified to prepare finishes that are believed to enhance the resistance of high strength fibers to UV. These tracks are: (a) self-polymerizing, (b) diffusion application, (c) polymer-filled with 30-40% UV absorber, and (d) combination of dyeing plus surface application. Four high performance fibers have been selected for this research investigation. These are Vectran, Spectra, Kevlar and, PBO (Zylon). This work will address the current progress of evaluating the performance of the UV finishes. This will be accomplished by comparing the tensile properties (strenthg, breaking elongation, modulus, etc) of untreated, unexposed to UV fibers

  7. Structural Changes Under Heat Treatment of High-Strength Cast Iron with Globular Graphite

    Science.gov (United States)

    Tsukanov, V. V.; Ziza, A. I.; Mikhailov, M. S.; Tsyganko, L. K.; Shandyba, G. A.

    2016-11-01

    High-strength cast iron of grade VCh50 with globular graphite is studied after isothermal quenching in the bainitic and martensitic ranges. The mechanical properties of the iron and the hardness of its structural components are determined. The fine structure of the iron with bainitic and martensitic matrix is studied. The effect of the tempering temperature after the isothermal quenching on the hardness and structure of the iron is estimated.

  8. Sound velocity of high-strength polymer with negative thermal expansion coefficient

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, R.; Ueno, M.; Okuda, Y.; Burmistrov, S.; Yamanaka, A

    2003-05-01

    Sound velocities of fiber reinforced plastics (FRPs) were measured along the fiber axis at temperatures between 360 and 77 K. We used two kinds of the high-strength crystalline polymer fibers, polyethylene (Dyneema) and polybenzobisoxazole (Zylon), which have negative thermal expansion coefficients. They also have high thermal conductivities and high resistances for flash over voltage, and are expected as new materials for coil bobbins or spacers at cryogenic temperatures. They have very large sound velocities of about 9000 (m/s) at 77 K, which are 4.5 times larger than that of the ordinary polyethylene fiber.

  9. Recent Advances in Ultra-High-Speed Optical Signal Processing

    DEFF Research Database (Denmark)

    Mulvad, Hans Christian Hansen; Palushani, Evarist; Hu, Hao;

    2012-01-01

    We review recent advances in the optical signal processing of ultra-high-speed serial data signals up to 1.28 Tbit/s, with focus on applications of time-domain optical Fourier transformation. Experimental methods for the generation of symbol rates up to 1.28 Tbaud are also described....

  10. Understanding advanced theory of mind and empathy in high-functioning adults with autism spectrum disorder.

    Science.gov (United States)

    Mathersul, Danielle; McDonald, Skye; Rushby, Jacqueline A

    2013-01-01

    It has been argued that higher functioning individuals with autism spectrum disorders (ASDs) have specific deficits in advanced but not simple theory of mind (ToM), yet the questionable ecological validity of some tasks reduces the strength of this assumption. The present study employed The Awareness of Social Inference Test (TASIT), which uses video vignettes to assess comprehension of subtle conversational inferences (sarcasm, lies/deception). Given the proposed relationships between advanced ToM and cognitive and affective empathy, these associations were also investigated. As expected, the high-functioning adults with ASDs demonstrated specific deficits in comprehending the beliefs, intentions, and meaning of nonliteral expressions. They also had significantly lower cognitive and affective empathy. Cognitive empathy was related to ToM and group membership whereas affective empathy was only related to group membership.

  11. Testing of High Thermal Cycling Stability of Low Strength Concrete as a Thermal Energy Storage Material

    Directory of Open Access Journals (Sweden)

    Chao Wu

    2016-09-01

    Full Text Available Concrete has the potential to become a solution for thermal energy storage (TES integrated in concentrating solar power (CSP systems due to its good thermal and mechanical properties and low cost of material. In this study, a low strength concrete (C20 is tested at high temperatures up to 600 °C. Specimens are thermally cycled at temperatures in the range of 400–300 °C, 500–300 °C, and 600–300 °C, which TES can reach in operation. For comparison, specimens also cycled at temperature in the range of 400–25 °C (room temperature, 500–25 °C, and 600–25 °C. It is found from the test results that cracks are not observed on the surfaces of concrete specimens until the temperature is elevated up to 500 °C. There is mechanical deterioration of concrete after exposure to high temperature, especially to high thermal cycles. The residual compressive strength of concrete after 10 thermal cycles between 600 °C and 300 °C is about 58.3%, but the specimens remain stable without spalling, indicating possible use of low strength concrete as a TES material.

  12. Nitrate removal from high strength nitrate-bearing wastes in granular sludge sequencing batch reactors.

    Science.gov (United States)

    Krishna Mohan, Tulasi Venkata; Renu, Kadali; Nancharaiah, Yarlagadda Venkata; Satya Sai, Pedapati Murali; Venugopalan, Vayalam Purath

    2016-02-01

    A 6-L sequencing batch reactor (SBR) was operated for development of granular sludge capable of denitrification of high strength nitrates. Complete and stable denitrification of up to 5420 mg L(-1) nitrate-N (2710 mg L(-1) nitrate-N in reactor) was achieved by feeding simulated nitrate waste at a C/N ratio of 3. Compact and dense denitrifying granular sludge with relatively stable microbial community was developed during reactor operation. Accumulation of large amounts of nitrite due to incomplete denitrification occurred when the SBR was fed with 5420 mg L(-1) NO3-N at a C/N ratio of 2. Complete denitrification could not be achieved at this C/N ratio, even after one week of reactor operation as the nitrite levels continued to accumulate. In order to improve denitrification performance, the reactor was fed with nitrate concentrations of 1354 mg L(-1), while keeping C/N ratio at 2. Subsequently, nitrate concentration in the feed was increased in a step-wise manner to establish complete denitrification of 5420 mg L(-1) NO3-N at a C/N ratio of 2. The results show that substrate concentration plays an important role in denitrification of high strength nitrate by influencing nitrite accumulation. Complete denitrification of high strength nitrates can be achieved at lower substrate concentrations, by an appropriate acclimatization strategy.

  13. RESIDUAL FLEXURAL STRENGTH OF RECYCLED BRICK AGGREGATE CONCRETE EXPOSED TO HIGH TEMPERATURES

    Directory of Open Access Journals (Sweden)

    Kasi Rekha

    2015-12-01

    Full Text Available The practice of using crushed brick in concrete is picking up due to its value addition to the mechanical properties of concrete. In the present experimental investigation the brick from the demolition waste is used as a coarse aggregate to study the flexural behaviour of recycled brick aggregate (RBA concrete after exposure to high temperatures. The recycled brick aggregate is replaced to granite aggregate up to 25% by its volume to produce RBA concrete. Beam specimens of size 100mm × 100mm × 500mm were used to study the flexural strength (modulus of rupture of both RBA concrete and granite aggregate (GA concrete. Both the concretes were heated to desired temperatures from 100oC to 1000oC in an interval of 100oC for three hours in bogie hearth furnace. The residual flexural strengths of both heated RBA and GA concretes were presented in this research to study the performance of RBAconcrete at high temperatures. The RBA concrete performed better than that of GA concrete in flexure at high temperatures by exhibiting higher residual strength.

