WorldWideScience

Sample records for alloy steel

  1. Alloy dissolution in argon stirred steel

    Science.gov (United States)

    Webber, Darryl Scott

    Alloying is required for the production of all steel products from small castings to large beams. Addition of large quantities of bulk alloys can result in alloy segregation and inconsistent alloy recovery. The objective of this research was to better understand alloy dissolution in liquid steel especially as it relates to Missouri S&Ts' patented continuous steelmaking process. A 45-kilogram capacity ladle with a single porous plug was used to evaluate the effect of four experimental factors on alloy dissolution: alloy species, alloy size or form, argon flow rate, and furnace tap temperature. Four alloys were tested experimentally including Class I low carbon ferromanganese, nickel and tin (as a surrogate for low melting alloys) and Class II ferroniobium. The alloys ranged in size and form from granular to 30 mm diameter lumps. Experimental results were evaluated using a theoretically based numerical model for the steel shell period, alloy mixing (Class I) and alloy dissolution (Class II). A CFD model of the experimental ladle was used to understand steel motion in the ladle and to provide steel velocity magnitudes for the numerical steel shell model. Experiments and modeling confirmed that smaller sized alloys have shorter steel shell periods and homogenize faster than larger particles. Increasing the argon flow rate shortened mixing times and reduced the delay between alloy addition and the first appearance of alloy in the melt. In addition, for every five degree increase in steel bath temperature the steel shell period was shortened by approximately four percent. Class II ferroniobium alloy dissolution was an order of magnitude slower than Class I alloy mixing.

  2. Plating on stainless steel alloys

    International Nuclear Information System (INIS)

    Dini, J.W.; Johnson, H.R.

    1981-01-01

    Quantitative adhesion data are presented for a variety of electroplated stainless steel type alloys. Results show that excellent adhesion can be obtained by using a Wood's nickel strike or a sulfamate nickel strike prior to final plating. Specimens plated after Wood's nickel striking failed in the deposit rather than at the interface between the substrate and the coating. Flyer plate quantitative tests showed that use of anodic treatment in sulfuric acid prior to Wood's nickel striking even further improved adhesion. In contrast activation of stainless steels by immersion or cathodic treatment in hydrochloric acid resulted in very reduced bond strengths with failure always occurring at the interface between the coating and substrate

  3. 46 CFR 59.20-1 - Carbon-steel or alloy-steel castings.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Carbon-steel or alloy-steel castings. 59.20-1 Section 59... BOILERS, PRESSURE VESSELS AND APPURTENANCES Welding Repairs to Castings § 59.20-1 Carbon-steel or alloy-steel castings. Defects in carbon-steel or alloy-steel castings may be repaired by welding. The repairs...

  4. Friction Stir Welding of Steel Alloys

    Science.gov (United States)

    Ding, R. Jeffrey; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    The friction stir welding process has been developed primarily for the welding of aluminum alloys. Other higher melting allows such, as steels are much more difficult to join. Special attention must be given to pin tool material selection and welding techniques. This paper addresses the joining of steels and other high melting point materials using the friction stir welding process. Pin tool material and welding parameters will be presented. Mechanical properties of weldments will also be presented. Significance: There are many applications for the friction stir welding process other than low melting aluminum alloys. The FSW process can be expanded for use with high melting alloys in the pressure vessel, railroad and ship building industries.

  5. Boron Steel: An Alternative for Costlier Nickel and Molybdenum Alloyed Steel for Transmission Gears

    Directory of Open Access Journals (Sweden)

    A. Verma

    2010-06-01

    Full Text Available Case Carburized (CC low carbon steels containing Ni, Cr and Mo alloying elements are widely used for transmission gears in automobile, as it possesses desired mechanical properties. In order to cut cost and save scarce materials like Ni and Mo for strategic applications, steel alloyed with Boron has been developed, which gives properties comparable to Ni-Cr-Mo alloyed steel. In the process of steel development, care was taken to ensure precipitation of boron which results in precipitation hardening. The characterization of the developed boron steel had exhibited properties comparable to Ni-Cr-Mo alloyed steel and superior to conventional boron steel.

  6. Athermal kinetics in low alloy steels

    International Nuclear Information System (INIS)

    Leiva, Jorge A Vega; Valencia Morales, Eduardo; Villar Cociña, Ernesto; Hernández Ruiz, Jesús; Donis, Carlos

    2008-01-01

    Athermic analyses for the kinetic study of the reactions in the solid state are preferred because they consume much less experimental work time than the isothermal tests, and lead to more accurate calculations of the energies of activation of reactions that have occurred. In the present work are required conditions where you can apply the equation of speed of an athermal reaction in a low alloy in solid steel. From records of steel (AISI 1050) dilatometric triples were calculated kinetics (E, Ko, n) that characterize the reactions that occurred during the tempering of samples using different methods of iso conversion, one of which is a new modification of the method of Friedman. Also, has shown that during the formation of carbide Epsilon in the first stage of the tempering has occurred a saturation of sites, which validates the use of some methods. Finally, the orders of the reactions occurred during tempering of steel studied treatment are calculated.

  7. Progress in the development of niobium alloyed high speed steel

    International Nuclear Information System (INIS)

    Guimaraes, J.R.C.

    1987-01-01

    The development of economy-grades of niobium alloyed high speed steel is described. Both the metallurgical concepts behind the steel design and the results of performance tests are presented. (Author) [pt

  8. Crack stability analysis of low alloy steel primary coolant pipe

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, T.; Kameyama, M. [Kansai Electric Power Company, Osaka (Japan); Urabe, Y. [Mitsubishi Heavy Industries, Ltd., Takasago (Japan)] [and others

    1997-04-01

    At present, cast duplex stainless steel has been used for the primary coolant piping of PWRs in Japan and joints of dissimilar material have been applied for welding to reactor vessels and steam generators. For the primary coolant piping of the next APWR plants, application of low alloy steel that results in designing main loops with the same material is being studied. It means that there is no need to weld low alloy steel with stainless steel and that makes it possible to reduce the welding length. Attenuation of Ultra Sonic Wave Intensity is lower for low alloy steel than for stainless steel and they have advantageous inspection characteristics. In addition to that, the thermal expansion rate is smaller for low alloy steel than for stainless steel. In consideration of the above features of low alloy steel, the overall reliability of primary coolant piping is expected to be improved. Therefore, for the evaluation of crack stability of low alloy steel piping to be applied for primary loops, elastic-plastic future mechanics analysis was performed by means of a three-dimensioned FEM. The evaluation results for the low alloy steel pipings show that cracks will not grow into unstable fractures under maximum design load conditions, even when such a circumferential crack is assumed to be 6 times the size of the wall thickness.

  9. Stress corrosion of low alloy steel forgings

    International Nuclear Information System (INIS)

    Thornton, D.V.; Mould, P.B.; Patrick, E.C.

    1976-01-01

    The catastrophic failure of a steam turbine rotor disc at Hinkley Point 'A' Power station was shown to have been caused by the growth of a stress corrosion crack to critical dimensions. This failure has promoted great interest in the stress corrosion susceptibility of medium strength low alloy steel forgings in steam environments. Consequently, initiation and growth of stress corrosion cracks of typical disc steels have been investigated in steam and also in water at 95 0 C. Cracking has been shown to occur, predominantly in an intergranular manner, with growth rates of between 10 -9 and 10 -7 mm sec. -1 . It is observed that corrosion pitting and oxide penetration prior to the establishment of a stress corrosion crack in the plain samples. (author)

  10. Stainless steel-zirconium alloy waste forms

    International Nuclear Information System (INIS)

    McDeavitt, S.M.; Abraham, D.P.; Keiser, D.D. Jr.; Park, J.Y.

    1996-01-01

    An electrometallurgical treatment process has been developed by Argonne National Laboratory to convert various types of spent nuclear fuels into stable storage forms and waste forms for repository disposal. The first application of this process will be to treat spent fuel alloys from the Experimental Breeder Reactor-II. Three distinct product streams emanate from the electrorefining process: (1) refined uranium; (2) fission products and actinides extracted from the electrolyte salt that are processed into a mineral waste form; and (3) metallic wastes left behind at the completion of the electrorefining step. The third product stream (i.e., the metal waste stream) is the subject of this paper. The metal waste stream contains components of the chopped spent fuel that are unaffected by the electrorefining process because of their electrochemically ''noble'' nature; this includes the cladding hulls, noble metal fission products (NMFP), and, in specific cases, zirconium from metal fuel alloys. The selected method for the consolidation and stabilization of the metal waste stream is melting and casting into a uniform, corrosion-resistant alloy. The waste form casting process will be carried out in a controlled-atmosphere furnace at high temperatures with a molten salt flux. Spent fuels with both stainless steel and Zircaloy cladding are being evaluated for treatment; thus, stainless steel-rich and Zircaloy-rich waste forms are being developed. Although the primary disposition option for the actinides is the mineral waste form, the concept of incorporating the TRU-bearing product into the metal waste form has enough potential to warrant investigation

  11. Structure and radiation induced swelling of steels and alloys

    International Nuclear Information System (INIS)

    Parshin, A.M.

    1983-01-01

    Regularities of vacancy void formation and radiation induced swelling of austenitic chromium-nickel steels and alloyse ferritic steels as well as titanium α-alloys under radiation by light and heavy ions and neutrons are considered. Possible methods for preparation of alloys with increased resistance to radiation swelling are described. Accounting for investigations into ferritic steels and α-alloys of titanium the basic way of weakening vacancy smelling is development of continuous homogeneous decomposition of solid solution using alloying with vividly expressed incubation period at a certain volumetric dilatation as well as decompositions of the type of ordering, K-state, lamination of solid solutions, etc. Additional alloying of solid solutions is also shown to be necessary for increasing recrystallization temperature of cold-deformed steel

  12. An Investigation of the Charpy V Notch Characteristics of Leaded Carbon and Alloy Steels.

    Science.gov (United States)

    Steel , *Lead alloys, * Charpy impact tests , Low alloy steels , Carbon steels , Billets(Materials), Elongation, Orientation(Direction), Low temperature...Heat treatment, Tensile properties, Hardness, Impact strength, Transition temperature, Microstructure, Fracture(Mechanics), Microradiography

  13. Low alloy steel versus ADI – differences and similarities

    Directory of Open Access Journals (Sweden)

    A. Krzyńska

    2009-01-01

    Full Text Available The results of comparison between the microstructure of selected bainitic low alloy steel and austempered ductile iron ADI are presented. The aim of the comparison was to find out differences and similarities existing in these iron carbon commercial alloys. In this paper our own results on ADI structure and literature data were used. It follows from discussion presented here that both microstructure and properties of ADI are very close that which are observed in low alloy carbon steel. Moreover, we suggest that there is no so doubt to treat ADI mechanical properties as steel containing nodular inclusions of graphite.

  14. Diode Laser Surface Alloying of Armor Steel with Tungsten Carbide

    OpenAIRE

    Janicki D.; Górka J.; Kwaśny W.; Gołombek K.; Kondracki M.; Żuk M.

    2017-01-01

    Metal matrix composite (MMC) surface layers reinforced by WC were fabricated on armor steel ARMOX 500T plates via a laser surface alloying process. The microstructure of the layers was assessed by scanning electron microscopy and X-ray diffraction.

  15. Influence of alloying elements and density on aqueous corrosion behaviour of some sintered low alloy steels

    International Nuclear Information System (INIS)

    Kandavel, T.K.; Chandramouli, R.; Karthikeyan, P.

    2012-01-01

    Highlights: ► Corrosion of low alloy P/M steels under HCl acid pickling environment has been studied. ► Influence of density, strain and alloying elements on the rate of corrosion of the steels has been investigated. ► Residual porosity has significant effect on acid corrosion. ► Addition of the alloying elements Cu, Mo and Ti reduces the corrosion rate significantly. ► Carbide forming elements Mo and Ti improve further the resistance of the steels to aqueous corrosion. -- Abstract: Low alloy steels produced through powder metallurgy route of sintering followed by forging are promising candidate materials for high strength small components. Porosity in such steels poses a real challenge during acid pickling treatment, which is one of the processing steps during manufacturing. The present research work attempts to investigate the mechanism underlying the acid corrosion behaviour of some sintered low alloy steels under induced acid pickling conditions. Sintered-forged low alloy steel samples containing molybdenum (Mo), copper (Cu) and titanium (Ti) were subjected to aqueous corrosion attack by immersing the samples in 18% HCl (Hydrochloric acid) solution for 25 h. Sample weight loss and Fe (Iron) loss were estimated for the corroded samples. The morphology of the corroded surfaces was studied through metallography and scanning electron microscopy. Higher porosity alloys underwent enhanced corrosion rates. Both corrosion rate and iron loss are found to decrease linearly with reduction in porosity in all cases of the alloys. The alloying elements Mo, Ti and Cu, when added in combination, have played a complementary role in the reduction of corrosion rate by almost one order of magnitude compared to unalloyed steel. Presence of carbides of the carbide forming elements Mo and Ti played a positive role on the corrosion behaviour of the low alloy steels.

  16. 48 CFR 252.225-7030 - Restriction on Acquisition of Carbon, Alloy, and Armor Steel Plate.

    Science.gov (United States)

    2010-10-01

    ... of Carbon, Alloy, and Armor Steel Plate. 252.225-7030 Section 252.225-7030 Federal Acquisition... Acquisition of Carbon, Alloy, and Armor Steel Plate. As prescribed in 225.7011-3, use the following clause: Restriction on Acquisition of Carbon, Alloy, and Armor Steel Plate (DEC 2006) (a) Carbon, alloy, and armor...

  17. Abrasive Wear of Alloyed Cast Steels Applied for Heavy Machinery

    Directory of Open Access Journals (Sweden)

    Studnicki A.

    2015-03-01

    Full Text Available In the paper the results and analysis of abrasive wear studies were shown for two grades of cast steels: low-alloyed cast steel applied for heavy machinery parts such as housing, covers etc. and chromium cast steels applied for kinetic nodes of pin-sleeve type. Studies were performed using the modified in Department of Foundry pin-on-disc method.

  18. Metal dusting of low alloy steels

    Energy Technology Data Exchange (ETDEWEB)

    Grabke, H.J. (Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)); Bracho-Troconis, C.B. (Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)); Mueller-Lorenz, E.M. (Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany))

    1994-04-01

    The metal dusting of two low alloy steels was investigated at 475 C in flowing CO-H[sub 2]-H[sub 2]O mixtures at atmospheric pressure with a[sub C] > 1. The reaction sequence comprises: (1) oversaturation with C, formation of cementite and its decomposition to metal particles and carbon, and (2) additional carbon deposition on the metal particles from the atmosphere. The metal wastage rate r[sub 1] was determined by analysis of the corrosion product after exposures, this rate is constant with time and virtually independent of the environment. The carbon deposition from the atmosphere was determined by thermogravimetry, its rate r[sub 2] increases linearly with time, which can be explained by the catalytic action of the metal particles - periodic changes are superposed. The rate of carbon deposition r[sub 2] is proportional to the carbon activity in the atmosphere. The metal dusting could not be suppressed by increasing the oxygen activity or preoxidation, even if magnetite should be stable. Addition of H[sub 2]S, however, effectively suppresses the attack. (orig.)

  19. The structure of the alphinizing coat on alloy steels

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2008-12-01

    Full Text Available In this paper results of the structure of the coat alphinizing in AlSi5 silumin on alloy steels: acid-proof 1H18N9T (X6CrNiTi18-10 and high speed SW18 (HS18-0-1 were presented. The temperature of the alphinizing bath was amounts to750±5°C, and immersion time of the element τ = 180s. It was shown, that there is the different “g” coat thickness on testing steels. On the 1H18N9T steel it amounts to g = 52μm, and on the SW18 steel – g = 203μm. Regardless of a grade of testing alloy steels the coat consist of three layers with diversified phasic structure. There is different chemical composition of coat layers on testing steels. The first layer from the base consist of AlFe phase containing alloy addictions of steels: Cr and Ni (1H18N9T and W, V and Cr (SW18. On this layer crystallize the second layer of intermetallic phases. It is the phase containing the main alloy addiction of steels: AlFeCr (1H18N9T and AlFeW (SW18. The last, outside layer consist of silumin containing AlFeNi intermetallic phases on the 1H18N9T steel and AlFeW on the SW18 steel. Regardless of the grade of testing steels there is Si element in all layers of the coat. There are morphological differences in tested layers. The second layer (AlFeW phase inside the coat on the SW18 steel consist of faced crystals growing into in outside silumin layer. On the 1H18N9T steel a boundary between transient and outside layer is more uniform. Free separations of intermetallic phases inside silumin layer on the 1H18N9T steel have lamellar and on the SW18 steel – faced form.

  20. Influence of alloying elements on the marine corrosion of low alloy steels

    International Nuclear Information System (INIS)

    Dajoux, E.; Malard, S.; Lefevre, Y.; Kervadec, D.; Gil, O.

    2005-01-01

    The study of steel marine corrosion leads to the survey of the parameters having an influence on this phenomenon. These parameters may be dependent on the seawater environment or on steel characteristics. Thus it appears that an experimental procedure could be set up in order to simulate immersion conditions in natural seawater. The system allows fifteen different steels with compositions ranging from carbon steels to stainless steels to be tested during some 14 months in natural seawater with or without microbiological activity. Electrochemical and gravimetric measurements are performed on immersed steel samples. Microbiological analyses are carried out either on the metallic surface and on the liquid medium. Possible influences of alloying elements and bacteria are studied. After a two-month immersion, first results show an influence of the chromium content on the steel corrosion resistance and on marine bacteria behaviour. They also reveal that the bio-film formed onto the carbon steel and low alloy steels surfaces tends to slow down the generalized corrosion or to increase localized corrosion depending on the steel alloying elements content. (authors)

  1. Fatigue and fracture behavior of low alloy ferritic forged steels

    International Nuclear Information System (INIS)

    Chaudhry, V.; Sharma, A.K.; Muktibodh, U.C.; Borwankar, Neeraj; Singh, D.K.; Srinivasan, K.N.; Kulkarni, R.G.

    2016-01-01

    Low alloy ferritic steels are widely used in nuclear industry for the construction of pressure vessels. Pressure vessel forged low alloy steels 20MnMoNi55 (modified) have been developed indigenously. Experiments have been carried out to study the Low Cycle Fatigue (LCF) and fracture behavior of these forged steels. Fully reversed strain controlled LCF testing at room temperature and at 350 °C has been carried out at a constant strain rate, and for different axial strain amplitude levels. LCF material behavior has been studied from cyclic stress-strain responses and the strain-life relationships. Fracture behavior of the steel has been studied based on tests carried out for crack growth rate and fracture toughness (J-R curve). Further, responses of fatigue crack growth rate tests have been compared with the rate evaluated from fatigue precracking carried out for fracture toughness (J-R) tests. Fractography of the samples have been carried out to reveal dominant damage mechanisms in crack propagation and fracture. The fatigue and fracture properties of indigenously developed low alloy steel 20MnMoNi55 (modified) steels are comparable with similar class of steels. (author)

  2. Laves intermetallics in stainless steel-zirconium alloys

    International Nuclear Information System (INIS)

    Abraham, D.P.; McDeavitt, S.M.; Richardson, J.W. Jr.

    1997-01-01

    Laves intermetallics have a significant effect on properties of metal waste forms being developed at Argonne National Laboratory. These waste forms are stainless steel-zirconium alloys that will contain radioactive metal isotopes isolated from spent nuclear fuel by electrometallurgical treatment. The baseline waste form composition for stainless steel-clad fuels is stainless steel-15 wt.% zirconium (SS-15Zr). This article presents results of neutron diffraction measurements, heat-treatment studies and mechanical testing on SS-15Zr alloys. The Laves intermetallics in these alloys, labeled Zr(Fe,Cr,Ni) 2+x , have both C36 and C15 crystal structures. A fraction of these intermetallics transform into (Fe,Cr,Ni) 23 Zr 6 during high-temperature annealing; the authors have proposed a mechanism for this transformation. The SS-15Zr alloys show virtually no elongation in uniaxial tension, but exhibit good strength and ductility in compression tests. This article also presents neutron diffraction and microstructural data for a stainless steel-42 wt.% zirconium (SS-42Zr) alloy

  3. Local corrosion of high alloy steels under biodeposits

    International Nuclear Information System (INIS)

    Korovyakova, M.D.; Nikitin, V.M.; Speshneva, N.V.

    1999-01-01

    Impact of the bacteriozenosis different structural-functional state under biodeposits on corrosion resistance of the 12Kh18N10T and Kh18N10T high-alloy steels in the natural seawater is studied. It is shown that saturation of natural micro communities by separate aerobic and facultative-anaerobic bacterial monocultures increases corrosion resistance of these steels by their overgrow with biodeposits [ru

  4. Problems of the supply of raw materials for steel alloys

    International Nuclear Information System (INIS)

    Haferkamp, H.

    1975-01-01

    A survey is given on the supply of raw metals, of the alloy elements Mn, Cr, Ni, Mo, W, Co, V, which play an important part as 'steel-refining elements' in the steel-producing industry, and of the special metals Nb and Te. This information is followed by a comparison of the supply situation for crude oil and for the basic material iron are, an assessment on the future development of demand and production with an assumed shortage of raw materials, the solutions to the supply problems of the steel industry, and the national raw materials policy. (HK/AK) [de

  5. Kinetics of chemical interactions between zirconium alloys and stainless steels

    International Nuclear Information System (INIS)

    Frecska, J.; Maroti, L.; Matus, L.

    1995-01-01

    The chemical interaction kinetics of reactor core component zirconium alloys and stainless steels at high temperatures was examined. Interaction of as-received and preoxidized Zr1%Nb with X18H10T stainless steel used in WWER type nuclear reactors, and also that of Zircaloy-4 and AISI-316 stainless steel, for comparison, were investigated. The reaction rate measurements were supplemented with post-test metallographical examinations. Results are presented and evaluated, and compared with literature data. (author). 14 refs., 31 figs., 8 tabs

  6. Welding of Aluminum Alloys to Steels: An Overview

    Science.gov (United States)

    2013-08-01

    51] in which the bimetal wires can be roll welded Al/ Steel strips and the welding is a kind of tricky process to have similar metals joined together...Al 1060) and steel (1Cr18Ni9Ti) were joined together using the vacuum furnace and A-Si alloy as the strip layer. The interface of the joints showed...also greatly appreciated. References [1] A. Kelkar, R. Roth, J. Clark, Automobile bodies: can aluminum be an economical alternative to steel ? , JOM

  7. Low Mn alloy steel for cryogenic service

    Science.gov (United States)

    Morris, J.W. Jr.; Niikura, M.

    A ferritic cryogenic steel which has a relatively low (about 4 to 6%) manganese content and which has been made suitable for use at cryogenic temperatures by a thermal cycling treatment followed by a final tempering. The steel includes 4 to 6% manganese, 0.02 to 0.06% carbon, 0.1 to 0.4% molybdenum and 0 to 3% nickel.

  8. On the rational alloying of structural chromium-nickel steels

    International Nuclear Information System (INIS)

    Astaf'ev, A.A.

    1982-01-01

    A study was made on the influence of chromium nickel, phosphorus on the critical brittleness temperature of Cr-Ni-Mo-V structural steels. It is shown that the critical brittleness temperature of these steels increases at chromium content more over than 2% and nickel content more than 2% in the result of carbide transformations during tempering. Increase of nickel content in Cr-Ni-Mo-V-steels strengthens the tendency to embrittlement during slow cooling, from tempering temperature owing to development of process of phosphorus grain-boundary segregation. Two mentioned mechanisms of embrittlement determine principles of rational steel alloying. The extreme dependence of the critical brittleness temperature on chromium and nickel content, which enables to choose the optimum composition of Cr-Ni-Mo-V-steels, was established

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    The present contribution showcases the possibility for developing new surface hardenable stainless steels containing strong nitride/carbide forming elements (SNCFE). Nitriding of the commercial alloys, austenitic A286, and ferritic AISI 409 illustrates the beneficial effect of having SNCFE present...

  10. High specialty stainless steels and nickel alloys for FGD dampers

    Energy Technology Data Exchange (ETDEWEB)

    Herda, W.R.; Rockel, M.B.; Grossmann, G.K. [Krupp VDM GmbH, Werdohl (Germany); Starke, K. [Mannesmann-Seiffert GmbH, Beckum (Germany)

    1997-08-01

    Because of process design and construction, FGD installations normally have bypass ducts, which necessitates use of dampers. Due to corrosion from acid dew resulting from interaction of hot acidic flue gases and colder outside environments, carbon steel cannot be used as construction material under these specific conditions. In the past, commercial stainless steels have suffered by pitting and crevice corrosion and occasionally failed by stress corrosion cracking. Only high alloy specialty super-austenitic stainless steels with 6.5% Mo should be used and considered for this application. Experience in Germany and Europe has shown that with regard to safety and life cycle cost analysis as well as providing a long time warranty, a new specialty stainless steel, alloy 31--UNS N08031--(31 Ni, 27 Cr, 6.5 Mo, 0.2 N) has proven to be the best and most economical choice. Hundreds of tons in forms of sheet, rod and bar, as well as strip (for damper seals) have been used and installed in many FGD installations throughout Europe. Under extremely corrosive conditions, the new advanced Ni-Cr-Mo alloy 59--UNS N06059--(59 Ni, 23 Cr, 16 Mo) should be used. This paper describes qualification and workability of these alloys as pertains to damper applications. Some case histories are also provided.

  11. Prediction of grain size evolution for low alloyed steels

    Science.gov (United States)

    Dub, Vladimir; Churyumov, Alexandr; Rodin, Alexey; Belikov, Sergey; Barbolin, Alexey

    2018-03-01

    The microstructure of the low alloyed steels after hot plastic deformation and high temperature annealing was described for different regimes of treatment. It was shown, that using of the Avrami- Kolmogorov type equation allows to predict the grain size with accuracy about 7%.

  12. Diode Laser Surface Alloying of Armor Steel with Tungsten Carbide

    Directory of Open Access Journals (Sweden)

    Janicki D.

    2017-06-01

    Full Text Available Metal matrix composite (MMC surface layers reinforced by WC were fabricated on armor steel ARMOX 500T plates via a laser surface alloying process. The microstructure of the layers was assessed by scanning electron microscopy and X-ray diffraction.

  13. Thermal Plasma Spheroidization of High-Nitrogen Stainless Steel Powder Alloys Synthesized by Mechanical Alloying

    Science.gov (United States)

    Razumov, Nikolay G.; Popovich, Anatoly A.; Wang, QingSheng

    2018-03-01

    This paper presents the results of experimental studies on the treatment of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, synthesized by the mechanical alloying (MA) of elemental powders in the flow of a thermal plasma. Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys were prepared by MA in the attritor under an argon atmosphere. For spheroidization of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, the TekSphero 15 plant manufactured by Tekna Plasma Systems Inc was used. The studies have shown the possibility of obtaining Fe-23Cr-11Mn-1N high-nitrogen spherical powders steel alloys from the powder obtained by MA. According to the results of a series of experiments, it was found that the results of plasma spheroidization of powders essentially depend on the size of the fraction due to some difference in the particle shape and flowability, and on the gas regime of the plasma torch. It is established that during the plasma spheroidization process, some of the nitrogen leaves the alloy. The loss rate of nitrogen depends on the size of the initial particles.

  14. Principles of alloy design in high nitrogen 12% chromium steels

    International Nuclear Information System (INIS)

    Goecmen, A.; Ernst, P.; Holmes, P.

    1999-01-01

    12% chromium steels are hardened by a martensitic transformation and by precipitation reactions of the martensite during a subsequent tempering treatment. The original alloy design of these steels is based on the intensifying effect of C on the martensitic transformation hardening as well as on the effects of V and Mo on intensity and stability of carbide precipitation hardening reactions. Advanced alloy design of high carbon 12% chromium steels makes use of f.c.c.-MX type carbonitrides to improve grain refinement and tempering resistance, whereas alloying with about 0.05 wt.-% nitrogen already plays a decisive role. In this paper, new alloy design opportunities provided by high nitrogen are reviewed, which promise to achieve a best possible compromise between grain size limitation, particle hardening and particle stability of 12% chromium steels. The crucial effects of the solubility product of MX-type phases on grain coarsening resistance, precipitation hardening and particle stability are reviewed. The advantages of high nitrogen steels to improve these properties are rationalized to result from the lower solubility of nitrides compared with carbides. As an advantageous opportunity of the achievable higher grain coarsening resistance, the normalizing temperature in high nitrogen steels can be increased in order to increase the amount of the less soluble and thereby slow coarsening f.c.c.-nitrides. In addition, as a consequence of a higher normalizing temperature, the solubility gap of nitrides in the austenite is expanded, which in turn enables an effective precipitation hardening due to low soluble nitrides in the metastable austenite before the martensitic transformation

  15. Liquid Phase Sintering of Highly Alloyed Stainless Steel

    DEFF Research Database (Denmark)

    Mathiesen, Troels

    1996-01-01

    of boride to AISI 316L type steels have previously been studied, but were found to be sensitive to intergranular corrosion due to formation of intermetallic phases rich in chromium and molybdenum. In order to improve this system further, new investigations have focused on the use of higher alloyed stainless......Liquid phase sintering of stainless steel is usually applied to improve corrosion resistance by obtaining a material without an open pore system. The dense structure normally also give a higher strength when compared to conventional sintered steel. Liquid phase sintrering based on addition...... calculations, made by use of the computer programme Thermo-Calc, were also correlated with the observed microstructure. Corrosion measurements by electrochemical techniques show no signs of intergranular corrosion in contrast to the case of AISI 316L based steel. Furthermore most of the material showed...

  16. Improved Heat Treatment Of Steel Alloy 4340

    Science.gov (United States)

    Cooper, Lawrence B.

    1993-01-01

    New process takes significantly less time than prior heat-treatment processes. Involves placing steel plate directly in furnace and heat-treating. Plate then quenched in slowly moving oil to reduce stresses. Any deflection then pressed out. Possible uses of 4340 steel include new and improved bulletproof vests for military and police personnel and armor for bulletproof automobiles for military, police, diplomatic, and private users. Also used in other military land vehicles as tanks and in both military and civilian aircraft. Lighter armorplate enables land vehicles and aircraft to attain greater speed and maneuverability, consume less fuel, and afford better protection from snipers or terrorists.

  17. Oxidation behavior of steels and Alloy 800 in supercritical water

    International Nuclear Information System (INIS)

    Olmedo, A.M.; Bordoni, R.; Dominguez, G.; Alvarez, M.G.

    2011-01-01

    The oxidation behavior of a ferritic-martensitic steel T91 and a martensitic steel AISI 403 up to 750 h, and of AISI 316L and Alloy 800 up to 336 h in deaerated supercritical water, 450ºC-25 MPa, was investigated in this paper. After exposure up to 750 h, the weight gain data, for steels T91 and AISI 403, was fitted by ∆W=k t n , were n are similar for both steels and k is a little higher for T91. The oxide films grown in the steels were characterized using gravimetry, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and X-ray diffraction. The films were adherent and exhibited a low porosity. For this low oxygen content supercritical water exposure, the oxide scale exhibited a typical duplex structure, in which the scale is composed of an outer iron oxide layer of magnetite (Fe 3 O 4 ) and an inner iron/chromium oxide layer of a non-stoichiometric iron chromite (Fe,Cr) 3 O 4 . Preliminary results, with AISI 316L and Alloy 800, for two exposure periods (168 and 336 h), are also reported. The morphology shown for the oxide films grown on both materials up to 336 h of oxidation in supercritical water, resembles that of a duplex layer film like that shown by stainless steels and Alloy 800 oxide films grown in a in a high temperature and pressure (220-350ºC) of a primary or secondary coolant of a plant. (author) [es

  18. Mechanical properties of low alloy high phosphorus weathering steel

    Directory of Open Access Journals (Sweden)

    Jena B.K.

    2015-01-01

    Full Text Available Mechanical behaviour of two low alloy steels (G11 and G12 was studied with respect to different phosphorus contents. Tensile strength and yield strength increased while percentage elongation at fracture decreased on increasing phosphorus content. The SEM and light optical photomicrograph of low phosphorus steel (G11 revealed ferrite and pearlite microstructure. On increasing phosphorus content from 0.25 wt.% to 0.42 wt.%, the morphology of grain changed from equiaxed shape to pan-cake shape and grain size also increased. The Charpy V notch (CVN impact energy of G11 and G12 steel at room temperature was 32 J and 4 J respectively and their fractographs revealed brittle rupture with cleavage facets for both the steels. However, the fractograph of G11 steel after tensile test exhibited ductile mode of fracture with conical equiaxed dimple while that of G12 steel containing 0.42 wt. % P exhibited transgranular cleavage fracture. Based on this study, G11 steel containing 0.25 wt. % P could be explored as a candidate material for weathering application purpose where the 20°C toughness requirement is 27 J as per CSN EN10025-2:2004 specification.

  19. Resistance Element Welding of Magnesium Alloy/austenitic Stainless Steel

    Science.gov (United States)

    Manladan, S. M.; Yusof, F.; Ramesh, S.; Zhang, Y.; Luo, Z.; Ling, Z.

    2017-09-01

    Multi-material design is increasingly applied in the automotive and aerospace industries to reduce weight, improve crash-worthiness, and reduce environmental pollution. In the present study, a novel variant of resistance spot welding technique, known as resistance element welding was used to join AZ31 Mg alloy to 316 L austenitic stainless steel. The microstructure and mechanical properties of the joints were evaluated. It was found that the nugget consisted of two zones, including a peripheral fusion zone on the stainless steel side and the main fusion zone. The tensile shear properties of the joints are superior to those obtained by traditional resistance spot welding.

  20. Preparation of ferritic 17%Cr ODS steel by mechanical alloying from prealloyed steel powder

    Czech Academy of Sciences Publication Activity Database

    Hadraba, Hynek; Husák, Roman; Kuběna, Ivo; Bureš, R.; Fáberová, M.; Strečková, M.

    2014-01-01

    Roč. 14, č. 4 (2014), s. 222-227 ISSN 1335-8987 R&D Projects: GA ČR(CZ) GA14-25246S Institutional support: RVO:68081723 Keywords : ODS steel * mechanical alloying * hot rolling Subject RIV: JG - Metallurgy

  1. Testing and assessment of low alloy steel for marine application

    International Nuclear Information System (INIS)

    Amjad, M.; Ahmad, S.; Mahmood, K.; Qureshi, A.H.

    2007-01-01

    This paper is an account of the work carried out during the assessment of low alloy steel (WH-80) for marine application. The relevant acceptance criteria consulted during the process is DEFST AN 02-874 and a standard reference material. Assessment is based on the experimental results of the tests carried out for the steel. Testing comprised of mechanical (tensile, impact and hardness) tests, corrosion (immersion corrosion and stress corrosion cracking) tests, metallography test and weldability (weld joint strength, controlled thermal severity -CTS and Y -Groove) tests undertaken at various testing laboratories in Pakistan. The results obtained after testing have been compared with acceptance criteria (DEFSTAN 02-874 and standard reference material). Moreover results have been compared with contemporary steels used for marine applications. Results showed a reasonable agreement with results available in literature for other low alloy steels with respect to mechanical strength and weldability. Steel weldments qualified the weld joint strength tests and weldability tests. Toughness has been measured at various temperatures. Results revealed that the toughness of base metal is higher than heat affected zone (HAZ) and weld metal. In weldability tests, weld metal and HAZ were examined microscopically to investigate integrity of weld. No cracks have been observed in the weld which indicates complete diffusion in to the welding material. WH- 80 steel has exhibited comparatively high corrosion rate, reduction in tensile strength during SCC test and low Charpy energy values at -50 degree C. It is therefore concluded that the WH-80 steel is unsuitable for use in application at subzero (OC) temperatures and in highly corrosive environment. (author)

  2. Description Of Alloy Layer Formation On A Cast Steel Substrate

    Directory of Open Access Journals (Sweden)

    Szajnar J.

    2015-09-01

    Full Text Available A description of alloy layer formation on a steel substrate is presented. Two types of formation are considered: diffusion of carbon and chromium into the solid from the pad in the direction of the cast steel within the FeCrC (grains and diffusion in a layer of liquid chromium cast iron formed in a preceding step. The influence of silicon in the pad on the pad’s transformation into the liquid is also examined. Solidus and liquidus temperatures of high carbon ferrochromium are determined. The larger the content of Si is used in the experiment, the lower the solidus temperature of the FeCrC alloy is observed. This results from the higher intensity of the elements’ diffusion and faster formation of the liquid.

  3. Attack polish for nickel-base alloys and stainless steels

    Science.gov (United States)

    Not Available

    1980-05-28

    A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels is described. The chemical attack polich comprises FeNO/sub 3/, concentrated CH/sub 3/COOH, concentrated H/sub 2/SO/sub 4/ and H/sub 2/O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

  4. Method of polishing nickel-base alloys and stainless steels

    Science.gov (United States)

    Steeves, Arthur F.; Buono, Donald P.

    1981-01-01

    A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels. The chemical attack polish comprises Fe(NO.sub.3).sub.3, concentrated CH.sub.3 COOH, concentrated H.sub.2 SO.sub.4 and H.sub.2 O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

  5. Alloy designing study on low alloy steels used for nuclear reactor pressure vessels

    International Nuclear Information System (INIS)

    Lee, Sunghak; Kim, Sangho; Im, Young Roc; Lee, Hu Chul; Oh, Yong Jun; Hong, Jun Hwa

    2000-01-01

    The present study aims at the development of low-alloy steels used for nuclear reactor pressure vessels by investing the effects of alloying elements on mechanical properties of base metals and heat affected zones. Four steels whose compositions were deviated from the composition specifications of SA 508 steel (class 3) were fabricated by vacuum-induction melting and heat-treatment, and their tensile properties and Charpy impact toughness were evaluated. Microstructural analyses indicated that coarse M 3 C-type carbides and fine M 2 C-type carbides were precipitated along lath boundaries and inside laths, respectively. In the steels having decreased carbon content and increased molybdenum content, the amount of fine M 2 C carbides was greatly increased, while that of coarse M 3 C carbides was decreased, thereby leading to the improvement of tensile properties and impact toughness. Their simulated heat affected zones also had sufficient impact toughness after post-weld heat-treatment. These findings suggested that the low-alloy steels with high strength and toughness could be processed by decreasing carbon and manganese contents and by increasing molybdenum content. (author)

  6. Corrosion of low alloy steels in natural seawater. Influence of alloying elements and bacteria

    International Nuclear Information System (INIS)

    Dajoux Malard, Emilie

    2006-01-01

    Metallic infrastructures immersed in natural seawater are exposed to important corrosion phenomena, sometimes characterised as microbiologically influenced corrosion. The presence of alloying elements in low alloy steels could present a corrosion resistance improvement of the structures. In this context, tests are performed with commercial steel grades, from 0,05 wt pc Cr to 11,5 wt pc Cr. They consist in 'on site' immersion in natural seawater on the one hand, and in laboratory tests with immersion in media enriched with marine sulphide-producing bacteria on the other hand. Gravimetric, microbiological, electrochemical measurements and corrosion product analyses are carried out and show that corrosion phenomenon is composed of several stages. A preliminary step is the reduction of the corrosion kinetics and is correlated with the presence of sessile sulphide-producing bacteria and an important formation of sulphur-containing species. This phase is shorter when the alloying element content of the steel increases. This phase is probably followed by an increase of corrosion, appearing clearly after an 8-month immersion in natural seawater for some of the grade steels. Chromium and molybdenum show at the same time a beneficial influence to generalised corrosion resistance and a toxic effect on sulphide-producing bacteria. This multidisciplinary study reflects the complexity of the interactions between bacteria and steels; sulphide-producing bacteria seem to be involved in corrosion processes in natural seawater and complementary studies would have to clarify occurring mechanisms. (author) [fr

  7. Estimation of atmospheric corrosion of high-strength, low-alloy steels

    Science.gov (United States)

    1997-05-01

    This data analysis was undertaken to investigate the weatherability of steels : whose compositions do not fall in the range of ASTM Standard G101, Estimating : the Atmospheric Corrosion Resistance of Low-Alloy Steels.

  8. Microstructural characterization of intercritically annealed low alloy PM steels

    International Nuclear Information System (INIS)

    Gueral, A.; Tekeli, S.

    2007-01-01

    In this study, the applicability of intercritical annealing heat treatment, which is usually practiced to high strength low alloy ingot steels (HSLA), to low alloy powder metallurgy (PM) processed steels was investigated. With this heat treatment, it was intended to produce a dual-phase steel structure (ferrite + martensite) in PM steel. The effect of various amount of graphite addition on microstructure was also examined. For these purposes, atomized iron powder (Ancorsteel 1000) was mixed with 0.3 and 0.5 wt% graphite powder. The mixed powders were cold pressed at 700 MPa with single action and sintered at 1120 deg. C for 30 min under pure argon gas atmosphere. Some of the sintered specimens were directly annealed at intercritical heat treatment temperatures of 724, 735 and 760 deg. C and rapidly water quenched. Through these heat treatments, ferrite + martensite microstructure with coarse grain size were produced. The other sintered specimens were first austenitized at 890 deg. C for 12 min before intercritically annealing and then rapidly water quenched to produce fully martensitic structure. These specimens with fully martensitic microstructure were subsequently annealed at intercritical annealing temperatures of 724, 735 and 760 deg. C and rapidly water quenched. Ferrite + martensite microstructure with fine grain size was obtained by this route. The experimental results showed that martensite volume fraction increased with increasing intercritical annealing temperature as well as increasing graphite content. It is thought that mechanical properties of PM steels can be controlled by these heat treatments which are an alternative to traditional heat treatments of quenching + tempering applied usually to PM steels

  9. Development of Zn50 Brazing Alloy for Joining Mild Steel to Mild Steel (SAE1018

    Directory of Open Access Journals (Sweden)

    S.C. Nwigbo

    2014-09-01

    Full Text Available This work has developed new brazing alloys for joining mild steel to mild steel (SAE1018 at a lower temperature. The alloys blends and error analysis were done by experimental design software (Design Expert 8.0.7.1. Design of experiments was done by Scheffe quadratic mixture method. The liquidus temperatures were predicted by calculation of phase diagrams of the alloying metals. The brazing alloys were produced by gravity technique and melted using silicon carbide graphite crucible. The quality of the brazing alloys was analyzed by optical microscopy (OM, atomic absorption spectroscopy (AAS and fourier transform infrared spectroscopy (FT-IR. Brazed joints were produced by torch method with a commercial flux. Brazing temperatures (liquidus were tracked by a digital infrared/laser pyrometer. Some mechanical properties studied were tensile strength and hardness. Finally, brazed joints produced from the developed brazing alloys were compared to that produced from muntz brass. Six (6 brazing alloys were successfully developed. Zinc and manganese were the main components, to which were added; 3 to 4 %wt silver and 11 to15 %wt modifying element. The microstructure showed a typical eutectic structure with zinc-rich phase distributed uniformly in the matrix with a combination of different sizes of dendrite, rounded blocks of compounds and hypoeutectic structures. AAS results indicated minimal out-gassing of zinc and FT-IR results indicated very low presence of atmospheric gas. The range of brazing temperature for best results was recorded from 690.90 to 735.10 0C. The joints produced from the developed brazing alloys had acceptable strengths with improved stress-strain behaviour compared to muntz brass.

  10. Mechanical alloying of lanthana-bearing nanostructured ferritic steels

    International Nuclear Information System (INIS)

    Pasebani, S.; Charit, I.; Wu, Y.Q.; Butt, D.P.; Cole, J.I.

    2013-01-01

    A novel nanostructured ferritic steel powder with the nominal composition Fe–14Cr–1Ti–0.3Mo–0.5La 2 O 3 (wt.%) was developed via high energy ball milling. La 2 O 3 was added to this alloy instead of the traditionally used Y 2 O 3 . The effects of varying the ball milling parameters, such as milling time, steel ball size and ball to powder ratio, on the mechanical properties and microstructural characteristics of the as-milled powder were investigated. Nanocrystallites of a body-centered cubic ferritic solid solution matrix with a mean size of approximately 20 nm were observed by transmission electron microscopy. Nanoscale characterization of the as-milled powder by local electrode atom probe tomography revealed the formation of Cr–Ti–La–O-enriched nanoclusters during mechanical alloying. The Cr:Ti:La:O ratio is considered “non-stoichiometric”. The average size (radius) of the nanoclusters was about 1 nm, with number density of 3.7 × 10 24 m −3 . The mechanism for formation of nanoclusters in the as-milled powder is discussed. La 2 O 3 appears to be a promising alternative rare earth oxide for future nanostructured ferritic steels

  11. Cyclic Partial Phase Transformations In Low Alloyed Steels : Modeling and Experiments

    NARCIS (Netherlands)

    Chen, H.

    2013-01-01

    Mechanical properties of low alloyed steels are directly determined by their microstructures. Thanks to versatility in their microstructures, the mechanical properties of low alloyed steels are much more adjustable than other materials. In the industry, one of the most effective ways to obtain the

  12. 48 CFR 225.7011 - Restriction on carbon, alloy, and armor steel plate.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Restriction on carbon, alloy, and armor steel plate. 225.7011 Section 225.7011 Federal Acquisition Regulations System DEFENSE... on carbon, alloy, and armor steel plate. ...

  13. The quality of the joint between alloy steel and unalloyed cast steel in bimetallic layered castings

    Directory of Open Access Journals (Sweden)

    T. Wróbel

    2012-01-01

    Full Text Available In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast process so-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer. The bearing part of bimetallic layered casting is typical foundry material i.e. ferritic-pearlitic unalloyed cast steel, whereas working part (layer is plate of austenitic alloy steel sort X2CrNi 18-9. The ratio of thickness between bearing and working part is 8:1. The aim of paper was assessed the quality of the joint between bearing and working part in dependence of pouring temperature and carbon concentration in cast steel. The quality of the joint in bimetallic layered castings was evaluated on the basis of ultrasonic non-destructive testing, structure and microhardness researches.

  14. 46 CFR 54.25-15 - Low temperature operation-high alloy steels (modifies UHA-23(b) and UHA-51).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Low temperature operation-high alloy steels (modifies... (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-15 Low temperature operation—high alloy steels (modifies UHA-23(b) and UHA-51). (a) Toughness...

  15. Phase equilibria and thermodynamic properties of high-alloy tool steels : theoretical and experimental approach

    OpenAIRE

    Bratberg, Johan

    2005-01-01

    The recent development of tool steels and high-speed steels has led to a significant increase in alloy additions, such as Co, Cr, Mo, N, V, and W. Knowledge about the phase relations in these multicomponent alloys, that is, the relative stability between different carbides or the solubility of different elements in the carbides and in the matrix phase, is essential for understanding the behaviour of these alloys in heat treatments. This information is also the basis for improving the properti...

  16. High-temperature corrosion of alloyed steels in molten sodium tetraborate under atmosphere of air

    International Nuclear Information System (INIS)

    Kochergin, V.P.; Zvegintseva, G.E.; Vinyarskaya, I.N.; Demidenko, O.V.; Sazonova, N.A.

    1993-01-01

    Results of corrosion process investigation at 1123-1223 K in molten sodium tetraborate on the surface of samples produced of steels alloyed by 1-6 mas.% of Mn, chromium-nickel steels containing 0.35 mas.% of C, 1-3 mas.% of Cr and Ni, as well as of a group of corrosion resistant steels are generalized

  17. Medium alloyed magnetic steel with low core loss and high permeability

    Science.gov (United States)

    Huneus, H.; Kochmann, T.; Schoppa, A.; Wich, H.

    1992-07-01

    In non-oriented silicon-steel the high-field permeability usually decreases with decreasing core loss. A new magnetic steel grade Staboperm T 1 is presented which combines the low core loss of high silicon steel grades with the high magnetic polarization of non-alloyed grades.

  18. Medium alloyed magnetic steel with low core loss and high permeability

    International Nuclear Information System (INIS)

    Huneus, H.; Kochmann, T.; Schoppa, A.; Wich, H.

    1992-01-01

    In non-oriented silicon-steel the high-field permeability usually decreases with decreasing core loss. A new magnetic steel grade Staboperm T 1 is presented which combines the low core loss of high silicon steel grades with the high magnetic polarization of non-alloyed grades

  19. Stress transmission through Ti-Ni alloy, titanium and stainless steel in impact compression test.

    Science.gov (United States)

    Yoneyama, T; Doi, H; Kobayashi, E; Hamanaka, H; Tanabe, Y; Bonfield, W

    2000-06-01

    Impact stress transmission of Ti-Ni alloy was evaluated for biomedical stress shielding. Transformation temperatures of the alloy were investigated by means of DSC. An impact compression test was carried out with use of split-Hopkinson pressure-bar technique with cylindrical specimens of Ti-Ni alloy, titanium and stainless steel. As a result, the transmitted pulse through Ti-Ni alloy was considerably depressed as compared with those through titanium and stainless steel. The initial stress reduction was large through Ti-Ni alloy and titanium, but the stress reduction through Ti-Ni alloy was more continuous than titanium. The maximum value in the stress difference between incident and transmitted pulses through Ti-Ni alloy or titanium was higher than that through stainless steel, while the stress reduction in the maximum stress through Ti-Ni alloy was statistically larger than that through titanium or stainless steel. Ti-Ni alloy transmitted less impact stress than titanium or stainless steel, which suggested that the loading stress to adjacent tissues could be decreased with use of Ti-Ni alloy as a component material in an implant system. Copyright 2000 Kluwer Academic Publishers

  20. Reactive Boride Brazing on Low-Alloy Automotive Grade Steel

    Science.gov (United States)

    Palanisamy, B.; Upadhyaya, A.

    2011-11-01

    Brazing is a widely used process to improve the performance of steels used in automotive applications. The substrate material is often exposed to harsh conditions in these applications and may affect the service life of the component. Reactive boride brazing aims to improve the mechanical properties of the substrate material by forming a ceramic-metal composite coating in a single-step process in situ. In this study, sintered Ancor 4300 low-alloy steel is used as the substrate with chromium-rich braze and chromium-lean braze materials. The mechanical properties of the brazed samples were studied in detail using microindentation hardness measurements and the transverse rupture test. The results indicate that the brazed superlayer has a 10 times higher hardness. There was a significant improvement in the transverse rupture strength of the steel brazed with the chromium-rich boride as compared to the pure substrate material. In an effort to reduce processing time, green compacts of the substrate were also directly brazed and yielded favorable results.

  1. STRESS CORROSION CRACKING OF ALLOY 152 WELD BUTTER NEAR THE LOW ALLOY STEEL INTERFACE

    Energy Technology Data Exchange (ETDEWEB)

    Alexandreanu, Bogdan; Chen, Yiren; Natesan, Ken; Shack, William J.

    2015-01-01

    The objective of this work was to obtain SCC growth data in Alloy 152 weld butter near the interface with Low Alloy Steel (LAS), which is a region where some dilution of Cr was expected to have occurred, thus presumably exhibiting an increased SCC-susceptibility vs. the bulk of the weld. The LAS piece used in this application was Alloy 533-Gr B from the Midland reactor lower head, and the Alloy 152 weld butter received a prototypical Post Weld Heat Treatment (PWHT) prior to joining by Alloy 152 to an Alloy 690 piece according to a procedure qualified to ASME IX. The compact tension specimens for SCC testing were aligned in the first layer of the Alloy 152 butter. The experimental approach based on tracking environmental enhancement vs. location was successful in identifying SCC-susceptible locations, and SCC rates ranging from 10-12 m/s to as high as 10-10 m/s were measured. The post-test examination of the specimens found that the fracture had the intergranular/interdendritic appearance typical of welds, and that the propagation was arrested wherever an intersection with the LAS occurred. The large range of SCC rates measured does not appear to correlate well with the local concentration of Cr (approx. 25% at the SCC locations), and, in fact, low Cr (20%) – high Fe “streaks” seemed to slow/arrest crack propagation. In short, simple “Cr dilution” does not seem to fully account for the “SCC-susceptible” microstructure that yielded the 10-10 m/s growth rate in this weld.

  2. Optimization of Micro-Alloying Elements for Mechanical Properties in Normalized Cast Steel Using Taguchi Technique

    Directory of Open Access Journals (Sweden)

    Chokkalingam B.

    2017-06-01

    Full Text Available In this study, Taguchi method is used to find out the effect of micro alloying elements like vanadium, niobium and titanium on the hardness and tensile strength of the normalized cast steel. Based on this method, plan of experiments were made by using orthogonal arrays to acquire the data on hardness and tensile strength. The signal to noise ratio and analysis of variance (ANOVA are used to investigate the effect of these micro alloying elements on these two mechanical properties of the micro alloyed normalized cast steel. The results indicated that in the micro alloyed normalized cast steel both these properties increases when compared to non-micro-alloyed normalized cast steel. The effect of niobium addition was found to be significantly higher to obtain higher hardness and tensile strength when compared to other micro alloying elements. The maximum hardness of 200HV and the maximum tensile strength of 780 N/mm2 were obtained in 0.05%Nb addition micro alloyed normalized cast steel. Micro-alloyed with niobium normalized cast steel have the finest and uniform microstructure and fine pearlite colonies distributed uniformly in the ferrite. The optimum condition to obtain higher hardness and tensile strength were determined. The results were verified with experiments.

  3. Cathodic protection of steel by electrodeposited zinc-nickel alloy coatings

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, K.R.; Smith, C.J.E. [Defence Research Agency, Farnborough (United Kingdom). Structural Materials Centre; Robinson, M.J. [Cranfield Univ. (United Kingdom). School of Industrial and Manufacturing Science

    1995-12-01

    The ability of electrodeposited zinc-nickel alloy coatings to cathodically protect steel was studied in dilute chloride solutions. The potential distribution along steel strips partly electroplated with zinc-nickel alloys was determined, and the length of exposed steel that was held below the minimum protection potential (E{sub prot}) was taken as a measure of the level of cathodic protection (CP) provided by the alloy coatings. The level of CP afforded by zinc alloy coatings was found to decrease with increasing nickel content. When nickel content was increased to {approx} {ge} 21 wt%, no CP was obtained. Surface analysis of uncoupled zinc-nickel alloys that were immersed in sodium chloride (NaCl) solutions showed the concentration of zinc decreased in the surface layers while the concentration of nickel increased, indicating that the alloys were susceptible to dezincification. The analysis of zinc-nickel alloy coatings on partly electroplated steel strips that were immersed in chloride solution showed a significantly higher level of dezincification than that found for uncoupled alloy coatings. This effect accounted for the rapid loss of CP afforded to steel by some zinc alloy coatings, particularly those with high initial nickel levels.

  4. Enhancement of Impact Toughness by Delamination Fracture in a Low-Alloy High-Strength Steel with Al Alloying

    Science.gov (United States)

    Sun, Junjie; Jiang, Tao; Liu, Hongji; Guo, Shengwu; Liu, Yongning

    2016-12-01

    The effect of delamination toughening of martensitic steel was investigated both at room and low temperatures [253 K and 233 K (-20 °C and -40 °C)]. Two low-alloy martensitic steels with and without Al alloying were both prepared. Layered structure with white band and black matrix was observed in Al alloyed steel, while a homogeneous microstructure was displayed in the steel without Al. Both steels achieved high strength (tensile strength over 1600 MPa) and good ductility (elongation over 11 pct), but they displayed stark contrasts on impact fracture mode and Charpy impact energy. Delamination fracture occurred in Al alloyed steel and the impact energies were significantly increased both at room temperature (from 75 to 138 J, i.e., nearly improved up to 2 times) and low temperatures [from 47.9 to 71.3 J at 233 K (-40 °C)] compared with the one without Al. Alloying with Al promotes the segregation of Cr, Mn, Si and C elements to form a network structure, which is martensite with higher carbon content and higher hardness than that of the matrix. And this network structure evolved into a band structure during the hot rolling process. The difference of yield stress between the band structure and the matrix gives rise to a delamination fracture during the impact test, which increases the toughness greatly.

  5. Effect of Aluminum Alloying on the Hot Deformation Behavior of Nano-bainite Bearing Steel

    Science.gov (United States)

    Yang, Z. N.; Dai, L. Q.; Chu, C. H.; Zhang, F. C.; Wang, L. W.; Xiao, A. P.

    2017-12-01

    Interest in using aluminum in nano-bainite steel, especially for high-carbon bearing steel, is gradually growing. In this study, GCr15SiMo and GCr15SiMoAl steels are introduced to investigate the effect of Al alloying on the hot deformation behavior of bearing steel. Results show that the addition of Al not only notably increases the flow stress of steel due to the strong strengthening effect of Al on austenite phase, but also accelerates the strain-softening rates for its increasing effect on stacking fault energy. Al alloying also increases the activation energy of deformation. Two constitutive equations with an accuracy of higher than 0.99 are proposed. The constructed processing maps show the expanded instability regions for GCr15SiMoAl steel as compared with GCr15SiMo steel. This finding is consistent with the occurrence of cracking on the GCr15SiMoAl specimens, revealing that Al alloying reduces the high-temperature plasticity of the bearing steel. On the contrary, GCr15SiMoAl steel possesses smaller grain size than GCr15SiMo steel, manifesting the positive effect of Al on bearing steel. Attention should be focused on the hot working process of bearing steel with Al.

  6. Process to determine light elements content of steel and alloys

    Energy Technology Data Exchange (ETDEWEB)

    Quintella, Cristina M.A.L.T.M.H.; Castro, Martha T.P.O. [Universidade Federal da Bahia (IQ/UFBA), Salvador, BA (Brazil). Inst. de Quimica. LabLaser; Mac-Culloch, Joao N.L.M. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2009-07-01

    The present work reports a process to determine qualitatively and quantitatively elements of molar mass inferior to 23 within materials, by X rays spectra associated with multivariate data analysis, or chemometric analysis. The spectra is acquired between 5 keV and 22 keV when the materials are exposed to X radiation. Here is reported the direct determination of carbon content in steel and metallic alloys. The process is more effective when using spectral regions which are not usually used. From the analysis of these spectral regions which were not considered before, it was possible to detect light elements with molar mass lower than 23, which have low capacity of absorbing and emitting radiation, but have high capacity of scattering radiation. The process here reported has the advantage that X-Ray spectra obtained are calibrated multivariately, showing high potential for development in order to be used in a portable field equipment. (author)

  7. Development of Creep Constitutive Equation for Low-Alloy Steel

    International Nuclear Information System (INIS)

    Jeong, Kwang J.; Lim, Joon; Hwang, Il S.; Kim, Hee D.; Pilch, Martin M.; Chu, Tze Y.

    2003-01-01

    High-temperature creep tests were performed with an SA533B1 low-alloy steel under both constant load and constant stress conditions. Using the measured minimum creep strain rates as a function of stress and temperature, least-square fittings were made into a Bailey-Norton-type power law equation. Based on the constant stress test results, a constitutive equation was developed for steady-state creep. The constitutive equation was then implemented in elastic-viscoplastic analysis of the lower head of a pressurized water reactor's reactor pressure vessel using a commercial FEM code named ABAQUS 5.8. The FEM model was validated using measured data from the lower head failure experiment conducted at the Sandia National Laboratories. The FEM model using the creep constitutive equation was shown to be capable of accurately predicting the lower head deformation behavior. Additional work, however, is needed to rationalize apparent inconsistency between the constant load data and constant stress data

  8. Friction Welding of Aluminium and Aluminium Alloys with Steel

    Directory of Open Access Journals (Sweden)

    Andrzej Ambroziak

    2014-01-01

    Full Text Available The paper presents our actual knowledge and experience in joining dissimilar materials with the use of friction welding method. The joints of aluminium and aluminium alloys with the different types of steel were studied. The structural effects occurring during the welding process were described. The mechanical properties using, for example, (i microhardness measurements, (ii tensile tests, (iii bending tests, and (iv shearing tests were determined. In order to obtain high-quality joints the influence of different configurations of the process such as (i changing the geometry of bonding surface, (ii using the interlayer, or (iii heat treatment was analyzed. Finally, the issues related to the selection of optimal parameters of friction welding process were also investigated.

  9. A study of the formation of Cr-surface alloyed layer on structural alloy steel by Co2 laser

    International Nuclear Information System (INIS)

    Kim, T.H.; Han, W.S.

    1986-01-01

    In order to improve wear and erosion-resistances of a structural alloy steel (SNCM 8) during heat-cycling, chromium-alloyed layers were produced on the surface by irradiating Co 2 laser. Specimens were prepared either by electroplating of hard-chromium or coating of chromium powders on the steel followed by the laser treatment. Index values, which related the depth and the width of the alloyed layers to the scanning speed of laser, for both samples are experimentally measured. At a fixed scanning speed, while both samples resulted in a similar depth of the alloyed layers, the chromium powder coated specimen showed larger width of the alloyed layer than the chromium electroplated one. The hardness values of the alloyed layers in both samples were slightly lower than that of the martensitic region beneath the alloyed layers. But they are considerably higher than those of steel matrices. Regardless of the prior treatments before laser irradiation, distributions of chromium were fairly uniform throughout the alloyed layers. (Author)

  10. Alloys influence in ferritic steels with hydrogen attack

    International Nuclear Information System (INIS)

    Moro, L; Rey Saravia, D; Lombardich, J; Saggio, M; Juan, A; Blanco, J

    2003-01-01

    Materials exposed to a corrosive environment and high temperatures, are associated with a decrease of their mechanical properties and embitterment.At room temperatures atomic hydrogen diffuses easily through metals structure, it accumulates in lattice defects forming molecular hydrogen and generating cracking due to internal stresses.Under high temperatures the phenomenon is more complex.The steels in these conditions present different structures of precipitates, that the change under creep conditions period.In this work it is determined the influence of Cr and V alloys, the changes of ferritic steel resistance in a corrosive environment and high temperatures.1.25 Cr 1 Mo 0.25 V and 2.25Cr 1 Mo under different loads and temperatures previously attacked by hydrogen environment.The hydrogen is induced by the electrolytic technique, optimizing the choice of temperatures, current density, electrolyte, etc. In order to control an adequate cathode charge, a follow up procedure is carried out by electronic barrier microscopy.After the attack, the material is settled at room temperatures for certain period of time, to allow the hydrogen to leave and evaluate the residual damage.Creep by torsion assays, under constant load and temperature is used as an experimental technique.With the outcome data curves are drawn in order to study the secondary creep rate, with the applied load and temperature, determining the value of stress exponent n and the activation energy Q.Comparing to equal assays to the same ferritic steels but non attacked by hydrogen, these values allows the prediction of microstructure changes present during these tests

  11. Investigation of Cr-CrN coatings of medium-carbon low-alloyed steels

    International Nuclear Information System (INIS)

    Lojko, V.A.; Semin, E.V.; Markova, L.V.

    2012-01-01

    Results of research of CrN coatings deposited by vacuum-plasma evaporation on a medium-carbon low-alloyed steel are presented. Defects of coatings the reasons of their occurrence are analyzed. (authors).

  12. Corrosion Behavior and Durability of Low-Alloy Steel Rebars in Marine Environment

    Science.gov (United States)

    Liu, Ming; Cheng, Xuequn; Li, Xiaogang; Yue, Pan; Li, Jun

    2016-11-01

    The corrosion resistance of Cr-modified low-alloy steels and HRB400 carbon steel was estimated using the open-circuit potential, potentiodynamic polarization, electrochemical impedance spectroscopic, and weight loss methods in simulated concrete pore solution. Results show that Cr-modified steels exhibit a higher corrosion resistance with a higher critical chloride level (CTL), lower corrosion current density, and higher impedance than carbon steel. The CTL of the steels significantly reduces with increasing temperature. Weight loss measurement shows that the Cr-modified steels exhibit low corrosion rates and small corrosion pitting. The primary constituents of the corrosion scales are Fe2O3, Fe3O4, β-FeOOH, γ-FeOOH, and α-FeOOH. A large amount of α-FeOOH could be detected in the Cr-modified steel corrosion products. Moreover, the Cr-modified steels demonstrate a higher durability than HRB400 carbon steel.

  13. Design of a low-alloy high-strength and high-toughness martensitic steel

    Science.gov (United States)

    Zhao, Yan-jun; Ren, Xue-ping; Yang, Wen-chao; Zang, Yue

    2013-08-01

    To develop a high strength low alloy (HSLA) steel with high strength and high toughness, a series of martensitic steels were studied through alloying with various elements and thermodynamic simulation. The microstructure and mechanical properties of the designed steel were investigated by optical microscopy, scanning electron microscopy, tensile testing and Charpy impact test. The results show that cementite exists between 500°C and 700°C, M7C3 exits below 720°C, and they are much lower than the austenitizing temperature of the designed steel. Furthermore, the Ti(C,N) precipitate exists until 1280°C, which refines the microstructure and increases the strength and toughness. The optimal alloying components are 0.19% C, 1.19% Si, 2.83% Mn, 1.24% Ni, and 0.049% Ti; the tensile strength and the V notch impact toughness of the designed steel are more than 1500 MPa and 100 J, respectively.

  14. Property Optimization in As-Quenched Martensitic Steel by Molybdenum and Niobium Alloying

    Directory of Open Access Journals (Sweden)

    Hardy Mohrbacher

    2018-04-01

    Full Text Available Niobium microalloying is the backbone of modern low-carbon high strength low alloy (HSLA steel metallurgy, providing a favorable combination of strength and toughness by pronounced microstructural refinement. Molybdenum alloying is established in medium-carbon quenching and tempering of steel by delivering high hardenability and good tempering resistance. Recent developments of ultra-high strength steel grades, such as fully martensitic steel, can be optimized by using beneficial metallurgical effects of niobium and molybdenum. The paper details the metallurgical principles of both elements in such steel and the achievable improvement of properties. Particularly, the underlying mechanisms of improving toughness and reducing the sensitivity towards hydrogen embrittlement by a suitable combination of molybdenum and niobium alloying will be discussed.

