Adhesive and tribocorrosive behavior of TiAlPtN/TiAlN/TiAl multilayers sputtered coatings over CoCrMo

Science.gov (United States)

Canto, C. E.; Andrade, E.; Rocha, M. F.; Alemón, B.; Flores, M.

2017-09-01

The tribocorrosion resistance and adherence of multilayer coatings of TiAlPtN/TiAlN/TiAl synthesized by PVD reactive magnetron sputtering over a CoCrMo alloy substrate in 10 periods of 30 min each were analyzed and compared to those of the substrate alone and to that of a TiAlPtN single layer coating of the same thickness. The objective of the present work was to create multilayers with different amounts of Pt in order to enhance the tribocorrosion resistance of a biomedical alloy of CoCrMo. Tribocorrosion tests were performed using Simulated Body Fluid (SBF) at typical body temperature with a tribometer in a pin on disk test. The elemental composition and thickness of the coating which behave better at the tribocorrosion tests were evaluated by means of RBS (Rutherford Backscattering Spectroscopy) IBA (Ion Beam Analysis) technique, using an alpha particles beam of 1.8 MeV, before and after the reciprocating motion in the tribocorrosion test. In order to simulate the elemental profile of the samples, the SIMNRA simulation computer code was used. Measurements of the adhesion of the coatings to the substrate were carried on by means of a scratch test using a tribometer. By taking micrographs of the produced tracks, the critical loads at which the coatings are fully separated from the substrate were determined. From these tests it was observed that a coating with 10 min of TiAlPtN in a TiAlPtN/TiAl period of 30 min in multilayers of 10 periods and with an average thickness of 145 nm for the TiAlPtN nanolayers had the best tribocorrosion resistance behavior, compared to that of the CoCrMo alloy. The RBS experiments showed a reduction of the thickness of the films along with some loss of the multilayer structure after the reciprocating motion. The adhesion tests indicated that the multilayer with the average TiAlPtN thickness of 145 nm displayed the highest critical load. These results indicate a high correlation between the adherence and the tribocorrosion behavior.

Creep-fatigue-environment interaction of 9Cr-1Mo-V-Nb steel

International Nuclear Information System (INIS)

Shibata, Hiroyuki; Ishikawa, Akiyoshi; Asada, Yasuhide

1996-01-01

An extension of the creep-fatigue damage model has been conducted in the present study. The original damage model has been developed to the predict the creep-fatigue life of 9Cr-1Mo-V-Nb steel (Modified 9Cr-1Mo steel) in a very high vacuum environment. The present study is to extend an applicability of the model to the creep-fatigue damage accumulation in the air environment. (orig.)

Multiaxial creep of fine grained 0.5Cr-0.5Mo-0.25V and coarse grained 1Cr-0.5Mo steels

International Nuclear Information System (INIS)

Browne, R.J.; Flewitt, P.E.J.; Lonsdale, D.

1991-01-01

To explore the multiaxial creep response of materials used for electrical power generating plant, two steels, a fine grained 0.5Cr-0.5Mo-0.25V steel in a normalised and tempered condition with high creep ductility and a coarse grained 1Cr-0.5Mo steel in a quenched and tempered condition with low uniaxial creep ductility, have been selected. A range of multiaxial stress testing techniques which span the stress states that would allow identification of any technique dependent variables has been used. The deformation and failure of the normalised and tempered 0.5Cr-0.5Mo-0.25V steel for a range of multiaxial test techniques and, therefore, stress states may be described by an equivalent stress criterion. The results from the multiaxial tests carried out on the fully bainitic 1Cr-0.5Mo steel show that the multiaxial stress rupture criterion (MSRC) varies with stress state; at high triaxiality (notch), it is controlled by the maximum principal stress, whereas at low triaxiality (shear) it is dependent on both maximum principal stress and equivalent stress. Furthermore, a simple description of stress state based on maximum principal and equivalent stress does not define this uniquely, since the MSRC derived from uniaxial and torsion testing does not describe the failure of notch, tube, or double shear tests. (author)

The research of axial corrosion fatigue on 10Ni3CrMoV steel

Science.gov (United States)

Xie, Xing; Yi, Hong; Xu, Jian; Xie, Kun

2017-09-01

Fatigue life had been studied with 10CrNi3MoV steel at different load ratios and in different environmental medias. The microstructure and micro-topography had been observed and analyzed by means of SEM, EDS and TEM. Our findings indicated that, the fatigue life of 10Ni3CrMoV steel in seawater was shorter than in air, the difference in longevity was larger with the decreasing of axis stress. Corrosion pits had a great influence on corrosion fatigue life.

Phase equilibria of the Mo-Al-Ho ternary system

Energy Technology Data Exchange (ETDEWEB)

Li, Yitai; Chen, Xiaoxian; Liu, Hao [Guangxi Univ., Nanning (China). College of Materials Science and Engineering; Guangxi Univ., Nanning (China). Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials; Zhan, Yongzhong [Guangxi Univ., Nanning (China). College of Materials Science and Engineering; Guangxi Univ., Nanning (China). Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials; Guangxi Univ., Nanning (China). Center of Ecological Collaborative Innovation for Aluminum Industry

2017-08-15

Investigation into the reactions and phase equilibria of transition metal elements (i.e. Mo, Zr, Cr, V and Ti), Al and rare earths is academically and industrially important for the development of both refractory alloys and lightweight high-temperature materials. In this work, the equilibria of the Mo-Al-Ho ternary system at 773 K have been determined by using X-ray powder diffraction and scanning electron microscopy equipped with energy dispersive X-ray analysis. A new ternary phase Al{sub 4}Mo{sub 2}Ho has been found and the other ternary phase Al{sub 43}Mo{sub 4}Ho{sub 6} is observed. Ten binary phases in the Al-Mo and Al-Ho systems, including Al{sub 17}Mo{sub 4} rather than Al{sub 4}Mo, have been determined to exist at 773 K. The homogeneity ranges of AlMo{sub 3} and Al{sub 8}Mo{sub 3} phase are 7.5 at.% and 1 at.%, respectively. According to the phase-disappearing method, the maximum solubility of Al in Mo is about 16 at.%.

Effect of Fe Content on the Microstructure and Mechanical Properties of Ti-Al-Mo-V-Cr-Fe Alloys

Directory of Open Access Journals (Sweden)

Bae K.C.

2017-06-01

Full Text Available To investigate the effect of Fe content on the correlation between the microstructure and mechanical properties in near-b titanium alloys, the Ti-5Al-5Mo-5V-1Cr-xFe alloy system has been characterized in this study. As the Fe content increased, the number of nucleation sites and the volume fraction of the α phase decreased. We observed a significant difference in the shape and size of the α phase in the matrix before and after Fe addition. In addition, these morphological deformations were accompanied by a change in the shape of the α phase, which became increasingly discontinuous, and changed into globular-type α phase in the matrix. These phenomena affected the microstructure and mechanical properties of Ti alloys. Specimen #2 exhibited a high ultimate tensile strength (1071 MPa, which decreased with further addition of Fe.

Analysis of High Temperature Deformed Structure and Dynamic Precipitation in W9Mo3Cr4V Steel

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

With TEM、SEM, various high-temperature deformed structures inW9Mo3Cr4V steel were investigated. The sub-structures，recrystallized nuclei, as well as the dynamic precipitation were also studied and analyzed. The relationship between recrystallized structures and dynamic precipitation was discussed. The results showed that the deformed structures in W9Mo3Cr4V steel are more complicated than those in low alloy steels. Because W9Mo3Cr4V steel is a high-speed steel, there are a large number of residual carbides on the matrix. Also, much dynamic precipitating carbides will precipitate during deformation at high temperature.

Growth (AlCrNbSiTiV)N thin films on the interrupted turning and properties using DCMS and HIPIMS system

Science.gov (United States)

Chang, Kai-Sheng; Chen, Kuan-Ta; Hsu, Chun-Yao; Hong, Po-Da

2018-05-01

This paper determines the optimal settings in the deposition parameters for (AlCrNbSiTiV)N high-entropy alloy (HEAs) nitride films that are deposited on CBN cutting tools and glass substrates. We use direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HIPIMS), with Ar plasma and N2 reactive gases. Experiments with the grey-Taguchi method are conducted to determine the effect of deposition parameters (deposition time, substrate DC bias, DC power and substrate temperature) on interrupted turning 50CrMo4 steel machining and the films' structural properties. Experimental result shows that the multiple performance characteristics for these (AlCrNbSiTiV)N HEAs film coatings can be improved using the grey-Taguchi method. As can be seen, the coated film is homogeneous, very compact and exhibits perfect adherence to the substrate. The distribution of elements is homogeneous through the depth of the (AlCrNbSiTiV)N film, as measured by an auger electron nanoscope. After interrupted turning with an (AlCrNbSiTiV)N film coated tool, we obtain much longer tool life than when using uncoated tools. The correlation of these results with microstructure analysis and tool life indicates that HIPIMS discharge induced a higher (AlCrNbSiTiV)N film density, a smoother surface structure and a higher hardness surface.

Phase equilibria in the Tl2MoO4–R2(MoO43–Zr(MoO42 (R = Al, Cr systems: synthesis, structure and properties of new triple molybdates Tl5RZr(MoO46 and TlRZr0.5(MoO43

Directory of Open Access Journals (Sweden)

V. G. Grossman

2017-12-01

Full Text Available The Tl2MoO4–R2(MoO43–Zr(MoO42 (R = Al, Cr systems were studied in the subsolidus region using X-ray powder diffraction and differential scanning calorimetric (DSC analysis. Quasi-binary joins were revealed, and triangulation was carried out. New ternary molybdates: Tl5RZr(MoO46 (5:1:2 and TlRZr0.5(MoO43 (1:1:1 (R = Al, Cr were prepared. The unit cell parameters for the new compounds were calculated.

The effects of microhardnesses and friction coefficients of GCr15 and Cr4Mo4V bearing materials by ion implantation

International Nuclear Information System (INIS)

Yang Qifa; Xiang Deguang; Lu Haolin

1988-01-01

Some experimental results of microhardnesses and friction coefficients of GCr15 and Cr4Mo4V bearing materials which were implanted with Cr, Mo, N and B ions are reported in this paper. It is found that the microhardnesses are increased and the friction coefficients are reduced by Cr, Mo, N and B ion implantation for two materials. The friction coefficients of Cr + Mo + N , Cr + Mo + B ion implanted samples are reduced to 1/3 of the unimplanted samples

Structural, morphological, and optical characterizations of Mo, CrN and Mo:CrN sputtered coatings for potential solar selective applications

Science.gov (United States)

Ibrahim, Khalil; Mahbubur Rahman, M.; Taha, Hatem; Mohammadpour, Ehsan; Zhou, Zhifeng; Yin, Chun-Yang; Nikoloski, Aleksandar; Jiang, Zhong-Tao

2018-05-01

Mo, CrN, and Mo:CrN sputtered coatings synthesized onto silicon Si(100) substrates were investigated as solar selective surfaces and their potential applications in optical devices. These coatings were characterized using XRD, SEM, UV-vis, and FTIR techniques. XRD investigation, showed a change in CrN thin film crystallite characteristic due to Mo doping. Compared to the CrN coating, the Mo:CrN film has a higher lattice parameter and lower grain size of 4.19 nm and 106.18 nm, respectively. FESEM morphology confirmed the decrement in Mo:CrN crystal size due to Mo doping. Optical analysis showed that in the visible range of the solar spectrum, the CrN coatings exhibit the highest solar absorptance of 66% while the lowest thermal emittance value of 5.67 was recorded for the CrN coating doped with Mo. Consequently, the highest solar selectivity of 9.6, and the energy band-gap of 2.88 eV were achieved with the Mo-doped CrN coatings. Various optical coefficients such as optical absorption coefficient, refractive index, extinction coefficient, real and imaginary parts of dielectric constants, and energy loss functions of these coatings were also estimated from the optical reflectance data recorded in the wavelength range of 190-2300 nm.

Comparative Effect of Mo and Cr on Microstructure and Mechanical Properties in NbV-Microalloyed Bainitic Steels

Directory of Open Access Journals (Sweden)

Andrii Kostryzhev

2018-02-01

Full Text Available Steel product markets require the rolled stock with further increasing mechanical properties and simultaneously decreasing price. The steel cost can be reduced via decreasing the microalloying elements contents, although this decrease may undermine the mechanical properties. Multi-element microalloying with minor additions is the route to optimise steel composition and keep the properties high. However, this requires deep understanding of mutual effects of elements on each other’s performance with respect to the development of microstructure and mechanical properties. This knowledge is insufficient at the moment. In the present work we investigate the microstructure and mechanical properties of bainitic steels microalloyed with Cr, Mo, Nb and V. Comparison of 0.2 wt. % Mo and Cr additions has shown a more pronounced effect of Mo on precipitation than on phase balance. Superior strength of the MoNbV-steel originated from the strong solid solution strengthening effect. Superior ductility of the CrNbV-steel corresponded to the more pronounced precipitation in this steel. Nature of these mechanisms is discussed.

Microstructural evolution in 13Cr-8Ni-2.5Mo-2Al martensitic precipitation-hardened stainless steel

International Nuclear Information System (INIS)

Ping, D.H.; Ohnuma, M.; Hirakawa, Y.; Kadoya, Y.; Hono, K.

2005-01-01

The microstructure of 13Cr-8Ni-2.5Mo-2Al martensitic precipitation-hardened (PH) stainless steel has been investigated using transmission electron microscopy, three-dimensional atom probe and small-angle X-ray scattering. A high number density (∼10 23-25 m -3 ) of ultra-fine (1-6 nm) β-NiAl precipitates are formed during aging at 450-620 deg. C, which are spherical in shape and dispersed uniformly with perfect coherency with the matrix. As the annealing temperature increases, the size and concentration of the precipitates increase concurrently while the number density decreases. The Mo and Cr segregation to the precipitate-matrix interface has been detected and is suggested to suppress precipitate coarsening. In the sample aged for 500 h at 450 deg. C, the matrix decomposes into Cr-rich (α') and Cr-poor (α) regions. The decrease in the strength at higher temperature (above 550 deg. C) is attributed to the formation of larger carbides and reverted austenite

Effect of laser absorption on picosecond laser ablation of Cr12MoV mold steel, 9Cr18 stainless steel and H13A cemented carbide

Science.gov (United States)

Wu, Baoye; Liu, Peng; Wang, Xizhao; Zhang, Fei; Deng, Leimin; Duan, Jun; Zeng, Xiaoyan

2018-05-01

Due to excellent properties, Cr12MoV mold steel, 9Cr18 stainless steel and H13A cemented carbide are widely used in industry. In this paper, the effect of absorption of laser light on ablation efficiency and roughness have been studied using a picosecond pulse Nd:YVO4 laser. The experimental results reveal that laser wavelength, original surface roughness and chemical composition play an important role in controlling ablation efficiency and roughness. Firstly, higher ablation efficiency with lower surface roughness is achieved on the ablation of 9Cr18 at 532, comparing with 1064 nm. Secondly, the ablation efficiency increases while the Ra of the ablated region decreases with the decrease of original surface roughness on ablation of Cr12MoV mold steel at 532 nm. Thirdly, the ablation efficiency of H13A cemented carbide is much higher than 9Cr18 stainless steel and Cr12MoV mold steel at 1064 nm. Scanning electron microscopy images reveals the formation of pores on the surface of 9Cr18 stainless steel and Cr12MoV mold steel at 532 nm while no pores are formed at 1064 nm. As to H13A cemented carbide, worm-like structure is formed at 1064 nm. The synergetic effects of the heat accumulation, plasma shielding and ablation threshold on laser ablation efficiency and machining quality were analyzed and discussed systematically in this paper.

Deuterium absorption property of Al/Zr-V/Mo multifilms

International Nuclear Information System (INIS)

Wang Haifeng; Peng Shuming; Zhang Xiaohong; Long Xinggui; Yang Benfu

2005-01-01

Deuterium absorption property of Al/Zr-V/Mo multifilms was studied experimentally to explore the effect of Al film. There is only one desorption peak at 320 degree C for Al film, two desorption peaks at 220 degree C and 350 degree C for Zr-V film. When the average thickness of Al film is less than 0.6 μm, the desorption property of Al/Zr-V multifilms is just as Zr-V film, when it is more than 0.6 μm, just as Al film. Deuterium absorption by Al/Zr-V multifilms decreases as the thickness of Al film increases until 0.7 μm, then the deuterium absorption no longer changes significantly. The Al film of multifilms cracks on desorbing, so the absorption rate varies as Zr-V film when the thickness of Al film is less than 0.6 μ. When the thickness of Al film is more than 0.6 μm, the deuterium absorption rate of multifilm does not change with the thickness of Al film. (author)

Mechanical behavior of 9Cr-1Mo-1V steel due to creep fatigue deformation

International Nuclear Information System (INIS)

Kim, Sang Tae; Kim, Jae Kyoung; Lee, Hak Sun; Oh, Sang Hyun; Kwun, Sook In; Kim, Chung Seok

2005-01-01

Creep-fatigue tests with trapezoid load wave were performed on a 9Cr-1Mo-1V steel at high temperature(550 .deg. C). Trapezoid load wave is considering about hold time for creep effects. we could find out some information in the relationship between number of cycles to failure and hold time. The number of cycles to failure depended on hold time. The cyclic behavior of 9Cr-1Mo-1V steel was characterized by cyclic softening with increasing number of cycles in high temperature. Also we could observe some cavity in the specimens. The size of cavity was different from each hold time

Structure and wear behavior of AlCrSiN-based coatings

Energy Technology Data Exchange (ETDEWEB)

Chen, Yun [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Chengdu Tool Research Institute Co., Ltd., Chengdu 610500 (China); Du, Hao [School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065 (China); Chen, Ming, E-mail: mchen@sjtu.edu.cn [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Yang, Jun [Chengdu Tool Research Institute Co., Ltd., Chengdu 610500 (China); Xiong, Ji [School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065 (China); Zhao, Haibo [The Analysis and Testing Centre, Sichuan University, Chengdu 610065 (China)

2016-05-01

Graphical abstract: - Highlights: • AlCrSiN based coating showed amorphous structure. • AlCrSiN/Me{sub x}N coatings obtained better wear resistance. • Molybdenum and niobium increased the coating hardness and wear resistance. - Abstract: AlCrN, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings have been deposited on high-polished WC–Co cemented carbide substrate and tools by mid-frequency magnetron sputtering in Ar/N{sub 2} mixtures. Al{sub 0.6}Cr{sub 0.4}, Al{sub 0.6}Cr{sub 0.3}Si{sub 0.1}, and C/Mo/Nb targets were used during the deposition. The microstructure and mechanical properties of as-deposited coatings were investigated. Investigations of the wear behaviors of coated tools were also performed. The results showed that cubic structure was formed in the coatings. Broader CrAlN (1 1 1) and (2 0 0) peaks without SiN{sub x} peak were formed in the AlCrSiN/Me{sub x}N coatings, which showed a nanocomposited structure. Meanwhile, according to SEM micrographs, AlCrN exhibited a columnar structure, while, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings showed nanocrystalline morphology. The nano-multilayered coatings performed higher hardness, H/E, and H{sup 3}/E{sup 2} ratios compared with AlCrN coating. Through the Rockwell adhesion test, all the coatings exhibited adhesion strength quality HF1. After turning Inconel 718 under dry condition, the nano-multilyered coatings showed better wear resistance than AlCrN coating. Due to the molybdenum and niobium in the coating, AlCrSiN/MoN and AlCrSiN/NbN coatings showed the best wear resistance.

Pressure Prediction of Electronic, Anisotropic Elastic, Optical, and Thermal Properties of Quaternary (M2/3Ti1/33AlC2 (M = Cr, Mo, and Ti

Directory of Open Access Journals (Sweden)

Liang Sun

2016-01-01

Full Text Available The electronic, mechanical, anisotropic elastic, optical, and thermal properties of quaternary (M2/3Ti1/33AlC2 (M = Cr, Mo, and Ti under different pressure are systematically investigated by first-principles calculations. The bonding characteristics of these compounds are the mixture of metallic and covalent bonds. With an increase of pressure, the heights of total density of states (TDOS for these compounds decrease at Fermi level. The highest volume compressibility among three compounds is Mo2TiAlC2 for its smallest relative volume decline. The relative bond lengths are decreasing when the pressure increases. The bulk and shear modulus of the one doped with Cr or Mo are larger than those of Ti3AlC2 with pressure increasing. With an increase of pressure, the anisotropy of these compounds also increases. Moreover, Mo2TiAlC2 has the biggest anisotropy among the three compounds. The results of optical functions indicate that the reflectivity of the three compounds is high in visible-ultraviolet region up to ~10.5 eV under ambient pressure and increasing constantly when under pressure. Mo2TiAlC2 has the highest loss function. The calculated sound velocity and Debye temperature show that they all increase with pressure. CV of the three compounds is also calculated.

IBA analysis and corrosion resistance of TiAlPtN/TiAlN/TiAl multilayer films deposited over a CoCrMo using magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Canto, C.E., E-mail: carloscanto2012@yahoo.com.mx [Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, 01000 México D.F. (Mexico); Andrade, E.; Lucio, O. de; Cruz, J.; Solís, C. [Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, 01000 México D.F. (Mexico); Rocha, M.F. [ESIME-Z, IPN, U.P. ALM, Gustavo A. Madero, C.P. 07738 México D.F. (Mexico); Alemón, B. [Departamento de Ingeniería de Proyectos, CUCEI, Universidad de Guadalajara, J. Guadalupe Zuno 48, Los Belenes, Zapopan, Jalisco 45101 (Mexico); Tecnológico de Monterrey, Av. General Ramón Corona 2514, Col. Nuevo México, Zapopan, Jalisco 45201 (Mexico); Flores, M. [Departamento de Ingeniería de Proyectos, CUCEI, Universidad de Guadalajara, J. Guadalupe Zuno 48, Los Belenes, Zapopan, Jalisco 45101 (Mexico); Huegel, J.C. [Tecnológico de Monterrey, Av. General Ramón Corona 2514, Col. Nuevo México, Zapopan, Jalisco 45201 (Mexico)

2016-03-15

The corrosion resistance and the elemental profile of multilayer coatings of TiAlPtN/TiAlN/TiAl synthesized by Physical Vapor Deposition (PVD) reactive magnetron sputtering over a CoCrMo alloy substrate in 10 periods of 30 min each were analyzed and compared to those of the substrate alone and to that of a TiAlPtN single layer coating of the same thickness. The objective of the present work was to create multilayers with different amounts of Pt to enhance the corrosion resistance of a biomedical alloy of CoCrMo. Corrosion tests were performed using Simulated Body Fluid (SBF) using potentiodynamic polarization tests at typical body temperature. The elemental composition and thickness of the coatings were evaluated with the combination of two ion beam analysis (IBA) techniques: a Rutherford Backscattering Spectroscopy (RBS) with alpha beam and a Nuclear Reaction Analysis with a deuteron beam.

IBA analysis and corrosion resistance of TiAlPtN/TiAlN/TiAl multilayer films deposited over a CoCrMo using magnetron sputtering

International Nuclear Information System (INIS)

Canto, C.E.; Andrade, E.; Lucio, O. de; Cruz, J.; Solís, C.; Rocha, M.F.; Alemón, B.; Flores, M.; Huegel, J.C.

2016-01-01

The corrosion resistance and the elemental profile of multilayer coatings of TiAlPtN/TiAlN/TiAl synthesized by Physical Vapor Deposition (PVD) reactive magnetron sputtering over a CoCrMo alloy substrate in 10 periods of 30 min each were analyzed and compared to those of the substrate alone and to that of a TiAlPtN single layer coating of the same thickness. The objective of the present work was to create multilayers with different amounts of Pt to enhance the corrosion resistance of a biomedical alloy of CoCrMo. Corrosion tests were performed using Simulated Body Fluid (SBF) using potentiodynamic polarization tests at typical body temperature. The elemental composition and thickness of the coatings were evaluated with the combination of two ion beam analysis (IBA) techniques: a Rutherford Backscattering Spectroscopy (RBS) with alpha beam and a Nuclear Reaction Analysis with a deuteron beam.

Fabrication of V-Cr-Ti-Y-Al-Si alloys by levitation melting

Energy Technology Data Exchange (ETDEWEB)

Chuto, Toshinori; Satou, Manabu; Abe, Katsunori [Department of Quantum Science and Energy Engineering, Tohoku University, Sendai, Miyagi (Japan); Nagasaka, Takuya; Muroga, Takeo [National Inst. for Fusion Science, Toki, Gifu (Japan); Shibayama, Tamaki [Center for Advanced Research of Energy Technology, Hokkaido University, Sapporo, Hokkaido (Japan); Tomiyama, Shigeki [Daido Bunseki Research Inc., Nagoya, Aichi (Japan); Sakata, Masafumi [Daido Steel Co. Ltd., Nagoya (Japan)

2000-09-01

Three allows of V-4Cr-4Ti type containing Si, Al and Y were fabricated by 2.5 kg scale levitation melting in this study. Workability and recrystallization behavior of the alloys were studied in order to establish the fabrication method of high-purity large ingot of V-Cr-Ti-Si-Al-Y type alloys, especially reducing interstitial impurity levels. Oxygen contents decreased with increasing yttrium contents and were kept below 180 mass ppm over wide region in the ingots. Nitrogen contents in the V-Cr-Ti-Y-Si-Al type alloys were only 100 mass ppm, which were as low as that in the starting materials. Only the V-4Cr-4Ti-0.1Y, Si, Al alloy could be cold-rolled at as-melted condition. Because large yttrium inclusions were observed in the alloys containing 0.5 mass%Y, it is necessary to optimize yttrium contents to avoid large inclusions and to obtain good workability. (author)

Fabrication of V-Cr-Ti-Y-Al-Si alloys by levitation melting

International Nuclear Information System (INIS)

Chuto, Toshinori; Satou, Manabu; Abe, Katsunori; Nagasaka, Takuya; Muroga, Takeo; Shibayama, Tamaki; Tomiyama, Shigeki; Sakata, Masafumi

2000-01-01

Three allows of V-4Cr-4Ti type containing Si, Al and Y were fabricated by 2.5 kg scale levitation melting in this study. Workability and recrystallization behavior of the alloys were studied in order to establish the fabrication method of high-purity large ingot of V-Cr-Ti-Si-Al-Y type alloys, especially reducing interstitial impurity levels. Oxygen contents decreased with increasing yttrium contents and were kept below 180 mass ppm over wide region in the ingots. Nitrogen contents in the V-Cr-Ti-Y-Si-Al type alloys were only 100 mass ppm, which were as low as that in the starting materials. Only the V-4Cr-4Ti-0.1Y, Si, Al alloy could be cold-rolled at as-melted condition. Because large yttrium inclusions were observed in the alloys containing 0.5 mass%Y, it is necessary to optimize yttrium contents to avoid large inclusions and to obtain good workability. (author)

Investigation of the structural and hydrogenation properties of disordered Ti-V-Cr-Mo BCC solid solutions

International Nuclear Information System (INIS)

Raufast, C.; Planté, D.; Miraglia, S.

2014-01-01

Highlights: • Materials synthesis and structural analysis of selected compositions of TiVCr(Mo) bcc samples. • Extraction of the thermodynamics relevant parameters for hydride formation and dissociation state of Ti 0.3 V 1.7 Cr 0.7 Mo 0.3 sample. • Discussion of the hydrides practicability. - Abstract: Selected compositions in the Ti-Cr-V-Mo system (with the BCC structure-type) have been synthesized and characterized for structural (crystalline structure, solidification microstructure) and thermodynamic properties (equilibrium and reversible hydrogen storage capacity). We present as well the effect of co-melting with a so-called activating phase that results in a secondary phase development and a subsequent enhancement of the hydrogen sorption kinetics. Ageing properties and applicability of such materials for hybrid hydrogen storage systems are also discussed

Study on Tribological Properties of CoCrMo Alloys against Metals and Ceramics as Bearing Materials for Artificial Cervical Disc

Science.gov (United States)

Xiang, Dingding; Song, Jian; Wang, Song; Liao, Zhenhua; Liu, Yuhong; Tyagi, Rajnesh; Liu, Weiqiang

2018-02-01

CoCrMo alloys are believed to be a kind of potential material for artificial cervical disc. However, the tribological properties of CoCrMo alloys against different metals and ceramics are not systematically studied. In this study, the tribological behaviors of CoCrMo alloys against metals (316L, Ti6Al4V) and ceramics (Si3N4, ZrO2) were focused under dry friction and 25 wt.% newborn calf serum (NCS)-lubricated conditions using a ball-on-disc apparatus under reciprocating motion. The microstructure, composition and hardness of CoCrMo alloys were characterized using x-ray diffraction, scanning electron microscopy (SEM) and hardness testers, respectively. The contact angles of the CoCrMo alloys with deionized water and 25 wt.% NCS were measured by the OCA contact angle measuring instrument. The maximum wear width, wear depth and wear volume were measured by three-dimensional white light interference. The morphology and the EDX analysis of the wear marks on CoCrMo alloys were examined by SEM to determine the basic mechanism of friction and wear. The dominant wear mechanism in dry friction for CoCrMo alloys against all pairings was severe abrasive wear, accompanied with a lot of material transfer. Under 25 wt.% NCS-lubricated condition, the wear mechanism for CoCrMo alloys against ceramics (Si3N4, ZrO2) was also mainly severe abrasive wear. However, severe abrasive wear and electrochemical corrosion occurred for the CoCrMo-316L pairing under lubrication. Severe abrasive wear, adhesive wear and electrochemical corrosion occurred for the CoCrMo-Ti6Al4V pairing under lubrication. According to the results, the tribological properties of CoCrMo alloys against ceramics were better than those against metals. The CoCrMo-ZrO2 pairing displayed the best tribological behaviors and could be taken as a potential candidate bearing material for artificial cervical disc.

Creep damage of 12% CrMoV weldments

International Nuclear Information System (INIS)

Kussmaul, K.; Maile, K.; Theofel, H.

1989-01-01

Creep tests were performed to determine the creep behaviour of similar welded joints of 12% CrMoV-steels which had been made using various heat inputs. The specimens were taken transverse to the seam. The transition from the coarse-grained to the fine-grained area of the heat affected zone (HAZ) proved to be the location of failure after longer rupture times. All tested specimens lie in the +-20% scatterband of the material standard DIN 17175. Creep rupture was initiated by the nucleation and growth of cavities. The appearance of the damage zone near the fracture face depends on testing conditions and heat input. The nucleation of cavities can be detected at an early stage of lifetime

Fatigue resistance of Cr-Ni-Mo-V steel

International Nuclear Information System (INIS)

Naumchenkov, N.E.; Filimonova, O.V.; Borisov, I.A.

1985-01-01

A study was made on the effect of additional alloying (Ni, Ni+Co), stress concentration, surface plastic strain on fatigue resistance of rotor steel of Cr-Ni-Mo-V-composition. It is shown that the steel with decreased carbon content possesses high complex of mechanical properties. Fatigue characteristics are not inferior to similar characteristics of steels of 25KhN3MFA type. Additional alloying of the steel containing 0.11...0.17% C and 4.5...4.7% N:, with niobium separately or niobium and cobalt in combination enabled to improve fatigue resistance of samles up to 25%. Strengthening of stress concentration zones by surface plastic strain is recommended for improving rotor suppporting 'nower under cyclic loading

Improvement of the corrosion property of Cr4Mo4V bearing steel using plasma immersion ion implantation

International Nuclear Information System (INIS)

Wang, S.Y.; Chu, P.K.

1997-01-01

The working conditions of aerospace bearings such as engine bearings are quite harsh and prolonging the life span of these components is thus very important to the aerospace industry. Previous results have shown that the main failure mechanism of aerospace bearings is corrosion, and enhancing their corrosion resistance is a key. Cr4Mo4V, which is equivalent to AISI M50 bearing steel, is usually used in aerospace bearings in China. In this study, Cr4Mo4V components are treated in a new generation plasma immersion ion implanter in which ion implantation and sputter deposition can be carried out in the same chamber without breaking vacuum. Three treatment processes involving Cr, Mo, and N are evaluated. Our test results indicate that Cr is the main element enhancing the corrosion resistance and the addition of nitrogen improves the properties further. The non line-of-sight advantage of PIII is important to the processing of complex-shaped samples such as engine bearings. (orig.)

Caracterización de los aceros sinterizados obtenidos a partir de polvos prealeados Fe-1,5% Mo

Directory of Open Access Journals (Sweden)

Torralba, J. M.

1995-02-01

Full Text Available Sintered molybdenum-, copper-, nickel- alloyed steels, have been studied through the influence of the Chemical composition on different mechanical and physical properties. In all the studied steels, a constant percentage of carbon has been used, as well Fe-Mo prealloyed powders, with a 1,5% Mo content. Selected sintering conditions were close to those used in the P/M industry, potential consumer of the studied steels.

Se estudian los aceros aleados sinterizados con molibdeno, cobre, níquel y grafito, a partir de la influencia de su composición sobre distintas propiedades mecánicas y físicas. En todos los aceros, se utilizó una composición de carbono constante, así como polvos prealeados de Fe-Mo, con 1,5% Mo. Las condiciones de sinterización elegidas han sido las más próximas a las utilizadas en la industria pulvimetalúrgica, que es el usuario potencial de los materiales estudiados.

Residual stresses in 2 1/4Cr1Mo welds

International Nuclear Information System (INIS)

Fidler, R.; Jerram, K.

1978-01-01

Two separate investigations, initiated in an attempt to explain the large amount of residual stress scatter previously observed in the weld metal of eighteen nominally identical thick-section 2 1/4Cr1Mo butt welds, are described in this paper. The first examined the detailed surface residual stress distributions in 2 1/4Cr1Mo manual arc circumferential butt welds in 80mm and 100mm thick 1/2Cr1/2Mo1/4V steam pipe. High residual stresses were found in the regions of overlap between adjacent weld beads, with low values in virgin weld metal. The second utilised single pass manual metal arc bead-in-groove welds to investigate the effects of preheat and weld metal composition on weld metal residual stresses. In four weld metals, mild steel, 1/2Cr1/2Mo1/4V, 1Cr1/2Mo, and 2 1/4Cr1Mo, the residual stresses were very similar, becoming less tensile (or more compressive) with increase of preheat, while the residual stresses in the fifth weld metal (12Cr) were significantly different, being compressive and less affected by preheat. In both investigations the effects have been described in terms of the basic metallurgical phenomena occurring in the weld metal. (author)

Type IIIa cracking at 2CrMo welds in 1/2CrMoV pipework

Energy Technology Data Exchange (ETDEWEB)

Brett, S J; Smith, P A [National Power plc, Swindon (United Kingdom)

1999-12-31

The most common form of in-service defect found today on the welds of National Power`s 1/2CrMoV pipework systems is Type IV cracking which occurs in intercritically transformed material at the edge of the heat affected zone. However an alternate form of cracking, termed IIIa, which occurs close to the weld fusion line in fully grain refined heat affected zones, has also been observed. The incidence of Type IIIa cracking has increased in recent years and these defects now constitute a significant part of the total recorded crack population. This presentation describes Type IIIa cracking and compares and contrasts it with the better documented Type IV cracking. Particular reference is made to the role of carbon diffusion at the weld fusion line in promoting Type IIIa damage in preference to Type IV. (orig.) 5 refs.

Type IIIa cracking at 2CrMo welds in 1/2CrMoV pipework

Energy Technology Data Exchange (ETDEWEB)

Brett, S.J.; Smith, P.A. [National Power plc, Swindon (United Kingdom)

1998-12-31

The most common form of in-service defect found today on the welds of National Power`s 1/2CrMoV pipework systems is Type IV cracking which occurs in intercritically transformed material at the edge of the heat affected zone. However an alternate form of cracking, termed IIIa, which occurs close to the weld fusion line in fully grain refined heat affected zones, has also been observed. The incidence of Type IIIa cracking has increased in recent years and these defects now constitute a significant part of the total recorded crack population. This presentation describes Type IIIa cracking and compares and contrasts it with the better documented Type IV cracking. Particular reference is made to the role of carbon diffusion at the weld fusion line in promoting Type IIIa damage in preference to Type IV. (orig.) 5 refs.

Resistencia a la oxidación de aleaciones Ni-Cr-Al plaqueadas por láser sobre aceros al carbono e inoxidables austeníticos

Directory of Open Access Journals (Sweden)

de Damborenea, J.

1995-04-01

Full Text Available Laser surface cladding has been carried out by means of a 5 kW CO₂ continuous wave laser on both a mild and a stainless steel. A powder injection technique has been used to deliver a Ni-Cr-Al alloy onto the steel molten pool. After processing, samples were analyzed by optical and scanning electron microscopy in order to know the microstructure and composition of present phases. High temperature corrosion resistance tests were done in an oxidant environment at temperatures of 950 °C. Phase transformations and corrosion behaviour are discussed. A general conclusion is the suitability of these alloys to bear oxidation due to the formation of protective oxide layers on their surface.

Se realiza un estudio sobre la obtención de recubrimientos de superficie mediante un láser continuo de CO₂ de 5 kW de potencia de salida. Mediante la técnica de inyección de partículas, se realizaron plaqueados en superficie de Ni-Cr-Al sobre un acero suave y otro inoxidable de tipo 316. Tras el procesado, se estudió la microestructura de las probetas obtenidas. Posteriormente, se procedió a su ensayo en atmósfera oxidante a 950 °C, observándose la evolución de la microestructura, la formación de las capas de óxido y la cinética del proceso. Como conclusión general, destaca, independientemente de la base sobre la que se obtienen los recubrimientos, la gran resistencia del material a la oxidación, seguramente debida a la formación de capas de alúmina que actúan como barreras frente al ataque del oxidante.

Quasi-static and dynamic forced shear deformation behaviors of Ti-5Mo-5V-8Cr-3Al alloy

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhiming; Chen, Zhiyong, E-mail: czysh@netease.com; Zhan, Congkun; Kuang, Lianjun; Shao, Jianbo; Wang, Renke; Liu, Chuming

2017-04-13

The mechanical behavior and microstructure characteristics of Ti-5Mo-5V-8Cr-3Al alloy were investigated with hat-shaped samples compressed under quasi-static and dynamic loading. Compared with the quasi-static loading, a higher shear stress peak and a shear instability stage were observed during the dynamic shear response. The results showed that an adiabatic shear band consisting of ultrafine equiaxed grains was only developed in the dynamic specimen, while a wider shear region was formed in the quasi-static specimen. The microhardness measurements revealed that shear region in the quasi-static specimen and adiabatic shear band in the dynamic specimen exhibited higher hardness than that of adjacent regions due to the strain hardening and grain refining, respectively. A stable orientation, in which the crystallographic {110} planes and <111> directions were respectively parallel to the shear plane and shear direction, developed in both specimens. And the microtexture of the adiabatic shear band was more well-defined than that of the shear region in the quasi-static specimen. Rotational dynamic recrystallization mechanism was suggested to explain the formation of ultrafine equiaxed grains within the adiabatic shear band by thermodynamic and kinetic calculations.

Precision casting of Ti-15V-3Cr-3Al-3Sn alloy setting

OpenAIRE

Nan Hai; Liu Changkui; Huang Dong

2008-01-01

In this research, Ti-15V-3Cr-3Al-3Sn alloy ingots were prepared using ceramic mold and centrifugal casting. The Ti-15V-3Cr-3Al-3Sn setting casting, for aeronautic engine, with 1.5 mm in thickness was manufactured. The alloy melting process, precision casting process, and problems in casting application were discussed. Effects of Hot Isostatic Pressing and heat treatment on the mechanical properties and microstructure of the Ti-15V-3Cr-3Al-3Sn alloy were studied.

Biospectroscopy for studying the influences of anti-diabetic metals (V, Cr, Mo, and W) to the insulin signaling pathway

Science.gov (United States)

Safitri, Anna; Levina, Aviva; Lee, Joonsup; Carter, Elizabeth A.; Lay, Peter A.

2017-03-01

The prevalence of diabetes, particularly with respect to type 2 diabetes, has reached epidemic proportions and continues to grow worldwide. One of the potential therapeutic targets in the treatment of type 2 diabetes involves the role of protein tyrosine phosphatases in the negative regulation of insulin signaling. The complexes of V(V/IV), Cr(III), W(VI), and Mo(VI), have all been proposed as possible drugs in the treatment of diabetes mellitus. Anti-diabetic activities of V(V/IV), Cr(III), Mo(VI), and W(VI) compounds are likely to be based on similar mechanisms, which involve phosphorylation/dephosphorylation reactions in the glucose uptake and metabolism. In order to clearly understand biological activities and phosphorylation/dephosphorylation reactions involved in anti-diabetic actions of Cr(III), V(V/IV), Mo(VI), and W(VI) complexes, the current research involves the use of cultured insulin-sensitive cells treated with these compounds. These reactions were investigated through vibrational spectroscopy. Protein phosphorylation/dephosphorylation induced conformational changes in secondary protein structure from α-helix to β-sheet, and these changes were detected by the IR spectra, which showed changes in the wavenumber and intensities of signals within the composite protein amide I band.

Microstructure and properties of Ti-Al intermetallic/Al2O3 layers produced on Ti6Al2Mo2Cr titanium alloy by PACVD method

Science.gov (United States)

Sitek, R.; Bolek, T.; Mizera, J.

2018-04-01

The paper presents investigation of microstructure and corrosion resistance of the multi-component surface layers built of intermetallic phases of the Ti-Al system and an outer Al2O3 ceramic sub-layer. The layers were produced on a two phase (α + β) Ti6Al2Mo2Cr titanium alloy using the PACVD method with the participation of trimethylaluminum vapors. The layers are characterized by a high surface hardness and good corrosion, better than that of these materials in the starting state. In order to find the correlation between their structure and properties, the layers were subjected to examinations using optical microscopy, X-ray diffraction analysis (XRD), surface analysis by XPS, scanning electron microscopy (SEM), and analyses of the chemical composition (EDS). The properties examined included: the corrosion resistance and the hydrogen absorptiveness. Moreover growth of the Al2O3 ceramic layer and its influence on the residual stress distribution was simulated using finite element method [FEM]. The results showed that the produced layer has amorphous-nano-crystalline structure, improved corrosion resistance and reduces the permeability of hydrogen as compared with the base material of Ti6Al2Mo2Cr -titanium alloy.

Stability, elastic properties and fracture toughness of Al0.75X0.75B14 (X=Sc, Ti, V, Cr, Y, Zr, Nb, Mo) investigated using ab initio calculations

International Nuclear Information System (INIS)

Emmerlich, Jens; Thieme, Niklas; To Baben, Moritz; Music, Denis; Schneider, Jochen M

2013-01-01

The effect of the transition metal valence electron concentration on the energy of formation, effective charge of B icosahedra, elastic properties, surface energy and fracture toughness was calculated using density functional theory for icosahedral transition metal borides of AlXB 14 (X=Sc, Ti, V, Cr, Y, Zr, Nb, Mo). Consistent with previous work on AlYB 14 (Kölpin et al 2009 J. Phys.: Condens. Matter 21 355006) it is shown that phase stability is generally dependent on the effective charge of the icosahedral transition metal borides. Also, ionization potential and electronegativity are identified as parameters affecting the effective charge of B icosahedra suitable for use in predicting the phase stability. Al 0.75 Y 0.75 B 14 , Al 0.75 Sc 0.75 B 14 and Al 0.75 Zr 0.75 B 14 have been identified as promising phases for application as protective coatings as they exhibit high phase stability and stiffness combined with a comparatively high fracture toughness. (paper)

Dynamic globularization of a-phase in Ti6Al4V alloy during hot compression

CSIR Research Space (South Africa)

Mutombo, K

2013-12-01

Full Text Available composition dependence of the martensite start temperature (Ms) has been done for Ti-Fe, Ti-Cr, Ti-Mo, Ti-V, Ti-Nb, Ti-Zr and Ti-Al alloys [1], [2]. The beneficial effect on the formation of hexagonal-structured martensite (α′) of Al, Mn, Cr, Sn and Fe... alloying elements, has been discussed by Lin et al [4]. However, the formation of the orthorhombic-structured martensite (α′′) which is favoured by elements such as Nb, Mo, Zr, W and V (strong β stabilizers) or H (a strong β stabilizer), has been reported...

Isothermal sections at 500 deg C of the Dy-V-Al and Dy-Cr-Al systems in the aluminium rich regions

International Nuclear Information System (INIS)

Rykhal', R.M.; Zarechnyuk, O.S.; Mats'kiv, O.P.

1979-01-01

X-ray diffraction and microscopic analyses have been used to investigate the ternary system dysprosium-vanadium-aluminium in the aluminium rich region. In the system Dy-V-Al two ternary compounds have been found: DyV 2 Al 20 (cubic structure, CeCr 2 Al 20 type, a=14.54 A and approximately DyVAl 8 (hexagonal crystal system, structure unknown, a=10.86, c=17.71 A, c/a=1.631). In the system dysprosium-chromium-aluminium three ternary compounds have been found: DyCr 2 Al 20 (cubic structure, CeCr 2 Al 20 type, a=14.39), approximately equal to DyCrAl 8 ) hexagonal crystal system, structure type unkown a=10.75, c=17.60 A, c/a=1.637) and DyCr 4 Al 8 (tetragonal structure, CeMn 4 Al 8 type, a=8.87, c=5.04 A, c/a=0.568). Isothermal sections of the systems Dy-V-Al and Dy-Cr-Al have been plotted at 500 deg C

Role of butter layer in low-cycle fatigue behavior of modified 9Cr and CrMoV dissimilar rotor welded joint

International Nuclear Information System (INIS)

Wu, Qingjun; Lu, Fenggui; Cui, Haichao; Liu, Xia; Wang, Peng; Tang, Xinhua

2014-01-01

Highlights: • Modified 9Cr–CrMoV dissimilar turbine rotor was successfully welded by NG-SAW. • LCF properties of both welded joints were approximate at smaller strain amplitude. • Tempered martensite with amounts of carbides in HAZ contributed to weakest zones. • Matched BL determined LCF properties of whole joint for dissimilar welded rotor. - Abstract: The present work aims at studying the role of butter layer (BL) in low-cycle fatigue (LCF) behavior of modified 9Cr steel and CrMoV steel dissimilar welded joint. The significant difference of the chemical composition of base metals (BMs) makes it a challenge to achieve sound welded joint. Therefore, buttering was considered to obtain a transition layer between the dissimilar steels. The LCF tests of two kinds of specimens without and with butter layer were performed applying strain-controlled cyclic load with different axial strain amplitudes. The test results indicated that the number of cycles at higher strain amplitudes of welded joint without butter layer was greatly higher than that of the joint with butter layer, while the fatigue lifetime to crack initiation (2N f ) became closer to each other at low and middle strain amplitudes. The failure was in the tempered heat affected zone (HAZ) at the CrMoV side for specimens without BL, while the fracture occurred at the tempered HAZ in the BL for specimens with BL. The microstructure details of BM, BL, HAZ and weld metals (WMs) were revealed by optical microscopy (OM). It was found that the tempered martensite was major microstructure for welded joint and much more carbides were observed in tempered HAZ than other parts due to the repeated tempering. Microhardness test indicated a softest zone existing tempered HAZ of BL and also there was a softer zone in tempered HAZ at the CrMoV side due to repeated tempering during welding and post weld heat treatment (PWHT). And scanning electron microscopy (SEM) was applied to observe the fractography. It was

EFECTO DEL PRECALENTAMIENTO Y LA SEVERIDAD DE TEMPLE SOBRE LA RESISTENCIA AL DESGASTE ADHESIVO DEL ACERO AUSTENÍTICO AL MANGANESO

Directory of Open Access Journals (Sweden)

OSCAR FABIÁN HIGUERA COBOS

2010-01-01

Full Text Available En este trabajo de investigación se estudió el efecto del precalentamiento y la severidad de temple sobre la resistencia al desgaste adhesivo del acero austenítico al manganeso ASTM A 128 grado C. El material se sometió a ciclos térmicos de temple y revenido con y sin precalentamiento con el fin de evaluar su influencia sobre la resistencia al desgaste. Posteriormente el material fue sometido a prueba según norma ASTM G83 y se determinó que el acero Austenítico al manganeso, es un material que presenta una microestructura metaestable en condiciones estables y no debe ser sometido a tratamiento térmico de revenido a altas temperaturas debido que favorece la descomposición de esta a ferrita (fase blanda de los acero y por ende disminuye su resistencia al desgaste.

Microscopical investigation of steamside oxide on X20CrMoV121 superheater tubes

DEFF Research Database (Denmark)

Montgomery, Melanie; Hansson, Anette Nørgaard; Jensen, Søren A.

2011-01-01

X20CrMoV121 is a 12%Cr martensitic steel which has been used in power plants in Europe for many decades. Superheater tubes exposed for various durations up to 135,000 hours in power plants in Denmark at steam temperatures varying from 450 to 575°C were investigated. Light optical and scanning ele...... electron microscopy was used to investigate steamside oxide morphologies. At all temperatures there is a double layered oxide, however, the inner:outer oxide thickness is not always equal. At the lower steam temperature range of...

Analysis of PTA hardfacing with CoCrWC and CoCrMoSi alloys

Directory of Open Access Journals (Sweden)

Adriano Scheid

2013-12-01

Full Text Available CoCrWC alloys are widely used to protect components that operate under wear and high temperature environments. Enhanced performance has been achieved with the CoCrMoSi alloys but processing this alloy system is still a challenge due to the presence of the brittle Laves phase, particularly when welding is involved. This work evaluated Plasma Transferred Arc coatings processed with the Co-based alloy CoMoCrSi - Tribaloy T400, reinforced with Laves phase, comparing its weldability to the CoCrWC - Stellite 6, reinforced with carbides. Coatings were also analyzed regarding the response to temperature exposure at 600°C for 7 days and subsequent effect on microstructure and sliding abrasive wear. Coatings characterization was carried out by light and scanning electron microscopy, X-ray diffraction and Vickers hardness. CoCrWC coatings exhibited a Cobalt solid solution dendritic microstructure and a thin interdendritic region with eutectic carbides, while CoCrMoSi deposits exhibit a large lamellar eutectic region of Laves phase and Cobalt solid solution and a small fraction of primary Laves phase. Although phase stability was observed by X-ray diffraction, coarsening of the microstructure occurred for both alloys. CoCrMoSi showed thicker lamellar Laves phase and CoCrWC coarser eutectic carbides. Coatings stability assessed by wear tests revealed that although the wear rate of the as-deposited CoCrMoSi alloy was lower than that of CoCrWC alloy its increase after temperature exposure was more significant, 22% against 15%. Results were discussed regarding the protection of industrial components in particular, bearings in 55AlZn hot dip galvanizing components.

Combined effect of rapid nitriding and plastic deformation on the surface strength, toughness and wear resistance of steel 38CrMoAlA

DEFF Research Database (Denmark)

Wang, B.; Lv, Z.A.; Zhou, Z.A.

2015-01-01

The combined treatment of pressurized gas nitriding and cold rolling is proposed as a new approach to rapid preparation of a strong and tough nitrided layer for steel 38CrMoAlA. The microstructural characteristics and properties of the modified surface layer in comparison with those of the conven......The combined treatment of pressurized gas nitriding and cold rolling is proposed as a new approach to rapid preparation of a strong and tough nitrided layer for steel 38CrMoAlA. The microstructural characteristics and properties of the modified surface layer in comparison with those...

Desarrollo de aceros reforzados con carburos primarios vía metalurgia líquida

Directory of Open Access Journals (Sweden)

Agote, I.

2005-12-01

Full Text Available The steel reinforcement by means of the addition of primary carbides via liquid metallurgy needs to fulfill two essential requirements to be technically viable: the development of a solid reinforcing product which is appropriate to be mixed with the steel and the optimization of the metallurgic addition of these reinforcing particles into the liquid steel. Besides, the improvement of the reinforced alloy characteristics is directly related to the particles' nature of reinforcing particles, their homogeneous and uniform distribution in the matrix and their size and morphology. The manufacture of these carbides by SHS ('Self propagating High temperature Synthesis' and their addition before steel is poured into moulds allows achieving the above-mentioned conditions.

Para que el reforzamiento de los aceros con carburos primarios vía metalurgia líquida sea técnicamente viable se requiere del desarrollo de un tipo de producto reforzante sólido, adecuado para su incorporación al acero, así como de la optimización de dicha vía metalúrgica de adición del producto reforzante al material base en estado líquido. Además, la mejora de características de la aleación reforzada es función directa de la naturaleza de las partículas, de su homogénea y uniforme distribución en la matriz y del tamaño y morfología regular de las mismas. Estas condiciones se consiguen cuando las partículas de carburo se elaboran previamente mediante la técnica SHS (selfpropagating high temperature synthesis y se añaden al baño de acero líquido previo a su colada en moldes o lingoteras.

Oxidation Behavior of TiAl-Based Alloy Modified by Double-Glow Plasma Surface Alloying with Cr-Mo

Science.gov (United States)

Wei, Xiangfei; Zhang, Pingze; Wang, Qiong; Wei, Dongbo; Chen, Xiaohu

2017-07-01

A Cr-Mo alloyed layer was prepared on a TiAl-based alloy using plasma surface alloying technique. The isothermal oxidation kinetics of the untreated and treated samples was examined at 850 °C. The microstructure and phase composition of the alloyed layer were analyzed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray powder diffraction (XRD). The morphology and constituent of the oxide scales were also analyzed. The results indicated that the oxidation resistance of TiAl was improved significantly after the alloying treatment. The oxide scale eventually became a mixture of Al2O3, Cr2O3 and TiO2. The oxide scale was dense and integrated throughout the oxidation process. The improvement was mainly owing to the enhancing of scale adhesion and the preferential oxidation of aluminum brought by the alloying effect for TiAl-based alloy.

Ab initio study of M2AlN (M = Ti,V,Cr)

International Nuclear Information System (INIS)

Sun, Zhimei; Music, Denis; Ahuja, Rajeev; Schneider, Jochen M

2005-01-01

We have studied M 2 AlN phases, where M = Ti, V, and Cr, by means of ab initio total energy calculations. The bulk modulus of M 2 AlN increases as Ti is replaced with V and Cr by 19.0% and 26.5%, respectively, which can be understood on the basis of the increased number of valence electrons filling the p-d hybridized bonding states. The bulk modulus of M 2 AlN is generally higher than that of the corresponding M 2 AlC phase, which may be explained by an extra electron in the former phases contributing to stronger chemical bonding. This work is important for fundamental understanding of elastic properties of these ternary nitrides and may inspire future experimental research. (letter to the editor)

The irradiation hardening of Ni-Mo-Cr and Ni-W-Cr alloy under Xe26+ ion irradiation

Science.gov (United States)

Chen, Huaican; Hai, Yang; Liu, Renduo; Jiang, Li; Ye, Xiang-xi; Li, Jianjian; Xue, Wandong; Wang, Wanxia; Tang, Ming; Yan, Long; Yin, Wen; Zhou, Xingtai

2018-04-01

The irradiation hardening of Ni-Mo-Cr and Ni-W-Cr alloy was investigated. 7 MeV Xe26+ ion irradiation was performed at room temperature and 650 °C with peak damage dose from 0.05 to 10 dpa. With the increase of damage dose, the hardness of Ni-Mo-Cr and Ni-W-Cr alloy increases, and reaches saturation at damage dose ≥1 dpa. Moreover, the damage dose dependence of hardness in both alloys can be described by the Makin and Minter's equation, where the effective critical volume of obstacles can be used to represent irradiation hardening resistance of the alloys. Our results also show that Ni-W-Cr alloy has better irradiation hardening resistance than Ni-Mo-Cr alloy. This is ascribed to the fact that the W, instead of Mo in the alloy, can suppress the formation of defects under ion irradiation.

