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Sample records for carbonitrides

  1. Facile Synthesis of Ternary Boron Carbonitride Nanotubes

    Directory of Open Access Journals (Sweden)

    Luo Lijie

    2009-01-01

    Full Text Available Abstract In this study, a novel and facile approach for the synthesis of ternary boron carbonitride (B–C–N nanotubes was reported. Growth occurred by heating simple starting materials of boron powder, zinc oxide powder, and ethanol absolute at 1150 °C under a mixture gas flow of nitrogen and hydrogen. As substrate, commercial stainless steel foil with a typical thickness of 0.05 mm played an additional role of catalyst during the growth of nanotubes. The nanotubes were characterized by SEM, TEM, EDX, and EELS. The results indicate that the synthesized B–C–N nanotubes exhibit a bamboo-like morphology and B, C, and N elements are homogeneously distributed in the nanotubes. A catalyzed vapor–liquid–solid (VLS mechanism was proposed for the growth of the nanotubes.

  2. Laser-Induced Chemical Vapour Deposition of Silicon Carbonitride

    OpenAIRE

    Besling, W.; van der Put, P.; Schoonman, J.

    1995-01-01

    Laser-induced Chemical Vapour Deposition of silicon carbonitride coatings and powders has been investigated using hexamethyldisilazane (HMDS) and ammonia as reactants. An industrial CW CO2-laser in parallel configuration has been used to heat up the reactant gases. HMDS dissociates in the laser beam and reactive radicals are formed which increase rapidly in molecular weight by an addition mechanism. Dense polymer-like silicon carbonitride thin films and nanosized powders are formed depending ...

  3. Effect of carbonitride precipitates on the abrasive wear behaviour of hardfacing alloy

    Science.gov (United States)

    Yang, Ke; Yu, Shengfu; Li, Yingbin; Li, Chenglin

    2008-06-01

    Hardfacing alloy of martensitic stainless steel expect higher abradability to be achieved through the addition of nitrogen being provided by the fine scale precipitation of complex carbonitride particles. Niobium and titanium as the most effective carbonitride alloying elements were added in the Fe-Cr13-Mn-N hardfacing alloy to get carbonitride precipitates. Carbonitride was systematically studied by optical microscopy, scanning electronic microscopy and energy spectrum analysis. Abrasive wear resistance of hardfacing alloy in as-welded and heat-treated conditions was tested by using the belt abrasion test apparatus where the samples slide against the abrasive belt. It is found that carbonitride particles in the hardfacing alloy are complex of Cr, Ti and Nb distributing on the grain boundary or matrix of the hardfacing alloy with different number and size in as-welded and heat-treated conditions. A large number of carbonitrides can be precipitated with very fine size (nanoscale) after heat treatment. As a result, the homogeneous distribution of very fine carbonitride particles can significantly improve the grain-abrasion wear-resisting property of the hardfacing alloy, and the mass loss is plastic deformation with minimum depth of grooving by abrasive particles and fine delamination.

  4. An expression for solubility product of complex carbonitrides in multicomponent microalloyed austenite

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xiaodong; Solberg, J.K.; Gjengedal, R. (NTH, Trondheim (Norway). Dept. of Metallurgy); Kluken, A.O. (SINTEF Metallurgy, Trondheim (Norway))

    1994-12-15

    In view of the great interest in HSLA steels with small additions of titanium, niobium and/or vanadium, the solubility products of nitrides, carbides and carbonitrides in austenite have been investigated both theoretically and experimentally by many researchers. Nordberg and Aronsson first derived the solubility product for a complex carbonitride of a single microalloying element such as niobium, on which Hudd et al made some modifications. More recently, the complex addition of microalloying elements in HSLA steels has also received more attention. Clearly, the equilibrium composition of the precipitates depends on the composition of the steel and on the temperature. Some theoretical method have been derived to give this information, but none of them deal with the solubility product of complex carbonitrides containing more than one microalloying element (e.g. niobium and titanium). In the present paper, a general solubility product expression is derived for all kinds of complex carbonitrides with multicomponent microalloying additions.

  5. Precipitation of niobium carbonitrides in ferrite: chemical composition measurements and thermodynamic modelling

    OpenAIRE

    Perez, Michel; Courtois, E.; Acevedo, D.; T. Epicier; Maugis, Philippe

    2007-01-01

    High-resolution transmission electron microscopy and electron-energy loss spectroscopy have been used to characterize the structure and chemical composition of niobium carbonitrides in the ferrite of a Fe–Nb–C–N model alloy at different precipitation stages. Experiments seem to indicate the coexistence of two types of precipitates: pure niobium nitrides and mixed substoichiometric niobium carbonitrides. In order to understand the chemical composition of these precipitates, a thermodynamic for...

  6. Microstructural and compositional evolution of iron carbonitride compound layers during salt bath nitrocarburizing

    Energy Technology Data Exchange (ETDEWEB)

    Somers, M.A.J.; Colijn, P.F.; Sloof, W.G.; Mittemeijer, E.J. (Technische Hogeschool Delft (Netherlands). Lab. of Metallurgy)

    1990-01-01

    An analysis was made of iron carbonitride compound layer development during nitrocarburizing of pure iron and two iron-carbon specimens, containing 0.3 wt.-% C and 0.6 wt.-% C, respectively, in an aerated cyanate-based salt bath at 853 K. The microstructural evolution was followed by means of light- and scanning electron microscopy and X-ray diffraction analysis. Composition-depth profiles were determined as a function of nitrocarburizing time applying electron-probe microanalysis and X-ray diffraction analysis. Compound layer formation on pure iron starts with the nucleation of cementite at the surface, which is immediately followed by nucleation of {epsilon} carbonitride containing a relatively high carbon content and a relatively low nitrogen content. Thereafter, {gamma}' (carbo)nitride and finally {epsilon} nitride develop at the outer surface. In general, on continued nitrocarburizing the nitrogen content at the outer surface increases and the carbon content decreases. Accordingly, the constitution of the compound layer is determined to a large extent by the (difference between the) absorption kinetics of carbon and of nitrogen rather than by equilibrium thermodynamics. In the surface-adjacent region, the layers are highly porous, predominantly as a consequence of corrosive attack by agents of the salt bath. As compared with nitrocarburizing of pure iron, the major effect of carbon present as cementite in pearlite regions in the iron-carbon specimens appears to be promotion of the formation of {epsilon} carbonitride in the compound layer at the cost of {gamma}' (carbo)nitride. (orig.).

  7. Study of structure and phase composition of nanocrystal silicon carbonitride films

    CERN Document Server

    Fainer, N I; Rumyantsev, Y M; Kosinova, M L; Kuznetsov, F A

    2001-01-01

    The novel ternary silicon carbonitride films were synthesised by RPECVD using hexamethyldisilazane Si sub 2 NH(CH sub 3) sub 6 as a volatile single-source precursor. Different analysis techniques such as IR, Raman spectroscopy, ellipsometry, XPS, SEM, HRTEM, and SAED were used to study their physical and chemical properties. Maximum attention has been concentrated on the application of synchrotron radiation in structure and phase investigation of thin films. On the basis of data of SEM, HRTEM and diffraction of synchrotron radiation, it was established that silicon carbonitride films represent a distribution of nanocrystals (20-90 A) in an amorphous matrix. The nanocrystalline component is a pseudo alpha-Si sub 3 N sub 4 phase faceted by high-index planes. This phase can contain carbon atoms which have insufficient influence on the modification of the alpha-Si sub 3 N sub 4 lattice parameters due to the similar atomic radius of carbon and silicon.

  8. Anti-corrosion layer prepared by plasma electrolytic carbonitriding on pure aluminum

    Science.gov (United States)

    Wu, Jie; Zhang, Yifan; Liu, Run; Wang, Bin; Hua, Ming; Xue, Wenbin

    2015-08-01

    In this paper, plasma electrolytic carbonitriding (PEC/N) method was applied to pure aluminum for the first time. The spectroscopic characterization of plasma discharge during PEC/N process was analyzed and the electron temperature was calculated in terms of optical emission spectroscopy. The results showed the discharge plasma was in local thermal equilibrium (LTE) state. Electron concentration and electron temperature were about 6 × 1021 m-3 and 4000 K, respectively. The carbonitrided layer contained Al4C3, AlN and Al7C3N3 phases. After PEC/N treatment, the corrosion resistance of pure aluminum was significantly improved, which was related to the formation of nitride phases. This work expands the application of plasma electrolysis technology on the surface modification of low melting point metal.

  9. Zirconium carbonitride pellets by internal sol gel and spark plasma sintering as inert matrix fuel material

    Science.gov (United States)

    Hedberg, Marcus; Cologna, Marco; Cambriani, Andrea; Somers, Joseph; Ekberg, Christian

    2016-10-01

    Inert matrix fuel is a fuel type where the fissile material is blended with a solid diluent material. In this work zirconium carbonitride microspheres have been produced by internal sol gel technique, followed by carbothermal reduction. Material nitride purities in the produced materials ranged from Zr(N0.45C0.55) to Zr(N0.74C0.26) as determined by X-ray diffraction and application of Vegard's law. The zirconium carbonitride microspheres have been pelletized by spark plasma sintering (SPS) and by conventional cold pressing and sintering. In all SPS experiments cohesive pellets were formed. Maximum final density reached by SPS at 1700 °C was 87% theoretical density (TD) compared to 53% TD in conventional sintering at 1700 °C. Pore sizes in all the produced pellets were in the μm scale and no density gradients could be observed by computer tomography.

  10. Anti-corrosion layer prepared by plasma electrolytic carbonitriding on pure aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jie; Zhang, Yifan; Liu, Run; Wang, Bin; Hua, Ming [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Xue, Wenbin, E-mail: xuewb@bnu.edu.cn [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2015-08-30

    Highlights: • PEC/N can be applied to low melting point metal. • The spectroscopic characterization of plasma discharge is investigated. • Electron concentration and electron temperature are evaluated for PEC/N. • Phase composition of the carbonitrided layer is determined. • PEC/N improves the corrosion resistance of aluminum greatly. - Abstract: In this paper, plasma electrolytic carbonitriding (PEC/N) method was applied to pure aluminum for the first time. The spectroscopic characterization of plasma discharge during PEC/N process was analyzed and the electron temperature was calculated in terms of optical emission spectroscopy. The results showed the discharge plasma was in local thermal equilibrium (LTE) state. Electron concentration and electron temperature were about 6 × 10{sup 21} m{sup −3} and 4000 K, respectively. The carbonitrided layer contained Al{sub 4}C{sub 3}, AlN and Al{sub 7}C{sub 3}N{sub 3} phases. After PEC/N treatment, the corrosion resistance of pure aluminum was significantly improved, which was related to the formation of nitride phases. This work expands the application of plasma electrolysis technology on the surface modification of low melting point metal.

  11. Effect of Residual Stress on Fatigue Failure of Carbonitrided Low-Carbon Steel

    Science.gov (United States)

    Kanchanomai, C.; Limtrakarn, W.

    2008-12-01

    The effect of residual stress on fatigue behavior and mechanisms of carbonitrided AISI 1015 steel under uniaxial cyclic loading has been experimentally studied. By progressive removal of thin surface layers using an electropolishing technique and subsequent residual stress measurements using an x-ray diffraction technique, the compressive residual stress at the surface was approximately 900 MPa. The stress decreased toward the center, and became stable tensile residual stress of approximately 20 MPa. The fatigue resistance of carbonitrided AISI 1015 steel was higher than that of AISI 1015 steel due to the presence of compressive residual stress in case layer. The fatigue limit of AISI 1015 steels with and without carbonitriding was 340 and 300 MPa, respectively. Subsurface cracks initiated at the case-core interface, i.e. approximately 400 μm from the surface. With increasing number of stress cycles, the subsurface cracks coalesced and propagated intergranularly through the case layer. After some incubation cycles, the subsurface cracks reached the surface of specimen, and became a main crack. During this stage, the stress increased, and caused the formation of voids in core material. Consequently, the crack propagated through the core material, interacted with voids, and caused complete fracture.

  12. Synthesising carbo-nitrides of some d-group transition metals using a solar furnace at PSA

    OpenAIRE

    Shohoji, Nobumitsu; Oliveira, F. A. Costa; Rosa, Luís Guerra; Fernandes, Jorge Cruz; Magalhães, Teresa; Coelho, Manuel Caldeira; RODRIGUEZ, José; Canadas, Inmaculada; RAMOS, CARLOS; Martinez, Diego

    2013-01-01

    Carbo-nitride synthesis was undertaken using a solar furnace at PSA in flowing N2/Ar gas mixture under total pressure 1 atm and processing temperature T = 1600ºC for some d-group transition elements (Ti; Zr, V, Nb, Mo, W) starting from 1.5G/M (graphite/metal powder mixture with mole ratio 1.5:1) compact to ensure co-presence of free carbon with the reaction product. Clear X-ray diffraction (XRD) evidence of formation of carbo-nitride was detected for Ti (IVa group metal) showing higher N cont...

  13. Application of desirability function for optimizing the performance characteristics of carbonitrided bushes

    Directory of Open Access Journals (Sweden)

    Boby John

    2013-06-01

    Full Text Available The performance of a product is generally characterized by more than one response variable. Hence the management often faces the problem of simultaneous optimization of many response variables. This study was undertaken to simultaneously optimize the surface hardness and case depth of carbonitrided bushes. Even though lots of literature has been published on various methodologies for tackling the multi-response optimization problem, the simultaneous optimization of heat treated properties of carbonitrided bushes are not reported yet. In this research the effect of four factors and two interactions on surface hardness and case depth of carbontirded bushes were studied using design of experiments. Based on the experimental results, the expected values of the heat treated properties of the bushes were estimated for all possible combination of factors. Then the best combination which, simultaneously optimized the response variables, was arrived at using desirability function. The study showed that the optimum combination obtained through desirability function approach not only minimized the variation around the targets of surface hardness and case depth but also was superior to the ones obtained by optimizing the response variables separately. Moreover this study provides a useful and effective approach to design the production process to manufacture bushes with customer specified surface hardness and case depth targets.

  14. SURFACE HARDENING OF AUTOMOBILES AND TRACTORS PARTS BY METHOD OF LOW-TEMPERATURE CARBONITRIDING IN POWDER MEDIUM

    OpenAIRE

    Kostyk, V. O.; Kostyk, K. O.; Dolzhenko, A. S.

    2013-01-01

    Performed is strengthening of the surface layer of steel method of low-temperature carbonitriding in macrodispersed carbo - and nitrogen-bearing powder mixture. Chosen and justified the optimal technological parameters of process developed chemical-thermal processing. The diffusion coefficient of nitrogen alloyed steel 40X for the proposed treatment.

  15. SURFACE HARDENING OF AUTOMOBILES AND TRACTORS PARTS BY METHOD OF LOW-TEMPERATURE CARBONITRIDING IN POWDER MEDIUM

    Directory of Open Access Journals (Sweden)

    Kostyk, V. O.

    2013-06-01

    Full Text Available Performed is strengthening of the surface layer of steel method of low-temperature carbonitriding in macrodispersed carbo - and nitrogen-bearing powder mixture. Chosen and justified the optimal technological parameters of process developed chemical-thermal processing. The diffusion coefficient of nitrogen alloyed steel 40X for the proposed treatment.

  16. Gradient nature shaping of the 20X2H4A steel structure as a carbonitriding result

    Institute of Scientific and Technical Information of China (English)

    Kozlov; E.; V.; Malinovskaya; V.; A.; Popova; N.; A.

    2005-01-01

    The study of the shaping of the gradient structure nature appearing in constructional alloy martensite 20X2H4A steel (0.2%C, 2%Cr, 4%Ni), as a result of surface saturation by carbon and nitrogen (carbonitriding) at 920℃ in industrial conditions is made in present work by methods of optical and transmission electron microscopy.……

  17. Gradient nature shaping of the 20X2H4A steel structure as a carbonitriding result

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ The study of the shaping of the gradient structure nature appearing in constructional alloy martensite 20X2H4A steel (0.2%C, 2%Cr, 4%Ni), as a result of surface saturation by carbon and nitrogen (carbonitriding) at 920℃ in industrial conditions is made in present work by methods of optical and transmission electron microscopy.

  18. The structure study of boron carbonitride films obtained by use of trimethylamine borane complex

    CERN Document Server

    Kosinova, M L; Fainer, N I; Maximovski, E A; Kuznetsov, F A

    2001-01-01

    Diffraction of synchrotron radiation (SR) was used to investigate crystalline structure and phase composition of thin films (1500-5000 A) of boron carbonitride. These films were synthesized by plasma-enhanced chemical vapor deposition using nontraditional volatile single source precursor trimethylamine borane complex (CH sub 3) sub 3 N centre dot BH sub 3 and its mixture with ammonia. The effect of the gas ratio and substrate temperature on chemical and phase composition as well as the structure of the films were investigated. The XRD peculiarities of texture films and ways of increasing sensibility of measurements were considered. A possibility of the information density rise of the thin film XRD was shown due to application of different methods for recording diffraction patterns.

  19. Formation of titanium carbonitride film by laser treatment: Structural and transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Soni, Sheetal; Pandey, A.; Gupta, Ratnesh [School of Instrumentation, Devi Ahilya University, Khandwa Road, Indore-452001 (India); Sinha, A. K., E-mail: gratnesh-ioi@yahoo.com [Indus Synchrotron Utilization Division, Raja Ramanna Center for Advanced Technology, Indore-452013 (India)

    2015-06-24

    In-plane and Out-of-plane Grazing incidence X-ray diffraction is used to characterize the preferred orientation present in the titanium carbonitride films using ADXRD beamline at INDUS 2 synchrotron radiation source. GIXRD shows the formation of mixture of FCCTiC{sub x}N{sub (1-x)} films for different values of x along with the solid solution. From the in-plane and out-of-plane XRD measurements, we have observed that a specific texture along the c-axis of Ti has been formed during the laser treatment process. Due to the diffusion of C and N into Ti, the resistance of the specimen has been decreases with respect to the resistance of pure Ti sheet. The formed phases are stable and there is no structural relaxation has been observed during annealing process.

  20. Structural, elastic and thermodynamic properties of the tetragonal structure of germanium carbonitride

    Science.gov (United States)

    Xing, Mengjiang; Li, Binhua; Yu, Zhengtao; Chen, Qi

    2016-04-01

    The structural, mechanical, electronic and thermodynamic properties of the tetragonal structure germanium carbonitride (t-GeCN) were first investigated using the density function theory with the ultrasoft psedopotential scheme in the frame of the generalized gradient approximation and the local density approximation. The elastic constants have confirmed that the t-GeCN is mechanically stable and phonon spectra have confirmed that the t-GeCN is dynamically stable. The anisotropy studies show that t-GeCN exhibits a larger anisotropy in its Poisson's ratio, Young's modulus, shear modulus, sound velocities and universal elastic anisotropy index. Electronic structure study shows that t-GeCN is an indirect semiconductor with band gap of 0.628 eV. The thermodynamic properties of t-GeCN, including Debye temperature, heat capacity, Grüneisen parameter and thermal expansion coefficient are investigated utilizing the quasi-harmonic Debye model.

  1. EELS study of niobium carbo-nitride nano-precipitates in ferrite.

    Science.gov (United States)

    Courtois, E; Epicier, T; Scott, C

    2006-01-01

    Micro-alloying steels allow higher strength to be achieved, with lower carbon contents, without a loss in toughness, weldability or formability through the generation of a fine ferrite grain size with additional strengthening being provided by the fine scale precipitation of complex carbo-nitride particles. Niobium is reported to be the most efficient micro-alloying element to achieve refinement of the final grain structure. A detailed microscopic investigation is one of the keys for understanding the first stages of the precipitation sequence, thus transmission electron microscopy (TEM) is required. Model Fe-(Nb,C) and Fe-(Nb,C,N) ferritic alloys have been studied after annealing under isothermal conditions. However the nanometre scale dimensions of the particles makes their detection, structural and chemical characterization delicate. Various imaging techniques have then been employed. Conventional TEM (CTEM) and high resolution TEM (HRTEM) were used to characterise the morphology, nature and repartition of precipitates. Volume fractions and a statistical approach to particle size distributions of precipitates have been investigated by energy filtered TEM (EFTEM) and high angle annular dark field (HAADF) imaging. Great attention was paid to the chemical analysis of precipitates; their composition has been quantified by electron energy loss spectroscopy (EELS), on the basis of calibrated 'jump-ratios' of C-K and N-K edges over the Nb-M edge, using standards of well-defined compositions. It is shown that a significant addition of nitrogen in the alloy leads to a complex precipitation sequence, with the co-existence of two populations of particles: pure nitrides and homogeneous carbo-nitrides respectively. PMID:16500107

  2. The effect of C atom concentration on the electronic properties of boron carbonitride alloy nanotube in zig-zag form

    Indian Academy of Sciences (India)

    H Milani Moghaddam

    2011-06-01

    Electronic properties of single-walled boron nitride nanotube in zig-zag form are numerically investigated by replacing B atoms with C atoms. Using a tight-binding Hamiltonian, the methods based on Green’s function theory, Landauer formalism and Dyson equation, the electronic density of states and electronic conductance in boron nitride nanotube and boron carbonitride nanotube are calculated. Our calculations indicate that in a boron nitride nanotube, the localized states associated with C impurities appear as the concentration of C atoms increases. The boron carbonitride nanotube thus behaves like a semiconductor. Also, by increasing the C atom concentration, the voltage in the first step on the – characteristics decreases, whereas the corresponding current increases.

  3. Development of High Strength Steel Designed for Carbonitriding with High Nitrogen Content to Be Used for Automatic Transmission Gears

    Institute of Scientific and Technical Information of China (English)

    Youichi Watanabe

    2004-01-01

    To downsize and lighten automatic transmission components, the gears installed must be strengthened in terms of pitting endurance and/or wear resistance. The most important metallurgical factor affecting fractures is well known to be resistance to softening when steel is tempered at approximately 573 K. Carbonitriding with a high anount of nitrogen is a very effective production technique because nitrogen increases the resistance during tempering. However, structural anomalies begin to appear in the surface layer when the nitrogen content exceeds 0.6 mass% in the chromium steel generally used. To address this, we have developed new high-strength chromium steel with an optimized chemical composition that effectively inhibits anomalies even when carbonitriding with a nitrogen content of more than 0.6 mass%.We performed a drivetrain durability test on an automatic transmission component designed to have excellent contact fatigue strength and a tooth root bending impact and fatigue strength. We found that the developed steel that was carbonitrided with a content of about 0.9 mass%, and then shot peened hard, has a pitting life of roughly 4.5 times that of conventionally manufactured steel.

  4. Synthesis and characterization of nanocrystalline hexagonal boron carbo-nitride under high temperature and high pressure

    International Nuclear Information System (INIS)

    A study of the synthesis of hexagonal boron carbo-nitride (h-BCN) compounds via a two-step high-temperature and high-pressure (HTHP) technique using melamine (C3N6H6) and boron oxide (B2O3) as raw materials is presented. An amorphous BCN precursor was prepared at 1000 K under vacuum in a resistance furnace and then single-phase h-BCN nanocrystalline was synthesized at 1600 K and 5.1 GPa in a multi-anvil apparatus. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the final products were pure h-BCN crystals with the lattice constants a 0.2510 nm and c = 0.6690 nm. The average grain size was about 150 nm. X-ray photoelectron spectroscopy (XPS) results confirmed the occurrence of bonding between C-C, C-N, C-B and N-B atoms. Raman scattering analysis suggested that there were three strong Raman bands centered at 1359, 1596 and 1617 cm-1, respectively. The band at 1617 cm-1 was considered to be consistent with the characteristic Raman peak of h-BCN

  5. Precipitation Behaviour of Carbonitrides in Ti-Nb-C-N Microalloyed Steels and an Engineering Application with Homogenously Precipitated Nano-particles

    Directory of Open Access Journals (Sweden)

    Yanlin WANG

    2015-11-01

    Full Text Available A thermodynamic model enabling calculation of equilibrium carbonitride composition and relative amounts as a function of steel composition and temperature has been developed previously based on the chemical equilibrium method. In the present work, actual carbonitride precipitation behaviour has been verified in the Ti-Nb-C-N microalloyed steels. The Ti microalloyed steel after refining with 0.012 % Nb exhibited highly improved tensile strength without sacrificing ductility. According to further detailed SEM and TEM analysis, the improved mechanical properties of Ti/Nb microalloyed steel could be attributed to the larger solubility of Nb and Ti, inducing fine dispersion of the carbonitrides with particle size of 2 – 10 nm in the ferrite matrix.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9622

  6. Precipitation and Solid Solution of Titanium Carbonitride Inclusions in Hypereutectoid Tire Cord Steel

    Institute of Scientific and Technical Information of China (English)

    Chen-fan YU; Zheng-liang XUE; Wu-tao JIN

    2016-01-01

    The properties of titanium carbonitride Ti(Cx N1-x )inclusions precipitated during solidification of tire cord steels and the thermodynamic conditions for their decomposition and solid solution during billet heating were investigated using a thermodynamics method.The solid solution of Ti(Cx N1 -x )inclusions during high-temperature heating was also studied experimentally.The results revealed that:(1)the higher the content of carbon in the tire cord steel is, the greater the value of x in the Ti(Cx N1 -x )inclusions is;(2)the higher the content of carbon in the tire cord steel is,the earlier the Ti(Cx N1 -x )inclusions precipitated during the solidification process and the lower the solidification front temperature is during precipitation;(3)when an 82A steel sample was heated to 1 087 ℃,the Ti(Cx N1 -x )in-clusions possess the thermodynamic conditions of decomposition and solid solution;and (4)when 82A samples were heated to 1 1 50 and 1 250 ℃,the total number of Ti(Cx N1 -x )inclusions larger than 5 μm in diameter decreased by 55.0% and 70.3%,respectively.In addition,although smaller inclusions with diameter less than 2 μm continued to decompose when the sample was heated at 1 250 ℃ for 2 h and then cooled to 1 000 ℃ in the furnace,the number of inclusions larger than 5 μm in diameter increased.

  7. Characterization of Boron Carbonitride (BCN Thin Films Deposited by Radiofrequency and Microwave Plasma Enhanced Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    M. A. Mannan

    2008-01-01

    Full Text Available Boron carbonitride (BCN thin films with a thickness of ~4 µ­m were synthesized on Si (100 substrate by radiofrequency and microwave plasma enhanced chemical vapor deposition using trimethylamine borane [(CH33N.BH3] as a molecular precursor. The microstructures of the films were evaluated using field emission scanning electron microscopy (FE-SEM and X-ray diffractometry (XRD. Fourier transform infrared spectroscopy (FT-IR and X-ray photoelectron spectroscopy (XPS were used to analyze the chemical bonding state and composition of the films. It has been observed that the films were adhered well to the silicon substrate even after being broken mechanically. XRD and FE-SEM results showed that the films were x-ray amorphous, rough surface with inhomogeneous microstructure. The micro hardness was measured by nano-indentation tester and was found to be approximately 2~7 GPa. FT-IR suggested the formation of the hexagonal boron carbonitride (h-BCN phase in the films. Broadening of the XPS peaks revealed that B, C and N atoms have different chemical bonds such as B-N, B-C and C-N. The impurity oxygen was detected (13~15 at.% as B-O and/or N-O.

  8. A simple one step organic to inorganic pyrolysis route to bulk quantity boron carbonitride/carbon nanocables

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, T.; Wang, Y.P.; Yang, J.Q. [School of Materials Science and Engineering, Harbin Institute of Technology (Weihai), Weihai 264209 (China); Huang, X.X., E-mail: swliza@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wen, G., E-mail: g.w.wen.hit@gmail.com [School of Materials Science and Engineering, Harbin Institute of Technology (Weihai), Weihai 264209 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-09-15

    Highlights: • Bulk quantity boron carbonitride/carbon (BCN/C) nanocables have been synthesized by a simple one step organic to inorganic pyrolysis route. • BCN/C nanocables exhibit a much better oxidation resistance than substrate carbon nanofibers. • A probable formation mechanism of the BCN/C nanocables is proposed according to the experimental results. - Abstract: Bulk quantity boron carbonitride/carbon (BCN/C) nanocables have been successfully synthesized by a simple one step organic compounds pyrolysis route at 1100 °C. The nanocables consist of nanocarbon fibers inside covered by the cylindrical BCN coatings. The characteristics of the surface morphology and the diameters of the nanocables are determined by soaking time. It is demonstrated that the elements of B, C and N are hybridly bonded in the coating. The weight loss of the nanocables is about 12% at 1200 °C which is much better than the substrate carbon nanofibers (CNFs) (more than 20% weight loss at 1200 °C). The minimum reflection coefficient below −20 dB for the products is −24.5 dB at 14.48 GHz indicating good microwave absorption properties. The results suggest that the nanocables are favorable for achieving high performance oxidization resistance and microwave absorption properties.

  9. A Novel Martensitic Creep-Resistant Steel Strengthened by MX Carbonitrides with Extremely Low Coarsening Rates: Design and Characterization

    Science.gov (United States)

    Lu, Qi; Ma, Wenjie; Yan, Wei; Yang, Ke; Toda, Yoshiaki; van der Zwaag, Sybrand; Xu, Wei

    2016-09-01

    A general computational alloy design approach, based on thermodynamics and thermokinetics and coupled with a genetic algorithm optimization routine, was applied to the design of novel creep martensitic resistant steels. The optimal alloy suggested by the model has a high density of barely coarsening MX carbonitride precipitates. The model yielded precise values for the concentrations of the 10 alloying elements considered. The model alloy was produced on a 10 kg lab scale. Samples of the new alloy of one of the best commercial martensitic steels on the market P92 were subjected to a high aging temperature of 923 K (650 °C) for times up to 1000 hours. The microstructure of the new alloy in the as-produced state as well as after 1000 hours exposure has all the intended features as predicted by the model. The coarsening rate of the MX rate carbonitrides was substantially lower than that of the precipitates in the P92 steel. The very low coarsening rate explains the superior hardness at very long exposure times.

  10. Study of bipolar pulsed plasma electrolytic carbonitriding on nanostructure of compound layer for a gamma Ti-Al alloy

    Institute of Scientific and Technical Information of China (English)

    Mahmood ALIOFKHAZRAEI; Alireza SABOUR ROUHAGHDAM; Mohsen ROOHZENDEH

    2008-01-01

    The surface hardening of a gamma Ti-Al alloy by using bipolar pulsed nanocrystalline plasma electro-lytic carbonitriding has been studied in this investigation. Coating process was performed on a triethanolamine-based electrolyte by a cooling bath. The nanostructure of the obtained compound layer was examined with the figure analysis of the scanning electron microscopy (SEM) nanographs. The effects of the process variables, i.e., fre-quency, temperature of the electrolyte, applied voltage and treatment time, have been experimentally studied. Statistical methods were used to achieve the optimum size of the nanocrystals. Finally, the contribution percentage of the effective factors of the pulsed current was revealed, and the confirmation run showed the validity of the obtained results.

  11. Methods for and products of processing nanostructure nitride, carbonitride and oxycarbonitride electrode power materials by utilizing sol gel technology for supercapacitor applications

    Science.gov (United States)

    Huang, Yuhong; Wei, Oiang; Chu, Chung-tse; Zheng, Haixing

    2001-01-01

    Metal nitride, carbonitride, and oxycarbonitride powder with high surface area (up to 150 m.sup.2 /g) is prepared by using sol-gel process. The metal organic precursor, alkoxides or amides, is synthesized firstly. The metal organic precursor is modified by using unhydrolyzable organic ligands or templates. A wet gel is formed then by hydrolysis and condensation process. The solvent in the wet gel is then be removed supercritically to form porous amorphous hydroxide. This porous hydroxide materials is sintered to 725.degree. C. under the ammonia flow and porous nitride powder is formed. The other way to obtain high surface area nitride, carbonitride, and oxycarbonitride powder is to pyrolyze polymerized templated metal amides aerogel in an inert atmosphere. The electrochemical capacitors are prepared by using sol-gel prepared nitride, carbonitride, and oxycarbonitride powder. Two methods are used to assemble the capacitors. Electrode is formed either by pressing the mixture of nitride powder and binder to a foil, or by depositing electrode coating onto metal current collector. The binder or coating is converted into a continuous network of electrode material after thermal treatment to provide enhanced energy and power density. Liquid electrolyte is soaked into porous electrode. The electrochemical capacitor assembly further has a porous separator layer between two electrodes/electrolyte and forming a unit cell.

  12. Plasma synthesis of titanium nitride, carbide and carbonitride nanoparticles by means of reactive anodic arc evaporation from solid titanium

    Energy Technology Data Exchange (ETDEWEB)

    Kiesler, D., E-mail: dennis.kiesler@uni-due.de; Bastuck, T.; Theissmann, R.; Kruis, F. E. [University of Duisburg-Essen, Institute of Technology for Nanostructures (NST) and Center for Nanointegration Duisburg-Essen (CENIDE) (Germany)

    2015-03-15

    Plasma methods using the direct evaporation of a transition metal are well suited for the cost-efficient production of ceramic nanoparticles. In this paper, we report on the development of a simple setup for the production of titanium-ceramics by reactive anodic arc evaporation and the characterization of the aerosol as well as the nanopowder. It is the first report on TiC{sub X}N{sub 1 − X} synthesis in a simple anodic arc plasma. By means of extensive variations of the gas composition, it is shown that the composition of the particles can be tuned from titanium nitride over a titanium carbonitride phase (TiC{sub X}N{sub 1 − X}) to titanium carbide as proven by XRD data. The composition of the plasma gas especially a very low concentration of hydrocarbons around 0.2 % of the total plasma gas is crucial to tune the composition and to avoid the formation of free carbon. Examination of the particles by HR-TEM shows that the material consists mostly of cubic single crystalline particles with mean sizes between 8 and 27 nm.

  13. Atmospheric Pressure Plasma CVD of Amorphous Hydrogenated Silicon Carbonitride (a-SiCN:H) Films Using Triethylsilane and Nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan Guruvenket; Steven Andrie; Mark Simon; Kyle W. Johnson; Robert A. Sailer

    2011-10-04

    Amorphous hydrogenated silicon carbonitride (a-SiCN:H) thin films are synthesized by atmospheric pressure plasma enhanced chemical vapor (AP-PECVD) deposition using the Surfx Atomflow{trademark} 250D APPJ source with triethylsilane (HSiEt{sub 3}, TES) and nitrogen as the precursor and the reactive gases, respectively. The effect of the substrate temperature (T{sub s}) on the growth characteristics and the properties of a-SiCN:H films was evaluated. The properties of the films were investigated via scanning electron microscopy (SEM), atomic force microscopy (AFM) for surface morphological analyses, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) for chemical and compositional analyses; spectroscopic ellipsometry for optical properties and thickness determination and nanoindentation to determine the mechanical properties of the a-SiCN:H films. Films deposited at low T{sub s} depict organic like features, while the films deposited at high T{sub s} depict ceramic like features. FTIR and XPS studies reveal that an increases in T{sub s} helps in the elimination of organic moieties and incorporation of nitrogen in the film. Films deposited at T{sub s} of 425 C have an index of refraction (n) of 1.84 and hardness (H) of 14.8 GPa. A decrease in the deposition rate between T{sub s} of 25 and 250 C and increase in deposition rate between T{sub s} of 250 and 425 C indicate that the growth of a-SiCN:H films at lower T{sub s} are surface reaction controlled, while at high temperatures film growth is mass-transport controlled. Based on the experimental results, a potential route for film growth is proposed.