  15. Galvanic Interaction between Chalcopyrite and Pyrite with Low Alloy and High Carbon Chromium Steel Ball

    Directory of Open Access Journals (Sweden)

    Asghar Azizi

    2013-01-01

    Full Text Available This study was aimed to investigate the galvanic interaction between pyrite and chalcopyrite with two types of grinding media (low alloy and high carbon chromium steel ball in grinding of a porphyry copper sulphide ore. Results indicated that injection of different gases into mill altered the oxidation-reduction environment during grinding. High carbon chromium steel ball under nitrogen gas has the lowest galvanic current, and low alloy steel ball under oxygen gas had the highest galvanic current. Also, results showed that the media is anodic relative to pyrite and chalcopyrite, and therefore pyrite or chalcopyrite with a higher rest potential acted as the cathode, whilst the grinding media with a lower rest potential acted as the anode, when they are electrochemically contacted. It was also found that low alloy steel under oxygen produced the highest amount of EDTA extractable iron in the slurry, whilst high carbon chromium steel under nitrogen atmosphere led to the lowest amount.

  16. Microstructural characterisation of friction stir welding joints of mild steel to Ni-based alloy 625

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J. [Brazilian Nanotechnology National Laboratory (LNNano), P.O. Box 6192, Campinas, SP (Brazil); University of Campinas (UNICAMP), Campinas, SP (Brazil); Ramirez, A.J., E-mail: ramirezlondono.1@osu.edu [Brazilian Nanotechnology National Laboratory (LNNano), P.O. Box 6192, Campinas, SP (Brazil); University of Campinas (UNICAMP), Campinas, SP (Brazil); Department of Materials Science and Engineering, The Ohio State University — OSU, Columbus, OH 43221 (United States)

    2015-12-15

    In this study, 6-mm-thick mild steel and Ni-based alloy 625 plates were friction stir welded using a tool rotational speed of 300 rpm and a travel speed of 100 mm·min{sup −1}. A microstructural characterisation of the dissimilar butt joint was performed using optical microscopy, scanning and transmission electron microscopy, and energy dispersive X-ray spectroscopy (XEDS). Six different weld zones were found. In the steel, the heat-affected zone (HAZ) was divided into three zones and was composed of ferrite, pearlite colonies with different morphologies, degenerated regions of pearlite and allotriomorphic and Widmanstätten ferrite. The stir zone (SZ) of the steel showed a coarse microstructure consisting of allotriomorphic and Widmanstätten ferrite, degenerate pearlite and MA constituents. In the Ni-based alloy 625, the thermo-mechanically affected zone (TMAZ) showed deformed grains and redistribution of precipitates. In the SZ, the high deformation and temperature produced a recrystallised microstructure, as well as fracture and redistribution of MC precipitates. The M{sub 23}C{sub 6} precipitates, present in the base material, were also redistributed in the stir zone of the Ni-based alloy. TMAZ in the steel and HAZ in the Ni-based alloy could not be identified. The main restorative mechanisms were discontinuous dynamic recrystallisation in the steel, and discontinuous and continuous dynamic recrystallisation in the Ni-based alloy. The interface region between the steel and the Ni-based alloy showed a fcc microstructure with NbC carbides and an average length of 2.0 μm. - Highlights: • Comprehensive microstructural characterisation of dissimilar joints of mild steel to Ni-based alloy • Friction stir welding of joints of mild steel to Ni-based alloy 625 produces sound welds. • The interface region showed deformed and recrystallised fcc grains with NbC carbides and a length of 2.0 μm.

  17. 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

  18. Comparative Studies on the Wear of ADI Alloy Cast Irons as Well as Selected Steels and Surface-Hardened Alloy Cast Steels in the Presence of Abrasive

    Directory of Open Access Journals (Sweden)

    Wieczorek A. N.

    2017-03-01

    Full Text Available The paper presents the results of wear tests obtained for 4 groups of materials: surface-hardened alloy steels and alloy cast steels for structural applications, hard-wearing surface-hardened alloy cast steels, and austempered alloy cast irons. The wear tests have been performed on a specially designed test rig that allows reproducing the real operating conditions of chain wheels, including the rolling and sliding form of contact between elements. The chain wheels subjected to tests were operated with the use of loose quartz abrasive. This study presents results of measurements of material parameters, micro-structure of a surface subject to wear, as well as the linear wear determined for the materials considered. Based on the results, the following was found: the best wear properties were obtained for surface-hardened alloy steels and wear surface; strengthening of the ADI surface took place - most probably as a result of transformation of austenite into martensite; the uniformity of the structure of the materials affects the surface wear process. The study also indicated a significant degree of graphite deformation in ADI characterized by the upper ausferritic structure and its oblique orientation in relation to the surface, which resulted in a facilitated degradation of the surface caused by the quartz abrasive.

  19. Tensile and impact behaviour of BATMAN II steels, Ti-bearing reduced activation martensitic alloys

    Science.gov (United States)

    Filacchioni, G.; Casagrande, E.; De Angelis, U.; De Santis, G.; Ferrara, D.; Pilloni, L.

    Two series of Reduced Activation Ferrous alloys (RAF) have been produced and studied by Casaccia's Laboratories. These martensitic alloys are named BATMAN steels. They are among the few presently developed RAF materials to exploit Ti as a carbide forming and grain size stabilizing element instead of Ta. In this work their mechanical properties are illustrated.

  20. 76 FR 78882 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Affirmative Preliminary Determination of...

    Science.gov (United States)

    2011-12-20

    ... Steel Wire Rod From Mexico: Affirmative Preliminary Determination of Circumvention of the Antidumping... circumvention inquiry into whether Deacero S.A. de C.V. (Deacero) and Ternium Mexico S.A. de C.V. (Ternium... wire rod are covered by this circumvention inquiry. \\3\\ See Carbon and Certain Alloy Steel Wire Rod...

  1. Use of Nitrocarburizing for Strengthening Threaded Joints of Drill Pipes from Medium-Carbon Alloy Steels

    Science.gov (United States)

    Priymak, E. Yu.; Stepanchukova, A. V.; Yakovleva, I. L.; Tereshchenko, N. A.

    2015-05-01

    Nitrocarburizing is tested at the Drill Equipment Plant for reinforcing threaded joints of drill pipes for units with retrievable core receiver (RCR). The effect of the nitrocarburizing on the mechanical properties of steels of different alloying systems is considered. Steels for the production of threaded joints of drill pipes are recommended.

  2. INVESTIGATION OF POSSIBILITY OF THE SILICON CARBIDE USING FOR DEOXIDATION AND ALLOYING OF STEEL

    OpenAIRE

    M. E. Kontanistov; A. V. Olenchenko

    2004-01-01

    The carried out work on investigation of the possibility of using of silicon carbide for the steel deoxidation and alloying showed that using of silicon carbide is economically expedient on medium-carbon, high-carbon and cord types of steel.

  3. Improvement of corrosion resistance of low-alloy steels by resurfacing using multifunction cavitation in water

    Science.gov (United States)

    Ijiri, Masataka; Yoshimura, Toshihiko

    2018-02-01

    Low-alloy steels are based on carbon steel in combination with several percent or less (in many cases, 1 mass%) alloying elements, and they offer improved resistance to corrosion at a cost slightly higher than that of carbon steel. However, these materials do not exhibit the same corrosion resistance as stainless steel. The authors have previously developed a novel multifunction cavitation (MFC) technique, which combines ultrasonic cavitation with water jet cavitation. In this study, MFC was used to modify the surface of Cr-Mo steel (SCM435) and Ni-Cr-Mo steel (SNCM630). MFC was found to improve the residual stress value of the material as the result of surface modification while also imparting high strength and superior corrosion resistance.

  4. Prevention of Crevice Corrosion of STS 304 Stainless Steel by a Mg-alloy Galvanic Anode

    International Nuclear Information System (INIS)

    Lim, U. J.; Yun, B. D.; Kim, J. J.

    2006-01-01

    Prevention of crevice corrosion was studied for STS 304 stainless steel using a Mg-alloy galvanic anode in solutions with various specific resistivity. The crevice corrosion and corrosion protection characteristics of the steel was investigated by the electrochemical polarization and galvanic corrosion tests. Experimental results show that the crevice corrosion of STS 304 stainless steel does not occur in solutions of high specific resistivity, but it occurs in solutions of low specific resistivity like in solutions with resistivities of 30, 60 and 115 Ω · m. With decreasing specific resistivity of the solution, the electrode potential of STS 304 stainless steel in the crevice is lowered. The potential of STS 304 stainless steel in the crevice after coupling is cathodically polarized more by decreasing specific resistivity indicating that the crevice corrosion of STS 304 stainless steel is prevented by the Mg-alloy galvanic anode

  5. Effect of tempering temperature on the properties of low-alloy cast steel

    Directory of Open Access Journals (Sweden)

    D. Bartocha

    2011-07-01

    Full Text Available The mechanical properties of cast steel are primarily a function of chemical composition and solidification conditions i.e. primary structure, however, them can be change in a limited extent, by heat treatment. In the article the influence parameters of quenching on mechanical properties of low-alloy structural cast steel, modeled in terms of chemical composition, on the cast steel L20HGSNM, are presented. An attempt to quantify this relationship was made.

  6. Diffusion Couple Alloying of Refractory Metals in Austenitic and Ferritic/Martensitic Steels

    Science.gov (United States)

    2012-03-01

    temperature (DBTT) and lower upper shelf energy (USE) obtained via a Charpy impact test (austenitic steels , however, do not experience DBTT) as seen in...ALLOYING OF REFRACTORY METALS IN AUSTENITIC AND FERRITIC/MARTENSITIC STEELS by Alexander L. McGinnis March 2012 Thesis Advisor: Luke...Ferritic/Martensitic Steels 5. FUNDING NUMBERS 6. AUTHOR(S) Alexander L. McGinnis 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval

  7. The kinetics of phase transformations during tempering of low alloy medium carbon steel

    OpenAIRE

    J. Krawczyk; J. Pacyna; P. Bała

    2007-01-01

    Purpose: This work contains a detailed description of the kinetics of phase transformations during tempering ofhardened low alloy medium carbon steel. Moreover, the differences in hardness and microstructure of samples ofthe investigated steel in relationship to the heat treatment were evaluated.Design/methodology/approach: CHT diagram, illustrating the kinetics of phase transformations duringcontinuous heating (tempering) from as-quenched state of investigated steel, was elaborated using a D...

  8. Role of alloying elements and carbides in the chlorine-induced corrosion of steels and alloys

    Directory of Open Access Journals (Sweden)

    Hans Jürgen Grabke

    2004-03-01

    Full Text Available The high temperature corrosion of steels and Ni-base alloys in oxidizing and chloridizing environments is of practical interest in relation to problems in waste incineration plants and power plants using Cl containing fuels. The behaviour of the most important alloying elements Fe, Cr, Ni, Mo, Mn, Si, Al upon corrosion in an oxidizing and chloridizing atmosphere was elucidated: the reactions and kinetics can be largely understood on the base of thermodynamic data, i.e. free energy of chloride formation, vapor pressure of the chlorides and oxygen pressure pO2 needed for the conversion chlorides -> oxides. The mechanism is described by 'active oxidation', comprising inward penetration of chlorine into the scale, formation of chlorides at the oxide/metal interface, evaporation of the chlorides and conversion of the evaporating chlorides into oxides, which occurs in more or less distance from the surface (depending on pO2. This process leads to loose, fragile, multilayered oxides which are unprotective (therefore: active oxidation. Fe and Cr are rapidly transferred into such scale, Ni and Mo are relatively resistant. In many cases, the grain boundaries of the materials are strongly attacked, this is due to a susceptibility of chromium carbides to chloridation. In contrast the carbides Mo2C, TiC and NbC are less attacked than the matrix. Alloys on the basis Fe-Cr-Si proved to be rather resistant, and the alloying elements Ni and Mo clearly retard the attack in an oxidizing and chloridizing environment.

  9. [Determination of trace bismuth in iron, steel and alloy by hydride generation-atomic fluorimetry].

    Science.gov (United States)

    Liu, Q

    2000-02-01

    With the aid of hydride generation-atomic fluorimetry, an analysis method by adding thiosemicarbazide-ascorbic acid and phosphoric acid to eliminate the interference of matrix has been developed for the determination of trace bismuth in iron, steel and alloy. The detection limit is Bi = 0.02 microgram.g-1 (3 sigma, n = 11, sample amount 0.2000 g). The method has been applied to determine trace arsenic in middle and low alloy steel, ferro and nickel-based superalloy, nickel-based superalloy, cobalt-based superalloy, copper alloy with satisfactory results.

  10. Deformation Induced Martensitic Transformation and Its Initial Microstructure Dependence in a High Alloyed Duplex Stainless Steel

    DEFF Research Database (Denmark)

    Xie, Lin; Huang, Tian Lin; Wang, Yu Hui

    2017-01-01

    Deformation induced martensitic transformation (DIMT) usually occurs in metastable austenitic stainless steels. Recent studies have shown that DIMT may occur in the austenite phase of low alloyed duplex stainless steels. The present study demonstrates that DIMT can also take place in a high alloyed...... Fe–23Cr–8.5Ni duplex stainless steel, which exhibits an unexpectedly rapid transformation from γ-austenite into α′-martensite. However, an inhibited martensitic transformation has been observed by varying the initial microstructure from a coarse alternating austenite and ferrite band structure...

  11. Evaluation of non-conformities of hip prostheses made of titanium alloys and stainless steel

    International Nuclear Information System (INIS)

    Bezerra, Ewerton de Oliveira Teotonio; Nascimento, Jose Jeferson da Silva; Luna, Carlos Bruno Barreto; Morais, Crislene Rodrigues da Silva; Campos, Karla Valeria Miranda de

    2017-01-01

    A large number of metallic alloys has satisfactory behavior when used to manufacture implants for hip prostheses. However, they must be in conformity with standards, to ensure their quality for long periods without losing its functionality. Therefore, this paper aims to study the non-conformities in two hip prostheses, one of titanium and other stainless steel according to standards. The implants studied passed by X-ray diffraction (XRD), X-ray fluorescence, tensile test and optical microscopy (OM). Specimens for the tensile test were made according to ASTM E 8M, as well, MO samples passed by metallographic procedure. The results evidenced that some chemical compositions showed in relation to the standards. The XRD analysis showed peaks of austenite and absence of ferrite for the stainless steel, while the titanium alloy presents an alpha phase (HCP) more significant than the beta phase (BCC). The stainless steel alloys and titanium have yield strength and tensile strength that meet the standards. On the other hand, the elastic modulus of the titanium alloy and stainless steel, comes to be ten times greater than the human bone. Therefore, the high modulus of elasticity of the alloys, favors bone resorption problems. The stainless steel microstructure is typical of an austenitic matrix, while the titanium alloy presents α + β microstructure. (author)

  12. Supercritical water corrosion of high Cr steels and Ni-base alloys

    International Nuclear Information System (INIS)

    Jang, Jin Sung; Han, Chang Hee; Hwang, Seong Sik

    2004-01-01

    High Cr steels (9 to 12% Cr) have been widely used for high temperature high pressure components in fossil power plants. Recently the concept of SCWR (supercritical water-cooled reactor) has aroused a keen interest as one of the next generation (Generation IV) reactors. Consequently Ni-base (or high Ni) alloys as well as high Cr steels that have already many experiences in the field are among the potential candidate alloys for the cladding or reactor internals. Tentative inlet and outlet temperatures of the anticipated SCWR are 280 and 510 .deg. C respectively. Among many candidate alloys there are austenitic stainless steels, Ni base alloys, ODS alloys as well as high Cr steels. In this study the corrosion behavior of the high Cr steels and Ni base (or high Ni) alloys in the supercritical water were investigated. The corrosion behavior of the unirradiated base metals could be used in the near future as a guideline for the out-of-pile or in-pile corrosion evaluation tests

  13. Effect of Cooling Rate on Microstructures and Mechanical Properties in SA508 Gr4N High Strength Low Alloy Steel

    International Nuclear Information System (INIS)

    Kim, Minchul; Park, Sanggyu; Choi, Kwonjae; Lee, Bongsang

    2013-01-01

    The microstructure of Ni-Cr-Mo low alloy steel is a mixture of tempered martensite and tempered lower bainite and that of Mn-Mo-Ni low alloy steel is predominantly tempered upper bainite. Higher strength and toughness steels are very attractive as an eligible RPV steel, so several researchers have studied to use the Ni-Cr-Mo low alloy steel for the NPP application. Because of the thickness of reactor vessel, there are large differences in austenitizing cooling rates between the surface and the center locations of thickness in RPV. Because the cooling rates after austenitization determine the microstructure, it would affect the mechanical properties in Ni-Cr-Mo low alloy steel, and it may lead to inhomogeneous characteristics when the commercial scale of RPV is fabricated. In order to apply the Ni-Cr-Mo low alloy steel to RPV, it is necessary to evaluate the changes of microstructure and mechanical properties with varying phase fractions in Ni-Cr-Mo low alloy steel. In this study, the effects of martensite and bainite fractions on mechanical properties in Ni-Cr-Mo low alloy steel were examined by controlling the cooling rate after austenitization. First of all, continuous cooling transformation(CCT) diagram was established from the dilatometric analyses. Then, the phase fractions at each cooling rate were quantitatively evaluated. Finally, the mechanical properties were correlated with the phase fraction, especially fraction of martensite in Ni-Cr-Mo low alloy steel

  14. Finite Element Simulation of Plastic Joining Processes of Steel and Aluminum Alloy Sheets

    Science.gov (United States)

    Mori, K.; Abe, Y.; Kato, T.

    2007-05-01

    Various high tensile strength steel sheets and an aluminum alloy sheet were joined with a self-piercing rivet. It is not easy to weld the aluminum alloy sheet and high tensile strength sheets by means of conventional resistance welding because of very different melting points. To obtain optimum joining conditions, joining defects were categorized into separation of the sheets and an inner fracture. The joining range of ultra high tensile strength steel and aluminum alloy sheets was extended by means of dies optimized by finite element simulation. The joint strength is greatly influenced by not only the strength of the sheets and rivets but also the ratio of the thickness of the lower sheet to the total thickness. In addition, mechanical clinching of high strength steel and aluminum alloy sheets was simulated.

  15. Self-Pierce Riveting of Three Aluminium Alloy and Mild Steel Sheets

    Science.gov (United States)

    Mori, K.; Abe, Y.; Kato, T.; Sakai, S.

    2010-06-01

    Three aluminium alloy and steel sheets were joined with a self-piercing rivet. Self-pierce riveting has the function of joining steel and aluminium alloys having very different melting points due to plastic joining. The requisites for joining the three sheets are the driving of the rivet leg through the middle sheet, the flaring of the rivet leg in the lower sheet and the prevention of the fracture of the lower sheet. The joinability for various combinations of the three sheets was determined. When the rivet leg is small, no driving through the middle sheet occurs, the lower sheet ruptures for a large rivet leg. In addition, 980 MPa high strength steel, mild steel and aluminium alloy sheets were joined by the self-pierce riveting.

  16. The creep properties of a low alloy ferritic steel containing an intermetallic precipitate dispersion

    International Nuclear Information System (INIS)

    Batte, A.D.; Murphy, M.C.; Edmonds, D.V.

    1976-01-01

    A good combination of creep rupture ductility and strength together with excellent long term thermal stability, has been obtained from a dispersion of intermetallic Laves phase precipitate in a non-transforming ferritic low alloy steel. The steel is without many of the problems currently associated with the heat affected zone microstructures of low alloy transformable ferritic steels, and can be used as a weld metal. Following suitable development to optimize the composition and heat treatment, such alloys may provide a useful range of weldable creep resistant steels for steam turbine and other high temperature applications. They would offer the unique possibility of easily achievable microstructural uniformity, giving good long term strength and ductility across the entire welded joint

  17. Nitrogen alloyed 9-12% chromium steels for high temperature applications

    International Nuclear Information System (INIS)

    Anthamatten, B.

    1990-01-01

    Worldwide advanced steam and gas turbines are currently being designed to operate at increased temperature and/or pressure in order to improve the thermodynamic efficiency. To meet the demand of the advanced conditions new ferritic steels with improved creep strength and improved high temperature strength must be developed. 9-12% chromium steels with high nitrogen and reduced carbon contents turn out to be very promising candidate materials. Fundamental knowledge about the nitriding process of 9-12% chromium steels are presented in the first part of this work. Alloys with nitrogen contents up to 0.8% were produced in pressure-ESR-facilities or in a pressure-induction-furnace. The mechanical properties, especially the ratio of strength to toughness, may be distinctly influenced by the addition of nitrogen to 9-12% chromium alloys with reduced carbon contents. It has been shown that for special properties of nitrogen alloyed steels the way of heat treatments is very important. The toughness of these steels is significantly influenced by the solution temperature. At low solution temperatures the nitrogen-steels show higher toughness values than the conventional carbon-steel X20CrMoV121, at high solution temperatures the toughness of both type of steel is almost the same. At high temperatures nitrogen-steels offer significant advantages. At operating temperatures of 600 o C for components in steam turbines high creep rupture properties are desired. At solution treatments around 1150 o C and annealing treatments at 750 o C the nitrogen alloyed 9-12% chromium steels prove high creep rupture strength and significantly exceeded those of the carbon-steels. (author) 54 figs., 13 tabs., 116 refs

  18. TECHNOLOGICAL COMPLEX OF EQUIPMENT FOR REFINING AND CASTING OF STEEL AND ALLOYS IN THE FOUNDRY AND STEEL INDUSTRIES

    Directory of Open Access Journals (Sweden)

    V. I. Zolotukhin

    2013-01-01

    Full Text Available Vulcan TM is a small innovative company, specializing in the manufacture of steel and alloys casting systems and refractory accessories.Available for foundry and metallurgical industries, special technological equipment, designed and manufactured by LLC NPP “Vulkan-TM.”

  19. Effect of Alloy 625 Buffer Layer on Hardfacing of Modified 9Cr-1Mo Steel Using Nickel Base Hardfacing Alloy

    Science.gov (United States)

    Chakraborty, Gopa; Das, C. R.; Albert, S. K.; Bhaduri, A. K.; Murugesan, S.; Dasgupta, Arup

    2016-04-01

    Dashpot piston, made up of modified 9Cr-1Mo steel, is a part of diverse safety rod used for safe shutdown of a nuclear reactor. This component was hardfaced using nickel base AWS ER NiCr-B alloy and extensive cracking was experienced during direct deposition of this alloy on dashpot piston. Cracking reduced considerably and the component was successfully hardfaced by application of Inconel 625 as buffer layer prior to hardface deposition. Hence, a separate study was undertaken to investigate the role of buffer layer in reducing the cracking and on the microstructure of the hardfaced deposit. Results indicate that in the direct deposition of hardfacing alloy on modified 9Cr-1Mo steel, both heat-affected zone (HAZ) formed and the deposit layer are hard making the thickness of the hard layer formed equal to combined thickness of both HAZ and deposit. This hard layer is unable to absorb thermal stresses resulting in the cracking of the deposit. By providing a buffer layer of Alloy 625 followed by a post-weld heat treatment, HAZ formed in the modified 9Cr-1Mo steel is effectively tempered, and HAZ formed during the subsequent deposition of the hardfacing alloy over the Alloy 625 buffer layer is almost completely confined to Alloy 625, which does not harden. This reduces the cracking susceptibility of the deposit. Further, unlike in the case of direct deposition on modified 9Cr-1Mo steel, dilution of the deposit by Ni-base buffer layer does not alter the hardness of the deposit and desired hardness on the deposit surface could be achieved even with lower thickness of the deposit. This gives an option for reducing the recommended thickness of the deposit, which can also reduce the risk of cracking.

  20. Corrosion of carbon steel and low-alloy steel in diluted seawater containing hydrazine under gamma-rays irradiation

    International Nuclear Information System (INIS)

    Nakano, Junichi; Yamamoto, Masahiro; Tsukada, Takashi

    2014-01-01

    Seawater was injected into reactor cores of Units 1, 2, and 3 in the Fukushima Daiichi nuclear power station as an urgent coolant. It is considered that the injected seawater causes corrosion of steels of the reactor pressure vessel and primary containment vessel. To investigate the effects of gamma-rays irradiation on weight loss in carbon steel and low-alloy steel, corrosion tests were performed in diluted seawater at 50°C under gamma-rays irradiation. Specimens were irradiated with dose rates of 4.4 kGy/h and 0.2 kGy/h. To evaluate the effects of hydrazine (N 2 H 4 ) on the reduction of oxygen and hydrogen peroxide, N 2 H 4 was added to the diluted seawater. In the diluted seawater without N 2 H 4 , weight loss in the steels irradiated with 0.2 kGy/h was similar to that in the unirradiated steels, and weight loss in the steels irradiated with 4.4 kGy/h increased to approximate 1.7 times of those in the unirradiated steels. Weight loss in the steels irradiated in the diluted seawater containing N 2 H 4 was similar to that in the diluted seawater without N 2 H 4 . When N 2 was introduced into the gas phase in the flasks during gamma-rays irradiation, weight loss in the steels decreased. (author)

  1. Study of the Metallurgical Aspects of Steel Micro-Alloying by Titan

    Directory of Open Access Journals (Sweden)

    Kijac, J.

    2006-01-01

    Full Text Available The metal properties upgrading applying it’s alloying with the simultaneous limitation of the impurities represents a prospective possibility of the metallurgical production further development. The interaction of the alloying substance active element with oxygen in metal and adjacent multiphase environment occurs under the actual conditions. Present paper is oriented particularly to the thermodynamic aspects of deoxygenation by titan in process of production of micro alloyed low carbon steel in two plants (oxygen converter 1-OC1 and 2-OC2 with the different effect of micro-alloy exploitation. Analysis of the effect of the metallurgical factors on the titan smelting loss in micro-alloyed steel production points at the need to master the metal preparation for the alloying and especially has got the decisive effect upon the oxidizing ability and rate of the slag phase availability. When comparing the micro-alloying matter yield among the individual production units, disclosed have been better results obtained in plant OC 2. Confirmed has been the effect of the slag amount (average amount of 7,3 t at OC 1 and 5,83 t at OC 2 and its quality during the steel tapping as one among the most significant factors affecting the alloying process and which also represent its oxidizing potential.

  2. Study of austenitic stainless steel welded with low alloy steel filler metal. [tensile and impact strength tests

    Science.gov (United States)

    Burns, F. A.; Dyke, R. A., Jr.

    1979-01-01

    The tensile and impact strength properties of 316L stainless steel plate welded with low alloy steel filler metal were determined. Tests were conducted at room temperature and -100 F on standard test specimens machined from as-welded panels of various chemical compositions. No significant differences were found as the result of variations in percentage chemical composition on the impact and tensile test results. The weldments containing lower chromium and nickel as the result of dilution of parent metal from the use of the low alloy steel filler metal corroded more severely in a marine environment. The use of a protective finish, i.e., a nitrile-based paint containing aluminum powder, prevented the corrosive attack.

  3. Effect of impurity and alloying microadditions on the Cr-Mo-V steel structure and properties

    International Nuclear Information System (INIS)

    Lanskaya, K.A.; Kulikova, L.V.; Yarovoj, V.V.

    1985-01-01

    The effect of impurity elements (nitrogen and aluminium) and alloying microadditions titanium and zirconium on the 12Kh1MF-steel-Cr-Mo-V structure, phase composition and properties is investigated. It is shown that the nitrogen and aluminium introduction leads to time decrease up to 12Kh1MF steel fracture. Introduction of zirconium into Cr-Mo-V steel (up to 5%) exerts positive influence on its properties owing to a structural factor. With titarium content of about 0.10% heat resisting steel properties increase, with subsequent increase of its content - they decrease. The cause of such decrease is titanium capacity to extend the ferrite region

  4. Study on Spheroidization and Related Heat Treatments of Medium Carbon Alloy Steels

    OpenAIRE

    Harisha S. R.; Sharma Sathyashankara; Kini U. Achutha; Gowri Shankar M. C.

    2018-01-01

    The importance of medium carbon steels as engineering materials is reflected by the fact that out of the vast majority of engineering grade ferrous alloys available and used in the market today, a large proportion of them are from the family of medium carbon steels. Typically medium carbon steels have a carbon range of 0.25 to 0.65% by weight, and a manganese content ranging from 0.060 to 1.65% by weight. Medium carbon steels are more resistive to cutting, welding and forming as compared to l...

  5. [Study on the multivariate quantitative analysis method for steel alloy elements using LIBS].

    Science.gov (United States)

    Gu, Yan-hong; Li, Ying; Tian, Ye; Lu, Yuan

    2014-08-01

    Quantitative analysis of steel alloys was carried out using laser induced breakdown spectroscopy (LIBS) taking into account the complex matrix effects in steel alloy samples. The laser induced plasma was generated by a Q-switched Nd:YAG laser operating at 1064 nm with pulse width of 10 ns and repeated frequency of 10 Hz. The LIBS signal was coupled to the echelle spectrometer and recorded by a high sensitive ICCD detector. To get the best experimental conditions, some parameters, such as the detection delay, the CCDs integral gate width and the detecting position from the sample surface, were optimized. The experimental results showed that the optimum detection delay time was 1.5 micros, the optimal CCDs integral gate width was 2 micros and the best detecting position was 1.5 mm below the alloy sample's surface. The samples used in the experiments are ten standard steel alloy samples and two unknown steel alloy samples. The quantitative analysis was investigated with the optimum experimental parameters. Elements Cr and Ni in steel alloy samples were taken as the detection targets. The analysis was carried out with the methods based on conditional univariate quantitative analysis, multiple linear regression and partial least squares (PLS) respectively. It turned out that the correlation coefficients of calibration curves are not very high in the conditional univariate calibration method. The analysis results were obtained with the unsatisfied relative errors for the two predicted samples. So the con- ditional univariate quantitative analysis method can't effectively serve the quantitative analysis purpose for multi-components and complex matrix steel alloy samples. And with multiple linear regression method, the analysis accuracy was improved effectively. The method based on partial least squares (PLS) turned out to be the best method among all the three quantitative analysis methods applied. Based on PLS, the correlation coefficient of calibration curve for Cr is 0

  6. An Investigation of the Mechanical Properties of a Weldment of 7% Nickel Alloy Steels

    Directory of Open Access Journals (Sweden)

    Jeong Yeol Park

    2016-11-01

    Full Text Available During the last decade, the demand for natural gas has steadily increased for the prevention of environmental pollution. For this reason, many liquefied natural gas (LNG carriers have been manufactured. Since one of the most important issues in the design of LNG carriers is to guarantee structural safety, the use of low-temperature materials is increasing. Among commonly employed low-temperature materials, nickel steel has many benefits such as good strength and outstanding corrosion resistance. Accordingly, nickel steels are one of the most commonly used low-temperature steels for LNG storage tanks. However, the study of fracture toughness with various welding consumables of 7% nickel alloy steel is insufficient for ensuring the structural safety of LNG storage tanks. Therefore, the aim of this study was to evaluate fracture toughness of several different weldments for 7% nickel alloy steels. The weldment of 7% nickel alloy steel was fabricated by tungsten inert gas (TIG, flux cored arc welding (FCAW, and gas metal arc welding (GMAW. In order to assess the material performance of the weldments at low temperature, fracture toughness such as crack tip opening displacement (CTOD and the absorbed impact energy of weldments were compared with those of 9% nickel steel weldments.

  7. 75 FR 44763 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico; Extension of Time Limit for Preliminary...

    Science.gov (United States)

    2010-07-29

    ... welded non- alloy steel pipe from Mexico. We also received review requests on November 30, 2009, from companies Tuberia Nacional, S.A. de C.V.'s (TUNA), Mueller Comercial de Mexico, S. de R.L. de C.V. (Mueller... International Trade Administration Certain Circular Welded Non-Alloy Steel Pipe From Mexico; Extension of Time...

  8. 78 FR 25253 - Seamless Carbon and Alloy Steel Standard, Line, and Pressure From the People's Republic of China...

    Science.gov (United States)

    2013-04-30

    ... International Trade Administration Seamless Carbon and Alloy Steel Standard, Line, and Pressure From the People... seamless carbon and alloy steel standard, line, and pressure pipe ] (``seamless pipe'') from the People's... Act of 1930, as amended, and 19 CFR 351.213(d)(4). Dated: April 22, 2013. Christian Marsh, Deputy...

  9. 76 FR 34044 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Extension of Time Limits for the Preliminary...

    Science.gov (United States)

    2011-06-10

    ... International Trade Administration Carbon and Certain Alloy Steel Wire Rod From Mexico: Extension of Time Limits... administrative review of the antidumping duty order on carbon and certain alloy steel wire rod from Mexico...) and 777(i)(1) of the Act. Dated: June 3, 2011. Christian Marsh, Deputy Assistant Secretary for...

  10. Bonding evolution with sintering temperature in low alloyed steels with chromium

    Directory of Open Access Journals (Sweden)

    Fuentes-Pacheco L.

    2009-01-01

    Full Text Available At present, high performance PM steels for automotive applications follow a processing route that comprises die compaction of water-atomized powder, followed by sintering and secondary treatments, and finishing operations. This study examines Cr-alloyed sintered steels with two level of alloying. In chromium-alloyed steels, the surface oxide on the powder is of critical importance for developing the bonding between the particles during sintering. Reduction of this oxide depends mainly on three factors: temperature, dew point of the atmosphere, and carbothermic reduction provided by the added graphite. The transformation of the initial surface oxide evolves sequence as temperature increases during sintering, depending on the oxide composition. Carbothermic reduction is supposed to be the controlling mechanism, even when sintering in hydrogen-containing atmospheres. The effect of carbothermic reduction can be monitored by investigating the behavior of the specimens under tensile testing, and studying the resultant fracture surfaces.

  11. Corrosion resistance of stainless steels and high Ni-Cr alloys to acid fluoride wastes

    Energy Technology Data Exchange (ETDEWEB)

    Smith, H.D.; Mackey, D.B.; Pool, K.H. (Pacific Northwest Lab., Richland, WA (United States)); Schwenk, E.B. (Westinghouse Hanford Co., Richland, WA (United States))

    1992-04-01

    TRUEX processing of Hanford Site waste will utilize potentially corrosive acid fluoride processing solutions. Appropriate construction materials for such a processing facility need to be identified. Toward this objective, candidate stainless steels and high Ni-Cr alloys have been corrosion tested in simulated acid fluoride process solutions at 333K. The high Ni-Cr alloys exhibited corrosion rates as low as 0.14 mm/y in a solution with an HF activity of about 1.2 M, much lower than the 19 to 94 mm/y observed for austenitic stainless steels. At a lower HF activity (about 0.008 M), stainless steels display delayed passivation while high Ni-Cr alloys display essentially no reaction.

  12. Characterization of Coatings on Steel Self-Piercing Rivets for Use with Magnesium Alloys

    Science.gov (United States)

    McCune, Robert C.; Forsmark, Joy H.; Upadhyay, Vinod; Battocchi, Dante

    Incorporation of magnesium alloys in self-pierce rivet (SPR) joints poses several unique challenges among which are the creation of spurious galvanic cells and aggravated corrosion of adjacent magnesium when coated steel rivets are employed. This work firstly reviews efforts on development of coatings to steel fasteners for the diminution of galvanic corrosion when used with magnesium alloys. Secondly, approaches, based on several electrochemical methods, for the measurement of the galvanic-limiting effect of a number of commercially-available coatings to hardened 10B37 steel self-piercing rivets inserted into alloy couples incorporating several grades of magnesium are reported. Electrochemical impedance spectroscopy (EIS), zero-resistance ammeter (ZRA), corrosion potential and potential-mapping visualization methods (e.g. scanning vibrating electrode technique — SVET) are illustrated for the several rivet coatings considered.

  13. Fracture performance of high strength steels, aluminium and magnesium alloys during plastic deformation

    Directory of Open Access Journals (Sweden)

    Yu Haiyan

    2015-01-01

    Full Text Available A series of uniaxial tension tests were performed for 5052 and 6061 aluminum alloys, AZ31B magnesium alloy, TRIP600 and DP600 steels, to obtain a better understanding of their fracture performance. Scanning electron microscope (SEM observation of the microstructure evolution was conducted. The dimple structure, orientation relationship between the fracture surface and tensile direction, necking behavior were analyzed. The fracture mechanism and fracture mode of each material was discussed in detail. The results show that TRIP600 steel is subject to a typical inter-granular ductile fracture combined by shear fracture. DP600 steel belongs to mainly ductility mixed with normal fracture. Both 5052 and 6061 aluminum alloys are subject to a mixed ductility fracture and brittle fracture. AA5052 and AA6061 belong to a typical shear fracture and a normal fracture, respectively. Magnesium AZ31B is typical of a brittle fracture combined with normal fracture.

  14. Assessment of special stainless steels and nickel-base alloys for use under offshore conditions

    Energy Technology Data Exchange (ETDEWEB)

    Jasner, M.R. [Krupp VDM GmbH, Duisburg (Germany); Herda, W.R. [Krupp VDM GmbH, Werdohl (Germany)

    1994-12-31

    Major offshore installations are designed for a 25-years` life span and more. To predict the corrosion behavior of various alloys for such a long period results from accelerated laboratory tests have to be verified by suitable field tests. The results from laboratory tests and exposure to natural seawater show that nickel-based alloys such as alloy 59 (UNS N06059) and alloy 31 (UNS N08031) can be employed to most severe conditions. For general applications 6Mo stainless steels with 25% Ni such as alloy 926 (UNS N08926) may be used. If higher strength is required alloy 24 (18 Ni-24.5 Cr-6.2 Mn-4.3 Mo-0.6 Cu-0.45 Mn) is the preferred material.

  15. Corrosion of martensitic steels in flowing 17Li83Pb alloy

    International Nuclear Information System (INIS)

    Flament, T.; Fauvet, P.; Hocde, B.; Sannier, J.

    1988-01-01

    Corrosion of three martensitic steels - 1.4914, HT9 and T91 - in the presence of flowing 17Li83Pb is investigated in thermal convection loops Tulip entirely made of 1.4914 steel. Two 3000-hour tests were performed at maximal temperatures of respectively 450 and 475 0 C with a δT of 60 0 C and an alloy velocity of about 0.08 m.s -1 . In both tests, corrosion is characterized by an homogeneous dissolution of the steel without formation of a corrosion layer. Corrosion rate is constant and very temperature dependent: the sound-metal loss of 1.4914 steel is 22 μm. year -1 at 450 0 C and 40 μm.year -1 at 475 0 C. Behaviours of 1.4914 and HT9 steels are very similar whereas T91 steel is about 20% less corroded

  16. Microstructure and phase identification in type 304 stainless steel-zirconium alloys

    International Nuclear Information System (INIS)

    Abraham, D.P.; McDeavitt, S.M.; Park, J.

    1996-01-01

    Stainless steel-zirconium alloys have been developed at Argonne National Laboratory to contain radioactive metal isotopes isolated from spent nuclear fuel. This article discusses the various phases that are formed in as-cast alloys of type 304 stainless steel and zirconium that contain up to 92 wt pct Zr. Microstructural characterization was performed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), and crystal structure information was obtained by X-ray diffraction. Type 304SS-Zr alloys with 5 and 10 wt pct Zr have a three-phase microstructure--austenite, ferrite, and the Laves intermetallic, Zr(Fe,Cr,Ni) 2+x , whereas alloys with 15, 20, and 30 wt pct Zr contain only two phases--ferrite and Zr(Fe,Cr,Ni) 2+x . Alloys with 45 to 67 wt pct Zr contain a mixture of Zr(Fe,Cr,Ni) 2+x and Zr 2 (Ni,Fe), whereas alloys with 83 and 92 wt pct Zr contain three phases--α-Zr, Zr 2 (Ni,Fe), and Zr(Fe,Cr,Ni) 2+x . Fe 3 Zr-type and Zr 3 Fe-type phases were not observed in the type 304SS-Zr alloys. The changes in alloy microstructure with zirconium content have been correlated to the Fe-Zr binary phase diagram

  17. Microstructure and corrosion behavior of shielded metal arc-welded dissimilar joints comprising duplex stainless steel and low alloy steel

    Science.gov (United States)

    Srinivasan, P. Bala; Muthupandi, V.; Sivan, V.; Srinivasan, P. Bala; Dietzel, W.

    2006-12-01

    This work describes the results of an investigation on a dissimilar weld joint comprising a boiler-grade low alloy steel and duplex stainless steel (DSS). Welds produced by shielded metal arc-welding with two different electrodes (an austenitic and a duplex grade) were examined for their microstructural features and properties. The welds were found to have overmatching mechanical properties. Although the general corrosion resistance of the weld metals was good, their pitting resistance was found to be inferior when compared with the DSS base material.

  18. Phase analysis of micro-alloyed steels using X-ray diffraction measurements

    International Nuclear Information System (INIS)

    Tobisch, J.; Kleinstueck, K.; Schatt, W.; Riehle, M.; Technische Univ., Dresden

    1977-01-01

    The applicability of neutron diffraction and X-ray diffraction to phase analyses of micro-alloyed steels is tested. The results show that the resolution of neutron reflexes was too low for quantitative statements. X-ray diffraction measurements of the reflex intensity permit quantitative analyses of the phase TiN, TiC, and Ti 4 C 2 S 2 in micro-alloyed steels without and after heat treatment. The values of the quantitative determination of these phases ranged from about 0.03 to 0.4 per cent by weight

  19. The mechanism of the surface alloy layer creation for cast steel

    Directory of Open Access Journals (Sweden)

    A. Walasek

    2012-01-01

    Full Text Available The paper presents a detailed description of the process of creation of a surface alloy layer (using high-carbon ferrochromium on the cast steel casting. The mechanism of the surface alloy layer is based on the known theories [5,6]. The proposed course of formation of the layers has been extended to decarburization stage of steel. The research included proving the presence of carbon-lean zone. The experiment included the analysis of the distribution of elements and microhardness measurement.

  20. Enhanced Densification of PM Steels by Liquid Phase Sintering with Boron-Containing Master Alloy

    Science.gov (United States)

    Vattur Sundaram, Maheswaran; Surreddi, Kumar Babu; Hryha, Eduard; Veiga, Angela; Berg, Sigurd; Castro, Fransisco; Nyborg, Lars

    2018-01-01

    Reaching high density in PM steels is important for high-performance applications. In this study, liquid phase sintering of PM steels by adding gas-atomized Ni-Mn-B master alloy was investigated for enhancing the density levels of Fe- and Mo- prealloyed steel powder compacts. The results indicated that liquid formation occurs in two stages, beginning with the master alloy melting (LP-1) below and eutectic phase formation (LP-2) above 1373 K (1100 °C). Mo and C addition revealed a significant influence on the LP-2 temperatures and hence on the final densification behavior and mechanical properties. Microstructural embrittlement occurs with the formation of continuous boride networks along the grain boundaries, and its severity increases with carbon addition, especially for 2.5 wt pct of master alloy content. Sintering behavior, along with liquid generation, microstructural characteristics, and mechanical testing revealed that the reduced master alloy content from 2.5 to 1.5 wt pct (reaching overall boron content from 0.2 to 0.12 wt pct) was necessary for obtaining good ductility with better mechanical properties. Sintering with Ni-Mn-B master alloy enables the sintering activation by liquid phase formation in two stages to attain high density in PM steels suitable for high-performance applications.

  1. Comparison of stainless steel and titanium alloy orthodontic miniscrew implants: a mechanical and histologic analysis.

    Science.gov (United States)

    Brown, Ryan N; Sexton, Brent E; Gabriel Chu, Tien-Min; Katona, Thomas R; Stewart, Kelton T; Kyung, Hee-Moon; Liu, Sean Shih-Yao

    2014-04-01

    The detailed mechanical and histologic properties of stainless steel miniscrew implants used for temporary orthodontic anchorage have not been assessed. Thus, the purpose of this study was to compare them with identically sized titanium alloy miniscrew implants. Forty-eight stainless steel and 48 titanium alloy miniscrew implants were inserted into the tibias of 12 rabbits. Insertion torque and primary stability were recorded. One hundred grams of tensile force was applied between half of the implants in each group, resulting in 4 subgroups of 24 specimens each. Fluorochrome labeling was administered at weeks 4 and 5. When the rabbits were euthanized at 6 weeks, stability and removal torque were measured in half (ie, 12 specimens) of each of the 4 subgroups. Microdamage burden and bone-to-implant contact ratio were quantified in the other 12 specimens in each subgroup. Mixed model analysis of variance was used for statistical analysis. All implants were stable at insertion and after 6 weeks. The only significant difference was the higher (9%) insertion torque for stainless steel. No significant differences were found between stainless steel and titanium alloy miniscrew implants in microdamage burden and bone-to-implant contact regardless of loading status. Stainless steel and titanium alloy miniscrew implants provide the same mechanical stability and similar histologic responses, suggesting that both are suitable for immediate orthodontic clinical loads. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  2. New metallurgical feasibilities in improvement of steel and alloy corrosion resistance

    International Nuclear Information System (INIS)

    Khasin, G.A.; Pokrovskij, A.B.; Krylov, S.M.; Leonovich, B.I.; Tomilov, V.I.

    1981-01-01

    New methods of the improvement of steel and alloy corrosion resistance are described. Some versions of technology of especially corrosion resistant steels melting in arc furnace with low carbon content are developed. One of such methods provides the complete decarburization of iron-nickel melt by oxygen-air mixture, the transition to the reduction period without the skimming of oxidation slag, ferrochromium melting at the expense of excess heat and the final reduction and refining of metal by inert gas blowing in the ladle. The 03Kh18N11, 03Kh18N12, 03Kh21N21M4GB, 03Kh17N14M3 and other steels are melted using this technology. Lately the melting technology of corrosion resistant and other alloyed steels and alloys with program thermo-time treatment of melts in arc and open induction furnaces is introduced. The method of phase equilibria calculation, which permits to estimate qualitatively and quantitatively the phases, formed in liquid metal during its solidification, and in solid metal, depending on temperature and composition of metal, is developed. Using the casting method, the production of corrosion resistant compositions with titanium carbides, is realized. Heat treatment and deformation methods of corrosion resistant steels and alloys are also discussed [ru

  3. Electrochemical assessment of some titanium and stainless steel impact dental alloys

    International Nuclear Information System (INIS)

    Echavarria, A.; Arroyave, C.

    2003-01-01

    Commercially pure titanium alloy, Ti-6Al-4V alloy and stainless steel screw implants were evaluated in both Ringer and synthetic saliva physiological solutions at body temperature by EIS (Electrochemical Impedance Spectroscopy) with immersion times of 30 d. Results were simulated as a sandwich system composed by four capacitors-resistances connected in series with the solution resistance. A model explaining the results in terms of the porosity and thickness of four different layers, was proposed. (Author) 22 refs

  4. Laser surface alloying of 316L stainless steel : different hardening routes and related microstructures

    OpenAIRE

    Laroudie, F.; Tassin, C.; Pons, M.

    1994-01-01

    The goal of this study is to investigate different hardening routes for 316L stainless steel by laser surface alloying. We have investigated the incorporation of hard submicronic particles of Tic, the precipitation of titanium carbide from mixtures of Ti and SiC and the formation of iron-chromium carbides by carbon incorporation. For each hardening route we present the microstructure and the hardness of the processed surface alloys and the conditions leading to the best compromise between hig...

  5. Special Features of Induction Annealing of Friction Stir Welded Joints of Medium-Alloy Steels

    Science.gov (United States)

    Priymak, E. Yu.; Stepanchukova, A. V.; Bashirova, E. V.; Fot, A. P.; Firsova, N. V.

    2018-01-01

    Welded joints of medium-alloy steels XJY750 and 40KhN2MA are studied in the initial condition and after different variants of annealing. Special features of the phase transformations occurring in the welded steels are determined. Optimum modes of annealing are recommended for the studied welded joints of drill pipes, which provide a high level of mechanical properties including the case of impact loading.

  6. Design of model alloys for martensitic/ferritic super heat-resistant 650 C steels

    Energy Technology Data Exchange (ETDEWEB)

    Knezevic, V.; Vilk, J.; Inden, G.; Sauthoff, G.; Agamennone, R.; Blum, W.

    2001-07-01

    The key to high creep strength of steels, besides solid solution strengthening, are fine distributions of stable precipitates which block the movement of subgrain boundaries and dislocations and delay coarsening of microstructure. The aim of the present study is to design new super heat-resistant 12%Cr ferritic steels using basic principles and concepts of physical metallurgy, to test and optimise model alloys and to investigate and clarify their behaviour under long-term creep conditions with emphasis on microstructural stability. Taking into consideration recent world-wide developments of 9-12%Cr steels with screening of available data, a series of model alloys is designed, which is supported by theoretical calculations and simulations of the expected phase transformations and precipitation processes. The alloys are prepared and tested mechanically. The effects of different types of precipitates as well as alloying elements on mechanical long-term properties are investigated. In particular the Laves phase is studied, which precipitates during service and which is to strengthen the alloys when M{sub 23}C{sub 6} precipitate particles besides finely distributed other carbides and nitrides become less effective. The effects of various austenite-forming alloying elements are also studied. (orig.)

  7. Study on Spheroidization and Related Heat Treatments of Medium Carbon Alloy Steels

    Directory of Open Access Journals (Sweden)

    Harisha S. R.

    2018-01-01

    Full Text Available The importance of medium carbon steels as engineering materials is reflected by the fact that out of the vast majority of engineering grade ferrous alloys available and used in the market today, a large proportion of them are from the family of medium carbon steels. Typically medium carbon steels have a carbon range of 0.25 to 0.65% by weight, and a manganese content ranging from 0.060 to 1.65% by weight. Medium carbon steels are more resistive to cutting, welding and forming as compared to low carbon steels. From the last two decades a number of research scholars reported the use of verity of heat treatments to tailor the properties of medium carbon steels. Spheroidizing is the novel industrial heat treatment employed to improve formability and machinability of medium/high carbon low alloy steels. This exclusive study covers procedure, the effects and possible outcomes of various heat treatments on medium carbon steels. In the present work, other related heat treatments like annealing and special treatments for property alterations which serve as pretreatments for spheroidizing are also reviewed. Medium carbon steels with property alterations by various heat treatment processes are finding increased responsiveness in transportation, aerospace, space, underwater along with other variegated fields. Improved tribological and mechanical properties consisting of impact resistance, stiffness, abrasion and strength are the main reasons for the increased attention of these steels in various industries. In the present scenario for the consolidation of important aspects of various heat treatments and effects on mechanical properties of medium carbons steel, a review of different research papers has been attempted. This review may be used as a guide to provide practical data for heat treatment industry, especially as a tool to enhance workability and tool life.

  8. A new approach to alloy compensation in a thickness measurement of high-tensile steel

    International Nuclear Information System (INIS)

    Lee, Jin Woo; Lee, Yun Jong; Kim, Chan Hyeong; Choi, Cheol Hee

    2013-06-01

    In on-line manufacturing iron-making process, several kinds of element are mixed in iron in order to meet the required quality for a final product. In this paper, the results show that the alloy compensation method is needed to improve accuracy required at thickness gauge, that is, ±0.5% at the target thickness. In addition, the alloy compensation method in measurement will be proposed in the form of correction function of each element weight percentage to be alloyed using the analyzed result of MCNP simulation program. Finally, an automatic thickness compensation method applied to the high-tensile steel product during manufacturing is introduced. (authors)

  9. Parallel between steels alloyed with chrome-nickel and Fe-Mn-Al-C steels, in their response to fracture and wear (Review)

    International Nuclear Information System (INIS)

    Ramos, J; Perez, G.A

    2008-01-01

    The big worldwide demand for chrome-nickel alloy steels ('conventional steel') leads to the need for advanced materials for applications in different engineering systems that operate at high temperatures and in aggressive environmental conditions, favoring research and development in alternate alloys. In this technological race in search of these new materials, the FeMnAlC alloys ('new steels') have attracted attention for their excellent mechanical and tribological properties as well as for their good performance in corrosive-oxide environments, which make them similar to conventional steel. There are two important similarities between these two steels. First, an agent that causes the passive film to become stainless appears in both steels: chrome in the conventional steel, and aluminum in the FeMnAl alloy. The second similarity is that a stabilizing agent of the austenitic phase (FCC) appears in both, so that excellent mechanical properties can be obtained: nickel in the conventional steel, and manganese in the FeMnAl alloy. In certain sectors, such as aeronautics, conventional steel is rarely used because it is a very heavy material. This conventional steel is almost three times heavier that aluminum (7.85/2.7). Two advantages that the new FeMnAIC steels have compared to the conventional steels are that they are about 13% lighter in weight and they are less expensive. The FeMnAl also have excellent mechanical properties and good corrosion-oxidation resistance, which generates big expectations for their application in a broad scientific spectrum. This work reports the state of the information currently available about FeMnAlC alloys, comparing the mechanical and tribological behaviors of conventional alloy steels with chrome and nickel alloys, specifying the scopes of their application. A condition that favors the steels' fragility is the high speed of deformation and impact, where the FCC crystalline structure materials do not have a fragile ductile transition

  10. The dependency of mechanical properties on the microstructure anisotropy index of some alloyed steels

    Science.gov (United States)

    Maisuradze, M. V.; Ryzhkov, M. A.

    2017-12-01

    The microstructure banding of the 4340, 42CrMo4 and 20NC11 alloyed steels is estimated using the approach of the ASTM E 1268 standard. The values of the anisotropy index and microhardness are obtained on the longitudinal specimens at various distances from the center of round steel bars with various diameters. Impact strength values in the transversal and longitudinal directions of the bars are obtained. The correlation of the anisotropy index values and the mechanical properties (microhardness and impact strength) of the steels under consideration is derived.

  11. Effects of LWR environments on fatigue life of carbon and low-alloy steels

    International Nuclear Information System (INIS)

    Chopra, O.K.; Shack, W.J.

    1995-03-01

    SME Boiler and Pressure Vessel Code provides construction of nuclear power plant components. Figure I-90 Appendix I to Section III of the Code specifies fatigue design curves for structural materials. While effects of environments are not explicitly addressed by the design curves, test data suggest that the Code fatigue curves may not always be adequate in coolant environments. This paper reports the results of recent fatigue tests that examine the effects of steel type, strain rate, dissolved oxygen level, strain range, loading waveform, and surface morphology on the fatigue life of A 106-Gr B carbon steel and A533-Gr B low-alloy steel in water

  12. Influence of microstructure of high-strength low-alloy steels on their weldability

    International Nuclear Information System (INIS)

    Cwiek, J.; Labanowski, J.

    2003-01-01

    Microstructure of steel before welding has influence on the steel's susceptibility to cold cracking because it influences hardenability and maximum hardness of heat affected zone (HAZ). Two high-strength low-alloy (HSLA) steel grades 18G2AV and 14HNMBCu, in various heat treatment conditions, were subjected to simulated welding thermal cycles. It was revealed that maximum HAZ hardness is influenced by microstructure presented before thermal cycle was applied. The higher HAZ hardness was observed for quenched and tempered condition, comparing to full annealed and overheated conditions. (author)

  13. Interim fatigue design curves for carbon, low-alloy, and austenitic stainless steels in LWR environments

    International Nuclear Information System (INIS)

    Majumdar, S.; Chopra, O.K.; Shack, W.J.

    1993-01-01

    Both temperature and oxygen affect fatigue life; at the very low dissolved-oxygen levels in PWRs and BWRs with hydrogen water chemistry, environmental effects on fatigue life are modest at all temperatures (T) and strain rates. Between 0.1 and 0.2 ppM, the effect of dissolved-oxygen increases rapidly. In oxygenated environments, fatigue life depends strongly on strain rate and T. A fracture mechanics model is developed for predicting fatigue lives, and interim environmentally assisted cracking (EAC)-adjusted fatigue curves are proposed for carbon steels, low-alloy steels, and austenitic stainless steels

  14. Corrosion of steels in molten gallium (Ga), tin (Sn) and tin lithium alloy (Sn–20Li)

    International Nuclear Information System (INIS)

    Kondo, Masatoshi; Ishii, Masaomi; Muroga, Takeo

    2015-01-01

    Graphical abstract: Corrosion of RAFM steel, JLF-1, in liquid Sn–20Li was caused by the formation of Fe-Sn alloyed layer. - Highlights: • The corrosion tests were performed for the reduced activation ferritic martensitic steel JLF-1 and the austenitic steel SUS316 in liquid Ga, Sn and Sn-20Li at 873 K up to 750 h. • The weight loss of the specimens exposed to liquid Ga, Sn and Sn-20Li was evaluated. • The corrosion of the steels in liquid Ga was caused by the alloying reaction between Ga and Fe on the steel surface. • The corrosion of the steels in liquid Sn was caused by the alloying reaction between Sn and Fe on the steel surface. • The corrosion of the steels in liquid Sn-20Li was caused by the formation of the Fe-Sn alloyed layer and the diffusion of Sn and Li into the steel matrix. - Abstract: The compatibility of steels in liquid gallium (Ga), tin (Sn) and tin lithium alloy (Sn–20Li) was investigated by means of static corrosion tests. The corrosion tests were performed for reduced activation ferritic martensitic steel JLF-1 (JOYO-HEAT, Fe–9Cr–2W–0.1C) and austenitic steel SUS316 (Fe–18Cr–12Ni–2Mo). The test temperature was 873 K, and the exposure time was 250 and 750 h. The corrosion of these steels in liquid Ga, Sn and Sn–20Li alloy was commonly caused by the formation of a reaction layer and the dissolution of the steel elements into the melts. The reaction layer formed in liquid Ga was identified as Fe 3 Ga from the results of metallurgical analysis and the phase diagram. The growth rate of the reaction layer on the JLF-1 steel showed a parabolic rate law, and this trend indicated that the corrosion could be controlled by the diffusion process through the layer. The reaction layer formed in liquid Sn and Sn–20Li was identified as FeSn. The growth rate had a linear function with exposure time. The corrosion in Sn and Sn–20Li could be controlled by the interface reaction on the layer. The growth rate of the layer formed in

  15. Corrosion Behavior of New Cr-Ni-Cu Low Alloy Seawater Corrosion Resistant Steel

    Science.gov (United States)

    Zhang, Piaopiao; Yang, Zhongmin; Chen, Ying; Wang, Huimin

    Two kinds of Cr-Ni-Cu low alloyed steels were designed, 0.1%C-0.7%Cr-1.2%Ni-0.7Cu and 0.1%C-0.7%Cr-0.3%Ni-0.5Cu. With the method of SEM, XRD and electrochemical analysis and testing technology, periodic immersion accelerated corrosion test was carried out to investigate the corrosion resistance of the designed steels in simulated marine environment. The steel with best corrosion resistance was selected, and then focused on the variation of its corrosion rate with time. The results indicated that the designed Cu-Cr-Ni low alloyed steels showed better corrosion resistance than 20MnSi, the ratio of their corrosion rates was 0.44. The corrosion rate of designed steels decreased gradually to 3 4 g/(mm2·h) with the elongation of test period, while the corrosion rate of 20MnSi kept downward trend, not reach stability, and the corrosion rate gap between them became smaller. The Cr element banding enriched in the inner rust can withstand the diffusion of Cl-. Besides, the addition of Ni raised the self-corrosion potential of the bare steels and promoted the transformation of γ-FeOOH to α-FeOOH, and consequently, improved the stability of the rust and the corrosion resistance of steels.

  16. Characterization of Desulfovibrio desulfuricans biofilm on high-alloyed stainless steel: XPS and electrochemical studies

    Energy Technology Data Exchange (ETDEWEB)

    Dec, Weronika [Institute of Industrial Organic Chemistry, Branch Pszczyna, Doświadczalna Street 27, 43-200 Pszczyna (Poland); Mosiałek, Michał; Socha, Robert P. [Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek Street 8, 30-239 Kraków (Poland); Jaworska-Kik, Marzena [Department of Biopharmacy, Medical University of Silesia, Jedności Street 8, 41-200 Sosnowiec (Poland); Simka, Wojciech [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego 6 Street, 44-100 Gliwice (Poland); Michalska, Joanna, E-mail: joanna.k.michalska@polsl.pl [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego 6 Street, 44-100 Gliwice (Poland)

    2017-07-01

    Results on D. desulfuricans biofilm formation on austenitic-ferritic duplex (2205 DSS) and superaustenitic (904L) stainless steels are presented. Surface characterization including the structure, configuration and chemical composition of biofilms were carried out using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical impedance spectroscopy (EIS) measurements were used to monitor the attachment activity of bacteria on the steels' surface and to determine the effect of bacteria on passivity. It was proved that investigated steels are rapidly colonized by bacteria. The presence of biofilm caused significant ennoblement of 904L steel surface, while retarded the attainment of high passive state of 2205 DSS. XPS analysis revealed significant sulphidation of the biofilm and its layered structure. Accumulation of sulphides and hydroxides was proved in the outermost layer, while the increasing contents of disulphides, organometallic and C-N bonds were detected in the internal part of the biofilm. Irreversible bondings between steel matrix and biofilm had also been observed. - Highlights: • High-alloyed steels are rapidly colonized by sulphate-reducing bacteria. • Higher Ni content stimulates more intensive biofilm growth. • Extracellular polymeric substances indelibly bind to the high-alloyed steels. • Sulphate-reducing bacteria caused irreversible sulphidation of passive films.

  17. Microstructures and properties of low-alloy fire resistant steel

    Indian Academy of Sciences (India)

    Unknown

    Report 66 29. Ho C Y, Powell R W and Liley P E 1975 Thermal conductivity of the elements: A comprehensive review (NewYork: AIP). Honeycombe R W K 1981 Steel microstructure and properties. (London: Edward Arnold; Ohio : ASM). Houdremont E 1953 Handbook of special steels (Berlin: Springer Verlag) 1. Irvine K J ...

  18. Laser Overlap Welding of Zinc-coated Steel on Aluminum Alloy

    Science.gov (United States)

    Kashani, Hamed Tasalloti; Kah, Paul; Martikainen, Jukka

    Local reinforcement of aluminum with laser welded patches of zinc-coated steel can effectively contribute to crashworthiness, durability and weight reduction of car body. However, the weld between Zn-coated steel and aluminum is commonly susceptible to defects such as spatter, cavity and crack. The vaporization of Zn is commonly known as the main source of instability in the weld pool and cavity formation, especially in a lap joint configuration. Cracks are mainly due to the brittle intermetallic compounds growing at the weld interface of aluminum and steel. This study provides a review on the main metallurgical and mechanical concerns regarding laser overlap welding of Zn-coated steel on Al-alloy and the methods used by researchers to avoid the weld defects related to the vaporization of Zn and the poor metallurgical compatibility between steel and aluminum.

  19. Behavior of the elements in the mechanically alloyed and cast ferritic steels and a type 316 stainless steel in a flowing sodium environment

    International Nuclear Information System (INIS)

    Suzuki, T.; Mutoh, I.

    1988-01-01

    Sodium corrosion behavior of a mechanically alloyed ferritic steel, dispersion-strengthened with addition of Y 2 0 3 and Ti, two kinds of melted/cast ferritic steels and a Type 316 stainless steel was examined by using a non-isothermal sodium loop system, constructed of another Type 316 stainless steel, with a direct resistance electrical heater. The sodium conditions were 675 0 C, 4.0 m/s in velocity and 1-2 ppm oxygen concentration and a cumulative exposure time of the specimens was about 3000 h. The absorption of Ni and selective dissolution of Cr played an important role in the corrosion of the mechanically alloyed ferritic steel as in the case of the cast ferritic steels. However, the region of Ni absorption and Cr diminution was deeper than that of the cast ferritic steels. Peculiar finding for the mechanically alloyed ferritic steel was the corroded surface with irregularly shaped protuberance, that might be related with formation of sodium titanate, and the absorption of carbon and nitrogen to form carbide and nitride of titanium. It seems that these facts resulted in the irregular weight loss of the specimens, which depended on the downstream position and the cumulative exposure time. However, the tensile properties of the mechanically alloyed ferritic steel did not noticeably change by the sodium exposure

  20. Study made of corrosion resistance of stainless steel and nickel alloys in nuclear reactor superheaters

    Science.gov (United States)

    Greenberg, S.; Hart, R. K.; Lee, R. H.; Ruther, W. E.; Schlueter, R. R.

    1967-01-01

    Experiments performed under conditions found in nuclear reactor superheaters determine the corrosion rate of stainless steel and nickel alloys used in them. Electropolishing was the primary surface treatment before the corrosion test. Corrosion is determined by weight loss of specimens after defilming.

  1. Practical measurement of silicon in low alloy steels by differential pulse stripping voltammetry

    International Nuclear Information System (INIS)

    Rahier, A.; Lunardi, S.; Triki, C.

    2005-01-01

    A sensitive differential pulse anodic stripping voltammetry has been adapted to allow the determination of Si in low-alloy steels using a hanging mercury drop electrode. The method has been qualified using certified ASTM standards and is now running in routine. The present report describes the experimental details, thereby allowing the reader to carry out the measurements precisely. (author)

  2. Use of steel and tantalum apparatus for molten Cd-Mg-Zn alloys

    Science.gov (United States)

    Bennett, G. A.; Burris, L., Jr.; Kyle, M. L.; Nelson, P. A.

    1966-01-01

    Steel and tantalum apparatus contains various ternary alloys of cadmium, zinc, and magnesium used in pyrochemical processes for the recovery of uranium-base reactor fuels. These materials exhibit good corrosion resistance at the high temperatures necessary for fuel separation in liquid metal-molten salt solvents.