Influence of boron vacancies on phase stability, bonding and structure of MB2 (M  =  Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W) with AlB2 type structure

International Nuclear Information System (INIS)

Dahlqvist, Martin; Rosen, Johanna; Jansson, Ulf

2015-01-01

Transition metal diborides in hexagonal AlB 2 type structure typically form stable MB 2 phases for group IV elements (M  =  Ti, Zr, Hf). For group V (M  =  V, Nb, Ta) and group VI (M  =  Cr, Mo, W) the stability is reduced and an alternative hexagonal rhombohedral MB 2 structure becomes more stable. In this work we investigate the effect of vacancies on the B-site in hexagonal MB 2 and its influence on the phase stability and the structure for TiB 2 , ZrB 2 , HfB 2 , VB 2 , NbB 2 , TaB 2 , CrB 2 , MoB 2 , and WB 2 using first-principles calculations. Selected phases are also analyzed with respect to electronic and bonding properties. We identify trends showing that MB 2 with M from group V and IV are stabilized when introducing B-vacancies, consistent with a decrease in the number of states at the Fermi level and by strengthening of the B–M interaction. The stabilization upon vacancy formation also increases when going from M in period 4 to period 6. For TiB 2 , ZrB 2 , and HfB 2 , introduction of B-vacancies have a destabilizing effect due to occupation of B–B antibonding orbitals close to the Fermi level and an increase in states at the Fermi level. (paper)

Effect of load ratio and saltwater corrosive environment on the initiation life of fatigue of 10Ni5CrMoV steel

Science.gov (United States)

Xie, Xing; Yi, Hong; Xu, Jian; Gen, Liming; Chen, Luyun

2017-09-01

Fatigue initiation life has been studied with 10CrNi5MoV steel for use in ocean engineering at different load ratios and in different environmental media. The microstructure and micro-topography have been observed and analyzed by means of SEM, EDS and EBSD. Our findings indicate that, the initiation life of 10Ni5CrMoV steel in seawater is shorter than that in air, and the difference in longevity is larger with the increasing of load ratio. Corrosion pits had a great influence on initial corrosion fatigue life.

Low-Cycle Fatigue Behavior of 10CrNi3MoV High Strength Steel and Its Undermatched Welds.

Science.gov (United States)

Song, Wei; Liu, Xuesong; Berto, Filippo; Razavi, S M J

2018-04-24

The use of high strength steel allows the design of lighter, more slender and simpler structures due to high strength and favorable ductility. Nevertheless, the increase of yield strength does not guarantee the corresponding improvement of fatigue resistance, which becomes a major concern for engineering structure design, especially for the welded joints. The paper presents a comparison of the low cycle fatigue behaviors between 10CrNi3MoV high strength steel and its undermatched weldments. Uniaxial tension tests, Push-pull, strain-controlled fatigue tests were conducted on base metal and weldments in the strain range of 0.2⁻1.2%. The monotonic and cyclic stress-strain curves, stress-life, strain-life and energy-life in terms of these materials were analyzed for fatigue assessment of materials discrepancy. The stress-life results of base metal and undermatched weld metal exhibit cyclic softening behaviors. Furthermore, the shapes of 10CrNi3MoV steel hysteresis loops show a satisfactory Masing-type behavior, while the weld metal shows a non-Masing type behavior. Strain, plastic and total strain energy density amplitudes against the number of reversals to failure results demonstrate that the undermatched weld metal presents a higher resistance to fatigue crack initiation than 10CrNi3MoV high strength steel. Finally, fatigue fracture surfaces of specimens were compared by scanning electron microscopy to identify the differences of crack initiation and the propagation between them.

Low-Cycle Fatigue Behavior of 10CrNi3MoV High Strength Steel and Its Undermatched Welds

Directory of Open Access Journals (Sweden)

Wei Song

2018-04-01

Full Text Available The use of high strength steel allows the design of lighter, more slender and simpler structures due to high strength and favorable ductility. Nevertheless, the increase of yield strength does not guarantee the corresponding improvement of fatigue resistance, which becomes a major concern for engineering structure design, especially for the welded joints. The paper presents a comparison of the low cycle fatigue behaviors between 10CrNi3MoV high strength steel and its undermatched weldments. Uniaxial tension tests, Push-pull, strain-controlled fatigue tests were conducted on base metal and weldments in the strain range of 0.2–1.2%. The monotonic and cyclic stress-strain curves, stress-life, strain-life and energy-life in terms of these materials were analyzed for fatigue assessment of materials discrepancy. The stress-life results of base metal and undermatched weld metal exhibit cyclic softening behaviors. Furthermore, the shapes of 10CrNi3MoV steel hysteresis loops show a satisfactory Masing-type behavior, while the weld metal shows a non-Masing type behavior. Strain, plastic and total strain energy density amplitudes against the number of reversals to failure results demonstrate that the undermatched weld metal presents a higher resistance to fatigue crack initiation than 10CrNi3MoV high strength steel. Finally, fatigue fracture surfaces of specimens were compared by scanning electron microscopy to identify the differences of crack initiation and the propagation between them.

Polymorphism in the Laves-phase precipitates of a quinternary Nb-Mo-Cr-Al-Si alloy

International Nuclear Information System (INIS)

Hu Yanling; Vasiliev, Alexandre; Zhang Lichun; Song, Kai; Aindow, Mark

2009-01-01

Transmission electron microscopy has been used to study the precipitates that develop in the A2 phase of an Nb-Mo-Cr-Al-Si alloy upon heat treatment. The precipitates include a Laves-phase that adopts the cubic C15 structure initially and the hexagonal C14 structure in the later stages of precipitation. The morphologies, orientation relationships and defect microstructures indicate that the metastable C15 phase arises due to tensile coherency stresses and that a synchroshear polymorphic transformation to the equilibrium C14 phase occurs as these relax

Análisis mecánico y tribológico de los recubrimientos fe-cr-ni-c y ni-al-mo

Directory of Open Access Journals (Sweden)

JORGE E. MUÑOZ

2007-01-01

Full Text Available En este trabajo de investigación se evaluaron dos recubrimientos aplicados por medio de la técnica de rociado térmico por combustión, la aleación: Ni=89%, Al = 5,5%, Mo=5,5% y la aleación Fe=81,8%, Cr=16%, Ni=2%, C=0,2. La preparación superficial de las probetas se realizó usando chorro de arena. Se realizaron pruebas de resistencia al cortante, adherencia, desgaste abrasivo, desgaste por deslizamiento y flexión en cuatro puntos. El recubrimiento Fe-Cr-Ni-C presentó menor pérdida de masa, tanto para desgaste abrasivo como para el desgaste por deslizamiento. La multicapa presentó una mayor porosidad en el recubrimiento Ni-Al- Mo usado como capa base y la capa exterior de Fe-Cr-Ni-C presentó mayor cantidad de partículas no fundidas y óxidos. La falla ocurrida en el ensayo de adherencia para las probetas con recubrimiento multicapa fue de característica adhesiva y cohesiva. El esfuerzo en el que se presenta la fisura por flexión en el recubrimiento multicapa disminuyó con el aumento del espesor

First-Principles Study on the Structural Stability and Segregation Behavior of γ-Fe/Cr2N Interface with Alloying Additives M (M = Mn, V, Ti, Mo, and Ni

Directory of Open Access Journals (Sweden)

Hui Huang

2016-07-01

Full Text Available This study investigated the structural stability and electrochemical properties of alloying additives M (M = Mn, V, Ti, Mo, or Ni at the γ-Fe(111/Cr2N(0001 interface by the first-principles method. Results indicated that V and Ti were easily segregated at the γ-Fe(111/Cr2N(0001 interface and enhanced interfacial adhesive strength. By contrast, Ni and Mo were difficult to segregate at the γ-Fe(111/Cr2N(0001 interface. Moreover, the results of the work function demonstrated that alloying additives Mn reduced local electrochemical corrosion behavior of the γ-Fe(111/Cr2N(0001 interface by cutting down Volta potential difference (VPD between clean γ-Fe(111 and Cr2N(0001, while alloying additives V, Ti, Mo, and Ni at the γ-Fe(111/Cr2N(0001 interface magnified VPD between clean γ-Fe(111 and Cr2N(0001, which were low-potential sites that usually serve as local attack initiation points.

In Situ Synthesis of γ-AlOOH and Synchronous Adsorption Separation of V(V) from Highly Concentrated Cr(VI) Multiplex Complex solutions

Energy Technology Data Exchange (ETDEWEB)

Zhang, Hailin [National; University of Chinese Academy of Sciences, No. 19A Yuquan Road, Shijingshan District,; Li, Ping [National; Wang, Zheming [Physcial; Zhang, Xin [Physcial; Zheng, Shili [National; Zhang, Yi [National

2017-07-13

Boehmite (γ-AlOOH) was synthesized to selectively adsorb V(V) from K₂CrO₄-KVO₃-H₂O solutions with highly concentrated Cr(VI) and low concentration V(V). The synthesized γ-AlOOH has a BET surface area of 433.2 m²/g and an average pore size of 3.5 nm. It possesses a maximum adsorption capacity of V(V) of 1.53 mmol/g from K₂CrO₄-KVO₃-H₂O solutions. The adsorption of V(V) onto γ-AlOOH follows the Langmuir isotherm model and pseudo-second-order kinetics equation by forming innersphere complexes while the Cr(VI) adsorption forms both inner-sphere and outer-sphere chromate complexes depending on solution pH. The γ-AlOOH was further synthesized in situ by adding HNO₃ into the K₂CrO₄-KAlO₂- KVO₃-H₂O solutions and then used for synchronous adsorption of V(V) and Cr(VI), resulting in increased adsorption capacity of V(V) of 2.88 mmol/g and decreased adsorption capacity of Cr(VI) to 0.073 mmol/g, respectively. In the latter process, adsorption pH values were adjustable, and adsorption reached equilibrium instantaneously, supporting a novel in situ synthesis and adsorption integration strategy with adjustable surface charge of adsorbent and disappearance of diffusion effect.

Selected characteristic of silumins with additives of Ni, Cu, Cr, Mo, W and V

Directory of Open Access Journals (Sweden)

S. Pietrowski

2010-04-01

Full Text Available The study, presents an investigation results of new grades of silumins containing of: 7,0÷17,0% Si, 4,0% Ni, 4,0% Cu and 0,5% Cr, Mo, W each as well as V. The influence tests were carried out of - antimony addition, strontium and phosphorus modification, supersaturation and ageing processes - on microstructure and silumins hardness. Revealed that investigated silumins, depending on the state, are characte-rized by hardness in the range of 80÷180 HB.

Tribological properties of anti-wear PVD coatings for elevated temperatures application deposited onto X37CrMoV5-1 type hot work steel

International Nuclear Information System (INIS)

Dobrzanski, L.A.; Polok, M.; Adamiak, M.

2003-01-01

The paper presents results of tribological and adhesion investigations of anti-wear PVD coatings TiN, TiN/(Ti,Al)N and CrN types deposited in ion plating PVD process onto X37CrMoV5-1 type hot work tool steel. It was found that damage mechanism during scratch test in all investigated coatings begins with multiple spallings located on the scratch edges followed by cracking and tool coatings delamination. Regarding to the coating types it can be seen different location of such damages and loads typical for them. According to this observations it can be stated that highest adhesion among investigated coating present, CrN monolayer coating and the lowest one multilayers Ti/(Ti,Al)N coating. The wear resistance was investigated by pin-on-disc method performed in room and elevated to 500 o C temperatures. It was found that the lowest wear in to fixed investigation conditions in both room and elevated temperatures shows TiN monolayer coating. Additionally one can see that TiN coatings application improve wear resistance some five times. (author)

Solidification Segregation and Homogenization Behavior of 1Cr-1.25Mo-0.25V Steel Ingot

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong-Bae [Dae-gu Mechatronics and Materials Institute, Daegu (Korea, Republic of); Na, Young-Sang; Seo, Seong-Moon [Korea Institute of Materials Science, Changwon (Korea, Republic of); Lee, Je-Hyun [Changwon National University, Changwon (Korea, Republic of)

2016-09-15

As a first step to optimizing the homogenization heat treatment following high temperature upset forging, the solidification segregation and the homogenization behaviors of solute elements were quantitatively analyzed for 1Cr-1.25Mo-0.25V steel ingot by electron probe micro-analysis (EPMA). The random sampling approach, which was designed to generate continuous compositional profiles of each solute element, was employed to clarify the segregation and homogenization behaviors. In addition, ingot castings of lab-scale and a 16-ton-sized 1Cr-1.25Mo-0.25V steel were simulated using the finite element method in three dimensions to understand the size effect of the ingot on the microsegregation and its reduction during the homogenization heat treatment. It was found that the microsegregation in a large-sized ingot was significantly reduced by the promotion of solid state diffusion due to the extremely low cooling rate. On the other hand, from the homogenization point of view, increasing the ingot size causes a dramatic increase in the dendrite arm spacing, and hence the homogenization of microsegregation in a large-sized ingot appears to be practically difficult.

Phase formation in Na2MoO4 - MgMoO4 - Cr2(MoO4)3 system

International Nuclear Information System (INIS)

Kotova, I.Yu.; Kozhevnikova, N.M.

1998-01-01

Interaction within Na 2 MoO 4 - MgMoO 4 - Cr 2 (MoO 4 ) 3 ternary system is studied by X ray phase and DTA methods. State diagram of NaCr(MoO 4 ) 2 - MgMoO 4 section is plotted. Production of ternary molybdates of Na 1-x Mg 1-x Cr 1+x (MoO 4 ) 3 , where 0 ≤ x ≤ 0.3, and NaMg 3 Cr(MoO 4 ) 5 composition is ascertained [ru

Effect of Cr, Ti, V, and Zr Micro-additions on Microstructure and Mechanical Properties of the Al-Si-Cu-Mg Cast Alloy

Science.gov (United States)

Shaha, S. K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D. L.

2016-05-01

Uniaxial static and cyclic tests were used to assess the role of Cr, Ti, V, and Zr additions on properties of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in as-cast and T6 heat-treated conditions. The microstructure of the as-cast alloy consisted of α-Al, eutectic Si, and Cu-, Mg-, and Fe-rich phases Al2.1Cu, Al8.5Si2.4Cu, Al5.2CuMg4Si5.1, and Al14Si7.1FeMg3.3. In addition, the micro-sized Cr/Zr/Ti/V-rich phases Al10.7SiTi3.6, Al6.7Si1.2TiZr1.8, Al21.4Si3.4Ti4.7VZr1.8, Al18.5Si7.3Cr2.6V, Al7.9Si8.5Cr6.8V4.1Ti, Al6.3Si23.2FeCr9.2V1.6Ti1.3, Al92.2Si16.7Fe7.6Cr8.3V1.8, and Al8.2Si30.1Fe1.6Cr18.8V3.3Ti2.9Zr were present. During solution treatment, Cu-rich phases were completely dissolved, while the eutectic silicon, Fe-, and Cr/Zr/Ti/V-rich intermetallics experienced only partial dissolution. Micro-additions of Cr, Zr, Ti, and V positively affected the alloy strength. The modified alloy in the T6 temper during uniaxial tensile tests exhibited yield strength of 289 MPa and ultimate tensile strength of 342 MPa, being significantly higher than that for the Al-Si-Cu-Mg base. Besides, the cyclic yield stress of the modified alloy in the T6 state increased by 23 pct over that of the base alloy. The fatigue life of the modified alloy was substantially longer than that of the base alloy tested using the same parameters. The role of Cr, Ti, V, and Zr containing phases in controlling the alloy fracture during static and cyclic loading is discussed.

Reheat cracking in 1/2 CrMoV steel. Heat affected zones

International Nuclear Information System (INIS)

Batte, A.D.; Miller, R.C.; Murphy, M.C.

1976-01-01

Low alloy creep resisting steels are inherently susceptible to cracking during stress relief heat treatment (reheat cracking) though few welds give rise to problems in manufacture or service. Mechanical tests on simulated affected zone structures in CrMoV forgings have shown that cracking occurs when the high temperature ductility is inadequate to accommodate the residual welding strain. Differences in susceptibility result from differences in heat affected zone grain size if the purity level is sufficiently high; reheat cracking may then be avoided by ensuring complete grain refinement during welding. The susceptibility of a lower purity forging was insensitive to grain size; heat affected zone refinement is unlikely to eliminate cracking in such steel. (orig.) [de

The creep-fatigue crack growth behaviour of a 1CrMoV rotor steel

International Nuclear Information System (INIS)

Priest, R.H.; Miller, D.A.; Gladwin, D.N.; Maguire, J.

1989-01-01

Crack growth rates under simultaneous creep-fatigue conditions have been quantified for a 1CrMoV rotor steel. Measured growth rates were partitioned into cyclic and hold period contributions and these characterized by the relevant fracture mechanics parameters K and C. Cyclic growth rates measured in the creep-fatigue tests were enhanced compared with pure fatigue rates. This observation is compared with the behaviour of other steels and explained by quantitative metallography. The resulting crack growth equation can be used during integrity assessments for plant components containing cracks which are subject to thermal fatigue

Liquidus projection of the Nb-Cr-Al system near the Al3(Nb,Cr) + Cr(Al,Nb) eutectic region

International Nuclear Information System (INIS)

Souza, S.A.; Ferrandini, P.L.; Nunes, C.A.; Coelho, A.A.; Caram, R.

2006-01-01

The system Nb-Cr-Al was investigated in the region near the Al 3 (Nb,Cr) + Cr(Al,Nb) eutectic and the liquidus projection of that region was determined based on the microstructural characterization of arc melted alloys. The characterization utilized scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential thermal analysis (DTA) and X-ray diffraction (XRD). The results allowed one to determine three primary solidification liquidus surfaces ((Cr,Al) 2 Nb, Cr(Al,Nb) and Al 3 (Nb,Cr)), that are originated from the binary systems Cr-Nb, Cr-Al and Al-Nb. It is proposed the occurrence of the invariant reaction L + (Cr,Al) 2 Nb ↔ Al 3 (Nb,Cr) + Cr(Al,Nb) and of a point of minimum, which involves a three phase reaction, L ↔ Al 3 (Nb,Cr) + Cr(Al,Nb). All alloys studied showed formation of the Al 3 (Nb,Cr) + Cr(Al,Nb) eutectic as the last solidification step with Al(Nb)Cr 2 precipitating from Cr(Al,Nb)

Creep Rupture Analysis and Life Estimation of 1.25Cr-0.5Mo, 2.25Cr-1Mo and Modified 9Cr-1Mo Steel: A Comparative Study

Science.gov (United States)

Roy, Prabir Kumar

2018-04-01

This paper highlights a comparative assessment of creep life of 1.25Cr-0.5Mo, 2.25Cr-1Mo and modified 9Cr-1Mo steels based on accelerated creep rupture tests. Creep rupture test data have been analysed and creep life of the above mentioned materials have been assessed using Larson Miller parameter at the stress levels of 60 and 42 MPa for different temperatures. Limiting steam temperatures for minimum design life of 105 h at 42 and 60 MPa for the above mentioned steels have also been calculated. Microstructural studies for the three above mentioned steels are also done.

Effects of Microalloying on the Microstructures and Mechanical Properties of Directionally Solidified Ni-33(at.%)Al-31Cr-3Mo Eutectic Alloys Investigated

Science.gov (United States)

Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

2002-01-01

Despite nickel aluminide (NiAl) alloys' attractive combination of oxidation and thermophysical properties, their development as replacements for superalloy airfoils in gas turbine engines has been largely limited by difficulties in developing alloys with an optimum combination of elevated-temperature creep resistance and room-temperature fracture toughness. Alternatively, research has focused on developing directionally solidified NiAl-based in situ eutectic composites composed of NiAl and (Cr,Mo) phases in order to obtain a desirable combination of properties a systematic investigation was undertaken at the NASA Glenn Research Center to examine the effects of small additions of 11 alloying elements (Co, Cu, Fe, Hf, Mn, Nb, Re, Si, Ta, Ti, and Zr) in amounts varying from 0.25 to 1.0 at.% on the elevated-temperature strength and room-temperature fracture toughness of directionally solidified Ni-33Al-31Cr-3Mo eutectic alloy. The alloys were grown at 12.7 mm/hr, where the unalloyed eutectic base alloy exhibited a planar eutectic microstructure. The different microstructures that formed because of these fifth-element additions are included in the table. The additions of these elements even in small amounts resulted in the formation of cellular microstructures, and in some cases, dendrites and third phases were observed. Most of these elemental additions did not improve either the elevated-temperature strength or the room-temperature fracture toughness over that of the base alloy. However, small improvements in the compression strength were observed between 1200 and 1400 K when 0.5 at.% Hf and 0.25 at.% Ti were added to the base alloy. The results of this study suggest that the microalloying of Ni-33Al-31Cr-3Mo will not significantly improve either its elevatedtemperature strength or its room-temperature fracture toughness. Thus, any improvements in these properties must be acquired by changing the processing conditions.

Welding repair of the steam and gas turbines rotors made of Cr-Mo-V steel

International Nuclear Information System (INIS)

Mazur, Z.; Kubiak, J.; Hernandez, A.

1999-01-01

An analysis of typical steam turbine and gas turbine rotor failures is carried out. On the base of the rotors different failure causes and their mode of occurring, an evaluation of the weldability of the Cr-Mo-V steels and the classification of the common turbine rotors repair possibilities is presented. The developing of specific in-situ welding repair process of the damaged 20.65 MW gas turbine rotor is described. After repair, the rotor was put back into service. (Author) 15 refs

Corrosion behavior of Ti6Al4V, CoCrMo alloy, and SS316L under different simulated body fluid environment

International Nuclear Information System (INIS)

Norsafikah Jamli; Nursyahirah Mohd Shah; Mohammed Rafiq Abdul Kadir

2007-01-01

full text: The corrosion behaviors of three different biomedical grade materials-Ti-6Al-4V, CoCrMo and SS316L- were studied in simulated human body environment. Three different simulated body fluids were used-the Hanks solution, MEM+Foetal Bovine Serum (MEM+FBS), and Phosphate Buffered Saline (PBS). Corrosion rates were determined by the Tafel extrapolation method. The corrosion rates of the three metals were comparable with higher rates found with MEM+FBS solution and lowest rates with PBS. Static immersion tests were also conducted, where the samples were kept for two weeks at pH values ranging from 5 to 9. This range of pH values was chosen to simulate the actual pH changes when these materials were inserted into human body. Spot analyses were then carried out using Field Emission Scanning Electron Microscope. The metals degrade with pitting corrosion with the diameter of pitting ranges from 1.44 μm to 1.88 μm. For all three SBF, ions from the solution were found to attach on the surface of the metal. Ion release tests were also performed and metal ion release. The overall results showed that different SBF has different effect on the corrosion behaviour of the three biomedical grade metals. with MEM+FBS showing significant effect on the metals. (author)

Structural relaxation and colour in the spinel-magnesiochromite (MgAl2O4-MgCr2O4) and gahnite-zincochromite (ZnAl2O4-ZnCr2O4) solid solution series

Science.gov (United States)

Hålenius, U.; Andreozzi, G. B.; Skogby, H.

2009-04-01

.5 %, respectively, is determined. Based on a Cr-O bond distance for the CrO6 polyhedron in magnesiochromite and zincochromite of 1.995 and 1.991 Å respectively (O'Neill and Dollase, 1994) and applying the ligand field relationship 10Dq?C×R-5 (R equals the M-O distance of the MO6-polyhedron), Cr-O bond distances in gahnite and spinel with Cr-contents at trace levels are determined to 1.959 and 1.969 Å, respectively. These M-O bond distances are considerably longer than the M-O distances determined for end member gahnite and spinel by XRD-methods (1.9137 and 1.9280 Å, respectively; O'Neill and Dollase, 1994) and shows that there is considerable structural relaxation of M-O bonds in the two present spinel series. The relaxation parameter, ɛ, determined from the optical absorption spectra is 0.59 and 0.63 for the ZnAl2-2xCr2xO4 and MgAl2-2xCr2xO4 and series, respectively. These values are lower than those suggested from X-ray absorption spectroscopy (Juhin et al. 2007), which may be explained by second nearest neighbour interactions. In contrast to what may be expected, the interelectronic repulsion parameter, B, for V ICr3+ decreases with increasing Cr-content and apparent Cr-O bond length in both of the present spinel series . This indicates that interactions between Cr-atoms in neighbouring octahedra become important at increasing Cr-content and result in more covalent Cr-O bonds. This in turn suppresses the energy of 4A2g -4T2g (4F) transition (and calculated 10Dq-values) in octahedrally coordinated Cr3+. Consequently, the values of structural relaxation parameters determined from the optical absorption spectra must be regarded as minimum numbers. Literature Juhin, A., Calas, G., Cabaret, D. and Galoisy, L. (2007): Structural relaxation around Cr3+ in MgAl2O4. Physical Review, B76, 054105. O'Neill, H.St.C. and Dollase, W.A. (1994): Crystal structures and cation distributions in simple spinels from powder XRD structure refinements: MgCr2O4, ZnCr2O4, Fe3O4 and the temperature

Tratamientos térmicos de los aceros sinterizados obtenidos a partir de polvos prealeados Fe-1,5% Mo

Directory of Open Access Journals (Sweden)

Torralba, J. M.

1995-04-01

Full Text Available The influence of several heat treatments on the mechanical and physical properties of three different sintered Ni-Cu-Mo alloyed steels are evaluated. The heat treatments carried out were quenching and tempering at different temperatures. The raw material studied was a Fe-Mo prealloyed powder with an 1.5% Mo content.

Se estudia la influencia que distintos estados de tratamiento térmico ejercen sobre las propiedades mecánicas y físicas de tres aceros aleados con cobre, níquel y molibdeno sinterizados. Los tratamientos térmicos realizados consisten en temple y revenido a distintas temperaturas. El material de partida utilizado para conseguir la aleación de molibdeno ha sido un polvo prealeado de Fe-1,5% Mo.

Structure and magnetic properties of NdFeB thin films with Cr, Mo, Nb, Ta, Ti, and V buffer layers

International Nuclear Information System (INIS)

Jiang, H.; O'Shea, M.J.

2000-01-01

Layers of NdFeB of the form A(20 nm)/NdFeB(d nm)/A(20 nm) where A represents Cr, Mo, Nb, Ta, Ti, V were prepared on a silicon substrate by magnetron sputtering. The purpose is to determine how (i) the chosen buffer layer and (ii) NdFeB layer thickness d (especially d 2 Fe 14 B with no preferred crystalline orientation. Our highest coercivities occur for buffer layer elements from row five of the periodic table, 20 kOe (1600 kA/m) in a Nb buffered sample with d of 180 nm and 17 kOe (1350 kA/m) in a Mo buffered sample with d of 180 nm. Buffer layers from row four (Ti, V, and Cr) and row six (Ta) all give lower coercivities. Our largest energy product, 10.3 MG-Oe (82 kJ/m 3 ), is obtained for the Mo buffered sample. Average Nd 2 Fe 14 B crystallite size for this sample is 27 nm. Only the Cr and Ti buffered films show a large coercivity (≥2 kOe) for d of 54 nm with the Cr films showing the highest coercivity, 2.7 kOe (215 kA/m). In films subjected to a rapid thermal anneal (anneal time 30 s) we find that both the coercivity and energy product are larger than in samples subjected to a 20 min anneal. In our Nb buffered systems we obtain coercivities as high as 26.3 kOe (2090 kA/m) after a rapid thermal anneal

Abrasive wear of BA1055 bronze with additives of Si, Cr, Mo and/or W

Directory of Open Access Journals (Sweden)

B. P. Pisarek

2008-10-01

Full Text Available Aluminium bronzes belong to the high-grade constructional materials applied on the put under strongly load pieces of machines, aboutgood sliding, resistant properties on corrosion both in the cast state how and after the thermal processing. It moves to them Cr and Si in the aim of the improvement of their usable proprieties. The additions Mo and/or W were not applied so far. It was worked out therefore the new kind of bronzes casting including these elements. Make additions to the Cu-Al-Fe-Ni bronze of Si, Cr, Mo and/or W in the rise of these properties makes possible. The investigations of the surface distribution of the concentration of elements in the microstructure of the studied bronze on X-ray microanalyzer were conducted. It results from conducted investigations, that in the aluminium bronze BA1055 after makes additions Si, Cr, Mo and/or W the phases of the type κFe, κNi crystallize, probably as complex silicides. Elements such as: Fe and Si dissolve first of all in phases κ, in smaller stage in the matrix of the bronze; Mn, Ni and W they dissolve in matrix and phases κ. It dissolves Cr and Mo in the larger stage in phases κ than in the matrix. The sizes of the abrasive wear were compared in the state cast multicomponentnew casting Cu-Al-Fe-Ni bronzes with the additives Cr, Mo or W with the wear of the bronze CuAl10Fe5Ni5Si. The investigations of thewear were conducted on the standard device. It results from conducted investigations, that make additions to bronze BA1055 of the additives of Si, Cr, Mo, and/or W it influences the rise of the hardness (HB of the bronze in the cast state, in the result of the enlarged quantity separates of hard phases κ, and in the consequence the decrease of the abrasive wear. The addition of molybdenum made possible obtainment of the microhardness of the phase α and γ 2 on the comparable level. From the microstructure of the bronze CuAl10Fe5Ni5MoSi is characterizes the smallest abrasive wear among

Quality of Metal Deposited Flux Cored Wire With the System Fe-C-Si-Mn-Cr-Mo-Ni-V-Co

Science.gov (United States)

Gusev, Aleksander I.; Kozyrev, Nikolay A.; Osetkovskiy, Ivan V.; Kryukov, Roman E.; Kozyreva, Olga A.

2017-10-01

Studied the effect of the introduction of vanadium and cobalt into the charge powder fused wire system Fe-C-Si-Mn-Cr-Ni-Mo-V, used in cladding assemblies and equipment parts and mechanisms operating under abrasive and abrasive shock loads. the cored wires samples were manufactured in the laboratory conditions and using appropriate powder materials and as a carbonfluoride contained material were used the dust from gas purification of aluminum production, with the following components composition, %: Al2O3 = 21-46.23; F = 18-27; Na2O = 8-15; K2O = 0.4-6; CaO = 0.7-2.3; Si2O = 0.5-2.48; Fe2O3 = 2.1-3.27; C = 12.5-30.2; MnO = 0.07-0.9; MgO = 0.06-0.9; S = 0.09-0.19; P = 0.1-0.18. Surfacing was produced on the St3 metal plates in 6 layers under the AN-26C flux by welding truck ASAW-1250. Cutting and preparation of samples for research had been implemented. The chemical composition and the hydrogen content of the weld metal were determined by modern methods. The hardness and abrasion rate of weld metal had been measured. Conducted metallographic studies of weld metal: estimated microstructure, grain size, contamination of oxide non-metallic inclusions. Metallographic studies showed that the microstructure of the surfaced layer by cored wire system Fe-C-Si-Mn-Cr-Mo-Ni-V-Co is uniform, thin dendrite branches are observed. The microstructure consists of martensite, which is formed inside the borders of the former austenite grain retained austenite present in small amounts in the form of separate islands, and thin layers of δ-ferrite, which is located on the borders of the former austenite grains. Carried out an assessment the effect of the chemical composition of the deposited metal on the hardness and wear and hydrogen content. In consequence of multivariate correlation analysis, it was determined dependence to the hardness of the deposited layer and the wear resistance of the mass fraction of the elements included in the flux-cored wires of the system Fe-C-Si-Mn-Cr-Mo-Ni-V

Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

NARCIS (Netherlands)

Bojack, A.; Zhao, L.; Morris, P.F.; Sietsma, J.

2016-01-01

The influence of austenitization treatment of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) on austenite formation during reheating and on the fraction of austenite retained after tempering treatment is measured and analyzed. The results show the formation of austenite in two

The relation between experiments and modeling of rapidly solidified 12Cr-Mo-V stainless steel

DEFF Research Database (Denmark)

Pryds, Nini; Hattel, Jesper Henri

1998-01-01

Solidification during melt spinning of a 12Cr-Mo-V stainless steel has been experimentally studied and numerically simulated. The resulting microstructures have been related to the unknown parameter h, i.e. the heat transfer coefficient between the substrate and the melt, by fitting the heat flow...... of metastable austenite as the primary phase near the chill side of the ribbon. Upon quenching to room temperature, this austenite transformed into martensite. At a distance of about 15 mu m from the chill surface, the growth velocity of the solid/liquid interface decreased (

Evaluation of the material in creep-exposed critical 12Cr-1Mo-V ferritic steel components of the pressure section of power plant steam boilers

International Nuclear Information System (INIS)

Dobrzanski, J.

2002-01-01

Metallographic examinations were carried out on ferritic 12Cr-1Mo-V steel with tempered martensite structure after 68,000 - 145,000 hr service in creep conditions. Structural evolution related to the form of martensite, carbide precipitation and internal damage due to long-term action of thermally activated processes was discussed. A generalised scheme of structural evolution and progress of the internal damage was developed in correlation with the life exhaustion ratio. Principles of the classification for ferritic 12Cr-1Mo-V steel after long-term-service were proposed together with the method for evolution of the state of the material for the industrial practice. (author)

Microstructure Of A SIC/(Ti/V/Cr/Sn/Al) Composite

Science.gov (United States)

Lerch, Bradley A.; Hull, David R.; Leonhardt, Todd A.

1990-01-01

NASA technical memorandum reports on analysis of composite material made of SiC fibers in matrix of 0.76 Ti/0.15 V/0.03 Cr/0.03 Sn/0.03 Al (parts by weight) alloy. Purposes of study to investigate suitability of some metallographic techniques for use on composite materials in general and to obtain information about macrostructure and microstructure of this specific composite to provide guidance for experimental and theoretical studies of more advanced composites.

Evaluation of dynamic fracture toughness of cold worked 9Cr-1Mo steel

International Nuclear Information System (INIS)

Sathyanarayanan, S.; Sasikala, G.; Ray, S.K.

2004-01-01

Dynamic J-R curves for cold worked 9Cr-1Mo steel have been estimated from instrumented impact test data at ambient temperature on pre-cracked Charpy specimens using three methods of analysis, namely those by Ray et al., Schindler, and Sreenivasan and Mannan. It is concluded that of these three, Schindler's method is the best suited for the purpose since it gives consistent variations with cold work of dynamic J-R curves and dynamic fracture toughness. Cold work results in substantial degradation in dynamic fracture toughness of 9Cr-1Mo steel

Microstructure and Room-Temperature Mechanical Properties of FeCrMoVTi x High-Entropy Alloys

Science.gov (United States)

Guo, Jun; Huang, Xuefei; Huang, Weigang

2017-07-01

FeCrMoVTi x ( x values represent the molar ratio, where x = 0, 0.5, 1.0, 1.5, and 2.0) high-entropy alloys were prepared by a vacuum arc melting method. The effects of Ti element on the microstructure and room-temperature mechanical properties of the as-cast FeCrMoVTi x alloys were investigated. The results show that the prepared alloys exhibited typical dendritic microstructure and the size of the microstructure became fine with increasing Ti content. The FeCrMoV alloy exhibited a single body-centered cubic structure (BCC1) and the alloys prepared with Ti element exhibited BCC1 + BCC2 mixed structure. The new BCC2 phase is considered as (Fe, Ti)-rich phase and was distributed in the dendrite region. With the increase of Ti content, the volume fraction of the BCC2 phase increased and its shape changed from a long strip to a network. For the FeCrMoV alloy, the fracture strength, plastic strain, and hardness reached as high as 2231 MPa, 28.2%, and 720 HV, respectively. The maximum hardness of 887 HV was obtained in the FeCrMoVTi alloy. However, the fracture strength, yield stress, and plastic strain of the alloys decreased continuously as Ti content increased. In the room-temperature compressive test, the alloys showed typical brittle fracture characteristics.

A method for nondestructive estimation of the fracture toughness of CrMoV rotor steels

International Nuclear Information System (INIS)

Viswanathan, R.; Gehl, S.

1990-01-01

Assessment of the remaining life of steam turbine rotors in the presence of bore defects requires a knowledge of the fracture toughness (K IC ) of the rotors. Current procedures for estimating the K IC involve two steps; as a first step, the fracture appearance transition temperature (FATT) at the critical location is determined; the FATT value is then used to estimate the K IC , based on published correlations between the excess temperature (T-FATT) and K IC . Some problems arise in implementing both of these steps. To determine the FATT of the material, large pieces of material have to be removed, machined into charpy specimens and tested; this procedure is often time consuming and expensive and sometimes not feasible. The excess temperature vs the K IC correlation that is used to derive the K IC values from the FATT data is based on a variety of low alloy steels and is therefore characterized by a large scatter band, thus leading to considerable uncertainty in the estimated K IC . In this work, FATT and K IC data reported for a number of retired CrMoV rotors were gathered and analyzed and correlations specific to CrMoV rotors were developed. Based on these correlations, a method for estimating K IC with greater accuracy, based on a knowledge of the steel chemistry alone, is proposed. The method offers the advantage that very small samples removed from noncritical locations in the rotor would be sufficient to get the desired data

Substitution of modified 9 Cr-1 Mo steel for austentic stainless steels

International Nuclear Information System (INIS)

Sikka, V.K.

1982-04-01

This report describes the current program to develop a high-strength ferritic-martensitic steel. The alloy is essentially Fe-9% Cr-1% Mo with small additions of V and Nb and is known as modifed 9 Cr-1 Mo steel. Its elevated-temperature properties and design allowable stresses match those of type 304 stainless steel for temperatures up to 600 0 C and exceed those of other ferritic steels by factors of 2 to 3. The improved strength of this alloy permits its use in place of stainless steels for many applications

Experimental study and modelling of high temperature creep flow and damage behaviour of 9Cr1Mo-NbV steel weldments

International Nuclear Information System (INIS)

Gaffard, V.

2004-12-01

Chromium martensitic stainless steels are under development since the 70's with the prospect of using them as structural components in thermal and nuclear power plants. The modified 9Cr1Mo-NbV steel is already used, especially in England and Japan, as a material for structural components in thermal power plants where welding is a commonly used joining technique. New generations of chromium martensitic stainless steels with improved mechanical properties for high pressure and temperature use are currently under development. However, observations of several in-service premature failures of welded components in 9Cr1Mo-NbV steel, outline a strong need for understanding the high temperature creep flow and damage behaviour of 9Cr1Mo-NbV steels and weldments. The present study aimed at experimentally determining and then modelling the high temperature creep flow and damage behaviour of both 9Cr1Mo-NbV steels and weldments (typically in the temperature range from 450 C to 650 C). The base metal was first studied as the reference material. It was especially evidenced that tempered chromium martensitic steels exhibit a change in both creep flow and damage behaviour for long term creep exposure. As a consequence, the classically performed extrapolation of 1,000 hours creep data to 100,000 hours creep lifetime predictions might be very hazardous. Based on experimental observations, a new model, integrating and coupling multiple creep flow and damage mechanisms, was developed in the framework of the mechanics of porous media. It was then successfully used to represent creep flow and damage behaviour of the base metal from high to low stress levels even for complex multiaxial loading conditions. Although the high temperature creep properties of the base metal are quite good, the occurrence of premature failure in weldments in high temperature creep conditions largely focused the attention of the scientific community. The lower creep strength of the weld component was also

Irradiation hardening of Mod.9Cr-1Mo steel

International Nuclear Information System (INIS)

Ryu, Woo-Seog; Kim, Sung-Ho; Choo, Kee-Nam; Kim, Do-Sik

2009-01-01

An irradiation test of Mod.9Cr-1Mo steel was carried out in the OR5 test hole of HANARO of a 30 MW thermal power at 390±10degC up to a fast neutron fluence of 4.4x10 19 (n/cm 2 ) (E > 1.0 MeV). The dpa of the irradiated specimens was evaluated to be 0.034 - 0.07. Tensile and impact tests of the irradiated Mod.9Cr-1Mo were done in the hot cell of the IMEF. The change of the tensile strength by irradiation was similar to the change of the yield strength. The increase of the yield and tensile strengths was up to 18% and 10% respectively. The elongation reduction of the weldment was up to 65%. (author)

Supersonic Plasma Spray Deposition of CoNiCrAlY Coatings on Ti-6Al-4V Alloy

Science.gov (United States)

Caliari, F. R.; Miranda, F. S.; Reis, D. A. P.; Essiptchouk, A. M.; Filho, G. P.

2017-06-01

Plasma spray is a versatile technology used for production of environmental and thermal barrier coatings, mainly in the aerospace, gas turbine, and automotive industries, with potential application in the renewable energy industry. New plasma spray technologies have been developed recently to produce high-quality coatings as an alternative to the costly low-pressure plasma-spray process. In this work, we studied the properties of as-sprayed CoNiCrAlY coatings deposited on Ti-6Al-4V substrate with smooth surface ( R a = 0.8 μm) by means of a plasma torch operating in supersonic regime at atmospheric pressure. The CoNiCrAlY coatings were evaluated in terms of their surface roughness, microstructure, instrumented indentation, and phase content. Static and dynamic depositions were investigated to examine their effect on coating characteristics. Results show that the substrate surface velocity has a major influence on the coating properties. The sprayed CoNiCrAlY coatings exhibit low roughness ( R a of 5.7 μm), low porosity (0.8%), excellent mechanical properties ( H it = 6.1 GPa, E it = 155 GPa), and elevated interface toughness (2.4 MPa m1/2).

Crystallization, microstructure and mechanical properties of silumins with micro-additions of Cr, Mo, W and V

Directory of Open Access Journals (Sweden)

S. Pietrowski

2010-01-01

Full Text Available In this paper results of the crystallization, microstructure and mechanical properties studies of hypo-, hyper- and eutectic silumins with addition of: Cr, Mo, W and V in amount of about 0,05% are presented. The influence of Sb, Sr and P together with Ti + B on the silumins crystallization process has been given. Results of: the microstructure, Rm, Rp0,2, A5 and HB testing of silumins after precipitation hardening and heat treatment in temperature of 560°C/3min and water chilling are presented.

Selected Properties And Tribological Wear Alloys Co-Cr-Mo And Co-Cr-Mo-W Used In Dental Prosthetics

Directory of Open Access Journals (Sweden)

Augustyn-Pieniążek J.

2015-09-01

Full Text Available The presented work provides the results of the abrasive wear resistance tests performed on Co-Cr-Mo and Co-Cr-Mo-W alloys with the use of the Miller’s apparatus. The analyzed alloys underwent microstructure observations as well as hardness measurements, and the abraded surfaces of the examined materials were observed by means of electron scanning microscopy. The performed examinations made it possible to state that the Co-Cr alloys characterized in a high hardness, whereas the changes in the mass decrement were minimal, which proved a high abrasive wear resistance.

Consideraciones teórico prácticas acerca de la soldadura de los aceros al carbono

Directory of Open Access Journals (Sweden)

Osmundo Héctor Rodríguez Pérez

2006-01-01

Full Text Available Se analizan los tres tipos de aceros al carbono y su clasificación desde el punto de vista de su soldabilidad. Se pueden observar los aspectos físico - químicos en la zona fundida, zona de transición y zona afectada por el calor. Existen varios aspectos en la tecnología de la soldadura de los aceros al carbono, tales como: preparación de los bordes, limpieza superficial, posición relativa de las piezas, precalentamiento, selección del material de aporte, deposición de los cordones, postcalentamiento, tratamiento térmico posterior y el control de la calidad de las uniones soldadas a tomar en cuenta para realizar la soldadura.

Influência do teor de Mo na microestrutura de ligas Fe-9Cr-xMo Effect of the content of molybdenum in the microstructure of Fe-9Cr-xMo alloy

Directory of Open Access Journals (Sweden)

Rodrigo Freitas Guimarães

2010-12-01

Full Text Available Aços Cr-Mo são usados na indústria do petróleo em aplicações com óleos crus ricos em compostos sulfurosos. Aços comerciais como 2.5Cr1Mo ou 9Cr1Mo têm se mostrado ineficientes em consequência de altos índices de corrosão naftênica. Uma estratégia para resolver este problema é o aumento do teor de molibdênio destes aços. Neste trabalho foi estudado o efeito do aumento do teor de molibdênio na microestrutura de ligas Fe-9Cr-xMo, solubilizadas e soldadas. Foram levantados os diagramas de fases com auxílio de um programa comercial para verificar as possíveis fases a serem formadas e identificar os problemas de soldagem. A microestrutura das ligas solubilizadas foi analisada por microscopia óptica e EBSD, além da medição da dureza. Foram realizadas soldagens autógenas para verificar o efeito do aporte térmico na microestrutura e na dureza das ligas. O aumento do teor de molibdênio resultou no aumento da dureza das ligas. A análise microestrutural das ligas soldadas apresentou uma particularidade para a liga com menor teor de molibdênio, a presença de martensita. Já as ligas com maior teor de molibdênio apresentaram uma microestrutura completamente ferrítica. A formação de martensita pode ser um problema na solda da liga com menor teor de molibdênio, uma vez que a mesma pode causar perdas nas propriedades mecânicas comprometendo sua aplicação.Cr-Mo steels are used in the petroleum industry in applications with crude oils rich in sulfur compounds. 2.5Cr1Mo or 9Cr1Mo do not resist to operating conditions when in contact with crude oils. The increasing of molybdenum content can improve the corrosion resistance of these alloys. This paper studied the effect of increased concentration of molybdenum in the microstructure of Fe-9Cr-xMo alloys, annealed and welded. Phase diagrams were built with the aid of commercial program to check the possible phases to be formed and to identify the problems of welding. Analyses were

Influence of chemical composition in crystallographic texture Fe-Cr-Mo alloys; Influencia da composicao quimica na textura cristalografica de ligas Fe-Cr-Mo

Energy Technology Data Exchange (ETDEWEB)

Moura, L.B.; Guimaraes, R.F. [Instituto Federal de Educacao, Ciencia e Tecnologia do Ceara, Fortaleza, CE (Brazil). Dept. da Industria; Abreu, H.F.G. [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil)

2010-07-01

The use of steels with higher contents of Mo in the oil industry has been an alternative to reduce the effect of naphthenic corrosion in refining units. The addition of Mo in Fe-Cr alloys in the same manner that increases resistance to corrosion naphthenic causes some difficulties such as difficulty of forming, welding and embrittlement. In this work, experimental ingots of Fe-Cr-Mo alloys (Cr - 9, 15 and 17%, Mo - 5, 7 and 9%) were melted in vacuum induction furnace and hot and cold rolled in a laboratory rolling mill. The influence of chemical composition on crystallographic texture of samples subjected to the same thermo-mechanical treatment was analyzed by x-ray diffraction. The results indicate that fiber (111) becomes more intense with increasing Mo and/or Cr contents. (author)

Study of the 1.25Cr-1Mo-0.25V steel microstructure after a carburization phenomenon

Energy Technology Data Exchange (ETDEWEB)

Simonetti, S., E-mail: ssimonet@uns.edu.ar [Departamento de Fisica, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahia Blanca (Argentina); Departamentos de Ciencias Basicas e Ingenieria Mecanica, Universidad Tecnologica Nacional, 11 de Abril 461, 8000 Bahia Blanca (Argentina); Lanz, C. [Departamento de Ingenieria, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahia Blanca (Argentina); Brizuela, G.; Juan, A. [Departamento de Fisica, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahia Blanca (Argentina)

2010-08-20

We studied the changes in the structure and carbide particle size in 1.25Cr-1Mo-0.25V steel under 600 deg. C and 168 MPa, after 4000 h service. We used microscopy and microanalysis techniques to analyze the carbide particles. We performed a complementary theoretical study on the chemical bonding and electronic structure of the carbide-Fe matrix interaction. The results contribute to the understanding of the changes in the alloy microstructure caused by the carburization phenomenon.

Patterned CoCrMo and Al2 O3 surfaces for reduced free wear debris in artificial joint arthroplasty.

Science.gov (United States)

Tarabolsi, Mohamad; Klassen, Thomas; Mantwill, Frank; Gärtner, Frank; Siegel, Frank; Schulz, Arndt-Peter

2013-12-01

Surface wear of corresponding tribological pairings is still a major problem in the application of artificial joint surgery. This study aims at developing wear reduced surfaces to utilize them in total joint arthroplasty. Using a pico-second laser, samples of medical CoCrMo metal alloy and Al2 O3 ceramic were patterned by laser material removal. The subsequent tribological investigations employed a ring-on-disc method. The results showed that those samples with modified surfaces show less mass or volume loss than those with a regular, smooth surface. Using calf serum as lubricating medium, the volume loss of the structured CoCrMo samples was eight times lower than that of regular samples. By structuring Al2 O3 surfaces, the wear volume could be reduced by 4.5 times. The results demonstrate that defined surface channels or pits enable the local sedimentation of wear debris. Thus, the amount of free debris could be reduced. Fewer abrasives in the lubricated so-called three-body-wear between the contact surfaces should result in less surface damage. Apart from direct influences on the wear behavior, less amounts of free debris of artificial joints should also be beneficial for avoiding undesired reactions with the surrounding soft tissues. The results from this study are very promising. Future investigations should involve the use of simulators meeting the natural conditions in the joint and in vivo studies with living organisms. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

Estudio de electrodeposición de cobre sobre electrodos porosos de grafito y acero inoxidable vía SEM-DRX y análisis de imagen

OpenAIRE

Constanzo-R., Robinson; Pagliero-N., Antonio; Vergara-G., Froilán

2014-01-01

El objetivo de este trabajo fue realizar un análisis cualitativo de la distribución de un electrodepósito de cobre en el interior de electrodos porosos (EP) de acero inoxidable y carbono grafito. Para ello, se realizaron pruebas de electrodepositación de cobre a nivel de laboratorio, con un posterior análisis de cortes de muestras de acero y grafito vía Microscopía Estereoscópica, Microscopía SEM-DRX y Análisis de Imagen, los cuales mostraron que el cobre no se deposita en forma uniforme al i...

Interdiffusion between U(Mo,Pt) or U(Mo,Zr) and Al or Al A356 alloy

International Nuclear Information System (INIS)

Komar Varela, C.; Mirandou, M.; Arico, S.; Balart, S.; Gribaudo, L.

2009-01-01

Solid state reactions in chemical diffusion couples U-7 wt.%Mo-0.9 wt.%Pt/Al at 580 deg. C and U-7 wt.%Mo-0.9 wt.%Pt/Al A356 alloy, U-7 wt.%Mo-1 wt.%Zr/Al and U-7 wt.%Mo-1 wt.%Zr/Al A356 alloy at 550 deg. C were characterized. Results were obtained from optical and scanning electron microscopy, electron probe microanalysis and X-ray diffraction. The UAl 3, UAl 4 and Al 20 Mo 2 U phases were identified in the interaction layers of γU(Mo,Pt)/Al and γU(Mo,Zr)/Al diffusion couples. Al 43 Mo 4 U 6 ternary compound was also identified in γU(Mo,Zr)/Al due to the decomposition of γU(Mo,Zr) phase. The U(Al,Si) 3 and U 3 Si 5 phases were identified in the interaction layers of γU(Mo,Pt)/Al A356 and γU(Mo,Zr)/Al A356 diffusion couples. These phases are formed due to the migration of Si to the interaction layer. In the diffusion couple U(Mo,Zr)/Al A356, Zr 5 Al 3 phase was also identified in the interaction layer. The use of synchrotron radiation at Brazilian Synchrotron Light Laboratory (LNLS, CNPq, Campinas, Brazil) was necessary to achieve a complete crystallographic characterization.

Effects of Bond Coating on NiCrBSi-Mo Composite Functional Coating Properties in Plasma Spraying NiCrBSi-Mo/Ni Coating

OpenAIRE

DU Ji-yu; LI Fang-yi; LU Hai-yang; SHANG Jian-tong; LI Zhen

2017-01-01

Nickel-based bond coating and composite functional coating were sprayed on leaf blade steel material FV520B successively by using air plasma spraying system. NiCrBSi-Mo powder deposition rate, coating porosity, bonding strength and surface hardness were tested. The results indicate that, for the NiCrBSi-Mo/Ni coating, bond coating with 180-220μm thickness can improve NiCrBSi-Mo powder deposition rate while the surface coating with lower porosity, higher bonding strength and high hardness is p...

Soft zone formation in dissimilar welds between two Cr-Mo steels

International Nuclear Information System (INIS)

Albert, S.K.; Gill, T.P.S.; Tyagi, A.K.; Mannan, S.L.; Rodriguez, P.; Kulkarni, S.D.

1997-01-01

Two dissimilar weldments between 9Cr-1Mo and 2.25Cr-1Mo ferritic steels have been characterized for their microstructural stability during various postweld heat treatments (PWHTs). The samples for the investigation were extracted from bead-on-plate weldments made by depositing 2.25Cr-1Mo weld metal on 9Cr-1Mo base plate and vice versa. Subsequent application of PWHT resulted in the formation of a soft zone in the low Cr ferritic steel weld or base plate. A carbide-rich hard zone, adjoining the soft zone, was also detected in the high Cr side of the weldment. Unmixed zones in the weld metal provided additional soft and hard zones in the weld metals. The migration of carbon from low-Cr steel to high-Cr steel, driven by the carbon activity gradient, has been shown to be responsible for the formation of soft and hard zones. A carbon activity diagram for 2.25Cr-1Mo/9Cr-1Mo weldments has been proposed to aid in the selection of welding consumables for reducing or preventing the soft zone formation

Effect of heat treatment on the impact properties of a 12Cr-1Mo-V-W steel

International Nuclear Information System (INIS)

Chin, B.A.; Wilcox, R.C.

1983-01-01

This paper describes the effects of austenitization and tempering treatments on the strength and impact properties of a 12Cr-1Mo-V-W steel. Data are reported for austenitization temperatures covering the range 900 to 1250 0 C and tempering treatments of 600 to 800 0 C. A 50 0 C improvement in the ductile brittle transition temperature is achieved through heat treatment. This is found to result from elimination of delta ferrite and associated carbides at the delta ferrite-matrix interface. 17 figures

Phase transformation in a Ni-Mo-Cr alloy

International Nuclear Information System (INIS)

Dymek, S.; Wrobel, M.; Blicharski, M.; Dollar, M.