  14. Hollow-fiber membrane bioreactor for the treatment of high-strength landfill leachate

    KAUST Repository

    Rizkallah, Marwan

    2013-07-15

    Performance assessment of membrane bioreactor (MBR) technology for the treatability of high-strength landfill leachate is relatively limited or lacking. This study examines the feasibility of treating high-strength landfill leachate using a hollow-fiber MBR. For this purpose, a laboratory-scale MBR was constructed and operated to treat leachate with a chemical oxygen demand (COD) of 9000-11,000 mg/l, a 5-day biochemical oxygen demand (BOD5) of 4000-6,000 mg/l, volatile suspended solids (VSS) of 300-500 mg/l, total nitrogen (TN) of 2000-6000 mg/l, and an ammonia-nitrogen (NH3-N) of 1800-4000 mg/l. VSS was used with the BOD and COD data to simulate the biological activity in the activated sludge. Removal efficiencies > 95-99% for BOD5, VSS, TN and NH3-N were attained. The coupled experimental and simulation results contribute in filling a gap in managing high-strength landfill leachate and providing guidelines for corresponding MBR application. © The Author(s) 2013.

  15. Investigation on Friction and Wear of Cold Rolled High Strength Steel against an AISI52100 Counterpart

    Directory of Open Access Journals (Sweden)

    Jiwon Hur

    2017-03-01

    Full Text Available This article investigates the friction and wear of cold rolled high strength steel at various displacement amplitudes. Reciprocal sliding tests are carried out using a ball-on-flat testing apparatus. The tangential force occurring at the contact surface between a high strength steel specimen and an AISI52100 ball is measured during the tests. After each test, the worn surface profile on the steel specimen is determined. Experimental results show that the ratio of the maximum tangential to the normal force remains at 0.7 after an initial rapid increase, and the ratio does not greatly change according to the imposed displacement amplitudes (in the range of 0.05 mm and 0.3 mm. The wear volume loss on the steel specimen increases according to the number of cycles. It is determined that the wear rate of the specimen changes with respect to the imposed displacement amplitude. That is, the wear rate rapidly increases within the displacement amplitude range of 0.05 mm to 0.09 mm, while the wear rate gradually increases when the displacement amplitude is greater than 0.2 mm. The obtained results provide the friction and wear behaviors of cold rolled high strength steel in fretting and reciprocal sliding regimes.

  16. Mechanical Behavior of Two High Strength Alloy Steels Under Conditions of Cyclic Tension

    Science.gov (United States)

    Srivatsan, T. S.; Manigandan, K.; Sastry, S.; Quick, T.; Schmidt, M. L.

    2014-01-01

    The results of a recent study aimed at understanding the conjoint influence of load ratio and microstructure on the high cycle fatigue properties and resultant fracture behavior of two high strength alloy steels is presented and discussed. Both the chosen alloy steels, i.e., 300M and Tenax™ 310 have much better strength and ductility properties to offer in comparison with the other competing high strength steels having near similar chemical composition. Test specimens were precision machined from the as-provided stock of each steel. The machined specimens were deformed in both uniaxial tension and cyclic fatigue under conditions of stress control. The test specimens of each alloy steel were cyclically deformed over a range of maximum stress at two different load ratios and the number of cycles to failure recorded. The specific influence of load ratio on cyclic fatigue life is presented and discussed keeping in mind the maximum stress used during cyclic deformation. The fatigue fracture surfaces were examined in a scanning electron microscope to establish the macroscopic mode and to concurrently characterize the intrinsic features on the fracture surface. The conjoint influence of nature of loading, maximum stress, and microstructure on cyclic fatigue life is discussed.

  17. Concurrent solution-like decoloration rate and high mechanical strength from polymer-dispersed photochromic organogel.

    Science.gov (United States)

    Long, Shijun; Bi, Shuguang; Liao, Yonggui; Xue, Zhigang; Xie, Xiaolin

    2014-04-01

    To achieve a fast photochromic response in solid matrix, photochromic molecules/segments have been either dispersed into elastomers via physical doping or linked to glassy polymers by soft units through covalent bonding. However, the former is lack of high mechanical strength and the latter owes the drawback of time-consumption of synthesis. Here, we propose a facile strategy of co-solvent evaporation to prepare polymer-dispersed photochromic organogel where both high mechanical strength of the glassy polymer matrix and solution-like fast photochromism of the photochromic molecule within organogel can be retained concurrently. Glassy PVA matrix and dispersed organogel of 1,3:2,4-di-O-benzylidene-d-sorbitol/poly(propylene glycol) (DBS/PPG) provide high mechanical strength and sufficient free volume for intramolecular rotation of photochromic spiropyran (SP), respectively. Interestingly, these thin films behave a solution-like decoloration the decay rate of which is 65-70 fold faster than that in the SP-directly doped PVA film and only slightly slower than those in their corresponding PPG solutions.

  18. Monotonic and Cyclic Bond Behavior of Deformed CFRP Bars in High Strength Concrete

    Directory of Open Access Journals (Sweden)

    T. Tibet Akbas

    2016-05-01

    Full Text Available Composite reinforcing bars (rebars that are used in concrete members with high performance (strength and durability properties could have beneficial effects on the behavior of these members. This is especially vital when a building is constructed in an aggressive environment, for instance a corrosive environment. Although tension capacity/weight (or volume ratios in composite rebars (carbon fiber reinforced polymer (CFRP, glass fiber reinforced polymer (GFRP, etc. are very high when compared to steel rebars, major weaknesses in concrete members reinforced with these composite rebars may be the potential consequences of relatively poor bonding capacity. This may even be more crucial when the member is subjected to cyclic loading. Although monotonic bond tests are available in the literature, only limited experimental studies exist on bond characteristics under cyclic loading conditions. In order to fill this gap and propose preliminary design recommendations, 10 specimens of 10-mm-diameter ribbed CFRP rebars embedded in specially designed high strength concrete (f’c = 70 MPa blocks were subjected to monotonic and cyclic pullout tests. The experimental results showed that cyclically loaded CFRP rebars had less bond strength than those companion specimens loaded monotonically.

  19. Neptunium (V) Adsorption to a Halophilic Bacterium Under High Ionic Strength Conditions: A Surface Complexation Modeling Approach

    Energy Technology Data Exchange (ETDEWEB)

    Ams, David A [Los Alamos National Laboratory

    2012-06-11

    Rationale for experimental design: Np(V) -- important as analog for Pu(V) and for HLW scenarios; High ionic strength -- relevant to salt-based repositories such as the WIPP; Halophilic microorganisms -- representative of high ionic strength environments. For the first time showed: Significant adsorbant to halophilic microorganisms over entire pH range under high ionic strength conditions; Strong influence of ionic strength with increasing adsorption with increasing ionic strength (in contrast to trends of previous low ionic strength studies); Effect of aqueous Np(V) and bacterial surface site speciation on adsorption; and Developed thermodynamic models that can be incorporated into geochemical speciation models to aid in the prediction of the fate and transport of Np(V) in more complex systems.