  14. Silicon carbonitride by remote microwave plasma CVD from organosilicon precursor: Growth mechanism and structure of resulting Si:C:N films

    Energy Technology Data Exchange (ETDEWEB)

    Blaszczyk-Lezak, I. [Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, PL-90-363 Lodz (Poland); Wrobel, A.M. [Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, PL-90-363 Lodz (Poland)]. E-mail: amwrobel@bilbo.cbmm.lodz.pl; Kivitorma, M.P.M. [Department of Physics, University of Turku, FIN-20014 Turku (Finland); Vayrynen, I.J. [Department of Physics, University of Turku, FIN-20014 Turku (Finland); Tracz, A. [Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, PL-90-363 Lodz (Poland)

    2007-06-30

    The remote microwave hydrogen plasma chemical vapor deposition (RP-CVD) from bis(dimethylamino)methylsilane precursor was used for the synthesis of silicon carbonitride (Si:C:N) films. The effect of thermal activation on the RP-CVD process was examined by determining the mass- and the thickness-based film growth rate and film growth yield, at different substrate temperature (T {sub S}). It was found that the mechanism of the process depends on T {sub S} and for low substrate temperature regime, 30 deg. C {<=} T {sub S} {<=} 100 deg. C, RP-CVD is limited by desorption of film-forming precursors, whereas for high substrate temperature regime, 100 deg. C < T {sub S} {<=} 400 deg. C, RP-CVD is a non-thermally activated and mass-transport limited process. The Si:C:N films were characterized by X-ray photoelectron and Fourier transform infrared spectroscopies, as well as by atomic force microscopy. The increase of T {sub S} enhances crosslinking in the film via the formation of nitridic Si-N and carbidic Si-C bonds. On the basis of the structural data a hypothetical crsosslinking reactions contributing to silicon carbonitride network formation have been proposed.

  15. Atom Probe Tomography Study of Multi-microalloyed Carbide and Carbo-Nitride Precipitates and the Precipitation Sequence in Nb-Ti HSLA Steels

    Science.gov (United States)

    Kapoor, Monica; O'Malley, Ronald; Thompson, Gregory B.

    2016-05-01

    Composition analysis of carbide and carbo-nitride precipitates was performed for two Nb-Ti microalloyed steels with yield strengths of 750 and 580 MPa using an atom probe study. In the high-Ti 750 MPa steel, Ti-rich (Ti,Nb)(C,N) and Ti-rich (Ti,Nb)(C) precipitates were observed. In the high-Nb 580 MPa steel, a Ti-rich (Ti,Nb)(C,N) precipitate and (Ti,Nb)(C) clusters were noted. These (Ti,Nb)(C) clusters in the high-Nb 580 MPa steel were smaller than the (Ti,Nb)(C) precipitates in high-Ti 750 MPa steel. In general, a larger number of precipitates were found in the high-Ti 750 MPa steel. This difference in the number density of the precipitates between the two steels is attributed to the difference in Ti content. Combining the atom probe tomography results and thermodynamic calculations, the precipitation sequence in these alloys was inferred to be the following: as the temperature decreases, TiN precipitates out of the solution with successive (Ti,Nb)(C,N) layers of varying composition forming on these Ti-rich precipitates. Once N is depleted from the solution, a second set of (Ti,Nb)(C) precipitates in a similar manner in the matrix and also onto the carbo-nitride phase. This observation is consistent with previous observations in high-strength low-alloy steels containing comparable amounts of only Nb. It was noted that the amount of Nb, Nb/(Nb + Ti), in the precipitates decreased from 0.20 to 0.04 with the size of the precipitate. We believe that this is due to the Nb supersaturation in the matrix when these precipitates nucleate.

  16. Amorphous silicon carbonitride diaphragm for environmental-cell transmission electron microscope fabricated by low-energy ion beam induced chemical vapor deposition

    Science.gov (United States)

    Matsutani, Takaomi; Yamasaki, Kayo; Imaeda, Norihiro; Kawasaki, Tadahiro

    2015-12-01

    An amorphous silicon carbonitride (a-SiCN) diaphragm for an environmental-cell transmission electron microscope (E-TEM) was fabricated by low-energy ion beam induced chemical vapor deposition (LEIBICVD) with hexamethyldisilazane (HMDSN). The films were prepared by using gaseous HMDSN and N2+ ions with energies ranging from 300 to 600 eV. The diaphragms were applied to Si (1 0 0) and a Cu grid with 100-μm-diameter holes. With increasing ion energy, these diaphragms became perfectly smooth surfaces (RMS = 0.43 nm at 600 eV), as confirmed by atomic force microscopy and TEM. The diaphragms were amorphous and transparent to 200 kV electrons, and no charge-up was observed. Fourier transform infrared spectra and X-ray photoelectron spectra revealed that the elimination of organic compounds and formation of Si-N and C-N bonds can be promoted in diaphragms by increasing the ion impact energy. The resistance to electron beams and reaction gases in the E-cell was improved when the diaphragm was formed with high ion energy.

  17. Silicon carbonitride by remote microwave plasma CVD from organosilicon precursor: Physical and mechanical properties of deposited Si:C:N films

    Energy Technology Data Exchange (ETDEWEB)

    Blaszczyk-Lezak, I. [Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, PL-90-363 Lodz (Poland); Wrobel, A.M. [Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, PL-90-363 Lodz (Poland)]. E-mail: amwrobel@bilbo.cbmm.lodz.pl

    2007-07-15

    Silicon carbonitride (Si:C:N) films produced by the remote microwave hydrogen plasma chemical vapor deposition (RP-CVD) using bis(dimethylamino)methylsilane as single-source precursor and hydrogen as an upstream gas for plasma generation, were examined in terms of their physical (density) and mechanical (hardness, elastic modulus, friction coefficient, and 'plasticity index') properties. The effect of substrate temperature (varied in the range of 30-400 {sup o}C) on the properties of Si:C:N films is presented. A reasonable compositional and structural dependencies of film properties were determined using, respectively, the XPS atomic concentration ratios N/Si and C/Si, as well as the relative integrated intensities of the IR absorption bands from the Si-N and Si-C bonds (controlled by deposition temperature), evaluated in the first part of this work. In view of their good mechanical properties, Si:C:N films seem to be useful coatings for improving surface mechanics of engineering materials.

  18. Synthesis of complex carbonitride powders Ti{sub y}M{sub T1-y}C{sub x}N{sub 1-x} (M{sub T}: Zr, V, Ta, Hf) via a mechanically induced self-sustaining reaction

    Energy Technology Data Exchange (ETDEWEB)

    Cordoba, Jose M., E-mail: jmcordoba@icmse.csic.e [Instituto de Ciencia de Materiales de Sevilla, Centro Mixto CSIC-US, Americo Vespucio 49, 41092 Sevilla (Spain); Aviles, Miguel A.; Sayagues, Maria J.; Alcala, Maria D.; Gotor, Francisco J. [Instituto de Ciencia de Materiales de Sevilla, Centro Mixto CSIC-US, Americo Vespucio 49, 41092 Sevilla (Spain)

    2009-08-12

    The machinability of materials is a dynamic field with enormous implications in different industrial sectors because manufacturers are constantly looking for improvements that can increase the overall productivity. Manufacturers of cutting tool inserts need to develop products that can perform at higher speeds and last longer under increasingly rigorous operating conditions. It has been revealed that cermets may exhibit better properties and performances when solid solution of multiple hard compounds is added instead of a mixture of several binary ones. In this work, a mechanically induced self-sustaining reaction (MSR) is described as a suitable synthesis method to obtain a wide range of different new quaternary carbonitride systems by milling mixtures of elemental powders of transition metals and graphite in a nitrogen atmosphere. Characterization was carried out using X-ray powder diffraction, elemental analysis, energy dispersive X-ray analysis (EDX), scanning and transmission electron microscopy and electron diffraction (ED).

  19. Study of carbonitriding thermochemical treatment by plasma screen in active with pressures main austenitic stainless steels AISI 409 and AISI 316L; Estudo do tratamento termoquimico de carbonitretacao por plasma em tela ativa com pressoes variaveis nos acos inoxidaveis austenitico AISI 316L e ferririco AISI 409

    Energy Technology Data Exchange (ETDEWEB)

    Melo, M.S.; Oliveira, A.M.; Leal, V.S.; Sousa, R.R.M. de; Alves Junior, C. [Centro Federal de Educacao Tecnologica do Maranhao (CEFET/MA), Sao Luis, MA (Brazil); Centro Federal de Educacao Tecnologica do Piaui (CEFET/PI), Teresina, PI (Brazil); Universidade Federal do Rio Grande do Norte (DF/UFRN), Natal, RN (Brazil). Dept. de Fisica. Labplasma

    2010-07-01

    The technique called Active Screen Plasma Nitriding (ASPN) is being used as an alternative once it offers several advantages with respect to conventional DC plasma. In this method, the plasma does not form directly in the sample's surface but on a screen, in such a way that undesired effects such as the edge effect is minimized. Stainless steels present not very satisfactory wearing characteristics. However, plasma carbonitriding has been used as to improve its resistance to wearing due to the formation of a fine surface layer with good properties. In this work, samples of stainless steel AISI 316L and AISI 409 were treated at pressures of 2.5 and 5 mbar. After the treatments they were characterized by microhardness, microscopy and Xray diffraction. Microscopy and hardness analysis showed satisfactory layers and toughness in those steels. (author)

  20. New method for synthesis of metal carbides, nitrides and carbonitrides

    Energy Technology Data Exchange (ETDEWEB)

    Koc, R.; Folmer, J.S.; Kodambaka, S.K. [Southern Illinois Univ., Carbondale, IL (United States)] [and others

    1997-04-01

    The purpose of this work is to develop a novel synthesis method using a carbothermic reduction reaction of carbon coated precursors for producing high purity, submicron, non-agglomerated powders of metal carbide, metal nitride and metal boride systems. The authors also want to demonstrate the advantages of the process and provide information on the applicability of the process for synthesizing related advanced ceramic powders (e.g. SiC, WC, TiN, TiB{sub 2}, Si{sub 3}N{sub 4}). During the FY96 of the project, steps are taken to investigate the reaction mechanisms and phase evolution during the formation of TiC from carbon coated titania precursors and to produce submicron TiC powders with desired stoichiometries. Depending on the carbon content in the coated titania precursor, TiC powder was produced with different stoichiometries (different amount of oxygen and free carbon).

  1. Carbonitride based phosphors and light emitting devices using the same

    Science.gov (United States)

    Li, Yuanqiang; Tian, Yongchi; Romanelli, Michael Dennis

    2013-08-20

    Disclosed herein is a novel group of carbidonitride phosphors and light emitting devices which utilize these phosphors. In certain embodiments, the present invention is directed to a novel family of carbidonitride-based phosphors expressed as follows: Ca.sub.1-xAl.sub.x-xySi.sub.1-x+xyN.sub.2-x-xyC.sub.xy:A; (1) Ca.sub.1-x-zNa.sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xyC.sub.xy:- A; (2) M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x- -xyC.sub.xy:A; (3) M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xy-2w/- 3C.sub.xyO.sub.w-v/2H.sub.v:A; and (4) M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xy-2w/- 3-v/3C.sub.xyO.sub.wH.sub.v:A, (4a) wherein 0xy+z, and 0

  2. Development of compound layer of iron (carbo)nitrides during nitriding of steel

    DEFF Research Database (Denmark)

    Ratajski, J.; Tacikowski, J.; Somers, Marcel A.J.

    2003-01-01

    The composition and phase constitution of a compound layer developing during gaseous nitriding was investigated at 853 K for three commercial steels (AISI 120, 4340 and 1090) and Armco iron. The compound layers were characterised by light optical microscopy, X-ray diffraction and electron probe...... microanalysis. The formation of the compound layer occurs along two distinct sequences: alpha-gamma prime-epsilon and/or alpha(theta)-epsilon2-gamma prime-epsilon1. The preferred sequence depends mainly on the chemical composition of steel and on the nitriding potential....

  3. Carbonitride precipitation during hot direct rolling of nb-microalloyed steel

    International Nuclear Information System (INIS)

    Small ingots of Nb-microalloyed steels were cast in hot ceramic mould in order to simulate larger castings. The as- cast austenite was direct rolled in three passes from an initial thickness of 15mm to 4mm. In a series of experiments, first passes were applied in the temperature range 1200-1010 degree C, second passes between 1100-960 degree C and third passes between 1000-920 degree C. The ingots were quenched just after casting, or just before entry to or after exit from each pass to investigate changes in the precipitation of NbCN. Samples of the ingots quenched at different stages during processing were then tempered for 1 hour at 600 degree C to assess the amount of NbCN in solution at the quench temperature. As-cast austenite prior to the commencement of rolling was found to be undersaturated and Nb-based eutectic precipitates were present at high temperatures. These were stable during cooling, and supersaturation did not occur until the ingot temperature fell below 1100 degree C. Besides the eutectic precipitates, fine strain induced NbCN precipitates were present after first, second and third passes. It was found that these precipitates remove a small amount of Nb from solution. (author)

  4. Thermal Contact Conductance Analysis of Nitride and Carbonitride Thin Film Coatings for Thermal Interface Material Application

    Science.gov (United States)

    Subramani, Shanmugan; Thing, Lee Yuan; Devarajan, Mutharasu

    2015-12-01

    In order to reduce and maintain the bond line thickness between substrate and LED package, solid thin film with good thermal conductivity is suggested as thermal interface material and the proposed film thickness is about less than 1 µ. The surface parameter such as roughness and hardness is a key factor which alters the contact conductance between the two matt surfaces. Consequently, filtered vacuum cathodic arc deposited nitride thin films (CrN, TiN, AlTiN, and TiCN) on copper substrate were tested for thermal interface material applications in electronic packaging. The thermal contact conductance of the prepared thin films was evaluated using surface properties such as microhardness and surface roughness. The results were verified with the theoretical model. The measured microhardness and surface roughness of CrN thin film are 17 GPa (low) and 0.768 µm (high), respectively. The measured thermal contact conductance of all thin films showed linear properties for applied pressure and very close to the values of theoretical model. High value in thermal contact conductance of about 256 W/m2 K was noticed with CrN thin film at 1100 kPa. The percentage of deviation for our measured contact conductance value from the theoretical model value was decreasing for the increased contact pressure and observed low value (7 pct) for CrN thin film at 1100 kPa. The thermal conductivity of all thin films was also calculated from the conductance model and observed high value (19.34 W/mK) with CrN thin film.

  5. Titanium carbonitride thick coating prepared by plasma spray synthesis and its tribological properties

    Institute of Scientific and Technical Information of China (English)

    ZHU Lin; HE JiNing; YAN DianRan; XIAO LiSong; DONG YanChun; XUE DingChuan; MENG DeLiang

    2007-01-01

    TiCN coating,owing to its superior wear-resistance,has been frequently applied in many fields. TiCN thick coating was first prepared by reactive plasma spraying. The phase composition,microstructure and tribological properties of the TiCN coating were investigated in this research. Experimental results show that the microstructure of the TiCN coating was quite dense,and there was also a little amount of titanium oxides within the coating. By XPS analysis,Ti-C and Ti-N bonds were detected in the coating. The TiCN coating exhibited superior wear-resistance. The failure mechanism was attributed to the adhesive wear,the grinding of TiCN hard-grain,as well as the coating failure by oxidation. There were more Fe,Cr,O,etc. in the failure zone,suggesting that the corrosion propagated gradually from surface to interior.

  6. Optical and electrical characteristics of plasma enhanced chemical vapor deposition boron carbonitride thin films derived from N-trimethylborazine precursor

    Energy Technology Data Exchange (ETDEWEB)

    Sulyaeva, Veronica S., E-mail: veronica@niic.nsc.ru [Department of Functional Materials Chemistry, Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Kosinova, Marina L.; Rumyantsev, Yurii M.; Kuznetsov, Fedor A. [Department of Functional Materials Chemistry, Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Kesler, Valerii G. [Laboratory of Physical Principles for Integrated Microelectronics, Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090 (Russian Federation); Kirienko, Viktor V. [Laboratory of Nonequilibrium Semiconductors Systems, Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090 (Russian Federation)

    2014-05-02

    Thin BC{sub x}N{sub y} films have been obtained by plasma enhanced chemical vapor deposition using N-trimethylborazine as a precursor. The films were deposited on Si(100) and fused silica substrates. The grown films were characterized by ellipsometry, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, spectrophotometry, capacitance–voltage and current–voltage measurements. The deposition parameters, such as substrate temperature (373–973 K) and gas phase composition were varied. Low temperature BC{sub x}N{sub y} films were found to be high optical transparent layers in the range of 300–2000 nm, the transmittance as high as 93% has been achieved. BC{sub x}N{sub y} layers are dielectrics with dielectric constant k = 2.2–8.9 depending on the synthesis conditions. - Highlights: • Thin BC{sub x}N{sub y} films have been obtained by plasma enhanced chemical vapor deposition. • N-trimethylborazine was used as a precursor. • Low temperature BC{sub x}N{sub y} films were found to be high optical transparent layers (93%). • BC{sub x}N{sub y} layers are dielectrics with dielectric constant k = 2.2–8.9.

  7. The role of Ti carbonitride precipitates on fusion zone strength-toughness in submerged arc welded linepipe joints

    Energy Technology Data Exchange (ETDEWEB)

    Aucott, L., E-mail: la126@le.ac.uk [Department of Engineering, University of Leicester (United Kingdom); Wen, S.W., E-mail: shuwen.wen@tatasteel.com [Department of Engineering, University of Leicester (United Kingdom); Tata Steel, Swinden Technology Centre, Rotherham (United Kingdom); Dong, H., E-mail: hd38@le.ac.uk [Department of Engineering, University of Leicester (United Kingdom)

    2015-01-12

    The role of micro-alloying in the submerged arc welding (SAW) of high strength low alloy steel linepipe is paramount in facilitating the high strength properties of the linepipe. In this study, transmission electron microscopy analysis revealed the presence of large (0.85 µm) Ti (C,N) precipitates within the predominantly acicular ferrite SAW joint. Cross-weld Vickers hardness and Charpy impact tests revealed that the fusion zone has high hardness and low toughness properties in relation to the base metal and heat affected zone. Fractography observations made on the ductile fracture surface of the fusion zone revealed a high number of the large Ti (C,N) precipitates to be located within the microvoids – suggesting their role in nucleating microvoids. Finally, fracture micro-mechanics are used to evaluate the relationship between the coarse precipitates and reduced strength-toughness properties in the SAW weld of the API-5L grade X65 linepipe steel.

  8. The role of Ti carbonitride precipitates on fusion zone strength-toughness in submerged arc welded linepipe joints

    International Nuclear Information System (INIS)

    The role of micro-alloying in the submerged arc welding (SAW) of high strength low alloy steel linepipe is paramount in facilitating the high strength properties of the linepipe. In this study, transmission electron microscopy analysis revealed the presence of large (0.85 µm) Ti (C,N) precipitates within the predominantly acicular ferrite SAW joint. Cross-weld Vickers hardness and Charpy impact tests revealed that the fusion zone has high hardness and low toughness properties in relation to the base metal and heat affected zone. Fractography observations made on the ductile fracture surface of the fusion zone revealed a high number of the large Ti (C,N) precipitates to be located within the microvoids – suggesting their role in nucleating microvoids. Finally, fracture micro-mechanics are used to evaluate the relationship between the coarse precipitates and reduced strength-toughness properties in the SAW weld of the API-5L grade X65 linepipe steel

  9. Molecular precursor derived silicon boron carbonitride/carbon nanotube and silicon oxycarbide/carbon nanotube composite nanowires for energy based applications

    Science.gov (United States)

    Bhandavat, Romil

    Molecular precursor derived ceramics (also known as polymer-derived ceramics or PDCs) are high temperature glasses that have been studied for applications involving operation at elevated temperatures. Prepared from controlled thermal degradation of liquid-phase organosilicon precursors, these ceramics offer remarkable engineering properties such as resistance to crystallization up to 1400 °C, semiconductor behavior at high temperatures and intense photoluminescence. These properties are a direct result of their covalent bonded amorphous network and free (-sp2) carbon along with mixed Si/B/C/N/O bonds, which otherwise can not be obtained through conventional ceramic processing techniques. This thesis demonstrates synthesis of a unique core/shell type nanowire structure involving either siliconboroncarbonitride (SiBCN) or siliconoxycarbide (SiOC) as the shell with carbon nanotube (CNT) acting as the core. This was made possible by liquid phase functionalization of CNT surfaces with respective polymeric precursor (e.g., home-made boron-modified polyureamethylvinylsilazane for SiBCN/CNT and commercially obtained polysiloxane for SiOC/CNT), followed by controlled pyrolysis in inert conditions. This unique architecture has several benefits such as high temperature oxidation resistance (provided by the ceramic shell), improved electrical conductivity and mechanical toughness (attributed to the CNT core) that allowed us to explore its use in energy conversion and storage devices. The first application involved use of SiBCN/CNT composite as a high temperature radiation absorbant material for laser thermal calorimeter. SiBCN/CNT spray coatings on copper substrate were exposed to high energy laser beams (continuous wave at 10.6 mum 2.5 kW CO2 laser, 10 seconds) and resulting change in its microstructure was studied ex-situ. With the aid of multiple techniques we ascertained the thermal damage resistance to be 15 kW/cm -2 with optical absorbance exceeding 97%. This represents one order of magnitude improvement over bare CNTs (1.4 kW/cm-2) coatings and two orders of magnitude over the conventional carbon paint (0.1 kW/cm -2) currently in use. The second application involved use of SiBCN/CNT and SiOC/CNT composite coatings as energy storage (anode) material in a Li-ion rechargeable battery. Anode coatings (~1mg/cm-2) prepared using SiBCN/CNT synthesized at 1100 °C exhibited high reversible (useable) capacity of 412 mAh/g -1 even after 30 cycles. Further improvement in reversible capacity was obtained for SiOC/CNT coatings with 686 mAh/g-1 at 40 cycles and approximately 99.6% cyclic efficiency. Further, post cycling imaging of dissembled cells indicated good mechanical stability of these anodes and formation of a stable passivating layer necessary for long term cycling of the cell. This improved performance was collectively attributed to the amorphous ceramic shell that offered Li storage sites and the CNT core that provided the required mechanical strength against volume changes associated with repeated Li-cycling. This novel approach for synthesis of PDC nanocomposites and its application based testing offers a starting point to carry out further research with a variety of PDC chemistries at both fundamental and applied levels.

  10. Method of production of austenitic stainless and refractory steels stabilized with titanium, with guaranteed low occurrence of nitride and carbonitride colonies

    International Nuclear Information System (INIS)

    The claim of the invention consists in steel microalloying at casting temperature in the cradle with an addition of calcium or potassium such as to achieve its final level in the steel to be 10 to 250 ppm; the ratio of the sum of calcium and potassium levels to the sulfur level should range within 0.4 and 3.0. It is advantageous to do microalloying after previous vacuum degassing of the steel in the cradle. Using the method, it is possible to achieve inexpensive and reliable increase in purity and improvement of corrosion and mechanical properties of stabilized austenitic stainless steels. (A.K.)

  11. 碳氮共渗

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Characterisation and application of titanium carbonitride-based cutting tools;Composite ceramics and coatings for tribotechnical application; Crystallization of polymer-derived silicon carbonitride at 1873 K under nitrogen overpressure;1 Effect of cooling conditions on plasma-carbonitrided iron surfaces

  12. SiCN based Anode Materials for Lithium-Ion Batteries

    OpenAIRE

    Reinold, Lukas Mirko

    2016-01-01

    This thesis deals with the investigation of polymer-derived silicon carbonitride based anode materials for their application in lithium-ion batteries. Carbon-rich silicon carbonitrides are obtained by a pyrolysis of different organosilicon precursors, namely poly(phenylvinylsilylcarbodiimide), poly(phenylvinylsilazane), poly(diphenylsilylcarbodiimide), poly(phenylsilsesquicarbodiimide) and poly(phenylsilsesquiazane). The materials are characterized by means of Raman spectroscopy, elemental an...

  13. STRENGTHENING MECHANISMS IN Nb-Ti-V MICROALLOYED STEEL

    Directory of Open Access Journals (Sweden)

    Vinícius Lopes Vieira Martins

    2014-10-01

    Full Text Available Yield strength of Nb-Ti-V microalloyed steel has been investigated as a function of its microstructure obtained after industrial rolling on a hot strip mill. Optical (OM and transmission electron microscopy (TEM were used to reveal the ferrite grain structure, fine carbonitride precipitation and dislocation substructures. It was found that the effects of solid solution and grain size hardening were not sufficient to justify the results of tensile testing. Additional strengthening was attributed to carbonitride precipitation in austenite, interphase precipitation during transformation, and the formation of dislocations. All contributions of these microstructural features on mechanical property were estimated from empirical models available from literature. A global effect of both austenite and interphase carbonitride precipitation hardening was proposed. It was verified that yield strength calculated from cumulative effect of different strengthening mechanisms has presented good fitting with experimental tensile test.

  14. Effect of carbon on interstitial ordering and magnetic properties of ε-Fe2(N,C)1-z

    DEFF Research Database (Denmark)

    Brink, Bastian; Ståhl, Kenny; Christiansen, Thomas Lundin;

    2017-01-01

    Hexagonal ε-iron nitride and ε-iron carbonitride phases are formed on nitriding and nitrocarburizing ofiron and steel surfaces and can exist in broad compositional ranges. Long-range nitrogen ordering andmagnetic properties for ε-iron nitrides and their dependence on composition have been the focus...

  15. The ternary Fe-C-N system: Homogeneous distributions of nitrogen and carbon

    DEFF Research Database (Denmark)

    Brink, Bastian; Ståhl, Kenny; Christiansen, Thomas Lundin;

    2017-01-01

    Porous iron foils were used for synthesizing homogeneous samples of iron carbides and (carbo)nitrides. Homogeneous distributions of interstitial nitrogen and carbon were obtained without long treatment times due to limited required diffusion distances in the porous material. By adjustments of the...

  16. Selected Topics on Mass Transport in Gas-solid Interactions

    DEFF Research Database (Denmark)

    Somers, Marcel A.J.

    2004-01-01

    -controlled dissolution of carbon in an austenite matrix, nucleation of nitrides at an iron surface, the competition between surface reaction and solid state diffusion during iron-nitride layer growth and the evolution of the morphology of a carbonitride layer during nitrocarburizing. The work presented focuses...

  17. Comparative study of the tribological behavior under hybrid lubrication of diamond-like carbon films with different adhesion interfaces

    Science.gov (United States)

    Costa, R. P. C.; Lima-Oliveira, D. A.; Marciano, F. R.; Lobo, A. O.; Corat, E. J.; Trava-Airoldi, V. J.

    2013-11-01

    This paper reports the influence of the adhesion interlayer between stainless steel and diamond-like carbon (DLC) films in two different contact conditions: in dry air and deionized water. The water was the liquid used to understand the mechanism and chemical reactions of the tribolayer formation under boundary lubrication. The effect of silicon and carbonitride adhesion interlayer was investigated on uncoated and coated DLC films. The results show that DLC/DLC pairs using carbonitride in air (30% RH) showed 60% less friction coefficient and wear less than three orders of magnitude than DLC/DLC pairs using silicon as interlayer. In deionized water, DLC/DLC pairs using carbonitride as interlayer showed 31% less friction coefficient when compared to DLC/DLC pairs with silicon. Raman related the chemical and structural changes in the DLC films during sliding in air and in the presence of water. Scratch tests showed a critical load of 14 N and 33 N in DLC films with silicon and carbonitride, respectively.

  18. Precipitates in Steels With Ti Additive Produced by CSP Process

    Institute of Scientific and Technical Information of China (English)

    LOU Yan-zhi; LIU De-lu; NI Xiao-qing

    2009-01-01

    Hot strips of low carbon steels with Ti additive [contain C 0.04%-0.07%, Si≤0. 6%, Mn≤0. 6%,Ti 0.06%-0.14% (mass percent)] produced by EAF-CSP (Electric Arc Furnaces-Compact Strip Production)process were examined by TEM, HREM and XRD. Carbonitrides with different N/C ratio were found in the samples. The varying composition of the Ti-carbonitrides resulted from the supersaturation of Ti and temperature at which the compound was formed. In the tested steel, total mass fraction of the precipitates including cementite, carbonitride and a small quantity of Fe3O4, Al2O3, Ti2 CS and AlN was about 0. 305%. XRD results showed that about a quarter of the powder extracted by electrolysis was titanium nitrides, carbonitrides and carbides. Particle arrays formed by interphase precipitation could be observed either in slabs or in hot strips. The dominant reaction mechanisms were discussed. Compared with the conventional cold charge process, small amount of Ti addition would be more effective for precipitation of fine precipitates in the steels produced by CSP process.

  19. The aging by precipitation of Nb (C,N) in extra low carbon content steel

    International Nuclear Information System (INIS)

    Carbonitride precipitation has been studied in a high-niobium acicular - ferrite - type steel. Interphase precipitation occurred only in those samples in which high transformation temperatures led to distinctly polygonal-ferrite microestructures. In this latter case, precipitation occurred during a subsequent aging treatment, with a strong tendency for heterogeneous nucleation on dislocations. (Author)

  20. Microalloyed V-Nb-Ti and V steels Pt. 2 - precipitation behaviour during processing of structural beams

    Energy Technology Data Exchange (ETDEWEB)

    Tanniru, M.; Shanmugam, S.; Misra, R.D.K.; Panda, D.; Jansto, S.

    2005-02-15

    A comparative evaluation of the precipitation behaviour in V-Nb-Ti and V steels using transmission electron microscopy was undertaken to study the effective cumulative role of the microalloying additions. While the mechanical properties were similar, there were significant differences in the precipitation behaviour of the two steels. The microstructure of the V-Nb-Ti and V steels consisted predominantly of polygonal ferrite and fine pearlite; in addition, the former contained a small amount of bainite. The V-Nb-Ti steel exhibited significantly greater precipitation of carbonitrides compared with the V steel. In the V-Nb-Ti steel the carbonitrides precipitated as compounds (triplex and duplex type) of Ti, Nb, and V, while in the V steel they were V(C,N). They were characterised by cuboid (45-70 nm), spherical/irregular (20-45 nm), and fine/needleshaped (10-20 nm) morphology. The carbonitride precipitates grew as multimicroalloying compounds, depending on the processing conditions, as the number of microalloying elements increased. Coarse carbonitrides tended to precipitate preferentially along the grain boundaries, whereas fine carbides were dispersed in the matrix. The stoichiometric ratio of triplex carbonitrides in the V-Nb-Ti steel was Ti{sub 0.55}Nb{sub 0.35}V{sub 0.10}, while those of duplex type were Ti{sub 0.95}V{sub 0.05}, Nb{sub 0.70}V{sub 0.30}, and Ti{sub 0.73}Nb{sub 0.27}. Three microalloying elements (Ti, Nb, V) formed a coherent M{sub 4}C{sub 3} type of carbide in the V-Nb-Ti steel and exhibited short range order with the ferrite matrix, displayed by the diffraction pattern as a 'chemically sensitive' or 'superlattice' reflection. However, Nb formed the finest carbides (< 2 nm) and exhibited a ring form of selected area diffraction pattern. The carbonitrides that precipitated in the ferrite followed Baker-Nutting orientation relationships, and their partitioning was not observed in the pearlite or bainitic ferrite. The bainite

  1. Study creep in 4340 steels with different microstructure and plasma carbon nitridation processing; Estudo de fluencia em acos 4340 com diferentes microestruturas e tratamento de carbonitretacao a plasma

    Energy Technology Data Exchange (ETDEWEB)

    Abdalla, A.J., E-mail: abdalla@ieav.cta.b [Departamento de Ciencia e Tecnologia Aeroespacial (IEAv/DCTA), Sao Jose dos Campos, SP (Brazil). Inst. de Estudos Avancados; Carrer, I.R.; Barboza, M.J.R.; Baggio-Scheid, V.H. [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia; Moura Neto, C.; Reis, D.A.P. [Departamento de Ciencia e Tecnologia Aeroespacial (ITA/DCTA), Sao Jose dos Campos, SP (Brazil). Inst. Tecnologico de Aeronautica

    2010-07-01

    From the AISI 4340 bars specimens were made-for-test of creep, they were subjected to different heat treatments for the formation of multiphase microstructures. After this initial treatment, a lot of the specimens were tested in creep. One second batch of specimens was treated with a plasma carbonitriding, and later, were also tested. The carbonitriding layer and microstructure were characterized with X-ray analysis, laser confocal microscopy and hardness testing. Tests showed that the hardness in the steel was reduced due to thermochemical treatment at 500 deg C. We observed variation in creep behavior due to different microstructures formed. After the plasma treatment, there was a considerable reduction in the rate of creep and an increase in the time required for fracture. (author)

  2. Influence of second phase particles on the deformation of. alpha. -Fe at cryogenic temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Yue, S.; Bratina, W.J. (Univ. of Toronto (Canada))

    The deformation of fine grained polygonal ferrite (HSLA) steels was shown to be sensitive to variations in second phase particle characteristics. In particular a steel which contained a dispersion of fine niobium carbonitrides exhibited virtually no elongation to fracture at 77K, whereas a steel containing both fine niobium carbonitrides and coarser Fe{sub 3}C type particles exhibited considerable Luders strain and strain to fracture at 77K. It was observed that for the first steel, necking coincided with the nucleation of a Luders band whereas in the second steel, the nucleated Luders band propagated along the entire gauge length even at 77K. Luders band propagation and the delay of the onset of necking are connected by work hardening which, in turn, is governed by microstructural parameters such as grain size and second phase particles and it is these that result in this contrasting deformation behavior at 77K.

  3. XPS, XRD and laser raman analysis of surface modified of 6150 steel substrates for the deposition of thick and adherent diamond-like carbon coatings

    OpenAIRE

    William de Melo Silva; José Rubens Gonçalves Carneiro; Vladimir Jesus Trava-Airoldi

    2013-01-01

    Although the 6150 steel has an excellent fatigue and impact resistance, it is unsuitable to operate it when the corrosion is a limited factor. We propose here a sequence of steel pre-treatment by carburizing, carbonitriding and nitriding in order to improve the poor adhesion between Diamond Like-Carbon coatings on steel. This sequence is our attempt to reduce the difference between the coefficients of thermal expansion of steel and DLC through the graded interface. This work demonstrates the ...