2001-01-01

The paper gives a characteristic of a nickel-based superalloy containing 25 wt.% Mo and 8 wt.% Cr with particular attention to the influence of a thermochemical and heat treatment on phase transformations. The applied heat treatments are comprised of soaking temperature 1100 o C followed by aging at 650 o C at three conditions: conventional aging for 72 hours, prolonged aging for 4000 hours and prolonged aging for 4000 hours followed by cold working and subsequent aging for 1000 hours. The conventional aging led to the formation of lenticular precipitates of the dispersed metastable Ni 2 (Mo,Cr) phase. The aging for 4000 hours brought about coarsening of the ordered domains without changing their crystallographic and ordering characteristics. The plastic deformation preceded the further aging for 1000 hours accelerated the decomposition of the Ni 2 (Mo,Cr) phase on the mixture of the Ni 3 Mo and Ni 4 Mo-based phases. (author)

Estudio del comportamiento a fluencia en caliente de un acero avanzado de alta resistencia de bajo contenido en carbono NiCrVCu microaleado con boro

OpenAIRE

González Sala, Sara

2009-01-01

Una de las líneas de investigación prioritarias en el contexto internacional es el desarrollo de aceros avanzados de alta resistencia (AHSS) con excelentes propiedades de resistencia y tenacidad para aplicaciones en la industria automotriz, naval, aeronáutica y de generación de energía, que permitan disminuir el peso de los componentes y sustituyan aceros tradicionales de contenidos mayores de carbono. Los aceros AHSS microaleados al boro, debido a sus cualidades, tecnología de...

Experimental study and modelling of high temperature creep flow and damage behaviour of 9Cr1Mo-NbV steel weldments; Etude experimentale et modelisation, du comportement, de l'endommagement et de la rupture en fluage a haute temperature de joint soudes en acier 9Cr1Mo-NbV

Energy Technology Data Exchange (ETDEWEB)

Gaffard, V

2004-12-15

Chromium martensitic stainless steels are under development since the 70's with the prospect of using them as structural components in thermal and nuclear power plants. The modified 9Cr1Mo-NbV steel is already used, especially in England and Japan, as a material for structural components in thermal power plants where welding is a commonly used joining technique. New generations of chromium martensitic stainless steels with improved mechanical properties for high pressure and temperature use are currently under development. However, observations of several in-service premature failures of welded components in 9Cr1Mo-NbV steel, outline a strong need for understanding the high temperature creep flow and damage behaviour of 9Cr1Mo-NbV steels and weldments. The present study aimed at experimentally determining and then modelling the high temperature creep flow and damage behaviour of both 9Cr1Mo-NbV steels and weldments (typically in the temperature range from 450 C to 650 C). The base metal was first studied as the reference material. It was especially evidenced that tempered chromium martensitic steels exhibit a change in both creep flow and damage behaviour for long term creep exposure. As a consequence, the classically performed extrapolation of 1,000 hours creep data to 100,000 hours creep lifetime predictions might be very hazardous. Based on experimental observations, a new model, integrating and coupling multiple creep flow and damage mechanisms, was developed in the framework of the mechanics of porous media. It was then successfully used to represent creep flow and damage behaviour of the base metal from high to low stress levels even for complex multiaxial loading conditions. Although the high temperature creep properties of the base metal are quite good, the occurrence of premature failure in weldments in high temperature creep conditions largely focused the attention of the scientific community. The lower creep strength of the weld component was also

Search for high entropy alloys in the X-NbTaTiZr systems (X = Al, Cr, V, Sn)

Energy Technology Data Exchange (ETDEWEB)

Poletti, Marco Gabriele, E-mail: marcogabriele.poletti@unito.it [Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino (Italy); Fiore, Gianluca [Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino (Italy); Szost, Blanka A. [Strategic and Emerging Technologies Team (TEC-TS), European Space Agency, ESTEC, 1 Keplerlaan, 2201 AZ Noordwijk (Netherlands); Battezzati, Livio [Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino (Italy)

2015-01-25

Highlights: • Composition of refractory high entropy alloys predicted. • Solid solutions found in VNbTaTiZr and AlNbTaTiZr. • Alloys containing Cr and Sn are multi-phased. - Abstract: High entropy alloys, i.e. solid solution phases, are sought in the X-NbTaTiZr equiatomic system where the X element was chosen as Al, Cr, V and Sn by applying recent criteria based on size and electronegativity mismatch of alloy components, number of itinerant and total valence electrons, and the temperature at which the free energy of mixing changes at the alloy composition. The alloys containing V and Al are mostly constituted by solid solutions in good agreement with prediction.

In situ room temperature tensile deformation of a 1% CrMoV bainitic steel using synchrotron and neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Weisser, M.A. [Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Materials (IMX), CH-1012 Lausanne (Switzerland); Evans, A.D.; Van Petegem, S. [Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Holdsworth, S.R. [EMPA Materials Science and Technology, CH-8600 Duebendorf (Switzerland); Van Swygenhoven, H., E-mail: helena.vs@psi.ch [Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Materials (IMX), CH-1012 Lausanne (Switzerland)

2011-06-15

Neutron and synchrotron X-ray diffraction spectra have been acquired during room temperature tensile deformation of a creep-resistant bainitic 1% CrMoV steel, in order to study the evolution of internal microstresses and load-sharing mechanisms between the ferrite matrix and the various carbides. Cementite takes load from the plastifying matrix at the onset of macroscopic plasticity resulting in residual interphase stresses. Single peak fitting indicates an elastic anisotropic behaviour of cementite.

Alloy Design and Development of Cast Cr-W-V Ferritic Steels for Improved High-Temperature Strength for Power Generation Applications

Energy Technology Data Exchange (ETDEWEB)

Klueh, R L; Maziasz, P J; Vitek, J M; Evans, N D; Hashimoto, N

2006-09-23

Economic and environmental concerns demand that the power-generation industry seek increased efficiency for gas turbines. Higher efficiency requires higher operating temperatures, with the objective temperature for the hottest sections of new systems {approx} 593 C, and increasing to {approx} 650 C. Because of their good thermal properties, Cr-Mo-V cast ferritic steels are currently used for components such as rotors, casings, pipes, etc., but new steels are required for the new operating conditions. The Oak Ridge National Laboratory (ORNL) has developed new wrought Cr-W-V steels with 3-9% Cr, 2-3% W, 0.25% V (compositions are in wt.%), and minor amounts of additional elements. These steels have the strength and toughness required for turbine applications. Since cast alloys are expected to behave differently from wrought material, work was pursued to develop new cast steels based on the ORNL wrought compositions. Nine casting test blocks with 3, 9, and 11% Cr were obtained. Eight were Cr-W-V-Ta-type steels based on the ORNL wrought steels; the ninth was COST CB2, a 9Cr-Mo-Co-V-Nb cast steel, which was the most promising cast steel developed in a European alloy-development program. The COST CB2 was used as a control to which the new compositions were compared, and this also provided a comparison between Cr-W-V-Ta and Cr-Mo-V-Nb compositions. Heat treatment studies were carried out on the nine castings to determine normalizing-and-tempering treatments. Microstructures were characterized by both optical and transmission electron microscopy (TEM). Tensile, impact, and creep tests were conducted. Test results on the first nine cast steel compositions indicated that properties of the 9Cr-Mo-Co-V-Nb composition of COST CB2 were better than those of the 3Cr-, 9Cr-, and 11Cr-W-V-Ta steels. Analysis of the results of this first iteration using computational thermodynamics raised the question of the effectiveness in cast steels of the Cr-W-V-Ta combination versus the Cr-Mo-V

INFLUENCIA DE LOS RECUBRIMIENTOS DÚPLEX SOBRE LAS PROPIEDADES MECÁNICAS Y RESISTENCIA AL DESGASTE DEL ACERO AISI 4140 BONIFICADO

Directory of Open Access Journals (Sweden)

Francisco Javier Bolívar Osorio

Full Text Available El acero AISI 4140 es un acero de baja aleación al cromo/molibdeno de elevada resistencia mecánica y buena tenacidad, el cual se utiliza para la fabricación de piezas de maquinaria como piñones, cigüeñales, ejes de levas, etc. Sin embargo, su resistencia al desgaste es bastante limitada y suele ser mejorada mediante el tratamiento superficial de la nitruración. El propósito de este trabajo consistió en mejorar las propiedades mecánicas e incrementar la resistencia al desgaste del acero 4140 mediante la aplicación de un tratamiento superficial DUPLEX consistente en la nitruración líquida (conocida como Teniffer seguido del depósito de un recubrimiento duro de nitruro de titanio (TiN. La microestructura cristalina fue evaluada mediante difracción de rayos X, la morfología y la composición química fue determinada por microscopía SEM y espectroscopía de energía dispersiva de rayos X (EDS, las propiedades tribológicas fueron analizadas mediante mediciones en un tribómetro de tipo esfera sobre disco y la microdureza se determinó por el método Vickers. Las muestras tratadas con el recubrimiento dúplex mostraron una resistencia al desgaste 4 veces mayor que la muestra en estado bonificado, lo cual demuestra la aplicación potencial que tiene el acero 4140 sometido a este tratamiento dúplex.

The impact of different flooding periods on the dynamics of pore water concentrations of As, Cr, Mo and V in a contaminated floodplain soil - results of a lysimeter study

Science.gov (United States)

Rupp, Holger; Meissner, Ralph; Shaheen, Sabry; Rinklebe, Jörg

2014-05-01

Trace elements and arsenic (As) were transported with water during inundation in floodplain ecosystems, where they settled down and accumulated predominantly in depressions and low-lying terraces. Highly variable hydrological conditions in floodplains can affect the dynamics of pollutants. The impact of different flooding/drying periods on the temporal dynamics of pore water concentrations of As, Cr, Mo and V as a function of soil EH/pH changes and dynamics of DOC, Fe, Mn and SO42- was studied in a contaminated floodplain soil collected at the Elbe River (Germany). A specific groundwater lysimeter technique with two separate small lysimeter vessels served as replicates was used for this study. The groundwater level inside the lysimeters was controlled to simulate long term and short term flooding/drying. The long term (LT) flooding scenario consists of 94 days of flooding followed by similar drying term. The short term (ST) flooding/drying scenario comprises 21 days and was six times repeated. The entire experimental period (LT_ST) was about 450 days. Flooding of the soil caused a significant decrease of EH and pH. Concentrations of soluble As, Cr, Fe, Mn, Mo and DOC were higher under reducing conditions than under oxidizing conditions in LT. However, As and Cr tended to be mobilized under oxidizing conditions during ST, which might be due to slow kinetics of the redox reaction of As and Cr. Dynamics of Mo were more affected by changes of EH/pH as compared to As, Cr and V and governed mainly by Fe-Mn chemistry. Concentrations of V in ST were higher than in LT and were controlled particularly by pH and chemistry of Fe. The interactions between the elements and carriers studied were stronger during long flood-dry-cycles than during short cycles, which confirmed our hypothesis. We conclude that the dynamics of As, Cr, Mo and V are determined by the length of time soils are exposed to flooding, because drivers of element mobility need a certain time to provoke

Microstructural characterization of second phases in X10CrMoVNb9-1 and 12CrMoWCuVNb steels after long steam exposure time at 550 C

International Nuclear Information System (INIS)

Rodak, Kinga; Hernas, Adam; Vodarek, Vlastimil

2015-01-01

Microstructural changes in high alloy (9-12% Cr) creep resistant martensitic X10CrMoVNb9-1 and 12CrMoW . CuVNb steels after 100 000 h of steam exposure at 550 C have been studied using scanning transmission electron microscopy. Precipitates were identified using electron diffraction patterns and energy dispersive X-ray spectroscopy analysis. After long time exposure, a significant coarsening of M 23 C 6 carbides, and intensive precipitation of the coarse Laves phase were observed. Moreover, in the 12CrMoW . CuVNb steel, a low amount of the modified Z-phase particles was detected. The microstructures of the X10Cr . MoVNb9-1 and 12CrMoWCuVNb steels after 100 000 h of exposure differ in several aspects.

Microstructural characterization of second phases in X10CrMoVNb9-1 and 12CrMoWCuVNb steels after long steam exposure time at 550 C

Energy Technology Data Exchange (ETDEWEB)

Rodak, Kinga; Hernas, Adam [Silesian Univ. of Technology, Inst. of Materials Science, Katowice (Poland); Vodarek, Vlastimil [VSB-Technical Univ. of Ostrava (Czech Republic)

2015-07-15

Microstructural changes in high alloy (9-12% Cr) creep resistant martensitic X10CrMoVNb9-1 and 12CrMoW . CuVNb steels after 100 000 h of steam exposure at 550 C have been studied using scanning transmission electron microscopy. Precipitates were identified using electron diffraction patterns and energy dispersive X-ray spectroscopy analysis. After long time exposure, a significant coarsening of M{sub 23}C{sub 6} carbides, and intensive precipitation of the coarse Laves phase were observed. Moreover, in the 12CrMoW . CuVNb steel, a low amount of the modified Z-phase particles was detected. The microstructures of the X10Cr . MoVNb9-1 and 12CrMoWCuVNb steels after 100 000 h of exposure differ in several aspects.

Steam oxidation of X20CrMoV121: Comparison of laboratory exposures and in situ exposure in power plants

DEFF Research Database (Denmark)

Montgomery, M.; Hansson, A. N.; Vilhelmsen, T.

2012-01-01

X20CrMoV121 is a 12% Cr martensitic steel which has been used in power plants in Europe for many decades. Specimens have been removed from superheater tubes to investigate long‐term exposure with respect to steam oxidation. These tubes have been exposed for various durations up to 135 000 h...... in power plants in Denmark at steam temperatures varying from 450–565 °C. This paper collates the data, compares oxide morphologies and assesses to what extent parabolic kinetics can be used to describe the oxidation rate. The steam oxidation behaviour has been investigated in the laboratory in an Ar‐46%H2...

CATALIZADOR ESTRUCTURADO DE Pt/Al2O3 SOBRE UNA ESPUMA DE ACERO INOXIDABLE (AISI 314 PARA LA OXIDACIÓN DE CO

Directory of Open Access Journals (Sweden)

Juan P. Bortolozzi

2011-01-01

Full Text Available Se obtuvo un catalizador estructurado por recubrimiento de Pt/Al2O3 sobre las paredes de una espuma de acero inoxidable AISI 314. Para estabilizar térmicamente e incrementar la rugosidad de la superficie de la espuma original se realizó un tratamiento a 900°C por 2 h. El soporte, Al2O3, y el metal activo, Pt, se incorporaron por inmersión. Las técnicas de caracterización aplicadas, XRD, LRS y SEM-EDX, permiten concluir que el tratamiento térmico previo indujo la formación de óxido de cromo y de las espinelas Mn1+xCr2-xO4-x y FeCr2O4 como fases principales en las paredes del sustrato. El espesor de la capa formada es cercano a 1 μm y los cristales producidos tienen forma octaédrica. El cubrimiento de alúmina presentó en general una apariencia homogénea, sin interacción con los óxidos formados durante el tratamiento. El Pt se distribuyó de manera uniforme, resultando un catalizador muy activo para la reacción test elegida: oxidación de monóxido de carbono.

Synthesis and characterization of MoS2/Ti composite coatings on Ti6Al4V prepared by laser cladding

Science.gov (United States)

Yang, Rongjuan; Liu, Zongde; Wang, Yongtian; Yang, Guang; Li, Hongchuan

2013-02-01

The MoS2/Ti composite coating with sub-micron grade structure has been prepared on Ti6Al4V by laser method under argon protection. The morphology, microstructure, microhardness and friction coefficient of the coating were examined. The results indicated that the molybdenum disulfide was decomposed during melting and resolidification. The phase organization of composite coating mainly consisted of ternary element sulfides, molybdenum sulfides and titanium sulfides. The friction coefficient of and the surface roughness the MoS2/Ti coating were lower than those of Ti6Al4V. The composite coating exhibits excellent adhesion to the substrates, less surface roughness, good wear resistance and harder surface.

Heat treatment effects on impact toughness of 9Cr-1MoVNb and 12Cr-1MoVW steels irradiated to 100 dpa

Energy Technology Data Exchange (ETDEWEB)

Klueh, R.L.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)

1997-08-01

Plates of 9Cr-1MoVNb and 12Cr-1MoVW steels were given four different heat treatments: two normalizing treatments were used and for each normalizing treatment two tempers were used. Miniature Charpy specimens from each heat treatment were irradiated to {approx}19.5 dpa at 365{degrees}C and to {approx}100 dpa at 420{degrees}C in the Fast Flux Test Facility (FFTF). In previous work, the same materials were irradiated to 4-5 dpa at 365{degrees}C and 35-36 dpa at 420{degrees}C in FFTF. The tests indicated that prior austenite grain size, which was varied by the different normalizing treatments, had a significant effect on impact behavior of the 9Cr-1MoVNb but not on the 12Cr-1MoVW. Tempering treatment had relatively little effect on the shift in DBTT for both steels. Conclusions are presented on how heat treatment can be used to optimize impact properties.

Heat treatment effects on impact toughness of 9Cr-1MoVNb and 12Cr-1MoVW steels irradiated to 100 dpa

International Nuclear Information System (INIS)

Klueh, R.L.; Alexander, D.J.

1997-01-01

Plates of 9Cr-1MoVNb and 12Cr-1MoVW steels were given four different heat treatments: two normalizing treatments were used and for each normalizing treatment two tempers were used. Miniature Charpy specimens from each heat treatment were irradiated to ∼19.5 dpa at 365 degrees C and to ∼100 dpa at 420 degrees C in the Fast Flux Test Facility (FFTF). In previous work, the same materials were irradiated to 4-5 dpa at 365 degrees C and 35-36 dpa at 420 degrees C in FFTF. The tests indicated that prior austenite grain size, which was varied by the different normalizing treatments, had a significant effect on impact behavior of the 9Cr-1MoVNb but not on the 12Cr-1MoVW. Tempering treatment had relatively little effect on the shift in DBTT for both steels. Conclusions are presented on how heat treatment can be used to optimize impact properties

Postirradiation notch ductility tests of ESR alloy HT-9 and modified 9Cr-1Mo alloy from UBR reactor experiments

International Nuclear Information System (INIS)

Hawthorne, J.R.

1984-01-01

During this period, irradiation exposures at 300 0 C and 150 0 C to approx. 8 x 10 19 n/cm 2 , E > 0.1 MeV, were completed for the Alloy HT-9 plate and the modified Alloy 9Cr-1Mo plates, respectively. Postirradiation tests of Charpy-V (C/sub v/) specimens were completed for both alloys; other specimen types included in the reactor assemblies were fatigue precracked Charpy-V (PCC/sub v/), half-size Charpy-V, and in the case of the modified 9Cr-1Mo, 2.54 mm thick compact tension specimens

A Weakest-Link Approach for Fatigue Limit of 30CrNiMo8 Steels (Preprint)

Science.gov (United States)

2011-03-01

34Application of a Weakest-Link Concept to the Fatigue Limit of the Bearing Steel Sae 52100 in a Bainitic Condition," Fatigue and Fracture of...AFRL-RX-WP-TP-2011-4206 A WEAKEST-LINK APPROACH FOR FATIGUE LIMIT OF 30CrNiMo8 STEELS (PREPRINT) S. Ekwaro-Osire and H.V. Kulkarni Texas...2011 4. TITLE AND SUBTITLE A WEAKEST-LINK APPROACH FOR FATIGUE LIMIT OF 30CrNiMo8 STEELS (PREPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT

The application of miniature disc testing for the assessment of creep damage in CrMoV rotor steel

Energy Technology Data Exchange (ETDEWEB)

Parker, J D; Stratford, G C [University of Wales, Swansea (United Kingdom); Shaw, N; Spink, G [National Power plc (United Kingdom); Metcalfe, H [Siemens Power Generation (United Kingdom)

1999-12-31

A range of critical experiments has been performed studying the creep and fracture behaviour of a typical CrMoV rotor steel. Initially, uniaxial tests were carried out to provide material with a predetermined level of creep damage. Then, miniature disc tests were undertaken under accelerated conditions in a similar manner to procedures used for post-exposure uniaxial testing of service components. Data analysis demonstrates that the miniature tests accurately reflect the damage present so that this approach can be used to support run/repair/replace decisions. (orig.) 8 refs.

The application of miniature disc testing for the assessment of creep damage in CrMoV rotor steel

Energy Technology Data Exchange (ETDEWEB)

Parker, J.D.; Stratford, G.C. [University of Wales, Swansea (United Kingdom); Shaw, N.; Spink, G. [National Power plc (United Kingdom); Metcalfe, H. [Siemens Power Generation (United Kingdom)

1998-12-31

A range of critical experiments has been performed studying the creep and fracture behaviour of a typical CrMoV rotor steel. Initially, uniaxial tests were carried out to provide material with a predetermined level of creep damage. Then, miniature disc tests were undertaken under accelerated conditions in a similar manner to procedures used for post-exposure uniaxial testing of service components. Data analysis demonstrates that the miniature tests accurately reflect the damage present so that this approach can be used to support run/repair/replace decisions. (orig.) 8 refs.

Microchemistry of neutron irradiated 12%CrMoVNb martensitic steel

International Nuclear Information System (INIS)

Little, E.A.; Morgan, T.S.; Faulkner, R.G.

1992-01-01

Non-equilibrium solute segregation has been studied in a 12%CrMoVNb martensitic steel following fast reactor irradiation at 465 C and correlated with the development of M 6 X η-phase. Cr, Ni, Si, Mo, P and Mn are all shown to exhibit positive segregation to lath boundaries and are subsequently incorporated into M 6 X precipitates. The co-segregation of a combination of these elements which include P and Si, and possibly Cr or Mo, appears to promote M 6 X formation

Influence of chemical composition in crystallographic texture Fe-Cr-Mo alloys

International Nuclear Information System (INIS)

Moura, L.B.; Guimaraes, R.F.

2010-01-01

The use of steels with higher contents of Mo in the oil industry has been an alternative to reduce the effect of naphthenic corrosion in refining units. The addition of Mo in Fe-Cr alloys in the same manner that increases resistance to corrosion naphthenic causes some difficulties such as difficulty of forming, welding and embrittlement. In this work, experimental ingots of Fe-Cr-Mo alloys (Cr - 9, 15 and 17%, Mo - 5, 7 and 9%) were melted in vacuum induction furnace and hot and cold rolled in a laboratory rolling mill. The influence of chemical composition on crystallographic texture of samples subjected to the same thermo-mechanical treatment was analyzed by x-ray diffraction. The results indicate that fiber (111) becomes more intense with increasing Mo and/or Cr contents. (author)

Creep cavity and carbide studies during creep of a 12%CrMoV-steel

Energy Technology Data Exchange (ETDEWEB)

Andersson, Henrik; Storesund, J.; Seitisleam, F.

1997-03-01

Uniaxial creep tests of a X20CrMoV 12 1 steel has been carried out. The work was performed as a follow-up on earlier investigations on a similar steel with lower creep ductility. A comparison with this previous work is included. Both interrupted and rupture tests were performed and studies were made of cavity formation processes and carbide transformations. The creep curves could be reproduced using an analytical model. No secondary creep was observed. Cavities were found to form already at a strain of 1%. The cavity density, mean diameter and cavitated area fraction were found to have a linear relationship with the strain for strains up to about 10%. The mean carbide diameter was observed to be a function of time at temperature. A small decrease in carbide density with strain was detected 12 refs, 28 figs, 6 tabs

Influence of a sol–gel alumina coating on oxidation of X20CrMoV12-1 in air up to 650 °C

International Nuclear Information System (INIS)

Schulz, W.; Feigl, M.; Dörfel, I.; Nofz, M.; Kranzmann, A.

2013-01-01

The need for a more efficient coal power plant generation (e.g. oxyfuel technology) results in modified process parameters and enhanced corrosion. To reach the necessary service life of high temperature parts protective coatings may be a sufficient technical solution. A modified Yoldas sol (Al 2 O 3 based) was used to coat X20CrMoV12-1 by spin coating. After appropriate heat treatments transition alumina coatings being about 400 nm thick were obtained. Oxidation studies were carried out in laboratory air at temperatures up to 650 °C for up to 500 h exposure time. In case of the uncoated sample a rough oxide layer formed on the surface and a remarkable weight gain (2.62 mg/cm 2 ) were detected. The sol–gel alumina layer (mainly δ-Al 2 O 3 ) demonstrated a high protection, i.e. a very low weight gain (0.05 mg/cm 2 ). Diffusion of alloying elements into the coating was observed. No indication of spallation of the coating occurred. Local defects (2 μm–30 μm) in the coating led to the formation of iron-oxide islands. - Highlights: • Power plant steel X20 was coated with alumina by sol–gel method. • A 400 nm alumina layer provides good protection up to 650 °C. • Cr and Mn diffusion into Al 2 O 3 supports coating adhesion and protective ability. • Improvement of the coating process must be directed to avoidance of local defects

Nucleation and microstructure development in Cr-Mo-V tool steel during gas atomization

Science.gov (United States)

Behúlová, M.; Grgač, P.; Čička, R.

2017-11-01

Nucleation studies of undercooled metallic melts are of essential interest for the understanding of phase selection, growth kinetics and microstructure development during their rapid non-equilibrium solidification. The paper deals with the modelling of nucleation processes and microstructure development in the hypoeutectic tool steel Ch12MF4 with the chemical composition of 2.37% C, 12.06 % Cr, 1.2% Mo, 4.0% V and balance Fe [wt. %] in the process of nitrogen gas atomization. Based on the classical theory of homogeneous nucleation, the nucleation temperature of molten rapidly cooled spherical particles from this alloy with diameter from 40 μm to 600 μm in the gas atomization process is calculated using various estimations of parameters influencing the nucleation process - the Gibbs free energy difference between solid and liquid phases and the solid/liquid interfacial energy. Results of numerical calculations are compared with experimentally measured nucleation temperatures during levitation experiments and microstructures developed in rapidly solidified powder particles from the investigated alloy.

Cr-doped III-V nitrides: Potential candidates for spintronics

KAUST Repository

Amin, Bin

2011-02-19

Studies of Cr-doped III-V nitrides, dilute magnetic alloys in the zincblende crystal structure, are presented. The objective of the work is to investigate half-metallicity in Al 0.75Cr 0.25N, Ga 0.75Cr 0.25N, and In 0.75Cr 0.25N for their possible application in spin-based electronic devices. The calculated spin-polarized band structures, electronic properties, and magnetic properties of these compounds reveal that Al 0.75Cr 0.25N and Ga 0.75Cr 0.25N are half-metallic dilute magnetic semiconductors while In 0.75Cr 0.25N is metallic in nature. The present theoretical predictions provide evidence that some Cr-doped III-V nitrides can be used in spintronics devices. © 2011 TMS.

Cr-doped III-V nitrides: Potential candidates for spintronics

KAUST Repository

Amin, Bin; Arif, Suneela K.; Ahmad, Iftikhar; Maqbool, Muhammad; Ahmad, Roshan; Goumri-Said, Souraya; Prisbrey, Keith A.

2011-01-01

Studies of Cr-doped III-V nitrides, dilute magnetic alloys in the zincblende crystal structure, are presented. The objective of the work is to investigate half-metallicity in Al 0.75Cr 0.25N, Ga 0.75Cr 0.25N, and In 0.75Cr 0.25N for their possible application in spin-based electronic devices. The calculated spin-polarized band structures, electronic properties, and magnetic properties of these compounds reveal that Al 0.75Cr 0.25N and Ga 0.75Cr 0.25N are half-metallic dilute magnetic semiconductors while In 0.75Cr 0.25N is metallic in nature. The present theoretical predictions provide evidence that some Cr-doped III-V nitrides can be used in spintronics devices. © 2011 TMS.

Synthesis and characterization of MoS2/Ti composite coatings on Ti6Al4V prepared by laser cladding

Directory of Open Access Journals (Sweden)

Rongjuan Yang

2013-02-01

Full Text Available The MoS2/Ti composite coating with sub-micron grade structure has been prepared on Ti6Al4V by laser method under argon protection. The morphology, microstructure, microhardness and friction coefficient of the coating were examined. The results indicated that the molybdenum disulfide was decomposed during melting and resolidification. The phase organization of composite coating mainly consisted of ternary element sulfides, molybdenum sulfides and titanium sulfides. The friction coefficient of and the surface roughness the MoS2/Ti coating were lower than those of Ti6Al4V. The composite coating exhibits excellent adhesion to the substrates, less surface roughness, good wear resistance and harder surface.

About oxide dispersion particles chemical compatibility with areas coherent dissipation/sub-grains of bcc-alloys in Fe - (Cr, V, Mo, W systems

Directory of Open Access Journals (Sweden)

Udovsky A.

2016-01-01

Full Text Available A concept of partial magnetic moments (PMM of the iron atoms located in the first ч four coordination spheres (1÷4 CS for bcc lattice have been introduced based on analysis of results obtained by quantum-mechanical calculations (QMC for volume dependence of the average magnetic moment ferromagnetic (FM Fe. The values of these moments have been calculated for pure bcc Fe and bcc - Fe-Cr alloys. This concept has been used to formulate a three sub-lattice model for binary FM alloys of the Fe-M systems (M is an alloying paramagnetic element. Physical reason for sign change dependence of the short-range order and mixing enthalpy obtained by QMCs for Fe-(Cr, V bcc phases has been found. Using this model it has been predicted that static displacements of Fe - atoms in alloy matrix increase with increasing the of CS number and result in reducing of the area of coherent dissipation (ACD size with growth of the dimension factor (DF in the Fe-(Cr, V, Mo, W systems in agreement with the X-ray experiments. It has been shown theoretically that anisotropy of spin- density in bcc lattice Fe and DF in binary Fe - (Cr, V, Mo, W systems is main factor for origins of segregations on small angle boundaries of ACD and sub-grains boundaries To prevent the coagulation of both ACD and sub-grains, and to increase the strength of alloys, it is advisable to add oxide dispersion particles into ferrite steel taking into account their chemical compatibility and coherent interfacing with the crystalline lattice of a ferrite matrix. Application of phase diagrams for binary and ternary the Fe-(Y, Zr-O systems to verify chemical compatibility of oxide dispersion particles with ferrite matrix have been discussed

Optimized Gen-II FeCrAl cladding production in large quantity for campaign testing

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sun, Zhiqian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-06-03

There are two major objectives in this report; (1) to optimize microstructure control of ATF FeCrAl alloys during tube drawing processes, and (2) to provide an update on the progress of ATF FeCrAl tube production via commercial manufacturers. Experimental efforts have been made to optimize the process parameters balancing the tube fabricability, especially for tube drawing processes, and microstructure control of the final tube products. Lab-scale sheet materials of Gen II FeCrAl alloys (Mo-containing and Nb-containing FeCrAl alloys) were used in the study, combined with a stepwise warm-rolling process and intermediate annealing, aiming to simulate the tube drawing process in a commercial tube manufacturer. The intermediate annealing at 650ºC for 1h was suggested for the tube-drawing process of Mo-containing FeCrAl alloys because it successfully softened the material by recovering the work hardening introduced through the rolling step, without inducing grain coarsening due to recrystallization. The final tube product is expected to have stabilized deformed microstructure providing the improved tensile properties with sufficient ductility. Optimization efforts on Nb-containing FeCrAl alloys focused on the effect of alloying additions and annealing conditions on the stability of deformed microstructure. Relationships between the second-phase precipitates (Fe₂Nb-Laves phase) and microstructure stability are discussed. FeCrAl tube production through commercial tube manufacturers is currently in progress. Three different manufacturers, Century Tubes, Inc. (CTI), Rhenium Alloys, Inc. (RAI), and Superior Tube Company, Inc. (STC), are providing capabilities for cold-drawing, warm-drawing, and HPTR cold-pilgering, respectively. The first two companies are currently working on large quantity tube production (expected 250 ft length) of Gen I model FeCrAl alloy (B136Y3, at CTI) and Gen II (C35M4, at RAI), with the process parameters obtained from the experimental

On the excitation spectra of Cr{sup 3+}/Cr{sup 2+} and V{sup 3+} co-doped ZnAl{sub 2}S{sub 4} single crystals

Energy Technology Data Exchange (ETDEWEB)

Anghel, S., E-mail: anggell@gmail.com [Institute of Applied Physics, Academiei Str 5, Chis,inău MD-2028, Republic of Moldova (Moldova, Republic of); Ruhr-Universität Bochum, Anorganische Chemie III, Universitätsstrasse 150, D-44801 Bochum (Germany); Brik, M.G. [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, Ravila 14 C, Tartu 50411 (Estonia); Institute of Physics, Jan Dlugosz University, Armii Krajowej 13/15, PL-42200 Czestochowa (Poland); Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw (Poland); Ma, C.-G. [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Sushkevich, K. [State University of Moldova, Mateevici Str 60, Chis,inău MD-2009, Republic of Moldova (Moldova, Republic of); Kulyuk, L. [Institute of Applied Physics, Academiei Str 5, Chis,inău MD-2028, Republic of Moldova (Moldova, Republic of)

2015-10-15

The excitation spectra of the ZnAl{sub 2}S{sub 4} spinel crystals codoped with chromium and vanadium are investigated in order to explain some features of the Cr{sup 3+} ions optical spectra and the inconsistency of the experimental absorption/emission bands position with the Tanabe–Sugano diagram, as well as the “missing” band in the absorption spectrum of V{sup 3+} ion although this band should be present as it is due to a spin allowed transition. The unusual high Racah parameters of the C/B ratio for Cr{sup 3+} ions have been induced to recalculate the Tanabe–Sugano diagram for the d{sup 3} electron configuration and the ratio C/B=8 in order to use it for the experimental results interpretation. The presence of Cr{sup 2+} ions in the low spin electron configurations in the octahedral coordination was confirmed; the temperature dependence of the Cr{sup 2+} emission at about 1.9 eV was studied and the Huang–Rhys factors were estimated for different temperatures. Despite the fact that the V{sup 3+}C/B ratio has a different value compared to the case of Cr{sup 3+} ions, the electron–phonon interaction is similar for both ions, with the Huang–Rhys parameter equal to 10 in both cases. Further research into optimizing the ZnAl{sub 2}S{sub 4}:Cr, V system to get an efficient enhancement of the vanadium emission on account on re-absorbing the chromium emission is suggested. - Highlights: • The spectroscopic properties of Cr and V codoped α-ZnAI{sub 2}S{sub 4} have been investigated. • The crystal field calculations have been performed. • The Huang–Rhys factors have been estimated for different temperatures. • The theoretical calculations have been correlated with the excitation spectra.

Microstructure and Mechanical Properties of Highly Alloyed FeCrMoVC Steel Fabricated by Spark Plasma Sintering

Science.gov (United States)

Oh, Seung-Jin; Jun, Joong-Hwan; Lee, Min-Ha; Shon, In-Jin; Lee, Seok-Jae

2018-05-01

In this study, we successfully fabricated highly alloyed FeCrMoVC specimens within 2 min by using the spark plasma sintering (SPS) method. The densities of the sintered specimens were almost identical to their theoretical values. Fine (Mo, V)-rich carbides with lamellar structure were precipitated along the grain boundaries of the as-sintered specimen, whereas relatively large carbides were formed additionally in the transgranular region during the tempering treatment. Compared with the specimen produced by a conventional casting method, the FeCrMoVC specimens from SPS showed smaller grain size with finer carbides and higher hardness values.

Microstructural parameters and yielding in a quenched and tempered Cr-Mo-V pressure vessel steel

International Nuclear Information System (INIS)

Toerroenen, Kari

1979-01-01

In this work the plastic deformation behaviour of a Cr-Mo-V pressure vessel steel is studied at ambient and low temperatures. To produce a wide range of microstructures, different austenitizing, quenching and tempering treatments are performed. The microstructures, including grain and dislocation structures as well as carbides, are evaluated. A qualitative model is proposed for the martensitic and bainitic transformations explaining the morphology and crystallography of the transformation products. Based on microstructural observations of undeformed and deformed materials, as well as the tensile test results, the role of various obstacles to dislocation motion in plastic deformation is evaluated. Finally the strength increment, its temperature dependence and the effect due to combinations of various obstacles are analyzed. The results are intended to serve as basis for further fracture behaviour analyses. (author)

Análisis del comportamiento mecánico de una aleación Ni-Cr-Mo para pilares dentales/Analysis of Mechanical Behavior of Ni-Cr-Mo alloy for Dental Abutments

Directory of Open Access Journals (Sweden)

Luis Alberto Laguado Villamizar

2012-12-01

Full Text Available El presente estudio caracteriza una aleación aplicable al diseño de pilares para implantes dentales. Se propone un material biocompatible y de alta resistencia mecánica como alternativa a las aleaciones de Titanio, disminuyendo los costos de materia prima y procesamiento. Se realizan pruebas mecánicas de tracción y de compresión a la aleación de Ni-Cr-Mo, posteriormente se realiza modelado 3D y simulación de sus propiedades mecánicas por medio de análisis de elementos finitos. Como resultado se obtiene que el material disminuye su resistencia mecánica después del proceso de fundición empleado. El modelo de simulación es válido para análisis de resistencia en pilares dentales.This study presents the characterization of a dental implant alloy for abutments. It proposes a biocompatible material and high mechanical resistance as an alternative to Titanium alloys, lowering costs of raw materials and processing. Mechanical testing of the Ni-Cr-Mo alloy and subsequently perform simulations of its mechanical properties by means of finite element analysis. As a result is obtained that the material reduces its mechanical strength after the casting for electric induction molding process. The simulation model is valid to make analysis of resistance to this type of dental devices.

Evolution of the electronic structure and physical properties of Fe2MeAl (Me = Ti, V, Cr) Heusler alloys

International Nuclear Information System (INIS)

Shreder, E; Streltsov, S V; Svyazhin, A; Makhnev, A; Marchenkov, V V; Lukoyanov, A; Weber, H W

2008-01-01

We present the results of experiments on the optical, electrical and magnetic properties and electronic structure and optical spectrum calculations of the Heusler alloys Fe 2 TiAl, Fe 2 VAl and Fe 2 CrAl. We find that the drastic transformation of the band spectrum, especially near the Fermi level, when replacing the Me element (Me = Ti, V, Cr), is accompanied by a significant change in the electrical and optical properties. The electrical and optical properties of Fe 2 TiAl are typical for metals. The abnormal behavior of the electrical resistivity and the optical properties in the infrared range for Fe 2 VAl and Fe 2 CrAl are determined by electronic states at the Fermi level. Both the optical spectroscopic measurements and the theoretical calculations demonstrate the presence of low-energy gaps in the band spectrum of the Heusler alloys. In addition, we demonstrate that the formation of Fe clusters may be responsible for the large enhancement of the total magnetic moment in Fe 2 CrAl

Phase transformation and tribological properties of Ag-MoO3 contained NiCrAlY based composite coatings fabricated by laser cladding

Science.gov (United States)

Wang, Lingqian; Zhou, Jiansong; Xin, Benbin; Yu, Youjun; Ren, Shufang; Li, Zhen

2017-08-01

Ag-MoO3 contained NiCrAlY based composite coating was successfully prepared on GH4169 stainless steel substrate by high energy ball milling and laser cladding. The microstructure and phase transformation were investigated by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction spectrum (XRD). The tribological behavior and mechanism from room temperature to 800 °C were investigated. Results showed that MoO3 in the composite powders transformed to Mo2C reinforcement under the high energy density of laser, and a series of opposite transformation occurred during friction process. The coating showed the lowest friction coefficient and low wear rate at 600 °C and 800 °C due to the generation of Ag2MoO4 during tribo-chemical reactions and the formation of lubrication glaze on the worn surface. Ag made effective lubrication when the temperature rose up to 200 °C. The coating displayed a relatively high friction coefficient (about 0.51) at 400 °C, because though MoO3 (oxidation products of Mo2C) and Ag2MoO4 were detected on the worn surface, they could not realize effective lubrication at this temperature. Abrasive wear, adhesive wear and plastic deformation contributed to the increased friction and wear.

Hydrogen effect on different melts of steel 03Cr10Ni10Mo2(Ti,Al)

International Nuclear Information System (INIS)

Hruby, J.; Novosad, P.; Axamit, R.

1984-01-01

The effect of hydrogen on martensitic 03Cr10Ni10Mo2(Ti,Al) steel was studied following vacuum induction melting and electroslag remelting with and without the effect of radiation. Under the influence of hydrogen and under the same parameters of catodic hydrogen charging of steel after vacuum induction melting shows a 20 - 30% reduction in total ductility. Steels after electroslag remelting show a higher reduction in total ductility - within the range of 26 - 33%, i.e., 33 - 43% for different melts, and contraction Z shows a reduction of 23 - 59%. Electroslag remelted steels show a greater reduction in plasticity owing to hydrogen than steels melted in vacuum induction furnaces. The reduction of the yield point and the breaking strength owing to hydrogen are more explicit than in steel after vacuum melting. In non-irradiated hydrogenated samples a higher yield point was evident. (B.S.)

Density of thermal vacancies in γ-Ti-Al-M, M = Si, Cr, Nb, Mo, Ta or W

International Nuclear Information System (INIS)

Woodward, C.; Kajihara, S.

1999-01-01

Modifications to alloy chemistry are often used to tailor the intrinsic flow behavior of structural materials. Models of creep in intermetallic alloys must account for the influence of chemistry on the available intrinsic creep mechanisms. As in simple metals the presence of vacancies strongly influences bulk diffusion processes in these materials. Limiting the density of constitutional and thermal vacancies by alloying may produce materials with enhanced creep properties. The energy of intrinsic and substitutional point defects in L1 0 TiAl is calculated within a first principles, local density functional theory framework. Relaxed structures and energies for vacancies, antisites and solid solutions are calculated using a plane-wave-pseudopotential method. Calculated defect energies are used within a canonical ensemble formalism to estimate the point defect densities as a function of temperature and composition. The density of vacancies is found to be sensitive to the underlying stoichiometry of TiAl. The dependence of the vacancy concentration for solid solutions of Si, Cr, Nb, Mo, Ta and W is also predicted

Microstructure-based modelling of the long-term monotonic and cyclic creep of the martensitic steel X 20(22) CrMoV 12 1

International Nuclear Information System (INIS)

Henes, D.; Straub, S.; Blum, W.; Moehlig, H.; Granacher, J.; Berger, C.

1999-01-01

The current state of development of the composite model of deformation of the martensitic steel X 20(22) CrMoV 12 1 under conditions of creep is briefly described. The model is able to reproduce differences in monotonic creep strength of different melts with slightly different initial microstructures and to simulate cyclic creep with alternating phases of tension and compression. (orig.)

Oxidation Behavior of FeCrAl -coated Zirconium Cladding prepared by Laser Coating

Energy Technology Data Exchange (ETDEWEB)

Kim, Il-Hyun; Kim, Hyun-Gil; Choi, Byung-Kwan; Park, Jeong-Yong; Koo, Yang-Hyun; Kim, Jin-Seon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

From the recent research trends, the ATF cladding concepts for enhanced accident tolerance are divided as follows: Mo-Zr cladding to increase the high temperature strength, cladding coating to increase the high temperature oxidation resistance, FeCrAl alloy and SiC/SiCf material to increase the oxidation resistance and strength at high temperature. To commercialize the ATF cladding concepts, various factors are considered, such as safety under normal and accident conditions, economy for the fuel cycle, and developing development challenges, and schedule. From the proposed concepts, it is known that the cladding coating, FeCrAl alloy, and Zr-Mo claddings are considered as a near/mid-term application, whereas the SiC material is considered as a long-term application. Among them, the benefit of cladding coating on Zr-based alloys is the fuel cycle economy regarding the manufacturing, neutron cross section, and high tritium permeation characteristics. However, the challenge of cladding coating on Zr-based alloys is the lower oxidation resistance and mechanical strength at high-temperature than other concepts. Another important point is the adhesion property between the Zr-based alloy and coating materials. A laser coating method supplied with FeCrAl powders was developed to decrease the high-temperature oxidation rate in a steam environment through a systematic study for various coating parameters, and a FeCrAl-coated Zircaloy-4 cladding tube of 100 mm in length to the axial direction can be successfully manufactured.

Quasicrystalline and crystalline precipitation during isothermal tempering in a 12Cr-9Ni-4Mo maraging stainless steel

International Nuclear Information System (INIS)

Liu, P.; Stigenberg, A.H.; Nilsson, J.O.

1995-01-01

A thorough microstructural investigation has been performed on a high strength maraging steel of the type 12%Cr-9%Ni-4%Mo-2%Cu-1%Ti. The major precipitate formed during isothermal aging at 475 C is a quasicrystalline phase possessing icosahedral symmetry termed R'-phase with a typical chemical composition of 48%Mo-33%Fe-13%Cr-2%Ni-4%Si. At 550 C the major precipitate is trigonal R-phase with a typical composition of 45%Mo-31%Fe-18%Cr-4%Ni-2%Si. At 550 C also Laves phase with a composition of 48%Mo-35%Fe-13%Cr-2%Ni-2%Si could be observed. At both 475 and 550 C an ordered phase termed L-phase precipitated. This minority phase has an ordered face centered cubic (f.c.c.) structure of type L1 0 . Its composition is typically 9%Fe-4%Cr-52%Ni-15%Mo.-16%Ti-4%Al. R'-phase formed at 475 C transformed to R-phase and Laves phase during aging at 550 C. In an analogous manner, R-phase and Laves phase formed at 550 C transformed to R'-phase during subsequent aging at 475 C. This transformation was rationalized by a strong similarity in crystal structure between quasicrystalline R'-phase of icosahedral symmetry and Frank-Kasper phases such as R-phase and Laves phase

Influence of a sol–gel alumina coating on oxidation of X20CrMoV12-1 in air up to 650 °C

Energy Technology Data Exchange (ETDEWEB)

Schulz, W., E-mail: wencke.schulz@bam.de [BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin (Germany); Feigl, M. [BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin (Germany); Fügetechnik Berlin-Brandenburg GmbH, Kupferhammerweg 14-18, 16227 Eberswalde (Germany); Dörfel, I.; Nofz, M.; Kranzmann, A. [BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin (Germany)

2013-07-31

The need for a more efficient coal power plant generation (e.g. oxyfuel technology) results in modified process parameters and enhanced corrosion. To reach the necessary service life of high temperature parts protective coatings may be a sufficient technical solution. A modified Yoldas sol (Al{sub 2}O{sub 3} based) was used to coat X20CrMoV12-1 by spin coating. After appropriate heat treatments transition alumina coatings being about 400 nm thick were obtained. Oxidation studies were carried out in laboratory air at temperatures up to 650 °C for up to 500 h exposure time. In case of the uncoated sample a rough oxide layer formed on the surface and a remarkable weight gain (2.62 mg/cm{sup 2}) were detected. The sol–gel alumina layer (mainly δ-Al{sub 2}O{sub 3}) demonstrated a high protection, i.e. a very low weight gain (0.05 mg/cm{sup 2}). Diffusion of alloying elements into the coating was observed. No indication of spallation of the coating occurred. Local defects (2 μm–30 μm) in the coating led to the formation of iron-oxide islands. - Highlights: • Power plant steel X20 was coated with alumina by sol–gel method. • A 400 nm alumina layer provides good protection up to 650 °C. • Cr and Mn diffusion into Al{sub 2}O{sub 3} supports coating adhesion and protective ability. • Improvement of the coating process must be directed to avoidance of local defects.

The effects of minor alloy modifications and heat treatment on the microstructure and creep rupture behavior of 2.25Cr-1Mo Steel

International Nuclear Information System (INIS)

Todd, J.A.; Chung, D.W.; Parker, E.R.

1983-01-01

The effects of alloy additions on the microstructure of simulated cooled and tempered 2.25Cr-1Mo steels have been studied using transmission electron microscopy. Carbide precipitation sequences have been identified in the modification 3Cr-1Mo-1Mn-1Ni and compared to those in 2.25Cr-1Mo steels modified with Mn and Ni and also with Ti, V and B. The influence of minor compositional changes on the creep rupture behavior of 2.25Cr-1Mo steel has been studied at 500 C, 560 C, and 600 C. The most significant effect of alloy modifications on creep properties resulted from additions of Mn and Cr. Preliminary studies show that 1% Mn and 0.5Mn + 1Ni + 0.75Cr additions significantly reduce creep strength at all three temperatures for tests up to 2000 hours duration. The 3Cr-1Mo-1Mn-1Ni steel showed improvements in rupture ductility at all temperatures when compared with the base 2.25Cr-1Mo steel and the manganese-nickel modifications. Plots of the Larson-Miller parameter for both these modifications lay within the scatter band for commercial 2.25Cr-1Mo steels

Microstructural defects modeling in the Al-Mo system

International Nuclear Information System (INIS)

Pascuet, Maria I.; Fernandez, Julian R.; Monti, Ana M.

2006-01-01

In this work we have utilized computer simulation techniques to study microstructural defects, such as point defects and interfaces, in the Al-Mo alloy. Such alloy is taken as a model to study the Al(fcc)/U-Mo(bcc) interface. The EAM interatomic potential used has been fitted to the formation energy and lattice constant of the AlMo 3 intermetallic. Formation of vacancies for both components Al and Mo and anti-sites, Al Mo and Mo Al , as well as vacancy migration was studied in this structure. We found that the lowest energy defect complex that preserves stoichiometry is the antisite pair Al Mo +Mo Al , in correspondence with other intermetallics of the same structure. Our results also suggest that the structure of the Al(fcc)/Mo(bcc) interface is unstable, while that of the Al(fcc)/Al 5 Mo interface is stable, as observed experimentally. (author) [es

Comportamiento al desgaste por deslizamiento en aceros inoxidables: ferrítico, austenítico, dúplex y martensítico.

OpenAIRE

Renedo Rouco, Jordi

2010-01-01

En este proyecto se estudia el comportamiento al desgaste por deslizamiento de cuatro aceros representativos de las cuatro grandes familias de aceros inoxidables: ferrítico (AISI 446), austenítico (AISI 316), dúplex (AISI 2205) y martensítico (AISI 420). Para cada uno de ellos se han realizado: caracterización metalográfica, determinación de dureza, densidad y rugosidad, y ensayos de tribología mediante la técnica de bola sobre disco. Esta técnica consiste en deslizar una bola ...

Effect of chemical composition on irradiation embrittlement and annealing in Ni-Cr-Mo-V reactor pressure vessel steel

Energy Technology Data Exchange (ETDEWEB)

Novosad, P [Czech Nuclear Society, Prague (Czech Republic)

1994-12-31

Results concerning copper and phosphorus influence on radiation-induced changes in the Ni-Cr-Mo-V steel mechanical properties, are presented. Correlations between different mechanical properties for steels with different chemical composition, are presented. A comparison of transition temperature shifts obtained for static and dynamic fracture toughness tests and Charpy impact tests, is discussed. Recovery of radiation hardening, measured by hardness test after isochronal annealing of steels with different compositions, is also shown. Copper content strongly affects irradiation-induced changes of mechanical properties, but phosphorus content in connection with variable copper content has only a small effect. (author). 4 refs., 4 figs., 4 tabs.

Cyclic and isothermal oxidation behavior of 2.25Cr-1Mo steel; Estudio del comportamiento del acero 2.25Cr-1Mo frente a los fenomenos de oxidacion ciclica e isoterma

Energy Technology Data Exchange (ETDEWEB)

Proy, M.; Utrilla, M. v.; Otero, E.

2014-04-01

Cyclic and isothermal oxidation of chromium-molybdenum steel 2.25Cr-1Mo were analyzed at 550 degree centigrade and 650 degree centigrade during 360 hours in air atmospheres. The cycles were performed with two stages; one of heating in furnace during 90 minutes and then the sample were cooled to 50 degree centigrade by air flow. Thermogravimetric analyses were performed to obtain high temperature corrosion kinetics. Several characterization techniques have been used to identify the corrosion mechanism, as X-Ray Diffraction (XRD), Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). Thermal cycling tests can changes the corrosion mechanism, due cracks propagation in oxide scale, that witch can favors the access of oxidant agent to the substrate. (Author)

Creep properties and simulation of weld repaired low alloy heat resistant CrMo and Mo steels at 540 deg C. Sub-project 2 - Ex-serviced 2.25Cr1M0 weld metal and cross weld repairs

Energy Technology Data Exchange (ETDEWEB)

Rui Wu; Storesund, Jan; Borggreen, Kjeld; Feilitzen, Carl von

2007-12-15

Weld repair has been carried out in an ex-serviced 10 CrMo 9 10 pipe by using 10 CrMo 9 10, 13 CrMo 4 4 and 15 Mo 3 consumables. Application of current welding procedure and consumables results in an over matched weld repair. This is verified by both creep tests and the creep simulations at even lower stresses than tested. Creep specimens have been extracted from ex-serviced 10 CrMo 9 10 parent metal (PM) and weld metal (WM), from virgin 10 CrMo 9 10 WM, from virgin 13 CrMo 4 4 WM, and from virgin 15 Mo 3 WM. In addition, cross weld specimens including weld metal, heat affected zone (HAZ) and parent metal have been taken from the ex-serviced 10 CrMo 9 10 weld joint, and from three weld repairs. In total, there are nine test series. The sequence of creep lifetime at 540 deg C at given stresses is; virgin 10 CrMo 9 10 weld metal > virgin 15 Mo 3 weld metal approx virgin 13 CrMo 4 4 weld metal approx ex-serviced 10 CrMo 9 10 weld metal >> ex-serviced 10 CrMo 9 10 parent metal > ex-serviced 10 CrMo 9 10 cross weld approx 10 CrMo 9 10 cross weld repair approx 13 CrMo 4 4 cross weld repair approx and 15 Mo 3 cross weld repair. All the series show good creep ductility. The ex-serviced 10 CrMo 9 10 parent metal shows a creep lifetime about one order of magnitude shorter than that for both the virgin parent metal and the ex-serviced 10 CrMo 9 10 weld metal, independent of stresses. Differences in creep lifetime among the ex-serviced 10 CrMo 9 10 cross weld and other cross weld repairs are negligible, simply because rupture always occurred in the ex-serviced 10 CrMo 9 10 parent metal, approximately 10 mm from HAZ, for all the cross welds. Necking is frequently observed in the ex-serviced 10 CrMo 9 10 parent metal at the opposite side of the fracture. Creep damage to a large and a small extend is found adjacent to the fracture and at the necking area, respectively. Other parts of the weld joint like weld metal and HAZ are damage-free, independent of stress, weld metal and

Efectos gammágenos del cobre en los aceros inoxidables 18Cr8Ni

Directory of Open Access Journals (Sweden)

Botella, J.

1997-10-01

Full Text Available From a series of 22 typical 18Cr8Ni stainless steel 40 kg ingots, with copper variable concentrations from 0.6 to 3.0 weight %, δ-ferrite is measured with a ferrite-meter device, calculating a nickel equivalent of 0.27 for copper. Some differences between the 8-ferrite and that on calculated by DeLong -excluding the copper γ-gene action- have been found because of different solidification and cooling regimes in ingot and weld cases.