  20. High-intensity intermittent exercise and its effects on heart rate variability and subsequent strength performance

    Directory of Open Access Journals (Sweden)

    Valéria Leme Gonçalves Panissa

    2016-03-01

    Full Text Available PRUPOSE: To investigate the effects of a 5-km high-intensity interval exercise (HIIE on heart rate variability (HRV and subsequent strength performance. METHODS: nine trained males performed a control session composed of a half-squat strength exercise (4 x 80% of one repetition maximum – 1RM in isolation and 30-min, 1-, 4-, 8- and 24-h after an HIIE (1-min at the velocity peak:1-min passive recovery. All experimental sessions were performed on different days. The maximum number of repetitions and total weight lifted during the strength exercise were registered in all conditions; in addition, prior to each session, HRV were assessed [beat-to-beat intervals (RR and log-transformed of root means square of successive differences in the normal-to-normal intervals (lnRMSSD]. RESULTS: Performance in the strength exercise dropped at 30-min (31% and 1-h (19% post-HIIE concomitantly with lower values of RR (781±79 ms; 799±134 ms, respectively in the same recovery intervals compared to the control (1015±197 ms. Inferential analysis did not detect any effect of condition on lnRMSSD, however, values were lower after 30-min (3.5±0.4 ms and 1-h (3.3±0.5 ms with moderate and large effect sizes (0.9 and 1.2, respectively compared with the control condition (3.9±0.4 ms. CONCLUSION: Both RR and lnRMSSD seem to be associated with deleterious effects on strength performance, although further studies should be conducted to clarify this association.

  1. Effect of test temperature and strain rate on the tensile properties of high-strength, high-conductivity copper alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Eatherly, W.S. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    The unirradiated tensile properties of wrought GlidCop AL25 (ITER grade zero, IGO) solutionized and aged CuCrZr, and cold-worked and aged and solutionized and aged Hycon 3HP{trademark} CuNiBe have been measured over the temperature range of 20-500{degrees}C at strain rates between 4 x 10{sup {minus}4} s{sup {minus}1} and 0.06 s{sup {minus}1}. The measured room temperature electrical conductivity ranged from 64 to 90% IACS for the different alloys. All of the alloys were relatively insensitive to strain rate at room temperature, but the strain rate sensitivity of GlidCop Al25 increased significantly with increasing temperature. The CuNiBe alloys exhibited the best combination of high strength and high conductivity at room temperature. The strength of CuNiBe decreased slowly with increasing temperature. However, the ductility of CuNiBe decreased rapidly with increasing temperature due to localized deformation near grain boundaries, making these alloy heats unsuitable for typical structural applications above 300{degrees}C. The strength and uniform elongation of GlidCop Al25 decreased significantly with increasing temperature at a strain rate of 1 x 10{sup {minus}3} s{sup {minus}1}, whereas the total elongation was independent of test temperature. The strength and ductility of CuCrZr decreased slowly with increasing temperature.

  2. Enzymatic surface erosion of high tensile strength polycarbonates based on natural phenols.

    Science.gov (United States)

    Sommerfeld, Sven D; Zhang, Zheng; Costache, Marius C; Vega, Sebastián L; Kohn, Joachim

    2014-03-10

    Surface erosion has been recognized as a valuable design tool for resorbable biomaterials within the context of drug delivery devices, surface coatings, and when precise control of strength retention is critical. Here we report on high tensile strength, aromatic-aliphatic polycarbonates based on natural phenols, tyrosol (Ty) and homovanillyl alcohol (Hva), that exhibit enzymatic surface erosion by lipase. The Young's moduli of the polymers for dry and fully hydrated samples are 1.0 to 1.2 GPa and 0.8 to 1.2 GPa, respectively. Typical characteristics of enzymatic surface erosion were confirmed for poly(tyrosol carbonate) films with concomitant mass-loss and thickness-loss at linear rates of 0.14 ± 0.01 mg cm(-2) d(-1) and 3.0 ± 0.8 μm d(-1), respectively. The molecular weight and the mechanical properties of the residual films remained constant. Changing the ratio of Ty and Hva provided control over the glass transition temperature (T(g)) and the enzymatic surface erosion: increasing the Hva content in the polymers resulted in higher T(g) and lower enzymatic erosion rate. Polymers with more than 50 mol % Hva were stable at 37 °C in enzyme solution. Analysis on thin films using quartz crystal microbalance with dissipation (QCM-D) demonstrated that the onset temperature of the enzymatic erosion was approximately 20 °C lower than the wet T(g) for all tested polymers. This new finding demonstrates that relatively high tensile strength polycarbonates can undergo enzymatic surface erosion. Moreover, it also sheds light on the connection between T(g) and enzymatic degradation and explains why few of the high strength polymers follow an enzyme-meditated degradation pathway.

  3. Variable amplitude corrosion fatigue and fracture mechanics of weldable high strength jack-up steels

    Science.gov (United States)

    Etube, Linus Sone

    The tubular welded joints used in the construction of Offshore structures can experience millions of variable amplitude wave induced stress cycles during their operational life. Fatigue has been identified as the main cause of degradation of structural integrity in these structures. As a result, fatigue is an important consideration in their design. Jack-up legs are made from a range of high strength steels with yield strengths up to TOOMPa. These steels are thought to exhibit fatigue resistance properties which are different when compared with conventional fixed platform steels such as BS 4360 50D and BS 7191 355D. The difference in their behaviour was heightened by the discovery, in the late 80s and early 90s, of extensive cracking around the spud can regions of several Jack-ups operating in the North Sea. It was thought that these steels may be more susceptible to hydrogen cracking and embrittlement. There was the additional requirement to study their behaviour under realistic loading conditions typical of the North Sea environment. This thesis contains results of an investigation undertaken to assess the performance of a typical high strength weldable Jack-up steel under realistic loading and environmental conditions. Details of the methodology employed to develop a typical Jack-up Offshore Standard load History (JOSH) are presented. The factors which influence fatigue resistance of structural steels used in the construction of Jack-up structures are highlighted. The methods used to model the relevant factors for inclusion in JOSH are presented with particular emphasis on loading and structural response interaction. Results and details of experimental variable amplitude corrosion fatigue (VACF) tests conducted using JOSH are reported and discussed with respect to crack growth mechanisms in high strength weldable Jack-up steels. Different fracture mechanics models for VACF crack growth prediction are compared and an improved generalised methodology for fast

  4. Apparatus for advancing a wellbore using high power laser energy

    Science.gov (United States)

    Zediker, Mark S.; Land, Mark S.; Rinzler, Charles C.; Faircloth, Brian O.; Koblick, Yeshaya; Moxley, Joel F.

    2014-09-02

    Delivering high power laser energy to form a borehole deep into the earth using laser energy. Down hole laser tools, laser systems and laser delivery techniques for advancement, workover and completion activities. A laser bottom hole assembly (LBHA) for the delivery of high power laser energy to the surfaces of a borehole, which assembly may have laser optics, a fluid path for debris removal and a mechanical means to remove earth.

  5. Progress in advanced high temperature turbine materials, coatings, and technology

    Science.gov (United States)

    Freche, J. C.; Ault, G. M.

    1978-01-01

    Advanced materials, coatings, and cooling technology is assessed in terms of improved aircraft turbine engine performance. High cycle operating temperatures, lighter structural components, and adequate resistance to the various environmental factors associated with aircraft gas turbine engines are among the factors considered. Emphasis is placed on progress in development of high temperature materials for coating protection against oxidation, hot corrosion and erosion, and in turbine cooling technology. Specific topics discussed include metal matrix composites, superalloys, directionally solidified eutectics, and ceramics.