  3. Laser surface alloying of 316L stainless steel with Ru and Ni mixtures

    CSIR Research Space (South Africa)

    Lekala, MB

    2012-05-01

    Full Text Available The surfaces of AISI 316L stainless steel were laser alloyed with ruthenium powder and a mixture of ruthenium and nickel powders using a cw Nd:YAG laser set at fixed operating parameters. The microstructure, elemental composition, and corrosion...

  4. Corrosion resistance of Zn-Co-Fe alloy coatings on high strength steel

    NARCIS (Netherlands)

    Lodhi, Z.F.; Mol, J.M.C.; Hovestad, A.; Hoen-Velterop, L. 't; Terryn, H.; Wit, J.H.W.de

    2009-01-01

    The corrosion properties of electrodeposited zinc-cobalt-iron (Zn-Co-Fe) alloys (up to 40 wt.% Co and 1 wt.% Fe) on steel were studied by using various electrochemical techniques and compared with zinc (Zn) and cadmium (Cd) coatings in 3.5% NaCl solution. It was found that with an increase in Co

  5. Inverse Processing of Undefined Complex Shape Parts from Structural High Alloyed Tool Steel

    Czech Academy of Sciences Publication Activity Database

    Monková, K.; Monka, P.; Hloch, Sergej

    -, č. 1 (2014), s. 1-11 ISSN 1687-8132 Institutional support: RVO:68145535 Keywords : 3D digitization * complex shape parts * high alloyed tool steel Subject RIV: JQ - Machines ; Tools Impact factor: 0.575, year: 2014 http://www.hindawi.com/journals/ame/aip/478748/

  6. Microstructural aspects of phosphorus grain boundary segregation in low alloy steels

    Czech Academy of Sciences Publication Activity Database

    Perháčová, J.; Grman, D.; Svoboda, Milan; Patscheider, J.; Výrostková, A.; Janovec, J.

    2001-01-01

    Roč. 47, č. 1 (2001), s. 44-49 ISSN 0167-577X Grant - others:VEGA(SK) 2/5161/98 Institutional research plan: CEZ:AV0Z2041904 Keywords : microstructure * grain boundary segregation * low alloy steel Subject RIV: JG - Metallurgy Impact factor: 0.670, year: 2001

  7. Long term ground support with stainless steel and nickel alloy rock bolts

    International Nuclear Information System (INIS)

    Shaffer, T.F.; Revie, R.W.; Mandal, A.

    1994-01-01

    Stainless steel and nickel alloy Swellex rock bolts have been developed to provide long-term ground support in corrosive environments or in underground openings that are inaccessible for periodic reconditioning. Laboratory and underground testing has shown that the mechanical properties of stainless steel Swellex rock bolts am adequate for long term service. The corrosivity of underground sites may vary considerably and no one grade of stainless steel will provide adequate corrosion resistance economically for permanent service at all sites. Six stainless steels and two nickel alloys have been evaluated and used to manufacture Swellex. These alloys can be used to manufacture all types of rock bolts including mechanically anchored bolts. The selection of the lowest-cost corrosion-resistant alloy suitable for the lifetime objective at a given site may be problematic. Therefore, a mine corrosivity assessment procedure, in which the performance of several candidate materials for permanent service at a specific site can be determined quickly and economically, is being developed and will be available in 1995

  8. The Effect of Microstructure on the Abrasion Resistance of Low Alloyed Steels

    NARCIS (Netherlands)

    Xu, X.

    2016-01-01

    The thesis attempts to develop advanced high abrasion resistant steels with low hardness in combination with good toughness, processability and low alloying additions. For this purpose, a novel multi-pass dual-indenter (MPDI) scratch test approach has been developed to approach the real continuous

  9. Galvanic Corrosion of Mg-Zr Alloy and Steel or Graphite in Mineral Binders

    Science.gov (United States)

    Lambertin, David; Rooses, Adrien; Frizon, Fabien

    The dismantling of UNGG nuclear reactor generates numerous nuclear wastes such as fuel decanning commonly composed of Mg-Zr alloy. A conditioning strategy consists in encapsulating these wastes into a hydraulic binder in a suitable state for storage. The eventual presence of steel and graphite accompanying the magnesium wastes could imply corrosion by galvanic coupling. This work is an experimental investigation of the galvanic coupling between Mg-Zr alloy and steel or graphite using ZRA electrochemical method in Portland cement or geopolymer pastes. The lowest corrosion activity of magnesium alloy while coupled to graphite or steel cathode has been observed in geopolymer pastes. Indeed, in this binder, an efficient corrosion protection of the magnesium alloy maintains the galvanic current very low during all the hardening process. In geopolymer paste, current densities of anodised Mg-Zr alloy is not dependent of the cathode/anode surface ratio in the range of 0.1 to 5 due to the dominance of the anode resistance.

  10. Passivation of Cu-Zn alloy on low carbon steel electrodeposited from a pyrophosphate medium

    Science.gov (United States)

    Yavuz, Abdulcabbar; Yakup Hacıibrahimoğlu, M.; Bedir, Metin

    2018-01-01

    The motivation of this study is to understand whether zinc-based alloy also has a passivation behaviour similar to zinc itself. Cu-Zn alloys were electrodeposited potentiostatically from a pyrophosphate medium on a carbon steel electrode and their corrosion behaviours were studied. Pt and carbon steel electrodes were used in order to examine the corrosion/passivation behaviour of bare Cu, bare Zn and Cu-Zn alloy coatings. The passivation behaviour of all brass-modified electrodes having Zn content between 10% and 100% was investigated. The growth potential affects the morphology and structure of crystals. The brass coatings are more porous than their pure components. The crystalline structure of Cu-Zn alloys can be obtained by changing the deposition potential. The zinc content in brass increases when the deposition voltage applied decreases. However, the growth potential and the ratio of zinc in brass do not affect the passivation behaviour of the resulting alloys. The coatings obtained by applying different growth potentials were immersed in tap water for 24 h to compare their corrosion behaviours with carbon steel having pitting formation.

  11. Effect of Mechanical Alloying Atmospheres and Oxygen Concentration on Mechanical Properties of ODS Ferritic Steels

    International Nuclear Information System (INIS)

    Noh, Sanghoon; Choi, Byoungkwon; Han, Changhee; Kim, Kibaik; Kang, Sukhoon; Chun, Youngbum; Kim, Taekyu

    2013-01-01

    Finely dispersed nano-oxide particles with a high number density in the homogeneous grain matrix are essential to achieve superior mechanical properties at high temperatures, and these unique microstructures can be obtained through the mechanical alloying (MA) and hot consolidation process. The microstructure and mechanical property of ODS steel significantly depends on its powder property and the purity after the MA process. These contents should be carefully controlled to improve the mechanical property at elevated temperature. In particular, appropriate the control of oxygen concentration improves the mechanical property of ODS steel at high temperature. An effective method is to control the mechanical alloying atmosphere by high purity inert gas. In the present study, the effects of mechanical alloying atmospheres and oxygen concentration on the mechanical property of ODS steel were investigated. ODS ferritic alloys were fabricated in various atmospheres, and the HIP process was used to investigate the effects of MA atmospheres and oxygen concentration on the microstructure and mechanical property. ODS ferritic alloys milled in an Ar-H 2 mixture, and He is effective to reduce the excess oxygen concentration. The YH 2 addition made an extremely reduced oxygen concentration by the internal oxygen reduction reaction and resulted in a homogeneous microstructure and superior creep strength

  12. Influence of Processing and Heat Treatment on Corrosion Resistance and Properties of High Alloyed Steel Coatings

    Science.gov (United States)

    Hill, Horst; Weber, Sebastian; Raab, Ulrich; Theisen, Werner; Wagner, Lothar

    2012-09-01

    Corrosion and abrasive wear are two important aspects to be considered in numerous engineering applications. Looking at steels, high-chromium high-carbon tool steels are proper and cost-efficient materials. They can either be put into service as bulk materials or used as comparatively thin coatings to protect lower alloyed construction or heat treatable steels from wear and corrosion. In this study, two different corrosion resistant tool steels were used for the production of coatings and bulk material. They were processed by thermal spraying and super solidus liquid phase sintering as both processes can generally be applied to produce coatings on low alloyed substrates. Thermally sprayed (high velocity oxygen fuel) coatings were investigated in the as-processed state, which is the most commonly used condition for technical applications, and after a quenching and tempering treatment. In comparison, sintered steels were analyzed in the quenched and tempered condition only. Significant influence of alloy chemistry, processing route, and heat treatment on tribological properties was found. Experimental investigations were supported by computational thermodynamics aiming at an improvement of tribological and corrosive resistance.

  13. Mechanical properties and oxidation and corrosion resistance of reduced-chromium 304 stainless steel alloys

    Science.gov (United States)

    Stephens, J. R.; Barrett, C. A.; Gyorgak, C. A.

    1979-01-01

    An experimental program was undertaken to identify effective substitutes for part of the Cr in 304 stainless steel as a method of conserving the strategic element Cr. Although special emphasis was placed on tensile properties, oxidation and corrosion resistance were also examined. Results indicate that over the temperature range of -196 C to 540 C the yield stress of experimental austenitic alloys with only 12 percent Cr compare favorably with the 18 percent Cr in 304 stainless steel. Oxidation resistance and in most cases corrosion resistance for the experimental alloys were comparable to the commercial alloy. Effective substitutes for Cr included Al, Mo, Si, Ti, and V, while Ni and Mn contents were increased to maintain an austenitic structure.

  14. Nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel and stainless steel alloys

    Energy Technology Data Exchange (ETDEWEB)

    Moore, D.G.; Sorensen, N.R.

    1998-02-01

    This report presents a nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel alloys from stainless steel alloys as well as an evaluation of cleaning techniques to remove a thermal oxide layer on aircraft exhaust components. The results of this assessment are presented in terms of how effective each technique classifies a known exhaust material. Results indicate that either inspection technique can separate inconel and stainless steel alloys. Based on the experiments conducted, the electrochemical spot test is the optimum for use by airframe and powerplant mechanics. A spot test procedure is proposed for incorporation into the Federal Aviation Administration Advisory Circular 65-9A Airframe & Powerplant Mechanic - General Handbook. 3 refs., 70 figs., 7 tabs.

  15. Perspective on present and future alloy development efforts on austenitic stainless steels for fusion application

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, P.J.

    1984-01-01

    The purpose of this paper is to address important questions concerning how to effect further alloy development of austenitic stainless steels for resistance, and to what extent the behavior of other properties under irradiation, such as strength/embrittlement, fatigue/irradiation creep, corrosion (under irradiation), and radiation-induced activation must be influenced. To summarize current understanding, helium has been found to have major effects on swelling and embrittlement, but several metallurgical avenues are available for significant improvement relative to type 316 stainless steel. Studies on fatigue and irradiation creep, particularly including helium effects, are preliminary but have yet to reveal engineering problems requiring additional alloy development remedies. The effects of irradiation on corrosion behavior are unknown, but higher alloy nickel contents make thermal corrosion in lithium worse. 67 refs. (JDB)

  16. Simultaneous Co-deposition of Zn-Mg Alloy Layers on Steel Strip by PVD Process

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Yeob [POSCO Technical Research Laboratories, Gwangyang (Korea, Republic of); Goodenough, Mark [Strategic Marketing, Tata Steel, Warwickshire (United Kingdom)

    2011-12-15

    This is the first release of an interim report on the development of coating technology of Zn-Mg alloy layers on steel strip by EML-PVD (electromagnetic levitation - physical vapor deposition) process in an air-to-air type continuous PVD pilot plant. It intends to introduce a basic principle of the EML-PVD process together with the high speed PVD pilot plant built in Posco. Due to the agitation effect provided by the high frequency induction coil, simultaneous evaporation of Zn and Mg from a droplet could produce alloy coating layers with Mg content of 6% to 12% depending on the composition of the droplet inside the coil. For its superior corrosion resistance, Zn-Mg alloy coated steel would be a very promising material for automotive, electrical appliances, and construction applications.

  17. Simultaneous Co-deposition of Zn-Mg Alloy Layers on Steel Strip by PVD Process

    International Nuclear Information System (INIS)

    Kim, Tae Yeob; Goodenough, Mark

    2011-01-01

    This is the first release of an interim report on the development of coating technology of Zn-Mg alloy layers on steel strip by EML-PVD (electromagnetic levitation - physical vapor deposition) process in an air-to-air type continuous PVD pilot plant. It intends to introduce a basic principle of the EML-PVD process together with the high speed PVD pilot plant built in Posco. Due to the agitation effect provided by the high frequency induction coil, simultaneous evaporation of Zn and Mg from a droplet could produce alloy coating layers with Mg content of 6% to 12% depending on the composition of the droplet inside the coil. For its superior corrosion resistance, Zn-Mg alloy coated steel would be a very promising material for automotive, electrical appliances, and construction applications

  18. Perspective on present and future alloy development efforts on austenitic stainless steels for fusion application

    International Nuclear Information System (INIS)

    Maziasz, P.J.

    1984-01-01

    The purpose of this paper is to address important questions concerning how to effect further alloy development of austenitic stainless steels for resistance, and to what extent the behavior of other properties under irradiation, such as strength/embrittlement, fatigue/irradiation creep, corrosion (under irradiation), and radiation-induced activation must be influenced. To summarize current understanding, helium has been found to have major effects on swelling and embrittlement, but several metallurgical avenues are available for significant improvement relative to type 316 stainless steel. Studies on fatigue and irradiation creep, particularly including helium effects, are preliminary but have yet to reveal engineering problems requiring additional alloy development remedies. The effects of irradiation on corrosion behavior are unknown, but higher alloy nickel contents make thermal corrosion in lithium worse. 67 refs

  19. Investigation of models to predict the corrosion of steels in flowing liquid lead alloys

    International Nuclear Information System (INIS)

    Balbaud-Celerier, F.; Barbier, F.

    2001-01-01

    Corrosion of steels exposed to flowing liquid lead alloys can be affected by hydrodynamic parameters. The rotating cylinder system is of interest for the practical evaluation of the fluid velocity effect on corrosion and for the prediction of the corrosion behavior in other geometries. Models developed in aqueous medium are tested in the case of liquid metal environments. It is shown that equations established for the rotating cylinder and the pipe flow geometry can be used effectively in liquid lead alloys (Pb-17Li) assuming the corrosion process is mass transfer controlled and the diffusion coefficient of dissolved species is known. The corrosion rate of martensitic steels in Pb-17Li is shown to be independent of the geometry when plotted as a function of the mass transfer coefficient. Predictions about the corrosion of steel in liquid Pb-Bi are performed but experiments are needed to validate the results obtained by modeling

  20. Adsorption and inhibitive properties of Tryptophan on low alloy steel corrosion in acidic media

    Directory of Open Access Journals (Sweden)

    Hesham T.M. Abdel-Fatah

    2017-02-01

    Corrosion inhibition was studied using electrochemical methods (electrochemical impedance spectroscopy; EIS and the new technique electrochemical frequency modulation; EFM and weight loss measurements. The influence of inhibitor concentration, solution temperature, and immersion time on the corrosion resistance of low alloy steel (LAS has been investigated. Trp proved to be a very good inhibitor for low alloy steel acid corrosion. EFM measurements showed that Trp is a mixed type inhibitor. Trp behaved better in 0.6 M HCl than in 0.6 M HSO3NH2. Moreover, it was found that the inhibition efficiency increased with increasing inhibitor concentration, while a decrease was detected with the rise of temperature and immersion time. The associated activation energy (Ea has been determined. The values of Ea indicate that the type of adsorption of Trp on the steel surface in both acids belongs to physical adsorption. The adsorption process was tested using Temkin adsorption isotherm.

  1. Martensitic/ferritic super heat-resistant 650 C steels - design of model alloys

    Energy Technology Data Exchange (ETDEWEB)

    Knezevic, V.; Sauthoff, G. [Max-Planck-Inst. fuer Eisenforschung GmbH, Duesseldorf (Germany)

    2002-07-01

    Tempered martensitic/ferritic 9-12%Cr steels are now recognized to be the most potential materials for 650 C ultra super critical (USC) Power Plants. The degradation of long-term creep strength, as a result of microstructural changes during long-term exposure at the elevated temperature, is the main problem for this group of steels. Therefore, to achieve sufficient creep resistance during the entire service life it is necessary to stabilize the microstructure by alloying with elements which provide enough solid solution and precipitation strengthening and slow down diffusion. The aim of the present study is to investigate the effect of different types of precipitates as well as alloying elements on mechanical long-term properties of new ferritic 12%Cr steels. Fine distributions of stable precipitates which block the movement of subgrain boundaries (M{sub 23}C{sub 6} carbides, Laves phase) and dislocations (MX carbonitrides) and delay coarsening of microstructure is the key to high creep strength of such steels. Furthermore, additional Laves phase, which precipitates during service, is to strengthen the alloys when M{sub 23}C{sub 6} particles become less effective. Addition of Co is to achieve an initially 100% martensitic microstructure and moreover to slow down diffusion processes and consequently coarsening of particles. The partial substitution of Co by Cu and Mn is also investigated to reduce costs. The first results of mechanical tests of the studied model alloys have shown positive effects of the addition of W as Laves phase forming element, as well as of the MX forming elements Ta and Ti. Alloying with Co has also shown beneficial effects on the creep strength of model alloys. Further optimisation of composition and microstructure is in progress. (orig.)

  2. Diffusion Bonding Behavior and Characterization of Joints Made Between 316L Stainless Steel Alloy and AZ31 Magnesium Alloy

    Science.gov (United States)

    Elthalabawy, Waled Mohamed

    The 316L austenitic stainless steel and AZ31 magnesium alloy have physical and mechanical properties which makes these alloys suitable in a number of high technology based industries such as the aerospace and automotive sectors. However, for these alloys to be used in engineering applications, components must be fabricated and joined successfully. The differences in the physical and metallurgical properties between these two alloys prevents the use of conventional fusion welding processes commonly employed in aerospace and transport industry. Therefore, alternative techniques need to be developed and diffusion bonding technology is a process that has considerable potential to join these two dissimilar alloys. In this research work both solid-state and transient liquid phase (TLP) bonding processes were applied. The solid-state bonding of 316L steel to AZ31 magnesium alloy was possible at a bonding temperature of 550°C for 120 minutes using a pressure of 1.3 MPa. The interface characterization of the joint showed a thin intermetallic zone rich in Fe-Al was responsible for providing a metallurgical bond. However, low joint shear strengths were recorded and this was attributed to the poor surface to surface contact. The macro-deformation of the AZ31 alloy prevented the use of higher bonding pressures and longer bonding times. In order to overcome these problems, the TLP bonding process was implemented using pure Cu and Ni foils as interlayers which produced a eutectic phase at the bonding temperature. This research identified the bonding mechanism through microstructural and differential scanning calorimetry investigations. The microstructural characterization of the TLP joints identified intermetallics which became concentrated along the 316L steel/AZ31 bond interface due to the "pushing effect" of the solid/liquid interface during isothermal solidification stage of bonding. The size and concentration of the intermetallics had a noticeable effect on the final joint

  3. Investigation of fretting corrosion of vacuum-chrome-plated vt3-1 titanium alloy in pair with unprotected vt3-1 alloy and 40khnma steel

    International Nuclear Information System (INIS)

    Rojkh, I.L.; Koltunova, L.N.; Vejtsman, M.G.; Birman, Ya.N.; Skosarev, A.V.; Kogan, I.S.

    1978-01-01

    The character of destruction of contacting surfaces in the process of fretting corrosion of titanium alloy VT3-1 chromized in vacuum in pair with unprotected alloy VT3-1 and steel 40KhNMA has been studied by scanning electron microscopy, electronography, and recording the surface profile. The specific load was 200 kg/cm 2 , vibration amplitude 50 mkm and frequency 500 Hz. It has been established that pairs unprotected with coating are subjected to intensive fretting corrosion especially when they are made of titanium alloy. For the pair chromized alloy VT3-1 - unprotected alloy VT3-1 no destruction of a chromized surface is observed. Vacuum chromium coating in the pair with steel 40KhNMA reveals similar properties as in pair with a titanium alloy. The surface of a steel sample is destroyed because of fretting corrosion, though the intensity of corrosion is lower than in the case of unprotected pairs. Vacuum chromium coating is recommended for protection of titanium alloy VT3-1 from fretting corrosion in pair with steel 40KhNMA or an alloy VT3-1 especially in those cases when various organic coatings are unsuitable

  4. Microstructural characterization of superaustenitic stainless steel surface alloys formed using laser treatment

    Science.gov (United States)

    Sridhar, K.; Deshmukh, M. B.; Khanna, A. S.; Gasser, A.

    2000-09-01

    Conventional stainless steels (SS’s) such as AISI type 304 SS are used in many industrial applications due to their excellent weldability and good mechanical properties. However, in contacts with chlorides, they suffer from localized corrosion. AISI type 304 SS was alloyed at the surface with chromium, nickel, and molybdenum using a CO2 laser carried under varying laser processing parameters. The objective is to create a surface alloy with composition and microstructure, suitable for marine environments. The surface alloys were characterized using optical microscopy and scanning electron microscopy (SEM) and revealed the presence of the austenitic phase. Analysis by SEM-energy dispersive analysis (EDAX) revealed good compositional homogeneity with molybdenum contents in the range of 3 to 15 wt.%. The dendrite arm spacing (DAS) measured at the surface and bottom of the surface alloy using an image analyzer was found to be in good correlation with calculated cooling rates.

  5. Influence of nitrogen alloying on hydrogen embrittlement in AISI 304-type stainless steels

    Science.gov (United States)

    Hannula, Simo-Pekka; Hänninen, Hannu; Tähtinen, Seppo

    1984-12-01

    Hydrogen embrittlement of AISI 304-type austenitic stainless steels has been studied with special emphasis on the effects of the nitrogen content of the steels. Hydrogen charging was found to degrade the mechanical properties of all the steels studied, as measured by a tensile test. The fracture surfaces of hydrogen charged specimens were brittle cleavage-like whereas the uncharged specimens showed ductile, dimpled fracture. In sensitized materials transgranular cleavage mode of fracture was replaced by an intergranular mode of fracture and the losses of mechanical properties were higher. Nitrogen alloying decreased the hydrogen-induced losses of mechanical properties by increasing the stability of austenite. In sensitized steels the stability of austenite and nitrogen content were found to have only a minor effect on hydrogen embrittlement, except when sensitization had caused α'-martensite transformation at the grain boundaries.

  6. Fe-Mn-Si master alloy steel by powder metallurgy processing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zongyin; Sandstroem, Rolf

    2004-01-28

    Fe-Mn-Si master alloy powders were produced by three methods: milling, atomising, and a combination of atomisation and milling. The effects of sintering temperature, time and atmosphere on the properties of sintered steels with these Fe-Mn-Si master alloy powders were studied. The density of the compacts increases with sintering temperature and time. The ultimate tensile strength and hardness increases with sintering temperature and time mainly due to increasing amounts of bainite and martensite after cooling. Elongation is initially raised with sintering temperature and time probably due to improved bonding between powder particles. The compacts with the milled and atomised-milled master alloy showed about the same mechanical properties. On the other hand, the steel with the atomised powder gave lower strength and elongation in both hydrogen and argon-5% hydrogen. Small dimensional changes have been obtained in the steels with milled and atomised-milled Fe-Mn-Si master alloys sintered at 1200 deg. C. It was shown that transient liquid phase sintering accelerates the sintering process, which leads to improved mechanical properties.

  7. Nitride alloy layer formation of duplex stainless steel using nitriding process

    Science.gov (United States)

    Maleque, M. A.; Lailatul, P. H.; Fathaen, A. A.; Norinsan, K.; Haider, J.

    2018-01-01

    Duplex stainless steel (DSS) shows a good corrosion resistance as well as the mechanical properties. However, DSS performance decrease as it works under aggressive environment and at high temperature. At the mentioned environment, the DSS become susceptible to wear failure. Surface modification is the favourable technique to widen the application of duplex stainless steel and improve the wear resistance and its hardness properties. Therefore, the main aim of this work is to nitride alloy layer on the surface of duplex stainless steel by the nitriding process temperature of 400°C and 450°C at different time and ammonia composition using a horizontal tube furnace. The scanning electron microscopy and x-ray diffraction analyzer are used to analyse the morphology, composition and the nitrided alloy layer for treated DSS. The micro hardnesss Vickers tester was used to measure hardness on cross-sectional area of nitrided DSS. After nitriding, it was observed that the hardness performance increased until 1100 Hv0.5kgf compared to substrate material of 250 Hv0.5kgf. The thickness layer of nitride alloy also increased from 5μm until 100μm due to diffusion of nitrogen on the surface of DSS. The x-ray diffraction results showed that the nitride layer consists of iron nitride, expanded austenite and chromium nitride. It can be concluded that nitride alloy layer can be produced via nitriding process using tube furnace with significant improvement of microstructural and hardness properties.

  8. Study on fatigue resistance of low alloy steels with Mo and Cr

    Science.gov (United States)

    Enculescu, E.; Chicet, D. L.; Dia, V.; Stanciu, S.

    2016-08-01

    This paper presents, based on a case study, the analysis of the factors that influence the mechanical cyclic fatigue resistance of two grades of low alloy steel with Mo and Cr. It was studied the fatigue behavior in real operating conditions of some active elements manufactured from the two low-alloyed steel grades, elements that are equipping some farm implements. Using the fractographic analysis, optical microscopy and scanning electron microscopy, were analyzed the samples that carried away because of the fatigue fracture. On samples taken from the two brands of low alloy steels with Mo and Cr were performed tempering thermal treatments that modified the structure, in order to improve the operating characteristics. The effect of those thermal treatments was initially observed by microstructural analysis of metallographic prepared samples (by polishing and chemical attack using nital reagent), that revealed a troostite type structure. On the heat-treated samples were determined a number of mechanical properties: hardness, impact strength and tensile test. There was observed an improvement of the impact bending strength for both alloys and a tensile behavior that favors increasing resistance to fatigue.

  9. Mechanical properties and microstructures of the welded union of steel micro-alloyed to niobium

    International Nuclear Information System (INIS)

    Bejar-Gomez, L; Medina-Flores, A; Bedolla-Jacuinde, A; Alfonso, I; Saavedra, M

    2006-01-01

    Experimental structural steel was used for this work, produced by welding and thermo-mechanical treatment, micro-alloyed with niobium and developed for structural applications. Its carbon content was 0.06 and niobium 0.03 weight %. This material was welded by electrical arc and manually by coated electrode, since it is a widely used application. The chemical composition of the steel, its resistance, the selection of the supporting material, and the position of the welding were taken into consideration. The welded union includes all the parts involved with the welding such as the welding metal or support, the thermally affected zone and the base material with no affects. The metallurgy for each part is associated with the type of material, with the welding process applied and with its procedure. This work analyzes the mechanical properties of the welded union of a steel micro-alloyed with niobium, and also studies the microstructure of the union in the sediment metal, in the thermally affected zone and in the base material. The importance of this work lies in establishing the facility or difficulty of an experimental steel micro-alloyed with niobium, containing 0.06% carbon, to avoid outlining or cracking in the welded union. Another basic aspect was to valuate the mechanical properties of the base metal and of the sediment, reinforcing the study with an analysis of the hardness profiles and of the microstructures found in the parts of the welded union (CW)

  10. Evaluation of microstructural difference in low alloy steel (SA508 CI.3) by magnetic measurements

    International Nuclear Information System (INIS)

    Chi, Se Hwan; Park, Duck Gun; Hong, Jun Hwa; Kuk, Il Hium; Song, Sook Hyang; Shur, Dong Soo

    1997-01-01

    Magnetic measurements on SA 508 Cl. 3 low alloy reactor pressure vessel (RPV) steels of three different refining processes were conducted to prepare baseline magnetic properties for future comparison with that of irradiated one and to examine the correlation between microstructures and magnetic parameters. TEM(transmission electron microscopy) on thin films and carbon replications were performed for microstructural investigation, and microhardness, tensile and fracture toughness tests were conducted for mechanical properties measurement. Barkhausen noise analysis was conducted and hysteresis parameters were measured. Microstructure, mechanist and magnetic properties were interpreted together to explore their inter-relationship. Also the applicability of a magnetic nondestructive evaluation method for monitoring fine microstructural changes in low alloy steels of complicated microstructure was examined. The results showed that, of all magnetic parameters, Barkhausen noise amplitudes show consistent change with microstructure (grain size, carbide microstructure, lath width) and hardness of the materials. For monitoring microstructural and mechanical property changes of low alloy steel under service environment of reactor pressure vessel steels, Barkhausen noise amplitude and coercivity appear to be as key magnetic parameters useful for nondestructive evaluation.

  11. Zr/ZrC modified layer formed on AISI 440B stainless steel by plasma Zr-alloying

    Energy Technology Data Exchange (ETDEWEB)

    Shen, H.H.; Liu, L.; Liu, X.Z.; Guo, Q.; Meng, T.X.; Wang, Z.X.; Yang, H.J.; Liu, X.P., E-mail: liuxiaoping@tyut.edu.cn

    2016-12-01

    Highlights: • A Zr/ZrC modified layer was formed on AISI 440B stainless steel using plasma surface Zr-alloying. • The thickness of the modified layer increases with alloying temperature and time. • Formation mechanism of the modified layer is dependent on the mutual diffusion of Zr and substrate elements. • The modified surface shows an improved wear resistance. - Abstract: The surface Zr/ZrC gradient alloying layer was prepared by double glow plasma surface alloying technique to increase the surface hardness and wear resistance of AISI 440B stainless steel. The microstructure of the Zr/ZrC alloying layer formed at different alloying temperatures and times as well as its formation mechanism were discussed by using scanning electron microscopy, glow discharge optical emission spectrum, X-ray diffraction and X-ray photoelectron spectroscopy. The adhesive strength, hardness and tribological property of the Zr/ZrC alloying layer were also evaluated in the paper. The alloying surface consists of the Zr-top layer and ZrC-subsurface layer which adheres strongly to the AISI 440B steel substrate. The thickness of the Zr/ZrC alloying layer increases gradually from 16 μm to 23 μm with alloying temperature elevated from 900 °C to 1000 °C. With alloying time from 0.5 h to 4 h, the alloyed depth increases from 3 μm to 30 μm, and the ZrC-rich alloyed thickness vs time is basically parabola at temperature of 1000 °C. Both the hardness and wear resistance of the Zr/ZrC alloying layer obviously increase compared with untreated AISI 440B steel.

  12. Replacement of steel parts with extruded aluminum alloys in an automobile

    Science.gov (United States)

    Daggula, Manikantha Reddy

    Over the past years, vehicle emissions have shown a negative impact on environment and human health. A new strategy has been used by automakers to reduce a vehicle's weight which significantly reduce fuel consumption and C02 emissions. A very light car consumes very less fuel as it needs to overcome less inertia, decreasing the required power to movie the vehicle. Reducing weight is the easiest way to increase fuel economy and making it by just 10% can increase its efficiency 6 to 8 percent. For a normal scale 80% of vehicles weight is shared among chassis, power train and other exterior components. Almost 60% of the vehicles weight is comprised of steel and the remaining is with cast and extruded aluminum and magnesium alloys. Our main aim is to look for the parts like Fuel tank holder, Fuel filler neck, Turbo inlet assembly, and Brake lines, Dash board frame which are made from steel and replace them with extruded aluminum alloys, to analyze a conventional rear wheel aluminum drive shaft and replace it with a new design and with a new aluminum alloy. The current project involves dismantling an automobile and looking for feasible steel parts and making samples, analyzing the hardness of the samples. These parts are optimally analyzed using Ansys Finite element analysis tool, these parts are subjected to the constraints such as three-point bending, tensile testing, hydrostatic pressure and also torsional stress action on the drive shaft, the deformation and stress are observed in these parts. The results show the current steel parts can be replaced with 3000 series aluminum alloy and the drive shaft can be replaced with new design with 6061-T6 Al-alloy which decreases 25% of the shaft weight.

  13. Nitrogen alloying of the 12% Cr martensitic-ferritic steel

    Science.gov (United States)

    Kudryavtsev, A. S.; Artem'eva, D. A.; Mikhailov, M. S.

    2017-08-01

    The influence of the nitrogen content on the structure and mechanical properties of heat and corrosion resistant 12% Cr martensitic-ferritic steel developed at the Central Research Institute of Structural Materials Prometey has been studied. Steel containing 0.061 wt % nitrogen possesses a high level of mechanical properties. The decrease in the nitrogen content to 0.017 wt % leads to an increase of structurally free ferrite fraction in the steel, a decrease in the density of dislocations, a decrease of structural dispersity and the absence of finely dispersed precipitates of niobium and vanadium nitrides and carbides. As a result, there is a decrease in the strength properties, especially in the heat resistance.

  14. Microscopy of Alloy Formation on Arc Plasma Sintered Oxide Dispersion Strengthen (ODS) Steel

    Science.gov (United States)

    Bandriyana, B.; Sujatno, A.; Salam, R.; Dimyati, A.; Untoro, P.

    2017-07-01

    The oxide dispersed strengthened (ODS) alloys steel developed as structure material for nuclear power plants (NPP) has good resistant against creep due to their unique microstructure. Microscopy investigation on the microstructure formation during alloying process especially at the early stages was carried out to study the correlation between structure and property of ODS alloys. This was possible thanks to the arc plasma sintering (APS) device which can simulate the time dependent alloying processes. The ODS sample with composition of 88 wt.% Fe and 12 wt.% Cr powder dispersed with 1 wt.% ZrO2 nano powder was mixed in a high energy milling, isostatic compressed to form sample coins and then alloyed in APS. The Scanning Electron Microscope (SEM) with X-ray Diffraction Spectroscopy (EDX) line scan and mapping was used to characterize the microstructure and elemental composition distribution of the samples. The alloying process with unification of each Fe and Cr phase continued by the alloying formation of Fe-Cr by inter-diffusion of both Fe and Cr and followed by the improvement of the mechanical properties of hardness.

  15. Braze alloy process and strength characterization studies for 18 nickel grade 200 maraging steel with application to wind tunnel models

    Science.gov (United States)

    Bradshaw, James F.; Sandefur, Paul G., Jr.; Young, Clarence P., Jr.

    1991-01-01

    A comprehensive study of braze alloy selection process and strength characterization with application to wind tunnel models is presented. The applications for this study include the installation of stainless steel pressure tubing in model airfoil sections make of 18 Ni 200 grade maraging steel and the joining of wing structural components by brazing. Acceptable braze alloys for these applications are identified along with process, thermal braze cycle data, and thermal management procedures. Shear specimens are used to evaluate comparative shear strength properties for the various alloys at both room and cryogenic (-300 F) temperatures and include the effects of electroless nickel plating. Nickel plating was found to significantly enhance both the wetability and strength properties for the various braze alloys studied. The data are provided for use in selecting braze alloys for use with 18 Ni grade 200 steel in the design of wind tunnel models to be tested in an ambient or cryogenic environment.

  16. Quantitative consideration for the tempering effect during multi-pass thermal cycle in HAZ of low-alloy steel

    International Nuclear Information System (INIS)

    Yu, Lina; Nakabayashi, Yuma; Saida, Kazuyoshi; Mochizuki, Masahito; Nishimoto, Kazutoshi; Kameyama, Masashi; Hirano, Shinro; Chigusa, Naoki

    2011-01-01

    A new Thermal Cycle Tempering Parameter (TCTP) to deal with the tempering effect during multi-pass thermal cycles has been proposed by extending Larson-Miller parameter (LMP). Experimental result revealed that the hardness in synthetic HAZ of the low alloy steel subjected to multi tempering thermal cycles has a good linear relationship with TCTP. By using this relationship, the hardness of the low-alloy steel reheated with tempering thermal cycles can be predicted when the original hardness is known. (author)

  17. Viscosity and plasticity rise and reduction of anisotropy of low-alloy steel properties

    International Nuclear Information System (INIS)

    Matrosov, Yu.I.; Polyakov, I.E.

    1976-01-01

    Based on the published data, consideration is given to the possibilities of upgrading the toughness and plastic properties of low-alloy structural steels (16GS, 09G20S, 18G2, etc.) through the reduction in carbon and detrimental impurity (including sulphur) contents and also by treating the steels with the elements which are active with respect to sulphur (rare-earth metals, titanium, zirconium) and provide for the modifying action on sulphide inclusions. Drawing the impact strength properties on lateral samples nearer to those on longitudinal samples may be very favourable to the higher reliability of the structural components [ru

  18. Local thermal expansions and lattice strains in Elinvar and stainless steel alloys

    Science.gov (United States)

    Yokoyama, Toshihiko; Koide, Akihiro; Uemura, Yohei

    2018-02-01

    Local thermal expansions and lattice strains in the Elinvar alloy Fe49.66Ni42.38Cr5.49Ti2.47 (Ni Span C) and the stainless steel SUS304 Fe71.98Ni9.07Cr18.09Mn0.86 (AISI304) were investigated by the temperature-dependent Cr, Fe, and Ni K -edge extended x-ray absorption fine-structure (EXAFS) measurements, combined with the path-integral effective classical potential Monte Carlo (PIECP MC) theoretical simulations. From the EXAFS analysis of the Elinvar alloy, the local thermal expansion around Fe is found to be considerably smaller than the ones around Ni and Cr. This observation can be understood simply because Fe in the Elinvar alloy exhibit an incomplete Invar-like effect. Moreover, in both the Elinvar and SUS304 alloys, the local thermal expansions and the lattice strains around Cr are found to be larger than those around Fe and Ni. From the PIECP MC simulations of both the alloys, the first-nearest neighbor Cr-Fe pair shows extraordinarily large thermal expansion, while the Cr-Cr pair exhibits quite small or even negative thermal expansion. These findings consequently indicate that the lattice strains in both the Elinvar and SUS304 alloys are concentrated predominantly on the Cr atoms. Although the role of Cr in stainless steel has been known to inhibit corrosion by the formation of surface chromium oxide, the present investigation may interestingly suggest that the Cr atoms in the bulk play a hidden new role of absorbing inevitable lattice strains in the alloys.

  19. Literature Survey on the Stress Corrosion Cracking of Low-Alloy Steels in High Temperature Water

    International Nuclear Information System (INIS)

    Seifert, H.P.

    2002-02-01

    The present report is a summary of a literature survey on the stress corrosion cracking (SCC) behaviour/ mechanisms in low-alloy steels (LAS) in high-temperature water with special emphasis to primary-pressure-boundary components of boiling water reactors (BWR). A brief overview on the current state of knowledge concerning SCC of low-alloy reactor pressure vessel and piping steels under BWR conditions is given. After a short introduction on general aspects of SCC, the main influence parameter and available quantitative literature data concerning SCC of LAS in high-temperature water are discussed on a phenomenological basis followed by a summary of the most popular SCC models for this corrosion system. The BWR operating experience and service cracking incidents are discussed with respect to the existing laboratory data and background knowledge. Finally, the most important open questions and topics for further experimental investigations are outlined. (author)

  20. The influence of deep cryogenic treatment on the properties of high-vanadium alloy steel

    Energy Technology Data Exchange (ETDEWEB)

    Li, Haizhi [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Tong, Weiping, E-mail: wptong@mail.neu.edu.cn [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Cui, Junjun [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Zhang, Hui [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Chen, Liqing [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Zuo, Liang [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China)

    2016-04-26

    Deep cryogenic treatment can improve the mechanical properties of many metallic materials, but there are few reports of the effect of deep cryogenic treatment on high-vanadium alloy steel. The main objective of this work is to investigate the effect of deep cryogenic treatment on the microstructure, hardness, impact toughness and abrasive wear resistance of high-vanadium alloy steel. The results show that large amounts of small secondary carbide precipitation after deep cryogenic treatment and microcracks were detected and occurred preferentially at carbide/matrix interfaces; except for the hardness, the mechanical properties increased compared to those of the conventional treatment sample. By increasing the deep cryogenic processing time and cycle number, impact toughness and abrasive wear resistance can be further improved, the carbide contents continuously increase, and the hardness decreases.

  1. Investigation of attenuation coefficients of some stainless steel and aluminum alloys

    Science.gov (United States)

    Caner, Zafer; Tufan, Mustafa ćaǧatay

    2018-02-01

    In this study, attenuation coefficients of two different stainless steel alloys (AISI 304 and AISI 310), which have a wide range of applications from home appliances to the automotive sector, and two different aluminum alloys (6013 and 5083), which have a high mechanical strength and a light weight structure and are used in many fields from aviation to military vehicles, has been determined. For this purpose, we used gamma spectrometer system with NaI(Tl) detector. In our measurements, we used Eu-152, Ra-226 and Co-60 as gamma ray sources. To narrow the beam of gamma rays, we designed the new steel based collimator. We also investigated the effect of using collimator. Obtained results were compared with the NIST XCOM values.

  2. Microstructural characterization of atom clusters in irradiated pressure vessel steels and model alloys

    International Nuclear Information System (INIS)

    Auger, P.; Pareige, P.; Akamatsu, M.; Van Duysen, J.C.

    1993-01-01

    In order to characterize the microstructural evolution of iron solid solution under irradiation, two pressure vessel steels irradiated in service conditions, and, for comparison, low copper model alloys irradiated with neutrons and electrons, have been studied through small angle neutron scattering and atom probe experiments. In Fe-Cu model alloys, copper clusters are formed containing uncertain proportions of iron. In the low copper industrial steels, the feature is more complex; solute atoms such as Ni, Mn and Si, sometimes associated with Cu, segregate as ''clouds'' more or less condensed in the iron solid solution. These silicides, or at least Si, Ni, Mn association, may facilitate the copper segregation although the initial iron matrix contains a low copper concentration. (authors). 24 refs., 3 figs., 2 tabs

  3. Characterization of atom clusters in irradiated pressure vessel steels and model alloys

    International Nuclear Information System (INIS)

    Auger, P.; Pareige, P.; Akamatsu, M.; Van Duysen, J.C.

    1993-12-01

    In order to characterize the microstructural evolution of the iron solid solution under irradiation, two pressure vessel steels irradiated in service conditions and, for comparison, low copper model alloys irradiated with neutrons and electrons have been studied. The characterization has been carried out mainly thanks to small angle neutron scattering and atom probe experiments. Both techniques lead to the conclusion that clusters develop with irradiations. In Fe-Cu model alloys, copper clusters are formed containing uncertain proportions of iron. In the low copper industrial steels, the feature is more complex. Solute atoms like Ni, Mn and Si, sometimes associated with Cu, segregate as ''clouds'' more or less condensed in the iron solid solution. These silicides, or at least Si, Ni, Mn association, may facilitate the copper segregation although the initial iron matrix contains a low copper concentration. (authors). 24 refs., 3 figs., 2 tabs

  4. Laser fusion-brazing of aluminum alloy to galvanized steel with pure Al filler powder

    Science.gov (United States)

    Liu, Jia; Jiang, Shichun; Shi, Yan; Kuang, Yulin; Huang, Genzhe; Zhang, Hong

    2015-03-01

    The fusion-brazing connection of the dissimilar metal 5052 aluminum alloy/ST07Z steel was achieved by using the Nd:YAG laser with pure Al filler powder, and the effects of the laser power and powder feeding speed on the formation and mechanical properties of the resultant joints were investigated. The experimental results show that melting-brazing connection of 5052 aluminum alloy/galvanized steel can be successfully achieved, and the zinc plating layer has played the role of flux, assuring the brazing properties. The intermetallic compound layer was generated on the welded brazing interface. The joint exhibited a shear strength of 174 N/mm if the thickness of the intermetallic layer at the interface is about 6-7 μm.

  5. Corrosion studies on Cu-Ni alloys and ferritic steel in salt water for desalination service

    International Nuclear Information System (INIS)

    Shibad, P.R.; Balachandra, J.

    1975-01-01

    Corrosion studies on In 838 and In 848 alloys in 3% NaCl solution, synthetic sea water and in 3% NaCl at pH3 and pH10 indicate that the latter alloy is more corrosion resistant than the former at room (28 0 C), and boiling temperature (101 0 C) and at 125 0 C. Ferritic steel is unaffected in boiling synthetic sea water. In boiling 3% NaCl solution at pH3 and pH10, (the pH values adjusted at room temperature) increase in the rate of corrosion of ferritic steel compared to that at room temperature has been observed. A fair correlation between polarization characteristics and dissolution rates in these solutions is seen for all these materials. (author)

  6. Evaluation of High Temperature Corrosion Resistance of Finned Tubes Made of Austenitic Steel And Nickel Alloys

    Directory of Open Access Journals (Sweden)

    Turowska A.

    2016-06-01

    Full Text Available The purpose of the paper was to evaluate the resistance to high temperature corrosion of laser welded joints of finned tubes made of austenitic steel (304,304H and nickel alloys (Inconel 600, Inconel 625. The scope of the paper covered the performance of corrosion resistance tests in the atmosphere of simulated exhaust gases of the following chemical composition: 0.2% HCl, 0.08% SO2, 9.0% O2 and N2 in the temperature of 800°C for 1000 hours. One found out that both tubes made of austenitic steel and those made of nickel alloy displayed good resistance to corrosion and could be applied in the energy industry.

  7. Thermal shock induced crack arrest of two low alloy steels

    International Nuclear Information System (INIS)

    Di Fant, M.; Genty, A.; Pineau, A.

    1990-01-01

    Tests were performed on a C-Mn-Nb steel (E36) and a C-Mn-Ni-Mo steel (A508) to determine the fracture toughness either at crack initiation, K Ic , or at crack arrest, K Ia , under a very severe thermal shock such as rupture of a PWR primary coolant circuit. Experiments were carried out either on small discs (thickness 19 mm) or on larger cylinders (height: 220 mm) with an inner diameter of 46 or 50 mm and an external diameter of 150 mm. Finite element method calculations were performed to determine the variations of the hoop stress and those of the stress intensity factor across the wall thickness. Results obtained on both materials are given. It is shown that the BEREMIN model for cleavage fracture takes well account of crack initiation and size effect [fr

  8. Gas bubbles evolution peculiarities in ferritic-martensitic and austenitic steels and alloys under helium-ion irradiation

    NARCIS (Netherlands)

    Chernov, [No Value; Kalashnikov, AN; Kahn, BA; Binyukova, SY

    2003-01-01

    Transmission electron microscopy has been used to investigate the gas bubble evolution in model alloys of the Fe C system, ferritic-martensitic steels of 13Cr type, nickel and austenitic steels under 40-keV helium-ion it. radiation up to a fluence of 5 x 10(20) m(-2) at the temperature of 920 K. It

  9. Spot welding of aluminium alloy sheets to coated steel sheets. Kakushu mekki koban to arumi gokin no spot yosetsusei

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, S.; Fukumura, K.; Soga, S. (Nisshin Steel Co. Ltd., Tokyo (Japan))

    1994-03-31

    Welding aluminum alloy sheets with coated steel sheets has become used frequently in association with weight reduction in automobiles. This paper describes investigations on the effects of spot welding aluminum alloy sheets with different kinds of coated steel sheets on optimal welding conditions and weld strength. An AC single-phase spot welding machine was used for an experiment using an aluminum alloy(5052)with a thickness of 1 mm(referred to as A)and different coated steel sheets with a thickness of 0.8 mm(referred to as B). The result may be summarized as follows: the weldable value of the electric current is closer to that for between the B steel sheets than the middle of that for between the As and between Bs; while the weldable current range is affected little by the coating materials when a CF electrode is used, it grows greater in aluminum coated steel sheets and hot-dip galvanized steel sheets than in alloyed hot-dip galvanized steel sheets and cold-rolled steel sheets when an R-type electrode is used; influence of the coating materials was observed in tensile shear strength and cross tensile shear strength; and any combination of metals shows fatigue strength lower than that in the A-A combination in a fatigue test of cross tensile system. 5 refs., 12 figs., 6 tabs.

  10. Innovative Technology of Mechanized Wet Underwater Welding of High-Alloy Corrosion Resistant Steel

    Directory of Open Access Journals (Sweden)

    Kakhovskyi, M.Yu.

    2015-07-01

    Full Text Available The results of the practice of welding-repair technology using self-shielded flux-cored wire for wet underwater welding of high-alloy stainless steels type 18-10 are presented. The application of the technology allows reducing human participation in welding process under the extreme conditions. The practical value of the technology consists in the possibility of welding-repair works directly under water without any additional assembly works.

  11. Corrosion behaviour of AISI 316L stainless-steel alloys in diabetic serum.

    Science.gov (United States)

    Moura e Silva, T; Monteiro, J M; Ferreira, M G; Vieira, J M

    1993-01-01

    The present study investigates the pitting-corrosion behaviour of AISI 316L stainless steel in human physiological fluids. The emphasis is on the effect of diabetic serum with glucose and proteins, but reference solutions of isotonic saline solution with and without antibiotics were also used. Polarization experiments were carried out, and the results point to the innocuity of those fluids on the performance of the alloy as far as pitting corrosion is concerned.

  12. Atom probe tomography reveals options for microstructural design of steels and titanium alloys by segregation engineering

    Directory of Open Access Journals (Sweden)

    Raabe D.

    2015-01-01

    Full Text Available Here we discuss approaches for designing microstructures in steels and titanium alloys by manipulating the segregation content and the structural state of lattice defects. Different mechanisms can be utilized in that context, such as for instance site specific segregation as described by the Gibbs isotherm and the generalized defectant concept, confined phase transformation phenomena and the formation of complexions, i.e. confined chemical and structural states at lattice defects.

  13. Fracture toughness of welded joints of a high strength low alloy steel

    International Nuclear Information System (INIS)

    Veiga, S.M.B. da; Bastian, F.L.; Pope, A.M.

    1985-10-01

    The fracture toughness of the different regions of welded joints of a high strength low alloy steel, Niocor 2, was evaluated at different temperatures and compared with the toughness of the base metal. The studied regions were: the weld metal, fusion boundary and heat affected zone. The welding process used was the manual metal arc. It is shown that the weld metal region has the highest toughness values. (Author) [pt

  14. Crack growth behavior of low-alloy bainitic 51CrV4 steel

    OpenAIRE

    Canadinç, Demircan; Lambers, H. G.; Gorny B.; Tschumak, S.; Maier, H.J.

    2010-01-01

    The crack growth behavior of low-alloy bainitic 51CrV4 steel was investigated. The current results indicate that the stress state present during the isothermal bainitic transformation has a strong influence on the crack propagation behavior in the near threshold regime, when the crack growth direction is perpendicular to the loading axis of the original sample undergoing phase transformation. However, the influence of stresses superimposed during the bainitic transformation on the crack growt...

  15. Welding of Nb micro-alloyed steel by the submerged arc process using Brazilian consumables

    International Nuclear Information System (INIS)

    Scotti, A.; Quites, A.M.

    1982-01-01

    A set of procedures was established for welding of Nb micro-alloyed steel by the submerged arc process, using national consumables, in order to simultaneously achieve a more economic welding and better mechanical properties. From all the wire-flux combinations the better were the correspondent to AWS F84ED1, F74EM12K and F84EH14, the last being the best. (Author) [pt

  16. The Use of Barium and Calcium Alloys in the Ladle Furnace Treatment of Selected Grades of Continuously Cast Steels

    Directory of Open Access Journals (Sweden)

    Derda W.

    2015-04-01

    Full Text Available The subject of the paper are the results of laboratory and industrial investigations into the use of Si - Ca - Ba alloys for modifying non-metallic inclusions. Based on laboratory tests, the morphology and chemical composition of non-metallic inclusions in carbon steel were examined before and after refining with the use of the above-mentioned alloy as a refining addition. In particular tests, variable additions of the alloy were used at a constant refining time and temperature.

  17. Analysis of impact-sliding wear property of aluminum bronze against titanium alloy and 2Cr13 steel

    Science.gov (United States)

    Wei, Yongqiang; Wang, Liqin

    2009-07-01

    Impact-sliding wear of aluminum bronze against titanium alloy and 2Cr13 steel have been conducted using impactsliding wear test rig which was developed independently. Some non-destructive examinations have been performed on worn specimens, using weighing, 2D and 3D profilometry, scanning electron microscopy and EDS technology. Using laser scanning confocal microscope (LSCM), it has been found that the surface of aluminum bronze which wears against titanium alloy is much coarser than the surface which wears against 2Cr13 steel. Results of wear volume show clearly that although the hardness of titanium alloy has greater value than aluminum bronze, the wear volume of titanium alloy has much greater value compared with aluminum bronze. It has been found that there is remarkable material transferring from titanium alloy to aluminum bronze and little material transfer from aluminum bronze to titanium alloy. For the impact-sliding wear between aluminum bronze against 2Cr13 steel, the hardness of aluminum bronze has greater value than 2Cr13 steel, the wear volume of aluminum bronze has much greater value compared with 2Cr13 steel, whose wear volume can be ignored. Using EDS technology, it has been found that there is material transferring from aluminum bronze to 2Cr13 steel and material transferring from 2Cr13 steel to aluminum bronze can be ignored. Through the SEM pictures of worn surfaces and worn debris, flaking, particles and micro-cracks can be found on the worn surfaces. The wear mechanism of aluminum bronze against titanium alloy and 2Cr13 steel is delamination wear.

  18. X-ray photoelectron spectroscopy characterization of high dose carbon-implanted steel and titanium alloys

    Science.gov (United States)

    Viviente, J. L.; García, A.; Alonso, F.; Braceras, I.; Oñate, J. I.

    1999-04-01

    A study has been made of the depth dependence of the atomic fraction and chemical bonding states of AISI 440C martensitic stainless steel and Ti-6Al-4V alloy implanted with 75 keV C + at very high doses (above 10 18 ions cm -2), by means of X-ray photoelectron spectroscopy combined with an Ar + sputtering. A Gaussian-like carbon distribution was observed on both materials at the lowest implanted dose. More trapezoidal carbon depth-profiles were found with increasing implanted doses, and a pure carbon layer was observed only on the titanium alloy implanted at the highest dose. The implanted carbon was combined with both base metal and carbon itself to form metallic carbides and graphitic carbon. Furthermore, carbon-enriched carbides were also found by curve fitting the C 1s spectra. The titanium alloy showed a higher carbidic contribution than the steel implanted at the same C + doses. A critical carbon concentrations of about 33 at.% and 23 at.% were measured for the formation of C-C bonds in Ti-6Al-4V and steel samples, respectively. The carbon atoms were bound with metal to form carbidic compounds until these critical concentrations were reached; when this C concentration was exceeded the proportion of C-C bonds increased and resulted in the growth of carbonaceous layers.

  19. Influence of MAO Treatment on the Galvanic Corrosion Between Aluminum Alloy and 316L Steel

    Science.gov (United States)

    Yang, Yuanhang; Gu, Yanhong; Zhang, Lei; Jiao, Xiangdong; Che, Juntie

    2017-12-01

    To slow down the galvanic corrosion of aluminum alloy and 316L stainless steel in subsea water, a micro-arc oxidation (MAO) coating was prepared on the surface of the Al alloy, and no treatment was performed on the surface of the 316L. The surface morphology of MAO-coated Al alloy was evaluated using a scanning electron microscope (SEM) before and after corrosion. A micro-hardness tester was used to measure the micro-hardness. Corrosion behaviors were evaluated by open-circuit potential (OCP), potentiodynamic polarization (PDP) and electrode impedance spectroscopy (EIS) tests in a 3.5 g/L NaCl solution. The results of PDP testing show that the corrosion potential of the MAO-coated galvanic pair was more positive than that of the uncoated galvanic pair and that the corrosion current density was smaller than that of the uncoated galvanic pair. EIS results show that the impedance of the galvanic pair increased after MAO coating. SEM images show that the corrosion damage of the uncoated Al alloy was more severe than that of the MAO-coated one, and the post-corrosion images of the surface of the 316L connected with MAO-coated Al alloy were more compact than those of the 316L connected with uncoated Al alloy. A physical model was developed to discuss the influence of MAO treatment on the galvanic corrosion process and corrosion mechanism.

  20. Alloy 31, a new 6 moly stainless steel with improved corrosion resistance in seawater

    Energy Technology Data Exchange (ETDEWEB)

    Jasner, M.; Heubner, U. [Krupp VDM GmbH, Werdohl (Germany)

    1995-10-01

    Alloy 31--UNS N08031--31Ni-27Cr-6.5Mo-1.2Cu-0.2N-balance iron--is an advanced 6 Mo stainless steel with increased chromium and nickel, contents for seawater service. In hot seawater the pitting potential of alloy 31 remains high up to 90 C (194 F). Investigations of resistance to crevice corrosion in real piping systems in natural seawater, both North Sea and Baltic Sea, show that the threshold conditions for alloy 31 in chlorinated seawater (North Sea) are at 40 C and 1 ppm chlorine well superior to the 6 Mo stainless grades being currently in use. In addition, alloy 31 shows an excellent resistance to corrosion versus both hot reducing media (e.g. H{sub 2}SO{sub 4}) and hot oxidizing media (e.g. HNO{sub 3}). The combination of high resistance to localized corrosion vs. hot chloride-bearing cooling waters including seawater and aggressive oxidizing and reducing hot corrosive media is a unique feature of alloy 31. Alloy 31 is recommended for the construction of heat exchangers, process coolers and piping systems. The material is supplied in a number of semifinished products such as seamless and welded pipes, fittings, flanges, forged bars, plate, sheet, strip, wire and prefabricated piping systems.

  1. Boronization and Carburization of Superplastic Stainless Steel and Titanium-Based Alloys

    Directory of Open Access Journals (Sweden)

    Masafumi Matsushita

    2011-07-01

    Full Text Available Bronization and carburization of fine-grain superplastic stainless steel is reviewed, and new experimental results for fine grain Ti88.5Al4.5V3Fe2Mo2 are reported. In superplastic duplex stainless steel, the diffusion of carbon and boron is faster than in non-superplastic duplex stainless steel. Further, diffusion is activated by uniaxial compressive stress. Moreover, non-superplastic duplex stainless steel shows typical grain boundary diffusion; however, inner grain diffusion is confirmed in superplastic stainless steel. The presence of Fe and Cr carbides or borides is confirmed by X-ray diffraction, which indicates that the diffused carbon and boron react with the Fe and Cr in superplastic stainless steel. The Vickers hardness of the carburized and boronized layers is similar to that achieved with other surface treatments such as electro-deposition. Diffusion of boron into the superplastic Ti88.5Al4.5V3Fe2Mo2 alloy was investigated. The hardness of the surface exposed to boron powder can be increased by annealing above the superplastic temperature. However, the Vickers hardness is lower than that of Ti boride.

  2. An electroplated copper–silver alloy as antibacterial coating on stainless steel

    DEFF Research Database (Denmark)

    Ciacotich, Nicole; Din, Rameez Ud; Sloth, Jens Jørgen

    2018-01-01

    electroplated with a copper-silver alloy with the aim of developing antibacterial surfaces for the medical and health care sector. The microstructural characterization showed a porous microstructure of electroplated copper-silver coating and a homogeneous alloy with presence of interstitial silver. The copper-silver......Transfer and growth of pathogenic microorganisms must be prevented in many areas such as the clinical sector. One element of transfer is the adhesion of pathogens to different surfaces and the purpose of the present study was to develop and investigate the antibacterial efficacy of stainless steel...... alloy coating showed active corrosion behavior in chloride-containing environments. ICP-MS measurements revealed a selective and localized dissolution of copper ions in wet conditions due to its galvanic coupling with silver. No live bacteria adhered to the copper-silver surfaces when exposed...

  3. The microstructural, mechanical, and fracture properties of austenitic stainless steel alloyed with gallium

    Science.gov (United States)

    Kolman, D. G.; Bingert, J. F.; Field, R. D.

    2004-11-01

    The mechanical and fracture properties of austenitic stainless steels (SSs) alloyed with gallium require assessment in order to determine the likelihood of premature storage-container failure following Ga uptake. AISI 304 L SS was cast with 1, 3, 6, 9, and 12 wt pct Ga. Increased Ga concentration promoted duplex microstructure formation with the ferritic phase having a nearly identical composition to the austenitic phase. Room-temperature tests indicated that small additions of Ga (less than 3 wt pct) were beneficial to the mechanical behavior of 304 L SS but that 12 wt pct Ga resulted in a 95 pct loss in ductility. Small additions of Ga are beneficial to the cracking resistance of stainless steel. Elastic-plastic fracture mechanics analysis indicated that 3 wt pct Ga alloys showed the greatest resistance to crack initiation and propagation as measured by fatigue crack growth rate, fracture toughness, and tearing modulus. The 12 wt pct Ga alloys were least resistant to crack initiation and propagation and these alloys primarily failed by transgranular cleavage. It is hypothesized that Ga metal embrittlement is partially responsible for increased embrittlement.

  4. Systematic investigation of the fatigue performance of a friction stir welded low alloy steel

    International Nuclear Information System (INIS)

    Toumpis, Athanasios; Galloway, Alexander; Molter, Lars; Polezhayeva, Helena

    2015-01-01

    Highlights: • The fatigue behaviour of a friction stir welded low alloy steel has been assessed. • The welds’ fatigue lives outperform the International Institute of Welding’s recommendations for fusion welds. • The slow weld exhibits the best fatigue performance of the investigated welds. • Fracture surface analysis shows that minor embedded flaws do not offer crack initiation sites. • Process-related surface breaking flaws have a significant effect on the fatigue life. - Abstract: A comprehensive fatigue performance assessment of friction stir welded DH36 steel has been undertaken to address the relevant knowledge gap for this process on low alloy steel. A detailed set of experimental procedures specific to friction stir welding has been put forward, and the consequent study extensively examined the weld microstructure and hardness in support of the tensile and fatigue testing. The effect of varying welding parameters was also investigated. Microstructural observations have been correlated to the weldments’ fatigue behaviour. The typical fatigue performance of friction stir welded steel plates has been established, exhibiting fatigue lives well above the weld detail class of the International Institute of Welding even for tests at 90% of yield strength, irrespective of minor instances of surface breaking flaws which have been identified. An understanding of the manner in which these flaws impact on the fatigue performance has been established, concluding that surface breaking irregularities such as these produced by the tool shoulder’s features on the weld top surface can be the dominant factor for crack initiation under fatigue loading

  5. Cr-Al coatings on low carbon steel prepared by a mechanical alloying technique

    Science.gov (United States)

    Hia, A. I. J.; Sudiro, T.; Aryanto, D.; Sebayang, K.

    2016-08-01

    Four different compositions of Cr and Al coatings as Cr10o, Cr87.5Al12.5, Cr5oAl5o, and Al100 have been prepared on the surface of low carbon steel by a mechanical alloying technique. The composition of each powder was milled for 2 hour in a stainless steel crucible with a ball to powder ratio of 10:1. Hereafter, the Cr-Al powder and substrate were mechanical alloyed in air for 1 hour. Heat treatment of coated sample were carried out at 800°C in a vacuum furnace. In order to characterize the phase composition and microstructure of the coating before and after heat treatment, XRD and SEM-EDX were used. The results show that Cr, Cr-Al or Al coatings were formed on the surface of low carbon steel. After heat treatment, new phases and interdiffusion zone were formed in the coating and at the coating/steel interface, depending on the coating composition.

  6. Microstructure and mechanical properties of a new type of austempered boron alloyed high silicon cast steel

    Directory of Open Access Journals (Sweden)

    Chen Xiang

    2013-05-01

    Full Text Available In the present paper, a new type of austempered boron alloyed high silicon cast steel has been developed, and its microstructures and mechanical properties at different temperatures were investigated. The experimental results indicate that the boron alloyed high silicon cast steel comprises a dendritic matrix and interdendritic eutectic borides in as-cast condition. The dendritic matrix is made up of pearlite, ferrite, and the interdendritic eutectic boride is with a chemical formula of M2B (M represents Fe, Cr, Mn or Mo which is much like that of carbide in high chromium white cast iron. Pure ausferrite structure that consists of bainitic ferrite and retained austenite can be obtained in the matrix by austempering treatment to the cast steel. No carbides precipitate in the ausferrite structure and the morphology of borides remains almost unchanged after austempering treatments. Secondary boride particles precipitate during the course of austenitizing. The hardness and tensile strength of the austempered cast steel decrease with the increase of the austempering temperature, from 250 篊 to 400 篊. The impact toughness is 4-11 J昪m-2 at room temperature and the impact fracture fractogragh indicates that the fracture is caused by the brittle fracture of the borides.

  7. Influence of alloying elements on resistance to tempering of low carbon pearlitic steels

    International Nuclear Information System (INIS)

    Sandomirskij, M.M.; Rivkin, S.I.; Rudnev, A.D.

    1981-01-01

    Specific effect of chromium, nickel, molybdenum, vanadium on stability against weakening during the tempering of low-carbon chromium-nickel-molybdenum-vanadium pearlitic steels of the 15KhNMF type is investigated. It is established that temperature dependence of the specific effect of alloying elements on stability to the tempering of low-carbon pearlitic steel is characterized by the curve with the maximum, position of which in the temperature scale increases from chromium to molybdenum and vanadium. With the increase of the tempering duration specific effect of each of the elements first increases and then, reaching a certain maximum, decreases. With the increase of chromium content from 1 % to 3 % in the steels investigated its specific effect on stability to the tempering decrease monotonously [ru

  8. The measurement of phosphorus in low alloy steels by electrochemical methods

    Energy Technology Data Exchange (ETDEWEB)

    Rahier, A.; Campsteyn, A.; Verheyen, E.; Verpoucke, G.