A partir de una serie de 22 lingotes de 40 kg de aceros inoxidables típicos 18Cr8Ni, con concentraciones variables de cobre entre 0,6 y 3,0 % en masa, se mide la ferrita δ mediante un medidor de ferrita y se deduce para el cobre un equivalente en níquel de 0,27, a la vez que se establecen ciertas diferencias entre los contenidos de ferrita δ medida y la deducida según DeLong -excluida la acción gammágena del cobre- por el hecho de solidificar en lingotes en vez de la típica solidificación de soldaduras.

Effect of Titanium on the Microstructure and Mechanical Properties of High-Carbon Martensitic Stainless Steel 8Cr13MoV

OpenAIRE

Wen-Tao Yu; Jing Li; Cheng-Bin Shi; Qin-Tian Zhu

2016-01-01

The effect of titanium on the carbides and mechanical properties of martensitic stainless steel 8Cr13MoV was studied. The results showed that TiCs not only acted as nucleation sites for δ-Fe and eutectic carbides, leading to the refinement of the microstructure, but also inhibited the formation of eutectic carbides M7C3. The addition of titanium in steel also promoted the transformation of M7C3-type to M23C6-type carbides, and consequently more carbides could be dissolved into the matrix duri...

The rate(time)- dependent mechanical behavior modified 9Cr-1Mo steel, 3

International Nuclear Information System (INIS)

Moosbrugger, J.C.

1991-01-01

In this paper, constitutive equations are presented for the nonisothermal small strain behavior of modified 9Cr-1Mo steel between 25degC - 600degC. The basic framework uses the superposition of nonlinear kinematic hardening rules as proposed by Chaboche and coworkes. A framework for accounting for isotropic softening is presented wherein this softening can be included in a drag stress, in a yield stress or as a decrease in the saturation level of kinematic hardening or some combination of these; a single isotropic softening equation is used as determined from experiments. The behavior of modified 9Cr-1Mo steel between 25degC - 600degC has been investigated by Swindeman, and Majors et. al. and many important features have been discussed. Here, model parameters are determined from available isothermal uniaxial data and some correlations with isothermal and nonisothermal tests are presented. (J.P.N.)

PROTECCIÓN CONTRA LA CORROSIÓN POR SALES FUNDIDAS DE UN ACERO AL CARBONO POR ROCIADO TERMICO

OpenAIRE

JOSE MARULANDA; ANDRÉS GARCÍA; JOSE VITOLA

2009-01-01

Se evaluó la corrosión por sales fundidas mediante la técnica gravimétrica en un acero de bajo carbono rociado térmicamente con una aleación de acero inoxidable, en una mezcla de sal con 20% Na2SO4 - 80% V2O5, entre 700ºC - 850ºC. Los resultados de las pruebas gravimétricas mostraron una deficiente protección de la capa rociada térmicamente y se presentó alta degradación en el recubrimiento protector, debido a que las temperaturas de exposición fueron mayores que las temperaturas de fusión de...

Metallurgical aspects of the weldability of Cr-Mo stabilised ferritic steels

International Nuclear Information System (INIS)

Colombe, Gerard; Petrequin, Pierre; Donati, J.R.; Zacharie, C.

1977-01-01

Results of tests performed to compare the tendency of 2.25 Cr-Mo and 9 Cr-2 Mo steels stabilised with niobium and niobium + vanadium, to different cracking phenomena susceptible to occur during welding, stress-relieving and service in the conditions of fast breeder reactors are presented

Properties of surface layer of X40CrMoV5-1 in the relation to remelting conditions by the use of a high power diode laser

International Nuclear Information System (INIS)

Dobrzanski, L.A.; Bonek, M.; Klimpel, A.

2003-01-01

Investigations included remelting experiments on the X40CrMoV5-1 hot-work steel with the high power diode laser. Tests have been made using the high power diode laser (HPDL) in the technological process of remelting. The effect of remelting parameters on structure and properties of its surface layer, as well as on remelting geometry and shape. The influence of the technological conditions and their effect on the mechanical properties of the surface layer, and especially its hardness has been tested. Dependence of the microhardness changes, on the degree of the laser beam influence on the treated surface, and mostly on the hardness increase in the remelted layer is presented. The influence of remelting process parameters on the structure of substrate material is presented. Guidelines for remelting of the X40CrMoV5-1 steel surface using the high power diode laser feature the outcome of the investigation aimed at obtaining its optimum mechanical and working properties. (author)

The influence of wall thickness on the microstructure of bronze BA1055 with the additions of Si, Cr, Mo and/or W

Directory of Open Access Journals (Sweden)

B.P. Pisarek

2008-12-01

Full Text Available Aluminium bronzes belong to the high-grade constructional materials applied on the put under strongly load pieces of machines, about good sliding, resistant properties on corrosion both in the cast state how and after the thermal processing. It moves to them Cr and Si in the aim of the improvement of their usable proprieties. Additions Mo and/or W were not applied so far in the larger concentration, these elements were introduced to the melts of the copper as the components of modifiers. It was worked out therefore the new kind of bronzes casting including these elements. Make additions to the Cu-Al-Fe-Ni bronze of Si, Cr, Mo and/or W in the rise of these properties makes possible. The investigations of the influence of the wall thickness of the cast on size of crystallites were conducted: the primary phase β and intermetallic phase κ and the width separates of the secondary phase α precipitate at phase boundary. It results from conducted investigations, that in the aluminium bronze BA1055 after simultaneous makes additions Si, Cr, Mo and in the primary phase β it undergoes considerable reducing size. The addition W reduce size of the grain phase β in the thin walls of the cast 3-6 mm, and addition Cr in the range of the thickness of the wall of the cast 3-6 mm it favors to reducing size the phase β, in walls 12-25 mm the growth causes it. The addition Mo does not influence the change of the size of the grain of the β phase significantly. The make addition singly or simultaneously of the Cr, Mo and W to the bronze CuAl10Fe5Ni5Si it influences the decrease of the quantity separates of the phase α on the interface boundary and of width it separates independently from the thickness of the wall of the cast. The simultaneous make addition of the Si, Cr, Mo and W it enlarges the surface of the phase κFe, κMo. The make addition to the bronze CuAl10Fe5Ni5Si of the Cr, Mo or W the quantity of crystallizing hard phase κ enlarges and the

Corrosion resistance of amorphous NiCrZr and NiCrMoZr alloys

International Nuclear Information System (INIS)

Naka, M.; Miyake, M.; Okamoto, I.

1987-01-01

One of the authors has reported that the corrosion resistance of chromium containing amorphous alloys is extremely improved by alloying phosphorus among metalloids. Two factors operate for the improvement of corrosion resistance of the amorphous alloys. First, phosphorus serves for the rapid formation of protective passive film. Second, the compositional and structural homogeneity in amorphous state also account for the formation of protective film. The latter factor has been clearly seen in the high corrosion resistance of CoCrMoZr and CoCrWZr alloys without metalloids. In order to clarify the separately two factors in the corrosion resistance of amorphous alloys, the corrosion resistance of amorphous alloys without metalloids has to be further investigated. This paper also deals with the corrosion resistance and electrochemical behavior of NiCrZr and NiCrMoZr alloys in 1N HCl, and compare them with the corrosion behavior of the crystalline alloys containing the same composition as that of the amorphous alloys

Characteristics of CrAlSiN + DLC coating deposited by lateral rotating cathode arc PVD and PACVD process

Energy Technology Data Exchange (ETDEWEB)

Lukaszkowicz, Krzysztof, E-mail: krzysztof.lukaszkowicz@polsl.pl [Institute of Engineering Materials and Biomaterials, Silesian University of Technology, Konarskiego St. 18A, 44-100 Gliwice (Poland); Sondor, Jozef, E-mail: j.sondor@liss.cz [LISS, a.s., Dopravni 2603, 756 61 Roznov p.R. (Czech Republic); Balin, Katarzyna, E-mail: katarzyna.balin@us.edu.pl [A. Chełkowski Institute of Physic, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Kubacki, Jerzy, E-mail: jerzy.kubacki@us.edu.pl [A. Chełkowski Institute of Physic, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland)

2014-09-01

Highlights: • The chemical composition of the CrAlSiN + DLC coatings was studied. • The coatings have nanostructural character with fine crystallites. • Their average size grain is less than 10 nm. • The coatings demonstrate friction coefficient within the range 0.05–0.07. • The coating demonstrated a dense cross-sectional morphology as well as good adhesion to the substrate. - Abstract: Coating system composed of CrAlSiN film covered by diamond-like carbon (DLC)-based lubricant, deposited on hot work tool steel substrate was the subject of the research. The CrAlSiN and DLC layers were deposited by PVD lateral rotating ARC-cathodes (LARC) and PACVD technology on the X40CrMoV5-1 respectively. HRTEM investigation shows an amorphous character of DLC layer. It was found that the tested CrAlSiN layer has a nanostructural character with fine crystallites while their average size is less than 10 nm. Based on the XRD pattern of the CrAlSiN, the occurrence of fcc phase was only observed in the coating, the texture direction 〈3 1 1〉 is perpendicular to the sample surface. Combined SEM, AES and ToF-SIMS studies confirmed assumed chemical composition and layered structure of the coating. The chemical distribution of the elements inside the layers and at the interfaces was analyzed by SEM and AES methods. It was shown that additional CrN layer is present between substrate and CrAlSiN coating. The atomic concentration of the particular elements of DLC and CrAlSiN layer was calculated from the XPS measurements. In sliding dry friction conditions the friction coefficient for the investigated elements is set in the range between 0.05 and 0.07. The investigated coating reveals high wear resistance. The coating demonstrated a dense cross-sectional morphology as well as good adhesion to the substrate.

Fatigue Properties of Aged Mod. 9Cr-1Mo

International Nuclear Information System (INIS)

Kim, Dae Whan; Kim, Sung Ho; Lee, Chan Bock

2007-01-01

Ferritic/Martensitic steel has a good mechanical properties and a lower thermal expansion coefficient than austenitic stainless steel. Mechanical property of Mod. 9Cr-1Mo steel is less than austenitic stainless steel at high temperature. High temperature mechanical properties are affected by precipitation for Mod. 9Cr-1Mo. FMS steel is used for long time at high temperature and the effect of aging on mechanical properties is very important. In this study, low cycle fatigue properties with aging were investigated

RESISTENCIA A LA CORROSIÓN DE LAS MULTICAPAS DE [TIN/ALTIN]n DEPOSITADAS SOBRE ACERO AL CARBONO AISI 1045

Directory of Open Access Journals (Sweden)

WILLIAM APERADOR

2011-01-01

Full Text Available En este artículo se presenta el mejoramiento frente a la corrosión de los recubrimientos multicapas de [TiN/AlTiN]n con periodos de 2, 6, 12 y 24 bicapas depositados mediante la técnica de PVD magnetrón Sputtering sobre acero al carbono AISI 1045. La evaluación electroquímica se realizó mediante las técnicas espectroscopia de impedancia electroquímica (EIS y curvas de polarización Tafel, en una solución de 0.5M de H2SO4 + 3.5% wt. de NaCl. La resistencia a la corrosión aumentó de forma gradual en función del número de bicapas en comparación al sustrato encontrando valores de velocidad de corrosión de 18.51 mpy para el sustrato sin recubrir y de 1x10 6 mpy para la muestra con 24 bicapas. Los resultados electroquímicos revelan el efecto positivo en cuanto a la protección superficial del acero 1045 con el incremento del periodo en las multicapas de [TiN /AlTiN]n.

Mechanical properties and microstructure changes of low-activation 3Cr-2W-V-Ti ferritic steels developed for nuclear applications

International Nuclear Information System (INIS)

Asakura, Kentaro; Kohyama, Akira; Yamada, Takemi.

1990-01-01

The effects of alloying elements such as Cr, W, V and Mn on tensile strength at elevated temperatures, creep-rupture properties and toughness of low activation (2.25-3)Cr-(2-2.5)W-V-Ti steels were investigated together with their microstructure change during high temperature exposure. These steels were normalized to produce bainitic structures in the same manner as that for a conventional 2.25Cr-1Mo steel. They presented superior tensile strength at elevated temperatures and creep-rupture strength in comparison with a conventional 2.25Cr-1Mo steel. The creep-rupture strength of the steels at 500degC for 100 000 h demonstrated about twice that of the conventional 2.25Cr-1Mo steel. The 3Cr-2.5W-0.2V-0.01Ti steel is recommended as a potential low activation ferritic steel for nuclear applications with well optimized mechanical properties, such as tensile strength at elevated temperatures, creep-rupture strength and toughness. The effects of alloying elements were discussed with correlating microstructural and mechanical aspects. (author)

Stress corrosion cracking in repair-welded 3.5 NiCrMoV steel in an actual turbine environment

International Nuclear Information System (INIS)

Hitomi, Itoh; Takashi, Shige; Takashi, Momoo

2001-01-01

Temporary welding repairs are sometimes needed when damage occurs at the teeth of blade grooves in a low-pressure turbine rotor operated at the dry/wet boundary region. When repair welding has been performed for the 3,5 NiCrMoV steel used in low-pressure turbines, the soundness of the weld must be confirmed. For this reason, a laboratory investigation of susceptibility for stress corrosion cracking (SCC) was conducted for test specimens taken from simulated welds, and then an exposure test was conducted in an actual turbine environment for approximately 7,000 hours. As no SCC initiation was detected and also the propagation was extremely small, repair welding is deemed to be applicable. (author)

Wear tests in a hip joint simulator of different CoCrMo counterfaces on UHMWPE

International Nuclear Information System (INIS)

Gonzalez-Mora, V.A.; Hoffmann, M.; Stroosnijder, R.; Gil, F.J.

2009-01-01

The objective in this work was to study the effect of different material counterfaces on the Ultra High Molecular Weight Polyethylene (UHMWPE) wear behavior. The materials used as counterfaces were based on CoCrMo: forged with hand polished and mass finished, CoCrMo coating applied on the forged CoCrMo alloy obtained by Physical Vapour Deposition (PVD). A hip joint simulator was designed and built for these studies. The worn surfaces were observed by optical and scanning electron microscopy. The results showed that the hand polished CoCrMo alloy caused the higher UHMWPE wear of the acetabular cups. The CoCrMo coating caused the least UHMWPE wear, while the mass finished CoCrMo alloy caused an intermediate UHMWPE wear. It is shown that the wear rates obtained in this work are closer to clinical studies than to similar hip joints simulator studies

Corrosión a alta temperatura de acero al carbono y acero inoxidable austenítico en atmósferas contaminadas por CO2

OpenAIRE

Proy Pérez, Manuel

2014-01-01

Los efectos a veces catastróficos producidos por los procesos de corrosión a alta temperatura en atmósferas contaminadas por agentes agresivos, poseen la suficiente relevancia para ser objeto de estudio en los próximos años, debido a que en muchas ocasiones no están definidos claramente. Los aceros al carbono y los inoxidables austeníticos son materiales potencialmente utilizables en condiciones de elevada temperatura gracias a su excelente relación entre sus propiedades est...

The stability of DLC film on nitrided CoCrMo alloy in phosphate buffer solution

International Nuclear Information System (INIS)

Zhang, T.F.; Liu, B.; Wu, B.J.; Liu, J.; Sun, H.; Leng, Y.X.; Huang, N.

2014-01-01

CoCrMo alloy is often used as the material for metal artificial joint, but metal debris and metal ions are the main concern on tissue inflammation or tissue proliferation for metal prosthesis. In this paper, nitrogen ion implantation and diamond like carbon (DLC) film composite treatment was used to reduce the wear and ion release of biomedical CoCrMo substrate. The mechanical properties and stability of N-implanted/DLC composite layer in phosphate buffer solution (PBS) was evaluated to explore the full potential of N-implanted/DLC composite layer as an artificial joint surface modification material. The results showed that the DLC film on N implanted CoCrMo (N-implanted/DLC composite layer) had the higher surface hardness and wear resistance than the DLC film on virgin CoCrMo alloy, which was resulted from the strengthen effect of the N implanted layer on CoCrMo alloy. After 30 days immersion in PBS, the structure of DLC film on virgin CoCrMo or on N implanted CoCrMo had no visible change. But the adhesion and corrosion resistance of DLC on N implanted CoCrMo (N-implanted/DLC composite layer) was weakened due to the dissolution of the N implanted layer after 30 days immersion in PBS. The adhesion reduction of N-implanted/DLC composite layer was adverse for in vivo application in long term. So researcher should be cautious to use N implanted layer as an inter-layer for increasing CoCrMo alloy load carrying capacity in vivo environment.

The effect of spheroidizing by thermal cycling in low concentration Cr-Mo alloy steel

International Nuclear Information System (INIS)

Yun, H.S.; Kang, C.Y.

1979-01-01

An intensive study was carried out on spheroidizing of pearlite (Sph) and number of spherical carbide in proeutectoid ferrite (No/100) of low concentration Cr-Mo steel with thermal cycling. Physical and mechanical properties of steel containing 0.33 % C with thermal cycling were compared with those of low concentration Cr-Mo steel with thermal cycling. The effect of normal heat treatment and cooling rate on spheroidizing of pearlite and precipitation of fine spherical carbide in the steels were investigated. The results obtained were as follows: 1) Thermal cycling of low concentration Cr-Mo steel promoted the spheroidizing of pearlite compared with that of steel without Cr and Mo to steel had significant effect on spheroidizing of pearlite. 2) Number of fine spherical carbides of low concentration Cr-Mo steel with thermal cycling was over 5 times to that of fine spherical carbides of hypoeutectoid steel with thermal cycling. 3) Spheroidizing of pearlite and number of fine spherical carbide in proeutectoid ferrite of low concentration Cr-Mo steel with increasing thermal cycle and cooling rate. 4) Hardness of steel with thermal cycling was decreased. However, low concentration Cr-Mo steel had little decreasing rate in hardness with increasing thermal cycle on the basis of 100 times in thermal cycle. Therefore, toughness was considered to be increased with increasing spheroidizing of pearlite without changing mechanical properties. (author)

Thermal Stability of Nanocrystalline Structure In X37CrMoV5-l Steel

Directory of Open Access Journals (Sweden)

Skołek E.

2015-04-01

Full Text Available The aim of the study was to investigate the thermal stability of the nanostructure produced in X37CrMoV5-1 tool steel by austempering heat treatment consisted of austenitization and isothermal quenching at the range of the bainitic transformation. The nanostructure was composed of bainitic ferrite plates of nanometric thickness separated by thin layers of retained austenite. It was revealed, that the annealing at the temperature higher than temperature of austempering led to formation of cementite precipitations. At the initial stage of annealing cementite precipitations occurred in the interfaces between ferritic bainite and austenite. With increasing temperature of annealing, the volume fraction and size of cementite precipitations also increased. Simultaneously fine spherical Fe7C3 carbides appeared. At the highest annealing temperature the large, spherical Fe7C3 carbides as well as cementite precipitates inside the ferrite grains were observed. Moreover the volume fraction of bainitic ferrite and of freshly formed martensite increased in steel as a result of retained austenite transformation during cooling down to room temperature.

Effect of Mn on microstructures and mechanical properties of Al-Mg-Si-Cu-Cr-V alloy

Directory of Open Access Journals (Sweden)

Zhao Zhihao

2012-11-01

Full Text Available In order to improve the performances of the Al-Mg-Si-Cu-Cr-V alloy, various amounts of Mn (0-0.9wt.% were added. The effect of this Mn on the microstructures and mechanical properties of Al-Mg-Si-Cu-Cr-V alloys in different states, especially after hot extrution and solid solution treatment, was systematically studied using scanning electron microscopy (SEM, energy dispersive spectroscopy (EDS, and mechanical tests at room temperature. The results show that 0.2wt.% Mn can both refine the as-cast microstructure of the alloy and strengthen the extrusion+T6 state alloy without damaging the plasticity badly due to the formation of Al15(FeMn3Si2 and Al15Mn3Si2 dispersoids. Compared with the extrusion+T6 state alloy without Mn addition, the ultimate tensile strength and yield strength of the alloy with 0.2wt.% Mn addition are increased from 416.9 MPa to 431.4 MPa, 360.8 MPa to 372 MPa, respectively. The elongation of the extrusion+T6 state alloy does not show obvious change when the Mn addition is less than 0.5wt.%, and for the alloy with 0.2wt.% Mn addition its elongation is still as high as 15.6%. However, when over 0.7wt.% Mn is added to the alloy, some coarse, stable and refractory AlVMn and Al(VMnSi phases form. These coarse phases can reduce the effect of Mn on the inhibition of re-crystallization; and they retain the angular morphology permanently after the subsequent deformation process and heat treatment. This damages the mechanical properties of the alloy.

Acero de alto silicio producido por inmersión en Al-Si y recocido de difusión

Directory of Open Access Journals (Sweden)

Ros-Yáñez, Tanya

2000-10-01

Full Text Available It is difficult to process steel sheet with a high Si content (>3.5%Si, mainly because of its brittleness and the appearance of cracks during rolling and oxidation. However, there is a market for this steel in electrical applications because of the favourable influence of Si on magnetostriction and electrical resistivity. As an alternative process, 3% Si-steel substrates were coated with hypereutectic Al-Si-alloys in a "hot-dip simulator" using different preheating and dipping times. The obtained layers were characterised by SEM and EDS analysis. Diffusion annealing experiments were performed to obtain sufficient amount of Si in the steel. It was observed that:

• intermetallic phases appear in the coating layers as according to the ternary Fe-Si-Al diagram
• with a double dipping primary silicon crystals are formed in the surface layer
• the ordered DO₃ structure is present if the dipping and/or diffusion time is long enough
• homogeneous silicon gradients in the whole substrate thickness have not yet been achieved
• theoretic calculations show that Si-gradient, also have beneficial effects on magnetic behaviour

Effect of cerium addition on microstructure and mechanical properties of high-strength Fe85Cr4Mo8V2C1 cast steel

Energy Technology Data Exchange (ETDEWEB)

Hufenbach, J., E-mail: j.k.hufenbach@ifw-dresden.de [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, D-01171 Dresden (Germany); Helth, A. [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, D-01171 Dresden (Germany); Lee, M.-H. [Korea Institute of Industrial Technology, Gaetbeol-ro 156, Yeonsu-gu, Incheon 406-840 (Korea, Republic of); Wendrock, H.; Giebeler, L. [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, D-01171 Dresden (Germany); Choe, C.-Y.; Kim, K.-H. [Korea Institute of Industrial Technology, Gaetbeol-ro 156, Yeonsu-gu, Incheon 406-840 (Korea, Republic of); Kühn, U. [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, D-01171 Dresden (Germany); Kim, T.-S. [Korea Institute of Industrial Technology, Gaetbeol-ro 156, Yeonsu-gu, Incheon 406-840 (Korea, Republic of); Eckert, J. [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, D-01171 Dresden (Germany); TU Dresden, Institute of Materials Science, D-01062 Dresden (Germany)

2016-09-30

This work presents an investigation on the influence of rare earth additions (Ce) on the microstructure and mechanical properties of a cast Fe85Cr4Mo8V2C1 (element contents in wt%) tool steel. The applied relatively high solidification rate during the casting process promotes the formation of non-equilibrium phases such as martensite, retained austenite as well as a fine network-like structure of complex carbides. This combination of phases and their morphology results in excellent mechanical properties already in the as-cast state. Cerium additions induce a change in phase formation and resulting mechanical properties. Besides morphological and quantitative changes of the main constituent phases, novel carbo-oxide and carbide phases are formed. To investigate this microstructural phenomenon, X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDX) were applied. Altogether, the addition of small amounts of the rare earth element cerium together with a tailored casting process results in enhanced mechanical properties compared to the Fe85Cr4Mo8V2C1 alloy and offers new possibilities to obtain high-strength and simultaneously adequate ductile cast steels for advanced tool design.

How TEM Projection Artifacts Distort Microstructure Measurements: A Case Study in a 9 pct Cr-Mo-V Steel

Science.gov (United States)

Monsegue, Niven; Reynolds, William T.; Hawk, Jeffrey A.; Murayama, Mitsuhiro

2014-08-01

Morphological data obtained from two-dimensional (2D) and three-dimensional (3D) transmission electron microscopy (TEM) observations were compared to assess the effects of TEM projection errors for submicron-size precipitates. The microstructure consisted of M23C6 carbides in a 9 pct Cr-Mo-V heat resistant steel before and after exposure to creep conditions. Measurements obtained from about 800 carbides demonstrate that particle size and spacing estimates made from 2D observations overestimate the more accurate values obtained from 3D reconstructions. The 3D analysis also revealed the M23C6 precipitates lengthen anisotropically along lath boundary planes, suggesting that coarsening during the early stage of creep in this alloy system is governed by grain boundary diffusion.

Laser cladding of Ti-6Al-4V with various carbide powders

International Nuclear Information System (INIS)

Folkes, J.A.; Shibata, K.

1994-01-01

Laser cladding Ti-6Al-4V can be achieved with various weight percentages of different carbide powders. The microstructure and morphology of the clad layer is determined by the cladding powder composition, for a given set of laser parameters, such that 10 and 20 wt% Cr 3 C 2 results in a β + TiC clad microstructure; 10 and 20 wt% WC results in an α + TiC clad microstructure (plus some original WC); and Mo 2 C gives an α + β + TiC or β + TiC structure, depending on the weight percentage of Mo 2 C. The morphology of the TiC in all cases is dendritic or feathery, depending on the carbide content. The microstructure observed in all cases agreed well with that theoretically predicted from the energetics of carbide formation and β-stabilizing properties of each element

Improvements in the susceptibility to hydrogen attack and stress-relief cracking of 2 1/4Cr-1Mo steels

International Nuclear Information System (INIS)

Imanaka, T.; Sato, S.; Shimomura, J.; Aso, K.

1985-01-01

The influence of sulphur content at extremely low level on the susceptibility to hydrogen attack and stress-relief cracking in 2 1/4Cr-1Mo steels was studied. The reduction of sulphur content and/or the addition of REM (rare earth metal) or Ca in accordance with sulphur content remarkably improve the resistivity against hydrogen attack and stress-relief cracking. Micro-structural examination has showed that there exist Mn-REM-S-Al-O complex particles in the REM-added steels. It is concluded that the effect of REM on hydrogen attack and stress-relief cracking is to reduce ''the free sulphur'' in 2 1/4Cr-1Mo steels

Al atom on MoO3(010) surface: adsorption and penetration using density functional theory.

Science.gov (United States)

Wu, Hong-Zhang; Bandaru, Sateesh; Wang, Da; Liu, Jin; Lau, Woon Ming; Wang, Zhenling; Li, Li-Li

2016-03-14

Interfacial issues, such as the interfacial structure and the interdiffusion of atoms at the interface, are fundamental to the understanding of the ignition and reaction mechanisms of nanothermites. This study employs first-principle density functional theory to model Al/MoO3 by placing an Al adatom onto a unit cell of a MoO3(010) slab, and to probe the initiation of interfacial interactions of Al/MoO3 nanothermite by tracking the adsorption and subsurface-penetration of the Al adatom. The calculations show that the Al adatom can spontaneously go through the topmost atomic plane (TAP) of MoO3(010) and reach the 4-fold hollow adsorption-site located below the TAP, with this subsurface adsorption configuration being the most preferred one among all plausible adsorption configurations. Two other plausible configurations place the Al adatom at two bridge sites located above the TAP of MoO3(010) but the Al adatom can easily penetrate below this TAP to a relatively more stable adsorption configuration, with a small energy barrier of merely 0.2 eV. The evidence of subsurface penetration of Al implies that Al/MoO3 likely has an interface with intermixing of Al, Mo and O atoms. These results provide new insights on the interfacial interactions of Al/MoO3 and the ignition/combustion mechanisms of Al/MoO3 nanothermites.

Solid solution limits and selected mechanical properties of the quaternary L12 trialuminide Al-Ti-Mn-Mo

International Nuclear Information System (INIS)

Schneibel, J.H.

1994-01-01

Intermetallics based on the trialuminide Al 3 Ti, or on Al 11 Ti 5 , have been extensively researched in recent years. Alloying with approximately 10 at.% of first-row transition elements, such as Cr or Mn, converts the DO 22 structure of Al 3 Ti to L1 2 . Although this transition to the L1 2 structure increases the number of independent slip systems to five and causes substantial softening, room-temperature tensile ductilities and fracture toughnesses remain low. Typical values for the room-temperature ductilities of Al-25Ti-8Cr and Al-25Ti-9Mn are 0.2% and room-temperature fracture toughnesses of trialuminides range from 2 to 5 MPa m 1/2 . Reasons for the low fracture toughness of trialuminides have been discussed by Turner et al. and George et al. On a phenomenological basis, it appears that fracture toughnesses might improve, if either Poisson's ratio or the ratio of the bulk and shear moduli can be increased. In principle, this might be achieved by macroalloying ternary L1 2 trialuminides, while at the same time maintaining the L1 2 crystal structure. Focusing on first-row transition elements, Kumar and Brown investigated a range of such quaternary compounds. They did not observe any improvement in ductility, as compared to the ternary compounds. In the present work, it was decided to focus on a second-row transition element, namely, 2 molybdenum. As compared to Cr and Mn, which are only slightly soluble in Al 3 Ti, up to 20 at. % Mo dissolves in Al 3 Ti at 1,198 K. This raises the question whether substantial amounts of Mo also dissolve in the cubic ternary trialuminides such as Al-Ti-Mn. In order to verify this possibility, the extent of the single-phase region of cubic Al-Ti-Mn-Mo intermetallic was mapped out at 1,473 K. In addition, a limited characterization of room-temperature mechanical properties was carried out

Ternary alloying study of MoSi2

International Nuclear Information System (INIS)

Yi, D.; Li, C.; Akselsen, O.M.; Ulvensoen, J.H.

1998-01-01

Ternary alloying of MoSi 2 with adding a series of transition elements was investigated by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). Iron, Co, Ni, Cr, V, Ti, and Nb were chosen as alloying elements according to the AB 2 structure map or the atomic size factor. The studied MoSi 2 base alloys were prepared by the arc melting process from high-purity metals. The EDS analysis showed that Fe, Co, and Ni have no solid solubility in as-cast MoSi 2 , while Cr, V, Ti, and Nb exhibit limited solid solubilities, which were determined to be 1.4 ± 0.7, 1.4 ± 0.4, 0.4 ± 0.1, and 0.8 ± 0.1. Microstructural characterization indicated that Mo-Si-M VIII (M VIII = Fe, Co, Ni) and Mo-Si-Cr alloys have a two-phase as-cast microstructure, i.e., MoSi 2 matrix and the second-phase FeSi 2 , CoSi, NiSi 2 , and CrSi 2 , respectively. In as-cast Mo-Si-V, Mo-Si-Ti, and Mo-Si-Nb alloys, besides MoSi 2 and C40 phases, the third phases were observed, which have been identified to be (Mo, V) 5 Si 3 , TiSi 2 , and (Mo, Nb) 5 Si 3

The influences of impurity content, tensile strength, and grain size on in-service temper embrittlement of CrMoV steels

International Nuclear Information System (INIS)

Cheruvu, N.S.; Seth, B.B.

1989-01-01

The influences of impurity levels, grain size, and tensile strength on in-service temper embrittlement of CrMoV steels have been investigated. The samples for this study were taken from steam turbine CrMoV rotors which had operated for 15 to 26 years. The effects of grain size and tensile strength on embrittlement susceptibility were separated by evaluating the embrittlement behavior of two rotor forgings made from the same ingot after an extended step-cooling treatment. Among the residual elements in the steels, only P produces a significant embrittlement. The variation of P and tensile strength has no effect on in-service temper embrittlement susceptibility, as measured by the shift in fracture appearance transition temperature (FATT). However, the prior austenite grain size plays a major role in service embrittlement. The fine grain steels with a grain size of ASTM No. 9 or higher are virtually immune to in-service embrittlement. In steels having duplex grain sizes, embrittlement susceptibility is controlled by the size of coarser grains. For a given steel chemistry, the coarse grain steel is more susceptible to in-service embrittlement, and a decrease in ASTM grain size number from 4 to 0/1 increases the shift in FATT by 61 degrees C (10/10 degrees F). It is demonstrated that long-term service embrittlement can be simulated, except in very coarse grain steels, by using the extended step-cooling treatment. The results of step-cooling studies show that the coarse grain rotor steels take longer time during service to reach a fully embrittled state than the fine grain rotor steels

X-ray study of rapidly cooled ribbons of Al-Cr-Zr and Al-Ni-Y-Cr-Zr alloys

International Nuclear Information System (INIS)

Betsofen, S.Ya.; Osintsev, O.E.; Lutsenko, A.N.; Konkevich, V.Yu.

2002-01-01

One investigated into phase composition, lattice spacing and structure of rapidly cooled 25-200 μm gauge strips made of Al-4,1Cr-3,2Zr and Al-1,5Cr-1,5Zr-4Ni-3Y alloys, wt. %, produced by melt spinning to a water-cooled copper disk. In Al-4,1Cr-3,2Zr alloy one detected intermetallic phases: Al 3 Zr and two Al 86 Cr 14 composition icosahedral phases apart from aluminium solid solution with 4.040-4.043 A lattice spacing. In Al-1,5Cr-1,5Zr-4Ni-3Y alloy one identified two Al 86 Cr 14 icosahedral phases and two AlNiY and Al 3 Y yttrium-containing ones, lattice spacing of aluminium solid solution was equal to 4.052-4.053 A [ru

Estudio de microestructura y composición de la oxidación en vapor a 700 y 750oC de los aceros austeníticos AISI 304, 316 y 317

Directory of Open Access Journals (Sweden)

José Luddey Marulanda

2013-01-01

Full Text Available Se ha investigado la oxidación de los aceros inoxidables austeníticos AISI SAE: 304, 316 y 317; a temperaturas de 700 y 750oC, en una atmósfera próxima al 100% de vapor de agua, y de 10 a 1000h de exposición. La finalidad es comprobar la calidad de los aceros austeníticos y estudiar la morfología, composición y estructura de la fases de las capas formadas en la cascarilla del óxido de las muestras por Microscopía Electrónica de Barrido (SEM, Análisis de Rayos X por Dispersión de Energía (EDAX y Difracción de Rayos X (XRD, respectivamente. Así como también, se ha realizado a diferentes tiempos un estudio sistemático de termogravimetría de las muestras oxidadas, donde se ha observado que el acero AISI 304 presentó la menor ganancia de masa y el acero AISI 316 fue el de mayor de masa respecto a los tres aceros del trabajo. Adicionalmente fue realizado un estudio teórico de simulación termodinámica de oxidación en vapor de los tres aceros, en las mismas condiciones experimentales y mediante el programa Thermo-calc. En estos aceros oxidados se han comprobado la presencia de estructuras de fases de óxidos como: Fe2O3, espinelas protectoras Fe3O4 y Cr2NiO4, y óxidos mixtos de tipo (CrxFey2O3, (Fe,Cr,Mn3O4 y Ni6MnO8. Finalmente, se discute un posible mecanismo de la formación de las capas de óxidos de las muestras ensayadas.

Investigation of the structure and properties of the titanium alloy of the Ti-Al-Mo-V-Fe-Cu-Zr-Sn system

International Nuclear Information System (INIS)

Moiseev, V.N.; Dolzhanskij, Yu.M.; Zakharov, Yu.I.; Znamenskaya, E.V.

1979-01-01

The alloys of martensitic type in the Ti-Al-Mo-V-Fe-Cu-Zr-Sn system after heat treatment are investigated. To determine the composition of the titanium alloy methods of mathematical planning of the experiment are applied. Results of mechanical tests of the alloys are presented, as well as coefficients of models for the properties, calculated according to these data. The investigation establishes the composition of a high-strength titanium alloy of a martensitic type, containing 4.5-60 % Al, 2.0-4.0 % Mo, 0.5-1.9 % V, 0.3-1.5 % Fe, 0.3-1.5 % Cu, 1.5-3.0 % Sn, 2.0-4.0 % Zr. The semiproducts, produced by deformation in β-field, after heat treatment have an ultimate strength >=120 kg/mm 2 , satisfactory ductility and reliability. The alloy possesses rather a high heat resistance and can be operated at 400-500 deg C

Electronic structure and interatomic bonding in Al10V

International Nuclear Information System (INIS)

Jahnatek, M; Krajci, M; Hafner, J

2003-01-01

On the basis of ab initio calculations we analysed the electron density distribution in the elementary cell of the compound Al 10 V. We found covalent bonding between certain atoms. The Al-V bonds of enhanced covalency are linked into -Al-V-Al-V- chains that extend over the whole crystal. The chains intersect at each V site and together form a Kagome network of corner-sharing tetrahedra. The large voids of this network are filled by Z 16 Friauf polyhedra consisting of Al atoms only. The skeleton of the Friauf polyhedron has the form of a truncated tetrahedron and consists of 12 strongly bonded Al atoms. These Al-Al bonds also have covalent character. The bonding is dominated by sp 2 hybridization. The centre of the Friauf polyhedron may be empty or occupied by an Al atom. The thermodynamic stability of the phase is investigated. The Al 21 V 2 phase with occupied voids is at low temperatures less stable than Al 10 V. The Al 10 V structure can be considered as a special case of the Al 18 Cr 2 Mg 3 structural class. We have found the same picture of bonding as we report here for Al 10 V for several other aluminium-rich alloys belonging to the Al 18 Cr 2 Mg 3 structural class also

Microstructural investigations of fatigued 12% Cr-steel 1.4914 (X 18 Cr Mo V Nb 12 1)

International Nuclear Information System (INIS)

Gersinska, R.

1992-10-01

The low cycle fatigue properties of a tempered steel X18 Cr Mo V Nb 12 1 (DIN 1.4914) have been investigated at different temperatures, strain amplitudes, mean strains and strain rates. The role of martensite lath structure and of precipitates and dislocations on the strengthening mechanisms and fatigue damage have been analysed. Plastic deformation results in a slip band formation on the surface and in a cellular dislocation structure in the interior of the specimens. A reduced strain rate is causing lower stress amplitudes and greater cells at higher temperatures. At lower temperatures the influence of strain rate is small. Fatigue mechanisms are soon dominant at lower strain rates. REM-investigations of the specimen surfaces are revealing the development of cracks at slip bands. The cracks start always at the surfaces of the specimen, and they are transcristalline in nature. The influence of the ageing temperature has been investigated. A reduced ageing temperature of 600degC results in a higher dislocation density and a lower martensite lath distance in the undeformed material. Strain ageing was initially observed in tensile experiments. The influence of dynamic strain ageing on the mechanical properties and the microstructure of tempered steel 1.4914 is investigated. A correlation of mechanical and microstructural data has been performed. (orig./MM) [de

Evaluación de la longitud de grietas por fatiga mediante la deformación plástica en muestras compactas de tracción empleando el ruido magnético de Barkhausen

Directory of Open Access Journals (Sweden)

de los Reyes-Rodríguez, F.

2013-08-01

Full Text Available In this paper the influence of different parameters on crack length is determined via plastic deformation using magnetic Barkhausen noise; the compact specimens steel used in this study were 12Cr1MoV and 11Cr1Mo, which are used for steam transportation on power plants. The main objective of this paper is to determine the crack length and its incubation time using magnetic Barkhausen noise, which lets to improve the pre-cracking process prior creep crack growth rate test simulating the real conditions of high pressure and temperature of main steam lines. Results showed that mean root square and maximum pick of voltage decrease with plastic deformation for each steel analyzed in this work, on the other hand, with the increasing of plastic deformation, a logic relationship between plastic deformation and spectrum density is observed for mid frequencies values, as well as, a variation of the amplitude, width and shape of the Barkhausen signal envelope.En este trabajo se estudia la influencia de distintos parámetros de la señal del ruido magnético de Barkhausen (RMB en la deformación plástica (DP y, en consecuencia, en la longitud de grieta de probetas compactas de tracción (PCT, fabricadas con aceros 12Cr1MoV y 11Cr1Mo respectivamente, los cuales son empleados principalmente en la industria termoenergética a nivel mundial. Este estudio se lleva a cabo con el objetivo de conocer, por medio de parámetros del RMB, la longitud de la grieta y el momento más próximo a su incubación, lo cual permite perfeccionar el proceso de preagrietamiento, previo el ensayo de velocidad de propagación de grietas a elevadas temperaturas. Se determina el voltaje medio cuadrado (Vrms y el máximo voltaje de pico (MVP de la señal del RMB, magnitudes que decrecen con el incremento de la deformación plástica para cada uno de los aceros estudiados; por otra parte, con el incremento de la deformación plástica se observa, para valores medios de la frecuencia

Análisis de soldabilidad de aceros inoxidables con aceros de medio y bajo carbono por SMAW

Directory of Open Access Journals (Sweden)

José Luddey Marulanda Arevalo

2013-12-01

Full Text Available Se presenta un estudio de la soldabilidad de aceros inoxidables austeníticos AISI 304 y AISI 316 con aceros de bajo y medio carbono AISI 1020 – AISI 1045, empleando como materiales de aporte los electrodos EutecTrode® 52 NG, 54 NG y 57 NG, mediante el proceso de arco eléctrico con electrodo revestido (SMAW. Para analizar la soldabilidad de estos electrodos cuando se realiza la unión de aceros inoxidables con aceros al carbono, se practicaron pruebas metalográficas y ensayos mecánicos de dureza, doblez y tracción, con el fin de observar el comportamiento tanto de la zona afectada térmicamente como del cordón de soldadura, a partir del cambio en las propiedades mecánicas y metalúrgicas en las diferentes regiones de las uniones soldadas. Durante el proceso de soldadura se siguió una especificación del procedimiento de soldadura (WPS, para que los resultados fueran repetibles, minimizando los problemas de agrietamiento en caliente, agrietamiento en frío, formación de fase sigma y precipitación de carburos.

Relationship of bainitic microstructure to impact toughness in Cr-Mo and Cr-W steels

International Nuclear Information System (INIS)

Klueh, R.L.; Alexander, D.J.

1992-01-01

Non-classical bainite microstructures can develop during continuous cooling of low-carbon alloy steels. These differ from classical upper and lower bainite developed by isothermal transformation. Two non-classical bainite microstructures were produced in a 3Cr-1.5Mo0.25V-0.lC steel using different cooling rates after austenitizing--water quenching and air cooling. The carbide-free acicular bainite formed in the quenched steel had a lower ductile-brittle transition temperature (DBTT) than the granular bainite formed in the air-cooled steel. With increasing tempering parameter (defined bv tempering time and temperature), the DBTT of both decreased and approached a common value, although the final value occurred at a much lower tempering parameter for the quenched steel than for the air-cooled steel. The upper-shelf enery was similarly affected by microstructure. These observations along with similar observations in two Cr-W steels indicate that control of the bainite microstructure can be used to optimize strength and toughness

Characterization of the interaction layer in diffusion couples U-Mo-Zr/Al and U-Mo-Zr/Al-A356 at 550 C degrees; Caracterizacion de la zona de interaccion en pares de difusion a 550 grados C U-Mo-Zr/Al y U-Mo-Zr/Al-A356

Energy Technology Data Exchange (ETDEWEB)

Komar Varela, Carolina; Arico, Sergio; Mirandou, Marcela; Balart, Silvia; Gribaudo, Luis [Comision Nacional de Energia Atomica, General San Martin (Argentina). Dept. de Materiales; com, carolinakomar@gmail

2007-07-01

Out-of-pile diffusion experiments were performed between U-7 wt.% Mo-1 wt.% Zr and Al or Al A356 (7,1 wt.% Si) at 550 C degrees. In this work morphological characterization and phase identification on both interaction layers are presented. They were carried out by the use of different techniques: optical and scanning electron microscopy, X-ray diffraction and WDS microanalysis. In the interaction layer U-7 wt.% Mo-1 wt.% Zr/Al, the phases UAl{sub 3}, UAl{sub 4}, Al{sub 20}Mo{sub 2}U and Al{sub 43}Mo{sub 4}U{sub 6} were identified. Similar results in the interaction layer of the U-7 % Mo/Al at 580 C degrees were previously obtained. In the interaction layer U-7 wt.% Mo-1 wt.% Zr/Al A356, the phases U(Al,Si){sub 3} with 25 at.% Si and Si{sub 5}U{sub 3} were identified. This last phase, with a higher Si concentration, was identified with X-ray diffraction synchrotron radiation performed at the National Synchrotron Light Laboratory, Campinas, Brazil. (author) [Spanish] Se realizaron experiencias fuera de reactor en pares de difusion quimica U-7 % Mo-1 % Zr/Al y U-7 % Mo-1 % Zr/Al A356. En este trabajo se presentan los resultados de la caracterizacion morfologica e identificacion de fases presentes en la zona de interaccion que se forma al ser sometidos a un tratamiento isotermico de 1,5 h a 550 grados C. Las tecnicas utilizadas fueron: microscopia optica y electronica de barrido, difraccion de rayos X y microanalisis cuantitativo por sonda electronica. En la zona de interaccion correspondiente al par U-7 % Mo-1 % Zr/Al se identificaron las fases UAl{sub 3}, UAl{sub 4}, Al{sub 20}Mo{sub 2}U y Al{sub 43}Mo{sub 4}U{sub 6}. Estas cuatro fases fueron identificadas en pares U-7 % Mo/Al a 580 grados C en trabajos anteriores. En la zona de interaccion correspondiente al par U-7 % Mo-1 % Zr/Al A356 se identificaron las fases U(Al,Si){sub 3} (con una concentracion de 25 %at.Si) y Si{sub 5}U{sub 3}. Este compuesto rico en Si solo pudo ser identificado mediante la utilizacion de

Computation of beam quality parameters for Mo/Mo, Mo/Rh, Rh/Rh, and W/Al target/filter combinations in mammography

International Nuclear Information System (INIS)

Kharrati, Hedi; Zarrad, Boubaker

2003-01-01

A computer program was implemented to predict mammography x-ray beam parameters in the range 20-40 kV for Mo/Mo, Mo/Rh, Rh/Rh, and W/Al target/filter combinations. The computation method used to simulate mammography x-ray spectra is based on the Boone et al. model. The beam quality parameters such as the half-value layer (HVL), the homogeneity coefficient (HC), and the average photon energy were computed by simulating the interaction of the spectrum photons with matter. The checking of this computation was done using a comparison of the results with published data and measured values obtained at the Netherlands Metrology Institute Van Swinden Laboratorium, National Institute of Standards and Technology, and International Atomic Energy Agency. The predicted values with a mean deviation of 3.3% of HVL, 3.7% of HC, and 1.5% of average photon energy show acceptable agreement with published data and measurements for all target/filter combinations in the 23-40 kV range. The accuracy of this computation can be considered clinically acceptable and can allow an appreciable estimation for the beam quality parameters

Creep properties and simulation of weld repaired low alloy heat resistant CrMo and Mo steels at 540 deg C. Sub project 1 - Ex-serviced parent metal and virgin weld metals

Energy Technology Data Exchange (ETDEWEB)

Rui Wu; Storesund, Jan; Borggreen, Kjeld; Weilin Zang

2006-10-15

Many existing power generating and process plants, where low alloy heat resistant CrMo(V) steels are extensively used for critical components, have exceeded their design lifetime of usually 100,000 hours. Assessment of residual lifetime and extension of economic life by weld repair have become increasingly important and attractive. This project aims at i) performing weld repair and determining the degree of mismatching, ii) evaluating the creep properties of weld repairs, iii) analysing creep behaviour of weld repair and providing necessary data for further reliable simulations of weld repair creep behaviour in long term service, and iv), simulating and assessing lifetime and creep damage evolution of weld repair. Weld repair using 10 CrMo 9 10, 13 CrMo 4 4 and 15 Mo 3 consumables has been carried out in a service-exposed 10 CrMo 9 10 pipe. Creep specimens have been extracted from the service-exposed 10 CrMo 9 10 parent metal (PM), from the virgin 10 CrMo 9 10 weld metal (WM), from the virgin 13 CrMo 4 4 WM as well as from the virgin 15 Mo 3 WM. Iso-thermal uniaxial creep tests have been performed at 540 deg C in air. Pre- and post-metallography are carried out on the selected samples. FEM simulations using obtained creep data are executed. Pre-test metallography shows normal and acceptable weld repairs at given welding conditions. Creep tests demonstrate that the virgin 10 CrMo 9 10, 13 CrMo 4 4 and 15 Mo 3 WMs have apparently longer creep lifetime than the service-exposed CrMo 9 10 PM at higher stresses than 110 MPa. Among the weld metals, the longest creep lifetime is found in 10 CrMo 9 10. Higher creep strength and lower creep strain rate in the weld metals indicate an overmatch weld. At 95 MPa, however, lifetime of 13 CrMo 4 4 WM is surprisingly short (factors which may shorten lifetime are discussed and one more test will start to verify creep strength at low stress) and tests are still running for other two weld metals. More results regarding low stress

V1.42In1.83Mo15Se19

Directory of Open Access Journals (Sweden)

Michel Potel

2010-10-01

Full Text Available The structure of the title compound, vanadium indium pentadecamolybdenum nonadecaselenide, V1.42In1.83Mo15Se19, is isotypic with In2.9Mo15Se19 [Grüttner et al. (1979. Acta Cryst. B35, 285–292]. It is characterized by two cluster units Mo6Sei8Sea6 and Mo9Sei11Sea6 (where i represents inner and a apical atoms that are present in a 1:1 ratio. The cluster units are centered at Wyckoff positions 2b and 2c and have point-group symmetry overline{3} and overline{6}, respectively. The clusters are interconnected through additional Mo—Se bonds. In the title compound, the V3+ cations replace the trivalent indium atoms present in In2.9Mo15Se19, and a deficiency is observed on the monovalent indium site. One Mo, one Se and the V atom are situated on mirror planes, and two other Se atoms and the In atom are situated on threefold rotation axes.

Corrosion resistance of Ni-Cr-Mo alloys. Chemical composition and metallurgical condition's effects

International Nuclear Information System (INIS)

Zadorozne, N.S.; Rebak, Raul B.

2009-01-01

Ni-Cr-Mo alloys offer an outstanding corrosion resistance in a wide variety of highly-corrosive environments. This versatility is due to the excellent performance of nickel in hot alkaline solutions and the beneficial effect of chromium and molybdenum in oxidizing and reducing conditions, respectively. Alloy C-22 (22 % Cr-13 % Mo-3% W) is a well known versatile member of this family. Due to its excellent corrosion resistance in a wide variety of environments, Alloy C-22 has been selected for the fabrication of the corrosion-resistant outer shell of the high-level nuclear waste container. The increasing demand of the industry for corrosion resistant alloys with particular properties of corrosion and mechanical resistance has led to the development of new alloys. Alloy C-22HS (Ni-21 % Cr-17 % Mo) is a new high-strength corrosion resistant material recently developed and introduced into the market. This alloy provides a corrosion resistance comparable with that of other C-type alloys, and it can also be age hardened to effectively double its yield strength. HASTELLOY HYBRID-BC1 (Ni-22 % Mo-15 % Cr) is a new development intended for filling the gap between Ni-Mo and Ni-Cr-Mo alloys. This novel alloy is able to withstand HCl and H 2 SO 4 , even in the presence of dissolved oxygen and other oxidizing species. Its resistance to chloride-induced pitting corrosion, crevice corrosion and stress corrosion cracking is also remarkable. Thermal aging of Ni-Cr-Mo alloys leads to microstructure changes depending on the temperature range and exposure time at temperature. A Long Range Ordering (LRO) reaction can occur in the range of 350 C degrees to 600 C degrees, producing an ordered Ni 2 (Cr,Mo) phase. This ordering reaction does not seem to affect the corrosion resistance and produces only a slight loss in ductility. LRO transformation is homogeneous and has proven to be useful to fabricate the age-hard enable Alloy C22-HS. Tetrahedral Close Packed (TCP) phases, like μ, σ and

Phase relations in the systems M2MoO4-Cr2(MoO4)3-Zr(MoO4)2 (M=Li, Na, or Rb)

International Nuclear Information System (INIS)

Bazarov, B.G.; Chimitova, O.D.; Bazarova, Ts.T.; Arkhincheeva, S.I.; Bazarova, Zh.G.

2008-01-01

Phase equilibria in the systems M 2 MoO 4 -Cr 2 (MoO 4 ) 3 -Zr(MoO 4 ) 2 (M=Li, Na, or Rb) were investigated by X-ray powder diffraction analysis, DTA, and IR spectroscopy. The subsolidus structure of the phase diagrams of the systems under study was established. Two phases are formed in the Rb 2 MoO 4 -Cr 2 (MoO 4 ) 3 -Zr(MoO 4 ) 2 system with the molar ratios of the starting components equal to 5:1:1 (S 2 ) and 1:1:1 (S 1 ). Proceeding from isostructural character of Rb 5 FeHf(MoO 4 ) 6 and S 2 , the unit cell parameters are determined for S 2 [ru

Characterization on the Microstructure Evolution and Toughness of TIG Weld Metal of 25Cr2Ni2MoV Steel after Post Weld Heat Treatment

Directory of Open Access Journals (Sweden)

Xia Liu

2018-03-01

Full Text Available The microstructure and toughness of tungsten inert gas (TIG backing weld parts in low-pressure steam turbine welded rotors contribute significantly to the total toughness of the weld metal. In this study, the microstructure evolution and toughness of TIG weld metal of 25Cr2Ni2MoV steel low-pressure steam turbine welded rotor under different post-weld heat treatment (PWHT conditions are investigated. The fractography and microstructure of weld metal after PWHT are characterized by optical microscope, SEM, and TEM, respectively. The Charpy impact test is carried out to evaluate the toughness of the weld. The optical microscope and SEM results indicate that the as-welded sample is composed of granular bainite, acicular ferrite and blocky martensite/austenite (M-A constituent. After PWHT at 580 °C, the blocky M-A decomposes into ferrite and carbides. Both the number and size of precipitated carbides increase with holding time. The impact test results show that the toughness decreases dramatically after PWHT and further decreases with holding time at 580 °C. The precipitated carbides are identified as M23C6 carbides by TEM, which leads to the dramatic decrease in the toughness of TIG weld metal of 25Cr2Ni2MoV steel.

Postirradiation fracture toughness tests of ESR alloy HT-9 and modified 9Cr-1Mo alloy from UBR reactor experiments

International Nuclear Information System (INIS)

Hawthorne, J.R.; Reed, J.R.; Sprague, J.A.