  4. N-type emitters passivation through antireflective phosphorus doped a-SiCxNy:H(n) stacks

    OpenAIRE

    Orpella García, Alberto; Blanqué, Servane; Roiati, V.; Martín García, Isidro; Voz Sánchez, Cristóbal; Puigdollers i González, Joaquim; Alcubilla González, Ramón

    2009-01-01

    This paper studies the passivation of industrially textured deep silicon emitters using amorphous silicon carbonitride layers in stack configuration, deposited by plasma enhanced chemical vapor deposition. With this technique, emitter saturation current density can be decreased to values around 250 fA middot cm-2. As a consequence, open circuit voltages can be increased 25 mV achieving values around 640 mV.

  5. High-strength low-alloy (HSLA) steels: Visokotrdna malolegirana (HSLA) konstrukcijska jekla:

    OpenAIRE

    Skobir Balantič, Danijela Anica

    2011-01-01

    Micro-alloyed, high-strength, low-alloy (HSLA) steels are important structural materials and contain small amounts of alloying elements, such as niobium, titanium, vanadium, and aluminium, which enhance the strength through the formation of stable carbides, nitrides or carbonitrides and have an effect on the hardenability. Such steels contain less than 0.1 % of the alloying additions, used individually or in combination. Yield strength increments of two or three times that of plain carbon-man...

  6. New approach for modelling strain induced precipitation of Nb(C,N) in HSLA steels during multipass hot deformation in austenite

    OpenAIRE

    Nagarajan, V.; Palmiere, E.J.; Sellars, C.M.

    2009-01-01

    A new model for strain induced precipitation of Nb(C,N) is developed from the existing model for single pass hot deformation. This new model can be extended to multipass deformation to explain the microstructural evolution during the hot deformation of Nb supersaturated high strength low alloy (HSLA) steels. The key feature of this model is the microband geometry employed, which leads to determination of the local solute concentration at microbands, and hence the potential for carbonitride pr...

  7. Deposition of chromium nitrides, oxy-nitrides and titanium carbides on steel substrates by DC magnetron sputtering

    International Nuclear Information System (INIS)

    The present paper deals with the deposition of chromium and titanium nitrides, oxynitrides, carbides and carbonitrides onto low carbon steel by reactive magnetron sputtering. The films were obtained by using different reactive gases (02, N2, CH4,). The process advancement and the corresponding film composition variations were investigated as a function of the specific reactivity of each gas. In addition, the cathode poisoning phenomena were studied. (author). 4 refs., 6 figs

  8. Zircon Carburation Studies as Intermediate Stage in the Zirconium Fabrication; Estudios encaminados a la carburacion del circon como etapa intermedia en la obtencion de circonio

    Energy Technology Data Exchange (ETDEWEB)

    Almagro Huertas, V.; Saenz de Tejada Gonzalez, L.; Lopez Rodriguez, M.

    1963-07-01

    Zirconium carbide and carbonitride mixtures were obtained by Kroll's method.Reaction products have been identified by micrography and X-ray diffraction analysis. The optimum graphite content in the initial charge for the carburation reaction has been studied. zirconium, silicon and carbon content in the final product has been controlled as a function of current in the furnace and reaction time.Further chlorination of the final product was performed successfully. (Author) 16 refs.

  9. Electronic properties of cubic TaC{sub x}N{sub 1-x}: A comparative study using self-consistent cluster and ab initio band-structure calculations and X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lavrentyev, A.A.; Gabrelian, B.V.; Vorzhev, V.B.; Nikiforov, I.Ya. [Department of Physics, Don State Technical University, Gagarin Sq. 1, Rostov-on-Don (Russian Federation); Khyzhun, O.Yu. [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky Street, UA-03142 Kyiv (Ukraine)], E-mail: khyzhun@ipms.kiev.ua

    2009-03-20

    To investigate the influence of substitution of carbon atoms for nitrogen atoms in the cubic TaC{sub x}N{sub 1-x} carbonitrides, total and partial densities of states were calculated for TaC, TaC{sub 0.5}N{sub 0.5} and TaN compounds (NaCl structure) using the self-consistent cluster (with the FEFF8 code) and ab initio band-structure augmented plane wave + local orbitals (APW + LO) methods. In the present work a rather good agreement of the theoretical FEFF8 and APW + LO data for electronic properties of the TaC{sub x}N{sub 1-x} system under consideration was obtained. The results indicate that a strong hybridization of the Ta 5d- and C(N) 2p-like states is characteristic for the valence band of the TaC{sub x}N{sub 1-x} carbonitrides. When going from TaC to TaN through the TaC{sub 0.5}N{sub 0.5} carbonitride, the main maxima of curves representing total and partial Ta 5d densities of states shift in the direction opposite to the position of the Fermi level. In the above sequence of compounds, an increase of occupation of the near-Fermi sub-band formed by contributions of Ta 5d(t{sub 2g}) states has been detected. The theoretical FEFF8 and APW + LO results for the electronic structure of the TaC{sub x}N{sub 1-x} carbonitrides were found to be in excellent agreement with the experimental data derived in the present work employing X-ray photoelectron, emission and absorption spectroscopy methods for cubic TaC{sub 0.98}, TaC{sub 0.52}N{sub 0.49} and TaN{sub 0.97} compounds.

  10. Splitting phenomenon in martensitic transformation of X12CrMoWVNbN10-1-1 steel

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Xingang; Han, Lizhan; Gu, Jianfeng [Shanghai Jiao Tong Univ. (China). Shanghai Key Laboratory of Materials Laser Processing and Modification

    2015-06-15

    The splitting phenomenon was detected in martensitic transformation of X12CrMoWVNbN10-1-1 steel using high resolution dilatometry under certain conditions. In-situ observation of austenite grain growth was carried out. Direct experimental results indicated that this splitting is not connected with the concentration gradient in the austenite resulting from the dissolution of carbonitrides during heating, but instead may be caused by the occurrence of abnormal grain growth.

  11. Influence Of Heat Treatment On Duplex Stainless Steel To Study The Material Properties

    OpenAIRE

    Jithin M; Anees Abdul Hameed; Ben Jose; Anush Jacob

    2015-01-01

    Abstract The various heat treatment processes are annealing normalizing hardening tempering spheroidising surface hardening flame and induction hardening nitriding cyaniding carbonitriding carburizing etc Heat treatment on duplex stainless steel is to improve ductility toughness strength hardness and to relieve internal stress developed in the material. Here basically the experiment of hardness test impact test wear test and compression is done to get idea about heat treated duplex stainless ...

  12. Cathodic cage nitriding of AISI 409 ferritic stainless steel with the addition of CH4

    OpenAIRE

    Rômulo Ribeiro Magalhães de Sousa; Francisco Odolberto de Araújo; José Alzamir Pereira da Costa; Antonio Maia de Oliveira; Mineia Sampaio Melo; Clodomiro Alves Junior

    2012-01-01

    AISI 409 ferritic stainless steel samples were nitrided using the cathodic cage plasma nitriding technique (CCPN), with the addition of methane to reduce chromium precipitation, increase hardness and wear resistance and reduce the presence of nitrides when compared to plasma carbonitriding. Microhardness profiles and X-Ray analysis confirm the formation of a very hard layer containing mainly ε-Fe3N and expanded ferrite phases.

  13. Cathodic cage nitriding of AISI 409 ferritic stainless steel with the addition of CH4

    Directory of Open Access Journals (Sweden)

    Rômulo Ribeiro Magalhães de Sousa

    2012-04-01

    Full Text Available AISI 409 ferritic stainless steel samples were nitrided using the cathodic cage plasma nitriding technique (CCPN, with the addition of methane to reduce chromium precipitation, increase hardness and wear resistance and reduce the presence of nitrides when compared to plasma carbonitriding. Microhardness profiles and X-Ray analysis confirm the formation of a very hard layer containing mainly ε-Fe3N and expanded ferrite phases.

  14. Complex influence of carbon, niobium and vanadium on the mechanical properties of the structural steel S355N

    OpenAIRE

    Рябікіна, Марина Анатоліівна; Ставровська, В. Є.

    2015-01-01

    The role of microalloying additions of V, Nb, Ti manifested mainly as a result of their influence on the formation of substitution solid solution; dispersion, shape and distribution of the carbides (carbonitrides); the structure of boundaries and the fine structure of the grains; reducing the negative impact of harmful impurities. It is important to precise knowledge of the required number of microalloying elements in the steel. The objective of the present article is to review the role of Nb...

  15. Precipitate phases in normalized and tempered ferritic/martensitic steel P92

    Science.gov (United States)

    Shen, Yinzhong; Liu, Huan; Shang, Zhongxia; Xu, Zhiqiang

    2015-10-01

    Ferritic/martensitic steel P92 is a promising candidate for cladding and duct applications in Sodium-Cooled Fast Reactor. The precipitate phases of the P92 steel normalized at 1323 K (1050 °C) for 30 min and tempered at 1038 K (765 °C) for 1 h have been investigated using transmission electron microscopes. Four types of phases consisting of M23C6, MX, M2X and sigma-FeCr were identified in the steel. MX phases consist of Nb-rich M(C,N) carbonitride, Nb-rich MC carbide, V-rich M(C,N) carbonitride, V-rich MC carbide, V-rich MN nitride, and complex MC carbides with Nb-rich MC core and V-rich MC wings. M2X phases consist of Cr-rich M2(C,N) carbonitride, Cr-rich M2C carbide and M2N nitride. Sigma-FeCr has a simple tetragonal lattice and a typical chemical formula of Fe0.45Cr0.45W0.1. M23C6 and MX are the dominant phases, while the sigma-FeCr has the lowest content. The formation of sigma-FeCr and M2X phases in the steel is also discussed.

  16. Nano- and Macro-wear of Bio-carbo-nitrided AISI 8620 Steel Surfaces

    Science.gov (United States)

    Arthur, Emmanuel Kwesi; Ampaw, Edward; Zebaze Kana, M. G.; Adetunji, A. R.; Olusunle, S. O. O.; Adewoye, O. O.; Soboyejo, W. O.

    2015-12-01

    This paper presents the results of an experimental study of nano- and macro-scale wear in a carbo-nitrided AISI 8620 steel. Carbo-nitriding is carried out using a novel method that involves the use of dried, cyanide-containing cassava leaves, as sources of carbon and nitrogen. These are used in a pack cementation that is used to diffuse carbon and nitrogen into case layers at intermediate temperatures [673.15 K, 723.15 K, 773.15 K, and 823.15 K (400 °C, 450 °C, 500 °C, and 550 °C)]. Nano- and macro-scale wear properties are studied in the case-hardened surfaces, using a combination of nano-scratch and pin-on-disk experiments. The measured wear volumes (at both nano- and macro-length scales) are shown to increase with decreasing pack cyaniding temperature. The nano- and macro-wear resistances are also shown to be enhanced by the in situ diffusion of carbon and nitrogen from cyanide-containing bio-processed waste. The underlying wear mechanisms are also elucidated via atomic force microscopy and scanning electron microscopy observations of the wear tracks. The implications of the results are discussed for the design of hardened carbo-nitrided steel surfaces with improved wear resistance.

  17. Advanced WC-Co cermet composites with reinforcement of TiCN prepared by extended thermal plasma route

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, B. [Centre for Advanced Materials Processing, Central Mechanical Engineering Research Institute, Mahatma Gandhi Avenue, Durgapur 713 209, West Bengal (India)], E-mail: bnmondal@rediffmail.com; Das, P.K. [Central Glass and Ceramic Research Institute, Kolkata (India); Singh, S.K. [Institute of Minerals and Materials Technology (IIMT), Bhubeneswar (India)

    2008-12-20

    The synthesis of titanium carbonitride (TiCN) powders by thermal plasma using extended arc thermal plasma reactor and the effect of TiCN reinforcement for the development of advanced WC-Co cermets has been studied with respect to hardness and fracture toughness. These classes of materials are being investigated for future application in wear-resistant seals, cutting tools, etc. Metallurgical reactions and microstructural developments during sintering of cermets and functionally graded cemented carbonitrides are being investigated by analytical methods such as differential thermal analysis/thermo-gravimetric analysis, X-ray diffraction and analytical Scanning electron microscopy with energy dispersive X-ray spectroscopy. By an in-depth understanding of the complex phase reactions and the mechanisms that govern the sintering process and metallurgical reactions, new cermets and different types of functionally graded cemented carbonitrides with desired microstructures and properties have been attempted to develop. The significant improvement of micro-hardness was observed with optimal concentration of TiCN reinforcement addition in WC-Co system without sacrificing much fracture toughness value of the composite cermets.

  18. Recrystallization and texture in a ferritic stainless steel: An EBSD study

    Energy Technology Data Exchange (ETDEWEB)

    Sinclair, C.W. [Department of Metals and Materials Engineering, University of British Columbia, Vancouver BC V6T 1Z4 (Canada); Robaut, F.; Maniguet, L. [CMTC-INPG, St. Martin d' Heres (France); Mithieux, J.D.; Schmitt, J.H. [CRI R and D Groupe Arcelor, Isbergues (France); Brechet, Y. [LTPCM-INPG, St. Martin d' Heres (France)

    2003-08-01

    The recrystallization behavior of laboratory-processed AISI409 ferritic stainless steel sheet has been studied with a focus on texture inhomogeneity and ''sluggish'' recrystallization kinetics, mainly using EBSD in the scanning electron microscope. Pronounced texture gradients were observed in some grain orientations and correlated to the deformation-induced substructure. The strong pinning of some boundaries has been linked not only to textural effects, but also to the precipitation of fine titanium carbonitrides. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  19. Application of phase equilibria and chemical thermodynamics to the preparation, farbiration, and performance of advanced fast reactor fuel materials

    International Nuclear Information System (INIS)

    Described are some phase equilibria and chemical thermodynamics of systems relevant to the production and operation of the so-called ''advanced'' fast breeder reactor fuels. The systems discussed include UPu carbides, nitrides, oxycarbides and carbonitrides. Some examples of the application of these phase equilibria to the preparation, fabrication and behaviour of the materials in temperature gradients appropriate to reactor conditions are presented. Finally, aspects of the complex four and five component, U-C-O-N and U-Pu-C-O-N systems are discussed, a detailed knowledge of which is required for an analysis of advanced fuel behaviour

  20. Niobium in rail steels

    International Nuclear Information System (INIS)

    The strengthening capacity of niobium in high carbon steels is governed by the carbon content, soaking conditions prior to rolling and the finish rolling temperature. Yield and tensile strengths may be increased by up to 70-100 MPa (10-15 k.s.i.) in C-Mn-Cr rails with niobium additions of about 0.03 percent. The strengthening mechanism appears to be precipitation hardening of niobium carbonitride in the pro-eutectoid ferrite and ferrite lamellae in pearlite. In addition, ductility improvements may be effected through the austenite grain refining action of niobium in hot rolling leading to a reduction in pearlite colony size

  1. MOCVD of Cr-based coatings using Cr(NEt2)4 as single source precursor

    International Nuclear Information System (INIS)

    Chromium carbo-nitride coatings with low nitrogen contents have been deposited by low pressure MOCVD using Cr(NEt2)4 as single source precursor. Depositions were carried out in the temperature range 300-520 deg C either under high vacuum without carrier gas or using a partial pressure of nitrogen or hydrogen as carrier gas. All the films are X-ray amorphous and they exhibit a uniform and specular surface morphology with a metallic shiny aspect. The major volatile by-products were analyzed and a decomposition mechanism is proposed. Preliminary properties of these films are also reported. (author). 13 refs., 1 fig., 1 tab

  2. Wear Behavior of Austempered Ductile Iron with Nanosized Additives

    OpenAIRE

    J. Kaleicheva

    2014-01-01

    The microstructure and properties of austempered ductile iron (ADI) strengthened with nanosized addtives of titanium nitride + titanium carbonitride (TiN + TiCN), titanium nitride TiN and cubic boron nitride cBN are investigated. The TiN, TiCN and cBN, nanosized particles are coated by electroless nickel coating EFTTOM-NICKEL prior to the edition to the melt. The spheroidal graphite iron samples are undergoing an austempering, including heating at 900 оС for an hour, after that isotherma...

  3. Phase Evolution during the Sintering of Submicron Ti(C,N)-Based Cermets

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The submicron powder mixtures of TiC-TiN-WC-Mo-C-Ni sintered at 1400℃ or below in vacuum were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. The results showed that Mo2C formed at 800℃ or below. Both WC and Mo2C disappeared at 1200℃, and TiN disappeared at 1250℃. In addition, the variations of lattice constants of the titanium carbonitride and nickel binder phase with sintering temperature were experimentally obtained, and the reason was analyzed.

  4. New Possibilities of Shaping the Surface Properties in Austempered Ductile Iron Castings

    Directory of Open Access Journals (Sweden)

    D. Myszka

    2013-01-01

    Full Text Available The paper presents recent developments concerning the formation of surface layer in austempered ductile iron castings. It was found thatthe traditional methods used to change the properties of the surface layer, i.e. the effect of protective atmosphere during austenitising or shot peening, are not fully satisfactory to meet the demands of commercial applications. Therefore, new ways to shape the surface layer and the surface properties of austempered ductile iron castings are searched for, to mention only detonation spraying, carbonitriding, CVD methods, etc.

  5. Centreline formation of Nb(C, N) eutectic in structural steel

    OpenAIRE

    J. Bernetič; Bradaškja, B.; G. Kosec; Bricelj, E.; B. Kosec; F. Vodopivec; Kosec, L.

    2010-01-01

    The reduction of area in the through thickness direction is an essential mechanical property of thick steel heavy plates. By a routine control, a very small through thickness reduction of area was found for tensile specimen of a 90 mm plate. Careful investigations of the fracture and section of specimens cut from the as solidified continuously cast 250mmthick slab showed that the cause was the presence of coarse particles of niobium carbonitride as constituent of the quasi eutectic Fe-Nb(C, N...

  6. Atom probe field ion microscopy characterizations of VVER steels

    International Nuclear Information System (INIS)

    An atom probe field ion microscopy (APFIM) characterization of Soviet types 15Kh2MFA Cr-Mo-V (VVER 440) and 15Kh2NMFA Ni-Cr-Mo-V (VVER 1000) pressure vessel steels has been performed. Field ion microscopy has revealed that the lath boundaries in unirradiated VVER 440 and VVER 1000 steels are decorated with a thin film of brightly-imaging molybdenum carbonitride precipitates and some coarser vanadium carbides. Atom probe analysis has revealed significant enrichments of phosphorous at the lath boundaries

  7. Influence Of Heat Treatment On Duplex Stainless Steel To Study The Material Properties

    Directory of Open Access Journals (Sweden)

    Jithin M

    2015-02-01

    Full Text Available Abstract The various heat treatment processes are annealing normalizing hardening tempering spheroidising surface hardening flame and induction hardening nitriding cyaniding carbonitriding carburizing etc Heat treatment on duplex stainless steel is to improve ductility toughness strength hardness and to relieve internal stress developed in the material. Here basically the experiment of hardness test impact test wear test and compression is done to get idea about heat treated duplex stainless steel which has extensive uses in all industries and scientific research and development fields.

  8. Centreline formation of Nb(C, N eutectic in structural steel

    Directory of Open Access Journals (Sweden)

    J. Bernetič

    2010-01-01

    Full Text Available The reduction of area in the through thickness direction is an essential mechanical property of thick steel heavy plates. By a routine control, a very small through thickness reduction of area was found for tensile specimen of a 90 mm plate. Careful investigations of the fracture and section of specimens cut from the as solidified continuously cast 250mmthick slab showed that the cause was the presence of coarse particles of niobium carbonitride as constituent of the quasi eutectic Fe-Nb(C, N that form because of the centerline segregation of niobium.

  9. Effects of combined silicon and molybdenum alloying on the size and evolution of microalloy precipitates in HSLA steels containing niobium and titanium

    International Nuclear Information System (INIS)

    The effects of combined silicon and molybdenum alloying additions on microalloy precipitate formation in austenite after single- and double-step deformations below the austenite no-recrystallization temperature were examined in high-strength low-alloy (HSLA) steels microalloyed with titanium and niobium. The precipitation sequence in austenite was evaluated following an interrupted thermomechanical processing simulation using transmission electron microscopy. Large (~ 105 nm), cuboidal titanium-rich nitride precipitates showed no evolution in size during reheating and simulated thermomechanical processing. The average size and size distribution of these precipitates were also not affected by the combined silicon and molybdenum additions or by deformation. Relatively fine (< 20 nm), irregular-shaped niobium-rich carbonitride precipitates formed in austenite during isothermal holding at 1173 K. Based upon analysis that incorporated precipitate growth and coarsening models, the combined silicon and molybdenum additions were considered to increase the diffusivity of niobium in austenite by over 30% and result in coarser precipitates at 1173 K compared to the lower alloyed steel. Deformation decreased the size of the niobium-rich carbonitride precipitates that formed in austenite. - Highlights: • We examine combined Si and Mo additions on microalloy precipitation in austenite. • Precipitate size tends to decrease with increasing deformation steps. • Combined Si and Mo alloying additions increase the diffusivity of Nb in austenite

  10. Boundary and sub-boundary hardening in high-Cr ferritic steels during long-term creep at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Abe, F. [National Institute for Materials Science (NIMS) (Japan)

    2008-07-01

    The sub-boundary hardening is shown to be the most important strengthening mechanism in creep of the 9% Cr steel base metal and welded joints. The addition of boron reduces the coarsening rate of M{sub 23}C{sub 6} carbides along boundaries near prior austenite grain boundaries during creep, enhancing the sub-boundary hardening. This improves long-term creep strength. The enhancement of boundary and subboundary hardening by fine distribution of precipitates along boundaries is significantly reduced in fine-grained region of Ac{sub 3} HAZ simulated specimens of conventional steels P92 and P122. In NIMS 9% Cr boron steel welded joints, the grain size and distribution of carbonitrides are substantially the same between the HAZ and base metal, where fine carbonitrides are distributed along the lath and block boundaries as well as along prior austenite grain boundaries. This is essential for the suppression of Type IV fracture in NIMS 9% Cr boron steel welded joints. (orig.)

  11. Evolution of Ti-Based Nonmetallic Inclusions During Solution Treatment of Maraging 250 Steel: Thermodynamic Calculations and Experimental Verification

    Science.gov (United States)

    Shmulevitsh, Mati; Pinkas, Malki; Weizman, Amir; Frage, Nachum

    2011-06-01

    The evolution of Ti-based nonmetallic inclusions in Maraging 250 steel, namely Ti(CxN1-x) and Ti4C2S2, was investigated experimentally. Their stability in austenite also was analyzed by a thermodynamic analysis of the Fe-Ni-Ti-C-N-S system. It was established that the total concentration of the inclusions decreases from 0.024 pct to 0.008 pct after treatment at 1453 K (1180 °C) for 3 hours. The Ti4C2S2 inclusions completely dissolve in austenite at 1523 K (1250 °C) during 1 hour of treatment. The composition of the carbonitride inclusions is shifted toward higher TiN contents when they dissolve in austenite. Nitrogen-enriched titanium carbonitride inclusions are stable in austenite and their fraction may be reduced only by controlling nitrogen content in the steel. The experimental observations are in good agreement with the results of the thermodynamic analysis.

  12. Effects of combined silicon and molybdenum alloying on the size and evolution of microalloy precipitates in HSLA steels containing niobium and titanium

    Energy Technology Data Exchange (ETDEWEB)

    Pavlina, Erik J., E-mail: e.pavlina@deakin.edu.au [Deakin University, Institute for Frontier Materials, 75 Pigdons Road, Waurn Ponds, Victoria (Australia); Van Tyne, C.J.; Speer, J.G. [Colorado School of Mines, Advanced Steel Processing and Products Research Center, 1500 Illinois Street, Golden, CO (United States)

    2015-04-15

    The effects of combined silicon and molybdenum alloying additions on microalloy precipitate formation in austenite after single- and double-step deformations below the austenite no-recrystallization temperature were examined in high-strength low-alloy (HSLA) steels microalloyed with titanium and niobium. The precipitation sequence in austenite was evaluated following an interrupted thermomechanical processing simulation using transmission electron microscopy. Large (~ 105 nm), cuboidal titanium-rich nitride precipitates showed no evolution in size during reheating and simulated thermomechanical processing. The average size and size distribution of these precipitates were also not affected by the combined silicon and molybdenum additions or by deformation. Relatively fine (< 20 nm), irregular-shaped niobium-rich carbonitride precipitates formed in austenite during isothermal holding at 1173 K. Based upon analysis that incorporated precipitate growth and coarsening models, the combined silicon and molybdenum additions were considered to increase the diffusivity of niobium in austenite by over 30% and result in coarser precipitates at 1173 K compared to the lower alloyed steel. Deformation decreased the size of the niobium-rich carbonitride precipitates that formed in austenite. - Highlights: • We examine combined Si and Mo additions on microalloy precipitation in austenite. • Precipitate size tends to decrease with increasing deformation steps. • Combined Si and Mo alloying additions increase the diffusivity of Nb in austenite.

  13. Oxygen adsorption and dissociation during the oxidation of monolayer Ti2C

    KAUST Repository

    Gan, Li-Yong

    2013-08-20

    Exfoliated two-dimensional early transition metal carbides and carbonitrides are usually not terminated by metal atoms but saturated by O, OH, and/or F, thus making it difficult to understand the surface structure evolution and the induced electronic modifications. To fill this gap, density functional theory and molecular dynamics simulations are performed to capture the initial stage of the oxidation process of Ti2C, a prototypical example from the recently fabricated class of two-dimensional carbides and carbonitrides. It is shown that the unsaturated Ti 3d orbitals of the pristine Ti2C surface interact strongly with the approaching O2 molecules, resulting in barrierless O2 dissociation. The diffusion of the dissociated O atoms is also found to be very facile. Molecular dynamics simulations suggest that both dissociation and diffusion are enhanced as the O2 coverage increases to 0.25 monolayer. For a coverage of less than 0.11 monolayer, the adsorbates lead to a minor modification of the electronic properties of Ti2C, while the modification is remarkable at 0.25 monolayer. The formed Ti2CO2 after O saturation is an indirect narrow gap semiconductor (0.33 eV) with high intrinsic carrier concentration at room temperature and high thermodynamic stability at intermediate temperature (e.g., 550 °C).

  14. 9%Cr heat resistant steels: Alloy design, microstructure evolution and creep response at 650 deg. C

    International Nuclear Information System (INIS)

    Highlights: → 9Cr alloys with varying Ti and C contents were designed, produced and crept at 650 deg. C. → Sub-grain and precipitate distribution and evolution investigated by STEM-HAADF. → Correlations between microstructure evolution and mechanical properties were studied. → Coarsening of sub-grain size was larger for Ti-containing 9Cr alloys. → 9Cr alloy with low C and no Ti showed the highest creep strength of all studied alloys. - Abstract: In this work 9%Cr alloys were designed supported by computational thermodynamic methods. Two sets of alloys were produced: 9%Cr alloys with 0.1%C and 0.05%C and 9%Cr alloys containing ∼0.03% Ti with 0.1%C and 0.05%C (always wt%). Microstructure investigations showed good agreement with the predicted phases of the thermodynamic modeling. The volume fraction of precipitated M23C6 carbides is directly related to the carbon content of the alloys. For Ti-containing alloys the precipitation of nano-sized Ti-rich MX carbonitrides was observed. The microstructure evolution (sub-grain and particle size) during creep at 650 deg. C/100 MPa was investigated by STEM-HAADF. The sub-grain size evolution and the coarsening of precipitates (MX carbonitrides, M23C6 and Laves phase) were more pronounced for Ti-containing alloys. 9Cr alloys without Ti and with low carbon content presented the highest creep strength of all investigated alloys.

  15. Boundary and sub-boundary hardening in tempered martensitic 9Cr steel during long-term creep at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Fujio [National Institute for Materials Science, Sengen, Tsukuba (Japan)

    2010-07-01

    The boundary and sub-boundary hardening is shown to be the most important strengthening mechanism in creep of the 9% Cr steel base metal and welded joints. The addition of boron reduces the coarsening rate of M{sub 23}C{sub 6} carbides along boundaries near prior austenite grain boundaries during creep, enhancing the boundary and sub-boundary hardening. This improves long-term creep strength of base metal. The enhancement of boundary and sub-boundary hardening is significantly reduced in fine-grained region of Ac{sub 3} HAZ simulated specimens of conventional steel P92. In NIMS 9Cr boron steel welded joints, the grain size and distribution of carbonitrides are substantially the same between the HAZ and base metal, where fine carbonitrides are distributed along the lath and block boundaries as well as along prior austenite grain boundaries. This is essential for the suppression of Type IV fracture in NIMS 9% Cr boron steel welded joints. Newly alloy-designed 9Cr steel with 160 ppm boron and 85 ppm nitrogen exhibits much higher creep rupture strength of base metal than P92 and also no Tpe-IV fracture in welded joints at 650 C. (orig.)

  16. Thermodynamic stability of in situ W–ZrC and W–Zr(CN) composites

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae-Hee [Korea Aerospace Research Institute, Daejeon 305-806 (Korea, Republic of); Zhe, Gao [Saint-Gobain Research Shanghai Co., Ltd, Wenjing-road, Minhang-district, Shanghai 200245 (China); Lim, Jaehyuk [Samsung Electronics, Yongin 446-811 (Korea, Republic of); Park, Choongkwon [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Kang, Shinhoo, E-mail: shinkang@snu.ac.kr [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

    2015-10-25

    Powders of W–ZrC and W–Zr(CN) were carbothermally synthesized in situ from milled mixtures of graphite, WO{sub 3} and ZrO{sub 2}. The thermal stability of Zr(CN) in a W matrix was simulated and compared with that of ZrC in W in terms of free energy change and carbide coarsening. Carbon and nitrogen had high mutual affinity in Zr(CN) of B1 crystal structure, which led their activity curves to exhibit strong negative deviation from ideal mixing behavior. Zr(CN) was more stable than ZrC up to 2075 K; however, a microstructural study showed that it became less stable than ZrC at around 1975 K. This result is attributed to the decreasing thermodynamic stability of ZrN with increasing temperature. Other transition metal carbonitrides containing group 4–6 elements are expected to show similar coarsening behaviors at high temperatures. - Highlights: • The Zr(CN) phase formed due to the high affinity between C and N in ZrC. • A complete reversal of the slope is found in the formation energy curves. • The growth of the carbonitride is due to the nitrogen, reducing the stability. • Solid solutions containing group 4 elements would show similar growth behavior.

  17. Influence of non-metallic second phases on fatigue behaviour of high strength steel components; Efecto de segundas fases no metalicas sobre el comportamiento a fatiga de componentes de acero con elevadas solicitaciones

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, L.; Elvira, R.; Garcia de Andoin, A.; Pizarro, R.; Bertrand, C.

    2005-07-01

    To assess the real effect of the inclusion type on fatigue life of ultra clean high strength steels mechanical components made of 100Cr6 steel were fatigue tested and fracture surfaces analysed to determine the origin of fatigue cracks.Two heats proceedings from different steelmaking routes were taken for the tests. The material were forged into ring shape components which were fatigue tested under compression-compression loads. Failures were analysed by SFEM (Scanning field Emission Microscopy), proving that most of failures at high loads were originated by manganese sulphides of small size (10-70 micros), while less than 40% of all fatigue cracks due to inclusions were caused by titanium carbonitrides and hard oxides. It has been demonstrated that once number and size of hard inclusions have been reduced, the hazardous effect of oxides and carbonitrides on the fatigue life decreases also. However, softer inclusions as manganese sulphides, currently considered as less hazardous, play a more relevant role as direct cause of fatigue failure and they should be taken into account in a deeper way in order to balance both machinability and fatigue life requirements in high strength steel components. (Author) 11 refs.

  18. Production and Machining of Thin Wall Gray and Ductile Cast Iron

    Energy Technology Data Exchange (ETDEWEB)

    Fleischman, E.H. (INEEL POC); Li, H.; Griffin, R.; Bates, C.E.; Eleftheriou, E.

    2000-11-03

    The University of Alabama at Birmingham, in cooperation with the American Foundry Society, companies across North America, with support from the U.S. Department of Energy, is conducting a project to develop an understanding of the factors that control the machinability of cast gray and ductile iron. Differences of as much as 500% have been found in machinability have been observed at the same strength. The most machinable irons were those with a high cell counts and few carbonitride inclusions. Additions of tin and copper can be added to both gray and ductile iron to stabilize the pearlite, but excessive additions (above those required to produce the desired pearlite content) degrade the machinability.

  19. 镀合金

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    [ 篇名 ] Influence of WC addition an microstructures of laser-melted Ni-based alloy coating, [ 篇名 ] Microstructure and dry sliding wear behavior of laser clad Ni-based alloy coating with the addition of SiC, [ 篇名 ] Preparation of Advanced Lithium Secondary Batteries with Tin-Iron Alloy Plating Anodes and Their Charge-Discharge Behaviors, [篇名] SnAg-alloy coating for connectors and soldering applications, [篇名] Structure and properties of wear-resistant titanium carbonitride-based coatings, [篇名] The analysis of the deposition mechanism of Zn/Ni alloy plating using an EQCM, [ 篇名 ]The effect of heat treatment on wear resistance of parts having hard-alloy coating.

  20. Q345E热轧中厚板探伤不合格原因分析%Unqualified Reason Analysis on Non-destructure Testing of Q345E Hot Rolling Medium Plate

    Institute of Scientific and Technical Information of China (English)

    李智丽

    2011-01-01

    通过低倍检验、金相检验和断口分析等方法分析了Q345E热轧中厚板探伤不合格的原因.结果表明:探伤不合格的原因是在热轧板中心区域偏析带存在硫化锰和碳氮化铌夹杂物,并通过控制和调整工艺解决了该问题.%The unqualified reason of Q345E hot rolling medium plate by ultrasonic inspection had been analyzed by means of macroscopic examination, metallographic examination, fracture analysis and so on. The results showed that the reason was the segregation zone and the inclusions including manganese sulfide and niobium carbonitride which congregated in the central part of the medium plate. And the problem was solved by adjusting the process.

  1. Nitrocarburizing treatments using flowing afterglow processes

    Science.gov (United States)

    Jaoul, C.; Belmonte, T.; Czerwiec, T.; David, N.