    2008-08-15

    The oscillo-polarographic method reported by Chen for the determination of phosphorus in silicates, iron ores, carbonates and tea leaves has been thoroughly studied and enhanced in view of the determination of P in various steels. Together with a carefully selected sample dissolution method, the chromatographic separation reported by Hanada et al. for eliminating the matrix has also been examined. The results of these investigations allowed finding out a path towards the successful electrochemical measurement of P in low alloy ferritic steels without eliminating the matrix. The limit of detection is 5.2 micro gram{sup -1} in the metal. The precision ranges between 5 and 15 % relative to the mean measured values. The finely tuned method has been successfully validated using five NIST standard steels. The chromatographic method remains an option for addressing other metals in the future, should they contain unacceptable levels of possibly interfering elements.. Detailed experimental procedures are given.

  9. The measurement of phosphorus in low alloy steels by electrochemical methods

    International Nuclear Information System (INIS)

    Rahier, A.; Campsteyn, A.; Verheyen, E.; Verpoucke, G.

    2008-01-01

    The oscillo-polarographic method reported by Chen for the determination of phosphorus in silicates, iron ores, carbonates and tea leaves has been thoroughly studied and enhanced in view of the determination of P in various steels. Together with a carefully selected sample dissolution method, the chromatographic separation reported by Hanada et al. for eliminating the matrix has also been examined. The results of these investigations allowed finding out a path towards the successful electrochemical measurement of P in low alloy ferritic steels without eliminating the matrix. The limit of detection is 5.2 micro gram -1 in the metal. The precision ranges between 5 and 15 % relative to the mean measured values. The finely tuned method has been successfully validated using five NIST standard steels. The chromatographic method remains an option for addressing other metals in the future, should they contain unacceptable levels of possibly interfering elements.. Detailed experimental procedures are given.

  10. Compatibility of 316L stainless steel with the liquid alloy Pb17Li

    International Nuclear Information System (INIS)

    Broc, M.; Fauvet, P.; Flament, T.; Terlain, A.; Sannier, J.

    1988-01-01

    The behavior of 316L austenitic stainless steel in liquid eutectic lead alloy is investigated. The 316L is a possible structural material for fusion reactors. The obtained results are summarized and compared with other experimental data. The mechanisms which control the corrosion process are discussed. The investigation shows that whatever, the hydraulic flow, the corrosion of 316L stainless steel exposed to Pb17Li is characterized by the formation of a porous ferritic layer. The corrosion kinetics is mainly dependent on temperature, hydraulic flow and metallurgical state of the steel. At 400 0 C in turbulent flow, the corrosion rate at steady state of 316L solution annealed is estimated to 27 microns/year to which a depth of 25 microns has to be added to take into account the initial transient period. From overall available results, dissolution and solid state transformation in case of turbulent flow and diffusion in liquid phase for laminar flow, may be suggested

  11. Development of stainless steel shape memory alloys; Desenvolvimento de acos inoxidaveis com efeito de memoria de forma

    Energy Technology Data Exchange (ETDEWEB)

    Otubo, J.; Mei, P.R. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica; Koshimizu, S. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    1995-12-31

    It is presented in this work, pioneer in Brazil, the development of two stainless steel shape memory alloys assisted by non thermo-elastic martensitic transformation. In terms of shape recovery, the results obtained are very promising comparable to the best results in the literature with 95 % shape recovery after pre-strain of 4 % when subjected do thermo-mechanical training cycle. The stainless steel character and the shape recovery of almost 4 % of the alloys promote it to practical applications such as for pipe fittings or satellite solar panel release mechanism. Consideration about the alloys processing, mechanical and microstructural properties will also be presented 28 refs., 7 figs., 2 tabs.

  12. Orientation Dependence of Cracking in Hot-Dip Zn-Al-Mg Alloy Coatings on a Sheet Steel

    Science.gov (United States)

    Park, Y. B.; Kim, I. G.; Kim, S. G.; Kim, W. T.; Kim, T. C.; Oh, M. S.; Kim, J. S.

    2017-03-01

    The present study was aimed at investigating a basic cause of cracking in hot-dip Zn-Al-Mg alloy coatings on an extra deep drawing quality sheet steel. The electron backscattering diffraction technique was employed to examine the crystallographic planes of the cracks generated before and after bending deformation of the coated steel sheets. It was clarified that the occurrence of cracking in the Zn-Al-Mg alloy coatings absolutely depends on the orientation of the primary Zn and eutectic Zn alloy phases. Finally, a cracking mechanism was proposed on the basis of the anisotropy of thermal expansion and the Young's modulus in the phases constituting the coatings.

  13. Atom probe study of the microstructural evolution induced by irradiation in Fe-Cu ferritic alloys and pressure vessel steels

    International Nuclear Information System (INIS)

    Pareige, P.

    1996-04-01

    Pressure vessel steels used in pressurized water reactors are low alloyed ferritic steels. They may be prone to hardening and embrittlement under neutron irradiation. The changes in mechanical properties are generally supposed to result from the formation of point defects, dislocation loops, voids and/or copper rich clusters. However, the real nature of the irradiation induced-damage in these steels has not been clearly identified yet. In order to improve our vision of this damage, we have characterized the microstructure of several steels and model alloys irradiated with electrons and neutrons. The study was performed with conventional and tomographic atom probes. The well known importance of the effects of copper upon pressure vessel steel embrittlement has led us to study Fe-Cu binary alloys. We have considered chemical aging as well as aging under electron and neutron irradiations. The resulting effects depend on whether electron or neutron irradiations ar used for thus. We carried out both kinds of irradiation concurrently so as to compare their effects. We have more particularly considered alloys with a low copper supersaturation representative of that met with the French vessel alloys (0.1% Cu). Then, we have examined steels used on French nuclear reactor pressure vessels. To characterize the microstructure of CHOOZ A steel and its evolution when exposed to neutrons, we have studied samples from the reactor surveillance program. The results achieved, especially the characterization of neutron-induced defects have been compared with those for another steel from the surveillance program of Dampierre 2. All the experiment results obtained on model and industrial steels have allowed us to consider an explanation of the way how the defects appear and grow, and to propose reasons for their influence upon steel embrittlement. (author). 3 appends

  14. Effects of surface contamination and cleaning with hypochlorite wipes on the antibacterial activity of copper-alloyed antibacterial stainless steel.

    Science.gov (United States)

    Kawakami, Hiroshi; Hayashi, Takatsuna; Nishikubo, Hideyuki; Morikawa, Akifumi; Suzuki, Satoshi; Sato, Yoshihiro; Kikuchi, Yasushi

    2014-01-01

    Effects of surface contamination and cleaning with hypochlorite wipes on the antibacterial activity of copper-alloyed stainless steel were studied. The antibacterial activity of copper alloyed stainless steel decreased with the increase in the amount of surface contaminant, and the bacterial counts from specimens contaminated with a contaminant, e.g. 1.6 × 10(-2) μg/mm(2) of bovine serum albumin, were not significantly different from those from ordinary stainless steel specimens. The once contaminated surface could regain its antibacterial activity when it was sufficiently wiped clean with sterile wipes loaded with sodium hypochlorite solution.

  15. Neutron irradiation test of copper alloy/stainless steel joint materials

    International Nuclear Information System (INIS)

    Yamada, Hirokazu; Kawamura, Hiroshi

    2006-01-01

    As a study about the joint technology of copper alloy and stainless steel for utilization as cooling piping in International Thermonuclear Experimental Reactor (ITER), Al 2 O 3 -dispersed strengthened copper or CuCrZr was jointed to stainless steel by three kinds of joint methods (casting joint, brazing joint and friction welding method) for the evaluation of the neutron irradiation effect on joints. A neutron irradiation test was performed to three types of joints and each copper alloy. The average value of fast neutron fluence in this irradiation test was about 2 x 10 24 n/m 2 (E>1 MeV), and the irradiation temperature was about 130degC. As post-irradiation examinations, tensile tests, hardness tests and observation of fracture surface after the tensile tests were performed. All type joints changed to be brittle by the neutron irradiation effect like each copper alloy material, and no particular neutron irradiation effect due to the effect of joint process was observed. On the casting and friction welding, hardness of copper alloy near the joint boundary changed to be lower than that of each copper alloy by the effect of joint procedure. However, tensile strength of joints was almost the same as that of each copper alloy before/after neutron irradiation. On the other hand, tensile strength of joints by brazing changed to be much lower than CuAl-25 base material by the effect of joint process before/after neutron irradiation. Results in this study showed that the friction welding method and the casting would be able to apply to the joint method of piping in ITER. This report is based on the final report of the ITER Engineering Design Activities (EDA). (author)

  16. Enhancement of mechanical properties of alloy steels on hot forging

    International Nuclear Information System (INIS)

    Radkevich, M.M.

    1993-01-01

    The paper present the results of an investigation into the effects of the basic parameters of high-temperature thermomechanical treatment (HTTMT) under hot forging. It is shown that forging in open dies of 45Kh, 20Kh13 and 08Kh18N10T steel blanks following the established HTTMT modes improves the ultimate strength by 46, 56 and 2% respectively, and yield limit - by 65, 66 and 14%, as compared with their production in compliance with factory modes, preserving the level of ductility and impact strength

  17. Internal stresses in steel plate generated by shape memory alloy inserts

    International Nuclear Information System (INIS)

    Malard, B.; Pilch, J.; Sittner, P.; Davydov, V.; Sedlák, P.; Konstantinidis, K.; Hughes, D.J.

    2012-01-01

    Graphical abstract: Display Omitted Highlights: ► Thermoresponsive internal stresses introduced into steel by embedding SMA inclusions. ► Neutron strain scanning on steel plate coupons with NiTi inserts at 21 °C and 130 °C. ► Internal stress field in steel evaluated directly from strains and by FE simulation. ► Internal stress generation by SMA insert resistant to thermal and mechanical fatigue. - Abstract: Neutron strain scanning was employed to investigate the internal stress fields in steel plate coupons with embedded prestrained superelastic NiTi shape memory alloy inserts. Strain fields in steel were evaluated at T = 21 °C and 130 °C on virgin coupons as well as on mechanically and thermally fatigued coupons. Internal stress fields were evaluated by direct calculation of principal stress components from the experimentally measured lattice strains as well as by employing an inverse finite element modeling approach. It is shown that if the NiTi inserts are embedded into the elastic steel matrix following a carefully designed technological procedure, the internal stress fields vary with temperature in a reproducible and predictable way. It is estimated that this mechanism of internal stress generation can be safely applied in the temperature range from −20 °C to 150 °C and is relatively resistant to thermal and mechanical fatigue. The predictability and fatigue endurance of the mechanism are of essential importance for the development of future smart metal matrix composites or smart structures with embedded shape memory alloy components.

  18. Simultaneous material flow analysis of nickel, chromium, and molybdenum used in alloy steel by means of input-output analysis.

    Science.gov (United States)

    Nakajima, Kenichi; Ohno, Hajime; Kondo, Yasushi; Matsubae, Kazuyo; Takeda, Osamu; Miki, Takahiro; Nakamura, Shinichiro; Nagasaka, Tetsuya

    2013-05-07

    Steel is not elemental iron but rather a group of iron-based alloys containing many elements, especially chromium, nickel, and molybdenum. Steel recycling is expected to promote efficient resource use. However, open-loop recycling of steel could result in quality loss of nickel and molybdenum and/or material loss of chromium. Knowledge about alloying element substance flow is needed to avoid such losses. Material flow analyses (MFAs) indicate the importance of steel recycling to recovery of alloying elements. Flows of nickel, chromium, and molybdenum are interconnected, but MFAs have paid little attention to the interconnected flow of materials/substances in supply chains. This study combined a waste input-output material flow model and physical unit input-output analysis to perform a simultaneous MFA for nickel, chromium, and molybdenum in the Japanese economy in 2000. Results indicated the importance of recovery of these elements in recycling policies for end-of-life (EoL) vehicles and constructions. Improvement in EoL sorting technologies and implementation of designs for recycling/disassembly at the manufacturing phase are needed. Possible solutions include development of sorting processes for steel scrap and introduction of easier methods for identifying the composition of secondary resources. Recovery of steel scrap with a high alloy content will reduce primary inputs of alloying elements and contribute to more efficient resource use.

  19. Effect of Aluminum and Silicon on Atmospheric Corrosion of Low-alloying Steel under Containing NaHSO3 Wet/dry Environment

    International Nuclear Information System (INIS)

    Xinhua, Chen; Junhua, Dong; Enhou, Han; Wei, Ke

    2008-01-01

    The atmospheric corrosion performance of Al-alloying Si-alloying and Al-Si-alloying steel were studied by wet/dry cyclic corrosion tests (CCT) at 30 .deg. C and 60% relative humidity (RH). The corrosion electrolyte used for CCT was 0.052 wt% NaHSO 3 (pH∼4) solution. The result of gravimetry demonstrated that Al-Si-bearing steels showed lower corrosion resistance than other rusted steels. But the rusted 0.7%Si-alloying steel showed a better corrosion resistance than rusted mild steel. Polarization curves demonstrated that Al-/Si-alloying and Al-Si-alloying improved the rest potential of steel at the initial stage: and accelerated the cathodic reduction and anodic dissolution after a rust layer formed on the surfaces of steels. XRD results showed that Al-Si-alloying decreased the volume fraction of Fe 3 O 4 and α-FeOOH. The recycle of acid accelerated the corrosion of steel at the initial stage. After the rust layer formed on the steel, the leak of rust destabilized the rust layer due to the dissolution of compound containing Al (such as FeAl 2 O 4 , (Fe, Si) 2 (Fe, Al)O 4 ). Al-Si-alloying is hence not suitable for improving the anti-corrosion resistance of steel in industrial atmosphere

  20. Fabrication of Nanostructured Medical-Grade Stainless Steel by Mechanical Alloying and Subsequent Liquid-Phase Sintering

    Science.gov (United States)

    Salahinejad, Erfan; Hadianfard, Mohammad J.; Ghaffari, Mohammad; Mashhadi, Shirazeh Bagheri; Okyay, Ali K.

    2012-08-01

    This article focuses on the microstructure of medical-grade P558 (ASTM F2581) stainless steel produced by mechanical alloying and liquid-phase sintering. Rietveld X-ray diffraction and transmission electron microscopy reflect that the mechanically alloyed stainless steel powder is a nanocrystal dispersed amorphous matrix composite. Mn-11.5 wt pct Si eutectic alloy as additive improves densification of the synthesized P558 alloy via liquid-phase sintering mechanism. X-ray mapping shows that after sintering at 1323 K (1050 °C) for 1 hour, a uniform distribution of dissolved Mn and Si is achieved. Moreover, the development of a nanostructured, fully austenitic stainless steel after sintering at the same temperature is realized by X-ray diffraction and transmission electron microscopy.

  1. An Industrial Perspective on Environmentally Assisted Cracking of Some Commercially Used Carbon Steels and Corrosion-Resistant Alloys

    Science.gov (United States)

    Ashida, Yugo; Daigo, Yuzo; Sugahara, Katsuo

    2017-08-01

    Commercial metals and alloys like carbon steels, stainless steels, and nickel-based super alloys frequently encounter the problem of environmentally assisted cracking (EAC) and resulting failure in engineering components. This article aims to provide a perspective on three critical industrial applications having EAC issues: (1) corrosion and cracking of carbon steels in automotive applications, (2) EAC of iron- and nickel-based alloys in salt production and processing, and (3) EAC of iron- and nickel-based alloys in supercritical water. The review focuses on current industrial-level understanding with respect to corrosion fatigue, hydrogen-assisted cracking, or stress corrosion cracking, as well as the dominant factors affecting crack initiation and propagation. Furthermore, some ongoing industrial studies and directions of future research are also discussed.

  2. Alloy Design Based on Computational Thermodynamics and Multi-objective Optimization: The Case of Medium-Mn Steels

    Science.gov (United States)

    Aristeidakis, John S.; Haidemenopoulos, Gregory N.

    2017-05-01

    A new alloy design methodology is presented for the identification of alloy compositions, which exhibit process windows (PWs) satisfying specific design objectives and optimized for overall performance. The methodology is applied to the design of medium-Mn steels containing Al and/or Ni. By implementing computational alloy thermodynamics, a large composition space was investigated systematically to map the fraction and stability of retained austenite as a function of intercritical annealing temperature. Alloys exhibiting PWs, i.e., an intercritical annealing range, which when applied satisfies the given design objectives, were identified. A multi-objective optimization method, involving Pareto optimality, was then applied to identify a list of optimum alloy compositions, which maximized retained austenite amount and stability, as well as intercritical annealing temperature, while minimized overall alloy content. A heuristic approach was finally employed in order to rank the optimum alloys. The methodology provided a final short list of alloy compositions and associated PWs ranked according to their overall performance. The proposed methodology could be the first step in the process of computational alloy design of medium-Mn steels or other alloy systems.

  3. Impact resistance and fractography of low-alloy martensitic steels

    Directory of Open Access Journals (Sweden)

    S. Frydman

    2008-03-01

    Full Text Available In this paper dynamic properties of HTK SOOH, HTK 900H. Hardox 400 and Hardox 500 steeZs in delivcrcd stalc (aftcr hardening andtempering are considered. Charpy V - notch (CVN test rcsults in connection with fractography in the ductilc - to - brittle transitionternpcrature region were analyzed. The impact transition curve obtained from CVN tcst not always predicts properly a behavior ofmaterials in conditions of dynamic loading, so the analyze of character of fracture helps to evalitate the rcal bchavior of ma~crials. Tcstcdsamples were cut out longitudinally and transversely in relation to cold work direction. The results of CVN test far investigated steels, inthe range of temperatures from 40t o 20 "C are presented. Regarding ductilc - to - bri~tlel ransition temperature, there is a significantdiffcrcnce taking into account vatues of Charpy V cncrgy absorbcd and a character of fracture.

  4. Effects of Zr Addition on Strengthening Mechanisms of Al-Alloyed High-Cr ODS Steels.

    Science.gov (United States)

    Ren, Jian; Yu, Liming; Liu, Yongchang; Liu, Chenxi; Li, Huijun; Wu, Jiefeng

    2018-01-12

    Oxide dispersion strengthened (ODS) steels with different contents of zirconium (denoted as 16Cr ODS, 16Cr-0.3Zr ODS and 16Cr-0.6Zr ODS) were fabricated to investigate the effects of Zr on strengthening mechanism of Al-alloyed 16Cr ODS steel. Electron backscatter diffraction (EBSD) results show that the mean grain size of ODS steels could be decreased by Zr addition. Transmission electron microscope (TEM) results indicate that Zr addition could increase the number density but decrease the mean diameter and inter-particle spacing of oxide particles. Furthermore, it is also found that in addition to Y-Al-O nanoparticles, Y-Zr-O oxides with finer size were observed in 16Cr-0.3Zr ODS and 16Cr-0.6Zr ODS steels. These changes in microstructure significantly increase the yield strength (YS) and ultimate tensile strength (UTS) of ODS steels through mechanisms of grain boundary strengthening and dispersion strengthening.

  5. Corrosion performance of mechanically fastened aluminum/steel joints: Influence of fastener type and aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gunkel, R.W.; Moran, J.P. [Aluminum Co. of America, Alcoa Center, PA (United States). Alcoa Technical Center

    1995-11-01

    This paper discusses the corrosion test results for aluminum to steel lap-shear joints fabricated from three aluminum alloys using four different mechanical fasteners. The evaluations included exposure to alternate immersion (AI) and 100% relative humidity (RH) corrosion tests after phosphating and applying a 25 {micro}m E-Coat (i.e., electrolytic coating) to the completed assembly. Lap-shear test results showed that specimens fabricated using self-piercing rivets and solid rivets exhibited strengthening after 30--60 days exposure to AI or RH testing, which was subsequently followed by a decrease in tensile strength as aluminum base metal deterioration began to control the mechanical properties. Metallographic examination suggested the strengthening effect resulted from corrosion product buildup which produced compressive stresses on the joint members. The data indicated that stainless steel fasteners do not limit the corrosion performance of mechanically fastened aluminum to steel joints fabricated from bare sheets which are primed after assembly. The data also indicated that utilization of sealants in mechanically fastened aluminum/steel joints significantly improve corrosion performance of aluminum/steel joints.

  6. Is galvanic corrosion between titanium alloy and stainless steel spinal implants a clinical concern?

    Science.gov (United States)

    Serhan, Hassan; Slivka, Michael; Albert, Todd; Kwak, S Daniel

    2004-01-01

    Surgeons are hesitant to mix components made of differing metal classes for fear of galvanic corrosion complications. However, in vitro studies have failed to show a significant potential for galvanic corrosion between titanium and stainless steel, the two primary metallic alloys used for spinal implants. Galvanic corrosion resulting from metal mixing has not been described in the literature for spinal implant systems. To determine whether galvanic potential significantly affects in vitro corrosion of titanium and stainless steel spinal implant components during cyclical compression bending. Bilateral spinal implant constructs consisting of pedicle screws, slotted connectors, 6.35-mm diameter rods and a transverse rod connector assembled in polyethylene test blocks were tested in vitro. Two constructs had stainless steel rods with mixed stainless steel (SS-SS) and titanium (SS-Ti) components, and two constructs had titanium rods with mixed stainless steel (Ti-SS) and titanium (Ti-Ti) components. Each construct was immersed in phosphate-buffered saline (pH 7.4) at 37 C and tested in cyclic compression bending using a sinusoidal load-controlling function with a peak load of 300 N and a frequency of 5 Hz until a level of 5 million cycles was reached. The samples were then removed and analyzed visually for evidence of corrosion. In addition, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) were used to evaluate the extent of corrosion at the interconnections. None of the constructs failed during testing. Gross observation of the implant components after disassembly revealed that no corrosion had occurred on the surface of the implants that had not been in contact with another component. The Ti-Ti interfaces showed some minor signs of corrosion only detectable using SEM and EDS. The greatest amount of corrosion occurred at the SS-SS interfaces and was qualitatively less at the SS-Ti and Ti-SS interfaces. The results from this study indicate

  7. Temperature and environmentally assisted cracking in low alloy steel

    International Nuclear Information System (INIS)

    Auten, T.A.; Monter, J.V.

    1995-01-01

    Environmentally assisted cracking (EAC) can be defined as the propagation of fatigue cracks in water at rates that are anywhere from 3 to over 40 times the growth rates expected in air. In the present work, five ASTM A 508 Class 2 forgings with ladle and check analyses that ranged from 0.010 to 0.019 wt% S were tested in high purity deaerated water in the temperature range of 93 to 260 C. At 260 C these forgings did not undergo EAC, reinforcing earlier results for two similar forgings. This broad sampling indicates a strong resistance to EAC for this class of forging at 260 C. On the other hand, EAC occurred consistently in the three of these forgings that were tested below 204 C, provided the test conditions were high enough to produce a high baseline fatigue crack growth rate (FCGR), where the baseline FCGR is that expected in air. At 149 C, EAC occurred at test conditions that combined to yield a baseline FCGR greater than ∼2E-6 mm/s. At 204, 121, and 93 C, this ''critical crack growth rate'' appeared to shift to lower baseline values. The EAC that occurred at lower temperatures was a factor of 3 to 12 times higher than baseline air rates, which was not as strong as the effect for higher sulfur steels at 240 to 290 C. Also, no plateau in the growth rates occurred as it does with the higher sulfur steels. In another approach, EAC was induced at 93 and at 260 C by raising the dissolved oxygen content of the water from 15 ppb. In this case, the EAC growth rates decreased to non-EAC levels when the oxygen supply was shut off. The oxygen-related EAC occurred over a broader range of baseline growth rates than found for the EAC driven by the baseline crack tip speed. Again, this can be rationalized by the buildup of sulfur in the crack tip water, which can be associated with the higher corrosion potential of the bulk water

  8. Effect of composition on corrosion resistance of high-alloy austenitic stainless steel weld metals

    International Nuclear Information System (INIS)

    Marshall, P.I.; Gooch, T.G.

    1993-01-01

    The corrosion resistance of stainless steel weld metal in the ranges of 17 to 28% chromium (Cr), 6 to 60% nickel (Ni), 0 to 9% molybdenum (Mo), and 0.0 to 0.37% nitrogen (N) was examined. Critical pitting temperatures were determined in ferric chloride (FeCl 3 ). Passive film breakdown potentials were assessed from potentiodynamic scans in 3% sodium chloride (NaCl) at 50 C. Potentiodynamic and potentiostatic tests were carried out in 30% sulfuric acid (H 2 SO 4 ) ar 25 C, which was representative of chloride-free acid media of low redox potential. Metallographic examination and microanalysis were conducted on the test welds. Because of segregation of alloying elements, weld metal pitting resistance always was lower than that of matching composition base steel. The difference increased with higher Cr, Mo, and N contents. Segregation also reduced resistance to general corrosion in H 2 SO 4 , but the effect relative to the base steel was less marked than with chloride pitting. Segregation of Cr, Mo, and N in fully austenitic deposits decreased as the Ni' eq- Cr' eq ratio increased. Over the compositional range studied, weld metal pitting resistance was dependent mainly on Mo content and segregation. N had less effect than in wrought alloys. Both Mo and N enhanced weld metal corrosion resistance in H 2 SO 4

  9. Bending Fretting Fatigue Characteristics of 18CrNiMo7-6 Alloy Steel

    Directory of Open Access Journals (Sweden)

    SHEN Yan-tuan

    2017-07-01

    Full Text Available A series of bending fretting fatigue tests of 18CrNiMo7-6 alloy steel were carried out, the bending fretting fatigue S-N curve was built up, and an analysis was made on the test results. The results show that, the S-N curve of 18CrNiMo7-6 alloy steel presents a shape of "ε" curve, which is different from the medium carbon steel, and also different from the plain bending fatigue. With the increase of the bending fatigue stress, the fretting regime transforms from partial slip regime to mixed regime and slip regime. The wear mechanisms of fretting damage zones mainly are delaminated, abrasive wear and oxidative wear. In the mixed regime, the cracks are easy to initiate and propagate, and the cracks all originate from the subsurface of contact zone. Due to the different influence levels of the contact stress and bending fatigue stress, the initiation and propagation of the bending fretting fatigue cracks can be divided into three stages. Firstly, the cracks initiate from subsurface under the control of contact stress; then propagate to a larger angle direction under the joint control of contact stress and bending fatigue stress; lastly the cracks propagate vertically to contact surface until fracture failure under the control of bending fatigue stress.

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

    Science.gov (United States)

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

    1980-01-01

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

  11. Effects of Alloying Elements (Cr, Mn) on Corrosion Properties of Carbon Steel in Synthetic Seawater

    International Nuclear Information System (INIS)

    Hyun, Youngmin; Kim, Heesan

    2016-01-01

    Effects of alloying elements, manganese and chromium, on corrosion resistance of carbon steel were examined using weight loss test and electrochemical tests (polarization test and electrochemical impedance spectroscopy (EIS)) in synthetic seawater at 60 ℃. The results from the weight loss test showed that chromium effectively improved corrosion resistance of carbon steel during the entire immersion time, but manganese improved corrosion resistance after the lowered corrosion resistance at the beginnings of immersion. Unlike the weight loss test, the electrochemical tests showed that the corrosion resistance did not increase with immersion time, in all the specimens. This disagreement is explained by the presence of rust involved in electrochemical reaction during electrochemical tests. The analysis of rust with transmission electron microscopy (TEM)−energy dispersive spectroscopy (EDS) showed that the amorphous-like rust layer located at the metal/rust interface with enriched alloying element (Cr, Mn) prevents diffusion of corrosive species into a metal/rust interface effectively, which leads to increased corrosion resistance. The initial corrosion behaviour is also affected by the rust types. In other words, manganese accelerated the formation of spinel oxides, negatively affecting corrosion resistance. Meanwhile, chromium accelerated the formation of goethite but impeded the formation of spinel oxides, positively affecting the corrosion resistance. From the above results, the corrosion resistance of steel is closely related with a rust type.

  12. Microstructure design of low alloy transformation-induced plasticity assisted steels

    Science.gov (United States)

    Zhu, Ruixian

    The microstructure of low alloy Transformation Induced Plasticity (TRIP) assisted steels has been systematically varied through the combination of computational and experimental methodologies in order to enhance the mechanical performance and to fulfill the requirement of the next generation Advanced High Strength Steels (AHSS). The roles of microstructural parameters, such as phase constitutions, phase stability, and volume fractions on the strength-ductility combination have been revealed. Two model alloy compositions (i.e. Fe-1.5Mn-1.5Si-0.3C, and Fe-3Mn-1Si-0.3C in wt%, nominal composition) were studied. Multiphase microstructures including ferrite, bainite, retained austenite and martensite were obtained through conventional two step heat treatment (i.e. intercritical annealing-IA, and bainitic isothermal transformation-BIT). The effect of phase constitution on the mechanical properties was first characterized experimentally via systematically varying the volume fractions of these phases through computational thermodynamics. It was found that martensite was the main phase to deteriorate ductility, meanwhile the C/VA ratio (i.e. carbon content over the volume fraction of austenite) could be another indicator for the ductility of the multiphase microstructure. Following the microstructural characterization of the multiphase alloys, two microstructural design criteria (i.e. maximizing ferrite and austenite, suppressing athermal martensite) were proposed in order to optimize the corresponding mechanical performance. The volume fraction of ferrite was maximized during the IA with the help of computational thermodyanmics. On the other hand, it turned out theoretically that the martensite suppression could not be avoided on the low Mn contained alloy (i.e. Fe- 1.5Mn-1.5Si-0.3C). Nevertheless, the achieved combination of strength (~1300MPa true strength) and ductility (˜23% uniform elongation) on the low Mn alloy following the proposed design criteria fulfilled the

  13. Formation Mechanism of Spinel-Type Inclusions in High-Alloyed Stainless Steel Melts

    Science.gov (United States)

    Park, Joo Hyun

    2007-08-01

    Fundamental thermodynamics of the relationship between high-alloyed stainless steel melts (Fe-20 mass pct Cr-13 mass pct Ni-3 mass pct Si) and the inclusions were investigated. The formation mechanism of the inclusions containing the spinel crystals was developed based on the experimental results and from the compositions of the inclusions in the steel samples taken during plant operations. The molar content of alumina in the inclusions was found to be linearly proportional to the increase of aluminum content, indicating that the inclusions could contain alumina even with less than about 200 ppm aluminum in the steel melt, e.g., steel melts that were mainly deoxidized by silicon. Furthermore, the composition of the inclusions is shown to be a function of the activity of the deoxidizers such as aluminum and silicon in the steel melt. From the analysis of the plant samples, it was found that the contents of MgO and Al2O3 in the calcium silicate type inclusions increased continuously as the steel melt transfers from the argon oxygen decarburization (AOD) converter to the tundish. This composition change in the inclusions originated from the reduction of MgO and Al2O3 in the slags or refractories by silicon in the steel melt. Increases of MgO and Al2O3 contents were prominent in tundish samples, and thus, the spinel phase could be crystallized in the calcium silicate inclusion matrix in the tundish; and finally the spinel crystals grew during cooling of the steel melt through the continuous casting (CC) mold and in the slabs. On the other hand, manganese silicate type inclusions containing chromium oxide were observed after tapping of the molten steel to the ladle. The MnO and Cr2O3 in these inclusions was initially reduced by silicon in the steel melt in the ladle treatment (LT) process, followed by further reduction by aluminum through the LT to the CC mold. The fractions of inclusions containing spinel crystals in cast slabs were negligible at the alumina content of

  14. Influence of heat input on weld bead geometry using duplex stainless steel wire electrode on low alloy steel specimens

    Directory of Open Access Journals (Sweden)

    Ajit Mondal

    2016-12-01

    Full Text Available Gas metal arc welding cladding becomes a popular surfacing technique in many modern industries as it enhances effectively corrosion resistance property and wear resistance property of structural members. Quality of weld cladding may be enhanced by controlling process parameters. If bead formation is found acceptable, cladding is also expected to be good. Weld bead characteristics are often assessed by bead geometry, and it is mainly influenced by heat input. In this paper, duplex stainless steel E2209 T01 is deposited on E250 low alloy steel specimens with 100% CO2 gas as shielding medium with different heats. Weld bead width, height of reinforcement and depth of penetration are measured. Regression analysis is done on the basis of experimental data. Results reveal that within the range of bead-on-plate welding experiments done, parameters of welding geometry are on the whole linearly related with heat input. A condition corresponding to 0.744 kJ/mm heat input is recommended to be used for weld cladding in practice.

  15. Spark Plasma Sintering of Low Alloy Steel Modified with Silicon Carbide

    Directory of Open Access Journals (Sweden)

    Hebda M.

    2016-06-01

    Full Text Available The influence of adding different amounts of silicon carbide on the properties (density, transverse rupture strength, microhardness and corrosion resistance and microstructure of low alloy steel was investigated. Samples were prepared by mechanical alloying (MA process and sintered by spark plasma sintering (SPS technique. After the SPS process, half of each of obtained samples was heat-treated in a vacuum furnace. The results show that the high-density materials have been achieved. Homogeneous and fine microstructure was obtained. The heat treatment that followed the SPS process resulted in an increase in the mechanical and plastic properties of samples with the addition 1wt. % of silicon carbide. The investigated compositions containing 1 wt.% of SiC had better corrosion resistance than samples with 3 wt.% of silicon carbide addition. Moreover, corrosion resistance of the samples with 1 wt.% of SiC can further be improved by applying heat treatment.

  16. Ferrite and Perlite Hardening in Copper-Alloyed Steels and Irons

    Science.gov (United States)

    Bataev, I. A.; Stepanova, N. V.; Bataev, A. A.; Razumakov, A. A.

    2017-10-01

    The paper presents transmission electron microscopy (TEM) investigations of ɛ-copper formation in ferritic grains and perlitic colonies of irons and steels alloyed with copper. It is shown that copper-enriched inclusions substantially differ in size and shape. The most disperse are particles produced by decomposition of α-phase in iron due to oversaturated copper. The size of particles appeared after austenite decomposition is approximately an order of magnitude larger. After the formation of ɛ-copper particles in ɛ-phase, they incorporate both in ferrite and partially in cementite laminas during the formation of lamellar perlite. Fine particles of ɛ-copper locating inside ferritic grains and in ferritic layers in perlite, restrain the dislocation mobility and have an additional hardening effect on iron-carbon alloys.

  17. The effect of σ-phase precipitation at 800°C on the corrosion resistance in sea-water of a high alloyed duplex stainless steel

    NARCIS (Netherlands)

    Wilms, M.E.; Gadgil, V.J.; Krougman, J.M.; Ijsseling, F.P.

    1994-01-01

    Super-duplex stainless steels are recently developed high alloyed stainless steels that combine good mechanical properties with excellent corrosion resistance. Because of a high content of chromium and molybdenum, these alloys are susceptible to σ-phase precipitation during short exposure to

  18. Grain boundary phosphorus segregation under thermal aging in low alloy steels

    International Nuclear Information System (INIS)

    Nakata, Hayato; Fujii, Katsuhiko; Fukuya, Koji; Shibata, Masaaki; Kasada, Ryuta; Kimura, Akihiko

    2002-01-01

    Intergranular embrittlement due to grain boundary segregation of phosphorus is recognized as one of the potential degradation factors in irradiated reactor pressure vessel steels at high neutron fluences. In this study, investigations on low alloy steels thermally aged at 400-500degC were conducted to evaluate the correlation between phosphorus segregation and intergranular embrittlement. Phosphorus segregation determined using Auger electron spectroscopy increased after aging above 450degC and was in good agreement with the calculated value based on McLean model. No influence of thermal aging was observed in tensile properties. The ductile brittle transition temperature determined using 1/3 size charpy impact tests increased of 12degC after aging at 450degC for 3000 hours. These results indicated that there is a threshold level of phosphorus segregation for non-hardening embrittlement and that the level is around 0.14 for P/Fe peak ratio. (author)

  19. Standard guide for estimating the atmospheric corrosion resistance of low-alloy steels

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

    1.1 This guide presents two methods for estimating the atmospheric corrosion resistance of low-alloy weathering steels, such as those described in Specifications A242/A242M, A588/A588M, A606 Type 4, A709/A709M grades 50W, HPS 70W, and 100W, A852/A852M, and A871/A871M. One method gives an estimate of the long-term thickness loss of a steel at a specific site based on results of short-term tests. The other gives an estimate of relative corrosion resistance based on chemical composition. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

  20. Partial-Isothermally-Treated Low Alloy Ultrahigh Strength Steel with Martensitic/Bainitic Microstructure

    Science.gov (United States)

    Luo, Quanshun; Kitchen, Matthew; Patel, Vinay; Filleul, Martin; Owens, Dave

    We introduce a new strengthening heat treatment of a Ni-Cr-Mo-V alloyed spring steel by partial isothermal salt-bath and subsequent air-cooling and tempering. Detailed isothermal treatments were made at temperatures below or above the Ms point (230°C). The salt bath time was controlled between 10 and 80 minutes. Through the new treatment, the candidate steel developed ultrahigh tensile strength 2,100 MPa, yield strength 1,800 MPa, elongation 8-10 %, hardness 580-710 HV, and V-notch Charpy toughness 10-12 J. Optical and electron microscopic observations and X-ray diffraction revealed multi-phase microstructures of bainitic/martensitic ferrites, fine carbide precipitates and retained austenite. Carbon partitioning during the bainitic/martensitic transformation was investigated for its remarkable influence on the strengthening mechanism.

  1. The influence of heat treatment on strain aging phenomena of the low alloyed carbon steel piping

    International Nuclear Information System (INIS)

    Lee, J. S.; Kim, I. S.; Kim, J. W.

    2001-01-01

    Strain aging characteristics were studied on the low alloyed carbon steel. Intercritical annealing in two phase region was performed to the SA106 Gr.C steel to reduce the detrimental strain aging effects. Tensile tests were carried out at various temperatures before and after treatment. Yield point return technique was used to measure the relative interstitial solute content. Tensile test results of heat treated specimen showed that the extent of ductility loss due to dynamic strain aging was reduced and that the temperature regions of the minimum ductility were shifted to higher temperature compared to the as received. The heat treatment seemed to reduce interstitial solute content in the ferrite matrix, which exhibited the decreased aging index as well as increased source hardening and yield point elongation. Activation energies of interstitial solute bulk diffusion determined by yield point return technique were 113.9 and 122.8 kJ/mol before and after heat treatment, respectively

  2. Semiconducting properties of oxide and passive films formed on AISI 304 stainless steel and Alloy 600

    Directory of Open Access Journals (Sweden)

    Ferreira M. G. S.

    2002-01-01

    Full Text Available The semiconducting properties of passive films formed on AISI 304 stainless steel and Alloy 600 in borate buffer solution were studied by capacitance (Mott-Schottky approach and photocurrent measurements. Oxide films formed on 304 stainless steel in air at 350 ºC have also been studied. The results obtained show that, in all cases the electronic structure of the films is comparable to that of a p-n heterojunction in which the space charges developed at the metal-film and film-electrolyte interfaces have also to be considered. This is in accordance with analytical results showing that the oxide films are in all cases composed of an inner region rich in chromium oxide and an outer region rich in iron oxide.

  3. Corrosion behavior of low-alloy steel in the presence of Desulfotomaculum sp

    International Nuclear Information System (INIS)

    Cetin, Demet; Aksu, Mehmet Levent

    2009-01-01

    The objective of this study was to determine the effect of sulfate-reducing Desulfotomaculum sp. bacteria isolated from a crude oil field on the corrosion of low-alloy steel. The corrosion rate and mechanism were determined with the use of Tafel slopes, mass loss method and electrochemical impedance spectroscopy (EIS). The formation of the biofilm and the corrosion products on the steel surface was determined with scanning electron microscopy (SEM) micrographs and energy dispersive X-ray spectra (EDS) analysis. It was observed from the Tafel plots that the corrosion potential exhibited a cathodic shift that verifies an increase in the corrosion rates. The semicircles tended to open at lower frequencies in the Nyquist plots which indicates the rupture of the protective film. The corrosion current density reached its maximum value at the 14th hour after the inoculation and decreased afterwards. This was attributed to the accumulation of corrosion products on the surface.

  4. Joining of Aluminium Alloy and Steel by Laser Assisted Reactive Wetting

    Science.gov (United States)

    Liedl, Gerhard; Vázquez, Rodrigo Gómez; Murzin, Serguei P.

    2017-12-01

    Compounds of dissimilar materials, like aluminium and steel offer an interesting opportunity for the automotive industry to reduce the weight of a car body. Thermal joining of aluminium and steel leads to the formation of brittle intermetallic compounds, which negatively affects the properties of the welded joint. Amongst others, growth of such intermetallic compounds depends on maximum temperature and on the time at certain temperatures. Laser welding with its narrow well seam and its fast heating and cooling cycles provides an excellent opportunity to obtain an ultrathin diffusion zone. Joining of sheet metal DC01 with aluminium alloy AW6016 has been chosen for research. The performed experimental studies showed that by a variation of the beam power and scanning speed it is possible to obtain an ultrathin diffusion zone with narrow intermetallic interlayers. With the aim of supporting further investigation of laser welding of the respective and other dissimilar pairings a multi-physical simulation model has been developed.

  5. Effect of heat-treatment on the hardness and mechanical properties of Boron Alloyed Steel

    Directory of Open Access Journals (Sweden)

    bin Khiyon Mohammad Raffik

    2017-01-01

    Full Text Available In an automotive industry, hot stamped, die quenched structural components have been widely used to provide extra protection against crash intrusion. Boron alloyed steel exhibit limited ductility, but it also promotes improvement in impact performance. This study analyzed the effect of cooling rate on the hardness and energy absorption. Self-quenched specimens were heated to 850°C and cooled in air of room temperature, water at room temperature and cold water. Vickers hardness test and tensile test was then carried out to analyze the effect of different quenching rate. Self-quenched specimens were compared to the properties of the die-quenched specimens obtained from commercial automobile body. Result shows that boron steel with the highest cooling rate has the highest value of hardness but low in strength.

  6. Structure and characteristics of chromium steel coatings alloyed with boron carbide

    Science.gov (United States)

    Eremin, E. N.; Losev, A. S.; Borodikhin, S. A.; Matalasova, A. E.; Ponomarev, I. A.; Ivlev, K. E.

    2018-01-01

    This study explores the problems arising from the increase of wear resistance on the coatings of details of a wide range of applications, obtained by surfacing the Fe - Cr system with flux-cored wires. It has shown that insignificant wear resistance of such steel under conditions of metal friction against another metal is due to their relatively low hardness and the absence of strengthening phases. It also shows the effect of boron carbide on the structure and the characteristics of chromium steel obtained by the surfacing process. It was established that the use of high-chromium flux-cored wires alloyed with boron carbide aids the production of a deposited metal of a composite type, with a dispersed hardening based on chromium carboboride. The deposited metal with such structure has a high wear resistance and the hardness of 55 … 58 HRC and can be used for surfacing cladding the hardening, corrosion-resistant coatings.

  7. Amorphization by friction welding between 5052 aluminum alloy and 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Fukumoto, S.; Tsubakino, H.; Okita, K.; Aritoshi, M.; Tomita, T.

    2000-04-14

    The joining of dissimilar metals such as aluminum/stainless steel is a very important technique. In the case of fusion welding of an Fe-Al system, excess formation of brittle intermetallic compounds degrades the joint. Since friction welding is one of the solid-state bonding procedures, few intermetallic compounds are formed at the weld interface. However, in the Al-Fe system, the solid solubility is almost nil, so some intermetallic compounds will be formed in spite of the friction welding. In the present study, microstructure of the friction weld interface between Al-Mg alloy and austenitic stainless steel was investigated by high resolution transmission electron microscopy and the mechanism of friction welding was examined.

  8. Study of anti-laser irradiation performance of shot-peened 40CrNiMoA alloy steel

    International Nuclear Information System (INIS)

    Liu, Zhanwei; Wu, Ningning; Huang, Xianfu; Xie, Huimin; Lv, Xintao; He, Guang

    2012-01-01

    In this paper, shot-peening treatment was introduced to reinforce an alloy surface to protect it from laser irradiation, and experiments were carried out on 40CrNiMoA alloy steel. Macro-mechanical properties were studied and compared before and after both shot-peening and laser irradiation by conducting tensile and hardness measurements. Experimental results showed that the shot-peened alloy showed better mechanical properties after laser irradiation when compared to the alloy without shot-peening treatment. The enhanced ability of the shot-peened alloy for anti-laser irradiation was explained as due to the large residual compressive stress distributions over the shot-peening layer greatly reducing the thermal shock effect introduced by the laser. On the other hand, the growth of microstructures in specific shape absorbed the thermal energy during irradiation, giving a higher probability for the alloy to resist damage.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-02-25

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

  10. Copper alloy-stainless steel bonds and recent developments for Tore Supra

    International Nuclear Information System (INIS)

    Lipa, M.; Chappuis, Ph.; Mitteau, R.; Reindl, G.

    1998-01-01

    High strength high conductivity copper alloys such as CuCrZr are used in Tore Supra as structural heat sink material for high heat flux plasma facing components. Although friction welded pipes on these components have shown a satisfactory in-service reliability, it came out that recently produced CuCrZr-stainless steel bonds showed very poor results in ductility. This led to a more detailed investigation of friction weldments. Finally, a more ductile joint has been developed with 'Plansee AG' on the basis of electron beam welded nickel adapters inserted between the two materials. Characterisation of such bonds is reported. (author)

  11. The effects of dynamic load on behaviour of welded joint A-387 Gr. 11 alloyed steel

    Directory of Open Access Journals (Sweden)

    O. Popović

    2013-01-01

    Full Text Available The in-service behaviour of alloyed steel A-387 Gr. 11 Class 1, for pressure vessels, used for high temperature applications, depends on the properties of its welded joint, with parent metal (BM, heat-affected-zone (HAZ and weld metal (WM, as constituents. Charpy testing of BM, WM and HAZ, together with, determination of the parameters of fatigue-crack growth and fatigue threshold ΔKth was used, in order to understand, how heterogeneity of structure and different mechanical properties of welded joint constituents affect on crack initiation and propagation.

  12. Resistance Spot Welding of Aluminum Alloy to Steel with Transition Material - From Process to Performance

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.; Shao, H; Kimchi, Menachem; Menachem Kimchi and Wanda Newman

    2004-05-11

    This paper summarizes work to date on resistance spot welding (RSW) of aluminum alloy to mild steel from process development to performance evaluation. A cold-rolled strip material is introduced as a transition material to aid the resistance welding process. The optimal welding parameters and electrode selections were established using a combination of experimental and analytical approaches. The mechanical behaviors of welded samples was evaluated using static and dynamic strength tests and cyclic fatigue tests. A statistical analysis was also performed to analyze the effect of different failure modes on the sample's peak load and energy absorption.

  13. Inertia and friction welding of aluminum alloy 1100 to type 316 stainless steel

    International Nuclear Information System (INIS)

    Perkins, M.A.

    1979-01-01

    The inertia and friction-welding processes were evaluated for joining aluminum alloy 1100-H14 and Type 316 vacuum-induction melted, vacuum-arc remelted (VIM VAR) stainless steel. While both processes consistently produced joints in which the strength exceeded the strength of the aluminum base metal, 100 percent bonding was not reliably achieved with inertia welding. The deficiency points out the need for development of nondestructive testing techniques for this type of joint. Additionally, solid-state volume diffusion did not appear to be a satisfactory explanation for the inertia and friction-welding bonding mechanism

  14. A simulation of corrosion fatigue life distribution in low alloy steel

    Science.gov (United States)

    Nakajima, Masaki; Kunieda, Hisashi; Tokaji, Keiro

    1992-07-01

    A Monte Carlo simulation of corrosion fatigue life distributions was conducted in a low alloy steel, SNCM439, by assuming that the scatter of fatigue life resulted from the variation in the growth characteristics of corrosion pits and fatigue cracks. The parameters used in the simulation were obtained experimentally. The results showed that the experimental distributions were expressed satisfactorily by the simulation in which the parameters obtained from fatigue tests at the same stress were used. Therefore, it is concluded that corrosion fatigue life distribution can be predicted by a Monte Carlo simulation taking account of the statistical properties in the growth processes of corrosion pits and fatigue cracks.

  15. Laser assisted cold spraying of aluminium alloy powder on stainless steel substrate

    CSIR Research Space (South Africa)

    Tlotleng, Monnamme

    2012-12-01

    Full Text Available International Conference on Information Warfare and Security, Denver, USA 25-26 March 2013 LASER ASSISTED COLD SPRAYING OF ALUMINIUM ALLOY POWDER ON STAINLESS STEEL SUBSTRATE M. Tlotleng1, 2; E.O. Olakanmi2; C. Meacock; Sisa Pityana1, 3; E.T. Akinlabi2...; M. Shukla2; and M. Doyoyo2 1Department of Mechanical Engineering Science, University of Johannesburg, P.O.Box 524, Auckland Park, 2006, South Africa 2Department of Chemical and Metallurgical Engineering, Tshwane University of Technology...

  16. Metallurgical and mechanical properties of laser welded high strength low alloy steel

    OpenAIRE

    Oyyaravelu, Ramachandran; Kuppan, Palaniyandi; Arivazhagan, Natarajan

    2016-01-01

    The study aimed at investigating the microstructure and mechanical properties of Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) laser welded high strength low alloy (HSLA) SA516 grade 70 boiler steel. The weld joint for a 4 mm thick plate was successfully produced using minimum laser power of 2 kW by employing a single pass without any weld preheat treatment. The micrographs revealed the presence of martensite phase in the weld fusion zone which could be due to faster cooling rate of the la...

  17. Effects of heat treatment on properties of multi-element low alloy wear-resistant steel

    Directory of Open Access Journals (Sweden)

    SONG Xu-ding

    2007-02-01

    Full Text Available The paper has studied the mechanical properties and heat treatment effects on multi-element low alloy wear-resistant steel (MLAWS used as a material for the liner of rolling mill torii. The results show that when quenched at 900-920℃ and tempered at 350-370℃, the MLAWS has achieved hardness above 60 HRC, tensile strength greater than 1 600 MPa, impact toughness higher than 18J/cm2 and fracture toughness greater than 37 MPa

  18. Application of electrochemical impedance spectroscopy to monitor seawater fouling on stainless steels and copper alloys

    International Nuclear Information System (INIS)

    Feron, D.

    1991-01-01

    Electrochemical impedance spectroscopy may be applied to detect and to follow seawater fouling. Experiments have been conducted with natural seawater flowing inside tube-electrodes at temperatures between 30 deg C and 85 deg C. With stainless steel tubes, mineral and organic foulings have been followed; a linear relationship between the dry weight of the organic fouling and its electrical resistance, has been observed. On copper alloy tubes, only mineral deposits have occurred and so have been detected by impedance spectroscopy. (Author). 5 refs., 6 figs

  19. Elastic properties of paramagnetic austenitic steel at finite temperature: Longitudinal spin fluctuations in multicomponent alloys

    Science.gov (United States)

    Dong, Zhihua; Schönecker, Stephan; Chen, Dengfu; Li, Wei; Long, Mujun; Vitos, Levente

    2017-11-01

    We propose a first-principles framework for longitudinal spin fluctuations (LSFs) in disordered paramagnetic (PM) multicomponent alloy systems and apply it to investigate the influence of LSFs on the temperature dependence of two elastic constants of PM austenitic stainless steel Fe15Cr15Ni. The magnetic model considers individual fluctuating moments in a static PM medium with first-principles-derived LSF energetics in conjunction with describing chemical disorder and randomness of the transverse magnetic component in the single-site alloy formalism and disordered local moment (DLM) picture. A temperature-sensitive mean magnetic moment is adopted to accurately represent the LSF state in the elastic-constant calculations. We make evident that magnetic interactions between an LSF impurity and the PM medium are weak in the present steel alloy. This allows gaining accurate LSF energetics and mean magnetic moments already through a perturbation from the static DLM moments instead of a tedious self-consistent procedure. We find that LSFs systematically lower the cubic shear elastic constants c' and c44 by ˜6 GPa in the temperature interval 300-1600 K, whereas the predominant mechanism for the softening of both elastic constants with temperature is the magneto-volume coupling due to thermal lattice expansion. We find that non-negligible local magnetic moments of Cr and Ni are thermally induced by LSFs, but they exert only a small influence on the elastic properties. The proposed framework exhibits high flexibility in accurately accounting for finite-temperature magnetism and its impact on the mechanical properties of PM multicomponent alloys.

  20. Formation of nanostructured NiAl coating on carbon steel by using mechanical alloying

    International Nuclear Information System (INIS)

    Mohammadnezhad, M.; Shamanian, M.; Enayati, M.H.

    2012-01-01

    Highlights: ► Mechanical alloying process could be used for the deposition of nanostructured NiAl intermetallic coatings at ambient atmosphere. ► Thicker coatings could be formed on the substrate and produced maximum value of around 470 μm after treatment of 480 min. ► The hardness of the coating on the substrate was more than seven times that of the initial steel substrate. ► The diffraction patterns before heat treatment, suggests the NiAl intermetallic and another phase and after heat treatment, suggests completely a NiAl intermetallic at 480 min. - Abstract: Nanostructured NiAl intermetallics coatings were generated on carbon steel by using mechanical alloying in ambient temperature and pressure. Ni and Al powders were mixed with the composition of Ni–50 at% Al. The process involved powder particles trapped between the ball and cold welding at surface. Coatings were examined using X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the phase transmutation during process and subsequent heat treatment are strongly dependent on mechanical alloying time. After 480 min heat treatment of mechanically alloyed sample, only NiAl peaks were viewed. Ball encounters and failures consecutively reduced the coarse grains of the coating to the nanoscale. The size of nanocrystalline grains in the NiAl coating ranged between 28 and 130 nm. The creation of the coatings was studied at milling intervals between 60 and 600 min. The average thickness and hardness of the surface layers at 480 min, were 470 μm and 930 HV, respectively.

  1. Trace element assessment of low-alloy and stainless steels with reference to gamma activity

    International Nuclear Information System (INIS)

    Goddard, A.J.H.; Macmahon, T.D.; Gamberini, D.; Taylor, J.M.; Duggan, F.

    1984-01-01

    In order to predict the long-lived gamma activities leading to radiation exposure during dismantling operations it is necessary to know the likely trace element content of the reactor vessel and internals. This work has been concerned with measuring the elements Ni, Nb, Mo, Co, Ag, Eu, Sm and Ho in steels, with particular reference to light-water reactors. Various steel samples have been provided by organizations in Europe. Analyses have been carried out principally by neutron activation analysis, but also by atomic absorption (AA), inductively coupled plasma (ICP) and secondary ion microprobe spectrometry (SIMS). Analyses for Ni, Mo and Co were straightforward and results agreed with analyses carried out elsewhere. A variety of techniques were employed for Nb; ICP was the most successful and results were confirmed using SIMS. In the case of Ag only flameless AA yielded results for all samples. The low concentration of rare earth elements required the development of a preliminary ion exchange technique. Low-alloy steels examined had Nb concentrations less than 10 ppm. Ag levels in the vicinity of 1 ppm were found in all steel samples, indicating that Ag may be the most significant element at long cooling times. Rare earth concentrations from this and other work indicate that these elements are unlikely to give gamma activities exceeding those of 60 Co, 59 Ni, sup(108m)Ag and 94 Nb activities. Illustrative gamma activity decay calculations using the Origen code are presented

  2. High silicon steel production through hot-dipping in Al-Si-alloy and diffusion annealing

    International Nuclear Information System (INIS)

    Ros-Yanez, T.; Houbaert, Y.; Schneeweis, O.; Asensio-Lozano, J.; Prado-Garcia, M.

    2000-01-01

    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 DO 3 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. (Author) 17 refs

  3. Comparing the cyclic behavior of concrete cylinders confined by shape memory alloy wire or steel jackets

    International Nuclear Information System (INIS)

    Park, Joonam; Choi, Eunsoo; Kim, Hong-Taek; Park, Kyoungsoo

    2011-01-01

    Shape memory alloy (SMA) wire jackets for concrete are distinct from conventional jackets of steel or fiber reinforced polymer (FRP) since they provide active confinement which can be easily achieved due to the shape memory effect of SMAs. This study uses NiTiNb SMA wires of 1.0 mm diameter to confine concrete cylinders with the dimensions of 300 mm × 150 mm (L × D). The NiTiNb SMAs have a relatively wider temperature hysteresis than NiTi SMAs; thus, they are more suitable for the severe temperature-variation environments to which civil structures are exposed. Steel jackets of passive confinement are also prepared in order to compare the cyclic behavior of actively and passively confined concrete cylinders. For this purpose, monotonic and cyclic compressive loading tests are conducted to obtain axial and circumferential strain. Both strains are used to estimate the volumetric strains of concrete cylinders. Plastic strains from cyclic behavior are also estimated. For the cylinders jacketed by NiTiNb SMA wires, the monotonic axial behavior differs from the envelope of cyclic behavior. The plastic strains of the actively confined concrete show a similar trend to those of passive confinement. This study proposed plastic strain models for concrete confined by SMA wire or steel jackets. For the volumetric strain, the active jackets of NiTiNb SMA wires provide more energy dissipation than the passive jacket of steel

  4. Quantum-mechanical analysis of effect of alloying elements on ε-martensite start temperature of steels.

    Science.gov (United States)

    Jang, J H; Moon, J; Ha, H-Y; Lee, T-H; Suh, D-W

    2017-12-19

    With regard to the transformation mechanism of austenitic high manganese steel, the prediction of the ε-martensite start temperature is a critical consideration in alloy design. Evaluation of the ε-martensite start temperature makes it possible to predict the microstructure and to understand the phase transformation occurring during deformation. Here we use the quantum mechanical calculation of random alloys to understand the physics for ε-martensitic transformation in steels. We could find the linear relationship between the measured ε-martensite start temperatures and the crystal structure stability for various compositions. We also could estimate the effect of several alloying elements. It is expected that the effect of decreasing the temperatures for the same amount of alloying elements addition will be larger moving farther from Group VIII. By creating a free-energy model that reflects the temperature effect, we were able to calculate the average driving force required for the ε-martensitic transformations.

  5. Design of Helical Self-Piercing Rivet for Joining Aluminum Alloy and High-Strength Steel Sheets

    International Nuclear Information System (INIS)

    Kim, W. Y.; Kim, D. B.; Park, J. G; Kim, D. H.; Kim, K. H.; Lee, I. H.; Cho, H. Y.

    2014-01-01

    A self-piercing rivet (SPR) is a mechanical component for joining dissimilar material sheets such as those of aluminum alloy and steel. Unlike conventional rivets, the SPR directly pierces sheets without the need for drilling them beforehand. However, the regular SPR can undergo buckling when it pierces a high-strength steel sheet, warranting the design of a helical SPR. In this study, the joining and forging processes using the helical SPR were simulated using the commercial FEM code, DEFORM-3D. High-tensile-strength steel sheets of different strengths were joined with aluminum alloy sheets using the designed helical SPR. The simulation results were found to agree with the experimental results, validating the optimal design of a helical SPR that can pierce high-strength steel sheets

  6. A Study of nuclear of interest martensitic steels and FeCr ODS alloys using small angle neutron scattering

    International Nuclear Information System (INIS)

    Mathon, Marie-Helene; De Carlan, Yann; Zhong, Shengyi; Klosek, Vincent; Ji, Vincent; Henry, Jean; Olier, Patrick

    2011-01-01

    Small Angle Neutron Scattering (SANS) technique allows to characterize at a nano-scale the microstructure of the ferritic martensitic steels and ODS FeCr alloys which are candidates for the internal structures of future nuclear reactors. Firstly, the microstructure evolution induced by neutron irradiation at high dose in conventional and Reduced Activation Fe9%Cr martensitic steels is presented. Then, a SANS study of Oxide Dispersion Strengthened (ODS) alloys is also presented. The main objective is to control the nano-size oxide particles at the various stages of the fabrication process. (authors)

  7. Assessment of hydrogen cracking sensitivity of interfaces in welds between stainless and low alloy steels by a tensile separation test

    International Nuclear Information System (INIS)

    Bocquet, P.; Perrat, G.; Faure, F.; Robin, Y.

    1988-01-01

    In PWR the primary coolant circuit is coated with 23 CN 20-10 and intermediary alloys are used for welds between main components (pressure vessel, steam generators, pressurizers) made of low alloy steels and stainless steel pipes. After description of the chemical and structural particularities of the bonding zone and evidencing of the interface sensitivity to H 2 induced cracking, the paper presents the implementation of the tensile shearing test: preparation, procedure, evaluation, results achieved. The prominent role of the stress relief treatment is highlighted [fr

  8. Quantifying Recycling and Losses of Cr and Ni in Steel Throughout Multiple Life Cycles Using MaTrace-Alloy.

    Science.gov (United States)

    Nakamura, Shinichiro; Kondo, Yasushi; Nakajima, Kenichi; Ohno, Hajime; Pauliuk, Stefan

    2017-09-05

    Alloying metals are indispensable ingredients of high quality alloy steel such as austenitic stainless steel, the cyclical use of which is vital for sustainable resource management. Under the current practice of recycling, however, different metals are likely to be mixed in an uncontrolled manner, resulting in function losses and dissipation of metals with distinctive functions, and in the contamination of recycled steels. The latter could result in dilution loss, if metal scrap needed dilution with virgin iron to reduce the contamination below critical levels. Management of these losses resulting from mixing in repeated recycling of metals requires tracking of metals over multiple life cycles of products with compositional details. A new model (MaTrace-alloy) was developed that tracks the fate of metals embodied in each of products over multiple life cycles of products, involving accumulation, discard, and recycling, with compositional details at the level of both alloys and products. The model was implemented for the flow of Cr and Ni in the Japanese steel cycle involving 27 steel species and 115 final products. It was found that, under a high level of scrap sorting, greater than 70% of the initial functionality of Cr and Ni could be retained over a period of 100 years, whereas under a poor level of sorting, it could plunge to less than 30%, demonstrating the relevance of waste management technology in circular economy policies.

  9. Effect of process parameters on formability of laser melting deposited 12CrNi2 alloy steel

    Science.gov (United States)

    Peng, Qian; Dong, Shiyun; Kang, Xueliang; Yan, Shixing; Men, Ping

    2018-03-01

    As a new rapid prototyping technology, the laser melting deposition technology not only has the advantages of fast forming, high efficiency, but also free control in the design and production chain. Therefore, it has drawn extensive attention from community.With the continuous improvement of steel performance requirements, high performance low-carbon alloy steel is gradually integrated into high-tech fields such as aerospace, high-speed train and armored equipment.However, it is necessary to further explore and optimize the difficult process of laser melting deposited alloy steel parts to achieve the performance and shape control.This article took the orthogonal experiment on alloy steel powder by laser melting deposition ,and revealed the influence rule of the laser power, scanning speed, powder gas flow on the quality of the sample than the dilution rate, surface morphology and microstructure analysis were carried out.Finally, under the optimum technological parameters, the Excellent surface quality of the alloy steel forming part with high density, no pore and cracks was obtained.

  10. Rust Formation Mechanism on Low Alloy Steels after Exposure Test in High Cl− and High SOx Environment

    Science.gov (United States)

    Nishimura, Toshiyasu

    2017-01-01

    Exposure tests were performed on low alloy steels in high Cl− and high SOx environment, and the structure of the rust were analyzed by TEM (Transmission Electron Microscopy) and Raman Spectroscopy. In the exposure test site, the concentrations of Cl− and SOx were found to be high, which caused the corrosion of the steels. The conventional weathering steel (SMA: 0.6% Cr-0.4% Cu-Fe) showed higher corrosion resistance as compared to the carbon steel (SM), and Ni bearing steel exhibited the highest one. Raman spectroscopy showed that the inner rust of Ni bearing steel was mainly composed of α-FeOOH and spinel oxides. On the other hand, SMA contained β- and γ-FeOOH in inner rust, which increased the corrosion. TEM showed that nano-scale complex iron oxides containing Ni or Cr were formed in the rust on the low alloy steels, which suppressed the corrosion of steels in high Cl− and high SOx environment. PMID:28772560

  11. Rust Formation Mechanism on Low Alloy Steels after Exposure Test in High Cl− and High SOx Environmen

    Directory of Open Access Journals (Sweden)

    Toshiyasu Nishimura

    2017-02-01

    Full Text Available Exposure tests were performed on low alloy steels in high Cl− and high SOx environment, and the structure of the rust were analyzed by TEM (Transmission Electron Microscopy and Raman Spectroscopy. In the exposure test site, the concentrations of Cl− and SOx were found to be high, which caused the corrosion of the steels. The conventional weathering steel (SMA: 0.6% Cr-0.4% Cu-Fe showed higher corrosion resistance as compared to the carbon steel (SM, and Ni bearing steel exhibited the highest one. Raman spectroscopy showed that the inner rust of Ni bearing steel was mainly composed of α-FeOOH and spinel oxides. On the other hand, SMA contained β- and γ-FeOOH in inner rust, which increased the corrosion. TEM showed that nano-scale complex iron oxides containing Ni or Cr were formed in the rust on the low alloy steels, which suppressed the corrosion of steels in high Cl− and high SOx environment.

  12. Rust Formation Mechanism on Low Alloy Steels after Exposure Test in High Cl- and High SOx Environmen.

    Science.gov (United States)

    Nishimura, Toshiyasu

    2017-02-17

    Exposure tests were performed on low alloy steels in high Cl- and high SOx environment, and the structure of the rust were analyzed by TEM (Transmission Electron Microscopy) and Raman Spectroscopy. In the exposure test site, the concentrations of Cl- and SOx were found to be high, which caused the corrosion of the steels. The conventional weathering steel (SMA: 0.6% Cr-0.4% Cu-Fe) showed higher corrosion resistance as compared to the carbon steel (SM), and Ni bearing steel exhibited the highest one. Raman spectroscopy showed that the inner rust of Ni bearing steel was mainly composed of α-FeOOH and spinel oxides. On the other hand, SMA contained β- and γ-FeOOH in inner rust, which increased the corrosion. TEM showed that nano-scale complex iron oxides containing Ni or Cr were formed in the rust on the low alloy steels, which suppressed the corrosion of steels in high Cl- and high SOx environment.