1984-01-01

Alloy HT-9 and Modified 9Cr-1Mo are being evaluated for potential applications as first wall materials in magnetic fusion reactors. Objectives of the current research task were to test fatigue-precracked Charpy-V (PCC/sub v/) specimens from representative plates irradiated in the UBR reactor at 149 0 C or 300 0 C, and, to compare the results against postirradiation notch ductility data developed previously for the materials. Both plates represent electroslag refined (ESR) melt processing. PCC/sub v/ specimens of Alloy HT-9 and Modified 9Cr-1Mo alloy were irradiated at 300 0 C and 149 0 C, respectively, to approx.0.8 X 10 20 n/cm 2 , E > 0.1 MeV. During this period, postirradiation tests for fracture toughness were completed and results compared to notch ductility determinations from standard Charpy-V (C/sub v/) specimens irradiated in the same reactor experiments. Fracture surface examinations by SEM are also reported

Structural, optical, and thermal properties of MAX-phase Cr2AlB2

Science.gov (United States)

Li, Xiao-Hong; Cui, Hong-Ling; Zhang, Rui-Zhou

2018-04-01

First-principles calculations of the structural, optical, and thermal properties of Cr2AlB2 are performed using the pseudopotential plane-wave method within the generalized gradient approximation (GGA). Calculation of the elastic constant and phonon dispersion indicates that Cr2AlB2 is mechanically and thermodynamically stable. Analysis of the band structure and density of states indicates that Cr2AlB2 is metallic. The thermal properties under increasing temperature and pressure are investigated using the quasi-harmonic Debye model. The results show that anharmonic effects on Cr2AlB2 are important at low temperature and high pressure. The calculated equilibrium primitive cell volume is 95.91 Å3 at T = 300 K, P = 0 GPa. The ability of Cr2AlB2 to resist volume changes becomes weaker with increasing temperature and stronger with increasing pressure. Analysis of optical properties of Cr2AlB2 shows that the static dielectric function of Cr2AlB2 is 53.1, and the refractive index n 0 is 7.3. If the incident light has a frequency exceeding 16.09 eV, which is the plasma frequency of Cr2AlB2, Cr2AlB2 changes from metallic to dielectric material.

Oxide Morphology of a FeCrAl Alloy, Kanthal APMT, following Extended Aging at 300-600C

Energy Technology Data Exchange (ETDEWEB)

Li, Nan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Parker, Stephen Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wood, Elizabeth Sooby [Univ. of Texas, San Antonio, TX (United States)

2017-09-19

Iron-chromium-aluminum (FeCrAl) alloys are of interest to the nuclear materials community due to their resistance to high temperature steam oxidation under accident conditions. The present work investigates oxide formation at temperatures relevant to light water reactor cladding operation following extended aging to assess growth kinetics, chemical composition, and microstructure of oxide formation on a commercial FeCrAl alloy, Fe-21wt.%Cr-5wt.%Al-3wt.%Mo (Kanthal APMT). Aging treatments were performed for 100-1000 hours in stagnant air at 300, 400, 500, and 600 °C, respectively. Oxide growth behavior under the investigated conditions follows a logarithmic time dependence. When the oxidization temperature is 400 °C or below, the oxide is amorphous. At 500 °C, isolated crystalline regions start to appear during short period aging time and expand with extended exposures. Crystalline α-Al2O3 oxide film develops at 600 °C and the correlated logarithmic rate constant decreases significantly, indicating enhanced oxidation resistance of the formed oxide film. In addition, Mo segregation at grain boundaries has been observed when the aging temperature exceeds 500 °C. The results of this study can be viewed as an upper bounding result for potential oxide coarsening during reactor operation.

Toughness of 2,25Cr-1Mo steel and weld metal

Science.gov (United States)

Acarer, Mustafa; Arici, Gökhan; Acar, Filiz Kumdali; Keskinkilic, Selcuk; Kabakci, Fikret

2017-09-01

2,25Cr-1Mo steel is extensively used at elevated temperature structural applications in fossil fire power plants for steam pipes, nozzle chambers and petrochemical industry for hydrocracking unit due to its excellent creep resistance and good redundant to oxidation. Also they should have acceptable weldability and toughness. The steels are supplied in quenched and tempered condition and their welded components are subjected to post-weld heat treatment (PWHT). Tempering process is carried out at 690-710°C to improve toughness properties. However they are sensitive to reheat cracking and temper embrittlement. To measure temper embrittlement of the steels and their weld metal, temper embrittlement factor and formula (J factor - Watanabe and X formula- Bruscato) are used. Step cooling heat treatment is also applied to determine temper embrittlement. In this study, toughness properties of Cr Mo (W) steels were reviewed. Also transition temperature curves of 2,25Cr-1Mo steel and its weld metal were constructed before and after step cool heat treatment as experimental study. While 2,25Cr-1Mo steel as base metal was supplied, all weld metal samples were produced in Gedik Welding Company. Hardness measurements and microstructure evaluation were also carried out.

Effect of electroslag remelting on carbides in 8Cr13MoV martensitic stainless steel

Science.gov (United States)

Zhu, Qin-tian; Li, Jing; Shi, Cheng-bin; Yu, Wen-tao

2015-11-01

The effect of electroslag remelting (ESR) on carbides in 8Cr13MoV martensitic stainless steel was experimentally studied. Phases precipitated from liquid steel during solidification were calculated using the Thermo-Calc software. The carbon segregation was analyzed by original position analysis (OPA), and the carbides were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), energy- dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results indicated that more uniform carbon distribution and less segregation were obtained in the case of samples subjected to the ESR process. After ESR, the amount of netty carbides decreased significantly, and the chromium and vanadium contents in the grain-boundary carbides was reduced. The total area and average size of carbides were obviously smaller after the ESR process. In the sample subjected to ESR, the morphology of carbides changed from lamellar and angular to globular or lump, whereas the types of carbides did not change; both M23C6 and M7C3 were present before and after the ESR process.

Microstructure and Corrosion Resistance Characteristics of Cr-Co-Mo Alloys Designed for Prosthetic Materials

Directory of Open Access Journals (Sweden)

Augustyn-Pieniążek J.

2013-12-01

Full Text Available W pracy przedstawiono wyniki badań mikroskopowych dwóch stopów: Co-Cr-Mo i Co-Cr-W-Mo wraz z ilościową ana- lizą punktową składu chemicznego przy wykorzystaniu mikroanalizatora rentgenowskiego EDS. W ramach pracy wykonano również badania odporności korozyjnej stopów w środowisku sztucznej śliny. Mikrostruktura badanych stopów miała budowę dendrytyczną. W przestrzeniach międzydendrytycznych występowała eutektyka składająca się z węglików stopowych i auste- nitu kobaltowego. Osnowę dendrytyczną stanowił roztwór stały chromu, molibdenu i węgla w kobalcie (yCo, zaś wydzielenia występujące w obszarach międzydendrytycznych były bogate w Cr i Mo - w przypadku stopu Co-Cr-Mo oraz W i Mo - w przypadku stopu Co-Cr-W-Mo. Analizowane materiały wykazywały zbliżone przebiegi krzywych polaryzacji. Z otrzymanych wartości potencjału bezprądowego oraz na podstawie szerokiego obszaru pasywacji tych stopów można wnioskować o ich wysokiej odporności korozyjnej w badanym środowisku.

The Relationships Between Microstructure, Tensile Properties and Fatigue Life in Ti-5Al-5V-5Mo-3Cr-0.4Fe (Ti-5553)

Science.gov (United States)

Foltz, John W., IV

beta-titanium alloys are being increasingly used in airframes as a way to decrease the weight of the aircraft. As a result of this movement, Ti-5Al-5V-5Mo-3Cr-0.4Fe (Timetal 555), a high-strength beta titanium alloy, is being used on the current generation of landing gear. This alloy features good combinations of strength, ductility, toughness and fatigue life in alpha+beta processed conditions, but little is known about beta-processed conditions. Recent work by the Center for the Accelerated Maturation of Materials (CAMM) research group at The Ohio State University has improved the tensile property knowledge base for beta-processed conditions in this alloy, and this thesis augments the aforementioned development with description of how microstructure affects fatigue life. In this work, beta-processed microstructures have been produced in a Gleeble(TM) thermomechanical simulator and subsequently characterized with a combination of electron and optical microscopy techniques. Four-point bending fatigue tests have been carried out on the material to characterize fatigue life. All the microstructural conditions have been fatigue tested with the maximum test stress equal to 90% of the measured yield strength. The subsequent results from tensile tests, fatigue tests, and microstructural quantification have been analyzed using Bayesian neural networks in an attempt to predict fatigue life using microstructural and tensile inputs. Good correlation has been developed between lifetime predictions and experimental results using microstructure and tensile inputs. Trained Bayesian neural networks have also been used in a predictive fashion to explore functional dependencies between these inputs and fatigue life. In this work, one section discusses the thermal treatments that led to the observed microstructures, and the possible sequence of precipitation that led to these microstructures. The thesis then describes the implications of microstructure on fatigue life and

Manufacturing of FeCrAl/Zr Dual Layer tube for its application to LWR Fuel cladding

Energy Technology Data Exchange (ETDEWEB)

Park, Dong Jun; Lim, Do Wan; Jung, Yang Il; Kim, Hyun Gil; Park, Jeong Yong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-10-15

Many advanced materials such as MAX phases, Mo, SiC, and Fe-based alloys are being considered a possible candidate to substitute the Zr-based alloy cladding has been used in light water reactors. Among the proposed candidate materials, Fe-based alloy is one of the most promising candidates owing to its excellent formability, very good high strength, and corrosion resistance at high temperature. However, neutron cross section of FeCrAl alloy is much higher than that of existing Zr-based alloys. In this study, FeCrAl/Zr dual layer tube was manufactured by using a hot isostatic pressing (HIP) method. The thickness of outer FeCrAl layer was varied from 50 to 250 μm but all the FeCrAl/Zr dual layer tube samples maintained its total thickness of 570 μm. For a detailed microstructural characterization of FeCrAl/Zr dual layer, polarized optical microscopy and scanning electron microscopy (SEM) study carried out and its mechanical property was measured by ring compression test. FeCrAl/Zr dual layer tube sample was successfully manufactured with good adhesion between both layers. Inter layer showing gradual element variation was observed at interface. Result obtained from simulated LOCA test indicates that FeCrAl/Zr dual layer tube may maintain its integrity during LOCA and its accident tolerance had greatly improved compared to that of Zr-based alloy.

U-Mo/Al-Si interaction: Influence of Si concentration

International Nuclear Information System (INIS)

Allenou, J.; Palancher, H.; Iltis, X.; Cornen, M.; Tougait, O.; Tucoulou, R.; Welcomme, E.; Martin, Ph.; Valot, C.; Charollais, F.; Anselmet, M.C.; Lemoine, P.

2010-01-01

Within the framework of the development of low enriched nuclear fuels for research reactors, U-Mo/Al is the most promising option that has however to be optimised. Indeed at the U-Mo/Al interfaces between U-Mo particles and the Al matrix, an interaction layer grows under irradiation inducing an unacceptable fuel swelling. Adding silicon in limited content into the Al matrix has clearly improved the in-pile fuel behaviour. This breakthrough is attributed to an U-Mo/Al-Si protective layer around U-Mo particles appeared during fuel manufacturing. In this work, the evolution of the microstructure and composition of this protective layer with increasing Si concentrations in the Al matrix has been investigated. Conclusions are based on the characterization at the micrometer scale (X-ray diffraction and energy dispersive spectroscopy) of U-Mo7/Al-Si diffusion couples obtained by thermal annealing at 450 deg. C. Two types of interaction layers have been evidenced depending on the Si content in the Al-Si alloy: the threshold value is found at about 5 wt.% but obviously evolves with temperature. It has been shown that for Si concentrations ranging from 2 to 10 wt.%, the U-Mo7/Al-Si interaction is bi-layered and the Si-rich part is located close to the Al-Si for low Si concentrations (below 5 wt.%) and close to the U-Mo for higher Si concentrations. For Si weight fraction in the Al alloy lower than 5 wt.%, the Si-rich sub-layer (close to Al-Si) consists of U(Al, Si) 3 + UMo 2 Al 20 , when the other sub-layer (close to U-Mo) is silicon free and made of UAl 3 and U 6 Mo 4 Al 43 . For Si weight concentrations above 5 wt.%, the Si-rich part becomes U 3 (Si, Al) 5 + U(Al, Si) 3 (close to U-Mo) and the other sub-layer (close to Al-Si) consists of U(Al, Si) 3 + UMo 2 Al 20 . On the basis of these results and of a literature survey, a scheme is proposed to explain the formation of different types of ILs between U-Mo and Al-Si alloys (i.e. different protective layers).

Propiedades mecánicas del acero de refuerzo utilizado en Colombia Propiedades mecánicas del acero de refuerzo utilizado en Colombia

OpenAIRE

Victoria González Quintana; Juan Carlos Botero; Roberto Rochel; Julián Vidal; Martha Cecilia Alvarez Uribe

2005-01-01

Se presentan resultados del análisis estadístico aplicado al estudio experimental que de- termina las propiedades mecánicas de aceros colombianos sometidos a cargas monotónicas de tracción. Se obtienen curvas típicas de esfuerzo-deformación que permiten caracterizar aceros nacionales estudiados haciendo énfasis en las variables que determinan el cambio de comportamiento del materialA statistical analysis applied to a experimental study that determines the mechanical properties of steels produ...

Microstructure, state of internal stress and corrosion resistance of the short-time laser heat-treated nitrogen high-alloyed tool steel X30CrMoN151; Mikrostruktur, Eigenspannungszustand und Korrosionsbestaendigkeit des kurzzeitlaserwaermebehandelten hochstickstofflegierten Werkzeugstahls X30CrMoN151

Energy Technology Data Exchange (ETDEWEB)

Bohne, C. (ed.)

2000-07-01

This study compares the crystalline structure, state of internal stress and chemical properties of the high-alloyed nitrogen tool steel X30CrMoN15 1 and conventional cold work steel X39CrMo17 1. Transformation points A{sub c}1b and A{sub c}1e were calculated from residual austenite analysis and the c{sub m}/a{sub m} martensite ratios for various heating rates. This was used to generate a TTA (time-temperature-austenitisation) graph for X30CrMoN15 1 for the first time. Transmission electron microscopy and small-angle neutron scattering show that precipitates in nitrogen high-alloyed steel X30CrMoN15 1 can be eliminated completely by short-time laser heat treatment. The corrosion tests show that in contrast to X39CrMo17 1 X30CrMoN15 1 reacts more sensitively to parameter changes during short-time heat treatment in oxidising acid at pH 5-6. [German] Im Rahmen der Arbeit werden die Gefuegeausbildung, Eigenspannungen und chemische Eigenschaften des hochstickstofflegierten Werkzeugstahls X30CrMoN15 1 und des konventionellen Kaltarbeitsstahls X39CrMo17 1 verglichen. Aus den Restaustenitanalysen und den c{sub m}/a{sub m}-Verhaeltnissen des Martensits konnten die Umwandlungspunkte A{sub c1b} und A{sub c1e} fuer verschiedene Aufheizraten bestimmt und daraus ein bisher nicht bekanntes ZTA-Schaubild fuer den X30CrMoN15 1 erstellt werden. Transmissionselektronenmikroskopie und Neutronenkleinwinkelstreuung zeigen, dass sich die Ausscheidungen im hochstickstofflegierten Stahl X30CrMoN14 1 durch die Kurzzeitlaserwaermebehandlung vollstaendig aufloesen koennen. Die Korrosionsversuche zeigen, dass im Gegensatz zum X39CrMo17 1 der X30CrMoN15 1 in oxidierender Saeure bei pH 5-6 empfindlicher auf Parameteraenderungen bei der Kurzzeitwaermebehandlung reagiert. (orig.)

Type-I band alignment at MoS2/In0.15Al0.85N lattice matched heterojunction and realization of MoS2 quantum well

KAUST Repository

Tangi, Malleswarara

2017-08-31

The valence and conduction band offsets (VBO and CBO) at the semiconductor heterojunction are crucial parameters to design the active region of contemporary electronic and optoelectronic devices. In this report, to study the band alignment parameters at the In0.15Al0.85N/MoS2 lattice matched heterointerface, large area MoS2 single layers are chemical vapor deposited on molecular beam epitaxial grown In0.15Al0.85N films and vice versa. We grew InAlN having an in-plane lattice parameter closely matching with that of MoS2. We confirm that the grown MoS2 is a single layer from optical and structural analyses using micro-Raman spectroscopy and scanning transmission electron microscopy. The band offset parameters VBO and CBO at the In0.15Al0.85N/MoS2 heterojunction are determined to be 2.08 ± 0.15 and 0.60 ± 0.15 eV, respectively, with type-I band alignment using high-resolution x-ray photoelectron spectroscopy in conjunction with ultraviolet photoelectron spectroscopy. Furthermore, we design a MoS2 quantum well structure by growing an In0.15Al0.85N layer on MoS2/In0.15Al0.85N type-I heterostructure. By reducing the nitrogen plasma power and flow rate for the overgrown In0.15Al0.85N layers, we achieve unaltered structural properties and a reasonable preservation of photoluminescence intensity with a peak width of 70 meV for MoS2 quantum well (QW). The investigation provides a pathway towards realizing large area, air-stable, lattice matched, and eventual high efficiency In0.15Al0.85N/MoS2/In0.15Al0.85N QW-based light emitting devices.

Comparison of low-cycle fatigue data of 2 1/4%CrMo steels

International Nuclear Information System (INIS)

Sanderson, S.J.; Petrequin, P.; Nieuwland, H.C.D.

Data files have been produced on international strain-controlled fatigue information available for 2 1/4%CrMo steels; data assessment from these files is treated in three categories viz: annealed and isothermally annealed 2 1/4%Cr1%Mo steel; normalised and tempered and quenched and tempered 2 1/4%Cr1%Mo steel; and 2 1/4%CrMo variants. The available data have been considered generally in terms of total strain range vs. cycles to failure (Nsub(f)), tensile stress at Nsub(f)/2 vs. cycles to failure and time to failure vs. cycles to failure. Where possible the continuous cycling data have been statistically analysed in terms of the elastic and plastic strain components and cycles to failure to yield best-fit equations over defined temperature (T) regimes viz: T <= 427 deg. C, 427 deg. C < T <= 550 deg. C. and 550 deg. C < T <= 600 deg. C. The behaviour of the steels within the various classifications is discussed. (author)

Synthesis and microstructure characterization of Ni-Cr-Co-Ti-V-Al high entropy alloy coating on Ti-6Al-4V substrate by laser surface alloying

International Nuclear Information System (INIS)

Cai, Zhaobing; Jin, Guo; Cui, Xiufang; Liu, Zhe; Zheng, Wei; Li, Yang; Wang, Liquan

2016-01-01

Ni-Cr-Co-Ti-V-Al high-entropy alloy coating on Ti-6Al-4V was synthesized by laser surface alloying. The coating is composed of a B2 matrix and (Co, Ni)Ti 2 compounds with few β-Ti phases. Focused ion beam technique was utilized to prepare TEM sample and TEM observations agree well with XRD and SEM results. The formation of HEA phases is due to high temperature and rapid cooling rate during laser surface alloying. The thermodynamic parameters, ΔH mix , ΔS mix and δ as well as Δχ, should be used to predict the formation of the BCC solid solution, but they are not the strict criteria. Especially when Δχ reaches a high value (≥ 10%), BCC HEA will be partially decomposed, leading to the formation of (Co, Ni)Ti 2 compound phases. - Highlights: •Preparing HEA coating on Ti-6Al-4V by laser surface alloying is successful. •The synthesized HEA coating mainly consists of BCC HEA and (Co, Ni)Ti 2 compounds. •FIB technology was used to prepare the sample for TEM analysis. • ΔH mix , ΔS mix and δ as well as Δχ, should be all used to predict the formation of solid solution.

The effects of Ni, Mo, Ti and Si on the mechanical properties of Cr free Mn steel (Fe-25Mn-5Al-2C)

International Nuclear Information System (INIS)

Schuon, S.R.

1982-01-01

The FeMnAlC alloys may hold potential as Cr-free replacements for high strategic material iron base superalloys, but little is known about their intermediate temperature (650 C to 870 C) mechanical properties. The effects of alloying elements on the mechanical properties of model FeMnAlC alloys were studied. Results showed that modified FeMnAlC alloys had promising short term, intermediate temperature properties but had relatively poor stress rupture lives at 172 MPa and 788 C. Room temperature and 788 C tensile strength of FeMnAlC alloys were better than common cast stainless steels. Changes in room temperature tensile and 788 C tensile strength and ductility, and 788 C stress rupture life were correlated with changes in Ni, Mo, Ti, and Si levels due to alloying effects on interstitial carbon levels and carbide morphology. Fe-25Mn-5Al-2C had a very poor stress rupture life at 172 MPa and 788 C. Addition of carbide-forming elements improved the stress rupture life

Processing and Mechanical Properties of NiAl-Based In-Situ Composites. Ph.D. Thesis Final Report

Science.gov (United States)

Johnson, David Ray

1994-01-01

In-situ composites based on the NiAl-Cr eutectic system were successfully produced by containerless processing and evaluated. The NiAl-Cr alloys had a fibrous microstructure while the NiAl-(Cr,Mo) alloys containing 1 at. percent or more molybdenum exhibited a lamellar structure. The NiAl-28Cr-6Mo eutectic displays promising high temperature strength while still maintaining a reasonable room temperature fracture toughness when compared to other NiAl-based materials. The Laves phase NiAlTa was used to strengthen NiAl and very promising creep strengths were found for the directionally solidified NiAl-NiAlTa eutectic. The eutectic composition was found to be near NiAl-15.5Ta (at. percent) and well aligned microstructures were produced at this composition. An off-eutectic composition of NiAl-14.5Ta was also processed, consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of these two phase alloys was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Polyphase in-situ composites were generated by directional solidification of ternary eutectics. The systems investigated were the Ni-Al-Ta-X (X=Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and both the eutectic composition and temperature were determined. Of these ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr,Al)NiTa-Cr eutectic was intermediate between those of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.

Effect of alloying element on mechanical and oxidation properties of Ni-Cr-Mo-Co alloys at 950 °C

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong-Jin, E-mail: djink@kaeri.re.kr; Jung, Su Jin; Mun, Byung Hak; Kim, Sung Woo; Lim, Yun Soo; Kim, Woo Gon; Hwang, Seong Sik; Kim, Hong Pyo

2016-12-01

Graphical abstract: Mo rich carbide was developed leading to significant increase of elongation to rupture and creep rupture time of Ni-Cr-Co-Mo alloy at 950 °C. Al addition improved corrosion resistance caused by enhancement of oxide/matrix interface stability. Abstract: The very-high-temperature reactor (VHTR) is a promising Generation-IV reactor design given its clear advantage regarding the production of massive amounts of hydrogen and in generating highly efficient electricity despite the fact that a material challenge remains at a high temperature of around 950 °C, where hydrogen production is possible under high pressure. In particular, among the many components composing a VHTR, the temperature of the intermediate heat exchanger (IHX) is expected to be the highest, with a coolant environment of up to 950 °C. Therefore, this work focuses on the mechanical and oxidation properties at 950 °C as a function of the alloying elements of Cr, Co, Mo, Al, and Ti constituting nickel-based alloys fabricated in a laboratory. The tensile, creep, and oxidation properties of the alloying elements were analyzed with SEM, TEM-EDS, and by assessing the weight change.

Selección automatizada de electrodos para la soldadura manual de los aceros al carbono

Directory of Open Access Journals (Sweden)

Alexander Velázquez Font

2008-01-01

Full Text Available Se aborda lo relativo a un sistema para la selección automatizada de electrodos en la soldadura de los aceros al carbono. Se inicia con una breve revisión de los problemas que presentan estos en su soldabilidad y los factores concernientes a la selección correcta del electrodo en los mismos. En el mismo se expone el fundamento teórico sobre el diseño del sistema el cual da solución a lo anteriormente expuesto. En la elaboración del software se tiene en cuenta los siguientes principios: propiedades mecánicas de la unión soldada, tipo de revestimiento, posición de la soldadura, etc. Se tienen en cuenta en el trabajo diferentes firmas y normas de fabricantes de electrodos y países que mas se utilizan en la industria mecánica en Cuba. El software tiene la ventaja de ser sencillo, rápido y seguro, garantizando la selección correcta de los electrodos para cada caso y situación. El software supone que el usuario no tenga que tener conocimientos profundos de soldadura, debido a que el sistema se encarga de la mayor parte de las decisiones para la selección del electrodo, procedimiento que con métodos convencionales, exigen del usuario una determinada experiencia en la selección de estos materiales para la soldadura de los aceros al carbono.

Creep constitutive equations for a 0.5Cr 0.5 Mo 0.25V ferritic steel in the temperature range 565 deg. C-675 deg. C

International Nuclear Information System (INIS)

Mustata, R.; Hayhurst, D.R.

2005-01-01

A two damage state variable model is used to describe the softening mechanisms, damage initiation and growth for a low alloy ferritic steel 1/2Cr-1/2Mo-1/4V at 565 and 590 deg. C within the Continuum Damage Mechanics framework. The level of complexity of the constitutive equations and the degree of coupling through damage is high and it is difficult to calibrate values of the constitutive constants without recourse to optimisation techniques. A methodology for the analysis of uni-axial experimental data, coupled with a traditional gradient-based optimisation technique, is presented for the unique determination of the constitutive constants. Two sets of experimental data on parent material are used for inversion purposes: at 565 deg. C, c.f. Cane [Cane BJ. Collaborative programme on the corelation of test data for high temperature design of welded steam pipes. Presentation and analysis of the material data. Note No. RD/L/2101N81, March, CEGB Laboratory; 1981]; and, at 590 deg. C, c.f. Miller [Miller DA. Private communication: 'Creep rupture testing of Cr M V pipe steel. ERA Project 63-01-040320009'. Barnwood, Gloucs, UK: British Energy; 2000]. The variation of the constitutive parameters with temperature in the range 565-590 deg. C has been deduced by considering the values of constitutive parameters for the same alloy deduced by Perrin and Hayhurst [Perrin IJ, Hayhurst DR. Creep constitutive equations for a 0.5Cr-0.5Mo-0.25V ferritic steel in the temperature range 600-675 deg. C. J Strain Anal 1996;31:299-314] in the temperature range 620-675 deg. C

On the Path to Optimizing the Al-Co-Cr-Cu-Fe-Ni-Ti High Entropy Alloy Family for High Temperature Applications

Directory of Open Access Journals (Sweden)

Anna M. Manzoni

2016-03-01

Full Text Available The most commonly investigated high entropy alloy, AlCoCrCuFeNi, has been chosen for optimization of its microstructural and mechanical properties by means of compositional changes and heat treatments. Among the different available optimization paths, the decrease of segregating element Cu, the increase of oxidation protective elements Al and Cr and the approach towards a γ-γ′ microstructure like in Ni-based superalloys have been probed and compared. Microscopical observations have been made for every optimization step. Vickers microhardness measurements and/or tensile/compression test have been carried out when the alloy was appropriate. Five derived alloys AlCoCrFeNi, Al23Co15Cr23Cu8Fe15Ni16, Al8Co17Cr17Cu8Fe17Ni33, Al8Co17Cr14Cu8Fe17Ni34.8Mo0.1Ti1W0.1 and Al10Co25Cr8Fe15Ni36Ti6 (all at.% have been compared to the original AlCoCrCuFeNi and the most promising one has been selected for further investigation.

Metallographic detection of carbides in the steel X 41 CrMoV 51 after different austenizing processes

International Nuclear Information System (INIS)

Fleer, R.; Rickel, J.; Draugelates, U.

1979-01-01

The etchant most suitable for clearly revealing the carbide particles in the developed hardened structure was determined by comparative structural investigations with several etchants in order to be able to undertake the metallographic detection of finely distributed carbides in the structure of the high alloy ultra-high strength steel X 41 CrMoV 51. The characteristic distribution and number of carbides could be revealed as well as the ferrite pearlite matrix. The picric-hydrochloric acid solution which, on a comparative basis, was the most effective, revealed the dependence of the carbide dissolution and structural formation on the temperature. The carbide components of the structure dissolved to an increasing extent at temperatures above 1100 0 C. All carbides up to the large volume mixed carbides appeared to dissolve in the segregation zone after annealing for one hour at 1200 0 C. Considerable grain growth also occurred. (orig./RW) [de

Study on Creep Damage Model of 1Cr1Mo1/4V Steel for Turbine Rotor

International Nuclear Information System (INIS)

Choi, Woo Sung; Song, Gee Wook; Kim, Bum Shin; Chang, Sung Ho; Fleury, Eric

2011-01-01

It is well known that the dominant damage mechanisms in high-temperature steam turbine facilities such as rotor and casing are creep and fatigue damages. Even though coupling of creep and fatigue should be considered while predicting the life of turbine facilities, the remaining life of large steam turbine facilities is generally determined on the basis of creep damage because the turbines must generate stable base-load power and because they are operated at a high temperature and pressure for a long time. Almost every large steam turbine in Korea has been operated for more than 20 years and is made of steel containing various amounts of principal alloying elements nickel, chromium, molybdenum, and vanadium. In this study, creep damage model of 1Cr1Mo1/4V steel for turbine rotor is proposed and that can assess the high temperature creep life of large steam turbine facilities is proposed

The Effect of Hold Time on Creep-Fatigue in 9Cr-1Mo

Energy Technology Data Exchange (ETDEWEB)

Oh, Tae Young; Kim, Dae Whan; Kim, Yong Wan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Baek, Kyoung Ho [Chungnam National University, Daejeon (Korea, Republic of)

2009-05-15

9Cr-1Mo steel is a candidate material for reactor vessel for VHTR. Because 9Cr-1Mo steel has a good mechanical properties and a lower thermal expansion coefficient than austenitic stainless steel. The reactor vessel of VHTR is operated at about 450 .deg. C. At this temperature, fatigue occurs during start-up and cool-down, and creep occurs during normal operation. Creep-fatigue damage by the interaction between fatigue and creep is an important factor that limits VHTR reactor vessel life. In this study, Effect of hold time on low cycle fatigue behavior of 9Cr-1Mo at 600 .deg. C was investigated in air.

The Effect of Hold Time on Creep-Fatigue in 9Cr-1Mo

International Nuclear Information System (INIS)

Oh, Tae Young; Kim, Dae Whan; Kim, Yong Wan; Baek, Kyoung Ho

2009-01-01

9Cr-1Mo steel is a candidate material for reactor vessel for VHTR. Because 9Cr-1Mo steel has a good mechanical properties and a lower thermal expansion coefficient than austenitic stainless steel. The reactor vessel of VHTR is operated at about 450 .deg. C. At this temperature, fatigue occurs during start-up and cool-down, and creep occurs during normal operation. Creep-fatigue damage by the interaction between fatigue and creep is an important factor that limits VHTR reactor vessel life. In this study, Effect of hold time on low cycle fatigue behavior of 9Cr-1Mo at 600 .deg. C was investigated in air

Developing of complex for hot plastic deformation modeling of steel type 20-30CrNiMoV for heavy forging

Directory of Open Access Journals (Sweden)

Dub Vladimir

2017-01-01

Full Text Available Production of heavy forging of bars weighing more then 235 tons for such products as rotors made of steel type 20-30CrNiMoV is a critical independent work, failure to perform which entails high costs related to repeated production (in case of defective product and untimely launch of production plants. One of the frequent causes of a defective product is the impossibility of ultrasonic testing in the barrel-gate zones on the rotor workpiece, which is due to the microstructure of the metal, namely the grain size. Determing the stages of deformation process wich causes such defects in structure is the main goal of this work.

Formation of Al{sub 2}O{sub 3}/FeAl coatings on a 9Cr-1Mo steel, and corrosion evaluation in flowing Pb-17Li loop

Energy Technology Data Exchange (ETDEWEB)

Majumdar, Sanjib, E-mail: sanjib@barc.gov.in [High Temperature Materials Development Section, Materials Processing & Corrosion Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Paul, Bhaskar [High Temperature Materials Development Section, Materials Processing & Corrosion Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Chakraborty, Poulami [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Kishor, Jugal; Kain, Vivekanand [High Temperature Materials Development Section, Materials Processing & Corrosion Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Dey, Gautam Kumar [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai (India); Materials Group, Bhabha Atomic Research Centre, Trombay, Mumbai (India)

2017-04-01

Iron aluminide coating layers were formed on a ferritic martensitic grade 9Cr-1Mo (P 91) steel using pack aluminizing process. The formation of different aluminide compositions such as orthorhombic-Fe{sub 2}Al{sub 5}, B2-FeAl and A2-Fe(Al) on the pack chemistry and heat treatment conditions have been established. About 4–6 μm thick Al{sub 2}O{sub 3} scale was formed on the FeAl phase by controlled heat treatment. The corrosion tests were conducted using both the FeAl and Al{sub 2}O{sub 3}/FeAl coated specimens in an electro-magnetic pump driven Pb-17Li Loop at 500 °C for 5000 h maintaining a flow velocity of 1.5 m/s. The detailed characterization studies using scanning electron microscopy, back-scattered electron imaging and energy dispersive spectrometry revealed no deterioration of the coating layers after the corrosion tests. Self-healing oxides were formed at the cracks generated in the aluminide layers during thermal cycling and protected the base alloy (steel) from any kind of elemental dissolution or microstructural degradation. - Highlights: •Al{sub 2}O{sub 3}/FeAl coating produced on P91 steel by pack aluminizing and heat treatment. •Corrosion tests of coated steel conducted in flowing Pb-17Li loop at 500 °C for 5000 h. •Coating was protective against molten metal corrosion during prolonged exposure. •Self-healing protective oxides formed in the cracks generated in aluminide layers.

Aceros aluminotérmicos. Nuevas aplicaciones

Directory of Open Access Journals (Sweden)

Duart Blay, J. M.

2004-02-01

Full Text Available The metallothermy is a process based on physical ' chemistry possibility of metallic oxides reduction (Fe, Cr, Mn, Cu for oxygen strong affinity metals, like Al, Mg and Ti. The reaction is highly exothermic giving place to a metallic phase and slag separation by refining and reduction process simultaneously. The technological developed patent initially by Thermit - and improved for other Companies - works well by more than 50 years; today it is employed almost exclusively for obtaining steels and coppers for complex welded joints unions. Particular application or interest presents in the Railways technology for building continuous tracks, practically implanted in all the word and in welding copper cable rope - steel rail employed for traffic signals control. This work displays the fundamental thermodynamic principles of the aluminothermics of iron and their application to the complex weld of crossrail, dilation joints and bypass in Railways, that combine Hadfield steels, stainless steels and pearlitic steels of different mechanical properties. The unions should be compact, with strength and hardness in the levels that are cited in the work, according to requirements demanded by high speed (350 km/ h. lines, now in construction in Spain, but they result of general use to whatever class of less demanding lines and to mining railroads.

La metalotermia es un proceso físicoquímico basado en la posibilidad de reducción de óxidos metálicos (hierro, cromo, manganeso, cobre por metales altamente afines por el oxígeno, como son aluminio, magnesio y titanio. La reacción es altamente exotérmica dando lugar a un caldo metálico separado de su escoria, por un proceso de reducción y afino combinados. La patente tecnológica, desarrollada inicialmente por Thermit y perfeccionada por otras Compañías, lleva en vigor más de 50 años; se aplica hoy, casi exclusivamente, a la obtención de aceros y cobres para uniones soldadas complejas

Microstructure and elevated-temperature erosion-oxidation behaviour of aluminized 9Cr-1Mo Steel

OpenAIRE

Huttunen, E.; Honkanen, M.; Tsipas, Sophia Alexandra; Omar, H.; Tsipas, D.

2012-01-01

Degradation of materials by a combination of erosive wear and atmospheric oxidation at elevated temperatures constitutes a problem in some power generation processes, such as fluidized-bed combustion. In this work, 9Cr-1Mo steel, a common tube material in combustion chambers, is coated by a pack cementation method from an Al-containing pack in order to improve the resistance to erosion-oxidation at elevated temperatures. The resulting coating is studied in terms of microstructure and microhar...

In vitro biocompatibility of CoCrMo dental alloys fabricated by selective laser melting.

Science.gov (United States)

Hedberg, Yolanda S; Qian, Bin; Shen, Zhijian; Virtanen, Sannakaisa; Wallinder, Inger Odnevall

2014-05-01

Selective laser melting (SLM) is increasingly used for the fabrication of customized dental components made of metal alloys such as CoCrMo. The main aim of the present study is to elucidate the influence of the non-equilibrium microstructure obtained by SLM on corrosion susceptibility and extent of metal release (measure of biocompatibility). A multi-analytical approach has been employed by combining microscopic and bulk compositional tools with electrochemical techniques and chemical analyses of metals in biologically relevant fluids for three differently SLM fabricated CoCrMo alloys and one cast CoCrMo alloy used for comparison. Rapid cooling and strong temperature gradients during laser melting resulted in the formation of a fine cellular structure with cell boundaries enriched in Mo (Co depleted), and suppression of carbide precipitation and formation of a martensitic ɛ (hcp) phase at the surface. These features were shown to decrease the corrosion and metal release susceptibility of the SLM alloys compared with the cast alloy. Unique textures formed in the pattern of the melting pools of the three different laser melted CoCrMo alloys predominantly explain observed small, though significant, differences. The susceptibility for corrosion and metal release increased with an increased number (area) of laser melt pool boundaries. This study shows that integrative and interdisciplinary studies of microstructural characteristics, corrosion, and metal release are essential to assess and consider during the design and fabrication of CoCrMo dental components of optimal biocompatibility. The reason is that the extent of metal release from CoCrMo is dependent on fabrication procedures. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Comportamiento frente al desgaste y fricción de aceros empleados en líneas de manutención aérea ensayados con y sin lubricación

Directory of Open Access Journals (Sweden)

Castro Regal, G.

2005-06-01

Full Text Available The sliding friction and wear behaviour of different steel qualities were investigated with and without lubrication conditions. Steel qualities tested are normally used in the overhead conveyor system of many industrial fields, like the automotive sector. Sliding wear tests have been conducted by means of a pin-on-disk machine. A 100Cr6 steel similar to that used within the overhead conveyor trolleys has been employed as a pin. Friction coefficient values obtained under lubrication conditions were three times smaller than those obtained without lubrication. The mechanism that controls wear behaviour under lubrication conditions is an abrasive one and the wear values obtained are almost worthless. On the other hand, mechanism controlling wear during non lubrication tests, was a combination of abrasion and adhesion

Se ha evaluado el comportamiento frente a fricción y el desgaste de distintas calidades de acero ensayadas bajo condiciones de lubricación y sin lubricación. Las calidades de acero seleccionadas son las que normalmente se emplean en los sistemas de manutención aérea de numerosos procesos de producción, como la fabricación de automóviles. Se han realizado ensayos de desgaste tipo punzón-disco mediante un punzón de acero de calidad100Cr6, empleado en los carros que circulan por las líneas de manutención aérea. Se ha observado que el valor del coeficiente de fricción obtenido bajo condiciones de lubricaciones, aproximadamente, tres veces menor que el obtenido sin lubricación. Por otro lado, el mecanismo que controla el proceso de desgaste de los aceros ensayados con lubricación es un mecanismo de desgaste abrasivo y los valores de desgaste obtenidos son prácticamente despreciables. El desgaste de los aceros ensayados sin lubricación se produjo por combinación de dos mecanismos de desgaste: abrasión y adhesión.

Elevated Temperature Corrosion Studies of AlCrN and TiAlN Coatings by PAPVD on T91 Boiler Steel

Science.gov (United States)

Goyal, Lucky; Chawla, Vikas; Hundal, Jasbir Singh

2017-11-01

The present investigation discusses the hot corrosion behavior of AlCrN and TiAlN nano-coatings on T91 boiler steel by PAPVD process subjected to molten salt of Na2SO4-60%V2O5 at 900 °C for 50 cycles. Surface and cross-sectional studies were performed by AFM, SEM/EDS and XRD techniques to understand the corrosion kinetics and mechanism. T91 bare boiler steel as well as TiAlN-coated specimen has shown higher internal oxidation as well as weight gain. The better corrosion resistance of AlCrN-coated specimen has been observed by virtue of higher availability of Cr and Al in the oxide scale as well as adherent and dense coating. The betterment of AlCrN coating can be attributed to low internal oxidation as well as movement of Cr and Al toward oxide scale to form protective corrosion barriers.

The Tribological Performance of CrMoN/MoS2 Solid Lubrication Coating on a Piston Ring

Directory of Open Access Journals (Sweden)

Yuelan Di

2017-05-01

Full Text Available In order to improve the tribological properties of an engine piston ring and enhance its service life, magnetron sputtering technology and low temperature ion sulphurizing treatment technology were used to prepare CrMoN/MoS2 solid lubricant coating on the surface of an engine piston ring. The morphologies and compositions of the surface and cross-section of the sulfuration layer were analyzed by field emission scanning electron microscopy (FESEM, and wear property under high load, high speed and high temperature conditions were tested by a SRV®4 friction and wear testing machine. The results show that the CrMoN/MoS2 composite coatings appear as a dense grain structure, and the coating is an ideal solid lubrication layer that possesses an excellent high temperature wear resistance, reducing the engine operating temperature abrasion effectively and prolonging the service life of the engine.

Sulfuric acid baking and leaching of spent Co-Mo/Al2O3 catalyst.

Science.gov (United States)

Kim, Hong-In; Park, Kyung-Ho; Mishra, Devabrata

2009-07-30

Dissolution of metals from a pre-oxidized refinery plant spent Co-Mo/Al(2)O(3) catalyst have been tried through low temperature (200-450 degrees C) sulfuric acid baking followed by mild leaching process. Direct sulfuric acid leaching of the same sample, resulted poor Al and Mo recoveries, whereas leaching after sulfuric acid baking significantly improved the recoveries of above two metals. The pre-oxidized spent catalyst, obtained from a Korean refinery plant found to contain 40% Al, 9.92% Mo, 2.28% Co, 2.5% C and trace amount of other elements such as Fe, Ni, S and P. XRD results indicated the host matrix to be poorly crystalline gamma- Al(2)O(3). The effect of various baking parameters such as catalyst-to-acid ratio, baking temperature and baking time on percentage dissolutions of metals has been studied. It was observed that, metals dissolution increases with increase in the baking temperature up to 300 degrees C, then decreases with further increase in the baking temperature. Under optimum baking condition more than 90% Co and Mo, and 93% Al could be dissolved from the spent catalyst with the following leaching condition: H(2)SO(4)=2% (v/v), temperature=95 degrees C, time=60 min and Pulp density=5%.

Modeling and Finite Element Analysis for the Dynamic Recrystallization Behavior of Ti-5Al-5Mo-5V-3Cr-1Zr Near β Titanium Alloy During Hot Deformation

Science.gov (United States)

Lv, Ya-ping; Li, Shao-jun; Zhang, Xiao-yong; Li, Zhi-you; Zhou, Ke-chao

2018-04-01

Evolution for the dynamic recrystallization (DRX) volume fraction of Ti-5Al-5Mo-5V-3Cr-1Zr near β titanium alloy during hot deformation was characterized by using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. To determine the equation parameters, a series of thermal simulation experiments at the temperature of 1023-1098 K and strain rate of 0.001-1 s‒1 to the true strain of 0.7 were conducted to obtain the essential data about stress σ and strain ɛ. By further transforming the relationship of σ versus ɛ into the relationship of strain hardening rate dσ/dɛ versus σ, two characteristic strains at the beginning of DRX (critical strain ɛc) and at the peak stress (peak strain ɛp) were identified from the dσ/dɛ-σ curves. Sequentially, the parameters in the JMAK equation were determined from the linear fitting of the different relationships among critical strain ɛc, peak strain ɛp and deformation conditions (including temperature T, strain rate \\dot ɛ and strain ɛ). The as-obtained JMAK equation was expressed as XDRX=1-exp[-0.0053((ɛ-ɛc)/ɛc)2.1], where ɛc=0.6053ɛp and ɛp=0.0031 \\dot ɛ .0081exp(28,781/RT). Finally, the JMAK equation was implanted into finite element program to simulate the hot compression of thermal simulation experiments. The simulation predictions and experimental results about the DRX volume fraction distribution showed a good consistency.

Bulk and surface properties of liquid Al-Cr and Cr-Ni alloys

International Nuclear Information System (INIS)

Novakovic, R

2011-01-01

The energetics of mixing and structural arrangement in liquid Al-Cr and Cr-Ni alloys has been analysed through the study of surface properties (surface tension and surface segregation), dynamic properties (chemical diffusion) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the framework of statistical mechanical theory in conjunction with quasi-lattice theory. The Al-Cr phase diagram exhibits the existence of different intermetallic compounds in the solid state, while that of Cr-Ni is a simple eutectic-type phase diagram at high temperatures and includes the low-temperature peritectoid reaction in the range near a CrNi 2 composition. Accordingly, the mixing behaviour in Al-Cr and Cr-Ni alloy melts was studied using the complex formation model in the weak interaction approximation and by postulating Al 8 Cr 5 and CrNi 2 chemical complexes, respectively, as energetically favoured.

Bulk and surface properties of liquid Al-Cr and Cr-Ni alloys.

Science.gov (United States)

Novakovic, R

2011-06-15

The energetics of mixing and structural arrangement in liquid Al-Cr and Cr-Ni alloys has been analysed through the study of surface properties (surface tension and surface segregation), dynamic properties (chemical diffusion) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the framework of statistical mechanical theory in conjunction with quasi-lattice theory. The Al-Cr phase diagram exhibits the existence of different intermetallic compounds in the solid state, while that of Cr-Ni is a simple eutectic-type phase diagram at high temperatures and includes the low-temperature peritectoid reaction in the range near a CrNi(2) composition. Accordingly, the mixing behaviour in Al-Cr and Cr-Ni alloy melts was studied using the complex formation model in the weak interaction approximation and by postulating Al(8)Cr(5) and CrNi(2) chemical complexes, respectively, as energetically favoured.

Mechanical properties of steel 8 CrMoNiNb 9 10 in dependence on the microstructural condition

International Nuclear Information System (INIS)

Fabritius, H.; Schnabel, E.

1976-01-01

Tension tests at room temperature to 600 0 C and creep-rupture tests at 500 to 600 0 C lasting up to about 75,000 h on two casts of steel 8 CrMoNiNb 9 10 with about 0.08% C, 0.3% Si, 0.7% Mn, 0.012% N, 0.005% Al, 2.34% Cr, 0.95% Mo, 0.8% Nb and 0.64% Ni in bainitic and ferritic microstructural condition. Influence of annealing at 650 to 800 0 C on the properties in the tension test. Influence of aging at 500 to 600 0 C lasting up to 30,000 h with and without mechanical stress on the properties in the tension test at aging temperature and on the toughness behaviour in the notched bar impact bend test at room temperature. (orig.) [de

Influence of Mo addition on the tempered properties of 13Cr martensitic stainless steel

International Nuclear Information System (INIS)

Jung, Byong Ho; Ahn, Yong Sik

1998-01-01

In order to investigate the effect of Mo addition on the mechanical properties of 13Cr-0.2C martensitic stainless steel, tensile test and Charpy V-notch test were performed after tempering at the temperature range of 200∼700 .deg. C following austenitizing at 1100 .deg. C. The yield strength and hardness of the steel were increased with the increase of Mo content at all tempering conditions, because Mo causes retardation of precipitation and coarsening of carbides and solid solution strengthening of matrix. Except 500 .deg. C of tempering temperature, the Charpy impact energy was significantly increased with Mo content and showed the highest value at 1.5 wt% addition. The increase of impact energy of the steel containing Mo is thought to be caused by δ-ferrite formed in the tempered martensitic matrix. At 500 .deg. C tempering, Charpy impact energy was decreased drastically due to temper embrittlement and it was not possible to prevent it even though Mo was added up to 1.5 wt%

Characterization of interaction between U-Mo alloy and Al diffusion-couple

International Nuclear Information System (INIS)

Liu Yunming; Yin Changgeng; Sun Changlong; Chen Jiangang; Sun Xudong

2011-01-01

In this paper, the interaction behavior of U-Mo/Al was studied with the diffusion-couple method, and the couple was continuously jointed by hot-pressing with special device. Annealing experiments were accomplished in a vacuum hot-pressing furnace, and at 550∼570℃ for 5∼21 hours. The results show that the morphology and composition of interaction Layer depend on the interaction layer thickness. The content of U (Mo) and Al is mutational at the interface of U-Mo/interaction layer/Al. The layer close to U-Mo side is mainly composed of product (U, Mo)Al 3 , while the Al side is composed of (U, Mo)Al 4 and UMO 2 Al 20 . Diffusion process of U-Mo/Al is Al immigrating over the Al/U-Mo original interface into U-Mo side and reacting with U-Mo, subsequently the interaction layer is growing into Al. (authors)

Evaluation of Surface Mechanical Properties and Grindability of Binary Ti Alloys Containing 5 wt % Al, Cr, Sn, and V

Directory of Open Access Journals (Sweden)

Hae-Soon Lim

2017-11-01

Full Text Available This study aimed to investigate the relationship between the surface mechanical properties and the grindability of Ti alloys. Binary Ti alloys containing 5 wt % concentrations of Al, Cr, Sn, or V were prepared using a vacuum arc melting furnace, and their surface properties and grindability were compared to those of commercially pure Ti (cp-Ti. Ti alloys containing Al and Sn had microstructures that consisted of only α phase, while Ti alloys containing Cr and V had lamellar microstructures that consisted of α + β phases. The Vickers microhardness of Ti alloys was increased compared to those of cp-Ti by the solid solution strengthening effect. Among Ti alloys, Ti alloy containing Al had the highest Vickers microhardness. At a low SiC wheel speed of 5000 rpm, the grinding rates of Ti alloys showed an increasing tendency as the hardness values of Ti alloys decreased. At a high SiC wheel speed of 10,000 rpm, the grinding rates of Ti alloys showed an increasing tendency as the tensile strength values increased. The Ti alloy containing Al, which showed the lowest tensile strength, had the lowest grinding rate. The grinding ratios of the Ti alloys were higher than those of cp-Ti at both wheel revolution speeds of 5000 and 10,000 rpm. The grinding ratio of the Ti alloy containing Al was significantly increased at 10,000 rpm (p < 0.05.

Lithium insertion in V{sub 2}O{sub 5}, M{sub x}V{sub 2}O{sub 5} (M = Fe, Cr, Al, La) mixed oxides; Insertion du lithium dans les oxydes mixtes de V{sub 2}O{sub 5}, M{sub x}V{sub 2}O{sub 5} (M = Fe, Cr, Al, La)

Energy Technology Data Exchange (ETDEWEB)

Gregoire, G.; Pecquenard, B.; Baffier, N. [Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France). Laboratoire de Chimie Appliquee de l`Etat Solide; Soudan, P.; Farcy, J.; Pereira-Ramos, J.P. [Centre National de la Recherche Scientifique (CNRS), 94 - Ivry-sur-Seine (France). Laboratoire d`Electrochimie Catalyse et Synthese Organique

1996-12-31

V{sub 2}O{sub 5} based compounds are interesting low potential materials for rechargeable cathodes of lithium electrochemical generators. However, the ionic conductivity and the reversibility of electrochemical cycling of V{sub 2}O{sub 5} are limited by the possibilities of lithium insertion. This work shows that the doping of vanadium pentoxide by a M{sup 3+} trivalent transition element (M Fe, Al, Cr or La) allows to intercalate a more important amount of lithium and to improve the behaviour of the material during cycling. These materials of M{sub 0.11}V{sub 2}O{sub 5.16} formula are obtained by sol-gel synthesis. the electrochemical study of the Fe compound has shown that it is a mixed oxide with a behaviour similar to V{sub 2}O{sub 5}. The maximum capacity is of about 2 F/mole in the case of Fe, Al and Cr compounds and of about 1.7 F/mole in the case of La. The structural evolution of the Fe compound has been followed during the chemical insertion of Li and the same succession of phases ({alpha}, {epsilon}, {delta} and {gamma}) is observed as in Li{sub x}V{sub 2}O{sub 5} compounds but with a delay. The occurrence of the {gamma} phase, in particular, which is involved in recharging problems is delayed thanks to the (Fe-O){sub n} chains perpendicular to the (V{sub 2}O{sub 5}){sub n} layers. Abstract only. (J.S.) 3 refs.

Lithium insertion in V{sub 2}O{sub 5}, M{sub x}V{sub 2}O{sub 5} (M = Fe, Cr, Al, La) mixed oxides; Insertion du lithium dans les oxydes mixtes de V{sub 2}O{sub 5}, M{sub x}V{sub 2}O{sub 5} (M = Fe, Cr, Al, La)

Energy Technology Data Exchange (ETDEWEB)

Gregoire, G; Pecquenard, B; Baffier, N [Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France). Laboratoire de Chimie Appliquee de l` Etat Solide; Soudan, P; Farcy, J; Pereira-Ramos, J P [Centre National de la Recherche Scientifique (CNRS), 94 - Ivry-sur-Seine (France). Laboratoire d` Electrochimie Catalyse et Synthese Organique

1997-12-31

V{sub 2}O{sub 5} based compounds are interesting low potential materials for rechargeable cathodes of lithium electrochemical generators. However, the ionic conductivity and the reversibility of electrochemical cycling of V{sub 2}O{sub 5} are limited by the possibilities of lithium insertion. This work shows that the doping of vanadium pentoxide by a M{sup 3+} trivalent transition element (M Fe, Al, Cr or La) allows to intercalate a more important amount of lithium and to improve the behaviour of the material during cycling. These materials of M{sub 0.11}V{sub 2}O{sub 5.16} formula are obtained by sol-gel synthesis. the electrochemical study of the Fe compound has shown that it is a mixed oxide with a behaviour similar to V{sub 2}O{sub 5}. The maximum capacity is of about 2 F/mole in the case of Fe, Al and Cr compounds and of about 1.7 F/mole in the case of La. The structural evolution of the Fe compound has been followed during the chemical insertion of Li and the same succession of phases ({alpha}, {epsilon}, {delta} and {gamma}) is observed as in Li{sub x}V{sub 2}O{sub 5} compounds but with a delay. The occurrence of the {gamma} phase, in particular, which is involved in recharging problems is delayed thanks to the (Fe-O){sub n} chains perpendicular to the (V{sub 2}O{sub 5}){sub n} layers. Abstract only. (J.S.) 3 refs.