    2006-09-01

    Nitrocarburizing of pure iron samples is achieved at 853 K and is easily controlled by introducing C 3H 8 in the afterglow of a flowing microwave Ar-N 2-H 2 plasma. The carbon uptake in the solid is actually possible with methane but strongly limited. The use of propane enhances the carbon flux and the ɛ/α configuration is synthesized for the first time by this kind of process. For this stack, diffusion paths in the ternary system determined from chemical analyses by secondary neutral mass spectrometry reproduce satisfactorily X-ray diffraction results which only reveal, as optical micrographs, ɛ and α phases. Propane offers an accurate control of the nitrocarburizing conditions. As an example, a modulation of N and C contents in iron could be achieved to create new carbonitride multilayers.

  2. Nitrocarburizing treatments using flowing afterglow processes

    Energy Technology Data Exchange (ETDEWEB)

    Jaoul, C. [Laboratoire de Science et Genie des Surfaces (UMR CNRS 7570), Ecole des Mines, Parc de Saurupt, 54042 Nancy Cedex (France); Belmonte, T. [Laboratoire de Science et Genie des Surfaces (UMR CNRS 7570), Ecole des Mines, Parc de Saurupt, 54042 Nancy Cedex (France)]. E-mail: Thierry.Belmonte@mines.inpl-nancy.fr; Czerwiec, T. [Laboratoire de Science et Genie des Surfaces (UMR CNRS 7570), Ecole des Mines, Parc de Saurupt, 54042 Nancy Cedex (France); David, N. [Laboratoire de Chimie du Solide Mineral, Universite Henri Poincare Nancy-I, Vandoeuvre-Les-Nancy (France)

    2006-09-30

    Nitrocarburizing of pure iron samples is achieved at 853 K and is easily controlled by introducing C{sub 3}H{sub 8} in the afterglow of a flowing microwave Ar-N{sub 2}-H{sub 2} plasma. The carbon uptake in the solid is actually possible with methane but strongly limited. The use of propane enhances the carbon flux and the {epsilon}/{alpha} configuration is synthesized for the first time by this kind of process. For this stack, diffusion paths in the ternary system determined from chemical analyses by secondary neutral mass spectrometry reproduce satisfactorily X-ray diffraction results which only reveal, as optical micrographs, {epsilon} and {alpha} phases. Propane offers an accurate control of the nitrocarburizing conditions. As an example, a modulation of N and C contents in iron could be achieved to create new carbonitride multilayers.

  3. Investigation of the chemical interaction in the TiC-Si3N4 system

    Directory of Open Access Journals (Sweden)

    V.A. Izhevskyi

    1999-10-01

    Full Text Available Chemical interaction in the TiCSi3N4 system was investigated. Thermodynamic calculations and kinetic analysis were carried out for a number of powder mixtures with various TiC:Si3N4 molar ratios in the temperature range 1300-1750 °C. Stability regions of the TiC-Si3N4 composites were defined. It was shown that the main reaction products are silicon carbide and titanium carbonitride. The overall chemical interaction is described in terms of chemical reaction between titanium carbide and silicon nitride, and the diffusion of carbon and nitrogen through the coherent reaction products layer after completion of the initial direct interaction of the components.

  4. XPS, XRD and laser raman analysis of surface modified of 6150 steel substrates for the deposition of thick and adherent diamond-like carbon coatings

    Directory of Open Access Journals (Sweden)

    William de Melo Silva

    2013-06-01

    Full Text Available Although the 6150 steel has an excellent fatigue and impact resistance, it is unsuitable to operate it when the corrosion is a limited factor. We propose here a sequence of steel pre-treatment by carburizing, carbonitriding and nitriding in order to improve the poor adhesion between Diamond Like-Carbon coatings on steel. This sequence is our attempt to reduce the difference between the coefficients of thermal expansion of steel and DLC through the graded interface. This work demonstrates the quantitative analysis of the molecules present at surface using X-ray photoelectron spectroscopy. The crystallographic structures are investigated by X-ray diffraction which shows the formation of carbides and nitride phases. Raman spectroscopy reveals the carburizing surface characteristics where DLC coating is nucleated and grown at the substrate. At the end of the analysis it is possible to verify which molecules and phases are formed on the steel surface interface after each step of pre-treatment.

  5. Application of electrochemical plasma techniques in surface engineering of iron based structural materials

    International Nuclear Information System (INIS)

    The surface of austenitic stainless steels 304L and 316L was modified by various complex surface treatments: - plasma electrolytic carbo-nitriding by means of Plasma electrolytic saturation (PES); the saturation of cathodic surfaces with C, N was performed using suitable electrolytes (aqueous solutions of inorganic acids, appropriate salts containing the desired elements and certain organic compounds); -electrodeposition of Al from ChCl based Ionic Liquid. The coatings obtained in various experimental conditions have been investigated by means of electron spectroscopy, scanning electron microscopy, energy dispersion x-ray spectrometry, electrochemical techniques, and the properties of the thin films have been correlated with the microstructure and the composition of the surface layers which are strongly dependents of the different regimes of diffusion treatments. The preliminary results on Electrochemical Plasma Technology (EPT) treatments demonstrate that we can select the processing parameters for essential improvement of corrosion behaviour in some aggressive medium and high values of microhardness. (authors)

  6. XPS, XRD and laser Raman analysis of surface modified of 6150 steel substrates for the deposition of thick and adherent diamond-like carbon coatings

    Energy Technology Data Exchange (ETDEWEB)

    Silva, William de Melo; Carneiro, Jose Rubens Goncalves, E-mail: williammelosilva@gmail.com [Pontificia Universidade Catolica de Minas Gerais (PUC-MG), Belo Horizonte (Brazil). Dept. de Engenharia Mecanica; Trava-Airoldi, Vladimir Jesus [Associate Laboratory of Sensors and Materials, National Institute for Space Research, Sao Jose dos Campos, SP (Brazil)

    2013-11-01

    Although the 6150 steel has an excellent fatigue and impact resistance, it is unsuitable to operate it when the corrosion is a limited factor. We propose here a sequence of steel pre-treatment by carburizing, carbonitriding and nitriding in order to improve the poor adhesion between Diamond Like-Carbon coatings on steel. This sequence is our attempt to reduce the difference between the coefficients of thermal expansion of steel and DLC through the graded interface. This work demonstrates the quantitative analysis of the molecules present at surface using X-ray photoelectron spectroscopy. The crystallographic structures are investigated by X-ray diffraction which shows the formation of carbides and nitride phases. Raman spectroscopy reveals the carburizing surface characteristics where DLC coating is nucleated and grown at the substrate. At the end of the analysis it is possible to verify which molecules and phases are formed on the steel surface interface after each step of pre-treatment. (author)

  7. New Developments in Thermo-Chemical Diffusion Processes

    Institute of Scientific and Technical Information of China (English)

    Bernd Edenhofer

    2004-01-01

    Thermo-chemical diffusion processes like carburising, nitriding and boronizing play an important part in modern manufacturing technologies. They exist in many varieties depending on the type of diffusing element used and the respective process procedure. The most important industrial heat treatment process is case-hardening, which consists of thermochemical diffusion process carburising or its variation carbonitriding, followed by a subsequent quench. The latest developments of using different gaseous carburising agents and increasing the carburising temperature are one main area of this paper. The other area is the evolvement of nitriding and especially the ferritic nitrocarburising process by improved process control and newly developed process variations using carbon, nitrogen and oxygen as diffusing elements in various process steps. Also boronizing and special thermo-chemical processes for stainless steels are discussed.

  8. Thermal analysis study of polymer-to-ceramic conversion of organosilicon precursors

    Directory of Open Access Journals (Sweden)

    Galusek D.

    2008-01-01

    Full Text Available The organosilicon precursors attract significant attention as substances, which upon heating in inert or reactive atmosphere convert directly to oxide or non-oxide ceramics, like nitrides, carbides, carbonitrides, boroncarbonitrides, oxycarbides, alons, etc. In characterisation, and in study of conversion of these polymers to ceramics thermal analysis plays an important role. The degree of cross-linking of the polymer vital for achievement of high ceramic yield is estimated with the use of thermal mechanical analysis (TMA. Decomposition of polymers and their conversion to ceramics is studied by the combination of differential thermal analysis (DTA, differential scanning calorimetry (DSC thermogravimetry(TG, and mass spectrometry (MS. The use of these methods in study of the polymer-to-ceramic conversion is illustrated by case studies of a commercially available poly(allylcarbosilane as the precursor of SiC, and a poly(hydridomethylsilazane as the precursor of SiCN.

  9. Effect of zirconium addition on the austenite grain coarsening behavior and mechanical properties of 900 Mpa low carbon bainite steel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The ultra-free bainitic microstructure of a 900 MPa low carbon bainitic Cu-Ni-Mo-B steel was obtained by a newly developed relaxation precipitation control (RPC) phase transformation processing.In a pan-cake like prior-anstenite grain,the microstructure consisted of lath bainite,a little of abnormal granular bainite,and acicular ferrite.The effect of zirconium carbonitrides on the austenite grain coarsening behavior was studied by transmission electron microscopy (TEM).The results show that,the lath is narrower with increasing cooling rate.The ratio of all kinds of bainitic microstructure is proper with the intermediate cooling rate;and Zr-containing precipitates distribute uniformly,which restrains austenite grain growing in heat-affected welding zone.

  10. Vibrational and mechanical properties of single layer MXene structures: a first-principles investigation

    Science.gov (United States)

    Yorulmaz, Uğur; Özden, Ayberk; Perkgöz, Nihan K.; Ay, Feridun; Sevik, Cem

    2016-08-01

    MXenes, carbides, nitrides and carbonitrides of early transition metals are the new members of two dimensional materials family given with a formula of {{{M}}}n+1 X n . Recent advances in chemical exfoliation and CVD growth of these crystals together with their promising performance in electrochemical energy storage systems have triggered the interest in these two dimensional structures. In this work, we employ first principles calculations for n = 1 structures of Sc, Ti, Zr, Mo and Hf pristine MXenes and their fully surface terminated forms with F and O. We systematically investigated the dynamical and mechanical stability of both pristine and fully terminated MXene structures to determine the possible MXene candidates for experimental realization. In conjunction with an extensive stability analysis, we report Raman and infrared active mode frequencies for the first time, providing indispensable information for the experimental elaboration of MXene field. After determining dynamically stable MXenes, we provide their phonon dispersion relations, electronic and mechanical properties.

  11. Nitrogen Contents on Tribological Properties of Magnetron Sputtered SiCN Coatings

    Institute of Scientific and Technical Information of China (English)

    TIETUN SUN; Y.Q. FU; J. WEI; H. J. DU

    2004-01-01

    Silicon carbonitride (SiCN) coatings were deposited on silicon and tungsten carbide substrates by co-sputtering silicon and carbon in argon and nitrogen mixture atmosphere using magnetron-sputtering system. The effect of the N2concentration, RF substrate bias voltage and target current on film deposition rate, roughness, adhesion, mechanical and tribological properties of coatings were investigated. The deposition rate was found to increase with the increasing nitrogen concentration. X-ray photoelectron spectroscopy analysis showed that high nitrogen concentration in the nitrogen-argon gas mixture enhanced the incorporation of C and N but reduced the incorporation of Si. SiCN coatings have good tribological properties at a N2 concentration of approximately 60%.

  12. Enhancement of strength properties of hot rolled 10KHSND steel

    International Nuclear Information System (INIS)

    To find out the reasons of low hot rolling yield for 10KhSND steel sheets in mechanical properties, titanium effect in the range of 0.008-0.03% concentrations is studied. It is established that the titanium content in a solid solution is conserved within 0.003-0.005%, the rest of titanium is bound to carbonitrides Ti(C, N). It is shown that alloys with 0.025-0.03% titanium content possess the increased values of ultimate and yield strength the necessary level of impact strength and good wealdability. The good steel yield, when the titanium content is sustained at the given level, increases from 40 to 85%

  13. Studying factors responsible for increasing ductility of the ferritic steel 08Kh18T1 in the course of repeated hot rolling

    International Nuclear Information System (INIS)

    Two possible reasons for embrittlement of ferritic steel 08Kh18T1 after high temperature (T ≥ 1100 deg C) rolling are considered: an α-phase grain growth and precipitation of titanium carbonitride fine crystal spreading along subboundaries under conditions of dynamic polygonization. Repeat rolling at more low temperatures ranging from 800 to 1000 deg C results in formation of other substructure that is of lath subgrain type. In the case of high deformation degree the accumulation of distortions over a large face of subcrystals results in stratification in a plane perpendicular to a fracture surface, and in so doing it changes the stressed state on main crack propagation so that the thickness (radius) of plastic zone increases and the temperature of ductile-brittle transition decreases

  14. Influence of carbon and nitrogen on corrosion resistance of high purity Fe-50mass% Cr alloys

    International Nuclear Information System (INIS)

    High purity Fe-50mass%Cr alloys containing (C+N) in the range of 30 to 500 mass ppm were prepared and their corrosion resistance was investigated. Pitting potential in a 3.5mass%NaCl solution at 343K rose with reducing (C+N) content. Alloys containing (C+N) at less than 100 mass ppm did not sustain pitting corrosion. However, alloys containing 500 mass ppm (C+N) corroded severely in 6%FeCl3+1/20N HCl solutions. Heat treatment at 923K was recognized as influencing corrosion resistance due to precipitation of carbonitrides only in the case of the alloy containing 500 mass ppm (C+N). (orig.)

  15. Cation intercalation and high volumetric capacitance of two-dimensional titanium carbide.

    Science.gov (United States)

    Lukatskaya, Maria R; Mashtalir, Olha; Ren, Chang E; Dall'Agnese, Yohan; Rozier, Patrick; Taberna, Pierre Louis; Naguib, Michael; Simon, Patrice; Barsoum, Michel W; Gogotsi, Yury

    2013-09-27

    The intercalation of ions into layered compounds has long been exploited in energy storage devices such as batteries and electrochemical capacitors. However, few host materials are known for ions much larger than lithium. We demonstrate the spontaneous intercalation of cations from aqueous salt solutions between two-dimensional (2D) Ti3C2 MXene layers. MXenes combine 2D conductive carbide layers with a hydrophilic, primarily hydroxyl-terminated surface. A variety of cations, including Na(+), K(+), NH4(+), Mg(2+), and Al(3+), can also be intercalated electrochemically, offering capacitance in excess of 300 farads per cubic centimeter (much higher than that of porous carbons). This study provides a basis for exploring a large family of 2D carbides and carbonitrides in electrochemical energy storage applications using single- and multivalent ions.

  16. Correlation of Fractographic Features with Mechanical Properties in Systematically Varied Microstructures of Cu-Strengthened High-Strength Low-Alloy Steel

    Science.gov (United States)

    Das, Arpan; Das, Swapan Kumar; Tarafder, Soumitra

    2009-12-01

    Fracture is often the culmination of continued deformation. Therefore, it is probable that a fracture surface may contain an imprint of the deformation processes that were operative. In this study, the deformation behavior of copper-strengthened high-strength low-alloy (HSLA) 100 steel has been investigated. Systematic variation of the microstructure has been introduced in the steel through various aging treatments. Due to aging, the coherency, size, shape, and distribution of the copper precipitates were changed, while those of inclusions, carbides, and carbonitrides were kept unaltered. Two-dimensional dimple morphologies, quantified from tensile fracture surfaces, have been correlated to the nature of the variation of the deformation parameters with aging treatment.

  17. Nanosized Si3N4/SiC-powders by polysilazane/polycarbosilane-pyrolysis

    International Nuclear Information System (INIS)

    The preparation of the nanosized powders has been realized by gasphase-pyrolysis of volatile precursor compounds at temperatures between 600 and 1200 C. Silicon carbonitride powders have been created from polysilazanes, which have been synthesized by ammonolysis of alkylchlorosilanes. Silicon carbide powders have been prepared from 1,1,3,3-tetramethyl-1,3-disilacyclobutane, gained by the dechlorination- and coupling reaction of chloromethyldimethylchlorosilane with magnesium. The ball-like powder particles have a diameter between 100 and 500 nm and a surface of 10 to 50 m2/g. They are X-ray amorphous and can be crystallized upper 1400 C to α-Si3N4 and β-SiC respectively. (orig.)

  18. Nitrogen Contents on Tribological Properties of Magnetron Sputtered SiCN Coatings

    Institute of Scientific and Technical Information of China (English)

    TIETUNSUN; Y.Q.FU; J.WEI; H.J.DU

    2004-01-01

    Silicon carbonitride (SiCN) coatings were deposited on silicon and tungsten carbide substrates by co-sputtering silicon and carbon in argon and nitrogen mixture atmosphere using magnetron-sputtering system. The effect of the N2 concentration, RF substrate bias voltage and target current on film deposition rate, roughness, adhesion, mechanical and tribological properties of coatings were investigated. The deposition rate was found to increase with the increasing nitrogen concentration. X-ray photoelectron spectroscopy analysis showed that high nitrogen concentration in the nitrogen-argon gas mixture enhanced the incorporation of C and N but reduced the incorporation of Si. SiCN coatings have good tribological properties at a N2 concentration of approximately 60%.

  19. Effect of Heat Treatment on the Microstructure and Hardness of 17Cr-0.17N-0.43C-1.7 Mo Martensitic Stainless Steel

    Science.gov (United States)

    Krishna, S. Chenna; Gangwar, Narendra Kumar; Jha, Abhay K.; Pant, Bhanu; George, Koshy M.

    2015-04-01

    The microstructure and hardness of a nitrogen-containing martensitic stainless steel were investigated as a function of heat treatment using optical microscopy, electron microscopy, amount of retained austenite, and hardness measurement. The steel was subjected to three heat treatments: hardening, cryo treatment, and tempering. The hardness of the steel in different heat-treated conditions ranged within 446-620 HV. The constituents of microstructure in hardened condition were lath martensite, retained austenite, M23C6, M7C3, MC carbides, and M(C,N) carbonitrides. Upon tempering at 500 °C, two new phases have precipitated: fine spherical Mo2C carbides and needle-shaped Cr2N particles.

  20. Methods for manufacturing porous nuclear fuel elements for high-temperature gas-cooled nuclear reactors

    Science.gov (United States)

    Youchison, Dennis L.; Williams, Brian E.; Benander, Robert E.

    2010-02-23

    Methods for manufacturing porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's). Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, a thin coating of nuclear fuel may be deposited inside of a highly porous skeletal structure made, for example, of reticulated vitreous carbon foam.

  1. Phase Transformation Behavior of Porous TiNi Alloys Produced by Powder Metallurgy Using Magnesium as a Space Holder

    Science.gov (United States)

    Aydoğmuş, Tarik; Bor, Elif Tarhan; Bor, Şakir

    2011-09-01

    Porous TiNi alloys with porosities in the range of 51 to 73 pct were prepared successfully applying a new powder metallurgy fabrication route in which magnesium was used as a space holder, resulting in either single austenite phase or a mixture of austenite and martensite phases dictated by the composition of the starting powders, but entirely free from secondary brittle intermetallics, oxides, nitrides, and carbonitrides. Since transformation temperatures are very sensitive to composition, deformation, and oxidation, for the first time, transformation temperatures of porous TiNi alloys were investigated using chemically homogeneous specimens in as-sintered and aged conditions eliminating secondary phase, contamination, and deformation effects. It was found that the porosity content of the foams has no influence on the phase transformation temperatures both in as-sintered and aged conditions, while deformation, oxidation, and aging treatment are severely influential.

  2. The effect of tempering temperature on the features of phase transformations in the ferritic–martensitic steel EK-181

    Energy Technology Data Exchange (ETDEWEB)

    Polekhina, N.A. [Institute of Strength Physics and Materials Science SB RAS, 2/1 Akademichesky av., Tomsk 634055 (Russian Federation); Litovchenko, I.Yu.; Tyumentsev, A.N. [Institute of Strength Physics and Materials Science SB RAS, 2/1 Akademichesky av., Tomsk 634055 (Russian Federation); Tomsk State University, 36 Lenin av., Tomsk 634050 (Russian Federation); V.D. Kuznetsov Siberian Physical-Technical Institute at Tomsk State University, 1 Novosobornaya Sq., Tomsk 634050 (Russian Federation); Astafurova, E.G. [Institute of Strength Physics and Materials Science SB RAS, 2/1 Akademichesky av., Tomsk 634055 (Russian Federation); Chernov, V.M.; Leontyeva-Smirnova, M.V. [JSC “A.A. Bochvar High-Technology Research Institute of Inorganic Materials”, 5 Rogov st., Moscow 123060 (Russian Federation)

    2014-12-15

    Using the methods of dilatometry and differential scanning calorimetry, critical points of phase transformations in the low-activation ferritic–martensitic steel EK-181 (RUSFER-EK-181) are identified. The characteristic temperature intervals of precipitation of carbide phases are revealed. It is shown that particles of the metastable carbide M{sub 3}C are formed within the temperature range (500–600) °C. Formation of the stable phases M{sub 23}S{sub 6} and V(CN) begins at the temperatures higher than T = 650 °S. An important feature of microstructure after tempering at T = 720 °S is high density of nanoparticles (⩽10 nm) of vanadium carbonitride V(CN)

  3. Evolution of dislocation density, size of subgrains and MX-type precipitates in a P91 steel during creep and during thermal ageing at 600 deg. C for more than 100,000 h

    International Nuclear Information System (INIS)

    There are rather few quantitative data on the microstructure of the 9-12%Cr heat resistant steels after long-term creep. This paper presents results of the quantitative measurement of the size of MX precipitates, subgrain size and dislocation density in a P91 steel that had been creep tested for 113,431 h at 600 deg. C. The same measurements were conducted in the same P91 steel in the as received conditions. Transmission electron microscopy investigations were conducted using thin foils and revealed a decrease in dislocation density and an increase in subgrain size after creep exposure. MX carbonitrides are very stable during thermal and creep exposure of P91 steel at 600 deg. C up to 113,431 h. Electron backscatter diffraction (EBSD) investigations also revealed a significant change in the substructure of the steel after creep exposure.

  4. Effects of Electric Discharge Plasma Treatment on the Thermal Conductivity of Polymer-Metal Nitride/Carbide Composites

    Science.gov (United States)

    Parali, Levent; Kurbanov, Mirza A.; Bayramov, Azad A.; Tatardar, Farida N.; Sultanakhmedova, Ramazanova I.; Xanlar, Huseynova Gulnara

    2015-11-01

    High-density polymer composites with semiconductor or dielectric fillers such as aluminum nitride (AIN), aluminum oxide (Al2O3), titanium carbide (TiC), titanium nitride (TiN), boron nitride (BN), silicon nitride (Si3N4), and titanium carbonitride (TiCN) were prepared by the hot pressing method. Each powder phase of the composites was exposed to an electric discharge plasma process before composite formation. The effects of the electric discharge plasma process and the filler content (volume fraction) on the thermal conductivity, volt-ampere characteristics, thermally stimulated depolarization current, as well as electrical and mechanical strength were investigated. The results of the study indicate that, with increasing filler volume fraction, the thermal conductivity of the samples also increased. Furthermore, the thermal conductivity, and electrophysical and mechanical properties of the high-density polyethylene + 70% BN composite modified using the electric discharge plasma showed improvement when compared with that without electric discharge plasma treatment.

  5. Porous nuclear fuel element with internal skeleton for high-temperature gas-cooled nuclear reactors

    Science.gov (United States)

    Youchison, Dennis L.; Williams, Brian E.; Benander, Robert E.

    2013-09-03

    Porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's), and to processes for fabricating them. Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, the nuclear fuel may be deposited inside of a highly porous skeletal structure made of, for example, reticulated vitreous carbon foam.

  6. Porous nuclear fuel element for high-temperature gas-cooled nuclear reactors

    Science.gov (United States)

    Youchison, Dennis L.; Williams, Brian E.; Benander, Robert E.

    2011-03-01

    Porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's), and to processes for fabricating them. Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, the nuclear fuel may be deposited inside of a highly porous skeletal structure made of, for example, reticulated vitreous carbon foam.

  7. Vibrational and mechanical properties of single layer MXene structures: a first-principles investigation.

    Science.gov (United States)

    Yorulmaz, Uğur; Özden, Ayberk; Perkgöz, Nihan K; Ay, Feridun; Sevik, Cem

    2016-08-19

    MXenes, carbides, nitrides and carbonitrides of early transition metals are the new members of two dimensional materials family given with a formula of [Formula: see text] X n . Recent advances in chemical exfoliation and CVD growth of these crystals together with their promising performance in electrochemical energy storage systems have triggered the interest in these two dimensional structures. In this work, we employ first principles calculations for n = 1 structures of Sc, Ti, Zr, Mo and Hf pristine MXenes and their fully surface terminated forms with F and O. We systematically investigated the dynamical and mechanical stability of both pristine and fully terminated MXene structures to determine the possible MXene candidates for experimental realization. In conjunction with an extensive stability analysis, we report Raman and infrared active mode frequencies for the first time, providing indispensable information for the experimental elaboration of MXene field. After determining dynamically stable MXenes, we provide their phonon dispersion relations, electronic and mechanical properties. PMID:27377143

  8. Structure and mechanical properties of corrosion-resistant high-nitrogen 04Kh22AG15N8M2F and 05Kh19AG10N7MFB steels after hot deformation

    Science.gov (United States)

    Blinov, E. V.; Khadyev, M. S.

    2012-03-01

    The structure and mechanical properties of corrosion-resistant high-nitrogen austenitic 04Kh22AG15N8M2F and 05Kh19AG10N7MFB steels are studied after hot rolling at 950 and 1100°C. The following specific features of the structure of hot-rolled 04Kh22AG15N8M2F steel are revealed: the presence of coarse grain-boundary precipitates of the molybdenum-rich σ phase and its nonuniform distribution over the volume of austenite grains. The 05Kh19AG10N7MFB steel hot rolled at 950°C contains ultrafine carbonitrides particles and has the best combination of a high strength and a sufficient elasticity and impact toughness. The structures of the hot-rolled steels have no ferrite, martensite, and traces of recrystallized austenite grains.

  9. Microstructural and weldability evaluation of 310TaN

    Energy Technology Data Exchange (ETDEWEB)

    Lundin, C.D.; Qiao, C.Y.P. [Univ. of Tennessee, Knoxville, TN (United States); Swindeman, R.W. [Oak Ridge National Lab., TN (United States)

    1996-08-01

    Excellent weldability and good microstructural stability of 310TaN, in terms of the formation and growth of secondary phases at elevated temperature, was revealed in this investigation. The interganular stress corrosion resistance of 310TaN is superior to modified 800H and 310HCbN evaluated previously due to the fact that TaC, TaN and Ta(C,N) particles are more stable compared to Nb-rich or Ti-rich carbides, nitrides and carbonitrides presented in the other advanced alloys. Using resistance spot welding technique for which extremely fast cooling is a characteristic, it was found that a very minor amount of gain boundary liquation takes place during welding thermal cycling. The limited grain boundary liquation is of the eutectic type i.e., a low tendency to weld HAZ hot cracking.

  10. Microstructure and properties of dual-phase steels containing fine precipitates

    Energy Technology Data Exchange (ETDEWEB)

    Gau, J.S.; Koo, J.Y.; Nakagawa, A.; Thomas, G.

    1981-07-01

    Very fine particles (carbides or carbonitrides) of the order of 20 A were extensively examined in the ferrite regions of dual-phase steels subjected to intercritical annealing followed by fast quenching to room temperature. These particles are probably formed during quenching after intercritical annealing. The driving force for the precipitation reaction may arise from the supersaturation of carbon (or nitrogen) in the ferrite phase. These precipitates in certain alloy compositions cause a deviation from the generally observed two phase mixture rule in that the strength of the dual-phase steels having a higher volume fraction of martensite is lower than that having a lower volume fraction of martensite. Thus, the influence of such precipitates must be considered in the structure-property relations of dual-phase steels when fast quenching is employed after intercritical annealing.

  11. Generic trend of work functions in transition-metal carbides and nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Yoshitake, Michiko, E-mail: yoshitake.michiko@nims.go.jp [MANA Nanoelectronics Materials Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0003 (Japan)

    2014-11-15

    Transition-metal carbides and nitrides (TMCs and TMNs) are promising electrode materials for various electronic devices such as metal-oxide-semiconductor field-effect transistors and metal-insulator-metal capacitors. In this paper, the work functions of TMCs and TMNs are discussed systematically. Based upon the origin of the work function, the effect upon transition metal species by different periodic table groups is explained, carbides are compared with nitrides for the same transition metal, and the effect of carbon or nitrogen vacancies is discussed. In addition, a method to estimate the generic trend of the work function is proposed for TMC{sub x}, TMN{sub x}, TMC{sub 1−y}N{sub y} (transition metal carbonitrides), and TM{sub 1−z}TM′{sub z}C (alloy carbides)

  12. Improved Creep Behavior of a High Nitrogen Nb-Stabilized 15Cr-15Ni Austenitic Stainless Steel Strengthened by Multiple Nanoprecipitates

    Science.gov (United States)

    Ha, Vu The; Jung, Woo Sang; Suh, Jin Yoo

    2011-11-01

    Austenitic stainless steels are expected to be a major material for boiler tubes and steam turbines in future ultra-supercritical (USC) fossil power plants. It is of great interest to maximize the creep strength of the materials without increasing the cost. Precipitation strengthening was found to be the best and cheapest way for increasing the creep strength of such steels. This study is concerned with improving creep properties of a high nitrogen Nb-stabilized 15Cr-15Ni austenitic alloy through introducing a high number of nanosized particles into the austenitic matrix. The addition of around 4 wt pct Mn and 0.236 wt pct N into the 15Cr-15Ni-0.46Si-0.7Nb-1.25Mo-3Cu-Al-B-C matrix in combination with a special multicycled aging-quenching heat treatment resulted in the fine dispersion of abundant quantities of thermally stable (Nb,Cr,Fe)(C,N) precipitates with sizes of 10 to 20 nm. Apart from the carbonitrides, it was found that a high number of coherent copper precipitates with size 40 to 60 nm exist in the microstructure. Results of creep tests at 973 K and 1023 K (700 °C and 750 °C) showed that the creep properties of the investigated steel are superior compared to that of the commercial NF709 alloy. The improved creep properties are attributed to the improved morphology and thermal stability of the carbonitrides as well as to the presence of the coherent copper precipitates inside the austenitic matrix.

  13. Effect of nitrogen microalloying on structure and properties of quenched martensitic steels

    International Nuclear Information System (INIS)

    Highlights: ► High temperature thermomechanical treatment with various hot rolling schemes is effective for realization of the high-strength state of structural martensitic steels after low-temperature tempering. ► Hot deformation by radial-shear rolling results in higher plasticity at the same strength level in comparison with longitudinal rolling. ► Radial-shear rolling allows obtaining polygonized substructure, peculiar “twisted” grain structure and texture favorable for strength and plasticity in an axial direction. ► The UTS level of the studied nitrogen-containing steels is 300–500 MPa higher than this for nitrogen-free analogs. -- Abstract: Structure, phase transformation features and the strengthening of nitrogen-microalloyed structural C(0.2–0.5)CrNiMoNV steels from alloying and high-temperature thermomechanical treatment (HTMT) by various hot deformation routes have been investigated using X-ray diffraction analysis, optical microscopy, hardness measurements and tensile testing. The nitrogen alloying retards recrystallization processes during hot deformation widens ε-carbonitride region and allows more effective thermomechanical treatment application for realization of high-strength state after low temperature tempering of quenched martensitic steels. Heat and thermomechanical treatment regimes providing increase of deformation and fracture resistance after quenching and tempering were determined. A complete dissolution of special carbonitrides during HTMT and following low-temperature tempering provide high strength level (by 300–500 MPa higher than for nitrogen-free analogs) combined with sufficient ductility and fracture toughness. HTMT comprising hot deformation by the radial-shear rolling with the same strain and deformation temperature as under longitudinal rolling, allows obtaining polygonized substructure, peculiar “twisted” in a definite direction grain structure and texture favorable for strength and plasticity

  14. Microstructure and properties of 13Cr5Ni1Mo0.025Nb0.09V0.06N super martensitic stainless steel

    International Nuclear Information System (INIS)

    Highlights: ► Characterization of the microstructures of a commercial martenistic stainless steel. ► Excess N content causes the occurrence of coarse carbo-nitride and Cr2N. ► Correlation of microstructures with mechanical and corrosion properties. ► The poor pitting resistance is due to Cr rich precipitates. - Abstract: The morphological microstructure, the density and dispersion of high angle boundaries, morphology and micro chemical composition of precipitates and the volume fraction of retained austenite of a commercial super martensitic stainless steel (SMSS) normalized and tempered at various temperatures were characterized by optical microscope, scanning electron microscope (SEM), electron backscattered diffraction (EBSD), transmission electron microscope (TEM) and X-ray diffraction (XRD) in the light of equilibrium phase diagram of the alloy calculated using Thermo-Calc software. The mechanical properties and pitting corrosion resistance were determined to correlate with microstructures. Two kinds of morphology of precipitate were observed in tempered commercial super martensitic stainless. Besides the globular Nb and V rich carbo-nitride precipitates, rod-like Cr rich nitrides were formed due to excess N content. While high density of high angle boundaries and precipitates contribute to strength properties, the dislocation softening of the matrix and retained austenite from tempering restore the ductility and impact toughness properties. The poor resistance to pitting corrosion is attributed to the occurrence of Cr rich precipitates. It is demonstrated that by lowering the nitrogen content and adding niobium, the Cr rich precipitates can be suppressed and the mechanical properties and resistance to pitting corrosion can be significantly improved.