  6. High-throughput design of low-activation, high-strength creep-resistant steels for nuclear-reactor applications

    Science.gov (United States)

    Lu, Qi; van der Zwaag, Sybrand; Xu, Wei

    2016-02-01

    Reduced-activation ferritic/martensitic steels are prime candidate materials for structural applications in nuclear power reactors. However, their creep strength is much lower than that of creep-resistant steel developed for conventional fossil-fired power plants as alloying elements with a high neutron activation cannot be used. To improve the creep strength and to maintain a low activation, a high-throughput computational alloy design model coupling thermodynamics, precipitate-coarsening kinetics and an optimization genetic algorithm, is developed. Twelve relevant alloying elements with either low or high activation are considered simultaneously. The activity levels at 0-10 year after the end of irradiation are taken as optimization parameter. The creep-strength values (after exposure for 10 years at 650 °C) are estimated on the basis of the solid-solution strengthening and the precipitation hardening (taking into account precipitate coarsening). Potential alloy compositions leading to a high austenite fraction or a high percentage of undesirable second phase particles are rejected automatically in the optimization cycle. The newly identified alloys have a much higher precipitation hardening and solid-solution strengthening at the same activity level as existing reduced-activation ferritic/martensitic steels.

  7. Bond strength of a resin cement to high-alumina and zirconia-reinforced ceramics : The effect of surface conditioning

    NARCIS (Netherlands)

    Felipe Valandro, Luiz; Ozcan, Mutlu; Bottino, Marco Cicero; Bottino, Marco Antonio; Scotti, Roberto; Della Bona, Alvaro

    2006-01-01

    Purpose: The aim of this study was to evaluate the effect of two surface conditioning methods on the microtensile bond strength of a resin cement to three high-strength core ceramics: high alumina-based (In-Ceram Alumina, Procera AllCeram) and zirconia-reinforced alumina-based (in-Ceram Zirconia) ce

  8. Bond strength of a resin cement to high-alumina and zirconia-reinforced ceramics: The effect of surface conditioning

    NARCIS (Netherlands)

    Valandro, L.F.; Ozcan, M.; Bottino, M.C.; Bottino, M.A.; Scotti, R.; Della Bona, A.

    2006-01-01

    Purpose: The aim of this study was to evaluate the effect of two surface conditioning methods on the microtensile bond strength of a resin cement to three high-strength core ceramics: high alumina-based (In-Ceram Alumina, Procera AllCeram) and zirconia-reinforced alumina-based (in-Ceram Zirconia) ce

  9. TIG-dressing of High Strength Steel Butt Welded Connections. Part 1: Weld Toe Geometry and Local Hardness

    NARCIS (Netherlands)

    Van Es, S.H.J.; Kolstein, M.H.; Pijpers, R.J.M.; Bijlaard, F.S.K.

    2014-01-01

    This paper presents the results of extensive measurements on weld toe geometry of as-welded and TIG-dressed butt welded connections in high strength steels S460, S690 and very high strength steels S890 and S1100. Descriptions of the measurement techniques and data analysis are presented. Four weld t

  10. TIG-dressing of high strength steel butt welded connections - Part 1: weld toe geometry and local hardness

    NARCIS (Netherlands)

    Es, S.H.J. van; Kolstein, M.H.; Pijpers, R.J.M.; Bijlaard, F.S.K.

    2013-01-01

    This paper presents the results of extensive measurements on weld toe geometry of as-welded and TIG-dressed butt welded connections in high strength steels S460, S690 and very high strength steels S890 and S1100. Descriptions of the measurement techniques and data analysis are presented. Four weld t

  11. High strength alloys for high temperature service in liquid-salt cooled energy systems

    Science.gov (United States)

    Holcomb, David E.; Muralidharan, Govindarajan; Wilson, Dane F.

    2017-01-10

    An essentially cobalt-free alloy consists essentially of, in terms of weight percent: 6.3 to 7.2 Cr, 0.5 to 2 Al, 0 to 5 Fe, 0.7 to 0.8 Mn, 9 to 12.5 Mo, 0 to 6 Ta, 0.75 to 3.5 Ti, 0.01 to 0.25 Nb, 0.2 to 0.6 W, 0.02 to 0.04 C, 0 to 0.001 B, 0.0001 to 0.002 N, balance Ni. The alloy is characterized by a .gamma.' microstructural component in the range of 3 to 17.6 weight percent of the total composition. The alloy is further characterized by, at 850.degree. C., a yield strength of at least 60 Ksi, a tensile strength of at least 70 Ksi, a creep rupture life at 12 Ksi of at least 700 hours, and a corrosion rate, expressed in weight loss [g/(cm.sup.2sec)]10.sup.-11 during a 1000 hour immersion in liquid FLiNaK at 850.degree. C., in the range of 5.5 to 17.

  12. High strength alloys for high temperature service in liquid-salt cooled energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, David E.; Muralidharan, Govindarajan; Wilson, Dane F.

    2017-01-10

    An essentially cobalt-free alloy consists essentially of, in terms of weight percent: 6.3 to 7.2 Cr, 0.5 to 2 Al, 0 to 5 Fe, 0.7 to 0.8 Mn, 9 to 12.5 Mo, 0 to 6 Ta, 0.75 to 3.5 Ti, 0.01 to 0.25 Nb, 0.2 to 0.6 W, 0.02 to 0.04 C, 0 to 0.001 B, 0.0001 to 0.002 N, balance Ni. The alloy is characterized by a .gamma.' microstructural component in the range of 3 to 17.6 weight percent of the total composition. The alloy is further characterized by, at 850.degree. C., a yield strength of at least 60 Ksi, a tensile strength of at least 70 Ksi, a creep rupture life at 12 Ksi of at least 700 hours, and a corrosion rate, expressed in weight loss [g/(cm.sup.2sec)]10.sup.-11 during a 1000 hour immersion in liquid FLiNaK at 850.degree. C., in the range of 5.5 to 17.

  13. Mechanical properties of ground state structures in substitutional ordered alloys: High strength, high ductility and high thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Tawancy, H.M., E-mail: tawancy@kfupm.edu.sa [Center for Engineering Research, Research Institute, King Fahd University of Petroleum and Minerals, KFUPM Box 1639, Dhahran 31261 (Saudi Arabia); Aboelfotoh, M.O., E-mail: oaboelfotoh@gmail.com [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27606 (United States)

    2014-05-01

    We have studied the effect of atom arrangements in the ground state structures of substitutional ordered alloys on their mechanical properties using nickel–molybdenum-based alloys as model systems. Three alloys with nominal compositions of Ni–19.43 at% Mo, Ni–18.53 at% Mo–15.21 at% Cr and Ni–18.72 at% Mo–6.14 at% Nb are included in the study. In agreement with theoretical predictions, the closely related Pt{sub 2}Mo-type, DO{sub 22} and D1{sub a} superlattices with similar energies are identified by electron diffraction of ground state structures, which can directly be derived from the parent disordered fcc structure by minor atom rearrangements on {420}{sub fcc} planes. The three superlattices are observed to coexist during the disorder–order transformation at 700 °C with the most stable superlattice being determined by the exact chemical composition. Although most of the slip systems in the parent disordered fcc structure are suppressed, many of the twinning systems remain operative in the superlattices favoring deformation by twinning, which leads to considerable strengthening while maintaining high ductility levels. Both the Pt{sub 2}Mo-type and DO{sub 22} superlattices are distinguished by high strength and high ductility due to their nanoscale microstructures, which have high thermal stability. However, the D1{sub a} superlattice is found to exhibit poor thermal stability leading to considerable loss of ductility, which has been correlated with self-induced recrystallization by migration of grain boundaries.