Caracterización de soldaduras circunferenciales de aceros avanzados 9Cr: parte 1

Directory of Open Access Journals (Sweden)

Mabel Ramini

2014-03-01

Full Text Available Os aços 9%Cr são amplamente utilizados à alta temperatura, principalmente em aplicações relacionadas à geração de energia. Ultimamente têm sido desenvolvidas variantes desses materiais incorporando B, W e Co, entre outros elementos, ao sistema de liga. Devido à escassez de informação sobre a influência do procedimento de soldagem sobre a junta soldada, neste trabalho se estudou o comportamento do metal base e do metal de solda em juntas circunferências soldadas com dois consumíveis diferentes pelo processo de soldagem semi-automático FCAW, sob proteção gasosa de Ar/20%CO2. Realizaram-se tratamentos térmicos pós-soldagem a 760ºC durante 4 e 2 horas. Utilizaram-se dois arames tubulares de escória rutílica, ligados ao 9Cr1Mo e 9Cr0,5Mo1WCo. Analisou-se a microestrutura nas zonas do metal de solda, afetada pelo calor (zonas de grão grosso, grão fino, intercrítica e subcrítica e metal base. Determinaram-se a composição química do metal de solda e as propriedades de tração transversal da junta, e realizaram levantamento do perfil de microdureza. Em todos os casos se observaram valores máximos de dureza na zona correspondente ao metal de soldadura e uma diminuição na zona afetada pelo calor desde a zona de grão grosso até o metal base, obtendo se valores mínimos na zona intercrítica, inferiores aos correspondentes ao aço base. Tanto a dureza como a resistência à tração aumentaram quando foi utilizado o arame 9Cr0,5Mo1W. O tratamento térmico mais curto permitiu alcançar maior resistência em todos os casos. Numa próxima etapa se fará as medições de tenacidade e de resistência ao creep.

Cyclic Oxidation of High Mo, Reduced Density Superalloys

Directory of Open Access Journals (Sweden)

James L. Smialek

2015-11-01

Full Text Available Cyclic oxidation was characterized as part of a statistically designed, 12-alloy compositional study of 2nd generation single crystal superalloys as part of a broader study to co-optimize density, creep strength, and cyclic oxidation. The primary modification was a replacement of 5 wt. % W by 7% or 12% Mo for density reductions of 2%–7%. Compositions at two levels of Mo, Cr, Co, and Re were produced, along with a midpoint composition. Initially, polycrystalline vacuum induction samples were screened in 1100 °C cyclic furnace tests using 1 h cycles for 200 h. The behavior was primarily delimited by Cr content, producing final weight changes of −40 mg/cm2 to −10 mg/cm2 for 0% Cr alloys and −2 mg/cm2 to +1 mg/cm2 for 5% Cr alloys. Accordingly, a multiple linear regression fit yielded an equation showing a strong positive Cr effect and lesser negative effects of Co and Mo. The results for 5% Cr alloys compare well to −1 mg/cm2, and +0.5 mg/cm2 for Rene′ N4 and Rene′ N5 (or Rene′ N6, respectively. Scale phases commonly identified were Al2O3, NiAl2O4, NiTa2O6, and NiO, with (Ni,CoMoO4 found only on the least resistant alloys having 0% Cr and 12% Mo. Scale microstructures were complex and reflected variations in the regional spallation history. Large faceted NiO grains and fine NiTa2O6 particles distributed along NiAl2O4 grain boundaries were typical distinctive features. NiMoO4 formation, decomposition, and volatility occurred for a few high Mo compositions. A creep, density, phase stability, and oxidation balanced 5% Cr, 10% Co, 7% Mo, and 3% Re alloy was selected to be taken forward for more extensive evaluations in single crystal form.

Microstructural effects on the yield strength and its temperature dependence in a bainitic precipitation hardened Cr-Mo-V steel

International Nuclear Information System (INIS)

Toerroenen, K.; Kotilainen, H.; Nenonen, P.

1980-03-01

The plastic deformation behaviour of a precipitation hardened bainitic Cr-Mo-V steel is analyzed at ambient and low temperatures. The temperature dependent component of the yield strength is composed of the Peierls-Nabarro force and also partly of the strengthening contribution of the lath- and cell boundaries or the solid solution hardening. The temperature dependence below 230 K is in accordance with the models presented by Yanoshevich and Ryvkina as well as Dorn and Rajnak. The temperature independent component can be calculated merely from the dislocation density, which is stabilized by the vanadium-rich carbides. The linear additivity cannot be used for the superposition of the strengthening effects of various strengthening parameters, By using the phenomenological approach starting from the dislocation movement mechanisms upon yielding the laws for the superposition are discussed. (author)

Atomic scale onset of Al adhesion on Mo2BC

International Nuclear Information System (INIS)

Bolvardi, Hamid; Music, Denis; Schneider, Jochen M.

2015-01-01

We have explored interfacial interactions between a Mo–C terminated Mo 2 BC(040) surface and an Al cluster using ab initio molecular dynamics. The Al cluster is disrupted and wets the Mo 2 BC(040) surface. This can be understood based on the electronic structure. Across the Al–MoC interface C s–Al s hybridized states are formed. These bonds are stronger than the Al–Al intra-cluster bonds. Hence, the onset of Al adhesion is caused by bond formation across the Al–MoC interface. - Highlights: • Interfacial interactions between Mo 2 BC and an Al cluster were explored. • Al forms bonds to C constituting the onset of Al adhesion on Mo 2 BC. • These data are relevant for other carbide coatings

Preliminary Results on FeCrAl Alloys in the As-received and Welded State Designed to Have Enhanced Weldability and Radiation Tolerance

International Nuclear Information System (INIS)

Field, Kevin G.; Gussev, Maxim N.; Hu, Xunxiang; Yamamoto, Yukinori

2015-01-01

The present report summarizes and discusses the recent results on developing a modern, nuclear grade FeCrAl alloy designed to have enhanced radiation tolerance and weldability. The alloys used for these investigations are modern FeCrAl alloys based on a Fe-13Cr-5Al-2Mo-0.2Si-0.05Y alloy (in wt.%, designated C35M). Development efforts have focused on assessing the influence of chemistry and microstructure on the fabricability and performance of these newly developed alloys. Specific focus was made to assess the weldability, thermal stability, and radiation tolerance.

Preliminary Results on FeCrAl Alloys in the As-received and Welded State Designed to Have Enhanced Weldability and Radiation Tolerance

Energy Technology Data Exchange (ETDEWEB)

Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hu, Xunxiang [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-09-30

The present report summarizes and discusses the recent results on developing a modern, nuclear grade FeCrAl alloy designed to have enhanced radiation tolerance and weldability. The alloys used for these investigations are modern FeCrAl alloys based on a Fe-13Cr-5Al-2Mo-0.2Si-0.05Y alloy (in wt.%, designated C35M). Development efforts have focused on assessing the influence of chemistry and microstructure on the fabricability and performance of these newly developed alloys. Specific focus was made to assess the weldability, thermal stability, and radiation tolerance.

A Comparative Physics Study of Commercial PWR Cores using Metallic Micro-cell UO{sub 2}-Cr (or Mo) Pellets with Cr-based Cladding Coating

Energy Technology Data Exchange (ETDEWEB)

Hwang, Dae Hee; Hong, Ser Gi [Kyung Hee University, Yongin (Korea, Republic of); In, Wang Kee [KAERI, Daejeon (Korea, Republic of)

2016-05-15

In this work, a comparative neutronic analysis of the cores using ATFs which include metallic micro-cell UO{sub 2}-Cr, UO{sub 2}-Mo pellets and Cr-based alloy coating on cladding was performed to show the effects of the ATF fuels on the core performance. In this study, the cores having different ATFs use the same initial uranium enrichments. The ATF concepts studied in this work are the metallic microcell UO{sub 2} pellets containing Cr or Mo with cladding outer coating composed of Cr-based alloy which have been suggested as the ATF concepts in KAERI (Korea Atomic Energy Research Institute). The metallic micro-cell pellets and Cr-based alloy coating can enhance thermal conductivity of fuel and reduce the production of hydrogen from the reaction of cladding with coolant, respectively. The objective of this work is to compare neutronic characteristics of commercial PWR equilibrium cores utilizing the different variations of metallic micro-cell UO{sub 2} pellets with cladding coating composed of Cr-based alloy. The results showed that the cores using UO{sub 2}-Cr and UO{sub 2}-Mo pellets with Cr-based alloy coating on cladding have reduced cycle lengths by 60 and 106 EFPDs, respectively, in comparison with the reference UO{sub 2} fueled core due to the reduced heavy metal inventories and large thermal absorption cross section but they do not have any significant differences in the core performances parameters. However, it is notable that the core fueled the micro-cell UO{sub 2}-Mo pellet and Cr-based alloy coating has considerably more negative MTC and slightly more negative FTC than the other cases. These characteristics of the core using micro-cell UO{sub 2}-Mo pellet and Cr-based alloy coating is due to the hard neutron spectrum and large capture resonance cross section of Mo isotopes.

Crystal Structure of Na3MoCl6

Directory of Open Access Journals (Sweden)

Martin Beran

2011-07-01

Full Text Available The ternary chloride Na3MoCl6 is obtained as red crystals from a disproportionation reaction of molybdenum dichloride, {Mo6}Cl12, in an acidic NaCl/AlCl3 melt at 350 °C. The crystal structure (trigonal, P-31c, a = 687.1(1, c = 1225.3(2 pm, Z = 2, V = 501,0(1 106 pm3 is that of Na3CrCl6: within a hexagonal closest-packing of chloride ions two thirds of the octahedral voids are filled between the AB double layers with Na+/Mo3+, and between the BA layers with Na+.

Effect of Cr and Mo on strain ageing behaviour of low carbon steel

International Nuclear Information System (INIS)

Pereloma, E.V.; Bata, V.; Scott, R.I.; Smith, R.M.

2010-01-01

This work explores the effects of Cr (0.26-0.74 wt%) and Mo (0.09-0.3 wt%) additions on the kinetics of strain ageing process in low carbon steel. The strain ageing behaviour of the steels was investigated by using tensile tests and transmission electron microscopy. The results have shown that Mo-alloyed steels undergo the same four stages of ageing as unalloyed low carbon steel, whereas Cr-alloyed steels exhibit only three stages of ageing. At the same time, the addition of Mo accelerates the ageing response, while alloying with Cr reduces the rate of strain ageing by ∼3 times in comparison with non-alloyed low carbon steel. It especially delays the offset of Stage III. This is explained by the reduction of carbon content in ferrite due to the enrichment of cementite with Cr leading to the reduction of its equilibrium solubility in ferrite.

Effect of Cr and Mo on strain ageing behaviour of low carbon steel

Energy Technology Data Exchange (ETDEWEB)

Pereloma, E.V., E-mail: elenap@uow.edu.au [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Bata, V. [Department of Materials Engineering, Monash University (Australia); Scott, R.I.; Smith, R.M. [BlueScope Steel Limited, Port Kembla (Australia)

2010-04-25

This work explores the effects of Cr (0.26-0.74 wt%) and Mo (0.09-0.3 wt%) additions on the kinetics of strain ageing process in low carbon steel. The strain ageing behaviour of the steels was investigated by using tensile tests and transmission electron microscopy. The results have shown that Mo-alloyed steels undergo the same four stages of ageing as unalloyed low carbon steel, whereas Cr-alloyed steels exhibit only three stages of ageing. At the same time, the addition of Mo accelerates the ageing response, while alloying with Cr reduces the rate of strain ageing by {approx}3 times in comparison with non-alloyed low carbon steel. It especially delays the offset of Stage III. This is explained by the reduction of carbon content in ferrite due to the enrichment of cementite with Cr leading to the reduction of its equilibrium solubility in ferrite.

Gate Tunable Transport in Graphene/MoS₂/(Cr/Au) Vertical Field-Effect Transistors.

Science.gov (United States)

Nazir, Ghazanfar; Khan, Muhammad Farooq; Aftab, Sikandar; Afzal, Amir Muhammad; Dastgeer, Ghulam; Rehman, Malik Abdul; Seo, Yongho; Eom, Jonghwa

2017-12-28

Two-dimensional materials based vertical field-effect transistors have been widely studied due to their useful applications in industry. In the present study, we fabricate graphene/MoS₂/(Cr/Au) vertical transistor based on the mechanical exfoliation and dry transfer method. Since the bottom electrode was made of monolayer graphene (Gr), the electrical transport in our Gr/MoS₂/(Cr/Au) vertical transistors can be significantly modified by using back-gate voltage. Schottky barrier height at the interface between Gr and MoS₂ can be modified by back-gate voltage and the current bias. Vertical resistance (R vert ) of a Gr/MoS₂/(Cr/Au) transistor is compared with planar resistance (R planar ) of a conventional lateral MoS₂ field-effect transistor. We have also studied electrical properties for various thicknesses of MoS₂ channels in both vertical and lateral transistors. As the thickness of MoS₂ increases, R vert increases, but R planar decreases. The increase of R vert in the thicker MoS₂ film is attributed to the interlayer resistance in the vertical direction. However, R planar shows a lower value for a thicker MoS₂ film because of an excess of charge carriers available in upper layers connected directly to source/drain contacts that limits the conduction through layers closed to source/drain electrodes. Hence, interlayer resistance associated with these layers contributes to planer resistance in contrast to vertical devices in which all layers contribute interlayer resistance.

The Al Effects of Co-Free and V-Containing High-Entropy Alloys

Directory of Open Access Journals (Sweden)

Songqin Xia

2017-01-01

Full Text Available In this study, five-component high-entropy alloys (HEAs AlxCrFeNiV (where x denotes the molar ratio, x = 0, 0.1, 0.3, 0.5, 0.75, 1, and 1.5 were prepared using an arc-melting furnace. The effects of the addition of the Al on the crystal structures were investigated using X-ray diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. Also, two non-equiatomic ratio HEAs, AlxCrFeNiV (x = 0.3, and 0.5, were systematically studied through the use of various characterization methods in the as-cast state. The Al0.3CrFeNiV alloy displayed typical duplex body-centered cubic (BCC structures, including disordered BCC (A2, and NiAl-type ordered BCC (B2 phases. Meanwhile, in regard to the Al0.5CrFeNiV alloy, this alloy was found to contain an unknown phase which was enriched in Cr and V, as well as the coherent A2/B2 phases. Both of these alloys displayed very high yield and fracture strengths. However, their compression fracture strains were approximately 10%. Also, the fracture surfaces showed mainly cleavage fracture modes.

Effect of ETA treatment on corrosion fatigue in rotors and blades and stress corrosion cracking in 3.5 NiCrMoV steel low-pressure turbine discs

International Nuclear Information System (INIS)

Hitomi, Itoh; Takashi, Momoo; Takayuki, Shiomi

2001-01-01

In recent years, to increase the reliability and reduce the amount of feed water iron to prevent of fouling of steam generator tubes, ethanolamine (ETA) treatment has been adopted into the secondary system. In this investigation, the authors verified that ethanolamine treatment does not adversely affect the susceptibility of either stress corrosion cracking (SCC) in the turbine discs that are the principal units in the secondary system or corrosion fatigue (CF) in rotors and blades. In the first stage, a laboratory investigation was made of (1) SCC initiation and propagation in 3,5 NiCrMoV steel and (2) CF in 3,5 NiCrMoV steel and blade steels, in both cases using deaerated water to which had been added ethanolamine with few organic acids that is 10 times the estimated concentration. It was confirmed that the ethanolamine treatment had almost no effect. In the second stage, test pieces (removed from the disc steel inserted into the turbine extraction chamber before the ethanolamine treatment was started) were used to observe the initiation and propagation of SCC. Even after long-term observation, ethanolamine treatment into the secondary system was found to have almost no effect on the susceptibility of SCC in discs. (author)

Characterization of the interaction layer in diffusion couples U-Mo-Zr/Al and U-Mo-Zr/Al-A356 at 550 C degrees

International Nuclear Information System (INIS)

Komar Varela, Carolina; Arico, Sergio; Mirandou, Marcela; Balart, Silvia; Gribaudo, Luis

2007-01-01

Out-of-pile diffusion experiments were performed between U-7 wt.% Mo-1 wt.% Zr and Al or Al A356 (7,1 wt.% Si) at 550 C degrees. In this work morphological characterization and phase identification on both interaction layers are presented. They were carried out by the use of different techniques: optical and scanning electron microscopy, X-ray diffraction and WDS microanalysis. In the interaction layer U-7 wt.% Mo-1 wt.% Zr/Al, the phases UAl 3 , UAl 4 , Al 20 Mo 2 U and Al 43 Mo 4 U 6 were identified. Similar results in the interaction layer of the U-7 % Mo/Al at 580 C degrees were previously obtained. In the interaction layer U-7 wt.% Mo-1 wt.% Zr/Al A356, the phases U(Al,Si) 3 with 25 at.% Si and Si 5 U 3 were identified. This last phase, with a higher Si concentration, was identified with X-ray diffraction synchrotron radiation performed at the National Synchrotron Light Laboratory, Campinas, Brazil. (author) [es

Characteristics of Modified 9Cr-1Mo Steel for Reactor Pressure Vessel of Very High Temperature Gas Cooled Reactor

Energy Technology Data Exchange (ETDEWEB)

Kim, Sung Ho; Ryu, W. S.; Han, Chang Hee; Yoon, J. H.; Chang, Jong Hwa

2004-11-15

Many researches and developments have been progressed for the construction of VHTR by 2020 in Korea. Modified 9Cr-1Mo steel has been receiving attention for the application to the reactor pressure vessel material of VHTR. We collected and analyzed the research data for modified 9Cr-1Mo steel in order to understand the characteristics of modified 9Cr-1Mo steel. The modified 9Cr-1Mo steel is a modified alloy system similar to conventional 9Cr-1Mo grade ferritic steel. Modifications include additions of vanadium, niobium, and nitrogen, as well as lower carbon content. In this report, we summarized the change of microstructure and mechanical properties after tempering, thermal aging, and irradiation. Modified 9Cr-1Mo steel has high strength and thermal conductivity, low thermal expansion, and good resistance to corrosion. But the irradiation embrittlement behavior of modified 9Cr-1Mo steel should be evaluated and the evaluation methodology also should be developed. At the same time, the characteristics of weldment which is the weak part in pressure vessel should be evaluated.

Passive and transpassive behaviour of CoCrMo in simulated biological solutions

International Nuclear Information System (INIS)

Hodgson, A.W.E.; Kurz, S.; Virtanen, S.; Fervel, V.; Olsson, C.-O.A.; Mischler, S.

2004-01-01

In this work, the behaviour of a CoCrMo alloy under simulated body conditions was investigated. More specifically, the electrochemical properties of the alloy and the relevant mechanisms in the passive and transpassive states were studied in detail. Electrochemical techniques such as potentiodynamic and potentiostatic polarisation, cyclic voltammetry, rotating disc electrode and electrochemical impedance spectroscopy were employed. Further, ex situ X-ray photoelectron spectroscopy analysis of the passive films was carried out. A good correlation between the results obtained from all the experimental techniques was achieved. Overall, it was found that the passive film on CoCrMo changed in composition and thickness with both potential and time. The passive behaviour of the CrCrMo alloy is due to a formation an oxide film highly enriched with Cr (∼90% Cr oxides) on the alloy surface. The passive and transpassive behaviour of the alloy is hence dominated by the alloying element Cr. In the transpassive region, strong thickening of the oxide film takes place, combined with a change in the composition of the film, and strongly increased dissolution rate. In the transpassive region, all alloying elements dissolve according to the composition of the alloy. The metal ion release is also very strongly enhanced by cyclic variation of the potential between reducing and oxidizing conditions. In this case, during activation/repassivation cycles, cobalt dissolution is greater than expected from the composition of the alloy. Therefore, active dissolution behaviour is mainly dominated by the alloying element Co

Epitaxial growth of AlN on single crystal Mo substrates

International Nuclear Information System (INIS)

Okamoto, Koichiro; Inoue, Shigeru; Nakano, Takayuki; Kim, Tae-Won; Oshima, Masaharu; Fujioka, Hiroshi

2008-01-01

We have grown AlN films on single-crystalline Mo(110), (100), and (111) substrates using a low temperature pulsed laser deposition (PLD) growth technique and investigated their structural properties. Although c-axis oriented AlN films grow on Mo(100), the films contain 30 o rotated domains due to the difference in the rotational symmetry between AlN(0001) and Mo(100). AlN films with only poor crystalline quality grow on Mo(111) substrates, probably due to the poor surface morphology and high reactivity of the substrates. On the other hand, single crystal AlN films grow epitaxially on Mo(110) substrates with an in-plane relationship of AlN[11-20] // Mo[001]. Reflection high-energy electron diffraction or electron backscattered diffraction analysis has revealed that neither in-plane 30 deg. rotated domains nor cubic phase domains exist in the AlN films. X-ray reflectivity measurements have revealed that the heterointerface between AlN and Mo prepared by PLD at 450 deg. C is quite abrupt. These results indicate that PLD epitaxial growth of AlN on single crystal Mo substrates is quite promising for the fabrication of future high frequency filter devices

Epitaxial growth of AlN on single crystal Mo substrates

Energy Technology Data Exchange (ETDEWEB)

Okamoto, Koichiro; Inoue, Shigeru [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505 (Japan); Nakano, Takayuki; Kim, Tae-Won [Kanagawa Academy of Science and Technology (KAST) KSP east 301, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa, 213-0012 (Japan); Oshima, Masaharu [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 (Japan); Fujioka, Hiroshi [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505 (Japan); Kanagawa Academy of Science and Technology (KAST) KSP east 301, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa, 213-0012 (Japan)], E-mail: hfujioka@iis.u-tokyo.ac.jp

2008-06-02

We have grown AlN films on single-crystalline Mo(110), (100), and (111) substrates using a low temperature pulsed laser deposition (PLD) growth technique and investigated their structural properties. Although c-axis oriented AlN films grow on Mo(100), the films contain 30{sup o} rotated domains due to the difference in the rotational symmetry between AlN(0001) and Mo(100). AlN films with only poor crystalline quality grow on Mo(111) substrates, probably due to the poor surface morphology and high reactivity of the substrates. On the other hand, single crystal AlN films grow epitaxially on Mo(110) substrates with an in-plane relationship of AlN[11-20] // Mo[001]. Reflection high-energy electron diffraction or electron backscattered diffraction analysis has revealed that neither in-plane 30 deg. rotated domains nor cubic phase domains exist in the AlN films. X-ray reflectivity measurements have revealed that the heterointerface between AlN and Mo prepared by PLD at 450 deg. C is quite abrupt. These results indicate that PLD epitaxial growth of AlN on single crystal Mo substrates is quite promising for the fabrication of future high frequency filter devices.

Long-term Stability of 9- to 12 % Cr Steels

DEFF Research Database (Denmark)

Hald, John

2004-01-01

In the recent 25 years creep rupture strength of 9- to 12 %Cr steels for steam pipes and turbines has been doubled by development of new alloys. This development has formed a basis for improved efficiency of fossil fired steam power plants by introduction of advanced steam temperatures...... and pressures. Newly developed steam pipe steels are based on modifications of well-established steels like the X 20CrMoV12 1. Balanced addition of V, Nb and N to a 9Cr 1 Mo steel led to the Modified 9 Cr steel P 91. Addition of 1% W to a 9Cr 1 MoVNbN base composition led to steel E 911 and partial replacement...... of Mo with 1.8 % W combined with a slight amount of Boron led to steel P 92. The creep rupture strength of these new alloys are now secured with long-term tests up to 100,000 hours, which demonstrate improvements of 50% (P 91), 75 % (E 911) and 100 % (P 92) in strength compared to X 20CrMoV12 1....

Hormigones de alta resistencia con nano-adiciones y fibras de acero

OpenAIRE

Alizo Mirabal, Manuel Arturo

2015-01-01

El presente Trabajo Fin de Máster consistió en determinar la influencia que pueden poseer las nano-adiciones de Sílice y Alúmina y fibras de acero en un Hormigón de Alta Resistencia. Partiendo de una dosificación de Hormigón de Alta Resistencia conocida, que contenía humo de Sílice (10%) y fibras de poliolefina (3kg/m3), se les procedió a sustituir por la incorporación de nano-adiciones de Sílice y Alúmina (7% y 3% respectivamente) y añadiendo fibras de acero en lugar de poliolefina. En el pr...

Crack repair welding by CMT brazing using low melting point filler wire for long-term used steam turbine cases of Cr-Mo-V cast steels

Energy Technology Data Exchange (ETDEWEB)

Kadoi, Kota, E-mail: kadoi@hiroshima-u.ac.jp [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Murakami, Aoi; Shinozaki, Kenji; Yamamoto, Motomichi [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Matsumura, Hideo [Chugoku Electric Power Co., 3-9-1 Kagamiyama, Higashi-Hiroshima 739-0046 (Japan)

2016-06-01

Surface melting by gas tungsten arc (GTA) welding and overlaying by cold metal transfer (CMT) brazing using low melting point filler wire were investigated to develop a repair process for cracks in worn cast steel of steam turbine cases. Cr-Mo-V cast steel, operated for 188,500 h at 566 °C, was used as the base material. Silver and gold brazing filler wires were used as overlaying materials to decrease the heat input into the base metal and the peak temperature during the welding thermal cycle. Microstructural analysis revealed that the worn cast steel test samples contained ferrite phases with intragranular precipitates of Cr{sub 7}C{sub 3}, Mo{sub 2}C, and CrSi{sub 2} and grain boundary precipitates of Cr{sub 23}C{sub 6} and Mo{sub 2}C. CMT brazing using low melting point filler wire was found to decrease the heat input and peak temperature during the thermal cycle of the process compared with those during GTA surface melting. Thus, the process helped to inhibit the formation of hardened phases such as intermetallics and martensite in the heat affected zone (HAZ). Additionally, in the case of CMT brazing using BAg-8, the change in the hardness of the HAZ was negligible even though other processes such as GTA surface melting cause significant changes. The creep-fatigue properties of weldments produced by CMT brazing with BAg-8 were the highest, and nearly the same as those of the base metal owing to the prevention of hardened phase formation. The number of fracture cycles using GTA surface melting and CMT brazing with BAu-4 was also quite small. Therefore, CMT brazing using low melting point filler wire such as BAg-8 is a promising candidate method for repairing steam turbine cases. However, it is necessary to take alloy segregation during turbine operation into account to design a suitable filler wire for practical use.

Nondestructive testing for microstructural characterization in 9Cr-1Mo ferritic steel towards assessment of fabrication quality and in-service degradation

Energy Technology Data Exchange (ETDEWEB)

Jayakumar, T.; Rao, K.B.S.; Raj, Baldev [Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

1999-07-01

The paper discusses the usefulness of non destructive testing for microstructural characterization in 9Cr-1Mo ferritic steel. Ultrasonic velocity and attenuation measurements and spectral analysis have been used in a complementary way for characterizing Ac{sub 1} and Ac{sub 3} temperatures, amount of martensite and ferrite, dissolution of V{sub 4}C{sub 3} and NbC and formation of {delta}-ferrite. The microstructural degradation occurring due to thermal ageing and creep has also been studied by ultrasonic velocity measurements. Magnetic Barkhausen noise technique has been used for estimating the extent of various regions in heat affected zone (HAZ) of 9Cr-1Mo ferritic steel weldment. The same technique has been used for the assessment of low cycle fatigue damage in 9Cr-1Mo steel. The study establishes that non destructive methods can be used for the assessment of fabrication quality and in service degradation of the components. (author)

Microstructure Evolution and Chemical Analysis on Carbon Steels and Fe-Cr-Mo Alloys after FAC Simulation Tests

International Nuclear Information System (INIS)

Kim, Seunghyun; Kim, Taeho; Lee, Yun Ju; Kim, Ji Hyun

2017-01-01

Flow-accelerated corrosion (FAC) is an environment assisted degradation of structural materials, which usually occurs in pipelines of power plants. There have been many studies to investigate the fundamental mechanism and corresponding countermeasures against FAC, and recently the carbon steels have been replaced by ASTM A 335 P22, which contains approximately 2.2 wt.% of Cr and 1 wt.% of Mo. By enhancing passivity of P22 by Cr, it is reported that FAC rate has been greatly reduced. However, while corrosion behavior of Fe-based alloys is relatively well known, their behavior under high-temperature flowing water is not well investigated. In other words, effects of Cr and its corrosion and oxidation behavior is not clearly revealed. Furthermore, it is known that Mo enhances the pitting corrosion resistance of alloys however its mechanism is not clearly investigated. Recently, replacement of Mo in alloy contents has been widely studied because of the cost of Mo. Carbon steels undergo severe environmental-assisted degradation behavior so called FAC, and as its countermeasure the carbon steel has been replaced by P22 which contains Cr and Mo. It is generally known that Cr and Mo enhances passivity of Fe-based alloys however their corrosion and oxidation behavior has not been fully investigated especially in high-temperature flowing water environments. In this study, we employed HRTEM and synchrotron XAS techniques in order to investigate detailed microstructure evolution and chemical bonding of the commercialized carbon steel and the Fe-Cr-Mo alloys. From the analysis, it is found that while carbon steels exhibit porous oxide P22 exhibit oxide structures with thin Cr-rich oxide and spinel. Therefore, carbon steel undergoes severe FAC compared to P22 however effects of Cr and Mo and their behavior in high-temperature flowing water will be investigated.

Efectos del tratamiento térmico en la fractura de aceros

Directory of Open Access Journals (Sweden)

Héctor Hernández A.

1992-05-01

Full Text Available No obstante de los avances logrados en otros tipos de aleaciones, los aceros se siguen utilizando en forma extensiva en la construcción de elementos estructurales, porque con una adecuada selección y tratamiento técnico, los aceros permiten obtener una conveniente combinación de propiedades mecánicas ante unas exigencias específicas de servicio. La fractura en elementos de máquinas frecuentemente se encuentra asociada a una discontinuidad, la cual provoca una concentración de esfuerzo, lo que puede originar sitios de iniciación de una falla por fractura. La carga límite de fractura es afectada por parámetros geométricos, naturaleza y tipo de carga y propiedades mecánicas del material. La mayoría de fallas por fractura de elementos de máquinas son fallas por fatiga; por lo general una fractura por fatiga tiene lugar por una progresiva generación y crecimiento de grietas hasta obtenerse una condición crítica de fractura súbita de la sección residual resistente. Frecuentemente en una fractura por fatiga se observan marcas de playa, las cuales son evidencias de la posición del frente de grietas antes que se alcance la condición de fractura súbita final. En este trabajo se muestra como el tratamiento térmico de temple y revenido de los aceros afecta el esfuerzo límite de falla por fractura para carga de tracción estática y carga de fatiga uniaxial con la presencia de una entalla severa. También se estudia el efecto del tratamiento térmico en la tenacidad de fractura, propiedad que cuantifica la resistencia al crecimiento súbito de una grieta bajo carga estática.

Binary and tertiary reaction cross-sections of V, Cr, Mn, Fe, Ni, Cu, Zr, Nb, Mo, Ta, W, Pt and their isotopes

International Nuclear Information System (INIS)

Garg, S.B.

1982-01-01

Neutron induced binary and tertiary reaction cross-sections have been evaluated for V, Cr, Mn, Fe, Ni, Cu, Zr, Nb, Mo, Ta, W, Pt and their isotopes in the 'energy range 0.5 MeV to 20 MeV using the nuclear statistical empirical model. The reactions considered are (n,n'), (n,2n), (n,3n), (n,p), (n,d), (n,t), (n, 3 He), (n,α), (n,np), (n,nd), (n,nt), (n,n 3 He), (n,nα), (n,pn), (n,2p), (n,ν), (n,αp), (n,dn) and (n,pα). Most of the above mentioned elements are used as structural materials in nuclear reactors and the measured cross-section data for the above listed reactions are seldom available for the radiation damage and safety analysis. With a view to providing these data, this nuclear model based evaluation has been undertaken. The associated uncertainties in the cross-sections and their fission averages have also been evaluated. (author)

Estudio del comportamiento del acero 2.25Cr-1Mo frente a los fenómenos de oxidación cíclica e isoterma

OpenAIRE

Proy, Manuel; Victoria Utrilla, M; Otero, Enrique

2014-01-01

Cyclic and isothermal oxidation of chromium-molybdenum steel 2.25Cr-1Mo were analyzed at 550 °C and 650 °C during 360 hours in air atmospheres. The cycles were performed with two stages; one of heating in furnace during 90 minutes and then the sample were cooled to 50 °C by air flow. Thermogravimetric analyses were performed to obtain high temperature corrosion kinetics. Several characterization techniques have been used to identify the corrosion mechanism, as X-Ray Diffraction (XRD), Optical...

Structure and delayed failure behaviour of 0.25C-Ni-Cr-Mo-V steel

International Nuclear Information System (INIS)

Kang, C.H.; Maeng, S.C.

1980-01-01

Delayed failure behaviour of the different transformation structures of 0.25C-2.5Ni-2.5Cr-0.5Mo-0.1V low alloy steel has been studied. The studied microstructures are martensite, lower bainite, and mixed structure of 50% martensite and 50% lower bainite. All these structures have been tempered at 450 deg C for 40 min to have the same tensile strength level of 143 kg/mm 2 . Delayed failure testing has been carried out with cantilever bend tester, in distilled water at 25 deg C. By comparing K 1 sub(scc) values, lower bainitic structure has shown the highest value, although it is only slightly higher than that of the martensitic structure. Mixed structure has the lowest resistance to delayed failure. The fracture modes of both martensitic and mixed structures have been observed as intergranular. In the martensitic structure, however, it is noticeable that there is a larger amount of ductile tearing between intergranular facets. The fracture mode of lower bainitic structure is the mixed topography of microplastic tearing and microvoid coalescence. The above experimental results are discussed in terms of Oriani's decohesion theory of hydrogen embrittlement. The lowest resistance of the mixed structure to delayed failure may be due to the enhanced decohesion by hydrogen at the phase boundaries of martensite and lower bainite. (author)

CrAlN coatings deposited by cathodic arc evaporation at different substrate bias

International Nuclear Information System (INIS)

Romero, J.; Gomez, M.A.; Esteve, J.; Montala, F.; Carreras, L.; Grifol, M.; Lousa, A.

2006-01-01

CrAlN is a good candidate as an alternative to conventional CrN coatings especially for high temperature oxidation-resistance applications. Different CrAlN coatings were deposited on hardened steel substrates by cathodic arc evaporation (CAE) from chromium-aluminum targets in a reactive nitrogen atmosphere at negative substrate bias between - 50 and - 400 V. The negative substrate bias has important effects on the deposition growth rate and crystalline structure. All our coatings presented hardness higher than conventional CrN coatings. The friction coefficient against alumina and tungsten carbide balls was around 0.6. The sliding wear coefficient of the CrAlN coatings was very low while an important wear was observed in the balls before a measurable wear were produced in the coatings. This effect was more pronounced as the negative substrate bias was increased

Structural stability, electronic, mechanical and superconducting properties of CrC and MoC

Energy Technology Data Exchange (ETDEWEB)

Kavitha, M.; Sudha Priyanga, G. [Department of Physics, N.M.S.S.V.N College, Madurai 625019, Tamilnadu (India); Rajeswarapalanichamy, R., E-mail: rrpalanichamy@gmail.com [Department of Physics, N.M.S.S.V.N College, Madurai 625019, Tamilnadu (India); Iyakutti, K. [Department of Physics and Nanotechnology, SRM University, Chennai 603203, Tamilnadu (India)

2016-02-01

The structural, electronic, mechanical and superconducting properties of chromium carbide (CrC) and molybdenum carbide (MoC) are investigated using first principles calculations based on density functional theory (DFT). The computed ground state properties like equilibrium lattice constants and cell volume are in good agreement with available theoretical and experimental data. A pressure induced structural phase transition from tungsten carbide phase (WC) to zinc blende phase (ZB) and then zinc blende phase (ZB) to nickel arsenide phase (NiAs) are observed in both chromium and molybdenum carbides. Electronic structure reveals that these carbides are metallic at ambient condition. All the calculated elastic constants obey the Born–Huang stability criteria, suggesting that they are mechanically stable at normal and high pressure. The super conducting transition temperatures for CrC and MoC in WC phase are found to be 31.12 K and 17.14 K respectively at normal pressure. - Highlights: • Electronic and mechanical properties of CrC and MoC are investigated. • Pressure induced structural phase transition is predicted at high pressure. • Electronic structure reveals that these materials exhibit metallic behaviour. • Debye temperature values are computed for CrC and MoC. • Superconducting transition temperature values are computed.

The corrosion and mechanical behaviour of Al, FeCrAlY, and CoCrAlY coatings in aggressive environments

NARCIS (Netherlands)

Haanappel, V.A.C.; Haanappel, V.A.C.; Geerdink, Bert; Fransen, T.; Gellings, P.J.

1991-01-01

The mechanical and chemical behaviours of aluminide coatings applied by pack cementation, FeCrAlY coatings applied by plasma spraying and CoCrAlY coatings applied by electrodeposition were studied. The coatings were pretreated for 0.5 h in argon at 1373 K to improve the adhesion and structural

Precipitation sequences in austenitic Fe-22Cr-21Ni-6Mo-(N) stainless steels

International Nuclear Information System (INIS)

Kim, S.-J.; Lee, T.-H.

1999-01-01

Precipitation sequence of nitrogen containing Fe-22Cr-21Ni-6Mo-N austenitic stainless steel has been investigated after aging at high temperatures, and compared with nitrogen free steel. The σ phases and M 23 C 6 carbides were observed along the grain boundaries as well as in the matrix in both of the solution treated specimens. The M 6 C carbides and chi phase appeared successively in between 3 hours and 24 hours depending on the nitrogen content. Main difference in aging behavior was the precipitation of fine nitrides. Aging for 24 hours and 168 hours of nitrogen containing steel resulted in the formation of fine Cr 2 N and faceted AlN nitrides. The crystallography, structure and morphology were analyzed with analytical electron microscopy. (orig.)

Evaluation of microstructure and mechanical properties of 50Cr5NiMoV steel for forged backup roll

Energy Technology Data Exchange (ETDEWEB)

Song, X.Y.; Zhang, X.J.; Fu, L.C.; Yang, H.B.; Yang, K.; Zhu, L., E-mail: zl508@126.com

2016-11-20

The microstructure and mechanical properties of forged 50Cr5NiMoV steel backup roll were evaluated in this study. The microstructure characteristics from surface to center along radial direction of the backup roll were carefully observed by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the chemical composition, hardness, tensile property, impact and fracture toughness in different position of the backup roll were also examined. The results indicate that the finely precipitated carbides at different matrix during heat treatment process strongly influence mechanical properties of the backup roll. Especially, the spheroidized pearlite at the inner regions which consists of large globular or rod-like M{sub 7}C{sub 3} and a little of small globular M{sub 23}C{sub 6} possesses much better toughness and fracture resistance properties than those of the lamellar pearlite with lamellar M{sub 23}C{sub 6} and a little of globular M{sub 7}C{sub 3}.

Gate Tunable Transport in Graphene/MoS2/(Cr/Au Vertical Field-Effect Transistors

Directory of Open Access Journals (Sweden)

Ghazanfar Nazir

2017-12-01

Full Text Available Two-dimensional materials based vertical field-effect transistors have been widely studied due to their useful applications in industry. In the present study, we fabricate graphene/MoS2/(Cr/Au vertical transistor based on the mechanical exfoliation and dry transfer method. Since the bottom electrode was made of monolayer graphene (Gr, the electrical transport in our Gr/MoS2/(Cr/Au vertical transistors can be significantly modified by using back-gate voltage. Schottky barrier height at the interface between Gr and MoS2 can be modified by back-gate voltage and the current bias. Vertical resistance (Rvert of a Gr/MoS2/(Cr/Au transistor is compared with planar resistance (Rplanar of a conventional lateral MoS2 field-effect transistor. We have also studied electrical properties for various thicknesses of MoS2 channels in both vertical and lateral transistors. As the thickness of MoS2 increases, Rvert increases, but Rplanar decreases. The increase of Rvert in the thicker MoS2 film is attributed to the interlayer resistance in the vertical direction. However, Rplanar shows a lower value for a thicker MoS2 film because of an excess of charge carriers available in upper layers connected directly to source/drain contacts that limits the conduction through layers closed to source/drain electrodes. Hence, interlayer resistance associated with these layers contributes to planer resistance in contrast to vertical devices in which all layers contribute interlayer resistance.

Mechanism and kinetics of Fe, Cr, Mo and Mn atom interaction with molecular oxygen

International Nuclear Information System (INIS)

Akhmadov, U.S.; Zaslonko, I.S.; Smirnov, V.N.

1988-01-01

Rate constants of atomic interaction of some transition metals (Fe, Cr, Mo, Mn) with molecular oxygen are measured in shock waves using the resonance atomic-absorption method. A new method for determination of the parameter γ in the modified Lambert-Beer law D=ε(lN)γ is suggested and applied. Bond strength in CrO and MoO molecules is estimated

Improvement of the crystallographic orientation of double-layered perpendicular recording media by using CoCr (Mo)/Cu intermediate layers

International Nuclear Information System (INIS)

Tamai, Ichiro; Yamamoto, T.; Kikukawa, A.; Tanahashi, K.; Ishikawa, A.; Futamoto, M.

2001-01-01

We have introduced intermediate layers of CoCr/Cu and CoCrMo/Cu between a CoCrPtB recording layer and a soft-magnetic CoTaZr underlayer. The combination of the FCC-Cu first-intermediate layer and the HCP-CoCrMo second-intermediate layer was found to enhance the c-axis vertical orientation of the CoCrPtB recording layer. In media with intermediate layers of CoCrMo/Cu, the thickness of the intermediate layers can be reduced without sacrificing good magnetic properties, and this leads to high resolutions

The effect of tungsten on the tensile and creep rupture strength of 12 CrMoV steels

International Nuclear Information System (INIS)

Oakes, G.; Orr, J.

1978-01-01

A collaborative project involving the Brown-Firth Research Laboratories, the Sheffield Laboratories of the British Steel Corporation and Tube Investments Limited has been carried out to assess the effect of a controlled tungsten addition (0.5%) on the tensile and rupture properties of 12 CrMoV steel. The results obtained indicate that 0.5% tungsten increases the tensile properties at room temperature by approximately 3% but this diminishes with increasing test temperature. The creep rupture properties of the tungsten-bearing material showed a marked short time (500-1000 hours) strength advantage over the tungsten-free material at temperatures up to 650 0 C. At longer times and higher temperatures this stress advantage was reduced considerably so that at times in the region of 10,000 to 15,000 hours it was approximately 5%. In view of the limited data generated, it was found impossible to extrapolate with confidence to longer times but there was, however, no indication that a significant strength advantage is to be anticipated at 100,000 hours for the tungsten-bearing material. (author)

Influence of carbides and microstructure of CoCrMo alloys on their metallic dissolution resistance.

Science.gov (United States)

Valero-Vidal, C; Casabán-Julián, L; Herraiz-Cardona, I; Igual-Muñoz, A

2013-12-01

CoCrMo alloys are passive and biocompatible materials widely used as joint replacements due to their good mechanical properties and corrosion resistance. Electrochemical behaviour of thermal treated CoCrMo alloys with different carbon content in their bulk alloy composition has been analysed. Both the amount of carbides in the CoCrMo alloys and the chemical composition of the simulated body fluid affect the electrochemical properties of these biomedical alloys, thus passive dissolution rate was influenced by the mentioned parameters. Lower percentage of carbon in the chemical composition of the bulk alloy and thermal treatments favour the homogenization of the surface (less amount of carbides), thus increasing the availability of Cr to form the oxide film and improving the corrosion resistance of the alloy. © 2013.

Low-cost, high-strength Fe--Ni--Cr alloys for high temperature exhaust valve application

Science.gov (United States)

Muralidharan, Govindarajan

2017-09-05

An Fe--Ni--Cr alloy is composed essentially of, in terms of wt. %: 2.4 to 3.7 Al, up to 1.05 Co, 14.8 to 15.9 Cr, 25 to 36 Fe, up to 1.2 Hf, up to 4 Mn, up to 0.6 Mo, up to 2.2 Nb, up to 1.05 Ta, 1.9 to 3.6 Ti, up to 0.08 W, up to 0.03 Zr, 0.18 to 0.27 C, up to 0.0015 N, balance Ni, wherein, in terms of atomic percent: 8.5.ltoreq.Al+Ti+Zr+Hf+Ta.ltoreq.11.5, 0.53.ltoreq.Al/(Al+Ti+Zr+Hf+Ta).ltoreq.0.65, and 0.16.ltoreq.Cr/(Fe+Ni+Cr+Mn).ltoreq.0.21, the alloy being essentially free of Cu, Si, and V.

Oxidation resistance of TiN, CrN, TiAlN and CrAlN coatings deposited by lateral rotating cathode arc

International Nuclear Information System (INIS)

Chim, Y.C.; Ding, X.Z.; Zeng, X.T.; Zhang, S.

2009-01-01

In this paper, four kinds of hard coatings, TiN, CrN, TiAlN and CrAlN (with Al/Ti or Al/Cr atomic ratio around 1:1), were deposited on stainless steel substrates by a lateral rotating cathode arc technique. The as-deposited coatings were annealed in ambient atmosphere at different temperatures (500-1000 o C) for 1 h. The evolution of chemical composition, microstructure, and microhardness of these coatings after annealing at different temperatures was systematically analyzed by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and nanoindentation experiments. The oxidation behaviour and its influence on overall hardness of these four coatings were compared. It was found that the ternary TiAlN and CrAlN coatings have better oxidation resistance than their binary counterparts, TiN and CrN coatings. The Cr-based coatings (CrN and CrAlN) exhibited evidently better oxidation resistance than the Ti-based coatings (TiN and TiAlN). TiN coating started to oxidize at 500 o C. After annealing at 700 o C no N could be detected by EDX, indicating that the coating was almost fully oxidized. After annealed at 800 o C, the coating completely delaminated from the substrate. TiAlN started to oxidize at 600 o C. It was nearly fully oxidized (with little residual nitrogen detected in the coating by EDX) and partially delaminated at 1000 o C. Both CrN and CrAlN started to oxidize at 700 o C. CrN was almost fully oxidized (with little residual nitrogen detected in the coating by EDX) and partially delaminated at 900 o C. The oxidation rate of the CrAlN coating is quite slow. After annealing at 1000 o C, only about 19 at.% oxygen was detected and the coating showed no delamination. The Ti-based (TiN and TiAlN) coatings were not able to retain their hardness at higher temperatures (≥ 700 o C). On the other hand, the hardness of CrAlN was stable at a high level between 33 and 35 GPa up to an annealing temperature of 800 o C and still kept at a comparative high value of

Reaction layer in U-7WT%MO/Al diffusion couples

International Nuclear Information System (INIS)

Mirandou, M.I.; Balart, S.N.; Ortiz, M.; Granovsky, M.S.

2003-01-01

New results of the reaction layer characterization between γ (U-7wt%Mo) alloy and Al, in chemical diffusion couples, are presented. The analysis was performed using optical and scanning electron microscopy with EDAX and X-ray diffraction techniques. Besides the main components (U, Mo)Al 3 and (U, Mo)Al 4 , already reported, two ternary compounds of high Al content have been identified in the reaction layer when it grew in retained or decomposed γ (U, Mo) phase, respectively. The drastic consequence on the interdiffusion behavior due to the thermal instability of the retained γ (U, Mo) phase is discussed. (author)

Atomic scale onset of Al adhesion on Mo{sub 2}BC

Energy Technology Data Exchange (ETDEWEB)

Bolvardi, Hamid; Music, Denis, E-mail: music@mch.rwth-aachen.de; Schneider, Jochen M.

2015-08-31

We have explored interfacial interactions between a Mo–C terminated Mo{sub 2}BC(040) surface and an Al cluster using ab initio molecular dynamics. The Al cluster is disrupted and wets the Mo{sub 2}BC(040) surface. This can be understood based on the electronic structure. Across the Al–MoC interface C s–Al s hybridized states are formed. These bonds are stronger than the Al–Al intra-cluster bonds. Hence, the onset of Al adhesion is caused by bond formation across the Al–MoC interface. - Highlights: • Interfacial interactions between Mo{sub 2}BC and an Al cluster were explored. • Al forms bonds to C constituting the onset of Al adhesion on Mo{sub 2}BC. • These data are relevant for other carbide coatings.

Fission induced swelling of U–Mo/Al dispersion fuel

Energy Technology Data Exchange (ETDEWEB)

Kim, Yeon Soo, E-mail: yskim@anl.gov [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Jeong, G.Y. [Ulsan National Institute of Science and Technology, 50 UNIST-gil, Eonyang-eup, Uljoo-gun, Ulsan 689-798 (Korea, Republic of); Park, J.M. [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Robinson, A.B. [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-6188 (United States)

2015-10-15

Fission-induced swelling of U–Mo/Al dispersion fuel meat was measured using microscopy images obtained from post-irradiation examination. The data of reduced-size plate-type test samples and rod-type test samples were employed for this work. A model to predict the meat swelling of U–Mo/Al dispersion fuel was developed. This model is composed of several submodels including a model for interaction layer (IL) growth between U–Mo and Al matrix, a model for IL thickness to IL volume conversion, a correlation for the fission-induced swelling of U–Mo alloy particles, a correlation for the fission-induced swelling of IL, and models of U–Mo and Al consumption by IL growth. The model was validated using full-size plate data that were not included in the model development.

Analysis of diamond-like carbon and Ti/MoS2 coatings on Ti-6Al-4V substrates for applicability to turbine engine applications

International Nuclear Information System (INIS)

Wu, L.; Holloway, B.C.; Kalil, C.; Manos, D.M.

2000-01-01

Ti-6Al-4V substrates have been coated by diamond-like carbon (DLC) films, with no surface pretreatment, and have been coated by Ti/MoS 2 films, with a simple surface pre-cleaning. The DLC films were deposited by planar coil r.f. inductively-coupled plasma-enhanced chemical vapor deposition (r.f. ICPECVD); the Ti/MoS 2 films were deposited by magnetron sputtering. Both the DLC and Ti/MoS 2 films were characterized by pull tests, hardness tests, scanning electron microscopy (SEM), and wear tests (pin-on-disk and block-on-ring) to compare their adhesion, hardness, surface topology, and wear properties to plasma-sprayed Cu-Ni-In coating currently used for turbine engine applications. The DLC films were easily characterized by their optical properties because they were highly transparent. We used variable-angle spectroscopic ellipsometry (VASE) to characterize thickness and to unequivocally extract real and complex index of refraction, providing a rapid assessment of film quality. Thicker coatings yielded the largest hardness values. The DLC coatings did not require abrasive pretreatment or the formation of bond-layers to ensure good adhesion to the substrate. Simple surface pre-cleaning was also adequate to form well-adhered Ti/MoS 2 on Ti-6Al-4V. The results show that the DLC and Ti/MoS 2 coatings are both much better fretting- and wear-resistant coatings than plasma-sprayed Cu-Ni-In. Both show excellent adhesion to the substrates, less surface roughness, harder surfaces, and more wear resistance than the Cu-Ni-In films. (orig.)

Thermodynamic modeling of the Ti-Al-Cr ternary system

International Nuclear Information System (INIS)

Chen Leyi; Qiu Aitao; Liu Lanjie; Jiang Ming; Lu Xionggang; Li Chonghe

2011-01-01

Research highlights: → The full experimental results of the Ti-Al-Cr ternary system and its sub-binary systems are reviewed and analysed in detail. → Based on the latest thermodynamic assessments of the Ti-Al, Ti-Cr and Al-Cr systems and the ternary experimental data in literature, the thermodynamic parameters of the Ti-Al-Cr ternary system are fully assessed by the Calphad method. → The transformation of disorder to order (bcc a 2 to B2) and the new ternary compound L 12T i 25 Cr 8 Al 67 are considered in this work. - Abstract: The Ti-Al-Cr ternary system is one of the most important systems to studying the titanium alloys. Some experimental data of this ternary system are available and a few partial thermodynamic assessments are reported. However, no full thermodynamic descriptions were published. In this study, the previous work on the Ti-Al-Cr system and its related binary systems are reviewed. Based on the thermodynamic descriptions of the Ti-Al, Ti-Cr and Al-Cr systems and the ternary experimental data in literature, the Ti-Al-Cr ternary system is assessed by means of the Calphad method. Several isothermal sections from 1073 K to 1573 K and some invariant reactions are calculated, which are in good agreement with the most of the experimental results.

Aceros de baja aleación y alto rendimiento

Directory of Open Access Journals (Sweden)

Campos, M.

2008-02-01

Full Text Available A highly demanding automobile market requires an intensification of the efforts on increasing the performance and reducing costs of sintered steels, in order to stay in such a competitive market. Final properties of sintered parts and their cost depend on two main factors, density and the alloying system. The growing interest for Cr and Mn as alloying elements is due to both price, more suitable than Mo, and the excellent level of properties which are achieved in assintered parts as well as after the heat treatments. In this work, the possible techniques which lead to an enhancement of density are discussed, such as warm and high velocity compaction, or high temperature sintering; moreover it is important to study the synergy between the proposed techniques which may be compatible.

Las nuevas demandas en el sector del automóvil están haciendo que se intensifiquen los esfuerzos en aumentar las prestaciones y reducir los costes de los aceros sinterizados, para poder mantenerse en este mercado tan competitivo. Las propiedades finales de los componentes sinterizados y su coste dependen de dos factores principales, la densidad y el sistema de aleación. El creciente interés por el cromo y el manganeso como elementos de aleación se debe tanto al precio, más ventajoso que, por ejemplo, el molibdeno, como al nivel excelente de propiedades que se pueden conseguir tanto en estado sinterizado como después de los tratamientos térmicos. En este trabajo, se discuten además las posibles técnicas que conducen a una mejora de la densidad del componente, como la compactación de polvos precalentados, la compactación por propagación de ondas de impacto, o la sinterización a alta temperatura; además, es importante estudiar los efectos sinérgicos entre las técnicas propuestas que sean compatibles.

Optimizing Heat Treatment Process of Fe-13Cr-3Mo-3Ni Martensitic Stainless of Steel

Science.gov (United States)

Anwar, M. S.; Prifiharni, S.; Mabruri, E.

2017-05-01

The Fe-13Cr-3Mo-3Ni stainless steels are modified into martensitic stainless steels for steam turbine blades application. The working temperature of steam turbine was around 600 - 700 °C. The improvement properties of turbine blade material is necessary to maintain steam turbine work. The previous research revealed that it has corrosion resistance of Fe-13Cr-3Mo-3Ni which is better than 13Cr stainless steels in the chloride environment. In this work, the effect of heat treatment on microstructure and hardness of Fe-13Cr-3Mo-3Ni stainless steels has been studied. The steel was prepared by induction melting followed by hot forging. The steels were austenitized at 1000, 1050, and 1100 °C for 1 hour and were tempered at 600, 650, and 700 °C for 1 hour. The steels were then subjected to metallographic observation and hardness test of Rockwell C. The optimal heat treatment of Fe-13Cr-3Mo-3Ni was carried out austenitized in 1050 °C and tempered in 600 - 700 °C.

Ultrasonic impact treatment of CoCrMo alloy: Surface composition and properties

Energy Technology Data Exchange (ETDEWEB)

Chenakin, S.P., E-mail: chenakin@list.ru; Filatova, V.S.; Makeeva, I.N.; Vasylyev, M.A.