  15. Performance Evaluation of Advanced Ferritic/Martensitic Steels for a SFR Fuel Cladding

    International Nuclear Information System (INIS)

    High-chromium(9-12 wt.%) ferritic/martensitic steels are currently being considered as candidate materials for cladding and duct applications in a Gen-IV SFR (sodium-cooled fast reactor) nuclear system because of their higher thermal conductivities and lower expansion coefficients as well as excellent irradiation resistance to void swelling when compared to austenite stainless steels. Since the operation condition in the design of Gen-IV SFR would be envisioned to be harsh from the viewpoints of temperature (≥600 .deg. C) and irradiation dose (≥200 dpa), the primary emphasis is on the fuel cladding materials, i.e. high-Cr ferritic/martensitic steels. The ferritic/martensitic steels for the fuel cladding are commonly used in a 'normalized and tempered' condition. This heat treatment involves a solutionizing treatment (austenitizing) that produces austenite and dissolves the M23C6 carbides and MX carbonitrides, followed by an air cooling that transforms the austenite to martensite. Precipitation sequence during a long-term creep exposure is strongly influenced by the distribution of those in the as heat treated condition of the steels. Their creep strength has been improved by their martensitic lath structure, the precipitation strengthening effects of M23C6 carbides and MX carbonitrides and the solid solution strengthening effects of Mo and W in the matrix. Especially, the precipitation strengthening effect of MX is important because its coarsening rate is small and a fine particle size is maintained for a long-term creep exposure. Z-phase formation from MX-type precipitates has been proposed as a degradation mechanism for a long-term creep regime. The ferritic/martensitic steels should need to improve their performance to be utilized in the high burn-up fuel cladding. For this purpose, KAERI has been developing advanced ferritic/martensitic steels since 2007. This study includes some performance evaluation results of the mechanical and microstructural

  16. Effect of precipitates on long-term creep deformation properties of P92 and P122 type advanced ferritic steels for USC power plants

    International Nuclear Information System (INIS)

    Long-term creep rupture strengths and the microstructural stability of ASME P92 and P122 pipes have been studied using creep testing at the temperatures from 550 to 700 deg. C and detailed scanning transmission electron microscopy. Creep rupture strength of P92 is found to be more stable than that of P122 at temperatures over 600 deg. C, which is mainly due to the difference in their Cr content. P122 type model steel with reduced Cr content, 9%Cr, has been prepared to explore the effect of Cr on the stability of MX and formation of Z-phase during creep deformation. MX in 9%Cr steel is found to be stable even after prolonged exposure at 650 deg. C, while Cr and Fe concentration to MX without marked coarsening has been observed in 10.5%Cr steel after aging for 10,000 h at 650 deg. C. This seems to lead to the transition of MX carbonitride into the Z-phase after aging for 23,000 h, which requires ordering in a M2N lattice to achieve a tetragonal Z-phase to be stable. Creep deformation behavior in the transient creep region of the steels is almost same up to about 7000 h, while in the acceleration creep region the creep rate of 10.5%Cr steel becomes much faster than that of 9%Cr steel, resulting in shorter rupture life. It is obvious that the creep rupture strength degradation starts prior to the formation of Z-phase in 10.5%Cr steel. It is thus concluded that Z-phase is not a necessary factor for degradation of creep rupture strength but the instability of the fine precipitates such as Cr2(C, N) caused by the compositions change like Cr supply to MX carbonitride is more essential.

  17. Influence of the carbon content on the phase composition and mechanical properties of P92-type steel

    Science.gov (United States)

    Dudko, V. A.; Fedoseeva, A. E.; Belyakov, A. N.; Kaibyshev, R. O.

    2015-11-01

    The deformation behavior and the microstructure evolution under the creep of 10Kh9V2MFBR steel (Russian analog of the P92 steel) (in wt %, Fe-8.9% Cr-0.05% Si-0.2% Mn-1.9% W-0.5% Mo-0.25% V-0.07Nb-0.08% N-0.01% B) with the standard (0.1%) and lowered (0.018%) carbon contents have been investigated. After the heat treatment, which included normalizing at 1050°C and tempering at 720-750°C, carbides M 23 C 6 and carbonitrides M(C,N) are formed in the 10Kh9V2MFBR steel, while in the 02Kh9V2MFBR steel (modified P92 steel), carbides M 23 C 6, nitrides M 2N, and carbonitrides M(C,N) as well as δ-ferrite (23%) were found. The measurements of hardness and tensile tests at room and elevated temper-atures did not reveal substantial distinctions in the short-term mechanical properties of both steels. The hardness of steels after tempering was 220 HB. At the same time, the creep characteristics of the steels were found to be different. A decrease in the carbon content leads to an increase in the long-term creep strength and creep limit at 650°C for short-term tests with time-to-fracture shorter than 103 h. The time to fracture of steels with various carbon contents is almost the same in long-term creep tests. Factor responsible for such effect of carbon on the creep strength are discussed.

  18. Effect of nitrogen microalloying on structure and properties of quenched martensitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Prokoshkina, V., E-mail: vgp@tmo.misis.ru [National University of Science and Technology “MISIS”, 4, Leninsky Prospect, Moscow, 119049 (Russian Federation); Kaputkina, L., E-mail: klm@tmo.misis.ru [National University of Science and Technology “MISIS”, 4, Leninsky Prospect, Moscow, 119049 (Russian Federation); Khadeev, G., E-mail: hadeev87@bk.ru [National University of Science and Technology “MISIS”, 4, Leninsky Prospect, Moscow, 119049 (Russian Federation)

    2013-11-15

    Highlights: ► High temperature thermomechanical treatment with various hot rolling schemes is effective for realization of the high-strength state of structural martensitic steels after low-temperature tempering. ► Hot deformation by radial-shear rolling results in higher plasticity at the same strength level in comparison with longitudinal rolling. ► Radial-shear rolling allows obtaining polygonized substructure, peculiar “twisted” grain structure and texture favorable for strength and plasticity in an axial direction. ► The UTS level of the studied nitrogen-containing steels is 300–500 MPa higher than this for nitrogen-free analogs. -- Abstract: Structure, phase transformation features and the strengthening of nitrogen-microalloyed structural C(0.2–0.5)CrNiMoNV steels from alloying and high-temperature thermomechanical treatment (HTMT) by various hot deformation routes have been investigated using X-ray diffraction analysis, optical microscopy, hardness measurements and tensile testing. The nitrogen alloying retards recrystallization processes during hot deformation widens ε-carbonitride region and allows more effective thermomechanical treatment application for realization of high-strength state after low temperature tempering of quenched martensitic steels. Heat and thermomechanical treatment regimes providing increase of deformation and fracture resistance after quenching and tempering were determined. A complete dissolution of special carbonitrides during HTMT and following low-temperature tempering provide high strength level (by 300–500 MPa higher than for nitrogen-free analogs) combined with sufficient ductility and fracture toughness. HTMT comprising hot deformation by the radial-shear rolling with the same strain and deformation temperature as under longitudinal rolling, allows obtaining polygonized substructure, peculiar “twisted” in a definite direction grain structure and texture favorable for strength and plasticity

  19. Contribution to the study of the (U,Pu)C,N system; Contribution a l'etude du systeme (U,Pu)C,N

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzelli, R. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-07-01

    The reactions of UC, PuC, (U,Pu)C, UC{sub 2} and U(C{sub 1-x}O{sub x}) with nitrogen at moderate temperatures (room temperature to 400 C) are described. The influence of the uptake of nitrogen by the powders necessary to sinter the carbides upon the nature of the final product has been investigated; it has been shown that the sintered carbides are hyper-stoichiometric. The reactions of carbon with UN, PuN and (U,Pu)N has also been studied. Under vacuum, carbon reacts on the nitrides at temperatures as low as 1100 C; nitrogen is replaced by carbon and the final product is a carbonitride. The reaction is: MN + x C {yields} MN{sub 1-x}C{sub x} + x/2N{sub 2}. The reaction is limited and the carbonitrides have a fixed composition in presence of M{sub 2}C{sub 3} or MC{sub 2}; hence it is impossible to produce pure MC using the reaction. The ternary diagram U-C-N, Pu-C-N and (U,Pu)C-N have been drawn. They show clearly that it is possible to obtain single phase carbonitrides in a wide domain of compositions. (author) [French] On decrit les reactions avec l'azote de UC, PuC,(U,Pu)C,UC{sub 2} et U(C{sub 1-x}O{sub x}), par action directe de l'azote a temperature moderee (de l'ambiante a 450 C). On a etudie l'influence de la contamination par l'azote des poudres de carbures necessaires au frittage sur la nature des produits frittes; on a montre que les carbures frittes obtenus sont hyperstoechiometriques. On a etudie parallelement les reactions du carbone avec UN, PuN et (U,Pu)N. Sous vide le carbone reagit sur les nitrures des 1100 C: le carbone se substitue a l'azote; l'azote libere est elimine et le produit final est un carbonitrure. La reaction s'ecrit: MN + x C {yields} MN{sub 1-x}C{sub x} + x/2N{sub 2}. La reaction est limitee et les carbonitrures obtenus ont une composition limite fixe en presence des carbures superieurs M{sub 2}C{sub 3} et MC{sub 2}; il est donc impossible d'obtenir MC pur par cette reaction. Les diagrammes

  20. Effect of cobalt on microstructure and creep deformation behaviour of tempered martensitic 9% Cr steel for USC power

    Energy Technology Data Exchange (ETDEWEB)

    Helis, L.; Toda, Y.; Abe, F. [NIMS, Tsukuba (Japan). Structural Metals Center; Hara, T. [NIMS, Tsukuba (Japan). Advanced Nano Characterization Center; Miyazaki, H. [NIMS, Tokyo (Japan). Materials Data Sheet Station

    2008-07-01

    Four ingots with chemical composition 9Cr-3W-0/5Co-0.2V-0.05Nb-0.08C-0.05N, varying in the amount of Co addition were studied. Creep tests were conducted at temperature of 923K. Steels with 3% and 5% Co showed creep resistance superior to those with 1% and 0% Co at stresses above 140MPa. On the other hand 5% Co steel showed a significant deterioration in long term creep properties at 80MPa. Calculation by Thermo-Calc. suggested and observation of microstructure before the creep test confirmed the presence of about 6% and 0.4% of delta-ferrite in Co free and 1% Co steel, respectively. ICP mass spectrometry measurement showed that the amount of precipitation in steels after heat treatment increased with increase in Co addition, especially significant gap was found between 1% and 3% Co steels. Distribution of precipitation was studied by SEM and TEM. Particles of M{sub 23}C{sub 6} and MX carbonitrides preferentially precipitated around prior austenitic grain boundaries. Density of precipitation around these boundaries was found to depend on prior austenitic grain size, which is affected by the presence of anti o-ferrite and precipitation at normalizing temperature. Particles of Laves phase precipitated in the microstructure during the creep tests at 923K at all stresses. Its precipitation at the early stage was also enhanced by the addition of Co. It is known that creep properties of steels with fine grain deteriorate faster than those with coarse grains, due to the faster recovering during the keep at high temperatures. Combination of larger prior austenitic grains and higher precipitation contributes to the prolonged life of steels with higher amount of Co after testing at 923K and 160MPa. Deterioration in long term creep strength of steels with high amount of Co can be attributed to the precipitation Cr(V,Nb)N particles known as Z-phase, which is associated with dissolution of MX carbonitrides. (orig.)

  1. Precipitation in V bearing microalloyed steel containing low concentrations of Ti and Nb

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugam, S.; Tanniru, M.; Misra, R.D.K.; Panda, D.; Jansto, S.

    2005-08-15

    The paper describes the precipitation behaviour in a thermomechanically processed V bearing microalloyed steel containing small additions of Ti and Nb (0.007-0.008 wt-%) using analytical transmission electron microscopy. An intriguing aspect is the significant precipitation of titanium and niobium at these low concentrations, contributing to strength. A high density of multimicroalloyed precipitates of (V, Nb, Ti)(C, N) are observed instead of simple TiN, TiC, and NbC precipitates. They are characterised as cuboidal (45-70 nm), spherical (20-45 nm), irregular (20-45 nm), and fine (10-20 nm). Estimation of solubility products of carbides and nitrides of V, Nb, and Ti implies that the precipitation of titanium occurs primarily in austenite. Interphase precipitation of niobium occurs during austenite to ferrite transformation, while complete precipitation of vanadium takes place in the austenite-ferrite region close to completion of transformation. Substoichiometric concentrations of Ti and Nb, the presence of nitrogen, and the mutual extensive solubility of microalloying carbonitrides explains the formation of core shell (triplex/duplex) precipitates with highly stable nitrides ((Ti, Nb, V)N) in the core and carbides ((Ti, Nb, V)C) in the shell. The qualitative stochiometric ratios of triplex and duplex carbonitrides were Ti{sub 0.}5{sub 3}Nb{sub 0.35}V{sub 0.12} and Ti{sub 0.6}V{sub 0.4}, Nb{sub 0.51}V{sub 0.49} and Ti{sub 0}.{sub 64}Nb{sub 0.36}. Extensive precipitation of fine carbides on dislocation substructures, and sub-boundaries occurred. They were generally characterised as vanadium carbide precipitates with ordered cubic L1{sub 2} structure and exhibited a Baker-Nutting orientation relationship with the ferrite matrix. M{sub 4}C{sub 3} types of carbides were also observed similar to the steel, having high concentrations of Ti and Nb. (author)

  2. Carbon effect in the sintered highspeed steels matrix composites – HSSMC

    Directory of Open Access Journals (Sweden)

    G. Matula

    2012-11-01

    Full Text Available Goal: The goal of this monograph is development of the tool materials being the outcome of the concept of merging the surface engineering as the domain of knowledge with technology which is the powder metallurgy. The result are the fabricated materials with the gradient, high-speed steels matrix composites (HSSMC surface layers on steel substrate, combining the mutually exclusive mechanical properties like the high surface hardness and ductility of a tool.Project/methodology/approach: Modern powder forming technologies were used for fabrication of the developed tool materials, e.g., powder injection moulding, pressureless forming, and classic compacting. Sintering was carried out in the vacuum or protective atmosphere conditions, which makes direct material hardening possible from the sintering temperature. Testing of mechanical properties encompassed hardness testing, bending strength testing, and determining the abrasion wear resistance. Detailed structural examinations were carried out to determine the effect of temperature and atmosphere during sintering on type and size of the carbide- and carbonitride precipitations. Moreover, retained austenite portion was determined after hardening and tempering.Achievements: The original achievement is development of the method of the polymer-powder slurry moulding for fabrication of coatings which, because of the binding agent degradation and sintering, form the homogeneous or gradient HSSMC surface layers on the steel substrate - completed or fabricated in the same technological process. Tool materials fabricated with this method are characteristic of high ductility of the steel core and high hardness of the surface layer.Limitations of research/applications: The assumption of the powder injection moulding technique is forming of the small elements with complex shapes and, therefore, this technology is not designed for fabrication of tools with the big overall dimensions. In case of the pressureless

  3. Spark plasma sintering of Ti{sub y}Nb{sub 1-y}C{sub x}N{sub 1-x} monolithic ceramics obtained by mechanically induced self-sustaining reaction

    Energy Technology Data Exchange (ETDEWEB)

    Borrell, Amparo, E-mail: aborrell@upvnet.upv.es [Instituto de Tecnologia de Materiales (ITM), Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain); Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN) (Consejo Superior de Investigaciones Cientificas - Universidad de Oviedo - Principado de Asturias), Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain); Salvador, Maria Dolores [Instituto de Tecnologia de Materiales (ITM), Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain); Garcia-Rocha, Victoria [ITMA Materials Technology, Parque Tecnologico de Asturias, 33428 Llanera (Asturias) (Spain); Fernandez, Adolfo [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN) (Consejo Superior de Investigaciones Cientificas - Universidad de Oviedo - Principado de Asturias), Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain); ITMA Materials Technology, Parque Tecnologico de Asturias, 33428 Llanera (Asturias) (Spain); Chicardi, Ernesto; Gotor, Francisco J. [Instituto de Ciencia de Materiales de Sevilla (CSIC-US), Calle Americo Vespucio 49, 41092 Sevilla (Spain)

    2012-05-01

    Nanometer-sized titanium-niobium carbonitride powders (Ti{sub y}Nb{sub 1-y}C{sub x}N{sub 1-x}) with different Ti/Nb atomic ratios were obtained by a mechanically induced self-sustaining reaction, and sintered by spark plasma sintering technique at 1500 Degree-Sign C for 1 min in a vacuum atmosphere. Mechanical properties such as hardness and Young's modulus were determined by nanoindentation technique and friction and wear coefficients assessed by ball-on-disk testing using alumina ball in dry sliding conditions. The fracture surface and wear tracks of samples were examined by scanning electron microscopy. Results showed that it is possible to obtain dense monolithic ceramics from the solid solution (Ti{sub y}Nb{sub 1-y}C{sub x}N{sub 1-x}) with good mechanical properties and excellent wear resistance. The optimum values of nanomechanical properties were found for the Ti{sub 0.3}Nb{sub 0.7}C{sub 0.5}N{sub 0.5} ceramic composition, which exhibited a high hardness over 26.0 GPa and Young's modulus around 400 GPa.

  4. New Insights into Understanding Irreversible and Reversible Lithium Storage within SiOC and SiCN Ceramics

    Directory of Open Access Journals (Sweden)

    Magdalena Graczyk-Zajac

    2015-02-01

    Full Text Available Within this work we define structural properties of the silicon carbonitride (SiCN and silicon oxycarbide (SiOC ceramics which determine the reversible and irreversible lithium storage capacities, long cycling stability and define the major differences in the lithium storage in SiCN and SiOC. For both ceramics, we correlate the first cycle lithiation or delithiation capacity and cycling stability with the amount of SiCN/SiOC matrix or free carbon phase, respectively. The first cycle lithiation and delithiation capacities of SiOC materials do not depend on the amount of free carbon, while for SiCN the capacity increases with the amount of carbon to reach a threshold value at ~50% of carbon phase. Replacing oxygen with nitrogen renders the mixed bond Si-tetrahedra unable to sequester lithium. Lithium is more attracted by oxygen in the SiOC network due to the more ionic character of Si-O bonds. This brings about very high initial lithiation capacities, even at low carbon content. If oxygen is replaced by nitrogen, the ceramic network becomes less attractive for lithium ions due to the more covalent character of Si-N bonds and lower electron density on the nitrogen atom. This explains the significant difference in electrochemical behavior which is observed for carbon-poor SiCN and SiOC materials.

  5. Microstructural characterization of 5-9% chromium reduced-activation steels

    Energy Technology Data Exchange (ETDEWEB)

    Jayaram, R. [Univ. of Pittsburgh, PA (United States); Klueh, R.L. [Oak Ridge National Lab., TN (United States)

    1997-08-01

    The microstructures of a 9Cr-2W-0.25-0.1C (9Cr-2WV), a 9Cr-2W-0.25V-0.07Ta-0.1C (9Cr-2WVTa), a 7Cr-2W-0.25V-0.07Ta-0.1C (7Cr-2WVTa), and a 5Cr-2W-0.25V-0.07Ta-0.1C (5Cr-2WVTa) steel (all compositions are in weight percent) have been characterized by Analytical Electron Microscopy (AEM) and Atom Probe Field Ion Microscopy (APFIM). The matrix in all four reduced-activation steels was 100% martensite. In the two 9Cr steels, the stable precipitates were blocky M{sub 23}C{sub 6} and small spherical MC. The two lower-chromium steels contained blocky M{sub 7}C{sub 3} and small needle-shaped carbonitrides in addition to M{sub 23}C{sub 6}. AEM and APFIM analysis revealed that in the steels containing tantalum, the majority of the tantalum was in solid solution. The experimental observations were in good agreement with phases and compositions predicted by phase equilibria calculations.

  6. Evolution of Minor Phases in a 9PctCr Steel: Effect of Tempering Temperature and Relation with Hydrogen Trapping

    Science.gov (United States)

    Hurtado-Noreña, Carolina; Danón, Claudio Ariel; Luppo, María Inés; Bruzzoni, Pablo

    2015-09-01

    The evolution of minor phases in ASTM A335 P91 steel has been studied on specimens submitted to different thermal treatments including a tempering step. Particular emphasis has been put on the tempering temperature range 573 K to 873 K (300 °C to 600 °C), which has not been yet intensively studied. The techniques used in this investigation were X-ray diffraction with synchrotron light, scanning electron microscopy with field emission gun and transmission electron microscopy. In the low tempering temperature range [573 K to 673 K (300 °C to 400 °C)], retained austenite, Fe3C and MX precipitates are observed. In the high tempering temperature range [773 K to 1053 K (500 °C to 780 °C)], M23C6-type carbides, MX-type carbonitrides and M2X precipitates are observed. The effect of the microstructure on hydrogen trapping is analyzed. The distorted matrix around the M2X and MX particles provides the most important trap sites in the P91 steel.

  7. Calorimetric Investigation of Thermal Stability of 304H Cu (Fe-17.7Cr-9.3Ni-2.95Cu-0.91Mn-0.58Nb-0.24Si-0.1C-0.12N-Wt Pct) Austenitic Stainless Steel

    Science.gov (United States)

    Tripathy, Haraprasanna; Subramanian, Raju; Hajra, Raj Narayan; Rai, Arun Kumar; Rengachari, Mythili; Saibaba, Saroja; Jayakumar, Tammana

    2016-05-01

    The sequence of phase instabilities that take place in a Fe-17.7Cr-9.3Ni-0.58Nb-2.95Cu-0.12N (wt pct) austenitic stainless steel (304H Cu grade) as a function of temperature has been investigated using dynamic calorimetry. The results obtained from this investigation are supplemented by Thermocalc-based equilibrium and Scheil-Gulliver nonequilibrium solidification simulation. The following phase transformation sequence is found upon slow cooling from liquid: L → L + γ → L + γ + MX → γ + MX + δ → γ +MX + M23C6 → γ + MX + M23C6 + Cu. Under slow cooling, the solidification follows austenite + ferrite (AF) mode, which is in accordance with Thermocalc prediction and Scheil-Gulliver simulation. However, higher cooling rates result in skeletal δ-ferrite formation, due to increased segregation tendency of Nb and Cr to segregate to interdendritic liquid. The solidification mode is found to depend on combined Nb + Cu content. Experimental estimates of enthalpy change associated with melting and secondary phase precipitation are also obtained. In addition a semi-quantitative study on the dissolution kinetics of M23C6 type carbides has also been investigated. The standard solution treatment at 1413 K (1140 °C) is found to be adequate to dissolve both Cu and M23C6 into γ-austenite; but the complete dissolution of MX type carbonitrides occurs near the melting region.

  8. Corrosion resistance appraisal of TiN, TiCN and TiAlN coatings deposited by CAE-PVD method on WC-Co cutting tools exposed to artificial sea water

    Science.gov (United States)

    Matei, A. A.; Pencea, I.; Branzei, M.; Trancă, D. E.; Ţepeş, G.; Sfăt, C. E.; Ciovica (Coman), E.; Gherghilescu, A. I.; Stanciu, G. A.

    2015-12-01

    A new advanced sintered composite cutting tool has been developed based on tungsten carbide matrix ligated with cobalt (WC-Co) additivated with tantalum carbide (TaC), titanium carbide (TiC) and niobium carbide (NbC) as grain growth inhibitors. Titanium nitride (TiN), titanium carbonitride (TiCN) and titanium aluminium nitride (TiAlN) coatings were deposited on these tools by CAE-PVD technique to find out the best solution to improve the corrosion resistance of this tool in marine environment. The electrochemical behaviours of the specimens in 3.5% NaCl water solution were estimated by potentiodynamic polarization measurements i.e. the open circuit potential (Eoc), corrosion potential (Ecorr) and corrosion current density (icorr). Wide angle X-ray diffraction (WAXD), optical microscopy (OM) and atomic force microscopy (AFM) investigations have been carried on tested and untested specimens to substantiate the corrosion resistance of the tested specimens. Based on the open circuit potential (Eoc) and corrosion potential (Ecorr) results, the tested specimens were ranked as TiN, TiAlN, TiCN and WC-Co while on corrosion current density (icorr) and protective efficiency (P) values they have been ranked as TiN, TiAlN, WC-Co and TiCN. The WAXD, MO and AFM results unambiguously show that the corrosion resistance depends on the nature and morphology of the coating.

  9. Cyclic deformation behaviour of austenitic steels at ambient and elevated temperatures

    Indian Academy of Sciences (India)

    Th Nebel; D Eifler

    2003-02-01

    The aim of the present investigation is to characterise cyclic deformation behaviour and plasticity-induced martensite formation of metastable austenitic stainless steels at ambient and elevated temperatures, taking into account the influence of the alloying elements titanium and niobium. Titanium and niobium are ferrite-stabilising elements which influence the ferrite crystallisation. Furthermore, They form carbides and/or carbonitrides and thus limit the austenite-stabilising effect of carbon and nitrogen. Several specimen batches of titanium and niobium alloyed austenite and of a pure Cr-Ni-steel for comparison were tested under stress and total strain control at a frequency of 5 Hz and triangular load-time waveforms. Stress-strain-hysteresis and temperature measurements were used at ambient temperature to characterise cyclic deformation behaviour. Plasticity-induced martensite content was detected with non-destructive magnetic measuring techniques. The experiments yield characteristic cyclic deformation curves and corresponding magnetic signals according to the actual fatigue state and the amount of martensite. Fatigue behaviour of X6CrNiTi1810 (AISI 321), X10CrNiCb189 (AISI 348) and X5CrNi1810 (AISI 304) is characterised by cyclic hardening and softening effects which are strongly influenced by specific loading conditions. Martensite formation varies with the composition, loading conditions, temperature and number of cycles.

  10. Welding stainless steels for structures operating at liquid helium temperature

    International Nuclear Information System (INIS)

    Superconducting magnets for fusion energy reactors require massive monolithic stainless steel weldments which must operate at extremely low temperatures under stresses approaching 100 ksi (700 MPa). A three-year study was conducted to determine the feasibility of producing heavy-section welds having usable levels of strength and toughness at 4.20K for fabrication of these structures in Type 304LN plate. Seven welding processes were evaluated. Test weldments in full-thickness plate were made under severe restraint to simulate that of actual structures. Type 316L filler metal was used for most welds. Welds deposited under some conditions and which solidify as primary austenite have exhibited intergranular embrittlement at 4.20K. This is believed to be associated with grain boundary metal carbides or carbonitrides precipitated during reheating of already deposited beads by subsequent passes. Weld deposits which solidify as primary delta ferrite appear immune. Through use of fully austenitic filler metals of low nitrogen content under controlled shielded metal arc welding conditions, and through use of filler metals solidifying as primary delta ferrite where only minimum residuals remain to room temperature, welds of Type 316L composition have been made with 4.2K yield strength matching that of Type 304LN plate and acceptable levels of soundness, ductility and toughness

  11. Texture recrystallization formation in 08Kh18T1

    International Nuclear Information System (INIS)

    Effect of heat treatment of semi-finished hot-rolled products before cold rolling and the strain degree on texture formation and the value of a plastic anisotropy coefficient in a cold-rolled sheet of the 08Kh18T1 steel after recrystallization has been investigated. The cold-rolled sheet of the ferritic stainless 08Kh18T1 steel after recrystallization at 950 deg C during 3 min is shown to have texture components like low-carbon steels: (111)(110), (111)(112), (112)(110), (100)(110) and axial component with axis (111). The quantative ratio of ideal oreientations in the steel depends on the degree of cold metal strain and to a larger extent on the structural state of semi-finished rolled products before cold rolling. Titanium addition in a stainless steel with 18% Cr affects formation, being favourable for texture sheet stamping with predominance of grain orientation with plane (111) only then, when titanium binds carbon and nitrogen in heat stable and disperse carbonitrides, which be in a cold-rolled sheet before recrystallization semi-finished hot-rolled products is to be subjected to stabilizing heat treatment before rolling. Increase in metal of orientations with plane (111) affects favourably increase of the plastic anisotropy coefficient of sheet rolling

  12. Structure of MoCN films deposited by cathodic arc evaporation

    International Nuclear Information System (INIS)

    Molybdenum carbonitride (MoCN) coatings were deposited onto HS6-5-2 steel substrate using pure Mo targets in mixed acetylene and nitrogen atmosphere by cathodic arc evaporation. The structural properties of MoCN coatings with different carbon contents (as an effect of the C2H2 flow rate) were investigated systematically. Phase and chemical composition evolution of the coatings were characterized both by the glancing angle of X-ray diffraction (XRD) and wavelength dispersive spectrometry, respectively. These analyses have been supplemented by estimates of grain sizes and stress in the coatings. The XRD results show that the increase in acetylene flow rate causes the formation of molybdenum carbide (MoC) hexagonal phase in the coatings, a reduction of grain size and an increase in internal stress. - Highlights: • MoN and MoCN coatings were deposited by cathodic arc evaporation in nitrogen atmosphere. • MoCN coatings were formed using different acetylene flow rates. • Phase composition evolution was observed. • Crystallite size and stress were calculated

  13. The Cause of Premature Tensile Fracture of Gas-Nitrocarburized Steel

    Science.gov (United States)

    Hwang, Jaeyoon; Han, Jeongho; Lee, Young-Kook

    2016-08-01

    The objective of the present study was to investigate the mechanism of premature tensile fracture of the gas-nitrocarburized steel. For this purpose, tempered martensitic steel specimens were nitrocarburized at 853 K (580 °C) for maximum 3.5 hours, and tensile-strained at room temperature. The prolongation of nitrocarburizing time caused the high strength, the short elongation, and the heavy serrations at the yield point elongation range of the tensile flow curve. The serrations were generated by vertical cracking at the specimen surface, which started at the bottom of the gauge portion, and were propagated to the top of the gauge portion with increasing tensile strain up to the yield point elongation. The vertical cracks were triggered at the porous compound layer when the local deformation occurred by the propagation of the Lüders band from the bottom to the top of the gauge portion. The cracks readily passed through the diffusion layer with an assistance of ɛ-carbonitride particles, which formed at the boundaries of tempered martensite during nitrocarburizing, resulting in brittle fracture at the diffusion layer and finally in premature failure of the gas-nitrocarburized specimens.

  14. Use of AWCC in evaluation of unknown fissile materials

    International Nuclear Information System (INIS)

    An important technological problem in the sphere of non-proliferation and safeguards is nondestructive analysis (NDA) methodology for qualitative and quantitative characterization of nuclear materials. Additionally, NDA tends to be labor and time intensive. Two NDA techniques used at KIPT included Gamma Spectroscopy (for qualitative analysis) and Neutron activation (for quantitative analysis). Gamma Spectroscopy was used to confirm the presence of radionuclides within the samples, whereas an Active Well Coincidence Counter (AWCC) in the active mode was used to quantitatively determine the 235U content in particular types of fissile materials at KIPT. This paper describes the usage of the AWCC at NSG KIPT for characterizing nuclear materials for IAEA safeguards. It was also an opportunity to estimate fissile materials of unknown composition. The equipment used was a model JCC-51 AWCC using a shift register model JSR-12 from Canberra and two neutron sources [AN-HP (241ArnLi)]. A Compaq Presario computer using Windows version of NCC (Los Alamos software) was used to operate the AWCC. Materials studied in this project included highly enriched nuclear material in the form of powder, compacts (tablets, microspheres, rods), salt and scrap. The chemical composition of nuclear material included uranium metal, uranium dioxide, uranium nitride, uranium carbonitride, thorium dioxide, and mixtures of these compounds. Scrap consisted of uranium and impurities of hydrocarbons, carbon, silicon, tungsten, etc

  15. Multi analysis of the effect of grain size on the dynamic behavior of microalloyed steels

    Energy Technology Data Exchange (ETDEWEB)

    Zurek, Anna K [Los Alamos National Laboratory; Muszka, K [AGH; Majta, J [AGH; Wielgus, M [AGH

    2009-01-01

    This study presents some aspects of multiscale analysis and modeling of variously structured materials behavior in quasi-static and dynamic loading conditions. The investigation was performed for two different materials of common application: high strength microalloyed steel (HSLA, X65), and as a reference more ductile material, Ti-IF steel. The MaxStrain technique and one pass hot rolling processes were used to produce ultrafine-grained and coarse-grained materials. The efficiency and inhomogeneity of microstructure refinement were examined because of their important role in work hardening and the initiation and growth of fracture under tensile stresses. It is shown that the combination of microstructures characterized by their different features contributes to the dynamic behavior and final properties of the product. In particular, the role of solute segregation at grain boundaries as well as precipitation of carbonitrides in coarse and ultrafine-grained structures is assessed. The predicted mechanical response of ultrafine-grained structures, using modified KHL model is in reasonable agreement with the experiments. This is a result of proper representation of the role of dislocation structure and the grain boundary and their multiscale effects included in this model.

  16. Carbothermic synthesis of 820 μm uranium nitride kernels: Literature review, thermodynamics, analysis, and related experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lindemer, T.B. [Harbach Engineering and Solutions, Dayton, OH 45458 (United States); Voit, S.L.; Silva, C.M.; Besmann, T.M. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6223 (United States); Hunt, R.D., E-mail: huntrd@ornl.gov [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6223 (United States)

    2014-05-01

    The US Department of Energy is developing a new nuclear fuel that would be less susceptible to ruptures during a loss-of-coolant accident. The fuel would consist of tristructural isotropic coated particles with uranium nitride (UN) kernels with diameters near 825 μm. This effort explores factors involved in the conversion of uranium oxide–carbon microspheres into UN kernels. An analysis of previous studies with sufficient experimental details is provided. Thermodynamic calculations were made to predict pressures of carbon monoxide and other relevant gases for several reactions that can be involved in the conversion of uranium oxides and carbides into UN. Uranium oxide–carbon microspheres were heated in a microbalance with an attached mass spectrometer to determine details of calcining and carbothermic conversion in argon, nitrogen, and vacuum. A model was derived from experiments on the vacuum conversion to uranium oxide–carbide kernels. UN-containing kernels were fabricated using this vacuum conversion as part of the overall process. Carbonitride kernels of ∼89% of theoretical density were produced along with several observations concerning the different stages of the process.

  17. The Cause of Premature Tensile Fracture of Gas-Nitrocarburized Steel

    Science.gov (United States)

    Hwang, Jaeyoon; Han, Jeongho; Lee, Young-Kook

    2016-05-01

    The objective of the present study was to investigate the mechanism of premature tensile fracture of the gas-nitrocarburized steel. For this purpose, tempered martensitic steel specimens were nitrocarburized at 853 K (580 °C) for maximum 3.5 hours, and tensile-strained at room temperature. The prolongation of nitrocarburizing time caused the high strength, the short elongation, and the heavy serrations at the yield point elongation range of the tensile flow curve. The serrations were generated by vertical cracking at the specimen surface, which started at the bottom of the gauge portion, and were propagated to the top of the gauge portion with increasing tensile strain up to the yield point elongation. The vertical cracks were triggered at the porous compound layer when the local deformation occurred by the propagation of the Lüders band from the bottom to the top of the gauge portion. The cracks readily passed through the diffusion layer with an assistance of ɛ-carbonitride particles, which formed at the boundaries of tempered martensite during nitrocarburizing, resulting in brittle fracture at the diffusion layer and finally in premature failure of the gas-nitrocarburized specimens.