  13. Grain boundary phosphorus segregation under thermal aging in low alloy steels

    International Nuclear Information System (INIS)

    Nakata, Hayato; Fujii, Katsuhiko; Fukuya, Koji; Kasada, Ryuta; Kimura, Akihiko

    2007-01-01

    Intergranular embrittlement due to grain boundary segregation of phosphorus is recognized as one of the potential degradation factors in irradiated reactor low alloy steels at high neutron fluence. In this study, low alloy steels thermally aged at 400-500degC were investigated to evaluate the correlation between phosphorus segregation and intergranular embrittlement. Phosphorus segregation determined using Auger electron spectroscopy increased after thermal aging above 450degC and was in good agreement with the calculated value based on McLean's model. No influence of thermal aging on tensile properties or hardness was observed. The ductile brittle transition temperature determined using a one-third size Charpy impact test increased at a P/Fe peak ratio of 0.14. These results indicated that there is a threshold level of phosphorus segregation for non-hardening embrittlement. DBTT increased with the proportion of intergranular fracture, so this result shows that there is a relationship between DBTT and the properties of intergranular fracture. The fracture stress decreases due to non-hardening embrittlement on the thermally aged material with high proportion of intergranular fracture. (author)

  14. Low temperature mechanical properties, fractographic and metallographic evaluation of several alloy steels

    Science.gov (United States)

    Montano, J. W.

    1973-01-01

    The mechanical properties are presented of alloy steels, 4130, 4140, 4340, 6150, and 8740. Test specimens were manufactured from approximately 1.00 inch (2.54 cm) diameter bar stock which had been heat treated to two different hardness levels. The following mechanical tests were performed at temperatures of 80 F (+26.7 C), 0 F (-17.8 C), -100 F (-73 C), and -200 F (-129 C): (1) tensile test (Ultimate, yield, modulus, elongation, and reduction of area), (2) notched tensile test, (3) charpy V-notched impact test (impact energy), and (4) double shear strength test (ultimate and yield). The test data indicate excellent tensile strength, notched/unnotched tensile ratios, ductility, impact, and shear properties at all test temperatures, except at -200 F (-129 C) where the impact strength of the higher strength group of alloy steels, 4130 (Rc-37) and 4140 (Rc-44) decreased to approximately 9 ft. lbs. (12 joules) and 6 ft. lbs. (8 joules), respectively. Chemical, metallographic, and fractographic analyses were also performed to evaluate microstructure, microhardness and the effect of decrease in temperature on the ductile to brittle failure transition.

  15. High corrosion resistance of austenitic stainless steel alloyed with nitrogen in an acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Metikos-Hukovic, M., E-mail: mmetik@fkit.h [Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Savska 16, P.O. Box 177, 100000 Zagreb (Croatia); Babic, R. [Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Savska 16, P.O. Box 177, 100000 Zagreb (Croatia); Grubac, Z. [Department of General and Inorganic Chemistry, Faculty of Chemistry and Technology, University of Split, 21000 Split (Croatia); Petrovic, Z. [Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Savska 16, P.O. Box 177, 100000 Zagreb (Croatia); Lajci, N. [Faculty of Mine and Metallurgy, University of Prishtina, 10000 Prishtina, Kosovo (Country Unknown)

    2011-06-15

    Highlights: {yields} ASS alloyed with nitrogen treated at 1150 {sup o}C exhibits microstructure homogeneity. {yields} Passivation peak of ASS corresponds to oxidation of metal and absorbed hydrogen. {yields} Transfer phenomena and conductivity depend on the film formation potential. {yields} Electronic structure of the passive film and its corrosion resistance correlate well. {yields} Passive film on ASS with nitrogen is low disordered and high corrosion resistant. - Abstract: Passivity of austenitic stainless steel containing nitrogen (ASS N25) was investigated in comparison with AISI 316L in deareated acid solution, pH 0.4. A peculiar nature of the passivation peak in a potentiodynamic curve and the kinetic parameters of formation and growth of the oxide film have been discussed. The electronic-semiconducting properties of the passive films have been correlated with their corrosion resistance. Alloying austenitic stainless steel with nitrogen increases its microstructure homogeneity and decreases the concentration of charge carriers, which beneficially affects the protecting and electronic properties of the passive oxide film.

  16. Mechanical properties of low-alloy-steels with bainitic microstructures and varying carbon content

    Science.gov (United States)

    Weber, A.; Klarner, J.; Vogl, T.; Schöngrundner, R.; Sam, G.; Buchmayr, B.

    2016-03-01

    Materials used in the oilfield industry are subjected to special conditions. These requirements for seamless steel tubes are between the priorities of strength, toughness and sour gas resistance. Steels with bainitic microstructure provide a great opportunity for those harsh environmental conditions. With different morphologies of bainite, like carbide free, upper or lower bainite, the interaction of high tensile strength and elongation is assumed to be better than with tempered martensite. To form carbide free bainite two ways of processing are proposed, isothermal holding with accurate time control or controlled continuous cooling. Both require knowledge of time-temperature transformation behaviour, which can be reached through a detailed alloying concept, focused on the influence of silicon to supress the carbide nucleation and chromium to stabilize the austenite fraction. The present work is based on three alloys with varying silicon and chromium contents. The carbide free microstructure is obtained by a continuous cooling path. Additionally different heat treatments were done to compare the inherent performance of the bainitic morphologies. The bainitic structures were characterized metallographically for their microstructure and the primary phase by means of transmission electron microscopy. The mechanical properties of carbide-free structures were analysed with quasi-static tensile tests and Charpy impact tests. Moreover, investigations about hydrogen embrittlement were done with focus on the effect of retained austenite. The results were ranked and compared qualitatively.

  17. Virtual Testing of Composite Structures Made of High Entropy Alloys and Steel

    Directory of Open Access Journals (Sweden)

    Victor Geantă

    2017-11-01

    Full Text Available High entropy alloys (HEA are metallic materials obtained from a mixture of at least five atomic-scale chemical elements. They are characterized by high mechanical strength, good thermal stability and hardenability. AlCrFeCoNi alloys have high compression strength and tensile strength values of 2004 MPa, respectively 1250 MPa and elongation of about 32.7%. These materials can be used to create HEA-steel type composite structures which resist to dynamic deformation during high speed impacts. The paper presents four different composite structures made from a combination of HEA and carbon steel plates, using different joining processes. The numerical simulation of the impact behavior of the composite structures was performed by virtual methods, taking into account the mechanical properties of both materials. For analyzing each constructive variant, three virtual shootings were designed, using a 7.62 × 39 mm cal. incendiary armor-piercing bullet and different impact velocities. The best ballistic behavior was provided by the composite structures obtained by welding and brazing that have good continuity and rigidity. The other composite structures, which do not have good surface adhesion, show high fragmentation risk, because the rear plate can fragment on the axis of shooting due to the combination between the shock waves and the reflected ones. The order of materials in the composite structure has a very important role in decreasing the impact energy.

  18. Novel Dissimilar Joints Between Alloy 800H and 2.25%Cr and 1%Mo Steel

    Energy Technology Data Exchange (ETDEWEB)

    DebRoy, Tarasankar

    2017-12-31

    Dissimilar metal joints between ferritic steels and nickel base alloys are currently fabricated using conventional arc welding processes with selected filler metal combinations. The dissimilar metal joints contain abrupt changes in composition over a relatively small distance. Many years of service at elevated temperatures has shown that these welds are susceptible to creep and creep fatigue failures. The primary mechanism for these creep failures involves carbon diffusion from the ferritic steel to the nickel base alloy. As a result, a carbon depleted zone is created that contains very few stable carbides. This work used additive manufacturing (AM) technologies as a highly controllable means for reducing carbon migration through theoretically designed, compositionally graded transition joints guided by appropriate thermodynamic, kinetic and heat transfer and fluid flow modeling. The contents of the report include the objectives and tasks set forth by the PI and collaborators, major technical accomplishments throughout the research and additional details in the form of technical publications resulting from the NEUP grant and reports from the collaborating university and national laboratory.

  19. Initial bacterial deposition on bare and zeolite-coated aluminum alloy and stainless steel.

    Science.gov (United States)

    Chen, Gexin; Beving, Derek E; Bedi, Rajwant S; Yan, Yushan S; Walker, Sharon L

    2009-02-03

    In this study, the impact of zeolite thin film coatings on bacterial deposition and "biofouling" of surfaces has been investigated in an aqueous environment. The synthesis of two types of zeolite coatings, ZSM-5 coated on aluminum alloy and zeolite A coated on stainless steel, and the characterization of the coated and bare metal surfaces are described. The extent of cell deposition onto the bare and zeolite-coated aluminum alloy and stainless steel surfaces is investigated in a parallel plate flow chamber system under a laminar flow conditions. The initial rates of bacterial transfer to the various surfaces are compared by utilizing a marine bacterium, Halomonas pacifica g, under a range of ionic strength conditions. H. pacifica g deposited onto bare metal surfaces to a greater extent as compared with cells deposited onto the zeolite coatings. The surface properties found to have the most notable effect on attachment are the electrokinetic and hydrophobicity properties of the metal and zeolite-coated surfaces. These results suggest that a combination of two chemical mechanisms-hydrophobic and electrostatic interactions-contribute to the antifouling nature of the zeolite surface. Additional observations on the relative role of the hydrodynamic and physical phenomena are also discussed.

  20. Indoor accelerated corrosion test and marine field test of corrosion-resistant low-alloy steel rebars

    Directory of Open Access Journals (Sweden)

    Ming Liu

    2016-12-01

    Full Text Available Macrocell corrosion test and accelerated alternating wet–dry experiment combined with marine field test were employed to study the corrosion behavior of HRB400 carbon steel, 1.5Cr steel, and 5Cr steel in a simulated concrete pore solution and mortar. The macrocell current significantly decreases in samples added with Cr compared with that in HRB400 steel. The corrosion rate is decreased by Cr but increased by Cl−; as a consequence, the corrosion rates of 1.5Cr and 5Cr steel are lower than that of HRB400 steel. However, the corrosion products differ slightly in terms of the contents of α-FeOOH (goethite, γ-FeOOH (lepidocrocite, γ-Fe2O3, and Fe3O4 (maghemite or magnetite. The addition of Cr increases the content of the protective α-FeOOH and reduces the content of γ-FeOOH. Both ordinary and high-performance epoxy coatings remain intact after 1 year of marine field test. Among the bare steel rebars, HRB400 steel shows extensive localized corrosion on the surface, whereas 1.5Cr steel exhibits less severe corrosion. The scarcely visible corroded areas in 5Cr steel indicate that this rebar is in the passive state, consistent with results of the indoor accelerated test. Hence, the durability of concrete structures can be prolonged with the utilization of corrosion-resistant low-alloy rebars.

  1. Effects of material and loading variables on fatigue life of carbon and low-alloy steels in LWR environments

    International Nuclear Information System (INIS)

    Chopra, O.K.; Shack, W.J.

    1995-03-01

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Section III of the Code specifies fatigue design curves for structural materials. While effects of reactor coolant environments are not explicitly addressed by the design curves, test data suggest that the Code fatigue curves may not always be adequate in coolant environments. This paper reports the results of recent fatigue tests that examine the effects of steel type, strain rate, dissolved oxygen level, strain range, loading waveform, and surface morphology on the fatigue life of A106-Gr B carbon steel and A533-Gr B low-alloy steel in water

  2. Fabrication of Fe-Cr-Mo powder metallurgy steel via a mechanical-alloying process

    Science.gov (United States)

    Park, Jooyoung; Jeong, Gowoon; Kang, Singon; Lee, Seok-Jae; Choi, Hyunjoo

    2015-11-01

    In this study, we employed a mechanical-alloying process to manufacture low-alloy CrL and CrM steel powders that have similar specifications to their water-atomized counterparts. X-ray diffraction showed that Mo and Cr are alloyed in Fe after four cycles of planetary milling for 1 h at 150 RPM with 15-min pauses between the cycles (designated as P2C4 process). Furthermore, the measured powder size was found to be similar to that of the water-atomized counterparts according to both scanning electron microscope images and laser particle size analysis. The samples were sintered at 1120 °C, after which the P2C4-milled CrL showed similar hardness to that of water-atomized CrL, whereas the P2C4-milled CrM showed about 45% lower hardness than that of its water-atomized counterpart. Water-atomized CrM consists of a well-developed lathtype microstructure (bainite or martensite), while a higher fraction of polygonal ferrite is observed in P2C4-milled CrM. This phase difference causes the reduction of hardness in the P2C4-milled CrM, implying that the phase transformation behavior of specimens produced via powder metallurgy is influenced by the powder fabrication method.

  3. A study of microstructure, quasi-static response, fatigue, deformation and fracture behavior of high strength alloy steels

    Science.gov (United States)

    Kannan, Manigandan

    The history of steel dates back to the 17th century and has been instrumental in the betterment of every aspect of our lives ever since, from the pin that holds the paper together to the Automobile that takes us to our destination steel touches everyone every day. Path breaking improvements in manufacturing techniques, access to advanced machinery and understanding of factors like heat treatment, corrosion resistance have aided in the advancement in the properties of steel in the last few years. In this dissertation document, the results of a study aimed at the influence of alloy chemistry, processing and influence of the quasi static and fatigue behavior of seven alloy steels is discussed. The microstructure of the as-received steel was examined and characterized for the nature and morphology of the grains and the presence of other intrinsic features in the microstructure. The tensile, cyclic fatigue and bending fatigue tests were done on a fully automated closed-loop servo-hydraulic test machine at room temperature. The failed samples of high strength steels were examined in a scanning electron microscope for understanding the fracture behavior, especially the nature of loading be it quasi static, cyclic fatigue or bending fatigue . The quasi static and cyclic fatigue fracture behavior of the steels examined coupled with various factors contributing to failure are briefly discussed in light of the conjoint and mutually interactive influences of intrinsic microstructural effects, nature of loading, and stress (load)-deformation-microstructural interactions.

  4. Threshold velocity for environmentally-assisted cracking in low alloy steels

    International Nuclear Information System (INIS)

    Wire, G.L.; Kandra, J.T.

    1997-01-01

    Environmentally Assisted Cracking (EAC) in low alloy steels is generally believed to be activated by dissolution of MnS inclusions at the crack tip in high temperature LWR environments. EAC is the increase of fatigue crack growth rate of up to 40 to 100 times the rate in air that occurs in high temperature LWR environments. A steady state theory developed by Combrade, suggested that EAC will initiate only above a critical crack velocity and cease below this same velocity. A range of about twenty in critical crack tip velocities was invoked by Combrade, et al., to describe data available at that time. This range was attributed to exposure of additional sulfides above and below the crack plane. However, direct measurements of exposed sulfide densities on cracked specimens were performed herein and the results rule out significant additional sulfide exposure as a plausible explanation. Alternatively, it is proposed herein that localized EAC starting at large sulfide clusters reduces the calculated threshold velocity from the value predicted for a uniform distribution of sulfides. Calculations are compared with experimental results where the threshold velocity has been measured, and the predicted wide range of threshold values for steels of similar sulfur content but varying sulfide morphology is observed. The threshold velocity decreases with the increasing maximum sulfide particle size, qualitatively consistent with the theory. The calculation provides a basis for a conservative minimum velocity threshold tied directly to the steel sulfur level, in cases where no details of sulfide distribution are known

  5. Growth of creep life of type-347H austenitic stainless steel by micro-alloying elements

    International Nuclear Information System (INIS)

    Research highlights: → B, Ce and N can improve the creep life significantly at high temperature. → The precipitate of B element at the grain boundaries can improve the creep life. → The removing O through Ce provided the steel with longer creep life. → N increased the creep life by stabilizing austenite and solid solution strengthening. - Abstract: The creep life of type-347H austenitic stainless steel modified with B, Ce and N was measured, and microstructures were analyzed by optical microscope, X-ray diffraction, scanning electron microscope and transmission electron microscope equipped with energy dispersive spectroscopy. The results indicate that B, Ce and N can improve the creep life significantly at high temperature. The growth of creep life was mainly due to the precipitate of B in the elemental form at the grain boundaries and the removing O through Ce. N addition made for solid solution strengthening and effectively suppressed the precipitate of δ-ferrite at high temperature. The micro-alloying elements have a beneficial effect on creep life of type-347H austenitic stainless steel at high temperature.

  6. Finite element method analysis of cold forging for deformation and densification of Mo alloyed sintered steel

    Science.gov (United States)

    Kamakoshi, Y.; Nishida, S.; Kanbe, K.; Shohji, I.

    2017-10-01

    In recent years, powder metallurgy (P/M) materials have been expected to be applied to automobile products. Then, not only high cost performance but also more strength, wear resistance, long-life and so on are required for P/M materials. As an improvement method of mechanical properties of P/M materials, a densification is expected to be one of effective processes. In this study, to examine behaviours of the densification of Mo-alloyed sintered steel in a cold-forging process, finite element method (FEM) analysis was performed. Firstly, a columnar specimen was cut out from the inner part of a sintered specimen and a load-stroke diagram was obtained by the compression test. 2D FEM analysis was performed using the obtained load-stroke diagram. To correct the errors of stress between the porous mode and the rigid-elastic mode of analysis software, the analysis of a polynominal approximation was performed. As a result, the modified true stress-true strain diagram was obtained for the sintered steel with the densification. Afterwards, 3D FEM analysis of backward extrusion was carried out using the modified true stress-true strain diagram. It was confirmed that both the shape and density of the sintered steel analyzed by new FEM analysis that we suggest correspond well with experimental ones.

  7. Effects of LWR coolant environments on fatigue design curves of carbon and low-alloy steels

    International Nuclear Information System (INIS)

    Chopra, O.K.; Shack, W.J.

    1998-03-01

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Figures I-9.1 through I-9.6 of Appendix I to Section III of the code specify fatigue design curves for structural materials. While effects of reactor coolant environments are not explicitly addressed by the design curves, test data indicate that the Code fatigue curves may not always be adequate in coolant environments. This report summarizes work performed by Argonne National Laboratory on fatigue of carbon and low-alloy steels in light water reactor (LWR) environments. The existing fatigue S-N data have been evaluated to establish the effects of various material and loading variables such as steel type, dissolved oxygen level, strain range, strain rate, temperature, orientation, and sulfur content on the fatigue life of these steels. Statistical models have been developed for estimating the fatigue S-N curves as a function of material, loading, and environmental variables. The results have been used to estimate the probability of fatigue cracking of reactor components. The different methods for incorporating the effects of LWR coolant environments on the ASME Code fatigue design curves are presented

  8. Microstructural evolution at the overlap zones of 12Cr martensitic stainless steel laser alloyed with TiC

    CSIR Research Space (South Africa)

    Adebiyi, DI

    2014-09-01

    Full Text Available are not obtainable in the single tracks. X12CrNiMo steel has been laser alloyed with TiC using a 4.4 kW continuous wave (CW) Nd:YAG laser. The process parameters were first optimised after which they were kept constant for overlap ratios of 50% and 75%. The depths...

  9. 78 FR 33103 - Carbon and Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova, Trinidad and...

    Science.gov (United States)

    2013-06-03

    ... Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova, Trinidad and Tobago, and Ukraine... antidumping duty orders on wire rod from Brazil, Indonesia, Mexico, Moldova, Trinidad and Tobago, and Ukraine..., Mexico, Moldova, Trinidad and Tobago, and Ukraine (67 FR 65944-65947). Following the five-year reviews by...

  10. 78 FR 60316 - Carbon and Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova, Trinidad and...

    Science.gov (United States)

    2013-10-01

    ... Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova, Trinidad and Tobago, and Ukraine..., Indonesia, Mexico, Moldova, Trinidad and Tobago, and Ukraine would be likely to lead to continuation or... interested party group responses with respect to subject imports from Brazil, Indonesia, Moldova, Trinidad...

  11. 78 FR 63450 - Carbon and Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova, Trinidad and...

    Science.gov (United States)

    2013-10-24

    ..., Moldova, Trinidad and Tobago, and Ukraine: Final Results of the Expedited Second Sunset Reviews of the... on carbon and certain alloy steel wire rod (``wire rod'') from Brazil, Indonesia, Mexico, Moldova... Brazil, Indonesia, Mexico, Moldova, Trinidad and Tobago, and Ukraine, pursuant to section 751(c) of the...

  12. 78 FR 76653 - Carbon and Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova, Trinidad and...

    Science.gov (United States)

    2013-12-18

    ... Certain Alloy Steel Wire Rod From Brazil, Indonesia, Mexico, Moldova, Trinidad and Tobago, and Ukraine... from Brazil, Indonesia, Mexico, Moldova, Trinidad and Tobago, and Ukraine. AGENCY: United States... Brazil, Indonesia, Mexico, Moldova, Trinidad and Tobago, and Ukraine would be likely to lead to...

  13. Dispersion of the structure of steels under intense thermal effect. Part 1. Choice of optimum alloying system

    Science.gov (United States)

    Zayats, L. Ts.; Panov, D. O.; Simonov, Yu. N.

    2011-03-01

    Results of a complex study of the kinetics of transformations, structure, and characteristics of mechanical properties of low-carbon alloy steels are used to formulate principles for designing chemical composition. The principles make it possible to lower the factor of carbon activity and to raise the resistance of the system to diffusion relaxation, which promotes dispersion of the structure in heat treatment.

  14. Tempering of martensitic steel for fasteners : Effects of micro-alloying on microstructure and mechanical property evolution

    NARCIS (Netherlands)

    Öhlund, C.E.I.C.

    2015-01-01

    The research presented in this thesis aims to deepen our understanding of the effect of micro-alloying on the microstructure and mechanical property evolution during tempering of martensitic steel for fasteners. The ongoing trend of engine down-sizing has led to the need for stronger and more

  15. 75 FR 20342 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Final Results of Antidumping Duty...

    Science.gov (United States)

    2010-04-19

    ... covered in this review, but was covered in a previous review or the original less-than-fair-value (LTFV... investigation. See Final Determination of Sales at Less Than Fair Value: Circular Welded Non- Alloy Steel Pipe... for framing and support members for reconstruction or load-bearing purposes in the construction...

  16. 76 FR 77770 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Final Results of Antidumping Duty...

    Science.gov (United States)

    2011-12-14

    ... previous review or the original less-than-fair-value (LTFV) investigation, the cash deposit rate will... Determination of Sales at Less Than Fair Value: Circular Welded Non-Alloy Steel Pipe From Mexico, 57 FR 42953... structural pipe tubing used for framing and support members for reconstruction or load-bearing purposes in...

  17. 76 FR 36089 - Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Final Results of the Antidumping...

    Science.gov (United States)

    2011-06-21

    ..., or the original less-than-fair-value (``LTFV'') investigation, but the manufacturer is, the cash... Determination of Sales at Less Than Fair Value: Certain Circular Welded Non-Alloy Steel Pipe from Korea, 57 FR... for reconstruction or load- bearing purposes in the construction, shipbuilding, trucking, farm...

  18. 76 FR 49437 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Preliminary Results of Antidumping Duty...

    Science.gov (United States)

    2011-08-10

    ... to Final Determination of Sales at Less Than Fair Value: Certain Welded Non-Alloy Steel Pipe from... established in the less-than-fair-value investigation (32.62 percent) if there is no rate for the intermediary... pipe tubing used for framing and support members for reconstruction or load-bearing purposes in the...

  19. The effect of stainless steel, cobalt-chromium, titanium alloy, and titanium on the respiratory burst activity of human polymorphonuclear leukocytes.

    Science.gov (United States)

    Pascual, A; Tsukayama, D T; Wicklund, B H; Bechtold, J E; Merritt, K; Peterson, P K; Gustilo, R B

    1992-07-01

    Although infection is a serious complication associated with the use of orthopedic prosthetic implants, the impact of the metal used in these devices on host defense is poorly understood. The authors investigated the effect of stainless steel, titanium, titanium alloy, and cobalt-chromium alloy on the respiratory burst of polymorphonuclear leukocytes (PMN), a vital component of bactericidal activity. In the presence of stainless steel powder or supernatants obtained from the incubation of stainless steel in buffer, superoxide production by PMN was significantly impaired. Titanium, titanium alloy, and cobalt-chrome alloy had no significant effect on superoxide production. Nickel and chromium, the only metal ions detectable in the stainless steel supernatant, did not impair superoxide production when tested at concentrations similar to those found in the supernatant. Inhibition of PMN superoxide production may play a role in the establishment and persistence of stainless steel device-related infections.

  20. Effect of Heat Treatment, Pre-stress and Surface Hardening on Fracture Toughness of Micro-Alloyed Steel

    Science.gov (United States)

    Nag Chaudhury, Joydeb

    2014-01-01

    Micro-alloyed steels are being increasingly accepted by industry in various fields of application and are available with a wide variety of microstructures. Extensive literature is available on their microstructure-property relationships. The superior mechanical properties of micro-alloyed steels are caused by fine-grained microstructures and precipitation of micro-alloying elements such as V, Ti and Nb that led to an improvement in yield strength, in the product of tensile strength and total elongation and in Charpy V-notch impact energy as well. The microstructural changes caused by heat treatment or residual stress state caused by surface hardening or mechanical means may influence the fracture toughness of these micro-alloyed steels. It is in this context that the present work begins with experimental determination of quasi-static initiation fracture toughness ( J 1c) of low carbon (0.19%) micro-alloyed steel in as-rolled condition without any heat treatment. The study further explores the effect of normalizing, shot-peening and cyaniding followed by shot-peening on fracture toughness of as-rolled steel under study. The normalizing heat treatment, shot-peening and cyaniding followed by shot-peening—each indicates a positive influence on initiation fracture toughness. Results, when compared, show that cyaniding followed by shot-peening have led to a 2.7 times increase in J 1c. Cyaniding followed by shot-peening may therefore be considered as having the most positive influence on initiation fracture toughness in as-rolled condition for the type of micro-alloyed steel under study. Although initiation fracture toughness is in general known to decrease with increase in yield strength in LEFM arena, the micro-alloyed steel under study when normalized displayed simultaneous improvement in yield strength and J 1c. All these observed effects of normalizing, shot-peening and cyaniding on initiation fracture toughness (elastic-plastic fracture mechanics) were explained

  1. Overload effects on a ferritic-baintic steel and a cast aluminium alloy: two very different behaviours

    Energy Technology Data Exchange (ETDEWEB)

    Saintier, N. [Arts et Metiers Paris Tech, I2M, UMR CNRS, Universite Bordeaux 1, Talene Cedex (France); El Dsoki, C.; Kaufmann, H.; Sonsino, C.M. [Fraunhofer-Institute for Structural Durability and System Reliability LBF, Darmstadt (Germany); Dumas, C. [RENAULT, Technocentre, Guyancourt Cedex (France); Voellmecke, F.J. [BORBET GmbH, Hallenberg-Hesborn (Germany); Palin-Luc, T.; Bidonard, H.

    2011-10-15

    Load controlled fatigue tests were performed up to 10{sup 7} cycles on flat notched specimens (K{sub t} = 2.5) under constant amplitude and variable amplitude loadings with and without periodical overloads. Two materials are studied: a ferritic-bainitic steel (HE400M steel) and a cast aluminium alloy (AlSi7Mg0.3). These materials have a very different cyclic behaviour: the steel exhibits cyclic strain softening whereas the Al alloy shows cyclic strain hardening. The fatigue tests show that, for the steel, periodical overload applications reduce significantly the fatigue life for fully reversed load ratio (R{sub {sigma}} = -1), while they have no influence under pulsating loading (R{sub {sigma}} = 0). For the Al alloy overloads have an effect (fatigue life decreasing) only for variable amplitude loadings. The detrimental effect of overloads on the steel is due to ratcheting at the notch root which evolution is overload's dependent. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. [Studies on the recovery of pharmaceutical drug substances from surfaces made of defined stainless-steel alloys].

    Science.gov (United States)

    Kloss, S; Müller, U; Oelschläger, H

    2005-09-01

    Facilities for the manufacturing of pharmaceutical drug substances on the pilot-plant and the industrial scale as well as chemical reactors and vessels used for chemical work-up mainly consist of alloyed stainless steel. The influence of the alloy composition and the surface condition, i.e. of the roughness of the stainless-steel materials, on the adsorption of structurally diverse steroidal substances and, hence, on the quality of the products was studied. In general, stainless-steel alloys with smooth, not so rough surfaces are to be favored as reactor material. However, it was demonstrated in this study that, on account of the weak interaction between active substances and steel materials, mechanically polished materials of a medium roughness up to approx. 0.4 microm can be employed instead of the considerably more cost-intensive electrochemically polished stainless-steel surfaces. The type of surface finishing up to a defined roughness, then, has no influence on the quality of these pharmaceutical products. Substances that, because of their molecular structure, can function as "anions" in the presence of polar solvents, are adsorbed on very smooth surfaces prepared by electrochemical methods, forming an amorphous surface film. For substances with this structural characteristics, the lower-cost mechanically polished reactor materials of a medium roughness up to approx. 0.5 microm should be used exclusively.

  3. The Effect of Vanadium on Morphology and Chemical Composition of Carbides in High Alloyed Chromium-Molybdenum Steels

    Science.gov (United States)

    Todić, Aleksandar; Pejović, Branko; Todić, Tomislav; Čamagić, Ivica

    2017-12-01

    Despite of the permanent progress of technique and finding of the new, modern materials that successfully replace metals, steel continues to play an important role in the technical practice. The tendency is to discover the new alloys with better mechanical and technological characteristics, compared to conventional and standard types of steels. High-alloyed Cr-Mo steel, with a high content of Vanadium is the new type of wear resistant material, with high hardness and satisfactory impact and fracture toughness. During the solidification process Vanadium, as a strong carbide forming element, creates a network of M7C3 type carbide grains around the metal matrix, while in the matrix, the finely dispersed V6C5 type carbides are formed. In this paper, the chemical composition and morphology have been studied of carbides and the other phases present in the metal matrix in 1.4 wt % C, 12 wt % Cr, 1.0 wt % Mo steels with additions up to 3.0 wt % V. Experimental results indicate that Vanadium affects the solidification process in high Chromium steel. Vanadium is distributed between eutectic M7C3 carbide and the matrix, but its content in carbides is considerably higher. Vanadium changed the microstructure parameters of phases present in the structure of alloys, including volume fraction, size and morphology.

  4. Evaluation of Stress Corrosion Cracking Susceptibility Using Fracture Mechanics Techniques, Part 1. [environmental tests of aluminum alloys, stainless steels, and titanium alloys

    Science.gov (United States)

    Sprowls, D. O.; Shumaker, M. B.; Walsh, J. D.; Coursen, J. W.

    1973-01-01

    Stress corrosion cracking (SSC) tests were performed on 13 aluminum alloys, 13 precipitation hardening stainless steels, and two titanium 6Al-4V alloy forgings to compare fracture mechanics techniques with the conventional smooth specimen procedures. Commercially fabricated plate and rolled or forged bars 2 to 2.5-in. thick were tested. Exposures were conducted outdoors in a seacoast atmosphere and in an inland industrial atmosphere to relate the accelerated tests with service type environments. With the fracture mechanics technique tests were made chiefly on bolt loaded fatigue precracked compact tension specimens of the type used for plane-strain fracture toughness tests. Additional tests of the aluminum alloy were performed on ring loaded compact tension specimens and on bolt loaded double cantilever beams. For the smooth specimen procedure 0.125-in. dia. tensile specimens were loaded axially in constant deformation type frames. For both aluminum and steel alloys comparative SCC growth rates obtained from tests of precracked specimens provide an additional useful characterization of the SCC behavior of an alloy.

  5. Effect of mechanical alloying atmosphere on the microstructure and Charpy impact properties of an ODS ferritic steel

    International Nuclear Information System (INIS)

    Oksiuta, Z.; Baluc, N.

    2009-01-01

    Two types of oxide dispersion strengthened (ODS) ferritic steels, with the composition of Fe-14Cr-2W-0.3Ti-0.3Y 2 O 3 (in weight percent), have been produced by mechanically alloying elemental powders of Fe, Cr, W, and Ti with Y 2 O 3 particles either in argon atmosphere or in hydrogen atmosphere, degassing at various temperatures, and compacting the mechanically alloyed powders by hot isostatic pressing. It was found in particular that mechanical alloying in hydrogen yields a significant reduction in oxygen content in the materials, a lower dislocation density, and a strong improvement in the fast fracture properties of the ODS ferritic steels, as measured by Charpy impact tests.

  6. Effects of alloying elements and thermomechanical treatment on 9Cr Reduced Activation Ferritic–Martensitic (RAFM) steels

    International Nuclear Information System (INIS)

    Tan, L.; Yang, Y.; Busby, J.T.

    2013-01-01

    RAFM steels are one of the candidate structural materials for fusion reactors, in which tantalum (Ta) and tungsten (W) are alloyed to replace niobium (Nb) and molybdenum (Mo) in conventional FM steels, respectively. This paper, using three RAFM heats, presents the effects of Ta and the primary austenite stabilizer carbon (C) on microstructure and strength. Thermomechanical treatment (TMT) was also applied to the heats, leading to significant increases in strength, attributable to the TMT-refined sub-grains and precipitates. The Ta-alloying favored the formation of (V, Ta)(N, C) and (Ta, V)C and exhibited greater strength. Fractographs also revealed the beneficial effects of TMT and Ta-alloying. However, extra C content, favoring a larger amount of M 23 C 6 precipitates, did not show strengthening effect

  7. Cessation of environmentally-assisted cracking in a low-alloy steel: Theoretical analysis

    International Nuclear Information System (INIS)

    Wire, G.L.

    1997-01-01

    Environmentally Assisted Cracking (EAC) can cause increases in fatigue crack growth rates of 40 to 100 times the rate in air for low alloy steels. The increased rates can lead to very large predicted crack growth. EAC is activated by a critical level of dissolved sulfides at the crack tip. Sulfide inclusions (MnS) in the steel produce corrosive sulfides in solution following exposure by a growing crack. In stagnant, low oxygen water conditions considered here, diffusion is the dominant mass transport mechanism acting to change the sulfide concentration within the crack. The average crack tip velocity is below the level required to produce the critical crack tip sulfide ion concentration required for EAC. Crack extension analyses also consider the breakthrough of large, hypothetical embedded defects with the attendant large freshly exposed sulfide inventory. Combrade et al. noted that a large inventory of undissolved metallurgical sulfides on crack flanks could trigger EAC, but did not quantify the effects. Diffusion analysis is extended herein to cover breakthrough of embedded defects with large sulfide inventories. The mass transport via diffusion is limited by the sulfide solubility. As a result, deep cracks in high sulfur steels are predicted to retain undissolved sulfides for extended but finite periods of time t diss which increase with the crack length and the metallurgical sulfide content in the steel. The analysis shows that the duration of EAC is limited to t diss providing V eac , the crack tip velocity associated with EAC is less than V In , the crack tip velocity below which EAC will not occur in an initially sulfide free crack. This condition on V eac need only be met for a short time following crack cleanup to turn off EAC. The predicted crack extension due to limited duration of EAC is a small fraction of the initial embedded defect size and would not greatly change calculated crack depths

  8. Effect of (Ti, Al)N Nanostructured Arc-Coatings on Wear and Corrosion Properties of 4340 Alloy Steel.

    Science.gov (United States)

    Hsu, Cheng-Hsun; Lin, Chung-Kwei; Huang, Wei-Che; Lai, Dai-Wei

    2018-04-01

    This study utilized cathodic arc deposition technology to coat Ti-Al-N hard films on AISI 4340 alloy steel. Composition, morphology, and structure of the coatings were analyzed using EPMA, FESEM, XRD, and TEM. Both wear tests and polarization tests were conducted to determine the abrasion and corrosion properties of the steel before and after coating. The results showed that a specific (Ti, Al)N nanostructured multilayer was synthesized smoothly. The multilayer consisted of 10 nm-TiN and 15 nm-TiAlN interaction layers. The coating not only greatly reduced the friction coefficient of AISI 4340 alloy steel from 0.81 to 0.45, but also provided an effective improvement in corrosion resistance.

  9. Microstructures and mechanical properties of magnesium alloy and stainless steel weld-joint made by friction stir lap welding

    International Nuclear Information System (INIS)

    Wei, Yanni; Li, Jinglong; Xiong, Jiangtao; Huang, Fu; Zhang, Fusheng

    2012-01-01

    Highlights: → Friction stir lap welding technology with cutting pin was successfully employed to form lap joint of magnesium and steel. → The cutting pin made the lower steel participate in deformation and the interface was no longer flat. → A saw-toothed structure formed due to a mechanical mixing of the magnesium and steel was found at the interface. → A high-strength joint was produced which fractured in the magnesium side. -- Abstract: Friction stir lap welding was conducted on soft/hard metals. A welding tool was designed with a cutting pin of rotary burr made of tungsten carbide, which makes the stirring pin possible to penetrate and cut the surface layer of the hard metal. Magnesium alloy AZ31 and stainless steel SUS302 were chosen as soft/hard base metals. The structures of the joining interface were analyzed by scanning electron microscopy (SEM). The joining strength was evaluated by tensile shear test. The results showed that flower-like interfacial morphologies were presented with steel flashes and scraps, which formed bonding mechanisms of nail effect by long steel flashes, zipper effect by saw-tooth structure and metallurgical bonding. The shear strength of the lap joint falls around the shear strength of butt joint of friction stir welded magnesium alloy.

  10. Effect of Pipe Body Alloy on Weldability of X80 Steel

    Science.gov (United States)

    Kong, Xianglei; Huang, Guojian; Fu, Kuijun; Liu, Fangfang; Huang, Minghao; Zhang, Yinghui

    Effect of Mo, Ni, and Cr on impact property of pipe seam and heat-affected zone (HAZ) of X80 steel was investigated by thermal simulation test and butt welding test. The results showed that, there was an obvious relationship between strip's composition and the toughness of weld and HAZ, the more content of Mo, Ni and less of Cr in the strip matrix, the better of impact toughness of weld and HAZ. Metallographic microscope was used to compare microstructures of welding specimens, every welded seam microstructure was mainly acicular ferrite (AF) and a little volume of proeutectoid ferrite (PF), and with some granular precipitations on original austenite grain boundary, the difference was that there were more PF and less precipitations of the specimen with more content of Mo, Ni and less of Cr in the strip matrix. Because of the high price of Mo and Ni, alloy design must be considered comprehensively with the cost and property requirements in the production.

  11. Microstructure and mechanical characterization of friction stir welded high strength low alloy steels

    International Nuclear Information System (INIS)

    Ramesh, R.; Dinaharan, I.; Kumar, Ravi; Akinlabi, E.T.

    2017-01-01

    Friction stir welding (FSW) is a promising technique to join HSLA steels without the problems encountered during fusion based welding processes. In the present work, 3 mm thick HSLA plates were successfully welded using FSW. A tool made of tungsten-rhenium alloy was used in this work. The relationship between microstructure and tensile strength was studied under various welding conditions i.e. change in traverse speed (57–97 mm/min). The microstructure of the weld nugget revealed the presence of upper bainite and fine ferrite phases. The amount of upper bainite reduced with increase in traverse speed. EBSD images showed a reducing trend for grain size. The details of hardness, tensile strength and bending test were reported.

  12. Overlapping phase transformations on tempering of a low-alloy steel

    International Nuclear Information System (INIS)

    Valencia Morales, E; Galeano Alvarez, N.J; Vega Leiva, J; Castellanos L M; Villar C E; Antiquera Munoz J; Hernandez R J

    2006-01-01

    The kinetics of precipitation of the primary and independent carbides during tempering of a low-alloy steel are characterized by the application of the Kinetic Theory of the Overlapping Phase Transformations(KTOPT). It is based on the Avrami model and considers two simultaneous precipitation processes. The present set-up allows us to calculate the exponent of the Avrami equation for simultaneous reactions at different rates. Only the dilatometry curves on tempering are required. According to this new formulation, the treatment of the dilatometry records showed different mechanisms of nucleation and growth of the primary and independent carbides. These results are in agreement with the thin foil electron micrographs and hardness tests of the thermally treated samples (au)

  13. Comparison of Solid and Hollow Torque Transducer Shaft Response in a High Alloy Stainless Steel

    Science.gov (United States)

    Milby, Christopher L.; Hecox, Bryan G.; Wiewel, Joseph L.; Boley, Mark S.

    2007-03-01

    Recent investigations of the torque transducer response function (ambient field signal versus applied torque or shear stress) have been conducted in a 13% chromium and 8% nickel stainless steel alloy in both the hollow shaft and solid shaft configuration. An understanding of both is needed for applications with differing yield strength and hardness requirements. Axial hysteresis measurements conducted before and after heat treatment exhibited little difference in coercivity and retentivity between the two sample types. However, the field mapping and transducer sensitivity studies showed the hollow shaft configuration to have a far superior degree of polarization in the sensory region and to exhibit an enhanced sensitivity, especially after heat treatment. This is most likely due to its more efficient provision of closed circumferential geometry for the field lines and improved grain alignment during heat treatment.

  14. Hydrogen permeation inhibition by zinc-nickel alloy plating on steel XC68

    International Nuclear Information System (INIS)

    El Hajjami, A.; Gigandet, M.P.; De Petris-Wery, M.; Catonne, J.C.; Duprat, J.J.; Thiery, L.; Raulin, F.; Starck, B.; Remy, P.

    2008-01-01

    The inhibition of hydrogen permeation and barrier effect by zinc-nickel plating was investigated using the Devanathan-Stachurski permeation technique. The hydrogen permeation and hydrogen diffusion for the zinc-nickel (12-15%) plating on steel XC68 is compared with zinc and nickel. Hydrogen permeation and hydrogen diffusion were followed as functions of time at current density applied (cathodic side) and potential permanent (anodic side). The hydrogen permeation inhibition for zinc-nickel is intermediate to that of nickel and zinc. This inhibition was due to nickel-rich layer effects at the Zn-Ni alloy/substrate interface, is shown by GDOES. Zinc-nickel plating inhibited the hydrogen diffusion greater as compared to zinc. This diffusion resistance was due to the barrier effect caused by the nickel which is present at the interface and transformed the hydrogen atomic to Ni 2 H compound, as shown by GIXRD.

  15. Hydrogen permeation inhibition by zinc-nickel alloy plating on steel XC68

    Energy Technology Data Exchange (ETDEWEB)

    El Hajjami, A. [Institut UTINAM, UMR CNRS 6213, Sonochimie et Reactivite des Surfaces, Universite de Franche-Comte, 16 route de Gray, 25030 Besancon Cedex (France); Coventya S.A.S., 51 rue Pierre, 92588 Clichy Cedex (France); Gigandet, M.P. [Institut UTINAM, UMR CNRS 6213, Sonochimie et Reactivite des Surfaces, Universite de Franche-Comte, 16 route de Gray, 25030 Besancon Cedex (France)], E-mail: marie-pierre.gigandet@univ-fcomte.fr; De Petris-Wery, M. [Institut Universitaire de Technologie d' Orsay, Universite Paris XI, Plateau de Moulon, 91400 Orsay (France); Catonne, J.C. [Professeur Honoraire du Conservatoire national des arts et metiers (CNAM), Paris (France); Duprat, J.J.; Thiery, L.; Raulin, F. [Coventya S.A.S., 51 rue Pierre, 92588 Clichy Cedex (France); Starck, B.; Remy, P. [Lisi Automotive, 28 faubourg de Belfort, BP 19, 90101 Delle Cedex (France)

    2008-12-30

    The inhibition of hydrogen permeation and barrier effect by zinc-nickel plating was investigated using the Devanathan-Stachurski permeation technique. The hydrogen permeation and hydrogen diffusion for the zinc-nickel (12-15%) plating on steel XC68 is compared with zinc and nickel. Hydrogen permeation and hydrogen diffusion were followed as functions of time at current density applied (cathodic side) and potential permanent (anodic side). The hydrogen permeation inhibition for zinc-nickel is intermediate to that of nickel and zinc. This inhibition was due to nickel-rich layer effects at the Zn-Ni alloy/substrate interface, is shown by GDOES. Zinc-nickel plating inhibited the hydrogen diffusion greater as compared to zinc. This diffusion resistance was due to the barrier effect caused by the nickel which is present at the interface and transformed the hydrogen atomic to Ni{sub 2}H compound, as shown by GIXRD.

  16. Predicting the creep life and failure mode of low-alloy steel weldments

    Energy Technology Data Exchange (ETDEWEB)

    Brear, J.M.; Middleton, C.J.; Aplin, P.F. [ERA Technology Ltd., Leatherhead (United Kingdom)

    1998-12-31

    This presentation reviews and consolidates experience gained through a number of research projects and practical plant assessments in predicting both the life and the likely failure mode and location in low alloy steel weldments. The approach adopted begins with the recognition that the relative strength difference between the microstructural regions is a key factor controlling both life and failure location. Practical methods based on hardness measurement and adaptable to differing weld geometries are presented and evidence for correlations between hardness ratio, damage accumulation and strain development is discussed. Predictor diagrams relating weld life and failure location to the service conditions and the hardness of the individual microstructural constituents are suggested and comments are given on the implications for identifying the circumstances in which Type IV cracking is to be expected. (orig.) 6 refs.

  17. Deposition of Co-Ti alloy on mild steel substrate using laser cladding

    International Nuclear Information System (INIS)

    Alemohammad, Hamidreza; Esmaeili, Shahrzad; Toyserkani, Ehsan

    2007-01-01

    Laser cladding of a Co-Ti alloy on a mild steel substrate is studied. Premixed powders with the composition of 85 wt% cobalt and 15 wt% titanium are pre-placed on the substrate and a moving laser beam at different velocities is used to produce clad layers well bounded to the substrate. Characteristics of the clad are investigated using optical microscopy, X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and microhardness tests. The results reveal that the intermetallic phase TiCo 3 and β (i.e. fcc) cobalt are formed in the clad layer. The clad layer can also have major dilution from the substrate depending on the laser scanning velocity. It is observed that a finer microstructure is achievable with higher laser velocities whereas higher hardness is achieved using lower velocities. The latter is due to the formation of a larger fraction of TiCo 3 phase

  18. A rapid method for spectrophotometric determination of molybdenum in alloy steels

    International Nuclear Information System (INIS)

    Keshavan, B.; Nagaraja, P.

    1985-01-01

    Molybdenum(IV) forms an orange-red coloured mixed-ligand complex with perazine dimalonate and thiocyanate at room temperature (27 0 ) in hydrochloric acid. The complex is soluble in ethanol. It exhibits absorption maximum at 460 nm. Beer's law is valid over the molybdenum concentration range 0.1-14.0 μg/ml. Sandell's sensitivity of the reaction is 0.9 x 10 -3 μg Mo/cm 2 and the molar extinction coefficient is 1.06 x 10 4 l x mol -1 x cm -1 at 460 nm. The stoichiometry of the complex is (Perazine x H) [MoO(SCN) 4 ] as shown by Job's method, equilibrium shift method and elemental analyses of the isolated complex. The proposed method has been used for the determination of molybdenum in ores, alloy steels and in synthetic mixtures containing chromium, tungsten, iron, cobalt, nickel and copper.(Author)

  19. Nickel coating on high strength low alloy steel by pulse current deposition

    Science.gov (United States)

    Nigam, S.; Patel, S. K.; Mahapatra, S. S.; Sharma, N.; Ghosh, K. S.

    2015-02-01

    Nickel is a silvery-white metal mostly used to enhance the value, utility, and lifespan of industrial equipment and components by protecting them from corrosion. Nickel is commonly used in the chemical and food processing industries to prevent iron from contamination. Since the properties of nickel can be controlled and varied over broad ranges, nickel plating finds numerous applications in industries. In the present investigation, pulse current electro-deposition technique has been used to deposit nickel on a high strength low alloy (HSLA) steel substrate.Coating of nickel is confirmed by X-ray diffraction (XRD) and EDAX analysis. Optical microscopy and SEM is used to assess the coating characteristics. Electrochemical polarization study has been carried out to study the corrosion behaviour of nickel coating and the polarisation curves have revealed that current density used during pulse electro-deposition plays a vital role on characteristics of nickel coating.

  20. Low Alloy Steel Structures After Welding with Micro-Jet Cooling

    Directory of Open Access Journals (Sweden)

    Węgrzyn T.

    2017-03-01

    Full Text Available The paper focuses on low alloy steel after innovate welding method with micro-jet cooling. Weld metal deposit (WMD was carried out for welding and for MIG and MAG welding with micro-jet cooling. This method is very promising mainly due to the high amount of AF (acicular ferrite and low amount of MAC (self-tempered martensite, retained austenite, carbide phases in WMD. That structure corresponds with very good mechanical properties, ie. high impact toughness of welds at low temperature. Micro-jet cooling after welding can find serious application in automotive industry very soon. Until that moment only argon, helium and nitrogen were tested as micro-jet gases. In that paper first time various gas mixtures (gas mixtures Ar-CO2 were tested for micro-jet cooling after welding.

  1. A comparative study of the in vitro corrosion behavior and cytotoxicity of a superferritic stainless steel, a Ti-13Nb-13Zr alloy, and an austenitic stainless steel in Hank's solution.

    Science.gov (United States)

    Assis, S L; Rogero, S O; Antunes, R A; Padilha, A F; Costa, I

    2005-04-01

    In this study, the in vitro corrosion resistance of a superferritic stainless steel in naturally aerated Hank's solution at 37 degrees C has been determined to evaluate the steel for use as a biomaterial. The potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS) were used to determine the corrosion resistance. The polarization results showed very low current densities at the corrosion potential and electrochemical behavior typical of passive metals. At potentials above 0.75 V (SCE), and up to that of the oxygen evolution reaction, the superferritic steel exhibited transpassive behavior followed by secondary passivation. The superferritic stainless steel exhibited high pitting resistance in Hank's solution. This steel did not reveal pits even after polarization to 3000 mV (SCE). The EIS results indicated high impedance values at low frequencies, supporting the results obtained from the polarization measurements. The results obtained for the superferritic steel have been compared with those of the Ti-13Nb-13Zr alloy and an austenitic stainless steel, as Ti alloys are well known for their high corrosion resistance and biocompatibility, and the austenitic stainless steel is widely used as an implant material. The cytotoxicity tests indicated that the superferritic steel, the austenitic steel, and the Ti-13Nb-13Zr alloy were not toxic. Based on corrosion resistance and cytotoxicity results, the superferritic stainless steel can be considered as a potential biomaterial. (c) 2005 Wiley Periodicals, Inc.

  2. The tribological difference between biomedical steels and CoCrMo-alloys.

    Science.gov (United States)

    Fischer, Alfons; Weiss, Sabine; Wimmer, Markus A

    2012-05-01

    In orthopedic surgery, different self-mating metal couples are used for sliding wear applications. Despite the fact that in mechanical engineering, self-mating austenitic alloys often lead to adhesion and seizure in biomedical engineering, the different grades of Co-base alloys show good clinical results, e.g., as hip joints. The reason stems from the fact that they generate a so-called tribomaterial during articulation, which consists of a mixture of nanometer small metallic grains and organic substances from the interfacial medium, which act as a boundary lubricant. Even though stainless steel also generate such a tribomaterial, they were ruled out from the beginning already in the 1950s as "inappropriate". On the basis of materials with a clinical track record, this contribution shows that the cyclic creep characteristics within the shear zone underneath the tribomaterial are another important criterion for a sufficient wear behavior. By means of sliding wear and torsional fatigue tests followed by electron microscopy, it is shown that austenitic materials generate wear particles of either nano- or of microsize. The latter are produced by crack initiation and propagation within the shear fatigue zone which is related to the formation of subsurface dislocation cells and, therefore, by the fact that an Ni-containing CrNiMo solid solution allows for wavy-slip. In contrast to this, an Ni-free CrMnMo solid solution with further additions of C and N only shows planar slip. This leads to the formation of nanosize wear particles and distinctly improves the wear behavior. Still, the latter does not fully achieve that of CoCrMo, which also shows a solely planar-slip behavior. This explains why for metallurgical reasons the Ni-containing 316L-type of steels had to fail in such boundary lubricated sliding wear tribosystems. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Production and characterization of stainless steel based Fe-Cr-Ni-Mn-Si(-Co) shape memory alloys

    International Nuclear Information System (INIS)

    Otubo, J.

    1995-01-01

    It is well known that the Fe based alloys can exhibit shape memory effect due to the γ to ε martensitic transformation. The effect may not be as striking as observed in the NiTi alloy but it might become attractive from the practical point of view. In this work, two compositions of Fe-Cr-Ni-Mn-Si(-Co) stainless steel based shape memory alloy, prepared by the VIM technique, will be presented. The results are good with shape recovery of 95% for a pre-strain of 4% after some training cycles. In terms of workability the alloys produced are worse than the usual AISI304. However, adjusting the thermo-mechanical processing, it is perfectly possible to produce wire as thin as 1,20mm in dia. or down. (orig.)

  4. Fe-Cr-V ternary alloy-based ferritic steels for high- and low-temperature applications

    International Nuclear Information System (INIS)

    Rieth, M.; Materna-Morris, E.; Dudarev, S.L.; Boutard, J.-L.; Keppler, H.; Mayor, J.

    2009-01-01

    The phase stability of alloys and steels developed for application in nuclear fission and fusion technology is one of the decisive factors determining the potential range of operating temperatures and radiation conditions that the core elements of a power plant can tolerate. In the case of ferritic and ferritic-martensitic steels, the choice of the chemical composition is dictated by the phase diagram for binary FeCr alloys where in the 0-9% range of Cr composition the alloy remains in the solid solution phase at and below the room temperature. For Cr concentrations exceeding 9% the steels operating at relatively low temperatures are therefore expected to exhibit the formation of α' Cr-rich precipitates. These precipitates form obstacles for the propagation of dislocations, impeding plastic deformation and embrittling the material. This sets the low temperature limit for the use of of high (14% to 20%) Cr steels, which for the 20% Cr steels is at approximately 600 deg. C. On the other hand, steels containing 12% or less Cr cannot be used at temperatures exceeding ∼600 deg. C due to the occurrence of the α-γ transition (912 deg. C in pure iron and 830 deg. C in 7% Cr alloy), which weakens the steel in the high temperature limit. In this study, we investigate the physical properties of a concentrated ternary alloy system that attracted relatively little attention so far. The phase diagram of ternary Fe-Cr-V alloy shows no phase boundaries within a certain broad range of Cr and V concentrations. This makes the alloy sufficiently resistant to corrosion and suggests that steels and dispersion strengthened materials based on this alloy composition may have better strength and stability at high temperatures. Experimental heats were produced on a laboratory scale by arc melting the material components to pellets, then by melting the pellets in an induction furnace and casting the melt into copper moulds. The compositions in weight percent (iron base) are 10Cr5V, 10Cr

  5. Pitting corrosion resistance of a novel duplex alloy steel in alkali-activated slag extract in the presence of chloride ions

    Science.gov (United States)

    Shi, Jin-jie; Ming, Jing; Liu, Xin

    2017-10-01

    In this study, two types of reinforcing steels (conventional low-carbon steel and a novel duplex alloy steel with Cr and Mo) were exposed to chloride-contaminated extract solutions (ordinary Portland cement (OPC) extract and alkali-activated slag (AAS) extract) to investigate their pitting corrosion resistance. The results confirm that the pitting corrosion resistance of the alloy steel is much higher than that of the low-carbon steel in both extract solutions with various NaCl concentrations. Moreover, for each type of steel, the AAS extract contributes to a higher pitting corrosion resistance compared with the OPC extract in the presence of chloride ions, likely because of the formation of flocculent precipitates on the steel surface.

  6. The use of niobium bearing ferro-alloys in the manufacture of structural steels in the USSR

    International Nuclear Information System (INIS)

    Lyakishev, N.P.

    1984-01-01

    Information is presented concerning the use of niobium as a microalloying element in constructional steels of various types. Niobium causes substantial refinement of grain size and inhibits the process of static recrystallization. It is, therefore, widely used in high strength low-alloy steels subjected to controlled-rolling or thermo-mechanical treatment. The largest strength increases are observed with a niobium content of up to 0.05 percent at which point the impact toughness diminishes slightly. Increased amounts of niobium favorably affect both the impact toughness and the transition temperature. The effectiveness of niobium usage in existing types of construction steels, including HSLA steels intended for the manufacture of weldable large-diameter linepipe for use in Arctic environments is described

  7. Processing and properties of mechanically alloyed sintered steels with hard inclusions

    International Nuclear Information System (INIS)

    Gutsfeld, C.

    1991-10-01

    The aim of this work was the development of mechanically alloyed sintered steels with inert hard inclusions and their characterisation concerning the mechanical properties and the sliding wear behaviour. For this material concept the hard materials NbC, TiC, TiN and Al 2 O 3 were chosen with volume contents upto 20%. Mechanical alloying of the raw powders is a necessary prerequisit for an extreme fine and homogeneous microstructure and good mechanical and wear properties. Through a connecting powder annealing a conventional powder metallurgical processing with cold pressing and sintering is possible. For the consolidation pressureless liquid phase sintering initiated through phosphorus contents of 0,6% is suitable. Because of the strong hampering of grain growth through the included hard particles sintering densities upto 99% TD are possible with extreme fine microstructures. The mechanical properties can be varied in wide ranges. So tensile strengths of 1150 MPa, elongations at fracture of 17%, hardness of over 800 HV and fatigue strengths of 370 MPa have been reached. Throughout HIP or sinter forging the mechanical properties can be improved furthermore. (orig.) [de

  8. A mechanical property and stress corrosion evaluation of Custom 455 stainless steel alloy

    Science.gov (United States)

    Montano, J. W.

    1972-01-01

    The mechanical and stress corrosion properties are presented of vacuum melted Custom 455 stainless steel alloy bar (1.0-inch diameter) and sheet (0.083-inch thick) material aged at 950 F, 1000 F, and 1050 F. Low temperature mechanical properties were determined at temperatures of 80 F, 0 F, -100 F, and -200 F. For all three aging treatments, the ultimate tensile and 0.2 percent offset yield strengths increased with decreasing test temperatures while the elongation held fairly constant down to -100 F and decreased at -200 F. Reduction in Area decreased moderately with decreasing temperature for the longitudinal round (0.250-inch diameter) specimens. Notched tensile strength and charpy V-notched impact strength decreased with decreasing test temperature. For all three aging treatments, no failures were observed in the unstressed specimens or the specimens stressed to 50, 75, and 100 percent of their yield strengths for 180 days of alternate immersion testing in a 3.5 percent NaCl solution. As indicated by the results of tensile tests performed after alternate immersion testing, the mechanical properties of Custom 455 alloy were not affected by stress or exposure under the conditions of the evaluation.

  9. Characterization of thin Zn-Ni alloy coatings electrodeposited on low carbon steel

    International Nuclear Information System (INIS)

    El Hajjami, A.; Gigandet, M.P.; De Petris-Wery, M.; Catonne, J.C.; Duprat, J.J.; Thiery, L.; Raulin, F.; Pommier, N.; Starck, B.; Remy, P.

    2007-01-01

    The characteristics of initial layer formation in alkaline bath for Zn-Ni (12-15%) alloy electrodeposition on low carbon steel plates are detected in a nanometric thickness range by electron probe microanalysis (EPMA), with both bulk sample and thin film on substrate correction procedure, glow discharge optical emission spectroscopy (GDOES) and gracing incidence X-ray diffraction (GIXRD). The Zn-Ni coatings were elaborated using either intensiostatic or potentiostatic mode. A preferential deposition of Ni, in the initial thin layer, is detected by these analyses; according to EPMA and GDOES measurements, a layer rich in nickel at the interface substrate/deposit is observed (90 wt.% Ni) and approved by GIXRD; the thin layer of Ni formed in the first moments of electrolysis greatly inhibits the Zn deposition. The initial layer depends upon the relative ease of hydrogen and metal discharge and on the different substrate surfaces involved. The electrodeposition of zinc-nickel alloys in the first stage is a normal phenomenon of codeposition, whereby nickel - the more noble metal - is deposited preferentially

  10. Electrochemical assessment of some titanium and stainless steel implant dental alloys

    Directory of Open Access Journals (Sweden)

    Echevarría, A.

    2003-12-01

    Full Text Available Commercially pure titanium alloy, Ti-6Al-4V alloy and stainless steel screw implants were evaluated in both Ringer and synthetic saliva physiological solutions at body temperature by EIS (Electrochemical Impedance Spectroscopy with immersion times of 30 d. Results were simulated as a "sandwich system" composed by four capacitors-resistances connected in series with the solution resistance. A model explaining the results in terms of the porosity and thickness of four different layers, was proposed.

    Se utilizó la técnica de la Espectroscopia de Impedancia Electroquímica para evaluar en soluciones fisiológicas artificiales (Ringer y saliva sintética muestras extraídas de tornillos de implantes dentales certificados de titanio comercialmente puro, aleación Ti-6Al-W y acero inoxidable a temperatura corporal, con tiempos de inmersión hasta de 30 d. Los resultados se simularon mediante un modelo del tipo sandwich de cuatro elementos RC, conectados en serie con una resistencia de la solución. A partir de de esta simulación, se propone un modelo que explica los resultados obtenidos en términos de la evolución de la porosidad y el espesor de cuatro diferentes capas que se desarrollan en la superficie de los materiales evaluados.

  11. Compressive Deformation Behavior of Thick Micro-Alloyed HSLA Steel Plates at Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Lee J.-H.

    2017-06-01

    Full Text Available The hot deformation behavior of a heavy micro-alloyed high-strength low-alloy (HSLA steel plate was studied by performing compression tests at elevated temperatures. The hot compression tests were carried out at temperatures from 923 K to 1,223 K with strain rates of 0.002 s−1 and 1.0 s−1. A long plateau region appeared for the 0.002 s−1 strain rate, and this was found to be an effect of the balancing between softening and hardening during deformation. For the 1.0 s−1 strain rate, the flow stress gradually increased after the yield point. The temperature and the strain rate-dependent parameters, such as the strain hardening coefficient (n, strength constant (K, and activation energy (Q, obtained from the flow stress curves were applied to the power law of plastic deformation. The constitutive model for flow stress can be expressed as σ = (39.8 ln (Z – 716.6 · ε(−0.00955ln(Z + 0.4930 for the 1.0 s−1 strain rate and σ = (19.9ln (Z – 592.3 · ε(−0.00212ln(Z + 0.1540 for the 0.002 s−1 strain rate.

  12. Characterization of Friction Welded Titanium Alloy and Stainless Steel with a Novel Interlayer Geometry

    Science.gov (United States)

    Kumar, R.; Balasubramanian, M.

    The main purpose of the current research work is to identify and investigate a novel method of holding an intermediate metal and to evaluate its metallurgical and mechanical properties. Copper was used as an interlayer material for the welding of this dissimilar Ti-6Al-4V (Ti alloy) and 304L stainless steel (SS). The study shows that the input parameters and surface geometry played a very significant role in producing a good quality joints with minimum heat affected zone and metal loss. A sound weld was achieved between Ti-6Al-4V and SS304L, on the basis of the earlier experiments conducted by the authors in their laboratory, by using copper rod as intermediate metal. Box-Behnken method was used for performing a minimum number of experiments for the study. In the present study, Ti-6Al-4V alloy and SS304L were joined by a novel method of holding the interlayer and new surface geometry for the interlayer. Initially, the drop test was used for determining the quality of the fabricated joint and, subsequently, non-destructive techniques like radiography and C-scan were used. Further optical micrograph, SEM-EDS, hardness and tensile test were done for understanding the performance of the joint.

  13. Environmentally-Assisted Cracking of Low-Alloy Reactor Pressure Vessel Steels under Boiling Water Reactor Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Seifert, H.P.; Ritter, S

    2002-02-01

    The present report summarizes the experimental work performed by PSI on the environmentally-assisted cracking (EAC) of low-alloy steels (LAS) in the frame of the RIKORR-project during the period from January 2000 to August 2001. Within this project, the EAC crack growth behaviour of different low-alloy reactor pressure vessel (RPV) steels, weld filler and weld heat-affected zone materials is investigated under simulated transient and steady-state BWR/NWC power operation conditions. The EAC crack growth behaviour of different low-alloy RPV steels was characterized by slow rising load (SRL) / low-frequency corrosion fatigue (LFCF) and constant load tests with pre-cracked fracture mechanics specimens in oxygenated high-temperature water at temperatures of either 288, 250, 200 or 150 C. These tests revealed the following important interim results: Under low-flow and highly oxidizing (ECP >= 100 mV SHE) conditions, the ASME XI 'wet' reference fatigue crack growth curve could be significantly exceeded by cyclic fatigue loading at low frequencies (<0.001 Hz), at high and low load-ratios R, and by ripple loading near to DKth fatigue thresholds. The BWR VIP 60 SCC disposition lines may be significantly or slightly exceeded (even in steels with a low sulphur content) in the case of small load fluctuations at high load ratios (ripple loading) or at intermediate temperatures (200 -250 C) in RPV materials, which show a distinct susceptibility to dynamic strain ageing (DSA). (author)

  14. Structure and Properties of High-Temperature Multilayer Hybrid Material Based on Vanadium Alloy and Stainless Steel

    Science.gov (United States)

    Nechaykina, Tatyana A.; Nikulin, Sergey A.; Rozhnov, Andrey B.; Khatkevich, Vladimir M.; Rogachev, Stanislav O.