2017-06-30

Highlights: • Ultrasonic impact treatment in air enhances oxidation of CoCrMo alloy. • Impact treatment promotes segregation and accumulation of carbon on the surface. • Intense deformation brings about partial dissolution of carbides. • Impact-induced fcc-to-hcp transformation and hardening of the alloy. • Impact treatment improves corrosion properties of the alloy. - Abstract: X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry and X-ray diffraction were employed to study the effect of intense mechanical treatment on the surface chemical state, composition and structure of a commercial biomedical CoCrMo alloy (‘Bondi-Loy’). The ultrasonic impact treatment of the alloy in air with duration up to 30 s was found to cause the deformation-enhanced oxidation and deformation-induced surface segregation of the components and impurities from the bulk. The compositionally inhomogeneous mixed oxide layer formed under impact treatment was composed mainly of Cr{sub 2}O{sub 3} and silicon oxide with admixture of CoO, MoO{sub 2}, MoO{sub 3} and iron oxide/hydroxide, the latter being transferred onto the alloy surface from the steel pin. The impact treatment promoted a progressive accumulation of carbon on the alloy surface due to its deformation-induced segregation from the bulk and deformation-induced uptake of hydrocarbons from the ambient; concurrently, the dissolution/refinement of carbides originally present in the as-cast CoCrMo alloy occurred. The impact treatment gave rise to a two-fold increase in the volume fraction of the martensitic hcp ε-phase, a 30% increase in the surface microhardness and improved resistance to corrosion in the solution of artificial saliva compared to the as-polished alloy.

Interaction of Al with O2 exposed Mo2BC

International Nuclear Information System (INIS)

Bolvardi, Hamid; Music, Denis; Schneider, Jochen M.

2015-01-01

Highlights: • Al adheres to many surfaces. • Solid–solid interactions challenging for real (oxidized) surfaces. • Dissociative O 2 adsorption on Mo 2 BC(0 4 0). • Al nonamer is disrupted on oxidized Mo 2 BC(0 4 0). • Adhesion of a residual Al on the native oxide. - Abstract: A Mo 2 BC(0 4 0) surface was exposed to O 2 . The gas interaction was investigated using ab initio molecular dynamics and X-ray photoelectron spectroscopy (XPS) of air exposed surfaces. The calculations suggest that the most dominating physical mechanism is dissociative O 2 adsorption whereby Mo−O, O−Mo−O and Mo 2 −C−O bond formation is observed. To validate these results, Mo 2 BC thin films were synthesized utilizing high power pulsed magnetron sputtering and air exposed surfaces were probed by XPS. MoO 2 and MoO 3 bond formation is observed and is consistent with here obtained ab initio data. Additionally, the interfacial interactions of O 2 exposed Mo 2 BC(0 4 0) surface with an Al nonamer is studied with ab initio molecular dynamics to describe on the atomic scale the interaction between this surface and Al to mimic the interface present during cold forming processes of Al based alloys. The Al nonamer was disrupted and Al forms chemical bonds with oxygen contained in the O 2 exposed Mo 2 BC(0 4 0) surface. Based on the comparison of here calculated adsorption energy with literature data, Al−Al bonds are shown to be significantly weaker than the Al−O bonds formed across the interface. Hence, Al−Al bond rupture is expected for a mechanically loaded interface. Therefore the adhesion of a residual Al on the native oxide layer is predicted. This is consistent with experimental observations. The data presented here may also be relevant for other oxygen containing surfaces in a contact with Al or Al based alloys for example during forming operations

The use of extraction and electronic diffraction replicas for precipitates characterization in welded Cr-Mo Steels

International Nuclear Information System (INIS)

Gutierrez de Saiz-Solabarria, S.; San Juan Nunez, J.M.

1997-01-01

The precipitates and phases found in the structure of welded joints of Heat Interchanges Tubes were studied and identified. The base material satisfied the requirements of ASME Sec II, SA 213 Gr T22 (2 1/4 Cr 1 Mo). Compositions of Filler Metals were: 2 1/4 Cr 1 Mo and 2 1/4 Cr 1 Mo 1/4 Nb. The chemical composition of base and weld materials were analyzed by atomic emission spectroscopy in high vacuum electric discharge and by inductive plasma coupled. For the constituents characterization extraction and diffraction microscopy replicas were used. (Author) 65 refs

Oxidation behavior of Al/Cr coating on Ti2AlNb alloy at 900 °C

Science.gov (United States)

Yang, Zhengang; Liang, Wenping; Miao, Qiang; Chen, Bowen; Ding, Zheng; Roy, Nipon

2018-04-01

In this paper, the Al/Cr coating was fabricated on the surface of Ti2AlNb alloy via rf magnetron sputtering and double glow treatment to enhance oxidation resistance. The protective coating with an outer layer of Al and inner layer of Cr has great bonding strength due to the in-diffusion of Cr and the inter-diffusion between Al and Cr to form Al-Cr alloyed layer which has great hardness. Acoustic emission curve which was detected via WS-2005 scratch tester indicates the bonding strength between Al/Cr coating and substrate is great. Morphology of Ti2AlNb alloy with Al/Cr coating after scratch test shows that the scratch is smooth without disbanding, and the depth and breadth of scratch are changed uniformly. The mass change was reduced after oxidation test due to the Al/Cr protective coating. Isothermal oxidation test at 900 °C was researched. Results indicate that Al/Cr coating provided oxidation resistance of Ti2AlNb alloy with prolonged air exposure at 900 °C. Al2O3 was detected by XRD patterns and SEM images, and was formed on the surface of Ti2AlNb alloy to protect substrate during oxidation test. A certain content of Cr is beneficial for the formation of Al2O3. Besides, Cr2O3 was produced under Al2O3 by outward diffusion of Cr to protect substrate sequentially, no cracks were discovered on Al/Cr protective coating. The process of Ti outward diffusion into surface was suppressive due to integration of Cr-Ti and Al-Ti intermetallics. A steady, adherent and continuous coated layer of Al/Cr on Ti2AlNb alloy increases oxidation resistance.

The Cementation of Boron to Steels by the Method of Electrolytic Deposition; Cementation Electrolytique d'Aciers par le Bore; Tsementirovanie bora v stali putem ehlektroliticheskogo osazhdeniya; Cementacion de Aceros con Boro por Deposito Electrolitico

Energy Technology Data Exchange (ETDEWEB)

Kawakami, M. [Tokyo Institute of Technology (Japan)

1964-06-15

aceros al carbono, aceros inoxidables, acero de elevado contenido de cromo, etc.; todos ellos dan resultados satisfactorios. (author) [Russian] Privoditsja metod izgotovlenija upravljajushhego sterzhnja s cementirovaniem bora. Jetot process osushhestvljaetsja posredstvom jelektroliza rasplavlennogo tetrabornokislogo natrija pri temperature okolo 900 Degree-Sign S . Obrabatyvaemyj stal'noj sterzhen' sluzhit katodom, v k a chestve anoda ispol'zuetsja grafitovyj jelektrod. V processe jelektroliza bor osazhdaetsja na stal'noj sterzhen' i diffundiruet v sta l'. Pri podhodjashhih uslovijah jelektroliza legko udaetsja poluchit' stal'noj sterzhen', soderzhashhij po 20% bora. Issledovalis' sledujushhie tipy stali: uglerodistaja, nerzhavejushhie, hromistaja i t.d. , vo vseh sluchajah byli polucheny polozhitel'nye rezul'taty. (author)

The impedance properties of the oxide film on the Ni-Cr-Mo Alloy-22 in neutral concentrated sodium chloride solution

Energy Technology Data Exchange (ETDEWEB)

Jakupi, P.; Zagidulin, D.; Noel, J.J. [Department of Chemistry, University of Western Ontario, London, Ontario, N6A-3K7 (Canada); Shoesmith, D.W., E-mail: dwshoesm@uwo.ca [Department of Chemistry, University of Western Ontario, London, Ontario, N6A-3K7 (Canada)

2011-07-01

The oxide film properties on Alloy-22 in the applied potential (E) range -600 mV to 600 mV (vs. saturated KCl, Ag/AgCl reference electrode) were characterized by Electrochemical Impedance Spectroscopy (EIS) in near neutral pH, 5 M NaCl solutions, at 30 deg. C. The impedance properties of the film were compared to the chromium content of the film determined by X-ray photoelectron spectroscopy (XPS). The oxide film properties on Alloy-22 may be divided into three applied potential (E) ranges: -600 mV {<=} E < -300 mV, -300 mV {<=} E {<=} 300 mV, and E > 300 mV. For the range -600 mV {<=} E < -300 mV the film resistance (R{sub film}) increases with potential accompanied by an increase in Cr{sub 2}O{sub 3} content; in the range -300 mV {<=} E {<=} 300 mV, R{sub film} values and the Cr{sub 2}O{sub 3} content of the oxide film achieve their maximum values; for E > 300 mV, a decrease in both R{sub film} and Cr{sub 2}O{sub 3} is observed accompanied by a significant increase in Cr(OH){sub 3}. Comparison of the impedance properties for Alloy-22 to those of Ni-Cr alloys indicate that the barrier layer oxide on Alloy-22 contains a lower number of less mobile defects, most likely Cr interstitials. Destruction of the barrier layer for E > 300 mV leads to the formation of a thicker, less protective bilayer, which is high in Mo content.

Hot Corrosion Behavior of Stainless Steel with Al-Si/Al-Si-Cr Coating

Science.gov (United States)

Fu, Guangyan; Wu, Yongzhao; Liu, Qun; Li, Rongguang; Su, Yong

2017-03-01

The 1Cr18Ni9Ti stainless steel with Al-Si/Al-Si-Cr coatings is prepared by slurry process and vacuum diffusion, and the hot corrosion behavior of the stainless steel with/without the coatings is studied under the condition of Na2SO4 film at 950 °C in air. Results show that the corrosion kinetics of stainless steel, the stainless steel with Al-Si coating and the stainless steel with Al-Si-Cr coating follow parabolic laws in several segments. After 24 h corrosion, the sequence of the mass gain for the three alloys is the stainless steel with Al-Si-Cr coating coating coating. The corrosion products of the three alloys are layered. Thereinto, the corrosion products of stainless steel without coating are divided into two layers, where the outside layer contains a composite of Fe2O3 and FeO, and the inner layer is Cr2O3. The corrosion products of the stainless steel with Al-Si coating are also divided into two layers, of which the outside layer mainly consists of Cr2O3, and the inner layer is mainly SiO2. The corrosion film of the stainless steel with Al-Si-Cr coating is thin and dense, which combines well with substrate. Thereinto, the outside layer is mainly Cr2O3, and the inside layer is Al2O3. In the matrix of all of the three alloys, there exist small amount of sulfides. Continuous and protective films of Cr2O3, SiO2 and Al2O3 form on the surface of the stainless steel with Al-Si and Al-Si-Cr coatings, which prevent further oxidation or sulfide corrosion of matrix metals, and this is the main reason for the much smaller mass gain of the two alloys than that of the stainless steel without any coatings in the 24 h hot corrosion process.

A Preliminary Study to Enhance the Tribological Performance of CoCrMo Alloy by Fibre Laser Remelting for Articular Joint Implant Applications

Directory of Open Access Journals (Sweden)

Chi-Wai Chan

2018-03-01

Full Text Available CoCrMo alloy has long been used as a pairing femoral head material for articular joint implant applications because of its biocompatibility and reliable tribological performance. However, friction and wear issues are still present for CoCrMo (metal/CoCrMo (metal or CoCrMo (metal/ultrahigh molecular weight polyethylene (UHMWPE (plastic pairs in clinical observations. The particulate wear debris generated from the worn surfaces of CoCrMo or UHMWPE can pose a severe threat to human tissues, eventually resulting in the failure of implants and the need for revision surgeries. As a result, a further improvement in tribological properties of this alloy is still needed, and it is of great interest to both the implant manufacturers and clinical surgeons. In this study, the surface of CoCrMo alloy was laser-treated by a fibre laser system in an open-air condition (i.e., no gas chamber required. The CoCrMo surfaces before and after laser remelting were analysed and characterised by a range of mechanical tests (i.e., surface roughness measurement and Vickers micro-hardness test and microstructural analysis (i.e., XRD phase detection. The tribological properties were assessed by pin-on-disk tribometry and dynamic light scattering (DLS. Our results indicate that the laser-treated surfaces demonstrated a friction-reducing effect for all the tribopairs (i.e., CoCrMo against CoCrMo and CoCrMo against UHHMWPE and enhanced wear resistance for the CoCrMo/CoCrMo pair. Such beneficial effects are chiefly attributable to the presence of the laser-formed hard coating on the surface. Laser remelting possesses several competitive advantages of being a clean, non-contact, fast, highly accurate and automated process compared to other surface coating methods. The promising results of this study point to the possibility that laser remelting can be a practical and effective surface modification technique to further improve the tribological performance of CoCr

A FIM-atom probe investigation of the bainite transformation in CrMo steel

International Nuclear Information System (INIS)

Bach, P.W.

1981-01-01

To obtain a better understanding of the role played by Cr and Mo in the bainite transformation a Field-Ion Microscope - Atom Probe was constructed in order to study the distribution of the alloying elements near various types of boundaries on atomic scale. The distribution of alloying elements measured with this instrument is not so smooth on atomic scale as suggested by microprobe analysis. In a coherent twin boundary, formed during the bainite transformation, a depletion of the substitutionals Cr and Mo and an enhancement of the C content is observed, which is in accordance with the atomic model of a B.C.C. twin. In the twin plane the interstitial sites are even larger than the F.C.C. octahedral sites and this plane can act as an effective sink for the carbon atoms from bainitic ferrite. The depletion of Cr and Mo from the twin plane is due to interface coherency. (Auth.)

Degradación de recubrimientos ZrO2-CaO/NiAlMo por oxidación isoterma

Directory of Open Access Journals (Sweden)

Utrilla, V.

2006-12-01

Full Text Available This paper analyses the degradation of a ceramic top coating 70%ZrO2 – 30%CaO deposited onto a stainless steel AISI 304 by thermal spray, using Ni-6%Al-5%Mo as overlay coating. These thermal barrier coatings were heat treated for 48, 120 and 288 h at 800 ºC to evaluate the degradation of these materials by isothermal oxidation. The microstructure evolution during oxidation was analysed by environmental scanning electron microscopy, transmission electron microscopy, X ray microanalysis and X ray diffraction. A thermally grown oxide layer was observed between the overlay coating and the ceramic top coating after oxidation. This layer was formed by a mixed Al and Ni oxides.En este trabajo se estudia la degradación de un recubrimiento 70%ZrO2 – 30%CaO crecido por proyección térmica de oxiacetileno sobre un acero inoxidable austenítico AISI 304 y empleando una leación de Ni-6%Al-5%Mo como capa de anclaje. Los recubrimientos se trataron térmicamente en aire a 800 ºC durante 48, 120 y 288 horas para evaluar la degradación de estos materiales por oxidación isotérmica. La evolución de la microestructura de las barreras como consecuencia del proceso de oxidación se analizó mediante microscopía electrónica de barrido ambiental, microscopía electrónica de transmisión, microanálisis de rayos X (EDX y difracción de rayos X. Durante la oxidación de los recubrimientos creció una capa intermedia de óxidos (“thermally grown oxides”, TGO entre el anclaje metálico y el recubrimiento cerámico formada por una mezcla de óxidos de Al y Ni.

Development of banded microstructure in 34CrNiMo6 steel

Directory of Open Access Journals (Sweden)

A. Nagode

2016-07-01

Full Text Available In this paper the development of a banded microstructure in hot-rolled 34CrNiMo6 steel which consisted of bainitic and martensitic bands is explained. The chemical compositions of the bands were measured with energy dispersive x-ray spectroscopy (EDS, which showed that the martensitic bands contained more alloying elements (Mn, Cr, Mo, Si than bainitic bands. By using Oberhoffer reagent, the segregations of phosphorus were also revealed. These phosphorus segregations coincided with the positive segregations of the alloying elements. The continuous cooling transformation (CCT diagrams of steel were calculated. They confirmed the formation of martensite in positive segregations and the formation of bainite in negative segregations.

Thermal behavior analysis of U-Mo/Al dispersion fuel

Energy Technology Data Exchange (ETDEWEB)

Ryu, Ho Jin; Park, Jong Mang; Lee, Yoon Sang; Kim, Chang Kyu [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2004-07-01

According to the non-proliferation policy under the reduced enrichment for research and test reactors (RERTR) program, low enriched uranium(LEU) fuel such as uranium silicide dispersion fuels are being used in research reactors. Because of a lower enrichment higher uranium density fuels are required for some high performance research reactors. Some uranium alloys with a high uranium density such as U-Mo alloys have been considered as one of the most promising candidates for a dispersion fuel due to the good irradiation performance. An international qualification program to replace the uranium silicide dispersion fuel with U-Mo dispersion fuel is being carried out under the RERTR program. Although U-Mo powders are conventionally supplied by the mechanical comminuting of as-cast U-Mo alloys, KAERI developed a centrifugal atomization method in order to simplify the preparation process and improve the properties. The centrifugally atomized powders have a rapidly solidified gamma uranium structure and a spherical shape. During the in-reactor operation of a dispersion fuel, interdiffusion or chemical reactions between the fuel particles and the matrix occurr. Intermetallic compounds in the form of UAlx are formed as a result of the diffusional reaction. Because the intermetallic compounds are less dense than the combined reactants, the volume of the fuel element increases after the reaction. In addition to the effect on the swelling performance, the reaction layers between the U-Mo and the Al matrix induces a degradation of the thermal properties of the U-Mo/Al dispersion fuels. It is important to investigate the thermal behavior of U-Mo/Al dispersion fuel according to reaction between the fuel particles and the matrix with the burnup and linear power. In this study, a finite element analysis was used for the calculation of the temperature distribution of the U-Mo/Al dispersion fuel with a burnup and linear power. Kinetics data of the reaction layers such as the growth

Thermal behavior analysis of U-Mo/Al dispersion fuel

International Nuclear Information System (INIS)

Ryu, Ho Jin; Park, Jong Mang; Lee, Yoon Sang; Kim, Chang Kyu

2004-01-01

According to the non-proliferation policy under the reduced enrichment for research and test reactors (RERTR) program, low enriched uranium(LEU) fuel such as uranium silicide dispersion fuels are being used in research reactors. Because of a lower enrichment higher uranium density fuels are required for some high performance research reactors. Some uranium alloys with a high uranium density such as U-Mo alloys have been considered as one of the most promising candidates for a dispersion fuel due to the good irradiation performance. An international qualification program to replace the uranium silicide dispersion fuel with U-Mo dispersion fuel is being carried out under the RERTR program. Although U-Mo powders are conventionally supplied by the mechanical comminuting of as-cast U-Mo alloys, KAERI developed a centrifugal atomization method in order to simplify the preparation process and improve the properties. The centrifugally atomized powders have a rapidly solidified gamma uranium structure and a spherical shape. During the in-reactor operation of a dispersion fuel, interdiffusion or chemical reactions between the fuel particles and the matrix occurr. Intermetallic compounds in the form of UAlx are formed as a result of the diffusional reaction. Because the intermetallic compounds are less dense than the combined reactants, the volume of the fuel element increases after the reaction. In addition to the effect on the swelling performance, the reaction layers between the U-Mo and the Al matrix induces a degradation of the thermal properties of the U-Mo/Al dispersion fuels. It is important to investigate the thermal behavior of U-Mo/Al dispersion fuel according to reaction between the fuel particles and the matrix with the burnup and linear power. In this study, a finite element analysis was used for the calculation of the temperature distribution of the U-Mo/Al dispersion fuel with a burnup and linear power. Kinetics data of the reaction layers such as the growth

TI--CR--AL--O thin film resistors

Science.gov (United States)

Jankowski, Alan F.; Schmid, Anthony P.

2000-01-01

Thin films of Ti--Cr--Al--O are used as a resistor material. The films are rf sputter deposited from ceramic targets using a reactive working gas mixture of Ar and O.sub.2. Resistivity values from 10.sup.4 to 10.sup.10 Ohm-cm have been measured for Ti--Cr--Al--O film Ti--Cr--Al--O as a thin film resistor has been found to be thermodynamically stable, unlike other metal-oxide films. The Ti--Cr--Al--O film can be used as a vertical or lateral resistor, for example, as a layer beneath a field emission cathode in a flat panel display; or used to control surface emissivity, for example, as a coating on an insulating material such as vertical wall supports in flat panel displays.

Microstructural Characterization of Clad Interface in Welds of Ni-Cr-Mo High Strength Low Alloy Steel

Energy Technology Data Exchange (ETDEWEB)

Kim, Hong-Eun; Kim, Min-Chul; Lee, Ho-Jin; Kim, Keong-Ho [KAERI, Daejeon (Korea, Republic of); Lee, Ki-Hyoung [KAIST, Daejeon (Korea, Republic of); Lee, Chang-Hee [Hanyang Univ., Seoul (Korea, Republic of)

2011-08-15

SA508 Gr.4N Ni-Cr-Mo low alloy steel, in which Ni and Cr contents are higher than in commercial SA508 Gr.3 Mn-Mo-Ni low alloy steels, may be a candidate reactor pressure vessel (RPV) material with higher strength and toughness from its tempered martensitic microstructure. The inner surface of the RPV is weld-cladded with stainless steels to prevent corrosion. The goal of this study is to evaluate the microstructural properties of the clad interface between Ni-Cr-Mo low alloy steel and stainless weldment, and the effects of post weld heat treatment (PWHT) on the properties. The properties of the clad interface were compared with those of commercial Mn-Mo-Ni low alloy steel. Multi-layer welding of model alloys with ER308L and ER309L stainless steel by the SAW method was performed, and then PWHT was conducted at 610°C for 30 h. The microstructural changes of the clad interface were analyzed using OM, SEM and TEM, and micro-Vickers hardness tests were performed. Before PWHT, the heat affected zone (HAZ) showed higher hardness than base and weld metals due to formation of martensite after welding in both steels. In addition, the hardness of the HAZ in Ni-Cr-Mo low alloy steel was higher than that in Mn-Mo-Ni low alloy steel due to a comparatively high martensite fraction. The hardness of the HAZ decreased after PWHT in both steels, but the dark region was formed near the fusion line in which the hardness was locally high. In the case of Mn-Mo-Ni low alloy steel, formation of fine Cr-carbides in the weld region near the fusion line by diffusion of C from the base metal resulted in locally high hardness in the dark region. However, the precipitates of the region in the Ni-Cr-Mo low alloy steel were similar to that in the base metal, and the hardness in the region was not greatly different from that in the base metal.

Microstructural Characterization of Clad Interface in Welds of Ni-Cr-Mo High Strength Low Alloy Steel

International Nuclear Information System (INIS)

Kim, Hong-Eun; Kim, Min-Chul; Lee, Ho-Jin; Kim, Keong-Ho; Lee, Ki-Hyoung; Lee, Chang-Hee

2011-01-01

SA508 Gr.4N Ni-Cr-Mo low alloy steel, in which Ni and Cr contents are higher than in commercial SA508 Gr.3 Mn-Mo-Ni low alloy steels, may be a candidate reactor pressure vessel (RPV) material with higher strength and toughness from its tempered martensitic microstructure. The inner surface of the RPV is weld-cladded with stainless steels to prevent corrosion. The goal of this study is to evaluate the microstructural properties of the clad interface between Ni-Cr-Mo low alloy steel and stainless weldment, and the effects of post weld heat treatment (PWHT) on the properties. The properties of the clad interface were compared with those of commercial Mn-Mo-Ni low alloy steel. Multi-layer welding of model alloys with ER308L and ER309L stainless steel by the SAW method was performed, and then PWHT was conducted at 610°C for 30 h. The microstructural changes of the clad interface were analyzed using OM, SEM and TEM, and micro-Vickers hardness tests were performed. Before PWHT, the heat affected zone (HAZ) showed higher hardness than base and weld metals due to formation of martensite after welding in both steels. In addition, the hardness of the HAZ in Ni-Cr-Mo low alloy steel was higher than that in Mn-Mo-Ni low alloy steel due to a comparatively high martensite fraction. The hardness of the HAZ decreased after PWHT in both steels, but the dark region was formed near the fusion line in which the hardness was locally high. In the case of Mn-Mo-Ni low alloy steel, formation of fine Cr-carbides in the weld region near the fusion line by diffusion of C from the base metal resulted in locally high hardness in the dark region. However, the precipitates of the region in the Ni-Cr-Mo low alloy steel were similar to that in the base metal, and the hardness in the region was not greatly different from that in the base metal.

Effect of niobium on the embrittlement of 2.25 Cr and 2.25 Cr-1Mo steels by phosphous

International Nuclear Information System (INIS)

Antunes, J.L.B.

1985-01-01

The influence of niobium on the temper embrittlement of 2.25Cr and 2.25 Cr-1Mo steels doped with phosphorus is evaluated. The transition temperatures of the samples tempered at 650 0 C and aged at different temperatures for niobium steels. (M.J.C.) [pt

Microstructural studies on chemical interactions in U-Mo with Al

International Nuclear Information System (INIS)

Martins, Ilson Carlos

2010-01-01

This research refers to the study of U-Mo alloy as an alternative material for producing nuclear fuel elements with high density of uranium, for research reactors of high performance. The international non-proliferation of nuclear weapons has enrichment level limited to 20% U 23 '5. U-Mo alloys with 6-10 wt% Mo can lead to a density up to 9 gU/cm 3 , inside the fuel core. The MTR fuel element plates are made from briquettes (U-Mo powder + Al) encapsulated in Al plates, then welded and rolled However, the U-Mo alloy is very reactive in the presence of Al. The reaction products of this interaction are undesirable from the standpoint of nuclear usage, since they cause a chemical interaction layer (IL) formed during thermal cycling and exposure to nuclear fission neutrons. As the IL has low thermal conductivity, they may cause structural failure in the fuel element during operation. The present study provides a new preparation technique for interdiffusion pairs made by hot rolling. The U-Mo alloy, in tablet format, is involved by matrix Al-plates, which is sealed and then hot rolled. This way to prepare the diffusion couples is an ideal condition to avoid the oxidation at the contact interface at U-Mo/Al. The hot rolling preparation also simulates the first reduction pass during MTR fuel plate manufacture. We chose to work with a Mo content of 10 wt% in U-Mo alloy to ensure greater phase formation, since this level favors a greater chemical stability in this phase. The Al alloy matrix was used as the AA1050 since it contains small impurity amounts. The interdiffusion couples U-10Mo/AA1050 were thermally treated in two temperature ranges (1500C and 5500C) and three soaking times (5h, 40h and 80h) to simulate the interdiffusion process and formation of chemical interaction layer. The analysis of the interaction layer U-10Mo/AA1050 was made by SEM/EDS and X-ray diffraction. It revealed a general trend of low interdiffusion of Al (about 8 atomic %) inside U-Mo. There was

Hf-W chronology of CR chondrites: Implications for the timescales of chondrule formation and the distribution of 26Al in the solar nebula

Science.gov (United States)

Budde, Gerrit; Kruijer, Thomas S.; Kleine, Thorsten

2018-02-01

Renazzo-type carbonaceous (CR) chondrites are distinct from most other chondrites in having younger chondrule 26Al-26Mg ages, but the significance of these ages and whether they reflect true formation times or spatial variations of the 26Al/27Al ratio within the solar protoplanetary disk are a matter of debate. To address these issues and to determine the timescales of metal-silicate fractionation and chondrule formation in CR chondrites, we applied the short-lived 182Hf-182W chronometer to metal, silicate, and chondrule separates from four CR chondrites. We also obtained Mo isotope data for the same samples to assess potential genetic links among the components of CR chondrites, and between these components and bulk chondrites. All investigated samples plot on a single Hf-W isochron and constrain the time of metal-silicate fractionation in CR chondrites to 3.6 ± 0.6 million years (Ma) after the formation of Ca-Al-rich inclusions (CAIs). This age is indistinguishable from a ∼3.7 Ma Al-Mg age for CR chondrules, suggesting not only that metal-silicate fractionation and chondrule formation were coeval, but also that these two processes were linked to each other. The good agreement of the Hf-W and Al-Mg ages, combined with concordant Hf-W and Al-Mg ages for angrites and CV chondrules, provides strong evidence for a disk-wide, homogeneous distribution of 26Al in the early solar system. As such, the young Al-Mg ages for CR chondrules do not reflect spatial 26Al/27Al heterogeneities but indicate that CR chondrules formed ∼1-2 Ma later than chondrules from most other chondrite groups. Metal and silicate in CR chondrites exhibit distinct nucleosynthetic Mo and W isotope anomalies, which are caused by the heterogeneous distribution of the same presolar s-process carrier. These data suggest that the major components of CR chondrites are genetically linked and therefore formed from a single reservoir of nebular dust, most likely by localized melting events within the

Caustic cracking of 2 1/4 CrMo steel

International Nuclear Information System (INIS)

Cowen, H.C.; Thorley, A.W.

1983-12-01

Stress corrosion cracking tests performed on the 21/4 Cr Mo ferritic steel are described. The principal environments studied were strong, aqueous caustic soda, molten anhydrous caustic soda, and caustic soda with an addition of sodium. Emphasis has been placed on material in the quenched-hardened condition. (author)

Influence of Normalizing Temperature on the Microstructure and Hardness of 9Cr-1Mo ODS Steel

Energy Technology Data Exchange (ETDEWEB)

Jang, Ki Nam; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Kyu Tae [Dongguk University, Gyeongju (Korea, Republic of)

2016-10-15

Oxide dispersion strengthened(ODS) steel has superior high-temperature strength and creep properties because fine oxide particles having an excellent stability at high temperatures are uniformly distributed in the matrix. ODS steel has being developed for structure materials of sodium fast cooled reactor(SFR) because of its excellent irradiation resistance and mechanical properties. 9Cr-1Mo ODS steel has better high temperature strength and irradiation resistance than common 9Cr-1Mo steel because Y{sub 2}O{sub 3} nano-sized particles which interrupt dislocation movement and grain boundary slip are uniformly dispersed in the martensite matrix. The mechanical properties of the ODS steels are mainly determined by their microstructures, and the microstructure is considerably decided by the heat-treatment conditions. This study focused on the effect of normalizing temperature on microstructure and hardness of 9Cr-1Mo martensitic ODS steel so as to optimize the heat-treatment condition. In this study, the effect of normalizing temperature on mechanical property and microstructures of 9Cr-1Mo martensitic ODS steel was investigated. It was shown that the microhardness was steadily increased with increasing of the normalizing temperature. According to TEM observation, mechanical property of 9Cr-1Mo ODS steel was significantly affected by lath width. These observations, could be useful to understand the relationship between normalizing temperature and microstructure.

Effect of Titanium on the Microstructure and Mechanical Properties of High-Carbon Martensitic Stainless Steel 8Cr13MoV

Directory of Open Access Journals (Sweden)

Wen-Tao Yu

2016-08-01

Full Text Available The effect of titanium on the carbides and mechanical properties of martensitic stainless steel 8Cr13MoV was studied. The results showed that TiCs not only acted as nucleation sites for δ-Fe and eutectic carbides, leading to the refinement of the microstructure, but also inhibited the formation of eutectic carbides M7C3. The addition of titanium in steel also promoted the transformation of M7C3-type to M23C6-type carbides, and consequently more carbides could be dissolved into the matrix during hot processing as demonstrated by the determination of extracted carbides from the steel matrix. Meanwhile, titanium suppressed the precipitation of secondary carbides during annealing. The appropriate amount of titanium addition decreased the size and fraction of primary carbides in the as-cast ingot, and improved the mechanical properties of the annealed steel.

Precipitation of carbides in Cr – Mo – V cast steel after service and regenerative heat treatment

Directory of Open Access Journals (Sweden)

G. Golański

2009-01-01

Full Text Available The paper presents results of research on precipitation processes in chromium – molybdenum – vanadium cast steel. Theexamined material was the following cast steel grade: L21HMF and G17CrMoV5 – 10 (L17HMF after long-term operation at elevatedtemperatures and after regenerative heat treatment. Identification of precipitates was performed by means of the transmission electronmicroscope using carbon extraction replicas and thin foils. On the basis of identifications it has been proved that in the structure ofinvestigated cast steel grades, degraded by long-term operation, there are a few sorts of carbides with diverse stability, such as: M3C; M2C, M23C6, MC, M7C3. Moreover, the occurrence of compound complexes of precipitates – the so called “H-carbides” – has been revealed. Heat treatment of the examined cast steels contributed to changes in morphology and precipitation type. Whilst in the bainitic structure, obtained through heat treatment, only the occurrence of carbide types, such as: M3C; M23C6 and MC has been noticed.

Effects of Ni and Mo on the microstructure and some other properties of Co-Cr dental alloys

International Nuclear Information System (INIS)

Matkovic, Tanja; Matkovic, Prosper; Malina, Jadranka

2004-01-01

Influences of adding Ni and Mo on the microstructure and properties of as-cast Co-Cr base alloys have been investigated in order to determine the region of their optimal characteristics for biomedical application. The alloys were produced by arc-melting technique under argon atmosphere. Using optical metallography and scanning electron micro analyser it has been established that among 10 samples of Co-Cr-Ni alloys only samples 5 and 9 with the composition Co 55 Cr 40 Ni 5 and Co 60 Cr 30 Ni 10 have appropriate dendritic solidification microstructure. This microstructure, typical for commercial dental alloys, appears and beside greater number of as-cast Co-Cr-Mo alloys. The results of hardness and corrosion resistance measurements revealed the strong influence of different alloy chemistry and of as-cast microstructure. Hardness of alloys decreases with nickel content, but increases with chromium content. Therefore all Co-Cr-Ni alloys have significantly lower hardness than Co-Cr-Mo alloys. Corrosion resistance of alloys in artificial saliva was evaluated on the base of pitting potential. Superior corrosion characteristics have the samples with typical dendritic microstructure and higher chromium content, until nickel content have not significant effect. According to this, in ternary Co-Cr-Ni phase diagram was located the small concentration region (about samples 5 and 9) in them alloy properties can satisfied the high requirements for biomedical applications. This region is considerably larger in Co-Cr-Mo phase diagram

High-Temperature Oxidation Behavior and Kinetics of Forged 12Cr-MoVW Steel

Directory of Open Access Journals (Sweden)

Kim Yong Hwan

2017-06-01

Full Text Available The oxidation kinetics of forged 12Cr-MoVW steel was investigated in an air (N2+O2 atmosphere at 873-1073 K (Δ50 K using thermogravimetric analysis. The oxidized samples were characterized using X-ray diffraction, and the surface and cross-sectional morphologies were examined using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The forged 12Cr-MoVW steel samples exhibited parabolic behavior and a low oxidation rate compared with their as-cast counterparts. A protective oxide layer was uniformly formed at relatively low temperature (≤973 K for the forged samples, which thus exhibited better oxidation resistance than the as-cast ones. These oxides are considered solid-solution compounds such as (Fe, Cr2O3.

Effect of Cr3C2 content on the microstructure and properties of Mo2NiB2-based cermets

International Nuclear Information System (INIS)

Xie, Lang; Li, XiaoBo; Zhang, Dan; Yang, ChengMing; Yin, FuCheng; Xiangtan Univ., Hunan; Xiangtan Univ., Hunan; Xiao, YiFeng

2015-01-01

Four series of Mo 2 NiB 2 -based cermets with Cr 3 C 2 addition of between 0 and 7.5 wt.% in 2.5 wt.% increments were studied by means of scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffractometry. The transverse rupture strength and hardness were also measured. It was found that Cr 3 C 2 completely dissolved in Mo 2 NiB 2 -based cermets. Cr 3 C 2 addition improved the wettability of the Ni binder phase on the Mo 2 NiB 2 hard phase, which resulted in a decrease in the porosity and an increase in the phase uniformity. The cermets with 2.5 wt.% Cr 3 C 2 content showed relatively fine grains and almost full density. A high Cr 3 C 2 content resulted in the formation of M 6 C (M = Mo, Cr, Ni) phase. In addition, energy dispersive X-ray spectroscopy results showed that the content of Mo in the binder decreased with increasing Cr 3 C 2 content. The cermets with 2.5 wt.% Cr 3 C 2 addition exhibited the highest transverse rupture strength of 2210 MPa, whereas the cermets without Cr 3 C 2 addition exhibited the highest hardness.

The Effect of Stepped Austempering on Phase Composition and Mechanical Properties of Nanostructured X37CrMoV5-1 Steel

Directory of Open Access Journals (Sweden)

Marciniak S.

2015-04-01

Full Text Available This paper presents the results of studies of X37CrMoV5-1 steel subjected to quenching processes with a one-step and a two-step isothermal annealing. The TEM observation revealed that steel after one-step treatment led is composed of carbide-free bainite with nanometric thickness of ferrite plates and of high volume fraction of retained austenite in form of thin layers or large blocks. In order to improve the strength parameters an attempt was made to reduce the austenite content by use of quenching with the two-step isothermal annealing. The temperature and time of each step were designed on the basis of dilatometric measurements. It was shown, that the two-step heat treatment led to increase of the bainitic ferrite content and resulted in improvement of steel's strength with no loss of steel ductility.

Molybdenum depletion around P-phases Ni-Cr-Mo-W weld metals

International Nuclear Information System (INIS)

Silva, Cleiton Carvalho; Miranda, Helio Cordeiro de; Farias, Jesualdo Pereira

2010-01-01

This work evaluated the local chemical composition in matrix/precipitate interface in a Ni-Cr-Mo-W alloy weld metals deposited on substrate of C-Mn steel. The microstructural characterization was carried out through optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The results had shown that the presence of secondary phases precipitates in the interdendritic region. Through SEM analysis were observed indications of depletion of Mo around these phases. These precipitates were identified as P-phase by TEM analysis. The Mo depletion indications were confirmed through EDS. The Mo depletion was a result of a reheating due to several welding heat cycles deposited to promote the coating layer. (author)

Prediction of Ductile Fracture Behaviors for 42CrMo Steel at Elevated Temperatures

Science.gov (United States)

Lin, Y. C.; Liu, Yan-Xing; Liu, Ge; Chen, Ming-Song; Huang, Yuan-Chun

2015-01-01

The ductile fracture behaviors of 42CrMo steel are studied by hot tensile tests with the deformation temperature range of 1123-1373 K and strain rate range of 0.0001-0.1 s-1. Effects of deformation temperature and strain rate on the flow stress and fracture strain of the studied steel are discussed in detail. Based on the experimental results, a ductile damage model is established to describe the combined effects of deformation temperature and strain rate on the ductile fracture behaviors of 42CrMo steel. It is found that the flow stress first increases to a peak value and then decreases, showing an obvious dynamic softening. This is mainly attributed to the dynamic recrystallization and material intrinsic damage during the hot tensile deformation. The established damage model is verified by hot forging experiments and finite element simulations. Comparisons between the predicted and experimental results indicate that the established ductile damage model is capable of predicting the fracture behaviors of 42CrMo steel during hot forging.

Porous Fe21Cr7Al1Mo0.5Y metal supports for oxygen transport membranes: Thermo-mechanical properties, sintering and corrosion behaviour

DEFF Research Database (Denmark)

Glasscock, Julie; Mikkelsen, Lars; Persson, Åsa Helen

2013-01-01

and creep rates are sufficiently low. Ceramic interlayers with graded porosity and pore-size were applied and co-fired with the metal supports, producing substrates that were shown to be viable for a 3 μm dense Ce 0.8Gd0.2O1.9 - δ oxygen transport membrane deposited using sputtering. © 2013 Elsevier B.V....... are optimised simultaneously in-situ during sintering by controlling the growth rate of the oxide scale. Oxidation of metal supports with 20-40% porosity at 850 C and oxygen partial pressure of 10- 11 kPa showed sub-parabolic kinetics and stability over 3000 h. The FeCrAl steel shows vastly superior oxidation...... resistance compared with an FeCr steel of similar composition and porosity. Modelling of the alloy lifetime as a function of surface area and Al-content was performed, and lifetimes over 30 000 h are predicted for a metal support with 30% porosity operating at a temperature of 750 C, where the oxidation...

On the corrosion testing of weldments of high alloyed CrNiMo-stainless steels and NiCrMo-alloys

International Nuclear Information System (INIS)

Riedel, G.; Voigt, C.; Werner, H.

1997-01-01

Weldments of high-alloyed CrNiMo stainless steels and NiCrMo alloys can be more susceptible to localized corrosion than the solution annealed basic material owing to segregations and precipitations in the heat affected zone, the high temperature zone and/or in the weld. To investigate these differences the FeCl 3 -test (10% FeCl 3 . 6aq), the test ''green death'' (11.5% H 2 SO 4 , 1.2% HCl, 1% CuCl 2 , 1% FeCl 3 ) as well as chronopotentiostatic tests in artificial sea water or in 3% NaCl-solution are used. In particular for testing the highest alloyed materials a CaCl 2 -test was developed (4.5 M CaCl 2 , chronopotentiostatic test in duration of 8 to 10 hours at + 200 mV (SCE)), which can be carried out to a temperature of 115 C at atmospheric pressure. The aggressivity increases in the range FeCl 3 -test, ''green death''-test, CaCl 2 -test. Matching and graduated over-alloyed weldments (TIG, heat input of 7 and 15.5 kJ/cm) of materials 1.4529, 1.4562, 2.4856, 2.4819 (german materials No.) are comparingly examined in various tests, of materials 1.4406, 1.4539, 1.4439 and 1.4563 (german materials No.) only matching weldments in the FeCl 3 -test. In strongly oxidizing media only a highly over-alloyed performed weldment (filler material 2.4607, german material No.) produces the best corrosion behaviour, measured as the critical temperatures of localized corrosion. Measurements of critical current densities of passivation can be used for investigations of corrosion behaviour of weldments, too. Critical current densities of passivation are showing a tendency to inverse proportion to the critical temperatures of localized corrosion. Suitable electrolytes are among others 0.2 M H 2 SO 4 + 1 M NaCl + 10 -3 % KSCN, N 2 -bubbled, 25 to 60 C and xM H 2 SO 4 + 4 M NaCl + 10 -3 % KSCN (x = 0.05 to 1), 25 C, in contact with air. An influence of heat input at the welding is indicated in the test of localized corrosion, but it is only small. It is sometimes more clearly shown at

Effect of carbon on the microstructure, mechanical properties and metal ion release of Ni-free Co-Cr-Mo alloys containing nitrogen.

Science.gov (United States)

Mori, Manami; Yamanaka, Kenta; Kuramoto, Koji; Ohmura, Kazuyo; Ashino, Tetsuya; Chiba, Akihiko

2015-10-01

This paper investigated the effect of carbon addition on the microstructure and tensile properties of Ni-free biomedical Co-29Cr-6Mo (mass%) alloys containing 0.2 mass% nitrogen. The release of metal ions by the alloys was preliminarily evaluated in an aqueous solution of 0.6% sodium chloride (NaCl) and 1% lactic acid, after which samples with different carbon contents were subjected to hot rolling. All specimens were found to primarily consist of a γ-phase matrix due to nitrogen doping, with only the volume fraction of M23C6 increasing with carbon concentration. Owing to the very fine size of these carbide particles (less than 1 μm), which results from fragmentation during hot rolling, the increased formation of M23C6 increased the 0.2% proof stress, but reduced the elongation-to-failure. Carbon addition also increased the amount of Co and Cr released during static immersion; Co and Cr concentrations at the surfaces, which increased with increasing the bulk carbon concentrations, possibly enhanced the metal ion release. However, only a very small change in the Mo concentration was noticed in the solution. Therefore, it is not necessarily considered a suitable means of improving the strength of biomedical Co-Cr-Mo alloys, even though it has only to date been used in this alloy system. The results of this study revealed the limitations of the carbon strengthening and can aid in the design of biomedical Co-Cr-Mo-based alloys that exhibit the high durability needed for their practical application. Copyright © 2015 Elsevier B.V. All rights reserved.

Stress-relieving annealing of Cr-Mo steel for high temperature pressure vessels and the quality change in use

International Nuclear Information System (INIS)

Makioka, Minoru; Hirano, Hiromichi

1976-01-01

The securing of good mechanical properties is difficult in thick plates for large pressure vessels because cooling rate is insufficient and time is prolonged in heat treatment. Cr-Mo steel plates are usually used in the state of improved notch toughness though somewhat reduced strength by normalizing or accelerated cooling and tempering. If the time for heat treatment is prolonged, the embrittlement occurs. The effects of temperature, holding time, and cooling rate in stress-relieving treatment on the mechanical properties of 1-1/4Cr - 1/2Mo, 2-1/4Cr - 1Mo, 3Cr - 1Mo, and 5Cr - 1/2Mo steels were investigated. The tensile strength lowered almost linearly as the hollomon-Jaffe parameter of heat treatment condition increased in all the steels. The transition temperature shifted continuously to high temperature side in 1-1/4Cr - 1/2Mo steel, but the notch toughness was improved up to certain values and then the tendency turning to brittleness was shown in the other steels, as the H-J parameter increased. When the holding time became longer, the transition temperature shifted to higher temperature side, but the cooling rate showed no effect. The condition for stress relieving treatment must be selected so that the ferrite bands observed in welded metal do not arise. The embrittlement at the operation temperature of 400 - 450 0 C for a long time is evaluated by the comparison with that by stepped cooling method. (Kako, I.)

Atomic displacements in dilute alloys of Cr, Nb and Mo

Indian Academy of Sciences (India)

physics pp. 497–514. Atomic displacements in dilute alloys of Cr, Nb and Mo ... used to calculate dynamical matrix and the impurity-induced forces up to second nearest ... origin, the lattice is strained, and the host atoms get displaced to new ...

Nanometre-scale 3D defects in Cr2AlC thin films.

Science.gov (United States)

Chen, Y T; Music, D; Shang, L; Mayer, J; Schneider, J M

2017-04-20

MAX-phase Cr 2 AlC containing thin films were synthesized by magnetron sputtering in an industrial system. Nanometre-scale 3D defects are observed near the boundary between regions of Cr 2 AlC and of the disordered solid solution (CrAl) x C y . Shrinkage of the Cr-Cr interplanar distance and elongation of the Cr-Al distance in the vicinity of the defects are detected using transmission electron microscopy. The here observed deformation surrounding the defects was described using density functional theory by comparing the DOS of bulk Cr 2 AlC with the DOS of a strained and unstrained Cr 2 AlC(0001) surface. From the partial density of states analysis, it can be learned that Cr-C bonds are stronger than Cr-Al bonds in bulk Cr 2 AlC. Upon Cr 2 AlC(0001) surface formation, both bonds are weakened. While the Cr-C bonds recover their bulk strength as Cr 2 AlC(0001) is strained, the Cr-Al bonds experience only a partial recovery, still being weaker than their bulk counterparts. Hence, the strain induced bond strengthening in Cr 2 AlC(0001) is larger for Cr d - C p bonds than for Cr d - Al p bonds. The here observed changes in bonding due to the formation of a strained surface are consistent with the experimentally observed elongation of the Cr-Al distance in the vicinity of nm-scale 3D defects in Cr 2 AlC thin films.

Overview of research trends and problems on Cr-Mo low alloy steels for pressure vessel

International Nuclear Information System (INIS)

Chi, Byung Ha; Kim, Jeong Tae

2000-01-01

Cr-Mo low alloy steels have been used for a long time for pressure vessel due to its excellent corrosion resistance, high temperature strength and toughness. The paper reviewed the latest trends on material development and some problems on Cr-Mo low alloy steel for pressure vessel, such as elevated temperature strength, hardenability, synergetic effect between temper and hydrogen embrittlement, hydrogen attack and hydrogen induced disbonding of overlay weld-cladding

Propiedades mecánicas del acero de refuerzo utilizado en Colombia Propiedades mecánicas del acero de refuerzo utilizado en Colombia

Directory of Open Access Journals (Sweden)

Victoria González Quintana

2005-04-01

Full Text Available Se presentan resultados del análisis estadístico aplicado al estudio experimental que de- termina las propiedades mecánicas de aceros colombianos sometidos a cargas monotónicas de tracción. Se obtienen curvas típicas de esfuerzo-deformación que permiten caracterizar aceros nacionales estudiados haciendo énfasis en las variables que determinan el cambio de comportamiento del materialA statistical analysis applied to a experimental study that determines the mechanical properties of steels produced in Colombia subjected to monotonic loads of tension is presented. Typical stress-strain diagram that allow to characterize these steels making emphasis in the variables that determine the change of behaviour of the materia are presented.

Properties of the passive films on Ni-Cr-Mo alloys

International Nuclear Information System (INIS)

Lloyd, A.C.; Noel, J.J.; McIntyre, N.S.; Shoesmith, D.W.

2003-01-01

Ni-Cr-Mo alloys are among the most corrosion resistant materials known, showing exceptional localized corrosion resistance under extreme industrial conditions. Accordingly, one such alloy, Alloy-22. is a candidate material for the outer sheathing of nuclear waste packages for the Yucca Mountain repository. Nevada, USA. We briefly report our results on the passive behaviour for a series of Ni-Cr-Mo alloys, with the emphasis on determining if there is a temperature dependence associated with it. The change of passive corrosion rate with temperature is a critical parameter required for long-term performance assessment calculations. The results show that alloy C22 performed better than the other members of the C-series of alloys under acidic conditions. This indicates that its selection as a waste package material is appropriate, and that it possess the potential for long-term containment of radio-nuclides. (author)

Comentarios al dossier“¿Cómo se piensa lo ‘queer’ en América Latina”?

Directory of Open Access Journals (Sweden)

Edgar Vega Suriaga

2011-05-01

Full Text Available A partir del dossier de Íconos, 39, ¿Cómo se piensa lo ‘queer’ en América Latina?, este artículo trabajasobre los puntos centrales y las interrogantes que dan de sí cada uno de los artículos que locomponen. Destaca la crítica a la masculinidad hegemónica desde una noción de la alteridad enla que convergen las categorías de clase, etnia, género y edad. A medida que reflexiona sobre estospuntos, repasa cada uno de los artículos contextualizándolos en la crítica radical al sistema heteronormativo.

Tapices y crónica, imagen y texto: un entramado persuasivo al servicio de la imagen de Carlos V

Directory of Open Access Journals (Sweden)

Antonio Gozalbo

2016-12-01

Full Text Available Las consecuencias artísticas de la conquista de Túnez por Carlos V (1535 resultaron fundamentales para la articulación plena de su imagen de poder. Dentro de este amplio conjunto de manifestaciones plásticas y literarias destaca la monumental serie de tapices de «La Jornada de Túnez». Con el presente artículo queremos aportar mayor claridad a la tesis que otorga la autoría intelectual del conjunto al cronista Alonso de Santa Cruz, mostrando los evidentes vínculos entre los paños y su Crónica del Emperador Carlos V. Así pues, tapices y crónica con uyeron generando un potente entramado icónico-literario destinado a la miti cación de Carlos V. The artistic consequences of the conquest of Tunis by Charles V (1535 were essential in the full articulation of its image of power. Within this broad set of visual and literary artistic expressions the monumental series of tapestries of «la Jornada de Túnez» are highlighted. In this article we want to throw light upon the thesis of intellectual authorship of the whole work attributed to the chronicler Alonso de Santa Cruz, showing the obvious links between tapestries and his Chronicle of Emperor Charles V. us, tapestries and chronicle converged generating a powerful iconic literary framework intended to mythicize Charles V.

Parametric and experimentally informed BWR Severe Accident Analysis Utilizing FeCrAl - M3FT-17OR020205041

Energy Technology Data Exchange (ETDEWEB)

Ott, Larry J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howell, Michael [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-08-01

Iron-chromium-aluminum (FeCrAl) alloys are being considered as advanced fuel cladding concepts with enhanced accident tolerance. At high temperatures, FeCrAl alloys have slower oxidation kinetics and higher strength compared with zirconium-based alloys. FeCrAl could be used for fuel cladding and spacer or mixing vane grids in light water reactors and/or as channel box material in boiling water reactors (BWRs). There is a need to assess the potential gains afforded by the FeCrAl accident-tolerant-fuel (ATF) concept over the existing zirconium-based materials employed today. To accurately assess the response of FeCrAl alloys under severe accident conditions, a number of FeCrAl properties and characteristics are required. These include thermophysical properties as well as burst characteristics, oxidation kinetics, possible eutectic interactions, and failure temperatures. These properties can vary among different FeCrAl alloys. Oak Ridge National Laboratory has pursued refined values for the oxidation kinetics of the B136Y FeCrAl alloy (Fe-13Cr-6Al wt %). This investigation included oxidation tests with varying heating rates and end-point temperatures in a steam environment. The rate constant for the low-temperature oxidation kinetics was found to be higher than that for the commercial APMT FeCrAl alloy (Fe-21Cr-5Al-3Mo wt %). Compared with APMT, a 5 times higher rate constant best predicted the entire dataset (root mean square deviation). Based on tests following heating rates comparable with those the cladding would experience during a station blackout, the transition to higher oxidation kinetics occurs at approximately 1,500°C. A parametric study varying the low-temperature FeCrAl oxidation kinetics was conducted for a BWR plant using FeCrAl fuel cladding and channel boxes using the MELCOR code. A range of station blackout severe accident scenarios were simulated for a BWR/4 reactor with Mark I containment. Increasing the FeCrAl low-temperature oxidation rate

Stress-controlled inelastic behavior of modified 9 Cr-1 Mo steel at elevated temperatures

International Nuclear Information System (INIS)

Taguchi, Kosei.

1989-01-01

Interest in the ferritic steels of higher chromium concentration has increased recently because of an economical combination of mechanical and corrosion properties at elevated temperatures. A modified 9 Cr-1 Mo ferritic steel, developed in the United States, has been expected as an alternative structural material for fast breeder reactor components, in which Type 304 stainless steel or 2.25 Cr-1 Mo steel is currently used. For application of this material to the structural components, a lot of work has been done to develop evaluation methods for the deformation behavior and strength properties. The authors have studied the inelastic behavior and the creep-fatigue properties of modified 9 Cr-1 Mo steel at elevated temperatures, and proposed a constitutive equation and a creep-fatigue damage equation based on the overstress concept. In this paper, the applicability is discussed of the constitutive equation to stress-controlled inelastic behavior, such as creep strain hardening and stress cycling

Comportamiento del acero de baja aleación SA-508 y del acero al carbono A-410b en las condiciones de operación y parada del circuito primario de los reactores de agua ligera tipo PWR

Directory of Open Access Journals (Sweden)

García-Redondo, María del Sol

2000-04-01

Full Text Available The corrosion rate of low alloy steel SA-508 and carbon steel A-410b in simulated operation and shutdown conditions of pressurized water reactor has been determined. Moreover potentiodynamic polarization curves and galvanic effect through coupling of AISI-304 have been carried out under shutdown simulated condition.

En este trabajo se ha determinado la cinética de corrosión del acero de baja aleación SA-508 y del acero al carbono A-410b en condiciones que simulan la operación y la parada de los reactores de agua ligera a presión. También se han realizado curvas de polarización potenciodinámica y se ha estudiado el acoplamiento galvánico con AISI-304 en condiciones de parada de los reactores de agua ligera a presión.