  18. Microstructural analysis as the indicator for suitability of weld repairing of the heat resistant Cr - Ni steel

    International Nuclear Information System (INIS)

    Metallurgical evaluation was performed on a fractured column tube of the reformer furnace in an ammonia plant. The tubes were manufactured from centrifugally cast heat resistant steel HK 40. Optical and scanning electron microscope (SEM) were used for microstructural and fracture analysis. For composition determination of the micro constituents energy dispersive X ray spectroscopy (EDS) was used. To evaluate mechanical properties, hardness and microhardness measurements were performed. Investigations based on the microstructural features with the idea to indicate suitability of weld repair of the column were performed in this study. It was observed that the crack initiation, caused by oxidation/corrosion and thermal stresses induced by temperature gradient, appeared in the inner side of the tube wall and propagation occurred along grain boundaries. The results clearly showed the presence of an irregular microstructure which contributed to crack propagation through the tube wall. An occurrence of precipitated needle-shaped carbides/carbonitrides and brittle s phase was also identified in the microstructure. Results of the microstructural and fracture analysis clearly indicate that reformer furnace columns made of heat resistant steel HK 40 were unsuitable for weld repair. (Author)

  19. Effect of vanadium and titanium modification on the microstructure and mechanical properties of a microalloyed HSLA steel

    Energy Technology Data Exchange (ETDEWEB)

    Show, B.K., E-mail: bijay_show@rediffmail.com [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad 500058, Andhra Pradesh (India); Veerababu, R., E-mail: veeru_met@yahoo.com [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad 500058, Andhra Pradesh (India); Balamuralikrishnan, R., E-mail: bmk_pgh@yahoo.com [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad 500058, Andhra Pradesh (India); Malakondaiah, G., E-mail: director@dmrl.drdo.in [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad 500058, Andhra Pradesh (India)

    2010-03-15

    DMR-249A is a low carbon microalloyed high-strength low-alloy (HSLA) steel. While DMR-249A plates of thickness less than 18 mm meet the specified room temperature yield strength (390 MPa) and Charpy impact toughness (78J at -60 deg. C) in the as-rolled condition, thicker plates require water quenching and tempering. Elimination of the quenching and tempering treatment can result in significant cost and energy savings besides offering increased productivity. Therefore, in the present work, modifications to the base DMR-249A steel composition have been investigated with the objective of producing thicker gage plates (24 mm) capable of meeting the specified properties in the normalized condition. Plates from three modified compositions i.e., containing 0.015 wt.% titanium and 0.06, 0.09 and 0.12 wt.% vanadium respectively and one composition with 0.10 wt.% vanadium, and without any titanium were investigated over a range of normalizing temperatures (875-1000 deg. C). In all cases, only the steel without titanium met the specified properties in the normalized condition. Microstructural investigations using scanning and transmission electron microscopy, as well as support evidence from calculations performed using ThermoCalc software, suggest that this is due to the presence of nanoscale vanadium rich carbonitride particles distributed throughout the matrix. These particles were absent in the titanium-containing steel at a similar vanadium level.

  20. Structure and Properties of Thermomechanically-processedHSLA Steels for Naval Applications

    Directory of Open Access Journals (Sweden)

    A. Ghosh

    2007-07-01

    Full Text Available Four high-strength low-alloy (HSLA steels with varying chemical compositions were forgedin two different temperature ranges followed by cooling in various media. Microstructures andmechanical properties of the steels were evaluated. The microstructures obtained in water–quenchedlow-carbon HSLA steels were lath martensite packet within the pancaked grains. On air or sandcooling predominantly bainitic ferrite or granular bainite structure forms. The strength propertiesof these steels decreased with decrease in cooling rate and is accompanied by an increase inelongation and impact toughness values. The ductile-to-brittle transition temperature of HSLA-100grade steel was found to be – 40 oC. The impact fracture surface of air cooled HSLA-100 steel showedductile failure with formation of dimples at 20 oC and at – 20 oC. The fracture mode changed to brittlefailure with formation of cleavage and river pattern at – 40 oC and at – 60 oC. The microstructuresof the ultra-low carbon HSLA steel show lath ferrite or granular ferrite in water-quenched condition.With slower cooling rate, the volume fraction of lath ferrite decreased with an increase in formationof polygonal ferrite. The maximum strength value obtained in air-cooled condition is achieved dueto precipitation of fine microalloying carbides and carbonitrides. Slower cooling rate increases thevolume fraction of polygonal ferrite which increases the toughness value.

  1. A comprehensive study on the microstructure of high strength low alloy pipeline welds

    Energy Technology Data Exchange (ETDEWEB)

    Beidokhti, B., E-mail: beidokhti@um.ac.ir [Department of Materials Science and Metallurgical Engineering, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Kokabi, A.H.; Dolati, A. [Department of Material Science and Engineering, Sharif University of Technology, Azadi Ave., Tehran (Iran, Islamic Republic of)

    2014-06-01

    Highlights: • The effect of alloying elements on the microstructure of HSLA welds was investigated. • The microstructure of welds has been studied carefully using optical microscopy, scanning and transition electron microscopy. • Type and shape of main inclusions was determined. - Abstract: The microstructural characteristic of HSLA welds containing different amounts of titanium were evaluated carefully. It was observed that the microstructure of welds consisted of ferrite with mixed morphologies, and small amounts of pearlite and martensite–austenite micro-constituents. Because of insufficient time for diffusion of carbon, formation of pearlite lamellae could not be completed in the weld region. Martensite was formed from carbon enrichment of austenite during nucleation and growth of acicular ferrite and bainitic ferrite. While coarse manganese sulfide particles had weak interface strength with matrix and formed some micro-fissures; increasing titanium amount of welds dispersed different modified morphologies of inclusions in the microstructure. Several types of precipitates including spherical, cubical, fine and irregular titanium carbonitride were found in the microstructure and they were favorite sites for nucleation of acicular ferrite. The size of cubical/spherical and fine precipitates was measured between 70–100 and 10–20 nm, respectively. Low energy interface of inclusion/matrix and the depletion of carbon in austenite were proposed as the nucleation mechanisms of acicular ferrite from nano-sized inclusions.

  2. X-ray photoelectron spectroscopy of select multi-layered transition metal carbides (MXenes)

    Science.gov (United States)

    Halim, Joseph; Cook, Kevin M.; Naguib, Michael; Eklund, Per; Gogotsi, Yury; Rosen, Johanna; Barsoum, Michel W.

    2016-01-01

    In this work, a detailed high resolution X-ray photoelectron spectroscopy (XPS) analysis is presented for select MXenes-a recently discovered family of two-dimensional (2D) carbides and carbonitrides. Given their 2D nature, understanding their surface chemistry is paramount. Herein we identify and quantify the surface groups present before, and after, sputter-cleaning as well as freshly prepared vs. aged multi-layered cold pressed discs. The nominal compositions of the MXenes studied here are Ti3C2Tx, Ti2CTx, Ti3CNTx, Nb2CTx and Nb4C3Tx, where T represents surface groups that this work attempts to quantify. In all the cases, the presence of three surface terminations, sbnd O, sbnd OH and sbnd F, in addition to OH-terminations relatively strongly bonded to H2O molecules, was confirmed. From XPS peak fits, it was possible to establish the average sum of the negative charges of the terminations for the aforementioned MXenes. Based on this work, it is now possible to quantify the nature of the surface terminations. This information can, in turn, be used to better design and tailor these novel 2D materials for various applications.

  3. Effect of carbon and niobium on the microstructure and impact toughness of a high silicon 12% Cr ferritic/martensitic heat resistant steel

    International Nuclear Information System (INIS)

    In order to guide the design of 9–12% Cr ferritic/martensitic (F/M) heat resistant steels appropriate for use in accelerator-driven system, the impact toughness and behavior of precipitation of a 12% Cr F/M heat resistant steel containing high C and Si concentrations have been investigated. Particular focus has been given to the interaction of carbon and carbonitride-forming element. Because of the presence of primary NbC and a large amount of M23C6, the impact toughness of the investigated steel was much lower than that of the commercial 9–12% Cr F/M heat resistant steels. The primary NbC crystallizes directly from liquid metal when the Nb concentration is higher than a critical value. The critical value of Nb decreases with increase in the carbon concentration. In addition, the higher content and faster precipitation kinetics of M23C6 in the investigated steel during the tempering heat treatment also lowers the impact toughness

  4. 渗碳工艺在汽车车身齿轮中的应用%Application of Carburizing Technology in Automotive Gear

    Institute of Scientific and Technical Information of China (English)

    覃莉莉

    2013-01-01

    The practical application of the heat treatment process of carburizing and carbonitriding in automotive gear was experimentally researched.The results show that the process combined with gear hookers can realize the purpose to easily control microstructure and simple operating,and obtain a certain number of surface residual austenite and carbide mixture,enhance the strength and excellent plasticity,ductility of automotive gear,so it also increases the anti-fatigue life.The process is used in practical production to shorten manufacturing cycle,save production cost,improve economic benefits.%实验研究了渗碳及碳氮共渗热处理工艺在汽车齿轮生产中的实用效果.结果表明,该工艺结合齿轮挂具技术,不仅可以实现组织易控、操作简单的目的,还可以获得一定数量的表层残余奥氏体和碳化物的混合物,提高车用齿轮的强度,得到优良的材料塑形和韧性,从而提高了车用齿轮的抗疲劳寿命;该技术应用到实际生产中,缩短制造周期,节约生产成本,提高工厂的经济效益.

  5. Synthesis of nanostructured multiphase Ti(C,N)/a-C films by a plasma focus device

    International Nuclear Information System (INIS)

    Nanostructured multiphase Ti(C,N)/a-C films were deposited using a 3.3 kJ pulsed plasma focus device onto silicon (1 0 0) substrates at room temperature. The plasma focus device, fitted with solid titanium anode instead of usual hollow copper anode, was operated with nitrogen and Ar/CH4 as the filling gas. Films were deposited with different number of shots, at 80 mm from top of the anode and at zero angular position with respect to anode axis. X-ray diffraction results show the diffraction peaks related to different compounds such as TiC2, TiN, Ti2CN, Ti and TiC0.62 confirming the deposition of multiphase titanium carbo-nitride composite films on silicon. X-ray photoelectron spectroscopy confirms the formation of Ti-C, C-N, Ti-N, Ti-O and C-C bonds in the films. Scanning electron microscopy reveals that the nanostructure grains are agglomerates of smaller nanoparticles about 10-20 nm in size. Raman studies verify the formation of multiphase Ti(C,N) and also of amorphous graphite in the films. The maximum microhardness value of the composite film is 14.8 ± 1.3 GPa for 30 shots.

  6. Wear Behavior of Austempered Ductile Iron with Nanosized Additives

    Directory of Open Access Journals (Sweden)

    J. Kaleicheva

    2014-03-01

    Full Text Available The microstructure and properties of austempered ductile iron (ADI strengthened with nanosized addtives of titanium nitride + titanium carbonitride (TiN + TiCN, titanium nitride TiN and cubic boron nitride cBN are investigated. The TiN, TiCN and cBN, nanosized particles are coated by electroless nickel coating EFTTOM-NICKEL prior to the edition to the melt. The spheroidal graphite iron samples are undergoing an austempering, including heating at 900 оС for an hour, after that isothermal retention at 280 оС, 2 h and 380 оС, 2h. The metallographic analysis by optical metallographic microscope GX41 OLIMPUS and hardness measurements by Vickers Method are performed. The structure of the austempered ductile iron consists of lower bainite and upper bainite.Experimental investigation of the wear by fixed abrasive are also carried out. The influence of the nanosized additives on the microstructure, mechanical and tribological properties of the austempered ductile irons (ADI is studied.

  7. Structure of MoCN films deposited by cathodic arc evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Gilewicz, A., E-mail: adam.gilewicz@tu.koszalin.pl [Koszalin University of Technology, Faculty of Technology and Education, Sniadeckich 2, 75-453 Koszalin (Poland); Jedrzejewski, R.; Kochmanska, A.E. [West Pomeranian University of Technology Szczecin, Faculty of Mechanical Engineering and Mechatronics, 19 Piastów Ave., 70-313 Szczecin (Poland); Warcholinski, B. [Koszalin University of Technology, Faculty of Technology and Education, Sniadeckich 2, 75-453 Koszalin (Poland)

    2015-02-27

    Molybdenum carbonitride (MoCN) coatings were deposited onto HS6-5-2 steel substrate using pure Mo targets in mixed acetylene and nitrogen atmosphere by cathodic arc evaporation. The structural properties of MoCN coatings with different carbon contents (as an effect of the C{sub 2}H{sub 2} flow rate) were investigated systematically. Phase and chemical composition evolution of the coatings were characterized both by the glancing angle of X-ray diffraction (XRD) and wavelength dispersive spectrometry, respectively. These analyses have been supplemented by estimates of grain sizes and stress in the coatings. The XRD results show that the increase in acetylene flow rate causes the formation of molybdenum carbide (MoC) hexagonal phase in the coatings, a reduction of grain size and an increase in internal stress. - Highlights: • MoN and MoCN coatings were deposited by cathodic arc evaporation in nitrogen atmosphere. • MoCN coatings were formed using different acetylene flow rates. • Phase composition evolution was observed. • Crystallite size and stress were calculated.

  8. Solid solution cermet: (Ti,Nb)(CN)-Ni cermet.

    Science.gov (United States)

    Kwon, Hanjung; Jung, Sun-A

    2014-11-01

    Solid solution powders without W, (Ti,Nb)(CN) powders with a B1 structure (NaCl like), were synthesized by high energy milling and carbothermal reduction in nitrogen. The range of molar ratios of Ti/Nb for forming complete (Ti,Nb)(CN) phase was broader than that of Ti/W for the (Ti,W)(CN) phase because carbide or carbonitride of Nb had a B1 crystal structure identical to Ti(CN) while WC had a hexagonal crystal structure. The results revealed that the hardness of (Ti,Nb)(CN)-Ni cermets was higher than that of (Ti,W)(CN)-Ni cermets. The lower density of the (Ti,Nb)(CN) powder contributed to the higher hardness compared to (Ti,W)(CN) because the volumetric ratio of (Ti,Nb)(CN) in the (Ti,Nb)(CN)-Ni cermets was higher than that of (Ti,Nb)(CN) in the (Ti,W)(CN)-Ni cermets at the same weight ratio of Ni. Additionally, it was assumed that intrinsic the properties of (Ti,Nb)(CN) could also be the cause for the high hardness of the (Ti,Nb)(CN)-Ni cermets. PMID:25958611

  9. Microstructure and cutting performance of Ti(C, N)-based cermets heat-treated in nitrogen

    Institute of Scientific and Technical Information of China (English)

    LIU Wenjun; XIONG Weihao; ZHENG Yong; SHI Zengmin; YE Jiajian

    2007-01-01

    Ti(C, N)-based cermets were treated using hot isostatic pressing (HIP) at 1423 K in nitrogen. The microstructures compared with the as-sintered cermets were investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray analysis, and electron microprobe analysis. It was found that high nitrogen activity in the surface zone resulted in the formation of gradient structure. Approximately 20-μm-deep, nitrogen-rich and titanium-rich hard surface zone was introduced by the beat treatment. The nitrogen activity was the driving force that caused the transportation of the atoms through the binder, titanium towards the surface, and tungsten and molybdenum inwards. In the surface zone, the particle size became fine, the inner rim disappeared, and the volume fraction of the outer rim and the binder phase considerably reduced. Small grains of TiN, WC, Mo2C, and nitrogen-rich carbonitride phases formed in the surface zone during the heat treatment, improving the tribological property of the heat-treated cermet.

  10. Plastic behavior of medium carbon vanadium microalloyed steel at temperatures near g « a transformation

    Directory of Open Access Journals (Sweden)

    Lourenço N.J.

    2001-01-01

    Full Text Available Dilatometric techniques were used to build the continuous cooling transformation (CCT diagram for a medium carbon microalloyed steel; the microstructure and hardness were determined at different cooling rates. The mechanical behavior of the steel in the austenite field and at temperatures approaching austenite to ferrite transformation was measured by means of hot torsion tests under isothermal and continuous cooling conditions. The no recrystallization temperatures, Tnr, and start of phase transformation, Ar3, were determined under continuous cooling condition using mean flow stress vs. inverse of absolute temperature diagrams. Interruption of static recrystallization within the interpass time in the austenite field indicated that the start of vanadium carbonitride precipitation occurred under 860 °C. Austenite transformation was found to start at around 710 °C, a temperature similar to that measured by dilatometry, suggesting that interphase precipitation delays the transformation of deformed austenite. Pearlite was observed at temperatures ranging from 650 °C to 600 °C, with the flow curves taking on a particular shape, i.e., stress rose sharply as strain was increased, reaching peak stress at low deformation, around 0.2, followed by an extensive softening region after peak stress.

  11. Dynamic Recrystallization Behaviour of Nb-Ti Microalloyed Steels

    Institute of Scientific and Technical Information of China (English)

    MA Liqiang; LIU Zhenyu; JIAO Sihai; YUAN Xiangqian; WU Di

    2008-01-01

    The dynamic recrystallization(DRX)behavior of Nb-Ti microalloyed steels was investigated by isothermal single compression tests in the temperature range of 900-1 150 ℃ at constant strain rates of 0.1-5 S-1.DRX was retarded effectively at low temperature due to the onset of dynamic precipitation of Nb and Ti carbonitrides,resulting in higher values of the peak strain.An expression was developed for the activation energy of deformation as a function of the contents of Nb and Ti in solution as well as other alloying elements.A BeW value of corrective factor was determined and applied to quantify the retardation produced by increase in the amount of Nb and Ti dissolved at the reheating temperature.The ratio of critical strain to peak strain decreases with increasing equivalent Nb content.In addition,the effects of Ti content and deformation conditions on DRX kinetics and steady state grain size were determined.Finally,the kinetics of dynamic precipitation was determined and effect of dynamic precipitation on the onset of DRX was clarified based on the comparison between precipitate pinning force and recrystallization driving force.

  12. PERFORMANCE IMPROVEMENT OF CREEP-RESISTANT FERRITIC STEEL WELDMENTS THROUGH THERMO-MECHANICAL TREATMENT AND ALLOY DESIGN

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Yukinori [ORNL; Babu, Prof. Sudarsanam Suresh [University of Tennessee, Knoxville (UTK); Shassere, Benjamin [ORNL; Yu, Xinghua [ORNL

    2016-01-01

    Two different approaches have been proposed for improvement of cross-weld creep properties of the high temperature ferrous structural materials for fossil-fired energy applications. The traditional creep strength-enhanced ferritic (CSEF) steel weldments suffer from Type IV failures which occur at the fine-grained heat affected zone (FGHAZ). In order to minimize the premature failure at FGHAZ in the existing CSEF steels, such as modified 9Cr-1Mo ferritic-martensitic steels (Grade 91), a thermo-mechanical treatment consisting of aus-forging/rolling and subsequent aus-aging is proposed which promotes the formation of stable MX carbonitrides prior to martensitic transformation. Such MX remains undissolved during welding process, even in FGHAZ, which successfully improves the cross-weld creep properties. Another approach is to develop a new fully ferrtic, creep-resistant FeCrAl alloy which is essentially free from Type IV failure issues. Fe-30Cr-3Al base alloys with minor alloying additions were developed which achieved a combination of good oxidation/corrosion resistance and improved tensile and creep performance comparable or superior to Grade 92 steel.

  13. Precipitation behavior and martensite lath coarsening during tempering of T/P92 ferritic heat-resistant steel

    Science.gov (United States)

    Xu, Lin-qing; Zhang, Dan-tian; Liu, Yong-chang; Ning, Bao-qun; Qiao, Zhi-xia; Yan, Ze-sheng; Li, Hui-jun

    2014-05-01

    Tempering is an important process for T/P92 ferritic heat-resistant steel from the viewpoint of microstructure control, as it facilitates the formation of final tempered martensite under serving conditions. In this study, we have gained deeper insights on the mechanism underlying the microstructural evolution during tempering treatment, including the precipitation of carbides and the coarsening of martensite laths, as systematically analyzed by optical microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The chemical composition of the precipitates was analyzed using energy dispersive X-ray spectroscopy. Results indicate the formation of M3C (cementite) precipitates under normalized conditions. However, they tend to dissolve within a short time of tempering, owing to their low thermal stability. This phenomenon was substantiated by X-ray diffraction analysis. Besides, we could observe the precipitation of fine carbonitrides (MX) along the dislocations. The mechanism of carbon diffusion controlled growth of M23C6 can be expressed by the Zener's equation. The movement of Y-junctions was determined to be the fundamental mechanism underlying the martensite lath coarsening process. Vickers hardness was estimated to determine their mechanical properties. Based on the comprehensive analysis of both the micro-structural evolution and hardness variation, the process of tempering can be separated into three steps.

  14. An investigation on microstructure and mechanical propertiesof a Nb-microalloyed nano/ultrafine grained 201 austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Samaei Baghbadorani, H., E-mail: h.samaeibaghbadorani@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of); Kermanpur, A. [Department of Materials Engineering, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of); Najafizadeh, A. [Department of Materials Engineering, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of); Fould Institute of Technology, Fouldshare 84916-63763 (Iran, Islamic Republic of); Behjati, P.; Rezaee, A.; Moallemi, M. [Department of Materials Engineering, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of)

    2015-06-11

    The present study was aimed to investigate the mechanical properties of a nano/ultrafine grained Nb-containing 201 austenitic stainless steel. For this purpose, 90% cold rolled sheets with fully martensitic microstructure were isothermally annealed at 900 °C for different times of 1 to 1800 s, leading to the reversion of strain- induced α′-martensite to austenite and significant grain refinement. Ferritescopy, X-ray diffractometery and optical/electron microscopy techniques along with hardness measurements and tensile tests were used to study the evolution in microstructure and mechanical properties in the course of annealing. It was found that heavy cold-rolling promoted formation of Nb-rich carbonitrides which effectively retarded the growth of fine reverted austenite grains. The obtained results showed that the complete transformation of martensite to austenite took about 60 s with the corresponding austenite grain size of about 90 nm. This sample had an ultrahigh yield strength of 1170 MPa, which was almost four times higher than that of the raw material and outstanding elongation of 37%. Further, the true stress–strain curves of the reversion annealed samples revealed two distinct uniform elongation stages (stage I and stage II), whereas, the onset of stage II was concurrent with pronounced strain hardening. This was related to the sharp increase in the formation of α′-martensite upon tensile straining.

  15. Oxygen sensors increasing role to improve high temperature industrial processes

    International Nuclear Information System (INIS)

    Zirconium Dioxide (ZrO/sub 2/) Oxygen sensors have benefited from design improvements in recent months which increase reliability and use in high temperature applications such as metal treating, refractory and ceramics processes and conservation of fuel during combustion. Zirconia as an In-Situ Oxygen Sensor is capable of meeting extreme conditions of ''temperature'', ''time'' and ''atmosphere''. A small solid cylinder of zirconia has been fused successfully to an Alumina tube. The adaptation of metal alloy tube as a conductor, creates a unique approach to improve performance and the service life of Oxygen Sensors in heat treating metals. A Microprocessor Controller has been utilized to provide direct readout in % weight Carbon from .1 to 1.5%, or in % oxygen for oxygen rich atmospheres. The microprocessor is capable of solving the complex Nernst equation; EMF=.0215 x T x 1n o/sub 1//O/sub 2/. The controller will adjust automatically to hold a constant setpoint, regardless of process temperature change. Atmosphere control systems, using a Zirconia In-Situ Oxygen Sensor, are finding use in Carbonitriding, Carbon restoration, neutral hardening, Endothermic gas generator control, ceramic and refractory processing in kilns and control of combustion burners

  16. Distribution of arsenic on micro-interfaces in a kind of Cr, Nb and Ti microalloyed low carbon steel produced by a compact strip production process

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Y.Z., E-mail: tozyz1@163.com [Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081 (China) and School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China); Li, J.C.; Liang, D.M.; Liu, P. [School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China)

    2011-10-17

    Highlights: {yields} We evaluate the effect of Ti, V and Nb on grain boundary segregation of arsenic in steel. {yields} Arsenic segregates strongly on grain boundary at the base-metal/scale interface. {yields} Arsenic segregates on subgrain boundaries in the hot rolled steel strip. - Abstract: Distribution of arsenic on micro-interfaces in the Cr, Nb and Ti microalloyed low carbon steel strip was investigated by SEM, TEM and EDS in a compact strip production (CSP) and a following reheating processes. It is discovered that, in the CSP processes, the arsenic content within grains at the half thickness of the strip was a little higher than that at the grain boundaries, which was attributed to a quicker occupying of vacancies by carbon, Nb and Ti atoms on grain boundaries. However, arsenic segregated strongly on grain boundaries at the interface between the base metal and the oxide scale, where it had a maximum arsenic content of 2.93 wt.%. The strongly segregation of arsenic on grain boundaries at the interface between the base metal and the oxide scale may lead to difficulties in the subsequent production galvanized sheet with the hot rolled CSP strip that contains arsenic. When the hot rolled strip (CSP) was reheated to 1100 deg. C, held for half an hour, arsenic segregated strongly on subgrain boundaries for the availability of more vacancies caused by the solid solution of alloy carbonitrides.

  17. Effect of vanadium and titanium modification on the microstructure and mechanical properties of a microalloyed HSLA steel

    International Nuclear Information System (INIS)

    DMR-249A is a low carbon microalloyed high-strength low-alloy (HSLA) steel. While DMR-249A plates of thickness less than 18 mm meet the specified room temperature yield strength (390 MPa) and Charpy impact toughness (78J at -60 deg. C) in the as-rolled condition, thicker plates require water quenching and tempering. Elimination of the quenching and tempering treatment can result in significant cost and energy savings besides offering increased productivity. Therefore, in the present work, modifications to the base DMR-249A steel composition have been investigated with the objective of producing thicker gage plates (24 mm) capable of meeting the specified properties in the normalized condition. Plates from three modified compositions i.e., containing 0.015 wt.% titanium and 0.06, 0.09 and 0.12 wt.% vanadium respectively and one composition with 0.10 wt.% vanadium, and without any titanium were investigated over a range of normalizing temperatures (875-1000 deg. C). In all cases, only the steel without titanium met the specified properties in the normalized condition. Microstructural investigations using scanning and transmission electron microscopy, as well as support evidence from calculations performed using ThermoCalc software, suggest that this is due to the presence of nanoscale vanadium rich carbonitride particles distributed throughout the matrix. These particles were absent in the titanium-containing steel at a similar vanadium level.

  18. Relation among rolling parameters, microstructures and mechanical properties in an acicular ferrite pipeline steel

    International Nuclear Information System (INIS)

    The correlation among thermo-mechanical controlled processing (TMCP) parameters, microstructures and mechanical properties of an acicular ferrite (AF) pipeline steel was investigated in this study. The steel was hot rolled by four different kinds of TMCP to obtain different AF microstructures, and the corresponding mechanical properties were analyzed. Electron backscatter diffraction (EBSD) analysis was conducted to determine the effective grain size (EGS) in the steel. It was found that the EGS in the steel reduced obviously with decrease of the finish rolling temperature (FRT), but little changed with the cooling rate (CR) and the simulated coiling temperature (SCT). Additionally, the fraction of low angle grain boundaries (LAGBs) increased with increasing CR in the experimental range. It was shown that yield strength of the steel was enhanced by the increased CR and SCT, and reduced FRT, which were corresponding with the increases of LAGB fraction and precipitated carbonitrides as well as the decrease of EGS, respectively. Charpy impact results showed that the low temperature toughness of the steel with FRT about 40 oC above Ar3 tended to be the best, which was in good accordance with the highest fraction of high angle grain boundaries (HAGBs), but seemed not to be related with the EGS.

  19. Effects of nickel and cobalt addition on creep strength and microstructure of the precipitation-strengthened 15Cr ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Shibuya, Masachika; Toda, Yoshiaki; Sawada, Kota; Kushima, Hideaki; Kimura, Kazuhiro [National Inst. for Materials Science, Tsukuba, Ibaraki (Japan)

    2010-07-01

    Creep strength of 15Cr ferritic steel with ferrite matrix was increased by precipitation strengthening of intermetallic compounds. It was higher than those of 9-12Cr ferritic steels with a tempered martensitic microstructure strengthened by carbide and carbonitride. Addition of nickel was confirmed to improve Charpy impact toughness of the 15Cr steels, however, creep strength was slightly reduced by the addition of nickel. Microstructure of the 15Cr steel changes from ferrite single phase to dual phases of ferrite and martensite with the addition of nickel which is an austenite stabilizing element. The 15Cr steels investigated in the previous study, contain 3mass% of cobalt which is also an austenite stabilizing element, therefore, the influence of nickel and cobalt combination on mechanical properties and microstructure of the 15Cr-1Mo-6W-V-Nb steel is investigated in this study. Creep strength, Charpy impact toughness and microstructure of the steel were strongly influenced by the composition of nickel and cobalt. Design guideline of the 15Cr steel is discussed with respect to a role of microstructure and combination of nickel and cobalt addition. (orig.)

  20. Effect of microalloying elements and hot deformation on microstructure of direct-quenched steel plates

    International Nuclear Information System (INIS)

    The effects of microalloys (Nb, V, Ti and Nb-Ti) and hot deformation on microstructure were investigated in direct-quenched HSLA steels. Nb and Ti were shown to improve both strength and toughness of the steels, while V showed little effectiveness in improving the strength of the steels. Quantitative analysis showed that dissolved NB and Ti in austenite increased the hardenability of austenite, so that they refined the ferrite grain size and increased the fraction of bainite in the steels. On the other hand, dissolved V was much less effective in increasing;the hardenability of austenite. It was found that an addition of 0.03%Nb decreases the strength of Ti bearing steels reheated to a low temperature. Combined additions of microalloying elements decreases the solubility of carbonitrides and reduces the amount of dissolved microalloying elements in austenite during reheating through the formation of complex precipitates. Controlled rolling below 950 C had a considerable effect on improving the toughness of Nb bearing direct-quenched steels. Deformation of more than 50% in the un-recrystallized austenite region significantly refined the bainite microstructure, while deformation of less than 30% was less effective. It was shown that the increase in toughness due to the heavy deformation of un-recrystallized austenite resulted from the decrease in the length of lathlike ferrite and the decrease in the packet size of bainite

  1. B4CN3 and B3CN4 monolayers as the promising candidates for metal-free spintronic materials

    Science.gov (United States)

    Pan, Hongzhe; Sun, Yuanyuan; Zheng, Yongping; Tang, Nujiang; Du, Youwei

    2016-09-01

    The search for candidates of spintronic materials, especially among the two-dimensional (2D) materials, has attracted tremendous attentions over the past decades. By using a particle swarm optimization structure searching method combined with density functional calculations, two kinds of boron carbonitride monolayer structures (B4CN3 and B3CN4) are proposed and confirmed to be dynamically and kinetically stable. Intriguingly, we demonstrate that the magnetic ground states of the two B x C y N z systems are ferromagnetic ordering with a high Curie temperature of respectively 337 K for B4CN3 and 309 K for B3CN4. Furthermore, based on their respective band structures, the B4CN3 is found to be a bipolar magnetic semiconductor (BMS), while the B3CN4 is identified to be a type of spin gapless semiconductor (SGS), both of which are potential spintronic materials. In particular, carrier doping in the B4CN3 can induce a transition from BMS to half-metal, and its spin polarization direction is switchable depending on the doped carrier type. The BMS property of B4CN3 is very robust under an external strain or even a strong electric field. By contrast, as a SGS, the electronic structure of B3CN4 is relatively sensitive to external influences. Our findings successfully disclose two promising materials toward 2D metal-free spintronic applications.

  2. Comportamiento de la descarga luminiscente anormal dependiendo de la atmósfera gaseosa en un sistema apto para tratamiento de materiales

    Directory of Open Access Journals (Sweden)

    Armando Sarmiento-Santos

    2013-01-01

    Full Text Available The generation of the DC glow discharge can be in stationary state or with flow of gas atmosphere, where the gas is between two electrodes. Applying a voltage between the electrodes above a certain threshold value or disruption value that depends on the type of gas, the geometric characteristics of the system, and atmosphere pressure, it is possible the generation and maintenance of gaseous discharge. The type of discharge may be classified according to the potential difference applied between the electrodes and the corresponding electrical current flowing through the system, being the abnormal glow discharge of particular interest. Reactive species generated in the glow discharge are used to generate physical and chemical interactions on a surface, which can be exploited for surface treatment and synthesis of materials such as nitriding, carbonitriding and polymerization, but also has great potential for application as a thermal source. The present work describes the set up of a furnace for materials treatment which works by the impact of active species from the negative column of low pressure glow discharge, using direct current. In this setup, the temperature is controlled as a function of gas pressure, type and gas proportions of the mixture in which the discharge is generated (Ar, N2 , H2 , aire, Ar/N2 , N2 /H2 , y Ar/H2 .

  3. Studies on plutonium-zirconium co-precipitation and carbothermal reduction in the internal gelation process for nitride fuel preparation

    Science.gov (United States)

    Hedberg, Marcus; Ekberg, Christian

    2016-10-01

    Sol-gel based techniques are one way to lower the handling of highly radioactive powders when producing transuranium-containing fuel. In this work inert matrix (Zr0.6,Pu0.4)N fuel has been produced by internal gelation followed by carbothermal reduction. No co-gelation was observed during internal gelation and a two phase material could be detected by scanning electron microscopy in the nitrided microspheres. Sintering has been performed in both Ar and N2. X-ray diffraction revealed that sintering in N2 produced a solid solution, while sintering in Ar did not. The final metal composition in the microspheres was determined by ICP-MS to be about 41% Pu and 59% Zr. Vegard's law was applied to estimate the nitride purity in the solid solution pellet to be Zr0.6Pu0.4N0.87C0.13 making the final material more of a carbonitride than a pure nitride.

  4. Study on the cutting of self-fluxing alloy of Ni-Cr-WC systems. Ni-Cr-WC kei jiyo gokin yosha himaku no sessaku kako ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Inui, Y.; Hayami, T.; Kubohori, T.; Ikuta, T. (Kinki University, Osaka (Japan). Faculty of Science and Technology)

    1991-03-31

    In this paper, to investigate the cutting of sprayed self-fluxing alloy films of Ni-Cr-WC system containing 35 and 50%WC-Co composite grains in the Ni-Cr matrix, cutting tests by the lathe turning method were performed using CBN tools containing either oxide or carbonitride systems as a binder. Self-fluxing alloy films with about 2mm thichness, which were sprayed on the surface of a cylindrical substrate made of low carbon steel, were used as cutting materials. The wear was increased rapidly at the early stage of cutting, but this was changed to the gradual increasing level after about 30 seconds of cutting. The tool was subject to the abrasive action in cutting, and was fractured when CBN content was low. The CBN tool containing oxide system was found most suitable for cutting of these alloys. The variation in resistance to cutting was observed at the early stage, but this was disappeared after 90 seconds. The roughness of the cutting surface was decreased with cutting time. 8 refs., 10 figs., 2 tabs.

  5. Investigation of the isothermal precipitation behaviour of nickel-base alloys using electrochemical phase extraction

    International Nuclear Information System (INIS)

    Electrochemical phase extraction methods have been developed empirically for the selective separation of the precipitates in metallic materials. A detailed description of the process has been undertaken to allow optimization for various nickel-base alloys. For this part of the investigation, 16 model alloys were prepared as test electrodes and the electrolyte composition was varied over a wide range. The results enabled a series of effects to be explained on the basis of electrochemical data. The large number of test parameters limited the scope of the preliminary experiments and the range of model alloys used. In the nickel-base alloys, titanium carbo-nitride and primary M6C precipitates were identified. During isothermal ageing, M23C6 (except in Alloy KSN), Ni3Al (in INCONEL 617), Laves phases (in Hastelloy X and INCONEL 617), M12C (in HASTELLOY X and INCONEL 617) and α-tungsten (in the tungsten-containing alloys) were precipitated. The precipitation behaviour changed in the alloys investigated from intracrystalline to intercrystalline with increasing ageing temperature. The intracrystalline secondary precipitations affect the microhardness, structure and the solid-solution lattice. (orig.)