    2017-03-01

    The present work is devoted to the development of new structural composite material having the unique complex of properties for operating in ultrahard conditions that combine high temperatures, radiation, and aggressive environments. A new three-layer composite tube material based on vanadium alloy (V-4Ti-4Cr) protected by stainless steel (Fe-0.2C-13Cr) has been obtained by co-extrusion. Mechanism and kinetics of formation as well as structure, composition, and mechanical properties of "transition" area between vanadium alloy and stainless steel have been studied. The transition area (13- to 22- µm thick) of the diffusion interaction between vanadium alloy and steel was formed after co-extrusion. The microstructure in the transition area was rather complicated comprising different grain sizes in components, but having no defects or brittle phases. Tensile strength of the composite was an average 493 ± 22 MPa, and the elongation was 26 ± 3 pct. Annealing at 1073 K (800 °C) increased the thickness of transition area up to 1.2 times, homogenized microstructure, and slightly changed mechanical properties. Annealing at 1273 K (1000 °C) further increased the thickness of transition area and also lead to intensive grain growth in steel and sometimes to separation between composite components during tensile tests. Annealing at 1073 K (800 °C) is proposed as appropriate heat treatment after co-extrusion of composite providing balance between diffusion interaction thickness and microstructure and monolithic-like behavior of composite during tensile tests.

  15. Parameters of straining-induced corrosion cracking in low-alloy steels in high temperature water

    International Nuclear Information System (INIS)

    Lenz, E.; Liebert, A.; Stellwag, B.; Wieling, N.

    Tensile tests with slow deformation speed determine parameters of corrosion cracking at low strain rates of low-alloy steels in high-temperature water. Besides the strain rate the temperature and oxygen content of the water prove to be important for the deformation behaviour of the investigated steels 17MnMoV64, 20 MnMoNi55 and 15NiCuMoNb 5. Temperatures about 240 0 C, increased oxygen contents in the water and low strain rates cause a decrease of the material ductility as against the behaviour in air. Tests on the number of stress cycles until incipient cracking show that the parameters important for corrosion cracking at low strain velocities apply also to low-frequency cyclic loads with high strain amplitude. In knowledge of these influencing parameters the strain-induced corrosion cracking is counteracted by concerted measures taken in design, construction and operation of nuclear power stations. Essential aims in this matter are to avoid as far as possible inelastic strains and to fix and control suitable media conditions. (orig.) [de

  16. Residual stresses in a stainless steel - titanium alloy joint made with the explosive technique

    Science.gov (United States)

    Taran, Yu V.; Balagurov, A. M.; Sabirov, B. M.; Evans, A.; Davydov, V.; Venter, A. M.

    2012-02-01

    Joining of pipes from stainless steel (SS) and titanium (Ti) alloy still experience serious technical problems. Recently, reliable and hermetic joining of SS and Ti pipes has been achieved with the explosive bonding technique in the Russian Federal Nuclear Center. Such adapters are earmarked for use at the future International Linear Collider. The manufactured SS-Ti adapters have excellent mechanical behavior at room and liquid nitrogen temperatures, during high-pressure tests and thermal cycling. We here report the first neutron diffraction investigation of the residual stresses in a SS-Ti adapter on the POLDI instrument at the SINQ spallation source. The strain scanning across the adapter walls into the SS-SS and SS-Ti pipes sections encompassed measurement of the axial, radial and hoop strain components, which were transformed into residual stresses. The full stress information was successfully determined for the three steel pipes involved in the joint. The residual stresses do not exceed 300 MPa in magnitude. All stress components have tensile values close to the adapter internal surface, whilst they are compressive close to the outer surface. The strong incoherent and weak coherent neutron scattering cross-sections of Ti did not allow for the reliable determination of stresses inside the titanic pipe.

  17. Residual stresses in a stainless steel – titanium alloy joint made with the explosive technique

    International Nuclear Information System (INIS)

    Taran, Yu V; Balagurov, A M; Sabirov, B M; Evans, A; Davydov, V; Venter, A M

    2012-01-01

    Joining of pipes from stainless steel (SS) and titanium (Ti) alloy still experience serious technical problems. Recently, reliable and hermetic joining of SS and Ti pipes has been achieved with the explosive bonding technique in the Russian Federal Nuclear Center. Such adapters are earmarked for use at the future International Linear Collider. The manufactured SS-Ti adapters have excellent mechanical behavior at room and liquid nitrogen temperatures, during high-pressure tests and thermal cycling. We here report the first neutron diffraction investigation of the residual stresses in a SS-Ti adapter on the POLDI instrument at the SINQ spallation source. The strain scanning across the adapter walls into the SS-SS and SS-Ti pipes sections encompassed measurement of the axial, radial and hoop strain components, which were transformed into residual stresses. The full stress information was successfully determined for the three steel pipes involved in the joint. The residual stresses do not exceed 300 MPa in magnitude. All stress components have tensile values close to the adapter internal surface, whilst they are compressive close to the outer surface. The strong incoherent and weak coherent neutron scattering cross-sections of Ti did not allow for the reliable determination of stresses inside the titanic pipe.

  18. Performance of Ti-multilayer coated tool during machining of MDN431 alloyed steel

    Science.gov (United States)

    Badiger, Pradeep V.; Desai, Vijay; Ramesh, M. R.

    2018-04-01

    Turbine forgings and other components are required to be high resistance to corrosion and oxidation because which they are highly alloyed with Ni and Cr. Midhani manufactures one of such material MDN431. It's a hard-to-machine steel with high hardness and strength. PVD coated insert provide an answer to problem with its state of art technique on the WC tool. Machinability studies is carried out on MDN431 steel using uncoated and Ti-multilayer coated WC tool insert using Taguchi optimisation technique. During the present investigation, speed (398-625rpm), feed (0.093-0.175mm/rev), and depth of cut (0.2-0.4mm) varied according to Taguchi L9 orthogonal array, subsequently cutting forces and surface roughness (Ra) were measured. Optimizations of the obtained results are done using Taguchi technique for cutting forces and surface roughness. Using Taguchi technique linear fit model regression analysis carried out for the combination of each input variable. Experimented results are compared and found the developed model is adequate which supported by proof trials. Speed, feed and depth of cut are linearly dependent on the cutting force and surface roughness for uncoated insert whereas Speed and depth of cut feed is inversely dependent in coated insert for both cutting force and surface roughness. Machined surface for coated and uncoated inserts during machining of MDN431 is studied using optical profilometer.

  19. Anisotropic work-hardening behaviour ofstructural steels and aluminium alloys at large strains

    Science.gov (United States)

    Bouvier, S.; Teodosiu, C.; Haddadi, H.; Tabacaru, V.

    2003-03-01

    Sheet metal forming processes may often involve intense forming sequences, leading to large strains and severe strain-path changes. Optimizing such technologies requires a good understanding and description of the anisotropic plastic behaviour of the deformed material, in connection with the evolution of its texture and microstructure. In this paper, we present the predictions provided by a model involving isotropic and kinematioc hardening and by a physically-based microstructural model, which introduces additional internal variables taking into accounthe directional strength of dislocation structures and their polarity. These models have been identified by using sequences of uniaxial traction and simple shear experiments, carried out on various steels (DC06, DP600, HSLA340) and aluminium alloys (AA5182-O, AA6016-T4). The microstructural model proved able predict the complex hardening behaviour displayed, especially by the ferritic steels, namely the transient work-hardening stagnation during reversed deformation in Bauschinger tests, the temporary work-softening during orthogonal tests, and the grain fragmentation at large monotonie strains.

  20. Topical problems of crackability in weld annealing of low-alloyed pressure vessel steels

    International Nuclear Information System (INIS)

    Holy, M.

    1977-01-01

    The following method was developed for determining annealing crackability: A sharp notch was made in the middle of the bodies of rods imitated in a welding simulator. Chucking heads were modified such as to permit chucking a rod in an austenitic block by securing the nut. Prestress was controlled by button-headed screw adapters. The blocks were made of 4 types of austenitic steels with graded thermal expansivity coefficients, all higher than that of the tested low-alloyed steel rod. The blocks with rods were placed in a furnace and heated at a rate of 100 degC/h. As a result of the larger austenite block diameter the rod began to be stretched and at some temperature of more than 500 degC it was pulled apart. The risk of annealing crackability of welded joints may be reduced by the choice of material and melt and by the technology of welding, mainly by the choice of a suitable addition material in whose weld metal the plastic deformation preferably takes place in annealing. (J.P.)

  1. Factors affecting the grain growth of austenite in low alloy steel

    International Nuclear Information System (INIS)

    Parker, J.D.; Storer, S.M.

    1995-01-01

    The performance of steels is linked to the metallurgical transformations which occur during manufacture. Clearly then the optimization of a fabrication procedure must be based on fundamental relationships linking specific thermal treatments with transformation behaviour. Optimized manufacture of thick-section, multipass welds is therefore particularly complex since the thermal cycles associated with fusion welding result in the formation of heterogeneous microstructures. Moreover, these transformations will take place under rapid heating and cooling conditions so that standard data based on equilibrium behaviour may not be directly relevant. The present study is part of an integrated research programme aimed at establishing the basic microstructural relationships required to optimize the manufacture and performance of weldments. Work to date demonstrates that utilization of a computer controlled Gleeble simulation system allows a wider range of heating and cooling rates to be applied than is possible with traditional heat treatment techniques. Additional advantages of this system include precise control of time at peak temperature and uniform temperatures within a defined work zone. Results presented for a CrMoV creep resistant low alloy steel indicate that grain growth behaviour in the range 955-1390 C can be related to the time at peak temperature. The effect of this transformation behaviour on weldment behaviour is discussed. (orig.)

  2. Experimental Study on Vacuum Carburizing Process for Low-Carbon Alloy Steel

    Science.gov (United States)

    Wei, Shaopeng; Wang, Gang; Zhao, Xianhui; Zhang, Xiaopeng; Rong, Yiming

    2013-10-01

    As a low-carbon alloy steel, 20Cr2Ni4A steel has an excellent mechanical properties. It has been used for producing heavy-duty gears, which require good wear and fatigue resistance. The vacuum carburizing process can improve the quality of gears and extend the service life. In this article, a complete heat-treatment process for 20Cr2Ni4A, with carburizing, tempering, quenching and cryogenic steps involved, was proposed. A numerical method was employed to design the carburizing step. The carburized samples were characterized by analysis of carbon profile, surface-retained austenite content, microstructure, and hardness profile. A good microstructure was obtained with acicular-tempered martensite, less-retained austenite, fine granular-dispersed carbides, and was oxide free. The final surface hardness was 64.2HRC, and the case depth was 0.86 mm, which meet the requirements of products. The relationships among process, performance, and microstructure were investigated to understand the inner connection.

  3. Characterization and Cytotoxic Assessment of Ballistic Aerosol Particulates for Tungsten Alloy Penetrators into Steel Target Plates

    Directory of Open Access Journals (Sweden)

    Brian E. Schuster

    2010-08-01

    Full Text Available The nature and constituents of ballistic aerosol created by kinetic energy penetrator rods of tungsten heavy alloys (W-Fe-Ni and W-Fe-Co perforating steel target plates was characterized by scanning and transmission electron microscopy. These aerosol regimes, which can occur in closed, armored military vehicle penetration, are of concern for potential health effects, especially as a consequence of being inhaled. In a controlled volume containing 10 equispaced steel target plates, particulates were systematically collected onto special filters. Filter collections were examined by scanning and transmission electron microscopy (SEM and TEM which included energy-dispersive (X-ray spectrometry (EDS. Dark-field TEM identified a significant nanoparticle concentration while EDS in the SEM identified the propensity of mass fraction particulates to consist of Fe and FeO, representing target erosion and formation of an accumulating debris field. Direct exposure of human epithelial cells (A549, a model for lung tissue, to particulates (especially nanoparticulates collected on individual filters demonstrated induction of rapid and global cell death to the extent that production of inflammatory cytokines was entirely inhibited. These observations along with comparisons of a wide range of other nanoparticulate species exhibiting cell death in A549 culture may suggest severe human toxicity potential for inhaled ballistic aerosol, but the complexity of the aerosol (particulate mix has not yet allowed any particular chemical composition to be identified.

  4. Characterization and Cytotoxic Assessment of Ballistic Aerosol Particulates for Tungsten Alloy Penetrators into Steel Target Plates

    Science.gov (United States)

    Machado, Brenda I.; Murr, Lawrence E.; Suro, Raquel M.; Gaytan, Sara M.; Ramirez, Diana A.; Garza, Kristine M.; Schuster, Brian E.

    2010-01-01

    The nature and constituents of ballistic aerosol created by kinetic energy penetrator rods of tungsten heavy alloys (W-Fe-Ni and W-Fe-Co) perforating steel target plates was characterized by scanning and transmission electron microscopy. These aerosol regimes, which can occur in closed, armored military vehicle penetration, are of concern for potential health effects, especially as a consequence of being inhaled. In a controlled volume containing 10 equispaced steel target plates, particulates were systematically collected onto special filters. Filter collections were examined by scanning and transmission electron microscopy (SEM and TEM) which included energy-dispersive (X-ray) spectrometry (EDS). Dark-field TEM identified a significant nanoparticle concentration while EDS in the SEM identified the propensity of mass fraction particulates to consist of Fe and FeO, representing target erosion and formation of an accumulating debris field. Direct exposure of human epithelial cells (A549), a model for lung tissue, to particulates (especially nanoparticulates) collected on individual filters demonstrated induction of rapid and global cell death to the extent that production of inflammatory cytokines was entirely inhibited. These observations along with comparisons of a wide range of other nanoparticulate species exhibiting cell death in A549 culture may suggest severe human toxicity potential for inhaled ballistic aerosol, but the complexity of the aerosol (particulate) mix has not yet allowed any particular chemical composition to be identified. PMID:20948926

  5. Hydrogen effects in nitrogen-alloyed austenitic steels; Wirkung von Wasserstoff in stickstofflegierten austenitischen Staehlen

    Energy Technology Data Exchange (ETDEWEB)

    Uhlemann, M.; Mummert, K. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany); Shehata, M.F. [National Research Centre, Cairo (Egypt)

    1998-12-31

    Hydrogen increases the yield strength of nitrogen-alloyed steels, but on the other hand adversely affects properties such as tensile strength and elongation to fracture. The effect is enhanced with increasing nitrogen and hydrogen contents. Under the effect of hydrogen addition, the discontinuous stress-strain characteristic and the distinct elongation limit of hydrogen-free, nitrogen containing steels is no longer observed in the material. This change of mechanical properties is attributed to an interatomic interaction of nitrogen and hydrogen in the lattice, which is shown for instance by such effects as reduction of hydrogen velocity, high solubility, and a particularly strong lattice expansion. The nature of this interaction of nitrogen and hydrogen in the fcc lattice remains to be identified. (orig./CB) [Deutsch] Wasserstoff fuehrt in stickstofflegierten Staehlen zu einer Erhoehung der Streckgrenze, aber gleichzeitig zu einer Abnahme der Zugfestigkeit und Bruchdehnung. Dieser Effekt verstaerkt sich mit zunehmenden Stickstoff- und Wasserstoffgehalten. Ein diskontinuierlicher Spannungs-Dehnungsverlauf mit einer ausgepraegten Streckgrenze in wasserstofffreien hochstickstoffhaltigen Staehlen wird nach Wasserstoffeinfluss nicht mehr beobachtet. Die Aenderung der mechanischen Eigenschaften, wird auf eine interatomare Wechselwirkung von Stickstoff und Wasserstoff im Gitter zurueckgefuehrt, die sich u.a. in geringer Wasserstoffdiffusionsgeschwindigkeit, hoher Loeslichkeit und vor allem in extremer Gitteraufweitung aeussert. Insgesamt ist die Natur der Wechselwirkung zwischen Stickstoff und Wasserstoff im kfz Gitter noch nicht aufgeklaert. (orig.)

  6. Quantification of oxide particle composition in model oxide dispersion strengthened steel alloys

    Energy Technology Data Exchange (ETDEWEB)

    London, A.J., E-mail: andrew.london@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Lozano-Perez, S.; Moody, M.P. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Amirthapandian, S.; Panigrahi, B.K.; Sundar, C.S. [Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, TN (India); Grovenor, C.R.M. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

    2015-12-15

    Oxide dispersion strengthened ferritic steels (ODS) are being considered for structural components of future designs of fission and fusion reactors because of their impressive high-temperature mechanical properties and resistance to radiation damage, both of which arise from the nanoscale oxide particles they contain. Because of the critical importance of these nanoscale phases, significant research activity has been dedicated to analysing their precise size, shape and composition (Odette et al., Annu. Rev. Mater. Res. 38 (2008) 471–503 [1]; Miller et al., Mater. Sci. Technol. 29(10) (2013) 1174–1178 [2]). As part of a project to develop new fuel cladding alloys in India, model ODS alloys have been produced with the compositions, Fe–0.3Y{sub 2}O{sub 3}, Fe–0.2Ti–0.3Y{sub 2}O{sub 3} and Fe–14Cr–0.2Ti–0.3Y{sub 2}O{sub 3}. The oxide particles in these three model alloys have been studied by APT in their as-received state and following ion irradiation (as a proxy for neutron irradiation) at various temperatures. In order to adequately quantify the composition of the oxide clusters, several difficulties must be managed, including issues relating to the chemical identification (ranging and variable peak-overlaps); trajectory aberrations and chemical structure; and particle sizing. This paper presents how these issues can be addressed by the application of bespoke data analysis tools and correlative microscopy. A discussion follows concerning the achievable precision in these measurements, with reference to the fundamental limiting factors.

  7. Precipitation sensitivity to alloy composition in Fe-Cr-Mn austenitic steels developed for reduced activation for fusion application

    International Nuclear Information System (INIS)

    Maziasz, P.J.; Klueh, R.L.

    1988-01-01

    Special austenitic steels are being designed in which alloying elements like Mo, Nb, and Ni are replaced with Mn, W, V, Ti, and/or Ta to reduce the long-term radioactivity induced by fusion reactor irradiation. However, the new steels still need to have properties otherwise similar to commercial steels like type 316. Precipitation strongly affects strength and radiation-resistance in austenitic steels during irradiation at 400--600/degree/C, and precipitation is also usually quite sensitive to alloy composition. The initial stage of development was to define a base Fe-Cr-Mn-C composition that formed stable austenite after annealing and cold-working, and resisted recovery or excessive formation of coarse carbide and intermetallic phases during elevated temperature annealing. These studies produced a Fe-12Cr-20Mn-0.25C base alloy. The next stage was to add the minor alloying elements W, Ti, V, P, and B for more strength and radiation-resistance. One of the goals was to produce fine MC precipitation behavior similar to the Ti-modified Fe-Cr-Ni prime candidate alloy (PCA). Additions of Ti+V+P+B produced fine MC precipitation along network dislocations and recovery/recrystallization resistance in 20% cold worked material aged at 800/degree/C for 166h, whereas W, Ti, W+Ti, or Ti+P+B additions did not. Addition of W+Ti+V+P+B also produced fine MC, but caused some σ phase formation and more recrystallization as well. 29 refs., 14 figs., 9 tabs

  8. Chemical compatibility of Eurofer steel with sodium-potassium NaK-78 eutectic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Sena, A., E-mail: ali.abou-sena@kit.edu [Institute for Neutron Physics and Reactor Technology (INR), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Arbeiter, F. [Institute for Neutron Physics and Reactor Technology (INR), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Baumgaertner, S. [Institute for Applied Materials – Applied Materials Physics (IAM-AWP), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Boettcher, T. [Institute for Neutron Physics and Reactor Technology (INR), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Heinzel, A. [Institute for Pulsed Power and Microwave Technology (IHM), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Piecha, H. [Institute for Nuclear and Energy Technologies (IKET), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Zinn, K. [Institute for Neutron Physics and Reactor Technology (INR), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany)

    2016-02-15

    Highlights: • Eurofer SSTT specimens were immersed in static NaK-78 for 6 months at 480–500 °C. • The Eurofer steel did not suffer any degradation in its mechanical properties. • The chemical interaction between Eurofer specimens and NaK-78 was minimal. • Using NaK-78, with low oxygen content, is feasible for the IFMIF HFTM capsules. - Abstract: In the high flux area of the International Fusion Materials Irradiation Facility (IFMIF) neutron source, the capsules of the High Flux Test Module (HFTM) contain SSTT Eurofer specimens for fusion relevant irradiation at temperature up to 550 °C. Using the sodium potassium eutectic alloy NaK-78 to fill the gaps among the Eurofer specimens stacked inside the HFTM capsules was introduced in order to improve the thermal conduction among all specimens and have uniform and predictable temperature distribution. Therefore the objective of this study is to investigate the chemical compatibility between Eurofer steel and NaK-78 to evaluate the applicability of this concept. In the present experiment, the SSTT Eurofer specimens were immersed in static NaK-78 inside a capsule made of Eurofer and kept under IFMIF HFTM-relevant conditions including high temperature (cycling between 480 °C and 500 °C) and duration of six months. Following the experiment, mechanical tests (tensile and Charpy impact) of the Eurofer specimens were performed in addition to surface and microstructure analyses to detect any relevant corrosion or degradation. The mechanical tests revealed that the Eurofer specimens did not show any degradation in their mechanical properties. Also, the surface and microstructure analyses showed that the chemical interaction between the Eurofer steel and NaK-78 was minimal after six month of exposure at cyclic temperature between 480 and 500 °C.

  9. One-Step Quenching and Partitioning Heat Treatment of Medium Carbon Low Alloy Steel

    Science.gov (United States)

    Tariq, Fawad; Baloch, Rasheed Ahmed

    2014-05-01

    This paper presents the results of novel one-step quenching and partitioning (Q&P) heat treatment conducted on medium carbon low alloy steel sheet. Samples were austenitised at 1193 K followed by interrupted quenching at 473 K for different partitioning times and finally they were quenched in water. Dilatometry was employed for selection of treatment temperatures. Optical and scanning electron microscopy was carried out to examine the microstructural changes. Volume fraction of retained austenite was measured by x-ray diffraction technique. Resulting microstructures were correlated with the mechanical properties such hardness, tensile strength, elongation, impact absorbed energy, etc. The notch tensile and fracture toughness properties of Q&P steels are still lacking therefore notch tensile strength and plain strain fracture toughness tests were conducted and results are reported here. Results of Q&P treatments were also compared with the properties obtained by conventional Quenching and Tempering (Q&T) and normalizing treatments. Optimum strength-ductility balance of about 2000 MPa tensile strength with 11% elongation was achieved in samples quenched at 473 K and isothermally partitioned for 100 s. Higher ductility of Q&P steel was attributed to the presence of 6.8% film-type interlath retained austenite. Fine-grained martensitic structure with high density of interphase boundaries imparted ultrahigh strength. It was further noted that the impact toughness, notch tensile strength and fracture toughness of 1000 s partitioned samples was higher than 100 s partitioned samples. Possible reasons for high toughness are synergetic effect of recovery of dislocations, partial loss of martensite tetragonality and precipitation of fine transition carbides.

  10. Microstructural evolution of cold-sprayed Inconel 625 superalloy coatings on low alloy steel substrate

    International Nuclear Information System (INIS)

    Chaudhuri, Atanu; Raghupathy, Y.; Srinivasan, Dheepa; Suwas, Satyam; Srivastava, Chandan

    2017-01-01

    This study illustrates microstructural evolution of INCONEL 625 superalloy coatings cold-sprayed on a 4130 chrome alloy steel with medium carbon content. INCONEL 625 powder (5–25 μm) were successfully cold sprayed without any oxidation. The comprehensive microstructure analysis of the as-sprayed coatings and of the substrate-coating interface was carried out using EBSD, TEM, and XRD. The coating microstructure at the substrate-coating interface was markedly different from the microstructure away from the interface. The coating microstructure at steel-coating interface consisted of a fine layer of small grains. The microstructure beyond this fine layer can be divided into splats, inter splat and intra splat boundaries. Both splat and splat boundaries exhibited deformation induced dislocations. Dynamic recovery of dislocations-ridden regions inside the splat was responsible for the development of sub grain structure inside a splat with both low and high angle grain boundaries. Splat-splat (inter splat) boundary consisted of a relatively high density of dislocations and shear bands as a result of adiabatic shear flow localisation. This flow instability is believed to enhance the microstructural integrity by eliminating porosity at splat-splat boundaries. Based on the microstructural analysis using electron microscopy, a plausible mechanism for the development of microstructure has been proposed in this work. Cold spray technique can thus be deployed to develop high quality coatings of commercial importance. - Graphical abstract: Schematics of the evolution of microstructure at the 4130 steel substrate close to interface. i) initial deformation close to interface. ii) Accumulation of dislocation in the substrate. iii) Formation of cell structure due to dislocation tangling and arrangement. iv) Dislocation rearrangement and subgrain formation. v.a) Formation HAGB from dislocation accumulation into LAGB. v.b) HAGB formation through DRX by progressive lattice rotation

  11. Special Features of Structure Formation in Pipes from Medium-Carbon Low-Alloy Steel 32G2F Under Heat Treatment

    Science.gov (United States)

    Stepanov, A. I.; Belikov, S. V.; Musikhin, S. A.; Burmasov, S. P.; Popov, A. A.

    2017-03-01

    Special features of formation of structure and properties of seamless pipes from medium-carbon low-alloy steel for oil and gas applications are considered and associated with chemical inhomogeneity of the metal of the pipes.

  12. Laser cladding of stainless steel with a copper-silver alloy to generate surfaces of high antimicrobial activity

    Science.gov (United States)

    Hans, Michael; Támara, Juan Carlos; Mathews, Salima; Bax, Benjamin; Hegetschweiler, Andreas; Kautenburger, Ralf; Solioz, Marc; Mücklich, Frank

    2014-11-01

    Copper and silver are used as antimicrobial agents in the healthcare sector in an effort to curb infections caused by bacteria resistant to multiple antibiotics. While the bactericidal potential of copper and silver alone are well documented, not much is known about the antimicrobial properties of copper-silver alloys. This study focuses on the antibacterial activity and material aspects of a copper-silver model alloy with 10 wt% Ag. The alloy was generated as a coating with controlled intermixing of copper and silver on stainless steel by a laser cladding process. The microstructure of the clad was found to be two-phased and in thermal equilibrium with minor Cu2O inclusions. Ion release and killing of Escherichia coli under wet conditions were assessed with the alloy, pure silver, pure copper and stainless steel. It was found that the copper-silver alloy, compared to the pure elements, exhibited enhanced killing of E. coli, which correlated with an up to 28-fold increased release of copper ions. The results show that laser cladding with copper and silver allows the generation of surfaces with enhanced antimicrobial properties. The process is particularly attractive since it can be applied to existing surfaces.

  13. Influence of Magnesium Ions in the Seawater Environment on the Improvement of the Corrosion Resistance of Low-Chromium-Alloy Steel

    Directory of Open Access Journals (Sweden)

    Sol-Ji Song

    2018-01-01

    Full Text Available This study examined the synergic effect of alloying the element Cr and the environmental element Mg2+ ions on the corrosion property of a low-alloy steel in seawater at 60 °C, by means of electrochemical impedance spectroscopy (EIS, linear polarization resistance (LPR tests and weight-loss tests. The Mg2+ ions in seawater played an important role in lowering the electron transfer of the rust layer in the Cr-containing steel. The corrosion resistance of the Cr-containing steel is superior to that of blank steel in Mg2+ ions containing seawater. XPS and XRD results indicated that the formation of MgFe2O4 and a mixed layer (Cr oxide + FeCr2O4 + MgCr2O4 improved the corrosion resistance of the low-alloy steel in the seawater.

  14. Effect of material flow on joint strength in activation spot joining of Al alloy and steel sheets

    Science.gov (United States)

    Watanabe, Goro; Yogo, Yasuhiro; Takao, Hisaaki

    2014-08-01

    A new joining method for dissimilar metal sheets was developed where a rotated consumable rod of Al alloy is pressed onto an Al alloy sheet at the part overlapped with a mild steel sheet. The metal flow in the joining region is increased by the through-hole in the Al sheet and consumable Al rod. The rod creates the joint interface and pads out of the thinly joined parts through pressing. This produces a higher joint strength than that of conventional friction stir spot welding. Measurements of the joint interface showed the presence of a 5-10 nm thick amorphous layer consisting of Al and Mg oxides.

  15. Effect of material flow on joint strength in activation spot joining of Al alloy and steel sheets

    International Nuclear Information System (INIS)

    Watanabe, Goro; Yogo, Yasuhiro; Takao, Hisaaki

    2014-01-01

    A new joining method for dissimilar metal sheets was developed where a rotated consumable rod of Al alloy is pressed onto an Al alloy sheet at the part overlapped with a mild steel sheet. The metal flow in the joining region is increased by the through-hole in the Al sheet and consumable Al rod. The rod creates the joint interface and pads out of the thinly joined parts through pressing. This produces a higher joint strength than that of conventional friction stir spot welding. Measurements of the joint interface showed the presence of a 5-10 nm thick amorphous layer consisting of Al and Mg oxides

  16. A preliminary investigation of the initiation of pitting corrosion in austenitic stainless steels and nickel-based alloys

    International Nuclear Information System (INIS)

    Higginson, A.

    1984-01-01

    Pitting corrosion in a number of austenitic stainless steels and nickel-based alloys that differ widely in their resistance to corrosion was studed by electrochemical and electron-optical techniques. The effect of contamination of the sulphuric acid electrolyte by chloride ions was also investigated. Preliminary results for the surface analysis of samples of 316 stainless steel by Auger electron spectroscopy are presented, and suggestions are included for further application of this technique to the examination of pitting corrosion. A comprehensive review of the literature concerning the initiation of pitting corrosion is included

  17. Effect of thermomechanical treatment on the resistance of low-carbon low-alloy steel to brittle fracture

    Science.gov (United States)

    Schastlivtsev, V. M.; Tabatchikova, T. I.; Yakovleva, I. L.; Del'gado Reina, S. Yu.; Golosienko, S. A.; Pazilova, U. A.; Khlusova, E. I.

    2015-02-01

    Structure and mechanical properties of rolled plates (20-35 mm thick) of low-carbon low-alloy steel subjected to thermomechanical treatment (TMT) according to various regimes under laboratory and industrial conditions have been studied. Structural factors that favor obtaining high mechanical properties have been established. The retarding action of TMT on softening upon tempering has been revealed. The reasons for the decrease in the resistance to brittle fracture of the steel subjected to TMT, repeated quenching from the temperature of the furnace heating, and tempering have been determined.

  18. Fast Salt Bath Heat Treatment for a Bainitic/Martensitic Low-Carbon Low-Alloyed Steel

    Science.gov (United States)

    Urbanec, Julia; Saastamoinen, Ari; Kivivuori, Seppo; Louhenkilpi, Seppo

    2015-11-01

    The mechanical properties of a low-alloyed steel with 0.06 wt pct C were investigated after a series of heat treatment processes using salt bath followed by quenching into water in order to obtain bainitic/martensitic steel. Salt bath holding time varied from 30 to 330 seconds. Hardness, tensile properties and toughness have been examined. The results show the obtained microstructure significantly enhances the impact strength (up to 187 J) and toughness (up to 71.4 pct critical reduction) with good hardness (239 ± 4 HV) and tensile strength (720 to 800 MPa) compared to direct quenching heat treatment without salt bath holding.

  19. Chemical Changes at the Interface Between Low Carbon Steel and an Al-Si Alloy During Solution Heat Treatment

    OpenAIRE

    Zhe, M.; Dezellus, O.; Gardiola, B.; Braccini, M.; Viala, J.C.

    2011-01-01

    International audience; The aim of this work was to characterize the chemical changes during solid state solution heat treatment of a metallurgically bonded steel/Al-Si interface. For this purpose, low carbon steel plates covered with the A-S7G03 aluminium alloy (7wt%Si, 0.3wt%Mg analogous to A356) were prepared by dip coating, water-quenching to room temperature and reheating in the solid state at 480-560°C for 3 to 160 hours. Upon reheating at 535 °C, a reaction layer was observed to grow a...

  20. Identification of low cycle fatigue parameters of high strength low-alloy (HSLA steel at room temperature

    Directory of Open Access Journals (Sweden)

    S. Bulatović

    2014-10-01

    Full Text Available Low cycle fatigue test was performed in ambient atmosphere at room temperature. Cycle loading of material, in case of High strength low-alloy steel, entails modifications of its properties and in this paper is therefore shown behavior of fatigue life using low cycle fatigue parameters. More precisely, crack initiation life of tested specimens was computed using theory of Coffin-Manson relation during the fatigue loading. The geometry of the stabilized hysteresis loop of welded joint HSLA steel, marked as Nionikral 70, is also analyzed. This stabilized hysteresis loop is very important for determination of materials properties.

  1. Corrosion behaviour of austenitic stainless steel, nickel-base alloy and its weldments in aqueous LiBr solutions

    Energy Technology Data Exchange (ETDEWEB)

    Blasco-Tamarit, E.; Igual-Munoz, A.; Garcia Anton, J.; Garcia-Garcia, D. [Departamento de Ingenieria Quimica y Nuclear. E.T.S.I.Industriales, Universidad Politecnica de Valencia, P.O. Box 22012 E-46071 Valencia (Spain)

    2004-07-01

    With the advances in materials production new alloys have been developed, such as High- Alloy Austenitic Stainless Steels and Nickel-base alloys, with high corrosion resistance. These new alloys are finding applications in Lithium Bromide absorption refrigeration systems, because LiBr is a corrosive medium which can cause serious corrosion problems, in spite of its favourable properties as absorbent. The objective of the present work was to study the corrosion resistance of a highly alloyed austenitic stainless steel (UNS N08031) used as base metal, a Nickel-base alloy (UNS N06059) used as its corresponding filler metal, and the weld metal obtained by the Gas Tungsten Arc Welding (GTAW) procedure. The materials have been tested in different LiBr solutions (400 g/l, 700 g/l, 850 g/l and a commercial 850 g/l LiBr heavy brine containing Lithium Chromate as corrosion inhibitor), at 25 deg. C. Open Circuit Potential tests and potentiodynamic anodic polarization curves have been carried out to obtain information about the general electrochemical behaviour of the materials. The polarization curves of all the alloys tested were typical of passivable materials. Pitting corrosion susceptibility has been evaluated by means of cyclic potentiodynamic curves, which provide parameters to analyse re-passivation properties. The galvanic corrosion generated by the electrical contact between the welded and the base material has been estimated from the polarization diagrams according to the Mixed Potential Method. Samples have been etched to study the microstructure by Scanning Electron Microscopy (SEM). The results demonstrate that the pitting resistance of all these materials increases as the LiBr concentration decreases. In general, the presence of chromate tended to shift the pitting potential to more positive values than those obtained in the 850 g/l LiBr solution. (authors)

  2. Stress corrosion cracking behaviour of low alloy steels in high temperature water: Description and results from modelling

    International Nuclear Information System (INIS)

    Tirbonod, B.

    2001-01-01

    The initiation and growth of a crack by stress and corrosion in the low alloy steels used for the pressure vessels of Boiling Water Reactors may affect the availability and safety of the plant. This paper presents a new model for stress corrosion cracking of the low alloy steels in high temperature water. The model, based on observations, assumes the crack growth mechanism to be based on an anodic dissolution and cleavage. The main results deal with the position of the dissolution cell found at the crack tip, and with the identification of the parameters sensitive to crack growth, among which are the electrolyte composition and the cleavage length. The model is conservative, in qualitative agreement with measurements conducted at PSI, and may be extended to other metal-environment systems. (author)

  3. Surface alloying of high-vanadium high-speed steel on ductile iron using plasma transferred arc technique: Microstructure and wear properties

    NARCIS (Netherlands)

    Cao, H.T.; Dong, X.P.; Pan, Z.; Wu, X.W.; Huang, Q.W.; Pei, Y.T.

    2016-01-01

    A high-vanadium high speed steel (HVHSS) alloying layer was synthesized from pre-placed powders (V-Cr-Ti-Mo) on ductile iron (DI) substrate using plasma transferred arc (PTA) technique. The PTA-alloyed layer, characterized by microhardness, optical microscopy, XRD, EDS enabled SEM, TEM and

  4. 9-12% Cr heat resistant steels. Alloy design, TEM characterisation of microstructure evolution and creep response at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Rojas Jara, David

    2011-03-21

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

  5. 9-12% Cr heat resistant steels. Alloy design, TEM characterisation of microstructure evolution and creep response at 650 C

    International Nuclear Information System (INIS)

    Rojas Jara, David

    2011-01-01

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

  6. Creep and microstructural processes in a low-alloy 2.25%Cr1.6%W steel (ASTM Grade 23)

    Czech Academy of Sciences Publication Activity Database

    Kuchařová, Květa; Sklenička, Václav; Kvapilová, Marie; Svoboda, Milan

    2015-01-01

    Roč. 109, NOV (2015), s. 1-8 ISSN 1044-5803 R&D Projects: GA TA ČR TA02010260; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Bainitic steel * Low- alloy steel * Creep strength * Microstructural changes * Carbide precipitation Subject RIV: JG - Metallurgy Impact factor: 2.383, year: 2015

  7. The assessment of non-metallic inclusions in steels and nickel alloys for ultra high vacuum applications

    International Nuclear Information System (INIS)

    Meriguet, P.J.-L.

    1992-01-01

    The presence of non-metallic inclusions in steels and nickel alloys may create leak-paths under Ultra High Vacuum conditions. This paper shows the application of the ASTM E45 standard to the assessment of these inclusions and gives some design recommendations. Three case-histories encountered at the Joint European Torus Joint Undertaking and a possible explanation of the phenomenon are also presented. (Author)

  8. Nondestructive magnetic inspection of hardened and tempered articles made out of low-alloy structural and carbon steels. 2

    International Nuclear Information System (INIS)

    Mikheev, M.N.; Gorkunov, Eh.S.; Dunaev, F.N.

    1978-01-01

    Studied was the variation of the maximum residual induction (after it has been removed by an alternating magnetic field of a specified value) as a function of heat treatment conditions. Examined were aspects of using the apparent re--sidual induction of an asymmetric particular cycle for non-destructive magnetic inspection of the quality of heat treatment of items from low-alloy structural and plain carbon steels

  9. Super ODS steel R and D for fuel cladding of next generation nuclear systems. 2) Effect of minor alloying elements

    International Nuclear Information System (INIS)

    Ohnuki, S.; Hashimoto, N.; Ukai, S.; Kimura, A.; Inoue, Masaki; Kaito, Takeji; Fujisawa, T.; Okuda, T.; Abe, F.

    2009-01-01

    For development of advanced ferritic ODS steels including high concentration of Cr and Al, the effect of minor alloying elements on fine dispersion of oxide particle was investigated. Microstructural analysis for Fe-16Cr-4Al-mY 2 O 3 -nZr or mHf due to TEM indicated that 0.3Zr or 0.6Hf are the optimum concentration. The mechanism of nano-sized oxide formation was also discussed. (author)

  10. Effect of Heat Treatment on the Impact Toughness of `High-Chromium Cast Iron - Low Alloy Steel' Bimetal Components

    Science.gov (United States)

    Özdemir, Z.

    2017-03-01

    A bimetallic `low-alloy steel - high-chromium cast iron' composite obtained by successive sand casting is studied and shown to have good cohesion on the interface and no casting defects. The hardness and the impact toughness of the bimetal increase simultaneously. The microstructure is more homogeneous after diffusion annealing at 1040°C, rapid cooling, and 3-h tempering at 270°C.

  11. Measurement of titanium and molybdenum in special steels and alloys using wavelength dispersive X-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    Hasany, S.M.; Khan, A.A.; Rehman, H.

    1998-01-01

    An X-ray fluorescence spectrometric multivariable regression procedure is described for the determination of titanium and molybdenum in special steels and alloys in the concentration range from 9.41% down to 120 μg/g using Ti Kα 1,2 and Mo Kα 1,2 analyte lines. In general, better results have been achieved in first order base curve polynomials using LiF (200) crystal in combination with scintillation counter (SC) or krypton proportional counter (KPC). However, LiF (220) + SC combination also yields favorable results for Mo. The measured concentrations of Ti and Mo for BAS alloy steel standards agree very well with their certified values. The automated XRFS method for the determination of Ti and Mo appears to be free from matrix effects and is suitable for their measurement in special steels and alloys down to 120 μg/g concentration of Ti with a precision of 3.2% and an accuracy of ±2.5% and for Mo down to 350 μg/g with a precision of <1% and an accuracy of ±1.1%. The sensitivities for these lowest concentrations are calculated to be 5960 counts/mass %/s and 8000 count/mass %/s for Ti and Mo, respectively. (author)

  12. Brazing technology of Ti alloy/stainless steel dissimilar metal joint at system integrated modular advanced reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Sang Chul; Kim, Sung Ho; Kim, Yong Wan; Kim, Jong In

    2001-02-01

    For the technoldogy development of brazing Ti alloy to stainless steel joints used at SMART, the status of brazing technology development, brazing processes, and the brazing technology of Ti alloy and stainless steel are reviewed. Because fusion welding process cannot be applied due to the formation of intermetallic compounds in the weld metal, brazing joint was selected at the design. The joint part is assembled with a thread composed with male part of Ti alloy tube and female part of stainless tube. The gap in the thread will be filled with brazing filler metal. However, brittle Ti-Fe intermetallic compounds are formed at the surface of stainless steel through the diffusion of Ti at the melt. Brazing conditions should be set-up to reduce the formation of intermetallic compounds. For that, 3 kinds of Ag filler metals were selected as the candidates and heating will be done with induction and electric furnaces. Through measuring of joint strength according to the control of pre- and post-braze treatment, heating rate and heating time, optimal brazing method will be fixed. To qualify the brazing procedure and performance and to check defects in final product, the inspection plan will be established according to the req2wuirements of AWS and ASME.

  13. Microstructure and mechanical properties of a low carbon carbide-free bainitic steel co-alloyed with Al and Si

    International Nuclear Information System (INIS)

    Qian, Lihe; Zhou, Qian; Zhang, Fucheng; Meng, Jiangying; Zhang, Ming; Tian, Yuan

    2012-01-01

    Highlight: ► A low carbon carbide-free bainitic steel was produced. ► Co-alloying with Al and Si suppresses the precipitation of cementite. ► Fine carbide-free bainite laths and thin film-like retained austenite obtained. ► Excellent combination of strength, ductility and toughness enabled. -- Abstract: A low carbon, low alloy steel has been investigated for producing low carbon carbide-free bainitic microstructure by co-addition of alloying elements of aluminum and silicon. The influence of heat treatment process on microstructure, impact toughness as well as tensile properties was investigated by light optical microscopy, transmission electron microscopy, X-ray diffraction and mechanical property tests. The results demonstrate that the co-addition of aluminum and silicon in the investigated steel plays an effective role in suppressing the precipitation of cementite. A desired microstructure consisting of mainly fine-scale carbide-free bainitic ferrite and thin film-like retained austenite located between the ferrite laths was obtained and accordingly an excellent combination of toughness, ductility and strength was achieved by optimized heat treatments, i.e. by isothermal treatment at 320 °C for ∼84 min or more. The microstructure-mechanical property relationships are discussed.

  14. Brazing technology of Ti alloy/stainless steel dissimilar metal joint at system integrated modular advanced reactor

    International Nuclear Information System (INIS)

    Kwon, Sang Chul; Kim, Sung Ho; Kim, Yong Wan; Kim, Jong In

    2001-02-01

    For the technoldogy development of brazing Ti alloy to stainless steel joints used at SMART, the status of brazing technology development, brazing processes, and the brazing technology of Ti alloy and stainless steel are reviewed. Because fusion welding process cannot be applied due to the formation of intermetallic compounds in the weld metal, brazing joint was selected at the design. The joint part is assembled with a thread composed with male part of Ti alloy tube and female part of stainless tube. The gap in the thread will be filled with brazing filler metal. However, brittle Ti-Fe intermetallic compounds are formed at the surface of stainless steel through the diffusion of Ti at the melt. Brazing conditions should be set-up to reduce the formation of intermetallic compounds. For that, 3 kinds of Ag filler metals were selected as the candidates and heating will be done with induction and electric furnaces. Through measuring of joint strength according to the control of pre- and post-braze treatment, heating rate and heating time, optimal brazing method will be fixed. To qualify the brazing procedure and performance and to check defects in final product, the inspection plan will be established according to the req2wuirements of AWS and ASME

  15. Microstructure and Mechanical Properties of Inconel 625 Alloy on Low Carbon Steel by Heat Treatment after Overlay Welding

    International Nuclear Information System (INIS)

    Kim, Seungpil; Jang, Jaeho; Kim, Jungsoo; Kim, Byung Jun; Sohn, Keun Yong; Nam, Dae-Geun

    2016-01-01

    Overlay welding technique is one of methods used to improve metal mechanical properties such as strength, toughness and corrosion resistance. Generally, Inconel 625 alloy is used for overlay welding layer on low carbon steels for economic consideration. However, the method produces some problems in the microstructure of the cast structure and some defects, caused by the elevated temperatures of the overlay process. To resolve these problems, heat treatments are required. In this study, Inconel 625 alloy was welded on a low carbon steel by the overlay welding process to investigate the resulting microstructure and mechanical properties. A double heat treatment was performed to improve the mechanical properties of the welding and substrate layers. It was found that Inconel 625 alloy had an austenite microstructure after the first heat treatment, but the low carbon steel had a ferrite-pearlite microstructure after the second heat treatment. After the double heat treatment, the sample showed the optimum hardness because of grain refinement and homogenization of the microstructure.

  16. Chloride effects on the electrochemical degradation of micro-alloyed steel in E20 simulated fuel ethanol blend

    Directory of Open Access Journals (Sweden)

    Olufunmilayo O. Joseph

    Full Text Available Biofuels play a major role as a renewable energy source in mitigating global warming. The presence of impurities in fuel ethanol has resulted into certain downsides regarding material compatibility. This work is focused on an investigation of the influence of sodium chloride (NaCl as an impurity in the electrochemical degradation of micro-alloyed steel (MAS when exposed to E20 simulated fuel grade ethanol (SFGE environment. Immersion and electrochemical tests were carried out using NaCl concentrations ranging from 0 to 64 mg/L. Highest corrosion rates were obtained with 64 mg/L NaCl and lowest rates were observed in the zero chloride tests. Chloride was also seen to cause pitting corrosion on MAS. The results of potentiodynamic polarization tests on MAS compared well with mass loss corrosion rates. Analysis of variance (ANOVA test confirms the significance of the results at 99% confidence, and further showed that there is significant difference between the chloride concentrations. However, from the perspective of corrosion in fuel ethanol, micro-alloyed steel is thought to be compatible with E20 since the determined corrosion rates were very low. Keywords: Fuel ethanol, Corrosion, Micro-alloyed steel, Chloride, Pitting

  17. Microstructure and Mechanical Properties of Inconel 625 Alloy on Low Carbon Steel by Heat Treatment after Overlay Welding

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seungpil; Jang, Jaeho; Kim, Jungsoo; Kim, Byung Jun; Sohn, Keun Yong; Nam, Dae-Geun [Korea Institute of Industrial Technology, Busan (Korea, Republic of)

    2016-08-15

    Overlay welding technique is one of methods used to improve metal mechanical properties such as strength, toughness and corrosion resistance. Generally, Inconel 625 alloy is used for overlay welding layer on low carbon steels for economic consideration. However, the method produces some problems in the microstructure of the cast structure and some defects, caused by the elevated temperatures of the overlay process. To resolve these problems, heat treatments are required. In this study, Inconel 625 alloy was welded on a low carbon steel by the overlay welding process to investigate the resulting microstructure and mechanical properties. A double heat treatment was performed to improve the mechanical properties of the welding and substrate layers. It was found that Inconel 625 alloy had an austenite microstructure after the first heat treatment, but the low carbon steel had a ferrite-pearlite microstructure after the second heat treatment. After the double heat treatment, the sample showed the optimum hardness because of grain refinement and homogenization of the microstructure.

  18. Evaluation of a Belt-Cast Austenitic Steel Alloy from Salzgitter Mannesmann Forschung: Effect of Hardness on the Ballistic Resistance against Two 0.30-cal. Projectile Types

    Science.gov (United States)

    2017-08-01

    manufacturing technology and requisite alloy compositions for the production of high-strength and high-ductility security steels. Security steels...company was still experiencing fabrication issues that prevent the material from being fabricated in thicker sections. Therefore, currently, only 5-mm... production , an extended period of negotiations was required to obtain representative samples of this experimental steel from Salzgitter. As a result, 5

  19. Analysis Of The Austenite Grain Growth In Low-Alloy Boron Steel With High Resistance To Abrasive Wear

    Directory of Open Access Journals (Sweden)

    Białobrzeska B.

    2015-09-01

    Full Text Available Today low-alloy steels with boron achieve high resistance to abrasive wear and high strength. These features are obtained by using advanced technology of manufacturing. This makes boron steels increasingly popular and their application more diverse. Application of these steels can extend the lifetime of very expensive machine construction in many industries such as mining, the automotive, and agriculture industries. An interesting subgroup of these materials is steel with boron intended for heat treatment. These steels are supplied by the manufacturer after cold or hot rolling so that it is possible for them to be heat treated in a suitable manner by the purchaser for its specific application. Very important factor that determines the mechanical properties of final product is austenite grain growth occurring during hot working process such us quenching or hot rolling. Investigation of the effect of heating temperature and holding time on the austenite grain size is necessary to understand the growth behavior under different conditions. This article presents the result of investigation of austenite grain growth in selected low-allow boron steel with high resistance to abrasive wear and attempts to describe the influence of chemical composition on this process.

  20. Cessation of environmentally-assisted cracking in a low-alloy steel: Experimental results

    International Nuclear Information System (INIS)

    Li, Y.Y.

    1997-01-01

    The presence of dissolved metallurgical sulfides in pressure vessel and piping steels has been linked to Environmentally-Assisted Cracking (EAC), a phenomenon observed in laboratory tests that results in fatigue crack growth rates as high as 100 times that in air. Previous experimental and analytical work based on diffusion as the mass transport process has shown that surface cracks that are initially clean of sulfides will not initiate EAC in most applications. This is because the average crack tip velocity would not be sufficiently high to expose enough metallurgical sulfides per unit time and produce the sulfide concentration required for EAC. However, there is a potential concern for the case of a relatively large embedded crack breaking through to the wetted surface. Such a crack would not be initially clean of sulfides, and EAC could initiate. This paper presents the results of a series of experiments conducted on two heats of an EAC susceptible, high-sulfur, low-alloy steel in 243 degrees C low-oxygen water to further study the phenomenon of EAC persistence at low crack tip velocities. A load cycle profile that incorporated a significant load dwell period at minimum load was used. In one experiment, the fatigue cycling history was such that relatively high crack tip velocities at the start of the experiment produced a persistent case of EAC even when crack tip velocities were later reduced to levels below the EAC initiation velocity. The other series of experiments used initial crack tip velocities that were much lower and probably more realistic. Air precracking of the compact tension specimens produced an initial inventory of undissolved sulfides on the crack flanks that directly simulates the array of sulfides expected from the breakthrough of an embedded crack. In all cases, results showed EAC ceased after several hundred hours of cycling

  1. Application of Finite Element Method (FEM for definition of the relationship between properties of laser alloyed steel surface layer

    Directory of Open Access Journals (Sweden)

    A. Śliwa

    2017-01-01

    Full Text Available Investigations include FEM simulation model of alloying the PMHSS6-5-3 steel surface layer with the carbides and ceramic powders, especially WC, VC, TiC, SiC, Si3N4 and Al2O3 particles using the high power diode laser (HPDL. The FEM computations were performed using ANSYS software. The scope of FEM simulation was determination of temperature distribution during laser alloying process at various process configurations regarding laser beam power and method of powder deposition, as pre coated past or surface with machined grooves. The FEM simulation allows specifying the heat affected zone and the temperature distribution in the sample as a function of time and thus allows the estimation of the structural changes taking place during laser alloying process.

  2. Preliminary Investigation of the Corrosion Behavior of Proprietary Micro-alloyed Steels in Aerated and Deaerated Brine Solutions

    Science.gov (United States)

    Onyeji, Lawrence; Kale, Girish

    2017-12-01

    The corrosion performance of fairly new generation of micro-alloyed steels was compared in different concentrations of aerated and deaerated brines. Electrochemical polarization, weight loss and surface analyses techniques were employed. The results showed a threshold of corrosion rate at 3.5 wt.% NaCl in both aerated and deaerated solutions. The average corrosion current density for steel B, for example, increased from 1.3 µA cm-2 in 1 wt.% NaCl to 1.5 µA cm-2 in 3.5 wt.% NaCl, but decreased to 1.4 µA cm-2 in 10 wt.% deaerated NaCl solutions. The aerated solutions exhibited an average of over 80% increase in corrosion current density in the respective concentrations when compared with the deaerated solution. These results can be attributed to the effects of dissolved oxygen (DO) which has a maximum solubility in 3.5 wt.% NaCl. DO as a depolarizer and electron acceptor in cathodic reactions accelerates anodic metal dissolution. The difference in carbon content and microstructures occasioned by thermo-mechanical treatment contributed to the witnessed variation in corrosion performance of the steels. Specifically, the results of the various corrosion techniques corroborated each other and showed that the corrosion rate of the micro-alloyed steels can be ranked as CRSteel A < CRX65 < CRSteel B < CRSteel C.

  3. Corrosion and Fatigue Behavior of High-Strength Steel Treated with a Zn-Alloy Thermo-diffusion Coating

    Science.gov (United States)

    Mulligan, C. P.; Vigilante, G. N.; Cannon, J. J.

    2017-11-01

    High and low cycle fatigue tests were conducted on high-strength steel using four-point bending. The materials tested were ASTM A723 steel in the as-machined condition, grit-blasted condition, MIL-DTL-16232 heavy manganese phosphate-coated condition, and ASTM A1059 Zn-alloy thermo-diffusion coated (Zn-TDC). The ASTM A723 steel base material exhibits a yield strength of 1000 MPa. The effects of the surface treatments versus uncoated steel were examined. The fatigue life of the Zn-TDC specimens was generally reduced on as-coated specimens versus uncoated or phosphate-coated specimens. Several mechanisms are examined including the role of compressive residual stress relief with the Zn-TDC process as well as fatigue crack initiation from the hardened Zn-Fe alloy surface layer produced in the gas-metal reaction. Additionally, the effects of corrosion pitting on the fatigue life of coated specimens are explored as the Zn-TDC specimens exhibit significantly improved corrosion resistance over phosphate-coated and oiled specimens.

  4. Effect of Heat Treatment on Mechanical Properties and Microstructure Morphology of Low-Alloy High-Strength Steel

    Directory of Open Access Journals (Sweden)

    Bolanowski K.

    2016-06-01

    Full Text Available The paper analyzes the influence of different heat treatment processes on the mechanical properties of low-alloy high-strength steel denoted by Polish Standard (PN as 10MnVNb6. One of the findings is that, after aging, the mechanical properties of rolled steel are high: the yield strength may reach > 600 MPa, and the ultimate tensile strength is > 700 MPa. These properties are largely dependent on the grain size and dispersion of the strengthening phase in the ferrite matrix. Aging applied after hot rolling contributes to a considerable rise in the yield strength and ultimate tensile strength. The process of normalization causes a decrease in the average grain size and coalescence (reduction of dispersion of the strengthening phase. When 10MnVNb6 steel was aged after normalization, there was not a complete recovery in its strength properties.

  5. The role of nitrogen in improving pitting corrosion resistance of high-alloy austenitic and duplex stainless steel welds

    International Nuclear Information System (INIS)

    Vilpas, M.; Haenninen, H.

    1999-01-01

    The effects of nitrogen alloyed shielding gas on weld nitrogen content and pitting corrosion resistance of super austenitic (6%Mo) and super duplex stainless steels have been studied with special emphasis on microsegregation behaviour of Cr, Mo and N. The measurements performed with the 6%Mo steel indicate that all these elements segregate interdendritically in the fully austenitic weld metal. With nitrogen addition to the shielding gas the enrichment of nitrogen to the interdendritic regions is more pronounced than to the dendrite cores due to which the pitting corrosion resistance of the dendrite cores increases only marginally. In the super duplex steel welds nitrogen enriches in austenite increasing its pitting corrosion resistance more effectively. In these welds the pitting corrosion resistance of the ferrite phase remains lower. (orig.)

  6. Morphology and distribution of precipitates in extra low carbon steels micro alloyed with Ti, Nb and B tested by hot torsion

    International Nuclear Information System (INIS)

    Silva, Julio Marcio Silveira e; Dahl, Winfried; Barbosa, Ronaldo

    1996-01-01

    In the last decade, a great number of publications has been dedicated to the study of precipitation in micro alloyed steels. The present work deals with the morphology and distribution of simple as well as complex precipitates in two extra low C steels micro alloyed with Nb T i and Nb T i-B. The effect of different pre-deformation conditions on precipitation in these steels is showed and discussed. Results indicate that both nature of sites for nucleation and distribution of precipitates are influenced by chemical composition and by pre-deformation conditioning of the austenite. (author)

  7. Gas atomized precursor alloy powder for oxide dispersion strengthened ferritic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Rieken, Joel [Iowa State Univ., Ames, IA (United States)

    2011-12-13

    Gas atomization reaction synthesis (GARS) was employed as a simplified method for producing precursor powders for oxide dispersion strengthened (ODS) ferritic stainless steels (e.g., Fe-Cr-Y-(Ti,Hf)-O), departing from the conventional mechanical alloying (MA) process. During GARS processing a reactive atomization gas (i.e., Ar-O2) was used to oxidize the powder surfaces during primary break-up and rapid solidification of the molten alloy. This resulted in envelopment of the powders by an ultra-thin (t < 150 nm) metastable Cr-enriched oxide layer that was used as a vehicle for solid-state transport of O into the consolidated microstructure. In an attempt to better understand the kinetics of this GARS reaction, theoretical cooling curves for the atomized droplets were calculated and used to establish an oxidation model for this process. Subsequent elevated temperature heat treatments, which were derived from Rhines pack measurements using an internal oxidation model, were used to promote thermodynamically driven O exchange reactions between trapped films of the initial Cr-enriched surface oxide and internal Y-enriched intermetallic precipitates. This novel microstructural evolution process resulted in the successful formation of nano-metric Y-enriched dispersoids, as confirmed using high energy X-ray diffraction and transmission electron microscopy (TEM), equivalent to conventional ODS alloys from MA powders. The thermal stability of these Y-enriched dispersoids was evaluated using high temperature (1200°C) annealing treatments ranging from 2.5 to 1,000 hrs of exposure. In a further departure from current ODS practice, replacing Ti with additions of Hf appeared to improve the Y-enriched dispersoid thermal stability by means of crystal structure modification. Additionally, the spatial distribution of the dispersoids was found to depend strongly on the original rapidly solidified microstructure. To exploit this, ODS microstructures were engineered from

  8. Influence of 'third' elements and structure on the results of spectral analysis of high alloyed steels and cast iron with glow discharge

    International Nuclear Information System (INIS)

    Buravlev, Yu.M.; Zamarajev, V.P.; Chernyavskaya, N.V.

    1989-01-01

    The experimental technique consists in estimation of mutual arrangement of the calibration curves obtained using standard reference materials of low-alloyed and high-alloyed (high-chrome, stainless, high-speed) steels as well as of the curves for carbon steels and cast iron differing in their structure. ARL-31000 and Polyvac E-1000 quantometers with U=1300 V, I=0.12 A and argon pressure ∼1 kPa are used. The influence of third elements is shown in shift and slope changes of the curves for abovementioned high-alloyed steels in comparison to ones for low-alloyed steels accepted as basic. The influence magnitude runs up to 10-30 relative percents and more in the case of analysis of carbon, phosphorus, sulfur, silicon and other elements and depends on the type of the element and on the alloy composition. It is shown that the contribution of structure factor caused by different alloy thermal treatment makes up 10 to 20 relative percents. The experiments showed that the increase of influence of these factors caused by their imposing as well as the weakening of this influence caused by their counteraction is possible. When analyzed alloys differ in their composition and manufacturing technology it is necessary to take into consideration the influence of these effects. (author)

  9. Mechanical Properties and Corrosion-Abrasion Wear Behavior of Low-Alloy MnSiCrB Cast Steels Containing Cu

    Science.gov (United States)

    Luo, Kaishuang; Bai, Bingzhe

    2011-01-01

    Two medium carbon low-alloy MnSiCrB cast steels containing different Cu contents (0.01 wt pct and 0.62 wt pct) were designed, and the effect of Cu on the mechanical properties and corrosion-abrasion wear behavior of the cast steels was studied. The results showed that the low-alloy MnSiCrB cast steels obtained excellent hardenability by a cheap alloying scheme. The microstructure of the MnSiCrB cast steels after water quenching from 1123 K (850 °C) consists of lath martensite and retained austenite. After tempering at 503 K (230 °C), carbides precipitated, and the hardness of the cast steels reached 51 to 52 HRC. The addition of Cu was detrimental to the ductility and impact toughness but was beneficial to the wear resistance in a corrosion-abrasion wear test. The MnSiCrB cast steel with Cu by the simple alloying scheme and heat treatment has the advantages of being high performance, low cost, and environmentally friendly. It is a potential, advanced wear-resistant cast steel for corrosion-abrasion wear conditions.

  10. Simultaneous first order derivative spectrophotometric determination of vanadium and zirconium in alloy steels and minerals.

    Science.gov (United States)

    Varghese, Anitha; George, Louis

    2012-09-01

    A simple, selective and sensitive spectrophotometric method has been developed for the individual and simultaneous determination of trace amounts of vanadium(V) and zirconium(IV) in acetic acid medium using a newly synthesised reagent diacetylmonoxime salicyloylhydrazone (DMSH), without any prior separation. The molar absorptivity and Sandell's sensitivity of the coloured species are 1.30 x 10(4) and 1.82 x 10(4) L mol(-1)cm(-1) and 3.9 and 2.5 ng cm(-2) for V(V) and Zr(IV), respectively. Beer's law is obeyed between 0.26-2.80 and 0.30-3.20 μg mL(-1) concentration of vanadium (V) and zirconium (IV) at 405 and 380 nm respectively. The stoichiometry of the complex was found to be 1:1 (metal:ligand) for V(V) and 1:2 for Zr(IV) complexes. These metal ions interfere with the determination of each other in zero order spectrophotometry. The first derivative spectra of these complexes permitted a simultaneous determination of V(V) and Zr(IV) at zero crossing wavelengths of 445 nm and 405 nm, respectively. The optimum conditions for maximum colour development and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of zirconium and vanadium in standard alloy steel samples, mineral and soil samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Microstructural Evolution of Inverse Bainite in a Hypereutectoid Low-Alloy Steel

    Science.gov (United States)

    Kannan, Rangasayee; Wang, Yiyu; Li, Leijun

    2017-12-01

    Microstructural evolution of inverse bainite during isothermal bainite transformation of a hypereutectoid low-alloy steel at 773 K (500 °C) was investigated through a series of interrupted isothermal experiments using a quench dilatometer. Microstructural characterization revealed that the inverse bainitic transformation starts by the nucleation of cementite (Fe3C) from parent austenite as a midrib in the bainitic microstructure. The inverse bainite becomes "degenerated" to typical upper bainite at prolonged transformation times. Crystallographic orientation relationships between the individual phases of inverse bainite microstructure were found to obey { _{γ } || _{θ } } { _{α } || _{θ } } { _{γ } || _{α } } 111_{γ } || { \\overline{2} 21} _{θ } } { 110} _{α } || { \\overline{2} 21} _{θ } } { 111} _{γ } || { 110 } _{α } {111} _{γ } || {211} _{θ } {110} _{α } || {211} _{θ } Furthermore, the crystallographic orientation deviations between the individual phases of inverse bainite microstructure suggest that the secondary carbide nucleation occurs from the inverse bainitic ferrite. Thermodynamic driving force calculations provide an explanation for the observed nucleation sequence in inverse bainite. The degeneracy of inverse bainite microstructure to upper bainite at prolonged transformation times is likely due to the effects of cementite midrib dissolution at the early stage and secondary carbide coarsening at the later stage.

  12. Evaluation of Alumina-Forming Austenitic Stainless Steel Alloys in Microturbines

    Energy Technology Data Exchange (ETDEWEB)

    Brady, M.P.; Matthews, W.J. (Capstone Turbine Corp.)

    2010-09-15

    Oak Ridge National Laboratory (ORNL) and Capstone Turbine Corporation (CTC) participated in an in-kind cost share cooperative research and development agreement (CRADA) effort under the auspices of the Energy Efficiency and Renewable Energy (EERE) Technology Maturation Program to explore the feasibility for use of developmental ORNL alumina-forming austenitic (AFA) stainless steels as a material of construction for microturbine recuperator components. ORNL delivered test coupons of three different AFA compositions to CTC. The coupons were exposed in steady-state elevated turbine exit temperature (TET) engine testing, with coupons removed for analysis after accumulating ~1,500, 3,000, 4,500, and 6,000 hours of operation. Companion test coupons were also exposed in oxidation testing at ORNL at 700-800°C in air with 10% H2O. Post test assessment of the coupons was performed at ORNL by light microscopy and electron probe microanalysis. The higher Al and Nb containing AFA alloys exhibited excellent resistance to oxidation/corrosion, and thus show good promise for recuperator applications.