  14. Production of high strength hollow shafts using tool hardening and Q-P process

    Directory of Open Access Journals (Sweden)

    Masek Bohuslav

    2015-01-01

    Full Text Available Innovation opens new opportunities in the field of processing hollow semi-products, as it offers the potential for manufacturing complex-shaped structural parts with enhanced properties. This introduces a manufacturing route comprising the following steps: internal high pressure forming, hot stamping and thermomechanical Q&P processing. In this manufacturing route, the demonstration product, a tube–shaped stock, is first austenitized. It is then expanded in a closed die by internal pressure of nitrogen until the material touches the die wall. As a result, it cools down quickly and martensite begins to form. At a temperature above the Mf, the cooling is interrupted and the workpiece is transferred to a furnace and tempered. The furnace temperature is below the Ms temperature. Within several minutes, a mixed microstructure forms, consisting of martensite and stabilized retained austenite. Thanks to this microstructure, the material exhibits a favourable combination of high strength and adequate ductility. Martensite imparts sufficient strength to the material whereas the retained austenite provides ductility. At a carbon level of approximately 0.4 % and with a simple Si-Mn-Cr-based chemistry, strengths of 2000 MPa and A5 mm elongations of 15% can be achieved.

  15. Effects of Manufactured-sand on Dry Shrinkage and Creep of High-strength Concrete

    Institute of Scientific and Technical Information of China (English)

    ZHOU Mingkai; WANG Jiliang; ZHU Lide; HE Tusheng

    2008-01-01

    The influences of natural sand, manufactured-sand (MS) and stone-dust (SD) in the manufactured-sand on workability, compressive strength, elastic modulus, drying shrinkage and creep properties of high-strength concrete (HSC) were tested and compared. The results show that the reasonable content (7%-10.5%) of SD in MS will not deteriorate the workability of MS-HSC. It could even improve the workability. Moreover, the compressive strength increases gradually with the increasing SD content,and the MS-HSC with low SD content (smaller than 7%) has the elastic modulus which approaches that of the natural sand HSC, but the elastic modulus reduces when the SD content is high. The influence of the SD content on drying shrinkage performance of MS-HSC is closely related to the hydration age. The shrinkage rate of MS-HSC in the former 7 d age is higher than that of the natural sand HSC, but the difference of the shrinkage rate in the late age is not marked. Meanwhile the shrinkage rate reduces as the fly ash is added; the specific creep and creep coefficient of MS-HSC with 7% SD are close to those of the natural sand HSC.

  16. Seismic performance of steel reinforced ultra high-strength concrete composite frame joints

    Institute of Scientific and Technical Information of China (English)

    Yan Changwang; Jia Jinqing

    2010-01-01

    To investigate the seismic performance of a composite frame comprised of steel reinforced ultra high-strength concrete (SRUHSC) columns and steel reinforced concrete (SR.C) beams, six interior frame joint specimens were designed and tested under low cyclically lateral load. The effects of the axial load ratio and volumetric stirrup ratio were studied on the characteristics of the frame joint performance including crack pattern, failure mode, ductility, energy dissipation capacity, strength degradation and rigidity degradation. It was found that all joint specimens behaved in a ductile manner with flexural-shear failure in the joint core region while plastic hinges appeared at the beam ends. The ductility and energy absorption capacity of joints increased as the axial load ratio decreased and the volumetric stirrup ratio increased. The displacement ductility coefficient and equivalent damping coefficient of the joints fell between the corresponding coefficients of the steel reinforced concrete (SRC) frame joint and R.C frame joint. The axial load ratio and volumetric stirrup ratio have less influence on the strength degradation and more influence on the stiffness degradation. The stiffness of the joint degrades more significantly for a low volumetric stirrup ratio and high axial load ratio. The characteristics obtained from the SRUHSC composite frame joint specimens with better seismic performance may be a useful reference in future engineering applications.

  17. Seismic performance of steel reinforced ultra high-strength concrete composite frame joints

    Science.gov (United States)

    Yan, Changwang; Jia, Jinqing

    2010-09-01

    To investigate the seismic performance of a composite frame comprised of steel reinforced ultra high-strength concrete (SRUHSC) columns and steel reinforced concrete (SRC) beams, six interior frame joint specimens were designed and tested under low cyclically lateral load. The effects of the axial load ratio and volumetric stirrup ratio were studied on the characteristics of the frame joint performance including crack pattern, failure mode, ductility, energy dissipation capacity, strength degradation and rigidity degradation. It was found that all joint specimens behaved in a ductile manner with flexural-shear failure in the joint core region while plastic hinges appeared at the beam ends. The ductility and energy absorption capacity of joints increased as the axial load ratio decreased and the volumetric stirrup ratio increased. The displacement ductility coefficient and equivalent damping coefficient of the joints fell between the corresponding coefficients of the steel reinforced concrete (SRC) frame joint and RC frame joint. The axial load ratio and volumetric stirrup ratio have less influence on the strength degradation and more influence on the stiffness degradation. The stiffness of the joint degrades more significantly for a low volumetric stirrup ratio and high axial load ratio. The characteristics obtained from the SRUHSC composite frame joint specimens with better seismic performance may be a useful reference in future engineering applications.

  18. Adhesive bond strength evaluation in composite materials by laser-generated high amplitude ultrasound

    Science.gov (United States)

    Perton, M.; Blouin, A.; Monchalin, J.-P.

    2011-01-01

    Adhesive bonding of composites laminates is highly efficient but is not used for joining primary aircraft structures, since there is presently no nondestructive inspection technique to ensure the quality of the bond. We are developing a technique based on the propagation of high amplitude ultrasonic waves to evaluate the adhesive bond strength. Large amplitude compression waves are generated by a short pulse powerful laser under water confinement and are converted after reflection by the assembly back surface into tensile waves. The resulting tensile stresses can cause a delamination inside the laminates or at the bond interfaces. The adhesion strength is evaluated by increasing the laser pulse energy until disbond. A good bond is unaffected by a certain level of stress whereas a weaker one is damaged. The method is shown completely non invasive throughout the whole composite assembly. The sample back surface velocity is measured by an optical interferometer and used to estimate stress history inside the sample. The depth and size of the disbonds are revealed by a post-test inspection by the well established laser-ultrasonic technique. Experimental results show that the proposed method is able to differentiate weak bond from strong bonds and to estimate quantitatively their bond strength.

  19. Graded High-Strength Spring-Steels by a Special Inductive Heat T reatment

    Science.gov (United States)

    Tump, A.; Brandt, R.

    2016-03-01

    A method for effective lightweight design is the use of materials with high specific strength. As materials e.g. titanium are very expensive, steel is still the most important material for manufacturing automotive components. Steel is cost efficient, easy to recycle and its tensile strength easily exceeds 2,000 MPa by means of modern QT-technology (Quenched and Tempered). Therefore, lightweight design is still feasible in spite of the high density of steel. However, a further increase of tensile strength is limited, especially due to an increasing notch sensitivity and exposure to a corrosive environment. One solution is a special QT-process for steel, which creates a hardness gradient from the surface to the core of the material. This type of tailored material possesses a softer layer, which improves material properties such as fracture toughness and notch sensitivity. This leads to a better resistance to stress corrosion cracking and corrosion fatigue. Due to this optimization, a weight reduction is feasible without the use of expensive alloying elements. To understand the damage mechanism a comprehensive testing procedure was performed on homogeneous and gradient steels. Some results regarding the fracture mechanic behavior of such steels will be discussed.