  6. Effect of carbon and niobium on the microstructure and impact toughness of a high silicon 12% Cr ferritic/martensitic heat resistant steel

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Zhongfei [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Wang, Pei, E-mail: pwang@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Li, Dianzhong [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Zhang, Yutuo [Shenyang Ligong University, 6 Nanping Road, Shenyang 110159 (China); Li, Yiyi [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2014-10-20

    In order to guide the design of 9–12% Cr ferritic/martensitic (F/M) heat resistant steels appropriate for use in accelerator-driven system, the impact toughness and behavior of precipitation of a 12% Cr F/M heat resistant steel containing high C and Si concentrations have been investigated. Particular focus has been given to the interaction of carbon and carbonitride-forming element. Because of the presence of primary NbC and a large amount of M{sub 23}C{sub 6}, the impact toughness of the investigated steel was much lower than that of the commercial 9–12% Cr F/M heat resistant steels. The primary NbC crystallizes directly from liquid metal when the Nb concentration is higher than a critical value. The critical value of Nb decreases with increase in the carbon concentration. In addition, the higher content and faster precipitation kinetics of M{sub 23}C{sub 6} in the investigated steel during the tempering heat treatment also lowers the impact toughness.

  7. TEM investigations of fine niobium precipitates in HSLA steel

    Energy Technology Data Exchange (ETDEWEB)

    Beres, M.; Weirich, T.E.; Mayer, J. [Gemeinschaftslabor fuer Elektronenmikroskopie (GFE), RWTH Aachen, Aachen (Germany); Hulka, K. [Niobium Products Co. GmbH, Duesseldorf (Germany)

    2004-11-01

    Commercially produced 0.03% C, 0.08% Nb, 0.01% Ti high strength low alloyed (HSLA) steel in the form of 20 mm thick plates was investigated. The steel was thermomechanically processed and the mechanical properties of the steel were evaluated by tensile testing. Using analytical and high resolution transmission electron microscopy the distribution, morphology, composition, crystal structure and particle size of niobium and titanium carbonitrides were observed and identified in these steels. The distribution of the precipitates was found to be nearly random, with occasional occurrence of precipitation free zones. Complex agglomerates with a cubic TiN seed crystal overgrown by a cubic NbC particle were the most commonly observed precipitates. Further TEM analysis in the accelerated cooled and tempered specimens in 1/4 plate thickness did not reveal any evidence that additional precipitation in the ferrite occurred. Precipitation in ferrite was only detected after subsequent cold deformation and tempering of the same samples. By a combination of EFTEM, STEM, HRTEM in addition to EDX spectroscopy, a large population of strain induced NbC precipitates with fcc crystal structure ranging in size down to 2 nm were identified in the ferrite matrix. (orig.)

  8. Modeling of point defects and rare gas incorporation in uranium mono-carbide

    Science.gov (United States)

    Chartier, A.; Van Brutzel, L.

    2007-02-01

    An embedded atom method (EAM) potential has been established for uranium mono-carbide. This EAM potential was fitted on structural properties of metallic uranium and uranium mono-carbide. The formation energies of point defects, as well as activation energies for self migration, have been evaluated in order to cross-check the suitability of the potential. Assuming that the carbon vacancies are the main defects in uranium mono-carbide compounds, the migration paths and energies are consistent with experimental data selected by Catlow[C.R.A. Catlow, J. Nucl. Mater. 60 (1976) 151]. The insertion and migration energies for He, Kr and Xe have also been evaluated with available inter-atomic potentials [H.H. Andersen, P. Sigmund, Nucl. Instr. and Meth. B 38 (1965) 238]. Results show that the most stable defect configuration for rare gases is within uranium vacancies. The migration energy of an interstitial Xe is 0.5 eV, in agreement with the experimental value of 0.5 eV [Hj. Matzke, Science of advanced LMFBR fuels, Solid State Physics, Chemistry and Technology of Carbides, Nitrides and Carbonitrides of Uranium and Plutonium, North-Holland, 1986].

  9. Precipitation behavior and martensite lath coarsening during tempering of T/P92 ferritic heat-resistant steel

    Institute of Scientific and Technical Information of China (English)

    Lin-qing Xu; Dan-tian Zhang; Yong-chang Liu; Bao-qun Ning; Zhi-xia Qiao; Ze-sheng Yan; Hui-jun Li

    2014-01-01

    Tempering is an important process for T/P92 ferritic heat-resistant steel from the viewpoint of microstructure control, as it facili-tates the formation of final tempered martensite under serving conditions. In this study, we have gained deeper insights on the mechanism underlying the microstructural evolution during tempering treatment, including the precipitation of carbides and the coarsening of martensite laths, as systematically analyzed by optical microscopy, transmission electron microscopy, and high-resolution transmission electron mi-croscopy. The chemical composition of the precipitates was analyzed using energy dispersive X-ray spectroscopy. Results indicate the for-mation of M3C (cementite) precipitates under normalized conditions. However, they tend to dissolve within a short time of tempering, owing to their low thermal stability. This phenomenon was substantiated by X-ray diffraction analysis. Besides, we could observe the precipitation of fine carbonitrides (MX) along the dislocations. The mechanism of carbon diffusion controlled growth of M23C6 can be expressed by the Zener’s equation. The movement of Y-junctions was determined to be the fundamental mechanism underlying the martensite lath coarsening process. Vickers hardness was estimated to determine their mechanical properties. Based on the comprehensive analysis of both the micro-structural evolution and hardness variation, the process of tempering can be separated into three steps.

  10. High sensitivity and high resolution element 3D analysis by a combined SIMS–SPM instrument

    Directory of Open Access Journals (Sweden)

    Yves Fleming

    2015-04-01

    Full Text Available Using the recently developed SIMS–SPM prototype, secondary ion mass spectrometry (SIMS data was combined with topographical data from the scanning probe microscopy (SPM module for five test structures in order to obtain accurate chemical 3D maps: a polystyrene/polyvinylpyrrolidone (PS/PVP polymer blend, a nickel-based super-alloy, a titanium carbonitride-based cermet, a reticle test structure and Mg(OH2 nanoclusters incorporated inside a polymer matrix. The examples illustrate the potential of this combined approach to track and eliminate artefacts related to inhomogeneities of the sputter rates (caused by samples containing various materials, different phases or having a non-flat surface and inhomogeneities of the secondary ion extraction efficiencies due to local field distortions (caused by topography with high aspect ratios. In this respect, this paper presents the measured relative sputter rates between PVP and PS as well as in between the different phases of the TiCN cermet.

  11. 9-12% Cr heat resistant steels. Alloy design, TEM characterisation of microstructure evolution and creep response at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Rojas Jara, David

    2011-03-21

    This work was carried out aiming to design and characterise 9-12% Cr steels with tailormade microstructures for applications in fossil fuel fired power plants. The investigations concentrated in the design and characterisation of heat resistant steels for applications in high oxidising atmospheres (12% Cr) and 9% Cr alloys for components such as rotors (P91). ThermoCalc calculations showed to be a reliable tool for alloy development. The modeling also provided valuable information for the adjustment of the processing parameters (austenisation and tempering temperatures). Two 12% Cr heat resistant steels with a fine dispersion of nano precipitates were designed and produced supported by thermodynamic modeling (ThermoCalc). A detailed characterisation of the microstructure evolution at different creep times (100 MPa / 650 C / 8000 h) was carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis were correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M{sub 23}C{sub 6} carbides) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hundred hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M{sub 23}C{sub 6} precipitates show best creep properties. The influence of hot-deformation and tempering temperature on the microstructure evolution on one of the designed 12% Cr alloys was studied during short-term creep at 80-250 MPa and 650 C. Quantitative determination of dislocation density and sub-grain size in the initial microstructure and after creep was investigated by STEM combined with the high-angle annular dark-field detector (HAADF). A correlation between microstructure

  12. Plasma-arc reactor for production possibility of powdered nano-size materials

    Energy Technology Data Exchange (ETDEWEB)

    Hadzhiyski, V; Mihovsky, M; Gavrilova, R, E-mail: plasmalab@uctm.edu, E-mail: mihovsky@uctm.edu, E-mail: r.gavrilova@abv.bg [University of Chemical Technology and Metallurgy-Sofia, Plasma Metallurgy Research Laboratory ' PLASMALAB' (Bulgaria)

    2011-01-01

    Nano-size materials of various chemical compositions find increasing application in life nowadays due to some of their unique properties. Plasma technologies are widely used in the production of a range of powdered nano-size materials (metals, alloys, oxides, nitrides, carbides, borides, carbonitrides, etc.), that have relatively high melting temperatures. Until recently, the so-called RF-plasma generated in induction plasma torches was most frequently applied. The subject of this paper is the developments of a new type of plasma-arc reactor, operated with transferred arc system for production of disperse nano-size materials. The new characteristics of the PLASMALAB reactor are the method of feeding the charge, plasma arc control and anode design. The disperse charge is fed by a charge feeding system operating on gravity principle through a hollow cathode of an arc plasma torch situated along the axis of a water-cooled wall vertical tubular reactor. The powdered material is brought into the zone of a plasma space generated by the DC rotating transferred plasma arc. The arc is subjected to Auto-Electro-Magnetic Rotation (AEMR) by an inductor serially connected to the anode circuit. The anode is in the form of a water-cooled copper ring. It is mounted concentrically within the cylindrical reactor, with its lower part electrically insulated from it. The electric parameters of the arc in the reactor and the quantity of processed charge are maintained at a level permitting generation of a volumetric plasma discharge. This mode enables one to attain high mean mass temperature while the processed disperse material flows along the reactor axis through the plasma zone where the main physico-chemical processes take place. The product obtained leaves the reactor through the annular anode, from where it enters a cooling chamber for fixing the produced nano-structure. Experiments for AlN synthesis from aluminium power and nitrogen were carried out using the plasma reactor

  13. Physical and chemical characterization of surfaces of nitrogen implanted steels

    International Nuclear Information System (INIS)

    The studied steels are of industrial type (42CD4, 100C6, Z200C13). Very often, the low carbon steel XCO6 has been used as a reference material. The aim of the research is to understand and to explain the mechanisms of wear resistance to improvement. A good characterization of the implanted layer is thus necessary. It implies to establish the distribution profiles of the implanted ions to identify the chemical and structural state of the phases created during implantation as a function of various implantation parameters (dose, temperature). Temperature is the particularly parameter. Its influence is put in evidence both during implantation and during annealings under vacuum. Nitrogen distribution profiles are performed thanks to the non destructive 15N(p,αγ)12C nuclear reaction. The chemical state of the Fe-N phases formed by implantation is determined using first Electron Conversion Moessbauer Spectroscopy and secondly, as a complement, using grazing angle X ray diffraction. The detected compounds are ε-nitrides, ε-carbonitrides, (N) - martensite and α-Fe16N2 whose evolution is carefully followed versus temperature. The diffraction technique reveals a texture of the implanted layer. This preferentiel orientation is found to be temperature dependent but dose independent. The carbon presence at the surface is studied as a function of implantation conditions (vacuum, temperature, dose). Carbon profiling is obtained using α backscattering (12C(α,α') reaction at 5,7 MeV). Thus is achieved a complete characterization of the implanted zone whose evolution as a function of implantation parameters (especially temperature) is correlated with tribological results

  14. Characterization of TiN, TiC and Ti(C,N) in titanium-alloyed ferritic chromium steels focusing on the significance of different particle morphologies

    International Nuclear Information System (INIS)

    Titanium-alloyed ferritic chromium steels are a competitive option to classical austenitic stainless steels owing to their similar corrosion resistance. The addition of titanium significantly influences their final steel cleanliness. The present contribution focuses on the detailed metallographic characterization of titanium nitrides, titanium carbides and titanium carbonitrides with regard to their size, morphology and composition. The methods used are manual and automated Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy as well as optical microscopy. Additional thermodynamic calculations are performed to explain the precipitation procedure of the analyzed titanium nitrides. The analyses showed that homogeneous nucleation is decisive at an early process stage after the addition of titanium. Heterogeneous nucleation gets crucial with ongoing process time and essentially influences the final inclusion size of titanium nitrides. A detailed investigation of the nuclei for heterogeneous nucleation with automated Scanning Electron Microscopy proved to be difficult due to their small size. Manual Scanning Electron Microscopy and optical microscopy have to be applied. Furthermore, it was found that during solidification an additional layer around an existing titanium nitride can be formed which changes the final inclusion morphology significantly. These layers are also characterized in detail. Based on these different inclusion morphologies, in combination with thermodynamic results, tendencies regarding the formation and modification time of titanium containing inclusions in ferritic chromium steels are derived. - Graphical abstract: Display Omitted - Highlights: • The formation and modification of TiN in the steel 1.4520 was examined. • Heterogeneous nucleation essentially influences the final steel cleanliness. • In most cases heterogeneous nuclei in TiN inclusions are magnesium based. • Particle morphology provides important information

  15. Biotribological behavior of Ag-ZrCxN1-x coatings against UHMWPE for joint prostheses devices.

    Science.gov (United States)

    Calderon V, S; Sánchez-López, J C; Cavaleiro, A; Carvalho, S

    2015-01-01

    This study aims to evaluate the structural, mechanical and tribological properties of zirconium carbonitrides (ZrCxN1-x) coatings with embedded silver nanoparticles, produced with the intention of achieving a material with enhanced multi-functional properties, including mechanical strength, corrosion resistance, tribological performance and antibacterial behavior suitable for their use in joint prostheses. The coatings were deposited by direct current (DC) reactive magnetron sputtering onto 316 L stainless steel, changing the silver content from 0 to 20 at% by modifying the current density applied to the targets. Different nitrogen and acetylene gas fluxes were used as reactive gases. The coatings revealed different mixtures of crystalline ZrCxN1-x, silver nanoparticles and amorphous carbon phases. The hardness of the films was found to be mainly controlled by the ratio between the hard (ZrCxN1-x) and soft (Ag and amorphous carbon) phases in the films, fluctuating between 7.4 and 20.4 GPa. The coefficient of friction, measured against ultra-high molecular weight polyethylene (UHMWPE) in Hank's balanced salt solution with 10 gL(-1) albumin, is governed by the surface roughness and hardness. The UHMWPE wear rates were in the same order of magnitude (between 1.4 and 2.0 × 10(-6)mm(3)N(-1)m(-1)), justified by the effect of the protective layer of albumin formed during the tests. The small differences were due to the hydrophobic/hydrophilic character of the surface, as well as to the silver content.

  16. Nanostructured component fabrication by electron beam-physical vapor deposition

    Science.gov (United States)

    Singh, Jogender; Wolfe, Douglas E.

    2005-08-01

    Fabrication of cost-effective, nano-grained net-shaped components has brought considerable interest to Department of Defense, National Aeronautics and Space Administration, and Department of Energy. The objective of this paper is to demonstrate the versatility of electron beam-physical vapor deposition (EB-PVD) technology in engineering new nanostructured materials with controlled microstructure and microchemistry in the form of coatings and net-shaped components for many applications including the space, turbine, optical, biomedical, and auto industries. Coatings are often applied on components to extent their performance and life under severe environmental conditions including thermal, corrosion, wear, and oxidation. Performance and properties of the coatings depend upon their composition, microstructure, and deposition condition. Simultaneous co-evaporation of multiple ingots of different compositions in the high energy EB-PVD chamber has brought considerable interest in the architecture of functional graded coatings, nano-laminated coatings, and design of new structural materials that could not be produced economically by conventional methods. In addition, high evaporation and condensate rates allowed fabricating precision net-shaped components with nanograined microstructure for various applications. Using EB-PVD, nano-grained rhenium (Re) coatings and net-shaped components with tailored microstructure and properties were fabricated in the form of tubes, plates, and Re-coated spherical graphite cores. This paper will also present the results of various metallic and ceramic coatings including chromium, titanium carbide (TiC), titanium diboride (TiB2), hafnium nitride (HfN), titanium-boron-carbonitride (TiBCN), and partially yttria stabilized zirconia (YSZ) TBC coatings deposited by EB-PVD for various applications.

  17. The effects of laser surface modification on the microstructure and properties of gas-nitrided 42CrMo4 steel

    Science.gov (United States)

    Kulka, M.; Panfil, D.; Michalski, J.; Wach, P.

    2016-08-01

    Gas nitriding, together with gas carburizing and gas carbonitriding, was the most commonly used thermochemical treatment, resulting in many advantageous properties: high hardness, enhanced corrosion resistance, considerably improved wear resistance and fatigue strength. However, an unfavorable increase in the thickness of compound layer (ε+γ‧) close to the surface was observed after conventional gas nitriding. This was the reason for undesirable embrittlement and flaking. Therefore, a controlled gas nitriding was developed, reducing the thickness of compound layer. In this study, laser modification with or without re-melting was carried out after the controlled gas nitriding in order to change microstructure and to improve wear resistance. The effects of laser beam power on the dimensions of simple laser tracks were analyzed. It enabled to control the obtained microstructure and to select the laser processing parameters during producing the multiple tracks. Such a treatment was necessary to investigate wear resistance. Laser re-melting resulted in dissolving the majority of nitrides as well as in producing the martensitic structure in re-melted and heat-affected zones. This treatment required argon shielding in order to protect the surface against uncontrolled oxidation. Laser heat treatment without re-melting caused a modification of ε nitrides which became less porous and more compact. Simultaneously, it provided heat-affected zone with the partially martensitic structure of increased hardness below compound zone. Argon shielding was not necessary in this case because of the resistance of nitrides to oxidation during rapid heating and cooling. All the laser-modified layers, irrespective if the nitrided layer was re-melted or not, were characterized by the improved wear resistance compared to the typical gas-nitrided layer.

  18. Effect of welding thermal cycles on the structure and properties of simulated heat-affected zone areas in X10CrMoVNb9-1 (T91) steel at a state after 100,000 h of operation

    International Nuclear Information System (INIS)

    The article presents results of structural tests (light, scanning electron and scanning transmission electron microscopy) of X10CrMoVNb9-1 (T91) creep-resisting steel after approximately 100,000 h of operation. It was ascertained that the parent metal of T91 steel is characterized by the microstructure of tempered martensite with M23C6 carbide precipitates and few dispersive precipitates of MX-type niobium and vanadium carbonitrides. The most inconvenient change in T91 steel precipitate morphology due to long-term operation is the appearance of the Laves Fe2Mo phase which along with M23C6 carbide particles forms elongated blocks and conglomerates on grain boundaries. The article also presents results of tests related to the effect of simulated welding thermal cycles on selected properties of X10CrMoVNb9-1 (T91) grade steel at a state after approximately 100,000 h of operation. The tests involved the determination of the chemical composition of the steel tested as well as impact tests, hardness measurements and microscopic metallographic examination (based on light microscopy) of simulated heat-affected zone (HAZ) areas for a cooling time (t8/5) restricted within a range between 3 s and 120 s, with and without heat treatment. The tests revealed that, among other results, hardness values of simulated HAZ areas in X10CrMoVNb9-1 (T91) steel do not guarantee cold crack safety of the steel at the state without additional heat treatment. It was also observed that simulated welding thermal cycles of cooling times t8/5=3, 12, 60 and 120 s do not significantly affect the toughness and hardness of simulated HAZ areas of the steel tested

  19. Microstructural development and mechanical properties of iron based cermets processed by pressureless and spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Alvaredo, P. [Department of Materials Science and Engineering, IQMAAB, University Carlos III Madrid, Avda. de la Universidad, 30, 28911 Leganes (Spain); Gordo, E., E-mail: elena.gordo@uc3m.es [Department of Materials Science and Engineering, IQMAAB, University Carlos III Madrid, Avda. de la Universidad, 30, 28911 Leganes (Spain); Van der Biest, O.; Vanmeensel, K. [Katholieke Universiteit Leuven, Kasteelpark Arenberg, 44 3001 Heverlee (Belgium)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Processing of Fe-based cermets by pressureless sintering and spark plasma sintering. Black-Right-Pointing-Pointer Influence of carbon content on the sintering mechanism and hardness. Black-Right-Pointing-Pointer The cermet phase diagram was calculated and permits to explain the microstructure. Black-Right-Pointing-Pointer SPS provides ferritic matrix and different carbide distribution than CPS samples. Black-Right-Pointing-Pointer Pressureless sintered samples contain retained austenite at room temperature. - Abstract: Iron-based cermets are an interesting class of metal-ceramic composites in which properties and the factors influencing them are to be explored. In this work the metal matrix contains Cr, W, Mo and V as alloying elements, and the hard phase is constituted by 50 vol% of titanium carbonitride (TiCN) particles. The work studies the influence of the C content and the processing method on the sinterability, microstructure and hardness of the developed cermet materials. For that purpose, cermet samples with different C content in the matrix (0 wt%, 0.25 wt%, 0.5 wt%, 1.0 wt%) were prepared by conventional pressureless sintering (CPS) and, in order to achieve finer microstructures and to reduce the sintering time, by spark plasma sintering (SPS). The density and hardness (HV30) of the processed materials was evaluated, while their phase composition and microstructure was characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The equilibrium phase diagram of the composite material was calculated by ThermoCalc software in order to elucidate the influence of the carbon content on the obtained phases and developed microstructures.

  20. Effects of heat treatment processes on microstructure and creep properties of a high nitrogen 15Cr-15Ni austenitic heat resistant stainless steel

    International Nuclear Information System (INIS)

    Highlights: → CTMT induced elongated clusters of fine (Nb,Cr,Fe)(C,N) particles. → Hot rolling in MTMT induced evenly distributed fine (Nb,Cr,Fe)(C,N). → Number and distribution of Cu precipitates not affected by hot rolling. → Distribution homogeneity of fine (Nb,Cr,Fe)(C,N) promotes creep strength increase. → Finer grain size structure promotes lower creep ductility. - Abstract: Conventional thermo-mechanical treatment (CTMT) and modified thermo-mechanical treatment (MTMT) process were applied for manufacturing a high nitrogen niobium-stabilized 15Cr-15Ni austenitic alloy. CTMT process consists of 5 h of solution treatment at 1270 deg. C followed by water quenching and subsequent aging at 820 deg. C for 50 h. MTMT process differs from CTMT process in hot plastic deformation performed immediately after the solution treatment at 1270 deg. C and longer aging time. Microstructure and creep properties of the steel obtained by both processing routes were investigated. Creep rupture tests at 750 deg. C showed double increase in rupture time brought about by MTMT process. Examination of crept microstructure by transmission electron microscopy revealed that the improved creep properties in MTMT process were mainly due to improved distribution uniformity of fine nano-sized carbonitride precipitates in the austenitic matrix and that MTMT process has no effects on the number density and distribution of copper precipitates present in the steel. However, the creep ductility in MTMT process drastically reduced comparing to CTMT process. The higher density of grain boundaries due to finer grain recrystallized microstructures and the formation of higher volume fraction of coarser M23C6 precipitates at the boundaries are believed to be the main reason for the lower creep ductility in MTMT process.

  1. Microhardness study of Ti(C, N films deposited on stainless steel 316 by the hallow cathode discharge gun

    Directory of Open Access Journals (Sweden)

    A.J. Novinrooz

    2005-12-01

    Full Text Available Purpose: The micro hardness properties of Titanium Carbonitride composite coated on SS-316 substrates were studied to achieve a desired harden surfaces.Design/methodology/approach: Hollow Cathode Discharge gun (HCD–gun was employed for deposition of the Ti(C, N on SS-316. The evaporated and ionized metal (Ti was coated as an under layer with 0.5 ampere beam current and 100 volt bias voltage. The reactant nitrogen and methane gasses were fed through inlet in to the chamber containing Ti element to form Ti (C, N matrix with an optimized ratio.Findings: In this work, Glow Discharge Optical emission Spectroscopy (GDOS used for compositional analysis of the content elements. On the bases of this operation it was revealed the existence of Ti, C, N elements, X-ray diffraction (XRD technique was utilized to investigate films crystalline structure. The investigation showed that samples with different stoichiometry have a fcc structure with (111 plan of reflection. The atomic ratio of carbon and nitrogen were measured using energy dispersive X-ray (EDX analysis. The optimized value was funned to be TiC0.87 N0.13. The atomic force microscopy (AFM and scanning electron microscopy (SEM were employed to study the films microstructure. A hardness of 3250 HV was obtained in the carbon content C/C+ N atomic ratio of 9 to 1 using a Vickers microhardness tester.Research limitations/implications: As the study was carried out on a limited surfaces, we shall endeavor further attempt on large area deposition.Practical implications: The tools coated in titanium accompanied by nitride and carbide has shown significant improvement. Good compatibility of Ti (C, N compound makes these composite suitable in various technical and industrial applications.Originality/value: It may be remarked that, the hardness obtained in this work is very encouraging and therefore, it is convenient to regard this as a privileged step taken in tool manufacturing aspect.

  2. Enhancement of bioactivity of pulsed magnetron sputtered TiC{sub x}N{sub y} with bioactive glass (BAG) incorporated polycaprolactone (PCL) composite scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Anusha Thampi, V.V.; Subramanian, B., E-mail: subramanianb3@gmail.com

    2015-11-15

    Titanium carbonitride (TiC{sub x}N{sub y}) thin films were fabricated on SS 316 L by pulsed reactive DC magnetron sputtering using titanium and graphite targets. The sputtered film was characterized microstructurally by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The XRD pattern revealed that the film was preferentially oriented along (200) axis with a grain size of 20 nm. A globular morphology was observed from electron micrograph while Energy dispersive X-ray spectroscopy (EDS) showed the compositional purity of the film. To improve the bioactivity, bioactive glass (BAG) nanopowders of size 60 nm, synthesized by sol–gel method, was incorporated into a polycaprolactone (PCL) scaffold (BAG-PCL), which was applied over TiC{sub x}N{sub y}/SS (BAG-PCL/TiCN/SS). In-vitro bioactivity studies of BAG-PCL showed the apatite formation, which was confirmed from fourier transform infrared (FTIR) spectrum and SEM. In-vitro corrosion studies in simulated body fluid (SBF) solution showed that the coated specimen had a higher charge transfer resistance than stainless steel (SS) bare. The enhancement of bioactivity was monitored by hemocompatibility and cytocompatibility, where an improved cell attachment and lower thrombus formation was observed for the coatings with BAG-PCL. - Highlights: • Fabrication of TiC{sub x}N{sub y} thin films on SS 316 L (TiCN/SS) by reactive pulsed DC magnetron sputtering. • Synthesis of BAG nanopowders (45S5) by sol–gel method. • Incorporation of BAG nanopowders into PCL matrix to form polymer composite scaffold. • BAG-PCL scaffold was coated on TiCN/SS to enhance the bioactivity.

  3. Effect of simulated thermal cycles on the microstructure of the heat-affected zone in HSLA-80 and HSLA-100 steel plates

    Science.gov (United States)

    Shome, M.; Gupta, O. P.; Mohanty, O. N.

    2004-03-01

    The influence of weld thermal simulation on the transformation kinetics and heat-affected zone (HAZ) microstructure of two high-strength low-alloy (HSLA) steels, HSLA-80 and HSLA-100, has been investigated. Heat inputs of 10 kJ/cm (fast cooling) and 40 kJ/cm (slow cooling) were used to generate single-pass thermal cycles with peak temperatures in the range of 750 °C to 1400 °C. The prior-austenite grain size is found to grow rapidly beyond 1100 °C in both the steels, primarily with the dissolution of niobium carbonitride (Nb(CN)) precipitates. Dilatation studies on HSLA-80 steel indicate transformation start temperatures (T s ) of 550 °C to 560 °C while cooling from a peak temperature (T p ) of 1000 °C. Transmission electron microscopy studies show here the presence of accicular ferrite in the HAZ. The T s value is lowered to 470 °C and below when cooled from a peak temperature of 1200 °C and beyond, with almost complete transformation to lath martensite. In HSLA-100 steel, the T s value for accicular ferrite is found to be 470 °C to 490 °C when cooled from a peak temperature of 1000 °C, but is lowered below 450 °C when cooled from 1200 °C and beyond, with correspondingly higher austenite grain sizes. The transformation kinetics appears to be relatively faster in the fine-grained austenite than in the coarse-grained austenite, where the niobium is in complete solid solution. A mixed microstructure consisting of accicular ferrite and lath martensite is observed for practically all HAZ treatments. The coarse-grained HAZ (CGHAZ) of HSLA-80 steel shows a higher volume fraction of lath martensite in the final microstructure and is harder than the CGHAZ of HSLA-100 steel.

  4. Microstructural development and mechanical properties of iron based cermets processed by pressureless and spark plasma sintering

    International Nuclear Information System (INIS)

    Highlights: ► Processing of Fe-based cermets by pressureless sintering and spark plasma sintering. ► Influence of carbon content on the sintering mechanism and hardness. ► The cermet phase diagram was calculated and permits to explain the microstructure. ► SPS provides ferritic matrix and different carbide distribution than CPS samples. ► Pressureless sintered samples contain retained austenite at room temperature. - Abstract: Iron-based cermets are an interesting class of metal-ceramic composites in which properties and the factors influencing them are to be explored. In this work the metal matrix contains Cr, W, Mo and V as alloying elements, and the hard phase is constituted by 50 vol% of titanium carbonitride (TiCN) particles. The work studies the influence of the C content and the processing method on the sinterability, microstructure and hardness of the developed cermet materials. For that purpose, cermet samples with different C content in the matrix (0 wt%, 0.25 wt%, 0.5 wt%, 1.0 wt%) were prepared by conventional pressureless sintering (CPS) and, in order to achieve finer microstructures and to reduce the sintering time, by spark plasma sintering (SPS). The density and hardness (HV30) of the processed materials was evaluated, while their phase composition and microstructure was characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The equilibrium phase diagram of the composite material was calculated by ThermoCalc software in order to elucidate the influence of the carbon content on the obtained phases and developed microstructures.

  5. Characterization of TiN, TiC and Ti(C,N) in titanium-alloyed ferritic chromium steels focusing on the significance of different particle morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Michelic, S.K., E-mail: susanne.michelic@unileoben.ac.at [Chair of Ferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Loder, D. [Chair of Ferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Reip, T.; Ardehali Barani, A. [Outokumpu Nirosta GmbH, Essener Straße 244, 44793 Bochum (Germany); Bernhard, C. [Chair of Ferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria)

    2015-02-15

    Titanium-alloyed ferritic chromium steels are a competitive option to classical austenitic stainless steels owing to their similar corrosion resistance. The addition of titanium significantly influences their final steel cleanliness. The present contribution focuses on the detailed metallographic characterization of titanium nitrides, titanium carbides and titanium carbonitrides with regard to their size, morphology and composition. The methods used are manual and automated Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy as well as optical microscopy. Additional thermodynamic calculations are performed to explain the precipitation procedure of the analyzed titanium nitrides. The analyses showed that homogeneous nucleation is decisive at an early process stage after the addition of titanium. Heterogeneous nucleation gets crucial with ongoing process time and essentially influences the final inclusion size of titanium nitrides. A detailed investigation of the nuclei for heterogeneous nucleation with automated Scanning Electron Microscopy proved to be difficult due to their small size. Manual Scanning Electron Microscopy and optical microscopy have to be applied. Furthermore, it was found that during solidification an additional layer around an existing titanium nitride can be formed which changes the final inclusion morphology significantly. These layers are also characterized in detail. Based on these different inclusion morphologies, in combination with thermodynamic results, tendencies regarding the formation and modification time of titanium containing inclusions in ferritic chromium steels are derived. - Graphical abstract: Display Omitted - Highlights: • The formation and modification of TiN in the steel 1.4520 was examined. • Heterogeneous nucleation essentially influences the final steel cleanliness. • In most cases heterogeneous nuclei in TiN inclusions are magnesium based. • Particle morphology provides important information

  6. Enhanced Sintering of TiNi Shape Memory Foams under Mg Vapor Atmosphere

    Science.gov (United States)

    Aydoğmuş, Tarik; Bor, Şakir

    2012-12-01

    TiNi alloy foams are promising candidates for biomaterials to be used as artificial orthopedic implant materials for bone replacement applications in biomedical sector. However, certain problems exist in their processing routes, such as formation of unwanted secondary intermetallic phases leading to brittleness and deterioration of shape memory and superelasticity characteristics; and the contamination during processing resulting in oxides and carbonitrides which affect mechanical properties negatively. Moreover, the eutectic reaction present in Ti-Ni binary system at 1391 K (1118 °C) prevents employment of higher sintering temperatures (and higher mechanical properties) even when equiatomic prealloyed powders are used because of Ni enrichment of TiNi matrix as a result of oxidation. It is essential to prevent oxidation of TiNi powders during processing for high-temperature (>1391 K i.e., 1118 °C) sintering practices. In the current study, magnesium powders were used as space holder material to produce TiNi foams with the porosities in the range of 40 to 65 pct. It has been found that magnesium prevents secondary phase formation and contamination. It also prevents liquid phase formation while enabling employment of higher sintering temperatures by two-step sintering processing: holding the sample at 1373 K (1100 °C) for 30 minutes, and subsequently sintering at temperatures higher than the eutectic temperature, 1391 K (1118 °C). By this procedure, magnesium may allow sintering up to temperatures close to the melting point of TiNi. TiNi foams produced with porosities in the range of 40 to 55 pct were found to be acceptable as implant materials in the light of their favorable mechanical properties.

  7. Origen y endurecimiento por dispersión de carbonitruros en un acero comercial microaleado al niobio y laminado en caliente

    Directory of Open Access Journals (Sweden)

    Valencia, E.

    1998-12-01

    Full Text Available Throughout this work, a study on niobium carbonitrides formation and its hardening effect in a commercial hot strip microalloyed steel is presented. Optic and electron micrographs were obtained while mechanical tests and indirect models allow to predict samples yield strength, taking into account the steel composition and its structural characteristics. The results showed an extended precipitation on austenite boundary cells during the last thermomechanical processing stages, which probably achieved a considerable contribution to the hardening by dispersion in the material studied. Otherwise, no evidence of precipitation in ferrite by means of transmission electron microscopy (TEM was observed. A poor interphase precipitation was detected in about 10 per cent of the total observed zones with no appreciated contribution to the steel hardness.