  13. Low Cycle Fatigue behavior of SMAW welded Alloy28 superaustenitic stainless steel at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kchaou, Y., E-mail: yacinekchaou@yahoo.fr [Institut Pprime, Département Physique et Mécanique des Matériaux, UPR 3346 CNRS ISAE-ENSMA Université de Poitiers, Téléport 2, 1, avenue Clément Ader, BP 40109, F – 86961 Futuroscope Chasseneuil Cedex (France); Laboratoire de Génie des Matériaux et Environnement (LGME), ENIS, BPW 1173, Sfax (Tunisia); Pelosin, V.; Hénaff, G. [Institut Pprime, Département Physique et Mécanique des Matériaux, UPR 3346 CNRS ISAE-ENSMA Université de Poitiers, Téléport 2, 1, avenue Clément Ader, BP 40109, F – 86961 Futuroscope Chasseneuil Cedex (France); Haddar, N.; Elleuch, K. [Laboratoire de Génie des Matériaux et Environnement (LGME), ENIS, BPW 1173, Sfax (Tunisia)

    2016-01-10

    This paper focused on the study of Low Cycle Fatigue of welded joints of superaustenitic (Alloy28) stainless steels. Chemical composition and microstructure investigation of Base Metal (BM) and Weld Metal (WM) were identified. The results showed that both of composition is fully austenitic with a dendritic microstructure in the WM. Low cycle fatigue tests at different strain levels were performed on Base Metal (BM) and Welded Joint (WJ) specimens with a strain ratio R{sub ε}=−1. The results indicated that the fatigue life of welded joints is lower than the base metal. This is mainly due to the low ductility of the Welded Metal (WM) and the presence of welding defects. Simultaneously, Scanning Electron Microscope (SEM) observations of fractured specimens show that WJ have brittle behavior compared to BM with the presence of several welding defects especially in the crack initiation site. An estimation of the crack growth rate during LCF tests of BM and WJ was performed using distance between striations. The results showed that the crack initiation stage is shorter in the case of WJ compared to BM because of the presence of welding defects in WJ specimens.

  14. Metallurgical and mechanical properties of laser welded high strength low alloy steel.

    Science.gov (United States)

    Oyyaravelu, Ramachandran; Kuppan, Palaniyandi; Arivazhagan, Natarajan

    2016-05-01

    The study aimed at investigating the microstructure and mechanical properties of Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) laser welded high strength low alloy (HSLA) SA516 grade 70 boiler steel. The weld joint for a 4 mm thick plate was successfully produced using minimum laser power of 2 kW by employing a single pass without any weld preheat treatment. The micrographs revealed the presence of martensite phase in the weld fusion zone which could be due to faster cooling rate of the laser weldment. A good correlation was found between the microstructural features of the weld joints and their mechanical properties. The highest hardness was found to be in the fusion zone of cap region due to formation of martensite and also enrichment of carbon. The hardness results also showed a narrow soft zone at the heat affected zone (HAZ) adjacent to the weld interface, which has no effect on the weld tensile strength. The yield strength and ultimate tensile strength of the welded joints were 338 MPa and 549 MPa, respectively, which were higher than the candidate metal. These tensile results suggested that the laser welding process had improved the weld strength even without any weld preheat treatment and also the fractography of the tensile fractured samples showed the ductile mode of failure.

  15. Ion beam analysis of a-C:H films on alloy steel substrate

    International Nuclear Information System (INIS)

    Silva, T.F.; Moro, M.V.; Trindade, G.F.; Added, N.; Tabacniks, M.H.; Santos, R.J.; Santana, P.L.; Bortoleto, J.R.R.

    2013-01-01

    An a-C:H thin film deposited by plasma immersion ion implantation and deposition on alloy steel (16MnCr5) was analyzed using a self-consistent ion beam analysis technique. In the self-consistent analysis, the results of each individual technique are combined in a unique model, increasing confidence and reducing simulation errors. Self-consistent analysis, then, is able to improve the regular ion beam analysis since several analyses commonly used to process ion beam data still rely on handling each spectrum independently. The sample was analyzed by particle-induced x-ray emission (for trace elements), elastic backscattering spectrometry (for carbon), forward recoil spectrometry (for hydrogen) and Rutherford backscattering spectrometry (for film morphology). The self-consistent analysis provided reliable chemical information about the film, despite its “heavy” substrate. As a result, we could determine precisely the H/C ratio, contaminant concentration and some morphological characteristics of the film, such as roughness and discontinuities. - Highlights: • Self-consistent approach of ion beam analysis was used to characterize an a-C:H film. • The self-consistent analysis provided a unequivocal and reliable model of the sample. • Morphological aspects of the film were assessed with the ion beam analysis

  16. Modelling of the Stress Corrosion Cracking Behaviour for Low Alloy Steels in High Temperature Water

    International Nuclear Information System (INIS)

    Tirbonod, B.

    2000-11-01

    The goal of the model is to calculate the crack growth and to determine the parameters of relevance for the stress corrosion cracking of the low alloy steels in high temperature water for reactor safety purposes. The model assumes for the crack growth mechanism an anodic dissolution initiated by the rupture of the oxide film by creep at the crack tip, a repassivation, and, for representing other possible crack growth mechanisms, a cleavage. The model for the dissolution considers all the parameters of relevance for the dissolution and well accepted laws of physics. The creep is calculated by a constitutive law of Chaboche with the finite element method. The dissolution cell is found to be situated in the region of the crack tip with a length up to a few hundred micrometers. Sensitive parameters for the crack growth are the strain to film rupture, the composition of the electrolyte, the exchange current densities, and the cleavage length. The model is in qualitative agreement with measurements. It is discussed with particular attention to the geometry and dimensions of the dissolution cell and to the species transport in the dissolution cell and along the crack. Further work should be devoted to the comparison of the model to experiments. (author)

  17. Green superlubricity of Nitinol 60 alloy against steel in presence of castor oil

    Science.gov (United States)

    Zeng, Qunfeng; Dong, Guangneng; Martin, Jean Michel

    2016-07-01

    In the present work, first, we show that sliding Nitinol 60 alloy against steel under castor oil lubrication exhibits a new case of superlubricity (coefficient of friction CoF ≪ 0.01). So far, CoF below 0.01 have never been achieved under boundary lubrication at high contact pressure and in presence of vegetable oil as a green lubricant. Next, it is demonstrated that superlubricity is controlled by tribochemical reactions, involving chemical degradation of castor oil and the formation of metal oxy-hydroxides. Finally, to explain these findings, we propose a novel superlubricity mechanism consisting of hexanoic acid molecules intercalated between nickel and iron oxy-hydroxide lamellar layers, a structure very similar to the one found in Fe-Ni batteries. We propose that superlubricity is achieved due to repulsive electrostatic forces acting between the intercalated metal oxy-hydroxide lamellar compounds. This system would be suitable for practical engineering applications in many fields including biotechnologies.

  18. Stress Wave Attenuation in Aluminum Alloy and Mild Steel Specimens Under SHPB Tensile Testing

    Science.gov (United States)

    Pothnis, J. R.; Ravikumar, G.; Arya, H.; Yerramalli, Chandra S.; Naik, N. K.

    2018-02-01

    Investigations on the effect of intensity of incident pressure wave applied through the striker bar on the specimen force histories and stress wave attenuation during split Hopkinson pressure bar (SHPB) tensile testing are presented. Details of the tensile SHPB along with Lagrangian x- t diagram of the setup are included. Studies were carried out on aluminum alloy 7075 T651 and IS 2062 mild steel. While testing specimens using the tensile SHPB setup, it was observed that the force calculated from the transmitter bar strain gauge was smaller than the force obtained from the incident bar strain gauge. This mismatch between the forces in the incident bar and the transmitter bar is explained on the basis of stress wave attenuation in the specimens. A methodology to obtain force histories using the strain gauges on the specimen during SHPB tensile testing is also presented. Further, scanning electron microscope images and photomicrographs are given. Correlation between the microstructure and mechanical properties is explained. Further, uncertainty analysis was conducted to ascertain the accuracy of the results.

  19. Ultrasonic attenuation peak in steel and aluminum alloy during rotating bending fatigue

    Energy Technology Data Exchange (ETDEWEB)

    Ogi, Hirotsugu; Hamaguchi, Takayuki; Hirao, Masahiko

    2000-04-01

    Using electromagnetic acoustic resonance (EMAR), the authors studied the evolution of the surface shear wave attenuation and phase velocity in a 0.45 pct C steel and a 5052 aluminum alloy exposed to rotating bending fatigue. In the EMAR method, they used electromagnetic acoustic transducers (EMATs) for the contactless measurements of the axial shear wave, which is a surface shear wave that propagates along a cylindrical surface in the circumferential direction, with an axial polarization. There has been no precious report of continuous and contactless monitoring of the surface wave attenuation and velocity being performed without interrupting the fatigue. The attenuation coefficient always showed sharp peaks around 90 pct of the fatigue life, independent of the fatigue-stress amplitude. To interpret this phenomenon, the authors made crack-growth observations using replicas and measurements of recovery of attenuation and velocity by stopping the cyclic loading before and after the peak. From these results, they concluded that the evolution of the ultrasonic properties is caused by a drastic change in dislocation mobility being accompanied by the crack growth at the final stage of the fatigue life.

  20. Ultrasonic attenuation peak in steel and aluminum alloy during rotating bending fatigue

    Science.gov (United States)

    Ogi, Hirotsugu; Hamaguchi, Takayuki; Hirao, Masahiko

    2000-04-01

    Using electromagnetic acoustic resonance (EMAR), we studied the evolution of the surface shearwave attenuation and phase velocity in a 0.45 pct C steel and a 5052 aluminum alloy exposed to rotating bending fatigue. In the EMAR method, we used electromagnetic acoustic transducers (EMATs) for the contactless measurements of the axial shear wave, which is a surface shear wave that propagates along a cylindrical surface in the circumferential direction, with an axial polarization. There has been no previous report of continuous and contactless monitoring of the surface wave attenuation and velocity being performed without interrupting the fatigue. The attenuation coefficient always showed sharp peaks around 90 pct of the fatigue life, independent of the fatigue-stress amplitude. To interpret this phenomenon, we made crack-growth observations using replicas and measurements of recovery of attenuation and velocity by stopping the cyclic loading before and after the peak. From these results, we concluded that the evolution of the ultrasonic properties is caused by a drastic change in dislocation mobility being accompanied by the crack growth at the final stage of the fatigue life.

  1. Constitutive equations of a ballistic steel alloy as a function of temperature

    Science.gov (United States)

    Berkovic, L.; Chabotier, A.; Coghe, F.; Rabet, L.

    2012-08-01

    In the present work, dynamic tests have been performed on a new ballistic steel alloy by means of split Hopkinson pressure bars (SHPB). The impact behavior was investigated for strain rates ranging from 1000 to 2500 s-1, and temperatures in the range from - 196 to 300∘C. A robotized sample device was developed for transferring the sample from the heating or cooling device to the position between the bars. Simulations of the temperature evolution and its distribution in the specimen were performed using the finite element method. Measurements with thermocouples added inside the sample were carried out in order to validate the FEM simulations. The results show that a thermal gradient is present inside the sample; the average temperature loss during the manipulation of the sample is evaluated. In a last stage, optimal material constants for different constitutive models (Johnson-Cook, Zerilli-Amstrong, Cowper-Symonds) has been computed by fitting, in a least square sense, the numerical and experimental stress-strain curves. They have been implemented in a hydrocode for validation using a simple impact problem: an adapted projectile geometry with a truncated nose (.50 calibre fragment simulating projectiles) was fired directly against an armor plate. The parameters of the selected strength and failure models were determined. There is a good correspondence between the experimental and computed results. Nevertheless, an improved failure model is necessary to get satisfactory computed residual projectile velocities.

  2. Constitutive equations of a ballistic steel alloy as a function of temperature

    Directory of Open Access Journals (Sweden)

    Coghe F.

    2012-08-01

    Full Text Available In the present work, dynamic tests have been performed on a new ballistic steel alloy by means of split Hopkinson pressure bars (SHPB. The impact behavior was investigated for strain rates ranging from 1000 to 2500 s−1, and temperatures in the range from − 196 to 300∘C. A robotized sample device was developed for transferring the sample from the heating or cooling device to the position between the bars. Simulations of the temperature evolution and its distribution in the specimen were performed using the finite element method. Measurements with thermocouples added inside the sample were carried out in order to validate the FEM simulations. The results show that a thermal gradient is present inside the sample; the average temperature loss during the manipulation of the sample is evaluated. In a last stage, optimal material constants for different constitutive models (Johnson-Cook, Zerilli-Amstrong, Cowper-Symonds has been computed by fitting, in a least square sense, the numerical and experimental stress-strain curves. They have been implemented in a hydrocode for validation using a simple impact problem: an adapted projectile geometry with a truncated nose (.50 calibre fragment simulating projectiles was fired directly against an armor plate. The parameters of the selected strength and failure models were determined. There is a good correspondence between the experimental and computed results. Nevertheless, an improved failure model is necessary to get satisfactory computed residual projectile velocities.

  3. A comparative assessment of the fracture toughness behavior of ferritic-martensitic steels and nanostructured ferritic alloys

    Science.gov (United States)

    Byun, Thak Sang; Hoelzer, David T.; Kim, Jeoung Han; Maloy, Stuart A.

    2017-02-01

    The Fe-Cr alloys with ultrafine microstructures are primary candidate materials for advanced nuclear reactor components because of their excellent high temperature strength and high resistance to radiation-induced damage such as embrittlement and swelling. Mainly two types of Fe-Cr alloys have been developed for the high temperature reactor applications: the quenched and tempered ferritic-martensitic (FM) steels hardened primarily by ultrafine laths and carbonitrides and the powder metallurgy-based nanostructured ferritic alloys (NFAs) by nanograin structure and nanoclusters. This study aims at elucidating the differences and similarities in the temperature and strength dependences of fracture toughness in the Fe-Cr alloys to provide a comparative assessment of their high-temperature structural performance. The KJQ versus yield stress plots confirmed that the fracture toughness was inversely proportional to yield strength. It was found, however, that the toughness data for some NFAs were outside the band of the integrated dataset at given strength level, which indicates either a significant improvement or deterioration in mechanical properties due to fundamental changes in deformation and fracture mechanisms. When compared to the behavior of NFAs, the FM steels have shown much less strength dependence and formed narrow fracture toughness data bands at a significantly lower strength region. It appeared that at high temperatures ≥600 °C the NFAs cannot retain the nanostructure advantage of high strength and high toughness either by high-temperature embrittlement or by excessive loss of strength. Irradiation studies have revealed, however, that the NFAs have much stronger radiation resistance than tempered martensitic steels, such as lower radiation-induced swelling, finer helium bubble formation, lower irradiation creep rate and reduced low temperature embrittlement.

  4. Immunological parameters of dental alloy corrosion; A study of gingival inflammation after placement of stainless steel crown

    Directory of Open Access Journals (Sweden)

    Ratna Indriyanti

    2008-11-01

    Full Text Available The dental alloy is widely used in many fields of dentistry as a restoration material, orthodontic, prosthodontic, oral surgery and endodontic treatments. Naturally, most of the metallic materials without exception to stainless steel alloy will experience a process of corrosion in a form of electrochemical reaction to achieve thermodynamic equilibrium. The corrosion process in the oral cavity is due to the reaction of metal with saliva as an oral cavity electrolyte fluid. SSC has preformed restoration material conform with dental anatomy, manufactured from stainless steel alloy which is formable and adaptable to the teeth. Stainless Steel Crown generally made of austenitic stainless steel 18/8 of AISI 304 group contain chrome 18% and Nickel 8%, can be used as a restoration for teeth with excessive caries, crown fracture, email hypoplasia, or restoration after endodontic treatment. The toxic effect of Ni+2 released due to corrosion process may cause an inflammation of the gingiva and periodontal tissue. Laboratorically this condition indicated by the expression of pro-inflammation cytokines as immunological parameters such as IL-6, IL-8, TNF and IL-1β whose main role is to initiate and enhance any inflammation responses. The presence of pro-inflammation cytokines can be detected as soon as 1 hour after placement of SSC by examination of gingival crevicular fluid (GCF by ELISA technique. The magnitude of the toxic effect depends on corrosion rate and ions release which is influenced by metal chemical composition, environment temperature and pH, metal wear due to abrasion and friction, soldering if any, and elongation of the metal. Conclusion: The release of Ni+2 during corrosion process after placement of SSC cause gingival inflammation which is indicated by the change of the immunological parameters.

  5. Comparative study of two materials for dynamic hip screw during fall and gait loading: titanium alloy and stainless steel.

    Science.gov (United States)

    Taheri, Nooshin S; Blicblau, Aaron S; Singh, Manmohan

    2011-11-01

    Internal fixation with dynamic hip screw is a choice of treatment for hip fractures to stabilize a femoral fracture. Choosing the proper implant and its material has a great effect on the healing process and failure prevention. The purpose of this analysis was to assess biomechanical behavior of dynamic hip screw with two different materials implanted in the femur during fall and gait. A 3D finite element model of an intact femur and a 3D implant within the same femur were developed. A finite element analysis was carried out to establish the effect of load conditions and implant material properties on biomechanical behavior of the dynamic hip screw after internal fixation. Two load configurations are chosen: one simulating the stance phase of the normal gait cycle, and the other replicating a low-energy fall. The implanted femur was investigated with two different materials for the dynamic hip screw: stainless steel and titanium alloy. During stance, more stress is placed on the implanted femur compared with the intact femur. During a fall, the implanted femur is in a greater state of stress, which mostly occurs inside the dynamic hip screw. Titanium alloy decreases stress levels by an average of 40% compared with stainless steel. However, deformation is slightly reduced with a stainless steel dynamic hip screw during both load cases. After internal fixation, dynamic hip screw generates greater stresses within the implanted femur compared with the intact femur under the same loading conditions. A titanium alloy implant appears to undergo less stress from a low-energy fall compared with stainless steel and can be considered the preferred implant material. The critical parts of the dynamic hip screw are the forth distal screw and the plate.

  6. Characterization of dissimilar welding: carbon steel E309L-E308L-ERNiCr3-ENiCrFe3 alloy 600

    International Nuclear Information System (INIS)

    Mucino G, O.

    2015-01-01

    Most BWR type reactors have internal support components, which need to be attached to the inner surface by welding. Specifically, in these joints two materials interact, such as stainless steel and nickel base alloys. Nickel base alloys such as alloy 82 (ERNiCr3) and alloy 182 (ENiCrFe-3) are used for the joining of both dissimilar materials. For joints made with both nickel base alloys, the alloy 182 is prone to stress corrosion cracking (SCC); so it is essential to carry out studies related to this contribution material. In the nuclear industry any study related to this alloy is of importance because experience is gained in its behavior when is part of a system of an operation reactor. This work presents the characterization of the weld deposit of a stainless steel coating (with electrodes E309L and E308L) on a carbon steel plate type A36 and the joining with an Inconel 600 plate, simulating the joining of the internal coating of vessel and the heel of the support leg of the envelope of a BWR reactor. In this work, the mechanical and micro-structural characterization of the alloy deposit 182 was performed. (Author)

  7. Dresden 1 Radiation Level Reduction Program. Intergranular corrosion tests of sensitized Type-304 stainless steel in Dow NS-1, and stress corrosion cracking tests of Type-304 stainless steel and carbon and low alloy steels in Dow copper rinse solution

    International Nuclear Information System (INIS)

    Walker, W.L.

    1978-09-01

    Corrosion tests were performed to evaluate the extent of intergranular attack on sensitized Type-304 stainless steel by a proprietary Dow Chemical solvent, NS-1, which is to be used in the chemical cleaning of the Dresden 1 primary system. In addition, tests were performed to evaluate stress corrosion cracking of sensitized Type-304 stainless steel and post-weld heat-treated ASTM A336-F1, A302-B, and A106-B carbon and low alloy steels in a solution to be used to remove residual metallic copper from the Dresden 1 primary system surfaces following the chemical cleaning. No evidence of deleterious corrosion was observed in either set of tests

  8. Co-reduction of Copper Smelting Slag and Nickel Laterite to Prepare Fe-Ni-Cu Alloy for Weathering Steel

    Science.gov (United States)

    Guo, Zhengqi; Pan, Jian; Zhu, Deqing; Zhang, Feng

    2018-02-01

    In this study, a new technique was proposed for the economical and environmentally friendly recovery of valuable metals from copper smelting slag while simultaneously upgrading nickel laterite through a co-reduction followed by wet magnetic separation process. Copper slag with a high FeO content can decrease the liquidus temperature of the SiO2-Al2O3-CaO-MgO system and facilitate formation of liquid phase in a co-reduction process with nickel laterite, which is beneficial for metallic particle growth. As a result, the recovery of Ni, Cu, and Fe was notably increased. A crude Fe-Ni-Cu alloy with 2.5% Ni, 1.1% Cu, and 87.9% Fe was produced, which can replace part of scrap steel, electrolytic copper, and nickel as the burden in the production of weathering steel by an electric arc furnace. The study further found that an appropriate proportion of copper slag and nickel laterite in the mixture is essential to enhance the reduction, acquire appropriate amounts of the liquid phase, and improve the growth of the metallic alloy grains. As a result, the liberation of alloy particles in the grinding process was effectively promoted and the metal recovery was increased significantly in the subsequent magnetic separation process.

  9. Ultrasonic Spot Welding of Aluminum to High-Strength Low-Alloy Steel: Microstructure, Tensile and Fatigue Properties

    Science.gov (United States)

    Patel, V. K.; Bhole, S. D.; Chen, D. L.

    2014-04-01

    The structural applications of lightweight aluminum alloys inevitably involve dissimilar welding with steels and the related durability issues. This study was aimed at evaluating the microstructural change, lap shear tensile load, and fatigue resistance of dissimilar ultrasonic spot-welded joints of aluminum-to-galvanized high-strength low-alloy (HSLA) steel. Two non-uniform layers were identified in between Al and HSLA steel via SEM/EDS and XRD. One was an Al-Zn eutectic layer and the other was a thin (<2 μm) layer of intermetallic compound (IMC) of Al and Fe in the nugget zone. The lap shear tensile testing gave a maximum load of 3.7 kN and the sample failed initially in between the Al-Zn eutectic film and Al-Fe IMC, and afterward from the region containing Al on both matching fracture surfaces. The fatigue test results showed a fatigue limit of about 0.5 kN (at 1 × 107 cycles). The maximum cyclic stress at which transition of the fatigue fracture from transverse through-thickness crack growth mode to the interfacial failure mode occurs increases with increasing energy input.

  10. Dissimilar Joining of Stainless Steel and 5083 Aluminum Alloy Sheets by Gas Tungsten Arc Welding-Brazing Process

    Science.gov (United States)

    Cheepu, Muralimohan; Srinivas, B.; Abhishek, Nalluri; Ramachandraiah, T.; Karna, Sivaji; Venkateswarlu, D.; Alapati, Suresh; Che, Woo Seong

    2018-03-01

    The dissimilar joining using gas tungsten arc welding - brazing of 304 stainless steel to 5083 Al alloy had been conducted with the addition of Al-Cu eutectic filler metal. The interface microstructure formation between filler metal and substrates, and spreading of the filler metal were studied. The interface microstructure between filler metal and aluminum alloy characterized that the formation of pores and elongated grains with the initiation of micro cracks. The spreading of the liquid braze filler on stainless steel side packed the edges and appeared as convex shape, whereas a concave shape has been formed on aluminum side. The major compounds formed at the fusion zone interface were determined by using X-ray diffraction techniques and energy-dispersive X-ray spectroscopy analysis. The micro hardness at the weld interfaces found to be higher than the substrates owing to the presence of Fe2Al5 and CuAl2 intermetallic compounds. The maximum tensile strength of the weld joints was about 95 MPa, and the tensile fracture occurred at heat affected zone on weak material of the aluminum side and/or at stainless steel/weld seam interface along intermetallic layer. The interface formation and its effect on mechanical properties of the welds during gas tungsten arc welding-brazing has been discussed.

  11. Influence of Short Austenitization Treatments on the Mechanical Properties of Low-Alloy Steels for Hot Forming Applications

    Science.gov (United States)

    Holzweissig, Martin Joachim; Lackmann, Jan; Konrad, Stefan; Schaper, Mirko; Niendorf, Thomas

    2015-07-01

    The current work elucidates an improvement of the mechanical properties of tool-quenched low-alloy steel by employing extremely short austenitization durations utilizing a press heating arrangement. Specifically, the influence of different austenitization treatments—involving austenitization durations ranging from three to 15 seconds—on the mechanical properties of low-alloy steel in comparison to an industrial standard furnace process was examined. A thorough set of experiments was conducted to investigate the role of different austenitization durations and temperatures on the resulting mechanical properties such as hardness, bending angle, tensile strength, and strain at fracture. The most important finding is that the hardness, the bending angle as well as the tensile strength increase with shortened austenitization durations. Furthermore, the ductility of the steels exhibits almost no difference following the short austenitization durations and the standard furnace process. The enhancement of the mechanical properties imposed by the short heat treatments investigated, is related to a refinement of microstructural features as compared to the standard furnace process.

  12. A Method to Determine Lankford Coefficients (R-Values) for Ultra High Strength Low Alloy (Uhsla) Steels

    Science.gov (United States)

    Gösling, M.

    2017-09-01

    For Ultra High Strength Low Alloy Steels (UHSLAS) it is difficult to determine Lankford parameters, since the measurement of a stable strain ratio is often not possible. This report presents a method for determining Lankford coefficients for UHSLA Steels. The method is based on a combination of a theoretical material model and on experiences from a material data base. The Hill’48 yield condition is used to calculate the Lankford coefficients as a function of the yield stress. An empirical model based on the BILSTEIN material data base is used to predict the anisotropy. The result from earing test is used as an input parameter for the empirical model. The method is first checked using data from tensile tests. The predicted Lankford coefficients are compared with measured Lankford coefficients. In a further step, this method is applied to low alloyed steels with a yield stress of more than 900 MPa. For these materials the Lankford coefficients could not be measured by tensile tests. Predicted Lankford coefficients are used in the numerical simulation of earing test and compared with experimental results. In summary, it can be stated that the method presented here is suitable for predicting Lankford coefficients in case of an impossible direct measurement.

  13. Effect of Microstructure on Retained Austenite Stability and Tensile Behaviour in an Aluminum-Alloyed TRIP Steel

    Science.gov (United States)

    Chiang, Jasmine Sheree

    Transformation-induced plasticity (TRIP) steels have excellent strength, ductility and work hardening behaviour, which can be attributed to a phenomenon known as the TRIP effect. The TRIP effect involves a metastable phase, retained austenite (RA), transforming into martensite as a result of applied stress or strain. This transformation absorbs energy and improves the work hardening rate of the steel, delaying the onset of necking. This work describes two distinct TRIP steel microstructures and focuses on how microstructure affects the RA-to-martensite transformation and the uniaxial tensile behaviour. A two-step heat treatment was applied to an aluminum-alloyed TRIP steel to obtain a microstructure consisting of equiaxed grains of ferrite surrounded by bainite, martensite and RA -- the equiaxed microstructure. The second microstructure was produced by first austenitizing and quenching the steel to produce martensite, followed by the two-step heat treatment. The resulting microstructure (labelled the lamellar microstructure) consisted of elongated grains of ferrite with bainite, martensite and RA grains. Both microstructural variants had similar initial volume fractions of RA. A series of interrupted tensile tests and ex-situ magnetic measurements were conducted to examine the RA transformation during uniform elongation. Similar tests were also conducted on an equiaxed microstructure and a lamellar microstructure with similar ultimate tensile strengths. Results show that the work hardening rate is directly related to the RA transformation rate. The slower transformation rate, or higher RA stability, that was observed in the lamellar microstructure enables sustained work hardening at high strains. In contrast, the equiaxed microstructure has a lower RA stability and thus exhibits high values of work hardening at low strains, but the effect is quickly exhausted. Several microstructural factors that affect RA stability were examined, including RA grain size, aspect

  14. Corrosion Characteristics of Ni-Based Hardfacing Alloy Deposited on Stainless Steel Substrate by Laser Cladding

    Science.gov (United States)

    Awasthi, Reena; Abraham, Geogy; Kumar, Santosh; Bhattacharyya, Kaustava; Keskar, Nachiket; Kushwaha, R. P.; Rao, Ramana; Tewari, R.; Srivastava, D.; Dey, G. K.

    2017-06-01

    In this study, corrosion characteristics of a nickel-based Ni-Mo-Cr-Si hardfacing alloy having 32Mo, 15Cr, and 3Si (wt pct) as alloying elements, deposited on stainless steel SS316L substrate by laser cladding, have been presented. Corrosion behavior of the laser clad layer was evaluated in reducing (0.1 M HCl) and oxidizing (0.5 M HNO3) environments, in comparison with the reference substrate SS316L, using electrochemical potentiodynamic technique at room temperature. The corrosion mechanisms have been evaluated on the basis of microstructural and microchemical analysis using scanning electron microscopy attached with energy-dispersive spectrometry. Passivity behavior of the laser clad layer was studied in 0.5 M H2SO4, using the potentiostatic technique and analyzing the passive layer by X-ray photoelectron spectroscopy. Laser clad layer of Ni-Mo-Cr-Si exhibited higher pitting corrosion resistance in chloride (reducing) environment, indicated by much higher breakdown potential ( 0.8 VSCE) and the absence of pitting as compared to substrate SS316L ( 0.3 VSCE). However, in oxidizing (0.5 M HNO3) environment, both the laser clad layer and substrate SS316L showed excellent and similar corrosion resistance exhibiting high breakdown potential ( 0.85 VSCE) and wide passivation range ( 0.8 VSCE) with low passive current density ( 4 to 7 × 10-6 A/cm2). The stable passive layer formed on laser clad layer of Ni-Mo-Cr-Si after exposure in 0.5 M H2SO4 solution at constant potential 0.6 VSCE (within the passive range), consisted oxides of Mo as Mo+4 (MoO2) and Mo+6 (MoO4)-2, Cr as Cr3+ (mixture of both Cr2O3 and Cr (OH)3), and Si as Si4+(SiO2), which have contributed to passivation and repassivation and therefore excellent corrosion behavior.

  15. Dependency of single-phase FAC of carbon and low-alloy steels for NPP system piping on pH, orifice distance and material

    International Nuclear Information System (INIS)

    Moon, Jeong Ho; Chung, Hung Ho; Sung, Ki Woung; Kim, Uh Chul; Rho, Jae Seong

    2005-01-01

    To investigate the Flow-Accelerated Corrosion (FAC) dependency of carbon steel (A106 Gr. B) and low-alloy steels (1Cr-1/2Mo, 2 1/4Cr-1Mo) on pH, orifice distance, and material, experiments were carried out. These experiments were performed using a flow velocity of 4 m/sec (partly 9 m/sec) at pH 8.0∼10.0 in an oxygen-free aqueous solution re-circulated in an Erosion-Corrosion Test Loop at 130 .deg. ... for 500 hours. The weight loss of the carbon steel specimens appeared to be positively dependent on the flow velocity. That of the carbon and low-alloy steel specimens also showed to be distinguishably dependent on the pH. At pH levels of 8.0∼9.5 it decreased, but increased from 9.5 to 10.0. Utility water chemistry personnel should carefully consider this kind of pH dependency to control the water system pH to mitigate FAC of the piping system material. The weight loss of the specimens located further from the orifice in the distance range of 6.8∼27.2 mm was shown to be greater, except for 2 1/4Cr-1Mo, which showed no orifice distance dependency. Low alloy steel specimens exhibited a factor of two times better resistance to FAC than that of the carbon steel. Based on this kind of FAC dependency of the carbon and low-alloy steels on the orifice distance and material, we conclude that it is necessary to alternate the composition of the secondary piping system material of NPPs, using low-alloy steels, such as 2 1/4Cr-1Mo, particularly when the system piping has to be replaced

  16. 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.

  17. Fine structures in Fe3Al alloy layer of a new hot dip aluminized steel

    Indian Academy of Sciences (India)

    Unknown

    structure and performance in the coating can be improved and service life of the aluminized steel can significantly be enhanced. 2. Experimental. The base metal of the aluminized steel used in this inves- tigation was mild steel (0⋅18%C), which was aluminized by the hot dip aluminizing technology (HDA). In order to.

  18. 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)

  19. A novel approach for an automated liquid/liquid extraction system--principle and application for the determination of several trace contaminants in highly alloyed steels and base alloys.

    Science.gov (United States)

    Wiltsche, Helmar; Prattes, Karl; Knapp, Günter

    2011-06-01

    A novel automated liquid/liquid extraction system was developed for the determination of trace contaminants in unalloyed, alloyed and highly alloyed steels and super alloys. In the presented batch extraction system the aqueous phase and the non-water miscible organic phase were brought into close phase contact by high-speed stirring with a magnetic stir bar. Iodide complexes of Ag, Bi, Cd, Pb, Sb, Sn, Tl, and Zn were extracted from aqueous steel digests into 4-methylpentan-2-one (MIBK) containing 20 g L(-1) trioctylphosphine oxide. Ag, Bi, Cd, Pb, and Tl were extracted quantitatively whereas the extraction yields of Sb, Sn, and Zn were 83%, 61% and 75% respectively. Using high resolution continuum source flame AAS (HR-CS-FAAS) for analyte quantification the method was validated using 21 certified steel reference materials (CRMs).

  20. Assessment of The Cracking Properties of Stainless Steel Alloys and their Usability for Laser Welding in Production

    DEFF Research Database (Denmark)

    Juhl, Thomas Winther

    2001-01-01

    Methods to assess stainless steel alloys’ cracking properties and usability for laser welding has been studied. Also tests to assess alloys’ susceptibility to hot cracking has been conducted. Among these is the so-called Weeter test which assesses the alloy by executing a number of spot welds...... to provoke cracking in the alloy. In this work the Weeter test has been modified and changed in order to develop a faster and easier test also applicable to small specimens. The new test, called a Groove test differs from the Weeter test by its procedure in which linear seam welds are conducted instead...... of spot welds. The Groove test has the advantage of an easier microscopy and analysis in the welds. Results from crack tests was partly confirmed by predictions made on the basis of the alloy’s constituents and solidification growth rate....

  1. Evaluation of mechanically alloyed Cu-based powders as filler alloy for brazing tungsten to a reduced activation ferritic-martensitic steel

    Science.gov (United States)

    de Prado, J.; Sánchez, M.; Ureña, A.

    2017-07-01

    80Cu-20Ti powders were evaluated for their use as filler alloy for high temperature brazing of tungsten to a reduced activation ferritic/martensitic steel (Eurofer), and its application for the first wall of the DEMO fusion reactor. The use of alloyed powders has not been widely considered for brazing purposes and could improve the operational brazeability of the studied system due to its narrower melting range, determined by DTA analysis, which enhances the spreading capabilities of the filler. Ti contained in the filler composition acts as an activator element, reacting and forming several interfacial layers at the Eurofer-braze, which enhances the wettability properties and chemical interaction at the brazing interface. Brazing thermal cycle also activated the diffusion phenomena, which mainly affected to the Eurofer alloying elements causing in it a softening band of approximately 400 μm of thickness. However, this softening effect did not degrade the shear strength of the brazed joints (94 ± 23 MPa), because failure during testing was always located at the tungsten-braze interface.

  2. Corrosion of Cr bearing low alloy pipeline steel in CO2 environment at static and flowing conditions

    Science.gov (United States)

    Xu, Lining; Guo, Shaoqiang; Chang, Wei; Chen, Taihui; Hu, Lihua; Lu, Minxu

    2013-04-01

    We study the corrosion performance of Cr bearing low alloy pipeline steel (Cr3MoNi) in CO2 saturated formation water, under both static and flowing conditions. Cross-sectional morphologies of corrosion scales at progressively increased test duration are observed by scanning electron microscopy. The characteristic of the corrosion scales are investigated by energy dispersive X-ray spectroscopy and X-ray diffraction. Our results show that the corrosion rate of Cr3MoNi steel at flowing condition is higher than that of static condition, and the degree of Cr enrichment in the scales at flowing condition is also higher. Flow also makes ions distribute evenly in the solution close to the specimen, leading to a uniform distribution of Cr compound in the amorphous corrosion scales. In this way, flow suppresses the presence of the potential pits and also leads to a more flat scale/substrate interface.

  3. A study and development of technology for surface induction hardening of railroad rails from low-alloy steel

    Science.gov (United States)

    Degtyarev, S. I.; Skoblo, T. S.; Sapozhnikov, V. E.

    1998-12-01

    A technology of heat treatment of railroad rails using induction heating has been developed and installed in the Azovstal' metallurgical works. It provides the requisite combination of properties in the metal of rail heads. However, the metal of the web and the bottom of the rails remains in the initial (unhardened) state. Under severe operational conditions (small-radius curves, high axial loads, and composite configuration of the road) the wear resistance of the head and the structural strength of the web and the bottom not hardened in the plant have to be increased. The properties of the rail steel can be improved by alloying it using the most effective and available elements. Currently, in Ukraine this is manganese. The present paper is devoted to the effect of manganese additives on the phase transformations in induction hardening and the specific features of the formed structure and properties of the rail steel. Optimum parameters for heat treatment of rails are recommended.

  4. Structural state and geometric representation of a laser-welded joint between corrosion-resistant steel and titanium alloy with copper insert

    Science.gov (United States)

    Michurov, N. S.; Veretennikova, I. A.; Pugacheva, N. B.; Smirnova, E. O.

    2017-12-01

    The paper shows a characteristic structure of a welded joint between titanium alloy and corrosion-resistant steel, with a copper insert, produced by carbon dioxide laser welding. In the formation of the joint, the materials being welded are dissolved and mixed in the copper interlayer. The material of the welded joint is an oversaturated solid solution of Fe, Ni, Cr and Ti in the copper lattice with distributed TiFe, Ti(Fe, Cr)2 and CuTi2 intermetallic particles. A 10-150 µm thick diffusion zone with an altered chemical composition appears at the boundary with the steel, and a 50- 100 µm thick zone of the kind is formed at the boundary with the titanium alloy. The phase composition is determined and recrystallization maps at the boundaries of the welded joint are obtained. A geometric representation of a laser welded joint between titanium alloy and corrosion-resistant steel with a copper insert is constructed.

  5. New corrosion resistant alloys on the base of titanium and high-chromium steels

    International Nuclear Information System (INIS)

    Tomashov, N.D.; Chernova, G.P.

    1975-01-01

    It is shown that stability of titanium alloys, with α-structure (OT-4, AT3,AT6) and high-strength α+β or pure β-structure (BT-14; BT-15), in hydrochloric acid solutions may be significantly improved due to additional alloying by minor additions of Pd(0,2%) similar to pure titanium. Additions of 0,2% Pd also significantly improve acid resistance of alloys of the Fe-Cr system. The highest corrosion resistance has Fe,40%Cr,0,2%Pd alloy. This alloy is stable in 20-40%H 2 SO 4 and 1% HCl at 100 deg C

  6. Corrosion of stainless steels and nickel-base alloys in solutions of nitric acid and hydrofluoric acid

    International Nuclear Information System (INIS)

    Horn, E.M.; Renner, M.

    1992-01-01

    Reactions involving nitric acid may always result in the contamination of this acid with fluorides. In highly concentrted nitric acid, the presence of small amounts of HF will substantially reduce the corrosion of metallic materials. Mixtures consisting of hydrofluoric acid and hypo-azeotropic nitric acid on the other hand will strongly attack: the metal loss will markedly increase with increasing HNO 3 and HF concentrations as well as with rising temperatures. The investigation covered 12 stainless steel grades and nickel-base alloys. With constant HNO 3 content, corrosion rates will rise linearly when increasing the HF concentration. With constant HF concentration (0,25 M), corrosion rates will increase rapidly with increasing nitric acid concentration (from 0.3 M to 14.8 M). This can best be described by superimposing a linear function and a hyperbolic function that is reflecting the change in the HNO 3 content. Alloys containing as much chromium as possible (up to 46 wt.%) will exhibit the best corrosion resistance. Alloy NiCr30FeMo (Hastelloy alloy G-30) proved to be well suitable in this investigation. (orig.) [de

  7. Effect of Laser Beam Alloying Strategies on the Metallurgical and Mechanical Properties of Hot Forming Tool Steels

    Science.gov (United States)

    Hofmann, Konstantin; Neubauer, Franziska; Holzer, Matthias; Mann, Vincent; Hugger, Florian; Roth, Stephan; Schmidt, Michael

    In terms of increasing lightweight designs of car body parts, the machining of high strength steels in hot stamping processes becomes of particular interest. Due to high process forces at hot stamping, the surface of such tools in the area of maximal stress is subject wear, which necessitate some local increase of microhardness to enhance the mechanical performance. Especially laser beam alloying using filler wire and beam oscillation is some suitable method to modify the mechanical properties of tool surfaces to emcompass some continuous martensitic structure, featuring a certain microhardness. Nevertheless the thermal energy input during laser beam alloying induces tempering in the heat affected zone and reduces the hardness. This paper discusses the influence of alloying strategies on the thermal energy input and the resulting metallurgical structure of modified tool surfaces. Also the cooling behavior of alloyed lines for different energy inputs per unit length is of interest. Therefore, the metallurgical microstructure is analyzed regarding microhardness as well as formation of carbides. Furthermore, a numerical thermal simulation is developed to investigate the temperature profile in the heat affected zone of the specimen. These investigations permit the control of the spatiotemporal energy input to avoid tempering of the microstructure.

  8. Dynamic behaviour of TM380 mild steel and Ti6Al4V alloy subjected to blast loading

    CSIR Research Space (South Africa)

    Shoke, Lerato

    2016-10-01

    Full Text Available and Base Metals Development Network Conference 2016, 19-20 October 2016, KwaZulu Natal, Maharani Hotel Dynamic behaviour of TM380 mild steel and Ti6Al4V alloy subjected to blast loading L. Shoke,1* K. Mutombo2, I.M. Snyman1 and T. Sono1 1... Landwards Sciences, Defence Peace Safety and Security (DPSS), 2 Material Sciences and Manufacturing (MSM), Council for Scientific and Industrial Research (CSIR), Pretoria, South Africa Lshoke@csir.co.za Abstract This paper deals...

  9. Effect of Temperature on the Galvanic Corrosion of Cu-Ni Alloy/High Strength Steel in Seawater

    Directory of Open Access Journals (Sweden)

    Wang Chun Li

    2016-01-01

    Full Text Available The galvanic corrosion behavior of Cu-Ni Alloy(B10/high strength steel (921A has been studied using a zero-resistance ammeter (ZRA in seawater at different temperatures. As well as it was systemically investigated by weight loss measurements, electrochemical methods and scanning electron microscope.Results showed 921A acts as the anode and B10 act as the cathodes. The effect of temperature on the galvanic corrosion is important, the corrosion rate became higher with the temperature increased.

  10. Sulfide Stress Corrosion Cracking Resistance of Modified ASTM A694 F60 Low Alloy Steel for Subsea Applications

    OpenAIRE

    Stridsklev, Camilla A

    2013-01-01

    The resistance to sulfide stress corrosion cracking (SSC) of modified ASTM A694 F60 low alloy steel, produced by two different manufacturers, was studied by four-point bend-testing. The two materials are named material A and material B in this report. Both materials were tested in two different environments with different severity, one ?sweet-transition region? test and one ?sour service? test. The test conditions were controlled by the H2S partial pressure (pH2S) and pH. These parameters wer...

  11. Reduction of Residual Stress for High-Strength Low-Alloy Steel Strip Based on Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Zengshuai Qiu

    2018-01-01

    Full Text Available Intensive cooling technology is widely utilized in the production of high-strength hot-rolled steel strip. However, intensive cooling at high cooling rate may cause stress heterogeneity on a steel strip, which further generates great residual stress and influences steel strip shape. In this study, a three-dimensional finite element (FE model of high-strength low-alloy steel strip on the run-out table coupled with heat transfer, phase transformation, and strain/stress is developed by ABAQUS software. To enhance modeling precision, several experiments are conducted, such as uniaxial tensile test at multiple temperatures, dynamic continuous cooling transformation, and scanning electron microscopy, to determine the material properties and boundary conditions of the FE model. Four new models are established based on this model to reduce the residual stress of strip by modifying the initial and boundary conditions. Results show that reducing the initial transverse temperature difference is the most effective in reducing residual stress, followed by sparse cooling, edge masking, and posterior cooling.

  12. Study on Static Recrystallization Behavior of Medium-Carbon Cr-Ni-Mo Alloyed Steel During Hot Deformation

    Science.gov (United States)

    Xia, Yingnan; Zhang, Chi; Zhang, Liwen; Shen, Wenfei; Xu, Qianhong

    2017-12-01

    A series of two-pass hot compression tests were conducted on Gleeble-1500 thermo-mechanical simulator to investigate the static recrystallization (SRX) behavior of a medium-carbon Cr-Ni-Mo alloyed steel 34CrNiMo. The compression tests were performed at a deformation temperature range of 950-1150 °C, a strain rate range of 0.1-3.5 s-1, and an interval time range of 1-100 s. The experimental flow stress curves and microstructural observation indicate that deformation temperature, pass interval time, strain rate, and pre-strain have significant influences on the recrystallization behavior of 34CrNiMo steel. It is identified that the softening fraction increases with the increasing deformation temperature, pre-strain, and interval time, while it decreases with the increasing strain rate. Based on the experimental data, the SRX kinetics equations of 34CrNiMo steel were developed. And the calculated results are in good agreement with the experimental ones, which demonstrates that the established equations can be used to describe the SRX behavior of 34CrNiMo steel at elevated temperatures.

  13. Shape effect of ultrafine-grained structure on static fracture toughness in low-alloy steel

    Science.gov (United States)

    Inoue, Tadanobu; Kimura, Yuuji; Ochiai, Shojiro

    2012-01-01

    A 0.4C-2Si-1Cr-1Mo steel with an ultrafine elongated grain (UFEG) structure and an ultrafine equiaxed grain (UFG) structure was fabricated by multipass caliber rolling at 773 K and subsequent annealing at 973 K. A static three-point bending test was conducted at ambient temperature and at 77 K. The strength–toughness balance of the developed steels was markedly better than that of conventionally quenched and tempered steel with a martensitic structure. In particular, the static fracture toughness of the UFEG steel, having a yield strength of 1.86 GPa at ambient temperature, was improved by more than 40 times compared with conventional steel having a yield strength of 1.51 GPa. Furthermore, even at 77 K, the fracture toughness of the UFEG steel was about eight times higher than that of the conventional and UFG steels, despite the high strength of the UFEG steel (2.26 GPa). The UFG steel exhibited brittle fracture behavior at 77 K, as did the conventional steel, and no dimple structure was observed on the fracture surface. Therefore, it is difficult to improve the low-temperature toughness of the UFG steel by grain refinement only. The shape of crystal grains plays an important role in delamination toughening, as do their refinement and orientation. PMID:27877493

  14. In-situ synchrotron diffraction and digital image correlation technique for characterizations of retained austenite stability in low-alloyed transformation induced plasticity steel

    International Nuclear Information System (INIS)

    Brauser, S.; Kromm, A.; Kannengiesser, Th.; Rethmeier, M.

    2010-01-01

    Direct measurement and quantification of phase transformation in a low-alloyed transformation induced plasticity steels depending on the tensile load as well as determination of the real true stress and true strain values were carried out in-situ using high energy synchrotron radiation. Digital image correlation technique was used to quantify more precisely the true strain values. The aim of the work was to obtain a better understanding of the phase transformation of commercial low-alloyed transformation induced plasticity steel depending on the true strain and true stress values.

  15. Light-weight steels based on iron-aluminium - influence of micro alloying elements (B, Ti, Nb) on microstructures, textures and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Bruex, U.; Frommeyer, G. [Dept. of Materials Technology, Max-Planck-Inst. fuer Eisenforschung GmbH, Duesseldorf (Germany); Jimenez, J. [Centro Nacional de Investigaciones Metalurgicas (C.S.I.C.), Madrid (Spain)

    2002-12-01

    The influence of the micro alloying elements B, Ti and Nb on the recrystallization texture and mechanical properties of iron aluminium light-weight steels, particularly with reference to their improved deep drawing properties was investigated. Depending on the combination of the alloying elements the microstructures of the investigated micro alloyed Fe-6Al steels are influenced by grain refinement. Likewise, variable combinations of micro alloying elements differently affect the texture. Generally, the mechanical properties are improved. However, small amounts of B, Ti and Nb cause superior deep drawing and stretch forming properties of these iron aluminium light-weight steels. The microstructures of various micro alloyed cold rolled Fe-6Al steel sheets were evaluated by optical microscopy, scanning electron microscopy (SEM) inclusively EDAX and X-ray diffraction. Texture measurements were performed using a goniometer with a closed Eulerian cradle and analysed by ODF calculations. Tensile tests were carried out at room temperature and 200 C, respectively. The deep drawing behaviour was determined by performing cupping tests and digitalised strain analysis. (orig.)

  16. Standard test methods for pitting and crevice corrosion resistance of stainless steels and related alloys by use of ferric Chloride solution

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2003-01-01

    1.1 These test methods cover procedures for the determination of the resistance of stainless steels and related alloys to pitting and crevice corrosion (see Terminology G 15) when exposed to oxidizing chloride environments. Six procedures are described and identified as Methods A, B, C, D, E, and F. 1.1.1 Method A—Ferric chloride pitting test. 1.1.2 Method B—Ferric chloride crevice test. 1.1.3 Method C—Critical pitting temperature test for nickel-base and chromium-bearing alloys. 1.1.4 Method D—Critical crevice temperature test for nickel-base and chromium-bearing alloys. 1.1.5 Method E—Critical pitting temperature test for stainless steels. 1.1.6 Method F—Critical crevice temperature test for stainless steels. 1.2 Method A is designed to determine the relative pitting resistance of stainless steels and nickel-base, chromium-bearing alloys, whereas Method B can be used for determining both the pitting and crevice corrosion resistance of these alloys. Methods C, D, E and F allow for a rankin...

  17. Optimal Recycling of Steel Scrap and Alloying Elements: Input-Output based Linear Programming Method with Its Application to End-of-Life Vehicles in Japan.

    Science.gov (United States)

    Ohno, Hajime; Matsubae, Kazuyo; Nakajima, Kenichi; Kondo, Yasushi; Nakamura, Shinichiro; Fukushima, Yasuhiro; Nagasaka, Tetsuya

    2017-11-21

    Importance of end-of-life vehicles (ELVs) as an urban mine is expected to grow, as more people in developing countries are experiencing increased standards of living, while the automobiles are increasingly made using high-quality materials to meet stricter environmental and safety requirements. While most materials in ELVs, particularly steel, have been recycled at high rates, quality issues have not been adequately addressed due to the complex use of automobile materials, leading to considerable losses of valuable alloying elements. This study highlights the maximal potential of quality-oriented recycling of ELV steel, by exploring the utilization methods of scrap, sorted by parts, to produce electric-arc-furnace-based crude alloy steel with minimal losses of alloying elements. Using linear programming on the case of Japanese economy in 2005, we found that adoption of parts-based scrap sorting could result in the recovery of around 94-98% of the alloying elements occurring in parts scrap (manganese, chromium, nickel, and molybdenum), which may replace 10% of the virgin sources in electric arc furnace-based crude alloy steel production.

  18. Comparison on Mechanical Properties of SA508 Gr.3 Cl.1, Cl.2, and Gr.4N Low Alloy Steels for Pressure Vessels

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min-Chul; Park, Sang-Gyu; Lee, Bong-Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Ki-Hyoung [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2014-10-15

    In this study, microstructure and mechanical properties of SA508 Gr.3 Cl. 1, Cl.2, and Gr.4N low alloy steels are characterized to compare their properties. To evaluate the fracture toughness in the transition region, the master curve method according to ASTM E1921 was adopted in the cleavage transition region. Tensile tests and Charpy impact tests were also performed to evaluate the mechanical properties, and a microstructural investigation was carried out. The microstructure and mechanical properties of SA508 Gr.3 Cl.1, Cl2 and Gr.4N low alloy steels were characterized.. The predominant microstructure of SA508 Gr.4N model alloy is tempered martensite, while SA508 Gr.3 Cl.1 and Cl.2 steels show a typical tempered upper bainitic structure. SA508 Gr. 4N model alloy shows the best strength and transition behavior among the three SA508 steels. SA508 Gr.3 Cl.2 steel also has quite good strength, but there is a loss of toughness.

  19. Tendency of the 18-8 type corrosion-resistant steel to cracking in automatic building-up of copper and copper base alloys in argon

    International Nuclear Information System (INIS)

    Abramovich, V.R.; Andronik, V.A.

    1978-01-01

    Studied was the tendency of the 18-8 type corrosion-resistant steel to cracking during automatic building-up of copper and bronze in argon. The investigation was carried out on the 0kh18n10t steel in argon. It had been established, that the degree of copper penetration into the steel inceases with the increase in the time of the 0Kh18n10t steel contact with liquid copper. Liquid copper and copper base alloys have a detrimental effect on mechanical properties of the steel under external tensile load during intercontant. It is shown that in building-up of copper base alloys on the steel-0Kh18n10t, tendency of the steel to cracking decreases with increase in stiffness of a surfaced weld metal plate and with decrease in building-up energy per unit length. The causes of macrocracking in steel at building-up non-ferrous metals are explained. The technological procedures to avoid cracking are suggested

  20. DEVELOPMENT OF THE COMPLEX-ALLOYED STEEL OF INCREASED HARDENABILITY, VISCOSITY AND HEAT-RESISTANCE FOR CUTTING PARTS OF HIGH-SPEED INSTRUMENT, OPERATING IN CONDITIONS OF HEATING UP AND DYNAMIC LOADS

    Directory of Open Access Journals (Sweden)

    V. N. Fedulov

    2006-01-01

    Full Text Available The theoretical aspects of development of the complex-alloyed steel compounds for cutting parts of high-speed instrument, particularly influence of alloying elements on its structure and characteristics are considered. It is shown that combined alloying of steel by carbon, chrome, silicon, manganese, vanadium and molybdenum in a certain proportion allows to reach the intended aim, achieving at the same time increase of solidity, impact elasticity and heat stability.

  1. Photo-Electrochemical Effect of Zinc Addition on the Electrochemical Corrosion Potentials of Stainless Steels and Nickel Alloys in High Temperature Water

    International Nuclear Information System (INIS)

    Lee, Yi-Ching; Fong, Clinton; Fang-Chu, Charles; Chang, Ching

    2012-09-01

    Hydrogen water chemistry (HWC) is one of the main mitigating methods for stress corrosion cracking problem of reactor core stainless steel and nickel based alloy components. Zinc is added to minimize the radiation increase associated with HWC. However, the subsequently formed zinc-containing surface oxides may exhibit p-type semiconducting characteristics. Upon the irradiation of Cherenkov and Gamma ray in the reactor core, the ECP of stainless steels and nickel based alloys may shift in the anodic direction, possibly offsetting the beneficial effect of HWC. This study will evaluate the photo-electrochemical effect of Zinc Water Chemistry on SS304 stainless steel and Alloy 182 nickel based weld metal under simulated irradiated BWR water environments with UV illumination. The experimental results reveal that Alloy 182 nickel-based alloy generally possesses n-type semiconductor characteristics in both oxidizing NWC and reducing HWC conditions with zinc addition. Upon UV irradiation, the ECP of Alloy 182 will shift in the cathodic direction. In most conditions, SS304 will also exhibit n-type semiconducting properties. Only under hydrogen water chemistry, a weak p-type property may emerge. Only a slight upward shift in the anodic direction is detected when SS304 is illuminated with UV light. The potential influence of p-type semiconductor of zinc containing surface oxides is weak and the mitigation effect of HWC on the stress corrosion cracking is not adversely affected. (authors)

  2. Dissolution and oxidation behaviour of various austenitic steels and Ni rich alloys in lead-bismuth eutectic at 520 °C

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Marion, E-mail: marion.roy@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d’Etude de la Corrosion Non Aqueuse, F-91191 Gif-sur-Yvette (France); Martinelli, Laure, E-mail: laure.martinelli@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d’Etude de la Corrosion Non Aqueuse, F-91191 Gif-sur-Yvette (France); Ginestar, Kevin, E-mail: kevin.ginestar@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d’Etude de la Corrosion Non Aqueuse, F-91191 Gif-sur-Yvette (France); Favergeon, Jérôme, E-mail: jerome.favergeon@utc.fr [Laboratoire Roberval, UMR 7337, Université de Technologie de Compiègne, Centre de Recherche de Royallieu, CS 60319, 60203 Compiègne Cedex (France); Moulin, Gérard [Laboratoire Roberval, UMR 7337, Université de Technologie de Compiègne, Centre de Recherche de Royallieu, CS 60319, 60203 Compiègne Cedex (France)

    2016-01-15

    Ten austenitic steels and Ni rich alloys were tested in static lead-bismuth eutectic (LBE) at 520 °C in order to obtain a selection of austenitic steels having promising corrosion behaviour in LBE. A test of 1850 h was carried out with a dissolved oxygen concentration between 10{sup −9} and 5 10{sup −4} g kg{sup −1}. The combination of thermodynamic of the studied system and literature results leads to the determination of an expression of the dissolved oxygen content in LBE as a function of temperature: RT(K)ln[O](wt%) = −57584/T(K) −55.876T(K) + 254546 (R is the gas constant in J mol{sup −1} K{sup −1}). This relation can be considered as a threshold of oxygen content above which only oxidation is observed on the AISI 316L and AISI 304L austenitic alloys in static LBE between 400 °C and 600 °C. The oxygen content during the test leads to both dissolution and oxidation of the samples during the first 190 h and leads to pure oxidation for the rest of the test. Results of mixed oxidation and dissolution test showed that only four types of corrosion behaviour were observed: usual austenitic steels and Ni rich alloys behaviour including the reference alloy 17Cr-12Ni-2.5Mo (AISI 316LN), the 20Cr-31Ni alloy one, the Si containing alloy one and the Al containing alloy one. According to the proposed criteria of oxidation and dissolution kinetics, silicon rich alloys and aluminum rich alloy presented a promising corrosion behaviour. - Highlights: • 10 austenitic steels and Ni rich alloys were tested in LBE at 520 °C with dissolved oxygen content between 10{sup -9} and 5 10{sup -4} wt%. • It is shown that only thermodynamics cannot explain the Ni rich alloys corrosion behaviour in LBE. • The role of oxygen on corrosion behaviour in LBE was highlighted. • An equilibrium line was defined above which only oxidation has occurred on 316L: RTln[O](wt%) = -57584/T(K)-55.876T(K)+254546. • 18Cr-15Ni-3.7Si, 21Cr-11Ni-1.6Si and 14Cr-25Ni-3.5Al

  3. Effects of alloying elements and constituent phases on long-term creep strength of modified 9Cr-1Mo steel

    Energy Technology Data Exchange (ETDEWEB)

    Tokunaga, Tatsuya; Masuyama, Fujimitsu [Kyushu Institute of Technology, Kitakyushu (Japan). Dept. of Applied Science for Integrated System Engineering; Consortium of JRCM (The Japan Research and Development Center for Metals) ' Fundamental Studies on Technologies for Steel Materials with Enhanced Strength and Function' (Japan); Yoshida, Kohei [Mitsui High-tec Inc. (Japan); Sakanaba, Masaki [Mitsubishi Heavy Industries Ltd. (Japan)

    2010-07-01

    The effect of the alloying elements and constituent phases on the long-term creep strength of modified 9Cr-1Mo steel has been investigated using creep data from 34 heats of this steel. The creep rupture strength for 10{sup 5} h at 600 C was evaluated using the Larson-Miller parametric method, and the constituent phases and their composition at 600 C were obtained from thermodynamic equilibrium calculations. From various alloying elements, the long-term creep rupture strength was found to depend on the Cr, Mo, V, and N content. Regarding the effect of the constituent phases, the long-term creep rupture strength increased with increasing amount of NaCl-type carbonitride, MX (NbX + VX), and in particular, materials with higher VX/NbX ratios tended to exhibit higher creep strength. Furthermore, the enrichment of Mo in the M{sub 23}C{sub 6} carbide rather than in the bcc matrix may be effective in maintaining a higher creep strength. (orig.)

  4. Chloride effects on the electrochemical degradation of micro-alloyed steel in E20 simulated fuel ethanol blend

    Science.gov (United States)

    Joseph, Olufunmilayo O.

    Biofuels play a major role as a renewable energy source in mitigating global warming. The presence of impurities in fuel ethanol has resulted into certain downsides regarding material compatibility. This work is focused on an investigation of the influence of sodium chloride (NaCl) as an impurity in the electrochemical degradation of micro-alloyed steel (MAS) when exposed to E20 simulated fuel grade ethanol (SFGE) environment. Immersion and electrochemical tests were carried out using NaCl concentrations ranging from 0 to 64 mg/L. Highest corrosion rates were obtained with 64 mg/L NaCl and lowest rates were observed in the zero chloride tests. Chloride was also seen to cause pitting corrosion on MAS. The results of potentiodynamic polarization tests on MAS compared well with mass loss corrosion rates. Analysis of variance (ANOVA) test confirms the significance of the results at 99% confidence, and further showed that there is significant difference between the chloride concentrations. However, from the perspective of corrosion in fuel ethanol, micro-alloyed steel is thought to be compatible with E20 since the determined corrosion rates were very low.

  5. Investigation of the Phase Formation of AlSi-Coatings for Hot Stamping of Boron Alloyed Steel

    Science.gov (United States)

    Veit, R.; Hofmann, H.; Kolleck, R.; Sikora, S.

    2011-01-01

    Hot stamping of boron alloyed steel is gaining more and more importance for the production of high strength automotive body parts. Within hot stamping of quenchenable steels the blank is heated up to austenitization temperature, transferred to the tool, formed rapidly and quenched in the cooled tool. To avoid scale formation during the heating process of the blank, the sheet metal can be coated with an aluminium-silicum alloy. The meltimg temperature of this coating is below the austenitization temperature of the base material. This means, that a diffusion process between base material and coating has to take place during heating, leading to a higher melting temperature of the coating. In conventional heating devices, like roller hearth furnaces, the diffusion process is reached by relatively low heating rates. New technologies, like induction heating, reach very high heating rates and offer great potentials for the application in hot stamping. Till now it is not proofed, that this technology can be used with aluminum-silicon coated materials. This paper will present the results of comparative heating tests with a conventional furnace and an induction heating device. For different time/temperature-conditions the phase formation within the coating will be described.

  6. Mechanical and Electro-Chemical Properties of Laser Surface Alloyed AISI 304 Stainless Steel with WC+Ni+NiCr

    Science.gov (United States)

    Majumdar, J. D.

    In the present study, a detailed evaluation of wear and corrosion resistance properties of laser surface alloyed of AISI 304 stainless steel with WC+Ni+NiCr (in the ratio of 70:15:15) has been undertaken. Laser processing has been carried out using a 5 kW continuous wave (CW) Nd:YAG laser (at a beam diameter of 3 mm) by surface melting and simultaneous deposition of precursor powder mixture in the melt zone (at a flow rate of 10 mg/s) and using Ar shroud at a gas flow rate of 5 l/min. Followed by laser processing, a detailed evaluation of fretting wear behavior has been conducted against WC surface. Finally, the corrosion property is measured using a potentiodynamic polarization testing unit in a 3.56 wt.% NaCl solution. The wear resistance property is significantly improved due to laser surface alloying which is attributed to the improvement in surface microhardness to 1350 VHN as compared to 220 VHN of as-received γ-stainless steel substrate. The mechanism of wear is established. The pitting corrosion resistance property is also improved due to the presence of Ni and Cr in solution and homogenization of microstructure due to laser processing.

  7. An Investigation of the Microstructure of an Intermetallic Layer in Welding Aluminum Alloys to Steel by MIG Process.

    Science.gov (United States)

    Nguyen, Quoc Manh; Huang, Shyh-Chour

    2015-12-02

    Butt joints of A5052 aluminum alloy and SS400 steel, with a new type of chamfered edge, are welded by means of metal inert gas welding and ER4043 Al-Si filler metal. The microhardness and microstructure of the joint are investigated. An intermetallic layer is found on the surface of the welding seam and SS400 steel sheet. The hardness of the intermetallic layer is examined using the Vickers hardness test. The average hardness values at the Intermetallic (IMC) layer zone and without the IMC layer zone were higher than that of the welding wire ER4043. The tensile strength test showed a fracture at the intermetallic layer when the tensile strength is 225.9 MPa. The tensile value test indicated the average of welds was equivalent to the 85% tensile strength of the A5052 aluminum alloy. The thickness of the intermetallic layers is non-uniform at different positions with the ranges from 1.95 to 5 μm. The quality of the butt joint is better if the intermetallic layer is minimized. The Si crystals which appeared at the welding seam, indicating that this element participated actively during the welding process, also contributed to the IMC layer's formation.

  8. An Investigation of the Microstructure of an Intermetallic Layer in Welding Aluminum Alloys to Steel by MIG Process

    Directory of Open Access Journals (Sweden)

    Quoc Manh Nguyen

    2015-12-01

    Full Text Available Butt joints of A5052 aluminum alloy and SS400 steel, with a new type of chamfered edge, are welded by means of metal inert gas welding and ER4043 Al-Si filler metal. The microhardness and microstructure of the joint are investigated. An intermetallic layer is found on the surface of the welding seam and SS400 steel sheet. The hardness of the intermetallic layer is examined using the Vickers hardness test. The average hardness values at the Intermetallic (IMC layer zone and without the IMC layer zone were higher than that of the welding wire ER4043. The tensile strength test showed a fracture at the intermetallic layer when the tensile strength is 225.9 MPa. The tensile value test indicated the average of welds was equivalent to the 85% tensile strength of the A5052 aluminum alloy. The thickness of the intermetallic layers is non-uniform at different positions with the ranges from 1.95 to 5 μm. The quality of the butt joint is better if the intermetallic layer is minimized. The Si crystals which appeared at the welding seam, indicating that this element participated actively during the welding process, also contributed to the IMC layer’s formation.