Structure and tribological properties of MoS2 low friction thin films

Directory of Open Access Journals (Sweden)

Paradecka Agnieszka

2017-01-01

Full Text Available The main aim of the studies was the deposition of the AlCrN film, covered by molybdenum disulphide (MoS2 – based lubricant, on the austenitic steel substrate. The AlCrN and MoS2 layers were deposited by PVD lateral rotating ARC-cathodes (LARC and magnetron sputtering technology on the X6CrNiMoTi17-12-2 respectively. Structural characterizations of the MoS2 thin films have been carried out using SEM (scanning electron microscopy and AFM (atomic force microscopy to determine the surface topography as well as HRTEM (high-resolution transmission electron microscopy and Raman spectroscopy for structural investigations. The tribological wear relationships using ball-on-disc test were specified for surface layers, determining the friction co-efficient and mass loss of the investigated surfaces. Tests of the coatings’ adhesion to the substrate material were made using the scratch test. HRTEM investigation shows an amorphous character of the MoS2 layer. In sliding dry friction conditions, the friction co-efficient for the investigated elements is set in the range between 0.4-0.5. The investigated coating reveals high wear resistance. The coating demonstrated a dense cross-sectional morphology as well as good adhesion to the substrate. The good properties of the PVD AlCrN+MoS2 coatings make them suitable in various engineering and industrial applications.

Comparison of AlCrN and AlCrTiSiN coatings deposited on the surface of plasma nitrocarburized high carbon steels

International Nuclear Information System (INIS)

Chen, Wanglin; Zheng, Jie; Lin, Yue; Kwon, Sikchol; Zhang, Shihong

2015-01-01

Highlights: • The duplex coatings were produced by combination of nitrocarburizing and multi-arc ion plating. • The γ′-phase plays the nucleation sites for the coating nitrides. • The compound layers (CL) considerably enhance mechanical and tribological properties of the duplex PVD coatings. • The main wear mechanisms of the PVD coatings with and without CL are oxidation wear, the combination of spalling, chipping and oxidation wear, respectively. - Abstract: The AlCrN and AlCrTiSiN coatings were produced on the surface of plasma nitrocarburized T10 steels by multi-arc ion plating. The comparison of the microstructures and mechanical properties of the duplex coatings were investigated by means of X-ray diffraction, optical microscope, scanning electron microscope and transmission electron microscope, in association with mechanical property measurement. The results show that the AlCrN coatings with columnar grown are mainly composed of nanocrytalline fcc-(Cr,Al)N phases with {111} preferred orientation, whereas the superlattice and nanocomposite AlCrTiSiN coatings with planar growth mainly consist of nanocrystalline fcc-(Cr,Al)N phases with {100} perfected orientation, hcp-AlN and Si 3 N 4 amorphous phases. The AlCrTiSiN duplex coating with the compound layer reveals higher hardness, adhesion strength, load capacity and lower friction coefficient when compared with the other duplex coatings, which is due to its superlattice and nanocomposite structure. Additionally, these improved properties are related to the appearance of the γ′-phase which plays the nucleation sites for the coating nitrides and provides a strong supporting effect for the AlCrN and AlCrTiSiN coatings. The main wear mechanism of the duplex coatings without compound layer is spalling and chipping wear as well as tribooxidation wear, whereas the main wear mechanism of the duplex coatings with compound layer is tribooxidation wear

Corrosion-resistant amorphous metallic films of Mo49Cr33B18 alloy

Science.gov (United States)

Ramesham, R.; Distefano, S.; Fitzgerald, D.; Thakoor, A. P.; Khanna, S. K.

1987-01-01

Corrosion-resistant amorphous metallic alloy films of Mo49Cr33B18 with a crystallization temperature of 590 C were deposited onto glass and quartz substrates by magnetron sputter-quench technique. The amorphous nature of the films was confirmed by their diffuse X-ray diffraction patterns. The deposited films are densely packed (zone T) and exhibit low stress and good adhesion to the substrate. Corrosion current of as-deposited coating of MoCrB amorphous metallic alloy is approximately three orders of magnitude less than the corrosion current of 304 stainless steel in 1N H2SO4 solution.

Formation of (Cr, Al)UO{sub 4} from doped UO{sub 2} and its influence on partition of soluble fission products

Energy Technology Data Exchange (ETDEWEB)

Cooper, M.W.D. [Department of Materials, Imperial College London, London (United Kingdom); Gregg, D.J.; Zhang, Y.; Thorogood, G.J.; Lumpkin, G.R. [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales (Australia); Grimes, R.W. [Department of Materials, Imperial College London, London (United Kingdom); Middleburgh, S.C., E-mail: simm@ansto.gov.au [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales (Australia)

2013-11-15

CrUO{sub 4} and (Cr, Al)UO{sub 4} have been fabricated by a sol–gel method, studied using diffraction techniques and modelled using empirical pair potentials. Cr{sub 2}O{sub 3} was predicted to preferentially form CrUO{sub 4} over entering solution into hyper-stoichiometric UO{sub 2+x} by atomic scale simulation. Further, it was predicted that the formation of CrUO{sub 4} can proceed by removing excess oxygen from the UO{sub 2} lattice. Attempts to synthesise AlUO{sub 4} failed, instead forming U{sub 3}O{sub 8} and Al{sub 2}O{sub 3}. X-ray diffraction confirmed the structure of CrUO{sub 4} and identifies the existence of a (Cr, Al)UO{sub 4} phase for the first time (with a maximum Al to Cr mole ratio of 1:3). Simulation was subsequently used to predict the partition energies for the removal of fission products or fuel additives from hyper-stoichiometric UO{sub 2+x} and their incorporation into the secondary phase. The partition energies are consistent only with smaller cations (e.g. Zr{sup 4+}, Mo{sup 4+} and Fe{sup 3+}) residing in CrUO{sub 4}, while all divalent cations are predicted to remain in UO{sub 2+x}. Additions of Al had little effect on partition behaviour. The reduction of UO{sub 2+x} due to the formation of CrUO{sub 4} has important implications for the solution limits of other fission products as many species are less soluble in UO{sub 2} than UO{sub 2+x}.

Characterization of the reaction layer in U-7wt%Mo/Al diffusion couples

Energy Technology Data Exchange (ETDEWEB)

Mirandou, M.I.; Balart, S.N.; Ortiz, M.; Granovsky, M.S. E-mail: granovsk@cnea.gov.ar

2003-11-15

The reaction layer in chemical diffusion couples U-7wt%Mo/Al was investigated using optical and scanning electron microscopy, electron probe microanalysis and X-ray diffraction (XRD) techniques. When the U-7wt%Mo alloy was previously homogenized and the {gamma}(U, Mo) phase was retained, the formation of (U, Mo)Al{sub 3} and (U, Mo)Al{sub 4} was observed at 580 deg. C. Also a very thin band was detected close to the Al side, the structure of the ternary compound Al{sub 20}UMo{sub 2} might be assigned to it. When the decomposition of the {gamma}(U, Mo) took place, a drastic change in the diffusion behavior was observed. In this case, XRD indicated the presence of phases with the structures of (U, Mo)Al{sub 3}, Al{sub 43}U{sub 6}Mo{sub 4}, {gamma}(U, Mo) and {alpha}(U) in the reaction layer.

Elaboration and characterization of fluorohydroxyapatite and fluoroapatite sol−gel coatings on CoCrMo alloy

Energy Technology Data Exchange (ETDEWEB)

Romonţi, D. Covaciu [University “Politehnica” of Bucharest, Faculty of Applied Chemistry and Materials Science 1-7, Polizu Str., 011061, Bucharest (Romania); Iskra, J. [Jožef Stefan Institute, Department of Physical and Organic Chemistry, Jamova 39, SI-6280 (Slovenia); Bele, M. [National Institute of Chemistry, Laboratory for Materials Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia); Demetrescu, I. [University “Politehnica” of Bucharest, Faculty of Applied Chemistry and Materials Science 1-7, Polizu Str., 011061, Bucharest (Romania); Milošev, I., E-mail: ingrid.milosev@ijs.si [Jožef Stefan Institute, Department of Physical and Organic Chemistry, Jamova 39, SI-6280 (Slovenia)

2016-04-25

The surface of CoCrMo alloy used in orthopedic and dental applications was modified in order to improve its osseointegration. Fluorohydroxyapatite and fluoroapatite coatings were prepared by the sol–gel procedure and deposited on CoCrMo substrate by immersion. The steps of sol–gel synthesis were studied using Fourier transform infrared spectroscopy. The surfaces of the coatings were characterized using scanning electron microscopy and X-ray diffraction. The electrochemical properties of coatings were tested in Fusayama artificial saliva using polarization measurements. The most stable coating was fluorohydroxyapatite. It also has the strongest adhesion. - Highlights: • Fluorohydroxyapatite and fluoroapatite coatings were deposited by sol–gel process. • Synthesis was optimized in situ using Fourier transform infrared spectroscopy. • Coatings provide corrosion protection of CoCrMo substrate in artificial saliva. • Coatings are macroscopically dense, homogeneous and adhere well to the substrate.

Elaboration and characterization of fluorohydroxyapatite and fluoroapatite sol−gel coatings on CoCrMo alloy

International Nuclear Information System (INIS)

Romonţi, D. Covaciu; Iskra, J.; Bele, M.; Demetrescu, I.; Milošev, I.

2016-01-01

The surface of CoCrMo alloy used in orthopedic and dental applications was modified in order to improve its osseointegration. Fluorohydroxyapatite and fluoroapatite coatings were prepared by the sol–gel procedure and deposited on CoCrMo substrate by immersion. The steps of sol–gel synthesis were studied using Fourier transform infrared spectroscopy. The surfaces of the coatings were characterized using scanning electron microscopy and X-ray diffraction. The electrochemical properties of coatings were tested in Fusayama artificial saliva using polarization measurements. The most stable coating was fluorohydroxyapatite. It also has the strongest adhesion. - Highlights: • Fluorohydroxyapatite and fluoroapatite coatings were deposited by sol–gel process. • Synthesis was optimized in situ using Fourier transform infrared spectroscopy. • Coatings provide corrosion protection of CoCrMo substrate in artificial saliva. • Coatings are macroscopically dense, homogeneous and adhere well to the substrate.

Creep-fatigue life prediction method using Diercks equation for Cr-Mo steel

International Nuclear Information System (INIS)

Sonoya, Keiji; Nonaka, Isamu; Kitagawa, Masaki

1990-01-01

For dealing with the situation that creep-fatigue life properties of materials do not exist, a development of the simple method to predict creep-fatigue life properties is necessary. A method to predict the creep-fatigue life properties of Cr-Mo steels is proposed on the basis of D. Diercks equation which correlates the creep-fatigue lifes of SUS 304 steels under various temperatures, strain ranges, strain rates and hold times. The accuracy of the proposed method was compared with that of the existing methods. The following results were obtained. (1) Fatigue strength and creep rupture strength of Cr-Mo steel are different from those of SUS 304 steel. Therefore in order to apply Diercks equation to creep-fatigue prediction for Cr-Mo steel, the difference of fatigue strength was found to be corrected by fatigue life ratio of both steels and the difference of creep rupture strength was found to be corrected by the equivalent temperature corresponding to equal strength of both steels. (2) Creep-fatigue life can be predicted by the modified Diercks equation within a factor of 2 which is nearly as precise as the accuracy of strain range partitioning method. Required test and analysis procedure of this method are not so complicated as strain range partitioning method. (author)

Modification of the microstructure of a weld of the same composition as X 20 CrMoV 12 1 by means of purely thermal aging and by aging under mechanical stress at 550 C

International Nuclear Information System (INIS)

Deimel, P.; Hoffmann, M.; Kuppler, D.

1991-01-01

The experiments were to contribute deeper insight into the mechanisms and effects induced by long-term, purely thermal aging and by aging over the same period under mechanical stress in a weld of the same composition as X 20 CrMoV 12 1, which are known to cause microstructural changes resulting in modified toughness of the weld. (orig.) [de

Al2O3 adherence on CoCrAl alloys

International Nuclear Information System (INIS)

Kingsley, L.M.

1980-04-01

Adherence of protective oxides on NiCrAl and CoCrAl superalloys has been promoted by a dispersion of a highly oxygen reactive element or its oxide being produced within the protection system. Two aspects of this subject are investigated here: the use of Al 2 O 3 as both the dispersion and protective oxide; and the production of an HfO 2 dispersion while simultaneously aluminizing the alloy. It was found that an Al 2 O 3 dispersion will act to promote the adherence of an external scale of Al 2 O 3 to a degree comparable to previously tested dispersions and an HfO 2 dispersion comparable to that produced by a Rhines pack treatment is produced during aluminization

Adsorption of oxyanions of As, B, Cr, Mo and Se from coal fly ash leachates using Al3+/Fe3+modified bentonite clay

CSIR Research Space (South Africa)

Vhahangwele, M

2013-01-01

Full Text Available ponds. On disposal, coal fly ash leaches out toxic chemical species on contact with the aqueous media hence posing hazardous effects to the aquatic and terrestrial environment. Of prime concern are Oxyanionic species such as As, B, Cr, Mo and Se...

First-principles investigations of disorder effects on electronic structure and magnetic properties in Sr2CrMoO6

International Nuclear Information System (INIS)

Li, Q F; Zhu, X F; Chen, L F

2008-01-01

The electronic structures and magnetic properties are reported for ordered and disordered Sr 2 CrMoO 6 presenting oxygen vacancies or/and antisite defects (ASs). We investigate the stability of an antiparallel (AP) magnetic moment on Cr antisites and the calculations show that these solutions are more stable relative to the parallel solution for AS defects with or without oxygen vacancies. Electronic band structure calculations indicate that the perfect Sr 2 CrMoO 6 is half-metallic, and the half-metallic character is preserved for Sr 2 CrMoO 6 containing only oxygen vacancies, while the half-metallic nature is destroyed when 25% ASs (50% ASs) with or without oxygen vacancies is present. For 25% ASs with two oxygen vacancies, the system possibly shows nonmetallic behavior. The experimentally observed reduction of the magnetic moment mainly arises from an antiferromagnetic coupling of Cr-O-Cr (Cr-Cr) bonds in a disordered sample

Corrosion Resistance of Co-Cr-Mo Alloy Used in Dentistry

Directory of Open Access Journals (Sweden)

Łukaszczyk A.

2015-04-01

Full Text Available The presented paper studies the effect of the casting technology on the corrosion resistance of Co-Cr-Mo alloy. The investigations were conducted on a commercial alloy with the brand name ARGELOY N.P SPECIAL (Co-Cr-Mo produced by Argen as well as the same alloy melted and cast by the lost wax casting method performed by a dental technician. The corrosion behavior of the dental alloys in an artificial saliva was studied with the use of the following electrochemical techniques: open circuit potential and voltammetry. After the electrochemical tests, studies of the surface of the examined alloys were performed by means of a scanning electron microscope with an X-ray microanalyzer. The results of the electrochemical studies show that the dependence of the corrosion resistance on the microstructure associated with the recasting process is marginal. The results of the electrochemical studies of the considered alloy clearly point to their good corrosion resistance in the discussed environment.

Reacciones en estado sólido para el sistema Al-MoO₃ en la fabricación de materiales compuestos Al₂O₃-aluminuros de Mo

Directory of Open Access Journals (Sweden)

Marín, J.

2002-02-01

velocidad de calentamiento de 1 °C/min en el rango crítico de temperaturas (500-600 °C se logra el control de las reacciones de aluminotermia. Análisis por DRX y MEB indican que la microestructura del material compuesto sinterizado presenta una matriz de Al₂O₃ y una fase dispersa compuesta de aluminuros de Mo y molibdeno metálico. La composición de la mezcla precursora influye en la naturaleza de la fase dispersa del compuesto (aluminuros de molibdeno y/o Mo metálico, en las cantidades relativas de Al₂O₃/segunda fase y en la dureza del material sinterizado a 1.450 °C.

Combustion synthesis of CoCrMo orthopedic implant alloys: microstructure and properties

International Nuclear Information System (INIS)

Li, Bingyun; Mukasyan, Alexander; Varma, Arvind

2003-01-01

Because of their excellent properties, such as corrosion resistance, fatigue strength and biocompatibility, cobalt-based alloys are widely used in total hip and knee replacements, dental devices and support structures for heart valves. In this work, CoCrMo alloys were synthesized using a novel method based on combustion synthesis (CS), an advanced technique to produce a wide variety of materials including alloys and near-net shape articles. This method possesses several advantages over conventional processes, such as low energy requirements, short processing times and simple equipment. The evaluated material properties included density and yield measurements, composition and microstructure analysis, hardness, friction and tensile tests. It was shown that microstructure of CS-material is finer and more uniform as compared to the conventional standard. It was also found that among various additives, Cr 3 C 2 is the most effective one for increasing material hardness. In addition, synthesized CoCrMo alloys exhibited good friction and mechanical properties. (orig.)

The Influence of Plasma-Based Nitriding and Oxidizing Treatments on the Mechanical and Corrosion Properties of CoCrMo Biomedical Alloy

Science.gov (United States)

Noli, Fotini; Pichon, Luc; Öztürk, Orhan

2018-04-01

Plasma-based nitriding and/or oxidizing treatments were applied to CoCrMo alloy to improve its surface mechanical properties and corrosion resistance for biomedical applications. Three treatments were performed. A set of CoCrMo samples has been subjected to nitriding at moderate temperatures ( 400 °C). A second set of CoCrMo samples was oxidized at 395 °C in pure O2. The last set of CoCrMo samples was nitrided and subsequently oxidized under the experimental conditions of previous sets (double treatment). The microstructure and morphology of the layers formed on the CoCrMo alloy were investigated by X-ray diffraction, Atomic Force Microscopy, and Scanning Electron Microscopy. In addition, nitrogen and oxygen profiles were determined by Glow Discharge Optical Emission Spectroscopy, Rutherford Backscattering Spectroscopy, Energy-Dispersive X-ray, and Nuclear Reaction Analysis. Significant improvement of the Vickers hardness of the CoCrMo samples after plasma nitriding was observed due to the supersaturated nitrogen solution and the formation of an expanded FCC γ N phase and CrN precipitates. In the case of the oxidized samples, Vickers hardness improvement was minimal. The corrosion behavior of the samples was investigated in simulated body fluid (0.9 pct NaCl solution at 37 °C) using electrochemical techniques (potentiodynamic polarization and cyclic voltammetry). The concentration of metal ions released from the CoCrMo surfaces was determined by Instrumental Neutron Activation Analysis. The experimental results clearly indicate that the CoCrMo surface subjected to the double surface treatment consisting in plasma nitriding and plasma oxidizing exhibited lower deterioration and better resistance to corrosion compared to the nitrided, oxidized, and untreated samples. This enhancement is believed to be due to the formation of a thicker and more stable layer.

Assessment of the integrity of ferritic-austenitic dissimilar weld joints of different grades of Cr-Mo ferritic steels

Energy Technology Data Exchange (ETDEWEB)

Laha, K.; Chandravathi, K.S.; Parameswaran, P.; Goyal, Sunil; Mathew, M.D. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Metallurgy and Materials Group

2010-07-01

Integrity of the 2.25 Cr-1Mo / Alloy 800, 9Cr-1Mo / Alloy 800 and 9Cr-1Mo-VNb / Alloy 800 ferritic-austenitic dissimilar joints, fusion welded employing Inconel 182 electrode, has been assessed under creep conditions at 823 K. The dissimilar weld joints displayed lower creep rupture strength than their respective ferritic steel base metals. The strength reduction was more for 2.25Cr-1Mo steel joint and least for 9Cr-1Mo steel joint. The failure location in the joints was found to shift from the ferritic steel base metal to the intercritical region of heat-affected zone (HAZ) in ferritic steel (type IV cracking) with decrease in stress. At still lower stresses the failure occurred at the ferritic / austenitic weld interface. Localized creep deformation and cavitation in the soft intercritical HAZ induced type IV failure whereas creep cavitation at the weld interface particles induced ferritic / austenitic interface cracking due to high creep strength mismatch across it. Micromechanisms of type IV failure and interface cracking in the ferritic / austenitic joints and different susceptibility to failure for different grades of ferritic steels are discussed based on microstructural investigation, mechanical testing and finite element analysis. (Note from indexer: paper contains many typographical errors.)

PENGARUH SERBUK U-Mo HASIL PROSES MEKANIK DAN HYDRIDE – DEHYDRIDE – GRINDING MILL TERHADAP KUALITAS PELAT ELEMEN BAKAR U-Mo/Al

Directory of Open Access Journals (Sweden)

Supardjo Supardjo

2015-07-01

Full Text Available PENGARUH SERBUK U-Mo HASIL PROSES MEKANIK DAN HYDRIDE – DEHYDRIDE – GRINDING MILL TERHADAP KUALITAS PELAT ELEMEN BAKAR U-Mo/Al. Penelitian bahan bakar U-7Mo/Al tipe pelat dilakukan dalam rangka pengembangan bahan bakar U3Si2/Al untuk mendapatkan bahan bakar baru yang memiliki densitas uranium lebih tinggi, stabil selama digunakan sebagai bahan bakar di dalam reaktor dan mudah dilakukan proses olah ulangnya. Lingkup penelitian meliputi pembuatan: paduan U-7Mo dengan teknik peleburan, pembuatan serbuk U-7Mo dengan dikikir dan hydride - dehydride - grinding mill, IEB U-7Mo/Al dengan teknik kompaksi pada tekanan 20 bar, dan PEB U-7Mo/Al dengan teknik pengerolan panas pada temperatur 425oC. Paduan U-7Mo hasil proses peleburan cukup homogen, berat jenis 16,34 g/cm3 dan bersifat ulet, kemudian dibuat menjadi serbuk dengan cara dikikir dan hydride - dehydride - grinding mill. Serbuk U-7Mo hasil proses kikir berbentuk pipih, kontaminan Fe cukup tinggi, sedangkan serbuk hasil proses hydride - dehydride - grinding mill, cenderung equiaxial dengan kontaminan yang rendah. Kedua jenis serbuk U-7Mo tersebut digunakan sebagai bahan baku pembuatan IEB U-7Mo/Al dan PEB U-7Mo/Al dengan densitas uranium 7 gU/cm3 dan diperoleh produk dengan kualitas yang hampir sama. Hasil uji IEB U-7Mo/Al berukuran 25 x 15 x 3,15±0,05 mm, tidak terdapat cacat/retak, distribusi U-7Mo di dalam matriks cukup homogen dan tidak terdapat pengelompokan/aglomerasi U-7Mo yang berdimensi >1 mm. PEB U-7Mo/Al hasil pengerolan dengan tebal akhir 1,45 mm, memiliki ketebalan meat rerata 0,60 mm dan tebal kelongsong 0,4 mm dan terdapat 1 titik pengukuran kelongsong dengan ketebalan 0,15 mm. Dengan membandingkan penggunaan kedua jenis serbuk U-7Mo tersebut, IEB U-7Mo/Al dan PEB U-7Mo/Al yang dihasilkan memiliki kualitas hampir sama. Namun demikian penggunaan serbuk U- 7Mo hasil proses hydride - dehydride - grinding mill lebih baik karena proses pengerjaannya lebih cepat dan impuritas dalam

An analysis of a set of creep data for a 9Cr-1Mo-0.2V (P91 type) steel

International Nuclear Information System (INIS)

Cadek, J.; Sustek, V.; Pahutova, M.

1997-01-01

Recently published creep data for a 9Cr-1Mo-0.2V steel are analysed and an attempt is made to interpret them applying the concept of thermally activated detachment of dislocations from carbide particles as the rate controlling process. For the data, very high and stress dependent apparent activation energy of creep, Q c , and very high and temperature dependent apparent stress exponent, m c , are characteristic. The modelling of creep behavior applying the above mentioned concept is shown to fail to account for this temperature and applied stress dependence of minimum creep strain rate and/or the values of Q c and m c following from the data analysis. It is suggested that the behavior of the dislocation substructure, which is affected by the presence of carbide particles, must be introduced into any model to adequately describe the unusual creep behavior of the steel of interest. (orig.)

A preparation method and effects of Al-Cr coating on NdFeB sintered magnets

Energy Technology Data Exchange (ETDEWEB)

Zheng, Jingwu [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China); Lin, Min, E-mail: linm@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering Chinese Academy of Science, 519 Road Zhuangshi, District Zhenghai, Ningbo 315201, People' s Republic of China (China); Xia, Qingping [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China)

2012-11-15

A 50 {mu}m Al-Cr coating on NdFeB sintered magnets was prepared through dipping in solution, shaking dry and heating at 300 Degree-Sign C. The morphology and composition of the Al-Cr coating were investigated with scanning electron microscope, energy dispersive spectrometer and X-ray diffraction. The corrosion resistance of NdFeB sintered magnets with and without the Al-Cr coating was analyzed by normal salt spray, polarization curves and electrochemical impedance spectroscopy. The magnetic properties were measured with a hysteresis loop tracer. The results show that the Al-Cr coating forms an overlapping structure and Al flakes lie nearly parallel to the substrate, which improves the anticorrosion and increases normal salt spray test from 10 to 100 h. The corrosion potential of NdFeB sintered magnets with and without the Al-Cr coating moves positively from -0.67 to -0.48 V, which is in accordance with Nyquist and Bode plots. The Al-Cr coating has little influence on the magnetic properties of the NdFeB sintered magnets. - Highlights: Black-Right-Pointing-Pointer The Al-Cr coating can be prepared by dipping in solution, shaking dry and heating. Black-Right-Pointing-Pointer The coating morphology shows to be an intense overlapping structure. Black-Right-Pointing-Pointer The barrier effect combines with passivation and cathodic protection. Black-Right-Pointing-Pointer The anticorrosion abilities improve while magnetic properties change little. Black-Right-Pointing-Pointer Compared with other surface treatments, this method is convenient and low cost.

Diffusion-induced quadrupole relaxation of 27Al nuclei in dilute Al-Ti, Al-Cr, Al-Mn, and Al-Cu alloys at high temperatures

International Nuclear Information System (INIS)

Bottyan, L.; Beke, D.L.; Tompa, K.

1983-01-01

The temperature dependence of the laboratory frame spin-lattice relaxation time of 27 Al nuclei is measured in 5N Al and in dilute Al-Ti, Al-Cr, Al-Mn, and Al-Cu alloys at 5.7 and 9.7 MHz resonance frequencies. The relaxation in pure aluminium is found to be purely due to the conduction electrons. An excess T 1 -relaxation contribution is detected in all Al-3d alloys investigated above 670 K. The excess relaxation rate is proportional to the impurity content and the temperature dependence of the excess contribution is of Arrhenius-type with an activation energy of (1.3 +- 0.3) eV for all of the investigated alloys. The relaxation contribution is found to be quadrupolar in origin and is caused by the relative diffusional jumps of solute atoms and Al atoms relatively far from the impurity. (author)

Surface morphology of scale on FeCrAl (Pd, Pt, Y) alloys

International Nuclear Information System (INIS)

Amano, T.; Takezawa, Y.; Shiino, A.; Shishido, T.

2008-01-01

The high temperature oxidation behavior of Fe-20Cr-4Al, floating zone refined (FZ) Fe-20Cr-4Al, Fe-20Cr-4Al-0.5Pd, Fe-20Cr-4Al-0.5Pt and Fe-20Cr-4Al-(0.01, 0.02, 0.05, 0.1, 0.2, 0.5)Y alloys was studied in oxygen for 0.6-18 ks at 1273-1673 K by mass gain measurements, X-ray diffraction and scanning electron microscopy. The mass gains of FeCrAl, FZ FeCrAl, FeCrAlPd and FeCrAlPt alloys showed almost the same values. Those of FeCrAl-(0.01, 0.02, 0.05, 0.1, 0.2, 0.5)Y alloys decreased with increasing yttrium of up to 0.1% followed by an increase with the yttrium content after oxidation for 18 ks at 1473 K. Needle-like oxide particles were partially observed on FeCrAl alloy after oxidation for 7.2 ks at 1273 K. These oxide particles decreased in size with increasing oxidation time of more than 7.2 ks at 1473 K, and then disappeared after oxidation for 7.2 ks at 1573 K. It is suggested that a new oxide develops at the oxygen/scale interface. The scale surface of FeCrAl alloy showed a wavy morphology after oxidation for 7.2 ks at 1273 K which then changed to planar morphology after an oxidation time of more than 7.2 ks at 1573 K. On the other hand, the scale surfaces of other alloys were planar after all oxidation conditions in this study. The scale surfaces of FeCrAl, FZ FeCrAl, FeCrAlPd and FeCrAlPt alloys were rough, however, those of FeCrAl-(0.1, 0.2, 0.5)Y alloys were smooth. The oxide scales formed on FeCrAl-(0.1, 0.2, 0.5)Y alloys were found to be α-Al 2 O 3 with small amounts of Y 3 Al 5 O 12 , and those of the other alloys were only α-Al 2 O 3

Study of alpha-case depth in Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V

International Nuclear Information System (INIS)

Gaddam, R; Sefer, B; Pederson, R; Antti, M-L

2013-01-01

At temperatures exceeding 480°C titanium alloys generally oxidises and forms a hard and brittle layer enriched with oxygen, which is called alpha case. This layer has negative effects on several mechanical properties and lowers the tensile ductility and the fatigue resistance. Therefore any alpha-case formed on titanium alloys during various manufacturing processes, such as heat treatment procedures, must be removed before the final part is mounted in an engine. In addition, long time exposure at elevated temperatures during operation of an engine could possibly also lead to formation of alpha-case on actual parts, therefore knowledge and understanding of the alpha-case formation and its effect on mechanical properties is important. Factors that contribute for growth of alpha-case are: presence of oxygen, exposure time, temperature and pressure. In the present study, isothermal oxidation experiments in air were performed on forged Ti-6Al-2Sn-4Zr-2Mo at 500°C and 593°C up to 500 hours. Similar studies were also performed on Ti-6Al-4V plate at 593°C and 700°C. Alpha-case depth for both alloys was quantified using metallography techniques and compared

Fracture behavior of unirradiated HT-9 and modified 9Cr-1Mo welds

International Nuclear Information System (INIS)

Huang, F.H.; Gelles, D.S.

1983-05-01

Fracture toughness tests on HT-9 weld and HAZ samples and modified 9Cr-1Mo weld samples were performed at 93, 205, 427 and 538 0 C. Specimens were of circular compact tension type fabricated from welded material with the notch orientation parallel to the fusion line. The test results were analyzed using the J-integral approach. The results demonstrated that the toughness of HT-9 and 9Cr-1Mo was not significantly reduced due to welding. However, the tearing modulus of the welded material was lower than that of base metal, indicating that the alloys become less resistant to crack propagation as a result of welding

Stress corrosion cracking in 3,5 NiCrMoV steel in a 403 K potential-PH diagram

International Nuclear Information System (INIS)

Hitomi, Itoh; Takashi, Momoo

2001-01-01

3,5 NiCrMoV steel is used in low-pressure turbine rotors and discs. It has been pointed out that intergranular stress corrosion cracking may occur in this material in the wet region at temperatures of about 400 K. Accordingly, the authors focused on the environmental conditions under which stress corrosion cracking (SCC) occurs. A potential-pH diagram was used to investigate the region in which SCC occurs in the high strength materials that are particularly susceptible to SCC. The investigation found that SCC is initiated in this material not only in the high caustic region but in the neutral region as well. The investigation also found that initiation and propagation were accelerated in dissolved oxygen environments with increased chemical potential in the neutral region. Since careful observation of the starting point of cracks has shown that corrosion pits trigger SCC, subsequent immersion tests under constant potential were conducted. The results showed that corrosion pits are generated at the high potential range. These results led to the development of an acceleration test environment for laboratory to determine the susceptibility of SCC in field turbine disc and rotor materials. (author)

Morphology and Performance of 5Cr5MoV Casting Die Steel in the Process of Surfacing

Science.gov (United States)

Song, Yulai; Kong, Xiangrui; Yang, Pengcong; Fu, Hongde; Wang, Xuezhu

2017-12-01

To investigate the microstructures and mechanical properties of the deposited metal on surface of die steel, two layer of weld-seam were prepared on the surface of 5Cr5MoV die steel by arc surfacing. The surface microstructures and microhardness were characterized by scanning electron microscopy, energy dispersive spectrometer and Vickers microhardness tester, respectively. The effect of load on the abrasion resistance and wear mechanism of the base metal and surfacing metal was studied by pin-on-disk tribometer. The results showed that martensite and retained austenite exist in weld-seam, both of them grow up in the form of dendrites and equiaxed grains and microhardness reach 774.2HV. The microstructures of the quenching zone mainly consist of martensite and retained austenite, while tempered martensite is the dominant phase in partial quenching zone. The abrasion resistance of the surfacing metal is superior to the base metal based on the results of wear test. The wear rates of surfacing metal and base metal raise with the increase of load. The wear rates of base metal raise extremely when the load reach 210N. Both of two kinds of materials have the similar wear mechanism, namely, abrasive wear at low load, oxidative wear and adhesive wear at high load.

Chemical and Morphological Characterization of Magnetron Sputtered at Different Bias Voltages Cr-Al-C Coatings

Directory of Open Access Journals (Sweden)

Aleksei Obrosov

2017-02-01

Full Text Available MAX phases (M = transition metal, A = A-group element, and X = C/N are of special interest because they possess a unique combination of the advantages of both metals and ceramics. Most attention is attracted to the ternary carbide Cr2AlC because of its excellent high-temperature oxidation, as well as hot corrosion resistance. Despite lots of publications, up to now the influence of bias voltage on the chemical bonding structure, surface morphology, and mechanical properties of the film is still not well understood. In the current study, Cr-Al-C films were deposited on silicon wafers (100 and Inconel 718 super alloy by dc magnetron sputtering with different substrate bias voltages and investigated using Scanning Electron Microscopy (SEM, X-ray Photoelectron Spectroscopy (XPS, X-ray Diffraction (XRD, Atomic Force Microscopy (AFM, and nanoindentation. Transmission Electron Microscopy (TEM was used to analyze the correlation between the growth of the films and the coating microstructure. The XPS results confirm the presence of Cr2AlC MAX phase due to a negative shift of 0.6–0.9 eV of the Al2p to pure aluminum carbide peak. The XRD results reveal the presence of Cr2AlC MAX Phase and carbide phases, as well as intermetallic AlCr2. The film thickness decreases from 8.95 to 6.98 µm with increasing bias voltage. The coatings deposited at 90 V exhibit the lowest roughness (33 nm and granular size (76 nm combined with the highest hardness (15.9 GPa. The ratio of Al carbide to carbide-like carbon state changes from 0.12 to 0.22 and correlates with the mechanical properties of the coatings. TEM confirms the columnar structure, with a nanocrystalline substructure, of the films.

Effect of Si on DC arc plasma generation from Al-Cr and Al-Cr-Si cathodes used in oxygen

Science.gov (United States)

Zhirkov, I.; Landälv, L.; Göthelid, E.; Ahlgren, M.; Eklund, P.; Rosen, J.

2017-02-01

Al2O3 alloyed with Cr is an important material for the tooling industry. It can be synthesized from an arc discharge using Al-Cr cathodes in an oxygen atmosphere. Due to formation of Al-rich oxide islands on the cathode surface, the arc process stability is highly sensitive to oxygen pressure. For improved stability, the use of Al0.70Cr0.25Si0.05 cathodes has previously been suggested, where Si may reduce island formation. Here, we have investigated the effect of Si by comparing plasma generation and thin film deposition from Al0.7Cr0.3 and Al0.7Cr0.25Si0.05 cathodes. Plasma ion composition, ion energies, ion charge states, neutral species, droplet formation, and film composition have been characterized at different O2 flow rates for arc currents of 60 and 90 A. Si and related compounds are detected in plasma ions and in plasma neutrals. Scanning electron microscopy and energy dispersive X-ray analysis show that the cathode composition and the film composition are the same, with Si present in droplets as well. The effect of Si on the process stability, ion energies, and ion charge states is found to be negligible compared to that of the arc current. The latter is identified as the most relevant parameter for tuning the properties of the reactive discharge. The present work increases the fundamental understanding of plasma generation in a reactive atmosphere, and provides input for the choice of cathode composition and process parameters in reactive DC arc synthesis.

Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

International Nuclear Information System (INIS)

Wolf, W.; Bolfarini, C.; Kiminami, C.S.; Botta, W.J.

2016-01-01

The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al 71 Co 13 Fe 8 Cr 8 , Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al 71 Co 13 Fe 8 Cr 8 alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al 71 Co 13 Fe 8 Cr 8 . The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al 5 Co 2 and Al 13 Co 4 and are quasicrystalline approximants. Although the Al 5 Co 2 phase has already been reported in the Al 71 Co 13 Fe 8 Cr 8 alloy, the presence of the monoclinic Al 13 Co 4 is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al 13 Co 4 phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al 71 Co 13 Fe 8 Cr 8 alloy, the compositions Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were chosen to be within the region of formation of the quaternary extension of the Al 13 Co 4 phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system, around the compositions studied, is composed of quaternary extensions of Al-Co intermetallic phases, which present solubility of Fe and Cr at Co atomic sites. - Highlights: •The Al rich region of the AlCoFeCr

Oxide Morphology of a FeCrAl Alloy, Kanthal APMT, Following Extended Aging in Air at 300 °C to 600 °C

Science.gov (United States)

Li, Nan; Parker, Stephen S.; Wood, Elizabeth S.; Nelson, Andrew T.

2018-05-01

Iron-chromium-aluminum (FeCrAl) alloys are of interest to the nuclear materials community due to their resistance to high-temperature steam oxidation under accident conditions. The present work investigates oxide formation at temperatures relevant to light water reactor cladding operation following extended aging to assess growth kinetics, chemical composition, and microstructure of oxide formation on a commercial FeCrAl alloy, Fe-21 wt pct Cr-5 wt pct Al-3 wt pct Mo (Kanthal APMT). Aging treatments were performed for 100 to 1000 hours in stagnant air at 300 °C, 400 °C, 500 °C, and 600 °C, respectively. Oxide growth behavior under the investigated conditions follows a logarithmic time dependence. When the oxidization temperature is 400 °C or below, the oxide is amorphous. At 500 °C, isolated crystalline regions start to appear during short period aging time and expand with extended exposures. Crystalline α-Al2O3 oxide film develops at 600 °C and the correlated logarithmic rate constant decreases significantly, indicating enhanced oxidation resistance of the formed oxide film. In addition, Mo segregation at grain boundaries has been observed when the aging temperature exceeds 500 °C. The results of this study can be viewed as an upper bounding result for potential oxide coarsening during reactor operation.

Comparative study of cytotoxicity of direct metal laser sintered and cast Co-Cr-Mo dental alloy

Directory of Open Access Journals (Sweden)

T. Puskar

2015-07-01

Full Text Available The presented work investigated the cytotoxicity of direct metal laser sintered (DMLS and cast Co-Cr-Mo (CCM dental alloy. In vitro tests were done on human fibroblast cell line MRC-5. There was no statistically significant difference in the cytotoxic effects of DMLS and CCM alloy specimens. The results of this investigation show good potential of DMLS Co-Cr-Mo alloy for application in dentistry.

Evidence for the presence of U-Mo-Al ternary compounds in the U-Mo/Al interaction layer grown by thermal annealing: a coupled micro X-ray diffraction and micro X-ray absorption spectroscopy study

International Nuclear Information System (INIS)

Palancher, H.; Martin, P.; Nassif, V.

2007-01-01

The systematic presence of the ternary phases U 6 Mo 4 Al 43 and UMo 2 Al 20 is reported in a U-Mo/Al interaction layer grown by thermal annealing. This work shows, therefore, the low Mo solubility in UAl 3 and UAl 4 binary phases; it contradicts the hypothesis of the formation of (U,Mo)Al 3 and (U,Mo)Al 4 solid solutions often admitted in the literature. Using μ-XAS (micro X-ray absorption spectroscopy) at the Mo K edge and μ-XRD (micro X-ray diffraction), the heterogeneity of the interaction layer obtained on a γ-U 0.85 Mo 0.15 /Al diffusion couple has been precisely investigated. The UMo 2 Al 20 phase has been identified at the closest location from the Al side. Moreover, μ-XRD mapping performed on an annealed fuel plate enabled the characterization of the four phases resulting from the γ-U 0.85 Mo 0.15 /Al and (U 2 Mo+α-U)/Al interactions. A strong correlation between the concentrations of UAl 4 and UMo 2 Al 20 and those of UAl 3 and U 6 Mo 4 Al 43 has been shown. (orig.)

Interaction of Al with O{sub 2} exposed Mo{sub 2}BC

Energy Technology Data Exchange (ETDEWEB)

Bolvardi, Hamid; Music, Denis, E-mail: music@mch.rwth-aachen.de; Schneider, Jochen M.

2015-03-30

Highlights: • Al adheres to many surfaces. • Solid–solid interactions challenging for real (oxidized) surfaces. • Dissociative O{sub 2} adsorption on Mo{sub 2}BC(0 4 0). • Al nonamer is disrupted on oxidized Mo{sub 2}BC(0 4 0). • Adhesion of a residual Al on the native oxide. - Abstract: A Mo{sub 2}BC(0 4 0) surface was exposed to O{sub 2}. The gas interaction was investigated using ab initio molecular dynamics and X-ray photoelectron spectroscopy (XPS) of air exposed surfaces. The calculations suggest that the most dominating physical mechanism is dissociative O{sub 2} adsorption whereby Mo−O, O−Mo−O and Mo{sub 2}−C−O bond formation is observed. To validate these results, Mo{sub 2}BC thin films were synthesized utilizing high power pulsed magnetron sputtering and air exposed surfaces were probed by XPS. MoO{sub 2} and MoO{sub 3} bond formation is observed and is consistent with here obtained ab initio data. Additionally, the interfacial interactions of O{sub 2} exposed Mo{sub 2}BC(0 4 0) surface with an Al nonamer is studied with ab initio molecular dynamics to describe on the atomic scale the interaction between this surface and Al to mimic the interface present during cold forming processes of Al based alloys. The Al nonamer was disrupted and Al forms chemical bonds with oxygen contained in the O{sub 2} exposed Mo{sub 2}BC(0 4 0) surface. Based on the comparison of here calculated adsorption energy with literature data, Al−Al bonds are shown to be significantly weaker than the Al−O bonds formed across the interface. Hence, Al−Al bond rupture is expected for a mechanically loaded interface. Therefore the adhesion of a residual Al on the native oxide layer is predicted. This is consistent with experimental observations. The data presented here may also be relevant for other oxygen containing surfaces in a contact with Al or Al based alloys for example during forming operations.

Connection between twinning and brittle fracture in Fe-Cr-Co-Mo crystals

International Nuclear Information System (INIS)

Kirillov, V.A.; Chumlyakov, Yu.I.; Korotaev, A.D.; Aparova, L.A.

1989-01-01

Plasticity dependence on crystal orientation, on deformation temperature and structure state of alloy is investigated in Fe-28 % Cr-10 % Co-2 % Mo (at. %) monocrystals. Isostructure decomposition results in increase of critical shearing stresses τ cr , in change of deformation mechanism from slipping into twinning and abrupt reduction of plasticity. Brittleness - ductility transition is detected in high-stable structure states τ cr >280 MPa. Explanation of plasticity abrupt reduction of high-stable crystals using estimation of change of deformation mechanism and of deforming stress high level is given

PENGARUH TEMPERATUR DAN IRADIASI TERHADAP INTERDIFUSI PARTIKEL BAHAN BAKAR JENIS U−7Mo/Al

Directory of Open Access Journals (Sweden)

Maman Kartaman Ajiriyanto

2016-06-01

Full Text Available ABSTRAK PENGARUH TEMPERATUR DAN IRADIASI TERHADAP INTERDIFUSI PARTIKEL BAHAN BAKAR JENIS U−7Mo/Al. Paduan U−7Mo/Al memiliki potensi besar sebagai bahan bakar reaktor riset, tetapi bahan bakar ini memiliki beberapa kekurangan antara lain dapat membentuk interaction layer pada antarmuka pada saat proses fabrikasi maupun iradiasi di reaktor melalui mekaniame difusi. Penelitian ini dilakukan untuk mengetahui terjadinya interaction layer yang disebabkan oleh interdifusi atau diffusion couple paduan U−7Mo dengan pelat AlMg2 yang dipanaskan pada temperatur 500 °C dan 550 °C selama 24 jam dalam tungku arc furnace dan tungku DTA pada temperatur 30 °C hingga 1400 °C. Hasil pengamatan mikrostruktur menggunakan Scanning Electron Microscope (SEM pada sampel diffusion couple hasil pemanasan pada temperatur 500 °C belum terlihat adanya interaction layeratau pembentukan fasa baru antara partikel U−Mo dan matriks Al. Sementara itu, pemanasan pada temperatur 550 °C telah terjadi interdifusi paduan U−7Mo dengan pelat AlMg2 menghasilkan senyawa (U,MoAlx pada antarmuka atau interface. Hal ini didukung oleh hasil analisis DTA menunjukkan bahwa paduan U−7Mo/Al pada 500 °C mempunyai kompatibilitas panas yang baik, tetapi diatas temperatur 550 °C telah terjadi perubahan fasa a + d menjadi a + g. Pemanasan hingga 679,14 °C terjadi fasa metastabil U(Al,Mox dan selanjutnya mengalami proses interdifusi dengan leburan uranium membentuk interaction layer berupa aglomerat senyawa UAlx (UAl4, UAl3 danUAl2. Aglomerat yang terbentuk dari proses pemanasan secara diffusion couple maupun dalam tungku DTA dibandingkan dengan aglomerat yang terbentuk akibat proses iradiasi. Bahan bakar paduan U−7Mo/Al yang diradiasi dengan burn up 58% mengalami interdifusi antara U−7Mo dengan matriks Al menghasilkan fasa metastabil U(Al,Mox yang berubah menjadi layer (U,MoAl7, presipitat UMo2Al20, (UMoAl3−Al dan membentuk boundary atau aglomerat UAlx (UAl4, UAl3 danUAl2

Influence of graphite-alloy interactions on corrosion of Ni-Mo-Cr alloy in molten fluorides

Science.gov (United States)

Ai, Hua; Hou, Juan; Ye, Xiang-Xi; Zeng, Chao Liu; Sun, Hua; Li, Xiaoyun; Yu, Guojun; Zhou, Xingtai; Wang, Jian-Qiang

2018-05-01

In this study, the effects of graphite-alloy interaction on corrosion of Ni-Mo-Cr alloy in molten FLiNaK salt were investigated. The corrosion tests of Ni-Mo-Cr alloys were conducted in graphite crucibles, to examine the differences of test specimens in conditions of electric contact and isolated with graphite, respectively. The corrosion attack is severer with more weight loss and deeper Cr depletion layer in samples electric contact with graphite than those isolated with graphite. The occurrence of galvanic corrosion between alloy specimens and graphite container was confirmed by electrochemical measurement. The corrosion is controlled by nonelectric transfer in isolated test while electrochemical reaction accelerated corrosion in electric contact test.

Passive behaviour of alloy corrosion-resistant steel Cr10Mo1 in simulating concrete pore solutions with different pH

International Nuclear Information System (INIS)

Ai, Zhiyong; Jiang, Jinyang; Sun, Wei; Song, Dan; Ma, Han; Zhang, Jianchun; Wang, Danqian

2016-01-01

Highlights: • A new alloy corrosion-resistant steel Cr10Mo1 is developed for reinforcing rebar of concrete in severe environments. • The effects of pH on the passive behaviour of Cr10Mo1 steel compared with plain carbon steel were studied systematically by electrochemical techniques and surface analysis. • The mechanism for self-reinforcing passivity against carbonation of the corrosion-resistant steel is revealed. - Abstract: The passive behaviour of new alloy corrosion-resistant steel Cr10Mo1 and plain carbon steel (as a comparison) in simulating concrete pore solutions of different pH (ranging from 13.5 to 9.0) under open circuit potential conditions, was evaluated by various electrochemical techniques: potentiodynamic polarization, capacitance measurements and electrochemical impedance spectroscopy. The chemical composition and structure of passive films were investigated by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The electrochemical responses of passive films show that Cr10Mo1 steel has an increasing passivity with pH decreasing while carbon steel dose conversely, revealing carbonation does no negative effect on passivation of the corrosion-resistant steel. SIMS reveals that the passive film on the corrosion-resistant steel presents a bilayer structure: an outer layer mainly consisting of Fe oxides and hydroxides, and an inner layer enriched in Cr species, while only a Fe-concentrated layer for carbon steel. According to the XPS analysis results, as the pH decreases, more stable and protective Cr oxides are enriched in the film on Cr10Mo1 steel while Fe oxides gradually decompose. Higher content of Cr oxides in the film layer provides Cr10Mo1 corrosion-resistant steel more excellent passivity at lower pH.

Passive behaviour of alloy corrosion-resistant steel Cr10Mo1 in simulating concrete pore solutions with different pH

Energy Technology Data Exchange (ETDEWEB)

Ai, Zhiyong, E-mail: 230139452@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Jiang, Jinyang, E-mail: jiangjinyang16@163.com [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Sun, Wei, E-mail: sunwei@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Song, Dan, E-mail: songdancharls@hhu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); College of Mechanics and Materials, Hohai University, Nanjing 210098, Jiangsu (China); Ma, Han, E-mail: mahan-iris@shasteel.cn [Research Institute of Jiangsu Shasteel Iron and Steel, Zhangjiagang 215625, Jiangsu (China); Zhang, Jianchun, E-mail: Zhangjc-iris@shasteel.cn [Research Institute of Jiangsu Shasteel Iron and Steel, Zhangjiagang 215625, Jiangsu (China); Wang, Danqian, E-mail: wonderbaba@126.com [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China)

2016-12-15

Highlights: • A new alloy corrosion-resistant steel Cr10Mo1 is developed for reinforcing rebar of concrete in severe environments. • The effects of pH on the passive behaviour of Cr10Mo1 steel compared with plain carbon steel were studied systematically by electrochemical techniques and surface analysis. • The mechanism for self-reinforcing passivity against carbonation of the corrosion-resistant steel is revealed. - Abstract: The passive behaviour of new alloy corrosion-resistant steel Cr10Mo1 and plain carbon steel (as a comparison) in simulating concrete pore solutions of different pH (ranging from 13.5 to 9.0) under open circuit potential conditions, was evaluated by various electrochemical techniques: potentiodynamic polarization, capacitance measurements and electrochemical impedance spectroscopy. The chemical composition and structure of passive films were investigated by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The electrochemical responses of passive films show that Cr10Mo1 steel has an increasing passivity with pH decreasing while carbon steel dose conversely, revealing carbonation does no negative effect on passivation of the corrosion-resistant steel. SIMS reveals that the passive film on the corrosion-resistant steel presents a bilayer structure: an outer layer mainly consisting of Fe oxides and hydroxides, and an inner layer enriched in Cr species, while only a Fe-concentrated layer for carbon steel. According to the XPS analysis results, as the pH decreases, more stable and protective Cr oxides are enriched in the film on Cr10Mo1 steel while Fe oxides gradually decompose. Higher content of Cr oxides in the film layer provides Cr10Mo1 corrosion-resistant steel more excellent passivity at lower pH.

Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

Energy Technology Data Exchange (ETDEWEB)

Wolf, W., E-mail: witorw@gmail.com [Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Bolfarini, C., E-mail: cbolfa@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Kiminami, C.S., E-mail: kiminami@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Botta, W.J., E-mail: wjbotta@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil)

2016-12-15

The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8}, Al{sub 77}Co{sub 11}Fe{sub 6}Cr{sub 6} and Al{sub 76}Co{sub 19}Fe{sub 4}Cr{sub 1} were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8}. The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al{sub 5}Co{sub 2} and Al{sub 13}Co{sub 4} and are quasicrystalline approximants. Although the Al{sub 5}Co{sub 2} phase has already been reported in the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy, the presence of the monoclinic Al{sub 13}Co{sub 4} is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al{sub 13}Co{sub 4} phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy, the compositions Al{sub 77}Co{sub 11}Fe{sub 6}Cr{sub 6} and Al{sub 76}Co{sub 19}Fe{sub 4}Cr{sub 1} were chosen to be within the region of formation of the quaternary extension of the Al{sub 13}Co{sub 4} phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system

Creep behaviour of the alloys NiCr22Co12Mo and 10CrMo9 10 under static and cyclic load conditions

International Nuclear Information System (INIS)

Wolf, H.

1990-01-01

The creep behaviour of NiCr20Co12Mo is investigated under static strain and at 800deg C, with stresses applied ranging from 105 MPa to 370 MPa. The ferritic steel 10CrMo 9 10 is tested for its creep behaviour under static strain and at the temperatures of 600deg C and 550deg C, with stresses applied between 154 MPa and 326 MPa (at 600deg C), or between 250 MPa and 458 MPa (at 550deg C). The experiments are made to determine the effects of changes in strain on the materials' deformation behaviour, placing emphasis on transient creep and elastic or anelastic response. The mean internal stress is determined from changes in strain. Cyclic creep is analysed as a behaviour directly responding to the pattern of change in strain. Effects of certain strain changes not clarified so far are analysed. The cyclic strain experiments are analysed according to the velocity factor concept. The usual models of creep deformation (theta projection concept) are compared with the model of effective strain, which is based on the fundamental equation of plastic deformation by dislocation motion (Orowan equation). (MM) [de

Simultaneous extractive-photometric determination of Zr and Mo in multicomponent alloys

International Nuclear Information System (INIS)

Kutyrev, I.M.; Chernysheva, G.M.; Chebotnikovz, Yu.A.; Basargin, N.N.

2000-01-01

Nonaqueous buffer solutions of different acidity are developed for simultaneous photometric determination of Zr and Mo in the extract. Trioctylamine extraction system in toluene - sulfuric acid - molybdenum, zirconium provides selective isolation of the aforementioned elements in one extraction and makes it possible to remove the interfering effect of Fe(2,3), Co(2), Ni(2), Cu(2), Al(3), Ti(4), Cr(3), Mn(2), V(4), Si(4). The reliability of the method is confirmed by determination of the elements in SS123v standard sample [ru

Ferromagnetism in Cr-doped passivated AlN nanowires

KAUST Repository

Kanoun, Mohammed; Goumri-Said, Souraya; Schwingenschlö gl, Udo

2014-01-01

We apply first principles calculations to predict the effect of Cr doping on the electronic and magnetic properties of passivated AlN nanowires. We compare the energetics of the possible dopant sites and demonstrate the favorable configuration ferromagnetic ordering. The charge density of the pristine passivated AlN nanowires is used to elucidate the bonding character. Spin density maps demonstrate an induced spin polarization for N atoms next to dopant atoms, though most of the magnetism is carried by the Cr atoms. Cr-doped AlN nanowires turn out to be interesting for spintronic devices. © 2014 the Partner Organisations.

Effects of sodium environment on the mechanical properties of Fe-2 1/4Cr-1Mo steel

International Nuclear Information System (INIS)