    Se presenta un estudio sobre el origen de los carbonitruros de niobio y su efecto en el endurecimiento de un acero comercial microaleado y laminado en caliente. Para tal fin se utilizaron micrografías ópticas y electrónicas; así como también ensayos mecánicos y modelos indirectos que permitieron predecir el límite elástico teniendo en cuenta la composición del acero y sus características estructurales. Los resultados mostraron una extensa precipitación en la austenita durante las últimas fases del proceso de laminación siendo ésta responsable del principal aporte al endurecimiento por dispersión en el material investigado. No hubo evidencias de precipitación en la ferrita por observaciones al microscopio electrónico de transmisión y sólo una escasa precipitación interfásica fue detectada en un 10 % de las zonas observadas sin una apreciable contribución al endurecimiento del acero.

  8. Calculation and experimental investigation of multi-component ceramic systems

    International Nuclear Information System (INIS)

    This work shows a way to combine thermodynamic calculations and experiments in order to get useful information on the constitution of metal/non-metal systems. Many data from literature are critically evaluated and used as a basis for experiments and calculations. The following multi-component systems are treated: 1. Multi-component systems of 'ceramic' materials with partially metallic bonding (carbides, nitrides, oxides, borides, carbonitrides, borocarbides, oxinitrides of the 4-8th transition group metals) 2. multi-component systems of non-metallic materials with dominant covalent bonding (SiC, Si3N4, SiB6, BN, Al4C3, Be2C) 3. multi-component systems of non-metallic materials with dominant heteropolar bonding (Al2O3, TiO2, BeO, SiO2, ZrO2). The interactions between 1. and 2., 2. and 3., 1. and 3. are also considered. The latest commercially available programmes for the calculation of thermodynamical equilibria and phase diagrams are evaluated and compared considering their facilities and limits. New phase diagrams are presented for many presently unknown multi-component systems; partly known systems are completed on the basis of selected thermodynamic data. The calculations are verified by experimental investigations (metallurgical and powder technology methods). Altogether 690 systems are evaluated, 126 are calculated for the first time and 52 systems are experimentally verified. New data for 60 ternary phases are elaborated by estimating the data limits for the Gibbs energy values. A synthesis of critical evaluation of literature, calculations and experiments leads to new important information about equilibria and reaction behaviour in multi-component systems. This information is necessary to develop new stable and metastable materials. (orig./MM)

  9. Corrosion of vanadium and V 3Ti 1Si in flowing lithium

    International Nuclear Information System (INIS)

    A pumped Li loop fabricated from a titanium stabilized Type 316 steel was designed and constructed. At temperatures of about 823 K, experiments over a duration of more than 7500 h were performed. A magnetic trap had to be incorporated just before the flowmeter to avoid the precipitation of magnetic particles. Therefore it was possible to investigate the influence of the magnetic trap on the corrosion behaviour of V in flowing Li. The results are as follows: - The corrosion rate of V is about 14 μm/year and independent of the nitrogen content of Li. The corrosion rate of V 3Ti 1Si depends on the N concentration of Li. At about 30 wppm N in Li a vanadium-titanium-nitride is formed at the surface of the specimens. Hence, a low rate of 4 μm/year can be stated. - Both materials pick-up more N than C from Li, pure vanadium double as much nitrogen as the alloy V 3Ti 1Si. - N diffuses into the bulk of both materials, whilst C is bound near the surface. The hardening at the surface is due to the up-take of N. - The vanadium-carbonitride-, respectively the vanadium-titanium-nitride-layers have a strong influence on the weight loss and the up-take of non-metals. - The magnetic trap reduces the weight loss of vanadium in a significant way. The positive influence of the magnetic trap is supposed to be due to the reduction of the nitrogen content of Li. - The corrosion rates of the alloy V 3Ti 1Si show, that the dissolution due to V loss does not affect the lifetime of the alloy. The comparison with steels and nickle-base-alloys demonstrates the advantages of this material. Nevertheless, the purification of the Li and the control of its nonmetal-levels is indispensable. (orig./HP)

  10. Effect of welding thermal cycles on the structure and properties of simulated heat-affected zone areas in X10CrMoVNb9-1 (T91) steel at a state after 100,000 h of operation

    Energy Technology Data Exchange (ETDEWEB)

    Łomozik, Mirosław, E-mail: miroslaw.lomozik@is.gliwice.pl [Instytut Spawalnictwa, Testing of Materials Weldability and Welded Constructions Department, 44-100 Gliwice, Bł. Czesława 16-18 (Poland); Hernas, Adam, E-mail: adam.hernas@polsl.pl [Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, 40-019 Katowice, Krasińskiego 8 str. (Poland); Zeman, Marian L., E-mail: marian.zeman@is.gliwice.pl [Instytut Spawalnictwa, Testing of Materials Weldability and Welded Constructions Department, 44-100 Gliwice, Bł. Czesława 16-18 (Poland)

    2015-06-18

    The article presents results of structural tests (light, scanning electron and scanning transmission electron microscopy) of X10CrMoVNb9-1 (T91) creep-resisting steel after approximately 100,000 h of operation. It was ascertained that the parent metal of T91 steel is characterized by the microstructure of tempered martensite with M{sub 23}C{sub 6} carbide precipitates and few dispersive precipitates of MX-type niobium and vanadium carbonitrides. The most inconvenient change in T91 steel precipitate morphology due to long-term operation is the appearance of the Laves Fe{sub 2}Mo phase which along with M{sub 23}C{sub 6} carbide particles forms elongated blocks and conglomerates on grain boundaries. The article also presents results of tests related to the effect of simulated welding thermal cycles on selected properties of X10CrMoVNb9-1 (T91) grade steel at a state after approximately 100,000 h of operation. The tests involved the determination of the chemical composition of the steel tested as well as impact tests, hardness measurements and microscopic metallographic examination (based on light microscopy) of simulated heat-affected zone (HAZ) areas for a cooling time (t{sub 8/5}) restricted within a range between 3 s and 120 s, with and without heat treatment. The tests revealed that, among other results, hardness values of simulated HAZ areas in X10CrMoVNb9-1 (T91) steel do not guarantee cold crack safety of the steel at the state without additional heat treatment. It was also observed that simulated welding thermal cycles of cooling times t{sub 8/5}=3, 12, 60 and 120 s do not significantly affect the toughness and hardness of simulated HAZ areas of the steel tested.

  11. Studies on Nb Microalloying of 13Cr Super Martensitic Stainless Steel

    Science.gov (United States)

    Ma, Xiaoping; Wang, Lijun; Subramanian, Sundaresa V.; Liu, Chunming

    2012-12-01

    The effect of Nb microalloying on microstructure, mechanical properties, and pitting corrosion properties of quenched and tempered 13 pct Cr-5 pct Ni-0.02 pct C martensitic stainless steels with different Mo and N contents was investigated. The microstructure, density, and dispersion of high-angle boundaries, nanoscale precipitates, and amount of retained austenite were characterized by using electron backscattered diffraction, transmission electron microscopy, and X-ray diffraction to correlate with properties. The results show that the combined effects of lowering nitrogen content in 13 pct Cr-5 pct Ni-1~2 pct Mo-0.02 pct C steels to 0.01 wt pct, and adding 0.1 pct Nb are to decrease the amount of Cr-rich precipitates, as Nb preferentially combines with residual carbon and nitrogen to form carbonitrides, suppressing the formation of Cr2N and Cr23C6. Austenite grain refinement can be achieved by Nb microalloying through proper heat treatment. If the nitrogen content is kept high, then Cr-rich precipitates would occur irrespective of microalloying addition. The NbN would also occur at high temperature, which will act as substrate for nucleation of coarse precipitates during subsequent tempering, impairing the toughness of the steel. It was shown that the addition of Nb to low interstitial super martensitic stainless steel retards the formation of reversed austenite and results in the formation of nanoscale precipitates (5 to 15 nm), which contribute to a significant increase in strength. More importantly, the pitting corrosion resistance was found to increase with Nb addition. This is attributed to suppression of Cr-rich precipitates, which can cause local depletion of Cr in the matrix and the initiation of pitting corrosion.

  12. Multilayer, hybrid PVD coatings on Ti6Al4V titanium alloy

    Directory of Open Access Journals (Sweden)

    W. Pawlak

    2009-12-01

    Full Text Available Purpose: The main purpose of this paper was to develop hybrid PVD technology of deposition wear resistant, multilayer coatings onto diffusion-hardened Ti6Al4V titanium alloy. Titanium and its alloys are desirable materials in modern constructions and vehicles. They have a high specific strength and very good corrosion resistance and biocompatibility. On the other hand, they have a low load-bearing capacity and poor tribological properties, as, for example, high friction coefficient, low resistance to adhesive and abrasive wear and tendency to galling. Development of multiplex coatings depositions techniques is vital for expanding of areas of titanium alloys usage.Design/methodology/approach: In the present work a new approach to coatings deposition onto diffusion hardened in glow discharge plasma (in Ar+O2 atmosphere Ti6Al4V titanium alloy was proposed by means of a hybrid PVD method including three coatings deposition methods: Reactive Magnetron Sputtering (RMS, Filtered Cathodic Arc Evaporation (FCAE and Pulsed Cathodic Arc Deposition (PCAD. The main aim of the work was to develop multilayer coatings combined of sublayers of titanium or chromium carbonitrides or of pure, hard carbon ones.Findings: It was concluded from the results of investigations that not every proposed multilayer structure ensure good frictional properties of Ti6Al4V alloy even when the coating posses very high hardness. The lowest value of wear and friction coefficient was determined for multilayer coating with (TiC/Cx3 structure.Research limitations/implications: Further research is necessary for a better understanding of the mechanisms of friction and wear as well as the origin of superhardness of particular multilayers.Practical implications: Multilayer coatings deposited by means of the hybrid PVD technique can be used for low friction and wear protection of titanium alloys.Originality/value: Originality value of this paper consists in use in one process of three

  13. Use of AWCC in evaluation of unknown fissile materials

    International Nuclear Information System (INIS)

    An important technological problem in the sphere of non-proliferation and safeguards is nondestructive analysis (NDA) methodology for qualitative and quantitative characterization of nuclear materials. Additionally, NDA tends to be labor and time intensive. Two NDA techniques used at KIPT included Gamma Spectroscopy (for qualitative analysis) and Neutron activation (for quantitative analysis). Gamma Spectroscopy was used to confirm the presence of radionuclides within the samples, whereas an Active Well Coincidence Counter (AWCC) in the active mode was used to quantitatively determine the 235U content in particular types of fissile materials at KIPT. This paper describes the usage of the AWCC at NSC KIPT for characterizing nuclear materials for IAEA safeguards. It was also an opportunity to estimate fissile materials of unknown composition. The equipment used was a model JCC-51 AWCC using a shift register model JSR-12 from Canberra and two neutron sources [AN-HP (241AmLi)]. A Compaq Presario computer using Windows version of NCC (Los Alamos software) was used to operate the AWCC. Materials studied in this project included highly enriched nuclear material in the form of powder, compacts (tablets, microspheres, rods), salt and scrap. The chemical composition of nuclear material included uranium metal, uranium dioxide, uranium nitride, uranium carbonitride, thorium dioxide, and mixtures of these compounds. New standards were used to recalibrate the AWCC using material obtained at KIPT with documented compositional values more similar to the materials to be measured, and in similar containers as well. During this study, the AWCC calibration curves were obtained for uranium metal and uranium dioxide with different enrichments up to 90 % for 235U. A broad spectrum of other fissile materials of unknown composition with differing enrichments has also been studied, and the items' isotopic and quantitative compositions have also been determined. Using the new calibration

  14. Application of kenaf byproduct for Flammulina velutiper cultivation%红麻副产物栽培金针菇技术研究

    Institute of Scientific and Technical Information of China (English)

    严理; 谢纯良; 朱作华; 李智敏; 胡镇修; 彭源德

    2013-01-01

    To find the new materials for Flammulina velutiper cultivation and to increase the economic benefits of kenaf cultivation,its byproduct was used in the test ofFlammulina velutiper cultivation in the study.The effect of moisture,pH,calcium salts,sugars and carbonitride on the Flammulina velutiper growth was measured by mycelial growth rate and biological efficiency.The optimal medium conditions of kenaf byproduct for eryngii cultivation were also determined.The results showed that the culture medium contained 50% kenaf byproduct,30 nitrogen source,67.5% moisture content,0.5% calcium carbonate,0.5% calcium oxide and 1% sucrose,pH value of 6.5,the biological efficiency of Flammulina velutiper could reached up to 111.0%.The variety screening results showed that 'Jinza 19' grew orderly,and its biological efficiency could reach morethan 106.7%.'Changbai 201' had a short growing cycle and good appearance,and its biological efficiency colud reach to 101.6%.This study demonstrated that the kenaf byproduct should be a good raw material for Flammulina velutiper cultivation.%为了寻找金针菇新的栽培原料,增加红麻种植的经济效益,进行红麻副产物栽培金针菇试验.通过测定不同营养条件下金针菇的菌丝生长速率和生物学效率,确定红麻副产物栽培金针菇的最佳配方.结果表明,红麻副产物培养基pH为6.5,培养基中含麻骨50%、氮源30%、水分67.5%,且添加0.5%石灰粉、0.5%碳酸钙和1%白糖时栽培金针菇的生物学效率最高,达111.0%;红麻骨培养基上的‘金杂19’出菇齐,生物学效率可达106.7%,‘长白201’出菇早,色泽好,生物学效率约为101.6%.

  15. Chemistry of Two-Dimensional Transition Metal Carbides (MXenes)

    Science.gov (United States)

    Mashtalir, Olha

    With consumer trends pushing toward smaller, faster, more flexible, multitasking devices, researchers striving to meet these needs have targeted two-dimensional (2D) materials---and graphene in particular---as holding the most promise for use in advanced applications. But in 2011, a significant interest has been triggered by a newly discovered family of novel 2D materials---layered transitional metal carbides and carbonitrides, named MXenes. Those compounds were of general formula Mn+1 XnTx, where M stands for metal atom, X is C and/or N, n = 1, 2 or 3, and Tx represents surface groups. Being initially suggested as a material for electrical energy storage systems, MXenes' properties and their potential applications have not been explored. This work is the first complete study of MXenes' chemistry that sheds light on the chemical composition, structure and properties of these novel materials and possible routes of its modification. The research was focused on 2D titanium carbide, Ti3C2Tx, chosen as the representative of the MXene family. The kinetic study of Ti 3C2Tx synthesis discovered the main synthesis parameters, viz. temperature, time and particle size, that affect the etching process and define the quality of final product. MXenes were found to be able to spontaneously accommodate various ions and small organic molecules between the layers leading to preopening of the structure. A major challenge of large scale production of delaminated, atomically thin 2D MXene layers was solved with two delamination techniques involving dimethyl sulfoxide and isopropyl amine pre-intercalation followed by sonication in water. Ti3C2Tx was also found to possess adsorptive and photocatalytic properties, revealing its potential for environmental applications. It also showed limited stability in water and in the presence of oxygen, providing important practical information on proper handling and storage of MXene materials. Completion of this work allowed the performance of energy

  16. Determination of the non-recrystallization temperature (TNR) in multiple microalloyed steels

    Science.gov (United States)

    Homsher, Caryn Nicole

    Rolling mill metallurgists must be able to easily and accurately determine critical temperatures such as the non-recrystallization temperature (T NR) to properly plan rolling schedules for desired properties. Microalloyed steels have small additions of alloying elements such as V, Ti, and Nb, to improve mechanical properties through grain size control and precipitation strengthening. The value of TNR is based on both alloying elements and deformation parameters. To easily predict TNR, equations have been developed and utilized in the literature and industry. However, each equation has certain limitations which constrain its applicability. This study was completed using ten laboratory grade low-carbon microalloyed steels designed to meet the API X-70 specification with varying amounts of V, Nb, and Ti. Double-hit deformation tests were conducted on a Gleeble® 3500 system in the standard pocket-jaw configuration at the Colorado School of Mines to determine experimental values of TNR. Double-hit deformation tests involve cylindrical specimens in an axisymmetric compression test. The test method requires six steps: 1) reheat to ensure most precipitates dissolve back into solution, 2) cool to deformation temperature, 3) compress with given strain and strain rate, 4) hold for interpass time, 5) deform specimen again holding everything else constant, and 6) measure the percent recrystallized or percent fractional softening. The TNR is the temperature where fractional softening is equal to 20 %. Niobium plays the largest role in influencing TNR. Complex niobium-vanadium-carbonitride precipitates are believed to play a significant role increasing TNR in the Hi-V alloy The experimental values of TNR were compared with predicted values of TNR from four equations in the literature. The Bai 2011 equation was the most reliable of the existing empirical formulas considered, while the commonly used Boratto equation was not accurate in predicting the TNR for the alloys in this

  17. Characterization of the corrosion behavior of an austenitic stainless steel for biomedical applications coated with Ti N, Ti CN And DLC PVD coatings

    International Nuclear Information System (INIS)

    Metallic biomaterials must present a combination of properties such as corrosion resistance, biocompatibility and mechanical resistance. Austenitic stainless steels, especially AISI 316L combine these properties with the easy of fabrication at low cost. However, they are prone to corrosion in physiological solutions. Furthermore, their corrosion products may lead to infectious ou allergenic reactions in the tissues around the implant device. In the present work, coatings produced by physical vapour deposition (PVD) methods have been applied on the surface of a 316L stainless steel to increase its corrosion resistance and biocompatibility. Three thin films were tested: titanium nitride (TiN), titanium carbonitride (TiCN) and diamond-like carbon (DLC). These materials present high hardness, wear resistance and intrinsic biocompatibility that are key features when considering biomedical applications. The characterization of the electrochemical behavior of the stainless steel coated with the three different films showed that the presence of surface defects are deleterious to the corrosion resistance of the substrate. These defects were observed using scanning electron microscopy. The evolution of the electrochemical behavior of the coated steel was explained through a mechanism based on the experimental results obtained using electrochemical impedance spectroscopy. Two different passivation treatments were carried out on the stainless steel surface, either in sulfuric or nitric acid solutions, to increase its corrosion resistance. The results suggested que these treatments were not efficient, but may be modified to improve its performance. The electronic properties of the passive films of the non-passivated and passivated stainless steel were studied using the Mott-Schottky approach. The films presented a duplex character. Below the flat band potential the behavior is typical of a highly doped type-p semiconductor. Above the flat band potential is typical of a highly

  18. Effect of V and Nb on the Microstructure and Creep Property of High Chromium (12%Cr) Ferritic Steel%V和Nb对12%Cr铁索体钢微观组织和蠕变特性的影响

    Institute of Scientific and Technical Information of China (English)

    沈喜训; 刘俊亮; 徐洲

    2012-01-01

    The effect of trace amounts of vanadium and niobium on the microstructure and the distribution and morphology of precipitates of 12%Cr ferritic heat resistant steel was studied by the optical microscopy (OM) and the transmission electron microscopy (TEM) equipped with energy dispersive X-ray spectroscopy (EDS). The testing results illuminated that the ferrite steel with V and Nb holds a narrow martensite lath structure. It is also found that the M23C6-type carbides combined with the MX-type carbonitrides, have fine small particle size and precipitate along all sorts of boundaries and in the δ-ferrite phase in the manner of acicular or clubbed shape while the M23C6-type carbides singly precipitated present a rectangle or ellipse shape with a relative larger particle size. The above optimized structure and the dispersed strengthening from MX-type carbinitrides itself restrain the recovery and recrystallization of tempered martensite structure, and thus improve the creep-resistant of ferrite steel.%利用光学显微镜和透射电子显微镜以及光电子能谱分析方法,研究了元素V和Nb对12%Cr铁素体耐热钢的微观组织和析出相的形态和分布的影响.结果表明:添加V和Nb的铁素体钢具有更窄的马氏体板条组织;附于MX型碳氮化物生长的M23C6碳化物呈细小的针状或短棒状析出,而单独析出的M23 C6尺寸较大,呈椭圆形.这些组织上的优化和MX型碳氮化物的弥散析出有效抑制了回火马氏体组织的回复和再结晶,提高了铁素体钢的蠕变抗力.

  19. The effects of small titanium additions on the mechanical properties and the microstructures of controlled rolled niobium-bearing HSLA plate steels

    Energy Technology Data Exchange (ETDEWEB)

    He Kejian (Univ. of Strathclyde, Glasgow (United Kingdom)); Baker, T.N. (Univ. of Strathclyde, Glasgow (United Kingdom))

    1993-09-15

    Effects of small Ti additions (0.010, 0.022%) on mechanical properties and microstructures of Nb-bearing HSLA plate steels under two different rolling schedules were investigated. For comparison, a Ti-free steel was controlled rolled to 814 C. A side effect of the Ti additions was observed on strength of Nb-bearing steels. The lower yield stress values and hardness levels for all Ti-Nb steels were reduced both in as-rolled and normalized conditions, depending on Ti/N ratio and details of thermomechanical process. However, the Ti-Nb steels with a lower finish rolling temperature (FRT), 800 C, showed better toughness than the Ti-free control steel. For Ti-Nb steels, toughness was improved significantly by lowering the FRT from 940 to 800 C, owing mainly to considerable refinement of ferrite grain sizes and fewer fine carbides available for dispersion hardening. No advantages were observed for over-stoichiometric Ti addition (Ti/N=4.4). The steel with under-stoichiometric Ti addition (Ti/N = 2) and a lower FRT (800 C) showed best overall mechanical and toughness properties among all processed Ti-Nb steels. Precipitation of Nb nitrides and carbides in the Nb steels was changed by Ti additions which led to formation of complex Ti-Nb nitrides and carbonitrides, i.e. Ti-rich plates and cuboids. Moreover, these plates and cuboids acted as nucleating cores on which pure carbides formed, i.e. Nb carbide in 0.01%Ti steels whereas Nb-rich Ti-Nb carbide in 0.022%Ti steels. In as-rolled samples, no Al was found in the complex particles or as individual AlN while in the normalized condition, fine AlN precipitates were detected frequently with understoichiometric titanium addition (0.01%Ti), whereas formation of AlN was suppressed by the over-stoichiometric Ti addition (in 0.022%Ti). The Ti/N ratio, therefore, has a strong influence on type of precipitation and size.

  20. Characterization of precipitates in the weld HAZ for a range of offshore steels

    Energy Technology Data Exchange (ETDEWEB)

    Weatherly. G.C.; Yin. Z.M.; Wolosiuk, M.

    1989-01-01

    A detailed study was made of the dissolution, precipitation and compositional changes associated with microalloying elements (Nb, V, Ti) in a series of HSLA steels. Both welds and Gleeble simulated samples were studied and compared at two heat inputs, 3 and 6 kJ/mm, for 4 steels, BS4360 and LT60, which are Nb and Nb-V grades, and 350 WT CAB and 350 WT STRAND, which are Nb-V-Ti containing steels. The behaviour of the Nb and Nb-V grades was dictated by the dissolution behaviour of the coarse Nb-rich particles found in the base plate of both steels. The Gleeble samples of the BS4360 steel showed nearly complete dissolution of the particles. The LT60 steel contained a coarser size distribution of Nb carbo-nitrides, and this resulted in a greater fraction of particles surviving the weld cycles in LT60 than BS4360. Reprecipitation effects were observed in the LT60 welds at the higher input but not in the Gleeble simulated samples. The Ti-Nb bearing steels showed more complex behaviour than the Nb, V-containing steels because the particle composition was dependent on the history of the steel and the particular thermal cycle. Mean Ti/Nb content of the particles increased after Gleeble thermal cycling and as the fusion line was approached, attributed to the Nb caps loss and formation of Ti-rich skins. In the Gleeble samples all the fine spheroidal particles dissolved after the thermal cycles, but reprecipitation effects were observed in the welds. The transformation products produced on cooling the Gleeble samples were studied by electron microscopy techniques. The formation of ferrite or bainite structures and the appearance of MA or carbides in the inter-ferrite regions was shown to be related to the C content and cooling rate of the weld. The MA phase was favoured at low C levels and faster cooling rates for a given steel. 9 refs., 29 figs., 3 tabs.

  1. 回火对微合金管线钢疲劳裂纹扩展行为的影响%Effects of tempering treatment on fatigue crack propagation behavior of microalloyed pipeline steels

    Institute of Scientific and Technical Information of China (English)

    李红英; 宾杰; 林武; 魏冬冬; 李阳华; 曹俊

    2011-01-01

    采用MTS858电液伺服万能试验机、扫描电镜及透射电镜研究回火对一种高强度微合金管线钢疲劳裂纹扩展行为的影响.研究结果表明:回火可提高微合金管线钢疲劳裂纹扩展的门槛值,降低疲劳裂纹扩展速率,但对裂纹扩展稳态区的扩展速率影响不大;回火使碳氮化物沉淀析出、晶间马氏体/奥氏体(M/A)组元由岛状转变为点状及细条状,形成马氏体薄膜结构,阻碍变形和裂纹在材料中扩展,增加裂纹的偏折程度;在控轧控冷终冷温度进行2~4 h回火热处理,可以提高微合金管线钢强韧性和抗疲劳裂纹扩展能力.%The effects of different tempering treatments on fatigue crack propagation behavior of a high strength microalloyed pipeline steel were investigated by MTS858 material testing system, scanning electron microscopy and transmission electron microscopy. The results show that tempering treatments can improve the fatigue crack propagation threshold and reduce the fatigue crack growth rate of microalloyed pipeline steels, but with little effects on the intermediate region of stable crack propagation. Tempering treatment can promote the precipitation of microalloyed carbonitrides and transform the martensite/austenite (M/A) components at the grain boundary from islands to spots and strips, and the M/A components can be further changed to thin-film martensite as tempering time increases, and all these structures can inhibit the propagation and increase the deflection of fatigue crack. The strength, toughness and fatigue crack propagation resistance of microalloyed pipeline steels can be promoted by 2-4 h tempering at the final cooling temperature of thertno-mechanical control process.

  2. Design of heat treatments for 9-12%Cr steels to optimise creep resistance for power plant applications

    Energy Technology Data Exchange (ETDEWEB)

    Morris, P.F.; Sachadel, U.A.; Clarke, P.D. [Tata Steel Europe, Rotherham (United Kingdom). Swinden Technology Centre; CRD and T, IJmuiden (Netherlands)

    2010-07-01

    Optimisation of the creep rupture properties of Steel 92 (9%Cr, 0.5%Mo, 2%W) by modification of heat treatment and C:N ratio has been studied. It was shown that a higher austenization temperature and double tempering at lower temperature can significantly extend creep life of the standard composition. The increase in austenization temperature from 1060 C and double tempering at 660 C/3h instead of single tempering at 780 C/2h resulted in the increase of stress rupture life from 1,734 to 6,179h at 650 C/110MPa. Even greater improvement in creep life was achieved by the combination of the modified heat treatment and decreased C:N ratio. In this case the creep life was extended to 10,255 h at 650 C/110MPa. A further increase in austenitization temperature to 1200 C for the decreased C:N ratio variant extended the rupture life to 17,118h. Initial results indicate that this modified heat treatment schedule does not result in notch brittle behaviour and most of the improvement in creep strength remains after a simulated post weld heat treatment at 740 C. The stress rupture programme is continuing and at 600 C test durations are approaching 60,000h. To explain the effect on rupture life thermodynamic calculations, microscopic investigations and a literature study were performed. Electron metallography investigations revealed that the lower tempering temperature resulted in a finer distribution of nano-size particles. Calculations show that increasing the austenitization temperature gave more dissolved B, N, C, Nb and V. The lower C:N ratio resulted in a higher atomic fraction of N in nano-size particles on subsequent tempering. Dissolved B should stabilize M{sub 23}M{sub 6} and dissolved N, C, Nv, and V should allow precipitation of a higher volume fraction of nano-size carbo-nitrides during tempering. Literature data suggest that lower tempering temperatures could also change their type from MX to M{sub 2}X. (orig.)

  3. Development of Advanced Wear and Corrosion Resistant Systems Through Laser Surface Alloying and Materials Simulations

    Energy Technology Data Exchange (ETDEWEB)

    R. P. Martukanitz and S. Babu

    2007-05-03

    precipitation of titanium carbonitrides during laser surface alloying provided there was sufficient amount of dissolved titanium, carbon, and nitrogen in the liquid steel. This was confirmed experimentally by using a powder mixture of 431-martensitic steel, titanium carbide powder, and nitrogen shielding, during laser deposition to produce deposits exhibiting relatively high hardness (average surface hardness of 724 HV). The same approach was extended to direct diode laser processing and similar microstructures were attained. The above analysis was extended to develop an in-situ precipitation of Ti(CN) during laser deposition. The Ti addition was achieving by mixing the 431 martensitic steel powders with ferro-titanium. The dissolution of nitrogen was achieved by using 100% nitrogen shielding gas, which was indicated by thermodynamic analysis. Demonstrations were also conducted utilizing the tools developed during the program and resulted in several viable composite coating systems being identified. This included the use of TiC and ferro-titanium in martensitic-grade stainless steel matrix material with and without the use of active N2 shielding gas, WC hard particles in a martensitic-grade stainless steel matrix material, WC and BN in a nickel-based matrix material, and WC in highly alloyed iron-based matrix. Although these demonstrations indicated the potential of forming composite coatings, in certain instances, the intended industrial applications involved unique requirements, such as coating of internal surfaces, which hindered the full development of the improved coating technology. However, it is believed that the addition of common hard particles, such as WC or TiC, to matrix material representing martensitic grades of stainless steel offer opportunities for improved performance at relatively low material cost.

  4. Z-phase in 9-12% Cr steels

    Energy Technology Data Exchange (ETDEWEB)

    Danielsen, Hilmar; Hald, John [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Manufacturing Engineering and Management

    2004-04-01

    Precipitation of the complex nitride Z-phase Cr(Nb,V)N has recently been identified as a major cause for premature breakdown in creep strength of a number of new 9-12%Cr martensitic steels. These steels are primarily used in steam pipes and steam turbines of thermal power plants. Z-phase precipitation cancels out the beneficial effects of MX carbo-nitrides rich in V and Nb, which form the backbone of the creep strength of 9-12%Cr steels. Very little is known about the stability of Z-phase, and there are currently no means of predicting its occurrence. The development of a thermodynamic model based on the Thermo-Calc software could provide means to predict in which steels the Z-phase will appear. Ultimately this could form the basis for development of new high strength 9-12%Cr martensitic steels that would be immune to Z-phase precipitation. This could hopefully increase service parameters of future power plants and thus raise efficiency. A literature survey of the Z-phase was made in order to gather all available information for a thermodynamic model, mainly chemical composition and solution temperature of the Z-phase as a function of steel composition are of importance. The survey did not give a complete overview of the Z-phase, so heat treatment experiments and metallographic investigations were carried out to fill the identified gaps. As the model neared completion it became clear that it predicted the Z-phase to be stable in basically all 9-12%Cr steels, that contain its constituents. This also applied to steels like the X20CrMoV121 (12CrMoV), which has been in service for decades and has shown no signs of a breakdown in strength. Close inspection of this steel after very long service exposure showed the Z-phase to be present in a new version (CrVN), albeit in much smaller quantities compared with the newer steels. This effectively makes Z-phase precipitation a kinetic problem, and if its precipitation is sufficiently slow it will not affect the stability of a

  5. 几种碳源对碳热还原氮化法制备Ti(C,N)粉末的影响%Influence of several carbon source on Ti(C,N)powders prepared by carbothermal reduction and nitridation method

    Institute of Scientific and Technical Information of China (English)

    余鹏飞; 叶金文; 刘颖; 何旭; 王杰; 杨嘉

    2011-01-01

    以纳米TiO2和不同碳源为原料,采用碳热还原氮化法,制备了Ti(C,N)粉末.通过X射线衍射分析、热分析、扫描电镜、化学成分分析等手段研究了TiO2碳热还原氮化过程的反应机理和不同碳源对制备碳氮化钛粉末的影响.结果表明,在TiO2碳热还原氮化过程中,前期主要为TiO2/C固-固反应,后期CO参与的气-固反应变为主要反应;当碳黑为碳源时,比之活性碳和石墨,反应最为完全,而且粉末产物粒度较为细小均匀;同时随着碳黑比表面积的增大,碳氮比随之降低,游离碳和氧含量随之减小;当以比表面积为600m2/g的碳黑为碳源时,配碳量为28.8%的混合物在加热到1700℃,保温3h,氮气流量为1000mL/min的条件下,得到了游离碳含量<0.2%、氧含量<0.5%,总碳为11.42%的碳氮化钛粉末.%Ti(C,N)powders can be prepared by carbothermal reduction and nitridation method with the nanometer TiO2 and different carbon source as starting materials. X-ray diffractometer,TG/DSC thermal analyzer, SEM and chemical analysis are applied to investigate the reaction mechanism on carbothermal reduction-nitridation of TiO2 and the effects of different cardon source on preparation of titanium carbonitride powders. The results show that,in the reaction process,the predominant reaction mechanism is TiO2/C solid-solid reaction in the beginning and subsequent the gas-solid reaction in which CO participates. The reaction of mixtures with carbon black as the carbon source is more complete than those with active carbon and graphite, and the former is finer than the latter two in the grains of reaction products. At the same time,with the specific surface area of carbon black increasing,the carbon/nitrogen ratio declines, and the free carbon content and oxygen content decrease.Moreover,if the mixtures with carbon black specific surface of 600m2/g as the carbon source and a carbon content of 28. 8% were isothermal treated for 3h at 1700℃ in an

  6. Synthesis of IV-VI Transition Metal Carbide and Nitride Nanoparticles Using a Reactive Mesoporous Template for Electrochemical Hydrogen Evolution Reaction

    KAUST Repository

    Alhajri, Nawal Saad

    2016-01-01

    content rather than nitride. In addition, the reactivity of the transition metals of group IV-VI with the reactive template was investigated under a flow of N2 at different temperatures in the range of 1023 to 1573 K while keeping the weight ratio constant at 1:1. The results show that Ti, V, Nb, Ta, and Cr reacted with mpg-C3N4 at 1023 K to form nitride phase with face centered cubic structure. The nitride phase destabilized at higher temperature ≥1223 K through the reaction with the remaining carbon residue originated from the decomposition of the template to form carbonitride and carbide phases. Whereas, Mo and W produce a hexagonal structure of carbide irrespective of the applying reaction temperature. The tendency to form transition metal nitrides and carbides at 1023 K was strongly driven by the free energy of formation. The observed trend indicates that the free energy of formation of nitride is relatively lower for group IV and V transition metals, whereas the carbide phase is thermodynamically more favorable for group VI, in particular for Mo and W. The thermal stability of nitride decreases at high temperature due to the evolution of nitrogen gas. The electrocatalytic activities of the produced nanoparticles were tested for hydrogen evolution reaction in acid media and the results demonstrated that molybdenum carbide nanoparticles exhibited the highest HER current with over potential of 100 mV vs. RHE, among the samples prepared in this study. This result is attributed to the sufficiently small particle size (8 nm on average) and accordingly high surface area (308 m2 g-1). Also, the graphitized carbon layer with a thickness of 1 nm on its surface formed by this synthesis provides excellent electron pathway to the catalyst which will improve the rate of electron transfer reaction.