  9. Similar and Dissimilar Nd:YAGlaser Welding of NiTi Shape Memory Alloy to AISI 420Stainless Steel

    Directory of Open Access Journals (Sweden)

    Jassim Mohammed Salman Al-Murshdy

    2017-03-01

    Full Text Available Similar NiTi shape memory alloy(SMA plates, 420 Martensitic stainless steelplates and dissimilar NiTi shape memory alloy with Martensiticstainless steel were welded by a pulsed Nd:YAGlaser welding method.The nature microstructure of the base metal (BM, weld zone (WZ, interface and the heat affected zones(HAZ were showedby in a scanning electron microscope (SEM and optical microscope.Vickers hardness tests wasconducted to specifythe properties of the weld. The outcomes showed that the hardness of dissimilar NiTi-Stainless steel (St.St. weld is higher than that in similar NiTi-NiTi and St.St.-St.St. weld.TheMicrostructural examination in both NiTi-St.St. and NiTi-NiTi welds illustrates that the solidification process in the fusion zone changed the kind of plan to the cell type as well as the changes that occur in the cell to dentritic kind of intra- region of the weld through the weld center in the welded sample sides but in the St.St.-St.St. weld showed dendrite microstructure. In this study it is found that the increase of the welding speed leads to a decrease in hardness in all jointsNiTi-NiTi, NiTi-St.St. and St.St.-St.St.

  10. Identification of Intermetallic Compounds and Its Formation Mechanism in Boron Steel Hot-Dipped in Al-7 wt.% Mn Alloy

    Directory of Open Access Journals (Sweden)

    Sung-Yun Kwak

    2017-12-01

    Full Text Available In laser welding and hot stamping Al-Si-coated boron steel, there is a problem that the strength of the joint is lowered due to ferrite formation in the fusion zone. The purpose of this study is to develop an Al-7 wt.% Mn hot-dip coating in which Mn, an austenite stabilizing element, replaces the ferrite stabilizing element Si. The nucleation and formation mechanism of the reaction layer was studied in detail by varying the dipping time between 0 and 120 s at 773 °C. The microstructure and phase constitution of the reaction layer were investigated by various observational methods. Phase formation is discussed using a phase diagram calculated by Thermo-CalcTM. Under a 30 s hot-dipping process, no reaction occurred due to the formation of a Fe3O4 layer on the steel surface. The Fe3O4 layer decomposed by a reduction reaction with Al-Mn molten alloy, constituent elements of steel dissolved into a liquid, and the reaction-layer nucleus was formed toward the liquid phase. A coated layer consists of a solidified layer of Al and Al6Mn and a reactive layer formed beneath it. The reaction layer is formed mainly by inter-diffusion of Al and Fe in the solid state, which is arranged on the steel in the order of Al11Mn4 → FeAl3 (θ → Fe2Al5 (η phases, and the Fe3AlC (κ in several nm bands formed at the interface between the η-phase and steel.

  11. Hardness survey of cold-worked and heat-treated JBK-75 stainless steel alloy

    International Nuclear Information System (INIS)

    Jackson, R.J.; Lucas, R.L.

    1977-01-01

    The alloy JBK-75, an age-hardenable austenitic stainless steel, is similar to commercial A-286, but has certain chemistry modifications to improve weldability and hydrogen compatibility. The principal changes are an increase in nickel and a decrease in manganese with lower limits on carbon, phosphorus, sulfur, silicon, and boron. In this study, the effects of solutionizing time and temperature, quench rate, cold working, and the effects of cold working on precipitation kinetics were examined. Findings show that the solutionizing temperature has a moderate effect on the as-quenched hardness, while times greater than that required for solutionizing do not significantly affect hardness. Quench rate was found to have a small effect on as-quenched hardness, however, hardness gradients did not develop in small bars. It was found that JBK-75 can be significantly strengthened by cold working. Cold working alone produced hardness increases from Rockwell-A 49 to R/sub A/ 68. A recovery-related hardness change was noted on heat treating at 300 and 400 0 C for both as-quenched and as-worked JBK-75. Significant age-hardening was observed at temperatures as low as 500 0 C for as-worked metal. Aging at 600 0 C resulted in maximum hardness in the 75 percent worked sample at about 6 hours (R/sub A/ 73.5) while the 50 percent worked sample was near maximum hardness (R/sub A 72.5) after seven days. THE 25 and 0 percent worked samples were considerably underaged after seven days. Similar type kinetic data were obtained for worked and nonworked metal at 650, 700, 800, 850, 900, 1000, and 1100 0 C for times from 10 minutes to 10,000 minutes (6.7 days). The overall purpose of the hardness survey was to better define the effects of cold work on the stress-relieving range, coherent precipitation range, incoherent precipitation range, recrystallization range, solutionizing range, and grain-growth range

  12. Corrosion behaviour of low alloy steels: from ancient past to far future

    International Nuclear Information System (INIS)

    Santarini, G.

    2004-01-01

    With the envisaged concepts of long term storage and underground disposal of high level radioactive waste, corrosion science has to face a new challenge: to obtain reliable behaviour predictions over very long periods of time, up to thousands of years. For such durations, the development of mechanistically based models becomes an absolute necessity. In France, the first candidate materials considered for the containers of high level waste are low alloy steels because of their relatively low sensitivity to localized corrosion, when compared, for example, to passive materials: this characteristics makes their corrosion behaviour less difficult to predict. In this mechanistic modelling, numerous physicochemical steps have to be taken into consideration, such as chemical and/or electrochemical reactions, solid state diffusion of point defects, liquid state diffusion of chemical species in oxide pores, etc. However, since the complex links between all these steps highly depend on the nature and on the characteristics (porosity, conductivity, protectiveness, etc.) of the corrosion products, the first stage before the model construction is to obtain experimental data on this phenomenology in the very near environment of the metal. At the opposite, once a model constructed, it is necessary to compare its predictions to field experience, and to verify that the mechanisms and phenomenology retained in the model remain unchanged over very long periods of time. In the various stages of a progressive iterative model improvement, the examination of archaeological objects is liable to provide useful information. The considerable interest of such objects, in this context, comes from the long duration of the contact with a natural environment, a duration of the same order of magnitude as the one considered for high level waste storage. However, the differences between the ancient materials and the modern ones and also the poor knowledge about the initial conditions and about the

  13. Microstructure Control of Fire-resistant, Low-alloy Steel; An in-situ 3D X-ray Diffraction and A Small-angle X-ray Scattering Study

    NARCIS (Netherlands)

    Dere, E.G.

    2013-01-01

    The research presented in this thesis aims at deepening our understanding of the formation of the microstructure of steel during thermal processing in order to control the microstructure and thereby improve the fire-resistance of low-alloy steel. The strength of steel decreases during a fire mainly

  14. Intergranular corrosion in unserviced austenitic stainless steel pipes made of alloy 904L; Kornzerfall in nicht betriebsbeanspruchten rostfreien austenitischen Rohren aus Alloy 904L

    Energy Technology Data Exchange (ETDEWEB)

    Neidel, Andreas; Cagliyan, Erhan; Fischer, Boromir; Giller, Madeleine; Riesenbeck, Susanne [Siemens AG, Energy Sector, Berlin (Germany). Gasturbinenwerk Berlin

    2017-09-01

    Seamless tubes of the highly corrosion resistant austenitic steel 1.4539, X1NiCrMoCu25-20-5 (Alloy 904L) were observed to exhibit signs of inter-crystalline damage to a depth of several layers of grains and in particular on their internal surface. The material had been stored and had not been put into service. A number of hypotheses had been discussed to explain the predominant cause of the damage. Using optical light and scanning electron microscopy investigation techniques, clear evidence was obtained indicating it to be inter-crystalline corrosion due to the sensitisation of the grain boundaries. The most probable cause of this was determined to be the presence of residual deposits from the rolling process, which due to poor cleaning, had not been completely removed prior to the final solution annealing treatment. This explaining why predominantly the internal surface of the tubes was affected.

  15. The effect of molten salt on high temperature behavior of stainless steel and titanium alloy with the presence of water vapor

    Science.gov (United States)

    Baharum, Azila; Othman, Norinsan Kamil; Salleh, Emee Marina

    2018-04-01

    The high temperature oxidation experiment was conducted to study the behavior of titanium alloy Ti6A14V and stainless steel 316 in Na2SO4-50%NaCl + Ar-20%O2 (molten salt) and Na2SO4-50%NaCl + Ar-20%O2 + 12% H2O (molten salt + water vapor) environment at 900°C for 30 hours using horizontal tube furnace. The sample then was investigated using weight change measurement analysis and X-ray diffraction (XRD) analysis to study the weight gained and the phase oxidation that occurred. The weight gained of the titanium alloy was higher in molten salt environment compared to stainless steel due to the rapid growth in the oxide scale but showed almost no change of weight gained upon addition of water vapor. This is due to the alloy was fully oxidized. Stainless steel showed more protection and better effect in molten salt environment compared to mixed environment showed by slower weight gain and lower oxidation rate. Meanwhile, the phase oxidation test of the samples showed that the titanium alloy consist of multi oxide layer of rutile (TiO2) and Al2O3 on the surface of the exposed sample. While stainless steel show the formation of both protective Cr-rich oxide and non-protective Fe-rich oxide layer. This can be concluded that stainless steel is better compared to Ti alloy due to slow growing of chromia oxide. Therefore it is proven that stainless steel has better self-protection upon high temperature exposure.

  16. Investigations on discharge of stainless steel alloying components by condensates in condensing value boilers; Untersuchungen zum Austrag von Legierungsbestandteilen aus nichtrostenden Staehlen durch Kondensate in Brennwertanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Arlt, N. [Krupp Thyssen Nirosta GmbH, Duesseldorf (Germany); Heimann, W.; Dierschke, P. [Revierlabor, Chemische Laboratorien fuer Industrie und Umwelt GmbH, Essen (Germany); Steinbeck, G. [Verein Deutscher Eisenhuettenleute (VDEh), Duesseldorf (Germany)

    1999-04-01

    The research project investigated one of the ecological aspects of the condensing boiler technology, i.e. washout of alloying elements from the stainless steels of the boiler and exhaust system and the resulting pollution of liquid effluents. Investigations showed that the nickel concentrations in the condensation water samples were always less than the 1 mg/l specified in the pertinent legal regulations. Even in more difficult laboratory conditions, no erosion was observed in the standard steel 1.4571, i.e. the thicker walls required by DIN 4133 for steel chimney flues are unnecessary.

  17. Effect of heat input on microstructure and mechanical properties of dissimilar joints between super duplex stainless steel and high strength low alloy steel

    International Nuclear Information System (INIS)

    Sadeghian, M.; Shamanian, M.; Shafyei, A.

    2014-01-01

    Highlights: • The microstructure of weld metal consists of austenite and ferrite. • The HAZ of the API X-65 shows different transformation. • Impact strength of sample with low heat input was lower than base metals. • The heat input at 0.506 kJ/mm is not the suitable for dissimilar joining between UNS S32750/API X-65. - Abstract: In the present study, microstructure and mechanical properties of UNS S32750 super duplex stainless steel (SDSS)/API X-65 high strength low alloy steel (HSLA) dissimilar joint were investigated. For this purpose, gas tungsten arc welding (GTAW) was used in two different heat inputs: 0.506 and 0.86 kJ/mm. The microstructures investigation with optical microscope, scanning electron microscope and X-ray diffraction showed that an increase in heat input led to a decrease in ferrite percentage, and that detrimental phases were not present. It also indicated that in heat affected zone of HSLA base metal in low heat input, bainite and ferrite phases were created; but in high heat input, perlite and ferrite phases were created. The results of impact tests revealed that the specimen with low heat input exhibited brittle fracture and that with high heat input had a higher strength than the base metals

  18. Nanostructure evolution under irradiation of Fe(C)MnNi model alloys for reactor pressure vessel steels

    Energy Technology Data Exchange (ETDEWEB)

    Chiapetto, M., E-mail: mchiapet@sckcen.be [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium); Unité Matériaux Et Transformations (UMET), UMR 8207, Université de Lille 1, ENSCL, F-59600 Villeneuve d’Ascq Cedex (France); Becquart, C.S. [Unité Matériaux Et Transformations (UMET), UMR 8207, Université de Lille 1, ENSCL, F-59600 Villeneuve d’Ascq Cedex (France); Laboratoire commun EDF-CNRS Etude et Modélisation des Microstructures pour le Vieillissement des Matériaux (EM2VM) (France); Domain, C. [EDF R& D, Département Matériaux et Mécanique des Composants, Les Renardières, F-77250 Moret sur Loing (France); Laboratoire commun EDF-CNRS Etude et Modélisation des Microstructures pour le Vieillissement des Matériaux (EM2VM) (France); Malerba, L. [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium)

    2015-06-01

    Radiation-induced embrittlement of bainitic steels is one of the most important lifetime limiting factors of existing nuclear light water reactor pressure vessels. The primary mechanism of embrittlement is the obstruction of dislocation motion produced by nanometric defect structures that develop in the bulk of the material due to irradiation. The development of models that describe, based on physical mechanisms, the nanostructural changes in these types of materials due to neutron irradiation are expected to help to better understand which features are mainly responsible for embrittlement. The chemical elements that are thought to influence most the response under irradiation of low-Cu RPV steels, especially at high fluence, are Ni and Mn, hence there is an interest in modelling the nanostructure evolution in irradiated FeMnNi alloys. As a first step in this direction, we developed sets of parameters for object kinetic Monte Carlo (OKMC) simulations that allow this to be done, under simplifying assumptions, using a “grey alloy” approach that extends the already existing OKMC model for neutron irradiated Fe–C binary alloys [1]. Our model proved to be able to describe the trend in the buildup of irradiation defect populations at the operational temperature of LWR (∼300 °C), in terms of both density and size distribution of the defect cluster populations, in FeMnNi model alloys as compared to Fe–C. In particular, the reduction of the mobility of point-defect clusters as a consequence of the presence of solutes proves to be key to explain the experimentally observed disappearance of detectable point-defect clusters with increasing solute content.

  19. Cracking behavior and microstructure of austenitic stainless steels and alloy 690 irradiated in BOR-60 reactor, phase I.

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.; Chopra, O. K.; Soppet, W. K.; Shack, W. J.; Yang, Y.; Allen, T. R.; Univ. of Wisconsin at Madison

    2010-02-16

    Cracking behavior of stainless steels specimens irradiated in the BOR-60 at about 320 C is studied. The primary objective of this research is to improve the mechanistic understanding of irradiation-assisted stress corrosion cracking (IASCC) of core internal components under conditions relevant to pressurized water reactors. The current report covers several baseline tests in air, a comparison study in high-dissolved-oxygen environment, and TEM characterization of irradiation defect structure. Slow strain rate tensile (SSRT) tests were conducted in air and in high-dissolved-oxygen (DO) water with selected 5- and 10-dpa specimens. The results in high-DO water were compared with those from earlier tests with identical materials irradiated in the Halden reactor to a similar dose. The SSRT tests produced similar results among different materials irradiated in the Halden and BOR-60 reactors. However, the post-irradiation strength for the BOR-60 specimens was consistently lower than that of the corresponding Halden specimens. The elongation of the BOR-60 specimens was also greater than that of their Halden specimens. Intergranular cracking in high-DO water was consistent for most of the tested materials in the Halden and BOR-60 irradiations. Nonetheless, the BOR-60 irradiation was somewhat less effective in stimulating IG fracture among the tested materials. Microstructural characterization was also carried out using transmission electron microscopy on selected BOR-60 specimens irradiated to {approx}25 dpa. No voids were observed in irradiated austenitic stainless steels and cast stainless steels, while a few voids were found in base and grain-boundary-engineered Alloy 690. All the irradiated microstructures were dominated by a high density of Frank loops, which varied in mean size and density for different alloys.

  20. Development of bonding techniques for cryogenic components (2). HIP bonding between Cu Alloys and Ti, cryogenic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Shigeru; Ouchi, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Fukaya, Kiyoshi [Nihon Advanced Technology Ltd., Tokai, Ibaraki (Japan); Ishiyama, Shintaro [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Tsuchiya, Yoshinori; Nakajima, Hideo [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    2003-03-01

    Several joints between dissimilar materials are required in the superconducting (SC) magnet system of SC linear accelerator or fusion reactor, Pure titanium (Ti) is one of candidate materials for a jacket of SC coil of fusion reactor because Ti is non-magnetic material and has a feature that its thermal expansion is similar to SC material in addition to good corrosion resistance and workability. Also, Ti does not require strict control of environment during reaction heat treatment of SC material. Copper (Cu) or Cu-alloy is used in electrical joints and cryogenic stainless steel (SS) is used in cryogenic pipes. Therefore, it is necessary to develop new bonding techniques for joints between Ti, Cu, and SS because jacket, electrical joint and cryogenic pipe have to be bonded each other to cool SC coils. Japan Atomic Energy Research Institute (JAERI) has started to develop dissimilar material joints bonded by hot isostatic pressing (HIP), which can bring a high strength joint with good tolerance and can applied to a large or complex geometry device. HIP conditions for Cu-Ti, Cu alloy-Ti, Cu alloy-SS were investigated in this study and most stable HIP condition were evaluated by microscopic observation, tensile and bending tests at room temperature. (author)

  1. Metal release from stainless steel powders and massive sheets--comparison and implication for risk assessment of alloys.

    Science.gov (United States)

    Hedberg, Yolanda; Mazinanian, Neda; Odnevall Wallinder, Inger

    2013-02-01

    Industries that place metal and alloy products on the market are required to demonstrate that they are safe for all intended uses, and that any risks to humans, animals or the environment are adequately controlled. This requires reliable and robust in vitro test procedures. The aim of this study is to compare the release of alloy constituents from stainless steel powders of different grades (focus on AISI 316L) and production routes into synthetic body fluids with the release of the same metals from massive sheets in relation to material and surface characteristics. The comparison is justified by the fact that the difference between massive surfaces and powders from a metal release/dissolution and surface perspective is not clearly elucidated within current legislations. Powders and abraded and aged (24 h) massive sheets were exposed to synthetic solutions of relevance for biological settings and human exposure routes, for periods of up to one week. Concentrations of released iron, chromium, nickel, and manganese in solution were measured, and the effect of solution pH, acidity, complexation capacity, and proteins elucidated in relation to surface oxide composition and its properties. Implications for risk assessments based on in vitro metal release data from alloys are elucidated.

  2. Interfacial Bonding Energy on the Interface between ZChSnSb/Sn Alloy Layer and Steel Body at Microscale

    Directory of Open Access Journals (Sweden)

    Jianmei Wang

    2017-09-01

    Full Text Available To investigate the performance of bonding on the interface between ZChSnSb/Sn and steel body, the interfacial bonding energy on the interface of a ZChSnSb/Sn alloy layer and the steel body with or without Sn as an intermediate layer was calculated under the same loadcase using the molecular dynamics simulation software Materials Studio by ACCELRYS, and the interfacial bonding energy under different Babbitt thicknesses was compared. The results show that the bonding energy of the interface with Sn as an intermediate layer is 10% larger than that of the interface without a Sn layer. The interfacial bonding performances of Babbitt and the steel body with Sn as an intermediate layer are better than those of an interface without a Sn layer. When the thickness of the Babbitt layer of bushing is 17.143 Å, the interfacial bonding energy reaches the maximum, and the interfacial bonding performance is optimum. These findings illustrate the bonding mechanism of the interfacial structure from the molecular level so as to ensure the good bonding properties of the interface, which provides a reference for the improvement of the bush manufacturing process from the microscopic point of view.

  3. Effect of alloy grain size on the high-temperature oxidation behavior of the austenitic steel TP 347

    Directory of Open Access Journals (Sweden)

    Vicente Braz Trindade

    2005-12-01

    Full Text Available Generally, oxide scales formed on high Cr steels are multi-layered and the kinetics are strongly influenced by the alloy grain boundaries. In the present study, the oxidation behaviour of an austenite steel TP347 with different grain sizes was studied to identify the role of grain-boundaries in the oxidation process. Heat treatment in an inert gas atmosphere at 1050 °C was applied to modify the grain size of the steel TP347. The mass gain during subsequent oxidation was measured using a microbalance with a resolution of 10-5 g. The scale morphology was examined using SEM in combination with energy-dispersive X-ray spectroscopy (EDS. Oxidation of TP347 with a grain size of 4 µm at 750 °C in air follows a parabolic rate law. For a larger grain size (65 µm, complex kinetics is observed with a fast initial oxidation followed by several different parabolic oxidation stages. SEM examinations indicated that the scale formed on specimens with smaller grain size was predominantly Cr2O3, with some FeCr2O4 at localized sites. For specimens with larger grain size the main oxide is iron oxide. It can be concluded that protective Cr2O3 formation is promoted by a high density of fast grain-boundary diffusion paths which is the case for fine-grained materials.

  4. Development of Novel Pre-alloyed PM Steels for Optimization of Machinability and Fatigue Resistance of PM Components

    Science.gov (United States)

    Mardan, Milad; Blais, Carl

    2016-03-01

    It is well known that a large proportion of ferrous PM components require secondary machining operations for dimensional conformance or for producing geometrical features that cannot be generated during die compaction. Nevertheless, the machining behavior of PM parts is generally characterized as being "difficult" due to the presence of residual porosity that lowers thermal conductivity and induces interrupted cutting. Several admixed additives such as MnS and BN-h can be used to improve the machining behavior of PM steels. Nevertheless, their negative effect on mechanical properties, especially fatigue resistance, makes their utilization uninteresting for the fabrication of high-performance PM steel components. This article summarizes the work carried out to develop a novel PM steel that was especially engineered to form machinability enhancing precipitates. This new material is pre-alloyed with tin (Sn) in order to form Cu-Sn (Cu(α)) precipitates during transient liquid phase sintering. The newly developed material presents machinability improvement of 165% compared to reference material used in the PM industry as well as increases in toughness and fatigue resistance of 100% and 13%, respectively.

  5. Experimental study and modelling of the effect of microstructure on friction and wear mechanisms of low alloy steel

    Science.gov (United States)

    Trevisiol, C.; Jourani, A.; Bouvier, S.

    2017-12-01

    Few models are focused on the combined effects of microstructure and roughness on the tribological behavior of materials. Hardness is the material property mainly used in the tribological models which are usually at a macroscopic scale. For a dual-phase steel, experimental and predicted values of friction coefficients and specific wear resistances are compared. The investigated models are declined into two pressure distribution modes between the phases. Friction tests are performed between steel pins composed of a ferrite-martensite dual-phase microstructure against abrasive papers with various abrasive particle sizes ranging from 15 µm to 200 µm. By using heat treatments on a low alloy steel, dual-phase microstructures with various martensite volume fractions, ranging from 45% to 100%, are generated. As martensite volume fraction increases, the experimental and predicted results show that the specific wear resistance increases whereas the friction coefficient decreases. Furthermore, the latter evolutions depend on roughness. For a predominance of abrasive wear mechanisms generated by coarse abrasive particles (~200 µm), the experimental tribological parameters tend to follow the predicted ones associated to the mode characterized by equal pressures between the phases. Then, as the abrasive particle size decreases, abrasive wear mechanisms reduce whereas adhesive wear mechanisms increase and the experimental tribological parameters tend to follow the predicted ones associated to the mode characterized by equal wear rate between the phases.

  6. Effects of Zr, Ti, and Al Additions on Nonmetallic Inclusions and Impact Toughness of Cast Low-Alloy Steel

    Science.gov (United States)

    Bizyukov, Pavel V.; Giese, Scott R.

    2017-04-01

    A microalloying of the low-carbon and low-alloy cast steel was conducted with Zr, Ti, and Al that were added to the steel in four combinations. After heat treatment, the samples were tested for impact toughness at room temperature using the Charpy method. The highest values of impact toughness were obtained in the group treated with Zr, while Zr-Ti and Zr-Ti-Al groups showed moderate toughness values; the lowest values were observed in the Zr-Al group. Difference among the treatment groups was observed in the fracture mechanisms, morphology, and area distribution of the inclusions. High toughness values achieved in the trials treated with zirconium corresponded with smooth ductile fracture. The metal treated with a combination of zirconium and titanium had a relatively small area occupied by inclusions, but its toughness was also moderate. Lowest impact toughness values corresponded with the larger area occupied by the inclusions in the trials treated with aluminum. Also, a connection between the solubility product [Al][N] and impact toughness was established. The study also provides a qualitative description and quantitative analysis of the nonmetallic inclusions formation as a result of microalloying treatment. The precipitation sequence of the inclusions was described based on the thermochemical calculations for the nonmetallic compounds discovered in the experimental steel. A description of the size distribution, morphology, and composition was conducted for the oxides, nitrides, sulfides, and multiphase particles.

  7. Evaluation of the Effect of Different Plasma-Nitriding Parameters on the Properties of Low-Alloy Steel

    Science.gov (United States)

    Zdravecká, Eva; Slota, Ján; Solfronk, Pavel; Kolnerová, Michaela

    2017-07-01

    This work is concerned with the surface treatment (ion nitriding) of different plasma-nitriding parameters on the characteristics of DIN 1.8519 low-alloy steel. The samples were nitrided from 500 to 570 °C for 5-40 h using a constant 25% N2-75% H2 gaseous mixture. Lower temperature (500-520 °C) favors the formation of compound layers of γ' and ɛ iron nitrides in the surface layers, whereas a monophase γ'-Fe4 N layer can be obtained at a higher temperature. The hardness of this layer can be obtained when nitriding is performed at a higher temperature, and the hardness decreases when the temperature increases to 570 °C. These results indicate that pulsed plasma nitriding is highly efficient at 550 °C and can form thick and hard nitrided layers with satisfactory mechanical properties. The results show the optimized nitriding process at 540 °C for 20 h. This process can be an interesting means of enhancing the surface hardness of tool steels to forge dies compared to stamped steels with zinc coating with a reduced coefficient of friction and improving the anti-sticking properties of the tool surface.

  8. Incubation and development of corrosion in microstructures of low alloy steels under a thin liquid film of NaCl aqueous solution

    Science.gov (United States)

    Zhang, Wen-Hua; Yang, Shan-Wu; Guo, Jia; Liu, Zhi-Yong; He, Xin-Lai

    2010-12-01

    Electrochemical measurement, optical microscopy, and scanning electron microscopy were employed to investigate the corrosion behavior of some low alloy steels. The steels were held under a thin liquid film of 0.5wt% NaCl aqueous solution. It is found that the steels with the same chemical composition but different microstructures exhibit obviously different corrosion behaviors. However, the corrosion behavior of the steels with different compositions but the same microstructures may be similar in the present investigation. The corrosion rate of bainite is slower than that of ferrite and pearlite. The corrosion products of bainite are uniform and fine. The size of carbon-rich phases produces a great impact on the corrosion of the steels, whether in the initial stage or in the long term. It is easy to induce large pitting for carbon-rich phases with large size, which damages the compactness of the rust layer.

  9. Effect of alloying elements on the composition of carbide phases and mechanical properties of the matrix of high-carbon chromium-vanadium steel

    Science.gov (United States)

    Titov, V. I.; Tarasenko, L. V.; Utkina, A. N.

    2017-01-01

    Based on the results of phase physicochemical analysis of high-carbon chromium-vanadium steel, the predominant type of carbide that provides high wear resistance has been established, and its amount and amount of carbon in martensite have been determined. Data on the composition and the amount of carbide phase and on the chemical composition of the martensite of high-carbon steel have been obtained, which allows determination of the alloying-element concentration limits. The mechanical testing of heats of a chosen chemical composition has been carried out after quenching and low-temperature tempering. The tests have demonstrated benefits of new steel in wear resistance and bending strength with the fatigue strength being retained, compared to steels subjected to cementation. The mechanism of secondary strengthening of the steel upon high-temperature tempering has been revealed. High-temperature tempering can be applied to articles that are required to possess both high wear resistance and heat resistance.

  10. The Influence of Different Melting and Remelting Routes on the Cleanliness of High Alloyed Steels

    Science.gov (United States)

    Reiter, Gerhard; Schuetzenhoefer, Wolfgang; Tazreiter, Angelika; Martinez, Carlos; Wuerzinger, Paul; Loecker, Christian

    The cleanliness of steel has an essential impact on many properties like corrosion resistance or toughness. Beside the deoxidation treatment, remelting or even multiple remelting strongly influences the cleanliness and can result in huge improvements. After a rough overview on measurement methods and the melting and remelting facility at Böhler Edelstahl, this work first shows typical cleanliness results according to the ASTM E45 measurement of two different steel types taken from standard production. The investigated steels range from hot work tool steel to austenitic stainless steel covering also different kinds of deoxidation procedures. Furthermore the differences of various melting and remelting routes are described and compared to each other, including the process routes EAF, EAF+ESR, EAF+PESR and EAF+VAR. Additionally, the morphology and composition of the different inclusion types found in the investigated material are described and compared.

  11. Microstructure and stress corrosion cracking of the fusion boundary region in an alloy 182-A533B low alloy steel dissimilar weld joint

    International Nuclear Information System (INIS)

    Hou, Juan; Peng, Qunjia; Takeda, Yoichi; Kuniya, Jiro; Shoji, Tetsuo

    2010-01-01

    Research highlights: → High-angle misorientation at FB, type-II and type-I boundaries. → Highest residual strain and hardness in the zone between FB and type-II boundary. → Type-II and type-I boundaries had lower resistance to SCC growth than the FB. → Crack growth blunted by pitting at the FB. → Reactivation of crack growth from the pitting by oxidation along the grain boundary. - Abstract: Stress corrosion cracking (SCC) in the fusion boundary (FB) region of an Alloy 182-A533B low alloy steel (LAS) dissimilar weld joint in high temperature water doped with sulfate was studied following a microstructure characterization of the FB region. The microstructure characterization suggested the type-II and type-I boundaries in the dilution zone (DZ) adjacent to the FB had lower resistance to SCC growth than the FB. Crack propagating perpendicular to the FB in the DZ was observed to be blunted by pitting at the FB, followed by the reactivation from the pitting by localized oxidation along the grain boundary in LAS.

  12. Solid state alloying by plasma nitriding and diffusion annealing treatment for austenitic stainless steel

    International Nuclear Information System (INIS)

    Pinedo, C.E.; Vatavuk, J.; Oliveira, S.D. de; Tschiptschin, A.P.

    1999-01-01

    Nitrogen has been added to stainless steels to improve mechanical strength and corrosion resistance. High nitrogen steel production is limited by high gas pressure requirements and low nitrogen solubility in the melt. One way to overcome this limitation is the addition of nitrogen in solid state because of its higher solubility in austenite. However, gas and salt bath nitriding have been done at temperatures around 550 C, where nitrogen solubility in the steel is still very low. High temperature nitriding has been, thus proposed to increase nitrogen contents in the steel but the presence of oxide layers on top of the steel is a barrier to nitrogen intake. In this paper a modified plasma nitriding process is proposed. The first step of this process is a hydrogen plasma sputtering for oxide removal, exposing active steel surface improving nitrogen pickup. This is followed by a nitriding step where high nitrogen contents are introduced in the outermost layer of the steel. Diffusion annealing is then performed in order to allow nitrogen diffusion into the core. AISI 316 austenitic stainless steel was plasma nitrided and diffusion annealed at 1423K, for 6 hours, with 0.2 MPa nitrogen pressure. The nitrided steel presented ∝60 μm outermost compact layer of (Fe,Cr) 3 N and (Fe,Cr) 4 N with 11 wt.% N measured by surface depth profiling chemical analysis - GDS system. During the annealing treatment the nitride layer was dissolved and nitrogen diffused to the core of the sample leaving more even nitrogen distribution into the steel. Using this technique one-millimetre thick sample were obtained having high nitrogen content and uniform distribution through the thickness. (orig.)

  13. Development of Highly Ductile Spheroidized Steel from High C (0.61 wt.% C) Low-Alloy Steel

    Science.gov (United States)

    Monia, S.; Varshney, A.; Gouthama; Sangal, S.; Kundu, S.; Samanta, S.; Mondal, K.

    2015-11-01

    This research aims to develop a multiphase steel combining spheroidal cementite and bainite in ductile ferrite matrix possessing an optimal balance of reasonably high strength and excellent ductility. A high carbon (0.61 wt.%) high silicon (1.71 wt.%) EN45 spring steel was annealed to obtain ferrite pearlite microstructure. The samples were given 5 and 10% cold rolling followed by holding at temperature below Ac1 for about 3 h. The samples were then held in intercritical range at 770 °C temperature for different durations ranging from 5 to 20 min for partial re-austenitization followed by quenching in a salt bath maintained at 350 °C and holding for 10 min to get bainite. The samples were finally water quenched. Characterizations of the samples with the help of optical microscopy, x-ray diffraction, scanning electron microscopy, and atomic force microscopy were carried out. Optimal heat-treatment conditions were found out after correlating with tensile properties. The best combination of high tensile strength (~800 MPa) with very high elongation (~29%) was obtained. Effects of cold-rolled strain and holding time in the intercritical region on the mechanical properties and microstructural changes were studied. Finally, structural property correlation is established.

  14. Review of corrosion phenomena on zirconium alloys, niobium, titanium, inconel, stainless steel, and nickel plate under irradiation

    International Nuclear Information System (INIS)

    Johnson, A.B. Jr.

    1975-01-01

    The role of nuclear fluxes in corrosion processes was investigated in ATR, ETR, PRTR, and in Hanford production reactors. Major effort was directed to zirconium alloy corrosion parameter studies. Corrosion and hydriding results are reported as a function of oxygen concentration in the coolant, flux level, alloy composition, surface pretreatment, and metallurgical condition. Localized corrosion and hydriding at sites of bonding to dissimilar metals are described. Corrosion behavior on specimens transferred from oxygenated to low-oxygen coolants in ETR and ATR experiments is compared. Mechanism studies suggest that a depression in the corrosion of the Zr--2.5Nb alloy under irradiation is due to radiation-induced aging. The radiation-induced onset of transition on several alloys is in general a gradual process which nucleates locally, causing areas of oxide prosity which eventually encompass the surface. Examination of Zry-2 process tubes reveals that accelerated corrosion has occurred in low-oxygen coolants. Hydrogen contents are relatively low, but show some localized profiles. Gross hydriding has occurred on process tubes containing aluminum spacers, apparently by a galvanic charging mechanism. Titanium paralleled Zry-2 in corrosion behavior under irradiation. Niobium corrosion was variable, but did not appear to be strongly influenced by radiation. Corrosion rates on Inconel and stainless steel were only slightly higher in-flux than out-of-reactor. Corrosion rates on nickel-plated aluminum appeared to vary substantially with preexposure treatments, but the rates generally were accelerated compared to rates on unirradiated coupons. (59 references, 11 tables, 12 figs.)

  15. Effect of Contact Time on Interface Reaction between Aluminum Silicon (7% and 11% Alloy and Steel Dies SKD 61

    Directory of Open Access Journals (Sweden)

    Bambang Suharno

    2010-10-01

    Full Text Available Die soldering (die sticking is a defect of metal casting in which molten metal “welds” to the metallic die mold surface during casting process. Die soldering is the result of an interface reaction between the molten aluminum and the die material. Aluminum alloy with 7 and 11% silicon and SKD 61 die steel are the most common melt and die material used in aluminum die casting. This research is done to study the morphology and the characteristics of the formed AlxFeySiz intermetallic layer during interface reaction at dipping test. The samples of as-anneal SKD 61 tool steel was dipped into the molten of Al-7%Si held at temperature 680oC and into molten Al-11%Si held at temperature 710oC with the different contact time of 10 minutes; 30 minutes; and 50 minutes. The research results showed that the interface reaction can form a compact intermetallic layer with AlxFey phase and a broken intermetallic layer with AlxFeySiz phase on the surface of SKD 61 tool steel. The increasing of the contact time by the immersion of material SKD 61 tool steel in both of molten Al-7%Si and Al-11%Si will increase the thickness of the AlxFeySiz intermetallic layer until an optimum point and then decreasing. The micro hardness of the AlxFeySiz intermetallic layer depends on the content of the iron. Increasing of the iron content in intermetallic layer will increase the micro hardness of the AlxFeySiz. This condition happened because the increasing of Fe content will cause forming of intermetallic AlxFeySiz phase becomes quicker.

  16. Dynamic study of passive layers formed on stainless steels in chloride environment. Correlation with stress corrosion behaviour - influence of some alloying elements

    International Nuclear Information System (INIS)

    Rhanim, Hassan

    1985-01-01

    This research thesis reports the study of the nature and stability of passive films formed on stainless steels in chloride solutions in order to predict the conditions under which some forms of localized corrosion may occur. It aims at understanding the influence of surface preparation, of temperature, of strain rate, and, above all, of alloying elements on the reconstruction kinetics of the passive film after a disturbance induced by a mechanical action. After a discussion of the various techniques used to study passive films, and of their results, the author presents the experimental method (potentiostatic test and mechanical de-passivation test) and the obtained results which are then interpreted, more particularly in terms of influence of alloying elements (nickel, molybdenum, copper, titanium, austeno-ferritic steel). Correlations are established between the dynamic behaviour of passive films formed on the studied steels, and their sensitivity to stress corrosion cracking [fr

  17. Effect of nitrogen alloying of stainless steels on their corrosion stability

    International Nuclear Information System (INIS)

    Chigal, V.; Knyazheva, V.M.; Pitter, Ya.; Babich, S.G.; Bogolyubskij, S.D.

    1986-01-01

    Results of corrosion tests and structural investigations of 03Cr18Ni10 and 03Cr18Ni10Mo3 steels without nitrogen and with nitrogen content of 0.15-0.3% are presented. Corrosion-electrochemical behaviour of Cr20Ni20 steel with ultralow carbon content (0.004-0.006%) and nitrogen content with 0-0.5% as well as Cr 2 N nitride behaviour are investigated. A conclusion is made on nitrogen and excessive nitride phase effect on corrosion stability of steel in corrosive media with different reduction-oxidation properties

  18. A feasibility study on different NDT techniques used for testing bond quality in cold roll bonded Al-Sn alloy/steel bimetal strips

    Directory of Open Access Journals (Sweden)

    Tallafuss Philipp Johannes

    2017-01-01

    Full Text Available This paper presents non-destructive testing (NDT results for the detection of bond defects in aluminium-tin (Al-Sn alloy/steel bimetal strips. Among all types of bimetal strip that are used in the automotive industry for plain journal engine bearings, Al-Sn alloys cold roll bonded (CRB onto steel backing is the most common type. The difficulty to evaluate the metallurgical bond between the two dissimilar metals is a major industrial concern, which comprises the risk that bearings fail in the field. Considering the harsh performance requirements, 100% online non-destructive testing would be desirable to significantly reduce the business risk. Nowadays bimetal strip manufacturers still rely on destructive testing through different peel-off tests. This work offers the results from four independent NDT studies, using active thermography, shearography, ultrasound and guided wave electromagnetic acoustic transducers (EMATs and samples with different artificially implanted defects, to explore the feasibility to qualitatively indicate the occurrence of bond defects. A destructive peel off test was used to correlate the NDT results with known bond quality. The studies were done under laboratory conditions, and in case of ultrasound also online under production conditions. During the ultrasound online test, the requirements that a NDT technique has to fulfil for online inspection of Al-Sn alloy/steel bimetal strip were established. For active thermography, shearography and guided wave EMAT techniques, it was theoretically analysed, if the laboratory test results could be transferred to testing under production conditions. As a result, guided waves using EMATs, among the four tested methods, are best suited for online inspection of Al-Sn alloy/steel bimetal strip. This research was carried out in collaboration with MAHLE Engine Systems UK Ltd., an Al-Sn alloy/steel bimetal strip manufacturer for the automotive industry.

  19. Microstructural-Scale Model for Surfaces Spreading of Intergranular Corrosion in Sensitized Stainless Steels and Aluminum-Magnesium (AA5XXX) Alloys

    Science.gov (United States)

    Jain, Swati

    Components from AA5XXX (Al-Mg alloys with more than 3 wt% Mg) alloys are X attractive due to availability of low cost, high strength to weight ratio and good weldability. Therefore, these alloys have potential applications in Naval ships. However, these alloys become susceptible to IGC (intergranular corrosion) due to beta-phase precipitation due to improper heat treatment or inadvertent thermal exposure. Stainless steels may also become susceptible due to carbide precipitation and chromium depletion on grain boundaries. IGC susceptibility depends on the interplay between the metallurgical conditions, electrochemical conditions, and chemical conditions. Specific combinations cause IGC while others do not. The objective of this study is to investigate the conditions which bring about surface spreading of IGC in these alloy classes. To accomplish this goal, a microstructure scale model was developed with experimental inputs to understand the 2-D IGC spreading in stainless steels and AA5XXX alloys. The conditions strongly affecting IGC spreading were elucidated. Upon natural and artificial aging, the stainless steels become susceptible to intergranular corrosion because of chromium depletion in the grain boundaries. After aging Al-Mg (AA5XXX) alloys show susceptibility due to the precipitation of the beta-phase (Al3Mg7) in the grain boundaries. Chromium depleted grain boundaries in stainless steels are anodically more active as compared to the interior of the grains. (3-phase rich grain boundaries have lower OCP (open circuit potential) and pitting potentials as compared to the Al-Mg solid solutions. A new approach to modeling the IGC surface spreading in polycrystalline materials that is presented. This model is the first to couple several factors into one granular scale model that illustrates the way in which they interact and IGC occurs. It sheds new information on conditions which cause IGC spreading in two alloy classes and describes a new theory for the critical

  20. Microdomain Yield Behaviour in an Ultra-High Strength Low Alloy Steel for Marine Use with Low Sensitivity of SCC

    Science.gov (United States)

    Yin, Jiang; Tao, Anxiang; Xu, Pingguang; Ping, Dehai

    The present paper involves a fundamental research on microdomain yield behavior of an ultrahigh strength low alloy steel with high temperature tempered bainite. The smooth cylinder specimen was took from deep water mooring chain links from the steel with the chemical composition of 0.23C-0.25Si -0.70Mn-3.55 (Cr+Ni+Mo) -0.13 (V+Nb+Ti) (mass %) ,which was quenched from 1253K and then tempered at 873K Its macroscopic yield strength is 1120MPa and the tensile strength is 1250MPa In-situ neutron diffraction measurements of loading tension have suggested that a good linear elastic deformation can be kept up to 500MPa stress, and then (200) priority non-linear elastic strain, that is the yield of crystal lattice occur at 700MPa and the (110) non-linear elastic strain was found at 800MPa. The (200) and (110) nonlinear elastic strain increases gradually when the stress was further increased, however, the (211) kept its linear elastic deformation stage as before. The sub-microstructural analysis carried out using TEM and additional determine the nature and quantitative analysis has revealed that there are three kinds of alloy carbides: (1) θ-M3C cementites with an average particle size of less than 50 nm which inside laths and lath boundaries; (2) ɛ-M2C formed uniformly within the ferrites with a length of less than 200 nm and width of less than 20 nm; (3) ultra-fine high density MC cohered with matrix α-Fe and its particle size is about 2 nm. The whole microdomain yield behaviour of the material was possibly influenced by the fcc-MC with high density. The results of CLT (constant load), SSRT (slow strain rate) and KIscc test of the present chain in seawater solution indicate, that threshold value of SCC (stress corrosion cracking) stress exceed 0.8 tensile strength and the chain's KIscc value is double of KIscc value of 4340 steel type parts. MC not only form strong hydrogen trap, but also slow down microdomain yield likely by means of increasing yield strength of

  1. Thermomechanical Testing and Microstructural Development of Class L Steel Wheel Alloy

    Science.gov (United States)

    1994-03-01

    Macrostructure, microstructure, and quantitative metallographic analysis is conducted on Association of American Railroads Class L wheel steel specimens tested in a Gleeble 1500 under combined mechanical compression and resistance heating to temperat...

  2. Conditions of structure formation in sparingly alloyed steels intended for service under enhanced wear

    Science.gov (United States)

    Krylova, S. E.; Gryzunov, V. I.; Firsova, N. V.; Sokolov, S. O.

    2011-09-01

    A new armor lining steel 100Kh3G2MTR is fabricated and investigated. Different regimes of heat treatment of the steel are studied for the purpose of achieving optimal characteristics of abrasive and shock-abrasive resistance in combination with enhanced surface hardness with satisfactory strength and impact toughness of the metallic matrix. Astructural analysis is performed and the mechanism of phase transformations in the surface layer in the course of heat treatment and in service is described.

  3. 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

  4. Local mechanical fields simulation: application to low alloy steels; Simulation des champs mecaniques locaux: application aux aciers faiblement allies

    Energy Technology Data Exchange (ETDEWEB)

    Libert, M.; Rey, C. [Laboratoire MSSMat / Ecole Centrale Paris, Grande Voie des Vignes 92295 CHATENAY MALABRY (France); Libert, M.; Marini, B. [Commissariat a l Energie Atomique DEN/SAC/DMN/SRMA, 91191 GIF-sur-YVETTE (France)

    2006-07-01

    The aim of this study is to take into account the effect of the plasticity mechanisms on the ductile-brittle transition in low alloy steels constituent the PWR reactors vessels. A crystalline plasticity model which describes the temperature effect on the behaviour has been implemented in a framework of great transformations. The mechanical and microstructural characterizations have allowed to determine several parameters, the others have then been identified by an inverse method from tensile mechanical tests. Polycrystalline aggregates simulations have been carried out at imposed triaxiality. The study of local heterogeneities show that the main stress distributions can be modelled by a distribution of extreme values of first specie (Gumbel) and that the parameters of this distribution can be easily described as a function of {sigma}{sub mises} and T. This approach will allow later on to introduce the effect of these heterogeneities in a local approach criteria of rupture. (O.M.)

  5. New Insights in the Long-Term Atmospheric Corrosion Mechanisms of Low Alloy Steel Reinforcements of Cultural Heritage Buildings.

    Science.gov (United States)

    Bouchar, Marie; Dillmann, Philippe; Neff, Delphine

    2017-06-19

    Reinforcing clamps made of low alloy steel from the Metz cathedral and corroded outdoors during 500 years were studied by OM, FESEM/EDS, and micro-Raman spectroscopy. The corrosion product layer is constituted of a dual structure. The outer layer is mainly constituted of goethite and lepidocrocite embedding exogenous elements such as Ca and P. The inner layer is mainly constituted of ferrihydrite. The behaviour of the inner layer under conditions simulating the wetting stage of the RH wet/dry atmospheric corrosion cycle was observed by in situ micro-Raman spectroscopy. The disappearance of ferrihydrite near the metal/oxide interface strongly suggests a mechanism of reductive dissolution caused by the oxidation of the metallic substrate and was observed for the first time in situ on an archaeological system.

  6. New Insights in the Long-Term Atmospheric Corrosion Mechanisms of Low Alloy Steel Reinforcements of Cultural Heritage Buildings

    Directory of Open Access Journals (Sweden)

    Marie Bouchar

    2017-06-01

    Full Text Available Reinforcing clamps made of low alloy steel from the Metz cathedral and corroded outdoors during 500 years were studied by OM, FESEM/EDS, and micro-Raman spectroscopy. The corrosion product layer is constituted of a dual structure. The outer layer is mainly constituted of goethite and lepidocrocite embedding exogenous elements such as Ca and P. The inner layer is mainly constituted of ferrihydrite. The behaviour of the inner layer under conditions simulating the wetting stage of the RH wet/dry atmospheric corrosion cycle was observed by in situ micro-Raman spectroscopy. The disappearance of ferrihydrite near the metal/oxide interface strongly suggests a mechanism of reductive dissolution caused by the oxidation of the metallic substrate and was observed for the first time in situ on an archaeological system.

  7. Microstructure and phase composition of Fe-B-Al coatings on low carbon steel prepared by using mechanical alloying technique

    Science.gov (United States)

    Sundawa, R. Y.; Aryanto, D.; Wismogroho, A. S.; Sudiro, T.

    2017-04-01

    In the present study, varying composition of FeB-Al was coated on low carbon steel by using mechanical alloying technique for 4 hours and followed by heat treatment in vacuum atmosphere of 5.9 Pa at 700 °C. The microstructure and formed phases of FeB-50 at.%Al, FeB-25 at.%Al, FeB-12.5 at.%Al and FeB coatings were intensively discussed. The cross sectional observation indicates that the coating thickness tends to increase with increasing Al content. Before heat treatment, the coatings are composed of FeB and Al phases, depending on coating composition.. After heat treatment, the intermetallic phases were identified. Interdifussion layer was also formed in the FeB-50 at.%Al coating after heat treatment.

  8. Stainless steel surface alloying process with molybdenum or ruthenium by high-energy excimer laser: structural, electrochemical, and corrosion properties

    Science.gov (United States)

    Beaunier, Luc; Pasquier, Christian; Pillier, Francoise; Laurens, Patricia

    1997-08-01

    Chemical transformations on stainless steel surfaces (304 AISI) are obtained by melting with an excimer laser. The very high quenching rate allows to create a thin continuous metastable gradient in composition and structure by opposition to other melting techniques which promote multiphase layer. The mechanical properties of the bulk are maintained and the external layer is chemically modified for a better resistance to environmental aggressivity. Molybdenum is used for corrosion protection and ruthenium for cathodic and anodic properties. The composition is analyzed on cross-sections obtained by ultramicrotomy. A continuous gradient approximately 500 nm (nanometer) of Mo or Ru with decreasing grain size (304 AISI) is observed. Mo and Ru surface alloys show an important beneficial effect from cathodic and transpassive potential range.

  9. DIFFUSION BONDING OF TITANIUM ALLOY TI-6AL-4V AND AISI 304 STAINLESS STEEL – AN EXPERIMENTAL INVESTIGATION

    Directory of Open Access Journals (Sweden)

    M. BALASUBRAMANIAN

    2015-10-01

    Full Text Available Titanium alloy Ti-6Al-4V and AISI 304 stainless steel were diffusion bonded at various temperatures and holding times. The experimental investigation of the process parameters of the diffusion bonded coupons was carried out. Lap shear tests were performed to determine the strength of the joint, and hardness measurements were taken to understand the hardness in the diffusion region. Diffusion bonding was performed from the lower temperature to the higher temperature considering melting point of the parent material. Hardness measurement at the diffusion layer is almost equal to the parent material. Optical microscopy examination was carried out to determine the quality of the joint and XRD analysis was carried out to confirm the formation of intermetallic compounds. The highest lap shear strength of 138.3 MPa was obtained at 800˚C at 60min holding time under 5 MPa pressure.

  10. Effect of long-term thermal aging on magnetic hysteresis for low-alloy pressure vessel steel

    Science.gov (United States)

    Kobayashi, Satoru; Gillemot, Ferenc; Horváth, Ákos; Horváth, Marta; László, Almásy

    2017-10-01

    Long-term thermal aging experiments have been performed at 290 and 550°C up to ∼ 10000 h for low-alloy pressure vessel steels with low and high Ni contents, in order to elucidate effects of thermal embrittlement on a structure-sensitive property of minor B-H loops. While a minor-loop property obtained from a power-law scaling of minor-loop parameters exhibits a small but steady increase after aging at 290°C, that exhibits a decreasing trend after aging at 550°C. The observations suggest that the evolution of nanometer precipitates plays a crucial role for a magnetic property change at 290°C, while relaxation of lattice strain in a matrix associated with precipitation may dominate at 550°C.

  11. Effects of N and B on continuous cooling transformation diagrams of Mo-V-Ti micro-alloyed steels

    Science.gov (United States)

    Yuhui, Wang; Bo, Liao; Ligang, Liu; Xianfeng, Li; Hang, Su; Caifu, Yang; Qingfeng, Wang

    2012-05-01

    Effects of the single addition of nitrogen (N) and boron (B) and the combined addition of N and B on continuous cooling transformation (CCT) diagrams and properties of the three Mo-V-Ti micro-alloyed steels were investigated by means of a combined method of dilatometry and metallography. Microstructures observed in continuous cooled specimens were composed of pearlite (P), quasi-polygonal ferrite (QPF), granular bainite (GB), acicular ferrite (AF), lath-like bainite (LB) and martensite (M) depending on the cooling rates and transformation temperatures. Single addition of 12 ppm B effectively reduced the formation of QPF and broadened the cooling rate region for LB and M. Added N makes the action of B invalid and the QPF region was prominently broadened, and even though the cooling rate is higher than 50°C s-1, it cannot obtain full bainite.

  12. Effects of minor alloying additions on the strength and swelling behavior of an austenitic stainless steel

    International Nuclear Information System (INIS)

    Gessel, G.R.

    1978-06-01

    A set of 32 alloys consisting of various additions of the elements Mo, W, Al, Ti, Nb, C and Si to an Fe-7.5 Cr-20 Ni alloy were made in order to investigate the effects of these solute additions on alloy swelling and strength. Both single and multiple additions were examined. The influence of various solute elements on the swelling behavior in the range 500 to 730 0 C was investigated using 4 MeV Ni ion bombardment to a dose 170 dpa. It was found that on an atomic percent basis, the elements may be arranged in order of decreasing effectiveness in reducing peak temperature swelling as follows: Ti, C, Nb, Si, and Mo. Small amounts of aluminum enhance swelling. Additions of Si, Ti, or Nb truncate the high temperature swelling regime of the ternary alloy. Mo, W, and C do not have a strong effect on the temperature dependence of swelling. The results may be interpreted in terms of the effect of point defect trapping on void growth rates, and it is suggested that the changes in peak temperature are the result of small changes in the free vacancy formation energy. A method for treating certain multiple additions is proposed. The effect of these alloying additions on short time high temperature strength properties was estimated using hot hardness measurements over the temperature range 22 to 850 0 C. On an atom percent basis Nb and Ti were most effective in conferring solid solution strengthening and Si the least effective. In the regime 22 to approximately 650 0 C, the hardness data was found to fit an equation of the form: H = H 0 + b/T; where H is the hardness, T is the temperature, and H 0 and b are constants for a given alloy. An empirical method was devised to estimate the hot hardness of alloys containing more than one solute addition

  13. Improvement of mechanical strength of sintered Mo alloyed steel by optimization of sintering and cold-forging processes with densification

    Science.gov (United States)

    Kamakoshi, Y.; Shohji, I.; Inoue, Y.; Fukuda, S.

    2017-10-01

    Powder metallurgy (P/M) materials have been expected to be spread in automotive industry. Generally, since sintered materials using P/M ones contain many pores and voids, mechanical properties of them are inferior to those of conventional wrought materials. To improve mechanical properties of the sintered materials, densification is effective. The aim of this study is to improve mechanical strength of sintered Mo-alloyed steel by optimizing conditions in sintering and cold-forging processes. Mo-alloyed steel powder was compacted. Then, pre-sintering (PS) using a vacuum sintering furnace was conducted. Subsequently, coldforging (CF) by a backward extrusion method was conducted to the pre-sintered specimen. Moreover, the cold-forged specimen was heat treated by carburizing, tempering and quenching (CQT). Afterwards, mechanical properties were investigated. As a result, it was found that the density of the PS specimen is required to be more than 7.4 Mg/m3 to strengthen the specimen by heat treatment after CF. Furthermore, density and the microstructure of the PS specimen are most important factors to make the high density and strength material by CF. At the CF load of 1200 kN, the maximum density ratio reached approximately 99% by the use of the PS specimen with proper density and microstructure. At the CF load of 900 kN, although density ratio was high like more than 97.8%, transverse rupture strength decreased sharply. Since densification caused high shear stress and stress concentration in the surface layer, microcracks occurred by the damages of inter-particle sintered connection of the surface layer. On the contrary, in case of the CF load of 1200 kN, ultra-densification of the surface layer occurred by a sufficient plastic flow. Such sufficient compressed specimens regenerated the sintered connections by high temperature heat treatment and thus the high strength densified material was obtained. These processes can be applicable to near net shape manufacturing

  14. Study and development of solid fluxes for gas tungsten arc welding applied to titanium and its alloys and stainless steels

    International Nuclear Information System (INIS)

    Perry, N.

    2000-06-01

    Gas Tungsten Arc Welding uses an electric arc between the refractory tungsten electrode and the plates to be welded under an argon shielding gas. As a result, the joint quality is excellent, no pollution nor defects are to be feared, consequently this process is used in nuclear, aeronautic, chemical and food industries. Despite of this good qualities, GTAW is limited because of, on the one side, a poor penetrating weld pool and, on the other side, a week productivity rate. Indeed, up to 3 mm thick plates, machining and filler metal is needed. Multiple runs increase the defect's risks, the manufactory time and increase the deformations and the heat affected zone. The goal of this study is to break through this limits without any device investment. Active GTA welding (or ATIG) is a new technique with GTA device and an activating flux to be spread on the upper plate before welding. The arc, by plasma electrochemical equilibrium modifications, and the pool with the inner connective flows inversion, allow 7 mm thick joints in one run without edges machining or filler metal for both stainless steel and titanium alloys. This manuscript describes the development of these fluxes, highlights the several phenomena and presents the possibilities of this new process. This work, in collaboration with B.S.L. industries, leads to two flux formulations (stainless steel and titanium alloys) now in a commercial phase with CASTOLIN S.A. Moreover, B.S.L.industries produces a pressure device (nitrate column) with the ATIG process using more than 2800 ATIG welds. (author)

  15. Pitting corrosion resistance and bond strength of stainless steel overlay by friction surfacing on high strength low alloy steel

    Directory of Open Access Journals (Sweden)

    Amit Kumar Singh

    2015-09-01

    Full Text Available Surface modification is essential for improving the service properties of components. Cladding is one of the most widely employed methods of surface modification. Friction surfacing is a candidate process for depositing the corrosion resistant coatings. Being a solid state process, it offers several advantages over conventional fusion based surfacing process. The aim of this work is to identify the relationship between the input variables and the process response and develop the predictive models that can be used in the design of new friction surfacing applications. In the current work, austenitic stainless steel AISI 304 was friction surfaced on high strength low alloy steel substrate. Friction surfacing parameters, such as mechtrode rotational speed, feed rate of substrate and axial force on mechtrode, play a major role in determining the pitting corrosion resistance and bond strength of friction surfaced coatings. Friction surfaced coating and base metal were tested for pitting corrosion by potentio-dynamic polarization technique. Coating microstructure was characterized using optical microscopy, scanning electron microscopy and X-ray diffraction. Coatings in the as deposited condition exhibited strain-induced martensite in austenitic matrix. Pitting resistance of surfaced coatings was found to be much lower than that of mechtrode material and superior to that of substrate. A central composite design with three factors (mechtrode rotational speed, substrate traverse speed, axial load on mechtrode and five levels was chosen to minimize the number of experimental conditions. Response surface methodology was used to develop the model. In the present work, an attempt has been made to develop a mathematical model to predict the pitting corrosion resistance and bond strength by incorporating the friction surfacing process parameters.

  16. Additive manufacturing of metals: a brief review of the characteristic microstructures and properties of steels, Ti-6Al-4V and high-entropy alloys

    Science.gov (United States)

    Gorsse, Stéphane; Hutchinson, Christopher; Gouné, Mohamed; Banerjee, Rajarshi

    2017-01-01

    Abstract We present a brief review of the microstructures and mechanical properties of selected metallic alloys processed by additive manufacturing (AM). Three different alloys, covering a large range of technology readiness levels, are selected to illustrate particular microstructural features developed by AM and clarify the engineering paradigm relating process–microstructure–property. With Ti-6Al-4V the emphasis is placed on the formation of metallurgical defects and microstructures induced by AM and their role on mechanical properties. The effects of the large in-built dislocation density, surface roughness and build atmosphere on mechanical and damage properties are discussed using steels. The impact of rapid solidification inherent to AM on phase selection is highlighted for high-entropy alloys. Using property maps, published mechanical properties of additive manufactured alloys are graphically summarized and compared to conventionally processed counterparts. PMID:28970868

  17. Additive manufacturing of metals: a brief review of the characteristic microstructures and properties of steels, Ti-6Al-4V and high-entropy alloys.

    Science.gov (United States)

    Gorsse, Stéphane; Hutchinson, Christopher; Gouné, Mohamed; Banerjee, Rajarshi

    2017-01-01

    We present a brief review of the microstructures and mechanical properties of selected metallic alloys processed by additive manufacturing (AM). Three different alloys, covering a large range of technology readiness levels, are selected to illustrate particular microstructural features developed by AM and clarify the engineering paradigm relating process-microstructure-property. With Ti-6Al-4V the emphasis is placed on the formation of metallurgical defects and microstructures induced by AM and their role on mechanical properties. The effects of the large in-built dislocation density, surface roughness and build atmosphere on mechanical and damage properties are discussed using steels. The impact of rapid solidification inherent to AM on phase selection is highlighted for high-entropy alloys. Using property maps, published mechanical properties of additive manufactured alloys are graphically summarized and compared to conventionally processed counterparts.

  18. Hydrogen diffusion and effect on degradation in welded microstructures of creep-resistant low-alloyed steels

    Energy Technology Data Exchange (ETDEWEB)

    Rhode, Michael

    2016-04-04

    The main challenge for the future is to further increase the power plant thermal efficiency independent of the type of power plant concept, i.e. fossil-fired or nuclear power plant, where the material selection can directly affect reduction of CO{sub 2} emissions. In power plant design, welding is the most applied manufacturing technique in component construction. The necessary weld heat input causes metallurgical changes and phase transitions in the heat affected zone (HAZ) of the base materials and in the deposited weld metal. The weld joint can absorb hydrogen during welding or in later service - This absorption can cause degradation of mechanical properties of the materials, and in certain loading conditions, hydrogen-assisted cold cracks can occur. This cracking phenomenon can appear time delayed due to the temperature dependency of the hydrogen diffusion and the presence of a ''critical'' hydrogen concentration. Additionally, each specific weld microstructure shows a certain hydrogen diffusion and solubility that contribute to susceptibility of the cracking phenomenon. Therefore hydrogen cannot be neglected as possible failure effect, which was identified recently in the case of T24 creep-resistant tube-to-tube weld joints. It is necessary to identify and assess the hydrogen effect in weld joints of low-alloyed steel grades for to improve further early detection of possible failures. For each specific weld joint microstructure, it is necessary to separate the interdependencies between mechanical load and the hydrogen concentration. The diffusivity and solubility must be considered to identify hydrogen quantities in the material at any given time. In this case, the effects of mechanical loading were dealt with independently. For the characterization of the mechanical properties, hydrogen charged tensile specimens were investigated for the base materials and thermally simulated HAZ microstructures. The hydrogen diffusion was characterized

  19. Hydrogen diffusion and effect on degradation in welded microstructures of creep-resistant low-alloyed steels

    International Nuclear Information System (INIS)

    Rhode, Michael

    2016-01-01

    The main challenge for the future is to further increase the power plant thermal efficiency independent of the type of power plant concept, i.e. fossil-fired or nuclear power plant, where the material selection can directly affect reduction of CO 2 emissions. In power plant design, welding is the most applied manufacturing technique in component construction. The necessary weld heat input causes metallurgical changes and phase transitions in the heat affected zone (HAZ) of the base materials and in the deposited weld metal. The weld joint can absorb hydrogen during welding or in later service - This absorption can cause degradation of mechanical properties of the materials, and in certain loading conditions, hydrogen-assisted cold cracks can occur. This cracking phenomenon can appear time delayed due to the temperature dependency of the hydrogen diffusion and the presence of a ''critical'' hydrogen concentration. Additionally, each specific weld microstructure shows a certain hydrogen diffusion and solubility that contribute to susceptibility of the cracking phenomenon. Therefore hydrogen cannot be neglected as possible failure effect, which was identified recently in the case of T24 creep-resistant tube-to-tube weld joints. It is necessary to identify and assess the hydrogen effect in weld joints of low-alloyed steel grades for to improve further early detection of possible failures. For each specific weld joint microstructure, it is necessary to separate the interdependencies between mechanical load and the hydrogen concentration. The diffusivity and solubility must be considered to identify hydrogen quantities in the material at any given time. In this case, the effects of mechanical loading were dealt with independently. For the characterization of the mechanical properties, hydrogen charged tensile specimens were investigated for the base materials and thermally simulated HAZ microstructures. The hydrogen diffusion was characterized with

  20. The role of alloy composition, environment and stresses for the oxidation resistance of modern 9% Cr steels for fossil power stations

    Directory of Open Access Journals (Sweden)

    M. Schütze

    2004-03-01

    Full Text Available In recent years a new group of ferritic-martensitic chromium steels for the use in fossil power stations has been developed with chromium contents between 9 and 12%. Typical representatives of these steels are P91, E911 and Nf616, which are nowadays widely used in the more advanced power plants. In the development phase the focus was on the mechanical properties of these steels but when taking them to practical operation conditions it turned out that much of the life-time of the materials and components is determined by their oxidation properties. Oxidation resistance is first of all a function of alloy composition. For the steels of this group it is chromium, silicon, manganese and molybdenum that decide their oxidation performance and since the contents especially of the four elements can be significantly different for the different steels there can be clear differences in oxidation behaviour. One of the most important issues from this point of view is how the concentrations of these elements change in the metal subsurface zone during operation/oxidation since if their level drops below a critical level oxidation resistance of the steels will be lost. In the work to be reported the influence of alloy composition and metal subsurface zone concentration as a function of oxidation time up to 10000 h was investigated in dry air and air up to 10% water vapour at 650 °C. The investigations comprised several of the advanced commercial 9% Cr steels including P91, E911, Nf616 and six laboratory melts of Nf616 with different amounts of silicon. As the results of the investigations show humidity, which is omnipresent in combustion environments, can dramatically accelerate oxidation. Silicon as an alloying element reduces the detrimental effect of water vapour significantly while molybdenum has a negative effect. The effects of the key alloying elements in these steels was quantified for conditions with and without water vapour in the environment