  20. Temperature-Dependent Thermal Conductivity of High Strength Lightweight Raw Perlite Aggregate Concrete

    Science.gov (United States)

    Tandiroglu, Ahmet

    2010-06-01

    Twenty-four types of high strength lightweight concrete have been designed with raw perlite aggregate (PA) from the Erzincan Mollaköy region as new low-temperature insulation material. The effects of the water/cement ratio, the amount of raw PA, and the temperature on high strength lightweight raw perlite aggregate concrete (HSLWPAC) have been investigated. Three empirical equations were derived to correlate the thermal conductivity of HSLWPAC as a function of PA percentage and temperature depending on the water/cement ratio. Experimentally observed thermal conductivities of concrete samples were predicted 92 % of the time for each set of concrete matrices within 97 % accuracy and over the range from 1.457 W · m-1 · K-1 to 1.777 W · m-1 · K-1. The experimental investigation revealed that the usage of raw PA from the Erzincan Mollaköy region in concrete production reduces the concrete unit mass, increases the concrete strength, and furthermore, the thermal conductivity of the concrete has been improved. The proposed empirical correlations of thermal conductivity were considered to be applicable within the range of temperatures 203.15 K ≤ T ≤ 303.15 K in the form of λ = a( PAP b ) + c( T d ).

  1. Monitoring deep twist drilling for a rapid manufacturing of light high-strength parts

    Science.gov (United States)

    López de Lacalle, L. N.; Fernández, A.; Olvera, D.; Lamikiz, A.; Olvera, D.; Rodríguez, C.; Elias, A.

    2011-10-01

    In this work the manufacturing of high strength and/or high functional components is presented, using a new technique based on considerably long twist drills, called Deep Twist Drilling (DTD). This technology opens a rapid and economical method to manufacture parts for structural applications. Components made with this technique can reach high mass reduction and better stress distribution in comparison with welding or bolted parts with the same weight. However the application of DTD must be optimized to improve the reliability of the process and to make it economically feasible. In order to reach it, previous optimization by process monitoring was performed in AISI 1045, stainless steels, Ti6Al4V and nodular cat iron GGG70(AISI A536, SAE-ASTM 100-70-03). These materials are commonly used for structural applications in several sectors. Monitoring opened the way to improve cutting conditions and allow the application of the DTD technique focusing on a new design concept. In the same way monitoring makes drilling process reliable enough to be systematically used in industrial applications by a controlled increase of the performance demanded from the tool. In this manner, not only the objective to produce high-strength and light pieces is achieved, but also a high repetitive process is reached. In this research work a case of study is presented. A monolithic satellite-type component, its mass were reduced from 25 to 4.5 kg. The structural behavior of the component was studied under FEM analysis and the results showed high strength to compression and shear forces. During the machining of this element there was a serious risk of drill breakage due to the depth of the holes and crossing points between them; however, the previous process optimization eliminated this drawback. As a matter of fact, this paper brings out a good example where manufacturing technology allows a better performance of mechanical components within the philosophy of "new processes drive to new

  2. Adsorption of polar probe molecules on plasma-oxidised high-strength carbon fibres

    Energy Technology Data Exchange (ETDEWEB)

    Montes-Moran, M.A.; Martinez-Alonso, A.; Tascon, J.M.D. [Instituto Nacional del Carbon, CSIC, Apartado 73, 33080, Oviedo (Spain)

    2002-06-20

    The objective of this work was to examine the effect of oxygen plasma treatment on the surface chemistry of carbon fibres. Virgin, unsized high-strength carbon fibres were subjected to oxygen plasma treatments with different degrees of severity. Adsorption of probe molecules with different acid-base characteristics (acetone, carbon tetrachloride, trichloromethane, dichloromethane, diethyl ether, nitromethane, tetrahydrofurane) was measured at 303-353 K using inverse gas chromatography (IGC) at infinite dilution. Plasma treatment brings about increases in the specific free energy of adsorption of either acidic, basic or amphoteric probe molecules, indicating creation of surface functionalities with various acid-base strengths. This helps to justify the improvement in interfacial adhesion in polycarbonate matrix composites following plasma treatment of carbon fibres.

  3. A high-specific-strength and corrosion-resistant magnesium alloy

    Science.gov (United States)

    Xu, Wanqiang; Birbilis, Nick; Sha, Gang; Wang, Yu; Daniels, John E.; Xiao, Yang; Ferry, Michael

    2015-12-01

    Ultra-lightweight alloys with high strength, ductility and corrosion resistance are desirable for applications in the automotive, aerospace, defence, biomedical, sporting and electronic goods sectors. Ductility and corrosion resistance are generally inversely correlated with strength, making it difficult to optimize all three simultaneously. Here we design an ultralow density (1.4 g cm-3) Mg-Li-based alloy that is strong, ductile, and more corrosion resistant than Mg-based alloys reported so far. The alloy is Li-rich and a solute nanostructure within a body-centred cubic matrix is achieved by a series of extrusion, heat-treatment and rolling processes. Corrosion resistance from the environment is believed to occur by a uniform lithium carbonate film in which surface coverage is much greater than in traditional hexagonal close-packed Mg-based alloys, explaining the superior corrosion resistance of the alloy.

  4. Effect of Boron on Delayed Fracture Resistance of Medium-Carbon High Strength Spring Steel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The delayed fracture behavior of medium-carbon high strength spring steel containing different amounts of boron (0. 000 5%, 0. 001 6%) was studied using sustained load delayed fracture test. The results show that delayed fracture resistance of boron containing steels is higher than that of conventional steel 60Si2MnA at the same strength level and it increases with the increase of boron content from 0. 000 5 % to 0. 001 6 %. The delayed fracture mode is mainly intergranular in the boron containing steels tempered at 350 ℃, which indicates that the addition of boron does not change the fracture character. However, the increase of boron content enlarges the size of the crack initiation area. Further study of phase analysis indicates that most boron is in solid solution, and only a very small quantity of boron is in the M3 (C, B) phase.

  5. Biological effects of high strength electric fields. Second interim progress report, September 1976--March 1977

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, R.D.; Kaune, W.T.

    1977-05-01

    This report describes progress made on the Project during the period of September 9, 1976 to March 31, 1977 towards the determination of the biological effects of high strength electric fields on small laboratory animals. The efforts to date can be divided into five categories: (1) the design, construction, and testing of a prototype and special studies exposure system; (2) the design and construction of exposure systems for rats and mice; (3) dosimetry; (4) experiments to determine the maximum field strength which does not produce corona discharge, ozone formation, shocks to the animal, hair stimulation, or a behavioral preference by rats to avoid exposure to the field; and (5) preparations for the biological screening experiments.

  6. Experimental Analysis of Concrete Strength at High Temperatures and after Cooling

    Directory of Open Access Journals (Sweden)

    E. Klingsch

    2009-01-01

    Full Text Available In recent years, the cement industry has been criticized for emitting large amounts of carbon dioxide; hence it is developing environment-friendly cement, e.g., blended, supersulfated slag cement (SSC. This paper presents an experimental analysis of the compressive strength development of concrete made from blended cement in comparison to ordinary cement at high temperature. Three different types of cement were used during these tests, an ordinary portland cement (CEM I, a portland limestone cement (CEM II-A-LL and a new, supersulfated slag cement (SSC. The compressive strength development for a full thermal cycle, including cooling down phase, was investigated on concrete cylinders. It is shown that the SSC concrete specimens perform similar to ordinary cement specimens. 

  7. Effects of structure and defect on fatigue limit in high strength ductile irons

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Hak; Kim, Min Gun [Kangwon National Univ., Chunchon (Korea, Republic of)

    2000-05-01

    In this paper, the influence of several factors such as hardness, internal defect and non-propagating crack on fatigue limits was investigated with three kinds of ductile iron specimens. From the experimental results the fatigue limits were examined in relation with hardness and tensile strength in case of high strength specimens under austempering treatment; in consequence the marked improvement of fatigue limits were not showed. The maximum defect size was an important factor to predict and to evaluate the fatigue limits of ductile irons. And, the quantitative relationship between the fatigue limits({sigma}{sub {omega}}) and the maximum defect size({radical}area{sub max}) was expressed as {sigma}{sub {omega}}{sup n} {center_dot} {radical}area{sub max}=C{sub 2}. Also, it was possible to explain the difference for the fatigue limits in three ductile irons by introduction of the non-propagating crack rates.

  8. Fatigue of Austempered Ductile Iron with Two Strength Grades in Very High Cycle Regime

    Science.gov (United States)

    Zhang, Jiwang; Li, Wei; Song, Qingpeng; Zhang, Ning; Lu, Liantao

    2016-03-01

    In this study, Austempered ductile irons (ADIs) with two different strength grades were produced and the fatigue properties were measured at 109 cycles. The results show that the S-N curves give a typical step-wise shape and there is no fatigue limit in the very high cycle fatigue regime. The two grades ADI have the similar fracture behaviors and fatigue failure can initiate from defects at specimen surface and subsurface zone. On the fracture surfaces of some specimens, the `granular-bright-facet' area with rich carbon distribution is observed in the vicinity of the defect. The microstructure affects the crack behaviors at the early propagation stage. The ADI with upper and lower bainite shows higher fatigue strength compared with the ADI with coarse upper bainite.

  9. Aging Behavior of High-Strength Al Alloy 2618 Produced by Selective Laser Melting

    Science.gov (United States)

    Casati, Riccardo; Lemke, Jannis Nicolas; Alarcon, Adrianni Zanatta; Vedani, Maurizio

    2017-02-01

    High Si-bearing Al alloys are commonly used in additive manufacturing, but they have moderate mechanical properties. New high-strength compositions are necessary to spread the use of additively manufactured Al parts for heavy-duty structural applications. This work focuses on the microstructure, mechanical behavior, and aging response of an Al alloy 2618 processed by selective laser melting. Calorimetric analysis, electron microscopy, and compression tests were performed in order to correlate the mechanical properties with the peculiar microstructure induced by laser melting and thermal treatments

  10. Plastic Instabilities and Their Consequences in Steels and Other High Strength Alloys

    Science.gov (United States)

    1991-09-01

    rate yes Superalloys * Alloy 600 quasi-static no Rend 41 quasi-static no Steels * HY80 quasi-static no ultra-soft5 no low temperatures no AISI 4340...AD-A240 976 ([f) A Final Technical Report Contract No. N00014-88-K-0111 S PLASTIC INSTABILITIES AND THEIR CONSEQUENCES IN STEELS AND OTHER HIGH...PLASTIC INSTABILITIES AND THEIR CONSEQUENCES IN STEELS AND OTHER HIGH STRENGTH ALLOYS Submitted to: Office of Naval Research 800 North Quincy Street

  11. Strength and Biot's coefficient for high-porosity oil- or water-saturated chalk

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling

    . The Biot coefficient states the degree of cementation or how the pore pressure contributes to the strain resulting from an external load for a porous material. It is here calculated from dynamic measurements and correlated with the strength of outcrop chalk characterized by the onset of pore collapse...... during hydrostatic loading. The hypothesis is that the Biot coefficient and the theory of poroelasticity may cover the fluid effect by including the increased fluid bulk modulus from oil to water. A high number of test results for both oil- and water-saturated high-porosity outcrop chalk show correlation...

  12. Effect of Heat Treatment on Mechanical Properties and Microstructure Morphology of Low-Alloy High-Strength Steel

    Directory of Open Access Journals (Sweden)

    Bolanowski K.

    2016-06-01

    Full Text Available The paper analyzes the influence of different heat treatment processes on the mechanical properties of low-alloy high-strength steel denoted by Polish Standard (PN as 10MnVNb6. One of the findings is that, after aging, the mechanical properties of rolled steel are high: the yield strength may reach > 600 MPa, and the ultimate tensile strength is > 700 MPa. These properties are largely dependent on the grain size and dispersion of the strengthening phase in the ferrite matrix. Aging applied after hot rolling contributes to a considerable rise in the yield strength and ultimate tensile strength. The process of normalization causes a decrease in the average grain size and coalescence (reduction of dispersion of the strengthening phase. When 10MnVNb6 steel was aged after normalization, there was not a complete recovery in its strength properties.

  13. Effect of Multistage Heat Treatment on Microstructure and Mechanical Properties of High-Strength Low-Alloy Steel

    Science.gov (United States)

    Liu, Qingdong; Wen, Haiming; Zhang, Han; Gu, Jianfeng; Li, Chuanwei; Lavernia, Enrique J.

    2016-05-01

    The influence of Cu-rich precipitates (CRPs) and reverted austenite (RA) on the strength and impact toughness of a Cu-containing 3.5 wt pct Ni high-strength low-alloy (HSLA) steel after various heat treatments involving quenching (Q), lamellarization (L), and tempering (T) is studied using electron back-scatter diffraction, transmission electron microscopy, and atom probe tomography. The QT sample exhibits high strength but low impact toughness, whereas the QL samples mostly possess improved impact toughness but moderate strength, but the QLT samples again have degraded impact toughness due to additional tempering. The dispersion of nanoscale CRPs, which are formed during tempering, is responsible for the enhanced strength but simultaneously leads to the degraded impact toughness. The RA formed during lamellarization contributes to the improved impact toughness. Based on the present study, new heat treatment schedules are proposed to balance strength and impact toughness by optimizing the precipitation of CRPs and RA.

  14. Cellular graphene aerogel combines ultralow weight and high mechanical strength: A highly efficient reactor for catalytic hydrogenation.

    Science.gov (United States)

    Zhang, Bingxing; Zhang, Jianling; Sang, Xinxin; Liu, Chengcheng; Luo, Tian; Peng, Li; Han, Buxing; Tan, Xiuniang; Ma, Xue; Wang, Dong; Zhao, Ning

    2016-05-12

    The construction of three-dimensional graphene aerogels (GAs) is of great importance owing to their outstanding properties for various applications. Up to now, the combination of ultralow weight and super mechanical strength for GA remains a great challenge. Here we demonstrate the fabrication of cellular GAs by a facile, easily controlled and versatile route, i.e. the chemical reduction of graphene oxide assemblies at oil-water interface under a mild condition (70 °C). The GA is ultralight (with density <3 mg cm(-3)) yet mechanically resilient because the walls of the cell closely pack in a highly ordered manner to maximize mechanical strength. The GA has been utilized as an appealing reactor for catalytic hydrogenation, which exhibited great advantages such as large oil absorption capability, exceptional catalytic activity, ease of product separation and high stability.

  15. Fe I Oscillator Strengths for Transitions from High-lying Even-Parity Levels

    CERN Document Server

    Hartog, E A Den; Lawler, J E; Pickering, J C; Lind, K; Brewer, N R

    2014-01-01

    New radiative lifetimes, measured to $\\pm$ 5 % accuracy, are reported for 31 even-parity levels of Fe I ranging from 45061 cm$^{-1}$ to 56842 cm$^{-1}$. These lifetimes have been measured using single-step and two-step time-resolved laser-induced fluorescence on a slow atomic beam of iron atoms. Branching fractions have been attempted for all of these levels, and completed for 20 levels. This set of levels represents an extension of the collaborative work reported in Ruffoni et al. (2014). The radiative lifetimes combined with the branching fractions yields new oscillator strengths for 203 lines of Fe I. Utilizing a 1D-LTE model of the solar photosphere, spectral syntheses for a subset of these lines which are unblended in the solar spectrum yields a mean iron abundance of = 7.45 $\\pm$ 0.06.

  16. Fe I OSCILLATOR STRENGTHS FOR TRANSITIONS FROM HIGH-LYING EVEN-PARITY LEVELS

    Energy Technology Data Exchange (ETDEWEB)

    Den Hartog, E. A.; Lawler, J. E.; Brewer, N. R. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Ruffoni, M. P.; Pickering, J. C. [Blackett Laboratory, Imperial College London, London SW7 2BW (United Kingdom); Lind, K., E-mail: eadenhar@wisc.edu [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden)

    2015-01-01

    New radiative lifetimes, measured to ±5% accuracy, are reported for 31 even-parity levels of Fe I ranging from 45061 cm{sup –1} to 56842 cm{sup –1}. These lifetimes have been measured using single-step and two-step time-resolved laser-induced fluorescence on a slow atomic beam of iron atoms. Branching fractions have been attempted for all of these levels, and completed for 20 levels. This set of levels represents an extension of the collaborative work reported in Ruffoni et al. The radiative lifetimes combined with the branching fractions yields new oscillator strengths for 203 lines of Fe I. Utilizing a 1D-LTE model of the solar photosphere, spectral syntheses for a subset of these lines which are unblended in the solar spectrum yields a mean iron abundance of (log[ε(Fe)]) = 7.45 ± 0.06.

  17. Development of high performance and high strength heavy concrete for radiation shielding structures

    Science.gov (United States)

    Peng, Yu-Chu; Hwang, Chao-Lung

    2011-02-01

    Heavy concrete currently used for construction contains special materials that are expensive and difficult to work with. This study replaced natural aggregate (stones) in concrete with round steel balls, which are inexpensive and easily obtainable. The diameters of the steel balls were 0.5 and 1 cm, and their density was 7.8 kg/m3. Dense packing mixture methods were used to produce heavy concrete with densities of 3500 and 5000 kg/m3. The various properties of this concrete were tested according to the standards of the American Society for Testing and Materials (ASTM). The results indicated that the construction slump of the concrete could reach 260-280 mm and its slump flow could reach 610-710 mm. More important, its compressive strength could reach 8848 MPa. These results will significantly alter traditional construction methods that use heavy concrete and enhance innovative ideas for structural design.

  18. Change of Hot Cracking Susceptibility in Welding of High Strength Aluminum Alloy AA 7075

    Science.gov (United States)

    Holzer, M.; Hofmann, K.; Mann, V.; Hugger, F.; Roth, S.; Schmidt, M.

    High strength aluminum alloys are known as hard to weld alloys due to their high hot crack susceptibility. However, they have high potential for applications in light weight constructions of automotive industry and therefore it is needed to increase weldability. One major issue is the high hot cracking susceptibility. Vaporization during laser beam welding leads to a change of concentration of the volatile elements magnesium and zinc. Hence, solidification range of the weld and therefore hot cracking susceptibility changes. Additionally, different welding velocities lead to changed solidification conditions with certain influence on hot cracking. This paper discusses the influence of energy per unit length during laser beam welding of AA 7075 on the change of element concentration in the weld seam and the resulting influence on hot cracking susceptibility. Therefore EDS-measurements of weld seams generated with different velocities are performed to determine the change of element concentration. These quantitative data is used to numerically calculate the solidification range in order to evaluate its influence on the hot cracking susceptibility. Besides that, relative hot crack length and mechanical properties are measured. The results increase knowledge about welding of high strength aluminum alloy AA 7075 and hence support further developing of the welding process.

  19. Mechanical model for yield strength of nanocrystalline materials under high strain rate loading

    Institute of Scientific and Technical Information of China (English)

    朱荣涛; 周剑秋; 马璐; 张振忠

    2008-01-01

    To understand the high strain rate deformation mechanism and determine the grain size,strain rate and porosity dependent yield strength of nanocrystalline materials,a new mechanical model based on the deformation mechanism of nanocrystalline materials under high strain rate loading was developed.As a first step of the research,the yield behavior of the nanocrystalline materials under high strain rate loading was mainly concerned in the model and uniform deformation was assumed for simplification.Nanocrystalline materials were treated as composites consisting of grain interior phase and grain boundary phase,and grain interior and grain boundary deformation mechanisms under high strain rate loading were analyzed,then Voigt model was applied to coupling grain boundary constitutive relation with mechanical model for grain interior phase to describe the overall yield mechanical behavior of nanocrystalline materials.The predictions by the developed model on the yield strength of nanocrysatlline materials at high strain rates show good agreements with various experimental data.Further discussion was presented for calculation results and relative experimental observations.

  20. A nano lamella NbTi–NiTi composite with high strength

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jiang; Jiang, Daqiang; Hao, Shijie; Yu, Cun; Zhang, Junsong; Ren, Yang; Lu, Deping; Xie, Shifang; Cui, Lishan

    2015-05-01

    A hypereutectic Nb60Ti24Ni16 (at%) alloy was prepared by vacuum induction melting, and a nano lamellae NbTi-NiTi composite was obtained by hot-forging and wire-drawing of the ingot Microscopic analysis showed that NbTi and NiTi nano lamellae distributed alternatively in the composite, and aligned along the wire axial direction, with a high volume fraction (similar to 70%) of NbTi nano lamellae. In situ synchrotron X-ray diffraction analysis revealed that stress induced martensitic transformation occurred upon loading, which would effectively weaken the stress concentration at the interface and avoid the introduction of defects into the nano reinforced phase. Then the embedded NbTi nano lamellae exhibited a high elastic strain up to 2.72%, 1.5 times as high as that of the Nb nanowires embedded in a conventional plastic matrix, and the corresponding stress carried by NbTi was evaluated as 2.53 GPa. The high volume fraction of NbTi nano lamellae improved the translation of high strength from the nano reinforced phase into bulk properties of the composite, with a platform stress of similar to 1.7 GPa and a fracture strength of similar to 1.9 GPa. (C) 2015 Elsevier B.V. All rights reserved.